New Method of Measuring Coronary Diameter by Electron-Beam Computed Tomographic Angiography Using Adjusted Thresholds Determined by Calibration With Aortic Opacity

Quantitative Evaluation of Coronary Plaque Progression by Computed Tomographic Angiography

Understanding plaque formation in patients at risk for coronary artery disease-the leading cause of morbidity and death in the world-enables physicians to better determine whether and how to treat these individuals. We used computed tomographic angiography to quantitatively evaluate the progression of nonculprit coronary plaques along the full length of the right coronary artery in 21 patients with acute coronary syndrome. Each right coronary artery was analyzed in sequential, 3-mm-long segments, and the minimum luminal area, plaque burden, and plaque volume within each segment were evaluated at baseline and at 12-month follow-up. Serial remodeling of the right coronary artery was also evaluated. In total, 625 arterial segments were analyzed. At 12-month follow-up, the plaque burden had increased slightly by 0.34% (interquartile range [IQR], -4.32% to 6.35%; P=0.02), and the plaque volume was not significantly changed (0.33 mm3; IQR, -3.05 to 3.54; P=0.213). The minimum luminal area decreased 0.05 mm2 (IQR, -1.33 to 0.87 mm2; P=0.012), and this was accompanied by vessel reduction, as evidenced by negative remodeling in 43% of the 625 segments. We conclude that serial computed tomographic angiography can be used to quantitatively evaluate the morphologic progression of coronary plaques.

MDCT coronary angiography -- postprocessing, reading, and reporting: last but not least

Significant literature on MDCT coronary angiography (MDCT-CA) has emerged in the last decade concerning patient's selection, technical aspects of different generations of CT equipment, ECG gating, contrast material and beta-blockade administration, acquisition parameters, and radiation dose. However, the literature regarding postprocessing, reading, and reporting is not so extensive. This review highlights the main elements of MDCT-CA data analysis, thereby allowing the radiologist to take full advantage of this technology and enable a structured report to be generated, promoting best practice with high-quality results.

Quantification and characterization of obstructive coronary plaques using 64-slice computed tomography: a comparison with intravascular ultrasound

PURPOSE

The aim of this study was to determine the diagnostic accuracy of 64-slice computed tomography (CT) coronary angiography in the quantification and characterization of obstructive coronary plaques in comparison with intravascular ultrasound (IVUS).

MATERIALS AND METHODS

Thirty-nine patients were selected who underwent both CT coronary angiography (CTCA) and IVUS. For each stenotic site (n = 61), the maximum vessel cross-sectional area, lumen cross-sectional area, plaque area, and percentage of luminal obstruction were measured. Plaque composition was analyzed according to IVUS (plaque echogenicity and classified into several types: calcified, mixed, fibrous, and soft plaques) and CTCA criteria (Hounsfield units [HU]). The correlation between CTCA and IVUS measurements was determined using Pearson correlation coefficient. The statistical significance of differences in the CT densities of plaques among plaque types determined by IVUS was assessed using the Scheffe method.

RESULTS

The correlation coefficients for the measurements of the lumen, vessel, plaque area, and percentage of luminal obstruction were r = 0.712, r = 0.654, r = 0.753, and r = 0.799, respectively. The mean CT density values for soft (n = 10), fibrous (n = 11), mixed (n = 31), and calcified plaques (n = 9) were 54 +/- 13 HU, 82 +/- 17 HU, 162 +/- 57 HU, and 392 +/- 155 HU, respectively. Computed tomography density measurements were not significantly different between soft and fibrous plaques (P = 0.224).

CONCLUSIONS

Sixty-four-slice CTCA is a noninvasive modality that allows quantification of coronary artery plaques. However, reliable classification of noncalcified plaques as vulnerable or stable plaques based on CT density measurements is currently limited.

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

PURPOSE

To exclusively enhance the left side of the heart by a small amount of contrast material (CM) using rapid acquisition of multislice computed tomography (MSCT) with a 64-data acquisition system (DAS).

MATERIALS AND METHODS

Forty consecutive subjects underwent MSCT (Light Speed VCT, GE) with 0.625mm slice thickness to evaluate coronary arteries. We first measured transit time, using 8ml of CM followed by 20ml saline. Dependent upon transit time, total volume of CM was determined, ranging from 45 to 63ml. After injection of CM at a rate of 4ml/s, followed by 47ml saline at 3.5ml/s, ECG-gated MSCT scanning was performed. The mean and standard deviation (S.D.) of CT values of the right atrium (RA), right ventricle (RV), left atrium (LA), left ventricle (LV), ascending aorta (Ao) and each coronary artery were measured.

RESULTS

The mean of the CT values of the RA, RV, LA, LV, Ao, right coronary artery, left main, left anterior descending branch, and left circumflex branch were 225+/-76, 251+/-72, 353+/-55, 355+/-51, 352+/-34, 312+/-65, 296+/-57, 285+/-55, and 267+/-60HU, respectively. The corresponding S.D.s of the CT values were 39+/-22, 37+/-16, 32+/-7, 31+/-8HU, 25+/-5, 36+/-15, 31+/-13, 36+/-23, and 40+/-18HU, respectively. The mean of CT values of the RA and RV were significantly lower than those of the LA, LV, Ao, and each coronary artery (P<0.01), with excellent S.D.s. We could easily obtain three-dimensional coronary arterial and LV images without artifact of the RA and RV.

CONCLUSIONS

Using 64-DAS MSCT, we successfully obtained exclusive enhancement of the left side of the heart using a small amount of CM.

Utility of Four-Dimensional Analysis of the Acetabular Labrum Applying Motion-Gated Multislice Computed Tomography

To analyze the kinesis and morphology of the acetabular labrum (AL) noninvasively, we applied 4-dimensional arthrography with motion-gated multislice computed tomography and compared the results with arthroscopy and Harris hip score (HHS) in 49 symptomatic patients who performed reciprocating hip flexion-extension as we carried out mimic retrospective electrocardiogram-gating acquisition. The kinematics and morphology of AL were classified as stabilized, irregular, or eccentric motion patterns. Of the 9 subjects who had intact or frayed AL on arthroscopy, 7 had stabilized motion (average 50 HHS) and 2 had irregular (44 HHS) motion by CT arthroscopy. Of the 16 without adhesive AL on arthroscopy, 6 had irregular motion (48 HHS) and 4 had eccentric motion (58 HHS). We found that the 4-dimensional arthrography with motion-gated multislice computed tomography can reveal both kinetic and morphological changes of the AL, and facilitate further stratification in subjects with the American Academy of Orthopaedic Surgeons class 0, or 1 or without "detached" morphological findings by arthroscopy.

Direction, location, and size of shunt flow in congenital heart disease evaluated by ECG-gated multislice computed tomography

OBJECTIVE

To demonstrate the utility of multislice computed tomography (MSCT) in the evaluation of direction, location, and size of shunt flow in congenital heart disease.

BACKGROUND

Transthoracic and transesophageal echocardiography, magnetic resonance imaging, and conventional angiography has been used to evaluate congenital heart disease; however, some are invasive and some do not provide accurate information about the spatial relationship to other organs.

METHODS

Three patients with typical presentation of ventricular septal defect, atrial septal defect, and patent ductus arteriosus were recruited. Enhanced MSCT (Light Speed Ultra 16, General Electric) was performed with a 1.25-mm slice thickness, helical pitch 3.25. Following intravenous injection of 100 ml of iodinated contrast material (350 mg I/ml) at a rate of 3 ml/s, CT scanning was performed with retrospective ECG-gated reconstruction at 5 s and 30 s after injection.

RESULTS

In all cases the information of direction, location, and size of shunt flow including left-to-right and right-to-left shunt with spatial relationship to other organs could be obtained non-invasively.

CONCLUSION

ECG-gated MSCT is a useful tool to evaluate congenital heart diseases with shunts.

Utility of triple channel injection of contrast material with mixture of saline, with acquisition in the cephalic direction for arterial trees in the thorax using multislice computed tomography

BACKGROUND

If contrast material is injected into the cubital vein, artifacts due to high concentration of the contrast material in the vein lead to deterioration of the opacification of the thoracic aorta and the major branches. We describe a new protocol employing a combination of triple channel contrast material injection and a mixture of saline with acquisition in the cephalic direction utilizing capability of 16-slice multislice CT.

MATERIALS AND METHODS

Of 35 subjects who underwent thoracic CT, 18 were injected with 70 ml contrast each prior to scanning with acquisition in the cephalic direction during the injection of 30 ml contrast diluted 50/50 with saline, followed by the injection of 20 ml of saline (new protocol). Seventeen subjects were injected each with 100 ml contrast at 3 ml/s, with scanning in the caudal direction (ordinary protocol).

RESULTS

In the new protocol, the major branches of the aorta and the left ventricle were more opacified, but the veins were less opacified compared with the ordinary protocol, resulting in clear delineation of the thoracic aorta and the major branches without artifacts.

CONCLUSIONS

A new acquisition protocol is described in which the thoracic aorta and the major branches can be evaluated without artifact due to high CT values in the veins. Faster, more informative CT scans can be performed using diluted contrast.

Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography: a comparative study with quantitative coronary angiography and intravascular ultrasound

OBJECTIVES

The aim of the present study was to determine the diagnostic accuracy of 64-slice computed tomography (CT) to identify and quantify atherosclerotic coronary lesions in comparison with catheter-based angiography and intravascular ultrasound (IVUS).

BACKGROUND

Currently, the ability of multislice CT to quantify the degree of coronary artery stenosis and dimensions of coronary plaques has not been evaluated.

METHODS

We included 59 patients scheduled for coronary angiography due to stable angina pectoris. A contrast-enhanced 64-slice CT (Senation 64, Siemens Medical Solutions, Forchheim, Germany) was performed before the invasive angiogram. In a subset of 18 patients, IVUS of 32 vessels was part of the catheterization procedure.

RESULTS

In 55 of 59 patients, 64-slice CT enabled the visualization of the entire coronary tree with diagnostic image quality (American Heart Association 15-segment model). The overall correlation between the degree of stenosis detected by quantitative coronary angiography compared with 64-slice CT was r = 0.54. Sensitivity for the detection of stenosis <50%, stenosis >50%, and stenosis >75% was 79%, 73%, and 80%, respectively, and specificity was 97%. In comparison with IVUS, 46 of 55 (84%) lesions were identified correctly. The mean plaque areas and the percentage of vessel obstruction measured by IVUS and 64-slice CT were 8.1 mm2 versus 7.3 mm2 (p < 0.03, r = 0.73) and 50.4% versus 41.1% (p < 0.001, r = 0.61), respectively.

CONCLUSIONS

Contrast-enhanced 64-slice CT is a clinically robust modality that allows the identification of proximal coronary lesions with excellent accuracy. Measurements of plaque and lumen areas derived by CT correlated well with IVUS. A major limitation is the insufficient ability of CT to exactly quantify the degree of stenosis.

Cardiovascular Circulation and Hepatic Perfusion of Pigs in 4-Dimensional Films Evaluated by 256-Slice Cone-Beam Computed Tomography

BACKGROUND

In both cardiac and hepatic disorders it is desirable to accurately visualize the direction and scale of blood flow in the whole organ in pulsating 3-dimensional (D) images, which are known as 4-D images.

METHODS AND RESULTS

The present study used 256-slice cone-beam computed tomography (CT) (Athena, Sony-Toshiba) at one rotation per second and a section thickness of 0.5 mm to show the dynamics of cardiovascular circulation and hepatic perfusion by contrast injection in 4-D films of pigs. Four pigs (20 kg each) were anesthetized with isoflurane. The distal tips of the catheters were positioned in the inferior vena cava (IVC) (pigs 1-3) and in the proper hepatic artery (pig 4). Volumetric scanning and injection of contrast material were started simultaneously and continued for 25 s with image reconstruction at 1-s intervals. In pigs 1-3, 4-D filming revealed the dynamics of cardiovascular circulation, first in the IVC, followed by the right ventricle and pulmonary artery, then the left ventricle, left atrium, pulmonary vein, and finally, the right heart disappeared and only the left heart and aorta remained visible. In pig 4, the hepatic arterial trees, followed by the venous trees, could be easily visualized in turn on the 4-D images.

CONCLUSIONS

This technology successfully demonstrated cardiovascular circulation and hepatic perfusion in 4-D and will have clinical applicability.

Serial Angiographic Follow-up Beyond 10 Years After Coronary Artery Bypass Grafting

BACKGROUND

The long-term prognosis and serial angiographic follow-up beyond 10 years in patients who underwent coronary artery bypass grafting (CABG) have not been fully studied in Japan.

METHODS AND RESULTS

In the present study data from 71 patients who underwent CABG before 1992 were analyzed. Thirty patients had a saphenous vein graft (SVG) only group, and the remaining 41 had a left internal thoracic artery graft to the left anterior descending coronary artery (LITA) group; 6 patients died from malignancy, which was the most common cause of death after CABG. The major adverse cardiac events (MACE) were defined as cardiac death, Q-wave or nonQ-wave myocardial infarction, and congestive heart failure. The MACE-free rate was significantly higher in the LITA group than in the SVG group (p < 0.05). However, among the patients with an ejection fraction < 0.40, there was no significant difference in MACE-free rate between the 2 groups. The LITA patency rate was significantly higher than that for SVG (p < 0.05) and the SVG patency rate was lower in the patients with hyperlipidemia (p < 0.05); cholesterol-lowering therapy improved the SVG patency rate.

CONCLUSION

The long-term outcome of CABG was favorable, particularly if using an arterial graft. Although the patency rate was lower for the SVG than LITA, the patient's lipid profile might be an important factor in the SVG patency rate.