Utilization of Cinematic Rendering for Evaluation of Gastrointestinal Stromal Tumours (GIST)

Radiology is a rapidly evolving specialty with numerous opportunities for growth and exciting new techniques to change how we work day-to-day. This is often discussed over a cup of coffee between senior and more junior colleagues; some reminiscing that MRI was not a part of their practice and now it is one of the most utilized and valuable tools in our specialty. Dr. Adrian Brady wrote an editorial piece in 2021 for CARJ describing how time moves on and that we need to keep up! ¹ I was reminded of this editorial while reading Barat et al’s paper titled Cinematic Rendering of Gastrointestinal Stromal Tumors: a Review of Current Possibilities and Future Developments. The images of the gastrointestinal stromal tumours (GIST) using cinematic rendering in this article are photorealistic 3D views providing increased tumour characterization for pre-operative planning which show incredible details of these tumours. Cinematic rendering is another new technique that will push radiology further into the future.

Cinematic rendering is a 3D reconstruction technique inspired by the animated movie industry. It follows the same steps used for volume rendering in determining colour and opacity that models real-life physical propagation of light providing photorealistic 3D images with more surface details. ² The application of cinematic rendering in clinical practice has been described for pre-operative planning of tumours such as GIST. Originally clinical use of 3D imaging was confined to calculating organ volumes or orthopedic applications; however, the use of helical technology for the propagation of thin slice computed tomography (CT) in conjunction with advanced image reconstruction software has allowed this to be utilized for a variety of other applications. ³ Applications for cinematic rendering have been reported to include lesion characterization, localization, and risk stratification in the pre-operative setting. This has been adopted in the literature to date for the assessment of liver masses, pancreatic cancer, gastric tumours, leiomyosarcomas, gastrointestinal bleeding and GIST, to name a few.

To realize the value of cinematic rendering for the evaluation of GISTs it is first imperative to understand these tumours. GIST is the most common mesenchymal stromal tumour of the gastrointestinal tract (GIT). They are typically associated with a poor prognosis and a reported 5-year survival of 2% to 20%. ⁴ The biologic behaviors of GISTs are dependant on their mutational status and essentially all GISTs are considered malignant tumours. Surgical resection is the preferred treatment in resectable cases. When a tumour has not ruptured and is completely resected, there is a reported increase in disease free survival. ⁴ They have a high variability of imaging features due to their different growth patterns originating in the submucosa, subserosa, and outer muscular layer of the gastrointestinal tract with some having an intraluminal origin. Presently GISTs are characterized with standard 2D CT which appropriately demonstrates the size, shape, increased enhancement in the arterial phase relative to the venous phase, and the growth pattern of these tumours. These characteristics help to distinguish them from other gastrointestinal tumours. Barat et al describe the exciting additional value of cinematic rendering for these tumours and the future advances CT technology may have for the diagnosis of GIST in our clinical practice.

Cinematic rendering of GIST helps demonstrate the submucosal origin of the mass and visualize the dynamic enhancement pattern within the tumour allowing for better anatomical evaluation of the lesion providing more information on areas of necrosis and enhancement. Additionally, there is increased information regarding the growth pattern, vascular supply, adjacent anatomic structures, and blood vessels which improves pre-operative planning. Active bleeding from a small bowel tumour is difficult to characterize on conventional CT. Cinematic rendering can more easily detect if there is bleeding from a small bowel tumour. It also provides increased information to differentiate GIST form other gastrointestinal tumours, especially at the ampulla and in the pelvis where anatomical detail is limited on conventional CT. ⁵ The use of cinematic rendering in GIST is particularly useful as this technique provides exquisite mucosal detail which increases sensitivity for assessment of gastrointestinal mucosal fold changes. ⁵ Lastly, the ability to produce vascular mapping of a GIST with cinematic rendering allows localization of the feeding vessel in a preoperative setting. Many of the features described are also used to risk stratify GISTs from very low to high risk for recurrence; the added value of cinematic rendering for assessment of GIST may provide a future role for imaging estimation of risk.

As Barat et al discuss, there are limitations to adopting cinematic rendering into clinical practice. However, the scope for future developments is an exciting avenue for improving management of GIST including investigating gene mutations, and incorporating it into a hybrid imaging tool such as positron emission tomography/CT. This technique also has other potential applications including teaching anatomy with more photorealistic images simulating cadaveric specimens. Patient education could be improved with illustration of pathologic diseases in the pre-treatment setting and in the future to be used as an alternative to three-dimensional printing. ²

Cinematic rendering is an exciting new technique currently in its infancy that has the potential to add great value to our practice. To fulfill the advice of Dr Brady: to move forward and keep up, the next step should be to investigate how to implement cinematic rendering into our day-to-day practice.