SPECT, CT and MR: Integration in Degenerative Musculoskeletal Diseases

Abstract

In musculoskeletal degenerative disorders, physicians are often challenged by symptoms that are hard to locate precisely. Especially in the spine and the pelvis, as well as in the peripheral joints, the precise localization of the degeneration can be hard to detect. Additionally, symptoms can change during the course of time. After clinical examination, the imaging work-up usually starts with plain radiographs of different views (depending on the anatomical area); however, cross-sectional imaging modalities, such as magnetic resonance imaging (MRI), are frequently performed these days. The main advantage of MRI is the lack of radiation, the superb anatomical detail and, in contrast to single photon emission computed tomography (SPECT) and single photon emission computed tomography/computed tomography (SPECT/CT), the ability to show damage to cartilage, ligaments and tendons and other soft tissues. Thus, MRI is recommended by expert consensus opinion for use in several degenerative disorders as one of the primary diagnostic tools after plain radiographs. However, because MRI is able to show a large variety of lesions, it can be hard to evaluate those that are clinically relevant, especially when there is no adequate clinical history (a common problem in modern imaging) or when no dedicated musculoskeletal radiologist is available. As a consequence, some patients still lack an appropriate diagnosis after MRI, and hence they do not receive adequate therapy. Within recent years, hybrid SPECT/CT has emerged as a technique providing information on the morphological structure and metabolic activity of lesions, and providing an exact anatomical localization of pathological lesions. It has been shown in initial studies that SPECT/CT in selected indications can be a very valuable tool to provide a clinically relevant diagnosis or pinpoint the clinically relevant lesion to treat. It has also been shown that SPECT/CT can have higher inter- and intraobserver reliability than CT, bone scan or a combination of both in patients with different musculoskeletal degenerative disorders. SPECT/CT has also shown the ability to monitor osseous metabolism after anterior cruciate ligament repair, as well as the degree of loading of the knee compartments with consecutive osteoarthritis. Additionally, also compared with MRI, SPECT/CT has been found to be helpful, for example, in hand and wrist pain as well as treatment decisions for osteochondral lesions. Finally, there are upcoming initial trials that are integrating CT-arthrography into SPECT/CT to provide a full diagnostic, hybrid method for evaluation of bony morphology and osseous metabolism, as well as soft-tissue-like cartilage surface structure and ligaments.