The role of computed tomography in pre-procedural planning of cardiovascular surgery and intervention

Accuracy of a deep learning-based algorithm for the detection of thoracic aortic calcifications in chest computed tomography and cardiovascular surgery planning

OBJECTIVES

To assess the accuracy of a deep learning-based algorithm for fully automated detection of thoracic aortic calcifications in chest computed tomography (CT) with a focus on the aortic clamping zone.

METHODS

We retrospectively included 100 chest CT scans from 91 patients who were examined on second- or third-generation dual-source scanners. Subsamples comprised 47 scans with an electrocardiogram-gated aortic angiography and 53 unenhanced scans. A deep learning model performed aortic landmark detection and aorta segmentation to derive 8 vessel segments. Associated calcifications were detected and their volumes measured using a mean-based density thresholding. Algorithm parameters (calcium cluster size threshold, aortic mask dilatation) were varied to determine optimal performance for the upper ascending aorta that encompasses the aortic clamping zone. A binary visual rating served as a reference. Standard estimates of diagnostic accuracy and inter-rater agreement using Cohen's Kappa were calculated.

RESULTS

Thoracic aortic calcifications were observed in 74% of patients with a prevalence of 27-70% by aorta segment. Using different parameter combinations, the algorithm provided binary ratings for all scans and segments. The best performing parameter combination for the presence of calcifications in the aortic clamping zone yielded a sensitivity of 93% and a specificity of 82%, with an area under the receiver operating characteristic curve of 0.874. Using these parameters, the inter-rater agreement ranged from κ 0.66 to 0.92 per segment.

CONCLUSIONS

Fully automated segmental detection of thoracic aortic calcifications in chest CT performs with high accuracy. This includes the critical preoperative assessment of the aortic clamping zone.

Routine preoperative screening computed tomography of the thorax for cardiac surgery

Introduction

This study aimed to evaluate the role of screening computed tomography (CT) of the thorax in cardiac surgery by analysing the presence of CT aortic calcifications in association with changes in operative strategy and postoperative stroke, and the CT features of emphysema with development of pneumonia.

Methods

All patients who underwent cardiac surgery from January 2013 to October 2017 by a single surgeon were retrospectively studied. Patients who underwent screening CT thorax before cardiac surgery (CT group) were compared to those who did not (no CT group). Multivariate subgroup analyses were performed to determine significant association with postoperative outcomes.

Results

A total of 392 patients were included, of which 156 patients underwent preoperative screening CT thorax. Patients in the CT group were older (63.9 vs. 59.0 years, P = 0.001), had fewer recent myocardial infarctions preoperatively (41% vs. 56.4%, P = 0.003) and had better ejection fraction (>30%; P = 0.02). Operative strategy was changed in 4.3% of patients, and 4.9% of patients suffered stroke postoperatively. The presence of CT aortic calcifications was significantly associated with change in operative strategy (P = 0.016) but not with postoperative stroke (P = 0.33). Age was an independent risk factor for change in operative strategy among patients with CT thorax (P = 0.02). Multivariate age-adjusted analysis showed only palpable plaque to be significantly associated with change in operative strategy (P < 0.001). None of the patients with CT emphysema features developed pneumonia.

Conclusion

The results of this study do not support routine use of preoperative screening CT thorax. Contrasted CT may be advisable in older patients and for other operative planning purposes.

Early Biological Valve Failure: Structural Valve Degeneration, Thrombosis, or Endocarditis?

Biological valve failure (BVF) is an inevitable condition that compromises the durability of biological heart valves (BHVs). It stems from various causes, including rejection, thrombosis, and endocarditis, leading to a critical state of valve dysfunction. Echocardiography, cardiac computed tomography, cardiac magnetic resonance, and nuclear imaging play pivotal roles in the diagnostic multimodality workup of BVF. By providing a comprehensive overview of the pathophysiology of BVF and the diagnostic approaches in different clinical scenarios, this review aims to aid clinicians in their decision-making process. The significance of early detection and appropriate management of BVF cannot be overstated, as these directly impact patients' prognosis and their overall quality of life. Ensuring timely intervention and tailored treatments will not only improve outcomes but also alleviate the burden of this condition on patients' life. By prioritizing comprehensive assessments and adopting the latest advancements in diagnostic technology, medical professionals can significantly enhance their ability to manage BVF effectively.

The routine use of preoperative non-contrast chest computerized tomography and carotid arteries Doppler prior to cardiac surgery

Introduction

There is no consensus as to which patients should undergo Non-Contrast Chest Computerized Tomography (NCCCT) and carotid arteries Doppler (CD) prior to cardiac surgery. The objective of this study was to examine whether preoperative imaging modalities provide clinical benefits and a change in surgical strategy.

Methods

We routinely performed NCCCT and CD in all non-urgent cardiac surgery patients. Major NCCCT/CD findings related to cardiovascular findings (aortic calcification/atherosclerosis, carotid artery plaque/stenosis), or other incidental findings (lung kidney, thyroid, adrenal, gastrointestinal sites etc.) were documented. The results were divided into 3 categories: (A) findings requiring both changes in surgical strategy and post-operative evaluation/treatment; (B) findings requiring changes in surgical strategy, but not requiring a specific post-operative evaluation/treatment; (C) findings not requiring changes in surgical strategy but requiring post-operative evaluation/treatment.

Results

In this cohort, 93 (18.6%) out of 500 patients had significant cardiac and extra-cardiac findings on NCCCT and/or CD. Among the 93 patients with significant findings, 33.33% (31 patients, 6.2% of all patients) were in group A, 7.5% (7 patients, 1.4% of all patients) were in group B, and 59.14% (55 patients, 11% of all patients) were in group C. Change in surgical strategies included, for example, switching from planned on-pump Coronary Artery Bypass Graft surgery (CABG) to off-pump CABG and performing additional procedures to the originally planned heart surgery.

Conclusion

Routine preoperative NCCCT and CD evaluation in all non-urgent cardiac surgical patients is an effective measure for uncovering cardiac and extra-cardiac findings prior to surgery.

Role of computed tomography in transcatheter replacement of 'other valves': a comprehensive review of preprocedural imaging

Transcatheter procedures for heart valve repair or replacement represent a valid alternative for treating patients who are inoperable or at a high risk for open-heart surgery. The transcatheter approach has become predominant over surgical intervention for aortic valve disease, but it is also increasingly utilized for diseases of the 'other valves', that is the mitral and, to a lesser extent, tricuspid and pulmonary valve. Preprocedural imaging is essential for planning the transcatheter intervention and computed tomography has become the main imaging modality by providing information that can guide the type of treatment and choice of device as well as predict outcome and prevent complications. In particular, preprocedural computed tomography is useful for providing anatomic details and simulating the effects of device implantation using 3D models. Transcatheter mitral valve replacement is indicated for the treatment of mitral regurgitation, either primary or secondary, and computed tomography is crucial for the success of the procedure. It allows evaluating the mitral valve apparatus, the surrounding structures and the left heart chambers, identifying the best access route and the landing zone and myocardial shelf, and predicting obstruction of the left ventricular outflow tract, which is the most frequent postprocedural complication. Tricuspid valve regurgitation with or without stenosis and pulmonary valve stenosis and regurgitation can also be treated using a transcatheter approach. Computer tomography provides information on the tricuspid and pulmonary valve apparatus, the structures that are spatially related to it and may be affected by the procedure, the right heart chambers and the right ventricular outflow tract.

Cannulation strategies in aortic surgery: techniques and decision making

Arterial cannulation for cardiopulmonary bypass (CPB) is an important determinant of outcome in aortic surgery. Unlike traditional cardiac operations, aortic pathology may preclude the cannulation of the distal ascending aorta. In other cases, special need of the pathology/operation may demand an alternative cannulation site. Choosing the right cannulation site, especially in type A aortic dissection, is the most crucial initial step. The decision about cannulation sites should be individualized and patient-specific. Various cannulation techniques include femoral, right axillary, innominate, carotid, central aortic, direct true lumen, transapical, and trans-atrial left ventricle cannulation. The ideal cannulation should be easy, quick, and suitable for all clinical scenarios. It should allow smooth conduct of CPB without malperfusion or cerebral embolization. The cannulation strategy should also provide an option for selective antegrade cerebral perfusion and it should be free from neurovascular and local site complications. There is no ideal cannulation technique. Each technique has its pros and cons. Excellent results and drawbacks have been reported with each technique. Final selection of the cannulation site is dependent upon several factors. However, a surgeon's familiarity with a particular technique plays a major role in selection. Despite this, there is a definite shift in surgeons' preference from femoral to central cannulation (axillary, carotid, innominate, aortic) over the last few decades. The aim of this review is to give a brief overview of the cannulation techniques in aortic surgery and discuss the decision-making process.

A study on origin, termination, and course characteristics of internal thoracic artery relevant to coronary surgeries and reconstructive procedures

Objectives:

The internal thoracic artery is a favored vessel for coronary artery bypass grafting and is utilized for breast reconstructive surgeries. Our study focuses on the origin, termination, and course characteristics of the internal thoracic artery. A comprehension of these morphological features and possible variations will definitely aid a clinician in appropriate harvesting of the artery for clinical procedures.

Materials and Methods:

200 thoracic halves (from 100 embalmed adult human cadavers of either sex) were obtained from the department of anatomy. The origin, course characteristics, termination levels, and patterns for the internal thoracic artery were studied.

Results:

The internal thoracic artery originated from the first part of subclavian artery. The most common course pattern observed was medial concavity (88.5%). In 10% of cases, a tortuous course was observed. No artery with lateral concavity or rectilinear course pattern was documented. The artery terminated in the sixth space in 93.5% of cases. In 98% of cases, bifurcation in termination was observed. Trifurcation in termination was also observed in 2% of cases. The average length of variant artery (third terminating branch) was documented to be 5.5 cm.

Conclusion:

The increased utilization of the internal thoracic artery for coronary bypass arterial surgery and its role in sternal wound healing has made it imperative for clinicians to keep in mind its anatomical characteristics and local variations. This knowledge definitely will improve prognosis and decrease intraoperative/postoperative complications in patients undergoing coronary surgeries, percutaneous subclavian catheterizations, and reconstructive procedures.

Challenging Cases of Aortic Prosthesis Dysfunction, the Importance of Multimodality Imaging, a Case Series

ECG-gated multidetector computed tomography (MDCT) is a promising complementary technique for evaluation of cardiac native and prosthetic structures. MDCT is able to provide a broader coverage with faster scan acquisition times that yield higher spatial and temporal resolution for cardiac structures whose quality may be affected by artifacts on ultrasound. We report a case series about the most challenging complications occurring after prosthetic aortic valve implantation in four patients: pannus, paravalvular leak, prosthesis’ misfolding and subaortic membrane reformation. In all the cases, enhanced MDCT using a retrospective protocol provided accurate 3D morphoanatomic information about cardiac and extracardiac structures, improving and speeding up the correct diagnosis and treatment planning. Integrated imaging, in particular with MDCT, is now the present, and it will increasingly be the future in the assessment of cardiac structural pathology.

Deep learning method for aortic root detection

BACKGROUND

Computed tomography angiography (CTA) is a preferred imaging technique for a wide range of vascular diseases. However, extensive manual analysis is required to detect and identify several anatomical landmarks for clinical application. This study demonstrates the feasibility of a fully automatic method for detecting the aortic root, which is a key anatomical landmark in this type of procedure. The approach is based on the use of deep learning techniques that attempt to mimic expert behavior.

METHODS

A total of 69 CTA scans (39 for training and 30 for validation) with different pathology types were selected to train the network. Furthermore, a total of 71 CTA scans were selected independently and applied as the test set to assess their performance.

RESULTS

The accuracy was evaluated by comparing the locations marked by the method with benchmark locations (which were manually marked by two experts). The interobserver error was 4.6 ± 2.3 mm. On an average, the differences between the locations marked by the two experts and those detected by the computer were 6.6 ± 3.0 mm and 6.8 ± 3.3 mm, respectively, when calculated using the test set.

CONCLUSIONS

From an analysis of these results, we can conclude that the proposed method based on pre-trained CNN models can accurately detect the aortic root in CTA images without prior segmentation.

The role of CT in planning percutaneous structural heart interventions: Where to measure and why

As research continues to demonstrate successes in the use of percutaneous trans-vascular techniques in structural heart intervention, both the subspecialty trained and non-subspecialty trained cardiac imager find themselves performing and reporting larger amounts of information regarding cardiovascular findings. It is therefore imperative that the imager gains understanding and appreciation for how these various measurements are obtained, as well as their implication in a patient's care. Cardiac gated computed tomography (CT) has solidified its role and ability at providing high resolution images that can be used to obtain the key measurements used in structural heart intervention planning. This manuscript aims to provide an overview of what measurements are necessary to report when interpreting CT examinations purposed for structural heart intervention. This includes a review on indications and brief discussion on complications related to these procedures.

ACR Appropriateness Criteria® Nontraumatic Aortic Disease

Nontraumatic aortic disease can be caused by a wide variety of disorders including congenital, inflammatory, infectious, metabolic, neoplastic, and degenerative processes. Imaging examinations such as radiography, ultrasound, echocardiography, catheter-based angiography, CT, MRI, and nuclear medicine examinations are essential for diagnosis, treatment planning, and assessment of therapeutic response. Depending upon the clinical scenario, each of these modalities has strengths and weaknesses. Whenever possible, the selection of a diagnostic imaging examination should be based upon the best available evidence. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. The purpose of this document is to assist physicians select the most appropriate diagnostic imaging examination for nontraumatic aortic diseases.

Preoperative Computed Tomography in the Adult Cardiac Surgery Patient

Increasingly, computed tomography is requested for preoperative planning prior to cardiac surgery. Common pathologies, such as aortic and mitral annular calcification, can influence the choice of surgical technique or approach. In this article, we present a case-based review of primary and reoperative sternotomies that focuses on the clinical relevance of the common pathologies and findings in pre-operative computed tomography images, with respect to surgical decision-making and management.

Cardiovascular imaging modalities in the diagnosis and management of rheumatic heart disease

Rheumatic heart disease (RHD) is prevalent in sub-Saharan Africa, where the capacity for diagnosis and evaluation of disease severity and complications is not always optimal. While the medical history and physical examination are important in the assessment of patients suspected to have RHD, cardiovascular imaging techniques are useful for confirmation of the diagnosis. Echocardiography is the workhorse modality for initial evaluation and diagnosis of RHD. Cardiovascular magnetic resonance is complementary and may provide additive information, including tissue characteristics, where echocardiography is inadequate or non-diagnostic. There is emerging evidence on the role of computed tomography, particularly following valve replacement surgery, in the monitoring and management of RHD. This article summarises the techniques used in imaging RHD patients, considers the evidence base for their utility, discusses their limitations and recognises the clinical contexts in which indications and imaging with various modalities are expanding.

Cardiothoracic Morphology Measures in Heart Failure Patients to Inform Device Designs

PURPOSE

Approximately 5.7 million people in the US are affected by congestive heart failure. This study aimed to quantitatively evaluate cardiothoracic morphology and variability within a cohort of heart failure patients for the purpose of optimally engineering cardiac devices for a variety of heart failure patients.

METHODS

Co-registered cardiac-gated and non-gated chest computed tomography (CT) scans were analyzed from 20 heart failure patients (12 males; 8 females) who were primarily older adults (79.5 ± 8.8 years). Twelve cardiothoracic measurements were collected and compared to study sex and left ventricular (LV) ejection fraction (EF) type differences in cardiothoracic morphology.

RESULTS

Four measures were significantly greater in males compared to females: LV long-axis length, LV end diastolic diameter (LVEDD) at 50% length of the LV long-axis, the minimal distance between the sternum and heart, and the angle between the LV long-axis and coronal plane. Four measures were significantly greater in patients with reduced EF compared to preserved LV: LV long-axis length, LVEDD at 50% length of the LV long-axis, left ventricular volume normalized by body surface area, and the angle between the mitral valve plane and LV long-axis.

CONCLUSIONS

These cardiothoracic morphology measurements are important to consider in the design of cardiac devices for heart failure management (e.g. cardiac pacemakers, ventricular assist devices, and implantable defibrillators), since morphology differs by sex and ejection fraction.

Using coronary CT angiography for guiding invasive coronary angiography: potential role to reduce intraprocedural radiation exposure

OBJECTIVES

We investigated the potential reduction of patient exposure during invasive coronary angiography (ICA) if the procedure had only been directed to the vessel with at least one ≥ 50% stenosis as described in the CT report.

METHODS

Dose reports of 61 patients referred to ICA because of at least one ≥ 50% stenosis on coronary CT angiography (CCTA) were included. Dose-area product (DAP) was documented separately for left (LCA) and right coronary arteries (RCA) by summing up the single DAP for each angiographic projection. The study population was subdivided as follows: coronary intervention of LCA (group 1) or RCA (group 2) only, or of both vessels (group 3), or further bypass grafting (group 4), or no further intervention (group 5).

RESULTS

57.4% of the study population could have benefitted from reduced exposure if catheterization had been directly guided to the vessel of interest as described on CCTA. Mean relative DAP reductions were as follows: group 1 (n = 18), 11.2%; group 2 (n = 2), 40.3%; group 3 (n = 10), 0%; group 4 (n = 3), 0%; group 5 (n = 28), 28.8%.

CONCLUSIONS

Directing ICA to the vessel with stenosis as described on CCTA would reduce intraprocedural patient exposure substantially, especially for patients with single-vessel stenosis.

KEY POINTS

• Patients with CAD can benefit from decreased radiation exposure during coronary angiography. • ICA should be directed solely to significant stenoses as described on CCTA. • Severely calcified plaques remain a limitation of CCTA leading to unnecessary ICA referrals.

Frequency of sternal variations in living individuals

PURPOSE

To evaluate the variations of the sternum and provide the prevalence of sternal foramen and its anatomical relationships.

METHODS

In this retrospective study, 544 subjects ranging in age from 18 to 95 years were evaluated. Sternal variations, prevalence of sternal foramen and its anatomical relationships to mediastinal structures were examined with the axial, sagittal and coronal reformat images of the patients who underwent thoracic computerized tomography.

RESULTS

In 500 subjects, following sternal variations were found: sternal sclerotic band in 120 (24%), sternal cleft in 3 (0.6%), sternal foramen in 26 (5.2%), focal cortical notch and defect in 44 (8.8%) patients. The manubriosternal fusion was partial in 65 (13%) patients and complete in 112 (22.4%) patients. The sternoxiphoid fusion was partial in 201 (40.2%) and complete in 153 (30.6%) patients. There was no xiphoid process in 9 patients (1.8%; 29-51 years; mean age 38 years). Xiphoidal ending types were as follows: single-ended 361 (72.2%), double-ended 125 (25%), and triple-ended xiphoid 5 (1%) patients. The sternal foramen was adjacent to the lung in 13 (2.6%), to the pericardium of heart in 3 (0.6%), and to mediastinal fat in 10 (2%) patients.

CONCLUSION

The sternum is a very critical anatomic structure of the anterior chest wall with several variations that can be confused with pathologic conditions. Radiologists' familiarity with these variations is important for better radiologic evaluation in making differential diagnosis.

Low Radiation Dose Calcium Scoring: Evidence and Techniques

Coronary computed tomography (CT) allows for the acquisition of thin slices of the heart and coronary arteries, which can be used to detect and quantify coronary artery calcium (CAC), a marker of atherosclerotic cardiovascular disease. Despite the proven clinical value in cardiac risk prognostication, there remain concerns regarding radiation exposure from CAC CT scans. There have been several recent technical advancements that allow for significant radiation dose reduction in CAC scoring. This paper reviews the clinical utility and recent literature in low radiation dose CAC scoring.

Automatic aortic root landmark detection in CTA images for preprocedural planning of transcatheter aortic valve implantation

Transcatheter aortic valve implantation is currently a well-established minimal invasive treatment option for patients with severe aortic valve stenosis. CT Angiography is used for the pre-operative planning and sizing of the prosthesis. To reduce the inconsistency in sizing due to interobserver variability, we introduce and evaluate an automatic aortic root landmarks detection method to determine the sizing parameters. The proposed algorithm detects the sinotubular junction, two coronary ostia, and three valvular hinge points on a segmented aortic root surface. Using these aortic root landmarks, the automated method determines annulus radius, annulus orientation, and distance from annulus plane to right and left coronary ostia. Validation is performed by the comparison with manual measurements of two observers for 40 CTA image datasets. Detection of landmarks showed high accuracy where the mean distance between the automatically detected and reference landmarks was 2.81 ± 2.08 mm, comparable to the interobserver variation of 2.67 ± 2.52 mm. The mean annulus to coronary ostium distance was 16.9 ± 3.3 and 17.1 ± 3.3 mm for the automated and the reference manual measurements, respectively, with a mean paired difference of 1.89 ± 1.71 mm and interobserver mean paired difference of 1.38 ± 1.52 mm. Automated detection of aortic root landmarks enables automated sizing with good agreement with manual measurements, which suggests applicability of the presented method in current clinical practice.

Detecting Aortic Graft Complications: A Spectrum of Computed Tomography Findings

Endovascular aneurysm repair (EVAR) is a successful technique as well as an excellent alternative to the surgical management of abdominal aortic aneurysms. EVAR has improved the mortality and morbidity of many patients who would have otherwise suffered greatly from the consequences of abdominal aortic aneurysms. However, EVAR is not without complications. Some complications require lifelong surveillance, whereas others may necessitate immediate surgical intervention. We discuss the various modalities available for the surveillance as well as the common complications that can be seen on computed tomography.

Role of CT angiography for detection of coronary atherosclerosis

As laparoscopic surgery is replacing open surgery, similarly computed tomography angiography is replacing invasive conventional cardiac angiography. In the last century, marvelous efforts in research have improved strategies for cure, diagnosis and prevention of fatal human diseases; however, coronary artery disease, as the most prevalent cause of mortality and morbidity in the world, has remained a great challenge. Due to advancements in technology and research, it has become more simple and robust to diagnose and treat coronary artery disease (CAD) with minimal or no intervention, promising to not only diagnosis at an early stage but potential prevention altogether. While most with obvious CAD can be diagnosed easily and quickly with ECG, those identified as 'low risk' require more extensive testing to diagnose or rule out CAD. For example in emergency departments, low-risk patients with chest pain are diagnosed solely depending on history, ECG and blood testing for biomarkers. This approach has resulted in either delayed or miss-diagnosis of Acute coronary syndrome. To prevent this, many emergency departments now use protocols for low-risk heart patients that include cardiac stress tests and/or CT heart imaging. This review provides an overview of the current literature on the value of Computed tomography angiography and discusses how prognostic information obtained with Computed tomography angiography can be used to further integrate the technique into clinical practice.