Feasibility of low radiation dose retrospectively-gated cardiac CT for functional analysis in adult congenital heart disease

Low dose threshold for measuring cardiac functional metrics using four-dimensional CT with deep learning

BACKGROUND

Four-dimensional CT is increasingly used for functional cardiac imaging, including prognosis for conditions such as heart failure and post myocardial infarction. However, radiation dose from an acquisition spanning the full cardiac cycle remains a concern. This work investigates the possibility of dose reduction in 4DCT using deep learning (DL)-based segmentation techniques as an objective observer.

METHODS

A 3D residual U-Net was developed for segmentation of left ventricle (LV) myocardium and blood pool. Two networks were trained: Standard DL (trained with only standard-dose [SD] data) and Noise-Robust DL (additionally trained with low-dose data). The primary goal of the proposed DL methods is to serve as an unbiased and consistent observer for functional analysis performance. Functional cardiac metrics including ejection fraction (EF), global longitudinal strain (GLS), circumferential strain (CS), and wall thickness (WT), were measured for an external test set of 250 Cardiac CT volumes reconstructed at five different dose levels.

RESULTS

Functional metrics obtained from DL segmentations of standard dose images matched well with those from expert manual analysis. Utilizing Standard-DL, absolute difference between DL-derived metrics obtained with standard dose data and 100 mA (corresponding to ∼76 ± 13% dose reduction) data was less than 0.8 ± 1.0% for EF, GLS, and CS, and 5.6 ± 6.7% for Average WT. Performance variation of Noise-Robust DL remained acceptable at even 50 mA.

CONCLUSION

We demonstrate that on average radiation dose can be reduced by a factor of 5 while introducing minimal changes to global functional metrics (especially EF, GLS, and CS). The robustness to reduced image quality can be further boosted by using emulated low-dose data in the DL training set.

Minimal dose CT for left ventricular ejection fraction and combination with chest-abdomen-pelvis CT

Objectives

This prospective study tested the diagnostic accuracy, and absolute agreement with MRI of a low-dose CT protocol for left ventricular ejection fraction (LVEF) measurement. Furthermore we assessed its potential for combining it with Chest-Abdomen-Pelvis CT (CAP-CT) for a one-stop examination.

Materials & methods

Eighty-two patients underwent helical low-dose CT. Cardiac magnetic resonance imaging (MRI) was the reference standard. In fifty patients, CAP-CT was performed concurrently, using a modified injection protocol. In these, LVEF was measured with radioisotope cardiography (MUGA). Patients >18 years, without contrast media or MRI contraindications, were included. Bias was measured with Bland-Altman analysis, classification accuracy with Receiver Operating Characteristics, and inter-reader agreement with Intra-Class Correlation Coefficient (ICC). Correlation was examined using Pearson's correlation coefficients. CAP image quality was compared to previous scans with visual grading characteristics.

Results

The mean CT dose-length-product (DLP) was 51.8 mGycm, for an estimated effective dose of 1.4 mSv, compared to 5.7 mSv for MUGA. CT LVEF bias was between 2 % and 10 %, overestimating end-diastolic volume. When corrected for bias, sensitivity and specificity of 100 and 98.5 % for classifying reduced LVEF (50 % MRI value) was achieved. ICC for MUGA was significantly lower than MRI and CT. Distinction of renal medulla and cortex was reduced in the CAP scan, but proportion of diagnostic scans was not significantly different from standard protocol.

Conclusion

When corrected for inter-modality bias, CT classifies patients with reduced LVEF with high accuracy at a quarter of MUGA dose and can be combined with CAP-CT without loss of diagnostic quality.

Correlation between morphological parameters and dosimetric parameters of the heart and spinal cord in the intermediate- and advanced-stage esophageal cancer

BACKGROUND

Radiation therapy plays a pivotal role as the primary adjuvant treatment for esophageal cancer (EPC), emphasizing the critical importance of carefully balancing radiation doses to the target area and organs at risk in the radiotherapeutic management of esophageal cancer.

AIMS

This study aimed to explore the correlation between morphological parameters and dosimetric parameters of the heart and spinal cord in intermediate- and advanced-stage esophagus cancer to provide a reference for clinical treatment.

METHODS AND RESULTS

A total of 105 patients with intermediate- and advanced-stage EPC, who received treatment in our hospital from 2019 to 2021, were included. The morphological parameters were calculated by imaging. Intensity-modulated radiation therapy plan was executed at Raystation4.7. The PTV-G stood for the externally expanded planning target volume (PTV) of the gross tumor volume (GTV) and PTV-C for the externally expanded volume of the clinical target volume (CTV). The prescription dose of PTV-G and PTV-C was set as 60Gy/30F and 54Gy/30F, respectively. The linear regression model was used to analyze the correlation between morphologic parameters of EPC and dosimetric parameters of the heart and spinal cord. In 105 cases, the total lung length was correlated with the spinal cord maximum dose (D2 ). The heart mean doses (Dmean ) and heart V40 (the relative volume that receives 40 Gy or more) was correlated with PTV-G volume, PTV-G length; In middle- and upper-segment EPC cases, only the total lung volume was correlated with the spinal cord Dmean , spinal cord D2 , heart Dmean , and heart V40 ; In middle-stage EPC cases, the heart Dmean was correlated with the PTV-G volume, PTV-G length. The total lung length was correlated with the spinal cord D2 ; In middle- and lower-segment EPC, only the PTV-G volume and PTV-G length were correlated with the heart Dmean . All the aforementioned values were statistically significant.

CONCLUSIONS

Combined with the unsegmented tumor and different locations, the organ at risk dose was comprehensively considered.

Potential for Dose Reduction in CT-Derived Left Ventricular Ejection Fraction: A Simulation Study

BACKGROUND

Measuring left ventricular ejection fraction (LVEF) is important for detecting heart failure, e.g., in treatment with potentially cardiotoxic chemotherapy. MRI is considered the reference standard for LVEF, but availability may be limited and claustrophobia or metal implants still present challenges. CT has been shown to be accurate and would be advantageous, as LVEF could be measured in conjunction with routine chest-abdomen-pelvis oncology CT. However, the use of CT is not recommended due to the excessive radiation dose. This study aimed to explore the potential for dose reduction using simulation. Using an anthropomorphic heart phantom scanned at 13 dose levels, a noise simulation algorithm was developed to introduce controlled Poisson noise. Filtered backprojection parameters were iteratively tested to minimise differences in myocardium-to-ventricle contrast/noise ratio, as well as structural similarity index (SSIM) differences between real and simulated images at all dose levels. Fifty-one clinical CT coronary angiographies, scanned with full dose through end-systolic and -diastolic phases, were located retrospectively. Using the developed algorithm, noise was introduced corresponding to 25, 10, 5 and 2% of the original dose level. LVEF was measured using clinical software (Syngo.via VB50) with papillary muscles in and excluded from the LV volume. At each dose level, LVEF was compared to the 100% dose level, using Bland-Altman analysis. The effective dose was calculated from DLP using a conversion factor of 0.026 mSv/mGycm.

RESULTS

In the clinical images, mean CTDIvol and DLP were 47.1 mGy and 771.9 mGycm, respectively (effective dose 20.0 mSv). Measurements with papillary muscles excluded did not exhibit statistically significant LVEF bias to full-dose images at 25, 10 and 5% simulated dose. At 2% dose, a significant bias of 4.4% was found. With papillary muscles included, small but significant biases were found at all simulated dose levels.

CONCLUSION

Provided that measurements are performed with papillary muscles excluded from the LV volume, the dose can be reduced by a factor of 20 without significantly affecting LVEF measurements. This corresponds to an effective dose of 1 mSv. CT can potentially be used for LVEF measurement with minimal excessive radiation.

Preoperative Computed Tomography Assessment of Risk of Right Ventricle Failure After Left Ventricular Assist Device Placement

Identification of patients who are at a high risk for right ventricular failure (RVF) after left ventricular assist device (LVAD) implantation is of critical importance. Conventional tools for predicting RVF, including two-dimensional echocardiography, right heart catheterization (RHC), and clinical parameters, generally have limited sensitivity and specificity. We retrospectively examined the ability of computed tomography (CT) ventricular volume measures to identify patients who experienced RVF after LVAD implantation. Between September 2017 and November 2021, 92 patients underwent LVAD surgery at our institution. Preoperative CT-derived ventricular volumes were obtained in 20 patients. Patients who underwent CT evaluation had a similar demographics and rate of RVF after LVAD as patients who did not undergo cardiac CT imaging. In the study cohort, seven of 20 (35%) patients experienced RVF (2 unplanned biventricular assist device, 5 prolonged inotropic support). Computed tomography-derived right ventricular end-diastolic and end-systolic volume indices were the strongest predictors of RVF compared with demographic, echocardiographic, and RHC data with areas under the receiver operating curve of 0.79 and 0.76, respectively. Computed tomography volumetric assessment of RV size can be performed in patients evaluated for LVAD treatment. RV measures of size provide a promising means of pre-LVAD assessment for postoperative RV failure.

Detector-trigger-based cardiac multiphase micro-CT imaging for small animals

BACKGROUND

Micro-computed tomography is important in cardiac imaging for preclinical small animal models, but motion artifacts may appear due to the rapid heart rates. To avoid influence of motion artifacts, the prospective ECG gating schemes based on an X-ray source trigger have been investigated. However, due to the lack of pulsed X-ray exposure modes, high-resolution micro-focus X-ray sources do not support source triggering in most cases.

OBJECTIVE

To develop a fast-cardiac multiphase acquisition strategy using prospective ECG gating for micro-focus X-ray tubes with a continuous emission mode.

METHODS

The proposed detector-trigger-based prospective ECG gating acquisition scheme (DTB-PG) triggers the X-ray detector at the R peak of ECG, and then collects multiple phase projections of the heart in one ECG cycle by sequence acquisition. Cardiac multiphase images are reconstructed after performing the same acquisition in all views. The feasibility of this strategy was verified in multiphase imaging experiments of a phantom with 150 ms motion period and a mouse heart on a micro-focus micro-CT system with continuous emission mode.

RESULTS

Using a high frame-rate CMOS detector, DTB-PG discriminates the positions of the motion phantom well in 10 different phases and enables to distinguish the changes in the cardiac volume of the mouse in different phases. The acquisition rate of DTB-PG is much faster than other prospective gating schemes as demonstrated by theoretical analysis.

CONCLUSIONS

DTB-PG combines the advantages of prospective ECG gating strategies and X-ray detector-trigger mode to suppress motion artifacts, achieve ultra-fast acquisition rates, and relax hardware limitations.

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.

CT Angiography or Cardiac MRI for Detection of Coronary Artery Aneurysms in Kawasaki Disease

Background: Kawasaki disease (KD) is an acute vasculitis that mainly affects the coronary arteries. This inflammation can cause coronary artery aneurysms (CAAs). Patients with KD need cardiac assessment for risk stratification for the development of myocardial ischemia, based on Z-score (luminal diameter of the coronary artery corrected for body surface area). Echocardiography is the primary imaging modality in KD but has several important limitations. Coronary computed tomographic angiography (cCTA) and Cardiac MRI (CMR) are non-invasive imaging modalities and of additional value for assessment of CAAs with a high diagnostic yield. The objective of this single center, retrospective study is to explore the diagnostic potential of coronary artery assessment of cCTA vs. CMR in children with KD. Methods and Results: Out of 965 KD patients from our database, a total of 111 cCTAs (104 patients) and 311 CMR (225 patients) have been performed since 2010. For comparison, we identified 54 KD patients who had undergone both cCTA and CMR. CMR only identified eight patients with CAAs compared to 14 patients by cCTA. CMR missed 50% of the CAAs identified by cCTA. Conclusions: Our single center study demonstrates that cCTA may be a more sensitive diagnostic tool to detect CAAs in KD patients, compared to CMR.

Cardiac cine CT approaching 1 mSv: implementation and assessment of a 58-ms temporal resolution protocol

Clinical use of cardiac cine CT imaging is limited by high radiation dose and low temporal resolution. To evaluate a low radiation dose, high temporal resolution cardiac cine CT protocol in human cardiac CT and phantom scans. CT scans of a circulating iodine target were reconstructed using the conventional single heartbeat half-scan (HS, approx. 175 ms temporal resolution) and the 3-heartbeat multi-segment (MS, approx. 58 ms) algorithms. Motion artifacts were quantified by the root-mean-square error (RMSE). Low-dose cardiac cine CT scans were performed in 55 subjects at a tube potential of 80 kVp and current of 80 mA. Image quality of HS and MS scans was assessed by blinded reader quality assessment, left ventricular (LV) free wall motion, and LV ejection rate. Motion artifacts in phantom scans were higher in HS than in MS reconstructions (RSME 188 and 117 HU, respectively; p = 0.001). Median radiation dose in human scans was 1.2 mSv. LV late diastolic filling was observed more frequently in MS than in HS images (42 vs. 26 subjects, respectively; p < 0.001). LV free wall systolic motion was more physiologic and had less error in MS than in HS reconstructions (sum-of-squared errors 34 vs. 45 mm², respectively; p < 0.001), and LV peak ejection rate was higher in MS than in HS reconstructions (166 vs. 152 mL/s, respectively; p < 0.001). Cardiac cine CT imaging is feasible at a low radiation dose of 1.2 mSv. MS reconstruction showed improved imaging of rapid motion in phantom studies and human cardiac CTs.

Imaging of complications following Fontan circulation in children - diagnosis and surveillance

The Fontan operation is performed for various cardiac lesions with single-ventricle physiology. The survival rate of Fontan patients is increasing for adolescents and young adults, with an expected 30-year survival of >80%. Medical health care providers including specialists in organ systems and pediatric radiologists need to improve their knowledge about the Fontan circulation and the various organ complications to monitor care. In this review the author explains the basic anatomical and functional features of Fontan palliation and gives an overview of the multiple long-term organ complications that might present in the pediatric population. These include decreased physical capacity, ventricular dysfunction, atrioventricular valve regurgitation and arrhythmia, as well as protein-losing enteropathy, plastic bronchitis, growth/bone composition disturbances, renal dysfunction, and the recently recognized and important liver fibrosis (Fontan-associated liver disease). Neuropsychological and behavioral deficits occur frequently. This review focuses on the key role of radiology in making the diagnosis of these complications, monitoring therapy and predicting outcomes in the pediatric age group. The author discusses how and when radiology is important in Fontan patients, as well as how new techniques enabling quantitative measures in imaging with US, MRI and CT are adapted for pediatric use, and how they contribute to urgently needed surveillance strategies.

Assessment of intracardiac and extracardiac anomalies associated with coarctation of aorta and interrupted aortic arch using dual-source computed tomography

To evaluate the value of dual-source computed tomography (DSCT) compared with transthoracic echocardiography (TTE) in assessing intracardiac and extracardiac anomalies in patients with coarctation of aorta (CoA) and interrupted aortic arch (IAA). Seventy-five patients (63 with CoA and 12 with IAA) who received preoperative DSCT and TTE were retrospectively studied. Intracardiac and extracardiac anomalies were recorded and compared by DSCT and TTE, in reference to surgical or cardiac catheterization findings. A total of 155 associated anomalies were finally found. Collateral circulation (56, 74.70%), patent ductus arteriosus (PDA; 41, 54.67%) were the most common anomalies. PDA, aortopulmonary window, and collateral circulation were more frequently present in patients with IAA than those with CoA (100% vs. 46.03%, 16.67% vs. 0%, and 100% vs. 69.84%, respectively, all p < 0.05). DSCT was superior to TTE in assessing associated extracardiac-vascular anomalies (sensitivity: 100% vs. 39.81%; specificity: 100% vs. 100%; positive predictive value: 100% vs. 100%; negative predictive value: 100% vs. 76.06%). Extracardiac-vascular anomalies, including collateral circulation and PDA, were the most common anomalies in patients with IAA and CoA. Compared with TTE, DSCT is more reliable in providing an overall preoperative evaluation of morphological features and extracardiac anomalies for surgical planning.

Chest CT Scan at Radiation Dose of a Posteroanterior and Lateral Chest Radiograph Series: A Proof of Principle in Lymphangioleiomyomatosis

BACKGROUND

Given the rising utilization of medical imaging and the risks of radiation, there is increased interest in reducing radiation exposure. The objective of this study was to evaluate, as a proof of principle, CT scans performed at radiation doses equivalent to that of a posteroanterior and lateral chest radiograph series in the cystic lung disease lymphangioleiomyomatosis (LAM).

METHODS

From November 2016 to May 2018, 105 consecutive subjects with LAM received chest CT scans at standard and ultra-low radiation doses. Standard and ultra-low-dose images, respectively, were reconstructed with routine iterative and newer model-based iterative reconstruction. LAM severity can be quantified as cyst score (percentage of lung occupied by cysts), an ideal benchmark for validating CT scans performed at a reduced dose compared with a standard dose. Cyst scores were quantified using semi-automated software and evaluated by linear correlation and Bland-Altman analysis.

RESULTS

Overall, ultra-low-dose CT scans represented a 96% dose reduction, with a median dose equivalent to 1 vs 22 posteroanterior and lateral chest radiograph series (0.14 mSv; 5th-95th percentile, 0.10-0.20 vs standard dose 3.4 mSv; 5th-95th percentile, 1.5-7.4; P < .0001). The mean difference in cyst scores between ultra-low- and standard-dose CT scans was 1.1% ± 2.0%, with a relative difference in cyst score of 11%. Linear correlation coefficient was excellent at 0.97 (P < .0001).

CONCLUSIONS

In LAM chest CT scan at substantial radiation reduction to doses equivalent to that of a posteroanterior and lateral chest radiograph series provides cyst score quantification similar to that of standard-dose CT scan.

TRIAL REGISTRY

ClinicalTrials.gov; Nos.: NCT00001465 and NCT00001532; URL: www.clinicaltrials.gov.

Predictors of aortic dilation in patients with coarctation of the aorta: evaluation with dual-source computed tomography

BACKGROUND

Coarctation of aorta (CoA) may progressively develop aortic dilation at other site of the aorta and can lead to fatal aortic diseases. We aimed to evaluate the occurrence of aortic dilation and related predictors in patients with CoA using dual-source computed tomography (DSCT).

METHODS

Fifty-three patients with CoA identified by DSCT were retrospectively reviewed. Aortic diameters were measured at six different levels and standardized as z-scores based on the square root of body surface area. Coarctation site-diaphragm ratio (CDR) was used to describe the degree of narrowing. A total of 26 patients were included in mild group (CDR > 50%) and 27 in severe group (CDR < 50%) according to the severity of coarctation. Student's t-test and Spearman correlation coefficients, univariate and multivariable logistic regression analyses were used to assess the risk factors including age, degree of narrowing and other malformations for aortic dilation.

RESULTS

Severe group had significantly larger z-scores of ascending aorta (2.41 ± 0.39 vs. 2.10 ± 0.57, p < 0.05) and post-coarctation aorta (2.17 ± 0.48 vs. 1.68 ± 0.43, p < 0.001) compared with mild group. Degree of coarctation was associated with the z-scores of the ascending aorta (r = - 0.356, p < 0.05) and post-coarctation aorta (r = - 0.414, p < 0.05). Collateral circulation was related to the z-scores of ascending aorta (r = 0.375, p < 0.05). Increased severity of coarctation was independent predictor of ascending (odds ratio 7.46; 95% CI 1.19-46.76; p < 0.05) and post-coarctation aortic dilation(odds ratio 8.42; 95% CI 1.84-38.56; p < 0.05).

CONCLUSIONS

Ascending and post-coarctation aortic diameters or dilations were both associated with the degree of coarctation. By comprehensively evaluating the aortic diameters and associated malformations including collateral circulation, DSCT can aid in stratification of risk for aortic dilation in patients with CoA.

Regional myocardial strain measurements from 4DCT in patients with normal LV function

BACKGROUND

CT SQUEEZ is a new automated technique to evaluate regional endocardial strain by tracking features on the endocardium from 4D cine CT data. The objective of this study was to measure the range of endocardial regional strain (RS_CT) values obtained with CT SQUEEZ in the normal human left ventricle (LV) from standard clinical 4D coronary CTA exams.

METHODS

RS_CT was measured over the heart cycle in 25 humans with normal LV function using cine CT from three vendors. Mean and standard deviation of RS_CT values were computed in 16 AHA LV segments to estimate the range of values expected in the normal LV.

RESULTS

Curves describing RS_CT vs. time were consistent between subjects. There was a slight gradient of decreasing minimum RS_CT value (increased shortening) from the base to the apex of the heart. Mean RS_CT values at end-systole were: base = -32% ± 1%, mid = -33% ± 1%, apex = -36% ± 1%. The standard deviation of the minimum systolic RS_CT in each segment over all subjects was 5%. The average time to reach maximum shortening was 34% of the RR interval.

CONCLUSIONS

Regional strain (RS_CT) can be rapidly obtained from standard gated coronary CCTA protocols using 4DCT SQUEEZ processing. We estimate that 95% of normal LV end-systolic RS_CT values will fall between -23% and -43%; therefore, we hypothesize that an RS_CT value higher than -23% will indicate a hypokinetic segment in the human heart.

Assessment of transposition of the great arteries associated with multiple malformations using dual-source computed tomography

Purpose

To determine the value of dual-source computed tomography (DSCT) in depicting the morphological characteristics and diagnosing the associated malformations for patients with transposition of the great arteries (TGA) before surgery.

Materials and methods

Twenty-five patients with TGA who underwent DSCT and transthoracic echocardiography (TTE) examination were retrospectively reviewed. The morphological types of TGA, the spatial relationship between the pulmonary artery and the aorta, as well as coronary artery-associated abnormalities were assessed by DSCT. In contrast to TTE, the diagnostic accuracy of associated malformations on DSCT were analyzed and calculated with reference to surgical or digital subtraction angiography (DSA) findings. Effective doses (EDs) were also calculated.

Results

Among the 25 patients, 12 (48%) had ventricular septal defects and left ventricular outflow tract stenosis. Sixteen patients (16/25, 64%) had great arteries with an oblique spatial relationship on DSCT. In addition, we found seven patients (7/25, 28%) with coronary artery malformation, including five with an abnormal coronary origin and two with signs of a myocardial bridge. According to DSA or surgical findings, DSCT was superior to TTE in demonstrating extracardiac anomalies (sensitivity, anomalies of great vessels: 100% vs. 93.33%, other anomalies: 100% vs. 46.15%). The mean estimated ED for those aged <10 years was <2 mSv (1.59 ± 0.95 mSv).

Conclusions

DSCT can achieve an overall assessment of patients with TGA, including any associated malformations as well as the identification of the spatial relationship of the great arteries. DSCT can therefore be considered as an alternative imaging modality for surgical decision making.

Dual-source Computed Tomography for Evaluating Pulmonary Artery and Aorta in Pediatric Patients with Single Ventricle

To explore the accuracy of main pulmonary artery (MPA) and ascending aorta (AAO) image evaluation in pediatric patients with single ventricle (SV) by comparing dual-source computed tomography (DSCT) with echocardiography. Thirty-one children with SV were retrospectively enrolled. The stenosis, dilation, and location of MPA and AAO were independently evaluated by DSCT and echocardiography. The accompanying arterial malformations were also assessed by DSCT. For 17 patients undergoing cardiac catheterization, the DSCT-based diameters of MPA and AAO were correlated with their pressures as measured by catheterization. Referring to the surgical and catheterization findings, DSCT had better diagnostic performance in detecting the stenosis, dilation, and location of MPA and AAO with higher sensitivity than echocardiography (sensitivity, MPA: 88.0% vs. 80.0%, AAO: 100% vs. 66.7%, great arteries location: 95.7% vs. 95.2%). The correlations between diameters of MPA and AAO with their pressures were 0.399 (p = 0.04) and 0.611 (p = 0.01), respectively. In addition, DSCT detected 23 cases with patent ductus arteriosus, 26 systemic-to-pulmonary collaterals, 9 branch pulmonary distortions, and 4 coronary artery anomalies. DSCT is reliable for assessing the anatomic features of pulmonary artery and aorta in SV children, and provides comprehensive information for surgical strategy-making.

A novel method for evaluating regional RV function in the adult congenital heart with low-dose CT and SQUEEZ processing

BACKGROUND

Measuring local RV function in adult congenital heart disease (ACHD) with echocardiography or MRI is challenging because of the complex geometry and existing pacing devices. Visual assessment of ventricular function via low-dose cardiac CT has been recently performed. This pilot study assessed whether low-dose 4D cine CT combined with automatic measurement of regional shortening could quantify right-ventricular function in ACHD patients.

METHODS

Seven patients with Tetralogy of Fallot either contraindicated for MRI or assessed for coronary artery disease and seven non-congenital patients were imaged with ECG-gated cardiac CT utilizing a 320-detector row scanner. Right ventricular global function and regional shortening were quantified.

RESULTS

Non-congenital patients were imaged with 2.9±2.1mSv and 395±359 HU blood-myocardium contrast. The ACHD patients were imaged with 2.1±1.3mSv and 726±296 HU contrast. Right ventricles of the ACHD patients had higher end-diastolic volume (297±107mL vs 123±34mL, p=0.001), lower ejection fraction (32.0±4.9% vs 45.0±6.0%, p=0.001), and higher dyskinetic fraction (10.9±3.7% vs 2.6±2.8%, p<0.001) relative to the non-congenital controls.

CONCLUSIONS

In this initial pilot study, right ventricular global and regional systolic function were measured using low-dose cine CT with SQUEEZ quantification in non-congenital patients as well as ACHD patients with Tetralogy of Fallot. Unique regional features of RV dyskinesia were identified in the ACHD patients which could yield a more precise quantification of RV function.