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ABSTRACT: New technology combining dual-energy CT with the latest gemstone detectors for spectral imaging (GSI) can be used to synthesize monochromatic images that mimic images as if different monochromatic x-ray sources were used.
The aim of the study was to evaluate the optimal combination of monochromatic image energy and adaptive statistical iterative reconstruction (ASiR) for monochromatic reconstruction of coronary CT angiography (CTA) images with the use of GSI.
Twenty consecutive patients underwent coronary CTA on a GSI capable 64-slice CT scanner (Discovery CT 750 High Definition, GE Healthcare). In 7 sets of monochromatic images (60, 65, 70, 75, 80, 90, and 110 keV; each with increasing contributions of ASiR, ie, 0%, 20%, 40%, 60%, and 80%; n = 35 reconstructions per patient), signal-to-noise (aortic root) and contrast-to-noise (left main artery) ratios were assessed. Signal-to-noise ratio, contrast-to-noise ratio, and image quality (graded on a 5-point Likert scale) were assessed in all above monochromatic reconstructions and compared with the respective standard (conventional polychromatic) image.
Compared with conventional polychromatic images, reconstructions with 60 keV and 80% ASiR showed the highest improvement in contrast-to-noise (144%; P < 0.001) and signal-to-noise ratio (173%; P < 0.001). Image quality reached a plateau at 65-75 keV with 40%-60% ASiR blending, yielding a maximal image quality score improvement of 50% compared with conventional imaging (P < 0.001).
In coronary CTA with low radiation technique (mean radiation dose, 1.8 ± 0.7 mSv), GSI with monochromatic reconstructions (65-75 keV) and ASiR (40%-60%) offers significant noise reduction and image quality improvement.
Journal of cardiovascular computed tomography 01/2013; 7(1):25-31.
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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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ABSTRACT: A new generation of high definition computed tomography (HDCT) 64-slice devices complemented by a new iterative image reconstruction algorithm-adaptive statistical iterative reconstruction, offer substantially higher resolution compared to standard definition CT (SDCT) scanners. As high resolution confers higher noise we have compared image quality and radiation dose of coronary computed tomography angiography (CCTA) from HDCT versus SDCT. Consecutive patients (n = 93) underwent HDCT, and were compared to 93 patients who had previously undergone CCTA with SDCT matched for heart rate (HR), HR variability and body mass index (BMI). Tube voltage and current were adapted to the patient's BMI, using identical protocols in both groups. The image quality of all CCTA scans was evaluated by two independent readers in all coronary segments using a 4-point scale (1, excellent image quality; 2, blurring of the vessel wall; 3, image with artefacts but evaluative; 4, non-evaluative). Effective radiation dose was calculated from DLP multiplied by a conversion factor (0.014 mSv/mGy × cm). The mean image quality score from HDCT versus SDCT was comparable (2.02 ± 0.68 vs. 2.00 ± 0.76). Mean effective radiation dose did not significantly differ between HDCT (1.7 ± 0.6 mSv, range 1.0-3.7 mSv) and SDCT (1.9 ± 0.8 mSv, range 0.8-5.5 mSv; P = n.s.). HDCT scanners allow low-dose 64-slice CCTA scanning with higher resolution than SDCT but maintained image quality and equally low radiation dose. Whether this will translate into higher accuracy of HDCT for CAD detection remains to be evaluated.
The international journal of cardiovascular imaging 07/2012; · 2.15 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: PurposeThe purpose of the study is to determine the impact of 13N-ammonia positron emission tomography (PET) myocardial perfusion imaging (MPI) on clinical decision making and its cost-effectiveness.
Materials and methodsOne hundred consecutive patients (28 women, 72 men; mean age 60.9 ± 12.0years; range 24–85years) underwent 13N-ammonia PET scanning (and computed tomography, used only for attenuation correction) to assess myocardial perfusion in patients
with known (n = 79) or suspected (n = 8) coronary artery disease (CAD), or for suspected small-vessel disease (SVD; n = 13). Before PET, the referring physician was asked to determine patient treatment if PET would not be available. Four weeks
later, PET patient management was reassessed for each patient individually.
ResultsBefore PET management strategies would have been: diagnostic angiography (62 of 100 patients), diagnostic angiography and
percutaneous coronary intervention (PCI; 6 of 100), coronary artery bypass grafting (CABG; 3 of 100), transplantation (1 of
100), or conservative medical treatment (28 of 100). After PET scanning, treatment strategies were altered in 78 patients
leading to: diagnostic angiography (0 of 100), PCI (20 of 100), CABG (3 of 100), transplantation (1 of 100), or conservative
medical treatment (76 of 100). Patient management followed the recommendations of PET findings in 97% of the cases. Cost-effectiveness
analysis revealed lower costs of €206/patient as a result of PET scanning.
ConclusionIn a population with a high prevalence of known CAD, PET is cost-effective and has an important impact on patient management.
European journal of nuclear medicine and molecular imaging 04/2012; 35(5):889-895. · 4.99 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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ABSTRACT: To analyze the effect of H1N1 influenza A virus vaccination in patients referred for staging or follow-up F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for different malignant tumors.
Medical history of all patients scheduled for FDG PET/CT during the national vaccination campaign against H1N1 was evaluated for recent vaccination. Site of injection and time between PET/CT and the date of vaccination (dTime) was determined. A difference in the maximum SUV between ipsi- and contralateral deltoid muscle or axillary lymph node of more than 0.5 was determined as positive reaction. The best cut-off dTime for still visible reaction was calculated. All patients with positive ipsilateral lymph node were clinically followed. Institutional Review Board approval was waived.
Of 269 patients, 58 (21.5%) were vaccinated for the H1N1 within 4 weeks prior to PET/CT (mean, 14.5 ± 8.7 days). Of them, 17 (29.3%) patients had FDG-positive lymph nodes (mean SUV, 1.43 ± 1.06), with a dTime range from 1 to 14 days. Only 2 of them had no increased FDG uptake in the ipsilateral deltoid muscle. The area under the receiver operator characteristic curve revealed a strong relation between time delay (dTime) and axillary activity (AUC, 0.9; 95% confidence interval, 0.816-0.983) with a cutoff at 8 days (Youden Index). At follow-up (mean, 183 days; range, 173-196 days), no patient was found to have required treatment or signs of axillary lymphadenopathy.
H1N1 vaccination can cause false-positive FDG PET/CT findings, when administered less than 14 days before the test, with the highest probability if the vaccination was administered less than 8 days ago. Increased FDG activity in the ipsilateral deltoid muscle is a key finding for accurate interpretation of increased FDG activity in axillary lymph nodes.
Clinical nuclear medicine 10/2011; 36(10):848-53. · 3.92 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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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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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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Heart (British Cardiac Society) 12/2010; 96(24):2050. · 4.22 Impact Factor
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European Heart Journal 12/2010; 32(7):790. · 10.48 Impact Factor
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ABSTRACT: To validate the ultrafast assessment of left ventricular (LV) dyssynchrony by phase analysis using high-speed nuclear myocardial perfusion imaging (MPI) on a new gamma camera with cadmium-zinc-telluride (CZT) solid-state detector technology.
In 46 patients rest MPI with 960 MBq (99m)Tc-tetrofosmin was acquired on a dual-head detector SPECT camera (Ventri, GE Healthcare) and an ultrafast CZT camera (Discovery NM 530c, GE Healthcare) with acquisition times of 15 and 5 min, respectively. LV dyssynchrony was assessed using the Emory Cardiac Toolbox with established values for histogram bandwidth (male <62.4°; female <49.7°) and standard deviations (male <24.4°; female <22.1°) as the gold standard. Evaluating CZT scan times of 0.5, 1, 2, 3 and 5 min (list mode) in 16 patients revealed the preferred scan time to be 5 min, which was then applied in all 46 patients. Intraclass correlation and the level of agreement in dyssynchrony detection between the CZT and Ventri cameras were assessed.
In LV dyssynchrony the mean histogram bandwidths with the CZT camera (n = 8) and the Ventri camera (n = 9) were 123.3 ± 50.6° and 130.2 ± 43.2° (p not significant) and 42.4 ± 13.6° vs. 43.2 ± 12.7° (p not significant). Normal bandwidths and SD obtained with the CZT camera (35.9 ± 7.7°, 12.6 ± 3.5°) and the Ventri camera (34.8 ± 6.6°, 11.1 ± 2.1°, both p not significant) excluded dyssynchrony in 38 and 37 patients, respectively. Intraclass correlation and the level of agreement between the CZT camera with a 5-min scan time and the Ventri camera were 0.94 (p < 0.001, SEE 14.4) and 96% for histogram bandwidth and 0.96 (p < 0.001, SEE 3.9) and 98% for SD.
This ultrafast CZT camera allows accurate assessment of LV dyssynchrony with a scan time of only 5 min, facilitating repeat measurements which would potentially be helpful for parameter optimization for cardiac resynchronization therapy.
European Journal of Nuclear Medicine 11/2010; 37(11):2086-92. · 4.53 Impact Factor
