New acquisition method to exclusively enhance the left side of the heart by a small amount of contrast material achieved by multislice computed tomography with 64 data acquisition system

Contrast Enhancement of the Right Ventricle during Coronary CT Angiography--Is It Necessary?

Purpose

It is unclear if prolonged contrast media injection, to improve right ventricular visualization during coronary CT angiography, leads to increased detection of right ventricle pathology. The purpose of this study was to evaluate right ventricle enhancement and subsequent detection of right ventricle disease during coronary CT angiography.

Materials and Methods

472 consecutive patients referred for screening coronary CT angiography were retrospectively evaluated. Every patient underwent multidetector-row CT of the coronary arteries: 128x 0.6mm coll., 100-120kV, rot. time 0.28s, ref. mAs 350 and received an individualized (P3T) contrast bolus injection of iodinated contrast medium (300 mgI/ml). Patient data were analyzed to assess right ventricle enhancement (HU) and right ventricle pathology. Image quality was defined good when right ventricle enhancement >200HU, moderate when 140-200HU and poor when <140HU.

Results

Good image quality was found in 372 patients, moderate in 80 patients and poor in 20 patients. Mean enhancement of the right ventricle cavity was 268HU±102. Patients received an average bolus of 108±24 ml at an average peak flow rate of 6.1±2.2 ml/s. In only three out of 472 patients (0.63%) pathology of the right ventricle was found (dilatation) No other right ventricle pathology was detected.

Conclusion

Right ventricle pathology was detected in three out of 472 patients; the dilatation observed in these three cases may have been picked up even without dedicated enhancement of the right ventricle. Based on our findings, right ventricle enhancement can be omitted during screening coronary CT angiography.

Quantitative effect of Atorvastatin on size and content of non-calcified plaques of coronary arteries 1 year after Atorvastatin treatment by multislice computed tomography

PURPOSE

Intensive lipid-lowering treatment with Atorvastatin reduced progression of coronary atherosclerosis, confirmed by IVUS. To quantitate the effect of Atorvastatin on the size and content of non-calcified coronary plaques (NCP) using multislice CT (MSCT) and by comparison of LDL cholesterol levels.

MATERIALS AND METHODS

Twenty-one subjects (16 males, 35-79 years, median 69) with NCP by MSCT (Light Speed Ultra 16, GE) were enrolled. All were asymptomatic thereby distinguishing NCP from thrombi in coronary arteries. Following LDL cholesterol measurements, all were given 10 mg of Atorvastatin (2 were given 5 mg as LDL cholesterol levels were already <70 mg/dl) for 1 year, at which point MSCT and LDL cholesterol measurements were repeated. One remarkable NCP was selected in each subject and evaluated as representative of the effect of Atorvastatin. The area and CT values for NCP, excluding calcified portions, were manually measured from axial source or multiplanar reconstruction images under the same conditions using an workstation (Virtual Place Advance Plus, AZE).

RESULTS

Twenty-one NCPs (18 left anterior descending branch, 2 left circumflex branch, and 1 right coronary artery) were evaluated. Mean LDL cholesterol levels were 122 mg/dl at the first scan and significantly decreased to 96 mg/ml at the second scan (P<0.05). The NCP areas were 2-31 mm(2) (mean 11.8) at the first scan, and 2-32 mm(2) (mean 12.6) at the second scan. These differences were not significantly different. The averages of CT values were 15-91 HU (mean 55 HU) at the first scan and 38-114 HU (mean 62 HU) at the second scan. SDs of CT values of the two scans were 14-64 HU (mean 40 HU) and 20-68 HU (mean 45 HU), respectively. The averages and SDs of CT values were significantly higher in the second scan (P<0.05). There was a weak but significant positive correlation between ratios (%) of change in area to baseline area at first scan of NCPs (y) and LDL cholesterol levels (x) after 1 year of Atorvastatin treatment (y=0.0106x-0.7265, R(2)=0.1514, R=0.39, P<0.05).

CONCLUSION

Using MSCT, we could quantitate the effect of Atorvastatin to the size and content of NCP and compare those with LDL cholesterol levels. Atorvastatin may decrease area of NCP if LDL cholesterol levels are sufficiently reduced. Also, it may increase CT values, which could suggest a change in NCP composition. LDL cholesterol levels may be an important factor in decreasing NCP area. Further studies are needed using 64-slice MSCT in a larger population exhibiting greater decreases in LDL cholesterol levels.

Utility of multislice computed tomography with a 64-data acquisition system for four-dimensional volumetric analysis using a pulsating phantom and considering pulsation rate and reconstruction methods

PURPOSE

To evaluate 64-data acquisition system (DAS) MSCT (Light Speed VCT, GE) at 0.625 mm slice thickness, 0.35 s/rotation, tube 120 kV at 400 mA, ECG-gated for 4-D volumetric analysis, we used pulsating phantoms to measure end-diastolic (EDV) and end-systolic (ESV) volume and ejection fraction (EF) to assess reconstruction methods especially for higher pulsation rates.

MATERIALS AND METHODS

A pulsating device (AZ-631N, Anzai Medical) with contrast material (300 mgI/dl) diluted 10x with saline was moved at 40-110 to-and-fro movements/min. ECG-gated MSCT was performed x5 per pulsation rate. The EDV and ESV were measured using workstation (Virtual Place Advance Plus, Aze).

RESULTS

The mean EDV and ESV were 98, 97, 97 96, 95, 94, and 101% and 145, 143, 142, 144, 145, 149, 156 and 160%, respectively, compared to the static state. EF was 80, 81, 81, 80, 79, 77, 73, and 76% at 40-110 pulsations/min, when reconstructed by the segmented method, but was improved to 82, 83, 85, and 84% at 80-110 beat/min when reconstructed by the burst method. The latter is therefore more appropriate for higher rates.

CONCLUSION

This 64-DAS MSCT can measure EDV even at high beat rates (up to 110 beats per minute) compared to the static state. Because ESV tended to be overestimated by approximately 140-160% compared with the static state, EF tended to be underestimated by approximately 73-81% compared with the static state. However, at higher beat rates of >70 beat/min, an appropriate reconstruction method (the burst method) may further improve the accuracy of EF measurement.

Interatrial shunt detected in coronary computed tomography angiography: differential features of a patent foramen ovale and an atrial septal defect

OBJECTIVE

To determine differential findings of patent foramen ovales (PFOs) and atrial septal defects (ASDs) demonstrating interatrial shunting on coronary computed tomography (CT) angiography.

METHODS

We retrospectively analyzed 15 cases of patients demonstrating a contrast jet from the left to the right atrium on CT and interatrial shunting on echocardiography. According to the echocardiography results, patients were divided into PFO (n = 10) or ASD (n = 5) groups. The contrast jet direction and atrial septum appearance on CT were compared between the 2 groups.

RESULTS

The PFO group had a contrast jet flowing toward the inferior vena cava, and the atrial septum appeared channel-like. The ASD group had a contrast jet flowing perpendicular to the atrial septum in all but one of the patients, and the atrial septum appeared as a membrane with a hole.

CONCLUSIONS

Atrial septal defects and PFOs can be differentiated using the characteristic direction of the contrast jet from the left to right atrium and the appearance of the atrial septum on coronary CT angiography.

Quantitative 4-dimensional volumetric analysis of left ventricle in ischemic heart disease by 64-slice computed tomography: a comparative study with invasive left ventriculogram

OBJECTIVE

To elucidate the usefulness of CT in evaluating left ventricular (LV) volumes and ejection fraction (EF) in ischemic heart disease (IHD), we compared 64-slice CT with conventional left ventriculography (CLVG).

MATERIALS AND METHODS

71 subjects with suspected or confirmed IHD underwent ECG-gated enhanced CT before or after cardiac catheterization. End-diastolic volume (EDV) and end-systolic volume (ESV) of LV were selected in 20 phases of R-R interval of ECG, and data sets were reconstructed to determine EDV, ESV, SV, and EF of LV using a multislice area summation method; in CLVG these parameters were calculated from the right anterior oblique 30-degree projection.

RESULTS

Correlation coefficients between CT and CLVG for EDV, ESV, SV, and EF were 0.759, 0.895, 0.550, and 0.836, respectively (P<0.01). In 35 subjects without apical asynergy of LV wall motion, correlation coefficients between CT and CLVG were 0.77, 0.91, 0.63, and 0.87 respectively (P<0.01); in 36 subjects, with apical asynergy, the correlation coefficients were 0.751, 0.875, 0.503, and 0.738, respectively (P<0.01). The limits of agreement of all parameters were wider in the subjects with apical asynergy of LV wall motion than the subjects without.

CONCLUSION

There was good correlation between EDV, ESV, SV, and EF estimated by CT and those by CLVG, but CT tended to overestimate EDV and ESV and underestimate EF. In subjects with apical asynergy of LV wall motion, estimates of EF were less correlated between CT and CLVG and the limits of agreement of all parameters were wider than in those without. These discrepancies may come from the capability of CT to estimate LV wall asynergy 3-dimensionally and more accurately.

Contrast enhancement in cardiovascular MDCT: effect of body weight, height, body surface area, body mass index, and obesity

OBJECTIVE

The purpose of our study was to evaluate the effect of body weight, height, body surface area (BSA), body mass index (BMI), and obesity on aortic contrast enhancement in cardiac MDCT.

MATERIALS AND METHODS

Seventy-three consecutive patients underwent cardiac CT angiography on a 64-MDCT scanner. Seventy-five mL of contrast medium (350 mg I/mL) was injected at 4.5 mL/s, followed by a 40-mL saline flush at 4.5 mL/s. The scanning delay of CT was determined with a bolus tracking technique. Aortic attenuation was measured over the aortic-root lumen. BMI and BSA were calculated from the patient's body weight and height. The patients were divided into low-(BMI < 30) and high-(> or = 30) BMI groups. Associations of aortic attenuation with body weight, height, BMI, and BSA were evaluated with regression analysis and the Student's t test.

RESULTS

Strong inverse correlations were seen between aortic attenuation and body weight (r = -0.73), height (r = -0.47), BMI (r = -0.63), and BSA (r = -0.74) (p < 0.001 for all). The regression formula of aortic attenuation versus body weight suggests that 1.0 mL/kg of contrast medium would yield a mean aortic attenuation of 355 H. The mean aortic attenuation was significantly higher in the low-BMI (352.6 +/- 59.1 H) than in the high-BMI (286.2 +/- 55.5 H) group. The regression formula for aortic attenuation on body weight was aortic attenuation = 586-3.1 body weight (p < 0.001) for the low-BMI group and aortic attenuation = 485-1.9 body weight (p < 0.001) for the high-BMI group, suggesting that the amount of contrast medium required with increased body weight is less in the high-BMI group. This group difference was less pronounced for the regression of aortic attenuation on BSA.

CONCLUSION

To achieve a consistent contrast enhancement in cardiac CT angiography (CTA), contrast-medium dose should be adjusted with the body weight or the BSA (which accounts for both the body weight and height factors) to provide adjustment of iodine dose over a wide range of body sizes.

Tricolored “Tricolore” myocardium by selective intracoronary injection of contrast using 256-slice cone-beam computed tomography

We report our experience with 256-slice cone-beam computed tomography following selective coronary arterial bolus injection in pigs, which distinguished the segmented left ventricular (LV) myocardium supplied by each coronary artery into three parts more clearly than with other modalities. Two pigs were anesthetized and catheters positioned in the left anterior descending branch (LAD) of the coronary artery in pig 1 and the left circumflex branch (LCx) in pig 2. 10 ml of iodinated contrast material diluted with 40 ml of saline was injected at a rate of 3 ml/s. Entire heart scanning was started simultaneously and continued for 25 s. We selected the most static images of the LV at around 5 s after contrast injection. Axial source and multiplanar reconstruction images from the right anterior oblique projection clearly revealed tricolored, segmented LV myocardial enhancement of the anterior and apical walls and inter-ventricular septum in pig 1, and the lateral and posterior walls in pig 2. We were able to identify the borders between the LV myocardium supplied by the LAD, the LCx and the right coronary artery, respectively, and this technique may facilitate new cardiovascular diagnoses.