Radiology MRI

Tuber Cinereum Hamartoma

2012-02-02T09:49:00.000+01:00

MRI showing non-enhancing hypothalamic mass located between mammillary bodies and infundibulum at the tuber cinereum. Mass represents Tuber Cinereum Hamartoma, also known as Hypothalamic Hamartoma (HH). It is a non-neoplastic congenital gray matter heterotopia. It can be associated with characteristic gelastic seizures - laughing epilepsy. It is a classic case for all sort of radiology exams!

Proton Density in Multiple Sclerosis

2012-01-14T15:29:00.001+01:00

It is well known that Proton Density sequence is valuable in evaluation of Multiple Sclerosis (MS) plaques located under tentorium cerebelli. Proton Density (PD) - also known as second echo from T2 sequence, is something we get "for free" with normal T2. However compared to "pure T2" the "double echo T2" is somehow degraded in quality. But the price is worth to pay. Note this plaque laterally on the left side in the pons. It is much better depicted on this scan from 3T MRI compared to T2 and FLAIR. I like FLAIR (third image) as the most "sensitive" sequence for detection of plaques. However PD is "the king" under tentorium.

Also, do not forget the Sagittal T2 showing characteristic "Dawson Fingers" in the other MS patient. We use 3mm slice sequence covering corpus callosum and adjacent structures. I prefer it to volume (3D) sagittal FLAIR.

PML in HIV - Cerebellum

2011-12-23T14:00:00.001+01:00

HIV patient with poor immune status presents with gait disturbance and dysdiadochokinesia. MRI reveals asymmetric primary white matter changes mostly in the left cerebellum. Note high signal on T2 and FLAIR as well as some volume increase and discrete contrast enhancement. Radiological signs together with clinical status correspond with Progressive Multifocal Leukoencephalopathy (PML). Diagnosis is not easy since HIV patients can suffer from other opportunistic infections and lymphoma. Clue here is asymmetry, infratentorial location and patient's clinical status. (See Fig 18.16 MRI of Brain and Spine, S. W. Atlas, 4th, p 943). You might also check my previous PML cases: PML 1, PML 2.

Incisive Canal Cyst on CT

2011-11-30T14:32:00.001+01:00

Incidental, benign finding on CT showing cyst in the trajectory of the incisive canal representing Incisive Canal Cyst, aka Nasopalatine Duct Cyst. Clues here are well defined borders and location. Developmental anomaly.

Snus on CT

2011-11-30T10:16:00.001+01:00

Unfortunately it is very popular in Sweden to use small tobacco bags placed under the upper lip - locally known as Snus. When I saw for the first time a nice Swedish lady placing such tobacco bag under her lip during a meeting - I was shocked with disgust. Note snus bag under the lip as "incidental finding" on the above CT.

This case expands "my collection" of various objects found in patient's mouth.

You might check my previous: Chewing Gum on CT and Candy Under the Tongue on CT.

Broca's Infarct

2011-11-29T08:38:00.001+01:00

Patient presented with expressive dysphasia. MRI shows acute infarct in Broca's Area in the left inferior frontal gyrus that is responsible for speech production. Note high signal on DWI, low on corresponding ADC as well as signal changes on T2 and coronal FLAIR.

CSF Leakage Spine - MRI Protocol

2011-11-25T14:25:00.001+01:00

I have already mentioned CSF Leakage - Intracranial Hypotension and Intracranial Hypotension before. Here I would like to present a simple and effective MRI protocol to show the CSF leakage. The clue is to use heavy T2 weighted sequence with thin slice, good resolution and what is most important - fat saturation. We want to get rid of epidural fat. Note on the images above the epidural CSF dorsally to dural sack that extends from cervical to low thoracic level. Sagittal projections show extend of the leakage, while tranversal images show more detail anatomy. This investigation was performed on Siemens Trio Tim 3T machine with the same sequence in two projections:

- sag: t2_spc_sag_p3_iso_384_myelo
Nex 2
Slice 0.8 mm
TR: 1500
TE: 224
Flip angle: 110

- tra: t2_spc_tra_p2_iso_320_myelo
Nex 2
Slice 1 mm
TR: 1500
TE: 224
Flip angle: 110

For the location of the tranversal sections it is wise to ask your technicians to request radiologist supervision. It is also useful to make coronal reconstructions from the sagittal sequences as well as rotating MIP reconstructions. The exact place of leakage is often difficult to visualize.

Above images of the brain from the the same patient showing fresh bilateral subdural hematomas and sagging of the midbrain. Note the low position of mesencephalon and pituitary stalk.

Tuberous Sclerosis

2011-11-22T11:17:00.001+01:00

This case shows typical findings in a patient with Tuberous Sclerosis. Note cortical and subcortical tubers on transversal T2 and coronal FLAIR as well as contrast enhancing Giant Cell Astrocytoma in the left foramen Monroe region.

Also note subependymal nodules that are both calcified (see CT and T2 GRE) and showing contrast enhancement (arrowheads). Above findings can present with variable expression in different patients.

Sturge Weber CT

2011-10-31T09:51:00.001+01:00

Non-contrast CT showing cortical calcifications and atrophy in the left occipital lobe in a patient with Sturge-Weber Syndrome. Due to leptomeningeal angiomatous venous plexus there are dystrophic cortical changes. In microscopy study those patients have a plexus of multiple small thin-walled telangiectatic capillaries or venules in the subarachnoid space between pia and arachnoid membranes. Diminished venous cortical draining causes cortical atrophy that can be seen on the second and third image. Cortical calcifications have "tram-track" pattern - see arrows fourth image. There is no significant contrast enhancement (not shown). Also enlarged ipsilateral sinuses are part of the intracranial findings - see FS on the first image.

Lateral Medullary Infarct - Wallenberg

2011-10-19T10:11:00.001+02:00

Diffusion Weighted Imaging (DWI) is showing acute infarct lateral in medulla oblongata on the right side (arrows). Note high signal on DWI, low on ADC and high on T2. This represents clinically Wallenberg Syndrome that is associated with Lateral Medullary Infarct. Infarct is due to occlusion of Posterior Inferior Cerebellar Artery (PICA). In this case the infarct is rather large, but sometimes it can be quite small. So look carefully.

See also my previous post with same type of infarct:
Wallenberg Syndrome - Lateral Medullary Syndrome
You may also check this article:
Jong S. Kim - Pure lateral medullary infarction: clinical–radiological correlation of 130 acute, consecutive patients

Quiz T2 sag

2011-09-27T13:27:00.001+02:00

Quick radiology Quiz. What can be seen on this sagittal T2 sequence?

A. Normal
B. Congenital anomaly
C. MS
D. Do not know, images move too fast!

Of course you don't have to answer this quiz. Only remember to include this sequence when trying to diagnose patients with this specific clinical question.

Aneurysm of Persistent Trigeminal Artery

2011-09-27T11:42:00.001+02:00

CTA showing large aneurysm at the dorsal upper part of the right Internal Carotid Artery (arrow). There is also an anatomic variant in form of a Persistent Trigeminal Artery (PTA) on the left side which is also showing an aneurysm in its anterior medial part (arrowhead). Note hypoplastic Basilar Artery (long arrow), as another anatomic variant. There are reports in the literature of aneurysms accompanying PTA. This was an incidental finding.

Note same findings on the 3D volume reconstructions. (Images are mirrored L-R).

Same 3D reconstructions from anterior angle. In this case aneurysms are obvious and easy to find. However it is good to be sure to look for aneurysms in case of this anatomic variant.
You might also check my previous post about Persistent Trigeminal Artery.
Also, if you like anatomic variants, there is a case of Persistent Hypoglossal Artery.

Fishbone in Larynx

2011-09-19T15:59:00.001+02:00

Unenhanced CT showing large (about 30mm) fishbone dorsally in the larynx. It is located supraglottic. Its oblique trajectory can be seen in the coronary plane. Hyperdense opacity of the fishbone allows for good depiction with CT. There is also surrounding edema around this foreign body. Initial laryngoscopy failed to reveal the fishbone as it was deeply sunk in soft tissues.

Schizencephaly Closed-Lip

2011-09-14T15:54:00.002+02:00

T2 and IR images showing Closed-Lip Schizencephaly in this two weeks old neonate located in the inferior parietal lobule region. Note that in this type of Schizencephaly cortex is covering the most medial parts of the cleft and there is no connection with the side ventricle.

MCA Territory

2011-09-13T09:17:00.001+02:00

Unenhanced CT showing tissue loss after Middle Cerebral Artery MCA infarct involving whole territory of MCA. Note sparring of occipital lobe as well as medial temporal lobe - that belong to Posterior Cerebral Artery PCA territory. Also note medial parts of the frontal lobe that belong to Anterior Cerebral Artery ACA.

Above unenhanced CT from the investigation three months prior at acute stage of infarct showing "Dense Vessel Sign" indicating occlusion of the main M1 segment of the MCA on the left side.

CT Perfusion study at the time of acute infarct showing: increased Mean Transit Time MTT, decreased Blood Volume BV and decreased Blood Flow BF. Especially the decreased BF - represented by dark blue in the last image indicates infarct that can not be saved. Remember: "Blue is Bad" in CT Perfusion.

Hot Cross Bun - MSA

2011-09-11T15:16:00.002+02:00

Note high signal intensity configuration in the pons that resembles a cross, or as some see it a Hot Cross Bun. This is a sign of MSA - Multiple System Atrophy. In this case MSA-c variant that involves mainly infratentorial structures. Note extensive atrophy in pons and cerebellum.

Above image shows a Hot Cross Bun example - image courtesy of Bakery Jasiek.

Glioblastoma

2011-09-08T14:30:00.001+02:00

T1 sequences showing contrast enhancing aggressive looking tumor in the dorsal parts of the right frontal lobe with extensive edema (last image - FLAIR). Pathology examination revealed Glioblastoma. It is a highly aggressive tumor with poor prognosis. Follow-up revealed recurrence of tumor despite resection, radiotherapy and chemotherapy.

One subjective note concerning this case.
When I see young patients (40 yrs) with such aggressive tumor I can not stop thinking about all the people I see around me talking on their GSM phones. There has not been, as far as I know, proven correlation between tumor occurrence and extensive use of GSM. And I even do not know if this patient was using handheld phone extensively. There are many theories, among other concerning genetic predisposition and external "vectors" that can stimulate growth of such tumors. But why not "stay on the safe side" and limit lengthy telephone conversations with handheld device. Modern phones mostly have antennas in the region where we hold them in our hands - as far away from the brain as possible. But the older ones had antennas radiating exactly in the region where this tumor occurred. So my teaching point from this case is - use headphones with microphone (not blue-tooth - as this is radiation as well only less) and hold the GSM in your hand whenever possible - just to "be on the safe side".

Pneumoparotid

2011-08-18T10:20:00.000+02:00

Incidental finding on a trauma CT scan showing air in ducts of the right parotid gland. Note also air in the main parotid duct. This is known as Pneumoparotid. It is caused by periodic increased air pressure in the oral cavity. It can be seen in people playing wind instruments, after dental procedures, coughing and other activities involving forceful exhalation.

Titanium Mesh

2011-08-17T16:08:00.000+02:00

Surface renderings of the CT showing Titanium Mesh used in cranioplasty to cover extensive defect in the right temporal bone. Defect was due to craniectomy after intracranial hemorrhage following trauma. Also note old zygomatic bone fractures.

Thalamic Infarct

2011-08-17T11:09:00.000+02:00

First image shows Acute Lacunar Thalamic Infarct on the right side with corresponding second image showing prior study 11 hours before, that also depicts acute infarction.

CTA shows occlusion of the P1 segment of the right Posterior Cerebral Artery (arrows). You can also (with some difficulty) depict a thromb in this segment (arrowheads).

Lacunar Thalamic Infarcts are quite common and often accompanied with Posterior Cerebral Artery territory infarcts. In fact PCA infarcts are detected more often. However isolated thalamic infarcts are also seen. The clue here is vascular supply to the thalami. It comes mainly from P1 and P2 segments of the Posterior Cerebral Arteries. Therefore radiologists and neurologists should pay attention to posterior circulation in case of suspected or detected thalamic infarcts. Patients with such infarcts present with specific neurologic findings.

Excellent review of vascular supply can be found in the following articles:
Jeremy D. Schmahmann - Vascular Syndromes of the Thalamus
Young-Mok Song - Topographic patterns of thalamic infarcts in association with stroke syndromes and aetiologies

You can also check my previous post showing examples of thalamic and PCA infarcts on MRI
Diffusion Weighted Imaging - MRI

Gadolinium Guidelines

2011-08-15T14:25:00.000+02:00

T1 with iv Gadolinium and T2 showing non-enhancing, pathology verified Astrocytoma grade 2 in the medial parts of the left temporal lobe. Note distortion of the brain architecture.

However subject of this post concerns Gadolinium Guidelines in attention to Nephrogenic Systemic Fibrosis. Here is the summary:

Gadolinium Guidelines

- eGFR 60 or greater - OK
- eGFR 30-59 - weight-based dose of GBCA (0.2 mL/kg) can be administered with maximal dose of 20 mL allowed within 24 hours
- eGFR less than 30 - GBCA cannot be administered except in cases of medical necessity; informed consent required; nephrology consultation required; hemodialysis should be considered

According to:
Yingbing Wang - Incidence of Nephrogenic Systemic Fibrosis after Adoption of Restrictive Gadolinium-based Contrast Agent Guidelines

MoyaMoya Child

2011-07-27T14:22:00.000+02:00

Three years old child that suffered from a major infarct at the age of 7 months. MRI of the brain shows large porencephaly of the left hemisphere with compensatory larger right hemisphere corresponding with "age" of the infarct. Note thickness of the bone on second image. But why would a 7 months old child suffer from such extensive infarction? There are some clues when you look at the vessels of the Circle of Willis. Note tapering (progressively narrowing) of the distal Internal Carotid Arteries (ICA). Also you might notice extensive small collateral vessels centrally in the brain (mostly lenticulostriate). This is a case of MoyaMoya disease that is also known as Idiopathic Progressive Arteriopathy of Childhood.

Above images show source and reconstructions of the flow based Time of Flight (ToF) MR Angiography (MRA). You can see tapering of the distal ICA (arrows) as well as multiple small collateral arteries (arrow heads). Those collaterals would show as "puff of smoke" cloud on the conventional angiography. This gives a name - MoyaMoya in Japanese. You might also check my previous case of MoyaMoya in adult.

External Auditory Canal Fracture

2011-07-26T09:54:00.000+02:00

Fall on mandible with blood from both external auditory canals. CT shows bilateral comminute fracture of the bony parts of external auditory canals (arrows). Fractures are not apparent at first glance, however clue here is emphysema - air in soft tissues medially to mandibular condyles (arrow heads). Mechanism of this trauma is impact of mandibular condyles against anterior parts of the bony external auditory canals. Lesson here is to look carefully at any abnormal air in soft tissues of trauma patients and ask yourself a question: Where does this air come from?

AVM and Hiccup

2011-07-21T13:41:00.000+02:00

Patient presents with persistent hiccup since about a week. CT of the brain followed by CT Angiography (CTA) (not shown) revealed a large Arterio Venous Malformation (AVM) located dorsally to medulla oblongata and extending into the proximal spinal canal. Additional MRI investigation (above) has revealed a large thrombosed part of AVM that was not apparent on CT. Note two first images showing non-contrast T1 followed by two images after contrast. There is a large branch of the AVM stretching through the right foramen of Luschka (arrows) that shows high signal on non-contrast T1. The contrast enhanced T1 sequences show enhancement of the remaining parts of the AVM located posteriorly to medulla oblongata (arrowheads). High signal on non-enhanced T1 of the thrombus is due to free methemoglobin indicating about one week old thrombus. (Check my previous post about blood product signal on MRI). This corresponds with onset of patients symptoms - since the AVM was "silent" and already in place before.

Also note on images above restricted diffusion from the thrombus seen on DWI. As usually first image is DWI (ep_b100t) then ADC (ep_b0_100) and T2 (ep_b0). Note high signal on DWI and low on ADC of this late subacute thrombus. Next stage in diagnostic imaging and therapy is conventional angiography.
Lesson from this case is that MRI is supplementary in diagnosis of intracranial AVMs and that it is very important to look at non-enhanced T1 since thromb can look just like patent AVM after contrast administration.

What concerns hiccups, let me quote an interesting article:

"Hiccup, nausea, and vomiting are thought to be caused by the lesions involving the dorsomedial medulla including the Area Postrema (AP) and Nucleus Tractus Solitarius (NTS), and the ventrolateral respiratory center (VRC) such as the nucleus ambiguus, although the neural network and its pathophysiologic relation to the symptoms in humans has not been fully understood." - Intractable hiccup and nausea with periaqueductal lesions in neuromyelitis optica - T. Mitsu
Neurology November 8, 2005 65:1479-1482

Cavum Velum Interpositum on MRI

2011-07-06T14:15:00.002+02:00

Incidental finding of Cavum Velum Interpositum (CVI) that is seen as triangular shaped CSF space between lateral ventricles, over thalami, below fornices.

CVI is most posteriorly located - that is contrary to anterior and middle location of Cavum Septi Pellucidi (CSP) and Cavum Vergae (CV) as shown on this very good scheme from Wikipedia.

You might also check my previous post showing Cavum Velum Interpositum on CT.

Hypothalamic Lipoma

2011-07-04T14:33:00.000+02:00

Not enhanced and contrast enhanced T1 sequences showing high signal well defined lesion dorsally to pituitary infundibulum and anterior to corpora mammillaria, caudally to hypothalamus. Lesion shows no contrast enhancement and its signal characteristics are of fat tissue. This is an incidental finding of Hypothalamic Lipoma.

Note the lesion location on non enhanced T1, contrast enhanced T1, T2 and FLAIR (with fat saturation - see subcutaneous tissue).

Also CT confirms fat tissue. The learning point is that in the hypothalamus region one can encounter various types of lesions. In this case the first next differential diagnosis would be Craniopharyngioma, or Germinoma. However lack of enhancement proves against the malign tumor. Always check for possible ectopic neurohypophysis, that in this case is in normal position (see first image). Tuber Cinereum Hamartoma - that can be found in this location has different signal characteristics.
For further reading about this region check Radiology of the Pituitary.

Intraventricular Meningioma

2011-05-31T10:37:00.000+02:00

Well defined solid mass located in the trigonum of the left lateral ventricle. Mass is hyperdense (to brain parenchyma) and contains calcifications as seen on unenhanced CT. It enhances homogeneously after contrast and is well demarcated. There is some edema of the adjacent brain tissue. This is a case of Intraventricular Meningioma. Only about 2% of meningiomas are intraventricular, without dural attachment. Those arise from choroid plexus stromal cells. No MRI in this case due to pacemaker.

Tail of Caudate Nucleus Infarct

2011-05-25T15:17:00.000+02:00

Another case of selective infarct. Here is an isolated infarct in the distal portion of the Tail of Caudate Nucleus. Note high signal on DWI and low on corresponding ADC. Images from 1.5T scanner.

On the second and third (FLAIR) image you can see high signal of the infarcted tail of caudate nucleus that is extending to the amygdala. It is also showing edema on T2 image. Such isolated infarct is in the territory of the Lateral Posterior Choroid Arteries (LPCAs) that originate from the distal Posterior Cerebral Artery (PCA) trunk. With modern imaging we see more of such selective infarcts. Neurological correlation is very interesting in such cases. This one is not easy to find in the literature.

You might also check short article: Isolated infarction in the territory of lateral posterior choroidal arteries.
As well as my previous post about Anterior Choroidal Artery Infarct.

Enlarged Parietal Foramina

2011-05-20T14:54:00.000+02:00

Note symmetric well defined large foramina in both parietal bones representing Enlarged Parietal Foramina. Finding is known to be associated with genetic defect that influences cranial maturation. In some patients it can be associated with structural brain anomalies.

Above image showing Normal Parietal Foramina - for comparison.

You might also find some further details at Genetics Home Reference - Enlarged Parietal Foramina.

PML - Progressive Multifocal Leukoencephalopathy

2011-05-18T15:07:00.000+02:00

Immunocompromised patient after bone marrow transplant with progressively deteriorating neurological symptoms. MRI investigations show within two weeks progressive diffuse white matter changes that did not enhance and initially shown some degree of diffusion restriction. Laboratory study of the Cerebro Spinal Fluid (CSF) has proven JC virus markers. This is a case of Progressive Multifocal Leukoencephalopathy (PML) that is caused by JC virus infecting oligodendrocytes and causing rapidly progressive demyelination in immunocompromised patients. It characteristically involves subcortical U-fibers. See frontal lobe on the transversal T2.
It is also known to affect Multiple Sclerosis (MS) patients treated with Natalizumab (Tysabri). Therefore we often screen our MS patients receiving Tysabri and developing neurological symptoms for possible PML.
Radiologically it is not an easy diagnose. Look at progressive confluent non-enhancing white matter changes that have predilection to subcortical regions but also in basal ganglia and infratentorial.
You might also check my previous case of Progressive Multifocal Leukoencephalopathy - PML.

Pontine Cavernoma

2011-05-18T11:09:00.001+02:00

Patient with known Cavernous Malformation (Cavernoma) in the pons presents with early subacute hemorrhage. Note high signal on non-enhanced sagittal T1, central and peripheral low signal on coronal FLAIR as well as high signal centrally and low peripheral on transversal Susceptibility Weighted Image (SWI). Transversal T2 shows low signal centrally and low peripheral. This represents early subacute hemorrhage with Methemoglobin in Red Blood Cells (RBCs) and deposits of Hemosiderin in the periphery of the Cavernoma. Also note mass effect on the fourth ventricle. Images from 3 Tesla (3T) MRI.
Learning points here are typical location of the Cavernous Malformation in the Pons as well as MRI signal characteristics of the early subacute hemorrhage.
You might also check my previous post on Intracranial Hemorrhage on MRI.

Anterior Choroidal Artery Infarct

2011-05-17T15:17:00.004+02:00

Non-enhanced CT showing hypodense region with local edema involving basal parts of the left temporal lobe including parahippocampal gyrus. This most likely represents selective subacute infarct in the Anterior Choroidal Artery (AChA) branch. AChA originates from Internal Carotid Artery just above the Posterior Communicating Artery (PCom). It usually supplies choroid plexus, optic tracts, temporal horn, cerebral peduncle, part of thalamus and posterior limb of internal capsule. There are also Lateral and Middle Posterior Choroidal Arteries that originate form the P2 segment of the Posterior Cerebral Artery (PCA) and provide complimentary blood supply. Those vascular territories although with many anatomical variants are important in differentiating such selective stroke from other pathologies such as for example Herpes Encephalitis that has predilection for the limbic system.

Congenital Cytomegalovirus Infection

2011-05-04T14:18:00.000+02:00

Four weeks old neonate with biopsy proven Cytomegalovirus (CMV) hepatitis was investigated with MRI of the brain due to altered neurologic status. T2* GRE Gradient Echo image shows multiple small black dots bilateral periventricular that represent multiple small calcifications. FLAIR shows extensive diffuse signal abnormalities in the white matter. Transversal T2 TSE shows calcifications round occipital horn of the left lateral ventricle. Coronal T1 shows high signal intensity small dots infratentorial that also represent small calcifications. (Yes - calcifications can show as high signal on T1). Periventricular distribution of calcifications is characteristic for Congenital Cytomegalovirus (CMV) Infection. Those would be even better visible on CT and even on Ultrasound.

However MRI shows further characteristic findings. Note pathological structure of the gyri on the parasagittal and transversal T2 images corresponding with dysplastic cortex - polymicrogyria. Also note on the sagittal T2 and T1 images a hypoplastic thin corpus callosum as well as large cisterna magna.

Acute MCA Infarct on CT

2011-05-02T10:30:00.002+02:00

First image shows Acute Middle Cerebral Artery (MCA) Infarct. It is only seen as diminished size of the sulci, diminished grey-white matter differentiation, as well as reduced delineation of the putamen and external capsule - when compared with normal left side. Second image 19 hours later shows well defined large MCA infarct with clear swelling of the ischemic brain tissue.
Cases like this are a real challenge for radiologist.

You might also check my previous cases:
Acute MCA Infarct
Media Infarct - CT Perfusion

Chewing Gum on CT

2011-05-02T09:17:00.000+02:00

On the light side of radiology imaging one can notice a chewing gum located above the tongue on this unenhanced CT. Rather easy "diagnosis" however worth recognition as in some cases such foreign bodies can be confusing.
See also my previous post about the candy: Candy Under the Tongue on CT.

Septooptic Dysplasia

2011-04-28T11:49:00.000+02:00

Coronal T2 showing absent septum pellucidum with characteristic configuration of frontal horns. Also note very thin optic chiasm (arrows). Thin corpus callosum and low fornices. Optic nerves are hypoplastic (not shown). Pituitary has normal appearance in this case. This is a case of Septooptic Dysplasia that is also known as De Morsier Syndrome.

Aqueduct Stenosis

2011-04-26T15:43:00.000+02:00

44 years old with clinical symptoms indicating hydrocephalus. CT (not shown) confirmed diagnosis of hydrocephalus. However the question was if this was a Normal Pressure Hydrocephalus or Aqueduct Stenosis? MRI performed on 3T using special thin slice T2 (volume) sequences shows increased flow through foramina of Monroe (arrowhead) as well as Magendie with at the same time no visible flow artifacts in the cerebral aqueduct. Further detail inspection of the aqueduct reveals a thin membrane (arrows) that is responsible for the Aqueduct Stenosis. Also note flattened hypophysis due to bulging of the suprasellar cistern. Increased supratentorial ventricles and stretching of corpus callosum. There is also increased flow in the prepontine cistern that might indicate spontaneous connection between floor of the third ventricle and the interpeduncular cistern. Most likely neurosurgical therapy would be to endoscopically create connection at this place (ventriculocisternostomy).

Chronic Subdural Hematomas - MRI

2011-04-19T15:55:00.000+02:00

Note nicely depicted compartmental anatomy of the bilateral frontal Chronic Subdural Hematomas. Subdural space being only a potential anatomic compartment and only visible in case of such fluid collections. Note especially on FLAIR the high signal of fluid collections that is due to high protein content. Also observe the normal subarachnoid space (black - CSF signal) that follows sulci.

Fig 769 by Henry Gray from Bartleby.com

You can also check my older post: Chronic Subdural Hematoma

Open Access Radiology Articles

2011-04-19T14:08:00.001+02:00

I must admit that I am a strong supporter of open access medical literature. My academic hospital provides doctors with access to subscribed articles from our workstations. Growing number of medical publishers switches from paper to digital only distribution. This is much more efficient in terms of searching for information, storing, as well as more environment friendly. With growing choice of electronic reading devices (PCs, notebooks, tablets, smartphones) it is even more easy and common to read medical literature in electronic form. However the way of accessing articles through hospital computer is still far from optimal. It happens to me that I struggle with a difficult case and find an interesting article in PubMed that I can not open since the article is restricted by publisher and my hospital has no subscription. Yes I am offered a 30$! per article purchase, and yes I can order this article through my library - but I need this information now! What is more interesting is that authors of medical articles are not paid for their articles and thus would welcome when articles are more open to the public. But the publishers put high pay-walls. I understand that publishers need revenue for peer reviews and other administrative costs. But there are ways to cut those costs like publish online and perhaps get sponsors or adopt Apple pay system - of low costs but high volume of sells. In such situation I welcome kind initiatives of Open Access Medical Articles. Below is a selection of some interesting recent Neuroradiology articles from AJNR.

Y.W. Lui - Sphenoid Masses in Children: Radiologic Differential Diagnosis with Pathologic Correlation
AJNR Am J Neuroradiol 2011;32 617-626

G. Zuccoli - Redefining the Guillain-Barre´ Spectrum in Children: Neuroimaging Findings of Cranial Nerve Involvement
AJNR Am J Neuroradiol 2011;32 639-642

M. Eapen - Using High-Resolution MR Imaging at 7T to Evaluate the Anatomy of the Midbrain Dopaminergic System
AJNR Am J Neuroradiol 2011;32 688-694

Alcohol Related Upper Vermis Atrophy

2011-04-14T14:23:00.000+02:00

50 years old male with known chronic alcohol abuse. CT showing marked atrophy in the upper vermis. This is a common finding in chronic alcohol abuse. However pay attention when examining the vermis in the sagittal plane as in the midline its appearance might be misleading and mimic atrophy. Therefore examine vermis in parasagittal as well as coronal and axial planes for definite diagnosis.

Rathke Cleft Cyst

2011-04-05T15:35:00.003+02:00

Note large cystic intrasellar lesion. Enhancing expanded pituitary gland tissue surrounds the cyst. This is called "claw sign" - seen near the pituitary infundibulum. Note that the wall of the cystic lesion is smooth. There are no signs of calcifications. Fluid inside the cyst is homogeneous. Differential diagnosis to Rathke Clef Cyst are: Cystic Adenoma and Craniopharyngioma.

See interesting article concerning differential diagnosis:
S.H Choi - Pituitary adenoma, craniopharyngioma, and Rathke cleft cyst involving both intrasellar and suprasellar regions: differentiation using MRI

MRI - Metal Screening

2011-04-04T13:24:00.000+02:00

Before every MRI we screen our patients for possible metal foreign bodies. Those can be implanted due to prior medical procedures as well as accidental. One of the specific inquiry concerns possible metal foreign bodies in the orbit. Sometimes patients work with metal and indicate possibility of being exposed to small projectile metal particles. In such case we check prior CT examinations for possible metal foreign bodies. Note above case of a small piece of metal located medially and superiorly in the left orbit. Here metal seems not to be attached to the globe. However due to risk of metal motion in strong magnetic field of the MRI scanner in a case like this we ask for ophthalmologist consultation. One should review scanogram as well as thin slices of the CT - considering size of foreign body and slice thickness. In case we do not have prior CT we order x-ray of the orbits.

CSF Leakage - Intracranial Hypotension

2011-03-29T10:47:00.002+02:00

Young woman two weeks after partus followed by spinal pain and stiffness in the neck. Sagittal T2 and contrast enhanced T1 show: sagging of the midbrain as well as cerebellar tonsils, enlarged dural sinuses and hypophysis, steep tentorium.

Axial contrast enhanced T1 showing increased dural enhancement and slightly increased subarachnoidal space seen on coronal T2. (BTW: Also note nicely depicted corticospinal tracts on the coronal T2.)

Coronal contrast enhanced T1 shows increased dural enhancement as well as sagging of the cerebellar tonsils. Findings strongly suggest Intracranial Hypotension as a consequence of the reduced Cerebro Spinal Fluid (CSF) pressure due to possible CSF leakage associated with lumbar puncture (LP). Differential diagnosis are: 'normal' dural enhancement after LP, as well as meningitis. However meningitis tends to show more subarachnoidal than dural enhancement.
See also other case of Intracranial Hypotension from my blog.

Optic Nerve Sheath Meningioma

2011-03-25T15:03:00.000+01:00

Contrast enhanced CT showing well defined, homogeneous intra orbital tumor. There is relation of the tumor with optic sheath and rather deep location in the orbital apex. This is most likely an Optic Nerve Sheath Meningioma.

Just Looking!

2011-03-22T13:59:00.000+01:00

Amusing T2 slice from 3T MRI scanner showing right sided fixed position of the lenses. Perhaps our patient saw something interesting in the scanner? :) For more fun radiology images check older posts in Fun label.

Hemorrhagic Choroid Plexus Cyst

2011-03-17T14:00:00.002+01:00

Transversal Diffusion Weighted sequence shows high signal in the left choroid plexus with corresponding low signal on ADC (restricted diffusion). Finding represents acute Hemorrhagic Choroid Plexus Cyst. It is also known as Choroid Plexus Xanthogranuloma. Gradient Echo sequence (third image) shows low signal in the right choroid plexus representing hemosiderine deposits after previous hemorrhage. Coronal T1 shows intermediate to high signal in the plexus cyst.

Note also low signal in the right plexus on T2 (old hemorrhage) and high signal on FLAIR in the left plexus (acute hemorrhage).
Choroid Plexus Cysts are very common normal finding. Those often show restricted diffusion. However in our case of patient with hypertension this finding is of interest to the clinicians as a requirement to more closely monitor patient's blood pressure. There were no signs of intraventricular hemorrhage.

AV Hemodialysis Shunt Thrombosis

2011-03-04T10:49:00.001+01:00

CTA (Computed Tomography Angiography) showing nice 3D rendering of the AV Hemodialysis Shunt Thrombosis (purple) in the cephalic vein with dilatation of the distal part of the cephalic vein. The Arterio-Venous shunt is open.

Source images of the same investigation show that there is partially blood flow around thrombus and dilated distal part of the cephalic vein.
Important note: CTA is not the investigation of choice for the suspected hemodialysis shunt thrombosis - Color Doppler Ultrasound is the investigation that should be performed first. This case was investigated in order to provide surgeon with anatomic topography of the anastomosis and in this way replacing angiography.

Struma

2011-03-03T16:05:00.000+01:00

3D rendering of the CT Angiography showing nicely a large struma displacing trachea without deforming trachea lumen. Eye Candy.

Epidermoid Cyst

2011-03-02T09:22:00.000+01:00

Note high signal on DWI of this cystic process in the left cerebellopontine angle. This is Epidermoid Cyst showing lobulated contour and mass effect on brainstem. On ADC signal resembles brain parenchyma. It shows slightly decreased signal on T2 and no contrast enhancement.

Sagittal T1 and coronal FLAIR show signal of Epidermoid to be slightly higher than CSF.
Somehow it resembles signal characteristics of Cholesteatoma that is also keratin based cystic inclusion process.

Tectal Glioma

2011-02-18T13:46:00.001+01:00

7 years old child presents with headaches and vomiting since a few weeks. MRI: transversal T2, FLAIR, sagittal T2 - show poorly delineated tumor in the quadrigeminal plate that has high signal on T2 sequences. There was no contrast enhancement (not shown). This brainstem tumor compromises cerebral aqueduct causing supratentorial obstructive hydrocephalus. Radiologic appearance of this tumor strongly suggest Tectal Glioma. Those are commonly slow growing usually benign tumors that mostly require follow up. However hydrocephalus is of concern and often requires shunting.

Incidental Meningioma

2011-02-14T13:44:00.001+01:00

Incidental Meningioma found on Non Contrast CT (NCCT) scan of a patient after a small trauma. Note that this extraaxial tumor is rather difficult to detect on NCCT.

Measured density of Meningioma is just slightly hyperdense to adjacent normal brain parenchyma on NCCT. This makes Meningiomas sometimes difficult to detect.

After iv contrast is given Meningioma shows typical homogeneous intensive contrast enhancement. This is our standard C35 W70 brain CT window.

However note that tumor delineation is much better on a broader CT window with higher center value of C50 W150. This setting is also useful for detection of hemorrhage and pathology in the skull base region, especially after iv contrast.

Neonatal Intraventricular Hemorrhage

2011-02-03T14:39:00.000+01:00

MRI of this 4 days old neonate showing extensive early subacute Intraventricular Hemorrhage in the left lateral ventricle. Hemorrhage is showing as low signal on T2 TSE and high signal on T1 IR and T1 SE sequences. See discussion about Intracranial Hemorrhage on MRI in my previous post. Note also signal changes and swelling of the left nucleus caudatus. This is most likely due to venous hemorrhagic infarcts.

Myxoma

2011-02-03T11:19:00.001+01:00

CT Pulmonary Angiography (CTPA) showing large mass in the left atrium extending through the mitral valve into the left ventricle. Pathology verified Myxoma. Note timing of the scan being precisely adjusted to show pulmonary arteries (most contrast) since primary question was pulmonary embolism.

Anterior Commissure

2011-02-02T14:48:00.000+01:00

Why I like Anterior Commissure? It is a horizontal stripe of tissue connecting hemispheres that is located below frontal horns and anterior and superior to the third ventricle.

It is very thin in antero-posterior dimension and very distinct on coronal images. Above two coronal 1.4mm thick T1 contrast enhanced images look identical but are from different examinations of the same patient. Anterior Commissure is helpful in synchronizing those two sequences for comparison e.g. in tumor growth.

I also love anatomy drawings. The above is Figure 744 from Henry Gray (1825–1861). Anatomy of the Human Body. 1918. Courtesy Bartleby.com

Subdural Hematomas

2011-02-01T11:00:00.001+01:00

Large bilateral subacute Subdural Hematomas (SDHs). Note gradual change in density from anterior to posterior due to sedimentation of red blood cells.

Monkey Looking at Cerebellum

2011-01-19T10:57:00.001+01:00

When looking at the contents of the Internal Acoustic Canal it always reminds me of a face of the "Monkey Looking at Cerebellum". So I developed a simple way to remember its contents. Note the position of the oblique sagittal T2 slice that is indicated on the topogram and its angle that is shown on the right. You recognize cerebellum easily on the left image.

Long arrow on the first image shows Vestibular Nerve entering Internal Acoustic Meatus. Oblique sagittal T2 sequence through the Internal Acoustic Canal showing it's contents:
02:00 - Superior Vestibular Nerve
04:00 - Inferior Vestibular Nerve
08:00 - Cochlear Nerve
10:00 - Facial Nerve.
In other words the "mouth" of our "monkey" has a V letter shape since it is a "smiling monkey" and V represents Vestibular Nerve (Superior and Inferior). The upper "eye" is the Facial Nerve and the lower "eye" is the Cochlear Nerve. We can follow the Cochlear Nerve to the Cochlea.

Le Fort Type 1 Fracture

2011-01-18T16:01:00.004+01:00

Note horizontal fracture Le Fort Type 1 involving maxillary sinus walls bilateraly. This type of the fracture causes instability of the alveolar process of the maxilla.

Note fractured maxillary sinus walls, pterygoid process, blood levels in both maxillary sinus and extensive soft tissue emphysema.
Le Fort fractures are divided in levels: Type 1 - below nose, Type 2 - above nose, Type 3 - through the orbits.

Above schema is from Wikipedia that nicely presents types of Le Fort fractures.

CT Radiation Dose Report

2011-01-18T11:22:00.001+01:00

This is a standard radiation dose report generated by GE LightSpeed 64-slice CT scanner. This is a report of the CT Angiography including native CT Brain scan followed by CT Angiography of the Head and Neck. Values presented in this report are: CTDI - CT Dose Index and DLP - Dose Length Product. Some physics:
The CTDI represents the radiation dose of a single CT slice and is determined using acrylic phantoms. The weighted CTDI (CTDIw) reflects the weighted sum of two thirds peripheral dose and one third central dose in a 100-mm range in acrylic phantoms. The volume CTDI (CTDIvol), defined as CTDIw divided by the beam pitch factor, is the most commonly cited index for modern MDCT equipment. The dose length product (DLP) is the CTDIvol multiplied by the scan length (slice thickness × number of slices) in centimeters.
DLP is independent of what is being scanned. So it is the same for a little child as for a large adult. It is possible, but difficult, to estimate the effective dose equivalent using some conversion factors. If we would like to determine a more accurate effective dose equivalent then individual organ doses would have to be determined. The effective dose equivalent is the sum of the product of organ doses (in mGy or cGy, the magnitude of CT organ doses) multiplied by a corresponding weighting factor. The effective dose represents a total body dose. For regional exposures, the effective dose equivalent is the equivalent dose to the whole body, for example, approximately 2.0 to 3.0 mSv for a head CT.
So the DLP method of estimating dose offers only approximation of the radiation that patient receives.
My conclusion from above is: Include the report in your evaluation and check for the Total Exam DLP. Be aware of the radiation expose values for specific exams. I wish in the future such values would be included as standard information on CT reports.

Cerebral Venous Sinus Thrombosis

2011-01-14T11:08:00.001+01:00

Native CT (without contrast) shows increased density in the right sigmoid sinus and transverse sinus. Those are not characteristic findings since also high RBC count can cause hyperdense sinus. However in this case note difference in density when compared with the normal left side. This is a sign that should raise suspicion of Cerebral Venous Sinus Thrombosis.

Finding of Cerebral Venous Sinus Thrombosis is confirmed with CT Cerebral Venography that is performed 45 seconds after contrast injection. Above images show lack of contrast in the right sigmoid sinus (arrows) that is known as "empty delta sign". Also note large thrombus in the right transverse sinus (arrow heads). The "empty delta sign" mostly refers to lack of contrast in the confluence of sinuses but in this case it is the same principle and same empty delta in the sigmoid sinus.
Most important take home message is to adjust the window and level on the native series and compare both sides for any asymmetry. In case of clinical suspect Cerebral Venous Sinus Thrombosis include CT Cerebral Venography in your investigation.

Occipital Dural Arteriovenous Fistula

2011-01-07T10:31:00.002+01:00

Patient resents with left sided pulsatile tinnitus. CTA reveals pathologically increased arterial circulation of the Occipital Artery and Posterior Auricular Artery branches (arrows). Also noted is arterial contrast intensity in the left Sigmoid Sinus and Internal Jugular Vein (arrowheads). Finding is consistent with Dural Arteriovenous Fistula (DAVF) from the Occipital Artery circulation.

Note increased size and number of the branches from the Occipital Artery circulation.

Intracranial Hemorrhage on MRI

2010-12-23T10:53:00.003+01:00

Case of a 2 days old neonate with bilateral subdural hematomas, mainly infratentorial. Note high signal on the coronal T1, low on GRE, high signal with level on T2 and same level on T1 sequences. Signal characteristics represent early subacute hematomas with methemoglobin still in the red blood cells. I would like to use this case as a reminder of signal changes of intracranial hematomas on MRI.

The table above shows how we stage (name) hematomas according to time. Important observation is that the very early (hyperacute) hematomas contain Oxyhemoglobin and are difficult to see (isodense to brain) on T1 sequences. Same with Deoxyhemoglobin. Then after about 3 days we start to see high signal of Methemoglobin on T1. That continues to be high on T1 even when Methemoglobin is released from the hemolyzed Red Blood Cells, but then we start to see it as high even on T2. Late remains of the hemorrhage on MR can be seen as a rim of Hemosiderin deposits - that is just black. Gradient Echo (T2*) (GRE) sequences show hemorrhage as black since it is a sort of susceptibility artefact. It also exaggerates the volume of bleeding ("blooming artefact").

You may also check:
Neonatal Intraventricular Hemorrhage
Hemorrhagic Choroid Plexus Cyst
Late Subacute Hemorrhage on DWI
Hemorrhagic Brain Metastases

Oculomotor Infarct

2010-12-10T09:06:00.003+01:00

This 40 years old patient has experienced acute oculomotor nerve paresis. A 1.5T MRI has revealed a micro infarct (about 2mm) in location of the oculomotor nerve nucleus in the mesencephalon. Note high signal on DWI (B1000), low signal on ADC and high on T2 (B0) of the Diffusion Weighted Images (DWI) and coronal FLAIR. This case illustrates how sensitive can DWI be even in small infarcts.

Above drawing courtesy of Bartleby.
Fig. 710 Anatomy of the Human Body by Henry Gray
This is also a great opportunity to remind the location of the oculomotor nerve nucleus in mesencephalon (8'). Note that mesencephalon here is "facing down" compared to MRI. Well seen structures on the MRI are Red Nucleus, Substantia Nigra and Cerebral Aqueduct.

Cranial Nerves Nuclei
Drawing titled: Brain stem human sagittal section - by Patrick J. Lynch, medical illustrator
Courtesy Wikipedia

Also note location of the other Cranial Nerves Nuclei in the brainstem that are nicely depicted in the above drawing.

Carotis Segments

2010-12-09T11:26:00.002+01:00

Images from MR Angiography (MRA) with Time of Flight (ToF) source sequence on the left and reconstructed Maximum Intensity Projection (MIP) showing stenoses in the Internal Carotid Artery (ICA). This patient has a stent in the distal carotid artery that beginns in petrous and ends in cavernous segment. Presence of the stent can influence images of this ToF a non-contrast MRA. You can see stenosis (arrow). In such case I would recommend CTA. I would like to use this case for a short reminder of the terminology concerning ICA segments.

It is easier in CTA since we have reference anatomy points but just in case of the above MIP the typical curves can help. Here are the names of the Internal Carotid Artery Segments:
C1 = cervical
C2 = petrous
C3 = lacerum
C4 = cavernous
C5 = clinoidal
C6 = ophthalmic
C7 = communicating
Location of the markers corresponds with beginning of the segments (except for C1).
As we see our patient has stenosis in the C3 and C4 segments. Also note that there is hypoplastic A1 segment on the right (origin marked with arrowhead) as anatomic variant.
However when reporting the locations of stenosis I also like to give their descriptive names, not only numbers.

See also interesting publication from Medscape
Aneurysms of the Petrous Internal Carotid Artery: Anatomy

Superficial Siderosis

2010-12-08T15:05:00.002+01:00

Note extensive hemosiderine deposits superficially around brainstem, cerebellum - seen on first T2 images as well as deposits round basal ganglia and on the brain surface on the GRE (Gradient Echo) images.

Note extensive superficial hemosiderine deposits at cerebellum surface and brainstem on above GRE images.

Above coronal, sagittal, axial T1 and coronal FLAIR sequences show extensive cerebellar atrophy - that is also characteristic to Superficial Siderosis.

Note also extensive Superficial Siderosis of the spinal cord as well as it's atrophy.

Superficial Hemosiderosis (Superficial Siderosis) of the central nervous system results from chronic iron deposition in neuronal tissues associated with cerebrospinal fluid. Residues of blood are penetrating the pia mater and deposit in the superficial layers of the cerebral cortex. Superficial cortical hemosiderosis is defined as linear residues of blood in the superficial layers of the cerebral cortex. It has been shown in animal models with experimental siderosis that repeated bleeding in the subarachnoid space leads to deposition of hemosiderin in the subpial layer of the brain. When observing low signal deposits of hemosiderine it is important to note if it is located in the subarachnoidal space or superficially at the surface of the central nervous system. Superficial Siderosis is an effect and not a cause. One of the proposed causes is Cerebral Amyloid Angiopathy (CAA).

See also interesting article from AJNR:
Subarachnoid Hemosiderosis and Superficial Cortical Hemosiderosis in Cerebral Amyloid Angiopathy - J. Linn

Abscess and Subdural Empyema

2010-12-08T10:01:00.001+01:00

Patient previously operated for bilateral Subdural Hematomas (SDH) presented in febrile state with seizures. CT revealed peripherally enhancing cavity with surrounding edema parieto-temporally. Also noted were hyperdense SDH frontally and parietally with suspected leptomeningeal enhancement (arrows).

MRI confirmed CT findings showing enhancing, fluid filled cavity with surrounding edema and subdural fluid collections showing high signal on FLAIR (last image) and leptomeningeal enhancement (third image). Note mass effect on the coronal image.

Diffusion Weighted Imaging presented restricted diffusion of the fluid in the cavity showing high signal on DWI sequence and low signal on ADC map. This type of diffusion restriction in the fluid cavity is very suggestive for abscess.

More cranially has DWI shown also restricted diffusion in the subdural fluid collections that indicate empyemas. With note that hematoma can also show restricted diffusion, high signal on FLAIR and leptomeningeal enhancement, the whole spectrum of findings in this patient have been evaluated. Conclusion from the radiology and clinical investigation was: Brain Abscess with Infected Subdural Hematomas - Empyemas. Patient was operated using stereotactic neurosurgery based on MRI T1 MPRAGE sequence (not shown). During operation a flow of pus under pressure was noted from the abscess cavity. This case presents value of Diffusion Weighted Imaging in distinguishing between abscess and tumor. Tumor with necrotic fluid cavity generally shows no restriction on DWI.

Contrast Perfusion MRI

2010-12-07T15:02:00.001+01:00

Above color maps are from MRI Dynamic Susceptibility Contrast Perfusion (DSCP) study of the patient with follow-up after resection and radiotherapy of the parieto-occipitally located Anaplastic Astrocytoma eight years ago. There is no recurrent tumor - only gliosis. Sometimes DSCP can help in characterization of the enhancement pattern of rest or recurrent tumor to differentiate if from radiation necrosis. This case has no contrast enhancement. Reason for this blog post is to mention this interesting MRI technique that I hope to expand on in the future.
What we see are the color maps representing:
TTP (Time To Peak) - that shows the regional distribution of arrival time of the bolus in the tissue
CBF (Cerebral Blood Flow)
CBV (Cerebral Blood Volume)
MTT (Mean Transit Time)

Above are T2, FLAIR and contrast enhanced T1 sequences from the same region as presented on the Perfusion maps. Note gliosis, tissue atrophy and lack of enhancement.
Images from 3 Tesla scanner.

Persistent Hypoglossal Artery

2010-12-06T14:36:00.000+01:00

Large Persistent Hypoglossal Artery (PHA) is seen traversing the hypoglossal canal.

Note origin of this large vessel (Persistent Hypoglossal Artery marked with arrow) that is from distal Internal Carotid Artery (ICA) (arrow head) and located posteriorly to it.

3D reconstructions with mandible partially removed show PHA (arrow) as a large vessel posterior to ICA. Also note how it feeds the basilar artery after exiting from the hypoglossal canal. This case is very interesting not only due to persistent vessel but also that PHA is the only feeding vessel for the basilar artery since both vertebral arteries are hypoplastic and there are no posterior communicating arteries.

Interesting article form RadioGraphics:
Normal Variants of the Cerebral Circulation at Multidetector CT Angiography - Simon J. Dimmick

Tuberculoma

2010-11-22T13:31:00.001+01:00

Young woman from Africa that has experienced vision abnormalities few months postpartum. MRI shows strongly enhancing extraaxial nodule parietoocipital with significant surrounding edema. There is also increased meningeal enhancement. Open biopsy has revealed granulomatous tissue that has been confirmed by pathology to be Tuberculoma. Lesion like this has large differential diagnosis that includes sarcoidosis, meningioma, metastasis. This case shows that Tuberculoma is a pathology that can be common in endemic regions and should not be forgotten by radiologist.

Persistent Trigeminal Artery

2010-11-15T15:37:00.001+01:00

3D reconstructions of the CT Angiography show large Persistent Trigeminal Artery (PTA) (arrows). Second image is in dorsal tilt and third in even more tilt with anterior cerebral arteries facing upwards. In such projection the last image shows where PTA enters cavernous sinus. Also note M2 segment stenosis on the contralateral side (arrowhead).

CT Angio images show how PTA exits basilary artery, enters cavernous sinus and anastomoses with internal carotid artery.

Persistent Trigeminal Artery represents carotid-vertebrobasilar anastomosis connecting basilar artery with internal carotid artery (ICA). Reported incidence is 0.1–0.6%. There are two types: Saltzman 1 (this case) with absent posterior communicating artery. And Saltzman type 2 when ipsilateralt posterior cerebral (PCA) artety arises directly from ICA and P1 segment is absent (fetal origin of PCA).

Interesting article: Akira Uchino - MR Angiography of Anomalous Branches of the Internal Carotid Artery

Colloid Cyst

2010-10-22T14:41:00.001+02:00

Non enhanced CT showing little Colloid Cyst (CC) that has characteristic hyperdense appearance and location. This CC is located slightly posteriorly to the foramina of Monro and not causing obstructive hydrocephalus. Note open foramina of Monro on the lower set of images. The ventricular system is dilated however, that is most likely due to central atrophy. Note also general cortical atrophy supra- and infratentorial.

Vertebral Artery Dissection Collaterals

2010-10-20T14:45:00.002+02:00

Patient with proximal right Vertebral Artery (VA) dissection. VA is occluded from origin till C5 level (arrowhead on last image). Patient suffered from right cerebellar and left occipital infarct. Right VA is dominant (as anatomical variant) since left VA ends in Posterior Inferior Cerebellar Artery (PICA). Note on those 3D reconstructions the collateral circulation. First two images show Deep Cervical Artery branch that originates from Costocervical Trunk and enters VA cranial to C1 arch (arrow). Third and fourth images show another collateral: Ascending Cervical Artery that originates from Thyrocervical Trunk and enters VA through the vertebral foramen at the level of C2-3 (long arrow on last image).

Blue Eyes

2010-10-12T14:51:00.003+02:00

Surface reconstruction image from CTA showing both ophthalmic arteries and intra-orbital structures (shaded in blue). Nice for viewing anatomy and from aesthetic perspective. There is also some diagnostic value in such reconstructions as it seems easier to find vascular anomalies and present those to clinical doctors. Oh, and images look much better in motion due to 3D effect.

Subdural Hematoma

2010-09-28T08:57:00.000+02:00

Non contrast CT of the 96 years old patient shows large subacute Subdural Hematoma (SDH). Note significant middle line shift. Also observe density of this hematoma gradually increasing from anterior to posterior due to sediment. This SDH is evident, however sometimes the isointensity to the brain can obscure even large hematomas.

Neurofibroma

2010-09-24T13:33:00.000+02:00

CT shows contrast enhancing soft tissue mass parietal and occipital on the left side. Bone window images show destruction and deformity of the occipital bone due to biopsy proven Neurofibroma.

3D reconstructions of the CT Angio study show relation of the Neurofibroma with the transverse and sigmoid sinus. There is no obstruction of the venous blood flow occipitally.

Subclavian Steal

2010-09-17T09:56:00.000+02:00

Note occlusion of the 3 cm long part of proximal left subclavian artery that is proximal to the left vertebral artery. The flow in the distal left subclavian artery is from the left vertebral artery - Subclavian Steal. As a consequence there is reverse flow in the left vertebral artery (confirmed by Duplex). Additionally there is stenosis in the origin of both vertebral arteries and in the right proximal subclavian artery (last image).

Not Similar

2010-09-14T15:24:00.001+02:00

The above screen-grab is a result of my Google Image search for MRI in Parkinson with selection to "show similar images" (that is to the first image above). Rather surprising and unexpected result! If computed assisted radiology is going to function like Google Image Search engine - than we are long way before computers are replacing humans at the radiology workstations.

Occipital Infarct

2010-09-14T11:27:00.001+02:00

This patient presented with right sided hemianopsia. Non contrast CT shows well demarcated occipital infarct on the left side. Infarct was not clear at the initial scan. Therefore it is important to look especially in the clinically suspected territory of the brain.

At the above simplified schema note physiological correlation of the optic pathways and infarct location. In this case the black striped area corresponds with left sided occipital infarct and right sided hemianopsia.

Acute MCA Infarct

2010-09-14T09:15:00.002+02:00

Unenhanced CT of the 93 yrs old patient showing extensive acute right Middle Cerebral Artery (MCA) infarct. At first look infarct may not seem obvious. However note decreased amount of sulci that is most striking compared to the normal left side in this patient with normal for age cortical atrophy. Note decreased attenuation of the MCA territory on the right side as well as diminished delineation of the grey-white matter differentiation.

Thalassemia

2010-08-26T11:43:00.000+02:00

CT of the 6 years old with thalassemia showing extensive hypertrophy of the diploic spaces mostly in the maxillary walls, skull base and frontal bones. Note obliteration of the maxillary, sphenoid and frontal sinuses. Also note increased trabeculation in the diploë. This results from bone marrow hypertrophy due to ineffective erythropoiesis.

See also:
The Hair-on-End Sign by Margaret A. Hollar - article from Radiology

Cavum Velum Interpositum

2010-08-24T11:38:00.001+02:00

Cavum Velum Interpositum as incidental finding on CT.

Atul Gawande - The Checklist Manifesto

2010-08-15T12:39:00.000+02:00

I have just finished listening to the latest book by Atul Gawande - The Checklist Manifesto. I was looking forward to this book after reading his previous Complications book. The general style of writing is very honest, catching and inspiring. However what I mostly liked in Complications was the interesting medical cases presented with a very exciting narrative. The Checklist is somehow disappointing in this. There are fewer medical cases and plenty of aviation and real estate stories. This time I have chosen for the audiobook instead of classical paper book. It is interesting to confront those two different types of book "reading" experiences. Audiobooks allow for time efficient absorption of the reading material. Since I walk a lot an audiobook is a great alternative for me. However the traditional paper book allows to read more carefully, come back and re-read some parts of it. Audiobooks are more prone to distractions and missing some interesting points. In case of The Checklist Manifesto it was a good choice to pick the audiobook since the whole book seems to me like an interesting 6 hours long lecture. I have just ordered his first book Better. This time in traditional paper form.

Peace and Love from C2

2010-08-04T11:12:00.004+02:00

Today a bit of positive humor in normal anatomy. Note a peace sign in the odontoid process at the upper image that corresponds with closed ossification centers. Lower image shows a heart sign that is a normal configuration of the spinous process of the second cervical vertebra (C2) - same vertebra as above.
Example of "positive reading" of the radiology images. ;-)

Atlantoaxial Subluxation

2010-08-03T15:05:00.000+02:00

Note vertical subluxation of the odontoid process into the foramen magnum. Also known as basilar impression. Most likely caused by rheumatoid arthritis. However list of differential diagnosis is large.
See also: Rheumatoid Arthritis with Vertical Subluxation from Neuroradiology On The Net Blog

Atul Gawande - Complications

2010-08-01T21:48:00.000+02:00

I have just finished reading this excellent book. I can highly recommend it.
At first when I heard about it I was sceptic. Subject is very delicate and difficult to portray. I was afraid that the book would be addressed to the general public but to my very positive surprise it is so well written that it is a great read for both general and medical readers. Book is presenting a number of interesting medical cases and doing it in a very absorbing way. Atul not only describes the cases but uses them to discuss various delicate issues we, doctors, are dealing with in our daily practice. I very much agree with the points of view presented by the author.
Looking forward to read more from Atul Gawande.
Great job! Thank you.

Skull Fracture Line

2010-07-29T08:23:00.000+02:00

This very thin skull fracture line without dislocation can be easily missed. It is hard to find on the axial images, well seen on the sagittal projection and easy to find on the 3D reconstructions. So my simple radiology tip is: "Look at all images".

PRES

2010-07-28T15:05:00.001+02:00

PRES - Posterior Reversible Encephalopathy Syndrome.
Patient after two kidney transplantations that presents with seizures. Initial CT without contrast shows bilateral hypodensities cortical and in subcortical white matter in the parietooccipital regions.

Initial MR (transversal and coronal T2 and axial FLAIR) shows signal abnormalities in the cortical and subcortical regions mostly occipital and parietal as well as frontal. Changes are believed to represent vasogenic edema.

Follow up MR ten days later shows decrease of the pathological high signal changes (edema) with some residue signal abnormalities still visible.

Lissencephaly

2010-07-28T14:34:00.003+02:00

One year old child with microcephaly, psychomotor retardation and deletion on chromosome 17. Transversal T2, IR, coronal FLAIR and parasagittal T1 show decreased number of sulci as well as clearly thickened gyri. Case of Lissencephaly - "smooth brain" with Pachygyria - "broad gyri". Images from 3T MRI scanner.

Falx Meningioma

2010-07-26T09:11:00.001+02:00

Large Falx Meningioma is an easy find on contrast enhanced CT. However note how isodense is the tumor on the non contrast enhanced CT. Also due to it's cranial location it can be missed on axial images. Therefore look carefully at those upper slices on the axial series and it is highly recommended to include coronal and sagittal reformations as standard evaluation protocol.

Cerebral Venous Sinus Thrombosis

2010-07-23T13:23:00.000+02:00

CT Venography (CTV) Maximum Intensity Projection (MIP) images show contrast filling defects in the right sigmoid sinus, right transversal sinus and superior sagittal sinus. Extensive Cerebral Venous Sinus Thrombosis. Note prominent collateral circulation in the posterior fossa on the right side.

Contrast in Vertebral Venous Plexus

2010-07-23T09:02:00.000+02:00

There is increased contrast in the vertebral venous plexus of the cervical spine. This is due to entrapment (positional exacerbated) of the left brachocephalic vein between aorta and sternum. This resulted in decreased (delayed) arterial contrast during this Carotid CTA.

Moyamoya

2010-07-20T14:42:00.001+02:00

Coronal contrast enhanced T1 shows increased number and size of the lenticulostriate arteries "puff of smoke" that represent collateral circulation as a consequence to the tapering of the great intracerebral vessels. This is a case of Moyamoya. Note reduced caliber of the left MCA shown on the ToF MRA images. Also note on the lateral MIP from the ToF MRA a defect in the basilar artery flow with multiple collateral vessels.

Mandibula Fracture

2010-07-16T14:35:00.000+02:00

Undislocated mandibula fracture. Note that fracture goes through mental foramen and apex of the root of tooth 34.

Developmental Venous Anomaly

2010-07-16T08:56:00.000+02:00

Contrast enhanced T1 images show large Developmental Venous Anomaly (DVA) in the cerebellum on the right side as incidental finding. Large vein is draining into the sinus. Another incidental finding is a small meningioma parietal on the right.

Tolosa-Hunt Syndrome

2010-07-12T13:19:00.002+02:00

Tolosa-Hunt syndrome is clinically a painful ophthalmoplegia cused by inflammatory lesion of the cavernous sinus that is steroid responsive. Pathologically this process is similar to orbital pseudotumor. Above axial non contrast enhanced and axial, coronal and sagittal contrast enhanced CT shows a lesion extending from the cavernous sinus into the orbit through the superior orbital fissure. According to the literature CT is often normal. This case however proves value of the CT. MR is the investigation of choice in order to exclude other pathology in this region. See below reconstruced images.

Meningioma

2010-05-26T10:59:00.000+02:00

Axial and coronal T2, axial FLAIR and coronal post contrast T1 show large extaaxial tumor compressing left frontal lobe. Giant meningioma. Tumor has homogeneous structure, is sharply demarcated. It is a slow growing tumor therefore you see no edema in the adjacent brain tissue. Note intense and homogeneous contrast enhancement and spoke wheel vascular pattern. Due to high vascularity meningiomas can occasionally bleed and on such occasion increase in size giving symptoms (not in this case).

Perivascular Spaces

2010-05-26T10:19:00.000+02:00

Perivascular Spaces PVS (also known as Virchow-Robin spaces) are seen in this 1.5 years old child on transversal T2, IR, coronal FLAIR and sagittal T1 images. Location is typical in the lower parts of the basal ganglia accompanying penetrating arteries. Should not be mistaken with pathological finding. Clinical significance (or lack of it) is being discussed in the literature.

Nature in May

2010-05-26T08:17:00.000+02:00

Toyota iQ - Dashboard Reflection

2010-05-24T11:56:00.005+02:00

Today I had opportunity to try Toyota iQ for the third time. Like previously as a replacement car while mine was in the service. This time the car was purple. You can read my previous review of Toyota iQ here.
I decided to make a note on a very important issue that this car has. The front mounted dashboard island console that really serves no particular purpose is painted in very shiny finish. This combined with horizontal orientation and curvy configuration produces very strong light reflections at almost any bright sun angle. This has really a blinding effect. I have seen notes on discussion groups of users asking how to matt the surface. Toyota should promptly address this problem.
Two other issues that came back when driving this cute little car are: quite uncomfortable seats and poor radio controls. Seats are OK for a low budget car but iQ is in the rather high price category for it's class. The other issue is the little joystick mounted on the steering wheel that operates the radio. It is very user unfriendly. I could not figure out how to adjust bass, treble and balance. I know it is there since I saw it for a moment when pressing all the buttons in panic when after I started the car it blasted at me with high volume music.

So once again I would like to point that it is very important for the driver how the car feels on the inside. It's even more important than how it looks from the outside since we see it from the inside for most of the time.

Double Proximal Vertebral Artery

2010-05-24T10:38:00.000+02:00

Normal anatomic variant showing Double Proximal Vertebral Artery on the right side that originates from proximal and distal a subclavia and conjoins at the level of C6. Artefacts on 3D reconstructions are from contrast pooling in the adjacent veins.

How to make Contact Me link in Blogger?

2010-05-23T16:59:00.001+02:00

Different ways of contact!

I could not find a widget that would display a simple Contact Me form. What I wanted was a window with a place for email address and a note from the person willing to contact me. After some search I’ve found a walk-around solution:
Write a post titled Contact Me. Enable Comments in Settings. Set Who Can Comment? to Anyone allowing also not logged users to post. Set Comment Moderation to Always. Put your email address in this field in order to be notified about a comment – in other words to be Contacted! Now in Layout Add a Gadget called Link List. After clicking on your Contact Me post copy http link and paste it as a new link in the Link List gadget. Title Link List as Contact and link as Contact Me. Now you can be contacted without revealing your email address and Contact Me will always be displayed. You may suggest that commenting is also contacting. True, but some people look for this Contact Me link in your blog.