Will frusemide administered to horses prior to scintigraphic examinations reduce the radiation dose rate? Erichsen C*, Falck-Andersen H*, Lønning M*, Bjørnstad A*, Eksell P # *Norwegian School of Veterinary Science, Oslo – Norway # Private practice, Ôrbyhus - Sweden

Introduction  Scintigraphy has high sensitivity for lesions in bone  Scintigraphy is commonly used in equine practice

Introduction  Radiation safety è The radiation dose from the horse has been claimed to be reduced after administration of frusemide. è No published data to support this.

Introduction  Pilot study at SLU, Uppsala  31 horses in two groups è 3 measurepoints è Measured at 2, 6 and 24 hours post injection  No difference between groups  Present study with improved method at NVH, Oslo è More horses è 1 measurepoint è 2 and 24 hours post injection

Purpose  To determine if administration of frusemide prior to scintigraphic examinations reduce the radiation dose rate from the horse at 2 and 24 h post injection.

Material 74 Horses Referred to NVH for scintigraphic examination 32 horses Group F (Frusemide) Group C (Control) 42 horses

Material Group F  Horses referred for scintigraphic examinations including the pelvis Group C  All horses referred for scintigraphic examinations of areas other than the pelvis

Material Group FGroup C Age7,48,1 BW (kg) Dose 99m Tc-HDP (MBq/kg BW) 10,310,1 Dose frusemide ( mg/kg BW) 0,33-

Material Group FGroup C Age7,48,1 BW (kg) Dose 99m Tc-HDP (MBq/kg BW) 10,310,1 Dose frusemide ( mg/kg BW) 0,33-

Method  All horses injected with radiopharmaceutical è 99m Tc HDP (10 MBq/kg BW)  Placed in a dedicated stable è Controlled area

Method Group F  Frusemide i.v. one hour post injection Group C  Control horses

Method  Geiger Müeller survey meter è Canberra Military Pocket Radiac  Accumulated Radiation dose during minimum 30 min was registered beginning è 2 hours post injection è 24 hours post injection

Method  Highest radiation dose 15 cm cranial to the tuber coxae against the skin

Method  Highest radiation dose 15 cm cranial to the tuber coxae against the skin

Method

Material and Methods  All measurements were corrected for time related to the time of injection and converted into  Sv/hour.  Minimum level of significance was set to p  0.05

Results  No significant differences in measured radiation dose between the groups Hours after injection  Sv/h F C

Results Radiation dose (  Sv/hour) MeanRange 2 hours63, hours3,42-7

Results Radiation dose (  Sv/hour) MeanRange 2 hours63, hours3,42-7 Myocard scan Bone scan

Results  Significant correlations: 1. Dose 99m Tc-HDP and radiation dose è Higher dose gives higher radiation dose 2. Bodyweight and radiation dose è Increased BW gives lower radiation dose

Discussion Claimed Advantages  Encourage urination è Improve image quality è Less radiation dose to personell Claimed Disadvantages  Possible increased restlessness during examination  Increases the risk of contamination by radioactive urine

Discussion Claimed Advantages  Encourage urination è Improve image quality è Less radiation dose to personell Claimed Disadvantages  Possible increased restlessness during examination  Increases the risk of contamination by radioactive urine

Conclusion  Dose 99m Tc & Horse size matters

Conclusion  For radiation safety reasons it should not be recommended to administer frusemide to all horses that undergo scintigraphy.  Administration of frusemide should only be recommended when pelvic imaging is performed, because of the increased risk of radioactive contamination due to urination.

Acknowledgements  The three students that did most of the measurements during 2006  Technicians at the Equine section, NVH  Anders Unoson

Thank you for your attention!