Diagnostic and Prognostic Implications of Spine Magnetic Resonance Imaging At Diagnosis in Patients with Multiple Myeloma

Abstract 3999

The role of baseline spine magnetic resonance imaging (MRI) in patients with multiple myeloma who have no related symptoms or signs is controversial. In the present study, we prospectively evaluated the diagnostic and prognostic implications of whole-spine MRI taken at the time of diagnosis in patients with multiple myeloma.

Patients who were newly diagnosed with multiple myeloma between 2004 and 2011 at Chungnam National University Hospital were enrolled. Abnormal MRI findings that were not detected in plain radiographs were analyzed and categorized as pathological fractures or extramedullary extension of the plasmacytoma. The bone marrow (BM) infiltration patterns on MRI were classified into five categories: homogenous diffuse, micronodular, macronodular, mixed, and normal appearance of the BM. The prognostic implications of the additional lesions found on MRI and the BM infiltration patterns were analyzed.

A total of 113 patients with a median age of 65 (range, 40μ–μ89) years were enrolled in the study. Pathological fractures that were not detected in the bone survey were found in 26 (23.0%) patients, including three (2.6%) patients with no related symptoms or signs. Extramedullary extension of the plasmacytoma was detected in 22 (19.5%) patients, including 15 (13.3%) with epidural extension of the tumor. Of these 22 patients, 11 (50.0%) had no relevant symptoms or signs. Neither the additional pathological fractures nor the extramedullary extensions found correlated with the international staging system stage (ISS). The presence of pathological fractures did not influence overall survival, whereas extramedullary extension of the plasmacytoma was associated with poor overall survival in multivariate analysis (HR 3.205; 95% CI, 1.430 – 9.845; P=0.042). Of the 113 patients, 35 (31.0%) had a diffuse infiltrative pattern, 39 (34.5%) had a micronodular pattern, 15 (13.3%) had a macronodular pattern, 17 (15.0%) had the mixed type, and 7 (6.2%) appeared normal. The BM infiltration patterns did not correlate with the ISS. During follow-up for a median of 21 (range 1 – 91) months, the overall survival of patients with the mixed type (median 24.0 months; 95% CI, 22.9 – 25.1) was shorter compared to those with other patterns (median 56 months; 95% CI, 48.9 – 63.1) (P=0.030). Survival differences were not found among the other patterns.

In summary, baseline spine MRI reveals not only bone lesions, but also extramedullary extension of plasmacytoma that cannot be detected in plain radiographs, even in patients with no relevant symptoms or signs. In addition, the mixed infiltration pattern on MRI is a predictor of poor overall survival. These results indicate that spine MRI should be included in the initial diagnostic investigations for patients with multiple myeloma.