Bioprinting continues to make significant strides towards a process that will involve dispensing cells onto biocompatible scaffolding using successive layers to generate tissue-like 3D structures and organs. Along the way, however, there will be a number of interim steps that can also benefit the healthcare community. An excellent example of this is highlighted in a new study Physical Models of Renal Malignancies Using Standard Cross-Sectional Imaging and 3-Dimensional Printers: A Pilot Study. The authors of the study, who work in the Department of Urology at Tulane University School of Medicine; were looking for a method of providing 3-dimensional models of patient’s kidneys based on cross-sectional imaging. According to Jonathan Silberstein, Assistant Professor of Urology, providing such a model “may aid patients, trainees, and clinicians in their comprehension, characterization, localization, and extirpation of suspicious renal masses.”
A common problem that urology physicians frequently encounter is not having patients fully understand the scope of their problem when the situation is explained based on having 2-dimential illustration. Whether the illustrations are based on computed tomography (CT) or magnetic resonance imaging (MRI) it makes little difference in the patient’s understanding. In essence, “the primary limitation with such reconstructed views including the representation of a 3-D image on a 2-dimensional screen permitting only a view of one plane at a time.” The study group felt that a far more realistic representation of the kidney could be provided with the use of an additive fabrication approach like that of which 3D printing could offer.
By using specialized software “to import patient’s diagnostic computerized tomography cross-sectional imaging into 3-D printers” the team was able to “create physical 3-D models of renal units with enhanced in situ lesions.” This approach allowed both patients and trainees to have an “opportunity to manipulate the individualized model before surgical resection. Sterolithography additive manufacturing, a technique in which an ultraviolet laser is used to cure a photosensitive resin in sequential horizontally oriented layers was used to build the model.” This permitted single layers from the CT scan to be printed individually, one upon another, allowing for a model that illustrated a complete excision of any suspicious renal mass.
Kidney models were developed by using clear translucent resin with the tumors in a red hue. The vasculature (blood vessels) was included in the model and it was printed in red. The study team noted that, “Our method of constructing models with translucent resins allows us to visualize the tumor and appreciate the depth of the malignancy.” They indicate that in the future, this approach may potentially allow surgeons to preserve a great amount of healthy renal tissue.
The study was made up of 5 patients with a 3-D model prepared specifically for each patient based on their situation. “Patients and their families verbally expressed improved comprehension of the size, location, and the intended surgical intervention preoperatively.” In addition to the positive feedback from the patients; “trainees, particularly those earlier in their careers, demonstrated improved understanding of the characteristics of the tumor when questioned by surgeons.” Further, the patients all experienced good preservation of the surrounding normal renal tissue.
The study team notes that frequently when patients are diagnosed with renal malignancies, surgeons discover lesions after reviewing 2-dimensional imaging equipment such as CT scans. Since these discoveries are incidental and unexpected, many patients have a limited understanding why additional surgery is needed. A major concern of the study group, notes Silberstein, is that “Limited patient understanding may result in poor treatment choices, which can negatively affect future renal function and/or diminish quality of life. In order to assist the patient in understanding the scope of the problem, surgeons would frequently review the results of the CT scan, or possibly draw pictures of the lesions, however, these alternatives rarely resulted in improved understanding. The 3-D models should allow for improved presentation by surgeons.
“Anecdotally, patients, their families, and trainees consistently stated that the models enhanced their comprehension of the renal tumor in relation to surrounding normal renal parenchyma and hilar structures and improved understanding of the goals of the surgery, states the study”
Additionally, as many fields of internal medicine move from open to minimally invasive procedures, it is more difficult to utilize the time honored technique of tactile sensation. However, surgeons can utilize the 3-Dimensional modeling to gain tactile sensation to help understand and localization of the size and dimension of the tumor.
These techniques should be able to be used in other surgeries beyond kidney, such as livers, and lungs. Not only can the model be used to determine the proper approach to the surgery, but they can also be used during the surgery to conform the tumor dimension and location. While the pilot program was considered a success, Silberstein notes that, “For these physical models to be of significant value and gain widespread acceptance, they must be inexpensive, easily reproducible, and rapidly constructed.”
Future efforts will be directed at these objectives. Let us know what you think about this story in the 3D printed medical model forum thread on 3DPB.com.