Faculty Bibliography

Three cases of giant cystic craniopharyngiomas with large areas of extension beyond the suprasellar area are presented. The magnetic resonance (MR) appearance in one case is described. These giant tumors had large, multilobulated cysts that comprised the bulk of the tumors. In one case, there was an unusual extension of the large tumor cyst into the lateral ventricle. In two cases, the tumors extended to the level of the foramen magnum. On CT, the cyst contents of these two tumors were hyperdense and became hypodense postoperatively. All three tumors harbored calcifications in the form of clumps in the suprasellar region and rim calcifications around the cysts. None of the tumors exhibited contrast enhancement. A literature review of the radiographic features of craniopharyngiomas is discussed

Magnetic resonance (MR) images--both nonenhanced and enhanced with gadolinium DTPA/dimeglumine (Gd)--were compared with high-iodine (88.1 g I) computed tomographic (HICT) scans in demonstrating lesions in 15 patients known to have multiple sclerosis (MS). T1-weighted, mixed (T1, proton density, and T2), and T2-weighted MR pulse sequences were used. More than 20 lesions in each of 14 patients were demonstrated by pre-Gd mixed images and T2WI. Nine patients had clinical symptoms of active disease. Gd-enhanced T1WI showed at least one lesion that appeared to correspond with newly reported symptoms or signs. In addition, three clinically stable patients showed enhancement. Enhancement was best seen on 3-minute T1WI. HICT scans showed enhancement in four of the nine patients with active disease and in none of five clinically stable patients. Gd-enhanced MR imaging appears to be more sensitive than HICT in the detection of the transient abnormalities of the blood-brain barrier that occur in patients with active MS and appears capable of distinguishing active lesions that may correspond to the anatomic regions responsible for abnormal clinical findings

The sensitivity and specificity of CT and high-field MR (1.5 T) were compared in an evaluation of 30 patients with head injuries (eight acute, 15 subacute, and seven chronic). By using T1- and T2-weighted images, it was possible to detect various stages of hemorrhages and their separation from edema. In the acute category, both CT and MR showed acute hemorrhagic lesions, but only MR demonstrated coexisting chronic hematomas or small hypothalamic or brainstem infarctions. MR was far superior to CT in the detection and characterization of subacute injuries, including shearing injuries, hemorrhagic and nonhemorrhagic contusions, and subdural hematomas. In chronic injury, atrophy was demonstrated by both techniques, but only MR showed parenchymal abnormalities and old hemorrhages. Its ease in monitoring patients and its greater speed make CT the procedure of choice for the evaluation of acute cases. CT also provides information that is useful in deciding between surgery and medical management. However, the more precise anatomic depiction of MR and its sensitivity to parenchymal abnormalities make MR the key to correct prognosis in patients with subacute or chronic injury

Until the development of magnetic resonance (MR) imaging there was no nondestructive technique for monitoring the pathologic response to acute spinal cord trauma. The characteristic findings of hemorrhage, necrosis, and edema have been well described in animal models. We used a 1.4-T, animal imaging system to study acute cord contusions in rats. Contusions were induced by means of extradural aneurysm clip compression, and imaging was performed 3-5 hours after injury with short and long spin-echo (SE) sequences. Animals were killed immediately after imaging, and the gross anatomic and histologic findings were correlated with image appearances. On long SE sequences edema appeared as an area of high signal intensity that extended proximal and distal to the site of contusion. At the contusion site there was focal intraparenchymal hemorrhage which had low signal intensity on T2-weighted images, presumably owing to deoxyhemoglobin. MR imaging can be used to assess pathologic changes resulting from acute cord contusion and to aid in differentiating irreversible damage (hemorrhage) from potentially reversible edema

Twenty-five newly diagnosed intracranial meningiomas were evaluated with magnetic resonance (MR) imaging at 1.5 T, and findings were correlated with those of computed tomography (CT), angiography, and tumor histology. Meningiomas were generally hypointense on T1-weighted images and hyperintense on T2-weighted images relative to cerebral white matter. In comparison with the cortex, they were hypointense or isointense on T1-weighted images and isointense or hyperintense on T2-weighted images. A heterogeneous texture produced by tumor vascularity, calcifications, cystic foci, or an intrinsic speckled or mottled pattern was observed in all but the smallest lesions. An interface between meningioma and brain was uniformly present and consisted of a cerebro-spinal fluid cleft, vascular rim, or dural margin. Large meningiomas were associated with arcuate displacement and compression of adjacent gyri. MR imaging was superior to CT in defining extracerebral tumor location, tumor vascularity, arterial encasement, and venous sinus invasion. No correlation was found between the appearance on MR images and the pathologic classification

We report a case of multiple aneurysms with subarachnoid hemorrhage in which CT was inconclusive as to the source of bleeding and in which the angiographic criteria were misleading. Magnetic resonance demonstrated a focal subarachnoid hematoma adjacent to the ruptured aneurysm

High-field magnetic resonance (MR) imaging was performed in three patients with clinically diagnosed acute disseminated encephalomyelitis (ADEM). Contrast enhanced CT was normal in all cases. Magnetic resonance demonstrated multiple foci of demyelination in the brain stem, cerebrum, and cerebellum. Lesions were characteristic, in that they were relatively few in number, frequently present in the brain stem and posterior fossa, nonhemorrhagic, asymmetric, and easily correlated with clinical symptoms and signs. Follow-up MR in one patient who had clinically improved after steroid therapy showed marked resolution of previously documented lesions. Typical MR findings in combination with the appropriate clinical presentation can confirm the diagnosis of ADEM, obviate other more invasive diagnostic tests, identify the extent and sites of involvement, and follow response to therapy

Agenesis of the corpus callosum is a complex malformation of the brain that has been associated with varying degrees of limbic system maldevelopment. We retrospectively reviewed the records of 11 patients with callosal agenesis (seven total, four partial) who underwent magnetic resonance (MR) imaging, with particular attention to the associated malformations of the limbic system. Comparison was made with selected images from MR examinations of healthy volunteers and with necropsy specimens from other patients with callosal agenesis. Ten of 11 patients demonstrated limbic anomalies (severe motion artifact precluded evaluation of these structures in one patient). MR depicted not only the abnormalities intrinsic to callosal agenesis but also the frequently associated malformations of the limbic system