Mr imaging

(MRI), an imaging method with particular value in assessing disorders of the musculoskeletal system. For a general description, see MR imaging.

The advantages of this technique include great inherent tissue contrast, excellent spatial resolution and exquisite anatomic display. Numerous MR imaging techniques have been developed to aid in assessment of musculoskeletal structures; these include spin echo pulse sequence, gradient echo GRE recalled imaging , fat saturation technique and short tau inversion recovery pulse sequence STIR . For most purposes, spin-echo sequences remain the standard method for obtaining imaging data from the musculoskeletal system.

MR imaging has also had an enormous impact on our understanding of the pathophysiology of musculoskeletal disease. The images display signal intensity derived from the tissue in a static magnetic field, reacting to external radiofrequency. MR images depend on parameters that reflect the chemical characteristics of tissues (Table 1), with the distribution of the hydrogen nucleus forming the basis of MR imaging. Contrast-enhancing chemical agents, specifically gadolinium chelates, can also be used to shorten the T1 relaxation time.

MR imaging (MRI), Table 1. Relative signal intensities of tissues in MR imaging.

MR imaging is particularly useful in evaluating normal and abnormal bone marrow (metastasis, plasma cell myeloma, leukaemia, lymphoma), osteomyelitis, devascularization and transient osteopenia about the hip. It is also helpful in the staging of musculoskeletal neoplasms and in the assessment and staging of soft tissue masses. MR imaging can be employed in cases of trauma to evaluate bone and soft tissue injury; muscle abnormalities can likewise be detected with this imaging method.

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