Utility of three-dimensional virtual and printed models for veterinary student education in congenital heart disease Markovic LE, Nguyen S, Clouser S,

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ORIGINAL ARTICLE

Ahead of print publication

Utility of three-dimensional virtual and printed models for veterinary student education in congenital heart disease

Lauren E Markovic¹, Sarah Nguyen¹, Sherry Clouser²
¹ Department of Small Animal Medicine and Surgery, University of Georgia, College of Veterinary Medicine, Athens, GA 30602, USA
² Office of Academic and Student Affairs, University of Georgia, College of Veterinary Medicine, Athens, GA 30602, USA

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Date of Submission	05-Oct-2022
Date of Acceptance	26-Nov-2022
Date of Web Publication	06-Feb-2023

Abstract

Introduction: Congenital heart disease (CHD) is a common heart defect that can be present in small and large animals at birth. Student understanding of normal and abnormal cardiac anatomy is imperative for proper diagnosis and management of CHD. Objectives were to create and use three-dimensional (3D) heart models during a workshop to understand veterinary student perception of 3D models for CHD education. We hypothesized that 3D models would enhance student understanding of CHD, and students would prefer 3D models during cardiac education. Materials and Methods: Computed tomography angiography datasets from canine patent ductus arteriosus were used to create 3D models. Segmentation and computer-aided design were performed. Virtual overlays of 3D models were displayed onto two-dimensional (2D) thoracic radiographs. Stereolithography files were fabricated by a 3D printer. Students participated in a CHD workshop consisting of 2D and 3D teaching stations. Self-assessment surveys before and after the workshop were completed. Results: Twenty-two veterinary students attended the workshop. The 3D-printed models were found to be the most helpful teaching modality based on students’ perception. The 3D-printed model (P < 0.0001) and the 3D digital model (P < 0.0001) were perceived to be significantly more helpful than the 2D radiograph station. All students strongly agreed (15/22) or agreed (7/22) that virtual models overlayed onto 2D radiographs enhanced their spatial recognition of anatomic structures. All students strongly agreed (17/22) and agreed (5/22) that the CHD workshop was a valuable learning opportunity. Conclusion: Creation of virtual and fabricated 3D heart models is feasible. Three-dimensional models may be helpful when understanding spatial recognition of cardiovascular anatomy on thoracic radiographs. We advocate using 3D heart models during CHD education.

Keywords: 3D printing, cardiac, cardiology, teaching

How to cite this URL:
Markovic LE, Nguyen S, Clouser S. Utility of three-dimensional virtual and printed models for veterinary student education in congenital heart disease. Educ Health Prof [Epub ahead of print] [cited 2023 Mar 26]. Available from: https://www.ehpjournal.com/preprintarticle.asp?id=369232

Introduction

Congenital heart disease (CHD) is a common heart defect that can be present in both small and large animals at birth. In a recent study with 76,301 mixed-breed dogs and 57,025 mixed-breed cats, the prevalence of CHD in dogs was 0.13% and in cats was 0.14%.^[1] The most common CHDs in small animals include pulmonary valve stenosis, patent ductus arteriosus (PDA), subaortic stenosis, ventricular septal defects, and atrioventricular valve dysplasia.^[2],[3] CHDs can lead to hemodynamically significant compromise of the animal and can require medical therapy, interventional therapy, surgical repair, or some combination of these. As CHD is the leading cause of heart disease in young animals, it is important to emphasize and expand knowledge about these diseases in the veterinary curriculum. Student understanding of normal and abnormal cardiac anatomy is imperative for proper diagnosis and management of animals with CHD.

Use of traditional two-dimensional (2D) techniques for learning about the heart may lack the spatial recognition cues necessary for the student to comprehend cardiac anatomy, especially for complex CHD. Virtual demonstration of the three-dimensional (3D) heart model on a computer screen helps to facilitate understanding of anatomy and can be beneficial during pre-procedural planning of CHD.^[4],[5] Three-dimensional cardiac printing represents an emerging tool for medical education training. The use of 3D models in teaching has been shown to objectively and subjectively improve understanding of CHD and cardiac anatomy and has been used in preparation of structural heart intervention and surgery.^{[6],[7],[8],[9],[10],[11],[12],[13],[14]} Few reports describe the impact that 3D cardiac printing can have in veterinary medicine.^[15],[16] In the classroom setting, veterinary students are classically taught about CHD with the use of 2D images, such as 2D thoracic radiographs or 2D echocardiography. It can be difficult for students to completely understand and visually reconstruct 3D concepts of cardiac anatomy using 2D images, especially for complex diseases.^[6] The use of 3D modeling in veterinary education has been shown to improve the understanding of specific veterinary concepts including cardiac anatomy,^[15] neuroanatomy,^[17] and obstetrics.^[18] As current literature on 3D heart models and student education is lacking, this study investigated the utility of 3D virtual and 3D-printed models and impact on veterinary student education of CHD. Objectives of this study were to create a 3D model of a PDA, to overlay this virtual 3D model onto a 2D thoracic radiograph, and to generate rapid prototypes of the PDA for hands-on use in a student workshop. The educational objective was to compare 2D traditional imaging methods with 3D virtual and 3D-printed models during the CHD workshop to understand veterinary student perception and subjective utility of 3D models when learning about heart disease. We hypothesized that (i) 3D digital and 3D-printed models would enhance student perceptions of their own understanding of CHD and (ii) students would prefer the inclusion of 3D models during cardiac education.

Materials and Methods

Datasets from a computed tomography angiography (CTA) study of a dog with a PDA were selected for the study. The CTA was performed on a 64-slice CT scanner (Somatom Sensation-64, Siemens Medical Solutions USA, Inc., Malvern, PA, USA). Digital Image Communication in Medicine (DICOM) datasets from the CTA were uploaded to Materialise Mimics Innovation Suite (Plymouth, MI, USA). Image segmentation of the PDA was performed by selecting the regions of interest from the dataset. The CT Heart tool in Mimics was used, placing seed points on every heart chamber and great vessel, which created a 3D mask for each structure. The 3D virtual model was created and was exported to Materialise 3-Matic (Plymouth, MI, USA) for computer-aided design and hollowing and smoothing of the model. The 3D models of each chamber and great vessel were saved as stereolithography (STL) files. Maxon Cinema 4D (Thousand Oaks, CA, USA) and Adobe Photoshop (San Jose, CA, USA) software programs were then used to create the virtual overlay of the 3D model onto 2D lateral and ventrodorsal thoracic radiographs. The thoracic radiographs were obtained from the same dog with the PDA. The STL file was cropped to highlight the PDA and was sent to a 3D printer (Formlabs Form2, Somerville, MA, USA). Dye was added to the resin to highlight the location of the PDA, whereas the other structures were printed in a clear resin. PDA models were printed for the workshop.^[19] One of the five printed models used in the workshop had a canine duct occluder device deployed across the ductus to a show a treatment option for PDA occlusion.

At the end of the 2021–2022 academic year, third- and fourth-year veterinary students at the University of Georgia were invited to participate in a CHD workshop outside of the normal veterinary cardiology curriculum. The participants received an email inviting them to take part in a 60-min CHD workshop. The workshop was held the following week. At the start of the workshop, each student chose a numerical identifier to keep all surveys anonymous. The students were asked to complete a self-assessment survey before and immediately after the congenital heart workshop. The pre-workshop survey consisted of six questions that included the numerical identifier, which cardiology and radiology courses they have taken, current year in veterinary school, their current knowledge of PDA on a 5-point Likert scale (1—very poor, 2—poor, 3—fair, 4—good, 5—excellent),^[11] and if the student had previously used 3D models for learning about cardiac disease [Appendix A]. The workshop consisted of three stations which students visited in the same order. Station 1 included 2D thoracic radiographs from a dog with a left to right PDA [Figure 1]. Station 2 included 3D virtual models of the PDA superimposed onto the 2D thoracic radiographs [Figure 2]. Station 3 included 3D-printed models from the PDA [Figure 3]. A board-certified veterinary cardiologist instructor was present for each station providing a verbal explanation and answering any student questions. The post-workshop survey included forced choice Likert scale questions, and students were asked to rate their level of agreement with each statement. Students were also asked to rank the educational benefit of each of the teaching modalities [Appendix B]. The workflow of the educational workshop is shown in [Figure 4].

Figure 1: Two-dimensional lateral (A) and ventrodorsal (B) thoracic radiographs in a German Shepherd with PDA, which were obtained immediately after interventional closure with a canine duct occluder. This figure was used as station 1 in the CHD workshop.

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Figure 2: Three-dimensional virtual model overlay of cardiovascular structures in the same dog as [Figure 1]. Virtual models are superimposed over the 2D radiograph in lateral (A) and ventrodorsal (B) projections. This figure was used as station 2 in the CHD workshop.

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Figure 3: Three-dimensional-printed heart models used as station 3. Great vessels were printed in clear resin and dye was added to highlight the PDA. This figure was used as station 3, showing different cardiac perspectives: cranial (A), lateral (B), pulmonary ostium from pulmonary trunk (C), and caudal (D).

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Figure 4: Flowchart for the CHD student education workshop.

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Statistical analyses were performed using SAS 9.4 (Cary, NC, USA). A significance threshold of 0.05 was used. A Friedman test was used to compare helpful scores between teaching modalities. Paired comparisons were made with signed-rank tests and corrected for multiple comparisons with the Holm–Bonferroni method.

Results

A 3D virtual model of the cardiovascular structures was generated from the CTA dataset of a client-owned German Shepherd with a PDA. Five rapid-prototype fabricated 3D PDA models were printed from the same dog and were used in the 3D hands-on portion of the student workshop. There were 22 student participants in the CHD workshop.

Twenty students completed the pre-workshop survey, with 18 students in the fourth year and 2 students in the third year of the 4-year veterinary curriculum. None of the participants had previously used 3D models when learning about heart disease. When asked to rate their current knowledge about PDA results were: 1/20 excellent, 7/20 good, 9/20 fair, 3/20 poor, and 0/20 very poor.

Twenty-two students completed the post-workshop survey, 18 fourth-year students, and 2 third-year students. The remaining two students who completed the post-workshop survey did not complete the pre-workshop survey; therefore, their class year is unknown. Overall, students thought that the 3D-printed models were found to be the most helpful teaching modality for understanding PDA. The 3D-printed model (P < 0.0001) and the 3D digital model (P < 0.0001) were perceived to be significantly more helpful than the 2D radiograph. In addition, the 3D heart print was significantly more helpful than the 3D digital model overlay on the 2D radiograph (P = 0.044) [Figure 5]. Student perception of the use of 3D models to enhance their understanding of the PDA was positive. Seventy-seven percent of students (17/22) strongly agreed that 3D-printed models enhanced their understanding of this defect while 23% (5/22) agreed. Seventy-three percent of students (16/22) strongly agreed that 3D digital models enhanced their understanding of this defect, whereas 27% (6/22) agreed. Students thought that 3D models helped to understand PDA anatomy, as 82% (18/22) strongly agreed and 18% (4/22) agreed. Fifty percent (11/22) of students strongly agreed that 3D models were helpful for learning pathophysiology of the PDA, while 45% (10/22) agreed and 5% (1/22) disagreed. When asked whether the 3D models helped the student to better understand the treatment for a PDA, 64% (14/22) strongly agreed, 32% (7/22) agreed, and 5% (1/22) disagreed. All students either strongly agreed 68% (15/22) or agreed 32% (7/22) that the digital models overlayed onto 2D radiographs enhanced their spatial recognition of anatomic structures. When asked whether 3D digital models were useful when learning about radiographic interpretation of heart disease, 86% (19/22) strongly agreed and 14% (3/22) agreed. Lastly, all of the students thought that the congenital heart workshop was a valuable learning opportunity: 77% (17/22) strongly agreed and 23% (5/22) agreed.

Figure 5: Box and whiskers plot of veterinary students who rated each of three teaching modalities as most helpful=5 to least helpful=1. HeartPrint3D = 3D-printed heart model, VirtualModel3D = virtual 3D overlay onto 2D radiograph, RAD2D = 2D thoracic radiograph

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Discussion

The present study represents an application of virtual 3D modeling of the PDA, with overlay techniques of 3D cardiovascular structures onto 2D radiographs. Generation of virtual models with thoracic radiograph overlay was successful using a combination of Materialise Mimics, 3-Matic, Maxon Cinema 4D, and Adobe Photoshop software. The study also depicts the application of patient-specific rapid prototyping for PDA, for hands-on use in a student workshop. Three-dimensional prints from the PDA, with resin highlight at the location of the defect, were all successfully printed. Although 3D model accuracy was not quantified during this study, it has been shown that producing cardiovascular 3D models in a similar fashion yields accurate models in comparison to initial CTAs.^{[20],[21],[22]} All of the materials were subsequently used in the CHD student workshop investigating 2D and 3D teaching methods.

Radiology is part of the core curriculum for veterinary student education. When provided with a 2D thoracic radiograph, it is not uncommon for students to struggle with understanding where structures are located and with radiographic interpretation.^[23],[24] This can be more challenging for the student to be able to visualize 3D anatomy of an animal with heart disease when viewing a 2D radiograph. This study compared 2D traditional imaging methods with 3D virtual and 3D-printed models during a CHD workshop to understand veterinary student perception and utility of models when learning about heart disease. Use of 3D-printed models have previously been shown to be effective for both medical and veterinary students when teaching echocardiography.^[15],[25] These findings appear to be transferable to other imaging modalities including radiographs, as the students in our study unanimously agreed that use of a virtual cardiovascular model overlayed onto a 2D thoracic radiograph enhances their spatial recognition of the heart and vessels. Self-assessments showed that veterinary students rated the overall educational experience positively and asked for 3D models to be incorporated into veterinary student education. While we tested the use of 3D models in the student population and not interns or residents, our results are similar to those found previously in which medical residents reported better satisfaction when using 3D models compared with 2D images with improvement in learner satisfaction scoring.^[6]

The sample size of participants was small as this was a volunteer pilot workshop held outside of the normal Doctor of Veterinary Medicine curriculum. This study would be relatively straightforward to implement during a cardiovascular laboratory within the veterinary curriculum, assessing student perceptions in a larger cohort of participants. In the study, we elected to use only one congenital heart defect. Using multiple and more complex heart defects could have altered the results from the students. Given this was a pilot CHD workshop looking at utility of 3D models when compared with traditional 2D methods, we elected to maximize student learning and impact by using a common CHD seen in dogs, PDA, throughout the workshop. The students in this study thought that the 3D-printed models were the most helpful teaching modality. Three-dimensional-printed congenital heart models have previously been shown to provide trainees with ease of manipulation and clear visualization of the defect and the relationship to nearby cardiovascular structures.^[6] The 3D-printed PDA models in this study offered the students a sense of depth and spatial knowledge that a 2D image lacks. The majority of the students thought that the 3D models helped them understand therapeutic options for a PDA, of which we optimized by placing a transcatheter PDA device implant across the exact location of deployment in the dog’s heart.

In addition, during the workshop, students rotated through each station in same order, from 2D radiographs to virtual overlay to 3D-fabricated models. Although students did not receive any workshop materials in advance, it is possible that if the station order was randomized results of this study could vary. Although this workshop tested the students’ perception of utility of 3D models, it did not assess quantitatively whether their understanding improved using pre- and post-workshop knowledge acquisition testing. While examinations were not given during this workshop, the authors feel that positive student feedback and student–instructor interactions provided a successful afterhours CHD workshop that all of the students agreed was a valuable learning opportunity. Future studies should include assessment of knowledge acquisition facilitated by the inclusion of 3D models in teaching veterinary cardiology.

The 3D modeling software, 3D printer, and materials used in this CHD study are all commercially available and could be purchased and utilized in an academic or private practice center. Virtual and 3D printing for heart model manufacturing can be costly, labor-intensive, and time-consuming, depending on many factors. Utilization of the CT heart tool^[2] in the study allowed for masks to be made of each heart chamber and great vessel in an efficient manner. High-resolution CT data contribute to efficiency of the segmentation process and as well as accuracy of the 3D model. The cardiovascular models generated from this tool were overlaid onto 2D radiographs, highlighting the image fusion technique vital for the virtual modeling aspect of this educational study. Although there is a learning curve to fabrication of 3D cardiac models,^[26] creating and printing 3D models in-house can allow for rapid turn-around times while outsourcing patient-specific cardiac models could be more costly and take several days to weeks to ship.

Conclusion

Creation of virtual and fabricated 3D canine heart models is feasible and can be used for veterinary student education. This study showed that veterinary students prefer the use of 3D models during CHD education. Use of 3D models may be helpful when understanding spatial recognition of cardiovascular anatomy on thoracic radiographs and when learning about CHD. We advocate the use of 3D heart models as an adjunct to traditional 2D teaching methods during CHD education.

Ethical approval

Owner consent for the CTA and 3D modeling in this dog was obtained as per protocol in the 3D cardiovascular modeling to enhance training, education, and pre-procedural planning for structural heart disease grant. This proposal was approved by the University of Georgia (UGA) Clinical Research Committee. The UGA Institutional Review Board (IRB) determined that the proposed workshop activity was not designed as research involving human subjects as defined by the Department of Health and Human Services and U.S. Food and Drug Administration regulations. University of Georgia IRB review and approval was therefore determined not to be required for the educational workshop.

Acknowledgments

The authors wish to acknowledge Brad Gilleland, Christopher Herron, and Dr. James Moore from the Educational Resources at the University of Georgia College of Veterinary Medicine and Materialise Mimics. The authors also wish to acknowledge all of the veterinary student participants in the workshop.

Financial support and sponsorship

Funding support for this study was from the Companion Animal Fund from the University of Georgia, Small Animal Medicine and Surgery Department, College of Veterinary Medicine.

Conflicts of interest

There are no conflicts of interest.

Supplementary Material

Appendix A: Pre-workshop survey

Q1 Number

Q2 Which courses/rotations have you taken?
- □SAMS5355 (Cardiology) (1)
- □ SAMS5346 (Small Animal Cardiology Elective) (2)
- □ LAMS 5323 (Large Animal Cardiology Elective) (3)
- □ Small Animal Cardiology Rotation (4)
- □ VBDI5310 (Veterinary Radiology) (5)
Q3 What is your current year of veterinary school?
- ○ Third year (1)
- ○ Fourth year (2)
Q4 Rate your current knowledge of patent ductus arteriosus.
- ○ 1 (very poor)- I do not know anything about this heart defect (1)
- ○ 2 (poor)- I know very little about this hear defect (2)
- ○ 3 (fair)- I know some things about this defect, but there is more to learn (3)
- ○ 4 (good)- I have good knowledge about this defect, but there is more to learn (4)
- ○ 5 (excellent)- I have excellent knowledge about this heart defect (5)
Q5 Have you previously used 3D models for learning about heart disease?
- ○ Yes (1)
- ○ No (2)
Q6 If yes to the previous question, please elaborate.

Appendix B: Post-workshop survey

Q1 Number

Q2 Rate your level of agreement with each statement.

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Q3 Rate each teaching modality as least helpful (1) to most helpful (5).

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Q4 General comments to provide the instructor

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