Multimedia articles. Images in cardiovascular medicine. Cervical origin of the subclavian artery: imaging of a rare but clinically relevant anomaly.
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Abnormalities, Multiple↗
Biomedical subjects
Axel Kuettner
Publications and source records attributed to Axel Kuettner.
Diagnostic accuracy of multidetector computed tomography coronary angiography in patients with angiographically proven coronary artery disease.
OBJECTIVES: The aim of the present study was to evaluate the diagnostic accuracy in detecting high-grade coronary stenoses in patients with known coronary artery disease (CAD) using multidetector computed tomography (MDCT). BACKGROUND: The MDCT systems with electrocardiographic (ECG)-gating permit visualization of the coronary arteries. However, severe calcifications and higher heart rates are known to degrade image quality and limit correct diagnosis. METHODS: Sixty-six patients with proven CAD as assessed by conventional coronary angiography (CCA) were studied by MDCT (mean time 24 months postangiography). Total calcium score and all coronary arteries, including distal segments and side branches, were assessed with respect to evaluability, presence of high-grade coronary artery stenoses (>70%), and correct diagnosis. Results were compared to CCA. RESULTS: A total of 105 lesions were detected by CCA. The MDCT correctly detected 39 lesions (sensitivity 37%, specificity 99%). The correct clinical diagnosis could be obtained in 24 patients (36%). Artifacts due to elevated heart rates or severe coronary artery calcification were the main cause of degraded image quality inhibiting correct diagnosis. In 21/66 patients (32%) all four major coronary vessel segments could be visualized. A threshold for maximum heart rate and a maximum calcification level were established (65 beats/min and an Agatston Score Equivalent of 335, respectively). A second analysis was made using these thresholds. Of all patients studied, 10/11 (91%) were correctly diagnosed when adhering to these thresholds. CONCLUSIONS: When using MDCT as a noninvasive diagnostic modality to assess advanced CAD, it appears to be mandatory to preselect patients in order to achieve reliable results.
Adult↗
Non-invasive evaluation of coronary artery bypass grafts using multi-slice computed tomography: initial clinical experience.
Recurrence of angina pectoris in patients with previous coronary artery bypass graft (CABG) surgery due to severe coronary artery disease (CAD) is a common problem. Non-invasive imaging of coronary artery bypass grafts by computed tomography was first described in the early 1980s. Meanwhile, multi-slice computed tomography (MSCT) is now available. This new technique allows detection of coronary lesions with good sensitivity and specificity due to continuous improvement and modification of this method. The aim of this study was to investigate whether stenosis or occlusion of CABG can be detected by MSCT. Ten consecutive male patients (mean age 61+/-9.1 years) with previous CABG surgery and 21 bypass grafts (14 venous grafts, seven arterial grafts) were included in this study. Conventional coronary angiography and MSCT angiography (MSCTA) were performed in all patients. MSCTA results were compared with coronary angiography in regard of visualization and lesion detection in CABG. The analysis of MSCTA was performed blinded to the angiographic results. It was found that 18 of 21 bypass grafts (86%) were analyzable by MSCTA: seven of 21 (33%) grafts showed a significant stenosis (>75%), while six of them were detected by MSCTA (sensitivity: 86%, positive predictive value: 0.75). Dissection of one arterial graft could not be evaluated by MSCTA. Twelve of 13 grafts without severe lesion showed no significant stenosis in MSCTA (negative predictive value: 0.86). All grafts without severe lesions by MSCT showed no significant lesion in X-ray angiography (specificity: 100%). MSCTA is a promising new method for the detection of lesions in coronary artery bypass grafts. However, these data based on a small number has to be reevaluated by larger studies.
Aged↗
Noninvasive evaluation of the prevalence of noncalcified atherosclerotic plaques by multi-slice detector computed tomography: results of a pilot study.
BACKGROUND: Multi-slice detector computed tomography (MDCT) not only allows for the determination of coronary calcifications, but also for the noninvasive visualization of noncalcified plaques. Thus, coronary artery disease (CAD) can be detected at a fairly early stage. Since data on the prevalence of potentially rupture prone noncalcified coronary lesions are still missing, it was aim of the present investigation to study this in patients with a distinct cardiovascular risk profile, but without known CAD. METHODS: 68 patients with clinical suspicion of CAD and multiple cardiovascular risk factors were included in this prospective study. Calcium scoring, as well as the detection of noncalcified plaques were performed using a Somatom VZ scanner (Siemens, Forchheim, Germany). RESULTS: Calcium scoring could be performed in all patients on native scans; 63/68 (96%) of contrast enhanced scans showed sufficient image quality to perform a screening for noncalcified plaques. The three scans without diagnostic image quality had been performed at heart rates of 95 +/- 18/min. Coronary calcifications were found in 36/65 (55%) patients (Agatston score: 247 +/- 358). Additional noncalcified plaques were detected in 16/36 (45%) of these patients; 29/65 (45%) patients had no coronary calcifications (Agatston score: 0), but noncalcified plaques could be detected in 3/29 (10%) of these patients. CONCLUSIONS: The prevalence of noncalcified plaques was 29% in the whole study group, and even in 10% of patients without coronary calcifications. Further prospective large scale studies are required to confirm these data, and to evaluate the clinical implication of this finding.
Calcinosis↗
Advances in cardiac imaging with 16-section CT systems.
RATIONALE AND OBJECTIVES: The authors present advances in electrocardiographically (ECG) gated cardiac spiral scanning with recently introduced 16-section computed tomographic (CT) equipment. MATERIALS AND METHODS: The authors discuss the technical principles of ECG-gated cardiac scanning. They give an overview on system properties and on the detector design. They describe ECG-gated scan- and image-reconstruction techniques and ECG-controlled dose modulation ("ECG pulsing") for a reduction of the patient dose. They discuss key parameters for image quality and present simulation and phantom studies and they give preliminary values for the patient dose. RESULTS: An extension of the adaptive cardiac volume reconstruction for ECG-gated spiral CT provides adequate image quality for up to 16 sections. With the smallest reconstructed section width (about 0.83 mm) and overlapping image reconstruction, cylindrical holes 0.6-0.7 mm in diameter can be resolved in a transverse resolution phantom independent of the heart rate. For coronary CT angiography, the influence of transverse resolution is most pronounced for coronary segments that are only slightly tilted relative to the scan plane. In this case, visualization of stents and plaques is considerably improved with 1.0-mm or smaller section width. For 0.42-second gantry rotation time, temporal resolution reaches its optimum (105 msec) at a heart rate of 81 beats per minute. Effective patient dose for the standard protocols recommended by the manufacturer ranges from 0.45 mSv (male) for ECG-triggered calcium scoring to 7.1 mSv (male) for high-resolution ECG-gated coronary CT angiography. With ECG pulsing, the dose is reduced by 30%-50% depending on the patient's heart rate. CONCLUSION: Clinical experience will be needed to evaluate fully the potential of 16-section technology for cardiac imaging.
Artifacts↗
Coronary vessel visualization using true 16-row multi-slice computed tomography technology.
BACKGROUND: Multi-slice computed tomography (MSCT) scanners with retrospective ECG-gating permit visualization of the coronary arteries. Limited spatial and temporal resolution as well as breathing artefacts due to the scan time can cause poor distal vessel segment and side branch visualization. The latest MSCT generation with true 16-detector slices (Sensation 16), Siemens, Forchheim, Germany) provides furthermore improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality we conducted the following study. METHODS AND MATERIAL: Sixty-two consecutive patients (33 male, 29 female, mean age 63+/-8 [47-79] years, heart rate after beta-blockade 63+/-7 [45-86] bpm) with suspicion of coronary artery disease (CAD) were examined by cardiac MSCT. Parameter settings were: 0.75 mm collimation, 2.8mm table feed/rotation, caudocranial scan direction, 80 cc contrast media biphasic injection protocol, gantry rotation time 375 ms, temporal resolution 188 ms). Thirteen coronary segments (sgts) were evaluated in each patient (total number: 806 sgts). Image quality of each segment was determined as: excellent--free of motion artefacts, good--mild motion artefacts, relevant artefacts--still diagnostic value, severe calcification and insufficient image quality--not visualized segment. RESULTS: 301/806 (37%) sgts showed excellent and 294/806 (36%) sgts good image quality. Relevant artefacts were seen in 107/806 (13%) sgts, calcifications in 41/806 (5%) sgts. 63/806 (8%) sgts could not be visualized (34 of them (54%) either segment 9 or 10). Diagnostic image quality was achieved in 702/806 (87%) sgts. CONCLUSIONS: Due to true 16-slice technology and faster gantry rotation time MSCT image quality could be improved and allows a visualization of the entire coronary tree. Larger, randomized, catheter-controlled studies have to be conducted to determine, whether this improved visualization also translates into better diagnostic accuracy.
Aged↗
Influence of heart rate on vessel visibility in noninvasive coronary angiography using new multislice computed tomography: experience in 94 patients.
OBJECTIVES: Initial reports indicate that coronary artery lesions might be visualized with high sensitivity and specificity by the use of recently introduced multislice computed tomography (MSCT). Current CT technology offers a temporal resolution of 250 ms. In case of heart rates (HRs) >65 beats/min (bpm), however, the reconstruction software switches from a single-phase algorithm (using data from one heart cycle only) to a biphase algorithm using image data of two consecutive heart cycles, improving temporal resolution to down to 125 ms. Thus, it was the aim of the present study to evaluate the influence of the patients' (pts) HR on image quality expressed by vessel segment visibility. METHODS AND RESULTS: MSCT scans (Somatom VZ) were performed in 94 pts. Ten coronary segments were analyzed in each patient with regard to image quality (RCA: segments [sgts] 1-4, LMS: sgt 5, LAD: sgts 5-8, LCX: sgts 11, 12). A total of 697 of 940 (74.1%) sgts were accurately visualizable (RCA: 244/376 [64.9%], LMS: 94/94 [100%], LAD: 232/283 (82.3%), LCX: 146/188 [77.7%]). Beta-blocker therapy had a significant influence on mean HR (65 pts on beta-blocker, HR 65.1+/-10.7 bpm vs. 29 pts, HR 71.6+/-12.2 bpm, P=.01). A significant inverse correlation between HR and segmental visibility was found (r=-.48, P<.0001), with best visibility in pts with lower HRs (n=14 pts with 10 analyzable sgts, HR 60+/-10.1 vs. n=8 pts with 4 analyzable sgts, HR 79.9+/-6.9, P<.0001). CONCLUSIONS: Our results indicate that vessel visibility is highly dependent on the pts HR. Best vessel visibility was found in pts with HR <65 bpm with single-phase image reconstruction. Thus, it appears to be advisable to evaluate, and if needed, to lower the pts HRs before undergoing MSCT coronary angiography in order to achieve best image quality.
Adult↗
Reliability of differentiating human coronary plaque morphology using contrast-enhanced multislice spiral computed tomography: a comparison with histology.
BACKGROUND: Initial clinical results indicate that multislice spiral computed tomography (MDCT) might be useful for the noninvasive characterization of human coronary plaque morphology by determining tissue density within the lesions. This seems to be of clinical relevance, because coronary artery disease might be detected at an early stage before calcifications occur and noncalcified plaques that may be more likely to rupture could also be visualized noninvasively. The aim of the present study was to evaluate the reliability of contrast-enhanced MDCT in differentiating human atherosclerotic coronary plaque morphology by comparing it with the histopathologic gold standard. METHODS AND RESULTS: Twelve human hearts were scanned postmortem using an MDCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) high-resolution computed tomography scanner to detect atherosclerotic coronary plaques. Density measurements were performed within detected plaque areas. The exact location of each plaque was marked at the surface of the heart to assure accurate histopathologic sectioning of these lesions. The plaques were classified according to a modified Stary classification. Seventeen plaques were identified by MDCT. Six plaques were histopathologically classified as lipid rich (Stary III/IV), 6 plaques as intermediate (Stary V), and 5 plaques as calcific (Stary VII). Lipid-rich plaques had a mean density on MDCT of 42 +/- 22 Hounsfield units (HU), intermediate plaques had a mean density of 70 +/- 21 HU, and calcific plaques had a mean density of 715 +/- 328 HU. ANOVA analysis revealed a significant difference in plaque density between the 3 groups (P < 0.0001). CONCLUSIONS: The comparison with histopathology confirms that tissue density as determined by contrast-enhanced MDCT might be used to differentiate atherosclerotic plaque morphology.
Analysis of Variance↗
Image quality and diagnostic accuracy of 16-slice multidetector spiral computed tomography for the detection of coronary artery disease in elderly patients.
OBJECTIVES: To determine the image quality and diagnostic accuracy of cardiac multislice spiral computed tomography (MSCT) in elderly patients (>65 years old) in comparison to younger patients, this retrospective analysis was performed. METHODS: The catheter-controlled MSCT results from patients older than 65 years of age were compared with the results of younger patients in a cohort of 117 patients with regard to sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and image quality. Fifty-three patients were older than 65 years of age (group 1: 31 men, age range: 72.2 +/- 4.1 years, number of risk factors: 2.6 +/- 1.3, Agatston score: 866 +/- 1090) and 64 were younger (group 2: 45 men, age range: 57.4 +/- 6.1 years, number of risk factors: 2.6 +/- 1.0, Agatston score: 765 +/- 1013). All patients were examined by MSCT (Sensation 16 Speed 4 D; Siemens, Forchheim, Germany, with a gantry rotation time of 375 milliseconds) and invasive coronary angiography. The MSCT results were compared blinded with the results of the coronary angiography with regard to the presence or absence of significant stenosis (>50%) in a 13-segment model. Image quality was assessed on a qualitative scale between 1 (very good) and 5 (insufficient image quality) for each segment. RESULTS: Sensitivity, specificity, PPV, and NPP were not different statistically in both groups (group 1: 0.80/0.96/0.89/0.93 and group 2: 0.89/0.98/0.93/0.97). Three patients (all <65 years old) had to be excluded from analysis because of technical problems. Image quality was significantly better in group 2. Gender, body mass index, number of risk factors, and mean heart rate were not significantly different in either group. CONCLUSIONS: Age has an impact on MSCT image quality but did not hamper diagnostic accuracy. Thus, MSCT is a noninvasive method to detect or rule out coronary artery disease independently of age. These retrospective data have to be confirmed in larger prospective trials.
Age Factors↗