Free-breathing coronary CT angiography using 16-cm wide-detector for challenging patients: comparison with invasive coronary angiography

Deep Learning-Based Motion Correction in Projection Domain for Coronary Computed Tomography Angiography: A Clinical Evaluation

OBJECTIVE

This study aimed to evaluate the clinical performance of a deep learning-based motion correction algorithm (MCA) in projection domain for coronary computed tomography angiography (CCTA).

METHODS

A total of 192 patients who underwent CCTA examinations were included and divided into 2 groups based on the average heart rate (HR): group 1, 82 patients with HR of <75 beats per minute; group 2, 110 patients with HR of ≥75 beats per minute. The CCTA images were reconstructed with and without MCA. The subjective image quality was graded in terms of vessel visualization, sharpness, diagnostic confidence, and overall image quality using a 5-point scale, where cases with all scores of ≥3 were deemed interpretable. Objective image quality was measured through signal-to-noise ratio and contrast-to-noise ratio in regions relative to the vessels. The image quality scores for 2 reconstructions and effective dose between 2 groups were compared.

RESULTS

The mean effective dose was similar between 2 groups. Neither group showed significant difference on objective image quality for 2 reconstructions. Images reconstructed with and without MCA were both found interpretable for group 1, whereas the subjective image quality was significantly improved by the MCA for all 4 metrics in group 2, with the interpretability increased from 80.91% to 99.09%. Compared with group 1, group 2 showed similar interpretability and diagnostic confidence, despite inferior overall image quality.

CONCLUSIONS

In CCTA examinations, the deep learning-based MCA is capable of improving the image quality and diagnostic confidence for patients with increased HR to a similar level as for those with low HR.

Influence of a new motion correction algorithm (CardioCapture) on the correlation between heart rate and optimal reconstruction phase

Purpose

To investigate the effect of a new motion correction algorithm (CardioCapture) on the correlation between heart rate and optimal reconstruction phase by evaluating the impact of wide detector CT combined with CardioCapture on CCTA image quality.

Materials and methods

All cases were examined from April 2021 to September 2021. Two experienced radiologists scored these images on a four-point Likert scale. First, all images were divided into eight groups according to HR (at an interval of 5 bpm). The subjective score of images, the frequency of used CardioCapture, and the proportion of the diastolic reconstruction phase were compared in each group. Then, all cases were divided into two groups, one group was reconstructed using the automatic temporal reconstruction algorithm (Ephase) only, and the other group was reconstructed using the Ephase with the CardioCapture. The relationship between HR and the diastolic reconstruction phase was analyzed by the receiver operator characteristic curve (ROC).

Result

The data of 515 patients were studied. With the increase in HR, the subjective image score decreased, the frequency of CardioCapture increased, and the phase ratio of diastolic reconstruction decreased. When the HR was less than 70 bpm, the percentage of excellence image in each group surpassed 94.90%. The highest utilization rate of CardioCapture was 65.22%, and the lowest proportion of diastolic reconstruction was 72.46%. When 70 bpm < HR ≤ 75 bpm, the image excellence rate was 90.43%, the CardioCapture utilization rate was 82.05%, and the diastolic reconstruction rate was 56.41%.When 75 bpm < HR ≤ 80 bpm, the image excellence rate was 87.91%, the CardioCapture utilization rate was 80.65%, and the diastolic reconstruction was 6.45%.When the HR > 80 bpm, the image excellence rate was 80.00%, the CardioCapture utilization rate was 75.00%, and the diastolic reconstruction rate was 22.50%. The best cut-off point between HR and the diastolic reconstruction ROC curve in the groups without CardioCapture was 65 bpm, while that in groups with CardioCapture was 68 bpm.

Conclusion

The CardioCapture can effectively improve the image quality of CCTA with high HR. By maintaining the HR below 68 bpm and utilizing the prospective ECG-gated narrow phase axial scan, it is possible to ensure optimal image quality and concurrently reduce radiation dose.

Intraindividual evaluation of effects of image filter function on image quality in coronary computed tomography angiography

Objectives

To evaluate whether applying image filters (smooth 3D+ and edge-2) improves image quality in coronary CT angiography (CCTA).

Methods

Ninety patients (routine group) with suspected coronary artery diseases based on 16-cm wide coverage detector CT findings were retrospectively enrolled at a chest pain center from December 2019 to September 2021. Two image filters, smooth 3D+ and edge-2 available on the Advantage Workstation (AW) were subsequently applied to the images to generate the research group (SE group). Quantitative parameters, including CT value, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), image sharpness and image quality score, and diagnostic accuracy were compared between the two groups.

Results

A total of 900 segments from 270 coronary arteries in 90 patients were analyzed. SNR, CNR, and image sharpness for vessels and image quality scores in the SE group were significantly better than those in the routine group (all p < 0.001). The SE group showed a slightly higher negative predictive value (NPV) on the left anterior descending artery and right coronary artery (RCA) stenosis evaluations, as well as total NPV. The SE group also showed slightly higher sensitivity and accuracy than the routine group on RCA stenosis evaluation.

Conclusion

The use of an image filter combining smooth 3D+ and edge-2 on an AW could improve the image quality of CCTA and increase radiologists' diagnostic confidence.

Automatic vs manual coronary CT angiography reconstruction for whole-heart coverage CT scanner: a comparison study in general patient population

BACKGROUND

Due to the limited temporal resolution and cardiac motion, coronary computed tomography angiography (CCTA) exam is one of the most challenging CT protocols which may require operating radiologist to apply additional phase adjustment or motion correction for image reconstruction.

OBJECTIVE

To evaluate image quality between automatic and manual CCTA reconstruction in a 0.25 second rotation time, 16 cm coverage, single-beat, CT scanner with automated phase selection and AI-assisted motion correction.

METHODS

CCTA exams of 535 consecutive patients were included. All exams were first reconstructed with an automatically selected phase. If there was an unacceptable motion artifact, a manual reconstruction process was performed by radiologists. Additionally, automatic image series which consist of auto-phase selection and a follow-up motion correction were reconstructed. For these two manual and automatic image series, a four-point Likert scale rating system was used to evaluate image quality of the coronary artery segment by two experienced radiologists, according to the 18-segment model.

RESULTS

Fifty-one patients (9.5%) did not have satisfactory image quality after auto-phase selection. In these patients, the heart rate during scanning was higher (78.3±18.4 bpm) than in the remaining 484 patients (68.9±13.1 bpm). Overall, 734 out of the 918 vessel segments were identified for quality evaluation among 51 patients. Automatic and manual image series were rated as having average Likert scores of 3.48±0.62 and 3.32±0.67 (P < 0.001), respectively.

CONCLUSIONS

Using a 0.25 second rotation speed, 16 cm z-coverage, CT scanner installed with an AI-assisted motion correction algorithm, the automatic image reconstruction with scanner equipped auto-phase-selection and motion correction algorithm outperforms manually controlled image reconstruction by radiologists. This suggests that the traditional CCTA exam reconstruction workflow could be altered allowing less radiologist involvement and becoming more efficient.

Combined Coronary CT Angiography and Evaluation of Access Vessels for TAVR Patients in Free-Breathing with Single Contrast Medium Injection Using a 16-cm-Wide Detector CT

RATIONALE AND OBJECTIVES

To investigate the feasibility of combining coronary computed tomography (CT) angiography (CCTA) and CTA to evaluate access vessels for transcatheter aortic valve replacement (TAVR) patients in free-breathing and with single contrast medium injection using a 16-cm-wide detector CT.

MATERIALS AND METHODS

One hundred and twenty-one consecutive patients (73.33 ± 6.43 years) referred for TAVR underwent a serious CT scans in free-breathing after one contrast injection: ECG-triggered one-heartbeat axial CCTA, followed by non-ECG-gated neck, thoracic, and abdominal CTA. Patient weight-dependent contrast dose volume at 1.0 mL/kg was used. CT attenuation values of the coronary, neck, aortic, iliac, and femoral arteries were measured and their image quality was evaluated with a 4-point score method. Stenosis (≥50%) in CCTA was evaluated using invasive coronary angiography result as a reference standard. Radiation and contrast doses were assessed.

RESULTS

The total dose-length-product for the entire examination was 411.4 ± 91.2 mGy.cm, and the total contrast dose was 57.3 ± 9.9 mL. There were adequate attenuations (>400 HU) in all arteries, and the peripheral access vessels and aortic annulus were evaluable in all patients. In neck CTA, 5 patients had vascular tortuosity, 6 patients had aberrant arteries and there were 212 plaques and 13 severe stenoses among the patients. In CCTA, on the per-segment, per-vessel, and per-patient analysis, CCTA showed a sensitivity and negative predictive value of (95% and 99%), (95% and 99%), and (96% and 98%), respectively, for the entire patient cohort, and (92% and 98%), (92% and 98%), and (88% and 93%), respectively, for patients with atrial fibrillation or heart rate higher than 75 beats.

CONCLUSION

It is feasible to perform a combined CCTA and CTA for evaluating access vessels for TAVR patients in free-breathing with single contrast injection. This approach generates acceptable image quality for all vessels and a high negative predictive value in excluding coronary artery disease with relatively low radiation and contrast doses.

Image quality and diagnostic performance evaluation in transcatheter aortic valve implantation candidates with atrial fibrillation using a whole-heart coverage CT scanner

OBJECTIVE

To evaluate the image quality and diagnostic performance for obstructive coronary artery disease of transcatheter aortic valve implantation (TAVI) patients with atrial fibrillation (AF) during TAVI planning CT using a whole-heart coverage CT scanner.

METHODS

Eighty-eight consecutive TAVI candidates with AF (50 men, 74 ± 6 years) who underwent both TAVI planning CT and invasive coronary catheter angiography (ICA) were retrospectively analyzed. With ICA results as the reference standard, the accuracy of TAVI planning CT for lesion detection on a per-vessel and per-patient level was calculated. Meanwhile, image quality, contrast volume, and effective dose (ED) were evaluated. A 5-point visual scale (1-5) was used to assess the subjective image quality. The CT value and signal-to-noise ratio were measured for the left main coronary artery (LM), left anterior descending (LAD), left circumflex (LCX), and right coronary arteries (RCA).

RESULTS

The ED for CCTA was 3.25 ± 1.39 mSv and contrast volume was 58.14 ± 12.34 mL. A total of 1371 (1371/1408 = 97.4%) segments with diameter > 1.5 mm were analyzed. For the subjective evaluation, the mean score was 3.99 ± 0.96 for overall image quality. The mean CT values in LM, RCA, LCX, and LAD were all above 400 HU. For the detection of > 50% stenosis, TAVI planning CT provided on the per-vessel and per-patient basis 97.06% and 100% in sensitivity, 96.23% and 89.06% in specificity, 99.7% and 100% in negative predictive value, and 73.3% and 77.4% in positive predictive value, respectively.

CONCLUSION

TAVI planning CT with whole-heart coverage demonstrates good CCTA image quality and a high sensitivity and NPV in excluding obstructive CAD in TAVI candidates with AF.

KEY POINTS

• Transcatheter aortic valve implantation planning (TAVI) CT with whole-heart coverage enables good image quality of CCTA in TAVI candidates with atrial fibrillation. • Obstructive coronary artery disease may be excluded with high accuracy in transcatheter aortic valve implantation (TAVI) candidates with atrial fibrillation with the usage of whole-heart coverage TAVI planning CT.

Image quality of automatic coronary CT angiography reconstruction for patients with HR ≥ 75 bpm using an AI-assisted 16-cm z-coverage CT scanner

Background

Coronary CT angiography (CCTA) is a complicated CT exam in comparison to other CT protocols. Exam success highly depends on image assessment of experienced radiologist and the procedure is often time-consuming. This study aims to evaluate feasibility of automatic CCTA reconstruction in 0.25 s rotation time, 16 cm coverage CT scanner with best phase selection and AI-assisted motion correction.

Methods

CCTA exams of 90 patients with heart rates higher than 75 bpm were included in this study. Two image series were reconstructed—one at automatically selected phase and another with additional motion correction. All reconstructions were performed without manual interaction of radiologist. A four-point Likert scale rating system was used to evaluate the image quality of coronary artery segment by two experienced radiologists, according to the 18-segment model. Analysis was done on per-segment basis.

Results

Total 1194 out of the 1620 segments were identified for quality evaluation in 90 patients. After automatic best phase selection, 1172 segments (98.3%) were rated as having diagnostic image quality (scores 2–4) and the average score is 3.64 ± 0.55. When motion corrections were applied, diagnostic segment number increases to 1192 (99.8%) and the average score is 3.85 ± 0.37.

Conclusions

With the help of 0.25 s rotation speed, 16-cm z-coverage and AI-assisted motion correction algorithm, CCTA exam reconstruction could be performed with minimum radiologist involvement and still meet image quality requirement.

Impact of respiratory motion artifact on coronary image quality of one beat coronary CT angiography

BACKGROUND

Accuracy of CT-derived fractional flow reserve depends on good image quality. Thus, improving image quality during coronary CT angiography (CCTA) is important.

OBJECTIVE

To investigate impact of respiratory motion artifact on coronary image quality focusing on vessel diameter and territory during one beat CCTA by a 256-row detector.

METHODS

We retrospectively reviewed patients who underwent CCTA under free-breathing (n = 100) and breath-holding (n = 100), respectively. Coronary image quality is defined as 4-1 from excellent to poor (non-diagnostic) and respiratory motion artifact severity is also scored on a 4-point scale from no artifact to severe artifact. Coronary image quality and respiratory motion artifact severity of all images were evaluated by two radiologists independently.

RESULTS

Compared with free-breathing group, the image qualities are significantly higher in per-segment, per-vessel and per-patient levels (P < 0.001) and proportion of segments with excellent image quality also improves significantly (73.6% vs 60.1%, P < 0.001) in breath-holding group. The image quality improvement occurs in medium-sized coronary arterial segments. Coronary image quality improves with respiratory motion artifacts decreasing in both groups, respectively.

CONCLUSION

During one heartbeat CCTA, breath-holding is still recommended to improve coronary image quality due to improvement of the image quality in the medium-sized coronary arteries.