Interactive MR imaging-guided biopsy and aspiration with a modified clinical C-arm system.

OBJECTIVE: This investigation was performed to test the hypotheses that interactive guidance of MR image acquisition during needle-directed procedures using a clinical 0.2-T C-arm open MR imaging system integrated with a frameless optically linked stereotaxy system is feasible, and that procedure times can be sufficiently short to be well tolerated by the patient. SUBJECTS AND METHODS: One hundred six MR-guided procedures were performed in 86 patients (ranging in age from 5 months to 88 years) using a clinical C-arm imaging system supplemented with an in-room RF-shielded liquid crystal display monitor, a frameless stereotaxy system, rapid gradient-echo sequences for needle guidance, and MR-compatible monitoring and surgical lighting equipment. We performed 50 biopsies and aspirations of the head and neck in 37 patients, 23 biopsies of musculoskeletal lesions in 22 patients, 16 biopsies of abdominal sites in 10 patients, six biopsies of the thoracolumbar spine or sacrum in six patients, and 11 shoulder joint injections for MR arthrography in 11 patients, in addition to 38 MR arthrographic injections on the same imaging system described in a previous report. Tissue sampling included fine-needle aspiration (n = 90) and cutting needle core biopsy (n = 41). Thirty-five patients underwent both procedures. Procedures were evaluated for success of needle placement, procedure time, and complications. RESULTS: Needle placement was successful in all cases, and no complications occurred. Tissue was sufficient for pathologic diagnosis for all but eight patients. Passes per patient averaged 2.1. For fine-needle aspiration, instrument time averaged 7 min 42 sec per pass, cutting needle core biopsy averaged 6 min 24 sec, and shoulder injection averaged 8 min. CONCLUSION: MR imaging guidance for needle procedures on a clinical 0.2-T C-arm system with supplemental interventional accessories is feasible, with relatively rapid needle placement.

Fractures of the greater tuberosity presenting as rotator cuff abnormality: magnetic resonance demonstration.

BACKGROUND: To show that magnetic resonance imaging (MRI) can be useful to diagnose radiographically invisible greater tuberosity fractures in patients with clinical presentations suspicious for rotator cuff injury. METHODS: Six patients with subtle greater tuberosity fractures who were sent for MRI because of possible rotator cuff tear are reviewed (age range, 27-51 years; mean, 40.5 +/- 8.4 years). Five of the patients recount direct trauma to their shoulders, whereas one noticed shoulder pain after a fall in which she fractured her ankle. RESULTS: MRI showed an area of edema confined to the greater tuberosity with linear low signal extending through the tuberosity consistent with a fracture in all cases. Although five patients had a complete set of shoulder radiographs before MRI, these were interpreted as normal in all cases. Full-thickness rotator cuff tears were not present in any of the cases. All of the patients were treated conservatively with good results. CONCLUSIONS: MRI can prevent unnecessary arthroscopy in patients clinically suspected of rotator cuff damage by showing subtle fractures of the greater tuberosity not visible on radiographs.

MR arthrography of the shoulder: rethinking traditional imaging procedures to meet the technical requirements of MR imaging guidance.

OBJECTIVE: The purpose of this study was to determine the feasibility of and the appropriate technique for performance of MR imaging-guided arthrography of the shoulder. SUBJECTS AND METHODS: Thirty-eight MR imaging-guided glenohumeral joint punctures were performed using an open C-arm scanner with a vertically oriented magnetic field, adapted for interventional procedures. Two different approaches to the shoulder were used: a modification of the traditional anterior approach (seven procedures), and an anterosuperior approach (31 procedures) mimicking the anterior arthroscopy portal. The average procedure duration was determined. A retrospective review of needle mediolateral and anterioposterior position was determined for the anterosuperior approaches. RESULTS: Average procedure duration was 21 min for the anterior approach and 12 min for the anterosuperior approach. Subjectively, needle conspicuity was minimal with the anterior approach, contributing to prolonged imaging times. Needle visualization was much improved with the anterosuperior approach. Nine of the 31 anterosuperior procedures involved inadvertent injection of the subacromial or subdeltoid bursa. At the time of retrospective review, the needle was too laterally or too anteriorly positioned in six of these nine patients. CONCLUSION: With consideration of the technical demands of MR imaging guidance for interventional procedures, MR imaging-guided arthrography of the shoulder is feasible. The traditional radiologic approach to the shoulder must be modified to provide adequate visualization of the needle. The anterosuperior approach meets this needs.

Vertical fracture of the central sacral canal: plane and simple.

A case is reported of a sagittal fracture of the sacrum associated with diastasis of the symphysis pubis. The patient suffered no lasting neurologic injury. A literature review suggests that these vertical fractures may carry a better prognosis than other sacral fractures that involve the central canal.