Hydration does not influence the image quality in bone scintigraphy: an investigation using 99Tcm-HDP

We investigated the possibility that the increased diuresis caused by hydration leads to enhanced renal excretion of radiotracer and thereby increases the target-to-background activity ratio and improves the image quality in bone scintigraphy. The study was carried out using paired comparisons in 10 healthy volunteers. Whole-body antero-posterior and postero-anterior acquisitions were obtained for 4 h after the administration of 99Tcm-hydroxymethylene diphosphonate with and without hydration. The bone-to-soft tissue activity ratio was semi-quantified by comparing regions of interest acquired from geometrical means of the acquisitions. Hydration was performed by slowly drinking 1.5 litres of water after administration of the tracer. Hydration induced a slight enhancement of excretion of the activity, but it had no effect on the bone-to-soft tissue activity ratio, nor did it influence image quality. We conclude that hydration could be avoided when it is cumbersome for the patient. However, as hydration reduces the radiation dose to the urinary bladder wall, which is the critical organ, hydration should be maintained in younger patients.