Use of a ray-based reconstruction algorithm to accurately quantify preclinical microSPECT images
Faculty of Medicine and Health Sciences
, 13 p.
University of Antwerp
This work aimed to measure the in vivo quantification errors obtained when ray-based iterative reconstruction is used in micro-singlephoton emission computed tomography (SPECT). This was investigated with an extensive phantom-based evaluation and two typical in vivo studies using (99m) Tc and In-111, measured on a commercially available cadmium zinc telluride (CZT)-based small-animal scanner. Iterative reconstruction was implemented on the GPU using ray tracing, including (1) scatter correction, (2) computed tomographybased attenuation correction, (3) resolution recovery, and (4) edge-preserving smoothing. It was validated using a National Electrical Manufacturers Association (NEMA) phantom. The in vivo quantification error was determined for two radiotracers: [Tc-99m] DMSA in naive mice (n = 10 kidneys) and [In-111] octreotide in mice (n = 6) inoculated with a xenograft neuroendocrine tumor (NCI-H727). The measured energy resolution is 5.3% for 140.51 keV (Tc-99m), 4.8% for 171.30 keV, and 3.3% for 245.39 keV (In-111). For Tc-99m, an uncorrected quantification error of 28 +/- 3% is reduced to 8 63%. For In-111, the error reduces from 26 +/- 14% to 6 +/- 22%. The in vivo error obtained with Tc-99m-dimercaptosuccinic acid ([Tc-99m] DMSA) is reduced from 16.2 +/- 2.8% to -0.3 +/- 2.1% and from 16.7 +/- 10.1% to 2.2 +/- 10.6% with [In-111] octreotide. Absolute quantitative in vivo SPECT is possible without explicit system matrix measurements. An absolute in vivo quantification error smaller than 5% was achieved and exemplified for both [Tc-99m] DMSA and [In-111] octreotide.