MRI scoring methods used in evaluation of muscle involvement in patients with idiopathic inflammatory myopathies

MRI is a promising imaging method commonly used to assess muscle involvement in patients with idiopathic inflammatory myopathies (IIM). MRI enables evaluation of both activity and damage and is therefore an ideal noninvasive diagnostic and monitoring tool. Despite its widespread use, there is no universally accepted method for scoring and reporting of MRI findings. The aim of this review is to provide an overview of systems used in the evaluation of MR images in patients with IIM.

A number of semi-quantitative and quantitative methods have been used to evaluate and record the severity of myopathy on MRI. These scoring systems differ in the number and type of parameters assessed and in their complexity; furthermore, they were evaluated in different patient populations, all of which make comparisons between them difficult.

There is a need to create a standardized and validated protocol for evaluation of pathological changes in muscle MRI in IIM. The most appropriate number and distribution of muscle groups as well as evaluated pathological features need to be determined. Based on this literature search, the future scoring system should include assessment of muscle oedema, fatty infiltration, muscle atrophy and possibly the presence of fascial and subcutaneous inflammation. Whether the quantitative methods provide more reliable information regarding disease activity remains unclear.