Characteristic MR image finding of squatting exercise-induced rhabdomyolysis of the thigh muscles.

ABSTRACT

OBJECTIVE: To describe the characteristic MRI appearance of squatting-induced rhabdomyolysis involving the thigh muscles. METHODS: This study consisted of 10 cases obtained at 3 institutions from 2005 to 2015. A retrospective review was performed to obtain clinical information and MR scans for rhabdomyolysis of the thigh muscles. MRI was analyzed according to the distribution and degree of muscle involvement; the degree was assessed and graded as normal, mild or prominent. RESULTS: The mean patient age was 20.2 years (range, 15-24 years), and 7 of the 10 patients were male. All patients had history of excessive squatting action, suffered clinically from bilateral thigh pain and were confirmed to have rhabdomyolysis through analysis of serum creatine kinase (CK) levels. All of the patients (10/10) exhibited diffuse mild to prominent degree involvement of the anterior thigh muscles according to fluid-sensitive MR sequences. Among the anterior thigh muscles, the rectus femoris was spared in 8 patients (8/10) and mild degree involved in 2 patients (2/10). Thus, no cases exhibited prominent degree involvement of the rectus femoris muscle. CONCLUSION: Preservation of the rectus femoris muscle on MRI in squatting-induced rhabdomyolysis may be useful for differentiating rhabdomyolysis from other aetiologies. Advances in knowledge Preservation of rectus femoris on MRI is distinguishable finding in squatting-induced rhabdomyolysis and reflects the functional anatomy of anterior thigh muscles.