Prospective and retrospective magnetic resonance (MR) imaging (0.35-T) interpretations were compared with final diagnoses in 110 patients suspected to have osteomyelitis. Diagnostic criteria of dark marrow on T1-weighted images and bright marrow on short-tau inversion-recovery images yielded a prospective sensitivity of 98% and a prospective specificity of 75%. Sixty percent of uncomplicated septic joint effusions demonstrated abnormal marrow signal intensity that was mistaken for osteomyelitis. Retrospective review revealed that overall specificity could be improved to 82% without loss of sensitivity if increased marrow signal intensity on T2-weighted images were included as an additional criterion. Specificity may be further increased by use of knowledge of morphologic patterns that distinguish various forms of osteomyelitis. Ten patients (9%) had potential pitfall diagnoses (eg, fracture, infarction, healed infection) that mimic osteomyelitis. MR imaging can be sensitive and specific for osteomyelitis if characteristic appearances and pitfall diagnoses are incorporated into the diagnostic criteria.

Current noninvasive imaging techniques for diagnosis of deep venous thrombosis (DVT) of extremities are limited in their ability to demonstrate central vein involvement and to distinguish acute from chronic changes. The utility of spin-echo magnetic resonance (MR) imaging for DVT was evaluated in 100 patients suspected of having either upper- (n = 25) or lower-extremity (n = 75) DVT. Ninety-seven patients were imaged successfully. In a subset of 36 patients, prospective comparison of MR imaging with contrast venography revealed a sensitivity of 90%, specificity of 100%, and Kappa level of agreement of .752 (P less than .0001). MR imaging showed more central extent of thrombus than did venography in all five patients with upper-extremity DVT and in 13 of 25 patients (52%) with lower-extremity DVT. Although all patients in the study were evaluated for acute symptoms, 13 of 59 (22%) MR imaging studies positive for DVT demonstrated chronic disease. MR images demonstrated ancillary abnormalities in 18 of 41 (44%) patients who did not have DVT. Thus, MR imaging has a role as the definitive examination when the results of initial screening studies are unsatisfactory, or as a first-line examination if (a) there is suspicion of upper-extremity or pelvic vein thrombosis, (b) there is a history of prior DVT that necessitates distinction of acute from chronic changes, or (c) other tests are unavailable.

Magnetic resonance (MR) imaging was used to assess for the presence of bacterial myositis, rare outside the tropics, in 13 patients with either the acquired immunodeficiency syndrome (AIDS) (n = 11) or positive results of serologic tests for the human immunodeficiency virus but without other evidence of AIDS (n = 2). Bacterial myositis was diagnosed in six patients: in five it was caused by pyogenic bacteria, and in the other, by Mycobacterium tuberculosis; in each patient, little or no subcutaneous tissue alteration occurred. On T1-weighted images in three patients, muscle abscesses showed a rim of increased signal intensity corresponding to margins between drainable pus and edematous muscle. Subcutaneous tissues appeared normal in patients with bacterial myositis but was not in the others, in whom muscle abnormalities tended to be less prominent. The latter group included patients with lymphoma (n = 1), Kaposi sarcoma (n = 2), and carbunculosis (n = 1), and three patients in whom no diagnosis was made; lymphedema was presumed to account for imaging abnormalities in four of the latter group.

MR imaging reliably depicts large and medium-size pulmonary emboli, regardless of infiltrates or effusion; hence, it may clarify findings on V-P scans that show intermediate probability of pulmonary embolism or are at variance with the clinical impression.

Primary ovarian pregnancy is a relatively rare form of ectopic pregnancy in which the gestational sac is implanted in the ovary and the tube is involved. Review of the literature demonstrated over 300 reported cases 1 and only 4 individual case reports that describe sonographic findings. 2 -5 We present an additional case report and emphasize the difficulty in distinguishing an ovarian pregnancy from a tubal ectopic pregnancy sonographically. CASE REPORTA 17-year-old woman, gravida II, para I, was admitted complaining of vaginal bleeding and pelvic pain for 10 days. She was sexually active and was not using any form of birth control, specifically no intrauterine contraceptive device (IUD). There was no history of venereal disease or pelvic inflammatory disease. Her last menstrual period was 9 weeks prior to admission.The patient was afebrile and normotensive. Pelvic examination demonstrated a tender cervix with a closed os. There was a small amount of blood in the vagina. The uterus was not enlarged or tender to palpation. The right adnexa was normal in size but the left was enlarged although nontender. Serum human chorionic gonadotropin was 80.7 nU/mL. Hemoglobin and hematocrit were normal.Sonography utilizing a Philips 3000 scanner and a 3.5-mHz transducer demonstrated a normal-sized nongravid uterus and normal-appearing right adnexa. A hypoechoic left adnexal mass measuring 5.2 em x 4.2 em x 6.5 em was located superior to the uterine fundus ( Figure 1). It dem-From the