CT for Pre- and Postprocedural Evaluation of Transcatheter Mitral Valve Replacement

Deep learning-based post hoc denoising for 3D volume-rendered cardiac CT in mitral valve prolapse

We hypothesized that deep learning-based post hoc denoising could improve the quality of cardiac CT for the 3D volume-rendered (VR) imaging of mitral valve (MV) prolapse. We aimed to evaluate the quality of denoised 3D VR images for visualizing MV prolapse and assess their diagnostic performance and efficiency. We retrospectively reviewed the cardiac CTs of consecutive patients who underwent MV repair in 2023. The original images were iteratively reconstructed and denoised with a residual dense network. 3DVR images of the "surgeon's view" were created with blood chamber transparency to display the MV leaflets. We compared the 3DVR image quality between the original and denoised images with a 100-point scoring system. Diagnostic confidence for prolapse was evaluated across eight MV segments: A1-3, P1-3, and the anterior and posterior commissures. Surgical findings were used as the reference to assess diagnostic ability with the area under curve (AUC). The interpretation time for the denoised 3DVR images was compared with that for multiplanar reformat images. For fifty patients (median age 64 years, 30 males), denoising the 3DVR images significantly improved their image quality scores from 50 to 76 (P <.001). The AUC in identifying MV prolapse improved from 0.91 (95% CI 0.87-0.95) to 0.94 (95% CI 0.91-0.98) (P =.009). The denoised 3DVR images were interpreted five-times faster than the multiplanar reformat images (P <.001). Deep learning-based denoising enhanced the quality of 3DVR imaging of the MV, improving the performance and efficiency in detecting MV prolapse on cardiac CT.

Feasibility and Exploration of a Standardized Protocol for Cardiac CT Assessment of Rheumatic Mitral Disease

Rheumatic mitral valve disease often requires surgical interventions, such as percutaneous mitral commissurotomy, surgical mitral valve repair, or replacement, especially in severe cases. This necessitates a precise preoperative assessment of the extent of mitral valve disease. Currently, transthoracic echocardiography, the gold standard for preoperative assessment, has limitations, such as restricted acoustic windows and dependence on the operator, which can affect the evaluation of subvalvular structures and calcification of the mitral valve. Previous studies have shown that cardiac computed tomography (CT), with its high resolution, strong multiplanar reconstruction capabilities, and sensitivity to calcifications, can effectively overcome these limitations. Therefore, this study aims to summarize and evaluate the effectiveness of cardiac CT in examining mitral valve leaflets, annulus, and subvalvular structures. It also reviews the feasibility and guiding significance of using cardiac CT to assess characteristic rheumatic mitral valve lesions.

Mitral Annular Disease at Cardiac MRI: What to Know and Look For

Accurate evaluation of the mitral valve (MV) apparatus is essential for understanding the mechanisms of MV disease across various clinical scenarios. The mitral annulus (MA) is a complex and crucial structure that supports MV function; however, conventional imaging techniques have limitations in fully capturing the entirety of the MA. Moreover, recognizing annular changes might aid in identifying patients who may benefit from advanced cardiac imaging and interventions. Multimodality cardiovascular imaging plays a major role in the diagnosis, prognosis, and management of MV disease. Transthoracic echocardiography is the first-line modality for evaluation of the MA, but it has limitations. Cardiac MRI (CMR) has emerged as a robust imaging modality for assessing annular changes, with distinct advantages over other imaging techniques, including accurate flow and volumetric quantification and assessment of variations in the measurements and shape of the MA during the cardiac cycle. Mitral annular disjunction (MAD) is defined as atrial displacement of the hinge point of the MV annulus away from the ventricular myocardium, a condition that is now more frequently diagnosed and studied owing to recent technical advances in cardiac imaging. However, several unresolved issues regarding MAD, such as the functional significance of pathologic disjunction and how this disjunction advances in the clinical course, require further investigation. The authors review the role of CMR in the assessment of MA disease, with a focus on MAD and its functional implications in MV prolapse and mitral regurgitation. ©RSNA, 2024 Supplemental material is available for this article. See the invited commentary by Stojanovska and Fujikura in this issue.

Transcatheter Mitral Valve Intervention: Current and Future Role of Multimodality Imaging for Device Selection and Periprocedural Guidance

Mitral regurgitation (MR) is a broadly diffuse valvular heart disease (VHD) with a significant impact on the healthcare system and patient prognosis. Transcatheter mitral valve interventions (TMVI) are now well-established techniques included in the therapeutic armamentarium for managing patients with mitral regurgitation, either primary or functional MR. Even if the guidelines give indications regarding the correct management of this VHD, the wide heterogeneity of patients' clinical backgrounds and valvular and heart anatomies make each patient a unique case, in which the appropriate device's selection requires a multimodal imaging evaluation and a multidisciplinary discussion. Proper pre-procedural evaluation plays a pivotal role in judging the feasibility of TMVI, while a cooperative work between imagers and interventionalist is also crucial for procedural success. This manuscript aims to provide an exhaustive overview of the main parameters that need to be evaluated for appropriate device selection, pre-procedural planning, intra-procedural guidance and post-operative assessment in the setting of TMVI. In addition, it tries to give some insights about future perspectives for structural cardiovascular imaging.

Computed tomography imaging in preprocedural planning of transcatheter valvular heart interventions

Cardiac Computed Tomography (CCT) has become a reliable imaging modality in cardiology providing robust information on the morphology and structure of the heart with high temporal and isotropic spatial resolution. For the past decade, there has been a paradigm shift in the management of valvular heart disease since previously unfavorable candidates for surgery are now provided with less-invasive interventions. Transcatheter heart valve interventions provide a real alternative to medical and surgical management and are often the only treatment option for valvular heart disease patients. Successful transcatheter valve interventions rely on comprehensive multimodality imaging assessment. CCT is the mainstay imaging technique for preprocedural planning of these interventions. CCT is critical in guiding patient selection, choice of procedural access, device selection, procedural guidance, as well as allowing postprocedural follow-up of complications. This article aims to review the current evidence of the role of CCT in the preprocedural planning of patients undergoing transcatheter valvular interventions.

Transcatheter mitral valve implantation for native valve disease

Mitral regurgitation is the second most frequent heart valve disease in Europe and the most frequent in the US. Although surgery is the therapy of choice when intervention is indicated, transcatheter mitral valve repair or replacement are alternatives for patients who are not eligible for surgery. However, the development of transcatheter mitral valves is slower than expected. Although several transcatheter heart valves have been developed, only one has been commercialised. Indeed, most of these devices are being evaluated in clinical studies, with promising initial results. In this review, we propose an overview on transcatheter mitral valve replacement for the treatment of native mitral valve disease, from indication to results, including patients with severe annular calcification, and we provide you with a glimpse into the future of these therapies.

Utility of CT and MRI in Tricuspid Valve Interventions

Transcatheter tricuspid valve interventions (TTVIs) comprise a variety of catheter-based interventional techniques for treatment of tricuspid regurgitation (TR) in patients at high surgical risk and those with failed previous surgeries. Several TTVI devices with different mechanisms of action are either currently used or in preclinical evaluation. Echocardiography is the first-line modality for evaluation of tricuspid valve disease that provides information on tricuspid valve morphology, mechanism of TR, and hemodynamics. Cardiac CT and MRI have several advantages for a comprehensive preprocedure evaluation. CT and MRI provide complementary information to that of echocardiography on the mechanism and cause of TR. MRI can quantify the severity of TR using indirect or direct techniques that involve two-dimensional or four-dimensional flow sequences. MRI and CT can also accurately quantify right ventricular volumes and function, which is crucial for timing of intervention. CT provides comprehensive three-dimensional information on the morphology of the valve, annulus, subvalvular apparatus, and adjacent structures. CT is the procedure of choice for evaluation of several device-specific measurements, including tricuspid annulus dimensions, annulus-to-right coronary artery distance, leaflet morphology, coaptation gaps, caval dimensions, and cavoatrial-to-hepatic vein distance. CT allows evaluation of the vascular access as well as optimal procedure fluoroscopic angles and catheter trajectory. Postprocedure CT and MRI are useful in detection of complications such as paravalvular leak, pseudoaneurysm, thrombus, pannus, infective endocarditis, and device migration. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Post-procedural structural heart CT imaging: TAVR, TMVR, and other interventions

Transcatheter valve replacement has experienced substantial growth in the past decade and this technique can now be used for any of the four heart valves. Transcatheter aortic valve replacement (TAVR) has overtaken surgical aortic valve replacement. Transcatheter mitral valve replacement (TMVR) is often performed in pre-existing valves or after prior valve repair, although numerous devices are undergoing trials for replacement of native valves. Transcatheter tricuspid valve replacement (TTVR) is similarly under active development. Lastly, transcatheter pulmonic valve replacement (TPVR) is most often used for revision treatment of congenital heart disease. Given the growth of these techniques, radiologists are increasingly called upon to interpret post-procedural imaging for these patients, particularly with CT. These cases will often arise unexpectedly and require detailed knowledge of potential post-procedural appearances. We review both normal and abnormal post-procedural findings on CT. Certain complications-device migration or embolization, paravalvular leak, or leaflet thrombosis-can occur after replacement of any valve. Other complications are specific to each type of valve, including coronary artery occlusion after TAVR, coronary artery compression after TPVR, or left ventricular outflow tract obstruction after TMVR. Finally, we review access-related complications, which are of particular concern due to the requirement of large-bore catheters for these procedures.

Three-dimensional cardiac computed tomography compared with autopsied material for the assessment of the mitral valve

To compare the morphometrical features of non-diseased mitral valves imaged in three-dimensional (3D) cardiac computed tomography with those analyzed macroscopically in autopsied healthy human hearts. A total of 51 cardiac computed tomography scans and 120 adult autopsied human hearts without cardiovascular disease were examined. The 3D reconstruction and visualization software (Mimics Innovation Suite 22, Materialise) was used for heart chambers semi-automatic segmentation and myocardial manual segmentation to visualize a 3D structure of the mitral valve complex and to perform all measurements. Direct comparison of corresponding mitral valve parameters revealed significant differences between obtained results. Significantly larger intercommisural diameter, aorto-mural diameter, and perimeter of the mitral annulus were observed in tomographic scans (all p < 0.0001). However, the intercommissural/aorto-mural diameter ratio showed comparable values for both groups. Nevertheless, the size of anterior mitral leaflet was higher in autopsied material. The height of the P2 scallops was the only parameter that show no significant difference between two groups (p = 0.3). The use of 3D postprocessing algorithms provides a very accurate image of the mitral valve structure, which could be useful for the precise non-invasive assessment of mitral valve size and structure. Three-dimensional contrast enhanced cardiac computed tomography significantly overestimates the measurements of the mitral annulus compared to postmortem analysis.

Role of Cardiac Computed Tomography in Planning Transcatheter Mitral Valve Replacement (TMVR)

PURPOSE OF REVIEW

Transcatheter mitral valve replacement (TMVR) is an evolving and rapidly expanding field within structural interventions, offering renewed treatment options for patients with high-risk mitral valve disease. We aim to highlight and illustrate the importance of cardiac CT in the planning of TMVR.

RECENT FINDINGS

As TMVR has evolved, so has the specific nuances of cardiac CT planning, we now understand the importance of accurate annular sizing and valve simulation to predict complications such as neo-LVOT obstruction and paravalvular leak (PVL). More so than any other modality, cardiac CT remains instrumental in accurately planning TVMR from feasibility, device sizing, access, and fluoroscopic angles. Cardiac CT remains the key modality in TMVR evaluation, often the first step in determining patient eligibility through comprehensive procedural planning as well as informing potential outcomes and prognosis. In this review, we discuss the critical role of cardiac computed tomography (CT) and the specific considerations involved in TMVR.

Multimodality Imaging in Valvular Structural Interventions

Structural valvular interventions have skyrocketed in the past decade with new devices becoming available and indications for patients who would previously have been deemed inoperable. Furthermore, while echocardiography is the main imaging tool and the first line for patient screening, cardiac magnetic resonance and CT are now essential tools in pre-planning and post-procedural follow-up. This review aims to address imaging modalities and their scope in aortic, mitral and tricuspid structural valvular interventions, including multimodality imaging. Pulmonary valve procedures, which are mostly carried out in patients with congenital problems, are discussed. This article presents a guide on individualised imaging approcahes on each of the available interventional procedures.

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.

Computed Tomography Planning for Transcatheter Mitral Valve Replacement

Transcatheter mitral valve replacement (TMVR) is a rapidly evolving treatment for mitral regurgitation. As with transcatheter aortic valve replacement, multidetector computed tomography analysis plays a central role in defining the candidacy, device selection and safety for TMVR procedures. This contemporary review will describe in detail the multidetector computed tomography data collection, analysis, and planning for TMVR procedures in patients with native mitral regurgitation as well as in those with failed surgical prosthetic mitral valve replacement or surgical mitral valve repair.

CT Planning prior to Transcatheter Mitral Valve Replacement (TMVR)

BACKGROUND

 Transcatheter mitral valve replacement (TMVR) is a treatment option for patients with therapy refractory high-grade mitral valve regurgitation and a high perioperative risk.During TMVR, the mitral annulus cannot be visualized directly. Therefore, comprehensive pre-interventional planning and a precise visualization of the patient's specific mitral valve anatomy, outflow tract anatomy and projected anchoring of the device are necessary.Aim of this review-article is, to assess the role of pre-procedural computed tomography (CT) for TMVR-planning METHODS:  Screening and evaluation of relevant guidelines (European Society of Cardiology [ESC], American Heart Association [AHA/ACC]), meta-analyses and original research using the search terms "TVMR" or "TMVI" and "CT". In addition to this, the authors included insight from their own clinical experience.

RESULTS

 CT allows for accurate measurement of the mitral annulus with high special and adequate temporal resolution in all cardiac phases. Therefore, CT represents a valuable method for accurate prosthesis-sizing.In addition to that, CT can provide information about the valvular- and outflow-tract-anatomy, mitral valve calcifications, configuration of the papillary muscles and of the left ventricle. Additionally, the interventional access-route may concomitantly be visualized.

CONCLUSION

 CT plays, in addition to echocardiographic imaging, a central role in pre-interventional assessment prior to TMVR. Especially the precise depiction of the left ventricular outflow tract (LVOT) provides relevant additional information, which is very difficult or not possible to be acquired in their entirety with other imaging modalities.

KEY POINTS

  · CT plays a central role in pre-interventional imaging for TMVR.. · CT-measurements allow for accurate prosthesis-sizing.. · CT provides valuable information about LVOT-anatomy, mitral calcifications and interventional access-route..

CITATION FORMAT

· Heiser L, Gohmann RF, Noack T et al. CT Planning prior to Transcatheter Mitral Valve Replacement (TMVR). Fortschr Röntgenstr 2022; DOI: 10.1055/a-1718-4182.

Dynamic changes of mitral valve annulus geometry at preprocedural CT: relationship with functional classes of regurgitation

BACKGROUND

We investigated mitral valve annular geometry changes during the cardiac cycle in patients with severe mitral regurgitation (MR) who underwent cardiac computed tomography angiography (CCTA) prior to percutaneous mitral valve replacement or annuloplasty.

METHODS

Fifty-one patients with severe MR and high surgical risk (Carpentier classification: 3 type I, 16 type II, 16 type IIIa, 16 type IIIb) underwent multiphase electrocardiographically gated (0-90%) CCTA, using a second generation dual-source CT scanner, as pre-procedural planning. Twenty-one patients without MR served as controls. The mitral valve annulus was segmented every 10% step of the R-R interval, according to the D-shaped segmentation model, and differences among groups were analysed by t-test or ANOVA.

RESULTS

Mitral annular area and diameters were larger in MR patients compared to controls, particularly in type II. Mitral annular area varied in MR patients throughout the cardiac cycle (mean ± standard deviation of maximum and minimum area 15.6 ± 3.9 cm² versus 13.0 ± 3.5 cm², respectively; p = 0.001), with greater difference between annular areas versus controls (2.59 ± 1.61 cm² and 1.98 ± 0.6 cm², p < 0.001). The largest dimension was found in systolic phases (20-40%) in most of MR patients (n = 27, 53%), independent of Carpentier type (I: n = 1, 33%; II: n = 10, 63%; IIIa: n = 8, 50%; IIIb: n = 8, 50%), and in protodiastolic phases (n = 14, 67%) for the control group.

CONCLUSIONS

In severe MR, mitral annular area varied significantly throughout the cardiac cycle, with a tendency towards larger dimensions in systole.

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.