MR imaging of primary lymphoma of bone: Variability of T2-weighted signal intensity

OBJECTIVE. The purpose of this study was to investigate the MR imaging characteristics of primary lymphoma of bone. MATERIALS AND METHODS. Records of 27 patients with histologic and clinical evidence of primary lymphoma of bone were retrospectively reviewed. Nineteen of these patients underwent MR imaging before surgical biopsy and initiation of therapy. Fifteen of the 19 patients underwent conventional spin-echo T1- and T2-weighted imaging, and the other four patients underwent T1-weighted and fast spin-echo T2-weighted imaging with fat saturation. MR images were separately and independently reviewed by two observers for signal intensity characteristics and homogeneity on T1- and T2-weighted sequences. Signal intensity characteristics were correlated with semiquantitative histopathologic assessments of tumor fibrosis, maturity of fibrosis, and vascularity. RESULTS. T1-weighted signal intensity ranged from isointense to hypointense relative to muscle for all lesions. Twelve of 19 cases showed heterogeneity of signal intensity on T2-weighted images. Predominant tumor T2-weighted signal intensities relative to fat for the 19 patients were assessed as hypointense (observer 1, n = 3; observer 2, n = 1), isointense (observer 1, n = 10; observer 2, n = 11), and hyperintense (observer 1, n = 6; observer 2, n = 7), No correlation among intralesional fibrosis, maturity of fibrosis, or intralesional vascularity and T2-weighted signal intensity characteristics was found. CONCLUSION. T2-weighted MR imaging characteristics of primary lymphoma of bone vary and do not seem to be a simple reflection of histologic findings of intralesional vascularity or fibrosis.