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Purpose: The purpose of this study was to evaluate the MR findings of calvarial eosinophilic granuloma.Materials and Methods: We reviewed the MR imaging studies of nine patients [M:F=3:6, aged 6 -35 (mean, 20.5) years] with pathologically proven eosinophilic granuloma in the calvaria. The findings were evaluated for involvement of the diploic space, changes in adjacent bone marrow, distinction of the transitional zone, pattern of bone destruction, signal intensity and contrast enhancement of the tumor, and contrast enhancement of the adjacent dura.Results: All lesions involved the diploic space, showed no change in adjacent bone marrow, and had a distinct transitional zone. In most (8/9) cases there was asymmetric bony destruction. On T1-weighted images, signal intensities of the tumors varied, while on T2-weighted images, hyperintensity was observed in seven cases, isointensity in one, and hypointensity in one. After the administration of contrast material, enhancement was homogeneous in four cases and inhomogeneous in five. Enhancement of the adjacent dura was demonstrated in all nine cases.Conclusion: The characteristic MR findings of calvarial eosinophilic granuloma are variable signal intensity on T1WI, high signal intensity on T2WI, and marked contrast enhancement; in addition, there is a distinct transitional zone, asymmetrical bony destruction, and associated dural enhancement.

PURPOSE: To compare the usefulness of combined fat- and fluid-suppressed selective partial inversion recovery-fluid attenuated inversion recovery(SPIR-FLAIR) images in the detection of high signal intensity of the optic nerve in optic neuritis with that of fat-suppressed selective partial inversion recovery(SPIR) or short inversion time inversion recovery(STIR) images. MATERIALS AND METHODS: Two radiologists independently analyzed randomly mixed MR images of 16 lesions in 14 patients (M:F=7:7; mean age, 40years) in whom optic neuritis had been clinically diagnosed. All subjects underwent both SPIR-FLAIR and fat-suppressed SPIR or STIR imaging, in a blind fashion. In order to evaluate the optic nerve, coronal images perpendicular to its long axis were obtained. The detection rate of high signal intensity of the optic nerve, the radiologists' preferred imaging sequences, and intersubject consistency of detection were evaluated. 'High signal intensity' was defined as the subjective visual evaluation of increased signal intensity compared with that of the contralateral optic nerve or that of white matter. RESULTS: The mean detection rate of high signal intensity of the optic nerve was 90% for combined fat- and fluid-suppressed SPIR-FLAIR images, and 59% for fat-suppressed SPIR or STIR images. In all cases in which the signal intensity observed on SPIR-FLAIR images was normal, that on fat-suppressed SPIR or STIR images was also normal. The radiologists preferred the contrast properties of SPIR-FLAIR to those of fat-suppressed SPIR or STIR images. CONCLUSION: In the diagnosis of optic neuritis using MRI, combined fat- and fluid-suppressed SPIR-FLAIR images were more useful for the detection of high signal intensity of the optic nerve than fat-suppressed SPIR or STIR images. For the evaluation of optic neuritis, combined fat- and fluid-suppressed SPIR-FLAIR imaging is superior to fat-suppressed SPIR or STIR imaging.

Purpose: To evaluate, using short-term follow-up MR imagings, the usefulness of gamma-knife radiosurgery in patients with acoustic schwannoma. Materials and Methods: In 34 patients (M:F=11:23, aged 11-69 years) with acoustic schwannoma, eleven of whom had undergone microsurgical resection prior to gamma-knife radiosurgery, we retrospectively reviewed the serial MR imaging findings obtained before and after this procedure. Analysis focused on post-sur-gical changes in tumor volume and intratumoral enhancement, and the follow-up period ranged from 3 to 44 months. Results: Follow-up imaging revealed that after radiosurgery, tumor size had decreased in 17 cases (50%), was unchanged in 14 (41.2%), and had increased in three (8.8%). Local tumor control was achieved in 31 of 34 cases (91.2%). Objectively defined tumor shrinkage was seen within 3 to 24 (median, 12) months of treatment, the rate of shrinkage increasing with longer follow-up. Three to 16 (median, 6) months after treatment, loss of cen-tral tumor enhancement was evident in 28 cases(82.4%). In 25 of 28 patients with intratumoral necrosis (89.3%), tumors were either smaller of their size was unchanged. Three to six (mean, 3.6) months after treatment, five cases demonstrated a transient size increase. Conclusion: Gamma-knife radiosurgery effectively controlled the growth of acoustic schwannoma, and intra-tumoral necrosis appears to be a predictable sign for decreased tumor size.

Purpose: To evaluate the usefulness, results, and technical problem of endovascular treatment in anteriorcommunicating artery(Acom) aneurysm using a Guglielmi detachable coil(GDC). Materials and Methods: We evaluated 18patients with Acom aneurysm who underwent endovascular treat-ment with GDC. Their clinical presentations weresubarachnoid hemorrhage (n=14), decreased visual acuity (n=2), and remnant aneurysm after surgical clipping (n=2).Hunt and Hess grades of 16 pre-surgical patients were Grade 0 in two patients, Grade I in three, Grade II in five,Grade III in one, Grade IV in three and Grade V in two. The size of aneurysms was 20mm in one lesion that wasclassified as large, while other lesions with diameters ranging from 3 to 12mm were classified as small.Theoutcome of treatment and technical complica-tions were analyzed. Clinical results were evaluated using the Glasgowoutcome scale(GOS). Results : Treatment was successful in 13 patients. Complete occlusion was observed in tenpatients and partial occlusion in three. In five patients, the procedure failed to occlude the aneurysms becauseof proximal arterial tortuousity (n=2), wide neck (n=2) or coil fracture during the procedure (n=1). Technicalcomplications in-cluded thromboembolism (n=1) and coil fracture during the procedure (n=1). Among the 13 patientswho were treated successfully, 11 were GOS I. Two patients died after treatment because of procedure-relatedthromboembolism in one patient and progressive vasospasm, demonstrated on angiography before treatment, in theother. Conclusions : Treatment of Acom aneurysm using a GDC is useful and has many advantages compared tosur-gical clipping. Because of the anatomical characteristics of the Acom, however, technical failure may be morelikely than in the case of posterior circulation aneurysm. Meticulous evaluation of aneurysms and adjacentar-teries on angiography, as well as careful patient selection, is needed.

Purpose : To determine the usefulness of fluid attenuated inversion recovery(FLAIR) imaging for the in detec-tion of high signal intensity of hippocampus or amygdala in mesial temporal sclerosis (MTS), compared with that of turbo spin-echo T2-weighted imaging. Materials and Methods : Two neuroradiologists independently analyzed randomly mixed MR images of 20 le-sions of 17 patients in whom MTS had been diagnosed, and ten normal controls. All subjects underwent both who performed both FLAIR and turbo spin-echo T2-weighted imaging, in a blind fashion. In order to deter-mine hippocampal morphology, oblique coronal images perpendicular to the long axis of the hippocampus were obtained. The detection rate of high signal intensity in hippocampus or amygdala, the radiologists ’preferred imaging sequence, and intersubject consistency of detection were evaluated. Signal intensity in hip-pocampus or amygdala was considered high if substantially higher than signal intensity in the cortex of adja-cent temporo-parietal lobe. Results : In all normal controls, FLAIR and spin-echo T2-weighted images showed normal signal intensity in hippocampus or amygdala. In MTS, the mean detection rate of high signal intensity in hippocampus or amyg-dala, as seen on FLAIR images was 93%, compared with 43% on spin-echo T2-weighted images. In all cases in which signal intensity on FLAIR images was normal, signal intensity on spin-echo T2-weighted images was al-so normal. The radiologists preferred the contrast properties of FLAIR to those of spin-echo T2-weighted images. Conclusion : In the diagnosis of MTS using MRI, FLAIR images are more useful for the detection of high signal intensity of hippocampus or amygdala than are spin-echo T2-weighted images. In the diagnosis of MTS, FLAIR imaging is therefore a suitable alternative to spin-echo T2-weighted imaging.