Comparison of core needle breast biopsy techniques: freehand versus three-dimensional US guidance

Low-Cost and Easily Fabricated Ultrasound-Guided Breast Phantom for Breast Biopsy Training

We aimed to develop an inexpensive and easy-to-fabricate gelatin-based training phantom for improving the breast biopsy skill and confidence level of residents. Young’s modulus and acoustic properties of the gelatin tissue phantom and simulated tumors were investigated. Six residents were requested to evaluate the effectiveness of the breast phantom. The results showed that 83% (n = 5) of the participants agreed that the ultrasound image quality produced by the breast phantom was excellent or good. Only 17% (n = 1) of the participants claimed that there was room for improvement for the haptic feedback they received during the placement of the core needle into the breast phantom. The mean pre-instructional score was 17% (SD 17%) for all participants. The mean post-instructional score was 83% (SD 17%), giving an overall improvement of 67%. In conclusion, the mean needle biopsy skill and confidence levels of the participants substantially increased through simulation training on our breast phantom. The participants’ feedback showed the phantom is sufficiently realistic in terms of ultrasound imaging and haptic feedback during needle insertion; thus, the training outcome can be linked to the performance of residents when they perform a live biopsy.

Sonographic visibility of breast tissue markers: a tissue phantom comparison study

Rationale and objectives: Several commercially available breast tissue markers are promoted as being sonographically visible, allowing for subsequent targeting using ultrasound. The aim of this study was to compare the visibility of selected sonographic markers with the use of tissue phantoms.

Materials and methods: Seven different markers were deployed into chicken and beef tissue phantoms, including a non‐sonographically enhanced marker used as a baseline. Six participants assessed their sonographic visibility and needle targeted the markers using ultrasound. The sonographic visibility of each marker was graded, with scores corrected for accuracy following mammographic review of needle targeting position.

Results: Only four of the six “ultrasound enhanced” markers demonstrated statistically significant greater visibility than the non‐sonographically designed marker (P range < 0.001 to 0.04). Marker size (P < 0.001) and composition (P < 0.004) were shown to be contributing factors, with the composition of the BiomarC™ (Carbon Medical Technologies Inc, St Paul, MN, USA) demonstrating the highest conspicuity adjusted for length.

Conclusion: There is significant variance in the visibility of breast tissue markers purported to be visible on ultrasound. Marker size, composition and possibly shape are contributory factors, with the utilisation of non‐metallic components associated with improved conspicuity. Our study provides a basis for further determination of optimal marker qualities, and we recommend evaluation with a larger sample size and an “in‐vivo” technique.

Evaluation of the eZono 4000 with eZGuide for ultrasound-guided procedures

Ultrasound-guided procedures are increasingly common in a variety of acute care settings, such as the operating room, critical care unit and emergency room. However, accurate judgment of needle tip position using traditional ultrasound technology is frequently difficult, and serious injury can result from inadvertently advancing beyond or through the target. Needle navigation is a recent innovation that allows the clinician to visualize the needle position and trajectory in real time as it approaches the target. A novel ultrasound machine has recently been introduced that is portable and designed for procedural guidance. The eZono 4000™ features an innovative needle navigation technology that is simple to use and permits the use of a wide range of commercially available needles, avoiding the inconvenience and cost of proprietary equipment. This article discusses this new ultrasound machine in the context of other currently available ultrasound machines featuring needle navigation.

Simultaneous ultrasound and MRI system for breast biopsy: compatibility assessment and demonstration in a dual modality phantom

Simultaneous capturing of ultrasound (US) and magnetic resonance (MR) images allows fusion of information obtained from both modalities. We propose an MR-compatible US system where MR images are acquired in a known orientation with respect to the US imaging plane and concurrent real-time imaging can be achieved. Compatibility of the two imaging devices is a major issue in the physical setup. Tests were performed to quantify the radio frequency (RF) noise introduced in MR and US images, with the US system used in conjunction with MRI scanner of different field strengths (0.5 T and 3 T). Furthermore, simultaneous imaging was performed on a dual modality breast phantom in the 0.5 T open bore and 3 T close bore MRI systems to aid needle-guided breast biopsy. Fiducial based passive tracking and electromagnetic based active tracking were used in 3 T and 0.5 T, respectively, to establish the location and orientation of the US probe inside the magnet bore. Our results indicate that simultaneous US and MR imaging are feasible with properly-designed shielding, resulting in negligible broadband noise and minimal periodic RF noise in both modalities. US can be used for real time display of the needle trajectory, while MRI can be used to confirm needle placement.

Evaluation of 11-gauge and 9-gauge vacuum-assisted breast biopsy systems in a breast parenchymal model

RATIONALE AND OBJECTIVES

To compare three commercially available vacuum-assisted breast biopsy systems for tissue yield, length and fragmentation of specimens.

MATERIALS AND METHODS

Specimens were acquired from radiolucent (bacon) and radioopaque (turkey breast) tissue using three different commercially available vacuum-assisted breast biopsy devices. Two systems (system 1 and 2) were equipped with 11 G needles, one system (system 3) with a 9 G needle. As for systems 1 and 2 a second chamber for applying the vacuum is attached to the needle, the external maximum diameter was identical for all three systems. 48 specimens were taken out for each tissue type and for each device. Specimens were measured for total weight, individual length, and number of fragments. Differences between groups were analyzed using analysis of variance (ANOVA) and Student's t-test.

RESULTS

For both tissue types, system 1 and 2 showed similar results, for system 3 tissue weight and length of specimens were larger. Differences in lengths and weight were statistically significant between system 1 and 3 and system 2 and 3 (ANOVA, P < 0.05). Differences between length and weight were statistically significant between tissue 1 and 2 for all devices (t-Test < 0.05).

CONCLUSION

As for system 3 a larger tissue yield was obtained with the same number of specimens compared to systems 1 and 2, it can be assumed that the same diagnostic accuracy as for systems 1 and 2 may be achieved for system 3 with less passes through tissue.

3D TRUS Image Segmentation in Prostate Brachytherapy

Brachytherapy is a minimally invasive interventional surgery used to treat prostate cancer. It is composed of three steps: dose pre-planning, implantation of radioactive seeds, and dose post-planning. In these procedures, it is crucial to determine the positions of needles and seeds, measure the volume of the prostate gland. Three-dimensional transrectal ultrasound (TRUS) imaging has been demonstrated to be a useful technique to perform such tasks. Compared to CT, MRI or X-ray imaging, US image suffers from low contrast, image speckle and shadows, making it challenging for segmentation of needles, the prostates and seeds in the 3D TRUS images. In this paper, we reviewed 3D TRUS image segmentation methods used in prostate brachytherapy including the segmentations of the needles, the prostate, as well as the seeds. Furthermore, some experimental results with agar phantom, turkey and chicken phantom, as well as the patient data are reported.

Automated localization of implanted seeds in 3D TRUS images used for prostate brachytherapy

An algorithm has been developed in this paper to localize implanted radioactive seeds in 3D ultrasound images for a dynamic intraoperative brachytherapy procedure. Segmentation of the seeds is difficult, due to their small size in relatively low quality of transrectal ultrasound (TRUS) images. In this paper, intraoperative seed segmentation in 3D TRUS images is achieved by performing a subtraction of the image before the needle has been inserted, and the image after the seeds have been implanted. The seeds are searched in a "local" space determined by the needle position and orientation information, which are obtained from a needle segmentation algorithm. To test this approach, 3D TRUS images of the agar and chicken tissue phantoms were obtained. Within these phantoms, dummy seeds were implanted. The seed locations determined by the seed segmentation algorithm were compared with those obtained from a volumetric cone-beam flat-panel micro-CT scanner and human observers. Evaluation of the algorithm showed that the rms error in determining the seed locations using the seed segmentation algorithm was 0.98 mm in agar phantoms and 1.02 mm in chicken phantoms.

Oblique needle segmentation and tracking for 3D TRUS guided prostate brachytherapy

An algorithm was developed in order to segment and track brachytherapy needles inserted along oblique trajectories. Three-dimensional (3D) transrectal ultrasound (TRUS) images of the rigid rod simulating the needle inserted into the tissue-mimicking agar and chicken breast phantoms were obtained to test the accuracy of the algorithm under ideal conditions. Because the robot possesses high positioning and angulation accuracies, we used the robot as a "gold standard," and compared the results of algorithm segmentation to the values measured by the robot. Our testing results showed that the accuracy of the needle segmentation algorithm depends on the needle insertion distance into the 3D TRUS image and the angulations with respect to the TRUS transducer, e.g., at a 10 degrees insertion anglulation in agar phantoms, the error of the algorithm in determining the needle tip position was less than 1 mm when the insertion distance was greater than 15 mm. Near real-time needle tracking was achieved by scanning a small volume containing the needle. Our tests also showed that, the segmentation time was less than 60 ms, and the scanning time was less than 1.2 s, when the insertion distance into the 3D TRUS image was less than 55 mm. In our needle tracking tests in chicken breast phantoms, the errors in determining the needle orientation were less than 2 degrees in robot yaw and 0.7 degrees in robot pitch orientations, for up to 20 degrees needle insertion angles with the TRUS transducer in the horizontal plane when the needle insertion distance was greater than 15 mm.

Brachytherapy needle deflection evaluation and correction

In prostate brachytherapy, an 18-gauge needle is used to implant radioactive seeds. This thin needle can be deflected from the preplanned trajectory in the prostate, potentially resulting in a suboptimum dose pattern and at times requiring repeated needle insertion to achieve optimal dosimetry. In this paper, we report on the evaluation of brachytherapy needle deflection and bending in test phantoms and two approaches to overcome the problem. First we tested the relationship between needle deflection and insertion depth as well as whether needle bending occurred. Targeting accuracy was tested by inserting a brachytherapy needle to target 16 points in chicken tissue phantoms. By implanting dummy seeds into chicken tissue phantoms under 3D ultrasound guidance, the overall accuracy of seed implantation was determined. We evaluated methods to overcome brachytherapy needle deflection with three different insertion methods: constant orientation, constant rotation, and orientation reversal at half of the insertion depth. Our results showed that needle deflection is linear with needle insertion depth, and that no noticeable bending occurs with needle insertion into the tissue and agar phantoms. A 3D principal component analysis was performed to obtain the population distribution of needle tip and seed position relative to the target positions. Our results showed that with the constant orientation insertion method, the mean needle targeting error was 2.8 mm and the mean seed implantation error was 2.9 mm. Using the constant rotation and orientation reversal at half insertion depth methods, the deflection error was reduced. The mean needle targeting errors were 0.8 and 1.2 mm for the constant rotation and orientation reversal methods, respectively, and the seed implantation errors were 0.9 and 1.5 mm for constant rotation insertion and orientation reversal methods, respectively.

3D ultrasound guided breast biopsy system

Stereotactic X-ray mammography (SM) and ultrasound (US) guidance are commonly used techniques for breast biopsy. While SM provides 3D targeting information and US provides real-time guidance, both techniques have limitations. SM is a long and uncomfortable procedure and the US guided procedure is inherently 2D, requiring a skilled physician for both safety and accuracy. We have developed a 3D US-guided biopsy system to integrate with SM. The dual modality breast biopsy system combines the advantages of both approaches with 3D US and SM targeting, near real-time 3D and real-time 2D US guidance, breast stabilisation and a confined needle trajectory. Our goal is to be able to biopsy a larger percentage of suspicious masses using ultrasound, by clarifying ambiguous structures with mammographic imaging. Using breast phantoms, we have shown that our ultrasound guided biopsy system was capable of targeting artificial lesions that were 3.2 mm in diameter, with a 96% success rate. Through this study, we also demonstrated that our system was equivalent to current clinical practice, for an in vitro biopsy task. Metal beads in known relative positions allowed us to determine the geometry of the SM system, so that stereotactic mammography could be registered to 3D US images. The target registration error was found to be 1.6 mm. This error was dominated by positioning error in the vertical direction (perpendicular to the film surface). As an adjunct to SM, we propose that 3D US could provide more complete imaging information for target identification and real-time monitoring of needle insertion, as well as providing a means for rapid confirmation of biopsy success.

Usefulness of three-dimensional sonography in procedures of ablation for liver cancers: initial experience

OBJECTIVE

To investigate the usefulness of three-dimensional sonography in procedures of ablation for liver cancers.

METHODS

Two- and three-dimensional sonography were used in guiding 18 chemical ablation procedures (7 with boiling carboplatin ablation and 11 with ethanol ablation) and 21 radio frequency ablation procedures for treatment of liver cancers. The applicator conspicuity depicted by the 2 imaging modalities, the confidence level of the operator in determining the position relationship between the applicator and the tumor using the 2 imaging modalities, and the alteration of ablation procedures were evaluated.

RESULTS

Three-dimensional sonography was better than two-dimensional sonography in delineation of multitined, expandable electrode tips in radio frequency ablation procedures, whereas the 2 modalities were equal in depicting percutaneous transhepatic cholangiography needle tips in chemical ablation procedures. Three-dimensional sonography significantly enhanced the confidence level in defining the spatial relationship between applicator and tumor in comparison with two-dimensional sonography (P < .01). Suboptimal applicator placement was detected in 6 (15%) of 39 ablation procedures on three-dimensional sonography: 3 chemical ablation procedures and 3 radio frequency ablation procedures. Applicator adjustment was required in 3 chemical ablation procedures. In 15 (38%) of 39 procedures, three-dimensional sonography allowed better visualization of the position relationship between the applicator and adjacent critical structures.

CONCLUSIONS

Three-dimensional sonography was useful in delineation of expandable radio frequency electrodes, improvement of operator confidence level, determination of applicator placement, and visualization of the position relationship between the applicator and adjacent critical structures during procedures of liver cancer ablation under image guidance.

The development and evaluation of a three-dimensional ultrasound-guided breast biopsy apparatus

We have designed a prototype three-dimensional ultrasound guidance (3D USB) apparatus to improve the breast biopsy procedure. Features from stereotactic mammography and free-hand US-guided biopsy have been combined with 3D US imaging. This breast biopsy apparatus accurately guides a needle into position for the sampling of target tissue. We have evaluated this apparatus in three stages. First, by testing the placement accuracy of a needle in a tissue mimicking phantom. Second, with tissue mimicking phantoms that had embedded lesions for biopsy. Finally, by comparison to free-hand US-guided biopsy, using chicken breast phantoms. The first two stages of evaluation quantified the mechanical biases in the 3D USB apparatus. Compensating for these, a 96% success rate in targeting 3.2 mm "lesions" in chicken breast phantoms was achieved when using the 3D USB apparatus. The expert radiologists performing biopsies with free-hand US guidance achieved a 94.5% success rate. This has proven an equivalence between our apparatus, operated by non-experts, and free-hand biopsy performed by expert radiologists, for 3.2 mm lesions in vitro, with a 95% confidence.