Timo Baks

High-Resolution Spiral Computed Tomography Coronary Angiography in Patients Referred for Diagnostic Conventional Coronary Angiography

Background— The diagnostic performance of the latest 64-slice CT scanner, with increased temporal (165 ms) and spatial (0.4 mm3) resolution, to detect significant stenoses in the clinically relevant coronary tree is unknown. Methods and Results— We studied 52 patients (34 men; mean age, 59.6±12.1 years) with atypical chest pain, stable or unstable angina pectoris, or non–ST-segment elevation myocardial infarction scheduled for diagnostic conventional coronary angiography. All patients had stable sinus rhythm. Patients with initial heart rates ≥70 bpm received &bgr;-blockers. Mean scan time was 13.3±0.9 seconds. The CT scans were analyzed by 2 observers unaware of the results of invasive coronary angiography, which was used as the standard of reference. All available coronary segments, regardless of size, were included in the evaluation. Lesions with ≥50 luminal narrowing were considered significant stenoses. Invasive coronary angiography demonstrated the absence of significant disease in 25% (13 of 52), single-vessel disease in 31% (16 of 52), and multivessel disease in 45% (23 of 52) of patients. One unsuccessful CT scan was classified as inconclusive. Ninety-four significant stenoses were present in the remaining 51 patients. Sensitivity, specificity, and positive and negative predictive values of CT for detecting significant stenoses on a segment-by-segment analysis were 99% (93 of 94; 95% CI, 94 to 99), 95% (601 of 631; 95% CI, 93 to 96), 76% (93 of 123; 95% CI, 67 to 89), and 99% (601 of 602; 95% CI, 99 to 100), respectively. Conclusions— Noninvasive 64-slice CT coronary angiography accurately detects coronary stenoses in patients in sinus rhythm and presenting with atypical chest pain, stable or unstable angina, or non–ST-segment elevation myocardial infarction.

Improving diagnostic accuracy of MDCT coronary angiography in patients with mild heart rhythm irregularities using ECG editing.

OBJECTIVE The objective of our study was to compare diagnostic accuracy of MDCT coronary angiography in a population of patients with mild heart rhythm irregularities before and after editing the ECG. SUBJECTS AND METHODS Thirty-eight patients who underwent MDCT coronary angiography and conventional coronary angiography were enrolled in the study. The inclusion criterion was the presence of mild heart rhythm irregularities (i.e., premature beats; atrial fibrillation; mistriggering; or low heart rate, defined as 40 beats per minute or less) during the scan. All patients underwent MDCT with the following parameters: 16 detectors; collimation, 0.75 mm; gantry rotation time, 375 msec; 120 kV; and effective milliampere-second setting, 500-600. Images were reconstructed in two settings: before ECG editing and after ECG editing (i.e., arbitrary modification of temporal windows within the cardiac cycle at the site of mild heart rhythm irregularities). Data sets were scored for the presence of significant stenoses (> or = 50% lumen reduction) in coronary segments > or = 2 mm diameter. The results of the two groups were compared with a McNemar test, and a p value of less than 0.05 was considered significant. RESULTS The sensitivity, specificity, and negative and positive predictive values of MDCT coronary angiography for the detection of significant stenoses before and after ECG editing were 63% (41/65) and 92% (78/85); 97% (251/260) and 96% (305/317); 87% (62/71) and 87% (81/93); 91% (251/275) and 97% (305/313), respectively (p < 0.05). The proportion of nonassessable segments was reduced from 17% (70/416) before ECG editing to 2% (10/416) after. CONCLUSION ECG editing significantly improves diagnostic accuracy in a selected population of patients with mild heart rate irregularities.

Addition of the long-axis information to short-axis contours reduces interstudy variability of left-ventricular analysis in cardiac magnetic resonance studies

Objectives:To reduce interstudy variability using long-axis information for correcting short-axis (SA) contours at basal and apical level for left-ventricular analysis by magnetic resonance imaging. Materials and Methods:A total of 20 patients with documented heart failure and 20 volunteers underwent magnetic resonance imaging examination twice for measuring endocardial end-diastolic volume, endocardial end-systolic volume, mass, and ejection fraction. The boundary of the left ventricle, the mitral valve plane, and apex were marked manually on the 2- and 4-chamber long-axis images. Automatic epicardial and endocardial contour detection was performed on the SA images using the intersection of the outlines from the long axis as starting positions. The same observer compared the interstudy variability of this method with analysis that was based on the SA images only. Results:The interstudy variability decreased when information from the long axis was included; for end-systolic volume, 9.6% versus 4.7% (P = 0.00014); for end-diastolic volume, 4.9% versus 2.5% (P = 0.0011); for mass, 7.4% versus 5.0% (P = 0.11); and for ejection fraction 12.2% versus 5.6% (P = 0.0017), respectively. Conclusions:Identification of the mitral valve plane and apex on long-axis images to limit the extent of volume at the base and the apex of the heart reduces interstudy variability for left-ventricular functional assessment.

Assessment of acute reperfused myocardial infarction with delayed enhancement 64-MDCT.

OBJECTIVE The purpose of this study was to evaluate the utility of delayed enhancement 64-MDCT in the assessment of myocardial infarct size in a porcine model of acute reperfused myocardial infarction. CT can be used for noninvasive assessment of coronary artery stenosis, but to our knowledge, evaluation of myocardial viability in the subacute phase of acute myocardial infarction has not been validated. We performed delayed enhancement imaging on six domestic swine 5 days after reperfused acute myocardial infarction and assessed the relation between delayed enhancement patterns in vivo and the extent of viable and nonviable myocardium at postmortem histochemical analysis. CONCLUSION Delayed enhancement imaging with 64-MDCT can be used for accurate assessment of the size of reperfused acute myocardial infarcts.

Non-invasive visualization of coronary atherosclerosis: State-of-art

Coronary artery disease remains the leading cause of death in the Western world. Non-invasive coronary artery imaging challenges any diagnostic modality because the coronary arteries are small and tortuous, whereas cardiac contraction and respiration cause motion artifacts. Therefore, non-invasive coronary imaging requires high spatial and temporal resolution. This review discusses the feasible applications in coronary imaging of magnetic resonance imaging and multi-slice computed tomography (MSCT), which are currently the only non-invasive diagnostic modalities for direct coronary atherosclerosis imaging. Particular attention and focus is devoted to the potential indications and clinical impact of MSCT due to its fast development and the robust results recently reported. MSCT of the coronary arteries is a promising imaging modality for the assessment of the coronary lumen and wall.

Accurate automatic papillary muscle identification for quantitative left ventricle mass measurements in cardiac magnetic resonance imaging.

RATIONALE AND OBJECTIVES We sought to evaluate the automatic detection of the papillary muscle and to determine its influence on quantitative left ventricular (LV) mass assessment. MATERIALS AND METHODS Twenty-eight Yorkshire-Landrace swine and 10 volunteers underwent cardiac magnetic resonance imaging (CMR) of the left ventricle. The variability in measurements of LV papillary muscles traced automatically and manually were compared to intra- and interobserver variabilities. CMR-derived LV mass with the papillary muscle included or excluded from LV mass measurements was compared to true mass at autopsy of the Yorkshire-Landrace swine. RESULTS Automatic LV papillary muscle mass from all subjects correlated well with manually derived LV papillary muscle mass measurements (r = 0.84) with no significant bias between both measurements (mean difference +/- SD, 0.0 +/- 1.5 g; P = .98). The variability in results related to the contour detection method used was not statistically significant different compared to intra- and interobserver variabilities (P = .08 and P = .97, respectively). LV mass measurements including the papillary muscle showed significantly less underestimation (-10.6 +/- 7.1 g) with the lowest percentage variability (6%) compared to measurements excluding the papillary muscles (mean underestimation, -15.1 +/- 7.4 g percentage variability, 7%). CONCLUSION The automatic algorithm for detecting the papillary muscle was accurate with variabilities comparable to intra- and interobserver variabilities. LV mass is determined most accurately when the papillary muscles are included in the LV mass measurements. Taken together, these observations warrant the inclusion of automatic contour detection of papillary muscle mass in studies that involve the determination of LV mass.

Hypertrophic obstructive cardiomyopathy: Septal ablation with overlapping sirolimus-eluting and covered stents after failed alcoholization and concomitant coronary artery disease

A 61-year-old man with exertional dyspnea was diagnosed with hypertrophic obstructive cardiomyopathy. The echocardiogram demonstrated an interventricular septum with a thickness of 18 mm, marked systolic anterior motion, and mitral regurgitation grade 3. The left ventricular outflow tract (LVOT) gradient was 100 mm Hg. The patient was treated with percutaneous transluminal septal myocardial alcohol ablation, resulting in a residual LVOT gradient of 20 mm Hg. Mild coronary artery disease of the proximal left anterior descending coronary artery (LAD) and the first diagonal branch (D1) (40% diameter stenosis by quantitative coronary angiography) was left untreated. The patient remained asymptomatic for 6 months and then again had development of exertional dyspnea. The echocardiogram revealed relapse of the LVOT gradient (80 mm Hg). Repeat percutaneous transluminal septal myocardial alcohol …

Different Algorithms for Quantitative Analysis of Myocardial Infarction with DE MRI. Comparison with Autopsy Specimen Measurements.

RATIONALE AND OBJECTIVES To compare two semiautomated methods for measurement of infarcted myocardium area on delayed contrast enhanced magnetic resonance imaging, with histopathology findings as standard of reference. MATERIALS AND METHODS Percentage area of myocardial infarction was measured in 10 Yorkshire landrace pigs manually and using two semiautomated methods. The first (standard deviation method) used two operator-selected regions of interest (ROIs) and nine different cutoff values (one to nine times the standard deviation of signal intensity in normal myocardium) to identify infarction. The second (threshold method) used threshold values based on percentages of maximum signal intensity to identify infarction. Results were compared with histopathology findings. RESULTS Difference between percentage area of infarction obtained with standard deviation method and autopsy specimens was in the range: -13.5% to +13.2%. With threshold method (thresholds from 30% to 90% of signal intensity), difference was -15% to +23%. Manual contouring underestimated infarcted area by 2% comparing to autopsy results. The best agreement between histopathology and semi-automated software was achieved for 4 standard deviations with standard deviation method: difference -0.45%, and for a percentage threshold of 70% (difference +0.67%) with threshold method. However, with standard deviation method, there was statistically significant difference between ROIs based on their location in viable myocardium: mean difference 1.7 ± 4%, P < .0001. CONCLUSION Semiautomated measurement of myocardial infarcted area on delayed enhanced magnetic resonance images performs well compared to autopsy. The threshold method, based on percentages of maximum signal intensity is preferable over standard deviation method, which is more susceptible to variability from location of ROIs within viable myocardium.

Chronic pseudoaneurysm of the left ventricle

We present a case of a 55-year-old men who suffered a silent myocardial infarction four years earlier and presented with exertional dyspnoea. Cardiac magnetic resonance imaging (CMR) and Multislice computed tomography (MSCT) was performed and revealed a giant pseudoaneursym of the lateral wall of the left ventricle with the presence of a thrombus in the lateral wall of the pseudoaneursym. We present this case since excellent non-invasive evaluation of the pseudoaneursym was feasible using state-of-the-art imaging modalities. Information on left ventricular geometry and function as well as myocardial viability and coronary anatomy is available when both MSCT and CMR are performed. This combined approach of these two imaging modalities provide clinically relevant information and may guide therapeutic decision making.

Impact of contrast material volume on quantitative assessment of reperfused acute myocardial infarction using delayed-enhancement 64-slice CT: experience in a porcine model

PurposeOur purpose in this study was to compare the impact of contrast material volume in delayed-enhancement computer tomography (CT) imaging for assessing acute reperfused myocardial infarction.Materials and methodsIn five domestic pigs (20–30 kg), the circumflex coronary artery (CX) was balloon-occluded for 2 h followed by reperfusion. After 5 days, CT imaging was performed after intravenous administration of iodinated contrast material (Iomeprol 400mgI/ml; Bracco, Italy). A 64-slice multidetector CT (MDCT) (Sensation 64, Siemens) scanner was used for imaging, with standard angiography characteristics. Three scans were performed: first, coronary angiography at first pass with 1.25 gI/kg of contrast material (ART); and remaining delayed-enhancement (DE1–DE2) 15 min after administration of 1.25 (DE1) and 15 min after additional administration of 2.50 gI/kg (=total 3.75 gI/kg — DE2). Mean heart rate decreased to 51±9 bpm after intravenous administration of Zatebradine (10 mg/kg). Data sets were reconstructed during the end-diastolic phase of the cardiac cycle. Areas of infarction-enhanced (DE), no-reflow (no-reflow) and remote myocardial [remote left ventricle (LV)] were manually contoured. CT attenuation values (Hounsfield units) were measured using five regions of interest: DE, no-reflow, remote LV, left ventricular cavity (lumen LV) and in air. Differences, correlations, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.ResultsWe found significant differences between the attenuation of DE, no-reflow and remote LV (p<0.001). DE and no-reflow size were assessed accurately with DEMDCT. In particular, SNR and CNR showed higher values in DE2 (∼6.0 and 3.5, respectively; r2=0.90) vs. DE1 (∼4.0 and 2.2, respectively; r2=0.85).ConclusionsThe increase of contrast material volume determines a significant improvement in myocardial infarction image quality with DE-MDCT.RiassuntoObiettivoObiettivo di questo lavoro è stato valutare l’impatto del volume di agente di contrasto nella tecnica delayed-enhancement (DE) con apparecchiatura per la tomografia computerizzata (TC) a 64 strati (MSTC), per la valutazione quantitativa dell’infarto miocardico acuto riperfuso.Materiali e metodiIn 5 maiali domestici, il ramo circonflesso dell’arteria coronarica sinistra è stato occluso mediante pallone e sottoposta a riperfusione a distanza di 2 h. Dopo 5 giorni, sono state eseguite le scansioni MSTC mediante tecnica standard con mezzo di contrasto (MdC). La prima (ART), al primo passaggio di 1,25 gI/kg di agente di contrasto iodato; le rimanenti (DE1 e DE2), con tecnica Delayed-Enhancement: DE1 eseguita 15 min dopo somministrazione di 1.25gI/kg; DE2 eseguita 15 min dopo somministrazione aggiuntiva di 2,50 gI/kg (MdC totale=3,75 gI/kg). La frequenza cardiaca media è stata ridotta a 51±9 battiti per minuto (bpm) mediante somministrazione di zatebradina EV (10 mg/kg). I data-set sono stati ricostruiti durante la fase tele-diastolica del ciclo cardiaco. Sono state definite manualmente l’area di miocardio necrotico vascolarizzato (DE), devascolarizzato (no-reflow) e di miocardio sano (ventricolo sinistro [LV] remoto). I valori di attenuazione TC sono stati misurati in cinque regioni d’interesse posizionate nelle zone di DE, no-reflow, LV remoto, cavità ventricolare sinistra (LV lume) e in aria. In seguito sono state valutate le differenze, le correlazioni, i rapporti segnale/rumore (S/R) e contrasto (C/R).RisultatiSignificative differenze sono state riscontrate tra i valori di attenuazione TC dell’area DE, no-reflow e LV remoto (p<0,001). Le scansioni DE-MSTC permettono una miglior visualizzazione e caratterizzazione dell’area DE e no-reflow. In particolare, i valori di S/N e C/N risultano essere maggiori in DE2 (∼6,0 e 3,5, rispettivamente; r2=0,90) vs DE1 (∼4,0 e 2,2, rispettivamente; r2=0,85).ConclusioniL’aumento del volume di agente di contrasto determina una migliore qualità delle immagini dell’infarto miocardico con DE-MSTC.