Differential Riagnosis of the Brain Tumor and Brain Abscess: the Usefulness of Dynamic MR Imaging

PURPOSE: To evaluate the usefulness of dynamic MR imaging in the differential diagnosis of intracranial tumorand abscess. MATERIALS AND METHODS: Dynamic MR images of 36 patients with surgically or clinically provenintracranial enhancing lesions were retrospectively reviewed. These lesions comprised 15 metastases, 14 gliomas,and seven abscesses. Images were sequentially obtained every 30 seconds for 3-5 minutes using the spin-echotechnique(TR/TE : 200 msec/15 msec) after bolus injection of gadolinium dimeglumine(2-3cc/sec). The dynamics ofcontrast enhancement of the lesions was analyzed visually and by calculating the sequential contrast-enhancementratio(CER). RESULTS: CER during the 30-second early dynamic phase was 93.16 in metastases, 67.78 in gliomas, and48.3 in abscesses(ANOVA, p<0.005). The contrast enhancement pattern of metastases showed rapidly increased signalintensity(SI) up to 30 seconds, followed by a relatively rapid decrease; less time was then required to reach theCER peak. In gliomas, SI increased gradually up to 180 seconds and then took a longer time to reach the CER peak.The SI of abscesses was similar to that of gliomas, with a more gradual increase for 30-60 seconds and a longertime for the CER peak to be reached. CONCLUSION: The contrast enhancement pattern and CER parameters seen ondynamic MRI can help differentiate intracranial tumor and abscess.

MR Imaging Findings of Ovarian Epithelial Tumor: Emphasis on Borderline Malignancy

PURPOSE: To evaluate the role of MR in the diagnosis of borderline epithelial tumors of the ovary comparedwith that of benign and malignant tumors. MATERIALS AND METHODS: MR images of 42 ovarian epithelial tumors in 39patients were retrospectively analyzed, focusing on the morphologic characters distinguishing borderlineepithelial tumors from benign and malignant tumors. All images were obtained using a 1.5T imager 3-27 (mean, 12)days before surgery. The size, shape, internal signal intensity, wall and septal thickness, papillary nodule,solid component, and contrast enhancement of the tumor were evaluated. RESULTS: Histopathologic diagnoses were 16serous epithelial tumors [benign (SB) 3, borderline malignancy (SBM) 5, malignancy (SM) 8]; 24 mucinous epithelialtumors [benign (MB) 11, borderline malignancy (MBM) 9, malignant (MM) 4]; one endometrial carcinoma (EC), and oneclear cell carcinoma (CC). Mucinous epithelial tumors were multilocular in 23 of 24 tumors, while signal intensityof the locules varied in 22 of 24. Six of 16 serous epithelial tumors were unilocular, and 15 of 16 were ofhomogeneous signal intensity. Papillary projection was seen in 14 tumors (SB 1/3, SBM 5/5, SM 3/8, MB 2/11, MBM2/9, CC 1/1), but multiple (>10) projections were seen in SBM (5/5) and CC (1/1). Multiple irregular thick septawere found in 18 tumors (SM 3/8, MB 2/11, MBM 9/9, MM 4/4), while solid components were seen in ten (SM 6/8, MB1/11, MM 2/4, EC 1/1). CONCLUSION: Multiple (>10) papillary projections and multiple irregular thick septa withoutremarkable solid components are suggestive MR findings of ovarian SBM and MBM, respectively.

Usefulness of Ultrasonography in follow-up evaluation after Ilizarov Procedure: Comparison with PlainRadiography

PURPOSE: To compare the usefulness of ultrasonography in follow up evaluation after the Ilizarov procedurewith that of plain radiography. MATERIALS AND METHODS: We analyzed ultrasound findings in twelve patients who hadundergone the Ilizarov procedure, and retrospectively compared the results with the findings of plain radiography.The procedure was performed due to post-traumatic limb deformity or non-union(nine of twelve patients), congenitalpseudoarthrosis(one case), sequelae of poliomyelitis(one case), and short stature(one case). The patients' meanage was 29 years ; eleven of twelve were male. Ten of twelve procedures were performed on the tibia and two on thefemur. After 7-10 days, distraction was initiated at a rate of 0.25mm four times a day. Ultrasonography wasperformed with a 5-10 MHz linear or convex transducer ; new bone formation was defined as dotted or linearechogenic foci within a hypoechoic distraction gap. Initial ultrasonographic examination was performed 2-4 weeksafter distraction, and the results were compared with those of plain radiography. Color Doppler imaging wasperformed in three cases. RESULTS: On ultrasonograms, new bone formation was initially detected 18-29(mean, 23)days after distraction, and on plain radiographs, 37-58(mean, 45) days after this procedure ; ultrasonography thusdetected new bone formation at least three weeks earlier than did plain radiography. Complication after theIlizarov procedure were four cysts at the distraction site, and one pin site infection, as seen on ultrasonograms.None of these four cysts, the size of which was 12-22mm(mean, 17mm), was visible on plain radiographs. In one casein which a cyst was present, ultrasound-guided aspiration was performed. Color Doppler examination was performedin three of twelve patients, and in all three, periosteal vascularity at the edge of the distracted gap was seento be preserved. CONCLUSION: After the Ilizarov bone lengthening procedure, ultrasound appears to be useful forfollow-up examination. New bone formation, as well as complications, can be detected earlier ; it can indicatewhether ultrasound-guided interventional procedure is required, and if combined with color Doppler study, is ableto detect the periosteal blood supply. Further evaluation of the clinical significance of preserved periostealblood supply seems however, to be needed.

Immature Teratoma of the Ovary: CT and US Findings

PURPOSE: To compare CT and US features of immature and mature teratomas of the ovary. MATERIALS AND METHODS: We retrospectively reviewed CT and US findings of 11 patients with immature teratoma and 18 patients(20 cases) with mature teratoma. The tumors were classified into three groups on the basis of image findings : predominantlycystic(type I), predominantly solid(type II), and mixed cystic and solid(type III). RESULT: All eleven cases of immature teratoma were of the mixed type(type III), showing multiple small(less than 2 cm) nodular and linear calcifications and fatty nodules within the solid component and adjacent to the septa of the cystic component of the masses. In contrast, mature teratomas were predominantly cystic in six cases, predominantly solid in eight,and mixed in six cases. In five of six mixed type mature teratomes, calcified fatty nodules were fewer and largerthan in immature teratomas. CONCLUSION: Immature teratoma may be diagnosed by the demonstration on CT or US ofmultiple small(less than 2cm) nodular and linear calcifications and fatty nodules in the solid and cystic components of the tumor.