Evaluation of image enhancement software as a method of performing half-count bone scans

Reducing the radiation dose and scanning time of diagnostic tests is often desirable. One method uses image enhancement software such as Pixon, which processes lower-count scans and aims to produce high-quality images. However, it is essential that diagnostic accuracy is not compromised. We compared the level of agreement between clinicians using standard scans, with half-count and Pixon-enhanced half-count scans. Bone scans from 150 patients referred to diagnose metastatic disease were degraded by a process of Poisson-preserving binomial resampling to generate equivalent half-count scans and then processed by Pixon software to recreate 'original' high-quality scans. Two experienced clinicians reported the scans in a randomized, blinded manner for metastatic disease (yes/no) and assigned a confidence level to this diagnosis. Levels of agreement between clinicians were calculated for the full-count, half-count, and Pixon-enhanced half-count scans and between scanning methods for each clinician. Agreement between clinicians for standard full-count scans was 92% (±4%, κ=0.80), compared with 92% (±4%, κ=0.79) for half-count scans and 87% (±5%, κ=0.70) for Pixon-processed half-count scans. Agreement for a single clinician viewing full-count versus half-count scans was 95% (±2%, κ=0.88), similar to the agreement for a single clinician viewing full-count versus Pixon-processed half-count scans (95%, ±2%, κ=0.88). With respect to confidence in diagnosis, 127 full-count scans were scored in the highest category, compared with 98 half-count and 88 Pixon-processed half-count scans. Switching to half-count scanning does not introduce more diagnostic disagreement than is already present between clinicians. However, clinicians feel less confident reporting half-count scans. The Pixon enhancement step improved neither objective diagnostic agreement nor clinician confidence.