Radiology MRI

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.

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 .

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 .

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 subcor

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 .

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.

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 sag

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

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 .