Faculty Bibliography

The enhanced and unenhanced MR examinations obtained after surgery for meningioma in 38 patients were reviewed to determine the value of enhanced vs unenhanced MR imaging for the detection of residual or recurrent tumor. Enhanced images improved delineation of the extent of tumor in seven of 13 cases in which meningioma was identified on unenhanced images and allowed more definitive detection or exclusion of residual or recurrent meningioma in 18 of 21 cases with equivocal findings on unenhanced images. In addition, enhanced images were helpful for detecting small recurrences, identifying en plaque growth, and showing subtle progression on serial studies. Enhanced MR imaging also allowed detection of two morphologic patterns of dural enhancement adjacent to the surgical bed: (1) thin and smooth, which was seen in patients both with and without residual or recurrent tumor, and (2) thick and nodular, which was seen only in patients with findings indicative of, or at least suggestive of, residual or recurrent meningioma. Unenhanced images failed to detect, or poorly detected, these dural abnormalities. Unenhanced sequences were necessary for accurate interpretation of the enhanced images (e.g., identification or exclusion of hemorrhage). The combination of unenhanced and enhanced MR imaging is recommended for the detection of residual or recurrent meningioma after surgery

The MR images of six patients with extraaxial empyemas (five subdural and four epidural) were reviewed and compared with CT scans. MR demonstrated convexity and interhemispheric collections, which were mildly hyperintense relative to CSF and hypointense relative to white matter on short TR pulse sequences and hyperintense relative to CSF and white matter on long TR pulse sequences, allowing distinction from sterile effusions and most chronic hematomas. A hypointense rim, representing displaced dura, was depicted at the interface between the lesion and brain in epidural empyemas, a feature absent in subdural empyemas. Inflammation-induced parenchymal abnormalities, including edema, mass effect, and reversible cortical hyperintensity, were well depicted on MR imaging. MR was superior to CT in demonstrating the presence, nature, and extent of these lesions in all cases. Because early and accurate diagnosis will significantly improve the prognosis of these serious infections, MR is preferred to CT for patients in whom an acute intracranial infection is suspected.

Computed tomographic (CT) scans were evaluated in 11 patients with acute hypertensive encephalopathy. Hypertensive encephalopathy is characterized by an acute, severe rise in blood pressure associated with headache, nausea, vomiting, altered mental status, and focal neurologic deficits, and rapid improvement after control of blood pressure. The systolic blood pressure range is 200-280 mm Hg; diastolic is 130-170 mm Hg. The most common CT finding was white-matter edema, diffuse or focal, affecting the supratentorial compartment in all cases and the infratentorial compartment in eight. These changes resolved after the blood pressure was lowered in all six patients studied by follow-up CT. Permanent areas of infarction were demonstrated in three patients. These abnormalities are correlated with the neuropathologic findings in hypertensive encephalopathy

The CT findings in 16 patients with nontuberculous spinal infections were reviewed. The specificity of certain CT features as well as the usefulness of intravenous contrast medium administration are discussed. The associated clinical presentations and predisposing factors are outlined. Emphasis is placed on a combined clinical, radiographic approach in facilitating an early diagnosis

Transient spontaneous regression of lesions was identified in four patients with intracerebral lymphoma. This finding, which may be related to cyclic changes in biological tumor activity as well as infarction and/or hemorrhage within the neoplasm, is not a good prognostic sign. Furthermore, when initial neuroradiologic studies suggest a diagnosis of lymphoma, subsequent spontaneous resolution of lesions should not be mistaken for a reliable sign of a benign, self-limiting disease. The diagnosis of this malignant neoplasm, despite regression of lesions, should be aggressively pursued early in the patient's clinical course when therapy would be most beneficial.