Appearance of meningiomas on diffusion-weighted images: correlating diffusion constants with histopathologic findings.

BACKGROUND AND PURPOSE: Malignant and atypical meningiomas are prone to recurrence and aggressive growth, which affects treatment planning and prognostication. Investigators have used diffusion-weighted imaging and apparent diffusion coefficient (ADC) maps to compare tumor grade and cellularity with the histopathologic findings of intraaxial primary brain neoplasms. The purpose of this study was to determine whether the signal characteristics of meningiomas on diffusion-weighted images correlate with the average diffusion constant (Dav) from ADC maps and histopathologic findings and whether the Dav can reliably distinguish benign from malignant and atypical meningiomas. METHODS: Seventeen patients (13 women and four men; average age, 55 years) with meningiomas were prospectively studied using routine MR imaging and diffusion-weighted imaging with a single-shot gradient-echo echo-planar pulse sequence (6000/100 [TR/TE]) and b values of 0 and 1000. Signal characteristics on routine MR and diffusion-weighted images were compared with the histopathologic findings after resection by using World Health Organization criteria. Dav values were calculated within the tumor mass from ADC maps before resection. RESULTS: Four meningiomas were malignant or atypical (World Health Organization grades II and III). Dav values were lower than normal brain values (average, 0.52 +/- 0.12 x 10(-5) cm2/s; range, 0.45-0.69 x 10(-5) cm2/s) and were hyperintense on diffusion-weighted images and hypointense on ADC maps. Thirteen meningiomas were benign. Dav values were higher than normal brain values (average, 1.03 +/- 0.29 x 10(-5) cm2/s; range, 0.62-1.8 x 10(-5) cm2/s). On diffusion-weighted images and ADC maps, most were isointense. Five benign meningiomas had very high Dav values, bright signal on ADC maps, and distinct histopathologic findings, including microcysts, necrotic infarct, and organizing intratumoral hemorrhage. The difference in Dav values between malignant and benign meningiomas was statistically significant (P < .00029). CONCLUSION: Albeit a small sample size, meningiomas with low Dav tended to be malignant or highly atypical (P < .00029) whereas meningiomas with the highest Dav had increased water content due to either a specific histologic subtype of meningioma or the presence of associated pathologic abnormality.

Primary melanoma of the esophagus: radiologic and clinical findings in six patients.

PURPOSE: To evaluate the clinical and radiologic findings of primary melanoma of the esophagus. MATERIALS AND METHODS: A computer search of pathology, radiology, and cancer registry records from 1973 to 1998 revealed six patients with primary malignant melanoma of the esophagus whose radiographs were available for review. Six esophagograms, three contrast material-enhanced chest computed tomographic (CT) scans, and four chest radiographs were reviewed. Medical records were reviewed for presenting symptoms and clinical course. RESULTS: Six patients (age range, 63-78 years; mean age, 70 years) had histopathologically proved primary malignant melanoma of the esophagus. All patients presented with dysphagia or odynophagia of 6 weeks duration or less. Esophagography and chest CT showed polypoid, nonobstructing esophageal masses, which were mucosal (n = 5) or submucosal (n = 1) and which were located in the middle (n = 3), distal (n = 2), or proximal (n = 1) third of the esophagus. Five patients underwent esophagogastrectomy: Three died a mean of 5 months afterward, two were lost to follow-up, and one was alive 7 months later. CONCLUSION: Primary melanoma of the esophagus is rare. It is usually polypoid, intraluminal, and nonobstructive. As with other esophageal malignancies, the prognosis is dismal despite resection.