Targeting difficult accessible breast lesions: MRI-guided needle localization using a freehand technique in a 3.0T closed bore magnet

A 20-gauge active needle design with thin-film printed circuitry for interventional MRI at 0.55T

PURPOSE

This work aims to fabricate RF antenna components on metallic needle surfaces using biocompatible polyester tubing and conductive ink to develop an active interventional MRI needle for clinical use at 0.55 Tesla.

METHODS

A custom computer numeric control-based conductive ink printing method was developed. Based on electromagnetic simulation results, thin-film RF antennas were printed with conductive ink and used to fabricate a medical grade, 20-gauge (0.87 mm outer diameter), 90-mm long active interventional MRI needle. The MRI visibility performance of the active needle prototype was tested in vitro in 1 gel phantom and in vivo in 1 swine. A nearly identical active needle constructed using a 44 American Wire Gauge insulated copper wire-wound RF receiver antenna was a comparator. The RF-induced heating risk was evaluated in a gel phantom per American Society for Testing and Materials (ASTM) 2182-19.

RESULTS

The active needle prototype with printed RF antenna was clearly visible both in vitro and in vivo under MRI. The maximum RF-induced temperature rise of prototypes with printed RF antenna and insulated copper wire antenna after a 3.96 W/kg, 15 min. long scan were 1.64°C and 8.21°C, respectively. The increase in needle diameter was 98 µm and 264 µm for prototypes with printed RF antenna and copper wire-wound antenna, respectively.

CONCLUSION

The active needle prototype with conductive ink printed antenna provides distinct device visibility under MRI. Variations on the needle surface are mitigated compared to use of a 44 American Wire Gauge copper wire. RF-induced heating tests support device RF safety under MRI. The proposed method enables fabrication of small diameter active interventional MRI devices having complex geometries, something previously difficult using conventional methods.

Recent Progress for the Techniques of MRI-Guided Breast Interventions and their applications on Surgical Strategy

With a high sensitivity of breast lesions, MRI can detect suspicious lesions which are occult in traditional breast examination equipment. However, the lower and variable specificity of MRI makes the MRI-guided intervention, including biopsies and localizations, necessary before surgery, especially for patients who need the treatment of breast-conserving surgery (BCS). MRI techniques and patient preparation should be first carefully considered before the intervention to avoid lengthening the procedure time and compromising targeting accuracy. Doctors and radiologists need to reconfirm the target of the lesion and be very familiar with the process approach and equipment techniques involving the computer-aided diagnosis (CAD) tools and the biopsy system and follow a correct way. The basic steps of MRI-guided biopsy and localization are nearly the same regardless of the vendor or platform, and this article systematically introduces detailed methods and techniques of MRI-guided intervention. The two interventions both face different challenging situations during procedures with solutions given in the article. Post-operative statistics show that the complications of MRI-guided intervention are infrequent and mild, and MRI-guided biopsy provides the pathological information for the subsequent surgical decisions and MRI-guided localization fully prepared for follow-up surgical biopsy. New techniques for MRI-guided intervention are also elaborated in the article, which leads to future development. In a word, MRI-guided intervention is a safe, accurate, and effective technique with a low complication rate and successful MRI-guided intervention is truly teamwork with efforts from patients to surgeons, radiologists, MRI technologists, and nurses.

Impact of clinical and lesion characteristics on the results of MR-guided wire localizations of the breast using an open 1.0-T MRI system

PURPOSE

Preoperative magnetic resonance (MR)-guided wire localizations are warranted in patients with suspicious focal breast lesions on MR mammographic findings without equivalent in x-ray mammography and ultrasonography. The study was performed to assess the impact of clinical parameters, tumor size, and target localization on the procedural characteristics in magnetic resonance imaging (MRI)-guided wire localizations of breast lesions using an open 1.0-T open MR system.

MATERIAL AND METHODS

The clinical, radiological, and histological characteristics of all 347 patients and all 394 interventional procedures performed in a 6-year interval were extracted from the clinical files. Two board-certified senior radiologists evaluated the impact of target localization and the size on the interventional results in the available 302 image data sets. Patient characteristics, lesion characteristics, and interventional results were statistically correlated in subgroup analyses.

RESULTS

A total of 387 of the 394 MR-guided wire localizations (98.2%) were technically successful. In 7 cases (2.3%), the intervention was aborted because the suspicious finding of the diagnostic MR mammography could not be visualized during the intervention. Minor complications occurred in 13 interventions (3.3%). The histological workup of the operative specimen showed benign results in 226 of the 394 interventions (57.4%) and malignant findings in 154 wire localizations (39.1%). The mean (SD) length of the interventional procedure time defined as the time interval between the start of the first and of the last MRI sequence as documented in the electronic MRI data sets was 24.6 (8.4) minutes. Patient age, medical history, and the anticipated risk for developing breast cancer and a simultaneous known carcinoma did not affect the technical success and complication rates and the interventional procedure time. A total of 60 targets (19.5%) were located in the retromamillary zone, 89 targets (28.9%) in the peripheral zone, and 1 target (0.3%) near the chest wall. The maximum diameter was 1 to 5 mm in 64 lesions (21.2%), 6 to 10 mm in 136 lesions (45.0%), 11 to 15 mm in 56 lesions (18.6%), and 16 mm or greater in 46 lesions (15.2%). A total of 23 of the 100 histologically proven invasive carcinomas had a maximum MRI diameter of 1 to 5 mm (23.0%) and 38 (38.0%) of 6 to 10 mm.

CONCLUSIONS

Magnetic resonance-guided wire localizations of suspicious breast lesions using an open high-field MR system are a clinically safe and feasible method even in small target lesions and anatomical regions that are usually considered difficult to access.

Magnetic resonance imaging-radioguided occult lesion localization (ROLL) in breast cancer using Tc-99m macro-aggregated albumin and distilled water control

Background

Magnetic resonance imaging (MRI) guided wire localization presents several challenges apart from the technical difficulties. An alternative to this conventional localization method using a wire is the radio-guided occult lesion localization (ROLL), more related to safe surgical margins and reductions in excision volume. The purpose of this study was to establish a safe and reliable magnetic resonance imaging-radioguided occult lesion localization (MRI-ROLL) technique and to report our initial experience with the localization of nonpalpable breast lesions only observed on MRI.

Methods

Sixteen women (mean age 53.2 years) with 17 occult breast lesions underwent radio-guided localization in a 1.5-T MR system using a grid-localizing system. All patients had a diagnostic MRI performed prior to the procedure. An intralesional injection of Technetium-99m macro-aggregated albumin followed by distilled water was performed. After the procedure, scintigraphy was obtained. Surgical resection was performed with the help of a gamma detector probe. The lesion histopathology and imaging concordance; the procedure’s positive predictive value (PPV), duration time, complications, and accuracy; and the rate of exactly excised lesions evaluated with MRI six months after the surgery were assessed.

Results

One lesion in one patient had to be excluded because the radioactive substance came back after the injection, requiring a wire placement. Of the remaining cases, there were four malignant lesions, nine benign lesions, and three high-risk lesions. Surgical histopathology and imaging findings were considered concordant in all benign and high-risk cases. The PPV of MRI-ROLL was greater if the indication for the initial MR examination was active breast cancer. The median procedure duration time was 26 minutes, and all included procedures were defined as accurate. The exact and complete lesion removal was confirmed in all (100%) patients who underwent six-month postoperative MRI (50%).

Conclusions

MRI-ROLL offers a precise, technically feasible, safe, and rapid means for performing preoperative MRI localizations in the breast.

MRI-guided intervention for breast lesions using the freehand technique in a 3.0-T closed-bore MRI scanner: feasibility and initial results

Objective

To report the feasibility of magnetic resonance imaging (MRI)-guided intervention for diagnosing suspicious breast lesions detectable by MRI only, using the freehand technique with a 3.0-T closed-bore MRI scanner.

Materials and Methods

Five women with 5 consecutive MRI-only breast lesions underwent MRI-guided intervention: 3 underwent MRI-guided needle localization and 2, MRI-guided vacuum-assisted biopsy. The interventions were performed in a 3.0-T closed-bore MRI system using a dedicated phased-array breast coil with the patients in the prone position; the freehand technique was used. Technical success and histopathologic outcome were analyzed.

Results

MRI showed that four lesions were masses (mean size, 11.5 mm; range, 7-18 mm); and 1, a nonmass-like enhancement (maximum diameter, 21 mm). The locations of the lesions with respect to the breast with index cancer were as follows: different quadrant, same breast - 3 cases; same quadrant, same breast - 1 case; and contralateral breast - 1 case. Histopathologic evaluation of the lesions treated with needle localization disclosed perilobular hemangioma, fibrocystic change, and fibroadenomatous change. The lesions treated with vacuum-assisted biopsy demonstrated a radial scar and atypical apocrine hyperplasia. Follow-up MRI after 2-7 months (mean, 4.6 months) confirmed complete lesion removal in all cases.

Conclusion

MRI-guided intervention for breast lesions using the freehand technique with a 3.0-T closed-bore MRI scanner is feasible and accurate for diagnosing MRI-only lesions.

Excite and receive solenoid radiofrequency coil for MRI-guided breast interventions

A radiofrequency coil based on a solenoid design was developed and integrated with a novel device for MR-guided breast interventions using a circumferential approach. The transmit/receive tapered solenoid design conforms to the shape of the pendent breast, and provides open circumferential needle access to breast tissue under rotational symmetry. Phantom and in vivo studies using a healthy volunteer demonstrated a superior uniformity using the tapered solenoid coil compared with a commercial 8-channel diagnostic imaging coil. The solenoid coil design has important advantages due to localized transmit/receive such as B(1) -homogeneity and reduced specific absorption ratio (SAR) especially at high-field strengths. Because it provides open access and a rotationally symmetric local field, the tapered solenoid design can easily be adapted for bilateral imaging and 3D MR-guided breast interventions.

Freehand MRI-guided preoperative needle localization of breast lesions after MRI-guided vacuum-assisted core needle biopsy without marker placement

PURPOSE

To evaluate the feasibility of magnetic resonance imaging (MRI)-guided preoperative needle localization (PNL) of breast lesions previously sampled by MRI-guided vacuum-assisted core needle biopsy (VACNB) without marker placement.

MATERIALS AND METHODS

We reviewed 15 women with 16 breast lesions undergoing MRI-guided VACNB without marker placement who subsequently underwent MRI-guided PNL, both on an open 0.5T magnet using freehand techniques. Mammograms and specimen radiographs were rated for lesion visibility; MRI images were rated for lesion visibility and hematoma formation. Imaging findings were correlated with pathology.

RESULTS

The average prebiopsy lesion size was 16 mm (range 4-50 mm) with 13/16 lesions located in mammographically dense breasts. Eight hematomas formed during VACNB (average size 13 mm, range 8-19 mm). PNL was performed for VACNB pathologies of cancer (5), high-risk lesions (5), or benign but discordant findings (6) at 2-78 days following VACNB. PNL targeted the lesion (2), hematoma (4), or surrounding breast architecture (10). Wire placement was successful in all 16 lesions. Final pathology showed six cancers, five high-risk lesions, and five benign findings.

CONCLUSION

MRI-guided PNL is successful in removing lesions that have previously undergone VACNB without marker placement by targeting the residual lesion, hematoma, or surrounding breast architecture, even in mammographically dense breasts.

A novel MR-guided interventional device for 3D circumferential access to breast tissue

MRI is rapidly growing as a tool for image-guided procedures in the breast such as needle localizations, biopsy, and cryotherapy. The ability of MRI to resolve small (<1 cm) lesions allows earlier detection and diagnosis than with ultrasound. Most MR-guidance methods perform a two-dimensional compression of the breast that distorts tissue anatomy and limits medial access. This work presents a system for localizing breast lesions with 360 degrees access to breast tissue. A novel system has been developed to perform breast lesion localization using MR guidance that uses a 3D radial coordinate system with four degrees of freedom. The device is combined with a novel breast RF coil for improved signal to noise and rotates 360 degrees around the breast to allow medial, lateral, superior, and inferior access minimizing insertion depth to the target. Coil performance was evaluated using a human volunteer by comparing signal to noise from both the developed breast RF coil and a commercial seven-channel breast coil. The system was tested with a breast-shaped gel phantom containing randomly distributed MR-visible targets. MR-compatible localization needles were used to demonstrate the accuracy and feasibility of the concept for breast biopsy. Localization results were classified based on the relationship between the final needle tip position and the lesion. A 3D bladder concept was also tested using animal tissue to evaluate the device's ability to immobilize deformable breast tissue during a needle insertion. The RF breast coil provided signal to noise values comparable to a seven-channel breast coil. The needle tip was in contact with the targeted lesion in 89% (25/28) of all the trials and 100% (6/6) of the trials with targeted lesions >6 mm. Target lesions were 3-4 mm in diameter for 47% (13/28), 5-6 mm in diameter for 32% (9/28), and over 6 mm in diameter for 21% (6/28) of the trials, respectively. The 3D bladder concept was shown to immobilize a deformable animal tissue phantom during needle insertion. It is concluded that the MR-guidance system accurately localizes small targets on the order of 3-4 mm in a breast phantom with 360 degrees rotational access.

Magnetic resonance imaging--guided breast interventions

The use of breast magnetic resonance imaging (MRI) for screening, diagnosis, staging, and management of breast cancer is rapidly increasing. MRI is highly sensitive for the detection of benign and malignant abnormalities that are occult to physical examination, ultrasound, and mammography. However, the specificity of MRI is moderate. These attributes necessitate methods for MR-guided tissue sampling to determine the histology of MRI detected lesions. This article will review appropriate peer-reviewed data and currently accepted methods for MR-guided tissue sampling. A detailed step-by-step technique for vacuum-assisted MR-guided breast biopsy is included. We also review emerging data for percutaneous and transcutaneous MR-guided breast interventions such as tissue ablation for benign and malignant disease.