The application of full-size three-dimensional individual printed model combined with three-dimensional digital demonstration can facilitate patient’s preoperative comprehension to robotic-assisted laparoscopic partial nephrectomy

General patient data

Between January 2020 and January 2021, 37 consecutive patients with cT1 renal tumors underwent RALPN in our institution. The ipsilateral glomerular filtration rate (GFR) was obtained with a camera-based method measuring the renal uptake of technetium Tc99m diethylenetriaminepentaacetic acid, revealed that all patients had a normal-functional contralateral kidney. The detailed demographic data of the patients and CAIFMs are listed in Table 1.

Table 1 Demographic data of patients and CAIFMsCT scan and 3D-IDM reconstruction

The enhanced scanning including arterial phase, venous phase, and excretory phase after intravenous contrast administration was used to obtain the original information of tomo-sliced images on a dual-source 64-slice CT system (LightSpeed VCT, GE Healthcare, USA, 0.625 mm thickness) for all 37 enrolled cases.

The acquired CT data of three phases in the format of DICOM (Digital Imaging and Communications in Medicine) was processed to reconstruct the 3D-IDM of affected kidney by using both manual and automatic segmentation techniques on 3D medical image reconstructing and guiding system (3D-MIRGS), which was also described in a report of our relevant study previously (Wang et al. 2015).

The anatomical region including the affected kidney, renal tumor mass, adrenal gland, and renal collecting system, as well as inferior vena cava (IVC), renal arteries, renal veins, and their branches were reconstructed simultaneously. Then, we applied rendering with different colors to distinguish the different vital structures (Fig. 1).

Fig. 1figure 1

The CT-based 3D-IDMs and 3D-IPMs of the representative renal tumor cases (white arrow: the renal mass). AC A 79-year-old male with a left-sided 4.8-cm renal mass on the upper pole (PUDUA score = 10P; R.E.N.A.L. nephrometry score = 8P). DF A 53-year-old female with a right-sided 5.5-cm renal mass on the lower pole (PUDUA score = 11P; R.E.N.A.L. nephrometry score = 9P). HJ A 73-year-old male with a right-sided 4.0-cm renal mass in the mid part (PUDUA score = 10P; R.E.N.A.L. nephrometry score = 9P)

The reconstructed model can be observed from multiple directions and angles with the algorithm of object rotating for 360° along all axes. The system allows users to zoom in and out on the random angle with your free will for each part of the reconstructed anatomical structures. When it comes to the tumor that closed to the renal collecting system or ipsilateral adrenal gland, the users can click on the function icons to remove the tumor mass, turn the irrelevant renal parenchyma into light semitransparent style, and leave the tumor and renal collecting system with different heavy solid colors in the meanwhile, which can provide the intraparenchymal view to help the patients and CAIFMs to understand the spatial relationship between the tumor and concerned adjacent structures.

Maximal diameter of tumor mass, the location and length of targeted segmental renal artery, the optimal site of segmental renal artery clamping, and the volume of renal tissue were measured and calculated as the parameters of quantitative morphometry of the reconstructed 3D-IDM. Based on these parameters, an optimal surgical project was designed, which will be illustrated and demonstrated to the patents and CAIFMs preoperatively.

The fabrication of 3D-IPM

According to the STL-formatted 3D-IDM provided as the printing template, a 3D printer (ProJet CJP 260C, 3D Systems Inc., USA) equipped with double print heads was used in the physical additive manufacturing. Core material named VisiJet PXL (3D Systems Inc., USA) was spread in thin layers over the build platform with a roller. After each layer of core material was spread, color binder was selectively jetted from inkjet print heads over the core layer, causing the core to solidify. The build platform lowered with each subsequent layer of core and binder until the high-resolution model was complete.

The maximal printable size of this printer is 236 × 185 × 127 mm, which can satisfy the full-size fabrication demand of kidney perfectly (Fig. 2). A video demonstrating 3D-IDM demonstration and 3D-IPM fabrication accompanies this article (Additional file 1: Supplemental video).

Fig. 2figure 2

The distinct spatial relationship between the tumor and the nearby vital structures, including renal pelvic, ureter and renal vascular network, can be presented intuitively (AC). The intrarenal sophisticated vasculature featured the targeted arterial branch can be presented in the life-sized 3D-IPM by using different colors (DF)

The preoperative conversations

For each patient and his/her CAIFM (spouse or son/daughter), two preoperative face-to-face semi-structured conversations with a single surgeon (Xuhui Zhang) were held by using patient’s CT films, the entity of 3D-IPM plus 3D-IDMs on IPAD screen as the auxiliary instructing tools separately. The patients’ and CAIFMs’ preoperative levels of comprehension were evaluated from five aspects as below: the renal anatomy, mass characteristics, the upcoming RALPN procedure, potential complication risks, and postoperative prognosis. A self-made 50-point questionnaire (Appendix 1) was used in the study.

Two days before the surgery, the first preoperative conversation was held. Three participants including the patient, his/her CAIFM and the designated surgeon were seated in a quiet and private consultation room to perform this conversation in the round-table style. The CT films were presented and the information of patient’s general health condition, the affected kidney, tumor and operation was delivered from the surgeon to the patient and CAIFM orally. After the communication, the patient and CAIFM were asked to complete the survey of the questionnaire independently. The day before the surgery, the second conference with the same pattern and the same members was held at the same place. The full-size entity of 3D-IPM was shown to the patient and CAIFM. With the free-will observation to the real physical model, the surgeon explained the kidney anatomy, tumor characteristics, the upcoming RALPN procedure, potential complication risks, and postoperative prognosis to the patient and CAIFM sufficiently. Meanwhile, in order to enhance the patient’s and CAIFM’s impression and understanding to the planned surgical manipulations, we demonstrated the vital steps of upcoming RALPN on 3D-IDM animatedly via an IPAD screen. The same questionnaire was completed by the patient and CAIFM separately after the conversation. All the survey sheets of 37 enrolled cases as well as their CAIFMs were collected and analyzed by a single investigator.

Statistical methods

All data are reported as mean and range. The results were compared statistically by using Wilcoxon test, with P < 0.05 considered to indicate statistical significance. All the reported P values were two sided. The statistical analysis was accomplished with SPSS 18.0 (SPSS Inc., 2009, Chicago, IL, USA).

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