Pulmonary hypertension: ECG-gated 64-section CT angiographic evaluation of new functional parameters as diagnostic criteria.

PURPOSE: To evaluate, by using electrocardiographically (ECG)-gated multidetector computed tomography (CT), parameters such as right ventricular outflow tract (RVOT) systolic shortening and myocardial thickness and right pulmonary artery (RPA) distensibility, reported to be abnormal at echocardiography and/or magnetic resonance (MR) imaging in patients with pulmonary hypertension (PHT). MATERIALS AND METHODS: The institutional review board approved the study and waived informed consent. Forty-five patients, 21 with PHT (group 1; mean pulmonary arterial pressure [PAP], 42 mm Hg) and 24 without (group 2; mean PAP, 16.5 mm Hg), who had undergone thoracic ECG-gated 64-section CT and right heart catheterization as part of their diagnostic work-up were included in this study. Two independent observers measured RPA distensibility and RVOT myocardial thickness, diameter, and cross-sectional area during systole and diastole. Their values were compared in both groups (Mann-Whitney U test). The area under the receiver operating characteristic (ROC) curve and Spearman correlation with mean PAP were also obtained. RESULTS: Interobserver agreement was good for all measurements (R > 0.8) except for systolic RVOT wall thickness. Median values of RPA distensibility, diastolic RVOT wall thickness, and systolic RVOT diameter and cross-sectional area were significantly different between groups 1 and 2. The largest area under the ROC curve was obtained with RPA distensibility (0.951; 95% confidence interval: 0.89, 1) also showing the closest correlation with mean PAP (r = -0.79; P < .0001). CONCLUSION: Among all parameters evaluated, RPA distensibility shows the best diagnostic value for PHT and could be useful for risk stratification.

Patent foramen ovale: detection with nongated multidetector CT.

PURPOSE: To evaluate nongated multidetector computed tomography (CT) in the detection of patent foramen ovale (PFO) and atrial septal aneurysm (ASA) in comparison with transesophageal echocardiography (TEE). MATERIALS AND METHODS: The study was approved by the institutional review board, and informed consent was obtained from all patients. One hundred five patients (57 men, 48 women; mean age, 53 years) with a recent stroke underwent TEE and multidetector CT on the same day. After injection of a diluted iodinated contrast material, a series of 2.4-mm-thick transverse images centered on the fossa ovalis were acquired in conjunction with release of the Valsalva maneuver. Two independent radiologists considered PFO present if left atrial enhancement was detected visually before enhancement of the pulmonary veins or if an early peak of left atrial enhancement was found at time-attenuation curve analysis. RESULTS: PFO was detected with 98% specificity (95% confidence interval [CI]: 0.91, 0.99). Overall sensitivity was 55% (95% CI: 0.38, 0.70), ranging from 28% for shunts classified as grade 1 at TEE to 91% for those classified as grade 4 at TEE. Interreader agreement was good (kappa = 0.81). Visual assessment was better than time-attenuation curve analysis, which enabled detection of only 15 of the 40 cases of PFO. Multidetector CT depicted only 22% of cases of ASA. The mean effective radiation dose was 2.3 mSv. CONCLUSION: Nongated multidetector CT can be used to diagnose high-grade shunts through a PFO, with 91% sensitivity and 98% specificity. Thus, PFO detection, in addition to routine CT evaluation of the lungs, could be indicated in patients with unexplained hypoxemia.

Coronary imaging quality in routine ECG-gated multidetector CT examinations of the entire thorax: preliminary experience with a 64-slice CT system in 133 patients.

To evaluate image quality in the assessment of the coronary arteries during routine ECG-gated multidetector CT (MDCT) of the chest. One hundred and thirty three patients in sinus rhythm underwent an ECG-gated CT angiographic examination of the entire chest without beta-blockers with a 64-slice CT system. In 127 patients (95%), it was possible to assess the coronary arteries partially or totally; coronary artery imaging failed in six patients (5%), leading to a detailed description of the coronary arteries in 127 patients. Considering ten coronary artery segments per patient, 75% of coronary segments were assessable (948/1270 segments). When the distal segments were excluded from the analysis (i.e., seven coronary segments evaluated per patient), the percentage of assessable segments was 86% (768/889 proximal and mid coronary segments) and reached 93% (474/508) when assessing proximal segments exclusively. The mean number of assessable segments was significantly higher in patients with a heart rate < or =80 bpm (n=95) than in patients with a heart rate >80 bpm (n=38) (p<0.002). Proximal and mid-coronary segments can be adequately assessed during a whole-chest ECG-gated CT angiographic examination without administration of beta-blockers in patients with a heart rate below 80 bpm.

Coronary artery imaging during preoperative CT staging: preliminary experience with 64-slice multidetector CT in 99 consecutive patients.

The purpose of this study was to evaluate the clinical feasibility of coronary artery imaging during routine preoperative 64-slice MDCT scans of the chest. Ninety-nine consecutive patients in sinus rhythm underwent a biphasic multidetector-row spiral CT examination of the chest without the administration of beta-blockers, including an ECG-gated acquisition over the cardiac cavities, followed by a non-gated examination of the upper third of the thorax. Data were reconstructed to evaluate coronary arteries and to obtain presurgical staging of the underlying disease. The percentage of assessable segments ranged from 65.4% (972/1,485) when considering all coronary artery segments to 88% (613/693) for the proximal and mid segments, reaching 98% (387/396) for proximal coronary artery segments. The 387 interpretable proximal segments included 97 (97%) LM, 99 (100%) LAD, 96 (97%) LCX and 95 (96%) RCA with a mean attenuation of 280.70+/-52.93 HU. The mean percentage of assessable segments was significantly higher in patients with a heart rate

Integrated cardio-thoracic imaging with ECG-Gated 64-slice multidetector-row CT: initial findings in 133 patients.

The purpose of this study was to investigate the possibility of assessing the underlying respiratory disease as well as cardiac function during ECG-gated CT angiography of the chest with 64-slice multidetector-row CT (MDCT). One hundred thirty-three consecutive patients in sinus rhythm with known or suspected ventricular dysfunction underwent an ECG-gated CT angiographic examination of the chest without beta-blockers using the following parameters: (1) collimation: 32 x 0.6 mm with z-flying focal spot for the acquisition of 64 overlapping 0.6-mm slices (Sensation 64; Siemens); rotation time: 0.33 s; pitch: 0.3; 120 kV; 200 mAs; ECG-controlled dose modulation (ECG-pulsing) and (2) 120 ml of a 35% contrast agent. Data were reconstructed: (1) to evaluate the underlying respiratory disease (1-mm thick lung and mediastinal scans reconstructed at 55% of the R-R interval; i.e., "morphologic scans") and (2) to determine right (RVEF) and left (LVEF) ventricular ejection fractions (short-axis systolic and diastolic images; Argus software; i.e., "functional scans"). The mean heart rate was 73 bpm (range: 42-120) and the mean scan time was 18.11 +/- 2.67 s (range: 10-27). A total of 123 examinations (92%) had both lung and mediastinal images rated as diagnostic scans, whereas 10 examinations (8%) had non-diagnostic images altered by the presence of respiratory-motion artifacts (n = 4) or cyclic artifacts related to the use of a pitch value of 0.3 in patients with a very low heart rate during data acquisition (n = 6). Assessment of right and left ventricular function was achievable in 124 patients (93%, 95% CI: 88-97%). For these 124 examinations, the mean RVEF was 46.10% (+/- 9.5; range: 20-72) and the mean LVEF was 58.23% (+/- 10.88; range: 20-83). In the remaining nine patients, an imprecise segmentation of the right and left ventricular cavities was considered as a limiting factor for precise calculation of end-systolic and end-diastolic ventricular volumes. The mean (+/- SD) DLP value of the examinations was 279.86 (+/- 117.50) mGy.cm. Assessment of underlying respiratory disease and cardiac function from the same data set was achievable in 92% of the patients with ECG-gated 64-slice MDCT.

Multi-detector row CT angiography of pulmonary circulation with gadolinium-based contrast agents: prospective evaluation in 60 patients.

PURPOSE: To prospectively evaluate gadolinium dose safety and effectiveness for 16-detector pulmonary computed tomographic (CT) angiography. MATERIALS AND METHODS: Ethics committee approval and informed consent were obtained. Sixty patients with contraindications to iodine underwent CT of the pulmonary circulation with 0.5 mmol/L gadolinium chelate given at either 0.3 (n = 29, group A) or 0.4 (n = 31, group B) mmol/kg; clinical and biologic tolerances were evaluated. Enhancement of central and segmental pulmonary arteries was measured (poor enhancement, <100 HU; good, 100-150 HU; excellent, >150 HU). Subsegmental artery enhancement was assessed as similar or inferior to that of segmental arteries. Confidence in analysis of the pulmonary arterial bed was graded according to arterial enhancement: Grades 1-3, diagnostic images; grade 4, nondiagnostic. The main effectiveness parameter for comparison between groups A and B was diagnostic value of CT angiograms. Nonparametric statistics were used to analyze results. RESULTS: The mean (+/- standard deviation) contrast material volume was 50.09 mL +/- 8.45 (all patients: range, 30-64 mL; group A: 46.54 mL +/- 8.59; group B: 53.42 mL +/- 6.92). Diagnostic images were obtained in 55 (92%) patients, and confident analysis of pulmonary arteries to the subsegmental level was achieved in 26 (grade 1, 44%) and to the segmental level, in 21 (grade 2, 35%). Mean attenuation was higher in group B than in group A in central (180.61 HU +/- 53.85 vs 148.14 HU +/- 52.61; P = .04) and segmental (201.59 HU +/- 54.70 vs 164.73 HU +/- 59.26; P = .03) arteries. Number of diagnostic CT angiograms was higher (P = .02) in group B (n = 31 [100%]) than in group A (n = 24 [83%]). In both groups, mean enhancement of pulmonary arteries was significantly higher at 80 or 100 kV than at 120 kV. Renal function was impaired in two group A patients. CONCLUSION: Gadolinium chelates may be used as an alternative CT contrast agent in patients who cannot receive iodine.