Feasibility of a single-beat prospective ECG-gated cardiac CT for comprehensive evaluation of aortic valve disease using a 256-detector row wide-volume CT scanner: an initial experience

New Whole-Heart motion correction algorithm enables diagnostic CT of aortic valve and coronary arteries in systolic phase for transcatheter aortic valve implantation candidates

OBJECTIVES

To investigate the ability of new generation snapshot freeze (NGSSF) algorithm in improving diagnostic image quality of both aortic valve and coronary arteries for transcatheter aortic valve implantation (TAVI) candidates in TAVI planning CT.

METHODS

Sixty-four TAVI candidates underwent TAVI planning CT were enrolled. Scans from coronary CT angiography were reconstructed at 20%, 30%, 40%, and 75% R-R cardiac phases with NGSSF and standard (STD) algorithm. In each phase, following parameters were compared: aortic valve measurements and their reproducibility; image quality of aortic valve and coronary arteries. The diagnostic accuracies of TAVI planning CT for coronary artery stenosis in 30% R-R phase with NGSSF and STD algorithms were calculated in 47out of 64 patients with invasive coronary angiography as reference standard.

RESULTS

For subjective image quality evaluation, the excellent rate for aortic valve improved from 25.0% to 93.8% and the interpretable rate for coronary arteries increased from 20.3% to 95.3% in the 30% phase images with NGSSF compared with images with STD. For the detection of > 50% coronary artery stenosis, the 30% phase images with NGSSF provided a sensitivity of 90%, specificity of 81.48%, negative predictive value of 91.7%, and positive predictive value of 78.3% on a per-patient basis; While images with STD, had a corresponding results of 95.0%, 33.33%, 90.0%, and 51.4%, respectively.

CONCLUSIONS

NGSSF significantly improves image quality for both aortic valve and coronary arteries compared with STD for TAVI patients of all heart rates. NGSSF enables the accurate measurement for aortic valve and satisfactory diagnostic performance for coronary arteries stenosis in the same systolic phase for TAVI planning.

Optimal end-systolic cardiac phase prediction for low-dose ECG-synchronized cardiac CT

PURPOSE

To predict optimal end-systolic (ES) cardiac phase for low-dose ECG-synchronized cardiac computed tomography (CT).

MATERIALS AND METHODS

ECG-synchronized ES cardiac CT examinations of 2441 patients from September 2010 to December 2016 were reviewed. Of them, 891 examinations acquired with an extended period of full tube current in a cardiac cycle (i.e., 10 % of RR interval or ≥100 ms) and adequate image quality (median patient age, 7 years; age range, 0 day‒60 years) were included. Absolute and relative delays (n = 861 and n = 30, respectively) of the cardiac CT were correlated with the heart rates. Best-fit equations were developed from the trend line with the highest coefficient of determination (R²) value for the two delays, and their success rates to obtain optimal ES phase in a padding with full tube current were calculated and compared with that of the T wave location method. CT radiation dose ratio was calculated as a width ratio of paddings with full tube current.

RESULTS

The absolute and relative delays in the Pearson correlation test demonstrated a strong negative correlation (R = -0.9, p < 0.001) and a nearly moderate positive correlation (R = 0.5, p < 0.001) with heart rates, respectively. Two best-fit equations could be developed separately for both relative (R² = 0.3) and absolute delays (R² = 0.8). When adjusting the period of full tube current to a 114 ms for absolute delay and a 17.4 % of RR interval for relative delay, success rates of 94.9 % and 95.1 %, respectively, could be achieved and were significantly higher than that determined by the T wave location (82.7 %, p <  0.001).

CONCLUSION

The best-fit equations method has a higher success rate for predicting the optimal end-systolic phase of ECG-synchronized cardiac CT than the T wave location method.

Chest CT Angiography for Acute Aortic Pathologic Conditions: Pearls and Pitfalls

Chest CT angiography (CTA) is essential in the diagnosis of acute aortic syndromes. Chest CTA quality can be optimized with attention to technical parameters pertaining to noncontrast imaging, timing of contrast-enhanced imaging, contrast material volume, kilovolt potential, tube-current modulation, and decisions regarding electrocardiographic-gating and ultra-fast imaging, which may affect the accurate diagnosis of acute aortic syndromes. An understanding of methods to apply to address suboptimal image quality is useful, as the accurate identification of acute aortic syndromes is essential for appropriate patient management. Acute aortic syndromes have high morbidity and mortality, particularly when involving the ascending aorta, and include classic aortic dissection, penetrating atherosclerotic ulcer, and acute intramural hematoma. An understanding of the pathogenesis and distinguishing imaging features of acute aortic syndromes and aortic rupture and some less common manifestations is helpful when interpreting imaging examinations. Related entities, such as ulcerated plaque, ulcerlike projections, and intramural blood pools, and mimics, such as vasculitis and aortic thrombus, are important to recognize; knowledge of these is important to avoid interpretive pitfalls. In addition, an awareness of postsurgical aortic changes can be useful when interpreting CTA examinations when patient history is incomplete. The authors review technical considerations when performing CTA, discuss acute aortic syndromes, and highlight diagnostic challenges encountered when interpreting aortic CTA examinations. ^©RSNA, 2021.

Value of Computed Tomography Radiomic Features for Differentiation of Periprosthetic Mass in Patients With Suspected Prosthetic Valve Obstruction

Background:

We aimed to determine whether quantitative computed tomography radiomic features can aid in differentiating between the causes of prosthetic valve obstruction (PVO) in patients who had undergone prosthetic valve replacement.

Methods:

This retrospective study included 39 periprosthetic masses in 34 patients who underwent cardiac computed tomography scan from January 2014 to August 2017 and were clinically suspected as PVO. The cause of PVO was assessed by redo-surgery and follow-up imaging as standard reference, and classified as pannus, thrombus, or vegetation. Visual analysis was performed to assess the possible cause of PVO on axial and valve-dedicated views. Computed tomography radiomic analysis of periprosthetic masses was performed and radiomic features were extracted. The advantage of radiomic score compared with visual analysis for differentiation of pannus from other abnormalities was assessed.

Results:

Of 39 masses, there were 20 cases of pannus, 11 of thrombus, and 8 of vegetation on final diagnosis. The radiomic score was significantly higher in the pannus group compared with nonpannus group (mean, −0.156±0.422 versus −0.883±0.474; P <0.001). The area under the curve of radiomic score for diagnosis of pannus was 0.876 (95% CI, 0.731–0.960). Combination of radiomic score and visual analysis showed a better performance for the differentiation of pannus than visual analysis alone.

Conclusions:

Compared with visual analysis, computed tomography radiomic features may have added value for differentiating pannus from thrombus or vegetation in patients with suspected PVO.