Figure 30-10. Contrast-enhanced MRI (left) showing multiple metastases from renal cell carcinoma. Note the extensive hypointense edema surrounding each lesion. The right image is a gradient echo MRI in which blood products appear hypointense (dark). This sequence can aid in detection of small or nonenhancing hemorrhagic metastases, such as the lesion in the left occipital lobe.
Figure 30-11. Leptomeningeal carcinomatosis from breast cancer showing infiltration of the cortical and cerebellar subarachnoid spaces on axial T1 post-gadolinium MRI. There is a small metastases in the pontine tegmentum.
Figure 30-12. Medulloblastoma. MRI in the sagittal (above) and axial (below) planes, illustrating involvement of the cerebellar vermis and neoplastic obliteration of the fourth ventricle.
Figure 30-13. Ependymoma of the fourth ventricle. A. Coronal T2 MRI shows an ependymoma growing out of the fourth ventricle. B. Axial T2 FLAIR MRI shows that the mass completely obliterates the fourth ventricle.
Figure 30-14. Hemangioblastoma. Contrast-enhanced MRI in the axial plane (left) shows the vascular tumor in the left cerebellar hemisphere. Selective left vertebral angiogram (right) defines a hypervascular nodule with dilated draining veins.
Figure 30-15. Pineal tumor. T2-weighted MRI in the sagittal plane (above) demonstrates a tumor that compresses the tectum and the cerebral aqueduct. Axial T2 FLAIR MRI (below) shows the tumor and evidence of hydrocephalus and transependymal flow of CSF from the lateral ventricles, resulting from aqueductal compression.
Figure 30-16. Lhermitte-Duclos disease. T2-weighted MRI showing the characteristic “tiger stripe” appearance of this hamartomatous tumor in the right cerebellar hemisphere.
Figure 30-17. Contrast-enhanced MRI of a cystic and nodular dysembryoplastic neuroepithelial tumor (DNET) of the left temporal lobe in an adult who had a single seizure. The nodule had an inflammatory component and the seizures ceased with resection.
Figure 30-18. Colloid cyst of the third ventricle. MRI in the axial and sagittal planes. Hydrocephalus due to obstruction at the foramen of Monro can occur, but is not apparent here.
Figure 30-19. Bilateral vestibular schwannomas in neurofibromatosis type 2. T1-weighted MRI in the axial plane before (left) and after (right) contrast administration.
Figure 30-20. A. MRI of a small vestibular schwannoma emanating from the left porus acusticus, showing typical homogenous gadolinium enhancement. B. A larger atypical vestibular schwannoma with rim enhancement, causing compression of the left middle cerebellar peduncle.
Figure 30-21. Pituitary macroadenoma. Coronal T1 MRI before (left) and after (right) contrast administration. A homogenously enhancing mass originating in the sella protrudes into the suprasellar cistern and displaces the optic chiasm and inferior hypothalamus. The lesion also extends into the adjacent cavernous sinuses.
Figure 30-22. Pontine glioma. Contrast-enhanced T1 MRI demonstrates a mass with prominent irregular peripheral gadolinium enhancement. The patient was a 3-year-old male with progressive cranial nerve and long tract deficits.