Y. Nemoto

MR appearance of Rathke's cleft cysts

SummaryTwo of three patients who proved to have symptomatic Rathkes cleft cysts presented with visual field deficit and all with diabetes insipidus. CT showed intra- and suprasellar cystic low density lesions with ring enhancement. MR showed intra-and suprasellar masses. On the T1-weighted images two of the three had hyperintense portions similar to fat and the other a hyperintense portion similar to white matter within the cysts. These portions were isointense to brain on the T2-weighted images in all cases. This characteristic intensity on MR images provides differentiation from cystic pituitary adenomas and cystic craniopharyngiomas, and leads to correct diagnosis of Rathkes cleft cyst.

MR imaging of intraspinal tumors--capability in histological differentiation and compartmentalization of extramedullary tumors.

SummaryMagnetic resonance (MR) images of 29 consecutive patients with intraspinal neoplasms (9 intramedullary tumors, 20 extramedullary tumors) were reviewed to evaluated the utility of MR imaging in distinguishing the intraspinal compartmental localisation and signal characteristics of each lesion. Compartment and histology of all neoplasms were surgically proven. MR correctly assigned one of three compartments to all lesions, 9 intramedullary, 14 intradural extramedullary (6 schwannomas, 3 neurofibromas, 5 meningiomas), and 6 extradural (3 schwannomas, 1 meningioma, 1 cavernous hemangioma, 1 metastatic renal cell carcinoma). All intramedullary tumors showed swelling of the spinal cord itself. In all five extradural tumors a low intensity band was visualized between the spinal cord and tumor. On the other hand, a low intensity band was demonstrated in no cases with intradural tumors. Visualization of this low intensity band is important in differentiating extradural from intradural-extramedullary lesions. We call this low intensity band, “the extradural sign”. Signal intensity of intradural tumors varied with histology. In extramedullary tumors, signal intensity of schwannomas was similar to that of the cerebrospinal fluid (CSF) both on T1 weighted (inversion recovery) and T2 weighted spin echo (SE) images. On the other hand, meningiomas tended to be isointense to the spinal cord on both T1 and T2 weighted SE images. We found relatively reliable signal characteristics to discriminate meningioma from schwannoma.

CT and MR imaging of cerebral tuberous sclerosis

Tuberous sclerosis is a heredofamilial neurocutaneous syndrome, or phakomatosis, with multisystem involvement including the brain, kidney, skin, retina, heart, lung, and bone. The brain is the most frequently affected organ in tuberous sclerosis. Brain lesions in tuberous sclerosis are of three kinds; cortical tubers, white matter abnormalities, and subependymal nodules. We review the computed tomography (CT) and magnetic resonance (MR) features of the brain lesions in patients with tuberous sclerosis. CT clearly demonstrates calcified subependymal nodules. MR imaging demonstrates more clearly cortical, and white matter lesions than CT, since MR imaging shows excellent image contrast between various normal structures and high sensitivity in detecting pathological states due to intrinsic differences in proton density and in particular, in proton relaxation times of tissues. Possible pathogenesis of this disorder is also discussed.

Lymphocytic adenohypophysitis: skull radiographs and MRI

Abstract We report the skull radiograph, CT and MRI findings in three patients with lymphocytic adenohypophysitis mimicking pituitary adenoma. All cases were associated with pregnancy. CT demonstrated a pituitary mass but did not differentiate lymphocytic adenohypophysitis from pituitary adenoma. The skull radiographs showed either a normal sella turcica or minimal abnormalities; they did not show ballooning or destruction. The MRI appearances were distinctive: relatively low signal on T1-weighted images; preservation of the bright posterior pituitary lobe despite the presence of a relatively large pituitary mass, less common in macroadenomas; marked contrast enhancement compared with pituitary macroadenomas; and dural enhancement adjacent to a pituitary mass.

Facial nerve neuromas: CT findings.

Although neuromas of the facial nerve are rare, they present with uniform clinical and radiological findings. Their pluridirectional tomography findings have been well described; however, the appearance of the intracranial extension of the neuroma which is best visualized by CT has not been emphasized. We report five cases of facial nerve neuromas with particular attention to their intracranial extension. For comparative purposes we also have reviewed 10 cases of acoustic and eight cases of trigeminal neuromas, all involving the cerebellopontine angle (CPA) and the middle cranial fossa. Two of the five facial nerve neuromas affected the second and third segments of the facial canal, and three involved both the CPA and the middle cranial fossa spreading across the midpetrosal bone. This type of tumor extension seems to be characteristic of facial nerve neuromas. In acoustic and trigeminal neuromas the tumor crossing toward the middle fossa takes place via the tentorial hiatus (acoustic) and the petrous apex (trigeminal).

Syringomyelia associated with adhesive spinal arachnoiditis: MRI

Abstract We reviewed the MRI of seven patients with syringomyelia associated with surgically proven adhesive spinal arachnoiditis to describe clinical and MRI findings in this condition. Using 0.5, 1.0 or 1.5 tesla units, we obtained sagittal T1- and T2-weighted spin-echo and axial T1-weighted images. Additional sagittal T2-weighted images were obtained without using motion-artefact suppression. Contrast medium was given intravenously to five patients. The syrinx cavities were thoracic in five cases, cervicothoracic in one, and extended from C4 to L1 in one. No Chiari malformation or craniovertebral junction anomaly was demonstrated. Meningeal thickening was seen on T2-weighted sagittal images only in one case. Cord deformity due to adhesion or displacement due to an associated arachnoid cyst was seen in all cases best demonstrated on axial images. Focal blurring of the syrinx wall on axial images was seen in six patients. Flow voids were seen in the syrinx fluid in all cases on T2-weighted images obtained without motion-artefact suppression. No abnormal contrast enhancement was demonstrated.

Magnetic resonance images of tuberous sclerosis

SummaryThe cerebral lesions in tuberous sclerosis are of three kinds: subependymal nodules, cortical tubers, and cluster of heterotopic cells in the white matter. Understanding of these hamartomas is still incomplete even with modern imaging modalities. Magnetic resonance (MR) images of ten patients with tuberous sclerosis were reviewed and compared to computed tomographic (CT) scans and to the clinical severity of the disease. T2 weighted spin echo (TR=1800, TE=120) images and inversion recovery (TR=2100, TI=500–600, TE=40) images were obtained at the same axial planes. Periventricular nodules were better seen, because of their calcifications, with CT than with MR imaging. They were demonstrated as iso- to low intensity depending on the amount of calcification on T2 weighted images, and as a similar intensity to the white matter on IR images. Small peripheral lesions in the hemispheres, which were only occasionally seen as small low density areas on CT scans, were well demonstrated on MR images. These foci were hyperintense on T2 weighted images, and hypointense on IR images. Exact location of these was not in the cortex, but in the subcortical white matter. The findings indicate that these foci represent the pathologically well known demyelinating foci, which are commonly present under the cortical tuber, but may be independent of them. Cortical tubers were not confidently identified, which suggested that they might have similar intensity to the cortical gray matter. Some of the parenchymal calcifications other than periventricular nodules showed identical MR signal intensities to periventricular nodules, and the rest of the parenchymal calcifications had similar intensities to the subcortical lesions. This indicates that parenchymal calcifications can occur in the demyelinating white matter as well as in the heterotopic tubers in the white matter. The severely mentally retarded patients tended to have a higher number of subcortical lesions and no correlation was noted between the severity of mental retardation and either the number of periventricular nocules or ventricular dilatation.

Intradural chordoma: case report and review of the literature

Chordomas are rare neoplasms arising from notochordal remnants found predominantly in the clivus and the sacrococcygeal regions. Most clivus chordomas show extradural extension and bone destruction. Such a tumour can rarely be intradural. This report is concerned with the radiological findings in prepontine intradural chordoma.

Occult cranium bifidum

SummarySix cases of congenital subscalp nodule associated with underlying cranium bifidum are reported. A plain skull roentgenogram showed a midline bone defect in the parieto-occipital region near the lambda. CT scan demonstrated neither brain malformation nor ventricular deformity except for the high position of the straight sinus. Cerebral angiography revealed an elongation of the vein of Galen and anomalous upward course of the straight sinus. At surgery, the tumor was solid and connected to a cord which extended intracranially via the cranium bifidum and blended with thickened arachnoid membrane either on the dorsal aspect of the midbrain or at the surface of the anterior vermis. Histologically, the tumor consisted in all cases of arachnoid cells and fibrous tissue with immature glial cells in one case. Possible pathogenesis of these tumors could be a result of the fetal nuchal bleb.

Rathke's cleft cyst associated with hypophysitis: MRI

Abstract We report a symptomatic Rathkes cleft cyst associated with hypophysitis in a 61-year-old woman. We demonstrate the MRI features and discuss the pathophysiology. To the best of our knowledge this is the first description of a Rathkes cleft cyst shrinking after high-dose steroid therapy.