Three-dimensional (3D) printing and its applications for aortic diseases

Unsuspected Limitations of 3D Printed Model in Planning of Complex Aortic Aneurysm Endovascular Treatment

OBJECTIVE

Static 3-dimensional (3D) printing became attractive for operative planning in cases that involve difficult anatomy. An interactive (low cost, fast) 3D print allowing deliberate surgical practice can be used to improve interventional simulation and planning.

BACKGROUND

Endovascular treatment of complex aortic aneurysms is technically challenging, especially in case of narrow aortic lumen or significant aortic angulation (hostile anatomy). The risk of complications such as graft kinking and target vessel occlusion is difficult to assess based solely on traditional software measuring methods and remain highly dependent on surgeon skills and expertise.

METHODS

A patient with juxtarenal AAA with hostile anatomy had a 3-dimensional printed model constructed preoperatively according to computed tomography images. Endovascular graft implantation in the 3D printed aorta with a standard T-Branch Cook (Cook® Medical, Bloomington, IN, USA) was performed preoperatively in the simulation laboratory enabling optimized feasibility, surgical planning and intraoperative decision making.

RESULTS

The 3D printed aortic model proved to be radio-opaque and allowed simulation of branched endovascular aortic repair (BREVAR). The assessment of intervention feasibility, as well as optimal branch position and orientation was found to be useful for surgeon confidence and the actual intervention in the patient. There was a remarkable agreement between the 3D printed model and both CT and X-ray angiographic images. Although the technical success was achieved as planned, a previously deployed renal stent caused unexpected difficulty in advancing the renal stent, which was not observed in the 3D model simulation.

CONCLUSION

The 3D printed aortic models can be useful for determining feasibility, optimizing planning and intraoperative decision making in hostile anatomy improving the outcome. Despite already offering satisfying accuracy at present, further advancements could enhance the 3D model capability to replicate minor anatomical deformities and variations in tissue density.

Future trends of additive manufacturing in medical applications: An overview

Additive Manufacturing (AM) has recently demonstrated significant medical progress. Due to advancements in materials and methodologies, various processes have been developed to cater to the medical sector's requirements, including bioprinting and 4D, 5D, and 6D printing. However, only a few studies have captured these emerging trends and their medical applications. Therefore, this overview presents an analysis of the advancements and achievements obtained in AM for the medical industry, focusing on the principal trends identified in the annual report of AM3DP.

Biomimicking Atherosclerotic Vessels: A Relevant and (Yet) Sub-Explored Topic

Atherosclerosis represents the etiologic source of several cardiovascular events, including myocardial infarction, cerebrovascular accidents, and peripheral artery disease, which remain the leading cause of mortality in the world. Numerous strategies are being delineated to revert the non-optimal projections of the World Health Organization, by both designing new diagnostic and therapeutic approaches or improving the interventional procedures performed by physicians. Deeply understanding the pathological process of atherosclerosis is, therefore, mandatory to accomplish improved results in these trials. Due to their availability, reproducibility, low expensiveness, and rapid production, biomimicking physical models are preferred over animal experimentation because they can overcome some limitations, mainly related to replicability and ethical issues. Their capability to represent any atherosclerotic stage and/or plaque type makes them valuable tools to investigate hemodynamical, pharmacodynamical, and biomechanical behaviors, as well as to optimize imaging systems and, thus, obtain meaningful prospects to improve the efficacy and effectiveness of treatment on a patient-specific basis. However, the broadness of possible applications in which these biomodels can be used is associated with a wide range of tissue-mimicking materials that are selected depending on the final purpose of the model and, consequently, prioritizing some materials' properties over others. This review aims to summarize the progress in fabricating biomimicking atherosclerotic models, mainly focusing on using materials according to the intended application.

Understanding Atherosclerosis Pathophysiology: Can Additive Manufacturing Be Helpful?

Atherosclerosis is one of the leading causes of death worldwide. Although this subject arouses much interest, there are limitations associated with the biomechanical investigation done in atherosclerotic tissues, namely the unstandardized tests for the mechanical characterization of these tissues and the inherent non-consensual results obtained. The variability of tests and typologies of samples hampers direct comparisons between results and hinders the complete understanding of the pathologic process involved in atherosclerosis development and progression. Therefore, a consensual and definitive evaluation of the mechanical properties of healthy and atherosclerotic blood vessels would allow the production of physical biomodels that could be used for surgeons' training and personalized surgical planning. Additive manufacturing (AM), commonly known as 3D printing, has attracted significant attention due to the potential to fabricate biomodels rapidly. However, the existing literature regarding 3D-printed atherosclerotic vascular models is still very limited. Consequently, this review intends to present the atherosclerosis disease and the consequences of this pathology, discuss the mechanical characterization of atherosclerotic vessels/plaques, and introduce AM as a potential strategy to increase the understanding of atherosclerosis treatment and pathophysiology.

3D printing in aortic endovascular therapies

Endovascular treatment of aortic disease, including aneurysm or dissection, is expanding at a rapid pace. Often, the specific patient anatomy in these cases is complex. Additive manufacturing, also known as three-dimensional (3D) printing, is especially useful in the treatment of aortic disease, due to its ability to manufacture physical models of complex patient anatomy. Compared to other surgical procedures, endovascular aortic repair can readily exploit the advantages of 3D printing with regard to operative planning and preoperative training. To date, there have been numerous uses of 3D printing in the treatment of aortic pathology as an adjunct in presurgical planning and as a basis for training modules for fellows and residents. In this review, we summarize the current uses of 3D printing in the endovascular management of aortic disease. We also review the process of producing these models, the limitations of their applications, and future directions of 3D printing in this field.

Mechanical characterization of 3D printed mimic of human artery affected by atherosclerotic plaque through numerical and experimental methods

This paper proposes a novel experimental investigation based on 3D printing to validate numerical models for biomechanics simulations. Soft elastomeric materials have been used in Polyjet multi-material 3D printer to mimicking arteries affected by atherosclerotic plaque. The nonlinear mechanical properties of five digital materials are characterized and used as an input for finite element (FE) modeling. Pressurized air is applied to the internal cavity of the printed model to reproduce the internal blood pressure in the artery. Digital Imaging Correlation is adopted to measure the displacement and deformation. A 1D linear higher-order FE model based on the Carrera Unified Formulation is compared to 3D nonlinear FE solutions.

Application of 3D Printing in Preoperative Planning

Preoperative planning is critical for success in the surgical suite. Current techniques for surgical planning are limited; clinicians often rely on prior experience and medical imaging to guide the decision-making process. Furthermore, two-dimensional (2D) presentations of anatomical structures may not accurately portray their three-dimensional (3D) complexity, often leaving physicians ill-equipped for the procedure. Although 3D postprocessed images are an improvement on traditional 2D image sets, they are often inadequate for surgical simulation. Medical 3D printing is a rapidly expanding field and could provide an innovative solution to current constraints of preoperative planning. As 3D printing becomes more prevalent in medical settings, it is important that clinicians develop an understanding of the technologies, as well as its uses. Here, we review the fundamentals of 3D printing and key aspects of its workflow. The many applications of 3D printing for preoperative planning are discussed, along with their challenges.

Accuracy evaluation of patient-specific 3D-printed aortic anatomy

INTRODUCTION

3D printing has a wide range of applications in medicine. In surgery, this technique can be used for preoperative planning of complex procedures, production of patient specific implants, as well as training. However, accuracy evaluations of 3D vascular models are rare.

OBJECTIVES

Aim of this study was to investigate the accuracy of patient-specific 3D-printed aortic anatomies.

METHODS

Patients suffering from aorto-iliac aneurysms and with indication for treatment were selected on the basis of different anatomy and localization of the aneurysm in the period from January 1st 2014 to May 27th 2016. Six patients with aorto-iliac aneurysms were selected out of the database for 3D-printing. Subsequently, computed tomography (CT) images of the printed 3D-models were compared with the original CT data sets.

RESULTS

The mean deviation of the six 3D-vascular models ranged between -0.73 mm and 0.14 mm compared to the original CT-data. The relative deviation of the measured values showed no significant difference between the 3D-vascular and the original patient CT-data.

CONCLUSION

Our results showed that 3D printing has the potential to produce patient-specific 3D vascular models with reliable accuracy. This enables the use of such models for the development of new endovascular procedures and devices.

Three-dimensional printing-guided fenestrated endovascular aortic aneurysm repair using open source software and physician-modified devices

Fenestrated endovascular aneurysm repair is frequently used for juxtarenal and pararenal aortic aneurysms. In urgent cases, however, the use of premanufactured patient-specific devices is not an option. Physician-modified endografts may be used to treat these patients but require experience and a steep learning curve for accurate planning to position fenestrations and to perform the graft modifications. Despite experience, a margin of error in placing fenestrations always exists, and a mismatch possibility between the fenestration and vessel ostium can lead to increased cannulation time and stent complications, including target vessel loss. Aortic three-dimensional printing has been widely described in medicine for simulation, training, and surgical planning. Commercial software is currently under investigation for planning of fenestrated endovascular aneurysm repair at high costs. We describe an effective and inexpensive technique using free computer-aided design software to create a real 1:1 aortic 3D model that can easily be printed and quickly sterilized. This aortic model can be used to create a physician-modified endograft and to place fenestrations in an accurate way, with potential for shorter and more precise procedures and better long-term results. Two cases are presented to illustrate the technique, demonstrating that 3D printing is a valuable tool to plan, design, and create fenestrated devices more accurately.

The Role of 3D Printing in Medical Applications: A State of the Art

Three-dimensional (3D) printing refers to a number of manufacturing technologies that generate a physical model from digital information. Medical 3D printing was once an ambitious pipe dream. However, time and investment made it real. Nowadays, the 3D printing technology represents a big opportunity to help pharmaceutical and medical companies to create more specific drugs, enabling a rapid production of medical implants, and changing the way that doctors and surgeons plan procedures. Patient-specific 3D-printed anatomical models are becoming increasingly useful tools in today's practice of precision medicine and for personalized treatments. In the future, 3D-printed implantable organs will probably be available, reducing the waiting lists and increasing the number of lives saved. Additive manufacturing for healthcare is still very much a work in progress, but it is already applied in many different ways in medical field that, already reeling under immense pressure with regards to optimal performance and reduced costs, will stand to gain unprecedented benefits from this good-as-gold technology. The goal of this analysis is to demonstrate by a deep research of the 3D-printing applications in medical field the usefulness and drawbacks and how powerful technology it is.

Assessment of distal access catheter performance during neuroendovascular procedures: measuring force in three-dimensional patient specific phantoms

BACKGROUND

The amount of force applied on a device is an important measure to evaluate the endovascular and surgical device manipulations. The measure has not been evaluated for neuroenodvascular procedures.

PURPOSE

We aimed to study the use of force measure as a novel approach to test distal access catheter (DAC) performance during catheterization of cervical and intracranial vessels using patient specific 3-dimentional (3D) phantoms.

METHODS

Using patient specific 3D phantoms of the cervical and intracranial circulation, we recorded measure of force required to deliver three types of DACs beyond the ophthalmic segment of the internal carotid artery. Six different combinations of DAC-microcatheter-guidewire were tested. We intentionally included what we considered suboptimal combinations of DACs, microcatheters, and guidewires during our experiments to test the feasibility of measuring force under different conditions. A six axis force sensor was secured to the DAC with an adjustable torque used to track axially directed push and pull forces required to navigate the DAC to the target site.

RESULTS

In a total of 55 experiments, we found a significant difference in the amount of force used between different DACs (mean force for DAC A, 1.887±0.531N; for DAC B, 2.153±1.280 N; and for DAC C, 1.194±0.521 N, P=0.007). There was also a significant difference in force measures among the six different catheter systems (P=0.035).

CONCLUSIONS

Significant difference in the amount of force used between different DACs and catheter systems were recorded. Use of force measure in neuroendovascular procedures on 3D printed phantoms is feasible.

Three-Dimensional Printing for Procedure Rehearsal/Simulation/Planning in Interventional Radiology

With the advances in affordable three-dimensional (3D) printing technology, 3D reconstruction and patient-specific 3D printed models are establishing a crucial role in the field of medicine for both educational purposes and procedural planning. 3D printed models provide physicians with increased 3D perception and tactile feedback, and enable a team-based approach to operational planning. However, performing an effective 3D reconstruction requires an in-depth understanding of the software features to accurately segment and reconstruct the human anatomy of interest from preacquired image data from multiple modalities such as computer tomography, 3D angiography and magnetic resonance imaging, and the different 3D printers/materials available in the market today. Increased understanding of this technology may benefit radiologists by developing techniques and tricks specific to interventional radiology and establishing a criterion to determine when to use these. Thus, the purpose of this manuscript is to provide physicians with an update on currently available 3D reconstruction software as well as printers and materials. Our initial experience using this technology is introduced based on a specific case of developing a 3D printed aorta for a patient with severe stenosis of the abdominal aorta.