Quantifying the Impact of Cancer on the Viscoelastic Properties of the Prostate Gland using a Quasi-Linear Viscoelastic Model

Pathological disorders can alter the mechanical properties of biological tissues, and studying such changes can help to better understand the disease progression. The prostate gland is no exception, as previous studies have shown that cancer can affect its mechanical properties. However, most of these studies have focused on the elastic properties of the tissue and have overlooked the impact of cancer on its viscous response. To address this gap, we used a quasi-linear viscoelastic model to investigate the impact of cancer on both the elastic and viscous characteristics of the prostate gland. By comparing the viscoelastic properties of segments influenced by cancer and those unaffected by cancer in 49 fresh prostates, removed within two hours after prostatectomy surgery, we were able to determine the influence of cancer grade and tumor volume on the tissue. Our findings suggest that tumor volume significantly affects both the elastic modulus and viscosity of the prostate (p-value less than 2%). Specifically, we showed that cancer increases Young's modulus and shear relaxation modulus by 20%. These results have implications for using mechanical properties of the prostate as a potential biomarker for cancer. However, developing an in vivo apparatus to measure these properties remains a challenge that needs to be addressed in future research. STATEMENT OF SIGNIFICANCE: This study is the first to explore how cancer impacts the mechanical properties of prostate tissues using a quasi-linear viscoelastic model. We examined 49 fresh prostate samples collected immediately after surgery and correlated their properties with cancer presence identified in pathology reports. Our results demonstrate a 20% change in the viscoelastic properties of the prostate due to cancer. We initially validated our approach using tissue-mimicking phantoms and then applied it to differentiate between cancerous and normal prostate tissues. These findings offer potential for early cancer detection by assessing these properties. However, conducting these tests in vivo remains a challenge for future research.

Development of a Spoon Motion Navigation Algorithm for the Mealtime Assistant Simulator

In aging society like Japan, maintaining the quality of life (QOL) is an important objective. The oral cavity has various significant functions that contribute to the QOL. Elderly people are susceptible to the swallowing disorders owing to various factors associated with advancing age. In such cases, mealtime assistance can provide elderly persons appropriate eating situations. Thus, mealtime assistance skills are essential for students in nursing and caregiver education. Recently, simulation education has attracted attention as an effective educational process for nursing and caregiver students before their clinical practice in a hospital or care house. In this educational process, a patient model that mimics specific symptoms called the simulation model, is used to learn the symptoms and its care process in the same clinical environment as actual. We have attempted to develop several oral care simulation models, and we have earlier developed a prototype of mealtime assistance simulation model. This simulation model had a tongue model with a sensor system to detect spoon motions, and its fundamental functions were evaluated via spoon detection experiments. Based on the earlier achievements, in this study, we develop an evaluation system of feeding skill using a spoon. The pressing force and position by spoon on the tongue model were estimated by transfer functions derived from experiments. In addition, we developed an algorithm that leads students’ spoon position and pressing force in the correct position.

Effectiveness of technology-enhanced simulation in teaching digital rectal examination: a systematic review narrative synthesis

Background

Digital rectal examination (DRE) is a challenging examination to learn.

Objective

To synthesise evidence regarding the effectiveness of technology-enhanced simulation (TES) for acquiring DRE skills.

Study selection

EMBASE, Medline, CINAHL, Cochrane, Web of Knowledge (Science and Social Science), Scopus and IEEE Xplore were searched; the last search was performed on 3 April 2019. Included were original research studies evaluating TES to teach DRE. Data were abstracted on methodological quality, participants, instructional design and outcomes; a descriptive synthesis was performed. Quality was assessed using a modified Medical Education Research Study Quality Instrument. The study design domain was modified by scoring the papers based on (1) evaluation of risk of bias for randomised controlled trials, (2) description of participants and (3) assessment of robustness and degree of simulation fidelity of the assessments used to evaluate learning.

Findings

863 articles were screened; 12 were eligible, enrolling 1507 prequalified medical/clinical students and 20 qualified doctors. For skill acquisition, role player was statistically significantly superior to a static manikin (2 studies). For knowledge acquisition, manikin use was significantly superior to role player (1 study); 2 studies showed no difference. For confidence, manikin use was significantly superior to no manikin (4 studies). For comfort, manikin use was significantly superior to no manikin (2 studies). For anxiety, role player was significantly superior to manikin (1 study).

Conclusions

TES training is associated with improved DRE skills and should be used more widely.

Development and Validation of Robot Patient Equipped with an Inertial Measurement Unit and Angular Position Sensors to Evaluate Transfer Skills of Nurses

To more efficiently enhance the patient transfer skills of nursing students, this study aims to integrate a transfer skills evaluation system and a robot patient. The evaluation parameters, namely, the translational acceleration of the waist, rotational speed of the chest, and joint angles of the shoulder, hip, and knee, were selected on the basis of the pre-experimental results obtained with a simulated patient acted by the human individuals. To measure these parameters, inertial measurement unit (IMU) and angular position sensors were installed on the robot patient. An experiment was conducted with four nursing teachers to verify whether the robot patient could distinguish the incorrect methods of the transfer skills, determined to be a common mistake made by the nurses. According to the results, most transfer steps had the same effect on the simulated patient and the robot patient, which demonstrates that the robot patient is a suitable substitute for an actual patient. However, in certain steps, the robot patient was not able to distinguish between the correct and incorrect methods using the chosen parameters owing to the differences being insignificant. These insignificant differences were mostly attributed to the passive joint design of the robot patient.

Granular Jamming Based Controllable Organ Design for Abdominal Palpation

Medical manikins play an essential role in the training process of physicians. Currently, most available simulators for abdominal palpation training do not contain controllable organs for dynamic simulations. In this paper, we present a soft robotics controllable liver that can simulate various liver diseases and symptoms for effective and realistic palpation training. The tumors in the liver model are designed based on granular jamming with positive pressure, which converts the fluid-like impalpable particles to a solid-like tumor state by applying low positive pressure on the membrane. Through inflation, the tumor size, liver stiffness, and liver size can be controlled from normal liver state to various abnormalities including enlarged liver, cirrhotic liver, and multiple cancerous and malignant tumors. Mechanical tests have been conducted in the study to evaluate the liver design and the role of positive pressure granular jamming in tumor simulations.

Translational Acceleration, Rotational Speed, and Joint Angle of Patients Related to Correct/Incorrect Methods of Transfer Skills by Nurses

Currently, due to shortages in the nursing faculty and low access to actual patients, it is difficult for students to receive feedback from teachers and practice with actual patients to obtain clinic experience. Thus, both evaluation systems and simulated patients have become urgent requirements. Accordingly, this study proposes a method to evaluate the nurse’s transfer skill through observation from the patient. After verifying the proposed method, it will be integrated with a robotic patient as a future work. To verify if such an evaluation is practical, a checklist comprising 16 steps with correct and incorrect methods was proposed by the nursing teachers. Further, the evaluation parameters were determined as translational acceleration, rotational speed, and joint angle of patient. Inertial sensors and motion capture were employed to measure the translational acceleration, rotational speed, and joint angle. An experiment was conducted with two nursing teachers, who were asked to carry out both correct and incorrect methods. According to the results, three parameters reveal the difference for a patient under correct/incorrect methods and can further be used to evaluate the nurse’s skill once the thresholds are determined. In addition, the applicability of inertial sensors is confirmed for the use of robot development.

Real-time Visualisation and Analysis of Clinicians' Performance during Palpation in Physical Examinations

OBJECTIVE

Motivated by the fact that palpation skills are challenging to learn and teach, particularly during Digital Rectal Examinations (DRE), and the lack of understanding of what constitutes adequate performance, we present a visualisation and analysis system that uses small position and pressure sensors located on the examining finger, allowing the quantitative analysis of duration, steps and pressure applied.

METHODS

The system is first described, followed by an experimental study of twenty experts from four clinical specialties performing ten DREs each on a benchtop model using the proposed system. Analysis of the constitutive steps was conducted to improve understanding of the examination. A Markov model representing executed tasks and analysis of pressure applied is also introduced.

RESULTS

The proposed system successfully allowed the visualisation and analysis during the experimental study. General Practitioners and Nurses were found to execute more tasks compared to Urologists and Colorectal Surgeons. Urologists executed the least number of tasks and were the most consistent group compared to others.

CONCLUSION

The ability to "see through" allowed us to better characterise the performance of experts when conducting a DRE on a benchtop model, comparing the performance of relevant specialties, and studying executed tasks and the pressure applied. The Markov model presented summarises task execution of experts and could be used to compare performance of novices against that of experts.

SIGNIFICANCE

This approach allows for the analysis of performance based on continuous sensor data recording that can be easily extended to real subjects and other types of physical examinations.

Programmable prostate palpation simulator using property-changing pneumatic bladder

The currently available prostate palpation simulators are based on either a physical mock-up or pure virtual simulation. Both cases have their inherent limitations. The former lacks flexibility in presenting abnormalities and scenarios because of the static nature of the mock-up and has usability issues because the prostate model must be replaced in different scenarios. The latter has realism issues, particularly in haptic feedback, because of the very limited performance of haptic hardware and inaccurate haptic simulation. This paper presents a highly flexible and programmable simulator with high haptic fidelity. Our new approach is based on a pneumatic-driven, property-changing, silicone prostate mock-up that can be embedded in a human torso mannequin. The mock-up has seven pneumatically controlled, multi-layered bladder cells to mimic the stiffness, size, and location changes of nodules in the prostate. The size is controlled by inflating the bladder with positive pressure in the chamber, and a hard nodule can be generated using the particle jamming technique; the fine sand in the bladder becomes stiff when it is vacuumed. The programmable valves and system identification process enable us to precisely control the size and stiffness, which results in a simulator that can realistically generate many different diseases without replacing anything. The three most common abnormalities in a prostate are selected for demonstration, and multiple progressive stages of each abnormality are carefully designed based on medical data. A human perception experiment is performed by actual medical professionals and confirms that our simulator exhibits higher realism and usability than do the conventional simulators.

Canine Prostate Palpation Simulator as a Teaching Tool in Veterinary Education

Adult dogs, especially elderly ones, are commonly affected by prostate diseases. Performing rectal palpation during physical examination in dogs is important in small animal clinical diagnosis. Prostate palpation training allows students to learn how to correctly introduce the finger into the rectum and identify the location, size, symmetry, and consistency of the prostate. Alternative methods are needed to teach this technique without using live dogs. Thus, our aim was to develop a canine prostate palpation simulator to provide students with the opportunity to learn the prostate palpation technique in dogs and to assess their opinion of this simulator as a teaching tool. The inner part of the canine mannequin contains a rotation system with three types of prostates that can be exchanged during the exam. Of the 64 participating students, 81% had never used alternative methods and 92.2% had never performed any prostatic palpation. According to the students' opinions, performing a clinical examination on a simulator allowed them to be prepared and familiarized with the palpation technique. They felt satisfied learning a practical method in a harmless way. Both the 3R (replacement, reduction, and refinement) and dog welfare principles were present in most of the students' concerns. We conclude that the simulator can help students to develop clinical skills for prostate palpation in dogs.

Construct validity in a high-fidelity prostate exam simulator

BACKGROUND

All health care practitioners should be facile in the digital rectal exam (DRE) as it provides prostate, rectal and neurological information. The purpose of this study was first to justify our hypothesis that tissue elasticity is indicative of carcinomatous changes. Second, we employed urological surgeons to evaluate our prostate simulator in three ways: (1) authenticate that the elasticity of the simulated prostates accurately represents the range of normal prostate stiffness, (2) determine the range of nodule size reasonably palpable by DRE and (3) discern what degree of elasticity difference within the same prostate suggests malignancy.

METHODS

Institutional Review Board-approved materials characterization, human-subjects experiments, histopathology and chart abstraction of clinical history were performed. Material characterization of 21 ex-vivo prostatectomy specimens was evaluated using a custom-built, portable spherical indentation device while a novel prostate simulator was employed to measure human-subject perception of prostatic state.

RESULTS

From the materials characterization, the measurements of the 21 gross prostates and 40 cross-sections yielded 306 data points. Within the same prostate, cancer was always stiffer. Of the seven cases with an abnormal DRE, the DRE accurately identified adenocarcinoma in 85%. From the human-subjects experiments, the simulated prostates evaluated by urologists ranged in stiffness from 8.9 to 91 kPa, mimicking the range found on ex vivo analysis of 4.6-236.7 kPa. The urological surgeons determined the upper limit of stiffness palpated as realistic for a healthy prostate was 59.63 kPa while the lower limit of stiffness was 27.1 kPa. Nodule size less than 7.5 mm was felt to be too small to reasonably palpate.

CONCLUSIONS

We found it is not the absolute elasticity of the nodule, but rather the relationship of the nodule with the background prostate elasticity that constitutes the critical tactile feedback. Prostate simulator training may lead to greater familiarity with pertinent diagnostic cues and diagnosis of prostate cancer.

Characterizing the range of simulated prostate abnormalities palpable by digital rectal examination

BACKGROUND

Although the digital rectal exam (DRE) is a common method of screening for prostate cancer and other abnormalities, the limits of ability to perform this hands-on exam are unknown. Perceptible limits are a function of the size, depth, and hardness of abnormalities within a given prostate stiffness.

METHODS

To better understand the perceptible limits of the DRE, we conducted a psychophysical study with 18 participants using a custom-built apparatus to simulate prostate tissue and abnormalities of varying size, depth, and hardness. Utilizing a modified version of the psychophysical method of constant stimuli, we uncovered thresholds of absolute detection and variance in ability between examiners.

RESULTS

Within silicone-elastomers that mimic normal prostate tissue (21kPa), abnormalities of 4mm diameter (20mm(3) volume) and greater were consistently detectable (above 75% of the time) but only at a depth of 5mm. Abnormalities located in simulated tissue of greater stiffness (82kPa) had to be twice that volume (5mm diameter, 40mm(3) volume) to be detectable at the same rate.

CONCLUSIONS

This study finds that the size and depth of abnormalities most influence detectability, while the relative stiffness between abnormalities and substrate also affects detectability for some size/depth combinations. While limits identified here are obtained for idealized substrates, this work is useful for informing the development of training and allowing clinicians to set expectations on performance.