Contrast-enhanced Cardiac Computed Tomography Research Articles

Automatic 3D left atrial strain extraction framework on cardiac computed tomography

Background and objectiveStrain analysis provides insights into myocardial function and cardiac condition evaluation. However, the anatomical characteristics of left atrium (LA) inherently limit LA strain analysis when using echocardiography. Cardiac computed tomography (CT) with its superior spatial resolution, has become critical for in-depth evaluation of LA function. Recent studies have explored the feasibility of CT-derived strain; however, they relied on manually selected regions of interest (ROIs) and mainly focused on left ventricle (LV). This study aimed to propose a first-of-its-kind fully automatic deep learning (DL)-based framework for three-dimensional (3D) LA strain extraction on cardiac CT. MethodsA total of 111 patients undergoing ECG-gated contrast-enhanced CT for evaluating subclinical atrial fibrillation (AF) were enrolled in this study. We developed a 3D strain extraction framework on cardiac CT images, containing a 2.5D GN-U-Net network for LA segmentation, axis-oriented 3D view extraction, and LA strain measure. The segmentation accuracy was evaluated using Dice similarity coefficient (DSC). The model-extracted LA volumes and emptying fraction (EF) were compared with ground-truth measurements using intraclass correlation coefficient (ICC), correlation coefficient (r), and Bland-Altman plot (B-A). The automatically extracted LA strains were evaluated against the LA strains measured from 2D echocardiograms. We utilized this framework to gauge the effect of AF burden on LA strain, employing the atrial high rate episode (AHRE) burden as the measurement parameter. ResultsThe GN-U-Net LA segmentation network achieved a DSC score of 0.9603 on the test set. The framework-extracted LA estimates demonstrated excellent ICCs of 0.949 (95 % CI: 0.93–0.97) for minimal LA volume, 0.904 (95 % CI: 0.86–0.93) for maximal LA volume, and 0.902 (95 % CI: 0.86–0.93) for EF, compared with expert measurements. The framework-extracted LA strains demonstrated moderate agreement with the LA strains based on 2D echocardiography (ICCs >0.703). Patients with AHRE > 6 min had significantly lower global strain and LAEF, as extracted by the framework than those with AHRE ≤ 6 min. ConclusionThe promising results highlighted the feasibility and clinical usefulness of automatically extracting 3D LA strain from CT images using a DL-based framework. This tool could provide a 3D-based alternative to echocardiography for assessing LA function.

Lipomatous Metaplasia Is Associated With Ventricular Tachycardia Recurrence Following Ablation in Patients With Nonischemic Cardiomyopathy

BackgroundVentricular tachycardia (VT) recurrence rates remain high following ablation among patients with nonischemic cardiomyopathy (NICM). ObjectivesThis study sought to define the prevalence of lipomatous metaplasia (LM) in patients with NICM and VT and its association with postablation VT recurrence. MethodsFrom patients who had ablation of left ventricular VT, we retrospectively identified 113 consecutive NICM patients with preprocedural contrast-enhanced cardiac computed tomography (CECT), from which LM was segmented. Nested within this cohort were 62 patients that prospectively underwent CECT and cardiac magnetic resonance from which myocardial border zone and dense late gadolinium enhancement (LGE) were segmented. A control arm of 30 NICM patients without VT with CECT was identified. ResultsLM was identified among 57% of control patients without VT vs 83% of patients without VT recurrence and 100% of patients with VT recurrence following ablation. In multivariable analyses, LM extent was the only independent predictor of VT recurrence, with an adjusted HR per 1-g LM increase of 1.1 (P < 0.001). Patients with LM extent ≥2.5 g had 4.9-fold higher hazard of VT recurrence than those with LM <2.5 g (P < 0.001). In the nested cohort with 32 VT recurrences, LM extent was independently associated with VT recurrence after adjustment for border zone and LGE extent (HR per 1 g increase: 1.1; P = 0.036). ConclusionsMyocardial LM is prevalent in patients with NICM of a variety of etiologies, and its extent is associated with postablation VT recurrence independent of the degree of fibrosis.

A deep learning approach to predict myocardial fibrosis in early contrast-enhanced CCT images

Abstract Funding Acknowledgements Type of funding sources: None. Background Late gadolinium enhancement (LGE) derived from cardiac magnetic resonance (CMR) has become a method of choice for the evaluation of myocardial tissue composition and detection of myocardial fibrosis. Advances in cardiac computed tomography (CCT) imaging have led to its growing role as possible alternative to CMR, because of its wider availability and suitability for patients with contraindication. Purpose To develop a myocardial fibrosis detection method from early contrast-enhanced CCT (CE-CCT) imaging using a deep learning (DL) approach. Methods Fifty consecutive patients (age: 62±10 y, male 84%) with known left ventricular dysfunction were enrolled. All patients underwent both LGE-CMR and early and delayed CE-CCT. According to the LGE-CMR patterns, patients were classified as ischemic (n=15, 30%) or non-ischemic (n=35, 70%). Scar regions were manually traced on delayed CE-CCT using LGE-CMR as reference. On early CE-CCT images, segments were extracted according to American Heart Association (AHA) 16-segment model and labeled (scar/no scar) based on the delayed CE-CCT manual tracing. A DL model was developed for automatic segmental classification. Results Based on 44187 segments analyzed, 71% of accuracy (ischemic: 66%; non-ischemic: 74%) for detecting scar on early CE-CCT images was achieved (Picture 1). In a per-segment analysis of the 16-segment AHA model, an accuracy of 91% (ischemic: 87%; non-ischemic: 93%) was obtained from early CE-CCT compared to the LGE-CMR. Conclusions DL on early CE-CCT acquisition may allow the detection of myocardial fibrosis without additional contrast-agent administration or radiation exposure, thus reducing the user interaction and visual inspection with benefit in both efforts and time.

Risk of Pacing-Induced Cardiomyopathy in Patients with High-Degree Atrioventricular Block-Impact of Right Ventricular Lead Position Confirmed by Computed Tomography.

Prospective studies applying fluoroscopy for assessment of right ventricular (RV) lead position have failed to show clear benefits from RV septal pacing. We investigated the impact of different RV lead positions verified by computed tomography (CT) on the risk of pacing-induced cardiomyopathy (PICM). We retrospectively included 153 patients who underwent routine fluoroscopy-guided pacemaker implantation between March 2012 and May 2020. All patients had normal pre-implant left ventricular ejection fraction (LVEF). Patients attended a follow-up visit including contrast-enhanced cardiac CT and transthoracic echocardiography. Patients were classified as septal or non-septal based on CT analysis. The primary endpoint was PICM (LVEF < 50% with ≥10% decrease after implantation). Based on CT, 48 (31.4%) leads were septal and 105 (68.6%) were non-septal. Over a median follow-up of 3.1 years, 16 patients (33.3%) in the septal group developed PICM compared to 31 (29.5%) in the non-septal group (p = 0.6). Overall, 13.1% deteriorated to LVEF ≤ 40%, 5.9% were upgraded to cardiac resynchronization therapy device, and 14.4% developed new-onset atrial fibrillation, with no significant differences between the groups. This study demonstrated a high risk of PICM despite normal pre-implant left ventricular systolic function with no significant difference between CT-verified RV septal or non-septal lead position.

Sex difference in aortic valve fibrosis assessed by contrast-enhanced computed tomography in severe aortic stenosis

Abstract Background Aortic stenosis (AS) is characterized by fibro-calcific remodeling of aortic valve leaflets. Progressive aortic valve calcification (AVC) occurs in both sexes and cardiac computed tomography (CT) is recognized as a high-quality technique for AVC evaluation. To date, sex-specific CT thresholds of AVC have been implemented in clinical practice since it is now recognized that women have less AVC burden than men. In addition, recent evidences indicate that women have more fibrotic remodeling of aortic valve leaflet compared to men. Purpose Aortic valve fibrosis (AVF) being a significant contributor to valve gradient, we sought to evaluate the difference in AVF burden between men and women with severe AS using contrast-enhanced CT. Methods We included 56 patients matched for age and sex with severe AS. All patients underwent Doppler echocardiography and cardiac CT before intervention. Contrast attenuation values (Hounsfield Units, HU) and contrast-to-noise ratio were measured at the level of the ascending aorta. Total AVF was assessed based on HU ranging between 30 and 350, adjusting the upper threshold by increments of 25 HU in either direction until blood pool was not highlighted. Indexed contrast-enhanced CT calcium volume (iAVC) and fibrosis volume (iAVF) were calculated dividing the volumes by the aortic annular area. Fibro-calcific ratio was calculate dividing iAVF by iAVC volumes. Results There was no difference between men and women in major cardiovascular risk factors, valve phenotype (bicuspid vs. tricuspid), nor pharmacological treatment. Men had higher body surface area than women (1.89±0.14 vs. 1.67±0.17 m2, respectively; p&amp;lt;0.001), while women had lower aortic valve area than men (AVA; 0.74±0.2 vs. 0.91±0.2 cm2, respectively; p=0.007) but similar indexed AVA (0.44±0.15 vs. 0.48±0.12 cm2/m2, respectively; p=0.262). Women had significantly lower iAVC compared to men (36 [36–72] vs. 72 [67–123] mm3/cm2, respectively; p=0.03). However, iAVF was significantly higher in women compared to men (83 [78–123] vs. 63 [58–83] mm3/cm2, respectively; p=0.006). Finally, the fibro-calcific ratio, which indicates the predominance of valve fibrosis if &amp;gt;1.0, was significantly higher in women compared to men (2.57 [2.14–7.02] vs. 0.78 [0.84–2.02], respectively; p=0.003). Conclusions Our study highlights for the first time a sex difference in the fibrotic content of severe AS evaluated by contrast-enhanced CT. These findings might be valuable to promote further studies on the role of sex-specific tissue composition in AS progression and outcomes. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Fondazione Gigi e Pupa Ferrari ONLUS

Coronary Artery Calcification as a Marker for Coronary Artery Stenosis: Comparing Kidney Failure to the General Population

Rationale & ObjectiveThe presence of calcified plaques in the coronary arteries is associated with cardiovascular mortality and is a hallmark of chronic kidney failure, but it is unclear whether this is associated with the same degree of coronary artery stenosis as in patients without kidney disease. We compared the relationship of coronary artery calcification (CAC) and stenosis between dialysis patients and patients without chronic kidney disease (CKD).Study DesignObservational cohort study.Setting & Participants127 dialysis patients and 447 patients without CKD with cardiovascular risk factors underwent cardiac computed tomography (CT), consisting of non–contrast-enhanced CT and CT angiography. CAC score and degree of coronary artery stenosis were assessed by independent readers.PredictorDialysis treatment.OutcomeAssociation between calcification and stenosis.Analytical ApproachLogistic regression to determine the association between CAC score and the presence of stenosis in a matched cohort and, in the full cohort, testing for the interaction of dialysis status with this relationship.Results112 patients were matched from each cohort, totaling 224 patients, using propensity scores for dialysis, balancing numerous cardiovascular risk factors. Median CAC score was 210 (IQR, 19-859) in dialysis patients and 58 (IQR, 0-254) in patients without CKD; 35% of dialysis patients and 36% of patients without CKD had coronary artery stenosis ≥ 50%. Per each 100-unit higher CAC score, the matched dialysis cohort had significantly lower ORs for stenosis than the non-CKD cohort, 0.67 (95% CI, 0.52-0.83) for stenosis ≥ 50% and 0.75 (95% CI, 0.62-0.90) for stenosis ≥ 70%.LimitationsNo comparison with the gold standard fractional flow reserve.ConclusionsDialysis patients have higher risk for coronary artery stenosis with higher CAC scores, but this risk is comparatively lower than in patients without CKD with similar CAC scores. In dialysis patients, a high CAC score can easily be found without significant stenosis. Our data enable “translation” of degree of calcification to the probability of coronary stenosis in dialysis patients.

Inter-Software and Inter-Scan Variability Amongst Post-Processing Software Platforms in Measurement of Epicardial Adipose Tissue

There is lack of standardisation of post-processing software platforms in the assessment of epicardial adipose tissue (EAT) on cardiac computed tomography (CT). This study assessed the inter-vendor agreement of EAT volume (EATv) and attenuation (EATa) on both contrast-enhanced (CE) and non-contrast CT (NCT) using freeware imaging software (OsiriX), EAT research-specific software (QFAT), and standard coronary CT reporting software (Vitrea).

Fully Automatic Coronary Calcium Score Software Empowered by Artificial Intelligence Technology: Validation Study Using Three CT Cohorts.

ObjectiveThis study aimed to validate a deep learning-based fully automatic calcium scoring (coronary artery calcium [CAC]_auto) system using previously published cardiac computed tomography (CT) cohort data with the manually segmented coronary calcium scoring (CAC_hand) system as the reference standard.Materials and MethodsWe developed the CAC_auto system using 100 co-registered, non-enhanced and contrast-enhanced CT scans. For the validation of the CAC_auto system, three previously published CT cohorts (n = 2985) were chosen to represent different clinical scenarios (i.e., 2647 asymptomatic, 220 symptomatic, 118 valve disease) and four CT models. The performance of the CAC_auto system in detecting coronary calcium was determined. The reliability of the system in measuring the Agatston score as compared with CAC_hand was also evaluated per vessel and per patient using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. The agreement between CAC_auto and CAC_hand based on the cardiovascular risk stratification categories (Agatston score: 0, 1–10, 11–100, 101–400, > 400) was evaluated.ResultsIn 2985 patients, 6218 coronary calcium lesions were identified using CAC_hand. The per-lesion sensitivity and false-positive rate of the CAC_auto system in detecting coronary calcium were 93.3% (5800 of 6218) and 0.11 false-positive lesions per patient, respectively. The CAC_auto system, in measuring the Agatston score, yielded ICCs of 0.99 for all the vessels (left main 0.91, left anterior descending 0.99, left circumflex 0.96, right coronary 0.99). The limits of agreement between CAC_auto and CAC_hand were 1.6 ± 52.2. The linearly weighted kappa value for the Agatston score categorization was 0.94. The main causes of false-positive results were image noise (29.1%, 97/333 lesions), aortic wall calcification (25.5%, 85/333 lesions), and pericardial calcification (24.3%, 81/333 lesions).ConclusionThe atlas-based CAC_auto empowered by deep learning provided accurate calcium score measurement as compared with manual method and risk category classification, which could potentially streamline CAC imaging workflows.

Abstract 12719: Diagnostic and Prognostic Contributions of Cardiac Computed Tomography for Infective Endocarditis Surgery

Background: Cardiac computed tomography (CT) is emerging as an adjunctive modality to echocardiography in the evaluation of infective endocarditis (IE) and surgical planning. CT studies in IE have, however, focused on its diagnostic rather than prognostic utility, the latter of which is important in high-risk diseases like IE. We evaluated the associations between cardiac CT and transesophageal echocardiography (TEE) findings and adverse outcomes after IE surgery. Methods: Of 833 consecutive patients with surgically proven IE during 5/1/2014-5/1/2019 at Cleveland Clinic, 155 underwent both pre-operative ECG-gated contrast-enhanced CT and TEE. Multivariable analyses were performed to identify CT and TEE biomarkers that predict adverse outcomes after IE surgery, adjusting for EuroSCORE II. Results: CT and TEE were positive for IE in 123 (75.0%) and 124 (75.6%) of patients respectively. CT identified an additional 11% of vegetations, 13% of pseudoaneurysms or abscesses, 5% of dehiscences and 14% of fistulae when TEE was negative. Thirty-day mortality occurred in 3 (1.9%) patients, and composite mortality and/or morbidities in 72 (46.5%). Pseudoaneurysm or abscess detected on TEE was the only imaging biomarker to show independent association with composite mortality and/or morbidities in-hospital, with odds ratio (95%CI) of 3.66 (1.76-7.59), P=0.001. There were 17 late deaths, and both pseudoaneurysm or abscess detected on CT and fistula detected on CT were the only independent predictors of total mortality during follow-up, with hazards ratios (95%CI) of 3.82 (1.25, 11.7), P&lt;0.001 and 9.84 (1.89, 51.0), P=0.007 respectively (Figure). Conclusion: We identified cardiac CT and TEE features that predicted separate adverse outcomes after IE surgery. Imaging biomarkers can play important roles incremental to conventional clinical factors for risk stratification in patients undergoing IE surgery.

Aortic dissection during transoesophageal echocardiography: a case report.

BackgroundTransoesophageal echocardiography (TOE) is a safe and useful tool. In our case, we are presenting a rare case of a patient with aortic dissection during TOE procedure.Case summaryA 79-year-old woman was referred to our hospital for recurrent paroxysmal atrial fibrillation (AF) with palpitation. Pre-procedural cardiac computed tomography (CT) showed slight dilated ascending aorta (maximum diameter: 40 mm). We decided to perform catheter ablation (CA) for AF, and recommended TOE before the CA because she had a CHADS2 score of 4. On the day before the CA, TOE was performed. Her physical examinations at the time of TOE procedure were unremarkable. At 3 min after probe insertion, there was no abnormal finding of the ascending aorta. At 5 min after the insertion, TOE showed ascending aortic dissection without pericardial effusion. After waking, she had severe back pain and underwent a contrast-enhanced CT. Computed tomography demonstrated Stanford type A aortic dissection extending from the aortic root to the bifurcation of common iliac arteries, and tight stenosis in the right coronary artery (maximum diameter; 49 mm). The patient underwent a replacement of the ascending aorta, and a coronary artery bypass graft surgery for the right coronary artery.DiscussionTransoesophageal echocardiography would have to be performed under sufficient sedation with continuous blood pressure monitoring in patients who have risk factors of aortic dissection. The risk–benefit of TOE must be considered before a decision is made. Depending on the situation, another modality instead of TOE might be required.

Current and novel imaging techniques to evaluate myocardial dysfunction during hemodialysis.

Patients on hemodialysis have significantly higher rates of cardiovascular mortality resulting from a multitude of myocardial dysfunctions. Current imaging modalities allow independent assessment of cardiac morphology, contractile function, coronary arteries and cardiac perfusion. Techniques such as cardiac computed tomography (CT) imaging have been available for some time, but have not yet had widespread adoption because of technical limitations related to cardiac motion, radiation exposure and safety of contrast agents in kidney disease. Novel dynamic contrast-enhanced (DCE) CT imaging can be used to acquire high-resolution cardiac images, which simultaneously allow the assessment of coronary arteries and the quantitative measurement of myocardial perfusion. The advancement of recent CT scanners and cardiac protocols have allowed noninvasive imaging of the whole heart in a single imaging session with minimal cardiac motion artefact and exposure to radiation. DCE-CT imaging in clinical practice would allow comprehensive evaluation of the structure, function, and hemodynamics of the heart in a short, well tolerated scanning session. It is an imaging tool enabling the study of myocardial dysfunction in dialysis patients, who have greater cardiovascular risk than nonrenal cardiovascular disease populations, both at rest and under cardiac stress associated with hemodialysis itself.

Complementary Diagnostic and Prognostic Contributions of Cardiac Computed Tomography for Infective Endocarditis Surgery.

Cardiac computed tomography (CT) is emerging as an adjunctive modality to echocardiography in the evaluation of infective endocarditis (IE) and surgical planning. CT studies in IE have, however, focused on its diagnostic rather than prognostic utility, the latter of which is important in high-risk diseases like IE. We evaluated the associations between cardiac CT and transesophageal echocardiography (TEE) findings and adverse outcomes after IE surgery. Of 833 consecutive patients with surgically proven IE during May 1, 2014 to May 1, 2019, at Cleveland Clinic, 155 underwent both preoperative ECG-gated contrast-enhanced CT and TEE. Multivariable analyses were performed to identify CT and TEE biomarkers that predict adverse outcomes after IE surgery, adjusting for EuroSCORE II (European System for Cardiac operative Risk Evaluation II). CT and TEE were positive for IE in 123 (75.0%) and 124 (75.6%) of patients, respectively. Thirty-day mortality occurred in 3 (1.9%) patients and composite mortality or morbidities in 72 (46.5%). Pseudoaneurysm or abscess detected on TEE was the only imaging biomarker to show independent association with composite mortality or morbidities in-hospital, with odds ratio (95% CI) of 3.66 (1.76-7.59), P=0.001. There were 17 late deaths, and both pseudoaneurysm or abscess detected on CT and fistula detected on CT were the only independent predictors of total mortality during follow-up, with hazards ratios (95% CI) of 3.82 (1.25-11.7), P<0.001 and 9.84 (1.89-51.0), P=0.007, respectively. We identified cardiac CT and TEE features that predicted separate adverse outcomes after IE surgery. Imaging biomarkers can play important roles incremental to conventional clinical factors for risk stratification in patients undergoing IE surgery.

Texture analysis of myocardial infarction in CT: Comparison with visual analysis and impact of iterative reconstruction

ObjectivesTo compare texture analysis (TA) with subjective visual diagnosis of myocardial infarction (MI) in cardiac computed tomography (CT) and to evaluate the impact of iterative reconstruction (IR). MethodsTen patients (4 women, mean age 68 ± 11 years) with confirmed chronic MI and 20 controls (8 women, mean age 52 ± 11 years) with no cardiac abnormality underwent contrast-enhanced cardiac CT with the same protocol. Images were reconstructed with filtered back projection (FBP) and with advanced modeled IR at strength levels 3–5. Subjective diagnosis of MI was made by three independent, blinded readers with different experience levels. Classification of MI was performed using machine learning–based decision tree models for the entire data set and after splitting into training and test data to avoid overfitting. ResultsSubjective visual analysis for diagnosis of MI showed excellent intrareader (kappa: 0.93) but poor interreader agreement (kappa: 0.3), with variable performance at different image reconstructions. TA showed high performance for all image reconstructions (correct classifications: 94%–97%, areas under the curve: 0.94–0.99). After splitting into training and test data, overall lower performances were observed, with best results for IR at level 5 (correct classifications: 73%, area under the curve: 0.65). ConclusionsAs compared with subjective, nonreliable visual analysis of inexperienced readers, TA enables objective and reproducible diagnosis of chronic MI in cardiac CT with higher accuracy. IR has a considerable impact on both subjective and objective image analysis.

Quantification of doxorubicin-induced interstitial myocardial fibrosis in a beagle model using equilibrium contrast-enhanced computed tomography: A comparative study with cardiac magnetic resonance T1-mapping

BackgroundThe noninvasive equilibrium contrast-enhanced cardiac computed tomography (CCT) has potential for myocardial tissue characterization. The objective of this study was to test the feasibility of CCT-based extracellular volume (ECV) fraction in beagle models of doxorubicin-induced interstitial myocardial fibrosis, with cardiac magnetic resonance (CMR) as the reference. MethodsThis study was approved by local ethics committee. Thirteen beagles were included with ECV quantified by CCT and CMR at baseline, 16 and 24 weeks after modeling. Spearman correlation analysis was used to determine the association between CT ECV, CMR ECV, collagen volume fraction (CVF), LVEF and serum fibrosis index (Hyaluronic acid [HA], Laminin [LN] and Type-III procollagen [PCIII]). ResultsMedian ECV values in CT and CMR at 16 and 24 weeks were significantly higher than those at baseline (CT ECV: 34.4% and 37.7% vs. 25.2%; CMR ECV: 32.2% and 37.4% vs. 22.7%; P < 0.001). A strong correlation was found between CCT and CMR for ECV (r = 0.899, P < 0.001). Both correlated well with CVF (r = 0.951 and 0.879 for CT and MR ECV vs. CVF, P < 0.001), serum fibrosis index (r = 0.830–0.907 for CT and MR ECV vs. HA, LN, PCIII, respectively, P < 0.05) and were inversely related to LVEF (r = −0.846 and −0.804 for CCT and CMR, P < 0.001). Bland-Altman analysis showed a small bias (1.5%), with 95% limits of agreement of −2.7% and 5.6%. ConclusionsCCT-derived ECV correlates well with CMR, histology and serum fibrosis index, suggesting that CCT is capable of myocardial tissue characterization.

Role of preoperative cardiac CT in the evaluation of infective endocarditis: comparison with transesophageal echocardiography and surgical findings.

Significant improvement of computed tomography (CT) technology in the last decade has led to more use of this modality for evaluating infective endocarditis (IE) especially since the introduction of high resolution electrocardiogram (ECG) synchronized multiphasic (4D) acquisition. While there are a number of reports on the accuracy and value of 4D CT for evaluation of IE, there is no published data regarding the performance of single-phase ECG gated CT for assessment of IE. The purpose of this study is to evaluate the sensitivity and specificity of preoperative single-phase ECG-gated CT imaging versus transesophageal echocardiography (TEE) in the assessment of complications related to IE, with comparison to surgical findings. Among 899 patients with surgically proven IE in our database, 122 underwent contrast-enhanced ECG cardiac CT and were included in the study; 84 of these patients also underwent TEE. Overall, there was no significant difference between CT and TEE in the identification of pseudoaneurysm/abscess and dehiscence. For the detection of pseudoaneurysm/abscess in prosthetic valves, CT demonstrated higher sensitivity (81% vs. 64%) and specificity (75% vs. 33%) in patients with mechanical aortic valves; TEE demonstrated marginally higher sensitivity (72% vs. 63%) and specificity (80% vs. 73%) in patients with bioprosthetic aortic valves, although the differences are not statistically significant. TEE demonstrated significantly higher sensitivity (85% vs. 16%) in identifying vegetation in all patients (P<0.0001), including patients with prosthetic valves (sensitivity, 78% vs. 19%). The combined imaging findings of CT and TEE demonstrated improved sensitivity in identifying pseudoaneurysm/abscess and slightly improved detection of prosthesis dehiscence. Preoperative single-phase gated CT can be seen as complementary to TEE in assessing complications of suspected IE or may be substituted for TEE when vegetation or dehiscence is depicted on transthoracic echocardiography and the patient has a contraindication to TEE.

Regional differences of fat depot attenuation using non-contrast, contrast-enhanced, and delayed-enhanced cardiac CT

Regional fat density assessed by computed tomography (CT) has been suggested as a marker of perivascular adipose tissue inflammation. Dual energy CT (DECT) allows improved tissue characterization compared to conventional CT. To explore whether DECT might aid regional fat density discrimination. We included patients who had completed a non-enhanced cardiac CT scan, CT coronary angiography (CTCA), and a delayed enhancement CT. Attenuation levels (Hounsfield units [HU]) were assessed at the epicardial, paracardial, visceral, and subcutaneous fat. The number of coronary segments with disease (SIS) was calculated. A total of 36 patients were included in the analysis. Twenty-six (72%) patients had evidence of obstructive disease at CCTA and 25 (69%) patients had evidence of previous myocardial infarction. At non-contrast CT, we did not identify significant attenuation differences between epicardial, paracardial, subcutaneous, and visceral fat depots (-110.8 ± 9 HU, vs. -113.7 ± 9 HU, vs. -114.7 ± 8 HU, vs. -113.8 ± 11 HU, P = 0.36). Significant attenuation differences were detected between fat depots at mid and low energy levels, both at CTCA and delayed-enhancement scans ( P < 0.05 for all). Epicardial fat showed the least negative attenuation, irrespective of the acquisition mode; epicardial fat evaluated at 40 keV was related to the SIS (r = 0.37, P = 0.03). In this study, regional fat depots amenable to examination during thoracic CT scans have distinctive regional attenuation values. Furthermore, such differences were better displayed using contrast-enhanced monochromatic imaging at low energy levels.

Field of view of mapping catheters quantified by electrogram associations with radius of myocardial attenuation on contrast-enhanced cardiac computed tomography

Contrast-enhanced cardiac computed tomography (CE-CT) provides useful substrate characterization in patients with ventricular tachycardia (VT). The purpose of this study was to describe the association between endocardial electrogram measurements and myocardial characteristics on CE-CT, in particular the field of view of electrogram features. Fifteen patients with postinfarct VT who underwent catheter ablation with preprocedural CE-CT were included. Electroanatomic maps were registered to CE-CT, and myocardial attenuation surrounding each endocardial point was measured at a radius of 5, 10, and 15 mm. The association between endocardial voltage and attenuation was assessed using a multilevel random effects linear regression model, clustered by patient, with best model fit defined by highest log likelihood. A total of 4698 points were included. There was a significant association of bipolar and unipolar voltage with myocardial attenuation at all radii. For unipolar voltage, the best model fit was at an analysis radius of 15 mm regardless of the mapping catheter used. For bipolar voltage, the best model fit was at an analysis radius of 15 mm for points acquired with a conventional ablation catheter. In contrast, the best model fit for points acquired with a multipolar mapping catheter was at an analysis radius of 5 mm. Myocardial attenuation on CE-CT indicates a smaller myocardial field of view of bipolar electrograms using multipolar catheters with smaller electrodes in comparison to standard ablation catheters despite similar interelectrode spacing. Smaller electrodes may provide improved spatial resolution for the definition of myocardial substrate for VT ablation.

Effect of iodinated contrast medium on thyroid function: a study in children undergoing cardiac computed tomography.

Few studies, and with conflicting results, have evaluated the potential effects of iodinated contrast media on children's thyroid function. To investigate the effects of iodinated contrast medium on thyroid function in neonates, infants and young children with congenital heart disease undergoing cardiac computed tomography (CT). We retrospectively evaluated 10 neonates (group 1) and 23 infants and young children (group 2) without thyroid or renal disease for serum levels of thyroid-stimulating hormone, free triiodothyronine and free thyroxine before contrast-enhanced cardiac CT, 48h after CT and at discharge from the hospital. Cardiac CT was performed with intravenous administration of 1.14±0.17mL/kg of body weight of iopromide (containing 370mg of iodine/mL). Group 1 had a reduction of thyroid-stimulating hormone from baseline to 48h post injection (P=0.002). Group 2 had a reduction of thyroid-stimulating hormone median levels from baseline to 48h post injection and an increase from 48h to discharge (P=0.0005 and P=0.0001, respectively). Intravenous iodinated contrast medium in children with congenital heart disease caused transient thyroid-stimulating hormone decrease 48h after CT, with thyroid-stimulating hormone returning to normal range at discharge.

SiSSR: Simultaneous subdivision surface registration for the quantification of cardiac function from computed tomography in canines.

Recent improvements in cardiac computed tomography (CCT) allow for whole-heart functional studies to be acquired at low radiation dose (<2mSv) and high-temporal resolution (<100ms) in a single heart beat. Although the extraction of regional functional information from these images is of great clinical interest, there is a paucity of research into the quantification of regional function from CCT, contrasting with the large body of work in echocardiography and cardiac MR. Here we present the Simultaneous Subdivision Surface Registration (SiSSR) method: a fast, semi-automated image analysis pipeline for quantifying regional function from contrast-enhanced CCT. For each of thirteen adult male canines, we construct an anatomical reference mesh representing the left ventricular (LV) endocardium, obviating the need for a template mesh to be manually sculpted and initialized. We treat this generated mesh as a Loop subdivision surface, and adapt a technique previously described in the context of 3-D echocardiography to register these surfaces to the endocardium efficiently across all cardiac frames simultaneously. Although previous work performs the registration at a single resolution, we observe that subdivision surfaces naturally suggest a multiresolution approach, leading to faster convergence and avoiding local minima. We additionally make two notable changes to the cost function of the optimization, explicitly encouraging plausible biological motion and high mesh quality. Finally, we calculate an accepted functional metric for CCT from the registered surfaces, and compare our results to an alternate state-of-the-art CCT method.

Texture analysis of acute myocardial infarction with CT: First experience study.

ObjectiveTo investigate the feasibility and accuracy of texture analysis to distinguish through objective and quantitative image information between healthy and infarcted myocardium with computed tomography (CT).Materials and methodsTwenty patients (5 females; mean age 56±10years) with proven acute myocardial infarction (MI) and 20 patients (8 females; mean age 42±15years) with no cardiac abnormalities (hereafter termed controls) underwent contrast-enhanced cardiac CT. Short axis CT images of the left ventricle (LV) were reconstructed at the slice thicknesses 1mm, 2mm, and 5mm. Two independent, blinded readers segmented the LV in controls and patients. Texture analysis was performed yielding first-level features based on the histogram (variance, skewness, kurtosis, entropy), second-level features based on the gray-level co-occurrence matrix (GLCM) (contrast, correlation, energy and homogeneity), and third-level features based on the gray-level run-length matrix (GLRLM).ResultsInter-and intrareader agreement was good to excellent for all histogram (intraclass correlation coefficient (ICC):0.70–0.93) and for all GLCM features (ICC:0.66–0.99), and was variable for the GLRLM features (ICC:-0.12–0.99). Univariate analysis showed significant differences between patients and controls for 2/4 histogram features, 3/4 GLCM and for 6/11 GLRLM features and all assessed slice thicknesses (all,p<0.05). In a multivariate logistic regression model, the single best variable from each level, determined by ROC analysis, was included stepwise. The best model included kurtosis (OR 0.08, 95%CI:0.01–0.65,P = 0.018) and short run high gray-level emphasis (SRHGE, OR 0.97, 95%CI:0.94–0.99,P = 0.007), with an area-under-the-curve (AUC) of 0.90 (95%CI:0.80–0.99). The best results for kurtosis and SRHGE (AUC = 0.78) were obtained at a 5mm slice thickness. A cut-off value of 14.4 for kurtosis+0.013*SRHGE predicted acute MI with a sensitivity of 95% (specificity 55%).ConclusionOur study illustrates the feasibility of texture analysis for distinguishing healthy from acutely infarcted myocardium with cardiac CT using objective, quantitative features, with most reproducible and accurate results at a short axis slice thickness of 5mm.