Value of 3D-volume rendering in the assessment of coronary arteries with retrospectively ECG-gated multislice spiral CT

Application of Computed Tomography Processed by Picture Archiving and Communication Systems in the Diagnosis of Acute Achilles Tendon Rupture

The applications of CT examination in the diagnosis of the acute Achilles tendon rupture (AATR) were investigated. A total of 36 patients with suspected acute Achilles tendon rupture were tested using physical examination, ultrasound, and 3DCT scanning, respectively. Then, surgery was performed for the patients who showed positive result in at least two of the three tests for AATR. 3DVR, MPR, and the other CT scan image processing and diagnosis were conducted in PACS (picture archiving and communication system). PACS was also used to measure the length of distal broken ends of the Achilles tendon (AT) to tendon calcaneal insertion. Our study indicated that CT has the highest accuracy in diagnosis of acute Achilles tendon complete rupture. The length measurement is matched between PACS and those actually measured in operation. CT not only demonstrates more details directly in three dimensions especially with the rupture involved calcaneal insertion flap but also locates the rupture region for percutaneous suture by measuring the length of distal stump in PACS without the effect of the position of ankle. The accuracy of CT diagnosis for Achilles tendon partial rupture is yet to be studied.

Cardiac helical CT involving a low-radiation-dose protocol with a 100-kVp setting: Usefulness of hybrid iterative reconstruction and display preset optimization

To compare the radiation dose and image quality of retrospective electrocardiogram (ECG)-gated cardiac computed tomography (CT) between a 100-kVp protocol, hybrid iterative reconstruction (HIR), and display preset optimization and the 120-kVp protocol.We prospectively enrolled 100 patients with tachycardia or atrial fibrillation scanned retrospective ECG-gated cardiac CT. We randomly assigned 50 patients to the 120-kVp protocol and 50 patients to the 100-kVp protocol. We compared effective doses (EDs) between the two protocols. The 120-kVp images were post-processed using filtered back projection (FBP). The 100-kVp images were post-processed using FBP (100-kVp protocol) and HIR (i-100-kVp protocol). We compared attenuation of the ascending aorta, signal-to-noise ratio (SNR), and image noise between the 120-kVp, 100-kVp, and i-100-kVp protocols. We performed qualitative image analysis for the 120-kVp and i-100-kVp protocols.ED of the 100-kVp protocol (4.4 ± 0.4 mSv) was 76% lower than that of the 120-kVp protocol (18.4 ± 0.6 mSv). Attenuations of the 100-kVp (549.1 ± 73.8 HU) and i-100-kVp (550.5 ± 73.7 HU) protocols were higher than that of the120-kVp protocol (437.3 ± 55.7 HU). Image noise of the 100-kVp (53.6 ± 18.5 HU) and i-100-kVp (30.9 ± 8.6 HU) protocols were higher than that of the120-kVp protocol (23.8 ± 5.7 HU). There was no significant difference in SNR and the result of qualitative image analysis between the 120-kVp and i-100-kVp protocols.The 100-kVp protocol with HIR reduced the 76% radiation dose while preserving the image quality compared with the conventional 120-kVp protocol on retrospective ECG-gated cardiac CT.

[Quantification of coronary artery stenoses: comparison of 64-slice and dual source CT angiography with cardiac catheterization]

BACKGROUND

Until now stenoses of the coronary arteries have been evaluated visually with CT angiography. Therefore, the results were highly dependent on subjective factors inherent in the examiner. New software tools for semiquantitative analysis (CT-QCA, quantitative coronary assessment) might be adequate to improve the diagnostic accuracy und reproducibility.

MATERIAL AND METHODS

CTAs of 20 patients were analyzed. Ten patients each were evaluated using 64-slice CT (64SCT) and dual source CT (DSCT) (Somatom Sensation 64 and Somatom Definition, Siemens Medical Solutions, Forchheim), respectively. Two radiologists independently evaluated the data visually and with the help of a software tool (Syngo Circulation, Siemens Medical Solutions, Forchheim). The results of the quantitative assessment of the invasive heart catheterization served as the reference standard. Sensitivity and specificity as well as the correlation coefficient, the systematic error, and the interobserver agreement (kappa) were determined.

RESULTS

In each of both patient groups 12 stenoses were detected. For the detection of stenoses >75%, sensitivity and specificity for the visual evaluation using the 64SCT were 100% and 90%, and with the CT-QCA both were 100%. For the DSCT sensitivity and specificity were 100% for both the visual and semiautomated evaluation. The Bland-Altman plot of the results of the 64SCT showed an overestimation of 3.3% (+/-62.7%/56.2%) compared to the heart catheterization. The results of the DSCT exhibited an overestimation of 6.2% (+/-33.1%/19.8%). The interobserver agreement of the CT-QCA and the visual evaluation showed a kappa value of 0.75 and for DSCT of 1.0.

CONCLUSION

The results showed a good correlation of grading stenosis between the software-assisted evaluation and the results of the coronary catheter angiography. The promising results of the DSCT are due to a superior temporal resolution compared to the 64SCT. Confirmation of these data by trials in larger patient collectives is warranted.

Reproducible coronary plaque quantification by multislice computed tomography

BACKGROUND

The aim of this study was to investigate reproducibility and accuracy of computer-assisted coronary plaque measurements by multislice computed tomography coronary angiography (QMSCT-CA).

METHODS AND RESULTS

Forty-eight patients undergoing MSCT-CA and coronary arteriography for symptomatic coronary artery disease and quantitative intravascular ultrasound (IVUS, QCU) were examined. Two investigators performed the QMSCT-CA twice and a third investigator performed the QCU, all blinded for each other's results. There was no difference found for the matched region of interest (ROI) lengths (QCU 29.4 +/- 13 mm vs. QMSCT-CA 29.6 +/- 13 mm, P = 0.6; total length = 1,400 mm). The comparison of volumetric measurements showed (lumen QCU 267 +/- 139 mm(3) vs. mean QMSCT-CA 177 +/- 91 mm(3), P < 0.001; vessel 454 +/- 194 mm(3) vs. 398 +/- 187 mm(3), P <<0.001; and plaque 189 +/- 93 mm(3) vs. 222 +/- 121 mm(3); investigator 1, P = 0.02; and investigator 2, P = 0.07) significant differences. Automated lumen detection was also applied for QMSCT-CA (218 +/- 112 mm(3), P < 0.001 vs. QCU). The interinvestigator variability measurements for QMSCT-CA showed no significant differences.

CONCLUSION

QMSCT-CA systematically underestimates absolute coronary lumen- and vessel dimensions when compared with QCU. However, repeated measurements of coronary plaque by QMSCT-CA showed no statistically significant differences, although, the outcome showed a scattered result. Automated lumen detection for QMSCT-CA showed improved results when compared with those of human investigators.

Diagnostic Accuracy of Image Postprocessing Methods for the Detection of Coronary Artery Stenoses by Using Multidetector CT1

PURPOSE

To retrospectively evaluate the diagnostic accuracy of multidetector computed tomography (CT) coronary angiography for detection of hemodynamically significant (>or=50%) stenoses by using various image postprocessing methods, with conventional coronary angiography as the reference standard.

MATERIALS AND METHODS

The analysis used data from previous studies, use of which had been approved by the Institutional Review Board. Sixteen-section multidetector CT data sets for 40 patients (30 men, 10 women; mean age 56 years +/- 8; mean heart rate, 61 beats per minute +/- 6) were evaluated. Six independent investigators evaluated the data sets for the presence of stenoses with diameter reduction of 50% or more, by using either exclusively transverse images, free oblique multiplanar reconstructions (MPRs), free oblique maximum intensity projections (MIPs, 5 mm thick), prerendered curved MPRs, prerendered curved MIPs, or prerendered three-dimensional volume rendered reconstructions (VRTs). Evaluation results were compared with conventional coronary angiography for each artery in a blinded fashion (chi(2) test).

RESULTS

Overall, 35 coronary artery stenoses were present. Percentage of evaluable arteries and accuracy for detecting stenosis (percentages of accurately classified arteries were, respectively, 99% and 88% for transverse, 99% and 91% for oblique MPR, 94% and 86% for oblique MIP, 94% and 83% for curved MIP, 93% and 81% for curved MPR, and 91% and 73% for VRT). Accuracy was significantly higher for oblique MPR than for curved MPR (P=.01), curved MIP (P=.03), and VRT (P<.001).

CONCLUSION

The evaluation of multidetector CT coronary angiography with interactive image display methods, especially interactive oblique MPRs, permits higher diagnostic accuracy than evaluation of prerendered images (curved MPR, curved MIP, or VRT images).

Noninvasive detection of coronary artery stenosis with 16-slice spiral computed tomography in a population at low to moderate risk for coronary artery disease

OBJECTIVE

To evaluate the feasibility and accuracy of 16-slice spiral computed tomography (MSCT) in detecting coronary artery lesions in a low to moderate risk population.

METHODS

MSCT was performed in 33/78 patients at low to moderate risk for coronary artery disease affected by mitral and/or aortic valve disease and scheduled for conventional coronary angiography for pre-surgery evaluation. The sensitivity (SE), specificity (SP), positive (PPV) and negative predictive values (NPV) to identify >or=50% obstructed lesions were evaluated. Moreover, a discriminant predictive statistical analysis was performed.

RESULTS

MSCT visualised 428/479 (89%) segments identified at coronary angiography and the percentage of evaluable segments was 87%. By including all coronary branches, SE, SP, PPV and NPV were 69%, 96%, 58% and 97%, respectively. By excluding the segments with a diameter of <or=2 mm, SE and SP were 74% and 96%, respectively (MSCT correctly identified 17/23 lesions). In the evaluable coronary arteries, SE and SP were 86% and 88% for the left anterior descending coronary artery, 100% and 85% for the left circumflex coronary artery, and 86% and 89% for the right coronary artery, respectively. SP was 100% for the left main artery. When restricting the analysis to the patients, 22/23 patients were adequately evaluable, and SE, SP, PPV and NPV were 100%, 80%, 85% and 100%, respectively. Using the discriminant predictive statistical analysis of quantitative (age, heart rate and calcium score) and qualitative variables (presence or absence of critical lesions at MSCT), an overall accuracy of 85% was obtained.

CONCLUSIONS

The percentage of adequately evaluable patients was low because of limitations due to calcifications. In selected populations at low to moderate risk for coronary artery disease, MSCT has a high NPV in the evaluation of coronary artery stenosis.

Visual and automatic grading of coronary artery stenoses with 64-slice CT angiography in reference to invasive angiography

The aim of this study was to assess the performance of a software tool for quantitative coronary artery analysis of computed tomography coronary angiography (CT-QCA) in comparison with invasive coronary angiography with quantitative analysis (CAG-QCA) as standard of reference. Two radiologists reviewed the CT angiography data sets (Siemens Sensation 64) of 25 patients, grading coronary artery stenoses visually and with a software tool (Circulation, Siemens). Twenty-three data sets with sufficient image quality were included in the final analysis. CAG revealed a total of 30 wall irregularities and 28 stenoses, of which 17 were graded as moderate and nine as hemodynamically significant. CT-QCA showed a better agreement to CAG-QCA, with a systematic overestimation of the degree of stenosis of 6.1% and limits of agreement of +36.1% and -23.9; the correlation coefficient was 0.82 (p < 0.0001). Using CT-QCA, sensitivity, specificity, and positive and negative predictive value were 89%, 100%, 89%, and 100%, respectively, for significant area stenoses greater than 75%. The positive predictive value for the visual assessment amounted to 53%. Interobserver variability between CT-QCA and visual assessment showed a kappa value of 0.72. In conclusion, software-supported CT-QCA makes it possible to quantify significant coronary artery stenoses automatically, with good agreement to CAG-QCA.

Comparison of transaxial source images and 3-plane, thin-slab maximal intensity projection images for the diagnosis of coronary artery stenosis with using ECG-gated cardiac CT

Objective

We wanted to compare the transaxial source images with the optimized three plane, thin-slab maximum intensity projection (MIP) images from electrocardiographic (ECG)-gated cardiac CT for their ability to detect hemodynamically significant stenosis (HSS), and we did this by means of performing a receiver operating characteristic (ROC) analysis.

Materials and Methods

Twenty-eight patients with a heart rate less than 66 beats per minute and who were undergoing both retrospective ECG-gated cardiac CT and conventional coronary angiography were included in this study. The contrast-enhanced CT scans were obtained with a collimation of 16×0.75-mm and a rotation time of 420 msec. The transaxial images were reconstructed at the mid-diastolic phase with a 1-mm slice thickness and a 0.5-mm increment. Using the transaxial images, the slab MIP images were created with a 4-mm thickness and a 2-mm increment, and they covered the entire heart in the horizontal long axis (4 chamber view), in the vertical long axis (2 chamber view) and in the short axis. The transaxial images and MIP images were independently evaluated for their ability to detect HSS. Conventional coronary angiograms of the same study group served as the standard of reference. Four radiologists were requested to rank each image with using a five-point scale (1 = definitely negative, 2 = probably negative, 3 = indeterminate, 4 = probably positive, and 5 = definitely positive) for the presence of HSS; the data were then interpreted using ROC analysis.

Results

There was no statistical difference in the area under the ROC curve between transaxial images and MIP images for the detection of HSS (0.8375 and 0.8708, respectively; p > 0.05). The mean reading time for the transaxial source images and the MIP images was 116 and 126.5 minutes, respectively.

Conclusion

The diagnostic performance of the MIP images for detecting HSS of the coronary arteries is acceptable and this technique's ability to detect HSS is comparable to that of the transaxial source images.

Three-dimensional registration of myocardial perfusion SPECT and CT coronary angiography

OBJECTIVE

In this study, we describe a new technique for three-dimensional registration of CT coronary angiography (CTCA) and gated myocardial perfusion SPECT.

METHODS

Twelve patients with known or suspected CAD who underwent CTCA and gated SPECT were enrolled retrospectively. Coronary arteries and their branches were traced using CTCA data manually and reconstructed in three-dimensions. Gated SPECT data were registered and mapped to a left ventricle binary model extracted from CTCA data using manual, rigid and nonrigid registration methods.

RESULTS

Three-dimensional reconstruction and volume visualization of both modalities were successfully achieved for all patients. All 3 registration methods gave better quality based on visual inspection, and nonrigid registration gave significantly better results than the other registration methods (p < 0.05). The cost function for three-dimensional registration using nonrigid registration (235.3 +/- 13.9) was significantly better than those of manual and rigid registration (218.5 +/- 15.3 and 223.7 +/- 17.0, respectively). Inter-observer reproducibility error was within acceptable limits for all methods, and there were no significant difference among the methods.

CONCLUSION

This technique of image registration may assist the integration of information from gated SPECT and CTCA, and may have clinical application for the diagnosis of ischemic heart disease.

Comparison of measurement of cross-sectional coronary atherosclerotic plaque and vessel areas by 16-slice multidetector computed tomography versus intravascular ultrasound

In 26 patients, 16-slice multidetector computed tomography (MDCT) with 0.75-mm collimation and intravascular ultrasound (IVUS) of 1 coronary artery were performed. At 100 sites within the coronary arteries, the measurement of cross-sectional luminal area and, if detectable, the cross-sectional area of atherosclerotic plaque was performed independently with IVUS and MDCT. The mean luminal area (r = 0.92), measured at 100 sites, and plaque area (r = 0.55), measured at 65 sites, were significantly correlated (p <0.001) between MDCT and IVUS. The mean luminal area and mean plaque area were slightly but significantly overestimated with MDCT. MDCT permits the noninvasive measurement of coronary cross-sectional luminal and plaque areas with moderate accuracy.