Development and validation of a cadaveric porcine Pseudotumor model for Oral Cancer biopsy and resection training

OBJECTIVE

The gold standard of oral cancer (OC) treatment is diagnostic confirmation by biopsy followed by surgical treatment. However, studies have shown that dentists have difficulty performing biopsies, dental students lack knowledge about OC, and surgeons do not always maintain a safe margin during tumor resection. To address this, biopsies and resections could be trained under realistic conditions outside the patient. The aim of this study was to develop and to validate a porcine pseudotumor model of the tongue.

METHODS

An interdisciplinary team reflecting various specialties involved in the oncological treatment of head and neck oncology developed a porcine pseudotumor model of the tongue in which biopsies and resections can be practiced. The refined model was validated in a final trial of 10 participants who each resected four pseudotumors on a tongue, resulting in a total of 40 resected pseudotumors. The participants (7 residents and 3 specialists) had an experience in OC treatment ranging from 0.5 to 27 years. Resection margins (minimum and maximum) were assessed macroscopically and compared beside self-assessed margins and resection time between residents and specialists. Furthermore, the model was evaluated using Likert-type questions on haptic and radiological fidelity, its usefulness as a training model, as well as its imageability using CT and ultrasound.

RESULTS

The model haptically resembles OC (3.0 ± 0.5; 4-point Likert scale), can be visualized with medical imaging and macroscopically evaluated immediately after resection providing feedback. Although, participants (3.2 ± 0.4) tended to agree that they had resected the pseudotumor with an ideal safety margin (10 mm), the mean minimum resection margin was insufficient at 4.2 ± 1.2 mm (mean ± SD), comparable to reported margins in literature. Simultaneously, a maximum resection margin of 18.4 ± 6.1 mm was measured, indicating partial over-resection. Although specialists were faster at resection (p < 0.001), this had no effect on margins (p = 0.114). Overall, the model was well received by the participants, and they could see it being implemented in training (3.7 ± 0.5).

CONCLUSION

The model, which is cost-effective, cryopreservable, and provides a risk-free training environment, is ideal for training in OC biopsy and resection and could be incorporated into dental, medical, or oncologic surgery curricula. Future studies should evaluate the long-term training effects using this model and its potential impact on improving patient outcomes.

First validation of a model-based hepatic percutaneous microwave ablation planning on a clinical dataset

A model-based planning tool, integrated in an imaging system, is envisioned for CT-guided percutaneous microwave ablation. This study aims to evaluate the biophysical model performance, by comparing its prediction retrospectively with the actual ablation ground truth from a clinical dataset in liver. The biophysical model uses a simplified formulation of heat deposition on the applicator and a heat sink related to vasculature to solve the bioheat equation. A performance metric is defined to assess how the planned ablation overlaps the actual ground truth. Results demonstrate superiority of this model prediction compared to manufacturer tabulated data and a significant influence of the vasculature cooling effect. Nevertheless, vasculature shortage due to branches occlusion and applicator misalignment due to registration error between scans affects the thermal prediction. With a more accurate vasculature segmentation, occlusion risk can be estimated, whereas branches can be used as liver landmarks to improve the registration accuracy. Overall, this study emphasizes the benefit of a model-based thermal ablation solution in better planning the ablation procedures. Contrast and registration protocols must be adapted to facilitate its integration into the clinical workflow.

Model-based hepatic percutaneous microwaveablation planning. First validation on a clinical dataset

A model-based planning tool, integrated in an imaging system, is envisioned for CT-guided percutaneous microwave ablation. This study aims to evaluate the biophysical model performance, by comparing its prediction retrospectively with the actualablation ground truth from a clinical data set in liver. The biophysical model uses a simplified formulation of heat depositionon the applicator and a heat sink related to vasculature to solve the bioheat equation. A performance metric is defined toassess how the planned ablation overlaps the actual ground truth. Results demonstrate superiority of this model predictioncompared to manufacturer tabulated data and a significant influence of the vasculature cooling effect. Nevertheless, vasculatureshortage due to branches occlusion and applicator misalignment due to registration error between scans affects the thermalprediction. With a more accurate vasculature segmentation, occlusion risk can be estimated, whereas branches can be usedas liver landmarks to improve the registration accuracy. Overall, this study emphasizes the benefit of a model-based thermalablation solution in better planning the ablation procedures. Contrast and registration protocols must be adapted to facilitate itsintegration into the clinical workflow.

Long loop technique with bifemoral access as salvage technique for repositioning of dislodged port catheters

BACKGROUND

Repositioning of dislocated port systems' catheters is usually performed with a pigtail catheter and/or a goose snare. In case of an inaccessible port catheter tip due to thrombosis, this classic approach may be not successful. For these cases, we describe a long loop bailout technique with bifemoral access.

TECHNIQUE

Via a right transfemoral access, a first attempt to reposition the dislodged port catheter using pigtail catheter and goose snare was performed. After an unsuccessful attempt and delineation of thrombosis of the catheter tip, the contralateral femoral vein was subsequently punctured and a sheath was placed. Through both vascular sheaths, pigtail catheter and goose wire were advanced distally to the catheter. The guidewire in the pigtail catheter was snared, thus creating a "Long loop" configuration. Pulling down both catheters simultaneously with improved stability allowed to detach the catheter tip from the vessel wall and replacement into the superior vena cava was possible. Refinement of catheter tip position was done using the goose snare. This technique was applied on 5 patients with dislodged port catheters in the jugular vein (2/5), the innominate vein (1/5), the subclavian vein (1/5) and the azygos vein (1/5) with a technical success of 100%. No complications were observed.

CONCLUSION

The Long loop technique can be used as salvage approach to reposition a dislodged catheter in case of failure with pigtail catheter and goose snare.

Augmented Reality-Assisted CT-Guided Puncture: A Phantom Study

Purpose

To investigate the feasibility of a novel augmented reality system for CT-guided liver interventions and to compare it with free-hand interventions in a phantom setting.

Methods and materials

A newly developed augmented reality interface was used, with projection of CT-imaging in multiplanar reconstruction and live rendering of the needle position, a bull`s eye view of the needle trajectory and a visualization of the distance to the target. Punctures were performed on a custom-made abdominal phantom by three interventional radiologists with different levels of expertise. Time and needle placement accuracy were measured. Two-tailed Wilcoxon signed rank test (p < 0.05) was performed to evaluate intraparticipant difference.

Results

Intraparticipant puncture times were significantly shorter for each operator in the augmented reality condition (< 0.001 for the resident, < 0.001 for the junior staff member and 0.027 for the senior staff member). The junior staff member had an improvement in accuracy of 1 mm using augmented reality (p 0.026); the other two participants showed no significant improvement regarding accuracy.

Conclusion

In this small series, it appears that the novel augmented reality system may improve the speed of CT-guided punctures in the phantom model compared to the free-hand procedure while maintaining a similar accuracy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-022-03195-y.

Safety and efficacy of right portal vein embolization in patients with prior left lateral liver resection

BACKGROUND

In patients with bilobar metastatic liver disease, surgical clearance of both liver lobes may be achieved through multiple-stage liver resections. For patients with extensive disease, a major two-staged hepatectomy consisting of resection of liver segments II and III before right-sided portal vein embolization (PVE) and resection of segments V-VIII may be performed, leaving only segments IV ± I as the liver remnant.

PURPOSE

To describe the outcome following right-sided PVE after prior complete resection of liver segments II and III.

MATERIAL AND METHODS

In this retrospective study, 15 patients (mean age = 60.4 ± 9.3 years) with liver metastases from colorectal cancer (n = 14) and uveal melanoma (n = 1) who were scheduled to undergo a major two-stage hepatectomy, were included. Total liver volume (TLV) and volume of the future liver remnant (FLR) were measured on pre- and postinterventional computed tomography (CT) scans, and standardized FLR volumes (ratio FLR/TLV) were calculated. Patient data were retrospectively analyzed regarding peri- and postinterventional complications, with special emphasis on liver function tests.

RESULTS

The mean standardized post-PVE FLR volume was 26.9% ± 6.4% and no patient developed hepatic insufficiency after the PVE. Based on FLR hypertrophy and liver function tests, all but one patient were considered eligible for the subsequent right-sided hepatectomy. However, due to local tumor progression, only 9/15 patients eventually proceeded to the second stage of surgery.  .

CONCLUSION

Right-sided PVE was safe and efficacious in this cohort of patients who had previously undergone a complete resection of liver segments II and III as part of a major staged hepatectomy pathway leaving only segments IV(±I) as the FLR. .