The purpose of this report is to describe our initial experience with
techniques employing magnetic resonance imaging (MRI) to guide the cho
ice of muscle to be biopsied in patients suspected of having inflammat
ory myopathy. Five patients with a clinical diagnosis of inflammatory
myopathy (IM) were studied. Four were imaged prior to biopsy. Four had
repeated examinations, either immediately following biopsy or to eval
uate disease progression. Use of MRI to localize muscle lesions was as
sociated with abnormal pathologic findings in all cases, including his
topathologic demonstration of lymphocyte infiltration in three cases o
f idiopathic polymyositis; nonspecific myopathic changes were seen in
one patient with probable dermatomyositis and in one patient with chro
nic inflammatory polyneuropathy and high serum creatine kinase levels
(>45,000 IU/ml). The precise location of the area sampled by biopsy wa
s visible in only one of four postbiopsy images. MRI shows promise in
identifying pathologic muscle in patients suspected of having one of t
he inflammatory myopathies; however, further refinement of localizatio
n techniques may be needed to optimize histopathologic diagnoses.