The impact of different bone tracers and acquisition times on image quality of equine bone scintigraphy.

The impact of different acquisition times (AqT) and technetium-99 m-labeled (99m Tc) diphosphonates on the image quality of bone scintigraphy is poorly documented in horses. The aim of this prospective experimental study was to evaluate the impact of varying 99m Tc-disphosphonates and AqT on semiquantitative and qualitative image parameters of bone scintigraphy in horses. Twenty-four horses undergoing bone scintigraphy were divided equally and randomly into methylene- (MDP), hydroxymethylene- (HDP), and dicarboxypropane diphosphonate (DPD) groups. Lateral scintigraphic images of the antebrachium were obtained 3 h post 99m TC-diphosphonate injection using three AqT (60, 90, 120 s). The images were analyzed semiquantitatively using the bone-soft tissue ratio (B:ST), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image contrast. Furthermore, a blinded qualitative analysis was performed using a visual grading analysis. The results showed that DPD images had a significantly higher B:ST ratio than MDP images (P < .01) but not HDP images in all AqT (P > .08). However, DPD and HPD images acquired at 60 s had significantly higher CNR (P < .05) than those acquired at 90 and 120 s. The qualitative analysis revealed no significant differences between 99m Tc-diphosphonates at AqT 60 and 90 s. However, MDP images acquired at 120 s had significantly lower image quality compared to DPD and HDP (P = .01 and .03, respectively). In conclusion, the bone tracers affected the semiquantitative image parameters but not the qualitative analysis findings. Increasing AqT did not necessarily improve the image quality. Therefore, decreasing the AqT enabled a reduction in personnel radiation exposure.

Furosemide administration onehour before bone scintigraphy examination in horses does not improve the image quality or reduce the radiation dose rate.

This prospective, cross-sectional, pilot study aimed to investigate the effects of furosemide as a diuretic on the image quality of bone scintigraphy performed using 99m Tc-HDP and to investigate the impact of furosemide on the radiation dose rate. Thirty-one horses undergoing bone scintigraphy were included. The horses were divided into the control (n = 14) and furosemide group (n = 17), which received 1 mg/kg furosemide intravenously 1 h post 99m Tc-HDP administration. The image quality was assessed subjectively and semi-quantitatively. The bone-to-soft tissue (B:S) ratio was calculated from the counts per pixel of regions of interest (ROI) positioned over the left radial diaphysis (bone ROI) and its caudal soft tissue area (soft tissue ROI). The radiation rate dose (µSv/h) of both groups was measured at 0, 3, 6, 12, 18, and 24 h post 99m Tc-HDP administration at a distance of 0, 30, and 100 cm from the head, kidney, and pelvis. The results showed no significant differences in the B:S ratio or the radiation dose rate observed between the groups. However, the radiation dose rate decreased by 56% at 3 h post 99m Tc-HDP administration and keeping a distance of 30 cm reduced the radiation dose rate by 65%. Administering furosemide does not improve the image quality or reduce the radiation dose rate. The authors recommend commencing with bone scintigraphy 3 h post 99m Tc-HDP administration and keeping at least a distance of 30 cm from the horse to reduce the staff radiation dose.