Ke Li, Abstract Co-Author: Nothing to Disclose

Richard Dortch PhD, Abstract Co-Author: Nothing to Disclose

Brian Welch, Abstract Co-Author: Nothing to Disclose

Susan Kroop MD, Abstract Co-Author: Nothing to Disclose

Joseph Huston, Abstract Co-Author: Nothing to Disclose

Bruce M. Damon PhD, Presenter: Nothing to Disclose

Jane Harting Park PhD, Abstract Co-Author: Nothing to Disclose

To characterize the pathophysiological abnormalities of Idiopathic Inflammatory Myopathy (IIM) patients using multi-parametric quantitative magnetic resonance imaging (MRI) methods, including fat/water, T1, T2, magnetization transfer (MT), and diffusion tensor imaging (DTI).

Eleven IIM patients (six polymyositis (PM) and five dermatomyositis (DM)) and eleven age-matched healthy controls were examined. Images were acquired from their right thighs. T1-weighted and T2-weighted images were acquired as anatomical references. Fat/water contents were estimated with a multiple gradient echo sequence. T1 and T2 values were estimated using inversion recovery and multiple spin-echo methods, respectively. QMT parameters were estimated using pulsed saturation method. DTI parameters were estimated with 15 diffusion-weighted directions (and one b = 0 image). All data were processed in pixel-wise approach. Imaging data were analyzed using a two-way ANOVA, with main effects for disease and muscle. CPK and LDH levels were measured with blood test. 

The patients had higher mean fat fractions (0.142) than the controls (0.063) (p < 0.05), indicating significant fat infiltration/replacement. In patients vs. controls, there were higher mean T2 (37.1 vs. 32.1 ms), higher T1 (1.54 vs. 1.47 s), lower macromolecular fractions (qMT) (0.077 vs. 0.089), and higher ADC values (0.0018 vs. 0.0017) (p < 0.05), indicating inflammation. Fiber tracking indicated that the fiber tracts in patients are shorter, less dense, and less ordered. ANOVA test indicated differences between PM and DM patients with more significant muscle damage in quadriceps muscles compared to other muscle groups. Consistent with MRI findings, all patients have higher CPK (1498) and LDH (470) levels than the controls (107 and 169, respectively) (p < 0.05).

These multi-parametric methods may provide an improved understanding of the pathological processes associated with inflammatory diseases at a microscopic level, objectively, quantitatively, and independently of the acquisition details. In the future, they may be applied to longitudinal studies to track treatment response in individuals and other muscle diseases.

The proposed multi-parametric approach may allow clinicians to correlate the quantitative parameters to variations in lab findings, and to track treatment response on an individual basis.

Li, K, Dortch, R, Welch, B, Kroop, S, Huston, J, Damon, B, Park, J, Multi-parametric Characterization of Idiopathic Inflammatory Myopathy at 3.0 Tesla.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14001654.html