MRI of the shoulder with its excellent soft tissue discrimination, and high spatial resolution offers the best noninvasive way to study the shoulder. MRI images of the bone, muscles and tendons of the glenohumeral joint can be obtained in any oblique planes and projections. MRI gives excellent depiction of rotator cuff tears, injuries to the biceps tendon and damage to the glenoid labrum. Shoulder MRI is better than ultrasound imaging at depicting structural changes such as osteophytic spurs, ligament thickening, and acromial shape that may have predisposed to tendon degeneration.
A dedicated shoulder coil and careful patient positioning in external rotation with the shoulder as close as reasonably possible to the center of the magnet is necessary for a good image quality. If possible, the opposite shoulder should be lifted up, so that the patient lies on the imaged shoulder in order to rotate and fix this shoulder to reduce motion during breathing.
Axial, coronal oblique, and sagittal oblique proton density with fat suppression, T2 and T1 provide an assessment of the rotator cuff, biceps, deltoid, acromio-clavicular joint, the glenohumeral joint and surrounding large structures. If a labral injury is suspected, a Fat Sat gradient echo sequence is recommended. In some cases, a direct MR shoulder arthrogram with intra-articular injection of dilute gadolinium or an indirect arthrogram with imaging 20 min. after intravenous injection may be helpful.

See also Imaging of the Extremities.

California-based research and development company. Alliance has several patents regarding 'microbubble' compositions such as Imagent® that are intended to enhance ultrasound imaging and Imagent GI as a gastrointestinal MRI contrast agent. Another product is Oxygent™, a synthetic 'blood substitute'.

MRI Contrast Agents:

• Imagent GI

From Hitachi Medical Systems America, Inc.;
the AIRIS made its debut in 1995. Hitachi followed up with the AIRIS II system, which has proven equally successfully. 'All told, Hitachi has installed more than 1,000 MRI systems in the U.S., holding more than 17 percent of the total U.S. MRI installed base, and more than half of the installed base of open MR systems,' says Antonio Garcia, Frost and Sullivan industry research analyst. Now Altaire employs a blend of innovative Hitachi features called VOSI™ technology, optimizing each sub-system's performance in concert with the other sub-systems, to give the seamless mix of high-field performance and the patient comfort, especially for claustrophobic patients, of open MR systems.

From Toshiba America Medical Systems Inc.;
the EXCELART is a superconducting whole body MRI system with a short wide-bore magnet, operating at 1.5 T. It features powerful high-speed gradients with a revolutionary gradient acoustic noise reduction system: Pianissimo. The dramatic reduction of gradient acoustic noise by Pianissimo greatly enhances patient comfort during exams. The standard array platform and a wide range of array coils ensure excellent images. A powerful 64-bit RISC-based computer system and newly developed array processor realize high productivity.

Manufactured by Esaote S.p.A.; compact in-office MRI system, fits in a 90 ft² (8.4 m²) space and requires no shielding or special power. This low field MRI magnet is optimized for orthopedic use and imaging of the extremities.
The C-SCAN™ is developed from the ARTOSCAN™ - M with a new computer platform, and is also known as Artoscan C.
Esaote North America and Hologic Inc. are the U.S. distributors of this MRI device.