OBJECTIVES: To develop a quantitative and noninvasive method of bone marrow cellularity evaluation in solvent-exposed painters. METHODS: Six painters (mean age 46.5 years, 5 males and one female) with hypocellular marrow, and 132 controls were examined using magnetic resonance imaging (MRI). A full examination of the peripheral blood and a bone marrow biopsy was done on each patient. Signal intensities were measured at the vertebral bodies from T12 to S1 on both the T1- and the T2-weighted image (T1WI and T2WI). Signal indices were calculated by dividing the signal indices of the vertebral bodies by that of the paraspinal muscle and the subcutaneous fat in the same view. RESULTS: The Bone marrow cellularities of the cases painters were between 20.3% and 33.6%. Signal indices based on the muscle at T1WI were greater in the cases of the painters compared to those of the controls (p<0.05, p<0.01). Signal indices based on the muscle at T1WI were significantly higher in older women compared with men (p< 0.05 ) . After adjusting for age and gender, the signal index of cases at S1 based on muscle of T1WI was higher than that of the controls by 0.364. Five of the six cases had a muscle signal index at S1 of T1WI higher than the mean + 1 standard deviation for the same age group and gender. CONCLUSIONS: MR signal indices are influenced by constitutional factors such as fat content, bone density, and the presence of other pathology. However, after adequate adjustment, it can be used as a useful indicator of bone marrow cellularity in a high-risk population.