Comparison between different kernel reformatting filters in 3D quantitative analysis of MDCT coronary angiography

Purpose

Coronary angiography with multidetector-row computed tomography (MDCT-CA) allows quantification of coronary artery stenosis with a high level of accuracy; however, a better estimation of stenosis can be achieved by using appropriate reformatting filters, especially in stents and calcified segments. Quantitative computed tomography angiography (QCTA) is intended to overcome the limitations of the visual score. The aim of this study was to evaluate the accuracy of QCTA with different filters in comparison with quantitative coronary angiography (QCA) and visual score.

Materials and methods

Two blinded operators visually scored 17 consecutive patients referred for MDCT-CA with a per-segment analysis. The degree of stenosis was classified as 0?C20%, 20?C50% (wall irregularities), 50?C70% (significant disease) and 70?C100% (vessel occlusion). Each segment was then analysed using the electronic callipers of the QCTA system with 15 different filters. No contour editing was performed. Data were compared with QCA and conventional coronary angiography (CCA). Comparison between QCTA, visual score and QCA were performed using Spearman??s rank correlation.

Results

Of 25 segments analysed (mean 1.4 diseased segment per patient), 375 measurements were considered. Good correlation was found between the visual score and QCA [Pearson correlation coefficient (rho=0.852; p<0.0001)] and between QCA and CCA (rho=0.804; p<0.0001). Moderate correlation was found between QCA and QCTA only using two filters (rho=0.444; p<0.0001 for YA filter and rho=0.450; p<0.0001 for YB filter).

Conclusions

Overall QCTA accuracy is low if contour editing is not applied, especially in calcified vessels. Certain filters can help to better estimate the exact percentage of stenosis.     

Novel attenuation correction of SPECT images using scatter photopeak window data for the detection of coronary artery disease

Background

Attenuation correction using segmentation with scatter and photopeak window data (SSPAC) may enable evaluation of the attenuation map in a patient-specific manner without the need for additional radiation exposure and more acquisition time. We examined the feasibility of SSPAC and compared the sensitivity, specificity, and accuracy of this new correction method with that of conventional non-corrected myocardial perfusion single-photon emission computed tomography (SPECT) among patients with suspected or diagnosed coronary artery disease.

Methods and Results

One hundred sixty-one patients who underwent both ^99mTc-tetrofosmin stress/rest SPECT examination and invasive coronary angiography were enrolled in the study. Data from the SSPAC-corrected and non-corrected methods were analyzed quantitatively using summed stress scores. Attenuation maps were obtained successfully for 150 (93%) of the patients. The SSPAC-corrected and non-corrected methods accurately predicted coronary artery disease defined as >50% luminal stenosis verified by coronary artery angiography and/or prior myocardial infarction, for 91% and 77% patients, respectively (P < .05). For diagnosis of coronary artery disease, SSPAC improved sensitivity in the left anterior descending artery territory and specificity in the right coronary artery territory.

Conclusions

Attenuation correction with SSPAC may be a feasible method of correction for myocardial perfusion SPECT and in some cases may provide better accuracy for diagnosing coronary artery disease.     

Diagnostic accuracy of combined coronary angiography and adenosine stress myocardial perfusion imaging using 320-detector computed tomography: pilot study

Objectives

To determine the diagnostic accuracy of combined 320-detector row computed tomography coronary angiography (CTA) and adenosine stress CT myocardial perfusion imaging (CTP) in detecting perfusion abnormalities caused by obstructive coronary artery disease (CAD).

Methods

Twenty patients with suspected CAD who underwent initial investigation with single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI) were recruited and underwent prospectively-gated 320-detector CTA/CTP and invasive angiography. Two blinded cardiologists evaluated invasive angiography images quantitatively (QCA). A blinded nuclear physician analysed SPECT-MPI images for fixed and reversible perfusion defects. Two blinded cardiologists assessed CTA/CTP studies qualitatively. Vessels/territories with both >50 % stenosis on QCA and corresponding perfusion defect on SPECT-MPI were defined as ischaemic and formed the reference standard.

Results

All patients completed the CTA/CTP protocol with diagnostic image quality. Of 60 vessels/territories, 17 (28 %) were ischaemic according to QCA/SPECT-MPI criteria. Sensitivity, specificity, PPV, NPV and area under the ROC curve for CTA/CTP was 94 %, 98 %, 94 %, 98 % and 0.96 (P?<?0.001) on a per-vessel/territory basis. Mean CTA/CTP radiation dose was 9.2?±?7.4 mSv compared with 13.2?±?2.2 mSv for SPECT-MPI (P?<?0.001).

Conclusions

Combined 320-detector CTA/CTP is accurate in identifying obstructive CAD causing perfusion abnormalities compared with combined QCA/SPECT-MPI, achieved with lower radiation dose than SPECT-MPI.

Key Points

? Advances in CT technology provides comprehensive anatomical and functional cardiac information. ? Combined 320-detector CTA/adenosine-stress CTP is feasible with excellent image quality. ? Combined CTA/CTP is accurate in identifying myocardial ischaemia compared with QCA/SPECT-MPI. ? Combined CTA/CTP results in lower patient radiation exposure than SPECT-MPI. ? CTA/CTP may become an established imaging technique for suspected CAD.     

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.     

Computed tomography coronary angiography and invasive coronary angiography demonstrate high correlation for area stenosis quantification in noncalcified and mixed plaques

We compared the variance of area and diameter significant stenosis measurement between quantitative computed tomography coronary angiography (QCTA) and quantitative invasive coronary angiography (QCA). Fifty patients presenting 65 significant coronary artery stenoses (≥70% area stenosis) in QCTA and QCA were included. Spearman's rank correlation revealed that area stenosis measurement by QCTA and QCA yields higher correlation than diameter stenosis and is highest for noncalcified and mixed lesions.     

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.     

Initial multicentre experience of high-speed myocardial perfusion imaging: comparison between high-speed and conventional single-photon emission computed tomography with angiographic validation

Purpose

High-speed (HS) single-photon emission computed tomography (SPECT) with a recently developed solid-state camera shows comparable myocardial perfusion abnormalities to those seen in conventional SPECT. We aimed to compare HS and conventional SPECT images from multiple centres with coronary angiographic findings.

Methods

The study included 50 patients who had sequential conventional SPECT and HS SPECT myocardial perfusion studies and coronary angiography within 3 months. Stress and rest perfusion images were visually analysed and scored semiquantitatively using a 17-segment model by two experienced blinded readers. Global and coronary territorial summed stress scores (SSS) and summed rest scores (SRS) were calculated. Global SSS ≥3 or coronary territorial SSS ≥2 was considered abnormal. In addition the total perfusion deficit (TPD) was automatically derived. TPD >5 % and coronary territorial TPD ≥3 % were defined as abnormal. Coronary angiograms were analysed for site and severity of coronary stenosis; ≥50 % was considered significant.

Results

Of the 50 patients, 13 (26 %) had no stenosis, 22 (44 %) had single-vessel disease, 6 (12 %) had double-vessel disease and 9 (18 %) had triple-vessel disease. There was a good linear correlation between the visual global SSS and SRS (Spearman’s ρ 0.897 and 0.866, respectively; p?<?0.001). In relation to coronary angiography, the sensitivities, specificities and accuracies of HS SPECT and conventional SPECT by visual assessment were 92 % (35/38), 83 % (10/12) and 90 % (45/50) vs. 84 % (32/38), 50 % (6/12) and 76 % (38/50), respectively (p?<?0.001). The sensitivities, specificities and accuracies of HS SPECT and conventional SPECT in relation to automated TPD assessment were 89 % (31/35), 57 % (8/14) and 80 % (39/49) vs. 86 % (31/36), 77 % (10/13) and 84 % (41/49), respectively.

Conclusion

HS SPECT allows fast acquisition of myocardial perfusion images that correlate well with angiographic findings with overall accuracy by visual assessment better than conventional SPECT. Further assessment in a larger patient population may be needed to confirm this observation.     

Correlation of regional distribution and morphological pattern of calcification at CT coronary artery calcium scoring with non-calcified plaque formation and stenosis

Objective

To investigate whether regional calcification patterns at CT coronary artery calcium scoring (CCS) correlate with stenosis and non-calcified plaque formation.

Methods

We studied 106 patients with quantitative catheter angiography (QCA), CCS, and coronary CT angiography (cCTA). CCS was determined globally and for each artery separately. The morphological pattern of each calcification was classified as calcified nodule, shell-like, or diffuse. cCTA studies were evaluated for non-calcified plaque. The global and regional CCS and the calcification pattern were correlated with stenosis ≥50% and non-calcified plaque.

Results

A total of 48/106 patients had stenosis ≥50% on QCA. There was weak correlation (r?=?0.36) of the global CCS with stenosis. Correlation was stronger per vessel (r?=?0.55–r?=?0.67). Shell-like and diffuse calcifications were significantly (p?=?0.0001) more frequently associated with ≥50% stenosis and non-calcified plaque (p?=?0.04) than calcified nodules.

Conclusion

As shown before, the global CCS does not correlate well with stenosis. However, regional calcium distribution and specific patterns of calcification are correlated with stenosis and non-calcified plaque. Thus, the specificity of CT calcium scoring for identifying individuals with obstructive disease could be improved by vessel-based rather than global quantification of calcium and by differentiating specific morphological patterns of calcification.     

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)     

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.     

Relationship Between Coronary Contrast-Flow Quantitative Flow Ratio and Myocardial Ischemia Assessed by SPECT MPI

Purpose

A new method has been developed to calculate fractional flow reserve (FFR) from invasive coronary angiography, the so-called “contrast-flow quantitative flow ratio (cQFR)”. Recently, cQFR was compared to invasive FFR in intermediate coronary lesions showing an overall diagnostic accuracy of 85%. The purpose of this study was to investigate the relationship between cQFR and myocardial ischemia assessed by single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI).

Methods

Patients who underwent SPECT MPI and coronary angiography within 3 months were included. The cQFR computation was performed offline, using dedicated software. The cQFR computation was based on 3-dimensional quantitative coronary angiography (QCA) and computational fluid dynamics. The standard 17-segment model was used to determine the vascular territories. Myocardial ischemia was defined as a summed difference score ≥2 in a vascular territory. A cQFR of ≤0.80 was considered abnormal.

Results

Two hundred and twenty-four coronary arteries were analysed in 85 patients. Overall accuracy of cQFR to detect ischemia on SPECT MPI was 90%. In multivariable analysis, cQFR was independently associated with ischemia on SPECT MPI (OR per 0.01 decrease of cQFR: 1.10; 95% CI 1.04-1.18, p = 0.002), whereas clinical and QCA parameters were not. Furthermore, cQFR showed incremental value for the detection of ischemia compared to clinical and QCA parameters (global chi square 48.7 to 62.6; p <0.001).

Conclusions

A good relationship between cQFR and SPECT MPI was found. cQFR was independently associated with ischemia on SPECT MPI and showed incremental value to detect ischemia compared to clinical and QCA parameters.

     

Accuracy of low-dose rubidium-82 myocardial perfusion imaging for detection of coronary artery disease using 3D PET and normal database interpretation

Background

Our aim was to develop a normal database to be used for quantification of myocardial perfusion and diagnosis of ??obstructive coronary artery disease?? (CAD) using low-dose rubidium-82 three-dimensional (3D) positron emission tomography (PET)-CT.

Methods

From a record of 1,501 patients, 77 were identified as having low-likelihood (LLK) of CAD. Forty LLK patients were used to construct a normal database using 4DM-PET, the remainder used for validation of normalcy. A group of 70 patients with CAD who had invasive coronary angiography and PET-CT were used to evaluate the accuracy of the database for detecting CAD using the sum-stress-score. The effect of clinical exclusion criteria and the inclusion of LLK patients were evaluated.

Results

The normal database for CAD detection had a normalcy rate of 95%. Sensitivity was 100% for detecting patients with either 50% or 70% stenosis. Optimal specificity was 87% for either 50% or 70% stenosis. For localizing disease at 50% stenosis in the left anterior descending, left circumflex, and right coronary artery, sensitivity ranged from 59% to 68%, while specificity was maintained at 87-89%. Similarly, at 70% stenosis, sensitivity ranged from 64% to 79%, and specificity from 87% to 91%.

Conclusions

A normal database containing the relative perfusion scores of patients with LLK of CAD can be used to accurately diagnose obstructive coronary disease using low-dose Rb-82 with 3D PET-CT imaging.     

Roles of myocardial blood volume and flow in coronary artery disease: an experimental MRI study at rest and during hyperemia

Objective

To validate fast perfusion mapping techniques in a setting of coronary artery stenosis, and to further assess the relationship of absolute myocardial blood volume (MBV) and blood flow (MBF) to global myocardial oxygen demand.

Methods

A group of 27 mongrel dogs were divided into 10 controls and 17 with acute coronary stenosis. On 1.5-T MRI, first-pass perfusion imaging with a bolus injection of a blood-pool contrast agent was performed to determine myocardial perfusion both at rest and during either dipyridamole-induced vasodilation or dobutamine-induced stress. Regional values of MBF and MBV were quantified by using a fast mapping technique. Color microspheres and ^99mTc-labeled red blood cells were injected to obtain respective gold standards.

Results

Microsphere-measured MBF and ^99mTc-measured MBV reference values correlated well with the MR results. Given the same changes in MBF, changes in MBV are twofold greater with dobutamine than with dipyridamole. Under dobutamine stress, MBV shows better association with total myocardial oxygen demand than MBF. Coronary stenosis progressively reduced this association in the presence of increased stenosis severity.

Conclusions

MR first-pass perfusion can rapidly estimate regional MBF and MBV. Absolute quantification of MBV may add additional information on stenosis severity and myocardial viability compared with standard qualitative clinical evaluations of myocardial perfusion.     

Difference of coronary stenosis severity between systolic and diastolic phases in quantitative CT angiography

Background

To compare the difference of coronary diameter stenosis by quantitative analysis of CT angiography (QCT) in the systolic (QCT-S) and diastolic phase (QCT-D) of the cardiac cycle, with invasive catheter angiography (QCA) as reference standard.

High-efficiency SPECT MPI: Comparison of automated quantification, visual interpretation, and coronary angiography

Background

Recently introduced high-efficiency (HE) SPECT cameras with solid-state CZT detectors have been shown to decrease imaging time and reduce radiation exposure to patients. An automated, computer-derived quantification of HE MPI has been shown to correlate well with coronary angiography on one HE SPECT camera system (D-SPECT), but has not been compared to visual interpretation on any of the HE SPECT platforms.

Methods

Patients undergoing a clinically indicated Tc-99m sestamibi HE SPECT (GE Discovery 530c with supine and prone imaging) study over a 1-year period followed by a coronary angiogram within 2 months were included. Only patients with a history of CABG surgery were excluded. Both MPI studies and coronary angiograms were reinterpreted by blinded readers. One hundred and twenty two very low (risk of CAD < 5%) or low (risk of CAD < 10%) likelihood subjects with normal myocardial perfusion were used to create normal reference limits. Computer-derived quantification of the total perfusion deficit at stress and rest was obtained with QPS software. The visual and automated MPI quantification were compared to coronary angiography (≥70% luminal stenosis) by receiver operating curve (ROC) analysis.

Results

Of the 3,111 patients who underwent HE SPECT over a 1-year period, 160 patients qualified for the correlation study (66% male, 52% with a history of CAD). The ROC area under the curve (AUC) was similar for both the automated and the visual interpretations using both supine only and combined supine and prone images (0.69-0.74). Using thresholds determined from sensitivity and specificity curves, the automated reads showed higher specificity (59%-67% vs 27%-60%) and lower sensitivity (71%-72% vs 79%-93%) than the visual reads. By including prone images sensitivity decreased slightly but specificity increased for both. By excluding patients with known CAD and cardiomyopathies, AUC and specificity increased for both techniques (0.72-0.82). The use of a difference score to evaluate ischemic burden resulted in lower sensitivities but higher specificities for both automated and visual quantification. There was good agreement between the visual interpretation and automated quantification in the entire cohort of 160 unselected consecutive patients (r = 0.70-0.81, P < .0001).

Conclusions

Automated and visual quantification of high-efficiency SPECT MPI with the GE Discovery camera provides similar overall diagnostic accuracy when compared to coronary angiography. There was good correlation between the two methods of assessment. Combined supine and prone stress imaging provided the best diagnostic accuracy.     

Gender differences in the evaluation of coronary artery disease with a cadmium-zinc telluride camera

Purpose

Coronary artery disease remains one of the most significant causes of morbidity and mortality among women. The published literature shows the importance of standard single photon emission computed tomography in the evaluation of women with known or suspected ischaemic heart disease, in terms of target intervention and clinical treatment. The purpose of the present study was to ascertain the diagnostic accuracy of cadmium-zinc-telluride (CZT) myocardial perfusion imaging according to gender, within a prospective database of patients with known or suspected coronary artery disease, using coronary angiography as the reference standard.

Methods

Included in the study were 309 consecutive patients, of whom 248 were men (80 %), with known or suspected coronary artery disease and who had been referred to our laboratory for stress–rest myocardial perfusion imaging. All patients underwent coronary angiography within 30 days. All patients underwent a single-day stress–rest low-dose ultrafast protocol. Fifteen minutes after the end of the stress (dose range 185 to 222 MBq of ^99mTc-tetrofosmin), all patients underwent the first scan with an acquisition time of 7 min. The rest scan (dose range 370 to 444 MBq of ^99mTc-tetrofosmin) was acquired from 30 min to 45 min after injection, with an acquisition time of 6 min. Images were visually inspected, and summed stress scores (SSS) and summed rest scores (SRS) were obtained.

Results

Image quality was graded “good” or better in more than 90 % of patients. On coronary angiography, left main trunk stenosis, left anterior descending artery stenosis, left circumflex artery stenosis and right coronary artery stenosis were seen in 3, 155 , 142 and 131 patients, respectively. In women, the mean SSS and SRS were 8?±?5 and 3?±?1, respectively. Semiquantitative regional and global SSS were good discriminants of coronary artery disease, and the overall area under the receiver operator characteristic (ROC) curve was 0.822 (95 % CI 0.685 – 0.959). The value was comparable to that obtained in men (overall ROC area 0.884, 95 % CI 0.836 – 0.933).

Conclusion

A low-dose protocol with a CZT camera can be routinely used in women with known or suspected coronary artery disease without loss of accuracy and with lower radiation exposure of the patients.     

Assessment of myocardial fibrosis and coronary arteries in hypertrophic cardiomyopathy using combined arterial and delayed enhanced CT: comparison with MR and coronary angiography

Objectives

We sought to determine the feasibility and accuracy of dual-source computed tomography (DSCT) in assessing coronary artery disease and myocardial fibrosis of hypertrophic cardiomyopathy (HCM) compared with cardiac magnetic resonance (CMR) imaging and coronary angiography (CA).

Methods

Forty-seven consecutive patients with HCM were prospectively enrolled. DSCT images were acquired in the arterial and late phases following intravenous contrast medium. The CMR and CA were performed within 7 days. Independent blinded readers read each study. Patients were classified according to myocardial delayed enhanced (MDE) CMR, coronary artery stenosis by CA, and arterial and MDE-DSCT. The diagnostic accuracy of DSCT in detecting coronary stenosis and MDE was analysed.

Results

Wall thickness determined by DSCT was strongly correlated with MR results (r?=?0.91). DSCT and CMR MDE showed substantial agreement for the detection of myocardial fibrosis on per-patient and per-segment levels. The CT classification of patients by arterial stenosis and delayed enhancement had excellent agreement with MR and CA methods.

Conclusions

The comprehensive cardiac CT examination provides reliable coronary artery and myocardial assessments. MDE-DSCT is a robust alternative method to MDE-CMR in assessing myocardial fibrosis in HCM particularly in patients with pacemakers or other contraindications to CMR.

Key Points

? Enhanced cardiac CT provides comprehensive assessment of patients with hypertrophic cardiomyopathy (HCM). ? Myocardial delayed enhanced-CT has comparable accuracy to MDE-MR in detecting HCM fibrosis. ? MDE-CT provides a robust alternative for HCM patients with MR contraindications.     

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.     

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.