A novel MRI-based algorithm to help diagnose and differentiate inherited myopathies presenting with spinal rigidity

 

Inherited myopathies are major causes of muscle atrophy and are often characterized by rigid spine syndrome, a clinical feature designating patients with early spinal contractures. In this multi-centre, retrospective study that included 79 patient, the authors aimed to present a decision algorithm based on muscular whole body magnetic resonance imaging (mWB-MRI) as a unique tool to orientate the diagnosis of each inherited myopathy long before the genetically confirmed diagnosis. Patients from referral centres in France, Brazil and Chile underwent 1.5-T or 3-T mWB-MRI. The protocol comprised STIR and T1 sequences in axial and coronal planes, from head to toe. All images were analyzed manually by multiple raters. Fatty muscle replacement was evaluated on mWB-MRI using both the Mercuri scale and statistical comparison based on the percentage of affected muscle. Patients were diagnosed with Pompe disease or harbored mutations in RYR1, Collagen VI, LMNA, SEPN1, LAMA2 and MYH7 genes. Each myopathy had a specific pattern of affected muscles recognizable on mWB-MRI. This allowed the authors to create a novel decision algorithm for patients with rigid spine syndrome by segregating these signs. This algorithm was validated by five external evaluators on a cohort of seven patients with a diagnostic accuracy of 94.3% compared with the genetic diagnosis.

Tordjman M, Dabaj I, Laforet P, et al. Muscular MRI-based algorithm to differentiate inherited myopathies presenting with spinal rigidity. Eur Radiol. 2018 May 25. [Epub ahead of print