A 57-year-old man with a past medical history significant for hypertension, hypothyroidism, and chronic back pain, presented for a second opinion regarding the management of an incidental right kidney mass detected on an MRI of the spine. A renal protocol MRI confirmed a 3.1-cm endophytic mass abutting the collecting system, renal vein (anteriorly) and artery (posteriorly) and a nephrometry score of 8ph (Figure 1). Although he was originally offered a radical nephrectomy due to the location of the tumor and the proximity to the renal hilar structures, he presented to NYU Langone for a second opinion.
Cr/eGFR: 1.18/> 60
UA – negative for proteinuria
The patient was enrolled in NYU S16-00697: Data Visualization of Kidney and Prostate Tumors Using Routine Pre-Operative Imaging, 3D Printed, and 3D Virtual Reality Models. The goal of this IRB-approved research study is to quantitatively evaluate the use of 3D printing and virtual/augmented reality models in patient care. In the study, patients are randomly assigned to 1 of 3 data visualization arms: (1) only routine imaging such as CT or MRI, (2) routine imaging (CT or MRI) and a 3D printed model, or (3) routing imaging (CT or MRI) with an augmented reality model that is viewable in the Microsoft HoloLens.
This patient was randomized to receive a 3D printed model. To create the 3D model, image segmentation of the tumor, kidney, artery, vein, and collecting system was performed (Mimics 20.0, Materialise, Leuven, Belgium). The segmented regions of interest were converted to 3D surface meshes that were saved in the standard triangle language format (STL) for printing (Figure 2A). The 3D printed model was printed on the J750 (Stratasys, Eden Prairie, MN) in multiple colors to properly highlight the appropriate structures (Figure 2B).
Based on the pre-operative 3D printed model, the patient underwent a robotic partial nephrectomy via a retroperitoneal approach (Figure 3A,B) The warm ischemia time (WIT) was 23 minutes, and over 95% of the renal parenchyma was spared. The final pathologic diagnosis was pT1aNxMx clear cell renal cell carcinoma with negative surgical margins. His 3-month postoperative Cr was 0.98 (eGFR > 60).
A 59-year-old woman with a history of gastroesophageal reflux disease (GERD) and gastric band placement was noted to have a spot on her lung on a cardiac screening CT. This finding prompted a chest CT demonstrating an incidental mass extending to the left upper quadrant (LUQ). A CT of the abdomen and pelvis subsequently confirmed a 13-cm mass arising from the isthmus of a horseshoe kidney (Figure 4A,B). The patient presented for management of this large renal mass.
The patient underwent a CT angiogram to further delineate the blood supply to the horseshoe kidney and was enrolled in NYU S16-00697. This patient was selected to receive a pre-operative 3D printed model that was segmented and reconstructed using the same methods above and printed on the Connex500 in clear and multiple gray-scales (Stratasys, Eden Prairie, MN; Figure 5A,B).
The patient successfully underwent an open partial nephrectomy via a chevron incision.
By examining the 3D printed model pre- and intraoperatively, the isthmus was successfully preserved, and the left renal pelvis and bilateral ureters were safely identified and mobilized free from the tumor. The great vessels were skeletonized, and the blood supply of the left moiety was selectively clamped or ligated during the partial nephrectomy with roughly 90% of the normal renal parenchyma spared (Figure 6). The final pathologic diagnosis was a 14-cm renal oncocytoma. Her 3-month postoperative Cr was 0.99 (eGFR > 60)
Although 3D anatomic models are being used with increasing frequency in medicine, the actual impact of 3D printed models on clinical decision-making has not been determined. The objective of our prospective 3D model study is to evaluate the clinical implications of these tactile 3D printed models in a clinical setting.
For localized renal cell carcinoma (RCC), partial nephrectomy is the most common treatment option and considered the standard of care for tumors <4 cm.1 More complex kidney tumors are associated with the development of major complications following partial nephrectomy, often requiring secondary interventions.2 Although advanced imaging technologies provide extremely useful anatomical and tumor displays for clinicians and patients to aid in treatment planning, there is an unmet need for a better pre-operative assessment of the tumor morphology and its relation to surrounding structures in order to prevent possible complications, help choose between different surgical approaches, and appropriately counsel the patient regarding the disease and treatment choice. Breakthrough representations of these solid organ tumors provided by patient-specific 3D printed models will enhance surgical methods as part of the thrust in the treatment and ultimate eradication of cancer.
Pre-operative, patient-specific 3D printed renal tumor models promote nephron-sparing surgery and preservation of the healthy parenchyma, as surgeons gain a better understanding of the size and location of a tumor in relation to normal, healthy tissue and vital structures such as the renal arteries, veins, and collecting system. 3D printed anatomic models are also useful for surgical house-staff education and patient understanding of disease.
The current workflow used to create 3D printed kidney tumor models at NYU Langone Health has been previously described.3,4 Also, we have shown how 3D printed models can alter presurgical planning decisions for patients with renal cancer5 and have demonstrated how 3D models improve patient understanding of disease and surgical procedure.6
Herein, the first case demonstrated how the 3D printed model enabled us to perform a robotic partial nephrectomy instead of a radical nephrectomy; the 3D printed model from the second case allowed for open resection of a large benign tumor arising from a horseshoe kidney with a complex blood supply without sacrificing either moiety or splitting the isthmus of the horseshoe kidney.
These case examples help to demonstrate how 3D printed kidney tumor models can aid in presurgical planning and can lead to improved surgical outcomes. Through our prospective clinical study, we are measuring quantitative patient outcomes such as WIT, blood loss, and OR time, and we hope to demonstrate how these can be improved with the addition of 3D printed models for patients with complex renal masses.