Low-field musculoskeletal MRI.

Since it was first introduced in the field of medical imaging in the early 1980s, MRI has become essential for the diagnosis and treatment of musculoskeletal conditions. Most imaging in the United States is performed on high-field (>1.0T), whole-body scanners. However, for reasons discussed below, imaging at low (<0.5T) and medium (0.5-1.0T) field strengths using small, low-cost, easily installed scanners in imaging centers and physicians' offices is gaining increasing popularity. Such scanners can be very useful for imaging the upper and lower extremities, from the shoulder to the fingers and the hips to the toes. In this review we provide an overview of the different available extremity scanners and their advantages and disadvantages, briefly review the literature regarding their use, and discuss our experience in using low-field extremity scanners to evaluate joints.

Low field MRI: a review of the literature and our experience in upper extremity imaging.

Since its introduction to medical imaging in the early 1980s, MRI has become essential in diagnosis and treatment of musculoskeletal conditions. Most imaging in the United States is performed on high-field whole-body scanners (>1.0 T). Imaging on low (<0.5 T) and medium (0.5-1.0 T) field strengths using small, low-cost, easily installed scanners in physicians' offices or imaging centers has gained popularity. These scanners can be useful in imaging the upper extremity from the shoulder to the fingers. This article provides an overview of the different extremity scanners available and their advantages and disadvantages, a brief review of the literature regarding their use, and a discussion of our experience in using the low-field extremity scanners in evaluating the upper extremity.

Increased through-transmission in abdominal tuberculous lymphadenitis.

OBJECTIVE: To describe 2 cases of abdominal tuberculosis in which sonographic evaluation of mesenteric lymphadenopathy showed increased through-transmission suggestive of caseating necrosis. METHODS: Two patients with abdominal pain and other symptoms (including fever, diarrhea, and weight loss) underwent abdominal sonography with a 6-MHz curved array transducer. One patient also underwent sonographically guided fine-needle aspiration of multiple lymph nodes, and the other underwent computed tomography, colonoscopy, and colon biopsy. RESULTS: In both patients, sonography showed multiple rounded hypoechoic lesions with increased ultrasound through-transmission suggestive of necrotic lymphadenopathy. No color flow was shown. In 1 case, the posterior acoustic enhancement was accentuated in the harmonic imaging mode. In the other case, the lesions shown on sonography corresponded to computed tomographic findings of low-density lymph nodes. Results of fine-needle aspiration and colon biopsy were positive for tuberculosis. CONCLUSIONS: Posterior acoustic enhancement in abdominal lymphadenopathy can suggest the diagnosis of tuberculous lymphadenitis. Detection of this finding is facilitated by scanning in the harmonic mode. Necrotic nodes will lack color flow and can be distinguished from lymphadenopathy of other causes. Sonography can also be used for fine-needle aspiration of necrotic nodes to yield a definitive diagnosis.