Dose reduction in newborns and infants undergoing hepatobiliary scintigraphy

Objectives The currently accepted minimum administered dose of hepatobiliary radiopharmaceutical is 0.5 mCi/18.5 MBq (Gelfand et al JNM 2011). This study aimed to reduce radiation exposure by lowering the administered radiopharmaceutical dose, while preserving image quality through Enhanced Planar Processing (EPP) software (OncoFlash; Siemens Medical Solutions USA; Petrocelli et al SNM 2006).

Methods Studies included 40 patients <1 year of age (range 10 days-9 months) undergoing hepatobiliary scintigraphy from 2004-2010 at our institution. All received the standard minimum dose of 0.5mCi injected activity. Reduced dose studies based on body weight (activity/kg) were simulated using Binomial Subsampling software provided by Siemens. EPP was applied to the resulting reduced dose images. Seven reviewers rated the image quality of all 120 images using an ordinal scale: not acceptable, fair, good, or excellent.

Results Analysis using General Estimating Equations yielded the following: full dose images-96% acceptable (95% CI: 94%-99%); reduced dose images-76% acceptable (95% CI: 66%-86%); and reduced images with EPP-92% acceptable (95% CI: 87%-97%). The acceptability was significantly higher for both full dose and reduced dose with EPP studies compared to the reduced dose studies (p<0.001). No significant differences were detected between full dose and reduced dose with EPP studies (p=0.07).

Conclusions A significant dose reduction with acceptable image quality in these small patients can be achieved with the application of EPP. This study demonstrates the administered dose in this population can be reduced to an average 16%; or from 0.5 mCi to approximately 0.08mCi/2.9MBq. Further refinements to this approach are under way