Purpose or Case Report: An international Task Force from International Myositis Assessment and Clinical Studies Group (IMACS) conducted a comprehensive scoping review of the literature on analyzing MRI indications for patients with JDM, MRI techniques and protocols, and the adopted scoring systems. We also analyzed whether MRI was comparable to other measures used to assess disease activity, remission, or flares and whether MRI was accurate in achieving the proposed goals.
Methods & Materials:
A comprehensive search for studies in the MEDLINE (via PubMed), EMBASE, and Cochrane databases was conducted from January 2000 to October 2023 using a combination of descriptors of interest. Two experienced imaging experts analyzed the MRI methodologies of these articles.
Results:
Fifteen studies on patients with JDM under 18 years at disease onset were eligible and analyzed as part of the review. The objectives, methodologies, and analyses of these studies were heterogeneous. Moreover, the proposed scoring systems differ among themselves. Quantitative assessment was performed in one study, and semi-quantitative or qualitative analyses were performed in the other 14 studies. Whole-body MRI was performed in four studies, whereas thigh, pelvis, upper or lower limb dedicated MRI were performed in other studies. Muscle groups were assessed for symmetric or asymmetric distribution of edema, fatty infiltration, and muscle atrophy. Regarding whole-body MRI protocols, T1 weighted images acquired on coronal views were the sequences of choice to measure chronic inflammatory changes, such as hypotrophy and fat substitution of muscle bellies. In this review, T1 was used in all analyzed studies, except for one. Fluid-sensitive sequences such as T2 with fat saturation or short tau inversion recovery (STIR) were present in all studies and were also obtained on the coronal axis in most manuscripts. Fluid-sensitive sequences are the most relevant images for detecting soft tissue edema (high signal intensity) related to acute or subacute inflammatory findings. One study used additional diffusion-weighted and postcontrast sequences.
Conclusions:
Further studies with an established whole-body MRI protocol are necessary to define not only the best tool for diagnostic and disease activity criteria but also to recommend a standardized model of imaging acquisition and analysis that can provide comparable results and optimized results to study and follow patients with JDM.