Three-dimensional ultrasound-guided core needle breast biopsy

Development and Preliminary Evaluation of a Robotic Device for MRI-Guided Needle Breast Biopsy

This study concerns the development and evaluation of a simple and ergonomic robotic system for Magnetic Resonance Imaging (MRI)-guided needle breast biopsy with lateral needle approach. The device comprises two piezoelectrically actuated linear motion stages intended to align a needle supporter with the target for manual needle insertion. The device demonstrated submillimeter accuracy and safe operation within a 3 T clinical MRI scanner. In phantom studies, tumor simulators of varying sizes were successfully targeted in both laboratory and MRI settings.

Uncertainty Estimation for Dual View X-ray Mammographic Image Registration Using Deep Ensembles

Techniques are developed for generating uncertainty estimates for convolutional neural network (CNN)-based methods for registering the locations of lesions between the craniocaudal (CC) and mediolateral oblique (MLO) mammographic X-ray image views. Multi-view lesion correspondence is an important task that clinicians perform for characterizing lesions during routine mammographic exams. Automated registration tools can aid in this task, yet if the tools also provide confidence estimates, they can be of greater value to clinicians, especially in cases involving dense tissue where lesions may be difficult to see. A set of deep ensemble-based techniques, which leverage a negative log-likelihood (NLL)-based cost function, are implemented for estimating uncertainties. The ensemble architectures involve significant modifications to an existing CNN dual-view lesion registration algorithm. Three architectural designs are evaluated, and different ensemble sizes are compared using various performance metrics. The techniques are tested on synthetic X-ray data, real 2D X-ray data, and slices from real 3D X-ray data. The ensembles generate covariance-based uncertainty ellipses that are correlated with registration accuracy, such that the ellipse sizes can give a clinician an indication of confidence in the mapping between the CC and MLO views. The results also show that the ellipse sizes can aid in improving computer-aided detection (CAD) results by matching CC/MLO lesion detects and reducing false alarms from both views, adding to clinical utility. The uncertainty estimation techniques show promise as a means for aiding clinicians in confidently establishing multi-view lesion correspondence, thereby improving diagnostic capability.

Medical instrument detection in ultrasound: a review

Medical instrument detection is essential for computer-assisted interventions, since it facilitates clinicians to find instruments efficiently with a better interpretation, thereby improving clinical outcomes. This article reviews image-based medical instrument detection methods for ultrasound-guided (US-guided) operations. Literature is selected based on an exhaustive search in different sources, including Google Scholar, PubMed, and Scopus. We first discuss the key clinical applications of medical instrument detection in the US, including delivering regional anesthesia, biopsy taking, prostate brachytherapy, and catheterization. Then, we present a comprehensive review of instrument detection methodologies, including non-machine-learning and machine-learning methods. The conventional non-machine-learning methods were extensively studied before the era of machine learning methods. The principal issues and potential research directions for future studies are summarized for the computer-assisted intervention community. In conclusion, although promising results have been obtained by the current (non-) machine learning methods for different clinical applications, thorough clinical validations are still required.

Versatile Low-Cost Volumetric 3-D Ultrasound Platform for Existing Clinical 2-D Systems

Ultrasound imaging has indications across many areas of medicine, but the need for training and the variability in skill and acquired image quality among 2-D ultrasound users have limited its wider adoption and utilization. Low-cost volumetric ultrasound with a known frame of reference has the potential to lower these operator-dependent barriers and enhance the clinical utility of ultrasound imaging. In this paper, we improve upon our previous research-scanner-based prototype to implement a versatile volumetric imaging platform for existing clinical 2-D ultrasound systems. We present improved data acquisition and image reconstruction schemes to increase quality, streamline workflow, and provide real-time visual feedback. We present initial results using the platform on a Vimedix simulator, as well as on phantom and in vivo targets using a variety of clinical ultrasound systems and probes.

Ultrasound Imaging Technologies for Breast Cancer Detection and Management: A Review

Ultrasound imaging is a commonly used modality for breast cancer detection and diagnosis. In this review, we summarize ultrasound imaging technologies and their clinical applications for the management of breast cancer patients. The technologies include ultrasound elastography, contrast-enhanced ultrasound, 3-D ultrasound, automatic breast ultrasound and computer-aided detection of breast ultrasound. We summarize the study results seen in the literature and discuss their future directions. We also provide a review of ultrasound-guided, breast biopsy and the fusion of ultrasound with other imaging modalities, especially magnetic resonance imaging (MRI). For comparison, we also discuss the diagnostic performance of mammography, MRI, positron emission tomography and computed tomography for breast cancer diagnosis at the end of this review. New ultrasound imaging techniques, ultrasound-guided biopsy and the fusion of ultrasound with other modalities provide important tools for the management of breast patients.

3D ultrasound imaging in image-guided intervention

Ultrasound imaging is used extensively in diagnosis and image-guidance for interventions of human diseases. However, conventional 2D ultrasound suffers from limitations since it can only provide 2D images of 3-dimensional structures in the body. Thus, measurement of organ size is variable, and guidance of interventions is limited, as the physician is required to mentally reconstruct the 3-dimensional anatomy using 2D views. Over the past 20 years, a number of 3-dimensional ultrasound imaging approaches have been developed. We have developed an approach that is based on a mechanical mechanism to move any conventional ultrasound transducer while 2D images are collected rapidly and reconstructed into a 3D image. In this presentation, 3D ultrasound imaging approaches will be described for use in image-guided interventions.

Paraffin-gel tissue-mimicking material for ultrasound-guided needle biopsy phantom

Paraffin-gel waxes have been investigated as new soft tissue-mimicking materials for ultrasound-guided breast biopsy training. Breast phantoms were produced with a broad range of acoustical properties. The speed of sound for the phantoms ranged from 1425.4 ± 0.6 to 1480.3 ± 1.7 m/s at room temperature. The attenuation coefficients were easily controlled between 0.32 ± 0.27 dB/cm and 2.04 ± 0.65 dB/cm at 7.5 MHz, depending on the amount of carnauba wax added to the base material. The materials do not suffer dehydration and provide adequate needle penetration, with a Young's storage modulus varying between 14.7 ± 0.2 kPa and 34.9 ± 0.3 kPa. The phantom background material possesses long-term stability and can be employed in a supine position without changes in geometry. These results indicate that paraffin-gel waxes may be promising materials for training radiologists in ultrasound biopsy procedures.

Three-dimensional ultrasound scanning

The past two decades have witnessed developments of new imaging techniques that provide three-dimensional images about the interior of the human body in a manner never before available. Ultrasound (US) imaging is an important cost-effective technique used routinely in the management of a number of diseases. However, two-dimensional viewing of three-dimensional anatomy, using conventional two-dimensional US, limits our ability to quantify and visualize the anatomy and guide therapy, because multiple two-dimensional images must be integrated mentally. This practice is inefficient, and may lead to variability and incorrect diagnoses. Investigators and companies have addressed these limitations by developing three-dimensional US techniques. Thus, in this paper, we review the various techniques that are in current use in three-dimensional US imaging systems, with a particular emphasis placed on the geometric accuracy of the generation of three-dimensional images. The principles involved in three-dimensional US imaging are then illustrated with a diagnostic and an interventional application: (i) three-dimensional carotid US imaging for quantification and monitoring of carotid atherosclerosis and (ii) three-dimensional US-guided prostate biopsy.

Integration and evaluation of a needle-positioning robot with volumetric microcomputed tomography image guidance for small animal stereotactic interventions

PURPOSE

Preclinical research protocols often require insertion of needles to specific targets within small animal brains. To target biologically relevant locations in rodent brains more effectively, a robotic device has been developed that is capable of positioning a needle along oblique trajectories through a single burr hole in the skull under volumetric microcomputed tomography (micro-CT) guidance.

METHODS

An x-ray compatible stereotactic frame secures the head throughout the procedure using a bite bar, nose clamp, and ear bars. CT-to-robot registration enables structures identified in the image to be mapped to physical coordinates in the brain. Registration is accomplished by injecting a barium sulfate contrast agent as the robot withdraws the needle from predefined points in a phantom. Registration accuracy is affected by the robot-positioning error and is assessed by measuring the surface registration error for the fiducial and target needle tracks (FRE and TRE). This system was demonstrated in situ by injecting 200 microm tungsten beads into rat brains along oblique trajectories through a single burr hole on the top of the skull under micro-CT image guidance. Postintervention micro-CT images of each skull were registered with preintervention high-field magnetic resonance images of the brain to infer the anatomical locations of the beads.

RESULTS

Registration using four fiducial needle tracks and one target track produced a FRE and a TRE of 96 and 210 microm, respectively. Evaluation with tissue-mimicking gelatin phantoms showed that locations could be targeted with a mean error of 154 +/- 113 microm.

CONCLUSIONS

The integration of a robotic needle-positioning device with volumetric micro-CT image guidance should increase the accuracy and reduce the invasiveness of stereotactic needle interventions in small animals.

Three-dimensional ultrasound guidance of autonomous robotic breast biopsy: feasibility study

Feasibility studies of autonomous robot biopsies in tissue have been conducted using real-time three-dimensional (3-D) ultrasound combined with simple thresholding algorithms. The robot first autonomously processed 3-D image volumes received from the ultrasound scanner to locate a metal rod target embedded in turkey breast tissue simulating a calcification, and in a separate experiment, the center of a water-filled void in the breast tissue simulating a cyst. In both experiments the robot then directed a needle to the desired target, with no user input required. Separate needle-touch experiments performed by the image-guided robot in a water tank yielded an rms error of 1.15 mm. (E-mail: kaicheng.liang@duke.edu).

Detection of focal liver lesions: from the subjectivity of conventional ultrasound to the objectivity of volume ultrasound

PURPOSE

This study was undertaken to establish the reliability of automated volumetric liver scans in detecting focal liver lesions by evaluating the degree of agreement between conventional and volume ultrasound (US) examinations.

MATERIALS AND METHODS

Over a period of 3 months, we prospectively studied 100 consecutive patients (36 men and 64 women; age range 15-87 years; mean age 63 years) referred to our institute for US imaging of the liver. Volumetric acquisition of the liver was achieved with a 3D transducer (2.0-5.0 MHz) and a Logiq 9 US scanner. All patients underwent both 2- and 3D US studies performed by two expert radiologists. Volumetric acquisitions were subsequently reviewed by the second radiologist, who was blinded to the first radiologist's report. Three categories were established: 1=presence of focal liver lesions; 2=doubtful finding; 3=absence of focal liver lesions. Concordance between volume US and conventional US was calculated by using the k statistic.

RESULTS

Out of 100 patients examined, 39 were found to be affected by focal liver lesions. All volume US examinations were technically adequate, allowing exploration of all hepatic sectors, except for five cases that were marred by major respiratory motion artefacts. Conventional and volume US identified the same number of focal liver lesions, with the exception of four cases of doubtful findings at volume US. Concordance between automated volume US and conventional US of the liver was high (k=0.92).

CONCLUSIONS

The identification of focal liver lesions on automated volume US is possible, and the examination shows a high level of concordance with conventional US.

A 256 x 256 2-D array transducer with row-column addressing for 3-D rectilinear imaging

We present simulation and experimental results from a 5-MHz, 256 x 256 2-D (65,536 elements, 38.4 x 38.4 mm) 2-D array transducer with row-column addressing. The main benefits of this design are a reduced number of interconnects, a modified transmit/receive switching scheme with a simple diode circuit, and an ability to perform volumetric imaging of targets near the transducer with transmit beamforming in azimuth and receive beamforming in elevation. The final dimensions of the transducer were 38.4 mm x 38.4 mm x 300 microm. After a row-column transducer was prototyped, the series resonance impedance was 104 Omega at 5.4 MHz. The measured -6 dB fractional bandwidth was 53% with a center frequency of 5.3 MHz. The SNR at the transmit focus was measured to be 30 dB. At 5 MHz, the average nearest neighbor crosstalk was -25 dB. In this paper, we present 3-D images of both 5 pairs of nylon wires embedded in a clear gelatin phantom and an 8 mm diameter cylindrical anechoic cyst phantom acquired from a 256 x 256 2-D array transducer made from a 1-3 composite. We display the azimuth and elevation B-scans as well as the C-scan for each image. The cross-section of the wires is visible in the azimuth B-scan, and the long axes can be seen in the elevation B-scan and C-scans. The pair of wires with 1-mm axial separation is discernible in the elevational B-scan. When a single wire from the wire target phantom was used, the measured lateral beamwidth was 0.68 mm and 0.70 mm at 30 mm depth in transmit beamforming and receive beamforming, respectively, compared with the simulated beamwidth of 0.55 mm. The cross-section of the cyst is visible in the azimuth B-scan whereas the long axes can be seen as a rectangle in the elevation B-scan and C-scans.

A dual-layer transducer array for 3-D rectilinear imaging

Very large element counts (16,000-65,000) are required for 2-D arrays for 3-D rectilinear imaging. The difficulties in fabricating and interconnecting 2-D arrays with a large number of elements (>5,000) have limited the development of suitable transducers for 3-D rectilinear imaging. In this paper, we propose an alternative solution to this problem by using a dual-layer transducer array design. This design consists of 2 perpendicular 1-D arrays for clinical 3-D imaging of targets near the transducer. These targets include the breast, carotid artery, and musculoskeletal system. This transducer design reduces the fabrication complexity and the channel count, making 3-D rectilinear imaging more realizable. With this design, an effective N x N 2-D array can be developed using only N transmitters and N receivers. This benefit becomes very significant when N becomes greater than 128, for example. To demonstrate feasibility, we constructed a 4 x 4 cm prototype dual-layer array. The transmit array uses diced PZT-5H elements, and the receive array is a single sheet of undiced P[VDF-TrFE] copolymer. The receive elements are defined by the copper traces on the flexible interconnect circuit. The measured -6 dB fractional bandwidth was 80% with a center frequency of 4.8 MHz. At 5 MHz, the nearest neighbor crosstalk of the PZT array and PVDF array was -30.4 +/- 3.1 dB and -28.8 +/- 3.7 dB, respectively. This dual-layer transducer was interfaced with an Ultrasonix Sonix RP system, and a synthetic aperture 3-D data set was acquired. We then performed offline 3-D beamforming to obtain volumes of nylon wire targets. The theoretical lateral beamwidth was 0.52 mm compared with measured beamwidths of 0.65 mm and 0.67 mm in azimuth and elevation, respectively. Then, 3-D images of an 8 mm diameter anechoic cyst phantom were also acquired.

Registered 3-D ultrasound and digital stereotactic mammography for breast biopsy guidance

Large core needle biopsy is a common procedure used to obtain histological samples when cancer is suspected in diagnostic breast images. The procedure is typically performed under image guidance, with freehand ultrasound and stereotactic mammography (SM) being the most common modalities used. To utilize the advantages of both modalities, a biopsy device combining three-dimensional ultrasound (3DUS) and digital SM imaging with computer-aided needle guidance was developed. An implementation of a stereo camera method was applied to SM calibration, providing a target localization error of 0.35 mm. The 3-D transformation between the two imaging modalities was then derived, with a target registration error of 0.52 mm. Finally, the needle guidance error of the device was evaluated using tissue-mimicking phantoms, showing a sample mean and standard deviation of 0.44 +/- 0.22 and 0.49 +/- 0.27 mm for targets planned from 3DUS and SM images, respectively. These results suggest that a biopsy procedure guided using this device would successfully sample breast lesions at a size greater than or equal to the smallest typically detected in mammographic screening (approximately 2 mm).

Stereotactic mammography imaging combined with 3D US imaging for image guided breast biopsy

Stereotactic X-ray mammography (SM) and ultrasound (US) guidance are both commonly used for breast biopsy. While SM provides three-dimensional (3D) targeting information and US provides real-time guidance, both have limitations. SM is a long and uncomfortable procedure and the US guided procedure is inherently two dimensional (2D), requiring a skilled physician for both safety and accuracy. The authors developed a 3D US-guided biopsy system to be integrated with, and to supplement SM imaging. Their goal is to be able to biopsy a larger percentage of suspicious masses using US, by clarifying ambiguous structures with SM imaging. Features from SM and US guided biopsy were combined, including breast stabilization, a confined needle trajectory, and dual modality imaging. The 3D US guided biopsy system uses a 7.5 MHz breast probe and is mounted on an upright SM machine for preprocedural imaging. Intraprocedural targeting and guidance was achieved with real-time 2D and near real-time 3D US imaging. Postbiopsy 3D US imaging allowed for confirmation that the needle was penetrating the target. The authors evaluated 3D US-guided biopsy accuracy of their system using test phantoms. To use mammographic imaging information, they registered the SM and 3D US coordinate systems. The 3D positions of targets identified in the SM images were determined with a target localization error (TLE) of 0.49 mm. The z component (x-ray tube to image) of the TLE dominated with a TLEz of 0.47 mm. The SM system was then registered to 3D US, with a fiducial registration error (FRE) and target registration error (TRE) of 0.82 and 0.92 mm, respectively. Analysis of the FRE and TRE components showed that these errors were dominated by inaccuracies in the z component with a FREz of 0.76 mm and a TREz of 0.85 mm. A stereotactic mammography and 3D US guided breast biopsy system should include breast compression for stability and safety and dual modality imaging for target localization. The system will provide preprocedural x-ray mammography information in the form of SM imaging along with real-time US imaging for needle guidance to a target. 3D US imaging will also be available for targeting, guidance, and biopsy verification immediately postbiopsy.

Fast prostate segmentation in 3D TRUS images based on continuity constraint using an autoregressive model

In this article a new slice-based 3D prostate segmentation method based on a continuity constraint, implemented as an autoregressive (AR) model is described. In order to decrease the propagated segmentation error produced by the slice-based 3D segmentation method, a continuity constraint was imposed in the prostate segmentation algorithm. A 3D ultrasound image was segmented using the slice-based segmentation method. Then, a cross-sectional profile of the resulting contours was obtained by intersecting the 2D segmented contours with a coronal plane passing through the midpoint of the manually identified rotational axis, which is considered to be the approximate center of the prostate. On the coronal cross-sectional plane, these intersections form a set of radial lines directed from the center of the prostate. The lengths of these radial lines were smoothed using an AR model. Slice-based 3D segmentations were performed in the clockwise and in the anticlockwise directions, where clockwise and anticlockwise are defined with respect to the propagation directions on the coronal view. This resulted in two different segmentations for each 2D slice. For each pair of unmatched segments, in which the distance between the contour generated clockwise and that generated anticlockwise was greater than 4 mm, a method was used to select the optimal contour. Experiments performed using 3D prostate ultrasound images of nine patients demonstrated that the proposed method produced accurate 3D prostate boundaries without manual editing. The average distance between the proposed method and manual segmentation was 1.29 mm. The average intraobserver coefficient of variation (i.e., the standard deviation divided by the average volume) of the boundaries segmented by the proposed method was 1.6%. The average segmentation time of a 352 x 379 x 704 image on a Pentium IV 2.8 GHz PC was 10 s.

A biplanar fluoroscopic approach for the measurement, modeling, and simulation of needle and soft-tissue interaction

A methodology for modeling the needle and soft-tissue interaction during needle insertion is presented. The approach consists of the measurement of needle and tissue motion using a dual C-arm fluoroscopy system. Our dual C-arm fluoroscopy setup allows real time 3-D extraction of the displacement of implanted fiducials in the soft tissue during needle insertion to obtain the necessary parameters for accurate modeling of needle and soft-tissue interactions. The needle and implanted markers in the tissue are tracked during the insertion and withdrawal of the needle at speeds of 1.016 mm/s, 12.7 mm/s and 25.4 mm/s. Both image and force data are utilized to determine important parameters such as the approximate cutting force, puncture force, the local effective modulus (LEM) during puncture, and the relaxation of tissue. We have also validated the LEM computed from our finite element model with arbitrary needle puncture tasks. Based on these measurements, we developed a model for needle insertion and withdrawal that can be used to generate a 1-DOF force versus position profile that can be experienced by a user operating a haptic device. This profile was implemented on a 7-DOf haptic device designed in our laboratory.

Interventional procedures in superficial lesions: the value of 2D with additional coronal reformatted 4D ultrasonography guidance

Objective

We wanted to assess the usefulness of four-dimensional (4D) ultrasonography (US), i.e., real-time three-dimensional US, as an adjunct for performing various US-guided interventional procedures in superficial lesions.

Materials and Methods

Thirty-three patients were referred for US-guided interventional procedures for superficial lesions, including core biopsy in 19, fine-needle aspiration in eight, therapeutic drug injection in four and needle puncture in two. The procedures were performed under 4D US guidance. We reviewed the pathologic/cytologic results of the core biopsies or needle aspirations, and also the outcomes of drug injection or needle puncture.

Results

For all the patients who underwent 4D US-guided core biopsy, the specimens were adequate for making the pathological diagnosis, and specimens were successfully obtained for those patients who underwent 4D US-guided aspiration. The patients treated with 4D US-guided therapeutic drug injection or needle puncture had a good response. No major procedure-related complications occurred. The procedural times were similar to those procedural times with using two-dimensional US.

Conclusion

Combining the two dimensional and 4D US techniques aids the physician when performing US-guided interventional procedures for the superficial lesions.

2-D array for 3-D ultrasound imaging using synthetic aperture techniques

A two-dimensional (2-D) array of 256 X 256 = 65,536 elements, with total area 4 X 4 = 16 cm2, serves as a flexible platform for developing acquisition schemes for 3-D rectilinear ultrasound imaging at 10 MHz using synthetic aperture techniques. This innovative system combines a simplified interconnect scheme and synthetic aperture techniques with a 2-D array for 3-D imaging. A row-column addressing scheme is used to access different elements for different transmit events. This addressing scheme is achieved through a simple interconnect, consisting of one top, one bottom single-layer, flex circuits that, compared to multilayer flex circuits, are simpler to design, cheaper to manufacture, and thinner so their effect on the acoustic response is minimized. We present three designs that prioritize different design objectives: volume acquisiton time, resolution, and sensitivity, while maintaining acceptable figures for the other design objectives. For example, one design overlooks time-acquisition requirements, assumes good noise conditions, and optimizes for resolution, achieving -6 dB and -20 dB beamwidths of less than 0.2 and 0.5 mm, respectively, for an F/2 aperture. Another design can acquire an entire volume in 256 transmit events, with -6 dB and -20 dB beamwidths in the order of 0.4 and 0.8 mm, respectively.

Methods for segmenting curved needles in ultrasound images

Ultrasound-guided percutaneous needle insertions are widely used techniques in current clinical practice. Some of these procedures have a high degree of difficulty because of poor observability of the needle in the ultrasound image. There have been recent efforts to improve guidance by computer assisted needle detection. These software techniques are often limited by not representing needle curvature. We present two methods to detect the needle in 2D ultrasound that specifically address needle curvature. Firstly, we demonstrate a real-time needle segmentation algorithm based on the Hough transform which detects the needle and represents its curved shape. Secondly, we demonstrate how a new coordinate transformation can transform detection of a curved needle to a linear fit. These methods are demonstrated on ultrasound and photographic images.

Projection-based needle segmentation in 3D ultrasound images

Needles are used extensively in interventional procedures such as biopsy and brachytherapy. To deliver radioactive seeds to pre-planned positions or sample lesions from the region that may contain cancer cells, the 3D position of the needle must be determined accurately and quickly. Three-dimensional ultrasound (US) image guidance is an efficient technique used to perform this task. In this paper, we describe the development of a projection-based needle segmentation method comprising three steps. First, the 3D image is projected along an initial direction perpendicular to the approximate needle direction determined from the 3D imaging system. The needle is then segmented in a projected 2D image. Using the projection direction and the detected 2D needle direction, a plane containing the needle--called the needle plane--is determined. Secondly, the 3D image is re-projected in the direction perpendicular to the normal of the needle plane and step 1 is repeated. If the needle direction in the projected 2D image is horizontal, the needle plane is correct; otherwise, steps 1 and 2 are repeated until a correct needle plane is found. Thirdly, the 3D image is projected along the normal direction of the needle plane and the needle endpoints in the projected 2D image are determined. Using the relationship between the 3D projection and the 3D volume coordinate systems, the coordinates of the endpoints of the needle in the 3D US coordinate system are determined. Experiments with agar and turkey phantom 3D US images demonstrated that our method could segment the needle from 3D US images with an average accuracy of 0.7 mm in position and 1.2 degrees in orientation with a speed of 13 fps on a 1.3-GHz PC. In addition, experiments illustrated that our method is robust to variations in the initial estimated needle direction, the size of the cropped volume, and the ray-casting transfer function parameters used in pre-processing.

Ultrasound-guided large-core needle biopsies of breast lesions: analysis of 962 cases to determine the number of samples for reliable tumour classification

The objective of this one-institutional study was to determine the number of large-core needle biopsies (LCNB), under three-dimensional ultrasound (3D-US) validation, that are sufficient to obtain a reliable histological diagnosis of a sonographically detectable breast lesion. Over an 28-month period, 962 sonographically guided LCNB were performed under 3D-US validation to assess 962 breast lesions. All biopsies were carried out with an automated core biopsy device fitted with 14-gauge (22 mm excursion) needles. Data of 962 biopsied breast lesions were gathered. Surgical follow-up was available for 659 lesions. Breast malignancies were diagnosed by ultrasound-guided LCNB with a sensitivity of 98.2% by performing three cores per lesion. In few cases, the open surgical specimen revealed the presence of invasive carcinomas in contrast to initial LNCB-based classification as ductal carcinomas in situ (DCIS, 11 lesions), lobular carcinoma in situ (one lesion), and atypical ductal hyperpasia (one lesion). Owing to disagreement between classification based on breast-imaging and histological findings, eight of these tumours were subsequently excised. Of the lesions that were removed at the patients’ requests despite benign LCNB diagnosis, two were infiltrating carcinoma and one a DCIS. We demonstrate that three 3D-US-guided percutaneous core specimens are sufficient to achieve tissue for a reliable histological assessment of sonographically detectable breast lesions and allow the detection of malignancies with high sensitivity and low rate of false-negative diagnoses.

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.

Evaluation of three-dimensional ultrasonography of the bovine mammary gland

OBJECTIVE

To evaluate 3-dimensional (3-D) ultrasonography of the bovine mammary gland, particularly of the teat.

ANIMALS

6 lactating cows.

PROCEDURES

Clinical and ultrasonographic examinations of mammary glands of each cow were performed. Teats were removed from a slaughtered cow and examined via ultrasonography. All scans were performed by use of a sensorless standard transducer (8.5 to 10 MHz linear array). The 2-dimensional data acquired were downloaded to an off-line system, and software was used to digitize each image and produce a 3-D block of digitized information. The selected anatomic area was displayed as a 3-D volume cube.

RESULTS

Good-quality, 3-D views of the entire mammary gland were acquired by obtaining sections through the glandular parenchyma, gland cistern, teat cistern, and teat canal.

CONCLUSIONS AND CLINICAL RELEVANCE

3-D ultrasonography allows perspective images of the mammary gland to be obtained. Many scanners routinely used in veterinary practice have the resolution required to produce satisfactory images, and the cost of refitting a standard ultrasonographic unit with 3-D software is affordable; however, the cost of a volume transducer with a positioning system and mechanical sweep strategy may be prohibitive. Three-dimensional ultrasonography is a new imaging technique that has promising applications in many fields of veterinary medicine.

Three-dimensional ultrasound-validated large-core needle biopsy: is it a reliable method for the histological assessment of breast lesions?

OBJECTIVE

The use of three-dimensional (3D) ultrasound may help to determine the exact position of the needle during breast biopsy, thereby reducing the number of core samples that are needed to achieve a reliable histological diagnosis. The aim of this study was to demonstrate the efficacy of 3D ultrasound-validated large-core needle biopsy (LCNB) of the breast.

METHODS

A total of 360 core needle biopsies was obtained from 169 breast lesions in 146 patients. Additional open breast biopsy was performed in 111 women (127/169 breast lesions); the remaining 42 lesions were followed up for at least 24 months. 3D ultrasound visualization of the needle in the postfiring position was used to classify the biopsy as central, marginal or outside the lesion. Based on this classification it was decided whether another sample had to be obtained.

RESULTS

A median of two core samples per lesion provided for all the lesions a sensitivity for malignancy of 96.9%, specificity of 100%, false-positive rate of 0% and false-negative rate of 3.1%, and for the excised lesions a sensitivity of 96.5%, specificity of 100%, false-positive rate of 0%, false-negative rate of 3.5% and an underestimation rate of 3.4%.

CONCLUSIONS

3D ultrasound validation of the postfiring needle position is an efficient adjunct to ultrasound-guided LCNB. The advantages of 3D ultrasound validation are likely to include a reduction in the number of core samples needed to achieve a reliable histological diagnosis (and a possible reduction in the risk of tumor cell displacement), reduced procedure time and lower costs.

Robot-assisted 3D-TRUS guided prostate brachytherapy: System integration and validation

Current transperineal prostate brachytherapy uses transrectal ultrasound (TRUS) guidance and a template at a fixed position to guide needles along parallel trajectories. However, pubic arch interference (PAI) with the implant path obstructs part of the prostate from being targeted by the brachytherapy needles along parallel trajectories. To solve the PAI problem, some investigators have explored other insertion trajectories than parallel, i.e., oblique. However, parallel trajectory constraints in current brachytherapy procedure do not allow oblique insertion. In this paper, we describe a robot-assisted, three-dimensional (3D) TRUS guided approach to solve this problem. Our prototype consists of a commercial robot, and a 3D TRUS imaging system including an ultrasound machine, image acquisition apparatus and 3D TRUS image reconstruction, and display software. In our approach, we use the robot as a movable needle guide, i.e., the robot positions the needle before insertion, but the physician inserts the needle into the patient's prostate. In a later phase of our work, we will include robot insertion. By unifying the robot, ultrasound transducer, and the 3D TRUS image coordinate systems, the position of the template hole can be accurately related to 3D TRUS image coordinate system, allowing accurate and consistent insertion of the needle via the template hole into the targeted position in the prostate. The unification of the various coordinate systems includes two steps, i.e., 3D image calibration and robot calibration. Our testing of the system showed that the needle placement accuracy of the robot system at the "patient's" skin position was 0.15 mm+/-0.06 mm, and the mean needle angulation error was 0.07 degrees. The fiducial localization error (FLE) in localizing the intersections of the nylon strings for image calibration was 0.13 mm, and the FLE in localizing the divots for robot calibration was 0.37 mm. The fiducial registration error for image calibration was 0.12 mm and 0.52 mm for robot calibration. The target registration error for image calibration was 0.23 mm, and 0.68 mm for robot calibration. Evaluation of the complete system showed that needles can be used to target positions in agar phantoms with a mean error of 0.79 mm+/-0.32 mm.

Characterization of spiculation on ultrasound lesions

Spiculation is a stellate distortion caused by the intrusion of breast cancer into surrounding tissue. Its existence is an important clue to characterizing malignant tumors. Many successful mammographic methods have been proposed to detect tumors with spiculation. Traditional two-dimensional (2-D) ultrasound cannot easily find spiculations because spiculations normally appear parallel to the surface of the skin. Recently, three-dimensional (3-D) ultrasound has been gradually used in clinical applications and it has been proven to be useful in determining the architectural distortion or spiculation that surrounds a breast tumor. This paper aims to identify spiculation from 3-D ultrasonic volume data of a tumor found by a physician. In the proposed method, each coronal slice of volume data is successively extracted and then analyzed as a 2-D ultrasound image by the proposed spiculation detection method. First, in each horizontal slice, the modified rotating structuring element (ROSE) operation is used to find the central region in which spiculation lines converge. Second, the stick algorithm is used to estimate the direction of the edge of each pixel around the central region. A pixel whose edge points toward the central region is marked as a potential spiculation. Finally, the marked pixels are collected around the central region and their distribution is analyzed to determine whether spiculation is present. The 3-D test datasets were obtained using the Voluson 530 or 730, Kretztechnik, Austria. First, the proposed method was tested on 104 2-D typical coronal images (selected by an experienced physician) extracted from 52 3-D ultrasonic datasets. Finally, 225 3-D pathologically proven datasets were tested to evaluate the performance. Spiculations are more easily observed in the coronal view than in the other two views. That is, the 3-D ultrasound is a powerful tool for identifying spiculations. Furthermore, 16% (19/120) of benign cases and 90% (94/105) of malignant cases are detected as spiculations.

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.

Breast cancer diagnosis using three-dimensional ultrasound and pixel relation analysis

Because ultrasound (US) imaging offers benefits compared with other medical imaging techniques, it is used routinely in nearly all hospitals and many clinics. However, the surface features and internal structure of a tumor are not easily demonstrated simultaneously using the traditional 2-D US. The newly developed three-dimensional (3-D) US can capture the morphology of a breast tumor and overcome the limitations of the traditional 2-D US. This study deals with pixel relation analysis techniques for use with 3-D breast US images and compares its performance to 2-D versions of the images. The 3-D US imaging was performed using a Voluson 530 scanner. The rectangular subimages of the volume-of-interest (VOI) were manually selected and the selected VOIs were outlined to include the entire extent of the tumor margin. The databases in this study included 54 malignant and 161 benign tumors. All solid nodules at US belong over C3 (probably benign) according to ACR BI-RADS category. All or some selected 2-D slices were used separately to calculate the diagnosis features for a 3-D US data set. We have proposed and compared several different methods to extract the characteristics of these consecutive 2-D images. As shown in our experiments, the diagnostic results were better than those of the conventional 2-D US. In the experiments, the area index Az under ROC curve of the proposed 3-D US method can achieve 0.9700 +/- 0.0118, but Az of the 2-D US is only 0.8461 +/- 0.0315. The p value of these two Az differences using z test is smaller than 0.01. Furthermore, we can find that the features from only several slices are enough to provide good diagnostic results if the adopted features are modified from the 2-D features.

Semiautomatic three-dimensional segmentation of the prostate using two-dimensional ultrasound images

In this paper, we report on two methods for semiautomatic three-dimensional (3-D) prostate boundary segmentation using 2-D ultrasound images. For each method, a 3-D ultrasound prostate image was sliced into the series of contiguous 2-D images, either in a parallel manner, with a uniform slice spacing of 1 mm, or in a rotational manner, about an axis approximately through the center of the prostate, with a uniform angular spacing of 5 degrees. The segmentation process was initiated by manually placing four points on the boundary of a selected slice, from which an initial prostate boundary was determined. This initial boundary was refined using the Discrete Dynamic Contour until it fit the actual prostate boundary. The remaining slices were then segmented by iteratively propagating this result to an adjacent slice and repeating the refinement, pausing the process when necessary to manually edit the boundary. The two methods were tested with six 3-D prostate images. The results showed that the parallel and rotational methods had mean editing rates of 20% and 14%, and mean (mean absolute) volume errors of -5.4% (6.5%) and -1.7% (3.1%), respectively. Based on these results, as well as the relative difficulty in editing, we conclude that the rotational segmentation method is superior.

Automatic needle segmentation in three-dimensional ultrasound images using two orthogonal two-dimensional image projections

In this paper, we describe an algorithm to segment a needle from a three-dimensional (3D) ultrasound image by using two orthogonal two-dimensional (2D) image projections. Not only is the needle more conspicuous in a projected (volume-rendered) image, but its direction in 3D lies in the plane defined by the projection direction and the needle direction in the projected 2D image. Hence, using two such projections, the 3D vector describing the needle direction lies along the intersection of the two corresponding planes. Thus, the task of 3D needle segmentation is reduced to two 2D needle segmentations. For improved accuracy and robustness, we use orthogonal projection directions (both orthogonal to a given a priori estimate of the needle direction), and use volume cropping and Gaussian transfer functions to remove complex background from the 2D projection images. To evaluate our algorithm, we tested it with 3D ultrasound images of agar and turkey breast phantoms. Using a 500 MHz personal computer equipped with a commercial volume-rendering card, we found that our 3D needle segmentation algorithm performed in near real time (about 10 fps) with a root-mean-square accuracy in needle length and endpoint coordinates of better than 0.8 mm, and about 0.5 mm on average, for needles lengths in the 3D image from 4.0 mm to 36.7 mm.

Value of four-dimensional ultrasonography in ultrasonographically guided biopsy of hepatic masses

OBJECTIVE

To assess the value of four-dimensional ultrasonography (dynamic three-dimensional ultrasonography with the added dimension of time) in ultrasonographically guided biopsy procedures of focal hepatic masses.

METHODS

Four-dimensional ultrasonographically guided biopsy experiments using a freehand technique were performed in phantoms that simulated human liver tissue and had target material. After the protocol was determined and Institutional Review Board approval was obtained, 12 patients underwent four-dimensional ultrasonographically guided biopsy of focal hepatic masses by informed consent. Planar images using 3 orthogonal planes plus a volume-rendered image were used for real-time guidance during the biopsy procedure.

RESULTS

Four-dimensional ultrasonography improved visualization of biopsy devices in all 12 patients (100%) regardless of minor changes in transducer position during the biopsy procedures. Four-dimensional ultrasonography allowed more intuitive apprehension of the spatial relationship of the needle and the target lesion and thus helped in adjusting the needle to an optimal prefiring position in 8 patients (67%). With regard to procedure time, four-dimensional ultrasonographically guided biopsy was comparable with standard two-dimensional ultrasonographically guided techniques.

CONCLUSIONS

Compared with standard two-dimensional ultrasonographically guided biopsy, four-dimensional ultrasonography provides improved visualization of biopsy devices and more perceptible information on the spatial relationship between the biopsy needle and the target lesion.

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.

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

RATIONALE AND OBJECTIVES

No single method is generally accepted for evaluating the accuracy of breast biopsy techniques before their clinical implementation. The purpose of this study was to test a new process for evaluating biopsy techniques by using it in the evaluation of a prototype three-dimensional ultrasound (US)-guided biopsy device.

MATERIALS AND METHODS

The biopsy accuracy of a new three-dimensional US-guided breast biopsy device was compared to that of the accepted clinical practice of biopsy by expert radiologists with two-dimensional freehand US guidance. Biopsies were performed in chicken tissue phantoms containing 3.2-mm lesions made of poly(vinyl alcohol) cryogel. The criterion for a successful biopsy was the presence of lesion in the sample. The equivalence limit difference tested was 10% by using a power of 90% and a two-sided test significance level, a, of 10%.

RESULTS

The biopsy success rate of the three-dimensional US-guided system (96%) was equivalent to that of expert radiologists using two-dimensional freehand US guidance (94.5%) in tissue phantoms containing poly(vinyl alcohol) cryogel lesions.

CONCLUSION

This evaluation procedure is a valuable precursor to clinical trials in the assessment of biopsy techniques. The three-dimensional US-guided breast biopsy system provides a suitable alternative to two-dimensional freehand US guidance for biopsy of breast cancer.