The plain-film, ultrasonography and computed tomography findings of retained surgical sponges (gossypibomas) are described in three patients. When a mass with hyperechoic wavy structures and posterior acoustic shadowing is seen on ultrasonography, the history of previous surgery must be questioned. Gossypiboma should be included in the differential diagnosis of such cases with a previous surgery. Plain film and computed tomography examinations should be obtained for correct pre-operative diagnosis.

OBJECTIVE. The purpose of thisstudyis to comparefat-suppressed T2-weightedfast spin-echosequences with T2-weighted multiplanargradient-echosequences in revealingro tator cuff disorders. MATERIALS AND METHODS. Obliquecoronal fat-suppressed fastspin-echo imagesand gradient-echo images of 39 patients who underwent surgery of the shoulder were retro spectively reviewed. Images from the two techniques were reviewed separately. Each set of images was interpreted twice by four musculoskeletal radiologists independently and with out knowledge of the surgical findings. Sensitivity and specificity for both sequenceswere determined. The kappa statistic was used to calculate intraobserver and interobserver agree ment of interpretations.RESULTS. Fordetecting anytear,thesensitivity of thefourreaders was71â€"96% using fast spin-echo and 58â€"100% using gradient-echo imaging. Confidence intervals showed no difference between the two sequences. Sensitivity of detecting full-thickness tears was 83â€" I00% for both sequences. Interobserver agreement was good. CONCLUSION. T2-weighted gradient-echo andfat-suppressed T2-weighted fastspinecho sequencesdepict rotator cuff tears equally well and take less time to acquire than con ventionaldual-echospin-echosequences. fat and fluid, increasedlesion conspicuity due to improved dynamic rangecharacteristics,re duced artifacts related to respiratory motion, and the elimination of chemical shift misregis tration artifacts [12,14,19,20]. Gradient-echo imaging allows significant reduction in image acquisition time by using gradient refocusing and reduced flip angles and provides higher contrast between the rotator cuff tendons and adjacent soft tissue than do conventional spin echo proton densityâ€"and T2-weighted se quencesI161,The purpose of our study is to compare the sensitivity and specificity of T2-weighted gradient-echo images and fat-suppressed T2-weighted fast spin-echo images for the detec tion of rotator cuff disorders. Materials and MethodsFrom October 1993 through March 1996, we obtained MR images of 329shoulders usingbothob lique coronal fat-suppressed fast spin-echo T2-weighted images and T2-weighted gradient-echo images u.spartof @ur standard imagingprotocol. All

Primary hemangiopericytoma of the bone is a rare tumor. We describe a patient with primary hemangiopericytoma of the tibia treated by surgery. The clinical and radiological features of this tumor are described. The radiological and histopathological different diagnosis of hemangiopericytoma is discussed.

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A case of histologically proven mediastinal paraganglioma presenting with metastatic spread to supraclavicular lymph nodes is presented. Mediastinal paragangliomas are extremely rare tumors and their CT and MR imaging features have not been well documented in the radiologic literature. The T 1-weighted and T 2-weighted spin-echo MR findings of a locally invasive mediastinal paraganglioma with metastasis to the supraclavicular lymph nodes are described and the literature is briefly reviewed.