Showing papers by "Stefan Martinoff published in 2012"

Image Quality and Radiation Exposure With Prospectively ECG-Triggered Axial Scanning for Coronary CT Angiography: The Multicenter, Multivendor, Randomized PROTECTION-III Study

Abstract: Objectives The purpose of this study was to evaluate image quality and radiation dose using a prospectively electrocardiogram (ECG)–triggered axial scan protocol compared with standard retrospective ECG-gated helical scanning for coronary computed tomography angiography. Background Concerns have been raised regarding radiation exposure during coronary computed tomography angiography. Although the use of prospectively ECG-triggered axial scan protocols may effectively lower radiation dose compared with helical scanning, it is unknown whether image quality is maintained in a clinical setting. Methods In a prospective, multicenter, multivendor trial, 400 patients with low and stable heart rates were randomized to either an axial or a helical coronary computed tomography angiography scan protocol. The primary endpoint was to demonstrate noninferiority in image quality with the axial scan protocol, which was assessed on a 4-point scale (1 = nondiagnostic, 4 = excellent image quality). Secondary endpoints included radiation dose and the rate of downstream testing during 30-day follow-up. Results Image quality in patients scanned with the axial scan protocol (score 3.36 ± 0.59) was not inferior compared with helical scan protocols (3.37 ± 0.59) (p for noninferiority Conclusions In patients with stable and low heart rates, the prospectively ECG-triggered axial scan protocol maintained image quality but reduced radiation exposure by 69% compared with helical scanning. Axial computed tomography data acquisition should be strongly recommended in suitable patients to avoid unnecessarily high radiation exposure. (Prospective Randomized Trial on Radiation Dose Estimates of CT Angiography in Patients Scanned With a Sequential Scan Protocol [PROTECTION-III]; NCT00612092 )

Cardiovascular risk assessment based on the quantification of coronary calcium in contrast-enhanced coronary computed tomography angiography.

Abstract: Aims The extent of coronary artery calcification (CAC) has been shown to be a strong and independent predictor for cardiovascular events. Usually, CAC scoring is performed in non-contrast-enhanced computed tomography (CT) examinations. The ability and accuracy of cardiovascular risk classification according to the degree of CAC determined in contrast-enhanced coronary CT angiography (CCTA) has not been investigated so far. The aim of this analysis was to develop and validate a method for CAC risk classification in CCTA. Methods and results In a test series of 100 patients who underwent both non-enhanced CAC scoring and CCTA, we developed a method to assess the extent of coronary calcification and the associated cardiovascular risk category in CCTA. The accuracy of the developed approach of CAC assessment in CCTA was determined in 500 consecutive patients in comparison to CAC scoring in the non-enhanced scan. CAC scoring results in the non-enhanced scan and CCTA scan showed a high correlation ( r = 0.954; P < 0.001). CAC quantification in CCTA correctly identified 98% of patients without CAC as shown in the non-enhanced scan (184 of 188 patients). When compared with non-enhanced CAC scoring, CAC scoring in CCTA grouped more than 95% of high-risk patients correctly into the same risk category according to the 75th age- and gender-specific percentiles or the absolute calcium scores. Conclusion Assessing cardiovascular risk associated with CAC is feasible and accurate in contrast-enhanced CCTA. This new technique may allow for reducing the radiation exposure of coronary CT studies while maintaining an accurate cardiovascular risk assessment, because the addition of non-enhanced scans to CCTA becomes unnecessary for comprehensive coronary CT studies.

Prognostic value of coronary computed tomographic angiography in patients with arterial hypertension

Abstract: Patients with arterial hypertension have a high risk of developing coronary artery disease (CAD), but noninvasive diagnosis of CAD remains difficult. We assessed the ability of coronary CT angiography (CCTA) to detect CAD and to predict subsequent cardiac events in hypertensive patients. We compared 906 hypertensive patients without known CAD undergoing CCTA with 906 matched normotensive patients. Besides calcium score and the degree of the most severe stenosis, the number of coronary segments with atherosclerotic changes was recorded. The primary endpoint was the occurrence of hard cardiac events defined as all cause death, nonfatal myocardial infarction or unstable angina requiring hospitalization. During a median follow-up of 29 months, there were 17 hard cardiac events in the hypertensive group and 13 events in the control group. The best predictor of events in hypertensive patients was the degree of the most severe stenosis (C-index 0.705, P < 0.001, both corrected for clinical risk). The annual event rate was 0.3% for patients without obstructive CAD and 1.5% for patients with obstructive CAD. In hypertensive patients without known CAD, coronary CT angiography allows for the identification of patients at high risk for incident cardiac events.

Repeat routine differential pulmonary blood flow measurements in congenital heart disease by MR: interstudy variability and benchmark of a clinically relevant change.

Abstract: Phase-velocity magnetic resonance (PV-MR) quantifies differential pulmonary blood flow as accurately as the previous gold standard lung perfusion scintigraphy in patients with a single pulmonary blood source supplied by a subpulmonary ventricle ([1–3][1]). Therefore, in routine clinical practice,

Comparison between magnetic resonance imaging and single-photon emission tomography for the assessment of myocardial salvage after coronary revascularization in acute myocardial infarction

Abstract: Background Myocardial salvage is an important surrogate endpoint assessing the success of coronary reperfusion in acute myocardial infarction. Single photon emission computed tomography (SPECT), the established modality for assessment of myocardial salvage, is logistically demanding and associated with a considerable radiation exposure. The combination of T2 and late-enhancement imaging in cardiac magnetic resonance (CMR) can assess myocardial salvage in one examination, but up to now data comparing both modalities is very limited. Methods We analyzed 180 patients who were treated by primary revascularization in acute myocardial infarction and underwent both SPECT and CMR for assessment of myocardial salvage. The first SPECT scan was performed with tracer injection before revascularization and image acquisition within 8 hours after revascularization, the second SPECT scan and the CMR scan were performed 3 to 7 days after the event. In CMR T2 weighted turbospin echo sequences and inversion recovery gradient echo sequences 15 minutes after application of dimeglumingadopentetat were performed. Area at risk and infarct size was quantified automatically using thresholds of 2 resp. 3 standard deviations above healthy myocardium. Results With SPECT, mean area at risk was 29.4 ± 18.7% of left ventricle (LV) and infarct size was 14.7 ± 16.9% LV, resulting in a mean salvage are of 14.9 ± 15.1% LV. With MRI, mean area at risk was 28.0 ± 14.5% LV and infarct size was 16.0 ± 13.5% LV, resulting in a mean salvage are of 11.9 ± 12.3%. Results of both modalities correlated well for area at risk (r=0.80), scar size (r=0.87) and salvage area (r=0.66, all p<0.0001, see also Figure below). Conclusions Assessment of the salvage area by CMR using T2 and late enhancement imaging correlates well with the established modality of SPECT. The use of CMR for myocardial salvage assessment can significantly simplify the procedure and may make the method usable beyond the realm of highly specialized centers. Funding

Gender differences in contrast-enhanced magnetic resonance imaging after acute myocardial infarction

Abstract: Besides different risk profiles for cardiovascular events in men and women, several studies reported gender differences in mortality after acute myocardial infarction (AMI). As infarct size has been shown to correlate with mortality, it is widely accepted as surrogate marker for clinical outcome. Currently, cardiovascular imaging studies covering the issue of gender differences are rare. As magnetic resonance scar characterization parameters are emerging as additional prognostic factors after acute myocardial infarction, we sought to evaluate gender differences in CMR infarct characteristics in patients after acute myocardial infarction. We prospectively analyzed patients (n = 448) with AMI and primary angioplasty, who underwent contrast enhanced cardiac magnetic resonance (CMR) imaging on a 1.5 T scanner in median 5 [Galatius-Jensen et al. in BMJ 313(7050):137–140, (1996), Burns et al. in J Am Coll Cardiol 39(1):30–36, (2002)] days after the acute event. CMR scar size was measured 15 min after gadolinium injection. In addition presence and extent of microvascular obstruction (MVO) was assessed. A matched pair analysis was performed in order to exclude confounding by gender related co-morbidities and gender differences in established clinical risk factors. Matching process according to clinical risk defined by GRACE score resulted in 93 mixed gender couples. Women were significantly older than men (64.4 ± 11.9 vs. 60.5 ± 12.3, p = 0.03) and presented with a significantly better ejection fraction before angioplasty (48.9 ± 8.4 vs. 46.2 ± 8.9, p = 0.04). Infarct size did not differ significantly between women and men (13.5 ± 10.7 vs. 15.1 ± 11.8, p = 0.32). Size of MVO was significantly smaller in women than in men (0.48 ± 1.3 vs. 1.2 ± 3.0, p = 0.03). Comparing scar characterization between women and men with similar risk profiles revealed no gender differences in scar size. Size of MVO, however, was significantly smaller in women and might reflect better cardioprotective mechanisms in women. Whether these changes have prognostic implications has to be tested on a larger patient population.