MR identification of white matter abnormalities in multiple sclerosis: a comparison between 1.5 T and 4 T.

BACKGROUND AND PURPOSE: Although MR spectroscopy and functional MR imaging of the brain have been successful at 4 T, conventional fast spin-echo imaging of the brain at 4 T has not been adequately evaluated. The purpose of this study was to compare the detection of white matter abnormalities in multiple sclerosis (MS) at 1.5 T and 4 T. METHODS: Fifteen patients with clinically definite MS were imaged at both 1.5 T and 4 T within a 1-week period. Comparison was made between fast spin-echo long-TR images at both field strengths. Pulse sequences were tailored to maximize resolution and signal-to-noise ratio in clinically relevant imaging times (< 7 min). Four interpreters independently reviewed the images obtained at both field strengths in separate sessions and evaluated them for lesion identification, size, characterization, and subjective resolution. Differences in interpretations at 1.5 T and 4 T were subsequently recorded. RESULTS: Images obtained at 4 T showed a mean of 88 more lesions as compared with images obtained at 1.5 T. All the lesions measured less than 5 mm and were typically aligned along perivascular spaces. Twenty-five consensually identified lesions on 4-T images were not seen at all on 1.5-T images. Moreover, 4-T images showed 56 additional consensually identified lesions, which were indistinct and seen only in retrospect on 1.5-T images. These lesions were frequently (n = 48) identified in large confluent areas of white matter signal intensity abnormality at 1.5 T. All observers also agreed that 4-T images subjectively enhanced the perception of normal perivascular spaces and small perivascular lesions. CONCLUSION: MR imaging at 4 T can depict white matter abnormalities in MS patients not detectable at 1.5 T through higher resolution with comparable signal-to-noise ratio and imaging times.

Neoplastic fixation to the prevertebral compartment by squamous cell carcinoma of the head and neck.

OBJECTIVE: The purpose of this study was to determine the accuracy of MR imaging in determining fixation of squamous cell carcinomas to the prevertebral space. MATERIALS AND METHODS: MR images of 15 patients with large pharyngeal carcinoma (n = 13) or laryngeal carcinomas with pharyngeal extension (n = 2) were retrospectively reviewed independently by two head and neck radiologists who were unaware of the surgical findings. MR images were evaluated for four criteria in the prevertebral longus muscle complex: muscle concavity, irregular tumor-muscle interface, T2 hyperintensity, and enhancement. All patients underwent panendoscopy where fixation or mobility of the tumor relative to the prevertebral fascia was assessed by manual manipulation. Tumors in six patients were fixed to the prevertebral space and inoperable. In nine patients whose tumors were not fixed, open neck explorations were performed and tumors were resected in seven patients. MR findings were compared with panendoscopy in all patients and with intraoperative assessment in nine patients. RESULTS: Eleven of 15 patients had at least two of the MR imaging criteria present. None of the MR findings were both sensitive and specific for tumor fixation. Although muscle concavity and enhancement each had a sensitivity of 88%, both criteria suffered from low specificity (14% and 29%, respectively). An irregular tumor-muscle interface and muscle T2 hyperintensity were criteria that suffered from both low sensitivity and specificity. Accuracy of the imaging criteria independently ranged from 53% to 60%. CONCLUSION: Although abnormal muscle contour, T2 hyperintensity, and enhancement are frequently present in neck carcinomas that are fixed to the prevertebral space, these findings may also be present in patients in whom the tumor is mobile and resectable. MR imaging may not be able to differentiate between neoplastic fixation and nonneoplastic changes in the prevertebral space.

Short-term prospective study of recovery in bulimia nervosa.

Thirty women who sought treatment at an eating disorders clinic in a general hospital and were diagnosed as having a current episode of bulimia nervosa were followed prospectively to assess the course of eating behaviors and other psychopathology. At intake, all 30 met DSM-III criteria for bulimia nervosa, and 57% met Research Diagnostic Criteria for an affective disorder. After 6 months of followup, 33% had recovered from the bulimic episode, and 24% had recovered from the affective disorder. One subject had recovered from both disorders. In subjects with an affective disorder at intake, the affective disorder had little effect on the time to recovery from bulimia nervosa, and recovery from bulimia nervosa had little effect on the time to recovery from the affective disorder.

Substance use, eating behaviors, and social impairment of medical students.

Self-report instruments assessing substance use, eating behaviors, social adjustment, and depression were distributed to all 329 first- and second-year medical students at a private northeastern university. Two-hundred students (61 percent) completed the questionnaires. Thirty-five students (17.5 percent) were found to be at risk for substance (alcohol and psychoactive drugs) abuse, of whom 13 were found to be at high risk. Thirty-three students (16.5 percent) were found to be at risk for an eating disorder, of whom only one was at high risk. Risk for eating disorders was greater for the female students, but risk for substance abuse was not related to gender. Psychosocial impairment and depression were associated with risk for either eating disorders or substance abuse.