BACKGROUND: The clinical significance of single-photon emission computed tomography (SPECT)-derived increase ratio (IR) remains unclear. This study aimed to investigate whether SPECT- IR can diagnose significant coronary...BACKGROUND: The clinical significance of single-photon emission computed tomography (SPECT)-derived increase ratio (IR) remains unclear. This study aimed to investigate whether SPECT- IR can diagnose significant coronary artery disease (CAD), correlate with positron emission tomography (PET)-derived myocardial flow reserve (MFR), and predict the composite endpoint. METHODS: We retrospectively analyzed 60 patients with known or suspected coronary heart disease (CHD) who underwent stress-rest Tc-sestamibi myocardial perfusion SPECT and N-ammonia PET. Global and regional SPECT-IR and PET-MFR were measured. The endpoint of this study was a composite of all-cause mortality and major adverse cardiovascular events. RESULTS: Global and regional IR predicted significant CAD, and IR correlated with their respective MFRs (global: r = .43, r = .18, P < .001; regional: r = .34, r = .12, P < .001). The global IR decreased with advancing CAD severity, as did global MFR. Among nonstenotic vessels, regional IR was significantly lower in patients with MFR <2.0 than in those with MFR ≥2.0. The SPECT-IR may also predict the need for early revascularization as well as PET-MFR. During a median follow-up of 765 days, nine primary events occurred. Using an IR threshold of 1.13, corresponding to an MFR of 2.0, eight of nine patients with events had IR < 1.13. The receiver operating characteristic (ROC) curve analysis of IR showed good predictive ability for adverse events. CONCLUSION: SPECT-IR is associated with PET-MFR and CAD severity. The SPECT-IR may be a potential predictor of adverse outcomes in patients with known or suspected CHD.
BACKGROUND: Colchicine reduces sympathetic denervation after acute myocardial infarction (AMI), yet the COLD-MI trial found no change in myocardial perfusion scintigraphy (MPS). MPS-detected necrotic lesions were limited...BACKGROUND: Colchicine reduces sympathetic denervation after acute myocardial infarction (AMI), yet the COLD-MI trial found no change in myocardial perfusion scintigraphy (MPS). MPS-detected necrotic lesions were limited by early management, and MPS may therefore have lacked the sensitivity to capture subtle colchicine-induced variations in minimal necrosis during the immediate post-stenting period. Myocardial perfusion reserve (MPR), a quantitative indicator of global microvascular function, may overcome these limitations. This ancillary analysis of the COLD-MI trial evaluated whether colchicine improves MPR six months after AMI. METHODS: Forty-five post-AMI patients randomized to colchicine for 30 days or no colchicine underwent quantitative dynamic [99mTc]Tc-tetrofosmin SPECT and [123I]-mIBG imaging at 6 months. MPR was quantified using CZT-SPECT as the stress-to-rest uptake ratio. Secondary endpoints included MPS scoring (SRS, SSS, SDS) and sympathetic innervation assessed by normalized mean segmental activity. Analyses were blinded. RESULTS: Colchicine-treated patients showed significantly higher MPR in remote myocardium than controls (2.37 ± 0.61 vs. 1.92 ± 0.53; P = 0.01). Denervated myocardial surface area in remote regions was also lower with colchicine (43% [29-50] vs. 50% [38-64]; P = 0.04). In infarcted myocardium, MPR did not differ (1.79 ± 0.61 vs. 1.60 ± 0.63; P = 0.35). A non-significant trend toward better preserved innervation was observed (denervation: 46% [35-50] vs. 50% [45-69]; P = 0.09). SRS, SSS, and SDS were similar between groups. CONCLUSIONS: Colchicine significantly increases MPR in remote myocardium six months after AMI, consistent with reduced sympathetic denervation and supporting a microvascular benefit of colchicine post-AMI.
BACKGROUND: A recent phase 3 study of the PET perfusion tracer F-18 flurpiridaz (flurpiridaz) met the primary efficacy endpoint for the detection of CAD, demonstrating statistically higher sensitivity, non-inferior speci...BACKGROUND: A recent phase 3 study of the PET perfusion tracer F-18 flurpiridaz (flurpiridaz) met the primary efficacy endpoint for the detection of CAD, demonstrating statistically higher sensitivity, non-inferior specificity compared to Tc-99m-tetrofosmin/sestamibi SPECT (Tc99m-SPECT) in the general population. This study reports a pre-specified subgroup analysis examining the diagnostic accuracy of flurpiridaz in women. METHODS: Patients with suspected CAD underwent rest-stress flurpiridaz PET and Tc99m-SPECT before invasive coronary angiography in the US, Canada, and Europe. The primary endpoint was sensitivity and specificity by 2 expert readers (majority rule between 3 blinded readers) for the diagnosis of significant CAD defined as a stenosis ≥50%. Secondary endpoints included comparison of the diagnostic performance of flurpiridaz PET and Tc99m-SPECT. RESULTS: 188 women were included in the subgroup analysis. Flurpiridaz met the pre-specified primary endpoint of sensitivity [82.9% (95% CI: 71.4, 94.4), P = 0.0014] and specificity [72.8% (95%CI: 65.6, 80),P = 0.0008]. Flurpiridaz sensitivity was significantly higher than Tc99m-SPECT [82.9% vs 65.9%, difference: 17.1% (-1.5%, 35.6%), P = 0.0448] and specificity was non-inferior [72.8% vs 66%, difference:6.8% (-3.4%, 17.0%) P = 0.0004]. Diagnostic certainty was significantly higher for women undergoing flurpiridaz PET compared to Tc99m-SPECT (82.4% v 48.9%). PET perfusion image quality was better than Tc99m-SPECT for rest and pharmacological stress images (P < 0.0001). The summed difference score was significantly higher for flurpiridaz (5.3 v 3.5). Radiation exposure was significantly lower for flurpiridaz than same day rest/stress Tc99m-SPECT (6.2 v 11.2 mSv). CONCLUSIONS: This pre-specified secondary analysis of the ARORA study in women, demonstrates high diagnostic accuracy of flurpiridaz PET to detect obstructive CAD. In women, the diagnostic performance of flurpiridaz PET for detection of CAD was significantly higher than with 99mTc-SPECT.
BACKGROUND: Visual score (VS) on imaging with technetium-based bone-avid tracers is used to qualify myocardial tracer uptake for diagnosis of transthyretin cardiac amyloidosis (ATTR-CA). While VS can be determined on bot...BACKGROUND: Visual score (VS) on imaging with technetium-based bone-avid tracers is used to qualify myocardial tracer uptake for diagnosis of transthyretin cardiac amyloidosis (ATTR-CA). While VS can be determined on both planar and single photon emission computed tomography (SPECT), the concordance between the 2 techniques has not been formally assessed. METHODS: Cardiac scintigraphy studies with bone-avid tracers performed between November 2017 and January 2024 were evaluated (N = 441; mean age: 73 ± 11 years, 42% women). VS was independently assessed on planar images and SPECT. Myocardial tracer uptake on SPECT was considered as the diagnostic standard. RESULTS: ATTR-CA was confirmed by myocardial tracer uptake on SPECT in 104 patients (24%). Among them, diffuse myocardial tracer uptake was noted in 64% of the patients, focal on diffuse in 26% of the patients and focal in 8% of the patients. When considering VS ≥ 2 on SPECT as indicative of a positive study, the sensitivity, specificity, positive predictive value, and negative predictive value of planar VS was 92%, 77%, 56%, and 98%, respectively. There was weak agreement between planar and SPECT VS (weighted kappa = 0.51). CONCLUSION: There is poor concordance between VS on planar imaging and SPECT. Only SPECT VS should be used to qualify tracer uptake for the confirmation of ATTR-CA.
BACKGROUND: Standard procedure involves acquiring separate computed tomography (CT) scans during rest and stress for attenuation correction of single-photon emission computed tomography (SPECT) myocardial perfusion imagi...BACKGROUND: Standard procedure involves acquiring separate computed tomography (CT) scans during rest and stress for attenuation correction of single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) which results in increased radiation dose for patients. The reduction of one of the CT scans can reduce radiation exposure. We investigated whether a single post-stress CT scan can be used for attenuation correction of both stress and rest MPI SPECT without affecting clinical interpretation. METHODS: A total of 106 consecutive patients underwent diagnostic MPI SPECT-CT with Tc-tetrofosmin using CT-derived attenuation data at stress and rest. We created 106 post-rest perfusion pairs of polar maps reconstructed twice with rest and post-stress CT attenuation data. The similarity between these pairs of maps was assessed in three ways: (1) mathematically, (2) subjectively by 6 independent experienced nuclear medicine physicians, and (3) by categorical analysis of the summed perfusion score (SPS) to evaluate potential changes in clinical interpretation. RESULTS: The Bland-Altman analysis showed no differences in SPS between the pair of maps. The t-test showed no statistically significant differences between the scores of individual myocardial segments. Physicians rated the maps' similarity on average of 9.3 (±0.8) on a scale of 1 to 10, and a function was proposed to describe physicians' predicted responses based on compared pairs of maps. A categorical analysis revealed that approximately 30% of patients changed their SPS category when using 1CT instead of 2CT and that a small subset exhibited shifts large enough to potentially influence interpretation. CONCLUSIONS: Using a single post-stress CT for attenuation correction of both stress and rest MPI SPECT appears feasible in most cases, but careful review is recommended. The method should be applied with caution, particularly when registration quality is suboptimal or when ischemia is clinically suspected.
BACKGROUND: Coronary microvascular dysfunction is implicated in ∼two-thirds of ischaemia with no obstructive coronary artery disease (INOCA) cases and is significant due to its association with a higher risk of major adv...BACKGROUND: Coronary microvascular dysfunction is implicated in ∼two-thirds of ischaemia with no obstructive coronary artery disease (INOCA) cases and is significant due to its association with a higher risk of major adverse cardiac events (MACE). While invasive techniques are the gold standard for diagnosing coronary microvascular dysfunction (CMD), positron emission tomography (PET) offers a noninvasive approach to quantifying myocardial blood flow (MBF) and detecting CMD. This study aimed to quantify myocardial flow reserve (MFR) using PET in INOCA patients to identify CMD and to correlate it with thrombolysis in myocardial infarction (TIMI) and TIMI myocardial perfusion grade (TMPG) angiographic flow grades. METHODS: Thirty INOCA patients with angiographic evidence of non-obstructive coronaries and slow flow were prospectively enrolled and underwent dynamic rest and stress cardiac N-NH PET with MBF and MFR quantification. Patients with MFR values below 2.3 were classified as having CMD. Angiographic flow grades (TIMI and TMPG) were correlated with MFR and MBF. RESULTS: The mean global stress MBF and MFR for the study cohort were 2.54 ± 0.72 mL/minute/gm and 2.91 ± 0.81, respectively. No significant correlation was found between MFR and TIMI (r = -0.140, P = 0.108) or MFR and TMPG (r = -0.06, P = 0.446). Among the participants, 8 (27 %) had reduced global MFR less than 2.3 (mean: 1.80 ± 0.36), indicating CMD. The remaining 22 patients (73 %) had normal MFR values. Within the CMD group, 3 patients had functional CMD with elevated resting MBF, while 5 had classic CMD with blunted hyperaemic response to vasodilator stress. CONCLUSIONS: PET is an excellent noninvasive modality for diagnosing CMD. Coronary slow flow in angiographically normal arteries does not correlate with N-NH PET MFR values and is not a reliable marker for identifying CMD as indicated by the study's findings.