Magnetic Resonance Imaging of the Peripheral Nervous System

Label-free in vivo imaging of peripheral nerve by multispectral photoacoustic tomography

Unintentional surgical damage to nerves is mainly due to poor visualization of nerve tissue relative to adjacent structures. Multispectral photoacoustic tomography can provide chemical information with specificity and ultrasonic spatial resolution with centimeter imaging depth, making it a potential tool for noninvasive neural imaging. To implement this label-free imaging approach, a multispectral photoacoustic tomography platform was built. Imaging depth and spatial resolution were characterized. In vivo imaging of the femoral nerve that is 2 mm deep in a nude mouse was performed. Through multivariate curve resolution analysis, the femoral nerve was discriminated from the femoral artery and chemical maps of their spatial distributions were generated.

Imaging of skeletal muscle

Various diagnostic imaging techniques such as sonography, computed tomography, scintigraphy, radiography, and magnetic resonance imaging (MRI) have made possible the noninvasive evaluation of skeletal muscle injury and disease. Although these different modalities have roles to play, MRI is especially sensitive in the diagnosis of muscle disorders and injury and has proved to be useful in determining the extent of disease, in directing interventions, and in monitoring the response to therapies. This article describes how magnetic resonance images are formed and how the signal intensities in T1- and T2-weighted images may be used for diagnosis of the above-mentioned conditions and injuries.

Bursitis, adventitious bursa, localized soft-tissue inflammation, and bone marrow edema in tibial stumps: the contribution of magnetic resonance imaging to the diagnosis and management of mechanical stress complications

OBJECTIVE

To assess the contribution of magnetic resonance imaging (MRI) in the diagnosis of tibial stump bursitis, in the establishment of differential diagnosis, and in the therapeutic management prosthetic-stump interface, mainly by adaptation of the prosthetic device.

DESIGN

Two-year, prospective, consecutive series.

SETTING

University-affiliated prosthetic and rehabilitation center and university department of radiology.

PARTICIPANTS

A group of 17 persons with stump problems identified from a total of 139 consecutive below-knee amputees with prosthesis problems.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Clinical symptoms and MRI.

RESULTS

Clinical symptoms (variable stump volume, fluctuating mass at palpation with or without mechanical pain) were suggestive of bursitis in 10 patients. MRI confirmed bursitis in 9 and identified 1 in whom clinical signs suggested neuroma, giving an incidence of 10 of 139 amputees (7.2%). MRI identified 13 sites of bursitis (adventitious bursa, 11; synovial bursitis, 2) and 5 localized areas of soft tissue inflammation. MRI showed diffuse muscular edema at 1 site of clinically suspected bursitis, and bursitis at another site of suspected neuroma. Calcified bursitis was observed in 1 case. Bone abnormalities associated with bursitis (n=7) included osteophytes or fracture (n=4) or bone marrow edema (n=3). Two asymptomatic neuromas were also identified. MRI-guided modifications of the prosthetic interface led to favorable outcome in all cases.

CONCLUSION

Bursitis, adventitious bursae, and areas of localized soft-tissue inflammation are different aspects of the same disorder resulting from a mechanical conflict between the stump and the prosthesis socket. Besides contributing to diagnosis, MRI provides a precise assessment necessary for correcting the prosthesis-stump interface in a way that reduces mechanical stress and subsequently cures bursitis.

Imaging of sports-related muscle injuries

Muscle derangements in athletes have a wide variety of causes, treatments, and prognoses. Given that the cause and severity of sports-related injuries may be difficult to determine clinically in some cases, MR imaging is utilized increasingly to evaluate muscle injuries in athletes. After reviewing useful MR imaging techniques, this article focuses on MR imaging of the most common causes of muscle pain and disability in athletes, including myotendinous strain, delayed onset muscle soreness, muscle contusion, myositis ossificans, muscle laceration, muscle herniation, and compartment syndrome. The differential diagnosis of various signal intensity abnormalities in muscle also is reviewed.