G.P.16: MR-guided muscle biopsy: A novel technique for the collection of muscle biopsies

Abstract

Muscle biopsy remains an important procedure in the diagnosis and research of muscle disorders. Traditional methods such as open or Bergstrom needle biopsy can be hampered by sampling error, especially in multifocal disorders such as inflammatory myopathies and facioscapulohumoral muscular dystrophy. Here we describe a novel technique to accurately obtain affected muscle tissue using a MR-guided approach. MR-guided biopsy of the vastus lateralis muscle was performed in 10 FSHD patients with varying degrees of disease severity. Fatty infiltration of vastus lateralis ranged from 90% of muscle area. The targeted area of muscle biopsy and needle trajectory were determined by an experienced neurologist and intervention radiologist using 3D T1 images. A MR-compatible needle was placed, after which another series of 3D T1 images were made to confirm that the needle was inserted at the region of interest. A vacuum-assisted biopsy was taken and a verification image with the stylet left in situ obtained. Despite the large amounts of fatty infiltration in some participants, muscle tissue was successfully acquired in all patients. A small non-symptomatic intramuscular hematoma (12 × 24 mm) was observed in 1 patient, a large symptomatic intramuscular hematoma (32 × 44 mm) was observed in another. However, in this patient a very lateral biopsy site was chosen, and the increased vascular supply to this area likely increased the risk of bleeding. MR-guided muscle biopsy is a safe and feasible method which enables the collection of muscle tissue from specific regions of interest, e.g. focal areas of inflammation. MR-guided biopsy can be performed in all muscles, however we advise to consider local vascular and nerve supply when choosing a target biopsy site. A titanium marker can be left in situ to perform follow-up imaging and/or biopsies of the same target area. Although not part of the current study, the technique can also be used to deliver therapeutic compounds.