As we have highlighted in this blog time and again, surgeons are moving beyond the limitations of two-dimensional images on a screen to achieve the goal of personalized patient care. While medical imaging has come a long way, ultimately an image on a screen cannot offer the same insight as seeing, feeling and interacting with the actual anatomy. Surgeons are increasingly incorporating 3D patient-specific models (PSMs) into their decision-making process to better understand, plan, and practice a complex surgery — and then explain it to the patient and their family.
With the rise in use of 3D PSMs in patient care, the FDA has taken notice. The FDA considers 3D patient-specific anatomical models for diagnostic purposes to be class II medical devices. Subsequently, the Materialise inPrint software received FDA clearance in March of 2018 to create anatomical models for patient care, specifically for orthopedic, maxillofacial and cardiovascular applications. Frank J. Rybicki, M.D., chief of Medical Imaging at Ottawa Hospital, sums it up, “510k clearance is an essential component to ensure quality and safety in the practice of anatomical modeling in hospitals. This milestone serves as a benchmark for the clinical implementation of 3D printing for physicians creating 3D models at the point-of-care.”
Now Stratasys has partnered with Materialise to ensure that the most advanced multi-material printers are part of the only currently available FDA cleared 3D printed model solution. As of November, the Stratasys PolyJet J750 and J735 3D Printers and the high-performance desktop Objet30 Prime 3D Printer offer the most versatile 3D printing systems for point-of-care across hospitals – advancing the production of patient-specific, life-like anatomical models for diagnostic purposes in conjunction with other clinical tools and expert judgment.
Hospital Benefits of FDA Cleared Solution
So, why should a hospital use an FDA cleared solution like the Materialise inPrint software in combination with the certified Stratasys J735, J750, and Objet30 Prime printers? The answer is simple. FDA cleared solutions are validated for each intended use to ensure adequate diagnostic quality, including reproducibility and clinically relevant accuracy and precision. To put it simply, FDA clearance means that you can safely implement 3D printing by relying on Stratasys’ validated tools and expert support. This reduces the burden on your quality control program by starting with a pre-vetted system of software, hardware, and materials. Best of all, you can choose from multiple PolyJet options. Go with either the J735 or J750 for the most complete system to support multidisciplinary programs or select the Objet30 Prime as an affordable entry point within the FDA cleared solutions.
Multi-Color and Multi-Material Deliver Clinical Impact
What sets PolyJet technology apart you may be asking? PolyJet technology provides the ability to combine virtually unlimited colors as well as various textures between soft and hard creating functional models. The printer’s fine resolution, down to 14 micron layers, allows the creation of minute details and thin walls for accurate representation of anatomical structures like vascular systems. The ability to print any color, including blended transitions and transparency, results in a system that can produce very realistic, patient-specific anatomical models. This versatility enables hospitals to support a wide range of anatomical models that extend beyond orthopedics, maxillofacial and cardiovascular applications, including, for example, neurosurgery where enhanced visualization and haptic feedback are critical for effective surgical planning, training, and education.
So what role do color and texture play in anatomical realism and why are they so critical? First and foremost, color can be used to differentiate anatomy by coloring structures such as tumors differently from bone, blood vessels or other critical anatomy. The J735 and J750 printers also have a unique ability to incorporate colors with translucent materials allowing the physician to view hidden structures. With its ability to print flexible materials and hollow channels and chambers, the look and feel of actual human tissue can realistically be simulated to give the surgeon the haptic feedback that he/she has come to rely upon.
Take for instance, developing a surgical plan for a patient with congenital heart disease. In this case, a 10-year old child with Tetralogy of Fallot and pulmonary atresia who had undergone single ventricle palliation with a Glenn shunt presented at Cardinal Glennon Children’s Hospital (Saint Louis, MO) with increasing cyanosis. After reviewing the clinical information as well as the 3D PSM in conference, the cardiologists and cardiovascular surgeons concluded that biventricular repair could be safely performed resulting in the best prognosis long-term of the options considered. The 3D PSM with the use of color allowed the surgeons to visualize and gain a precise understanding of the complex spatial relationships of the aorta and surrounding structures enabling easier identification and surgical manipulation during the case, thereby reducing operative time and potentially improving the surgical outcome (Figure 1 and 2). Specifically, understanding the size of each heart chamber was critical. If the left ventricle was too small, the patient would not tolerate biventricular repair. Should the left ventricle size be sufficient, a biventricular repair would offer improved quality of life. A model was constructed whereby the endocardial border of each chamber was designated a separate color. At the same time to approximate the heart muscle itself, the myocardium was modeled using clear resin. The result was a model where one could evaluate both the internal and external cardiac anatomy quickly and accurately. Ultimately, the use of color was instrumental in determining which surgery to perform, a critical decision with life-changing implications.
Another example of the use of transparency and color comes from Dr. Zen and his colleagues at the Cleveland Clinic (Cleveland, OH) (1). They used multi-material PolyJet technology to successfully 3D print PSMs of livers, along with their complex networks of vascular and biliary structures. Specifically, color was used to gain a thorough understanding of the intra- and extra-hepatic anatomical relationships between the portal vein, hepatic artery, biliary tract, and hepatic vein and to identify any anatomic anomalies which occur frequently and, subsequently, present significant surgical challenges (Figure 3). Additionally, they reported that combining the use of a soft material to simulate the mechanical properties of actual liver tissue with transparent material for the liver parenchyma for detailed visualization, makes the 3D PSMs ideal for both rehearsing liver resection in living donor liver transplantation (LDLT) or tumor resection in hepatobiliary anatomy as well as simulating transplant surgery for optimal surgical planning.
To sum it up, medicine is not black and white nor are the tools it relies upon to plan and deliver personalized medicine. In the words of Dr. Charles Huddleston, a pediatric cardiothoracic surgeon at SSM Cardinal Glennon Hospital and SLUCare, “Having a 3D model changes the game.”
Figure 1 and Figure 2 are a 3D printed model of Tetralogy of Fallot with pulmonary atresia s/p Glenn procedure. Color is extremely helpful for cardiologists and cardiothoracic surgeons to quickly understand complex internal and external cardiac anatomy. The endocardial border of each chamber was designated a separate color and to approximate the heart muscle itself, transparency was used. (AO – Aorta, LA – left atrium, LV – left ventricle, RA- right atrium, RV – Right ventricle, VSD – ventricular septal defect, SVC-superior vena cava).
Figure 3 is a 3D PSM used both for rehearsing liver resection in LDLT and simulating transplant surgery for optimal surgical planning. Color was applied to gain a thorough understanding of the intra- and extra-hepatic anatomical relationships between the portal vein, hepatic artery, biliary tract, and hepatic vein. Making the liver parenchyma transparent provided detailed visualization of the vasculature.
- Zein NN, Hanouneh IA, Bishop PD, Samaan M, Eghtesad B, Quintini C, Miller C, Yerian L, Klatte R. Three-dimensional print of a liver for preoperative planning in living donor liver transplantation. Liver Transpl. 2013; 19(12):1304-10.