A Rheumatoid Nodule Mimicking Soft Tissue Sarcoma on MR: A Case Report

We report a case of rheumatoid nodule of the right knee in a 55-year-old woman which on the basis of MR images was misdiagnosed as soft tissue sarcoma. Rheumatoid nodules occur in up to 20% of adult patients with rheumatoid arthritis and most patients with rheumatoid nodules are rheumatoid factor positive. The nod-ules are most commonly located between the skin and an underlying bony prominence. In this case, the patient had a history of rheumatoid arthritis and a soft tissue mass was present in the lateral aspect of the right knee. T1-weighted images revealed a mass of similar signal intensity to that of muscle, and on T2 weighted im-ages, a central portion of high signal intensity was noted. Enhanced T1 weighted images demonstrated periph-eral rim enhancement. The mass extended to subcutaneous tissue, with penetration of lateral patellar retinacu-lum. Excisional biopsy was performed, and the pathologic diagnosis was rheumatoid nodule. Although its radi-ologic findings are non-specific, rheumatoid nodule should - in appropriate clinical settings - be included in the differential diagnosis of a predominently solid or centrally necrotic periarticular soft tissue.

Sonographic Evaluation of Femoral Articular Cartilage in the Knee

PURPOSE: To investigate the usefulness of sonography for the evaluation of osteoarthritic articular cartilage. MATERIALS AND METHODS:Ten asymptomatic volunteers and 20 patients with osteoarthritis of the knee under-went sonographic evaluation. For this, the knee was maintained of full flexion in order to expose the deep portion of femoral condylar cartilage. Both transverse and longitudinal scans were obtained in standardized planes. Sonographic images of the articular cartilages were analyzed in terms of surface sharpness, echogenicity and thickness, along with associated bone changes. RESULTS: Normal cartilages showed a clearly-defined surface, omogeneously low echogenicity and regular thickness. Among 20 patients, the findings for medial and lateral condyles, respectively, were as follows: poorly defined cartilage surface, 16(80%) and ten(50%); increased echogenicity of cartilage, 17(85%) and 16(80%); cartilage thinning, 16(80%) and 14(70%) (two medial condyles demonstrated obvious cartilage thickening); the presence of thick subchondral hyperechoic bands, five (25%) and four (20%); the presence of osteophytes, 13 (65%) and 12(60%). CONCLUSION: Sonography is a convenient and accurate modality for the evaluation of femoral articular cartilage. In particular, it can be useful for detecting early degenerative cartilaginous change and for studying such change during clinical follow-up.

Acetic Acid Sclerotheraphy of Renal Cysts

PURPOSE: Sclerotherapy for renal cysts was performed, using 50% acetic acid as new sclerosing agent. Wereport the methods and results of this procedure. MATERIALS AND METHODS: Fifteen patients underwent sclerotherapyfor renal cyst, using 50% acetic acid. Because four patients were lost to follow-up, only 11 of the 15 wereincluded in this study. The renal cysts, including one infected case, were diagnosed by ultrasonograpy (n=10) ormagnetic resonance imaging (n=1). The patient group consisted of four men and seven women (mean age, 59 years;range, 23-77). At first, the cyst was completely aspirated, and 25 volume% of aspirated volume was replaced with50% sterile acetic acid through the drainage catheter. During the following 20 minutes, the patient changedposition, and the acetic acid was then removed from the cyst. Finally, the drainage catheter was removed, aftercleaning the cyst with saline. After treatment of infection by antibiotics and catheter drainage for 7 days,sclerotherapy in the infected case followed the same procedure. In order to observe changes in the size of renalcysts and recurrence, all patients were followed up by ultrasound between 2 and 8 months. We defined response totherapy as follows: complete regression as under 5 volume%, partial regression as 5-50 volume% and no response asmore than 50 volume% of initial cyst volume. RESULTS: No clinically significant complication occured during theprocedures or follow-up periods. All cysts regressed completely during follow-up of 8 months. Complete regressionoccurred as follows : two cysts at 2 months, seven cysts at 4 months, two cysts at 6 months. Two cysts showedresidues at the last follow-up, at 4 and 6 months, respectiivery. The volume of residual cysts decreased to under5 volume% of initial volume, however. Completely regressed cysts did not recurr during follow-up. CONCLUSION: Acetic acid sclerotherapy for renal cysts showed good results, regardless of the dilntion of sclersoing agent withresidual cyst fluid, and no significant complications. the procedure, therefore, appears to provide effectivetherapy for renal cysts.

An Experimental Study on Tissue Injury Following Intrahepatic Injection of Various Sclerosing Agents in Rats:Usefulness of 50% Acetic Acid

PURPOSE: To evaluate histopathologic change in the liver after injection of various kinds of sclerosants, andto thus determine whether 50% acetic acid, a new sclerosant, is suitable for percutaneous intrahepatic injection. MATERIALS AND METHODS: Four kinds of clinically available sclerosants were used : 50% acetic acid, 99% ethanol,10% phenol, and hot saline. Each group consisted of ten rats, and 0.1ml of each sclerosant was directly injectedinto the liver. After two days and one week, gross and histopathologic findings of resected liver in the area oftissue necrosis, as well as the degree of extrahepatic peritoneal adhesion, were assessed in each group. RESULTS:In all groups, the main pathologic changes were acute necrosis with inflammation after two days and secondaryregenerative fibrosis after week. In the 50% acetic acid injection group, the degree of necrosis was more severeand the mean diameter of the necrotic area was greater ; this latter was not, however, significantly wider than inthe 99% ethanol injection group, though was significantly wider than in the 10% phenol and hot saline injectiongroup. CONCLUSION: When used for percutaneous injection, 50% acetic acid, caused more tissue necrosis than 99%ethanol, 10% phenol, or hot saline. We therefore conclude that this acid may be useful for percutaneousintrahepatic injection of a hepatic tumor.

Spiral CT of Hepatic Masses: Usefulness of Additional Findings Except Enhancement Patterns / 대한간학회지

BACKGROUND/AIMS: We compared the accuracy in the diagnosis of hepatic masses such as hepatocellular carcinoma (HCC), metastasis and hemangioma using enhancing pattern alone with using additional findings, and determined whether the additional findings could improve the diagnostic accuracy. METHODS/MATERIALS: Triphasic spiral CT images were retrospectively analyzed in 83 cases of hepatic lesions,' 40 HCC, 21 metastases, and 22 hemangiomas. Three observers made the diagnosis first by the enhancement pattern of the mass alone, and then, by the whole information. The diagnosis of a lesion was considered correct if the lesion was correctly categorized by at least two observers. Diagnostic accuracies of two sessions were compared with McNemar test. RESULTS: Using enhancing patterns alone, 31/40 HCC (78%), 8/21 metastases (38%), 21/22 hemangiomas (95%) were correctly diagnosed. The frequency of correct diagnosis was significantly improved when all images with additional findings were used: 36/40 (90%) HCC, 20/21 (95%) metastases, 22/22 (100%) hemangiomas (P=0.00006). Metastasis showed most prominent and statistically significant improvement in the diagnostic accuracy (P=0.0004). The number of correct diagnoses for HCC increased without statistical significance (P=0.17). However, the images with additional findings did not significantly contribute to the diagnosis of hemangiomas. The additional finidngs those led to correct diagnosis of metastases were multiple mass (7 cases), coexistence of primary malignancy (6 cases), and metastasis to other organ (1 case). The findings of liver cirrhosis were helpful to diagnose HCC correctly in 5 cases. CONCLUSION: The enhancing pattems of tumors were important in the diagnosis of hepatic masses in spiral CT. However, the additional finidngs were also helpful for the diagnosis of hepatic masses especially for the masses with atypical enhancement pattern. In metastases, the additional findings such as multiple masses or detection of primary malignant focus were useful to diagnose correctly.

Fast FLAIR MR Imaging Finidngs of Cerebral Infarction: Comparison with T2-Weighted Spin Echo Imaging

PURPOSE: To evaluate the utility of FLAIR (Fluid Attenuated Inversion Recovery) MR imaging in cerebral infarction by comparing its results with those of T2-weighted spin-echo imaging. MATERIALS AND METHODS: We retrospectively evaluated fast FLAIR images and conventional spin echo images of 82 patients (47 men and 20 women; median age 60.9 years) with cerebral infarction. MR imaging used a 1.5T MR unit with conventional T2 (TR 3900, TE 90) and fast FLAIR sequence (TR 8000, TE 105, TI 2400). We analysed the size of the main lesion and number of lesions, and discrimination between old and new lesions and between small infarction and perivascular space. RESULTS: When T2-weighted and FLAIR imaging were compared, the latter showed that the main lesion was larger in 38 cases (46%), similar in 38 (46%), and smaller in six (7%). The number of lesions was greater in 23 cases (28%), similar in 52 (63%), and fewer in seven (9%). FLAIR images discriminated between old and new lesions in 31 cases ; perivascular space and small infartion were differentiated in eight cases, and CSF inflowing artifact was observed in 66 (80%). CONCLUSION: In the diagnosis of cerebral infaretion, fast FLAIR provides images that are equal or superior to T2-weighted images. The fast FLAIR sequence may therefore be used as a part of routine MR brain study in the diagnosis of cerebral infarction.

Microcystic Adenoma of the Pancreas Associated with Non-functionaing Islet Cell Tumor: A Case Report

Among cystic tumors arising in the pancreas, microcystic adenoma is relatively uncommon; it is usually benign, and is comprised of cysts that vary in size from microscopic to 2cm in diameter. It has recently been reported to be associated with other pancreatic tumors with malignant potential; in particular, microcystic adenoma with coexistent islet cell tumor has been reported in von Hippel-Lindau disease. We report a case of microcystic adenoma of the pancreas associated with coexistent surgically-proven islet cell tumor. On spiral CT, the islet cell tumor was seen as a highly enhanced inhomogeneous solid mass in the pancreatic head, and microcystic adenoma as numerous small cysts throughout the pancreas.