Three-dimensional (3D) printing, a rapidly advancing technology, is widely applied in fields such as mechanical engineering and architecture. Three-dimensional printing has been introduced recently into medical practice in areas such as reconstructive surgery, as well as in clinical research. Three-dimensionally printed models of anatomic and autopsy pathology specimens can be used for demonstrating pathology entities to undergraduate medical, dental, and biomedical students, as well as for postgraduate training in examination of gross specimens for anatomic pathology residents and pathology assistants, aiding clinicopathological correlation at multidisciplinary team meetings, and guiding reconstructive surgical procedures.
To apply 3D printing in anatomic pathology for teaching, training, and clinical correlation purposes.
Multicolored 3D printing of human anatomic pathology specimens was achieved using a ZCorp 510 3D printer (3D Systems, Rock Hill, South Carolina) following creation of a 3D model using Autodesk 123D Catch software (Autodesk, Inc, San Francisco, California).
Three-dimensionally printed models of anatomic pathology specimens created included pancreatoduodenectomy (Whipple operation) and radical nephrectomy specimens. The models accurately depicted the topographic anatomy of selected specimens and illustrated the anatomic relation of excised lesions to adjacent normal tissues.
Three-dimensional printing of human anatomic pathology specimens is achievable. Advances in 3D printing technology may further improve the quality of 3D printable anatomic pathology specimens.
Three-dimensional (3D) printing technology is a safe and affordable technique capable of producing 3D physical models of factual objects or constructed designs. It creates a 3D model of objects with realistic representation of depth, shape, and texture, producing a sharp, precise copy of portrayed objects. Since its development, 3D printing has been used in various fields such as architecture, mechanical engineering, and the food industry.1 Three-dimensional printing has markedly advanced in the past 2 years with the commercial availability of 3D printing facilities and laser scanners and the construction of computer-aided design (CAD). Three-dimensional printing technology has been introduced into medicine in clinical practice, biomedical engineering, and clinical research. Three-dimensional models of anatomic pathology specimens can be used for teaching at undergraduate and postgraduate levels and for training residents in pathology and allied fields such as medicine, surgery, and radiology, as well as for potential clinicopathological correlation at multidisciplinary team meetings. In addition, 3D printing of pathology specimens may permit expanded exposure of trainees in other health professions as biomedical scientists, as well as pathology assistants, radiographers, and nurses, who currently rarely, if ever, encounter anatomic pathology specimens in their training. Three-dimensionally printed models may replace or augment archived human pathology specimens in pathology museums at universities. Three-dimensional printing has proven particularly successful in reconstructive surgery. Similarly, 3-dimensionally printed models of surgically removed specimens may guide surgeons during reconstructive surgical procedures.
MATERIALS AND METHODS
For generation of CADs, gross anatomic pathology specimens such as radical nephrectomy and pancreatoduodenectomy specimens were selected from Cork University Hospital Pathology Department (Cork, Ireland). This study was approved by the Ethics Committee of Cork University Teaching Hospitals. Autodesk 123D Catch software (Autodesk, Inc, San Francisco, California) was used to create 3D CADs from 2-dimensional digital photographs using a commercially available iPhone camera (Apple Inc, Cupertino, California) and a commercially available digital single-lens reflex camera (Nikon Corporation, Tokyo, Japan). A sequential loop of digital photographic images of each anatomic pathology specimen was taken at incremental angles. Each specimen was placed on a plain white sheet of paper on the gross dissection board. The specimen was placed in the center of the camera field at an approximate distance of 30 cm. At least 20 photographs were taken per each specimen to create sufficient input for Autodesk 123D Catch software to construct a 3D model. Zooming or flash photography was not used. Digital photographs taken were not edited or cropped by the pathologist but were sent unaltered to a 3D sculptor.2 Created CADs were edited by the 3D sculptor using Magics 3-matic software (Materialise NV, Leuven, Belgium).
Three-dimensional printing was performed in a 3D creation laboratory (3D Creation Lab, Stoke on Trent, England). Multicolored 3D printing was performed using gypsum-based material on a ZCorp 510 3D printer (3D Systems, Rock Hill, South Carolina), a full-spectrum high-definition 24-bit color 3D printing machine with a resolution of 600 × 540 dpi, with a printing layer capacity of 0.089 to 0.102 mm and an output printable model capacity of up to 254 × 350 × 203 mm. The ZCorp 510 uses an ink-jet–based 3D printing technique to dispense layers of fine powder via the ink-jet printheads using a piston. Next, the ink-jet printheads dispense a liquid-based catalyst binder, which reacts with an agent in the powder to bind the layers together. Each model was 3-dimensionally printed in 5 hours and was left overnight for the material to settle. Following 1 hour of drying, cyanoacrylate-based infiltrate was applied to harden the material so that the model is strengthened and ready for handling.
Three-dimensional CADs were created for each specimen using Autodesk 123D Catch software (Figure 1). For optimum results, the 3D sculptor edited the CADs to remove minor defects and gaps in each 3D model, adjust the model surface, and smooth the outer contour. The 3-dimensionally printed model was durable and withstood manual handling and transportation.
Three-dimensionally printed models were created of anatomic pathology specimens, including radical nephrectomy (Figure 2) and pancreatoduodenectomy specimens (Figure 3). Three-dimensionally printed models successfully depicted both anatomic pathology specimens. The tumor in each specimen was sharply illustrated. Its anatomic relation to adjacent normal tissue was distinctly demonstrated, and the topographic anatomy of the adjacent uninvolved tissue was clearly visible. Furthermore, the colors were discernible, and the internal structure of both organs and lesions was appreciated. The shape, outline, and extent of each tumor clearly demonstrated the pathological tumor stage. The 3D print of the radical nephrectomy specimen depicted a pT1 circumscribed renal tumor with a homogeneous yellow cut surface. The tumor was confined within the renal parenchyma, with no extension into Gerota fascia or renal vessels. The renal cortex, including calyces, medulla, and pelvis, was discernible (Figure 4). The 3D print of the pancreatoduodenectomy specimen demonstrated a pT3 malignant tumor of the pancreas with a white homogeneous cut surface and infiltrative edges. The tumor involved the main pancreatic duct and was invading into the duodenum. The main pancreatic duct and common bile duct were clearly identified (Figure 5).
Three-dimensional printing uses 3D CAD data to produce 3D physical models. It builds up the model from a series of cross-sections that correspond to realistic sections from the CAD model. This is acheived by placing down successive layers of powder material or liquid plastic resins. Three-dimensional printing techniques include ink-jetting, fused deposition modeling, laminated object manufacturing (LOM), and laser sintering. Each of the above methods of 3D printing uses a distinct technique and specific material to create a 3D model. Briefly, the ink-jet printing technique uses a manufacturing method similar to 2-dimensional ink-jet printers whereby it deposits liquid plastic resins in striated lines to create a single layer of 16 μm or more. Fused deposition modeling uses a method of extruding and layering filaments of melted thermoplastic materials. Laminated object manufacturing uses a laser cutter technique of shaping and gluing layers of paper or plastic films. Laser sintering techniques include stereolithography and selective laser sintering. While stereolithography uses a technique of curing photopolymers by UV laser, the selective laser sintering technique is based on fusing small particles such as thermoplastic metal, ceramic, or glass by high-power laser.3
Techniques available to create 3D CAD models include laser scanning of objects and software reconstruction of 3D CADs from 2-dimensional digital photographs or computed tomography/magnetic resonance imaging images. Available laser scanners are not designed for use in a pathology laboratory. They are in general either too large to apply in an anatomic pathology laboratory or too small and limited to scan very small objects. Three-dimensional printing of human anatomic pathology specimens was achieved using Autodesk 123D Catch software, a simple, unsophisticated way to create a 3D CAD model from 2-dimensional digital photographs.4 Three-dimensional printing of models using a ZCorp 510 3D printer is performed at a high speed and generates models of moderate strength.
Three-dimensional printing technology is currently used in medicine. Illustrating a thorough, realistic representative copy of tissues, 3-dimensionally printed simulation of human organs such as bone has been used during surgical procedures and for training and clinical research purposes. Three-dimensionally printed models of bone have been used as a scaffold for tissue reconstruction in orthopedic surgical procedures.5 Similarly, a constructed 3-dimensionally printed model of vascular structures has been used in vascular surgical procedures to guide surgeons during procedures.6 By creating a realistic copy of a patient's organ, a 3-dimensionally printed model was used to provide a visual simulation of the surgical field. Simulated surgical maneuvering of organs during surgery was used to evaluate potential risks of surgical complications.7 Reconstruction of an organ by 3D printing has been exploited in clinical research. A 3-dimensionally printed model of a premature infant's airway was used to evaluate aerosol drug delivery to the lungs in one study.8 Recent developments in biotechniques using 3D printing are permitting tissue engineering of cultured cells for regenerative medicine.9
The above trials of 3D printing technology in medicine proved successful in clinical practice and research. In anatomic pathology, by simulating the anatomic structure of an anatomic pathology specimen, 3-dimensionally printed models can create realistic representations of pathology specimens and depict the topographic anatomic relation of targeted lesions. Moreover, because 3D printing can create realistic models of almost any complex shape or geometric feature with accuracy, 3-dimensionally printed models can be used to demonstrate complex lesions such as congenital heart defects. Therefore, 3-dimensionally printed models can be shown to undergraduate and postgraduate students, anatomic pathology residents, and other medical practitioners such as surgeons and radiologists for educational and training purposes. At the undergraduate level, 3-dimensionally printed models can be used to demonstrate pathology entities to medical, dental, and biomedical students, a potential tool that can be an adjunct to the teaching curriculum. Three-dimensionally printed models can aid in teaching gross examination of specimens to anatomic pathology residents and biomedical scientists. At multidisciplinary clinical team meetings, 3-dimensionally printed models can be used for clinicopathological correlation. Three-dimensional models of pathological specimens can guide radiologists and surgeons to correlate tumor stage and demonstrate relation of tumors to surgical margins.
By providing an exact replica of the excised tissue, 3-dimensionally printed models of surgically removed specimens may be used as a prosthesis. Such a prosthesis can be implanted at a second operation, or if advances in the speed of 3D model production permit, a 3D prothesis could be generated during surgery for immediate implantation. To date, such protheses have been generated only from radiological imaging.10
The use of anatomic pathology specimens has been discouraged at some universities because of controversies related to preserving human DNA–containing tissues, as well as risk of transmission of infectious agents such as viruses and bacteria. Three-dimensional printing of anatomic pathology specimens is an alternative that can potentially replace the need for preserving human pathology specimens. Three-dimensionally printed models can be mass produced to create a collection of pathology entities that can be stored in pathology museums at universities and used in undergraduate medical education. Therefore, 3-dimensionally printed models of pathology specimens can resurrect the use of anatomic pathology specimens in university teaching. Furthermore, 3-dimensionally printed models can be generated from any specimen, including rare pathology entities, a feature not readily available at every anatomic pathology museum across universities.
Three-dimensional printing of human anatomic pathology models is in its early phase. A 3-dimensionally printed model costs approximately $300. With increased demand, 3-dimensionally printed models will become more affordable on mass production. Current limitations of 3-dimensionally printed models include limited print size according to the 3D printer capacity, granularity of printed surfaces, and variable quality of produced colors. Current 3-dimensionally printed models need further manual handling to smooth their surface and augment their colors. However, with advances in 3D printing, production of better-quality printed models will ensue.
In conclusion, 3D printing of human anatomic pathology specimens is achievable. Three-dimensional printing of human anatomic pathology, reproducing thorough and realistic models of pathology entities, can be used in education, medical training, clinical research, clinicopathological correlation at multidisciplinary team meetings, and possibly surgical prostheses. Current 3D printing of human anatomic pathology specimens is promising and merits further investigations for application.
The authors have no relevant financial interest in the products or companies described in this article.