Establishing 3D Printing at the Point of Care: Basic Principles and Tools for Success.

As the medical applications of three-dimensional (3D) printing increase, so does the number of health care organizations in which adoption or expansion of 3D printing facilities is under consideration. With recent advancements in 3D printing technology, medical practitioners have embraced this powerful tool to help them to deliver high-quality patient care, with a focus on sustainability. The use of 3D printing in the hospital or clinic at the point of care (POC) has profound potential, but its adoption is not without unanticipated challenges and considerations. The authors provide the basic principles and considerations for building the infrastructure to support 3D printing inside the hospital. This process includes building a business case; determining the requirements for facilities, space, and staff; designing a digital workflow; and considering how electronic health records may have a role in the future. The authors also discuss the supported applications and benefits of medical 3D printing and briefly highlight quality and regulatory considerations. The information presented is meant to be a practical guide to assist radiology departments in exploring the possibilities of POC 3D printing and expanding it from a niche application to a fixture of clinical care. An invited commentary by Ballard is available online. ©RSNA, 2022.

Distribution of C-arm projections in native and bioprosthetic aortic valves cusps: Implication for BASILICA procedures.

OBJECTIVES: We sought to document aortic cusps fluoroscopic projections and their distributions using leaflet alignment which is a novel concept to optimize visualization of leaflets and for guiding BASILICA (bioprosthetic or native aortic scallop intentional laceration to prevent coronary artery obstruction) and determine whether these projections were feasible in catheter laboratory. BACKGROUND: Optimal fluoroscopic projections of aortic valve cusps have not been well described. METHODS: A total of 128 pre-transcatheter aortic valve replacement (pre-TAVR) computed tomographies (CT) (72 native valves and 56 bioprosthetic surgical valves) were analyzed. Using CT software (3Mensio, Pie medical imaging, the Netherlands), leaflet alignment was performed and the feasibility of these angles, which were defined as rate of obtainable with efforts (within LAO/RAO of 85° and CRA/CAU of 50°) were evaluated. RESULTS: High feasibility was seen in right coronary cusp (RCC) front view (100%) and left coronary cusp (LCC) side view (99.2%), followed by noncoronary cusp side view (95.3%). In contrast, low feasibility of RCC side view (7.8%) and LCC front view (47.6%) was observed. No statistical differences were seen between the distribution of native valves and bioprosthetic surgical valves. With patient/table tilt of 20°LAO and 10°CRA, the feasibility of RCC side view and LCC front view increased to 43.7 and 85.2%, respectively. CONCLUSION: Distributions of each cusp's leaflet alignment follows "sigmoid curve" which can provide better understanding of aortic valve cusp orientation in TAVR and BASILICA. RCC side view used in right cusp BASILICA is commonly unachievable in catheter laboratory and may improve with patient/table tilt.

Establishing Quality and Safety in Hospital-based 3D Printing Programs: Patient-first Approach.

The adoption of three-dimensional (3D) printing is rapidly spreading across hospitals, and the complexity of 3D-printed models and devices is growing. While exciting, the rapid growth and increasing complexity also put patients at increased risk for potential errors and decreased quality of the final product. More than ever, a strong quality management system (QMS) must be in place to identify potential errors, mitigate those errors, and continually enhance the quality of the product that is delivered to patients. The continuous repetition of the traditional processes of care, without insight into the positive or negative impact, is ultimately detrimental to the delivery of patient care. Repetitive tasks within a process can be measured, refined, and improved and translate into high levels of quality, and the same is true within the 3D printing process. The authors share their own experiences and growing pains in building a QMS into their 3D printing processes. They highlight errors encountered along the way, how they were addressed, and how they have strived to improve consistency, facilitate communication, and replicate successes. They also describe the vital intersection of health care providers, regulatory groups, and traditional manufacturers, who contribute essential elements to a common goal of providing quality and safety to patients. ©RSNA, 2021.

3D Printing Applications for Transcatheter Aortic Valve Replacement.

PURPOSE OF REVIEW: A combination of evolving 3D printing technologies, new 3D printable materials, and multi-disciplinary collaborations have made 3D printing applications for transcatheter aortic valve replacement (TAVR) a promising tool to promote innovation, increase procedural success, and provide a compelling educational tool. This review synthesizes the knowledge via publications and our group's experience in this area that exemplify uses of 3D printing for TAVR. RECENT FINDINGS: Patient-specific 3D-printed models have been used for TAVR pre-procedural device sizing, benchtop prediction of procedural complications, planning for valve-in-valve and bicuspid aortic valve procedures, and more. Recent publications also demonstrate how 3D printing can be used to test assumptions about why certain complications occur during THV implantation. Finally, new materials and combinations of existing materials are starting to bridge the large divide between current 3D material and cardiac tissue properties. Several studies have demonstrated the utility of 3D printing in understanding challenges of TAVR. Innovative approaches to benchtop testing and multi-material printing have brought us closer to being able to predict how a THV will interact with a specific patient's aortic anatomy. This work to date is likely to open the door for advancements in other areas of structural heart disease, such as interventions involving the mitral valve, tricuspid valve, and left atrial appendage.

3D printing from MRI Data: Harnessing strengths and minimizing weaknesses.

3D printing facilitates the creation of accurate physical models of patient-specific anatomy from medical imaging datasets. While the majority of models to date are created from computed tomography (CT) data, there is increasing interest in creating models from other datasets, such as ultrasound and magnetic resonance imaging (MRI). MRI, in particular, holds great potential for 3D printing, given its excellent tissue characterization and lack of ionizing radiation. There are, however, challenges to 3D printing from MRI data as well. Here we review the basics of 3D printing, explore the current strengths and weaknesses of printing from MRI data as they pertain to model accuracy, and discuss considerations in the design of MRI sequences for 3D printing. Finally, we explore the future of 3D printing and MRI, including creative applications and new materials. LEVEL OF EVIDENCE: 5 J. Magn. Reson. Imaging 2017;45:635-645.

A Biofabrication Strategy for a Custom-Shaped, Non-Synthetic Bone Graft Precursor with a Prevascularized Tissue Shell.

Critical-sized defects of irregular bones requiring bone grafting, such as in craniofacial reconstruction, are particularly challenging to repair. With bone-grafting procedures growing in number annually, there is a reciprocal growing interest in bone graft substitutes to meet the demand. Autogenous osteo(myo)cutaneous grafts harvested from a secondary surgical site are the gold standard for reconstruction but are associated with donor-site morbidity and are in limited supply. We developed a bone graft strategy for irregular bone-involved reconstruction that is customizable to defect geometry and patient anatomy, is free of synthetic materials, is cellularized, and has an outer pre-vascularized tissue layer to enhance engraftment and promote osteogenesis. The graft, comprised of bioprinted human-derived demineralized bone matrix blended with native matrix proteins containing human mesenchymal stromal cells and encased in a simple tissue shell containing isolated, human adipose microvessels, ossifies when implanted in rats. Ossification follows robust vascularization within and around the graft, including the formation of a vascular leash, and develops mechanical strength. These results demonstrate an early feasibility animal study of a biofabrication strategy to manufacture a 3D printed patient-matched, osteoconductive, tissue-banked, bone graft without synthetic materials for use in craniofacial reconstruction. The bone fabrication workflow is designed to be performed within the hospital near the Point of Care.

Contemporary Transcatheter Mitral Valve Replacement for Mitral Annular Calcification or Ring.

OBJECTIVES: The aim of this study was to evaluate outcomes of commercial transcatheter mitral valve replacement (TMVR) for annular rings and calcification using contemporary techniques. BACKGROUND: TMVR is evolving in the absence of other viable treatment options for severe mitral annular calcification and failing ring repairs. The concomitant use of laceration of the anterior mitral valve leaflet to prevent left ventricular outflow tract obstruction and pre-emptive alcohol septal ablation is not well studied in clinical practice. METHODS: A single-center study was conducted of valve-in-mitral annular calcification (ViMAC) and valve-in-ring (ViRing) TMVR from September 2015 to April 2020. In-hospital and 30-day outcomes were assessed. RESULTS: Forty patients underwent TMVR (28 ViMAC and 12 ViRing). Sixteen ViMAC (57%) and 5 ViRing (42%) patients underwent attempted laceration of the anterior mitral valve leaflet to prevent left ventricular outflow tract obstruction. Three patients underwent pre-emptive alcohol septal ablation. The median index hospitalization was 7 days. Six patients died within 30 days of the procedure, 6 (21%) in the ViMAC group and none in the ViRing group. Five patients (13%) had left ventricular outflow tract obstruction: 4 (14%) in the ViMAC cohort and 1 (8%) in the ViRing cohort. Five patients (13%) had either intraprocedural valve embolization or late migration (4 ViMAC and 1 ViRing). Technical success defined according to Mitral Valve Academic Research Consortium criteria was present in 25 patients (63%): 9 (75%) in the ViRing cohort and 16 (57%) in the ViMAC cohort. At 30 days, the mitral valve gradient was significantly reduced (5.5 ± 2.1 vs. 10.6 ± 4.8; p < 0.01). Three patients (8%) had at least moderate residual mitral regurgitation. CONCLUSIONS: Transcatheter ViMAC and ViRing can be successfully performed but frequently require the use of contemporary adjunctive techniques.

Coronary ostial eccentricity in severe aortic stenosis: Guidance for BASILICA transcatheter leaflet laceration.

BACKGROUND: Eccentricity of coronary ostial positions in relation to the aortic valve cusp may influence the target laceration location in BASILICA (Bioprosthetic or native Aortic Scallop Intentional Laceration to prevent Coronary Artery obstruction). Eccentricity of the coronary ostia in relation to coronary cusps of native and valve-in-valve transcatheter aortic valve replacement (TAVR) was not well described before. METHODS: A total of 121 pre-TAVR patients' CT data (72 native valves TAVR and 49 bioprosthetic surgical valves TAVR) was included and coronary ostial eccentricity angles were measured and compared. Coronary ostial angles were measured between mid-cusp line to coronary ostium in CT perpendicular images. RESULTS: In the overall cohort, the right coronary artery (RCA) had an eccentric origin in the majority of cases, favoring the commissure between the right and the non coronary cusp (17.0°, IQR; 10-25). On the other hand, the left coronary artery (LCA) originated most commonly near center of the cusp position (0°, IQR; -8 -7.5) In comparison of native and bioprosthetic valves, RCA ostial angles were more eccentric in native valves (19.0°, IQR; 12-26) than in bioprosthetic valves (14.0°, IQR; 3-20) (p = 0.004). Whereas, LCA ostial angle has no significant differences between native valves (-2.0°, IQR;-7.75-5.75) and bioprosthetic valves (1°, IQR;-8-13), (p = 0.6). CONCLUSION: RCA ostia often have an eccentric origin towards the non-coronary cusp, especially in native aortic valves, while LCA ostia commonly originate near the center of the cusp. This finding may contribute to better performance of BASILICA procedures.

Anatomy and Physiology of the Tricuspid Valve.

An appreciation of the complex and variable anatomy of the tricuspid valve is essential to unraveling the pathophysiology of tricuspid regurgitation. A greater appreciation of normal and abnormal anatomy is important as new methods of treating the tricuspid regurgitation are developed. This review of tricuspid valve and right heart anatomy is followed by a discussion of the possible pathophysiology of secondary (functional) tricuspid regurgitation.

Methods for verification of 3D printed anatomic model accuracy using cardiac models as an example.

BACKGROUND: Medical 3D printing has brought the manufacturing world closer to the patient's bedside than ever before. This requires hospitals and their personnel to update their quality assurance program to more appropriately accommodate the 3D printing fabrication process and the challenges that come along with it. RESULTS: In this paper, we explored different methods for verifying the accuracy of a 3D printed anatomical model. Methods included physical measurements, digital photographic measurements, surface scanning, photogrammetry, and computed tomography (CT) scans. The details of each verification method, as well as their benefits and challenges, are discussed. CONCLUSION: There are multiple methods for model verification, each with benefits and drawbacks. The choice of which method to adopt into a quality assurance program is multifactorial and will depend on the type of 3D printed models being created, the training of personnel, and what resources are available within a 3D printed laboratory.

Intact and Isolated Human Cadaveric Coronary Artery Perfusion Models to Facilitate Research and Education Regarding Coronary Anatomy and Pathology.

Cadaveric tissue-perfusion models are well established in the fields of structural heart and peripheral vascular disease; however, less consideration has been given toward coronary artery disease despite comparable prevalence and morbidity. Two tissue-perfusion models were developed to address this need. The first, an intact heart model, allows simulation of percutaneous coronary interventional procedures. The second focuses upon isolated arteries, allowing quantification of simulated procedures. Both models were applied for clinical training and for investigations into medical device behavior. The manner of preparation facilitates access to clinically relevant disease, thus providing a platform to further research on coronary artery disease.

Principles of three-dimensional printing and clinical applications within the abdomen and pelvis.

Improvements in technology and reduction in costs have led to widespread interest in three-dimensional (3D) printing. 3D-printed anatomical models contribute to personalized medicine, surgical planning, and education across medical specialties, and these models are rapidly changing the landscape of clinical practice. A physical object that can be held in one's hands allows for significant advantages over standard two-dimensional (2D) or even 3D computer-based virtual models. Radiologists have the potential to play a significant role as consultants and educators across all specialties by providing 3D-printed models that enhance clinical care. This article reviews the basics of 3D printing, including how models are created from imaging data, clinical applications of 3D printing within the abdomen and pelvis, implications for education and training, limitations, and future directions.

Three-Dimensional Printing for Planning of Structural Heart Interventions.

Three-dimensional (3D) printing is a process leading to the creation of a physical 3D model used for teaching, patient education, device evaluation, and procedural planning. 3D printed models of patient-specific anatomy can be generated from 3D transesophageal, cardiac MRI, or cardiac computed tomographic datasets. This article discusses the potential advantages of 3D printing, reviews the different modalities to acquire a 3D dataset, and highlights the application of 3D printing to enhance patient screening and procedural planning in structural heart intervention.

Anatomy and Function of the Normal and Diseased Mitral Apparatus: Implications for Transcatheter Therapy.

Transcatheter mitral valve therapy requires an in-depth understanding of the mitral valve apparatus (annulus, leaflets, chordae tendinae, and papillary muscles) and the impact of various disease states. Adjacent structures (left atrium, left ventricular outflow tract, aortic valve, coronary sinus, and circumflex artery) must also be respected. This article reviews the anatomy and function of the normal and diseased mitral valve apparatus and the implications for catheter-based intervention.