Radiology MRI

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 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.

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.

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.

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  

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