Biopsy Phantom Research Articles

A phantom for targeted endomyocardial biopsy training.

Endomyocardial biopsy (EMB) of the right ventricular (RV) septal surface during cardiac catheterization is the standard method to assess cardiac allograft rejection, heart failure, or inflammatory cardiomyopathies. We developed methodology using a three-dimensional (3D) printed phantom to provide proof of concept for using biplane overlay technology for targeted EMB. A standard bioptome and steerable sheath were used to discern feasibility of biopsy for seven regions of the RV septum guided by 3D overlay. This novel biopsy phantom can help train operators in biopsy techniques, and biplane overlay technology has the potential to advance targeted EMB in transplant and cardiomyopathy populations.

Phantom-based assessment of motion and needle targeting accuracy of robotic devices for magnetic resonance imaging-guided needle biopsy.

The current study proposes simple methods for assessing the performance of robotic devices intended for Magnetic Resonance Imaging (MRI)-guided needle biopsy. In-house made agar-based breast phantoms containing biopsy targets served as the main tool in the evaluation process of an MRI compatible positioning device comprising a needle navigator. The motion accuracy of mechanical stages was assessed by calliper measurements. Laboratory evaluation of needle targeting included a repeatability phantom test and a laser-based method. The accuracy and repeatability of needle targeting was also assessed by MRI. The maximum error of linear motion for steps up to 10mm was 0.1mm. Needle navigation relative to the phantom and alignment with the various biopsy targets were performed successfully in both the laboratory and MRI settings. The proposed biopsy phantoms offered tissue-like signal in MRI and good haptic feedback during needle insertion. The proposed methods could be valuable in the process of validating the accuracy of MRI-guided biopsy robotic devices in both laboratory and real environments.

Developing and testing a robotic MRI/CT fusion biopsy technique using a purpose-built interventional phantom

BackgroundMagnetic resonance imaging (MRI) can be used to target tumour components in biopsy procedures, while the ability to precisely correlate histology and MRI signal is crucial for imaging biomarker validation. Robotic MRI/computed tomography (CT) fusion biopsy offers the potential for this without in-gantry biopsy, although requires development.MethodsTest–retest T1 and T2 relaxation times, attenuation (Hounsfield units, HU), and biopsy core quality were prospectively assessed (January–December 2021) in a range of gelatin, agar, and mixed gelatin/agar solutions of differing concentrations on days 1 and 8 after manufacture. Suitable materials were chosen, and four biopsy phantoms were constructed with twelve spherical 1–3-cm diameter targets visible on MRI, but not on CT. A technical pipeline was developed, and intraoperator and interoperator reliability was tested in four operators performing a total of 96 biopsies. Statistical analysis included T1, T2, and HU repeatability using Bland–Altman analysis, Dice similarity coefficient (DSC), and intraoperator and interoperator reliability.ResultsT1, T2, and HU repeatability had 95% limits-of-agreement of 8.3%, 3.4%, and 17.9%, respectively. The phantom was highly reproducible, with DSC of 0.93 versus 0.92 for scanning the same or two different phantoms, respectively. Hit rate was 100% (96/96 targets), and all operators performed robotic biopsies using a single volumetric acquisition. The fastest procedure time was 32 min for all 12 targets.ConclusionsA reproducible biopsy phantom was developed, validated, and used to test robotic MRI/CT-fusion biopsy. The technique was highly accurate, reliable, and achievable in clinically acceptable timescales meaning it is suitable for clinical application.

Value-assessment of computer-assisted navigation strategies during percutaneous needle placement

PurposeNavigational strategies create a scenario whereby percutaneous needle-based interventions of the liver can be guided using both pre-interventional 3D imaging datasets and dynamic interventional ultrasound (US). To score how such technologies impact the needle placement process, we performed kinematic analysis on different user groups.MethodsUsing a custom biopsy phantom, three consecutive exercises were performed by both novices and experts (n = 26). The exercise came in three options: (1) US-guidance, (2) US-guidance with pre-interventional image-registration (US + Reg) and (3) US-guidance with pre-interventional image-registration and needle-navigation (US + Reg + Nav). The traveled paths of the needle were digitized in 3D. Using custom software algorithms, kinematic metrics were extracted and related to dexterity, decision making indices to obtain overall performance scores (PS).ResultsKinematic analysis helped quantifying the visual assessment of the needle trajectories. Compared to US-guidance, novices yielded most improvements using Reg (PSavg(US) = 0.43 vs. PSavg(US+Reg) = 0.57 vs. PSavg(US+Reg+Nav) = 0.51). Interestingly, the expert group yielded a reversed trend (PSavg(US) = 0.71 vs PSavg(US+Reg) = 0.58 vs PSavg(US+Reg+Nav) = 0.59).ConclusionDigitizing the movement trajectory allowed us to objectively assess the impact of needle-navigation strategies on percutaneous procedures. In particular, our findings suggest that these advanced technologies have a positive impact on the kinematics derived performance of novices.

Constructing and Pilot Testing a Novel Prostate Magnetic Resonance Imaging/Ultrasound Fusion Biopsy Phantom

ObjectiveTo describe the design and build of a novel phantom for magnetic resonance imaging (MRI)/ultrasound (US) fusion biopsy and present pilot testing results from a multicenter urology resident training session. MethodsWe cast our phantom from polyvinylchloride-plastisol that features 10 mm and 5 mm blue clay tumors, a urethral lumen, and an echogenic capsule. T2-weighted images were acquired with a 3T MR750 scanner (GE Healthcare, Boston, MA). Fusion testing was performed on the bkFusion system (BK ultrasound, Peabody, MA) with MIM Symphony software (MIM, Cleveland, OH) and an 18-gauge Bard Monopty disposable gun (Bard, Murray Hill, NJ). Twenty residents from 6 urology programs in Chicago performed proctored user testing. ResultsThe per phantom material cost was $12. The phantom was compatible with all necessary equipment to create a MRI/US fusion data set. MRI and US imaging characteristics were excellent with hypointense lesions. Image fusion was achieved through both end and side fire ultrasound probes. The phantom allowed for biopsies to be performed, and target lesion hits were confirmed by visual inspection of core samples. 38% (8/21) of urology resident pilot testing participants had previously performed a fusion biopsy. The mean postsession survey scores were (1-10 [best]): realism 9.0, usefulness 9.4, ease of use 9.1, ease of orientation 8.9, and overall experience 9.3. ConclusionThis simple and inexpensive phantom allows for training and accuracy testing of MRI/US fusion biopsy hardware and software platforms.

Special Ultrasound Phantom for Interventional Training: Construction, Advantages, and Application.

Interventional radiology procedures are becoming more challenging over time; thus, there is a need for excellent and reliable training methods. Training on live patients is neither safe nor an ethical solution. Alternatives are many and varied, but the most popular is ultrasound guided simulators. This report shows how a simple, homemade, low-cost phantom material, and construction modules can provide several advantages over ordinary gelatin phantoms. A new layering technique and target synthesis are described for the biopsy phantom, including tips on decreasing the needle pass artifact as well as controlling the mixture echogenicity.

Development and Evaluation of a Novel Curved Biopsy Device for CT-Guided Biopsy of Lesions Unreachable Using Standard Straight Needle Trajectories.

To evaluate the feasibility of a novel curved CT-guided biopsy needle prototype with shape memory to access otherwise not accessible biopsy targets. A biopsy needle curved by 90° with specific radius was designed. It was manufactured using nitinol to acquire shape memory, encased in a straight guiding trocar to be driven out for access of otherwise inaccessible targets. Fifty CT-guided punctures were conducted in a biopsy phantom and 10 CT-guided punctures in a swine corpse. Biposies from porcine liver and muscle tissue were separately gained using the biopsy device, and histological examination was performed subsequently. Mean time for placement of the trocar and deployment of the inner biopsy needle was ~205±69 and ~93±58s, respectively, with a mean of ~4.5±1.3 steps to reach adequate biopsy position. Mean distance from the tip of the needle to the target was ~0.7±0.8 mm. CT-guided punctures in the swine corpse took relatively longer and required more biopsy steps (~574±107 and ~380±148s, 8±2.6 steps). Histology demonstrated appropriate tissue samples in nine out of ten cases (90%). Targets that were otherwise inaccessible via standard straight needle trajectories could be successfully reached with the curved biopsy needle prototype. Shape memory and preformed size with specific radius of the curved needle simplify the target accessibility with a low risk of injuring adjacent structures.

Quality Assurance and Average Glandular dose Measurement in Mammography Units.

To ensure the safe operation of mammography units, acceptance tests and quality assurance (QA) protocols have been developed by the American Association of Physicists in Medicine (AAPM), Engineers Registration Board, and International Atomic Energy Agency. Eight mammography units manufactured by five different manufacturers located in hospitals in our region were investigated following the AAPM and Atomic Energy Regulatory Board (AERB) protocols using a solid-state dosimeter-based PTW-NOMEX Multimeter and a metal-oxide-semiconductor field-effect transistor. This study evaluated different operating parameters through mechanical test, accelerating voltage (kVp) accuracy test, machine output measurement, half-value layer measurement, calibration of compression device, image quality assessment, measurement of leakage radiation, radiation survey, and average glandular dose (AGD) measurements using stereotactic needle biopsy phantom. The results show that out of eight mammography units, only a single mammography unit (U-1) passed all QA tests and 2 units passed 7 tests, 2 units passed 6 tests, and 3 units passed 5 tests out of 8 QA tests. In unit 5, the AGD value was 4 and 1.93 mGy before and after service, respectively. QA programs as recommended by AAPM and AERB should be carried out periodically to ensure safety in breast cancer screening. This work points to the importance of the regulation and effective compliance and also help in both improving the QA and reduce the glandular dose received by the patients.

Imaging results of multi-modal ultrasound computerized tomography system designed for breast diagnosis

Nowadays, in the era of common computerization, transmission and reflection methods are intensively developed in addition to improving classical ultrasound methods (US) for imaging of tissue structure, in particular ultrasound transmission tomography UTT (analogous to computed tomography CT which uses X-rays) and reflection tomography URT (based on the synthetic aperture method used in radar imaging techniques). This paper presents and analyses the results of ultrasound transmission tomography imaging of the internal structure of the female breast biopsy phantom CIRS Model 052A and the results of the ultrasound reflection tomography imaging of a wire sample. Imaging was performed using a multi-modal ultrasound computerized tomography system developed with the participation of a private investor. The results were compared with the results of imaging obtained using dual energy CT, MR mammography and conventional US method. The obtained results indicate that the developed UTT and URT methods, after the acceleration of the scanning process, thus enabling in vivo examination, may be successfully used for detection and detailed characterization of breast lesions in women.

Abstract No. 376 - A pilot program for use of a homemade phantom for CT biopsy simulation training

To review the benefits of simulation training in interventional radiology (IR). Detail the specific role of simulation for trainees learning to perform image-guided biopsy. Demonstrate a simple way to make a reusable phantom to teach, practice, and evaluate the image-guided percutaneous biopsy skill set, with data from pilot program presented. Computed tomographic (CT) guided biopsy is a common procedure, with more than 600,000 performed annually in the United States. Training in IR predominantly uses the apprenticeship model, where clinical and technical skills of invasive procedures are learned while being performed on patients, which places both the patient and proceduralist at unnecessary risk. Medical education is moving towards increased use of simulation, as it allows learners to strengthen their technical skills without inferring risk to either patient or learner. A CT biopsy phantom that is inexpensive and easy to produce would be an asset for IR education. This exhibit will describe the planning, development and construction of such a phantom and present data from an initial small pilot study. Commercial CT biopsy phantoms are available to assist the trainee; however, these devices cost upwards of $2200 and must be replaced after repeated use. This exhibit will demonstrate the construction of a CT biopsy phantom using common, non-toxic ingredients that cost approximately $20. The phantom allows core biopsies to be obtained and examined, which confirms technical success. Mastering these core fundamentals increases skill and confidence, leading to improved patient care and safety. Three trainees surveyed before and after completing a teaching session with the phantom all reported increased comfort performing and describing steps of CT guided percutaneous biopsy. Interventional radiologists must be proficient and confident in performing CT guided biopsies. Medical simulation training is an evolving component of radiology education that should be utilized in all teaching programs. We describe the construction of a low cost, easily made, and reusable CT biopsy phantom that can be used for IR education.

Synchrotron based planar imaging and digital tomosynthesis of breast and biopsy phantoms using a CMOS active pixel sensor

The SYRMEP (SYnchrotron Radiation for MEdical Physics) beamline at Elettra is performing the first mammography study on human patients using free-space propagation phase contrast imaging. The stricter spatial resolution requirements of this method currently force the use of conventional films or specialized computed radiography (CR) systems. This also prevents the implementation of three-dimensional (3D) approaches. This paper explores the use of an X-ray detector based on complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology as a possible alternative, for acquisitions both in planar and tomosynthesis geometry.Results indicate higher quality of the images acquired with the synchrotron set-up in both geometries. This improvement can be partly ascribed to the use of parallel, collimated and monochromatic synchrotron radiation (resulting in scatter rejection, no penumbra-induced blurring and optimized X-ray energy), and partly to phase contrast effects. Even though the pixel size of the used detector is still too large – and thus suboptimal – for free-space propagation phase contrast imaging, a degree of phase-induced edge enhancement can clearly be observed in the images.

Virtobot 2.0: the future of automated surface documentation and CT-guided needle placement in forensic medicine

In this paper we present the second prototype of a robotic system to be used in forensic medicine. The system is capable of performing automated surface documentation using photogrammetry, optical surface scanning and image-guided, post-mortem needle placement for tissue sampling, liquid sampling, or the placement of guide wires. The upgraded system includes workflow optimizations, an automatic tool-change mechanism, a new software module for trajectory planning and a fully automatic computed tomography-data-set registration algorithm. We tested the placement accuracy of the system by using a needle phantom with radiopaque markers as targets. The system is routinely used for surface documentation and resulted in 24 surface documentations over the course of 11months. We performed accuracy tests for needle placement using a biopsy phantom, and the Virtobot placed introducer needles with an accuracy of 1.4mm (±0.9mm). The second prototype of the Virtobot system is an upgrade of the first prototype but mainly focuses on streamlining the workflow and increasing the level of automation and also has an easier user interface. These upgrades make the Virtobot a potentially valuable tool for case documentation in a scalpel-free setting that uses purely imaging techniques and minimally invasive procedures and is the next step toward the future of virtual autopsy.

A purpose-built simulator for percutaneous ultrasound-guided renal biopsy

To construct a simple and affordable simulator for ultrasoundguided percutaneous renal biopsy. The kidney biopsy phantom was constructed by embedding a porcine kidney in gelatine. Silicon carbide and aluminium oxide were used as scattering particles in order to mimic the ultrasound appearance of human tissues. Two porcine ribs were also embedded. A latex sheet was placed over the top of the gel layer to resemble skin. The simulator was used and feedback from participants obtained during a renal ultrasound course with an international audience of middle-grade trainees from adult and pediatric nephrology, many of whom had never done a renal biopsy. Biopsy was carried out a single-use biopsy gun. All participants were able to perform a biopsy and obtain a satisfactory sample. All trainees felt that our simulator was very realistic. 94% of participants agreed that the simulator would help to allay their fears in relation to renal biopsy The total cost of the simulator was around £ 50,- for consumables per simulator. We describe a purpose-built and affordable simulator for percutaneous ultrasound-guided renal biopsy. We suggest that others evaluate our simulator used as part of a structured approach to teach this important procedure.

Low cost anatomically realistic renal biopsy phantoms for interventional radiology trainees

This paper describes manufacturing of economically affordable renal biopsy phantoms for radiology residents and practicing radiologists. We reconstructed a realistic 3-dimensional patient-specific kidney model from CT data, manufactured an organ mould and casted the kidney phantoms. Using gelatin gel materials with calibrated parameters allowed making phantoms with realistic mechanical, ultrasound and CT properties including various pathologies. The organ phantoms with cysts included were further casted into gelatin gel medium. They were validated by radiology residents in biopsy training and compared against self-made phantoms traditionally used in the curriculum of interventional radiology. The realism, durability, price and suitability for training were evaluated. The results showed that our phantoms are more realistic and easier to use than the traditional ones. Our proposed technology allows creating a low-cost (50$/kg) alternative to the pricy commercial training phantoms available today.

Sci-Fri AM: Imaging - 05: Principal Component X-Ray Simulation Analysis of Breast Biopsy Phantoms

Multivariate principal component analysis (PCA) was performed on x‐ray simulations of breast biopsy phantoms. Semianalytic models were used to generate scatter (Ns) and photon transmission (N) signals from mixtures of fibrous (i), cancerous (j), and adipose tissue (k). A 5mm diameter 30 kV Mo beam is incident on a 5 mm thick biopsy. The incident exposure is 5.08 × 10−4 C/kg. An energy discriminating photon counting detector is assumed (e.g. CZT). For simulation of scattermeasurements, the detector is placed at a scatter angle θ=10°, whereas for transmission θ=0°. The distance from the biopsy center to a 5 mm diameter aperture above the detector is 15 cm. The variables used in the PCA are Ns/N0 (16 keV), Ns/N0 (25 keV) and N/N0 (8 keV) where N0 is the incident spectrum. These variables are calculated 10 times. Each trial consists of biopsy shuffling of tissue blocks for a chosen fractional composition (i,j,k). A statistical component was incorporated in No. As a preliminary test to the classification model, a total of 66 different biopsies have been simulated and are used as unknowns. The PCA classes generated are based on a biopsy composed of 5 layers and 5 radii. The 66 unknown compositions were tested against the PCA classes to determine if the biopsy tissue composition could be identified. Of the 66 biopsies, 46 were correctly identified. An example of a misclassified unknown was for the composition (0,0.2,0.8) which was classified as (0.3,0,0.7). Further work is required to increase accuracy of identification.

Stable, Intelligible Ultrasonic Strain Imaging

BACKGROUND: Freehand quasistatic strain imaging can reveal qualitative information about tissue stiffness with good spatial accuracy. Clinical trials, however, repeatedly cite instability and variable signal-to-noise ratio as significant drawbacks. METHODS: This study investigates three post-processing strategies for quasistatic strain imaging. Normalisation divides the strain by an estimate of the stress field, the intention being to reduce sensitivity to variable applied stress. Persistence aims to improve the signal-to-noise ratio by time-averaging multiple frames. The persistence scheme presented in this article operates at the pixel level, weighting each frame's contribution by an estimate of the strain precision. Precision-based display presents the clinician with an image in which regions of indeterminate strain are obscured behind a colour wash. This is achieved using estimates of strain precision that are faithfully propagated through the various stages of signal processing. RESULTS AND DISCUSSION: The post-processing strategy is evaluated qualitatively on scans of a breast biopsy phantom and in vivo head and neck examinations. Strain images processed in this manner are observed to benefit from improved stability and signal-to-noise ratio. There are, however, limitations. In unusual though conceivable circumstances, the normalisation procedure might suppress genuine stiffness variations evident in the unprocessed strain images. In different circumstances, the raw strain images might fail to capture significant stiffness variations, a situation that no amount of post-processing can improve. CONCLUSION: The clinical utility of freehand quasistatic strain imaging can be improved by normalisation, precision-weighted pixel-level persistence and precision-based display. The resulting images are stable and generally exhibit a better signal-to-noise ratio than any of the original, unprocessed strain images.

Novel Homemade Trans-Rectal Ultrasound Biopsy Training Phantom

Ultrasound phantoms are very helpful in allowing the trainee to develop the necessary manual coordination skills before attempting any procedure on patients and compromising their safety. The construction of agar-based trans-rectal ultrasound prostatic biopsy phantom, using inexpensive and simple materials, is described. Features include tissue-equivalent reflectivity, the ability to implant targets for biopsy taking and reasonable shelf life of several weeks. Our phantom is an effective mean of training and skill acquisition for a one of the frequently performed invasive urological procedure.

Addition of Metamucil to Gelatin for a Realistic Breast Biopsy Phantom

Journal of Ultrasound in MedicineVolume 26, Issue 8 p. 1123-1126 Tips and Techniques Addition of Metamucil to Gelatin for a Realistic Breast Biopsy Phantom Helen Morehouse MD, Corresponding Author Helen Morehouse MD [email protected] Department of Radiology Bronx Lebanon Hospital, Bronx, New York USA.Address correspondence to Helen Morehouse, MD, Department of Radiology, Bronx Lebanon Hospital, 1650 Grand Concourse, Bronx, NY 10457 USA.Search for more papers by this authorHarshada Pranav Thaker MD, Harshada Pranav Thaker MD Department of Radiology Bronx Lebanon Hospital, Bronx, New York USA.Search for more papers by this authorChandowti Persaud RT, Chandowti Persaud RT Department of Radiology Bronx Lebanon Hospital, Bronx, New York USA.Search for more papers by this author Helen Morehouse MD, Corresponding Author Helen Morehouse MD [email protected] Department of Radiology Bronx Lebanon Hospital, Bronx, New York USA.Address correspondence to Helen Morehouse, MD, Department of Radiology, Bronx Lebanon Hospital, 1650 Grand Concourse, Bronx, NY 10457 USA.Search for more papers by this authorHarshada Pranav Thaker MD, Harshada Pranav Thaker MD Department of Radiology Bronx Lebanon Hospital, Bronx, New York USA.Search for more papers by this authorChandowti Persaud RT, Chandowti Persaud RT Department of Radiology Bronx Lebanon Hospital, Bronx, New York USA.Search for more papers by this author First published: 01 August 2007 https://doi.org/10.7863/jum.2007.26.8.1123Citations: 28Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume26, Issue8August 2007Pages 1123-1126 RelatedInformation

MR image-guided needle biopsies with a combination of augmented reality and MRI: A pilot study in phantoms and animals

The goal of this study was to adapt an augmented reality (AR) system to work next to a high-field (1.5 T) closed bore MR scanner (Magnetom Sonata, Siemens Medical Solutions, Erlangen, Germany) and to test its use as a navigation tool for MRI-guided needle biopsies. The AR system consists of a video-see-through head-mounted display with two color video cameras attached to the HMD that provide a stereoscopic view and a that is added for tracking. The tracking camera measures the viewer's position and orientation in relation to a set of optical markers on the MRI table. Gel phantoms with tube targets and multiple anatomic structures in two pigs were used as targets. For the biopsy phantom all punctures were inside the 6-mm diameter tube in the axial plane. The needle depth was within the target in 11 biopsies, 9 biopsies showed a slight deviation with a mean distance to the edge of the target slice of 1.5 mm. In the animals the puncture was successful in all 10 cases with a mean target-needle distance of 9.6 + 4.85 mm. The AR system presented here has proven to effectively facilitate image-guided percutaneous needle biopsies. MR images acquired shortly before the procedures are mapped into the patient space after moving the patient outside the magnet. This method provides a direct and intuitive way to perform percutaneous image-guided interventions with a closed bore MR scanner.

Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging

Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze–thaw process. The number of freeze–thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s−1, and the attenuation coefficients were in the range of 0.075–0.28 dB (cm MHz)−1. T1 and T2 relaxation values were found to be 718–1034 ms and 108–175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process.