3D Virtual Models as an Adjunct to Preoperative Surgical Planning

Surgery is the mainstay treatment for abdominal cancer, resulting in over 50,000 surgeries annually in the UK, with 10% of those being for renal cancer. Preoperative surgery planning decisions are made by radiologists and surgeons upon viewing CT and MRI scans. The challenge is to mentally reconstruct the patient's 3D anatomy from these 2D image slices, including tumour location and its relationship to nearby structures such as critical vessels. This process is time consuming and difficult, often resulting in human error and suboptimal decision-making. It is even more important to have a good surgical plan when the operation is to be performed in a minimally-invasive fashion, as it is more challenging setting to rectify an unplanned complication than during open surgery. Therefore, better surgical planning tools are essential if one is to improve patient outcome and reduce the cost of surgical misadventure.

To overcome the limitations of current surgery planning in a soft-tissue oncology setting, dedicated software packages and service providers have provided the capability of classifying the scan voxels into their anatomical components in a process known as image segmentation (see Section 6.1 for more information). Once segmented, stereolithography files are generated which can be used to visualise the anatomy and have the components 3D printed. It has previously been shown that such 3D printed models influence surgical decision-making. However, the relevance of a physical model to plan for a minimally invasive surgical approach is debatable, and the financial and administrative costs of obtaining accurate 3D printed models for routine surgery planning has been speculated to be holding back 3D printed models from breaking into regular clinical usage.

As a necessary precursor to 3D printed models, computational 3D surface-rendered virtual models could be used by the urologist to assist with clinical decision-making. In the literature, such models are referred to by a variety of names such as '3D-rendered images', '3D reconstructions', or 'virtual 3D models'. In this protocol, the investigators will use the latter nomenclature. Virtual 3D models provide many of the advantages of their physical 3D printed counterpart without the challenge of the printing process, they can be easily viewed on standard digital devices such as laptops or smartphones and can be simultaneously viewed and interacted with from anywhere in the world, which could help with collaborative surgery planning between centres. Note that this study's use of virtual 3D models is not to be confused with Virtual-Reality visualisation, which is an immersive environment and currently requires specialist equipment. In support of this study, previous pioneering studies have already shown that surgeons benefit from computational 3D models in the theatre. However, in addition to the available 2D medical images (CT, MRI, volume-rendered images), it has not been shown that virtual 3D models, constructed from the same existing medical scan data, would influence the surgical decision-making process or alter surgeon confidence in their decisions. Crucially, it also remains to be shown that such 3D models can be built reliably and at scale to facilitate their widespread adoption.

Inclusion criteria

• Aged between 18 - 80 years, inclusive;
• Male and female;
• Diagnosed with T1a, or T1b renal tumours;
• Suitable for elective robot-assisted partial nephrectomy;
• Willing and able to provide written informed consent.

Exclusion criteria

• aged <18 or >80 years;
• have had prior abdominal surgery;
• have had pre-operative imaging that is not adherent to the study protocol;
• contraindicated for biopsy;
• do not consent to have biopsy;
• have a body mass index (BMI) ≥35 kg/m^2;
• have a bleeding disorder;
• have baseline chronic kidney disease (CKD);
• not fit or do not consent for surgery;
• chose to have treatment outside the Royal Free Hospital;
• participation in other clinical studies that would potentially confound this study;
• unable to understand English;
• unable to provide consent themselves;