Tumor phantom for training and research in transoral surgery

Abstract

Objective: With the paradigm shift towards minimally invasive surgical techniques such as transoral laser microsurgery and transoral robotic surgery for resection of head and neck malignancies, there is a need to enhance the surgical training of these techniques as well as provide a platform for testing new approaches and technologies. The steeper learning curve associated with minimally invasive surgical techniques may be mitigated with the use of tumor phantoms (TP) placed in cadaver models.

Methods: An injectable TP was developed using an agar-gelatin base, unsalted chicken stock, deionized water, food coloring for visual mimicry, and iohexol for radiographic mimicry. Four percentage glutaraldehyde was used as a cross-linking agent for solidification of the TP. The TP was then injected in various mucosal anatomic sites in four unfixed cadaver heads. Visual, radiographic, and tactile mimicry was assessed via endoscopy, CT scan, and tumor dissection and palpation, respectively.

Results: Tumor phantom injection was successfully achieved in all four cadaver heads. Visually and tactilely, the TP demonstrated similar color change, induration, and firmness of a typical squamous cell carcinoma (SCCa). However, ulceration that is often seen with SCCa could not be replicated. CT mimicry was compared with nine patients with known SCCa. Tumor radiodensity in the nine patients was between 77 and 110 HU (mean 86.3 HU) whereas TP radiodensity was 59 and 127 HU (mean 93.7 HU), with no significant difference between groups (P = .21).

Conclusion: This inexpensive, easy to apply, and unique tumor phantom could be used both to train transoral techniques and as a tool to further investigate new approaches and technologies for transoral surgery.

Level of evidence: NA.

Keywords: TLM; TORS; cadaver; surgical training; transoral surgery; tumor phantom.

FIGURE 1

A, 3D printed dual barrel mixing syringe. Top syringe is agar mixture as outlined in Table 1 and bottom syringe is 4% glutaraldehyde. B, Suspension laryngoscopy of cadaver head and injection through Lindholm laryngoscope. C‐E, Right tonsil prior to injection, C); during injection, D; and post injection, E

FIGURE 2

Pre and post injection endoscopic images at, A, left tonsil; B, vallecula; C, right lateral base of tongue; D, left pharyngoepiglottic fold. For A,C, blue food coloring was used whereas for B,D, a mixture of brown to white coloring in a 1:3 ratio was used. Note that although tumor fullness can be appreciated, color heterogeneity and ulceration are more difficult to mimic

FIGURE 3

A, Radical tonsillectomy and B, partial glossectomy. Top image is specimen right after removal. Lower image is after bisecting TP. Note the ability to easily delineate TP from surrounding soft tissue

FIGURE 4

CT imaging of cadaver TP (left) and patient (right) for, A,B, tonsil; C,D, tongue base; the tumors in each image are circled with dashed red line and radiodensity is noted