Wide beam reconstruction for half-dose or half-time cardiac gated SPECT acquisitions: Optimization of resources and reduction in radiation exposure

Claudio Marcassa, Riccardo Campini, Orazio Zoccarato, Paolo Calza

Research output: Contribution to journalArticlepeer-review


Purpose A new iterative reconstruction algorithm (WBR™) has been recently proposed for cardiac single photon emission computed tomography (SPECT). The WBR™ technology is designed to reduce noise, improving lesion identification without affecting the image resolution, allowing SPECT studies with reduced count statistic. This allows for either half-time (HT) or half-dose (HD) cardiac SPECT, with image quality and quantitative data comparable to standard-time (ST) or standard-dose (SD) SPECT. Few data exist on the comparison between conventional filtered backprojection (FBP) and this new algorithm in a clinical setting. The aim of this study was to compare the performance of FBP and WBR™. Methods Phantoms studies were performed to compare spatial resolution and contrast recovery with FBP, ordered subset expectation maximization (OSEM) and WBR™. A group of 92 patients, with different cardiac pathology, scheduled for a stress-rest SPECT were studied: 52 patients (group A) were injected with a SD of tracer and underwent both ST and HT SPECT; 40 patients (group B) were injected with a half dose of tracer and underwent ST SPECT and immediately after an additional SPECT at double time/projection (DT), to compensate for the low count statistic. A 2-day 99mTc-sestamibi protocol was used in all patients. SD/ST and HD/DT SPECT were reconstructed with a conventional FBP; SD/HT and HD/ST SPECT were reconstructed with WBR™. The summed stress score (SSS) and summed rest score (SRS) were calculated; the left ventricular ejection fraction (LVEF) was automatically derived. Results In group A (SD), no significant differences were observed between ST FBP SPECT and HT WBR™ in SSS (11.1 and 11.7, respectively) and SRS (9.4 and 10.3, respectively, NS). LVEF on rest acquisitions was also comparable (50% on ST SPECT and 49% on HT SPECT, NS); LVEF on post-stress studies in HT SPECT (46%) was lower than ST SPECT (50%), although not statistically significant. In group B (HD), SSS (6.2 in ST and 5.3 in DT) and SRS (4.0 in ST and 3.3 in DT) were also comparable. No differences were documented between ST and DT in rest (47 and 48%, respectively) and stress (48 and 50%, respectively) LVEF. Conclusion WBR™ performance and image quality were comparable to those of conventional FBP, allowing for either HT or HD studies. The former allows for an increased patient throughput and optimization of resources. The latter modalities would allow for a significant reduction in both patients' and operators' exposure. Further studies are needed to validate the clinical use of this method.

Original languageEnglish
Pages (from-to)499-508
Number of pages10
JournalEuropean Journal of Nuclear Medicine and Molecular Imaging
Issue number3
Publication statusPublished - Mar 2011


  • Filtered backprojection
  • Myocardial perfusion scintigraphy
  • Reconstruction algorithms
  • Wide beam reconstruction

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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