Cardiac Scans Research Articles

AI-enabled automated cardiac chambers volumetry in non-contrast ECG-gated cardiac scans vs. non-contrast non-gated lung scans

Abstract Introduction We have developed an AI-enabled automated volume measurement of cardiac chambers (AutoChamber) that works on ECG-gated coronary artery calcium scans and correlates well with contrast enhanced coronary CT angiography scans. We have recently reported that increased left atrial volume measured by AutoChamber is a strong predictor of new onset atrial fibrillation (AF) in asymptomatic individuals of Multi-Ethnic Study of Atherosclerosis (MESA). In this study, we compare the volumetry results in ECG- gated CAC scans with those of non-gated full-chest lung cancer screening scans in the same individuals. Methods We have studied 169 cases of paired ECG-gated cardiac CT scans and non-gated lung scans obtained from Harbor UCLA. Mean±SD for age was 62.1±10.0 years with 52% female participants. All cases were asymptomatic and were scanned for preventive health assessment. AutoChamber was run on all cases by an independent operator who was not involved in data analysis. P value was calculated using a two-tailed test of significance with α=0.05. Results AutoChamber in cardiac scans vs lung scans reported volume (Mean±SD) for left atrium (LA) was 63.8 ± 18.5 vs. 65.5 ± 19.4, left ventricle (LV) 102.8 ± 25.3 vs. 105.5 ± 25.2, right atrium (RA) 81.9 ± 20.5 vs. 85.7 ± 21.9 right ventricle (RV), 140.7 ± 34.2 vs. 134.2 ± 33.7, left ventricle wall (LVW) 113.0 ± 26.6 vs. 109.7 ± 27.0 respectively (P < 0.0001). Strong correlation was shown between cardiac and lung scans for each cardiac chamber: LA (R = 0.92), LV (R = 0.93), RA (R = 0.91), RV (R = 0.92), and left ventricular wall (LVW) R = 0.95. Conclusions AutoChamber volumetry results are similar in ECG-gated cardiac scans vs non-gated full-chest lung scans. This AI-enabled automated tool is promising as it can provide added value to patients undergoing coronary calcium and lung cancer screening scans flagging enlarged cardiac chambers at risk of AF and heart failure.

AI-enabled cardiac chambers volumetry in non-contrast coronary artery calcium CT scans vs. contrast-enhanced coronary CT angiography scans in the same patients

Abstract Introduction We have developed an AI-enabled automated volumetry of cardiac chambers (AutoChamber) that works both on non-contrast ECG-gated cardiac CT scans used for coronary artery calcium (CAC) score, and non-contrast non-gated lung cancer screening CT scans. We have recently reported the agreement between AutoChamber measurements vs cardiac MRI measurements. Here we report AutoChamber results on non-contrast CAC scans and contrast enhanced coronary CT angiography (CTA). Methods We have obtained CT images from a previously published study in which 131 cases underwent non-contrast CAC and contrast enhanced CCTA at research institute. The cases consisted of 52.4% women with ages 55.0 ± 10.1 years. The cardiac chambers volume in 131 cases of contrast enhanced CCTA were measured using automated chamber volumetry by Philips Brilliance Volume v 4.5; Philips Healthcare. Results The correlations between Philips’ automated chamber volumetry in contrast enhanced CCTA scans versus AutoChamber automated volumetry in non-contrast CAC scans for left atrium (LA), left ventricle (LV), right atrium (RA), right ventricle (RV), and left ventricular wall (LVW) volume were 0.73, 0.65, 0.85, 0.93, 0.90, respectively (P for all <0.01). Conclusion AI-enabled AutoChamber volumetry based on non-contrast cardiac scans is feasible, and correlates reasonably well with contrast-enhanced cardiac CT scans. Further studies are warranted to reproduce these results and explore the add-on value of AutoChamber to CAC scans.

Prevalence, characteristics and significance of anomalous coronary arteries in adults undergoing cardiac CT scans

Abstract Background/introduction The widespread use of CT coronary angiogram (CTCA) for the evaluation of patients with suspected coronary artery disease has resulted in increased identification of anomalous coronary arteries. These are often incidental findings and their prevalence and significance remains unknown. Purpose To identify the prevalence, characteristics and significance of anomalous coronary arteries in patient undergoing cardiac CT for suspected coronary artery disease. Methods This is a retrospective analysis of all cardiac CT scans (n= 5727 CTCAs) performed at two tertiary centres in the UK from 2015 to 2022. For the purpose of this study, we excluded separate LAD and circumflex artery coronary origins given it is clinical non-significance. Results Eighty three patients (1.45%) were identified as having anomalous coronary arteries. The average age of patients with anomalous coronary arteries was 57 years (range 18 - 86 years) and 36% were female. The most common coronary anomaly was the left circumflex artery arising from the right side (49 patients, 59%) and all had a retroaortic course. This was followed by an anomalous right coronary artery arising from the left side (29 patients, 35%) with 93% of them taking an interarterial course whilst 7% had a subpulmonic course. We also identified an anomalous left main stem (14 patients, 17%) arising from the right side (5 retroaortic, 5 subpulmonic, 2 prepulmonic, 1 anterior and 1 interarterial course). Four patients (5%) had an anomalous LAD arising from the right (2 prepulmonic, 1 subpulmonic and 1 anterior course). Four patients had other coronary anomalies (left circumflex artery arising from right pulmonary artery, OM arising from left ventricle, congenital atresia of left main stem and an ALCAPA). Majority of the patients with an anomalous coronary artery taking an interarterial course underwent a stress test. During a mean follow-up period of 4 years, four patients (5%) underwent cardiac surgery for treatment of anomalous coronary artery (ALCAPA, left main stem atresia and two anomalous right with interarterial course), seven patients underwent cardiac surgery for other reasons (significant atherosclerotic coronary artery disease and/or valve disease), five patients underwent PCI for treatment of atherosclerotic coronary artery disease and two patients died for reasons unrelated to their coronary anomaly. Conclusion This study of a large and unselected cohort of CTCA patients demonstrates an overall prevalence of coronary artery anomalies (as defined above) of 1.45%. We also report the prevalence and characteristics of different coronary anomalies and their outcomes. In the majority of patients, coronary artery anomalies are incidental findings and can be managed conservatively.

Relationship between epicardial adipose tissue and ventricular fibrillation in Brugada syndrome by cardiac computed tomography analysis

Abstract Background Fibrofatty changes in the myocardium of the right ventricular (RV) to right ventricular outflow tract (RVOT) in patients with Brugada syndrome (BrS) may contribute to ventricular conduction delay and ultimately in the development of ventricular fibrillation (VF). In patients with atrial fibrillation (AF), inflammatory infiltration of epicardial adipose tissue (EAT) into the atrial muscle, along with reduced quantity and quality of EAT, has been demonstrated to be associated with the development of AF. We hypothesized that EAT in the RVOT from the RV in patients with BrS may lead to organic abnormalities in the ventricular muscle, resulting in VF. Purpose The purpose of this study was to evaluate the quantity and quality of EAT in patients with BrS using cardiac computed tomography (CT) and to determine the relationship with the occurrence of VF. Methods We retrospectively evaluated 61 of 82 patients with BrS regularly followed in our outpatient clinic from January 2000 to December 2023, who underwent cardiac CT scans. Patients were divided into two groups: those with VF events during follow-up (VF event group) and those without events (VF non-event group). Patient background, various parameters, volume of epicardial adipose tissue (EAT), and CT values from cardiac CT scans were compared between the two groups. EAT volume and CT values were measured for the entire heart and four specific regions: right ventricle (RV-EAT), right ventricular outflow tract (RVOT) to pulmonary artery bifurcation (RVOT-EAT), left ventricle (LV-EAT), and the left coronary artery main trunk circumference (LV summit-EAT) were measured for four specific sites. Results Median age at first diagnosis of BrS was 43 years, 98% were male patients, 41 patients (71%) had symptomatic BrS, and 18 patients (31%) had a family history. During a median follow-up of 72 months (30-136 months), 22 patients (38%) had VF events, including 2 arrhythmic sudden deaths. The median time from diagnosis to the first VF event was 14.3 months (4.3-24.5 months). The VF event group had more overall EAT volume (98.3 cm3 [range: 77.4 to 120.3 cm3] vs. 70.1 cm3 [range: 53.8 to 98.0 cm3], P=0.02) and significantly more RV-EAT volume (18.4 cm3 [range: 11.5 to 28.0 cm3] vs. 11.0 cm3 [range: 7.9 to 18.3 cm3], P=0.008). The CT value of RV-EAT was significantly lower in the VF event group (-83.1±6.1 vs -78.0±6.2, P=0.003), although the RV-EAT/LV-EAT density ratio was not different between the two groups (1.01±0.05 vs 0.99±0.07, P=0.14). On the other hand, the density ratio of RVOT-EAT/LV-EAT was significantly lower in the VF event group (0.95±0.08 vs. 1.00±0.08, P=0.03). Conclusions EAT analysis via CT in patients with BrS revealed that those experiencing VF events during follow-up tended to exhibit greater RV-EAT volume, lower CT values of RV-EAT, and higher CT values of RVOT-EAT density. These findings suggest EAT involvement in VF occurrence in patients with BrS.

A novel marker of cardiovascular risk stratification: the role of total cardiovascular calcium score using cardiac CT

Abstract Introduction It is widely accepted that coronary and valve calcification measured by cardiac CT, individually, are associated with cardiovascular events and mortality. However, the role of an encompassing marker of cardiovascular atherosclerosis could be more representative of the real cardiovascular risk. Objectives To determine the prognostic value of a combined coronary, valvular and aortic calcium score to predict long-term major adverse cardiac and cerebrovascular events (MACCE). Methods We conducted a single center study on 316 consecutive patients who underwent cardiac CT scan between January 2018 and December 2019. We excluded patients with poor imaging quality, constrictive pericarditis, prosthetic valves and/or devices. The calcium score of coronary arteries (CA), mitral valve (MV), aortic valve (AoV), ascending aorta (AAo) and aortic arch (AAc) were calculated from non-contrast ECG-gated CT using the Agatston method and were combined to derive a valvular (VA=MV+AoV), total cardiac (TC=CA+VA) and total cardiovascular (TCV=TC+AAo+AAc) calcium scores (Fig.1A). The primary endpoint was a composite of MACCE, defined as all-cause death, stroke, myocardial infarction and hospital admission for heart failure. Results A total of 275 CT scans were suitable for analysis. Mean age was 59.6±12.3 years, 48.4% were female. A total of 183 (66.7%) patients presented calcification in at least one location. Patients with calcification on any of the prespecified locations had higher prevalence of hypertension, dyslipidemia and type 2 diabetes mellitus (DM) than those without any calcium (p<0.05). After a median follow-up of 3.18 [IQR 2.84-3.69] years, 40 (14.5%) patients had met the primary endpoint. Regression analyses demonstrated that all CA, VA, TC and TCV scores were independent predictors of MACCE (p<0.05 for all). The best prediction models included calcium score (all combinations), age, sex, type 2 DM and smoking status (Fig.1B). The model with TCV score was the most powerful predictor of MACCE (χ2 47.8), followed by TC score (χ2 43.1). Of interest, the model with CA score had the poorest performance (χ2 35.4). Conclusion Coronary calcium score is a quick way to stratify risk in clinical practice, but its performance is too focused on coronary events. Total cardiovascular calcium score, however, is more encompassing, also quick to measure, and a more truthful depiction of the patient’s cardiac and cerebrovascular risk, potentially allowing a more tailored and timely approach to risk factors in clinical practice.

AI-based algorithm for assessing coronary artery calcium score on contrast-enhanced cardiac computed tomography scans

Abstract Introduction In cardiac computed tomography (CT) examinations, non-contrast scans are often performed in addition to contrast-enhanced scans to quantify the coronary artery calcification (CAC) score. These calcium score scans are associated with additional exposure to ionizing radiation. Purpose We sought to develop a fully automated artificial intelligence (AI)-based algorithm capable of determining CAC score based solely on contrast-enhanced CT scans, eliminating the need for additional non-contrast scans. Methods An automated CAC scoring algorithm on contrast-enhanced CT scans was developed and trained using a dataset of 297 cardiac CT studies. Coronary artery calcifications were manually segmented in contrast-enhanced scans using a threshold of 2 standard deviations above the mean attenuation value of the ascending aorta. On non-contrast scans, CAC was manually assessed using a standard threshold of ≥130 Hounsfield Units. A correction factor for calcium score results assessed on contrast-enhanced scans was determined using linear regression. The algorithm was tested on an independent set of 90 contrast-enhanced CT scans (four manufacturers, eight scanner models). We compared automated CAC scores to manual expert reader reference assessments on non-contrast CT scans. CAC scores were categorized into four risk categories following the Society of Cardiovascular Computed Tomography recommendations: 0, 1-100, 101-300, and >300 Agatston Units. Results In the assessment of 90 CT studies (mean age 61.0±11.4 years, 46.7% males), the AI-model detected CAC in 69 contrast-enhanced scans (76.7%), comparable to the human reader's detection rate of CAC in 71 non-contrast scans (78.9%) (p = 0.63). The CAC score was initially calculated using AI-based segmentation of coronary calcification on contrast-enhanced scans and then the result was multiplied by established linear correction factor of 1.97. There was an excellent correlation between AI-model and manual reference total CAC scores (Pearson’s r = 0.96, 95% CI 0.94–0.97, p < 0.001). The model correctly classified 77 patients (85.6%) into the same CAC risk category as the human reader (Figure 1). Among 19 patients (21.1%) with a CAC score of zero, only 1 patient (5.3%) was reclassified with a non-zero CAC score by the AI-model. Cohen’s kappa value for CAC score risk categorization was 0.80 (p < 0.001), indicating very good agreement (Figure 2). Bland–Altman analysis revealed minimal bias of -9.7 Agatston Unit with 95% limits of agreement ranging from -184.8 to 165.5 Agatston Unit. Conclusions CAC score can be accurately quantified on contrast-enhanced cardiac CT scans using an automated AI-based algorithm. This approach has the potential to eliminate the necessity for an additional non-contrast CT scan, thereby reducing the patient's exposure to ionizing radiation.

Higher left ventricular stroke volume is associated with aortic dilatation in repaired tetralogy of Fallot patients.

Aortic root dilation has been reported commonly after repair of tetralogy of Fallot. However, the rate and risk factors of progression of the dilation are not fully understood. This is a single-centre, retrospective study to assess the rate and factors associated with progressive dilatation of the aortic root in repaired tetralogy of Fallot patients using cardiac MRI. The presence of the significant aortic dilation and the progression of dilation between initial and follow-up cardiac MRI were examined. The study cohort comprised 72 patients with repaired tetralogy of Fallot. The median age at the initial cardiac MRI scan was 19.6 (interquartile range: 14.6-31) years, and the median follow-up interval was 4.3 (2.9-5.7) years. Median dimension of ascending aorta at initial and follow-up cardiac MRI was 27.0 (22.3-31.0) mm and 29.2 (25.0-32.1) mm, respectively. Significant aortic dilation (the percentage predicted ascending aorta ≥150%) was observed in 11 (15.2%) patients at the initial cardiac MRI and 24 (33.3%) at the follow-up cardiac MRI. The significant aortic dilation at follow-up cardiac MRI was associated with increased indexed left ventricular stroke volume (odds ratio 1.062, p = 0.023). Thirteen patients demonstrated the significant progressive dilation of aorta between initial and follow-up cardiac MRI. The progressive dilation was associated with left ventricular ejection fraction at initial cardiac MRI (odds ratio 1.135, p = 0.048). In patients with repaired tetralogy of Fallot, aortic dilation is common and progresses over time. Cardiac MRI is a valuable tool for identifying individuals at risk for progressive aortic dilation.

Dynamic sequential cross-sectional scanning increases detection rate of congenital heart disease in sonographers: a prenatal ultrasound training program

BackgroundPrenatal ultrasound is the preferred modality for diagnosing fetal congenital heart disease. Given issues of physician proficiency and hospital distribution, we propose a dynamic sequential cross-sectional scanning (SCS) to explore the feasibility of cardiac screening by sonographers with less than 5 years of experience in ultrasound.Materials and methodsTwenty residents were randomly divided into two groups, receiving training in the American Institute of Ultrasound in Medicine (AIUM) fetal echocardiography and the SCS method. According to the needs of training, the professional staff developed the theoretical knowledge question bank, the CHD ultrasonic video disease bank, and the assessment scale. Trainees completed the pre-training examination, theory and skill operation training, and post-training assessment. For the two groups, the theoretical knowledge, skill operation and disease diagnosis were analyzed statistically before and after training.ResultsAfter training, the trainees in both groups had significantly improved knowledge and diagnostic abilities, their diagnostic thinking about CHD was clear, and they could identify major or even all structural abnormalities and make a definite diagnosis. In terms of skill operation, both groups could complete all required scanning within the specified time. The scanning time of the SCS group was significantly lower than that of the AIUM group, and the effect of the receptor site in the AIUM group was significantly higher than that in the SCS group.ConclusionSCS can be used as a new rapid fetal cardiac scanning method and try to popularize among echocardiographer.

Is there still protected health information in openly available PowerPoint files?

IntroductionPowerPoint presentations containing radiographic images continue to be an important educational tool for healthcare professionals. When properly deidentified, these radiographic imaging files are valuable and do not pose any privacy concerns for patients. However, when these images are not properly managed, patient information can be uncovered; raising concerns about patient privacy and potential legal consequences for healthcare systems and academic institutions. This study revisited and expanded upon previous work published by Weadock et. al in an attempt to see how this issue has changed in the last 15 years. MethodsThis study consisted of 8 separate Google Web searches related to a medical imaging modality. Each PowerPoint file was manually inspected for imaging files including x rays, CT scans, MRI's, PET scans, CT and MR angiography and ultrasounds. If a PowerPoint contained an image file, it was then inspected for PHI. Full PHI included all of the following: patient's full name, medical registration number (MRN), date and a geographic indicator smaller than a state. ResultsThe first two Google searches “Magnetic Resonance Imaging filetype:ppt” and “Cardiac CT CAT Scan filetype:ppt” returned 146 search results with 7.6 % containing full PHI. “Radiology Chest X-ray filetype:ppt” resulted in accessible PHI in 40 % of the presentations with images and “Post-Operative CT Scan filetype:ppt” resulted in accessible PHI in 29 %. Magnetic Resonance Imaging filetype:pptx” returned 0 results with PHI. “Cardiac CT CAT scan filetype:pptx” returned 1 result with partial PHI.“Radiology Chest X-ray filetype:pptx” contained 4 results with partial PHI and 1 result with full PHI. “Post-Operative CT scan filetype:pptx” contained 2 presentations with partial PHI. DiscussionWhile a declining percentage of PowerPoint files containing PHI is reassuring, this follow up study demonstrated that PHI can still be easily accessed openly on the internet by anyone who has basic familiarity with Microsoft PowerPoint. Work remains to continue to educate users on how to properly protect patient information in PowerPoint files. Appropriately protecting private healthcare information is essential for patient safety and can prevent unintentional HIPAA violations. Radiologists are uniquely positioned to educate other healthcare providers on how to properly remove PHI from radiologic imaging files.

A recurrent typical angina pectoris without any finding in coronary angiography: Microvascular angina.

Microvascular angina (MVA) can present with recurrent chest pain and normal coronary angiography. Recognizing MVA is crucial as it significantly impacts patient morbidity and mortality. Early diagnosis and management with antianginal medications are essential for improving outcomes and quality of life. Cardiovascular diseases are still the main cause of death in many parts of the world. Chest pain and dyspnea are always concerning due to the implications of cardiovascular disease. However, in patients with the involvement of the small coronary vessels (Microvascular Angina), symptoms might be recurrent and persistent despite the presence of normal coronary vessel evaluations. A 45-year-old man with a 25-year smoking history presented with recurrent chest pain, especially during physical activity, and mild shortness of breath. He was admitted, and a coronary angiography the next day appeared normal. However, a cardiac PET scan revealed the involvement of small coronary vessels not visible on angiography. The Patient was a 45-year-old man who presented with recurrent chest pain, more prominent during physical activity. He also had mild shortness of breath. The patient was admitted, and the next day, he underwent normal coronary angiography. The cardiac positron emission tomography (PET scan) showed the involvement of small coronary vessels that were not obvious on angiography.

3D-targeted, electrocardiographic imaging-aided stereotactic radioablation for ventricular tachycardia storm: a case report

Abstract Background Stereotactic arrhythmia radioablation (STAR) is a promising non-invasive therapy for patients with ventricular tachycardia (VT). Accurate identification of the arrhythmogenic volume, or clinical target volume (CTV), on the radiotherapy (RT) 4D planning computed tomography (CT) scan is key for STAR efficacy and safety. This case report illustrates our workflow of electro-structural image integration for CTV delineation. Case summary A 72-year-old man with ischaemic cardiomyopathy and VT storm, despite two (endocardial and epicardial) catheter-based ablations, was consented for STAR. A 3D electro-structural arrhythmia model was generated from co-registered electroanatomical voltage and activation maps, electrocardiographic (ECG) imaging, and the cardiac CT angiography scan (in ADAS 3D), pinpointing the VT isthmus and inferoapical VT exit. At this location, an area with short recovery times was found with ECG imaging. A multidisciplinary team delineated the CTV on the transmural ventricular myocardium, which was fused with the 4D planning CT scan using a digital images and communication in medicine (DICOM) radiotherapy file. The CTV was 63% smaller compared with using the conventional American Heart Association 17-segment approach (11 vs. 24 cm3). A single fraction of 25 Gy was delivered to the internal target volume. After an 8-week blanking period, no VT recurrences or radiation-related side-effects were noted. Eight months later, the patient died from end-stage heart failure. Discussion We report a novel workflow for 3D-targeted and ECG imaging-aided CTV delineation for STAR, resulting in a smaller irradiated volume compared with segmental approaches. Acute and intermediate outcome and safety were favourable. Non-invasive ECG imaging at baseline and during induced VT holds promise for STAR guidance.

Rational approximation of golden angles: Accelerated reconstructions for radial MRI.

To develop a generic radial sampling scheme that combines the advantages of golden ratio sampling with simplicity of equidistant angular patterns. The irrational angle between consecutive spokes in golden ratio-based sampling schemes enables a flexible retrospective choice of temporal resolution, while preserving good coverage of k-space for each individual bin. Nevertheless, irrational increments prohibit precomputation of the point-spread function (PSF), can lead to numerical problems, and require more complex processing steps. To avoid these problems, a new sampling scheme based on a rational approximation of golden angles (RAGA) is developed. The theoretical properties of RAGA sampling are mathematically derived. Sidelobe-to-peak ratios (SPR) are numerically computed and compared to the corresponding golden ratio sampling schemes. The sampling scheme is implemented in the BART toolbox and in a radial gradient-echo sequence. Feasibility is shown for quantitative imaging in a phantom and a cardiac scan of a healthy volunteer. RAGA sampling can accurately approximate golden ratio sampling and has almost identical PSF and SPR. In contrast to golden ratio sampling, each frame can be reconstructed with the same equidistant trajectory using different sampling masks, and the angle of each acquired spoke can be encoded as a small index, which simplifies processing of the acquired data. RAGA sampling provides the advantages of golden ratio sampling while simplifying data processing, rendering it a valuable tool for dynamic and quantitative MRI.

Reproducibility of Cardiac Computed Tomography Classifications of Hypoattenuated Thickening and Peridevice Leak Following Left Atrial Appendage Closure.

To assess the reproducibility of interpreting hypoattenuated thickening (HAT) and peridevice leak (PDL) using cardiac computed tomography (CT) imaging following Watchman FLX left atrial appendage closure (LAAC). In this multicenter retrospective reproducibility study, 100 anonymized post-LAAC cardiac CT scans were evaluated within the same cardiac phase by an experienced and a novice rater blinded to prior evaluations. All scans were evaluated twice by each rater, assessing overall HAT and PDL categories as well as specific associated findings based on suggested algorithms for post-LAAC interpretation. Inter- and intra-rater agreement and reliability were evaluated using absolute agreement, Cohen's kappa and Kendall's tau for categorical variables, and mean difference, Bland-Altman plots, limits of agreement and intraclass correlation coefficients (ICC) for continuous variables.Within overall categories of both HAT and PDL, substantial agreement (kappa >0.61) and reliability (Kendall's tau-b > 0.75) were observed. Specifically, identifying high-grade HAT (kappa >0.78) and distal patency (kappa >0.85) displayed the highest agreement within HAT and PDL interpretation. Meanwhile, measuring the height of the proximal screw hub cove represented the least reliable HAT assessment among both inter- and intra-rater comparisons (ICC<0.75), while suspected leak mechanism represented the least reproducible PDL measure. Despite only minimal training of one rater, overall high levels of inter- and intra-rater agreement and reliability were observed across the chosen algorithms for interpretation of HAT and PDL following Watchman FLX LAAC. Prognostic implications of the included variables are to be explored in future trials and registries.

Fat-free noncontrast whole-heart CMR with fast and power-optimized off-resonant water excitation pulses

BackgroundCardiovascular MRI (CMR) faces challenges due to the interference of bright fat signals in visualizing structures like coronary arteries. Effective fat suppression is crucial, especially when using whole-heart CMR techniques. Conventional methods often fall short due to rapid fat signal recovery, leading to residual fat content hindering visualization. Water-selective off-resonant radiofrequency (RF) pulses have been proposed but come with tradeoffs between pulse duration, which increases scan time, and increased RF energy deposit, which limits their applicability due to specific absorption rate (SAR) constraints. The study introduces a lipid-insensitive binomial off-resonant (LIBOR) RF pulse, which addresses concerns about SAR and scan time, and aims to provide a comprehensive quantitative comparison with published off-resonant RF pulses for CMR at 3T. MethodsA short (1ms) LIBOR pulse, with reduced RF power requirements, was developed and implemented in a free-breathing respiratory-self-navigated 3D radial whole-heart CMR sequence at 3T. A binomial off-resonant rectangular (BORR) pulse with matched duration, as well as previously published lipid-insensitive binomial off-resonant excitation (LIBRE) pulses (1ms and 2.2ms), were implemented and optimized for fat suppression in numerical simulations and validated in volunteers (n=3). Whole-heart CMR was performed in volunteers(n=10) with all four pulses. The signal-to-noise ratio (SNR) of ventricular blood, skeletal muscle, myocardium, and subcutaneous fat and the coronary vessel detection rates and sharpness were compared. ResultsExperimental results validated numerical findings and near homogeneous fat suppression was achieved with all four pulses. Comparing the short RF pulses (1ms), LIBOR reduced the RF power nearly two-fold compared with LIBRE, and three-fold compared with BORR, and LIBOR significantly decreased overall fat SNR from cardiac scans, compared to LIBRE and BORR. The reduction in RF pulse duration (from 2.2ms to 1ms) shortened the whole-heart acquisition from 8.5min to 7min. No significant differences in coronary arteries detection and sharpness were found when comparing all four pulses. ConclusionLIBOR pulses enabled whole-heart CMR under 7minutes at 3T, with large volume fat signal suppression, while reducing RF power compared with LIBRE and BORR pulses. LIBOR is an excellent candidate to address SAR problems encountered in CMR sequences where fat suppression remains challenging and short RF pulses are required. AVAILABILITY OF DATA AND MATERIALSAn online repository containing the anonymized human MRI raw data, as well as RF pulse shapes used in this study is publicly available at:https://zenodo.org/records/8338079(PART 1: KNEE V1-V3, HEART V1-V5)https://zenodo.org/records/10715769 (PART 2: HEART V6-V10)Matlab code to 1) simulate the different RF pulses within a GRE sequence and 2) to read and display the anonymized raw data is available from: https://github.com/QIS-MRI/LIBOR_LIBRE_BORR_SimulationCodeThe compiled research sequence can be requested through the Teamplay platform of Siemens Healthineers.

Improving Reproducibility of Volumetric Evaluation Using Computed Tomography in Pediatric Patients with Congenital Heart Disease.

The volumetric data obtained from the cardiac CT scan of congenital heart disease patients is important for defining patient's status and making decision for proper management. The objective of this study is to evaluate the intra-observer, inter-observer, and interstudy reproducibility of left ventricular (LV) and right ventricular (RV) or functional single-ventricle (FSV) volume. And compared those between manual and using semi-automated segmentation tool. Total of 127 patients (56 female, 71 male; mean age 82.1months) underwent pediatric protocol cardiac CT from January 2020 to December 2022. The volumetric data including both end-systolic and -diastolic volume and calculated EF were derived from both conventional semiautomatic region growing algorithms (CM, TeraRecon, TeraRecon, Inc., San Mateo, CA, USA) and deep learning-based annotation program (DLS, Medilabel, Ingradient, Inc., Seoul, Republic of Korea) by three readers, who have different background knowledge or experience of radiology or image extraction before. The reproducibility was compared using intra- and inter-observer agreements. And the usability was measured using time for reconstruction and number of tests that were reconfigured before the reconfiguration time was reduced to less than 5min. Inter- and intra-observer agreements showed better agreements degrees in DLS than CM in all analyzers. The time used for reconstruction showed significantly shorter in DLS compared with CM. And significantly small numbers of tests before the reconfiguration is needed in DLS than CM. Deep learning-based annotation program can be more accurate way for measurement of volumetric data for congenital heart disease patients with better reproducibility than conventional method.

Assessment of deep learning image reconstruction (DLIR) on image quality in pediatric cardiac CT datasets type of manuscript: Original research.

To evaluate the quantitative and qualitative image quality using deep learning image reconstruction (DLIR) of pediatric cardiac computed tomography (CT) compared with conventional image reconstruction methods. Between January 2020 and December 2022, 109 pediatric cardiac CT scans were included in this study. The CT scans were reconstructed using an adaptive statistical iterative reconstruction-V (ASiR-V) with a blending factor of 80% and three levels of DLIR with TrueFidelity (low-, medium-, and high-strength settings). Quantitative image quality was measured using signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The edge rise distance (ERD) and angle between 25% and 75% of the line density profile were drawn to evaluate sharpness. Qualitative image quality was assessed using visual grading analysis scores. A gradual improvement in the SNR and CNR was noted among the strength levels of the DLIR in sequence from low to high. Compared to ASiR-V, high-level DLIR showed significantly improved SNR and CNR (P<0.05). ERD decreased with increasing angle as the level of DLIR increased. High-level DLIR showed improved SNR and CNR compared to ASiR-V, with better sharpness on pediatric cardiac CT scans.

Developing Cut-off Values for Low and Very Low Bone Mineral Density at the Thoracic Spine Using Quantitative Computed Tomography

Osteoporosis is under-diagnosed while detectable by measuring bone mineral density (BMD) using quantitative computer tomography (QCT). Opportunistic screening for low BMD has previously been suggested using lumbar QCT. However, thoracic QCT also possesses this potential to develop upper and lower cut-off values for low thoracic BMD, corresponding to the current cut-offs for lumbar BMD. In participants referred with chest pain, lumbar and thoracic BMD were measured using non-contrast lumbar- and cardiac CT scans. Lumbar BMD cut-off values for very low (< 80 mg/cm3), low (80–120 mg/cm3), and normal BMD (> 120 mg/cm3) were used to assess the corresponding thoracic values. A linear regression enabled identification of new diagnostic thoracic BMD cut-off values. The 177 participants (mean age 61 [range 31–74] years, 51% women) had a lumbar BMD of 121.6 mg/cm3 (95% CI 115.9–127.3) and a thoracic BMD of 137.0 mg/cm3 (95% CI: 131.5–142.5), p < 0.001. Categorization of lumbar BMD revealed 14%, 35%, and 45% in each BMD category. When applied for the thoracic BMD measurements, 25% of participants were reclassified into a lower group. Linear regression predicted a relationship of Thoracic BMD = 0.85 * Lumbar BMD + 33.5, yielding adjusted thoracic cut-off values of < 102 and > 136 mg/cm3. Significant differences in BMD between lumbar and thoracic regions were found, but a linear relationship enabled the development of thoracic upper and lower cut-off values for low BMD in the thoracic spine. As Thoracic CT scans are frequent, these findings will strengthen the utilization of CT images for opportunistic detection of osteoporosis.

Stationary prospective cardiac gated computed tomography—dynamic study in phantoms and in vivo

Objective. This study explores the feasibility of a stationary gantry cardiac gated computed tomography (CT) with carbon nanotube (CNT) linear x-ray source arrays. Approach. We developed a stationary gantry CT system utilizing multipixel CNT x-ray sources. Given the advantages of straightforward x-ray pulse control with these sources, we investigated the potential for gated prospective imaging. We implemented prospective respiratory and cardiac gating control and evaluated the system through dynamic phantom imaging studies followed by imaging of a porcine model. Main Results. The findings revealed minimal anatomical motion artifacts in the heart and lungs, confirming successful physiologic gated acquisition in stationary gantry cardiac CT. This indicates the potential of this imaging approach for reducing artifacts and improving image quality. Significance. This study demonstrates the feasibility of prospective physiological gating with CNT x-ray sources in a stationary gantry setup for cardiac imaging. This approach could potentially alleviate the need for beta blocker administration during cardiac CT scans, thereby increasing the flexibility of the imaging system and enabling the imaging of a wider variety of patient cardiac conditions.

AI-based volumetric six-tissue body composition quantification from CT cardiac attenuation scans enhances mortality prediction: multicenter study.

Computed tomography attenuation correction (CTAC) scans are routinely obtained during cardiac perfusion imaging, but currently only utilized for attenuation correction and visual calcium estimation. We aimed to develop a novel artificial intelligence (AI)-based approach to obtain volumetric measurements of chest body composition from CTAC scans and evaluate these measures for all-cause mortality (ACM) risk stratification. We applied AI-based segmentation and image-processing techniques on CTAC scans from a large international image-based registry (four sites), to define chest rib cage and multiple tissues. Volumetric measures of bone, skeletal muscle (SM), subcutaneous, intramuscular (IMAT), visceral (VAT), and epicardial (EAT) adipose tissues were quantified between automatically-identified T5 and T11 vertebrae. The independent prognostic value of volumetric attenuation, and indexed volumes were evaluated for predicting ACM, adjusting for established risk factors and 18 other body compositions measures via Cox regression models and Kaplan-Meier curves. End-to-end processing time was <2 minutes/scan with no user interaction. Of 9918 patients studied, 5451(55%) were male. During median 2.5 years follow-up, 610 (6.2%) patients died. High VAT, EAT and IMAT attenuation were associated with increased ACM risk (adjusted hazard ratio (HR) [95% confidence interval] for VAT: 2.39 [1.92, 2.96], p<0.0001; EAT: 1.55 [1.26, 1.90], p<0.0001; IMAT: 1.30 [1.06, 1.60], p=0.0124). Patients with high bone attenuation were at lower risk of death as compared to subjects with lower bone attenuation (adjusted HR 0.77 [0.62, 0.95], p=0.0159). Likewise, high SM volume index was associated with a lower risk of death (adjusted HR 0.56 [0.44, 0.71], p<0.0001). CTAC scans obtained routinely during cardiac perfusion imaging contain important volumetric body composition biomarkers which can be automatically measured and offer important additional prognostic value.

Differentiating Left Ventricular Remodeling in Aortic Stenosis From Systemic Hypertension.

Left ventricular (LV) hypertrophy occurs in both aortic stenosis (AS) and systemic hypertension (HTN) in response to wall stress. However, differentiation of hypertrophy due to these 2 etiologies is lacking. The aim was to study the 3-dimensional geometric remodeling pattern in severe AS pre- and postsurgical aortic valve replacement and to compare with HTN and healthy controls. Ninety-one subjects (36 severe AS, 19 HTN, and 36 healthy controls) underwent cine cardiac magnetic resonance. Cardiac magnetic resonance was repeated 8 months post-aortic valve replacement (n=18). Principal component analysis was performed on the 3-dimensional meshes reconstructed from 109 cardiac magnetic resonance scans of 91 subjects at end-diastole. Principal component analysis modes were compared across experimental groups together with conventional metrics of shape, strain, and scar. A unique AS signature was identified by wall thickness linked to a LV left-right axis shift and a decrease in short-axis eccentricity. HTN was uniquely linked to increased septal thickness. Combining these 3 features had good discriminative ability between AS and HTN (area under the curve, 0.792). The LV left-right axis shift was not reversible post-aortic valve replacement, did not associate with strain, age, or sex, and was predictive of postoperative LV mass regression (R2=0.339, P=0.014). Unique remodeling signatures might differentiate the etiology of LV hypertrophy. Preliminary findings suggest that LV axis shift is characteristic in AS, is not reversible post-aortic valve replacement, predicts mass regression, and may be interpreted to be an adaptive mechanism.