Routine Myocardial Perfusion Imaging Research Articles

Assessing the diagnostic value of left ventricular synchrony indices derived from phase analysis by D-SPECT in identifying obstructive coronary artery disease.

This study aimed to assess the diagnostic efficacy of left ventricular synchrony (LVS) for detecting coronary artery disease (CAD). We explored whether the LVS index derived from phase analysis of D-SPECT provides superior diagnostic value compared to conventional perfusion analysis in identifying obstructive CAD. Patients with suspected or confirmed CAD underwent drug-stress/rest gated D-SPECT myocardial perfusion imaging (MPI) and coronary angiography (CAG). A 50% stenosis was set as the threshold for obstructive CAD. 110 participants were enrolled in this analysis. There were significant differences in phase standard deviation (PSD), phase histogram bandwidth (PHB) and entropy among the four groups. Patients without cardiac disease and those with mild-moderate stenosis exhibited no noticeable contraction asynchrony. However, LVS indices demonstrated a gradual increase with the progression of coronary stenosis when compared to NC (P < 0.001). Obstructive CAD was identified in 43 out of 110 participants (39%). Optimal cutoff values for diagnosing obstructive CAD during stress were determined as 7.6° for PSD, 24° for PHB, and 37% for entropy, respectively. Notably, PSD, PHB, and entropy indices exhibited higher sensitivity compared to MPI. The integration of the stress-induced LVS indices into routine MPI analysis resulted in a significantly greater area under the curve (AUC), leading to improved diagnostic performance and enhanced differential capacity. Stress-induced LVS indices increase with the severity of coronary artery stenosis by D-SPECT phase analysis. Further, the indices-derived phase analysis exhibits superior sensitivity and discriminatory ability compared to MPI in detecting obstructive CAD.

Going beyond summed stress scores: Correlating global and territorial coronary flow reserve by single photon emission tomography with routine myocardial perfusion imaging

(a) BackgroundTechnological advancement in the recent years has enabled the application of single photon emission tomography (SPECT) to evaluate myocardial blood flow (MBF). This method offers increased sensitivity in the assessment of coronary health, quantifiable through non-invasive imaging beyond the more conventional methods such as with myocardial perfusion imaging (MPI). (b) AimsTo correlate MBF, derived by dynamic SPECT, both global and by coronary territories to the summed stress scores (SSS) on conventional MPI. (c) MethodsImages obtained from dipyridamole-gated SPECT MPI stress and rest studies performed on recruited subjects were examined. We calculated the global and regional coronary flow reserve (CFR) via a standard software package, taken as the ratio of stress MBF to rest MBF, using CFR<2.5 as the cut off. (d) ResultsAmongst the 90 recruited subjects (mean age 67 ± 8 years; of which 76% were males), 49% had MPI within normal limits (summed stress score (SSS) 0–3; Left ventricular ejection fraction (LVEF) > 50%). We observed a progressive reduction in global and regional CFR across the normal SSS category to that of severely abnormal (SSS >13). Reduced global CFR with correspondent lower CFR across the regional arteries were detected in scans within normal limits of MPI scans in subjects who were older (69 ± 7 vs. 62 ± 9 years, p = 0.034). Decreasing CFR was significantly associated with increasing age across the regional arteries. (e) ConclusionIn our study we depict the global and regional MBF values obtained via SPECT MPI in correlation to the respective SSS categories. Our data proposes that dynamic SPECT has a part in refining cardiac risk stratification, particularly in the older adult population, who are at greater risk.

SPECT for risk stratification in patients with advanced liver disease

BackgroundPatients with advanced liver disease (ALD) have unique hemodynamics including high resting cardiac output and low systemic vascular resistance which may reduce the sensitivity of pharmacological myocardial perfusion imaging (MPI). MPI is frequently ordered for patients with ALD if liver transplantation is being considered. Because of the limited data on effectiveness of MPI in the ALD population, we conducted this cohort study focused on cardiac outcomes after pharmacological MPI. MethodsWe conducted a cohort study comparing normal versus abnormal MPI among 454 patients with ALD between 1/1/2011 and 06/01/2021 at a single tertiarycare academic medical center. Abnormal MPI was defined as summed stress score > 2 on LVEF < 40 %. The primary outcome was to compare the frequency of major adverse cardiovascular events (MACEs) among ALD patients with and without abnormal MPI. Secondary outcome included individual components of MACE analyzed by chi square. Kaplan-Meier survival curves and a logistic-regression model of associations with MACE were also performed. ResultsIn this cohort, 58 patients were observed to have an abnormal MPI. Baseline characteristics between the groups were similar, except prior coronary disease, which was more common among the abnormal MPI group (risk ratio 2.07, 95 % confidence interval 1.30–3.30, P = 0.003). MACE was more common in the group with abnormal MPI (n = 24, 41.4 % versus normal MPI n = 104, 26.3 %, P < .001). No difference in MACE was observed when stratified by liver disease type. In the logistic regression model, diabetes mellitus, stage 3 chronic kidney disease, and summed stress score >2 were retained as being associated with MACE. ConclusionsOur data suggest that MPI remains an effective test for identifying ALD patients at higher risk of mortality and cardiac events. Further study is needed to understand whether a strategy of routine MPI for liver transplant candidates effectively improves long term survival.

P2491Physiologic assessment for coronary artery disease with myocardial perfusion imaging is clinically more relevant when selecting diabetic with high risk features

Abstract Background Based on previously published data, routine myocardial perfusion imaging in diabetics is not recommended. Selecting patients with diabetes and high risk cardiovascular features could be important to improve the yield of physiologic assessment of the coronary arteries disease and subsequently patient outcome. Purpose We posed the question whether nuclear stress testing has a better yield by selecting diabetic individuals with known vascular disease. Methods We analyzed records for 15,392 diabetics from 1996 to 2009 with and without vascular disease. Vascular disease is defined as carotid vascular disease, abdominal aortic aneurysm, or peripheral arterial disease. There was 2457 myocardial perfusion studies performed within 2 years of the vascular evaluation. We studied the results of these stress testing in each group and evaluated for the presence of myocardial ischemia. Multivariate Cox proportional regression was used to calculate hazard ratios (HR) with 95% confidence intervals after adjusting for age, gender. Results Of those who underwent myocardial perfusion studies 1819 were diabetic with vascular disease group A (mean age 67.8, 70.5% female) and 638 were diabetic without vascular disease group B (mean age 64.5 years, 67.1% female). There was at least one reversible defect suggest myocardial ischemia in 225 and 758 studies in group A and B respectively. Comparing outcome based on the presence of myocardial ischemia in group A without vascular disease, those with vascular disease did have an increased risk of myocardial infarction (adjusted HR: 1.630, 95% CI: 1.281–2.074) and death (adjusted HR: 1.646, 95% CI: 1.413–1.918). Conclusion Myocardial perfusion imaging is a reasonable test in patients with diabetes and vascular disease. The presence of myocardial ischemia is more common and is associated with worse cardiovascular outcome. Acknowledgement/Funding None

USVAH Study Demonstrates Statistically Significant Improvement in Diagnosis and Care of U.S Veterans Using FMTVDM – FHRWW©℗ “Quantitative” Nuclear Imaging. The Era of Truly Quantitative Stress- First, Stress-Only Imaging has begun!

Background: Myocardial perfusion imaging (MPI) has evolved over the last several decades with improvements in equipment and isotopes. Despite these limitations sensitivity and specificity of this study remains 65%-85% principally due to “qualitative” interpretation of the results. Numerous investigators have recommended changes in protocols and quantification of data to increase the diagnostic accuracy of this non-invasive physiologic test. Initial investigations have demonstrated the ability to “quantitatively” measure isotope redistribution with planar, SPECT and PET using FMTVDM©℗. This study was designed to compare the diagnostic and treatment outcomes of U.S. Veterans undergoing conventional “stress-rest” “qualitative” imaging using Technetium 99m isotopes (Sestamibi and Myoview) compared with FMTVDM©℗ “quantification” isotope redistribution using a single dose of the isotope.Methods: Forty-one U.S. Veterans were studied using pharmacologic and exercise stress approaches with either Sestamibi or Myoview following routine MPI Imaging protocols compared with FMTVDM©℗. The results were compared with coronary angiography.Result: Angiographic coronary artery disease (CAD) was defined using both 50% and 70% diameter narrowing/ stenosis (%DS). Accuracy of a “qualitative” (yes/no) test in the determination of the presence or absence of CAD is measured by the ability of the test to find CAD when present (sensitivity) and to show that CAD is not present (specificity) when absent, based upon the arbitrarily assigned value for %DS. The sensitivity, specificity and accuracy of “qualitative” MPI assessment of 50% DS CAD was 50.0%, 88.2% and 70.7% for the left coronary artery system and 29.2%, 64.7% and 43.9% respectively for the right coronary artery system. These values improved to 59.1%, 89.5% and 73.2% for the left coronary artery system and 64.3%, 85.2% and 78.0% respectively for the right coronary artery system when 70%DS was used as the cutoff for CAD. No differences noted between either of the technetium 99m isotopes or cameras used for either the “qualitative” or “quantitative” (FMTVDM©℗) methods. FMTVDM©℗ provides the First Ever “quantitative” Nuclear Cardiology MPI test, which consequently defines CAD not on a yes/no basis, but “quantitatively.” As such, the accuracy of FMTVDM©℗ must be compared first to a “quantitative” measure which is known; viz. isotope decay using TFM. Results of FMTVDM©℗ is then not simply a yes/no result, but rather a “quantitative” value which places the “extent” of CAD on a measured continuum much as a coronary angiogram would, specifically a quantitative coronary angiogram (QCA). FMTVDM©℗ demonstrated a statistically significant relationship between CAD and %DS (r=0.75, p < 0.001).Conclusion: Modern Nuclear Cameras have relied completely upon “quality” control methods, which do exactly that; they provide for “qualitative” control but not “quantitative” control. The accuracy of the cameras ability to correctly count the resulting scintillations from which “quantitative” analysis and even “qualitative” images are displayed for clinician interpretation are dependent, has never been established or used in either the experimental or clinical areas of Medicine. This study demonstrated the importance of first using TFM from the FMTVDM©℗ for “quantitative” camera calibration and correction prior to conducting MPI. Even with the correction of the “quantitative” errors in the Nuclear Cameras, errors in “qualitative” MPI resulted in a conservative estimate of misdiagnosis of CAD 35% of the time. These errors result in potential life threatening CAD being missed as demonstrated here. This same CAD is accurately measured using the new “quantitative” MPI test (FMTVDM©℗), which accurately “quantify” the extent of CAD. FMTVDM©℗ provides the first “quantitative” Nuclear Cardiology and Medicine test, ushering in the era of “machine learning” and “quantitative” Nuclear Cardiology and Medicine providing accurate, reproducible measurement of CAD in less time and with less radiation than the prior “qualitatively” applied method of “physician interpretation” of CAD, reducing healthcare costs and improving patient throughput and clinical management.

Transient global amnesia and hemiplegic migraine following MPI with dipyridamole: a case report

Myocardial perfusion imaging (MPI) is a common form of cardiac radionuclide testing used in acute coronary syndromes (ACS) to assess myocardial perfusion when the heart is at rest and under stress. Dipyridamole is used in some UK nuclear medicine departments to simulate the effects of physiological stress on the cardiovascular system. This article reports an idiosyncratic reaction experienced by the author’s mother, a 71 year old lady called Sally, following routine MPI with dipyridamole, which manifested as severe headache and an episode of transient global amnesia (TGA), followed by the delayed onset of stroke-like symptoms which were later attributed to a migrainous event. Reference is made to limited evidence within the literature to support the link between dipyridamole and these adverse effects. It is recommendation that pre-MPI screening procedures be adapted to incorporate methods of identifying those patients at increased risk of experiencing a similar adverse reaction to that described.

P103 Clinical utility of myocardial perfusion imaging in liver transplant assessment patients

IntroductionCoronary artery disease (CAD) is associated with increased short-term morbidity and mortality following liver transplantation. As a result, the AASLD recommends that high risk individuals should undergo CAD evaluation during...

Integrated assessment of coronary anatomy and myocardial perfusion using a retractable SPECT camera combined with 64-slice CT: initial experience

We evaluated a prototype SPECT system integrated with multidetector row CT (MDCT) for obtaining complementary information on coronary anatomy and hemodynamic lesion significance. Twenty-five consecutive patients with known or suspected coronary artery disease (CAD) underwent routine SPECT myocardial perfusion imaging (MPI). All patients also underwent repeat MPI with a mobile SPECT unit which could be attached to a 64-slice MDCT system. Coronary CT angiography (cCTA) was performed without repositioning the patient. Investigational MPI was compared with routine MPI for detection of myocardial perfusion defects (PD). Two observers diagnosed presence or absence of CAD based on MPI alone, cCTA alone, and based on combined MPI and cCTA with fused image display. In 22/24 patients investigative MPI corresponded with routine MPI (r = 0.80). Stenosis >or= 50% at cCTA was detected in 6/24 patients. Six out of 24 patients had PD at regular MPI. Three of these six patients had no significant stenosis at cCTA. Three out of 19 patients with normal MPI studies had significant stenosis at cCTA. Our initial experience indicates that the integration of SPECT MPI with cCTA is technically feasible and enables the comprehensive evaluation of coronary artery anatomy and myocardial perfusion with a single instrumental setup.

Randomized, single-blind, factorial design study of the interaction of food and time on intestinal activity in 99mTc-tetrofosmin stress myocardial perfusion scintigraphy

Intestinal activity at the inferior myocardial wall represents an issue for assessment of myocardial perfusion imaging (MPI) with 99mTc-labelled tracers. The aim of this study was to investigate the effect of time and food on upper abdominal activity in 99mTc-tetrofosmin MPI. The study population consisted of 152 consecutive patients referred for routine MPI. All patients underwent 2-day stress-rest 99mTc-tetrofosmin single-photon emission computed tomography MPI. Before stress testing, patients were randomized in a factorial design to four different regimens. Group A: early scan (image acquisition initiated within 15 min after injection of the tracer) and no food; group B: early scan and food (two pieces of white bread with butter and a minimum of 450 ml of water); group C: late scan (image acquisition 30-60 min after injection of the tracer) and no food; and group D: late and scan with food. Patients underwent standard bicycle exercise or pharmacological stress test. The degree of upper abdominal activity was evaluated by trained observers blinded to the randomization code. The primary endpoint was the proportion of accepted scans in the intention-to-treat population in stress MPI. The results showed statistical significant impact on both time and food on upper abdominal activity. The primary endpoint showed that the acceptance rate improved from 55% in group A to 100% success rate in group D. An early scan reduced the acceptance rate by 30% versus a late scan [hazard ratio 0.70, 95% confidence interval 0.58-0.84; P<0.0001], whereas the addition of food improved the success rate versus no food by 27% (hazard ratio 1.27, 95% confidence interval 1.07-1.51; P=0.006). No significant interaction between food and time was observed. An analysis of accepted scans according to the actual scan time and food consumption confirmed the findings of the intention-to-treat analysis. In addition, similar findings were seen in 116 of 152 patients with a rest MPI (success rate of 53% in group A vs. 96% in group D). A combination of solid food and water administered after injection of the tracer and delayed image acquisition led to significant and clinically relevant decrease of interfering upper abdominal activity in 99mTc-tetrofosmin MPI.

Clinical relevance of left ventricular volume assessment by gated myocardial SPET in patients with coronary artery disease.

Coronary artery disease (CAD) is the leading cause of mortality in the Western world. Multiple parameters have been investigated to predict prognosis in CAD patients. The prognostic value of the left ventricular ejection fraction (LVEF) in patients with CAD is well established. More recently, left ventricular (LV) volumes have also shown prognostic value. Due to the favourable imaging characteristics of technetium-99m (high count density), the development of (99m)Tc-labelled myocardial perfusion tracers has made it possible to perform an electrocardiogram-gated acquisition during routine myocardial perfusion imaging. This enables assessment of LVEF and LV volumes during myocardial perfusion scintigraphy. This review considers the possible prognostic abilities of LV volume assessment by gated cardiac SPET.

Influence of arm positioning on tomographic thallium-201 myocardial perfusion imaging and the effect of attenuation correction.

Lateral attenuation in single-photon emission tomography (SPET) myocardial perfusion imaging (MPI) has been attributed to the left arm if it is held by the patient's side during data acquisition. As a result MPI data are conventionally acquired with the arms held above the head. The aims of this study were to determine the effect of imaging arms down on reconstructed tomographic images depicting regional myocardial thallium-201 distribution and to assess whether attenuation-corrected (AC) myocardial perfusion images acquired arms down could replace uncorrected (NC) images acquired arms up for routine clinical service. Twenty-eight patients referred for routine MPI underwent sequential 180 degrees emission/transmission imaging for attenuation correction using an L-shaped dual-headed gamma camera (GE Optima) fitted with two gadolinium-153 scanning line sources. Delay data were acquired twice: once supine with the arms up and then supine with the arms down. Detector radius of rotation (ROR) for arms up and arms-down studies was recorded. For each data set, count density was measured in 17 segments of a polar plot and segmental uptake expressed relative to study maximum. Oblique images were assessed qualitatively by two observers blinded to study type for tracer distribution and overall quality. Transmission maps were assessed for truncation. Mean detector ROR was 190 mm for arms-up studies and 232 mm for arms-down studies (P<0.05). Population mean segmental relative uptake values for NC arms-up studies were higher than for NC arms-down studies, with the greatest difference seen anterolaterally. Nevertheless, the majority (24/28) of oblique NC arms-up and NC arms-down images appeared similar and only four (14%) NC arms-down studies showed additional areas of reduced count density (one anterior and three lateral). Corresponding AC arms-down studies showed that count density within the anterior defect improved to normal but the lateral reductions persisted, and in two of these three studies the arms-down transmission map was distorted. Population mean segmental relative uptake values for NC arms-down studies were lower than for AC arms-down studies apart from three anterolateral segments where NC arms-down values were higher. Of 28 AC arms-down studies, 11 (39%) were of reduced quality compared with NC arms-up studies because of poorer spatial resolution and because AC enhances liver activity compared with NC. It is concluded that arm positioning influences reconstructed tomographic images depicting regional 201T1 distribution, particularly anterolaterally. There is lateral undercorrection in approximately 10% of AC arms-down studies, possibly because of attenuation map truncation. Image quality is reduced in about one-third of AC armsdown studies compared with NC arms-up studies. These data suggest that this attenuation correction method is not sufficiently robust to allow routine acquisition of MPI data with the arms down.

Technetium-99m Sestamibi-Avid Pulmonary Sclerosing Hemangioma Discovered during Myocardial Perfusion Imaging

Technetium-99m sestamibi is a standard myocardial perfusion agent used also for tumor imaging. A sestamibi-avid sclerosing hemangioma, a rare benign tumor of lung, was discovered during routine myocardial perfusion imaging.