Superparamagnetic iron oxide hepatic MR imaging: efficacy and safety using conventional and fast spin-echo pulse sequences.

The purpose of this study was to evaluate the technical efficacy and safety of iv ferumoxides (Feridex), a superparamagnetic iron oxide contrast agent for detection of hepatic lesions using conventional spin-echo and fast spin-echo MR images. Precontrast and postcontrast MR studies were performed on 25 patients with suspected focal hepatic lesions. Conventional T1- and T2-weighted MR images, as well as fast spin-echo and fat suppressed fast spin-echo MR images, were evaluated. Quantitative assessment of the contrast agent was performed obtaining region of interest measurements of the liver, spleen, and selected hepatic lesions. The pulse sequences were also evaluated subjectively for overall image quality and a subjective assessment of lesion detection. The use of a superparamagnetic iron oxide contrast agent led to a decrease in hepatic signal intensity on all pulse sequences. Lesion-to-liver contrast increased 41.1%, 36.5%, and 32.0% on the conventional T2, fast spin-echo, and fat suppressed fast spin echo pulse sequences, respectively. Lesion-to-liver contrast decreased on the T1-weighted postcontrast pulse sequence by 23.8%. Despite improvement in lesion-to-liver contrast, radiologists subjectively preferred the precontrast sequences because of overall better image quality. At a dose of 10 mumol/kg, ferumoxides favorably impacts lesion-to-liver contrast, and may be useful in hepatic imaging, more with conventional T2-weighted spin-echo pulse sequences than with T2-weighted fast spin-echo pulse sequence.

Prospective comparison of T2-weighted fast spin-echo, with and without fat suppression, and conventional spin-echo pulse sequences in the upper abdomen.

PURPOSE: To evaluate use of fast spin-echo (FSE) magnetic resonance imaging with and without fat suppression in the liver and upper abdomen. MATERIALS AND METHODS: Conventional spin-echo (SE) T2-weighted, FSE T2-weighted, and fat-suppressed FSE T2-weighted images from 37 patients strongly suspected to have focal hepatic lesions were evaluated. RESULTS: Quantitative analysis demonstrated that fat-suppressed FSE imaging had the highest lesion-liver contrast-to-noise ratio; conventional SE imaging, the lowest. In a qualitative analysis, FSE imaging was preferred. In a rank order analysis, FSE imaging was preferred 83% of the time and fat-suppressed FSE imaging 17% of the time as regards overall image quality; fat-suppressed FSE imaging was preferred 64% of the time, FSE imaging 23% of the time, and conventional SE imaging 13% of the time as regards signal abnormality detection. CONCLUSION: FSE imaging with and without fat suppression is a potentially useful pulse sequence for evaluating the upper abdomen.

Ovarian vein thrombosis.

We report five cases of OVT and review the literature on this disease. Among our patients OVT was not suspected clinically and was diagnosed by CT scanning or MRI. Ultrasound imaging, utilized in three cases, failed to detect OVT. Although this disease usually occurs after delivery, in two cases it was diagnosed before delivery. Of the two postpartum cases, one had a typical presentation and the other was asymptomatic. The final case was diagnosed incidentally 5 months after removal of an ovarian carcinoma. Our experience suggests that this disease may be underdiagnosed. More widespread use of CT scanning and MRI may lead to more frequent diagnosis of OVT. The role that clinically silent OVT may play in peripartum pulmonary embolism should be clarified.

Malignant pleural mesothelioma: value of CT and MR imaging in predicting resectability.

OBJECTIVE: Our objective was to determine if CT or MR imaging findings could be used to accurately predict resectability in patients with biopsy-proved malignant pleural mesotheliomas. SUBJECTS AND METHODS: CT and MR findings in 41 consecutive patients with malignant mesotheliomas who were referred to the thoracic surgery clinic for extrapleural pneumonectomy were studied by thoracic radiologists before surgery. Review of radiologic studies focused on local invasion of three separate regions: the diaphragm, chest wall, and mediastinum. Results of all imaging examinations were carefully correlated with intraoperative, gross, and microscopic pathologic findings. RESULTS: After radiologic and clinical evaluation, 34 patients (83%) had thoracotomy; 24 of these had tumors that were resectable. The sensitivity was high (> 90%) for both CT and MR in each region. Specificity, however, was low, probably because of the small number of patients with unresectable tumors. CONCLUSION: CT and MR provided similar information on resectability in most cases. Sensitivity was high for both procedures. Because CT is more widely available and used, we suggest it as the initial study when determining resectability. In difficult cases, important complementary anatomic information can be derived from MR images obtained before surgical intervention.

MR imaging of septic sacroiliitis.

Septic sacroiliitis is difficult to diagnose, causing delayed treatment and increased morbidity. The traditional imaging techniques for diagnosis have been CT and nuclear medicine. Our purpose was to determine the ability of MR imaging to detect septic sacroiliitis, to evaluate the features of septic sacroiliitis with MR, and to compare the relative detection rate of MR, CT, and nuclear medicine. All patients with a discharge diagnosis of septic sacroiliitis who were evaluated by MR imaging of the pelvis were retrospectively evaluated. Five patients were collected with six septic sacroiliac joints, which were also evaluated with CT, 99mTc-methylene diphosphonate bone scans, and 67Ga-citrate scans. Abnormalities consistent with sacroiliitis were seen in all sacroiliac joints both prospectively (impression from the initial report) and retrospectively on MR. In addition to the nonspecific MR findings of inflammation and/or fluid in the sacroiliac joint space, bone marrow of the sacrum and/or ilium, and iliopsoas muscle, fluid/inflammation was uniquely identified tracking posterior to the iliopsoas muscle in each of these patients with septic sacroiliitis. Even in retrospect, a definite diagnosis of sacroiliitis could be made in only five of six joints by 67Ga-citrate scans, three of six joints by CT scans, and one of six joints by 99mTc-methylene diphosphonate bone scans. These results suggest MR imaging may be a sensitive modality in the early diagnosis of septic sacroiliitis.