**10. Current limitations**

laparoscopic partial nephrectomies. The results showed zero cases with a positive surgical margin, zero complication rate and zero conversion to open surgery. This system does however, require placement of aids (like 1.5 cm long needles) into the kidney and is dependent on at least 4 aids being present. This brings risks of damage to healthy parenchyma and aids

An answer to tissue deformation could lie closer to technology used within the commercial sector. Advanced facial recognition software used in simulating real time 'Apple animojis' [31] could be adapted to intra-operative kidneys. The software could delineate an optical real time

Live imaging is an answer to capturing tissue deformation as it allows real-time dynamic information on the kidney and removes the need to 'estimate' structural changes in the tissue. Ultrasound is one live imaging modality that has shown high sensitivity and specificity at identifying tumour margins [32, 33]. There have been several studies using live USS to aid AR. Kang et al. [34] merged live laparoscopic ultrasound images on stereoscopic video and showed accuracy of image-to-video correlation of up to 2.76 mm. Kang et al. claim this aids in depth perception and better visualisation of internal structures. Cheung et al. demonstrated that a fused video-USS model for phantom partial nephrectomy allowed for a 1.1 mm tumour

Singla et al. [36] showed in their study, that simulated healthy renal tissue excised was

would be especially beneficial in critical structures like endophytic renal tumours where most of the tumour lies below the organ surface—(endophytic tumours currently have complica-

These are all however preliminary studies and are based on phantom models which does not represent the true nature of the operation in vivo. A majority of studies have involved manual registration with labour intensive methods that are unrealistic to be currently used in-vivo. Cheung et al. found that although there was 29% reduction in planning time with the USS-fused model, the tumour required longer operative times (being up to 39% slower than

Some projects have combined all three aspects of AR named above. An example of this is PARIS (projector-based AR intracorporeal system)—a method by Edgcumbe et al. [37] where there is a combination of a tracked projector, tracked marker and laparoscopic ultrasound transducer. This has been used in 16 simulated laparoscopic partial nephrectomies, where cancerous tumours were projected onto the kidney surface and this projection moved with kidney. An ultrasound allowed live imaging of the intra-operative environment. This study showed better identification of underlying anatomy and tumour boundaries to show signifi-

using intra-operative USS based AR. This technique

map of the kidney which would change with the active deformation.

resection margin (with 2D fusion) for endophytic tumours [35].

reduced from an average 30.6–17.5 cm3

tion rate of nearly 50%).

the conventional system) [35].

cation reduction in healthy tissue excised.

being lost intra-op.

100 Evolving Trends in Kidney Cancer

**8. Live imaging**

This chapter has described the different aspects of AR in renal cancer and areas that have seen progress. However, there are current limitations holding back the use of AR technology in the clinical set-up. Vavar et al. and Detmer et al. have highlighted some of these (as below):


Regardless of what aspect of AR being explored, there is little quantitative data on in-vivo procedures. Only 20 studies were found by a recent review [27] where AR had been used in clinical practice, and only 9 studies had 10 or more patients in the study. There is a crucial need for *clinical validity* to show improved patient outcomes and safety from using AR in renal interventions.

> tissues to distinguish between normal, borderline and malignant tissue [42] and this could be used in partial nephrectomies to give real time feedback for a precise tumour margin. **3.** AR headset—this is a device that is being engineered simultaneously in many major US hospitals. Dr. Varshey and Dr. Murthi, are developing one such headset with the engineering team at the "Augmentarium" (University of Maryland). They hope to develop a system where a headset such as the Microsoft HoloLens can be worn by the surgeon and real-time USS of the patient or vital signs and patient data can be overlaid on the felid of view. This would drastically reduce the number of displays a surgeon has to usually track during an operation. Used in conjunction with dynamic image projection, the AR headset would be a good answer to cover the abovementioned 3 aspects of AR in partial nephrectomies [43]. The AR headset hopes to eliminate any obstructions in the surgeon's view as compared to conventional methods. Furthermore, voice recognition and gesture recognition development would enable hands-free control of the device—which would allow the surgeon to

> **Figure 3.** AR of the future. AR involving additional input from live USS imaging, organ trackers and other vital

Augmented Reality in Kidney Cancer http://dx.doi.org/10.5772/intechopen.81890 103

observations and patient data all being fed into the AR headset—providing a hands free platform.

interact with the AR whilst maintaining a sterile environment [20] (**Figure 3**).

**4.** 3D printing—model replications of the patient's kidney can be printed using pre-operative CT/MRIs and these can be used to perform simulated operations prior to placing a knife onto the patient's skin. SIMPeds 3D Print at the Boston Children's Hospital offers exactly this—rapid printing and prototyping for nearly any organ in the human body [44]. Examples of this have been used to replicate and operate on difficult paediatric brain tumours [45], facial reconstructions and orthopaedic surgeries amongst many others [46]. This has allowed surgeons to simulate a realistic assessment of the individual's organ where it can be felt, touched and cut at precise margins. 3D printed surgical planning of partial
