Test-Retest Precision of Myocardial Blood Flow Measurements With ^99m Tc-Tetrofosmin and Solid-State Detector Single Photon Emission Computed Tomography

Abstract

Background: Measurement of myocardial blood flow (MBF) with single photon emission computed tomography (SPECT) is feasible using cardiac cameras with solid-state detectors. SPECT MBF has been shown to be accurate when compared with positron emission tomography MBF measured in the same patients. However, the value of a test result applied to an individual patient depends strongly on the precision or repeatability of the test. The purpose of our study is to measure the precision of SPECT MBF measurements using 99m Tc-tetrofosmin and a solid-state cardiac camera. Methods: SPECT MBF was measured in 30 patients and repeated at a mean interval of 18 days. MBF was evaluated from images with and without attenuation correction based on a separately acquired CT scan. The dynamic images were processed independently by 2 operators using in-house kinetic analysis software that applied a 1-tissue-compartment model. The K1 rate constant was converted to MBF using previously determined extraction fraction corrections. Correction for patient body motion was applied manually. Results: The average coefficient of variation (COV) in the differences between the 2 MBF measurements was between 28% and 31%. The interobserver COV was between 11% and 15%. Myocardial flow reserve is the ratio of MBF measured at stress and rest, and the COV is correspondingly higher. The COV for the difference in repeated myocardial flow reserve was 33% to 38%, whereas the interobserver COV was 13% to 22%. Conclusions: The COV for the difference in SPECT MBF measurements obtained on separate days is 28% to 31%. The corresponding COV for myocardial flow reserve is 33% to 38%.

Quantitative clinical nuclear cardiology, part 2: Evolving/emerging applications

“…Short-term test-retest studies are necessary to establish the repeatability of clinical SPECT MFR. In the only such study reported to-date, 33 SPECT MBF and MFR test-retest precision and inter-operator variability were found to be worse compared to PET, likely influenced by the inherently low extraction of 99m Tc-based perfusion tracers. Despite these challenges, promising SPECT MFR results have been shown in small single-center human studies compared to PET as the gold standard, [26][27][28][29][30] and ongoing prospective clinical studies are aiming to better establish the accuracy and reproducibility (https://clinicaltrials.gov/ct2/show/NCT02280941) and the diagnostic and prognostic utility of SPECT MFR (https://clinicaltrials.gov/ct2/show/NCT03637725, https://clinicaltrials.gov/ct2/ show/NCT02697760).…”

Improved precision of SPECT myocardial blood flow using a net tracer retention model

“…Comparisons of SPECT-SPECT flow measurements determined with the 1CM with +MC showed worse precision using the 2017 version of Corridor4DM software (COV = 34% for MBF and 41% for MFR) than using FlowQuant software for the same image set previously (COV = 28% for MBF and 35% for MFR). 3,13 The two software packages have different levels of automation for orienting the myocardium and selecting contours. For this study F I G U R E 8 Example images of the repeated SPECT MBF study, processed with the 1CM and RET models, for which the MBF difference between repeated studies is relatively large.…”

“…Within the processing protocol, one aspect that can introduce variability is the use of manual manipulation of the datasets. (3) In particular, motion-correction of the dynamic image series has been shown improve accuracy of SPECT MBF 1 -increasing the Pearson correlation coefficient with PET MBF from 0.79 to 0.85, but it must be done manually. Automated correction has been developed for PET MBF 4 but these approaches are not suitable for SPECT datasets.…”

“…These measurements have traditionally been performed with positron emission tomography (PET) but advances in single photon emission computed tomography have now enabled accurate MBF measurement with SPECT 1,2 . However, the day‐to‐day repeatability (precision) of SPECT MBF measurements in the same patients is worse than that of PET measurements 3 . Moreover, as development of SPECT MBF has been pursued independently by several different groups, this has led to considerable variability in the acquisition and processing protocols and produced a large range of values for measured MBF.…”

Myocardial perfusion imaging using single-photon emission computed tomography with cadmium-zinc-telluride technology

“…Several articles were concentrated on the practicality of dynamic SPECT using CTZ detectors and the association of fractional flow reserve measurements with cardiac PET and invasive coronary angiography [11]. Several investigations have found that MBF and MFR measurements have acceptable intra-and inter-operator repeatability [53][54][55][56][57][58].…”