The influence of differences in hydration on bone-to-soft tissue ratios and image quality in bone scintigraphy

This prospective study evaluated the effects of different amounts of fluid intake on the bone-to-soft tissue (B:ST) ratio and image quality of bone scans performed using Tc-99m MDP. One hundred sixty patients with no renal disease were divided into three groups with different degrees of hydration in liters (group 1, 0.25 I; group 2, 1 I; group 3, 1.5 I), and image quality was assessed with a semiquantitative score. The B:ST ratio was calculated over the femoral diaphysis and adductor area, respectively. No significant differences in the B:ST ratio or image quality were demonstrated in all three patient groups with median values of 1.90 (group 1), 1.93 (group 2), and 1.84 (group 3). A filled urinary bladder was associated with greater fluid intake. The B:ST and image quality were correlated directly with the postinjection time interval and inversely with age. When patients drink a large volume of fluid, B:ST ratios do not necessarily increase and bone scintigraphy image quality does not improve.