Nonmyelomatous monoclonal gammopathy: correlation of bone marrow MR images with laboratory findings and spontaneous clinical outcome.

PURPOSE: To determine the frequency of abnormal bone marrow magnetic resonance (MR) images in patients with nonmyelomatous monoclonal gammopathy and to compare the outcomes in patients with normal and in those with abnormal MR studies.
MATERIALS AND METHODS: In 37 patients with monoclonal gammopathy of undetermined or borderline significance (19 men, 18 women; aged 28-85 years), MR imaging findings of the vertebral, pelvic, and femoral bone marrow were analyzed and correlated with initial laboratory findings and outcome after a follow-up of 15-60 months (median, 31 months) with no treatment.
RESULTS: Thirty patients had normal MR studies; none required specific therapy after a median follow-up of 30 months. Seven had either diffuse (n = 4) or focal (n = 3) bone marrow abnormalities. Four required treatment after 15, 20, 50, or 58 months; three did not require treatment after 18, 26, or 40 months. Treatment-free survival curves in patients with normal and in those with abnormal MR studies were statistically significantly different (P = .005).
CONCLUSION: Bone marrow abnormalities were detected with MR imaging in seven patients (19%) with monoclonal gammopathy of undetermined or borderline significance. All patients with a normal MR investigation still had not required treatment after a median follow-up of 30 months.