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Koen Nieman

Publications and source records attributed to Koen Nieman.

At least 37 records · Page 2Linked to original sources
PubMed2003

Non-invasive 16-row multislice CT coronary angiography: usefulness of saline chaser.

The aim of this study was to investigate the usefulness of saline chaser in 16-row multislice CT (16-MSCT) coronary angiography. Forty-two patients were divided into two groups for contrast material (CM) administration: group 1 (140 ml at 4 ml/s) and group 2 (100 ml at 4 ml/s followed by 40 ml of saline chaser at 4 ml/s). All patients underwent retrospectively ECG-gated 16-MSCT coronary angiography. The attenuation at the origin coronary vessels was assessed. Three regions of interest (ROIs) were drawn throughout the data set: (a) ascending aorta (ROI 1); (b) descending aorta (ROI 2); and (c) pulmonary artery (ROI 3). The attenuation in the superior vena cava was recorded (ROI 4). The average attenuation and the slope were calculated in each ROI and differences were assessed with a Student's t test. The average attenuation in the coronary vessels was not significantly different in the two groups. The average attenuations in ROI 1 were 325 and 327 HU, in ROI 2 were 328 and 329 HU and in ROI 3 were 357 and 320 HU, for groups 1 and 2, respectively (p>0.05). The slopes in ROI 1 were -0.2 and 1.1, in ROI 2 were 2.8 and 2.1 (p>0.05) and in ROI 3 were 3.9 and -9.0 (p<0.05), for groups 1 and 2, respectively. The average attenuations in ROI 4 were 927 and 643 HU (p<0.05), for groups 1 and 2, respectively. One hundred milliliters of CM with 40 ml of saline chaser provides the same attenuation as 140 ml of CM (35% less) with decreased hyper-attenuation in the superior vena cava.

Adult↗
PubMed2003

Noninvasive angiographic evaluation of coronary stents with multi-slice spiral computed tomography.

BACKGROUND: The number of patients with obstructive coronary artery disease, who undergo coronary angioplasty with implantation of stents, is ever increasing. As an alternative to catheter-based angiography, ECG-gated multi-slice spiral computed tomography (MSCT) allows noninvasive imaging of the coronary arteries. However, coronary stents have been notoriously difficult to assess by CT. METHODS AND RESULTS: In vitro experiments were performed, using varying detector collimations, contrast concentrations, stent positions and stent diameters, to evaluate the feasibility and image characteristics of stents. The stent-related high-density artifacts expand the apparent size of the stent struts. This blooming effect is a fairly constant phenomenon, and therefore relatively less evident in larger-diameter stents. The in vivo images show the same artifacts, but assessment is further complicated by motion, lower contrast-to-noise, and vessel wall calcifications. CONCLUSIONS: The clinical value of CT after percutaneous coronary intervention currently remains largely limited to the detection of stent occlusion, and the progression of coronary artery disease in the remaining nonstented segments. Subtle in-stent abnormalities cannot be reliably imaged. Some relief will be offered by improvements in scanner technology, but the use of less radiopaque stent material would be more effective.

Angioplasty, Balloon, Coronary↗
PubMed2003

MS-CT coronary imaging.

Magnetic resonance imaging and computed tomography (CT) have recently emerged as two techniques that can noninvasively visualize the coronary arteries. The latest generation 16-row detector multislice CT scanner is now considered the most reliable technique to visualize the coronaries. The sensitivity and specificity to detect a significant (>50% diameter stenosis) coronary stenosis is +/-94% and +/-90%, respectively. Further technical improvements are necessary to make CT a clinically reliable diagnostic tool.

Cardiomyopathies↗
PubMed2003

Noninvasive visualization of atherosclerotic plaque with electron beam and multislice spiral computed tomography.

As an alternative to intracoronary modalities, electron beam computed tomography (EBCT) and multislice spiral computed tomography (MSCT) are able to noninvasively image the coronary arteries. In addition to stenosis detection by imaging the vessel lumen, MSCT has the ability to visualize the coronary artery wall. By using computed tomography (CT), the various components of atherosclerotic plaque may be distinguished and characterized, which holds the promise of, eventually, identifying vulnerable plaque.

Arteriosclerosis↗
PubMed2003

Evaluation of patients after coronary artery bypass surgery: CT angiographic assessment of grafts and coronary arteries.

PURPOSE: To evaluate the accuracy of electrocardiography (ECG)-gated multi-detector row computed tomography (CT) in enabling the detection of obstruction of both bypass grafts and coronary arteries in symptomatic patients who have undergone coronary artery bypass grafting. MATERIALS AND METHODS: ECG-gated contrast material-enhanced multi-detector row CT angiography was performed in 24 patients after bypass surgery. Two independent blinded observers evaluated all graft and coronary segments (> or =2.0-mm diameter) for occlusion and stenosis (50%-99% luminal reduction). Conventional angiography was regarded as the standard of reference. Descriptive parameters were calculated, and the results for arterial grafts, venous grafts, and coronary arteries, as well as for high and low heart rates, were compared by using a two-sided Fisher exact test. RESULTS: The following results were obtained by observers 1 and 2, respectively: Of the 60 venous graft segments, 60 (100%) and 57 (95.0%) were assessable, with an overall detection of all 17 occlusions (both observers) and three (50.0%) and five (83.3%) of six stenoses. Of 26 arterial graft segments, 19 (73.1%) and 15 (57.7%) were assessable. In the assessable segments, four of four (100%) and two of three (66.7%) stenoses and occlusions were detected, while one and two obstructions were located in nonassessable segments. Of 211 coronary segments, 146 (69.2%) and 140 (66.4%) were assessable, and detection of 50%-100% obstruction yielded a sensitivity of 89.9% (71 of 79) and 79.4% (54 of 68) and a specificity of 74.6% (50 of 67) and 72.2% (52 of 72) for each observer. Unlike the assessment of venous and arterial grafts, assessment of the coronary arteries with multi-detector row CT was significantly better in patients with low heart rates (P <.01). CONCLUSION: Multi-detector row CT allows noninvasive angiographic evaluation of both coronary arteries and bypass grafts in patients who have undergone bypass surgery. Multi-detector row CT is more effective in examining venous grafts compared with arterial grafts and diffusely diseased coronary arteries.

Adult↗
PubMed2003

Non-invasive demonstration of coronary artery anomaly performed using 16-slice multidetector spiral computed tomography.

Coronary artery anomalies are some of the most confusing, neglected topics in cardiology. Presently, no techniques are able to routinely screen those morphological alterations which can create potentially life-threatening complications, especially in young healthy subjects. Many efforts have been made to non-invasively image the coronary arteries using magnetic resonance, electron beam computed tomography, and recently multidetector computed tomography (MDCT). Even though interesting results have been reported, these techniques have hardly become an adequate substitute for conventional catheter coronary angiography. A new generation of MDCT scanners with 16 arrays of detectors and a higher temporal and spatial resolution have recently been introduced. We report a case of an anomalous coronary artery origin documented using a 16-slice MDCT scanner.

Coronary Angiography↗
PubMed2003

[Non-invasive 16-row spiral multislice computed tomography coronary angiography after one year of experience].

The gold standard for direct diagnostic imaging of coronary arteries is still conventional X-ray coronary angiography, even though for several other applications, noninvasive techniques substituted invasive ones. In the last 10 years several techniques (magnetic resonance, electron beam tomography, spiral computed tomography) attempted to emerge as noninvasive modality for the study of coronary arteries. The introduction of multislice computed tomography (MSCT) with retrospectively gated ECG reconstructions has substantially modified the coronary imaging scenario. In fact, the results have been promising since the beginning with 4-row MSCT. Currently the results reported with 16-row MSCT allow to question which role can the noninvasive coronary angiography play in clinical settings. With a scan of < 20 s after intravenous administration of iodinated contrast material it is possible to obtain information similar to conventional coronary angiography. Moreover, together with vascular patency, also atherosclerotic plaques are well visualized and characterized (type: calcified, soft, mixed). Ongoing studies are validating MSCT in the assessment of plaque vulnerability. The same technique allows to evaluate left ventricular function and myocardial wall motion impairment. Still with a few major limitations related to the heart rate, MSCT will broaden the noninvasive capability of evaluating coronary arteries in patients where conventional coronary angiography is exceeding the actual clinical question or considered as premature.

Algorithms↗
PubMed2003

Spiral CT-angiography with one, four, and sixteen slice scanners. Technical note.

Aim of this paper is to describe the technical main features that characterize Spiral Computed Tomography (CT) angiography. In particular, the technical features of the three main generations of single, four, and sixteen multislice scanners have been analised. Particular attention have been addressed to scan and reconstruction parameters, and to the geometry of contrast material related to angiographic scan. Guidelines for the different generations of CT scanner have been extracted to give the radiologist a platform for diagnostic questions.

Angiography↗
PubMed2002

Dosimetric comparison between high-precision external beam radiotherapy and endovascular brachytherapy for coronary artery in-stent restenosis.

PURPOSE: Several drawbacks of endovascular brachytherapy for the treatment of coronary artery in-stent restenosis may be addressed by high-precision external beam radiotherapy (EBRT). The dosimetric characteristics of both treatment techniques were compared. METHODS AND MATERIALS: The traversed volume of 10 coronary artery stents during the cardiac cycle was determined by electrocardiographically gated multislice spiral CT in 10 patients. By use of this traversed volume, high-precision EBRT treatment plans were generated for stents in the left circumflex (LCx), left anterior descending (LAD), and right coronary artery (RCA). The maximum dose to the nontargeted major coronary arteries was determined and compared to similar data calculated for endovascular brachytherapy. RESULTS: High-precision EBRT targeted at LCx stents contributed a mean maximum dose (D(max)) of 83.5% (range: 71.6-95.3%) and 16.3% to the LAD and RCA, respectively. Targeted LAD stents contributed a mean D(max) of 39.3% (range: 14.5-94.8%) and 5.2% (range: 0-13.4%) to the LCx and RCA, respectively. Targeted RCA stents contributed a mean D(max) of 6.2% (range: 0-12.4%) and 5.8% (range: 0-11.5%) to the LCx and LAD, respectively. Endovascular brachytherapy targeted at LCx stents contributed a mean D(max) of 1.7% (range: 0.7-2.7%) and 1.0% (range: 0.6-1.4%) to the LAD and RCA, respectively. Targeted LAD stents contributed a mean D(max) of 5.2% (range: 0.5-11.4%) and 0.7% (range: 0.4-1.1%) to the LCx and RCA, respectively; targeted RCA stents contributed a mean D(max) of 0.3% (range: 0.2-0.5%) and 0.2% (range: 0.1-0.3%) to the LCx and LAD, respectively. CONCLUSIONS: Although the doses distributed throughout the heart were higher for high-precision EBRT compared to endovascular brachytherapy, they are expected to be clinically irrelevant when nontargeted major coronary arteries are not closely situated to the targeted vessel segment. These encouraging results warrant further investigation of high-precision EBRT as a potential alternative to endovascular brachytherapy for the treatment of coronary artery in-stent restenosis.

Aged↗
PubMed2002

Reliable noninvasive coronary angiography with fast submillimeter multislice spiral computed tomography.

BACKGROUND: Multislice spiral computed tomography (MSCT) is a promising technique for noninvasive coronary angiography, although clinical application has remained limited because of frequently incomplete interpretability, caused by motion artifacts and calcifications. METHODS AND RESULTS: In 59 patients (53 male, aged 58+/-12 years) with suspected obstructive coronary artery disease, ECG-gated MSCT angiography was performed with a 16-slice MSCT scanner (0.42-s rotation time, 12x0.75-mm detector collimation). Thirty-four patients were given additional beta-blockers (average heart rate: 56+/-6 min(-1)). After contrast injection, all data were acquired during an approximately 20-s breath hold. The left main (LM), left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA), including > or =2.0-mm side branches, were independently evaluated by two blinded observers and screened for > or =50% stenoses. The consensus reading was compared with quantitative coronary angiography. MSCT was successful in 58 patients. Eighty-six of the 231 evaluated branches were significantly diseased. Without exclusion of branches, the sensitivity, specificity and positive and negative predictive value to identify > or =50% obstructed branches was 95% (82/86), 86% (125/145), 80% (82/102), and 97% (125/129), respectively. The overall accuracy for the LM, LAD, RCA, and LCX was 100%, 91%, 86%, and 81%, respectively. No obstructed LM, LAD, or RCA branches remained undetected. Classification of patients as having no, single, or multivessel disease was accurate in 78% (45/58) of patients and no patients with significant obstructions were incorrectly excluded. CONCLUSIONS: Improvements in MSCT technology, combined with heart rate control, allow reliable noninvasive detection of obstructive coronary artery disease.

Coronary Angiography↗
PubMed2002

Usefulness of multislice computed tomography for detecting obstructive coronary artery disease.

The latest generation of multislice spiral computed tomography (MSCT) scanners is capable of noninvasive coronary angiography. We evaluated its diagnostic accuracy to detect stenotic coronary artery disease (CAD). In 53 patients with suspected CAD, contrast-enhanced MSCT and conventional angiography were performed. The CT data were acquired within a single breathhold, and isocardiophasic slices were reconstructed by means of retrospective electrocardiographic gating. Coronary segments of > or = 2 mm in diameter, measured by quantitative angiography, were evaluated. In 70% of the 358 available segments, image quality was regarded as adequate for assessment. The overall sensitivity, specificity, and positive and negative predictive values to detect > or = 50% stenotic lesions in the assessable segments were 82% (42 of 51 lesions), 93% (285 of 307 nonstenotic segments), and 66% and 97%, respectively, regarding conventional quantitative angiography as the gold standard. Proximal segments were assessable in 92%, and distal segments and side branches in 71% and 50%, respectively. Including the undetected lesions in non-assessable segments, overall sensitivity decreased to 61% but remained 82% for lesions in proximal coronary segments. MSCT correctly predicted absent, single, or multiple lesions in 55% of patients. Thus, despite potentially high image quality, current MSCT protocols offer only reasonable diagnostic accuracy in an unselected patient group with a high prevalence of CAD.

Contrast Media↗