Abstract
1352
Objectives The advanced noise reduction algorithm included in the ReSPECT iterative reconstruction software might help to obtain a good image quality in scans with a low count-rate, as often seen in parathyroid scanning with Tc-99m MIBI. We studied whether the use of ReSPECT increases image quality in parathyroid SPECT as well as in a phantom model.
Methods In this retrospective study we collected image data and follow-up (surgery and pathology results) from 60 consecutive patients who underwent parathyroid SPECT in a university hospital serving as a tertiary center for endocrine surgery. All images were reconstructed with HOSEM (Hermes) and ReSPECT (SciVis) iterative reconstruction software. The images were interpreted randomly and independently by two experienced blinded nuclear medicine physicians. We compared the diagnostic strength of both images as well as subjective (via a score sheet) and objective image quality. Objective image parameters were evaluated by a series of phantom scans.
Results ReSPECT images had significantly lower noise, higher subjective contrast and spatial resolution (p<=0.005). Also, objective contrast was higher for ReSPECT (p<0.001) as confirmed by the phantom scans. Furthermore, the spatial resolution improved by more than a factor of 2 when RePSECT was used to reconstruct phantom scans (FWHM 16.7 mm for HOSEM versus 7.6 mm for ReSPECT in the X-axis and 17.1 mm versus 6.6 mm in the Z axis, respectively). The region-based diagnostic accuracy was comparable with a sensitivity and specificity of 73.0% and 91.5% for ReSPECT and 68.3% and 91.5% for HOSEM, respectively. However, the score for interpretive certainty did increase when ReSPECT was used for reconstruction (p<0.001).
Conclusions In parathyroid scintigraphy, ReSPECT reconstruction yields better image quality in comparison to HOSEM. These results are supported by the objective data obtained in the phantom studies