MRI based semi-quantitative scoring system analysis of thigh muscles in patients with VCP disease

Inclusion body myopathy with Paget’s disease and frontotemporal dementia (IBMPFD) or VCP disease or multisystem proteinopathy-1 (MSP1), is a rare disease caused by mutations in the valosin-containing protein ( VCP ) gene that commonly manifests as proximal myopathy. We investigated the value of a 5-grade semi-quantitative scoring system based on MRI for studying myopathy progression in VCP disease. Among the subjects, twelve (60%) had varying degrees of VCP disease, two (10%) were asymptomatic carriers, and six (30%) were healthy first-degree relatives who served as controls for the VCP patients. The mean age of myopathy onset was 39.9 years (range: 25–51) while the mean myopathy duration at enrollment was 10.4 years (range: 3–31). We found that the vastii, sartorius, and adductor magnus muscles in VCP disease patients demonstrated a significantly higher fatty infiltration, whereas the adductor longus and rectus femoris muscles were relatively spared. Moreover, we observed a one-grade increase in fatty infiltration with each ten-year increase in disease duration. Our study shows that the semi-quantitative method based on MRI offers a rapid and non-invasive approach to improve the accuracy of clinical diagnosis of VCP disease and can be utilized to monitor disease progression effectively.