Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch.

OBJECTIVES: To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. METHODS: Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. RESULTS: Estimates for mean relative ED was 7.1 ± 2.1 mSv/100 mAs for TCM and 12.5 ± 5.3 mSv/100 mAs for CTC (P < 0.001). Relative dose reduction at low HR (≤60 bpm) was highest (49 ± 5%) compared to intermediate (60-70 bpm, 33 ± 12%) and high HR (>70 bpm, 29 ± 12%). However lowest ED is achieved at high HR (5.2 ± 1.5 mSv/100 mAs), compared with intermediate (6.7 ± 1.6 mSv/100 mAs) and low (8.3 ± 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. CONCLUSIONS: Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. KEY POINTS: • Monte Carlo simulations allow for individual radiation dose calculations. • ECG-triggered tube current modulation (TCM) can effectively reduce radiation dose. • Slow and regular heart rates allow for highest dose reductions by TCM. • Adaptive pitch accounts for lowest radiation dose at high heart rates. • Women receive higher effective dose than men undergoing spiral coronary CT-angiography.

Coronary computed tomography angiography with a consistent dose below 1 mSv using prospectively electrocardiogram-triggered high-pitch spiral acquisition.

AIMS: We evaluated the feasibility and image quality of a new scan mode for coronary computed tomography angiography (CTA) with an effective dose of less than 1 mSv. METHODS AND RESULTS: In 50 consecutive patients (body weight

Radiation exposure and image quality in staged low-dose protocols for coronary dual-source CT angiography: a randomized comparison.

OBJECTIVE: To evaluate staged low-dose approaches for coronary CT angiography (CTA) in which a standard sequence was added if the low-dose sequence did not allow reliable rule-out of coronary stenosis. PATIENTS AND METHODS: A total of 176 consecutive patients referred for dual-source CTA were randomized to three protocols: group 1 using prospective ECG-triggering (100 kV, 330 mAs), group 2 a retrospectively gated "MinDose" sequence (100 kV, 330 mAs) and group 3 a standard spiral sequence (120 kV, 400 mAs). If image quality in low-dose groups 1 or 2 was non-diagnostic, an additional standard CT examination (as in group 3) was performed. RESULTS: Non-diagnostic image quality was found in 11/56, 4/55, and 2/65 patients (46/896, 4/880 and 3/1,040 coronary segments) in groups 1, 2 and 3, respectively. Median (interquartile ranges) volumes of contrast material, CTDI(vol), DLP and effective dose for low-dose groups 1 and 2 and for standard group 3 were 92.5 (11.3), 75.0 (2.5) and 75.0 (9.0) ml; 8.0 (1.4), 16.8 (4.8) and 48.1 (14.2) mGy; 108.0 (27.3), 246.0 (93.0) and 701.0 (207.8) mGy cm; and 1.5 (0.4), 3.4 (1.3) and 9.8 (2.9) mSv, respectively. CONCLUSION: A staged coronary CTA protocol with an initial low-dose approach and addition of a standard sequence--should image quality be too low--can lead to a substantial reduction in radiation exposure.

Prospectively ECG-triggered high-pitch spiral acquisition for coronary CT angiography using dual source CT: technique and initial experience.

OBJECTIVE: We evaluated radiation exposure and image quality of a new coronary CT angiography protocol, high-pitch spiral acquisition, using dual source CT (DSCT). MATERIAL AND METHODS: Coronary CTAwas performed in 25 consecutive patients with a stable heart rate of 60 bpm or less after premedication, using 2 x 128 0.6-mm sections, 38.4-mm collimation width and 0.28-s rotation time. Tube settings were 100 kV/320 mAs and 120 kV/400 mAs for patients below and above 100-kg weight, respectively. Data acquisition was prospectively ECG-triggered at 60% of the R-R interval using a pitch of 3.2 (3.4 for the last 10 patients). Images were reconstructed with 75-ms temporal resolution, 0.6-mm slice thickness and 0.3-mm increment. Image quality was evaluated using a four-point scale (1 = excellent, 4 = unevaluable). RESULTS: Mean range of data acquisition was 113 +/- 22 mm, mean duration was 268 +/- 23 ms. Of 363 coronary artery segments, 327 had an image quality score of 1, and only 2 segments were rated as "unevaluable". Mean dose-length product (DLP) was 71 +/- 23 mGy cm, mean effective dose was 1.0 +/- 0.3 mSv (range 0.78-2.1 mSv). For 21 patients with a body weight below 100 kg, mean DLP was 63 +/- 5 mGy cm (0.88 +/- 0.07 mSv; range 0.78-0.97 mSv). CONCLUSION: Prospectively ECGtriggered high-pitch spiral CT acquisition provides high and stable image quality at very low radiation dose.

Late enhancement using multidetector row computer tomography: a feasibility study with low dose 80 kV protocol.

AIMS: Detecting stenoses of coronary arteries with multidetector row computer tomography (MDCT) is a well feasible non-invasive method. However, there is still the problem of deciding whether a stenosis is hemodynamically relevant or not. Objective of the present study was to validate the feasibility of a low dose protocol for MDCT using 80 kV for detecting late enhancement. METHODS AND RESULTS: Using a Alderson-Rando Phantom evaluation of the effective dose of this LE protocol was performed. Ten patients (six male, four female, mean age 61) with known coronary artery disease and scheduled for a conventional coronary angiogram in our facility were subsequently recruited. All patients underwent CT-angiography (CTA) 1 day prior to magnetic resonance imaging. Five minutes after the application of 100ml contrast agent for the CTA scan, a low dose late enhancement scan (80 kV, 400 mA s maximum, ECG pulsed scan, 64 mm x 0.6mm collimation, 0.33 s tube rotation) was performed. Phantom dose measurements showed an effective dose for this protocol of 1.19 mSv (male) and 1.61 mSv (female). Fifty-six percent (5/9) of the patients showed a late enhancement on the MRI scan. Three transmural late enhancements and all four negative findings were correctly identified by CT. This represents a sensitivity of 78% (3/5), specificity of 100% (3/3), NPV of 100% (4/4) and a PPV of 97%. CONCLUSION: We were able to show that the low dose protocol is feasible and, furthermore, preliminary results look promising.

Diagnostic Accuracy of an MRI Protocol of the Knee Accelerated Through Parallel Imaging in Correlation to Arthroscopy.

PURPOSE: Parallel imaging allows for a considerable shortening of examination times. Limited data is available about the diagnostic accuracy of an accelerated knee MRI protocol based on parallel imaging evaluating all knee joint compartments in a large patient population compared to arthroscopy. MATERIALS AND METHODS: 162 consecutive patients with a knee MRI (1.5 T, Siemens Aera) and arthroscopy were included. The total MRI scan time was less than 9 minutes. Meniscus and cartilage injuries, cruciate ligament lesions, loose joint bodies and medial patellar plicae were evaluated. Sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV), as well as diagnostic accuracy were determined. RESULTS: For the medial meniscus, the values were: SE 97 %, SP 88 %, PPV 94 %, and NPV 94 %. For the lateral meniscus the values were: SE 77 %, SP 99 %, PPV 98 %, and NPV 89 %. For cartilage injuries the values were: SE 72 %, SP 80 %, PPV 86 %, and NPV 61 %. For the anterior cruciate ligament the values were: SE 90 %, SP 94 %, PPV 77 %, and NPV 98 %, while all values were 100 % for the posterior cruciate ligament. For loose bodies the values were: SE 48 %, SP 96 %, PPV 62 %, and NPV 93 %, and for the medial patellar plicae the values were: SE 57 %, SP 88 %, PPV 18 %, and NPV 98 %. CONCLUSION: A knee MRI examination with parallel imaging and a scan time of less than 9 minutes delivers reliable results with high diagnostic accuracy. KEY POINTS: · An accelerated knee MRI protocol with parallel imaging allows for high diagnostic accuracy.. · Especially meniscal and cruciate ligament injuries are well depicted.. · Cartilage injuries seem to be overestimated.. CITATION FORMAT: · Schnaiter JW, Roemer F, McKenna-Kuettner A et al. Diagnostic Accuracy of an MRI Protocol of the Knee Accelerated Through Parallel Imaging in Correlation to Arthroscopy. Fortschr Röntgenstr 2018; 190: 265 - 272.

Diagnostic accuracy of noninvasive coronary angiography in patients after bypass surgery using 64-slice spiral computed tomography with 330-ms gantry rotation.

BACKGROUND: Multidetector computed tomographic angiography (MDCT) has been shown to allow detection of coronary artery bypass graft (CABG) occlusions and stenoses. However, the assessment of native coronary arteries in addition to CABG has thus far not been sufficiently validated. METHODS AND RESULTS: Fifty patients with a total of 138 CABG (34 mammary grafts, 3 radial grafts, 101 venous grafts) were investigated by MDCT (0.6-mm collimation, 32 detector rows, 2 focal points, 330-ms rotation) 9 to 252 months (mean, 106 months) after surgery. CABG and all native coronary arteries with a diameter of > 1.5 mm were evaluated for the presence of significant stenoses (> or = 50% diameter reduction). Results were compared with quantitative coronary angiography. By MDCT, all CABG were evaluable and were correctly classified as occluded (n=38) or patent (n=100). Sensitivity for stenosis detection in patent grafts was 100% (16/16) with a specificity of 94% (79/84). For the per-segment evaluation of native coronary arteries and distal runoff vessels, sensitivity in evaluable segments (91%) was 86% (87/101) with a specificity of 76% (354/465). If evaluation was restricted to nongrafted arteries and distal runoff vessels, sensitivity was 86% (38/44) with a specificity of 90% (302/334). On a per-patient basis, classifying patients with at least 1 detected stenosis in a CABG, a distal runoff vessel, or a nongrafted artery or with at least 1 unevaluable segment as "positive," MDCT yielded a sensitivity of 97% (35/36) and specificity of 86% (12/14). CONCLUSIONS: We found that 64-slice MDCT permits the evaluation of bypass grafts and the assessment of the native coronary arteries for the presence of stenosis.

Influence of a lipid-lowering therapy on calcified and noncalcified coronary plaques monitored by multislice detector computed tomography: results of the New Age II Pilot Study.

PURPOSE: Multislice detector computed tomography (MSCT) is an accurate noninvasive modality to detect and classify different stages of atherosclerosis. The aim of the New Age II Study was to detect coronary lesions in men without established coronary artery disease (CAD) but with a distinct cardiovascular risk profile. We also sought to assess the effect after 1 year of a lipid-lowering therapy (LLT) using 20 mg of atorvastatin. METHODS: Forty-sixe male patients (mean, 61 +/- 10 years) with an elevated risk for CAD (PROCAM score >3 quintile) without LLT were included. Native and contrast-enhanced scans were performed in all patients. A total of 27 of 46 patients received a follow-up scan (after 488 +/- 138 days). Coronary plaque burden (CPB) was assessed volumetrically. RESULTS: The prevalence of CAD was 83% (38/46 patients), and 11% (5/46) without coronary calcifications still had noncalcified plaques. Total cholesterol and low-density lipoprotein cholesterol levels decreased significantly under LLT (225 +/- 41 mg/dL vs. 162 +/- 37 mg/dL, P < 0.0001 and 148 +/- 7 mg/dL vs. 88 +/- 5 mg/dL, P < 0.001, respectively). On follow-up, calcium score and CPB remained unchanged (Agatston score: 261 +/- 301 vs. 282 +/- 360; CPB: 0.149 +/- 0.108 vs. 0.128 +/- 0.075 mL, P > 0.05), whereas mean plaque volume of noncalcified plaques decreased significantly from 0.042 +/- 0.029 mL versus 0.030 +/- 0.014 mL (P < 0.05, mean reduction 0.012 +/- 0.017 mL or 24 +/- 13%). CONCLUSIONS: Statin therapy led to a significant reduction of noncalcified plaque burden that was not reflected in calcium scoring or total plaque burden. This finding might explain the risk reduction after the initiation of statin therapy. Using multislice detector computed tomography, physicians have the potential to monitor medical treatment in patients with coronary atherosclerosis.

Diagnostic accuracy of multislice computed tomography for the detection of coronary artery disease in diabetic patients.

BACKGROUND: Diabetes mellitus is an important risk factor for coronary artery disease. Cardiac multislice computed tomography (MSCT) permits visualization of the coronary arteries with good sensitivity and specificity. However, at present, there are no data whether MSCT allows an accurate assessment of coronary arteries of diabetic patients, in comparison to nondiabetic patients. Thus, we compared the catheter-controlled MSCT results from diabetic and nondiabetic patients in a cohort of 116 patients with regard to sensitivity, specificity, positive predictive value, and negative predictive value, as well as image quality. METHODS AND MATERIALS: Twenty-two diabetic patients (age, 64.6+/-8.5 years; number of risk factors, 3.4+/-1.1) and 94 nondiabetic patients (age, 64.2+/-9.2 years; number of risk factors, 2.4+/-1.0) were examined by MSCT (Sensation 16 Speed 4 D, Siemens, Forchheim, Germany; gantry rotation time, 375 ms) and invasive coronary angiography. MSCT results were compared, blinded to the results of the coronary angiography with regard to the presence or absence of a significant stenosis (>50%) in a modified American Heart Association 13-segment model. Image quality was assessed on a qualitative scale between 1 (very good) and 5 (invisible) for each segment. RESULTS: Sensitivity, specificity, positive predictive value, and negative predictive value were statistically not different in diabetic and nondiabetic patients (0.85/0.98/0.92/0.96 vs. 0.84/0.97/0.91/0.95). One diabetic and three nondiabetic patients had to be excluded from analysis. Diabetic patients had relevantly more risk factors (P < .05), but calcium scoring was not different in both groups (Agatston score 1090+/-1278 vs. 798+/-1033). The image quality in both cohorts was comparable. CONCLUSIONS: MSCT allows the assessment of the coronary arteries noninvasively in diabetic patients with a good sensitivity and specificity, and diabetes does not have an impact on the number of evaluable segments. Thus, MSCT is a noninvasive tool in the care of these patients.

Diagnostic accuracy of noninvasive coronary imaging using 16-detector slice spiral computed tomography with 188 ms temporal resolution.

OBJECTIVES: The aim of our study was to evaluate the diagnostic accuracy of 16-multi-detector spiral computed tomography (MDCT) with 188 ms temporal resolution. BACKGROUND: Because of rapid technical innovations, MDCT coronary imaging has significantly improved in the last five years. Recent results indicate a high diagnostic accuracy, especially in patients with clinical suspicion of coronary artery disease (CAD). METHODS: A total of 72 consecutive patients (30 women, 42 men, age 64 +/- 10 years) scheduled for invasive coronary angiography (ICA) because of suspected CAD were additionally studied by MDCT (Sensation 16 Speed 4D, Siemens, Forchheim, Germany). Thirty-seven of 72 patients (51%) received an additional beta-blockade before MDCT because of heart rates >65 beats/min. The MDCT scans were analyzed regarding the presence of coronary artery lesions. Results were compared with ICA. RESULTS: All 72 scans showed diagnostic image quality (heart rate: 64.1 +/- 9.2 beats/min, calcium mass: 86 +/- 156 mg). Thirteen coronary segments were evaluated in each patient. Sixty-two of 936 (6.6%) segments showed a nondiagnostic image quality. All segments were included in the analysis. A total of 117 relevant lesions (diameter stenosis >50%) were detected using ICA, and 96 of 117 (82%) were detected by MDCT. Sensitivity, specificity, and positive and negative predictive values for the whole study group were as follows: 82%, 98%, 87%, and 97%, respectively. The correct clinical diagnosis of presence or absence of significant CAD was obtained in 65 of 72 (90%) patients. All stenoses were detected by MDCT in 52 of 72 (72%) patients. CONCLUSIONS: Our results indicate a high diagnostic accuracy of 16-slice MDCT with improved temporal resolution.

Non-invasive evaluation of coronary artery bypass grafts using 16-row multi-slice computed tomography with 188 ms temporal resolution.

BACKGROUND: Cardiac multi-slice computed tomography (MSCT) scanners permit visualization of the coronary arteries and coronary artery bypass grafts. The latest MSCT generation with true 16-detector slices (Sensation 16 Speed 4 D, Siemens, Forchheim, Germany) provides 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 and accuracy of MSCT diagnosis in patients with previous coronary artery bypass graft (CABG) surgery the following study was conducted. METHODS AND MATERIAL: Thirteen consecutive patients (pts) (10 male, 3 female, mean age 62 +/- 6.4 [55-73] years, heart rate 68 +/- 11 [52-88] bpm) and a total number of 43 coronary bypass grafts (11 arterial, 32 venous grafts) were examined by MSCT (gantry rotation time 375 ms). In addition to the analysis of coronary bypass grafts, 13 coronary segments (sgts) were evaluated in each patient (n = 169 sgts). MSCT results were compared with coronary angiography. RESULTS: Forty-one of 43 bypass grafts (95%) were analyzable by MSCT. In conventional angiography 16 of 43 (37%) grafts were occluded. Sixteen of them were correctly diagnosed by MSCT (sensitivity 100%). One graft showed a 50% anastomosis stenosis which was also detected. Twenty-five of 27 grafts without severe lesion showed no significant stenosis in MSCT (specificity 93%, positive predictive value (PPV) 89%, negative predictive value (NPV) 100%). Ninety of 108 (83%) high-grade stenosis (>70%) of the native coronary vessels were correctly detected (sensitivity 83%, PPV 78%). From the 61 sgts without high grade stenosis 36 were correctly classified (specificity 59%, NPV 67%). If sgts number 8, 9 and 10, which are normally not target for revascularization, are excluded sensitivity rises to 89%, specificity to 71%, PPV to 87% and NPV to 75%. The correct clinical diagnosis (absence or presence of a high grade stenosis of at least one bypass graft) was achieved in all patients. CONCLUSIONS: True 16-slice MSCT with faster gantry rotation time allows detection of lesions in coronary artery bypass grafts with high sensitivity and specificity. The evaluation of native vessels in pts with known CAD remains a diagnostic challenge. However, the correct clinical diagnosis was achieved in all pts. MSCT is a non-invasive tool to assess coronary artery bypass grafts.

Contrast-enhanced coronary artery visualization by dual-source computed tomography--initial experience.

UNLABELLED: Multi-detector computed tomography (CT) scanners, by virtue of their high temporal and spatial resolution, permit imaging of the coronary arteries. However, motion artifacts, especially in patients with higher heart rates, can impair image quality. We thus evaluated the performance of a new dual-source CT (DSCT) with a heart rate independent temporal resolution of 83 ms for the visualization of the coronary arteries in 14 consecutive patients. METHODS: Fourteen patients (mean age 61 years, mean heart rate 71 min(-1)) were studied by DSCT. The system combines two arrays of an X-ray tube plus detector (64 slices) mounted on a single gantry at an angle of 90 degrees With a rotation speed of 330 ms, a temporal resolution of 83 ms (one-quarter rotation) can be achieved independent of heart rate. For data acquisition, intraveous contrast agent was injected at a rate of 5 ml/s. Images were reconstructed with 0.75 slice thickness and 0.5 mm increment. The data sets were evaluated concerning visibility of the coronary arteries and occurrence of motion artifact. RESULTS: Visualization of the coronary arteries was successful in all patients. Most frequently, image reconstruction at 70% of the cardiac cycle provided for optimal image quality (50% of patients). Of a total of 226 coronary artery segments, 222 (98%) were visualized free of motion artifact. In summary, DSCT constitutes a promising new concept for cardiac CT. High and heart rate independent temporal resolution permits imaging of the coronary arteries without motion artifacts in a substantially increased number of patients as compared to earlier scanner generations. Larger and appropriately designed studies will need to determine the method's accuracy for detection of coronary artery stenoses.

Noninvasive detection of coronary lesions using 16-detector multislice spiral computed tomography technology: initial clinical results.

OBJECTIVES: The aim of our study was to evaluate the feasibility of detecting coronary artery lesions using a new computed tomography (CT) scanner with 16 detectors and faster gantry rotation. BACKGROUND: Computed tomography angiography of the coronaries permits assessment of the coronaries; however, image quality is still impaired by motion artifacts and calcifications. METHODS: Sixty patients scheduled for conventional coronary angiography (CCA) were additionally studied by multislice spiral computed tomography (MSCT). Calcium scores and a contrast-enhanced visualization of the coronaries were performed and analyzed regarding evaluability, presence of coronary artery lesions, and correct clinical diagnosis. RESULTS: Calcium scoring was successful in all patients; 58 of 60 patients had a diagnostic contrast-enhanced scan. Mean calcium score was 506 +/- 743 Agatston score equivalent (ASE); 13 of 58 (22%) patients had an ASE >or=1,000, 46 of 58 (78%) patients <1,000. In 763 coronary segments, CCA detected a total of 75 lesions >or=50%. The MSCT correctly assessed 54 of these. Twenty-one lesions were missed or incorrectly underestimated. Sensitivity was 72%, specificity 97%. When restricting analysis to patients with an ASE <1,000, 40 significant lesions >or=50% were seen on CCA, and MSCT correctly detected 39 lesions (sensitivity 98%, specificity 98%). Regardless of any threshold, the correct clinical diagnosis could be obtained in 58 of 60 (97%) of all patients. CONCLUSIONS: In individuals with low-to-moderate amounts of coronary artery calcium, 16-detector CT coronary angiography has high sensitivity and specificity for the diagnosis of significant coronary artery stenosis.

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.

Flat-panel detector computed tomography for the assessment of coronary artery stents: phantom study in comparison with 16-slice spiral computed tomography.

PURPOSE: The evaluation of coronary artery stents is a major limitation of cardiac multislice spiral computed tomography (MSCT). The development of flat-panel detector computed tomography (FPCT) with truly isotropic spatial resolution may overcome this limitation. Thus, we evaluated the use of FPCT in comparison to MSCT for the assessment of coronary artery stents. MATERIAL AND METHODS: Eight different coronary artery stents with a diameter of 3 mm each were placed in a static chest phantom. The phantom was positioned in the CT gantry at angles of 0 degrees , 45 degrees , and 90 degrees toward the z-axis and examined with the prototype of a FPCT (Siemens, Forchheim, Germany) and a commercially available 16-detector row MSCT (Sensation 16, Siemens). Slice thickness was 0.25 mm with FPCT whereas for MSCT, an effective slice thickness of 1 mm with a reconstruction increment of 0.5 mm was used. Image quality was assessed visually using a 5-point grading scale. Stent diameters were measured and compared using a repeated-measures analysis of variance. RESULTS: When compared with MSCT, artificial lumen reduction was significantly less using FPCT. On average the visible stent lumen was reduced by 16.1% with FPCT, whereas the mean of the lumen reduction was 47.2% with 16-detector row MSCT. Visible lumen diameter as well as image noise significantly increased using FPCT (P < 0.001). With FPCT delineation of the different stent struts became possible. CONCLUSION: FPCT proved to be superior when compared with 16-detector row MSCT for the in vitro assessment of coronary artery stents. Improved spatial resolution allows for a detailed assessment of the coronary artery stent lumen.

Technology insight: possible applications of multislice computed tomography in clinical cardiology.

With the introduction of four-slice scanners in 1999, multislice CT (MSCT) technology became available for investigative examination of the heart. Since then, MSCT technology has undergone rapid technical progress; temporal and spatial resolutions have been especially improved. The improved diagnostic image quality has led to more possible uses of MSCT being defined. At present, issues such as visualization of coronary artery bypass grafts, detection of stenoses of native coronary arteries, description of coronary anomalies, and calcium scoring, can be investigated reasonably well. Other features, such as plaque imaging and visualization of intracoronary stents, need further evaluation. A large number of factors, however, such as heart rate, atrial fibrillation, breathing artefacts and severe calcification, still influence image quality and reduce validity. In this article we provide a summary of current fields of application of cardiac MSCT. The word 'indication' is consciously avoided because official guidelines for the use of MSCT in heart examination have not yet been issued. Hopefully, prospective multicenter trials will be performed soon, providing more data with which to establish guidelines for both cardiologist and radiologist.

Influence of coenzyme Q(10) and cerivastatin on the flow-mediated vasodilation of the brachial artery: results of the ENDOTACT study.

AIM: Endothelial dysfunction (ED) is the functional prestep in atherosclerosis. Aim of the present study was to evaluate the effects of a potent antioxidant (coenzyme Q(10), CoQ(10)) and of cerivastatin on ED of the brachial artery. METHODS AND RESULTS: Twenty-five male patients with manifest ED (flow-mediated vasodilation [FMD%]<4.5%) were included in this prospective, randomized, cross-over study. ED of the brachial artery was assessed by the use of high-resolution ultrasound. Each patient had to pass through three treatment phases ((1) single therapy with cerivastatin (C), (2) single therapy with CoQ(10), (3) combination therapy). FMD% significantly improved throughout all treatment phases ((1) 3.50+/-4.05% vs. 8.80+/-6.39%, p=0.009; (2) -0.25+/-4.0% vs. 7.06%+/-4.39%, p=0.004; (3) 3.14+/-3.54% vs. 8.82+/-5.78%, p=0.011). C led to a significant decrease of CoQ(10) plasma levels (1.23+/-0.34 vs. 0.87+/-0.39 microg/ml, p=0.004). CONCLUSION: Our results indicate a positive influence of CoQ(10) supplementation on human ED, which appears to be independent of lipid lowering. Although large-scale studies evaluating other antioxidants failed to demonstrate a positive prognostic effect, Q(10) has never been evaluated in larger trials. Experimental as well as clinical results indicate that CoQ(10) warrants further attention in atherosclerosis research.

Visualization of pulmonary vein stenosis after radio frequency ablation using multi-slice computed tomography: initial clinical experience in 33 patients.

PURPOSE: Radio frequency ablation (RFA) of the pulmonary veins (PV) is an established technique for treatment of atrial fibrillation (AF). However, stenoses within the treated areas are well known complications. Thus, a reliable non-invasive diagnosis of PV stenosis would be an important step forward in the care of these patients (pts). Aim of the present study was the diagnostic accuracy of new multi-slice detected computed tomography (MSCT) in visualization of PV and in detecting PV stenosis. MATERIAL AND METHODS: A total of 33 pts (17 male, 16 female, mean age 57+/-10.2 years [40-71]) were included. Retrospectively ECG-gated CT angiography (CTA) was performed within 1 day to a maximum of 380 days after RFA with a MSCT scanner. Interpretation of the scan was performed on conventional contrast enhanced axial slices and on 3D volume rendering images (maximum intensity projection: MIP, multi-planar reconstruction: MPR). Lesion severity was determined on a semi-quantitative scale (mild: <20%, intermediate: 20-50%, severe >50%) and compared to conventional angiography which had been performed at the beginning and at the end of RFA. RESULTS: MSCTA was applied without any complications, and all treated pulmonary veins (n=73) could be visualized. Diagnostic image quality was obtained in all examinations. A significant stenosis was detected by conventional angiography in 26/73 (36%) PV (2/73 (3%) severe, 14/73 (19%) intermediate, 10/73 (14%) mild). Using MSCTA, only 13 stenosis in 73 treated PV could be visualized (1/73 (1%) severe, 6/73 (8%) intermediate, 6/73 (8%) mild). CONCLUSIONS: Multi-slice-detector CT is able to visualize PV and to detect PV stenoses. However, stenosis severity seems to be underestimated and not all lesions could be accurately detected. Larger studies have to be performed to further assess the diagnostic accuracy and clinical reliability of this new non-invasive method and to focus on the incidence of PV stenosis following RFA especially in long-time follow up.

Usefulness of noninvasive MSCT coronary angiography as first-line imaging technique in patients with chest pain: initial clinical experience.

PURPOSE: Comparative studies with invasive coronary angiography (ICA) indicated a good sensitivity and specificity in the noninvasive detection of coronary artery disease (CAD) using Multi-slice spiral computed tomography coronary angiography (MS-CTA). The aim was to investigate the usefulness of MS-CTA as first-line imaging technique in patients (pts) with known or suspected CAD and low to intermediate probability of a severe coronary lesion. We report on our initial clinical experience using MS-CTA without compelled ICA. MATERIAL AND METHODS: One hundred thirty six patients with chest pain underwent MS-CTA on an outpatient basis (age 60+/-10, suspicion of CAD: n=95, suspicion of restenosis: n=24, after CABG: n=17). Based on the MS-CTA results, a recommendation concerning further diagnostics and therapy was given to each pt. A telephone interview was performed after 455+/-166 days to evaluate the further clinical course. RESULTS: Per pt, 8.2+/-2.7 coronary segments could be evaluated. Based on the MSCT results, the presence of flow-limiting stenoses was excluded in n=77 (57%) pts (group I). An additional ICA was recommended in n=59 (43%) pts (group II). An ICA had been performed in meantime in 27/136 (20%) pts, and could be avoided in the majority of pts. Nevertheless, 58/136 (42%) pts reported on improved clinical symptoms and 42/136 (31%) pts of improved quality of life. CONCLUSIONS: MS-CTA was found to be useful to evaluate the need and to reduce the total number of ICA in pts with unclear chest pain. It appears to be the first noninvasive modality, which might be used on a clinical routine basis in selected groups of pts.

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.