Technical Report: A Cost-Effective, Easily Available Tofu Model for Training Residents in Ultrasound-Guided Fine Needle Thyroid Nodule Targeting Punctures

Two Affordable, High-Fidelity Central Venous Models for Ultrasound-Guided Interventional Training

INTRODUCTION

Ultrasound-guided vascular access is an increasingly popular technique due to its reduced complication and higher success rates. Commercially bought training phantoms allow providers to develop tactile skills in a low-risk setting, but are also expensive and poorly accessible. This study analyzes the efficacy of homemade, low-cost, gelatin-based central line vascular models to teach vascular anatomy and intravascular access techniques in training physicians.

METHODS

A gelatin mold was created using a mixture of unflavored gelatin, hot water, psyllium husk powder, and rubbing alcohol. Latex tubing, balloons, precooked hot dog, and tofu were inserted to simulate arteries, veins, nerves, and the sternocleidomastoid muscle, respectively. Medical students from a single institution participated in a 90-minute workshop led by interventional radiology residents. Participants completed presurveys and postsurveys that assessed knowledge acquisition and confidence levels related to acquiring central access. All images were obtained using a USB-C Butterfly iQ probe.

RESULTS

Twenty medical students were analyzed after the workshop. There was a statistically significant increase in self-reported confidence in basic ultrasound use (adjusting gain, depth, probe manipulation), localizing major anatomical structures, using ultrasound for vessel access, and reported ease in identifying muscle, nerves, and major blood vessels under ultrasound. There was also a significant increase in correctly identified anatomical landmarks after the workshop, including the sternocleidomastoid muscle, internal jugular vein, carotid artery, femoral nerve, femoral artery, and femoral vein.

CONCLUSIONS

Our findings suggest that our homemade, low-cost, gelatin-based models were effective in teaching vascular anatomy and ultrasound-guided vascular access techniques to training physicians.

Comparison of low-cost phantoms for ultrasound-guided fine-needle aspiration biopsy training

INTRODUCTION

Phantoms and simulators are widely accepted methods to gain valuable experience and confidence for inexperienced trainees prior to seeing their patient and for refining their skills. A phantom model that is durable, simple, and inexpensive to produce and use would be ideal to train practitioners in ultrasound-guided fine-needle aspiration biopsy (USFNA) technique.

MATERIALS AND METHODS

In this study, we systematically compared several low-cost phantom models including gelatin, extra firm tofu, canned cooked pork, ballistics gel, and chicken breast for their haptic properties, echogenicity, teaching utility, and overall performance based on a Likert scale (1-5; 5 = best). Nine cytopathologists and cytopathology fellows who perform FNA regularly evaluated these models and completed the survey.

RESULTS

The gelatin phantom, with a gelatin to water ratio of 1:8 by weight, was found to be the best for USFNA practice and overall performance, followed by the 1:10 gelatin phantom. Tofu and chicken breast phantoms were also good low-cost alternatives that needed only a few minutes of total preparation time.

CONCLUSIONS

Low-cost, homemade phantoms can serve as excellent alternatives to commercial phantoms for practicing and teaching USFNA.

A model for training ultrasound-guided fine-needle punctures

OBJECTIVE

To evaluate the efficacy of a training program in ultrasound-guided fine needle puncture using a cost-effective model.

METHODS

We evaluated the training of 20 resident radiology physicians, based on a theoretical course and a practical simulation part with models that focused on the puncture technique of thyroid nodules. The total time to perform the procedure, the number of punctures on the model surface, and the application of a questionnaire were used to assess the performance and confidence of the resident physicians in performing the procedure.

RESULTS

The training model used was easy to reproduce, inexpensive, versatile, and capable of simulating the echotexture of thyroid tissue. There was a significant reduction in the total time needed to perform the procedure with a mean of 173.7 s±91.28 s from R1 and 112.8 s±17.66 s from R2 before the course vs. 19.2 s±112.8 s and 14.3 s±9.36 s, respectively, after the course (p<0.0001); as well as the number of superficial punctures, with a mean of 2.2 punctures±0.92 from R1 and 1.5 punctures±0.32 from R2 before the course vs 1.1 punctures±0.71 and 1.0 puncture±0.0, respectively, after the course (p<0.0001). There was also a subjective improvement in the performance and confidence in performing this procedure.

CONCLUSIONS

An inexpensive and easy-to-reproduce gelatin-based model enabled adequate training of resident physicians and proved capable of improving their skills and confidence in simulating the procedure, even with a short period of training.

Improving on the Do-It-Yourself Ultrasound-Guided Fine-Needle Aspiration Simulation Phantom

The increasing use of ultrasound (US) for the diagnostic workup of thyroid lesions has subsequently been met with an increasing demand for effective US and US-guided fine-needle aspiration models. Although numerous do-it-yourself phantoms have been previously described, to our knowledge, this is the first to describe a more realistic US thyroid model using inexpensive consumer-grade materials. A simple phantom was developed and successfully used to obtain US images that realistically mimic thyroid anatomy and echogenicity. The phantom was constructed for a total cost of $6.69. It served as an inexpensive and anatomically realistic means to simulate thyroid US and US-guided fine-needle aspiration.

Whirling technique for thyroid fine needle aspiration biopsy: a preliminary study of effectiveness and safety

PURPOSE

This study was aimed to compare thyroid fine needle aspiration biopsy (FNAB) techniques (conventional vs. whirling) in terms of cell harvesting ability ex vivo, the unsatisfactory rate and complication rate in vivo, and multi-operator performance in a phantom study.

METHODS

In the ex vivo study, cell counts per background at ×100 magnification were compared between both techniques. In the in vivo study, 70 patients who underwent whirling FNAB from July 2019 to November 2019 were retrospectively compared to 140 matched patients who underwent conventional FNAB from January 2018 to November 2019 regarding the unsatisfactory rate and complication rate. As a subgroup analysis, thyroid nodules in difficult biopsy situations (nodule diameter <10 mm and location within 3 mm from major anatomical structures) were compared. In the phantom study, eight operators with varying experience recorded levels of dexterity and needle tip visualization, and their preferences for both techniques.

RESULTS

In the ex vivo study, cell counts were comparable between both techniques in all thyroid nodule mimickers (80.0% vs. 87.5%, P=0.178). In the in vivo study, the unsatisfactory rate was comparable between the two groups (15.7% vs. 12.9%, P=0.859). In the subgroup analysis, the whirling technique demonstrated a lower unsatisfactory rate (5.9% vs. 24.2%, P=0.045) and a lower complication rate (0% vs. 6.1%, P=0.553). In the phantom study, the whirling technique demonstrated better dexterity and needle tip visualization and was preferred by all operators.

CONCLUSION

This newly proposed whirling technique for thyroid FNAB may be effective and safe, especially in difficult biopsy situations.