Late-onset left atrial appendage occlusion device-related thrombus attributed to mitral bioprosthetic stenosis: a case report.

Background: Left atrial appendage occlusion (LAAO) is an alternative to anticoagulation for stroke prevention in select patients with atrial fibrillation (AF). In this study, we describe the case of a patient with delayed device-related thrombus (DRT) at 13 months post-LAAO in a setting of atrial stasis due to a worsening mitral bioprosthetic stenosis. Case summary: A 69-year-old woman with a history of rheumatic mitral stenosis and regurgitation post-bioprosthetic mitral valve replacement (6 years prior) and paroxysmal AF was referred for percutaneous LAAO due to recurrent severe gastrointestinal bleeding while on anticoagulation. She underwent an uncomplicated LAAO, for which a 35 mm Watchman Flx device was used. Peri-procedural transoesophageal echocardiogram (TEE) at the time of implant showed thickened and calcified mitral bioprosthetic leaflets and a mild mitral stenosis. Her 45-day post-LAAO TEE showed a mild mitral stenosis and no peri-device leak or DRT. At 12 months, the patient had worsening exertional dyspnoea and pedal oedema. Her 12-month transthoracic echocardiogram (TTE) showed a moderate mitral stenosis and LAAO remained free of DRT. Her symptoms were deemed secondary from a worsening mitral valve stenosis. Mitral valve-in-valve (MViV) replacement was planned because the patient was deemed a prohibitive risk for a redo surgical replacement. Transthoracic echocardiogram on the day of MViV showed a large thrombus on the LAAO device. MViV was postponed. After the patient completed 45 days of anticoagulation with warfarin, a repeat TTE was performed, which showed a resolution of DRT. Transcatheter MViV was performed successfully. Discussion: This case demonstrates that increased stasis and left atrial dysfunction from prosthetic mitral stenosis can be a risk factor for late DRT after successful LAAO. The use of a LAAO occlusion device in the presence of a mitral bioprosthesis requires more frequent echocardiographic monitoring to assess both the function of the prosthesis and a delayed formation of thrombus. More studies need to be conducted to assess the safety of percutaneous LAAO devices in those with mitral bioprosthesis.

Pulmonary Vein Thrombus After Mitral Valve Transcatheter Edge-to-Edge Repair.

A 76-year-old female with a complicated medical history presented for Watchman (Boston Scientific) placement 2 months after mitral valve transcatheter edge-to-edge repair (TEER). Preoperative workup before Watchman placement confirmed the presence of a thrombus in the left superior pulmonary vein. Post-procedure mitral valve TEER transesophageal echocardiogram showed no thrombus in the left atrium appendage or pulmonary veins. We believe the thrombus in the left superior pulmonary vein occurred secondarily due to epithelium damage during the mitral valve TEER.

A Rare Case of Bivalvular Infective Endocarditis With Left Atrial Mural Endocarditis.

Infective endocarditis (IE) is a life-threatening cardiac infection usually associated with cardiac valves. Left atrial (LA) mural endocarditis is rarely seen and occurs in isolation or in conjunction with mitral valve endocarditis. We present a case of a 61-year-old male with no prior cardiac history who presented with melena and fevers. Blood cultures were positive for Enterococcus faecalis. Transesophageal echocardiogram (TEE) demonstrated aortic and mitral valve vegetations with several small echo densities present on the left atrial wall. These findings were further assessed with a computed tomography angiogram of the heart and cardiac magnetic resonance imaging Ti600 sequence. The patient was treated with intravenous antibiotics and underwent aortic and mitral valve replacement with resection of numerous small fungating masses on the left atrium. There are currently no formal guidelines in place for managing mural endocarditis. However, conducting a multidisciplinary evaluation by an endocarditis team could aid in achieving earlier and more precise diagnoses of the underlying condition and its complications. This approach could also ensure consistent antibiotic therapy and appropriate timing for surgical intervention.

All that Doesn't Enhance Isn't a Thrombus: Pitfalls Using Cardiac MRI TI 600 Sequence to Distinguish Between Cardiac Thrombus Versus Myxoma.

A 51-year-old male with a complicated medical history presented with shortness of breath. Preoperative workup confirmed the presence of a large atrial mass. However, delayed gadolinium enhancement CMR with long inversion time (TI 600) showed lack of enhancement, which was suggestive of a thrombus. During cardiac magnetic resonance imaging, delayed gadolinium enhancement sequences with long inversion time (TI 600) are commonly used to distinguish between an avascular thrombus versus a vascular tumor.

Iodine density mapping for the diagnosis of acute bowel ischemia using fast kV-switching dual-energy CT.

PURPOSE: To evaluate the diagnostic capabilities of a supplementary color ramped iodine density map compared to virtual monoenergetic images (VMIs) at 74 keV in the diagnosis of acute bowel ischemia (ABI). METHODS: Data for this study were prospectively gathered and retrospectively evaluated. Patients referred to the Department of Diagnostic Radiology between October 2020 and August 2022 on the suspicion of ABI and underwent surgery < 12 h following fast kV-switching venous phase abdominal dual-energy CT (DECT) were consecutively included. Images were evaluated by two board-certified radiologists and two radiology residents. First round included only 74 keV VMIs resembling conventional 120 kVp images, and the second round included a supplementary iodine density map. Readers were asked to register presence of ABI as well as their confidence in their diagnosis based on a 5-point Likert scale. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for each observer with the surgical findings as the gold-standard. McNemar's and Wilcoxon signed-rank test were used to compare registrations and diagnostic confidence across assessment rounds. RESULTS: A total of 29 patients resulting in 31 DECT scans were included. Fourteen cases of ischemic/necrotic bowel were reported following surgery. Sensitivity and NPV were decreased with the use of supplementary iodine map images compared to 120 kVp-like images without supplementary iodine map images for three of four observers (round 1 range: 71.4-92.9% and 78.0-94.8%; round 2 range: 57.1-78.6% and 70.1-83.3%, respectively), while specificity and PPV were increased for three of four observers (round 1 range: 64.7-94.1% and 67.4-93.1%; round 2 range: 88.2-94.1% and 73.8-91.1%, respectively). However, no significant difference in ABI diagnosis or diagnostic confidence was found (p-value range: 0.07-1.00 and 0.23-0.58, respectively). CONCLUSION: No significant difference for the diagnosis of ABI was found using supplementary iodine mapping. Our study may suggest a trend of increased specificity and decreased sensitivity, hence, the use of supplementary iodine mapping should be carefully considered.

Reconstruction of the human lower esophageal sphincter based on ultra-mill imaging for biomechanical analysis.

Introduction: The lower esophageal sphincter (LES) controls the passage into the stomach and prevents reflex of contents into the esophagus. Dysfunctions of this region typically involves impairment of muscular function, leading to diseases including gastro-esophageal reflux disease and achalasia. The main objective of this study was to develop a finite element model from a unique human LES dataset reconstructed from an ultra-mill imaging setup, and then to investigate the effect of anatomical characteristics on intraluminal pressures. Methods: A pipeline was developed to generate a mesh from a set of input images, which were extracted from a unique ultra-mill sectioned human LES. A total of 216 nodal points with cubic Hermite basis function was allocated to reconstruct the LES, including the longitudinal and circumferential muscles. The resultant LES mesh was used in biomechanical simulations, utilizing a previously developed LES mathematical model based on the Visible Human data to calculate intraluminal pressures. Anatomical and functional comparisons were made between the Ultra-mill and Visible human models. Results: Overall, the Ultra-mill model contained lower cavity (1,796 vs. 5,400 mm3) and muscle (1,548 vs. 15,700 mm3) volumes than the Visible Human model. The Ultra-mill model also developed a higher basal pressure (13.8 vs. 14.7 mmHg) and magnitude of pressure (19.8 vs. 18.9 mmHg) during contraction. Out of all the geometric transformations (i.e., uniform enlargement of volume, lengthening along the center-axis, dilation of the diameter, and increasing muscle thickness), the muscle volume was found to be the main contributor of basal and magnitude of pressures. Increases in length also caused proportional increases to pressures, while dilation of diameter had a less influential reverse effect. Discussion: The findings provide information on interindividual variability in LES pressure and demonstrates that anatomy has a large influence on pressures. This model forms the basis of more complex simulations involving food bolus transport and predicting LES dysfunctions.

Evaluation of thin-slice abdominal DECT using deep-learning image reconstruction in 74 keV virtual monoenergetic images: an image quality comparison.

PURPOSE: To compare noise, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and image quality using deep-learning image reconstruction (DLIR) vs. adaptive statistical iterative reconstruction (ASIR-V) in 0.625 and 2.5 mm slice thickness gray scale 74 keV virtual monoenergetic (VM) abdominal dual-energy CT (DECT). METHODS: This retrospective study was approved by the institutional review board and regional ethics committee. We analysed 30 portal-venous phase abdominal fast kV-switching DECT (80/140kVp) scans. Data were reconstructed to ASIR-V 60% and DLIR-High at 74 keV in 0.625 and 2.5 mm slice thickness. Quantitative HU and noise assessment were measured within liver, aorta, adipose tissue and muscle. Two board-certified radiologists evaluated image noise, sharpness, texture and overall quality based on a five-point Likert scale. RESULTS: DLIR significantly reduced image noise and increased CNR as well as SNR compared to ASIR-V, when slice thickness was maintained (p < 0.001). Slightly higher noise of 5.5-16.2% was measured (p < 0.01) in liver, aorta and muscle tissue at 0.625 mm DLIR compared to 2.5 mm ASIR-V, while noise in adipose tissue was 4.3% lower with 0.625 mm DLIR compared to 2.5 mm ASIR-V (p = 0.08). Qualitative assessments demonstrated significantly improved image quality for DLIR particularly in 0.625 mm images. CONCLUSIONS: DLIR significantly reduced image noise, increased CNR and SNR and improved image quality in 0.625 mm slice images, when compared to ASIR-V. DLIR may facilitate thinner image slice reconstructions for routine contrast-enhanced abdominal DECT.

Severely Calcified Pericardium Causing Constrictive Pericarditis.

Constrictive pericarditis (CP) is a type of diastolic heart failure caused by an inelastic pericardium that impairs cardiac filling. Diagnosing CP can be challenging, and a variety of imaging techniques may be necessary. We present a unique case of severely calcified pericardium leading to CP.

Gender Differences and Outcomes of Hypoattenuated Leaflet Thickening (HALT) Following Transcatheter Aortic Valve Replacement: A Meta-analysis of Randomized and Cohort Studies.

Subclinical leaflet thrombosis is characterized by hypoattenuated leaflet thickening (HALT) after transcatheter aortic valve replacement (TAVR) on computed tomography. However, given the low incidence of HALT after TAVR, the clinical significance of HALT is still being investigated. We sought to generate a more reliable estimate of the risk factors and adverse outcomes associated with HALT after TAVR by pooling data from randomized trials and cohort studies. PubMed/Medline database was systematically searched from inception until November 24, 2021, using the following terms: ("hypoattenuated leaflet thickening" and "transcatheter aortic valve replacement") and ("Subclinical leaflet thrombosis" and "transcatheter aortic valve replacement"). A random effects model meta-analysis was conducted using Mantel-Haenszel odds ratios (ORs) and the associated 95% confidence intervals (CIs), mean difference and the associated 95%. Ten studies with a total of 1462 patients were included, with follow-up ranging between 4 months and 3 years. HALT occurred in 14.4% of the patients undergoing TAVR. HALT was not associated with increased risk of stroke/TIA (OR 1.38; 95% CI [0.61-3.11]; I2=0%) or increased risk of all-cause mortality (OR 0.67; 95% CI [0.25-1.80]; I2=0). HALT was associated with a greater post-procedural mean aortic valve gradient (mean difference 2.31 mmHg; 95% CI [0.27, 4.35]; I2=71%). Interestingly, there was a trend of higher risk of HALT in men (OR 1.37; 95% CI [0.82-2.30]; I2=44%) while there was a trend towards lower risk of HALT in the presence of CKD (OR 0.76; 95% CI [0.49-1.19]; I2=0%); these trends did not reach statistical significance. This meta-analysis shows that the occurrence of HALT following TAVR is associated with a greater post-procedural mean aortic valve gradient but no excess risk of death or cerebrovascular events. The clinical significance of this higher post-procedural mean aortic valve gradient is uncertain and requires further investigations.

Characterizing incidental mass lesions in abdominal dual-energy CT compared to conventional contrast-enhanced CT.

BACKGROUND: Incidental findings are common in abdominal computed tomography (CT) and often warrant further investigations with economic implications as well as implications for patients. PURPOSE: To evaluate the potential of dual-energy CT (DECT) in the identification and/or characterization of abdominal incidental mass lesions compared to conventional contrast-enhanced CT. MATERIAL AND METHODS: This retrospective study from a major tertiary hospital included 96 patients, who underwent contrast-enhanced abdominal DECT. Incidental lesions in adrenals, kidneys, liver, and pancreas were evaluated by two board-certified abdominal radiologists. Observer 1 only had access to standard CT reconstructions, while observer 2 had access to standard CT as well as DECT reconstructions. Disagreements were resolved by consensus review and used as a reference for observers using McNemar's test. RESULTS: Observers 1 and 2 identified a total of 40 and 34 findings, respectively. Furthermore, observer 1 registered 13 lesions requiring follow-up, of which seven (two renal and five adrenal lesions) were resolved following consensus review using DECT (P = 0.008). The inter-observer agreement was near perfect (κ = 0.82). CONCLUSION: DECT has the potential to improve the immediate characterization of incidental findings when compared to conventional CT for abdominal imaging.

Percutaneous Management of Bioprosthetic Mitral Valve Dehiscence with Combined Valve-in-Valve Replacement and Paravalvular Leak Closure.

This case report describes a patient with bioprosthetic mitral valve dehiscence that resulted in severe paravalvular regurgitation and cardiogenic shock. Due to prohibitive surgical risk, valve-in-valve transcatheter mitral valve replacement was attempted but did not reduce the severity of the prosthetic paravalvular leak (PVL) severity. Subsequent percutaneous PVL closure with a ventricular septal defect occluder successfully reduced the PVL severity and led to significant clinical improvement.

Reconstruction of the Gastro-esophageal Junction Based on Ultramill Imaging for Biomechanical Analysis.

The gastro-esophageal junction (GEJ) regulates the entry of food into the stomach and prevents reflux of acidic gastric contents into the lower esophagus. This is achieved through multiple mechanisms and the maintenance of a localized high-pressure zone. Diseases of the GEJ typically involve impairments to its muscular functions and often are accompanied by symptoms of reflux, heartburn, and dysphagia. This study aimed to develop a finite element-based model from a unique human cadaver GEJ data reconstructed from an ultramill imaging setup. A pipeline was developed to generate a mesh from an input stack of images. The anatomy of the model was compared to an existing Visible Human finite element GEJ model. Biomechanical simulations were also performed on both models using loading steps of differing levels of calcium to model different levels of contraction. It was found that the ultramill GEJ model is shorter than the Visible Human model (31 vs 48.3 mm), as well as producing lower pressure (1.35 vs 4.36 kPa). The model will be used to investigate detailed pressure development in the GEJ during swallowing under realistic loading conditions. Clinical Relevance - The modeling of the GEJ would allow further insights into pressure influencing factors and aid in the development and testing of treatments.

Percutaneous Aspiration (AngioVac) of a Mitral Valve Vegetation followed by a Transcatheter Mitral Valve-in-Valve Intervention.

The AngioVac transcatheter aspiration system (Angiodynamics) is used to percutaneously extract thrombi as well as vegetations typically growing from the right heart. We report a case of a failed mitral stented bioprosthesis due to a large vegetation that was treated successfully with AngioVac evacuation through a transseptal puncture followed by valve-in-valve intervention in the same setting.

Quantitative and qualitative assessments of deep learning image reconstruction in low-keV virtual monoenergetic dual-energy CT.

OBJECTIVES: To evaluate a novel deep learning image reconstruction (DLIR) technique for dual-energy CT (DECT) derived virtual monoenergetic (VM) images compared to adaptive statistical iterative reconstruction (ASIR-V) in low kiloelectron volt (keV) images. METHODS: We analyzed 30 venous phase acute abdominal DECT (80/140 kVp) scans. Data were reconstructed to ASIR-V and DLIR-High at four different keV levels (40, 50, 74, and 100) with 1- and 3-mm slice thickness. Quantitative Hounsfield unit (HU) and noise assessment were measured within the liver, aorta, fat, and muscle. Subjective assessment of image noise, sharpness, texture, and overall quality was performed by two board-certified radiologists. RESULTS: DLIR reduced image noise by 19.9-35.5% (p < 0.001) compared to ASIR-V in all reconstructions at identical keV levels. Contrast-to-noise ratio (CNR) increased by 49.2-53.2% (p < 0.001) in DLIR 40-keV images compared to ASIR-V 50 keV, while no significant difference in noise was identified except for 1 and 3 mm in aorta and for 1-mm liver measurements, where ASIR-V 50 keV showed 5.5-6.8% (p < 0.002) lower noise levels. Qualitative assessment demonstrated significant improvement particularly in 1-mm reconstructions (p < 0.001). Lastly, DLIR 40 keV demonstrated comparable or improved image quality ratings when compared to ASIR-V 50 keV (p < 0.001 to 0.22). CONCLUSION: DLIR significantly reduced image noise compared to ASIR-V. Qualitative assessment showed that DLIR significantly improved image quality particularly in thin sliced images. DLIR may facilitate 40 keV as a new standard for routine low-keV VM reconstruction in contrast-enhanced abdominal DECT. KEY POINTS: • DLIR enables 40 keV as the routine low-keV VM reconstruction. • DLIR significantly reduced image noise compared to ASIR-V, across a wide range of keV levels in VM DECT images. • In low-keV VM reconstructions, improvements in image quality using DLIR were most evident and consistent in 1-mm sliced images.

Assessment of Liver Fat: Dual-Energy CT versus Conventional CT with and without Contrast.

We assessed the correlation between liver fat percentage using dual-energy CT (DECT) and Hounsfield unit (HU) measurements in contrast and non-contrast CT. This study included 177 patients in two patient groups: Group A (n = 125) underwent whole body non-contrast DECT and group B (n = 52) had a multiphasic DECT including a conventional non-contrast CT. Three regions of interest were placed on each image series, one in the left liver lobe and two in the right to measure Hounsfield Units (HU) as well as liver fat percentage. Linear regression analysis was performed for each group as well as combined. Receiver operating characteristic (ROC) curve was generated to establish the optimal fat percentage threshold value in DECT for predicting a non-contrast threshold of 40 HU correlating to moderate-severe liver steatosis. We found a strong correlation between fat percentage found with DECT and HU measured in non-contrast CT in group A and B individually (R2 = 0.81 and 0.86, respectively) as well as combined (R2 = 0.85). No significant difference was found when comparing venous and arterial phase DECT fat percentage measurements in group B (p = 0.67). A threshold of 10% liver fat found with DECT had 95% sensitivity and 95% specificity for the prediction of a 40 HU threshold using non-contrast CT. In conclusion, liver fat quantification using DECT shows high correlation with HU measurements independent of scan phase.

Caseous Calcification: Now You See Me, Now You Don't.

Caseous calcification of mitral annulus is a rare variant of mitral annulus calcification that can mimic infective endocarditis, myocardial abscess, valve myxoma, or papillary fibroelastoma. On transthoracic echocardiography, the mass appears as a large, round echodense structure with a large calcification and central echolucency. We present a case of a 72-year-old female with a past medical history significant for diabetes mellitus, hypertension, and end-stage renal disease who was noted to have caseous calcification of the mitral annulus on transthoracic echocardiography, which was done as part of a preoperative kidney transplantation evaluation. The mass spontaneously resolved before the planned mitral valve surgery. Caseous calcification of mitral annulus should be considered in the differential for a cardiac mass, particularly if it is attached to the posterior aspect of the mitral valve. Accurate identification of this rare cardiac mass is essential to avoid unnecessary surgical intervention as clinical course is usually benign.

Coronary-Cameral Fistula, Thebesian Veins, and Anomalous Coronary Vein on Cardiac Computed Tomography.

A 63-year-old female with a history of hypertension presented with progressively worsening shortness of breath. She underwent a cardiac catheterization and was found to have prominent Thebesian veins as well as anomalous connections between the proximal right coronary artery and the right ventricle. Cardiac computed tomography was ordered for further evaluation and showed a coronary fistula to the right ventricular outflow tract confirming the diagnosis of a coronary-cameral fistula (CCF). CCF are rare congenital anomalous communications that occur between coronary arteries and a cardiac chamber. They are usually an incidental finding and patients are rarely symptomatic. As the use of coronary computed tomography angiography is rapidly expanding, the detection of CCF will likely increase in the general population.

[Dual-energy CT].

Dual-energy CT (DECT) is an emerging imaging technique and has become increasingly available in Danish hospitals in recent years. DECT utilizes data acquired from high and low kV photons. This allows for the separation of materials based on their atomic buildup, which can be visualised and quantified during post-processing. DECT entails a broad range of clinical applications across multiple organ systems and can support diagnostic decision-making as described in this review. DECT is not yet widely utilised mainly due to limited knowledge combined with a new workflow for the radiologist.

Gastrointestinal Applications of Iodine Quantification Using Dual-Energy CT: A Systematic Review.

Dual-energy computed tomography (DECT) can estimate tissue vascularity and perfusion via iodine quantification. The aim of this systematic review was to outline current and emerging clinical applications of iodine quantification within the gastrointestinal tract using DECT. The search was conducted with three databases: EMBASE, Pubmed and The Cochrane Library. This identified 449 studies after duplicate removal. From a total of 570 selected studies, 30 studies were enrolled for the systematic review. The studies were categorized into four main topics: gastric tumors (12 studies), colorectal tumors (8 studies), Crohn's disease (4 studies) and miscellaneous applications (6 studies). Findings included a significant difference in iodine concentration (IC) measurements in perigastric fat between T1-3 vs. T4 stage gastric cancer, poorly and well differentiated gastric and colorectal cancer, responders vs. non-responders following chemo- or chemoradiotherapy treatment among cancer patients, and a positive correlation between IC and Crohn's disease activity. In conclusion, iodine quantification with DECT may be used preoperatively in cancer imaging as well as for monitoring treatment response. Future studies are warranted to evaluate the capabilities and limitations of DECT in splanchnic flow.