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Marcus Hacker

Publications and source records attributed to Marcus Hacker.

9 recordsLinked to original sources
PubMed2006

Sixty-four slice spiral CT angiography does not predict the functional relevance of coronary artery stenoses in patients with stable angina.

PURPOSE: The aim of this study was to evaluate spiral multidetector computed tomography (MDCT) angiography using 64-slice technique in the detection of functionally relevant coronary artery stenoses (CAS). METHODS: Thirty-eight patients (62+/-11 years, 28 men) with stable angina (26 with suspected and 12 with known coronary artery disease) were investigated using 64-slice MDCT angiography and gated myocardial perfusion SPECT (gated SPECT); a subgroup of 30 patients had additional invasive coronary angiography (ICA). Stenoses with luminal narrowing of >or=50% were defined as "significant" in MDCT angiography and ICA. MDCT angiography was compared with gated SPECT and the combination of gated SPECT plus ICA with respect to the detection of functionally relevant CAS. RESULTS: The sensitivity, specificity and negative and positive predictive values of MDCT angiography in detecting reversible perfusion defects on gated SPECT were 63%, 80%, 94% and 32%, respectively, in vessel-based analysis and 71%, 62%, 72% and 60%, respectively, in patient-based analysis. If only reversible perfusion defects on gated SPECT with CAS >or=50% on ICA were considered, the sensitivity, specificity and negative and positive predictive values were, respectively, 85%, 79%, 98% and 33% for vessel-based analysis and 85%, 59%, 83% and 61% for patient-based analysis. CONCLUSION: Sixty-four slice MDCT angiography failed to predict the functional relevance of CAS, but had a high negative predictive value in the exclusion of functionally relevant CAS in symptomatic patients.

Angina Pectoris↗
PubMed2006

Value of PET/CT versus PET and CT performed as separate investigations in patients with Hodgkin's disease and non-Hodgkin's lymphoma.

PURPOSE: The aim of this study was to assess the clinical benefit of combined [(18)F]FDG PET/CT in patients with malignant lymphoma as compared to separately performed PET and CT. METHODS: Overall, 100 patients with Hodgkin's disease (HD) or non-Hodgkin's lymphoma (NHL) were included in this study. Co-registered PET/CT with [(18)F]FDG and contrast medium was performed in 50 consecutive patients with NHL (n=38) or HD (n=12) for initial staging (IS) (n=12) or re-treatment staging (RS) (n=38). Another 50 patients with NHL (n=32) or HD (n=18) underwent separate PET and CT investigations within a time frame of 10 days for IS (n=22) or RS (n=28). Lymphoma involvement was separately evaluated for seven different regions in each patient. Each patient had clinical follow-up evaluation for >6 months. PET and CT data were analysed separately as well as side-by-side or in fused mode. RESULTS: In the PET/CT group, region-based evaluation for lymphoma involvement suggested a sensitivity/specificity of 85%/91% for CT, 98%/99% for PET and 98%/99% for PET/CT. In the PET and CT group, region-based evaluation showed a sensitivity/specificity of 87%/80% for CT, 98%/99% for PET and 98%/100% for PET and CT read side by side. CONCLUSION: PET was superior to CT alone and was improved further by side-by-side reading of both examinations. However, no significant difference was observed between PET/CT and separate PET and CT imaging in patients with lymphoma.

Adult↗
PubMed2006

Value of 99mTc-TRODAT-1 SPECT to predict clinical response to methylphenidate treatment in adults with attention deficit hyperactivity disorder.

BACKGROUND: In a previous study, binding of Tc-TRODAT-1 to the dopamine transporter (DAT) was found to be higher in patients with attention deficit hyperactivity disorder (ADHD) as compared to healthy controls. AIM: To determine whether the degree of Tc-TRODAT-1 binding to the striatal DAT may have a predictive role on the response to methylphenidate (MPH) in patients with ADHD. METHODS: Twenty-two adult patients suffering from ADHD underwent a brain SPECT scan with Tc-TRODAT-1. After the scan patients received MPH, individually medicated up to 60 mg.day. Severity of illness was estimated using the Clinical Global Impression (CGI-S) Scale before treatment. Ten weeks after the beginning of MPH treatment the improvement in global symptoms was rated by the Clinical Global Improvement Scale (CGI-I). RESULTS: Before treatment 17/22 patients with ADHD presented with higher striatal DAT binding as compared to age-matched healthy controls (+23.8%; P<0.01). After treatment with MPH a significant improvement of ADHD symptoms was demonstrated by the CGI-I in 16 of these 17 patients (CGI-S before: 4.8; CGI-I after MPH: 1.9; P<0.01). Five patients showed reduced DAT binding prior to therapy (-14.4%; P=0.04); these patients did not respond to MPH therapy (CGI-S before: 4.5; CGI-I after MPH: 4.2; P=0.40). CONCLUSION: Our findings suggest that ADHD patients with primarily elevated binding of Tc-TRODAT-1 to the striatal DAT responded better to therapy with MPH as compared to those with normal or low DAT binding. Consequently, our results - even if obtained on a small collective indicate that measurement of DAT may be an important prognostic predictor for therapy response to MPH.

Adult↗
PubMed2005

Clinical validation of the gated blood pool SPECT QBS processing software in congestive heart failure patients: correlation with MUGA, first-pass RNV and 2D-echocardiography.

INTRODUCTION: Left (LVEF) and right ventricular ejection fraction (RVEF) as well as LV regional wall motion at rest are valuable tools to monitor and tailor treatment of congestive heart failure (CHF) patients. Gated blood pool SPECT (GBPS) is under evaluation as an "all-in-one" technique, providing information on LVEF, RVEF, and wall motion derived from a single examination. Aim of the study was to evaluate a commercially available automated GBPS processing software for EF measurements and wall motion analysis in heart failure patients. METHODS: Thirty-two patients (12 female; mean age+/-SD: 53+/-13 years), suffering from dilated (63%), ischemic (25%) or hypertrophic (13%) cardiomyopathy, were studied. First-pass radionuclide ventriculography (FP-RNV), planar multigated radionuclide angiography (MUGA), and GBPS were performed at rest after in vivo labeling of red blood cells, and LVEF and RVEF was calculated with each method. Later on the same day LVEF was calculated by echocardiography. LV wall motion (summed motion score and wall motion index) was derived from GBPS and echocardiography using the standard 16-segment model. RESULTS: Mean LVEF measured by GBPS, echocardiography, MUGA and FP-RNV was 33+/-13%, 37+/-15%, 41+/-14% and 45+/-13%, respectively. LVEF values calculated from GBPS showed moderate to good correlation with FP-RNV (r=0.61), MUGA (r=0.65) and ECHO (r=0.74; all p<0.01). Mean RVEF calculated by GBPS, FP-RNV and MUGA was 45+/-14%, 46+/-9% and 38+/-9%, respectively. RVEF values calculated from GBPS showed weak correlation with FP-RNV (r=0.33) and MUGA (r=0.26; all p=n.s.). Assessment of GBPS wall motion was qualitatively possible in all patients. The agreement between GBPS and ECHO was 82% (kappa=0.73). The wall motion index showed good correlation between both methods (r=0.88; p<0.001). CONCLUSION: An automated algorithm for LVEF calculation and wall motion analysis using GBPS is feasible for clinical routine diagnostic in CHF patients. The RVEF calculation method needs to be improved before routine clinical application can be recommended.

Algorithms↗
PubMed2005

Dobutamine myocardial scintigraphy for the prediction of cardiac events after heart transplantation.

BACKGROUND: The long-term outcome after heart transplantation (HTx) is essentially influenced by the occurrence and extent of cardiac allograft vasculopathy (CAV). Single photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) has been shown to be a useful and cost-effective non-invasive method in patients with known or suspected coronary artery disease, but its role in detecting CAV remains unclear. AIM: To evaluate the accuracy and predictive value of dobutamine MPI in patients after HTx during a 12-month follow-up. METHODS: Seventy-seven patients (60 males, 17 females) underwent a total of 216 dobutamine MPI examinations over a period of 5 years. Examinations were obtained an average of 89+/-42 months after orthotopic HTx according to a 1-day protocol using 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) with and without attenuation correction. For the present study, findings from 77 MPI examinations (one MPI examination per patient) were analysed visually and semiquantitatively using a 20-segment model. Summed stress scores (SSS) and summed rest scores (SRS) were calculated and receiver operating characteristic (ROC) analysis was performed to detect optimum threshold values. Patients were followed up for 12 months and cardiac events were registered. RESULTS: Cardiac events were observed in 10 of the 77 patients. Good interobserver agreement was found for global visual and SRS-/SSS-based analysis (kappa=0.74 and 0.66, respectively). SSS was superior to SRS in the detection of cardiac events. ROC analysis showed an optimized SSS threshold value of three. For predicting a cardiac event during the 12-month follow-up, global visual and semiquantitative analysis reached sensitivities of 90% and 90%, specificities of 72% and 88%, accuracies of 74% and 87%, positive predictive values of 32% and 53% and negative predictive values of 98% and 98%, respectively. The sensitivity, specificity, accuracy and positive and negative predictive values for MPI to detect clinically relevant coronary artery stenoses (> or =50%) at conventional coronary angiography were 83%, 87%, 86%, 56% and 96%, respectively. CONCLUSIONS: Non-invasive dobutamine MPI reliably identifies patients at risk for subsequent cardiac events in cases of CAV, with a high negative predictive value of 98% and an accuracy of 87%.

Coronary Disease↗
PubMed2005

Comparison of spiral multidetector CT angiography and myocardial perfusion imaging in the noninvasive detection of functionally relevant coronary artery lesions: first clinical experiences.

UNLABELLED: Compared with conventional coronary angiography, spiral multidetector CT (MDCT) angiography has delivered promising accuracy in the detection and validation of coronary lesions. Myocardial perfusion imaging (MPI) using SPECT is an established method for noninvasively assessing the functional significance of coronary stenoses and delivers valuable information for risk stratification. This retrospective analysis compared the accuracies of MDCT angiography and MPI in the detection of hemodynamically relevant lesions of the coronary arteries. METHODS: Twenty-five patients with suspected or known coronary artery disease were studied. Electrocardiographically gated MPI and 16-MDCT angiography were performed. Myocardial perfusion images were analyzed by 2 experienced observers, and reversible and fixed perfusion defects were detected and allocated to their corresponding coronary vessels. For the evaluation of MDCT angiography, image quality was determined, and lesions > or = 50% and luminal narrowing < 50% were visually assessed and characterized by 2 independent observers unaware of the results of MPI. RESULTS: Ninety-nine coronary vessels were analyzed, and the quality of MDCT angiography images was assessed for 330 coronary segments. Coronary artery diameter was interpretable for 231 (70%) of 330 segments, whereas in 99 (30%) of 330 segments, vessel diameter could not be evaluated because of heavy calcifications, blurring, motion artifacts, or intracoronary stents. MDCT angiography detected stenoses > or = 50% in 15 of 100 coronary arteries. Eight (53%) of 15 stenoses > or = 50% showed reversible or fixed perfusion defects in the corresponding myocardial areas on MPI. Sensitivity, specificity, and negative and positive predictive values were 100%, 87%, 100%, and 29%, respectively, for the ability of MDCT angiography to detect reversible perfusion defects in the corresponding myocardial areas. CONCLUSION: MDCT angiography detected myocardial ischemia, as defined by reversible perfusion defects on MPI, with a positive predictive value of 29% in a nonselected study cohort. Compared with MPI alone, MDCT angiography added important morphologic information, but MPI remains mandatory for evaluating the functional relevance of coronary artery lesions.

Coronary Angiography↗
PubMedDate not supplied

Comparison of Tc-99m sestamibi SPECT with fractional flow reserve in patients with intermediate coronary artery stenoses.

BACKGROUND: Myocardial single photon emission computed tomography (SPECT) is an established noninvasive method for the assessment of the functional significance of coronary artery stenoses. Intracoronary pressure measurements to determine fractional flow reserve (FFR) are increasingly performed during coronary angiography whenever an immediate decision regarding possible intervention is required. We hypothesized that the regional summed difference score (SDSr), reflecting reversible perfusion defects in the myocardial supply area of the FFR target vessel, would be the best predictor of an abnormal FFR in patients without prior myocardial infarction. Otherwise, a regional summed stress score (SSSr) should be the best predictor of an abnormal FFR in patients with prior myocardial infarction for different patient subgroups with coronary artery disease. METHODS AND RESULTS: In this study 50 patients (mean age, 65 +/- 9.1 years; 18 women) with coronary artery disease and a 50% to 75% coronary stenosis (target vessel) were prospectively investigated. Dobutamine myocardial SPECT was performed as a single-day stress/rest protocol by use of technetium 99m sestamibi. For image interpretation, semiquantitative analysis was conducted by calculating SSSr and SDSr. Within 8 (+/-14.9) days, coronary angiography was performed and FFR was calculated by use of a pressure wire (normal FFR, > or = 0.75). The mean FFR of all patients was 0.78 +/- 0.14. Of 50 patients, 17 had an FFR lower than 0.75 in the target vessel. Receiver operating characteristic analysis identified an SDSr of 1 or greater and an SSSr of 3 or greater as the best threshold values for predicting ischemic FFR. Sensitivity, specificity, and negative and positive predictive values of SDSr and SSSr for the detection of FFR values lower than 0.75 in the target vessel were 80%, 76%, 53%, and 92%, respectively, and 70%, 93%, 78%, and 90%, respectively, in patients without prior myocardial infarction and 57%, 50%, 67%, and 40%, respectively, and 100%, 50%, 78%, and 100%, respectively, in patients with prior myocardial infarction. Weak correlation was found between the single values of FFR with both SDSr and SSSr for the different patient subgroups. CONCLUSION: Among the dobutamine myocardial scintigraphy variables studied, SDSr was the best predictor of an abnormal FFR (cutoff value of 0.75) in patients without prior myocardial infarction. As assumed, SSSr was the best predictor of an abnormal FFR in patients with prior myocardial infarction in the target region.

Adult↗
PubMedDate not supplied

Relationship between right ventricular ejection fraction and maximum exercise oxygen consumption: a methodological study in chronic heart failure patients.

BACKGROUND: Peak oxygen consumption at maximum exercise (peak VO(2)) predicts survival in chronic heart failure (CHF) patients. Right ventricular ejection fraction (RVEF) at rest has been reported to correlate with peak VO(2). We evaluated the strength and consistency of the association between peak VO(2) and RVEF measured by different radionuclide ventriculography (RNV) techniques in a prospective cohort study. METHODS AND RESULTS: In 58 consecutive CHF patients (mean age, 53 years; 39 patients with dilated cardiomyopathy; 48 men), upright symptom-limited bicycle ergometry was performed. During exercise, ventilatory and gas exchange data were recorded and peak VO(2) was calculated. RVEF was calculated by use of first-pass (FP) RNV with single and dual region of interest (ROI) acquisition and planar multigated acquisition (MUGA). Irrespective of the method used, RVEF showed no relevant correlation with the corresponding peak VO(2) value (r = 0.11 for FP single ROI, r = 0.06 for FP dual ROI, r = 0.16 for MUGA). Peak VO(2) or changes in peak VO(2) after 6 and 12 months of follow-up were not determined by RVEF measurements. CONCLUSION: In CHF patients no association was found between peak VO(2) at maximum exercise and RVEF at rest with different RNV techniques. Changes in exercise capacity are not reliably reflected by changes in RVEF measurements at rest.

Adult↗