Staging and monitoring of malignant lymphoma of the bone: Comparison of Ga-67 scintigraphy and MRI

The aim of this study was two-fold: to compare Ga-67 scintigraphy with MRI (a) for the staging of malignant lymphoma of the bone and (b) with regard t o accuracy in detecting residual disease after first-line chemotherapy for restaging. Methods: Twenty-one patients with 36 malignant osseous lesions w ere examined, including 7 patients with primary or multifocal osseous lymph oma and 14 patients with malignant lymphoma and simultaneous or secondary i nvolvement of the bone. After first-line therapy, MRI and Ga-67 scintigraph y were performed on 13 patients. The remission status based on all clinical and radiological findings during the follow-up was used as the gold standa rd. Results: The osseous lesions were located on the axial skeleton in 64% of patients and on the appendicular skeleton in 36%, Ga-67 scintigraphy det ected 77% of the osseous lesions examined by MRI. For restaging after first -line therapy, MRI had a sensitivity of 90% and a specificity of 80% when d ynamic MRI information was included. There were several false-positive resu lts as a result of the pathologic increase in signal intensity ratios of re active hematopoietic regions after chemotherapy. For Ga-67 scintigraphy, a sensitivity of 70% and a specificity of 93% were calculated. Conclusion: Th ese data show that monitoring malignant lymphoma of the bone still presents diagnostic problems. Given the high sensitivity of MRI and the high specif icity of Ga-67 scintigraphy but the limited specificity of MRI and sensitiv ity of Ga-67 scintigraphy, both methods are valuable but should be used as complementary diagnostic tools.