Wide-beam reconstruction half-time SPECT improves diagnostic certainty and preserves normalcy and accuracy: A quantitative perfusion analysis
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Filtered back-projection (FBP) has been a standard in SPECT imaging. Newer iterative reconstruction algorithms have been shown to improve image quality and shorten acquisition time by taking into account statistical nature of raw data and using resolution recovery (RR). Wide-beam reconstruction (WBR) is an iterative algorithm with RR and adaptive noise control. We prospectively investigated outcome of WBR half-time SPECT on diagnostic certainty, accuracy and normalcy by quantitative perfusion analysis in comparison to full-time FBP images.
434 patients underwent rest 201Tl/stress 99mTc-sestamibi full-time (20 s/stop, FBP) followed by a half-time (10 s/stop, WBR) SPECT. 34 patients underwent an angiogram within 90 days of SPECT. Diagnostic certainty was based on summed stress scores (SSS, 5-point/17 segments): normal if SSS ≤ 1, equivocal if SSS = 2-3, and abnormal if SSS ≥ 4. Perfusion defects were normalized to a percent of total myocardium, and expressed as %LV = defect SSS/maximal SSS × 100% with maximal SSS of 28 for left anterior descending (LAD), and of 20 for right coronary (RCA) and left circumflex (LCX). Change in %LV (Δ%LV = %LV FBP − %LV WBR) was evaluated for diagnostically discordant versus concordant scans.
SSS and %LV demonstrated very good correlation. There were significantly fewer equivocal scans with WBR (38 vs 151 FBP, P < .0001). Most discordant scans were equivocal FBP SPECT becoming normal with WBR (123/151). Δ%LVLAD for discordant studies was greater for women (5.4% ± 4.2%, P < .001), while Δ%LVRCA,LCX (4.4% ± 5.1%, P < .001; 1.2% ± 5.0%, P = .04) were greater for men. Normalcy rate was 91.4% for FBP and WBR with more definitely normal WBR studies (84.5% vs 43.9% for FBP, P < .0001). There were no differences in sensitivity (FBP 84.2%, WBR 81.6%), specificity (FBP 54.6%, WBR 63.6%), and accuracy (FBP, WBR 77.6%).
Quantitative perfusion analysis suggests that adaptive noise control with WBR improves uniformity of myocardium comparing to FBP techniques, and results in improved diagnostic certainty while preserving normalcy and accuracy.
KeywordsMyocardial perfusion imaging SPECT image reconstruction diagnostic and prognostic application image processing image quality
We are thankful to Michael Wilk, Ph.D. for editorial assistance in clarifying the physics of WBR algorithm.
Regina S. Druz, MD has received a travel grant from UltraSPECT, Ltd. The other authors have nothing to disclose.
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