Quantitative coronary arterial stenosis assessment by multidetector CT and invasive coronary angiography for identifying patients with myocardial perfusion abnormalities

Background

Semi-quantitative stenosis assessment by coronary CT angiography only modestly predicts stress-induced myocardial perfusion abnormalities. The performance of quantitative CT angiography (QCTA) for identifying patients with myocardial perfusion defects remains unclear.

Methods

CorE-64 is a multicenter, international study to assess the accuracy of 64-slice QCTA for detecting ??50% coronary arterial stenoses by quantitative coronary angiography (QCA). Patients referred for cardiac catheterization with suspected or known coronary artery disease were enrolled. Area under the receiver-operating-characteristic curve (AUC) was used to evaluate the diagnostic accuracy of the most severe coronary artery stenosis in a subset of 63 patients assessed by QCTA and QCA for detecting myocardial perfusion abnormalities on exercise or pharmacologic stress SPECT.

Results

Diagnostic accuracy of QCTA for identifying patients with myocardial perfusion abnormalities by SPECT revealed an AUC of 0.71, compared to 0.72 by QCA (P?=?.75). AUC did not improve after excluding studies with fixed myocardial perfusion abnormalities and total coronary arterial occlusions. Optimal stenosis threshold for QCTA was 43% yielding a sensitivity of 0.81 and specificity of 0.50, respectively, compared to 0.75 and 0.69 by QCA at a threshold of 59%. Sensitivity and specificity of QCTA to identify patients with both obstructive lesions and myocardial perfusion defects were 0.94 and 0.77, respectively.

Conclusions

Coronary artery stenosis assessment by QCTA or QCA only modestly predicts the presence and the absence of myocardial perfusion abnormalities by SPECT. Confounding variables affecting the relationship between coronary anatomy and myocardial perfusion likely account for some of the observed discrepancies between coronary angiography and SPECT results.     

The site of acute myocardial infarction is related to the coronary territory of transient defects on prior myocardial perfusion imaging

Background

Prior studies have established the prognostic value of myocardial perfusion imaging. In particular, the presence and extent of transient defects have been shown to predict future cardiac events including acute myocardial infarction. However, the relationship between the location of the perfusion defect and the site of subsequent myocardial infarction remains unclear.

Methods and Results

Review of prior records of consecutive patients admitted with acute myocardial infarction identified 34 patients whose prior myocardial perfusion imaging studies had demonstrated transient defects and no interval revascularization. The coronary artery territory of the transient defects was identified and related to the site of subsequent acute myocardial infarction. To reduce the potentially confounding effect of progression of coronary artery disease between the time of the myocardial perfusion imaging study and subsequent infarction, patients were divided into those less than 2 years and those 2 years or greater between imaging and infarction. Among patients with a transient defect and less than 2 years between infarction and imaging, 11 (79%) of 14 had a myocardial infarction in the same coronary territory as their prior transient defect (p<0.0005). This association decreased to only five (25%) of 20 when the interval was 2 years or greater (difference not significant). Among 22 patients who had undergone prior coronary angiography, myocardial infarction occurred in the same coronary territory as the most severe angiographic stenosis in 12 (54%). The association was not related to the time interval between angiography and infarction.

Conclusions

There is a strong association between the coronary territory of transient defects on myocardial perfusion imaging and the site of subsequent myocardial infarction when the duration is less than 2 years. These observations support the concept that the hemodynamic significance of a coronary lesion is an important factor in the pathophysiology of acute myocardial infarction.     

Does location matter? Prognostic value of single-photon emission computed tomography myocardial perfusion imaging by vascular territory

Background

The location of a myocardial perfusion abnormality frequently affects clinical decision making, especially if the left anterior descending artery (LAD) territory is involved. The purpose of this study was to determine whether the location of abnormalities on single-photon emission computed tomography (SPECT) imaging affects outcomes.

Methods

We retrospectively analyzed 21,294 consecutive patients with known or suspected coronary artery disease who underwent exercise or pharmacological stress SPECT over a 10-year period. Using the ASNC 17-segment model, 2 observers interpreted images with regards to defect severity, size, and reversibility. The summed stress score (SSS) was used in relation to vascular territories [LAD, right coronary artery (RCA), and left circumflex artery (LCx)]. All patients were followed over a mean period of 2.5?±?2?years for cardiac events (cardiac death or non-fatal myocardial infarction).

Results

Of the enrolled patients, 5,676 had single-vessel territory defects with a mean SSS of 4.3?±?2.8. Cardiac event-free survival curves revealed no significant difference between the 3 locations (LAD, RCA, and LCx) (P?=?.235). When compared by mild (2-3), moderate (4-8), or severe (>8) SSS, outcomes between the 3 groups were again similar. There were 2,907 patients with two-vessel territory defects with a mean SSS of 10.8. Outcomes were similar between the following 2 groups: two-vessel with LAD involvement and two-vessel without LAD involvement (P?=?.558).

Conclusion

In patients with single- or two-vessel territory perfusion abnormalities with similar size and severity of perfusion defects, the location of defect did not impact future cardiac events. Location of myocardial perfusion defect on SPECT imaging may not be helpful in clinical decision making.     

82Rb PET myocardial perfusion imaging is superior to 99mTc-labelled agent SPECT in patients with known or suspected coronary artery disease

Purpose

We compared the quality, interpretive confidence and interreader agreement between SPECT and PET myocardial perfusion imaging (MPI) in the same group of patients.

Methods

The study group comprised 27 patients (age 55?±?8.5?years, 12 men) with known or suspected coronary artery disease (CAD) who had undergone gated rest/stress MPI with ^99mTc-labelled agent SPECT (with and without attenuation correction, AC), and subsequent clinical confirmation with ⁸²Rb PET. Three experienced readers blinded to the clinical information interpreted all MPI studies.

Results

Interreader agreement was significantly superior for PET studies than for SPECT studies. Following consensus interpretation, the quality of 22?% of the non-AC SPECT studies, 33?% of the AC SPECT studies and 63?% of the PET studies was assessed as excellent or good (p?=?0.016). Interpretations were definitely normal or abnormal in 7?% of non-AC SPECT studies, 30?% of AC SPECT studies and 85?% of PET studies (p?=?0.046). In 13 patients who had received either invasive coronary angiography or CT angiography with no significant CAD, the true-positive rate for significant CAD was higher for PET, and the true-negative rate was equal for PET and AC SPECT, and lower for non-AC SPECT.

Conclusion

⁸²Rb PET MPI, used as a confirmatory test after SPECT, offers improved image quality, interpretive confidence and interreader agreement.     

Coronary angiographic rates after stress single-photon emission computed tomographic scintigraphy

Background

There is speculation that coronary angiography may be oversued for the assessment of coronary artery disease. Because of its proved ability to differentiate high- and low-risk subsets of patients with coronary artery disease, myocardial perfusion scintigraphy should be an effective strategy in patient selection for angiography. This retrospective clinical study analyzed the relation between scintigraphic findings and subsequent angiography.

Methods and Results

Coronary angiographic rates were determined by following up on all stress single-photon emission computed tomographic (SPECT) myocardial perfusion studies performed in a cardiology practice nuclear laboratory during a 26-month interval. All patients were followed up for at least 3 months; mean follow-up was 8.9 months. Subsequent angiography was determined from catheterization laboratory logs, medical records, and telephone contact. Scintigraphic studies were graded according to presence or absence of reversible perfusion defects, affected coronary territories, and lung uptake of ²⁰¹Tl. Scans were categorized high risk if more than two of the following three criteria were met: reversibility of left anterior descending or multivessel distributions or abnormal lung uptake of thallium. Of 4162 studies, 60% had reversible perfusion defects. Of such studies, 32% were followed up by angiography versus 3.5% without reversible defects. Among studies with reversible defects, the subsequent angiography rate was 60% for those showing high-risk reversibility, compared with 9% for all other studies demonstrating reversibility. Multivariate logistic regression identified high-risk reversibility (odds ratio 20.96) and any reversibility (odds ratio 8.22) as the strongest predictors of angiography. Other correlates of lesser statistical significance were angina and absence of prior infarction or coronary bypass.

Conclusion

In this large retrospective study, the results of SPECT scintigraphy overpowered all other clinical and treadmill characteristics in determining the likelihood of subsequent coronary angiography. Only rarely were patients categorized as relatively low risk by scintigraphy referred for angiography. As such, SPECT scintigraphy as used in a private practice, self-referral environment appears to be effective in stratifying potential candidates for coronary angiography.     

Diagnostic performance of stress myocardial perfusion imaging for coronary artery disease: a systematic review and meta-analysis

Objectives

To determine and compare the diagnostic performance of stress myocardial perfusion imaging (MPI) for the diagnosis of obstructive coronary artery disease (CAD), using conventional coronary angiography (CCA) as the reference standard.

Methods

We searched Medline and Embase for literature that evaluated stress MPI for the diagnosis of obstructive CAD using magnetic resonance imaging (MRI), contrast-enhanced echocardiography (ECHO), single-photon emission computed tomography (SPECT) and positron emission tomography (PET).

Results

All pooled analyses were based on random effects models. Articles on MRI yielded a total of 2,970 patients from 28 studies, articles on ECHO yielded a sample size of 795 from 10 studies, articles on SPECT yielded 1,323 from 13 studies. For CAD defined as either at least 50?%, at least 70?% or at least 75?% lumen diameter reduction on CCA, the natural logarithms of the diagnostic odds ratio (lnDOR) for MRI (3.63; 95?% CI 3.26–4.00) was significantly higher compared to that of SPECT (2.76; 95?% CI 2.28–3.25; P?=?0.006) and that of ECHO (2.83; 95?% CI 2.29–3.37; P?=?0.02). There was no significant difference between the lnDOR of SPECT and ECHO (P?=?0.52).

Conclusion

Our results suggest that MRI is superior for the diagnosis of obstructive CAD compared with ECHO and SPECT. ECHO and SPECT demonstrated similar diagnostic performance.

Key Points

? MRI can assess myocardial perfusion. ? MR perfusion diagnoses coronary artery disease better than echocardiography or SPECT. ? Echocardiography and SPECT have similar diagnostic performance. ? MRI can save coronary artery disease patients from more invasive tests. ? MRI and SPECT show evidence of publication bias, implying possible overestimation.     

Evaluation of regional myocardial perfusion in patients with severe left ventricular dysfunction: Comparison of 13N-ammonia PET and 99mTc sestamibi SPECT

Objective

Positron emission tomography (PET) scanning with ¹³N-ammonia and ¹⁸FDG is well established for the detection of myocardial viability. Due to the limited availability of PET facilities, recent studies have combined technetium 99m sestamibi single photon emission computed tomography (SPECT) with ¹⁸FDG PET or ¹⁸FDG SPECT. This approach enables simultaneous assessment of regional myocardial blood flow and metabolism and substantially increases the capacity for viability detection. To validate whether ^99mTc-Sestamibi SPECT can replace ¹³N-ammonia PET, we compared these two modalities in patients with severe left ventricular dysfunction due to coronary artery disease.

Materials and Methods

Thirty-one patients (mean age 57±8 years; mean ejection fraction 27%±8%) with angiographically verified coronary artery disease were included. In random order, ammonia-PET and sestamibi-SPECT scans were performed. In a 20-segment model of the left ventricle, two blinded observers scored a total of 610 segments on a five-point scale. In a subset of 20 patients, 400 segments were scored twice to evaluate the observer variations of the two techniques. Segmental score differences were used to compare the imaging modalities. The impact on viability detection was assessed by combining the two flow tracers with FDG PET.

Results

Segmental comparison of the PET and SPECT studies yielded similar (difference ≤1) results in 74% of segments, reflecting regional concordance values in the lateral, apical, anterior, septal, and inferior myocardial walls of 86%, 82%, 71%, 66%, and 63%, respectively. The differences in the septal and inferior walls were primarily due to overestimation of perfusion defects by sestamibi SPECT, which yielded a higher proportion of mismatch patterns in those regions. The overall observer variations of the PET and SPECT studies were 7.5% and 5.8%.

Conclusion

Myocardial perfusion imaging with ¹³N-ammonia PET and ^99mTc-sestamibi SPECT yielded similar results in patients with severe left ventricular dysfunction, except for the septal and inferior regions. In these regions, SPECT tended to overestimate perfusion defects. Hence, attenuation correction should be considered when combining FDG PET and sestamibi SPECT for diagnosing myocardial viability to avoid overestimation of mismatch patterns in those regions.     

Impact on exercise single-photon emission computed tomographic thallium imaging on patient management and outcome

Background

Stress perfusion imaging is useful in risk stratification of patients with known or suspected coronary artery disease. In the current era of managed health care, there is a need to provide data on patient outcome.

Methods and Results

This study examined the impact of exercise single-photon emission computed tomographic (SPECT) thallium imaging on patient management (the subsequent need for coronary angiography and revascularization) and outcome (the occurrence of hard cardiac events defined as cardiac death or nonfatal acute myocardial infarction) in 2700 patients who were being evaluated for diagnostic purposes. None of the patients had previous coronary angiography, coronary revascularization, or Q-wave myocardial infarction. The SPECT images were normal in 2027 patients (group 1) and abnormal in 673 patients (group 2). Within 6 months after thallium imaging 53 patients in group 1 (3%) and 242 patients in group 2 (36%) underwent coronary angiography (p=0.0001). The patients who underwent coronary angiography had higher pretest probability of coronary disease (group 1) or more perfusion defects (group 2) than patients who did not (p=0.0001 each). Coronary revascularization within 3 months of coronary angiography was performed in 1 of the 53 patients (2%) in group 1 and in 87 of 242 patients (30%) in group 2 (p=0.0001). Among the remaining patients who had coronary angiography but were medically treated there were no hard cardiac events in group 1 but there were 15 events in group 2 (p=0.02).

Conclusions

The results of exercise SPECT thallium imaging are important in patient management and outcome. Coronary angiography, coronary revascularization and events are rare in patients with normal exercise SPECT thallium images.     

Combined quantitative analysis of attenuation corrected and non-corrected myocadial perfusion SPECT: Method development and clinical validation

Background  

Attenuation corrected myocardial perfusion SPECT (AC-MPS) has been demonstrated to improve the specificity of detecting coronary artery disease (CAD) by visual analysis which utilizes both non-corrected (NC) and AC data. However, the combined automated quantification of NC and AC-MPS has not been previously described. We aimed to develop a combined quantitative analysis from AC and NC data to improve the accuracy of automated detection of CAD from AC-MPS.     

Electrocardiographic changes during vasodilator SPECT myocardial perfusion imaging: Does it affect diagnosis or prognosis?

Background

Significance of electrocardiographic (ECG) changes during vasodilator stress myocardial perfusion imaging (MPI) is controversial. We examined the diagnostic and prognostic significance of ECG changes during vasodilator single photon emission computerized tomography (SPECT) MPI.

Methods

We studied consecutive patients who underwent vasodilator SPECT MPI from 1995 to 2009. Patients with baseline ECG abnormalities, previous history of coronary artery bypass graft surgery or myocardial infarction (MI) were excluded. Significant coronary artery disease (CAD) was defined as >70% stenosis of any vessel or ??50% stenosis of left main. Mean follow-up was 2.4?±?1.5?years for cardiac events (cardiac death and non-fatal MI).

Results

Of patients in the diagnostic cohort, ST depression was associated with increased incidence of CAD with abnormal (P?=?.020 and P?<.001) but not in those with normal perfusion (P?=?.342). Of 3,566 patients with follow-up in the prognostic cohort, including 130 (5.0%) with ST depression and normal perfusion, the presence of ST depression ??1?mm did not affect the outcomes in any summed stress score category.

Conclusions

ST depression ??1?mm during vasodilator SPECT MPI is associated with CAD in patients with abnormal perfusion, but provides no additional risk stratification beyond concomitant perfusion imaging, including those with normal studies.     

The significance of transient ischemic dilation in the setting of otherwise normal SPECT radionuclide myocardial perfusion images

Background

Transient ischemic dilation (TID) in the setting of an abnormal SPECT radionuclide myocardial perfusion imaging (MPI) study is considered a marker of severe and extensive coronary artery disease (CAD). However, the clinical significance of TID and its association with CAD in patients with an otherwise normal MPI study is unclear.

Methods

From a database of patients who underwent MPI over a 9-year period, 96 without known cardiac history who had normal image perfusion patterns, and who underwent coronary angiography within 6 months, were identified. TID quantitative values were derived. To adjust for varying stress and image protocols, a TID index based on published threshold values was derived for each patient, with >1 considered as TID. We examined the relationship of TID to the presence/extent of CAD, and to a CAD prognostic index. TID was also correlated with patient survival. To address referral bias, survival in a separate cohort of 3,691 patients with a normal perfusion MPI who did not undergo angiography in the 6-month interval was correlated with the presence and severity of TID.

Results

For 28 (29.2%) patients with normal MPI perfusion patterns but with TID, there was no increased incidence of CAD, multivessel or left main disease, or a higher prognostic index compared with no TID. In addition, there was no increased mortality associated with TID in both the angiography cohort and in the patients who did not undergo immediate angiography.

Conclusions

TID in patients with an otherwise normal SPECT MPI study does not increase the likelihood of CAD, its extent or severity, and is not associated with worsened patient survival.     

Prospective clinical comparison of non-corrected and attenuation- and scatter-corrected myocardial perfusion SPECT in patients with suspicion of coronary artery disease

Attenuation artefacts decrease the specificity of myocardial perfusion single-photon emission computed tomography (SPECT). In this paper, the results of a prospective study evaluating the clinical applicability of attenuation and scatter correction in myocardial perfusion SPECT are presented. Of 607 patients in whom post-stress 99mTc-tetrofosmin myocardial perfusion SPECT was performed due to suspicion of coronary artery disease, 99 also underwent coronary angiography (CAG). A simultaneous emission/transmission acquisition was performed. A multiple linear array of 153Gd sources and four independent energy windows were used for attenuation and scatter correction. A blind separate analysis of non-corrected (NC) and attenuation- and scatter-corrected (AC-SC) images was performed with scores of zero (no uptake) to three (normal uptake). The final diagnosis was based on CAG findings, and stenoses of > or =70% were considered to be significant. NC images had a sensitivity of 92% and a specificity of 46%. In AC-SC images, the sensitivity decreased to 76%, but the specificity increased to 71%. The decrease in the sensitivity of AC-SC images was observed in all three coronary regions. Attenuation and scatter correction increased the specificity in the right coronary region, but decreased the specificity in the left anterior descending coronary region. In 13 of the 99 patients, AC-SC images showed false positive findings due to count deficiency in the anterior wall with normal CAG. The size of perfusion defects was decreased in AC-SC images (from 5.01 +/- 2.74 to 3.15 +/- 2.50 segments). The severity of perfusion defects was higher in NC (1.10 +/- 0.60) than in AC-SC (1.28 +/- 0.56) images. The combined evaluation of NC and AC-SC images was in agreement with the CAG findings in 79% of patients. It can be concluded that, when compared with NC images, AC-SC images improved the specificity in the right coronary region and decreased the sensitivity in all three coronary regions. Attenuation and scatter correction may generate anterior wall defects with normal CAG. The analysis of AC-SC images cannot be used alone for the diagnosis of coronary artery disease. In the clinical setting, combined NC and AC-SC images are recommended for the evaluation of post-stress myocardial perfusion SPECT.     

Evaluation of myocardial perfusion in patients with Behçet’s disease

Aim

To estimate the prevalence of silent myocardial ischemia (SMI) in patients with Behçet’s disease (BD) and to identify a subgroup of patients at higher risk for the presence of SMI. Materials and Methods We evaluated 41 patients (mean age 42.8 ± 12.3 years) with BD and 35 healthy control subjects. Treadmill exercise test and thallium-201 myocardial perfusion single photon emission computed tomography (SPECT) were performed in all subjects. Coronary angiography was performed in all patients with a diagnosis of SMI in Behçet’s group.

Results

All subjects had normal resting electrocardiograms. Eight patients with BD (19.5%) had evidence of ischemia on exercise testing and myocardial perfusion SPECT. Only one SMI positivity (2.9%) was recorded in the control group. Significant coronary stenosis was not found with coronary angiography in the patients with a diagnosis of SMI in Behçet’s group. SMI positivity was recorded in 2 of 18 female patients (11%) and in 6 of 23 male patients (26.1%) with BD (p = 0.429). The mean duration of BD was 13.8 ± 2.6 years in patients with SMI and 7 ± 4.1 in patients without it (p < 0.001). Seven of the 8 patients (87.5%) with SMI had a duration of BD of greater than 10 years.

Conclusions

The results of this study show that the prevalence of SMI is high in patients with BD. Based on our findings, screening with myocardial perfusion scintigraphy may be recommended for patients with duration of BD greater than 10 years.     

Diagnostic accuracy of dipyridamole technetium 99m-labeled sestamibi myocardial tomography for detection of coronary artery disease

Background

The diagnostic accuracy of exercise ^99mTc-labeled sestamibi and intravenous dipyridamole ²⁰¹Tl-labeled myocardial tomography is established. The accuracy of dipyridamole stress ^99mTc-labeled sestamibi myocardial tomography for the detection of coronary artery disease has not been reported.

Methods and Results

Our purpose was to determine the diagnostic accuracy of same-day, rest-dipyridamole stress ^99mTc-labeled sestamibi myocardial single-photon emission computed tomography (SPECT) compared with coronary angiography. Two hundred forty-four patients who were unable to exercise adequately underwent both dipyridamole ^99mTc-labeled sestamibi SPECT and coronary angiography within 6 months. Dipyridamole was administered intravenously in a standard dose of 0.56 mg/kg for 4 minutes. Cardiac and noncardiac side effects were recorded. The presence of coronary stenoses of 50% or greater diameter reduction in each of the major coronary arteries was compared with imaging data in corresponding myocardial perfusion beds. The patient population was predominately (98.8%) male with a mean age of 63±9 years (range 33 to 83 years). The majority of patients had stable angina (88%). Eighty-four patients (35%) gave a prior history of myocardial infarction; 44 patients (18%) had a history of congestire heart failure. The principal limitation to exercise stress was peripheral vascular disease in 62 patients (26%). No serious side effects occurred during dipyridamole stress; 14% of patients had chest pain and 8% of patients had 1 mm or greater ST segment depression. Of the 204 patients with documented coronary stenoses, 43 (21%) had single-vessel disease and 161 (79%) had multivessel disease. The sensitivity was 93% (40/43 in patients with single-vessel disease) and 91% (146/161 in patients with multivessel disease). Overall sensitivity was 91%. The specificity was 28% (11/40) in this population with a high prestest probability of coronary artery disease and posttest referral for cardiac catheterization.

Conclusion

^99mTc-labeled sestamibi myocardial tomography in conjunction with intravenous dipyridamole stress is a safe and sensitive method for the detection of coronary artery disease. The diagnostic accuracy of dipyridamole stress ^99mTc-labeled sestamibi SPECT for the detection of coronary artery disease is similar to that reported for exercise stress ^99mTc-labeled sestamibi tomography, making this a suitable alternative for the evaluation of patients who are unable to exercise adequately.     

Detection of coronary artery disease: Comparison between technetium 99m-labeled sestamibi single-photon emission computed tomography and two-dimensional echocardiography with dipyridamole low-level exercise-stress

Background

Myocardial perfusion imaging in conjunction with dipyridamole low-level exercise stress has proved its value in the evaluation of patients with coronary artery disease (CAD). Simultaneous wall motion analysis by two-dimensional (2D) echocardiography may provide additional information beyond that obtained by myocardial perfusion imaging alone. The purpose of this study was to compare ^99mTc-labeled sestamibi single-photon emission computed tomography (SPECT) and 2D echocardiography for the evaluation of CAD according to a dipyridamole low-level bicycle exercise stress protocol.

Methods and Results

We studied 35 consecutive patients referred for the evaluation of chest pain who had undergone coronary arteriography. ^99mTc-labeled sestamibi SPECT and 2D echocardiography agreed in 27 patients (80%) studied for overall detection of CAD. On a segmental basis, agreement was found between SPECT and 2D echocardiography in 124 (73%) of 170 segments (Cohen’s kappa=0.43). The accuracy of the combined assessment of myocardial perfusion and echocardiographic wall motion in detecting CAD was 86%, which was not different from the accuracy of SPECT alone (80%; difference not significant) but significantly higher than for 2D echocardiography alone (71%; p=0.03). In the detection of individual coronary artery stenoses, SPECT had a significantly higher accuracy for detecting left anterior descending coronary artery lesions than had 2D echocardiography (80% vs 60%; p<0.01); combining the two methods did not improve the accuracy (80%). The combined assessment slightly improved the accuracy for detecting left circumflex coronary artery stenoses from 71% to 83% (p=0.05).

Conclusion

The combined simultaneous assessment of myocardial perfusion by ^99mTc-labeled sestamibi SPECT and wall motion by 2D echocardiography did not significantly improve overall accuracy over that obtained by ^99mTc-labeled sestamibi SPECT alone. Therefore ^99mTc-labeled sestamibi SPECT with dipyridamole low-level exercise stress appears the preferred imaging modality for the evaluation of patients with CAD.     

Downstream resource utilization following hybrid cardiac imaging with an integrated cadmium-zinc-telluride/64-slice CT device

Purpose

Low yield of invasive coronary angiography and unnecessary coronary interventions have been identified as key cost drivers in cardiology for evaluation of coronary artery disease (CAD). This has fuelled the search for noninvasive techniques providing comprehensive functional and anatomical information on coronary lesions. We have evaluated the impact of implementation of a novel hybrid cadmium-zinc-telluride (CZT)/64-slice CT camera into the daily clinical routine on downstream resource utilization.

Methods

Sixty-two patients with known or suspected CAD were referred for same-day single-session hybrid evaluation with CZT myocardial perfusion imaging (MPI) and coronary CT angiography (CCTA). Hybrid MPI/CCTA images from the integrated CZT/CT camera served for decision-making towards conservative versus invasive management. Based on the hybrid images patients were classified into those with and those without matched findings. Matched findings were defined as the combination of MPI defect with a stenosis by CCTA in the coronary artery subtending the respective territory. All patients with normal MPI and CCTA as well as those with isolated MPI or CCTA finding or combined but unmatched findings were categorized as ??no match??.

Results

All 23 patients with a matched finding underwent invasive coronary angiography and 21 (91%) were revascularized. Of the 39 patients with no match, 5 (13%, p?p?Conclusion Cardiac hybrid imaging in CAD evaluation has a profound impact on patient management and may contribute to optimal downstream resource utilization.     

Automated quantitative coronary computed tomography correlates of myocardial ischaemia on gated myocardial perfusion SPECT

Purpose

Automated software tools have permitted more comprehensive, robust and reproducible quantification of coronary stenosis, plaque burden and plaque location of coronary computed tomography angiography (CTA) data. The association between these quantitative CTA (QCT) parameters and the presence of myocardial ischaemia has not been explored. The aim of the present investigation was to evaluate the association between QCT parameters of coronary artery lesions and the presence of myocardial ischaemia on gated myocardial perfusion single-photon emission CT (SPECT).

Methods

Included in the study were 40 patients (mean age 58.2?±?10.9 years, 27 men) with known or suspected coronary artery disease (CAD) who had undergone multidetector row CTA and gated myocardial perfusion SPECT within 6 months. From the CTA datasets, vessel-based and lesion-based visual analyses were performed. Consecutively, lesion-based QCT was performed to assess plaque length, plaque burden, percentage lumen area stenosis and remodelling index. Subsequently, the presence of myocardial ischaemia was assessed using the summed difference score (SDS ≥2) on gated myocardial perfusion SPECT.

Results

Myocardial ischaemia was seen in 25 patients (62.5 %) in 37 vascular territories. Quantitatively assessed significant stenosis and quantitatively assessed lesion length were independently associated with myocardial ischaemia (OR 7.72, 95 % CI 2.41–24.7, p?<?0.001, and OR 1.07, 95 % CI 1.00–1.45, p?=?0.032, respectively) after correcting for clinical variables and visually assessed significant stenosis. The addition of quantitatively assessed significant stenosis (χ ²?=?20.7) and lesion length (χ ²?=?26.0) to the clinical variables and the visual assessment (χ ²?=?5.9) had incremental value in the association with myocardial ischaemia.

Conclusion

Coronary lesion length and quantitatively assessed significant stenosis were independently associated with myocardial ischaemia. Both quantitative parameters have incremental value over baseline variables and visually assessed significant stenosis. Potentially, QCT can refine assessment of CAD, which may be of potential use for identification of patients with myocardial ischaemia.     

Cardiac hybrid SPECT/CTA imaging to detect “functionally relevant coronary artery lesion”: a potential gatekeeper for coronary revascularization?

Objective

Combination of both morphological and functional information has gained more and more appreciation with the concept of “functionally relevant coronary artery lesion (FRCAL)” and “functional revascularization”. This has paved the way for non-invasive single-photon emission computed tomography (SPECT)/computed tomography angiography (CTA) hybrid imaging. We aimed at assessing the value of cardiac hybrid imaging on the detection of FRCAL and its potential as a gatekeeper for invasive examination and treatment.

Methods

In Two hundred and thirty-eight patients with known or suspected coronary artery disease (CAD) underwent CTA and myocardial perfusion imaging (MPI) using SPECT on a dual system scanner in one session before treatment. 78 patients underwent invasive coronary angiography (CAG) within 1 month. Detection of FRCAL by the combination of SPECT/CTA was compared with SPECT/CAG, which served as a standard of reference. According to the both combination results, treatment decision (revascularization or medical treatment) was chosen in the catheterization laboratory.

Results

Sensitivity, specificity, accuracy, positive and negative prediction rate by SPECT/CTA vs. SPECT/CAG for the detection of flow-limiting coronary stenosis on patient- and vessel-based analysis were 94.33, 72.00, 87.18, 87.71, 85.71 % and 88.71, 92.44, 91.45, 80.89, 95.78 %, respectively. No revascularization procedures were performed in patients without flow-limiting stenosis. However, more than one-third (25/67, 37 %) of revascularized vessels were not associated with ischemia on MPI.

Conclusions

The cardiac SPECT/CTA hybrid imaging can accurately detect FRCAL and thereby it may be used as a gatekeeper for CAG and revascularization procedures.     

Angiographic correlation of myocardial perfusion imaging with half the radiation dose using ordered-subset expectation maximization with resolution recovery software

Background

We previously described the feasibility of performing myocardial perfusion imaging (MPI) with half the technetium (Tc-99m) activity using ordered-subset expectation maximization with resolution recovery (OSEM-RR) processing. This study sought to assess the accuracy of this technique by correlating the findings with coronary angiography.

Methods

Of 290 patients who underwent MPI-gated SPECT using a half dose of Tc-99m sestamibi and OSEM-RR software in 2010-2012 at a tertiary medical center, 62 were referred for invasive coronary angiography within 90 days and formed the study group. Ischemia was defined as a summed difference score (SDS) of >3 on the MPI scan. Luminal stenosis of ≥70% on invasive coronary angiography served as the reference.

Results

Mean Tc-99m activity per study was 23.9 ± 11.5 mCi and mean effective radiation dose was 7.2 ± 3.4 mSv. MPI revealed no abnormalities in 10 patients (16.2%), myocardial infarction only in 8 patients (12.9%), and ischemia in 44 patients (71.1%). Overall sensitivity, specificity, and positive and negative predictive values for MPI compared to invasive angiography were 89.1%, 75.0%, 91.1%, and 70.5%, respectively.

Conclusions

MPI SPECT performed with a half dose of Tc-99m and OSEM-RR image processing correlates well with invasive angiography. (J Nucl Cardiol 2013)     

Myocardial single-photon emission computed tomographic imaging with technetium 99m tetrofosmin: Stress-rest imaging with same-day and separate-day rest imaging

Background

Technetium 99m tetrofosmin is a new ethylene diphosphine ligand for myocardial perfusion imaging and has unique properties. We have compared stress-rest single-photon emission computed tomographic (SPECT) imaging with^99mTc tetrofosmin with same-day and separate-day rest imaging to detect myocardial perfusion defects.

Methods and Results

Myocardial SPECT imaging was performed in 22 patients with coronary artery disease who had undergone planar thallium 201 imaging and coronary angiography. Single-day (stress-rest) and separate-day rest^99mTc tetrofosmin SPECT protocols were compared in the same patient. Images were assessed by a blinded panel to identify myocardial infarction, ischemia, or normal scans. Overall sensitivity for identification of patients with coronary artery disease was 86% (19/22) by both same-day stress-rest and separate-day rest protocols with^99mTc tetrofosmin (p=NS). Of a total of 396 segments studied, 107 abnormal segments were identified at exercise and 76 and 81 at the same-day and separate-day rest tests, respectively (p=NS). Same-day stress-rest and separate-day rest^99mTc tetrofosmin SPECT protocols were also useful for detecting individual coronary stenosis with a greater than 50% lesion: 80% of the left anterior descending, 93% of the right coronary, and 75% of the left circumflex coronary arteries were detected.

Conclusion

Excellent images were obtained with^99mTc tetrofosmin during both stress and rest.^99mTc tetrofosmin imaging with the same-day stress-rest and separate-day rest imaging protocols have similar diagnostic sensitivities for detection of coronary heart disease.