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Koen Nieman

Publications and source records attributed to Koen Nieman.

At least 19 recordsLinked to original sources
PubMed2025

Cardiac CT fractal analysis of LV noncompaction and common cardiomyopathies.

BACKGROUND: Left ventricular noncompaction (LVNC), or hypertrabeculation, is a myocardial condition that remains challenging to diagnose and differentiate from other cardiomyopathies. This study evaluated the ability of cardiac CT to differentiate between LVNC, hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and controls using fractal analysis of LV trabeculae. METHODS: Subjects with LVNC, HCM, DCM, as well as controls, who underwent coronary CT angiography were included. LV trabecular structure was quantified using fractal analysis on a stack of 15 short-axis CT images. For each subject, maximum (FDmax) and average (FDglobal) fractal dimensions were reported. A subset of subjects also had clinically acquired cardiac MRI (CMR) exams for comparison. One-way ANOVA, Pearson correlation, and Bland-Altman analysis were used for statistical analysis. RESULTS: The study included 313 subjects (median age: 58.8 [48.1-68.0] years, 153 male) categorized into Control (89), LVNC (46), HCM (106), and DCM (72) cohorts. FDmax was significantly higher in LVNC (1.379 &#x200b;&#xb1; &#x200b;0.047) than in Control (1.305 &#x200b;&#xb1; &#x200b;0.033), HCM (1.321 &#x200b;&#xb1; &#x200b;0.040), and DCM (1.344 &#x200b;&#xb1; &#x200b;0.054) cohorts; all p &#x200b;< &#x200b;0.001. Similarly, FDglobal was significantly higher in LVNC (1.279 &#x200b;&#xb1; &#x200b;0.041) than in the other cohorts; all p &#x200b;< &#x200b;0.05. In a subset of 132 subjects with both CT and CMR exams, fractal dimensions from the two modalities were strongly correlated (r &#x200b;= &#x200b;0.63, p &#x200b;< &#x200b;0.0001), with CT-derived values being higher (1.337 &#x200b;&#xb1; &#x200b;0.049 vs. 1.262 &#x200b;&#xb1; &#x200b;0.045, p &#x200b;< &#x200b;0.0001). CONCLUSIONS: CT-derived fractal dimensions of LV trabecular structure were significantly higher in LVNC compared to control subjects, HCM, and DCM. CT-derived fractal dimensions strongly correlated with, but were higher than, those from cardiac MRI in the same subjects.

Humans↗
PubMed2006

Comparison of sixty-four-slice multidetector computed tomographic coronary angiography to coronary angiography with intravascular ultrasound for the detection of transplant vasculopathy.

Coronary allograft vasculopathy (CAV) is the most important limitation to long-term survival in adult heart transplant recipients and is difficult to detect without intravascular ultrasound (IVUS). We systematically evaluated the image quality of 64-slice multidetector computed tomographic (MDCT) coronary angiography in heart transplant recipients and tested the hypothesis that this modality is comparable to invasive coronary angiography with IVUS for the detection of CAV. Heart transplant recipients (n = 20) underwent invasive coronary angiography with IVUS and MDCT coronary angiography with a 64-slice scanner. Images were systematically analyzed for image quality and the presence of CAV. In addition, multidetector computed tomography and quantitative coronary angiography were used to measure lumen diameters at prespecified locations. Image quality analysis showed that, despite high mean heart rates (77 +/- 7 beats/min) and body mass index (29.5 +/- 5.3 kg/m(2)), 83% of coronary segments were graded as of excellent or good image quality. On average, 95 +/- 9% of the overall visualized length of the coronary arteries was imaged without motion artifacts, and the mean contrast-to-noise ratio was 11.3 +/- 4.6. Compared with IVUS, multidetector computed tomography had a sensitivity of 70%, specificity of 92%, positive predictive value of 89%, and negative predictive value of 77% for the detection of CAV. MDCT vessel diameter measurements correlated well with those obtained from quantitative coronary angiography (R(2) = 0.89). In conclusion, 64-slice multidetector computed tomography provides good to excellent image quality in heart transplant recipients and has moderate to excellent test characteristics for the detection of CAV. Further, MDCT measurements of lumen diameters correlated well with quantitative coronary angiography.

Body Mass Index↗
PubMed2006

Use of 64-slice CT in symptomatic patients after coronary bypass surgery: evaluation of grafts and coronary arteries.

AIMS: Although previous generations of multislice computed tomography (CT) have demonstrated accurate detection of obstructive bypass graft disease, progression of coronary disease is a more frequent cause for ischaemic symptoms late after bypass graft surgery. We explored the diagnostic performance of 64-slice CT in symptomatic patients after bypass surgery, for the assessment of both grafts and native coronary arteries. METHODS AND RESULTS: The 64-slice CT angiography (Siemens Sensation 64, Germany) was performed in 52 symptomatic patients, 10 +/- 5 years after bypass surgery. Two independent, blinded observers assessed all grafts and coronary arteries for stenosis, using conventional quantitative angiography as a reference. A total of 109 grafts (182 graft segments), 123 distal coronary run-offs, and 116 non-bypassed coronary branches (288 segments) were analysed. Per-segment detection of graft disease yielded a sensitivity of 99% (71/72) and specificity of 96% (106/110). Sensitivity and specificity to detect run-off disease were 89% (8/9) and 93% (106/114), positive predictive value was 50% (8/16). In non-grafted coronary segments, CT detected significant stenosis with a sensitivity and specificity of 97% (62/64) and 86% (192/224). Overestimation occurred more frequently in calcified segments (P = 0.002). CONCLUSION: The 64-slice CT allows angiographic evaluation of grafts and coronary arteries, although overestimation of coronary obstruction occurs, particularly in the presence of calcified disease.

Aged↗
PubMed2006

Differentiation of recent and chronic myocardial infarction by cardiac computed tomography.

Clinical use of cardiac computed tomography is rapidly expanding, and its purpose may reach beyond noninvasive coronary angiography. We investigated the ability of 64-slice multidetector computed tomography to differentiate between recent and long-standing myocardial infarction (MI). Contrast-enhanced coronary computed tomographic (CT) scans (Siemens Sensation 64) of patients with a recent MI (< 7 days, n = 16), long-standing MI (> 12 months, n = 13), and no MI (n = 13) were retrospectively evaluated. To anticipate transmural variation of myocardial perfusion and to neutralize image noise, a series of thin, overlapping slices was created in parallel alignment to the myocardial wall. Within each of these slices, a small region of interest was placed at a constant in-plane position to measure the CT attenuation (Hounsfield units [HU]) at consecutive transmural locations of injured and normal remote myocardium. In addition, wall thickness and the myocardial cavity were measured. Significantly lower CT attenuation values were found in patients with long-standing MI (-13 +/- 37 HU) than in those with acute MI (26 +/- 26 HU) and normal controls (73 +/- 14 HU, p < 0.001). The attenuation difference between infarcted and remote myocardia was larger in patients with long-standing MI than in patients with recent MI (89 +/- 41 and 55 +/- 33 HU, respectively, p < 0.001). In addition, long-standing MI was associated with wall thinning (p < 0.01), and ventricular dilation (p < 0.05), whereas recent MI was not (p > 0.05). In conclusion, recent and long-standing MIs may be differentiated by computed tomography based on myocardial CT attenuation values and ventricular dimensions.

Coronary Angiography↗
PubMed2006

Noninvasive assessment of plaque morphology and composition in culprit and stable lesions in acute coronary syndrome and stable lesions in stable angina by multidetector computed tomography.

OBJECTIVES: The purpose of this study was to assess morphology and composition of culprit and stable coronary lesions by multidetector computed tomography (MDCT). BACKGROUND: Noninvasive identification of culprit lesions has the potential to improve noninvasive risk stratification in patients with acute chest pain. METHODS: Thirty-seven patients with acute coronary syndrome (ACS) or stable angina underwent coronary 16-slice MDCT and invasive selective angiography. In all significant coronary lesions two observers measured the degree of stenosis, plaque area at stenosis, and remodeling index and assessed plaque composition. Differences between culprit lesions in patients with ACS and stable lesions in patients with ACS or stable angina were determined. RESULTS: We analyzed 40 lesions with excellent image quality in 14 patients with ACS and 9 patients with stable angina. Culprit lesions in patients with ACS (n = 14) had significantly greater plaque area and a higher remodeling index than both stable lesions in patients with ACS (n = 13) and in patients with stable angina (n = 13) (17.5 +/- 5.9 mm2 vs. 9.1 +/- 4.8 mm2 vs. 13.5 +/- 10.7 mm2, p = 0.02; and 1.4 +/- 0.3 vs. 1.0 +/- 0.4 vs. 1.2 +/- 0.3, p = 0.04, respectively). The prevalence of non-calcified plaque was 100%, 62%, and 77%, respectively, and the prevalence of calcified plaque was 71%, 92%, and 85%, respectively, in culprit lesions in patients with ACS and in stable lesions in patients with ACS or stable angina. CONCLUSIONS: We introduce the concept of noninvasive detection and characterization of coronary atherosclerotic lesions in patients with ACS by MDCT. We identified differences in lesion morphology and plaque composition between culprit lesions in ACS and stable lesions in ACS or stable angina, consistent with previous intravascular ultrasound studies.

Acute Disease↗
PubMed2006

Accuracy of 16-slice multi-detector CT to quantify the degree of coronary artery stenosis: assessment of cross-sectional and longitudinal vessel reconstructions.

BACKGROUND: Sixteen-slice multi-detector computed tomography (MDCT) permits reliable noninvasive detection of significant coronary stenosis based on qualitative visual assessment. The purpose of this study was to determine the accuracy of MDCT to quantify the degree of coronary stenosis as compared to quantitative coronary angiography (QCA) using two different reconstruction methods. METHODS: We studied 69 coronary artery lesions from 38 consecutive patients that underwent 16-slice MDCT as a part of research study, which enrolled consecutive subjects scheduled for clinically indicated invasive coronary angiography. Nine coronary artery lesions with motion artifacts, heavily calcified plaques or stents were excluded from the analysis. The degree of stenosis was calculated by two independent readers non-blinded to the location of the stenosis, but blinded to the results of the QCA. MDCT luminal diameters were measured in cross-sectional multi-planar reformatted (CS-MPR) images created perpendicular to the centerline of the vessel and in 5 mm thin-slab maximum intensity projections (MIP) parallel to the long axis of the vessel. Both MDCT methods were compared against QCA. RESULTS: The mean degree of stenosis as measured by MDCT was closely correlated to QCA for both methods (CS-MPR versus QCA: 61 +/- 23% versus 64 +/- 29%; r2 = 0.83, p < 0.001 and MIP versus QCA: 64 +/- 22% versus 64 +/- 29%; r2 = 0.84, p < 0.001 for MIP. Bland-Altman analysis demonstrated a negative bias of the degree of stenosis of -2.8 +/- 12% using CS-MPR and a minimally positive bias of 0.6 +/- 12% for MIP. In stratified analysis for lesion severity (mild, 0-40%; moderate, 41-70% or severe, > 70%) the agreement between both CS-MPR and MIP was high when compared to QCA (kappa = 0.74 and 0.71, respectively). CONCLUSION: Multi-detector spiral CT permits accurate quantitative assessment of the degree of coronary stenosis in selected data sets of sufficient quality using both cross-sectional and longitudinal vessel reconstructions.

Aged↗
PubMed2006

Quantitative parameters of image quality in 64-slice computed tomography angiography of the coronary arteries.

We explored quantitative parameters of image quality in consecutive patients undergoing 64-slice multi-detector computed tomography (MDCT) coronary angiography for clinical reasons. Forty-two patients (36 men, mean age 61 +/- 11 years, mean heart rate 63 +/- 10 bpm) underwent contrast-enhanced MDCT coronary angiography with a 64-slice scanner (Siemens Sensation 64, 64 mm x 0.6 mm collimation, 330 ms tube rotation, 850 mAs, 120 kV). Two independent observers measured the overall visualized vessel length and the length of the coronary arteries visualized without motion artifacts in curved multiplanar reformatted images. Contrast-to-noise ratio was measured in the proximal and distal segments of the coronary arteries. The mean length of visualized coronary arteries was: left main 12 +/- 6 mm, left anterior descending 149 +/- 25 mm, left circumflex 89 +/- 30 mm, and right coronary artery 161 +/- 38 mm. On average, 97 +/- 5% of the total visualized vessel length was depicted without motion artifacts (left main 100 +/- 0%, left anterior descending 97 +/- 6%, left circumflex 98 +/- 5%, and right coronary artery 95 +/- 6%). In 27 patients with a heart rate < or = 65 bpm, 98 +/- 4% of the overall visualized vessel length was imaged without motion artifacts, whereas 96+/-6% of the overall visualized vessel length was imaged without motion artifacts in 15 patients with a heart rate > 65 bpm (p < 0.001). The mean contrast-to-noise ratio in all measured coronary arteries was 14.6 +/- 4.7 (proximal coronary segments: range 15.1 +/- 4.4 to 16.1 +/- 5.0, distal coronary segments: range 11.4 +/- 4.2 to 15.9 +/- 4.9). In conclusion, 64-slice MDCT permits reliable visualization of the coronary arteries with minimal motion artifacts and high CNR in consecutive patients referred for non-invasive MDCT coronary angiography. Low heart rate is an important prerequisite for excellent image quality.

Adult↗
PubMed2006

Mapping epicardial fat with multi-detector computed tomography to facilitate percutaneous transepicardial arrhythmia ablation.

A sizable portion of ventricular tachycardia circuits are epicardial, especially in patients with non-ischemic cardiomyopathy, e.g. Chagas disease. Thus there is a growing interest among the electrophysiologists in transepicardial mapping and myocardial ablation for treatment of arrhythmias. However, increased epicardial fat can be a significant hindrance in procedural success as it can mimic infarct during mapping and can also decrease the effectiveness of ablation. Quantitative knowledge of epicardial fat pre-procedure can potentially significantly facilitate the conduct and outcomes of these procedures. In this study we assessed the epicardial fat distribution and thickness in vivo in 59 patients who underwent multi-detector computed tomography (MDCT) for coronary artery assessment using a 16-slice scanner. Multiplanar reconstructions were obtained in the ventricular short axis at the basal, mid ventricular, and near the apex level, and in a four-chamber view. In the short axis slices, we measured epicardial fat diameter in nine segments, and in the four-chamber view, it was measured in five segments. In grooved segments the maximum fat thickness was recorded, while in non-grooved segments thickness at three equally spaced points were averaged. The results were as follows starting clockwise: superior inter-ventricular (IV) groove (all measurements are in mm, in basal, mid ventricular, and apical levels, respectively) (11.2, 8.6, 7.3), left ventricular (LV) superior lateral wall (1.0, 1.5, 1.7), LV inferior lateral wall (1.3, 2.2, 3.5), inferior IV groove (9.2, 6.5, 6.1), right ventricular (RV) diaphragmatic wall (1.4, 0.2, 1.0), acute margin (9.2, 7.3, 7.8), RV anterior free wall inferior (6.8, 4.0, 4.7), RV anterior free wall superior (6.5, 3.2, 3.1), RV superior wall (5.6, 2.7, 4.0), We measured the following four-chamber segments: LV apex (2.8 mm), left atrio-ventricular (AV) groove (12.7), right AV groove (14.8), RV apex (4.8), and anterior IV groove (7.7). The mean epicardial fat thickness for all cases was 5.3 mm (S.D. 1.6). The mean total epicardial fat for patients over 65 was 22% greater than younger patients, with a 36% increase along the RV anterior free wall, 57% along the RV diaphragmatic wall and 38% along the LV lateral wall. Women averaged 17% more total epicardial fat. In conclusion, this study was designed to provide an epicardial fat map for physicians performing percutaneous epicardial mapping and interventions. While the acute margin and RV anterior free wall tend to have high epicardial fat, and the LV lateral wall and RV diaphragmatic wall tend to have little to no fat, there is significant variation between patients. MDCT is a reliable modality for visualizing epicardial fat, and should be considered prior to undergoing procedures that are affected by epicardial fat content, especially in elderly and female populations.

Adipose Tissue↗
PubMed2005

Comparison of the degree of coronary stenoses by multidetector computed tomography versus by quantitative coronary angiography.

Sixteen-slice multidetector computed tomography (MDCT) and quantitative coronary angiography (QCA) were performed in 29 patients. Quantification of the degree of luminal narrowing and lesion length measurements were performed independently on MDCT and QCA at 42 sites with sufficient computed tomographic image quality. The correlation between MDCT and QCA for quantifying the degree of stenosis was excellent (r2 = 0.93), although a systematic overestimation was observed by MDCT (bias 4% +/- 8%). The correlation between MDCT and QCA was moderate with respect to lesion length (r2 = 0.54). In the absence of severe calcifications or motion artifacts, MDCT permits noninvasive quantification of coronary stenosis.

Aged↗
PubMed2005

Noninvasive assessment of coronary plaque burden using multislice computed tomography.

We performed coronary plaque imaging with 16-row multislice computed tomography in 85 patients who had stable angina pectoris and a high pretest likelihood of having coronary plaque to evaluate plaque burden, i.e., extent (number of diseased coronary segments) and size (small vs large) of plaque. We also assessed type of plaque (calcified, noncalcified, or mixed) and its anatomic distribution. Of 85 patients included, 78 (92%) had fully evaluable multislice computed tomograms that allowed assessment of coronary plaque burden, including major and side branches (>or=2 mm), yielding a total of 855 segments. These 78 patients (92% men; mean age +/- SD 58 +/- 11.5 years) were in sinus rhythm, with heart rates of <70 beats/min (spontaneous or induced by beta blocker). Plaque was detected in 57% of all segments (487 of 855). The mean number of segments with plaque per patient +/- SD was 6.2 +/- 3.9. Plaque was classified as large in 33% of segments and small in 67%. Overall, 65% of plaques were calcified, 24% were noncalcified, and 11% were mixed. Plaques were predominantly located in the proximal and middle segments of the main coronary vessels.

Coronary Angiography↗
PubMed2005

Noninvasive evaluation of cardiac veins with 16-MDCT angiography.

OBJECTIVE: Anatomic mapping of the cardiac veins is important to guide transvenous therapeutic procedures such as biventricular pacing. As an alternative to invasive venography, we studied the feasibility of MDCT of the cardiac venous anatomy. CONCLUSION: Cardiac venous anatomy is variable. MDCT is a noninvasive method that allows detailed imaging of the cardiac venous anatomy, including small cardiac veins and thebesian valves. Therefore, cardiac MDCT may be a valuable tool for guiding procedures that involve the cardiac venous system.

Coronary Angiography↗
PubMed2005

Computed tomographic coronary angiography: an alternative to invasive coronary angiography.

Over the past decade, enormous progress has been made in the technology of computed tomography (CT) imaging. Substantial improvements in spatial resolution, temporal resolution, hardware and software now permit imaging of the entire coronary artery tree within a single breath-hold. Several studies have demonstrated a high sensitivity and specificity for the detection of significant coronary artery stenoses. In addition to imaging of the native coronary arteries, CT angiography may also be used to assess arterial and venous bypass grafts, and to detect the presence and composition of atherosclerotic plaque. Because CT angiography images are acquired with electrocardiogram gating, the data sets permit the assessment of left ventricular function (ejection fraction and regional wall motion), left ventricular volumes and, potentially, myocardial perfusion at no extra cost. The practical advantages of CT angiography (in regard to safety and cost) along with its future anticipated advancements make it an attractive alternative to diagnostic coronary angiography.

Coronary Angiography↗
PubMed2004

Intravenous contrast material administration at 16-detector row helical CT coronary angiography: test bolus versus bolus-tracking technique.

PURPOSE: To compare test bolus and bolus-tracking techniques for intravenous contrast material administration at 16-detector row computed tomographic (CT) coronary angiography. MATERIALS AND METHODS: This study had institutional review board approval, and patients gave informed consent. Thirty-eight patients (mean age, 60 years; three women) were randomized into two groups according to bolus timing technique: group 1 (20-mL test bolus with 100-mL main bolus) and group 2 (bolus tracking with 100-mL main bolus). All patients underwent electrocardiography-gated 16-detector row CT coronary angiography with 12 detectors (collimation, 0.75 mm; rotation time, 420 msec). In group 1, test bolus peak attenuation was used as a delay, while in group 2, a +100-HU threshold in ascending aorta triggered angiographic acquisition, with an additional 4-second delay for patient instruction. Attenuation was measured in the longitudinal direction throughout the examination in three main vessels: ascending aorta (region of interest [ROI] 1), descending aorta (ROI 2), and main pulmonary artery (ROI 3). Mean attenuation and slope of bolus geometry curve were calculated in each patient and ROI. Attenuation at origin of coronary arteries was measured. Student t test was used to compare results. RESULTS: Mean scan delay was 6 seconds longer in group 2 (P < .05). Average attenuation values were 306.6 HU +/- 44.0 (standard deviation) and 328.2 HU +/- 58.6 (P > .05) in ROI 1, 291.6 HU +/- 45.1 and 326.4 HU +/- 62.6 (P > .05) in ROI 2, and 354.7 HU +/- 78.0 and 305.3 HU +/- 71.4 (P < .05) in ROI 3 for groups 1 and 2, respectively. Average slope values were 5.8 and -0.8 (P < .05) in ROI 1, 7.7 and 0.7 (P < .05) in ROI 2, and -1.0 and -13.3 (P < .05) in ROI 3 for groups 1 and 2, respectively. Average attenuation values in left main, left anterior descending, and left circumflex arteries were higher in group 2 (P < .05); there were no differences (P > .05) between groups in right coronary artery. CONCLUSION: Bolus-tracking yields more homogeneous enhancement than does the test bolus technique.

Adult↗
PubMed2004

Multislice spiral computed tomography coronary angiography in patients with stable angina pectoris.

OBJECTIVES: This study was designed to prospectively evaluate the diagnostic performance of multislice spiral computed tomography (MSCT) coronary angiography for the detection of significant lesions in all segments of the coronary tree potentially suitable for revascularization. BACKGROUND: Noninvasive MSCT coronary angiography is a promising coronary imaging technique. METHODS: Sixteen-row MSCT coronary angiography was performed in 128 patients (89% men, mean age 58.9 +/- 11.7 years) in sinus rhythm with stable angina pectoris scheduled for conventional coronary angiography. Sixty percent (77 of 128) of patients received pre-scan oral beta-blockers, resulting in a mean heart rate of 57.7 +/- 7.7 beats/min. The diagnostic performance of MSCT for detection of significant lesions (> or =50% diameter reduction) was compared with that of quantitative coronary angiography (QCA). RESULTS: The sensitivity of MSCT for detection of significant lesions was 92% (216 of 234, 95% confidence interval [CI]: 88 to 95). Specificity was 95% (1,092 of 1,150, 95% CI: 93 to 96), positive predictive value 79% (216 of 274, 95% CI: 73 to 88), and negative predictive value 98% (1,092 of 1,110, 95% CI: 97 to 99). Two > or =50% lesions were missed because of motion artifacts and two because of severe coronary calcifications. The rest (78%, 14 of 18) were detected but incorrectly classified as <50% obstructions. All patients with and 86% (18 of 21) of patients without significant lesions on QCA were correctly classified by MSCT. All patients with significant left main disease or total occlusions were correctly identified on MSCT. CONCLUSIONS: Sixteen-row MSCT coronary angiography permits reliable detection of significant obstructive coronary artery disease in patients with stable angina in sinus rhythm.

Aged↗