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ABSTRACT: To assess the impact of adaptive statistical iterative reconstruction (ASIR) on coronary plaque volume and composition analysis as well as on stenosis quantification in high definition coronary computed tomography angiography (CCTA). We included 50 plaques in 29 consecutive patients who were referred for the assessment of known or suspected coronary artery disease (CAD) with contrast-enhanced CCTA on a 64-slice high definition CT scanner (Discovery HD 750, GE Healthcare). CCTA scans were reconstructed with standard filtered back projection (FBP) with no ASIR (0 %) or with increasing contributions of ASIR, i.e. 20, 40, 60, 80 and 100 % (no FBP). Plaque analysis (volume, components and stenosis degree) was performed using a previously validated automated software. Mean values for minimal diameter and minimal area as well as degree of stenosis did not change significantly using different ASIR reconstructions. There was virtually no impact of reconstruction algorithms on mean plaque volume or plaque composition (e.g. soft, intermediate and calcified component). However, with increasing ASIR contribution, the percentage of plaque volume component between 401 and 500 HU decreased significantly (p < 0.05). Modern image reconstruction algorithms such as ASIR, which has been developed for noise reduction in latest high resolution CCTA scans, can be used reliably without interfering with the plaque analysis and stenosis severity assessment.
The international journal of cardiovascular imaging 10/2012; · 2.15 Impact Factor
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Cathérine Gebhard,
Michael Fiechter,
Tobias A Fuchs,
Jelena R Ghadri, Bernhard A Herzog,
Felix Kuhn,
Julia Stehli,
Ennio Müller,
Egle Kazakauskaite,
Oliver Gaemperli,
Philipp A Kaufmann
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ABSTRACT: OBJECTIVE: Assessment of coronary artery calcification is increasingly used for cardiovascular risk stratification. We evaluated the reliability of calcium-scoring results using a novel iterative reconstruction algorithm (ASIR) on a high-definition 64-slice CT scanner, as such data is lacking. METHODS AND RESULTS: In 50 consecutive patients Agatston scores, calcium mass and volume score were assessed. Comparisons were performed between groups using filtered back projection (FBP) and 20-100% ASIR algorithms. Calcium score was measured in the coronary arteries, signal and noise were measured in the aortic root and left ventricle. In comparison with FBP, use of 20%, 40%, 60%, 80%, and 100% ASIR resulted in reduced image noise between groups (7.7%, 18.8%, 27.9%, 39.86%, and 48.56%, respectively; p<0.001) without difference in signal (p=0.60). With ASIR algorithms Agatston coronary calcium scoring significantly decreased compared with FBP algorithms (837.3±130.3; 802.2±124.9, 771.5±120.7; 744.7±116.8, 724.5±114.2, and 709.2±112.3 for 0%, 20%, 40%, 60%, 80%, and 100% ASIR, respectively, p<0.001). Volumetric score decreased in a similar manner (p<0.001) while calcium mass remained unchanged. Mean effective radiation dose was 0.81±0.08mSv. CONCLUSION: ASIR results in image noise reduction. However, ASIR image reconstruction techniques for HDCT scans decrease Agatston coronary calcium scores. Thus, one needs to be aware of significant changes of the scoring results caused by different reconstruction methods.
International journal of cardiology 09/2012; · 7.08 Impact Factor
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ABSTRACT: The ability to obtain quantitative values of flow and myocardial flow reserve (MFR) has been perceived as an important advantage of PET over conventional nuclear myocardial perfusion imaging (MPI). We evaluated the added diagnostic value of MFR over MPI alone as assessed with (13)N-ammonia and PET/CT to predict angiographic coronary artery disease (CAD).
Seventy-three patients underwent 1-d adenosine stress-rest (13)N-ammonia PET/CT MPI, and MFR was calculated. The added value of MFR as an adjunct to MPI for predicting CAD (luminal narrowing ≥ 50%) was evaluated using invasive coronary angiography as a standard of reference.
Per patient, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MPI for detecting significant CAD were 79%, 80%, 91%, 59%, and 79%, respectively. Adding a cutoff of less than 2.0 for global MFR to MPI findings improved the values to 96% (P < 0.005), 80%, 93%, 89% (P < 0.005), and 92% (P < 0.005), respectively.
The quantification of MFR in (13)N-ammonia PET/CT MPI provides a substantial added diagnostic value for detection of CAD. Particularly in patients with normal MPI results, quantification of MFR helps to unmask clinically significant CAD.
Journal of Nuclear Medicine 06/2012; 53(8):1230-4. · 6.38 Impact Factor
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ABSTRACT: We have evaluated the impact of increased body mass on the quality of myocardial perfusion imaging using a latest-generation γ-camera with cadmium-zinc-telluride semiconductor detectors in patients with high (≥40 kg/m(2)) or very high (≥45 kg/m(2)) body mass index (BMI).
We enrolled 81 patients, including 18 with no obesity (BMI < 30 kg/m(2)), 17 in World Health Organization obese class I (BMI, 30-34.9 kg/m(2)), 15 in class II (BMI, 35-39.9 kg/m(2)), and 31 in class III (BMI ≥ 40 kg/m(2)), including 15 with BMI ≥ 45 kg/m(2). Image quality was scored as poor (1), moderate (2), good (3), or excellent (4). Patients with BMI ≥ 45 kg/m(2) and nondiagnostic image quality (≤2) were rescanned after repositioning to better center the heart in the field of view. Receiver-operating-curve analysis was applied to determine the BMI cutoff required to obtain diagnostic image quality (≥3).
Receiver-operating-curve analysis resulted in a cutoff BMI of 39 kg/m(2) (P < 0.001) for diagnostic image quality. In patients with BMI ≥ 40 kg/m(2), image quality was nondiagnostic in 81%; after CT-based attenuation correction this decreased to 55%. Repositioning further improved image quality. Rescanning on a conventional SPECT camera resulted in diagnostic image quality in all patients with BMI ≥ 45 kg/m(2).
Patients with BMI ≥ 40 kg/m(2) should be scheduled for myocardial perfusion imaging on a conventional SPECT camera, as it is difficult to obtain diagnostic image quality on a cadmium-zinc-telluride camera.
Journal of Nuclear Medicine 06/2012; 53(9):1401-6. · 6.38 Impact Factor
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ABSTRACT: PurposeThe aim of this study was to evaluate whether ECG-triggered coronary calcium scoring (CCS) scans can be used for attenuation
correction (AC) to quantify myocardial blood flow (MBF) and coronary flow reserve (CFR) assessed by PET/CT with 13N-ammonia.
MethodsThirty-five consecutive patients underwent a 13N-ammonia PET/CT scan at rest and during standard adenosine stress. MBF values were calculated using AC maps obtained from
the ECG-triggered CCS scan during inspiration and validated against MBF values calculated using standard non-gated transmission
scans for AC. CFR was calculated as the ratio of hyperaemic over resting MBF. In all 35 consecutive patients intraobserver
variability was assessed by blinded repeat analysis for both AC methods.
ResultsThere was an excellent correlation between CT AC and CCS for global MBF values at rest (n = 35, r = 0.94, p < 0.001) and during stress (n = 35, r = 0.97, p < 0.001) with narrow Bland-Altman (BA) limits of agreement (−0.21 to 0.10ml/min per g and −0.41 to 0.30ml/min per g) as
well as for global CFR (n = 35, r = 0.96, p < 0.001, BA −0.27 to 0.34). The excellent correlation was preserved on the segmental MBF analysis for both rest and stress
(n = 1190, r = 0.93, p < 0.001, BA −0.60 to 0.50) and for CFR (n = 595, r = 0.87, p < 0.001, BA −0.71 to 0.74). In addition, reproducibility proved excellent for global CFR by CT AC (n = 35, r = 0.91, p < 0.001, BA −0.42–0.58) and CCS scans (n = 35, r = 0.94, p < 0.001, BA −0.34–0.45).
ConclusionUse of attenuation maps from CCS scans allows accurate quantitative MBF and CFR assessment with 13N-ammonia PET/CT.
KeywordsAttenuation correction-Coronary calcium score-PET-Myocardial blood flow
European journal of nuclear medicine and molecular imaging 04/2012; 37(3):517-521. · 4.99 Impact Factor
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ABSTRACT: BACKGROUND/OBJECTIVES: The aim of the present study was to assess the long-term predictive value of myocardial perfusion imaging (MPI) with (13)N-ammonia positron emission tomography (PET) in patients with suspected myocardial perfusion abnormality. At present, outcome data on the predictive value of MPI in (13)N-ammonia PET exist only for rather small patient populations. METHODS: Cardiac perfusion was assessed in 943 consecutive patients using (13)N-ammonia PET, and follow-up was obtained in 698 (74%). 77 patients who underwent early revascularization (<60days) were excluded and 621 patients were assigned to normal versus abnormal perfusion for outcome analysis. Hard events (cardiac death and non-fatal myocardial infarction) and major adverse cardiac events (MACE; hard events, hospitalization for cardiac reasons and late revascularization) were investigated using the Kaplan-Meier method. Independent predictors for various cardiac events were identified using Cox proportional hazard regression analysis. RESULTS: During follow-up (5.7±2.5years), 275 patients had at least 1 cardiac event, including 102 cardiac deaths and 33 non-fatal myocardial infarction. Abnormal perfusion (n=469) was associated with a higher incidence of MACE (P<0.001) and hard events (P<0.001) throughout the 10-year follow-up period. CONCLUSIONS: Cardiac perfusion findings in (13)N-ammonia PET are strong predictors of long-term outcome.
International journal of cardiology 04/2012; · 7.08 Impact Factor
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Michael Fiechter,
Jelena R Ghadri,
Mathias Wolfrum,
Silke M Kuest,
Aju P Pazhenkottil,
Rene N Nkoulou, Bernhard A Herzog,
Cathérine Gebhard,
Tobias A Fuchs,
Oliver Gaemperli,
Philipp A Kaufmann
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ABSTRACT: 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.
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".
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 < 0.001 vs matched) underwent catheterization and 3 (8%, p < 0.001 vs matched) were revascularized.
Cardiac hybrid imaging in CAD evaluation has a profound impact on patient management and may contribute to optimal downstream resource utilization.
European Journal of Nuclear Medicine 12/2011; 39(3):430-6. · 4.53 Impact Factor
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Bernhard A Herzog,
Lars Husmann,
Ronny R Buechel,
Aju P Pazhenkottil,
Irene A Burger,
Ines Valenta,
Ulrich Altorfer,
Mathias Wolfrum,
Rene N Nkoulou,
Jelena R Ghadri,
Christophe A Wyss,
Philipp A Kaufmann
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ABSTRACT: Ischemic coronary artery disease (CAD) is a major cause for morbidity and mortality resulting in a continuously increasing number of diagnostic interventions. We have validated a new hybrid imaging method using minimized radiation dose for rapid non-invasive prediction of invasive coronary angiography (CA) findings with regard to coronary lesion detection and revascularization.
Forty patients referred for elective invasive coronary angiography (CA) due to suspected CAD were prospectively enrolled to undergo a low-dose CTCA with prospective ECG-triggering and a stress-only SPECT-MPI scan administering half of the standard low-dose stress (99m)Tc-tetrofosmin activity. The latter was acquired immediately after adenosine stress (omitting the standard 30-60 min waiting time). After fusing CTCA and SPECT-MPI decisions towards conservative management versus revascularization strategy based on hybrid images were compared to the decisions taken by the interventional operator in the catheterization laboratory based on CA. The latter served as standard of reference.
Hybrid images yielded sensitivity, specificity, positive and negative predictive values and accuracy of 100%, 96.0%, 100%, 93.8% and 97.5% for predicting coronary revascularization. The estimated mean effective radiation doses were significantly lower for hybrid imaging (4.7 ± 1.0 mSv) than for invasive CA (8.7 ± 4.2 mSv; P<0.001 vs. hybrid). Total non-invasive protocol time was below 60 min, comparing favourably to standard SPECT protocols.
Rapid cardiac hybrid imaging allows accurate prediction of invasive CA findings and of treatment decision despite minimized radiation dose and protocol time.
International journal of cardiology 11/2011; 153(1):10-3. · 7.08 Impact Factor
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Rene Nkoulou,
Aju P Pazhenkottil,
Silke M Kuest,
Jelena R Ghadri,
Mathias Wolfrum,
Lars Husmann,
Michael Fiechter,
Ronny R Buechel, Bernhard A Herzog,
Pascal Koepfli,
Cyrill Burger,
Oliver Gaemperli,
Philipp A Kaufmann
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ABSTRACT: Cadmium zinc telluride (CZT) detectors with linear counting rate response enable count subtraction in sequential scanning. We evaluated whether count subtraction eliminated the need for higher activity doses in the second part of the 1-d stress-rest myocardial perfusion imaging (MPI) protocol.
For 50 patients (mean age ± SD, 66 ± 12 y) with visually abnormal (n = 42) or equivocal (n = 8) adenosine-stress MPI (320 MBq of (99m)Tc-tetrofosmin) on a CZT camera, rest MPI was performed with a low dose (320 MBq) and repeated after injection of an additional 640 MBq of (99m)Tc-tetrofosmin to achieve a standard 3-fold increased dose at rest (960 MBq), compared with stress (320 MBq). Low-dose rest myocardial perfusion images were reconstructed after subtracting the background activity of the preceding stress scan. Segmental percentage tracer uptake of the 2 rest myocardial perfusion images (320 vs. 960 MBq) was compared using intraclass correlation and Bland-Altman limits of agreement. Patient- and coronary territory-based clinical agreement was assessed.
The standard protocol revealed ischemia in 34 (68%) and a fixed defect in 8 (16%) patients, of whom 33 (97%) and 8 (100%) were correctly identified by low-dose MPI (clinical agreement, 98%). Segmental uptake correlated well between low- and standard-dose rest scans (r = 0.94, P < 0.001; Bland-Altman limits of agreement, -11 to +11%). Defect extent was 14.4% (low-dose) versus 13.1% (standard-dose) at rest (P = not statistically significant) and 26.6% at stress (P < 0.001 vs. rest scans).
These promising results suggest that accurate assessment of ischemic myocardial disease is feasible with a low-dose-low-dose 1-d SPECT MPI protocol using a CZT device.
Journal of Nuclear Medicine 08/2011; 52(8):1204-9. · 6.38 Impact Factor
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Aju P Pazhenkottil,
Rene N Nkoulou,
Jelena-Rima Ghadri, Bernhard A Herzog,
Silke M Küest,
Lars Husmann,
Mathias Wolfrum,
Robert Goetti,
Ronny R Buechel,
Oliver Gaemperli,
Thomas F Lüscher,
Philipp A Kaufmann
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ABSTRACT: Cardiac hybrid imaging by fusing single-photon emission computed tomography (SPECT) myocardial perfusion imaging with coronary computed tomography angiography (CCTA) provides important complementary diagnostic information for coronary artery disease (CAD) assessment. We aimed at assessing the impact of cardiac hybrid imaging on the choice of treatment strategy selection for CAD.
Three hundred and eighteen consecutive patients underwent a 1 day stress/rest (99m)Tc-tetrofosmin SPECT and a CCTA on a separate scanner for evaluation of CAD. Patients were divided into one of the following three groups according to findings in the hybrid images obtained by fusing SPECT and CCTA: (i) matched finding of stenosis by CCTA and corresponding reversible SPECT defect; (ii) unmatched CCTA and SPECT finding; (iii) normal finding by both CCTA and SPECT. Follow-up was confined to the first 60 days after hybrid imaging as this allows best to assess treatment strategy decisions including the revascularization procedure triggered by its findings. Hybrid images revealed matched, unmatched, and normal findings in 51, 74, and 193 patients. The revascularization rate within 60 days was 41, 11, and 0% for matched, unmatched, and normal findings, respectively (P< 0.001 for all inter-group comparisons).
Cardiac hybrid imaging with SPECT and CCTA provides an added clinical value for decision making with regard to treatment strategy for CAD.
European Heart Journal 07/2011; 32(22):2824-9. · 10.48 Impact Factor
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ABSTRACT: To establish the value of the main pulmonary artery (MPA) diameter assessed from unenhanced computer tomography (CT) scans used for attenuation correction (AC) of single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) to predict pulmonary hypertension (PHT).
In contrast-enhanced chest CT scans an MPA diameter of 29 mm or greater is an established predictor of PHT. However, it is unknown, whether measurements from an unenhanced CT scan for AC may be used as predictor of PHT.
100 patients underwent SPECT MPI for assessment of coronary artery disease. PHT was defined as a right ventriculo-atrial gradient of 30 mm Hg or greater by Doppler echocardiography. We compared MPA diameter from CT to SPECT findings (right ventricular hypertrophy/enlargement, septal wall motion abnormality/perfusion defect, and D-shape) to determine the best predictor of PHT.
PHT was found in 37 patients. An MPA diameter of 30 mm or greater yielded a sensitivity, specificity, accuracy, positive, and negative predictive value of 78%, 91%, 86%, 83%, and 88%, respectively. This yielded an area under the ROC curve of 0.85.
MPA diameter from low-dose unenhanced multi-slice CT reliably predicts PHT, providing an important added clinical value from AC for SPECT MPI.
Journal of Nuclear Cardiology 06/2011; 18(4):634-41. · 2.67 Impact Factor
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Aju P Pazhenkottil,
Ronny R Buechel,
Rene Nkoulou,
Jelena-Rima Ghadri, Bernhard A Herzog,
Lars Husmann,
Mathias Wolfrum,
Silke M Küest,
Michael Fiechter,
Oliver Gaemperli,
Philipp A Kaufmann
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ABSTRACT: The outcome of patients with severe ischaemic left ventricular (LV) dysfunction is determined by the extent of myocardial viability and the presence of LV dyssynchrony. We aimed at assessing both parameters from the same imaging method, i.e. gated positron emission tomography (PET) F18-fluorodeoxyglucose (FDG) scans.
Phase analysis from Emory Cardiac Toolbox was applied on gated PET-FDG scans to assess histogram bandwidth and standard deviation (SD) as a measure of LV dyssynchrony in 30 heart failure patients (mean ejection fraction: 30.2% ± 13.8%) referred for the evaluation of myocardial viability. Cut-off values from single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) best predicting cardiac resynchronization therapy (CRT) response served as standard of reference (bandwidth < 135°; phase SD < 43°). Severe LV dyssynchrony was diagnosed if both SPECT-MPI values were above these limits. Intraclass correlation and clinical agreement in detection of severe LV dyssynchrony by PET vs SPECT were assessed.
There was a significant correlation between PET-FDG and SPECT-MPI for bandwidth (r = 0.88, P < .001) and phase SD (r = 0.88, P < .001) resulting in an excellent clinical agreement between the two methods of 93%.
Accurate LV dyssynchrony assessment by phase analysis of gated PET-FDG scans is feasible, allowing assessing myocardial viability and severe LV dyssynchrony in one scan.
Journal of Nuclear Cardiology 06/2011; 18(5):920-5. · 2.67 Impact Factor
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Jelena R Ghadri,
Aju P Pazhenkottil,
Rene N Nkoulou,
Robert Goetti,
Ronny R Buechel,
Lars Husmann, Bernhard A Herzog,
Mathias Wolfrum,
Christophe A Wyss,
Christian Templin,
Philipp A Kaufmann
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ABSTRACT: To study the clinical impact of a very high coronary artery calcium score (CAC >1000) in patients with no known coronary artery disease (CAD) and normal single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). The secondary aim was to evaluate whether triple vessel disease would support the notion of balanced ischaemia as an underlying mechanism of false negative SPECT MPI in patients with very high CAC.
No data exist on the clinical value of high CAC in patients with normal SPECT MPI.
50 patients with suspected CAD and normal stress/rest SPECT MPI and CAC >1000 prospectively underwent invasive coronary angiography as the standard of reference. Coronary lesions with ≥50% luminal diameter narrowing on invasive coronary angiography were considered to represent significant stenosis.
The median total CAC was 1975 (range 1018-8046). In 37/50 (74%) patients, coronary angiography revealed one-vessel disease (1-VD) (n=15), 2-VD (n=10) or 3-VD (n=12). Twenty-six revascularisations (percutaneous coronary intervention/coronary artery bypass grafting) were performed in seven (6/1), seven (6/1) and 12 (7/5) patients with 1-VD, 2-VD and 3-VD, respectively.
In patients with normal SPECT MPI, a CAC >1000 confers a high diagnostic added value for detecting CAD. This is not solely based on unmasking balanced ischaemia due to epicardial 3-VD, as it occurred predominantly in patients with 1-VD and 2-VD.
Heart (British Cardiac Society) 06/2011; 97(12):998-1003. · 4.22 Impact Factor
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Jelena R Ghadri,
Robert Goetti,
Michael Fiechter,
Aju P Pazhenkottil,
Silke M Küest,
Rene N Nkoulou,
Christina Windler,
Ronny R Buechel, Bernhard A Herzog,
Oliver Gaemperli,
Christian Templin,
Philipp A Kaufmann
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ABSTRACT: Coronary artery calcium (CAC) scoring has emerged as a tool for risk stratification and potentially for monitoring response to risk factor modification. Therefore, repeat measurements should provide robust results and low inter-scanner variability for allowing meaningful comparison. The purpose of this study was to investigate inter-scanner variability of CAC for Agatston, volume, and mass scores by head-to-head comparison using two different cardiac computed tomography scanners: 64-detector multislice CT (MSCT) and 64-slice dual-source CT (DSCT).
Thirty patients underwent CAC measurements on both 64-MSCT (GE LightSpeed XT scanner: 120 kV, 70 mAs, 2.5 mm slices) and 64-DSCT (Siemens Somatom Definition: 120 kV, 80 mAs, 3 mm slices) within <100 days (0-97). Retrospective intra-scan comparison revealed an excellent correlation. The excellent intra-scan (inter-observer) agreement was documented by narrow limits of agreement and a correlation coefficient of variation (COV) of r ≥ 0.99 (P < 0.001) for all CAC scores with a low COV for both scanners (64-MSCT/64-DSCT), i.e. Agatston (2.0/2.1%), mass (3.0/2.0%), and volume (4.7/3.9%). Inter-scanner comparison revealed larger Bland-Altman (BA) limits of agreement, despite high correlation (r ≥ 0.97) for all scores, with COV at 15.1, 21.6, and 44.9% for Agatston, mass, and volume scores. The largest BA limits were observed for volume scores (-1552.8 to 574.2), which was massively improved (-241.0 to 300.4, COV 11.5%) after reanalysing the 64-DSCT scans (Siemens) with GE software/workstation (while Siemens software/workstation does not allow cross-vendor analysis). Phantom measurements confirmed overestimation of volume scores by 'syngo Ca-Scoring' (Siemens) software which should therefore be reviewed (vendor has been notified).
Intra- and inter-scan agreement of CAC measurement in a given data set is excellent. Inter-scanner variability is reasonable, particularly for Agatston units in the clinically most relevant range <1000. The use of different software solutions has a greater influence particularly on volume scores than the use of different scanner types.
European Heart Journal 05/2011; 32(15):1865-74. · 10.48 Impact Factor
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ABSTRACT: To assess the prognostic value of low-dose 64-slice coronary CT angiography (CCTA) using prospective ECG triggering in a patient population with known or suspected coronary artery disease (CAD).
Longitudinal follow-up study.
Tertiary referral cardiac imaging centre.
434 consecutive patients who were referred for evaluation of CAD by CCTA.
The presence, distribution and severity of coronary lesions (non-obstructive <50% vs obstructive ≥50% luminal narrowing) were recorded by low-dose prospective ECG-triggered CCTA for each patient. The prognostic value of low-dose CCTA to predict major adverse cardiac events, defined as cardiac death, non-fatal myocardial infarction, or the need for revascularisation, was assessed using multivariate Cox regression analysis. Each person was followed up by telephone interviews and/or on the basis of clinical records. Thirty-eight early revascularised patients were excluded from outcome analysis.
Completely normal coronary arteries were documented in 171 patients (47%), while exclusively non-obstructive lesions were found in 66 (18%), and obstructive coronary lesions were diagnosed in 130 patients (35%). A mean follow-up of 47±16 weeks was obtained. The first-year event rate was 0% in patients with normal coronary arteries on CCTA but increased to 3% and 26% in patients with non-obstructive and obstructive coronary artery lesions, respectively. In multivariate Cox regression analysis, a significant predictor of events was the presence of obstructive or any coronary lesions. Mean effective radiation dose was 1.8±0.6 mSv.
These data document an excellent prognostic performance of low-dose CCTA.
Heart (British Cardiac Society) 04/2011; 97(17):1385-90. · 4.22 Impact Factor
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Ronny R Buechel, Bernhard A Herzog,
Lars Husmann,
Irene A Burger,
Aju P Pazhenkottil,
Valerie Treyer,
Ines Valenta,
Patrick von Schulthess,
René Nkoulou,
Christophe A Wyss,
Phillip A Kaufmann
European Journal of Nuclear Medicine 04/2011; · 4.53 Impact Factor
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ABSTRACT: The aim of this study was to determine the impact of attenuation correction with CT (CT-AC) on the prognostic value of SPECT myocardial perfusion imaging (SPECT MPI).
The summed stress score (SSS; 20-segment model) was obtained from filtered backprojection (FBP) and iterative reconstruction with CT-AC in 876 consecutive patients undergoing a 1-d stress-rest (99m)Tc-tetrofosmin SPECT MPI study for the evaluation of known or suspected coronary artery disease. Survival free of major adverse cardiac events (MACEs; cardiac death or nonfatal myocardial infarction) and survival free of any adverse cardiac events (including cardiac hospitalization, unstable angina, and late coronary revascularization) were analyzed by Kaplan-Meier analysis.
At a mean follow-up of 2.3 ± 0.6 y, a total of 184 adverse events occurred in 145 patients, including 35 MACEs (16 cardiac deaths [rate, 1.8%] and 19 nonfatal myocardial infarctions [rate, 2.2%]). With FBP, an SSS of 0-3 best distinguished patients with a low MACE rate (0.6%), followed by an SSS of 4-8 (4.3%), with increased MACE rate, and an SSS of 9-13 (3.8%), which was comparable. By contrast, with CT-AC the discrimination of low from intermediate MACE rate was best observed between an SSS of 0 (0%) and an SSS of 1-3 (3.7%), with a plateau at an SSS of 4-8 (3.2%).
CT-AC for SPECT MPI allows improved risk stratification. The prognostically relevant SSS cutoff is shifted toward lower values.
Journal of Nuclear Medicine 02/2011; 52(2):196-200. · 6.38 Impact Factor
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Aju P Pazhenkottil,
René N Nkoulou,
Jelena-Rima Ghadri, Bernhard A Herzog,
Ronny R Buechel,
Silke M Küest,
Mathias Wolfrum,
Michael Fiechter,
Lars Husmann,
Oliver Gaemperli,
Philipp A Kaufmann
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[hide abstract]
ABSTRACT: Aims Although cardiac hybrid imaging, fusing single-photon emission computed tomography (SPECT) myocardial perfusion imaging with coronary computed tomography angiography (CCTA), provides important complementary diagnostic information for coronary artery disease (CAD) assessment, no prognostic data exist on the predictive value of cardiac hybrid imaging. Hence, the aim of this study was to assess the prognostic value of hybrid SPECT/CCTA images. Methods and results Of 335 consecutive patients undergoing a 1-day stress/rest (99m)Tc-tetrofosmin SPECT and a CCTA, acquired on stand-alone scanners and fused to obtain cardiac hybrid images, follow-up was obtained in 324 patients (97%). Survival free of all-cause death or non-fatal myocardial infarction (MI) and free of major adverse cardiac events (MACE: death, MI, unstable angina requiring hospitalization, coronary revascularizations) was determined using the Kaplan-Meier method for the following groups: (i) stenosis by CCTA and matching reversible SPECT defect; (ii) unmatched CCTA and SPECT finding; and (iii) normal finding by CCTA and SPECT. Cox's proportional hazard regression was used to identify independent predictors for cardiac events. At a median follow-up of 2.8 years (25th-75th percentile: 1.9-3.6), 69 MACE occurred in 47 patients, including 20 death/MI. A corresponding matched hybrid image finding was associated with a significantly higher death/MI incidence (P < 0.005) and proved to be an independent predictor for MACE. The annual death/MI rate was 6.0, 2.8, and 1.3% for patients with matched, unmatched, and normal findings. Conclusion Cardiac hybrid imaging allows risk stratification in patients with known or suspected CAD. A matched defect on hybrid image is a strong predictor of MACE.
European Heart Journal 02/2011; 32(12):1465-71. · 10.48 Impact Factor
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ABSTRACT: We sought to assess the feasibility of prospective electrocardiogram triggering for achieving low-dose computed tomography coronary angiography (CTCA) in a large population.
Prospective electrocardiogram triggering dramatically reduces radiation exposure for CTCA but requires heart rate (HR) control to obtain diagnostic image quality. Its feasibility in daily clinical routine has therefore remained to be elucidated.
We evaluated 612 patients consecutively referred for CTCA by 64-slice computed tomography. Intravenous metoprolol (2 to 30 mg) was administered if necessary to achieve a target HR below 65 beats/min. Image quality was assessed on a semiquantitative 4-point scale for each coronary segment.
Forty-six (7.5%) patients were deemed ineligible due to irregular heart rhythm (n = 19), insufficient response to metoprolol (n = 21), renal insufficiency (n = 3), or inability to follow breath-hold commands (n = 3). Mean effective radiation dose was 1.8 ± 0.6 mSv with a diagnostic image quality in 96.2% of segments. Finally, low-dose CTCA allowed a firm diagnosis with regard to the presence or absence of coronary artery disease in 527 (86.1%) patients. Intravenous metoprolol to achieve an HR below 65 beats/min was used in 64.4% of patients. Incidence of nondiagnostic segments was inversely related to HR (r = -0.809, p < 0.001). Below an HR cutoff of 62 beats/min, only 1.2% of coronary segments were nondiagnostic.
Low-dose CTCA by electrocardiogram triggering is feasible in the vast majority of an every-day population. However, HR control is crucial, as an HR below 62 beats/min favors diagnostic image quality.
Journal of the American College of Cardiology 01/2011; 57(3):332-6. · 14.16 Impact Factor
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Joëlla E van Velzen,
Joanne D Schuijf,
Jacob M van Werkhoven, Bernhard A Herzog,
Aju P Pazhenkottil,
Eric Boersma,
Fleur R de Graaf,
Arthur J Scholte,
Lucia J Kroft,
Albert de Roos,
Marcel P Stokkel,
J Wouter Jukema,
Philipp A Kaufmann,
Ernst E van der Wall,
Jeroen J Bax
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ABSTRACT: previous studies have shown that the presence of stenosis alone on multislice computed tomography (MSCT) has a limited positive predictive value for the presence of ischemia on myocardial perfusion imaging (MPI). The purpose of this study was to assess which variables of atherosclerosis on MSCT angiography are related to ischemia on MPI.
both MSCT and MPI were performed in 514 patients. On MSCT, the calcium score, degree of stenosis (≥ 50% and ≥ 70% stenosis), and plaque extent and location were determined. Plaque composition was classified as noncalcified, mixed, or calcified. Ischemia was defined as a summed difference score (≥ 2 on a per-patient basis. Ischemia was observed in 137 patients (27%). On a per-patient basis, multivariate analysis showed that the degree of stenosis (presence of (≥ 70% stenosis, odds ratio=3.5), plaque extent and composition (mixed plaques (≥3, odds ratio=1.7; calcified plaques ≥ 3, odds ratio=2.0), and location (atherosclerotic disease in the left main coronary artery and/or proximal left anterior descending coronary artery, odds ratio=1.6) were independent predictors for ischemia on MPI. In addition, MSCT variables of atherosclerosis, such as plaque extent, composition, and location, had significant incremental value for the prediction of ischemia over the presence of ≥70% stenosis.
in addition to the degree of stenosis, MSCT variables of atherosclerosis describing plaque extent, composition, and location are predictive of the presence of ischemia on MPI.
Circulation Cardiovascular Imaging 11/2010; 3(6):718-26. · 5.94 Impact Factor
