Supine breast MRI using a wearable coil facilitates the translation of MR imaging findings to clinical practice

PURPOSE

The aim of this study is the evaluation of a wearable radiofrequency coil vest (BraCoil) for supine breast MRI, comparing lesion displacement and size with standard prone MRI and supine ultrasound, and assessing its potential impact on clinical workflows for targeted ultrasound and ultrasound-guided biopsy.

MATERIAL AND METHODS

MRI and ultrasound data were collected from 11 female patients with 18 breast lesions. Patients underwent two MRI exams: standard prone MRI using a commercial coil and supine MRI using the BraCoil. Lesion positions were compared between prone MRI, supine MRI, and supine ultrasound using anatomical landmarks (skin, pectoral muscle, nipple). Statistical analysis was performed on the mean absolute differences in lesion positions.

RESULTS

With ultrasound lesion positions as a reference, supine MRI acquired with the BraCoil showed significantly less lesion displacement compared to prone MRI, with on average 7.3 mm less lesion-skin (p = 0.004) and 26.7 mm less lesion-pectoral muscle (p = 0.0001) displacement. Lesion-nipple distances in supine MRI showed strong deviations compared to prone MRI (p < 0.004). Lesion size in supine MRI was more comparable to ultrasound than prone MRI (p = 0.03) but changed insignificantly across modalities. 4 out of 18 lesions were only detectable in targeted ultrasound after supine BraCoil MRI.

CONCLUSIONS

Supine MRI with the BraCoil offers a significant advantage over prone MRI by providing more accurate lesion positioning relative to ultrasound. This approach could improve lesion localization in radiotherapy planning, surgery, targeted ultrasound, and ultrasound-guided biopsy, potentially reducing the need for MR-guided biopsies.

Evaluation of the intramammary distribution of breast lesions detected by MRI but not conventional second-look B-mode ultrasound using an MRI/ultrasound fusion technique

The objective of this study was to evaluate the intramammary distribution of MRI-detected mass and focus lesions that were difficult to identify with conventional B-mode ultrasound (US) alone. Consecutive patients with lesions detected with MRI but not second-look conventional B-mode US were enrolled between May 2015 and June 2023. Following an additional supine MRI examination, we performed third-look US using real-time virtual sonography (RVS), an MRI/US image fusion technique. We divided the distribution of MRI-detected mammary gland lesions as follows: center of the mammary gland versus other (superficial fascia, deep fascia, and atrophic mammary gland). We were able to detect 27 (84%) of 32 MRI-detected lesions using third-look US with RVS. Of these 27 lesions, 5 (19%) were in the center of the mammary gland and 22 (81%) were located in other areas. We were able to biopsy all 27 lesions; 8 (30%) were malignant and 19 (70%) were benign. Histopathologically, three malignant lesions were invasive ductal carcinoma (IDC; luminal A), one was IDC (luminal B), and four were ductal carcinoma in situ (low-grade). Malignant lesions were found in all areas. During this study period, 132 MRI-detected lesions were identified and 43 (33%) were located in the center of the mammary gland and 87 (64%) were in other areas. Also, we were able to detect 105 of 137 MRI-detected lesions by second-look conventional-B mode US and 38 (36%) were located in the center of the mammary gland and 67 (64%) were in other areas. In this study, 81% of the lesions identified using third-look US with RVS and 64% lesions detected by second-look conventional-B mode US were located outside the center of the mammary gland. We consider that adequate attention should be paid to the whole mammary gland when we perform third-look US using MRI/US fusion technique.

Recent Advances in Ultrasound Breast Imaging: From Industry to Clinical Practice

Breast ultrasound (US) has undergone dramatic technological improvement through recent decades, moving from a low spatial resolution, grayscale-limited technique to a highly performing, multiparametric modality. In this review, we first focus on the spectrum of technical tools that have become commercially available, including new microvasculature imaging modalities, high-frequency transducers, extended field-of-view scanning, elastography, contrast-enhanced US, MicroPure, 3D US, automated US, S-Detect, nomograms, images fusion, and virtual navigation. In the subsequent section, we discuss the broadened current application of US in breast clinical scenarios, distinguishing among primary US, complementary US, and second-look US. Finally, we mention the still ongoing limitations and the challenging aspects of breast US.

Prospective Evaluation of Ultrasound in a Novel Position with MRI Virtual Navigation for MRI-Detected Only Breast Lesions: A Pilot Study of a More Efficient and Economical Method

The aim of this study was to evaluate the clinical utility of ultrasound (US) with magnetic resonance imaging (MRI) virtual navigation in a novel prone position for MRI-detected incidental breast lesions. Between June 2016 and June 2020, 30 consecutive patients with 33 additional Breast Imaging Reporting and Data System (BI-RADS) category 4 or 5 lesions that were detected on MRI but occult on second-look US were enrolled in the study. All suspicious lesions were located in real-time US using MRI virtual navigation in the prone position and then followed by US-guided biopsy or surgical excision. Pathological results were taken as the standard of reference. The detection rate of US with MRI virtual navigation was calculated. The MRI features and pathological types of these lesions were analyzed. A total of 31 lesions were successfully located with real-time US with MRI virtual navigation and then US-guided biopsy or localization, and the detection rate was 93.9% (31/33). Twenty-seven (87.1%, 27/31) proved to be benign lesions and four (12.9%, 4/31) were malignant lesions at pathology. Of the 33 MRI-detected lesions, 31 (93.9%, 31/33) were non-mass enhancements and two (6.1%, 2/33) were masses. This study showed that real-time US with prone MRI virtual navigation is a novel efficient and economical method to improve the detection and US-guided biopsy rate of breast lesions that are detected solely on MRI.

Laparoscopic Liver Surgery Guided by Virtual Real-time CT-Guided Volume Navigation

BACKGROUND

Recently, virtual navigation system has been applied to hepatic surgery, enabling better visualization of intrahepatic vascular branches and location of tumor. Intraoperative ultrasonography (IOUS) is the most common form of image guidance during liver surgery. However, during laparoscopic hepatectomies (LH), IOUS has several limitations and its reliability has been poorly evaluated. The objective of this work is to evaluate VRCT (virtual real-time CT-guided volume navigation) during LH. This system aims to provide accurate anatomical orientation for surgeons enhancing the safety of LH.

METHODS

Twenty-seven hepatic neoplasms were resected laparoscopically at our institution under reference guidance of VRCT. During operation, electromagnetic tracking of the surgical instrument was used for navigating the direction of accurate liver transection.

RESULTS

Twenty-six (96.3%) of the 27 lesions (mean diameter 11 mm) were successfully performed under VRCT guidance. Average registration time was < 2 min. Average setup time was approximately 7 min per procedure. VRCT allows the surgeon to navigate liver transection with acceptable accuracy. The mean error was 12 mm. All surgical margins were negative and the mean histologic resection margin was 9 mm.

CONCLUSIONS

VRCT-guided LH is feasible and provides valuable real-time anatomical feedback during hepatic resections. Advancement of such systems to improve accuracy might greatly compensate for the limitation of laparoscopic IOUS.

Feasibility, Image Quality and Clinical Evaluation of Contrast-Enhanced Breast MRI Performed in a Supine Position Compared to the Standard Prone Position

Background: To assess the feasibility, image quality and diagnostic value of contrast-enhanced breast magnetic resonance imaging (MRI) performed in a supine compared to a prone position. Methods: One hundred and fifty-one patients who had undergone a breast MRI in both the standard prone and supine position were evaluated retrospectively. Two 1.5 T MR scanners were used with the same image resolution, sequences and contrast medium in all examinations. The image quality and the number and dimensions of lesions were assessed by two expert radiologists in an independent and randomized fashion. Two different classification systems were used. Histopathology was the standard of reference. Results: Two hundred and forty MRIs from 120 patients were compared. The analysis revealed 134 MRIs with monofocal (U), 68 with multifocal (M) and 38 with multicentric (C) lesions. There was no difference between the image quality and number of lesions in the prone and supine examinations. A significant difference in the lesion extension was observed between the prone and supine position. No significant differences emerged in the classification of the lesions detected in the prone compared to the supine position. Conclusions: It is possible to perform breast MRI in a supine position with the same image quality, resolution and diagnostic value as in a prone position. In the prone position, the lesion dimensions are overestimated with a higher wash-in peak than in the supine position.

Deformable Mapping Method to Relate Lesions in Dedicated Breast CT Images to Those in Automated Breast Ultrasound and Digital Breast Tomosynthesis Images

This work demonstrates the potential for using a deformable mapping method to register lesions between dedicated breast computed tomography (bCT) and both automated breast ultrasound (ABUS) and digital breast tomosynthesis (DBT) images (craniocaudal [CC] and mediolateral oblique [MLO] views). Two multi-modality breast phantoms with external fiducial markers attached were imaged by the three modalities. The DBT MLO view was excluded for the second phantom. The automated deformable mapping algorithm uses biomechanical modeling to determine corresponding lesions based on distances between their centers of mass (d_COM) in the deformed bCT model and the reference model (DBT or ABUS). For bCT to ABUS, the mean d_COM was 5.2 ± 2.6 mm. For bCT to DBT (CC), the mean d_COM was 5.1 ± 2.4 mm. For bCT to DBT (MLO), the mean d_COM was 4.7 ± 2.5 mm. This application could help improve a radiologist's efficiency and accuracy in breast lesion characterization, using multiple imaging modalities.

Feasibility of supine MRI (Magnetic Resonance Imaging)-navigated ultrasound in breast cancer patients

OBJECTIVE

The purpose of this study was to evaluate the feasibility of image fusion between US and supine MRI in breast cancer patients, and to evaluate differences in tumor location between prone and supine positions.

METHODS

This prospective study included 88 patients who underwent an additional supine MRI (MRsup) sequence following routine prone MRI (MRpro) for breast cancer between May 2016 and December 2017. The location of the tumor and discrepancies in the distances from nipple to lesion (NLD), skin to lesion (SLD), and chest wall to lesion (CLD) were evaluated between MRpro and MRsup (MRpro-sup), MRpro and MRsup-navigated US (MRpro-USnav), and MRsup and USnav (MRsup-USnav). Associations between breast thickness and measurement discrepancies were analyzed.

RESULTS

Total 91 index lesions were evaluated. The intraclass correlation coefficients (ICCs) for the location of MRpro and MRsup compared with USnav were 0.994 (range: 0.990-0.996) and 0.998 (range: 0.996-0.999), respectively. The mean MRpro-sup and MRpro-USnav measurement discrepancies were greater than those of MRsup-USnav, significantly. Most outer locations showed greater mean measurement discrepancies than inner locations, and each NLD, SLD, and CLD mean measurement discrepancy showed different tendencies according to location (upper or lower) and lesion depth (superficial, middle, or deep). High breast thickness showed significantly greater mean measurement discrepancies than low breast thickness.

CONCLUSION

Image fusion between US and supine MRI is feasible in breast cancer patients, although there is a considerable difference in tumor location measurements between prone and supine positions, especially with thicker breasts.

MRI-detected breast lesions: clinical implications and evaluation based on MRI/ultrasonography fusion technology

Magnetic resonance imaging (MRI) is a highly sensitive imaging modality that frequently reveals additional breast lesions that are occult on mammography and ultrasonography (US) and are thus difficult to diagnose. It is important to investigate these MRI-detected suspicious lesions, which are associated with a fairly high rate of malignancy. In this review, we have discussed MRI/US fusion technology, a magnetic position tracking system that synchronizes real-time US and MRI to improve lesion detection and enables comparisons of MRI and US findings of the detected lesions. This combination increases the precision of second-look US. We hope that our review underscores the importance of understanding the US findings and histopathology of MRI-detected breast lesions, as this will enable radiologists to perform appropriate assessments.

Position-based modeling of lesion displacement in ultrasound-guided breast biopsy

PURPOSE

Although ultrasound (US) images represent the most popular modality for guiding breast biopsy, malignant regions are often missed by sonography, thus preventing accurate lesion localization which is essential for a successful procedure. Biomechanical models can support the localization of suspicious areas identified on a preoperative image during US scanning since they are able to account for anatomical deformations resulting from US probe pressure. We propose a deformation model which relies on position-based dynamics (PBD) approach to predict the displacement of internal targets induced by probe interaction during US acquisition.

METHODS

The PBD implementation available in NVIDIA FleX is exploited to create an anatomical model capable of deforming online. Simulation parameters are initialized on a calibration phantom under different levels of probe-induced deformations; then, they are fine-tuned by minimizing the localization error of a US-visible landmark of a realistic breast phantom. The updated model is used to estimate the displacement of other internal lesions due to probe-tissue interaction.

RESULTS

The localization error obtained when applying the PBD model remains below 11 mm for all the tumors even for input displacements in the order of 30 mm. This proposed method obtains results aligned with FE models with faster computational performance, suitable for real-time applications. In addition, it outperforms rigid model used to track lesion position in US-guided breast biopsies, at least halving the localization error for all the displacement ranges considered.

CONCLUSION

Position-based dynamics approach has proved to be successful in modeling breast tissue deformations during US acquisition. Its stability, accuracy and real-time performance make such model suitable for tracking lesions displacement during US-guided breast biopsy.

Supplementary abbreviated supine breast MRI following a standard prone breast MRI with single contrast administration: is it effective in detecting the initial contrast-enhancing lesions?

PURPOSE

We aimed to evaluate the detectability of contrast enhancing lesions, initially demonstrated in standard prone dynamic contrast-enhanced MRI (DCE-MRI), in a supplementary supine breast MRI examination performed following the standard prone DCE-MRI examination and to show the correlation of spatial displacement of the lesions with breast size and density.

METHODS

Forty-two patients with 45 lesions were prospectively evaluated. Supine breast MRI was acquired with a 6-channel body coil following a standard DCE-MRI in prone position after repositioning the patient. No additional contrast media was administered. Images were evaluated by two radiologists in consensus for the visibility of the lesions. Lesion localization relative to the sternal midline, chest wall and nipple was measured in both prone and supine positions. Correlations between lesion displacement and breast size or breast density were analyzed.

RESULTS

Of 45 lesions, 23 (52.3%) were masses, 22 (47.7%) were nonmass enhancements (NME). Forty-four lesions (97.8%) could be detected on supine images. One linear NME of 33 mm in length could not be seen on supine images. Twenty (46.5%) of the detected lesions in supine position were equal to or smaller than 10 mm (11 NME [55%] and 9 masses [45%]). Lesion displacement relative to the chest wall increased with increasing breast size (P < 0.001).

CONCLUSION

An abbreviated supine sequence following a standard prone DCE-MRI with single contrast media administration is an effective method for defining the lesion location in supine position.

Efficacy of Second-Look Ultrasound with MR Coregistration for Evaluating Additional Enhancing Lesions of the Breast: Review of the Literature

Contrast enhanced magnetic resonance imaging (CE-MRI) has acquired a central role in the field of diagnosis and evaluation of breast cancer due to its high sensitivity; on the other hand, MRI has shown a variable specificity because of the wide overlap between the imaging features of benign and malignant lesions. Therefore, when an additional breast lesion is identified at CE-MRI, a second look with targeted US is generally performed because it provides additional information to further characterise the target lesion and makes it possible to perform US-guided biopsies which are costless and more comfortable for patients compared with MRI-guided ones. Nevertheless, there is not always a correspondence between CE-MR findings and targeted US due to several factors including different operator's experience and position of patients. A new technique has recently been developed in order to overcome these limitations: US with MR coregistration, which can synchronise a sonography image and the MR image with multiplanar reconstruction (MPR) of the same section in real time. The aim of our study is to review the literature concerning the second look performed with this emerging and promising technique, showing both advantages and limitations in comparison with conventional targeted US.

Deformable mapping technique to correlate lesions in digital breast tomosynthesis and automated breast ultrasound images

PURPOSE

To develop a deformable mapping technique to match corresponding lesions between digital breast tomosynthesis (DBT) and automated breast ultrasound (ABUS) images.

METHODS

External fiducial markers were attached to the surface of two CIRS multi-modality compressible breast phantoms (A and B) containing multiple simulated lesions. Both phantoms were imaged with DBT (upright positioning with cranial-caudal compression) and ABUS (supine positioning with anterior-to-chest wall compression). The lesions and markers were manually segmented by three different readers. Reader segmentation similarity and reader reproducibility were assessed using Dice similarity coefficients (DSC) and distances between centers of mass (d_COM ). For deformable mapping between the modalities each reader's segmented dataset was processed with an automated deformable mapping algorithm as follows: First, Morfeus, a finite element (FE) based multi-organ deformable image registration platform, converted segmentations into triangular surface meshes. Second, Altair HyperMesh, a FE pre-processor, created base FE models for the ABUS and DBT data sets. All deformation is performed on the DBT image data; the ABUS image sets remain fixed throughout the process. Deformation was performed on the external skin contour (DBT image set) to match the external skin contour on the ABUS set, and the locations of the external markers were used to morph the skin contours to be within a user-defined distance. Third, the base DBT-FE model was deformed with the FE analysis solver, Optistruct. Deformed DBT lesions were correlated with matching lesions in the base ABUS FE model. Performance (lesion correlation) was assessed with d_COM for all corresponding lesions and lesion overlap. Analysis was performed to determine the minimum number of external fiducial markers needed to create the desired correlation and the improvement of correlation with the use of external markers.

RESULTS

Average DSC for reader similarity ranged from 0.88 to 0.91 (ABUS) and 0.57 to 0.83 (DBT). Corresponding d_COM ranged from 0.20 to 0.36 mm (ABUS) and 0.11 to 1.16 mm (DBT). Lesion correlation is maximized when all corresponding markers are within a maximum distance of 5 mm. For deformable mapping of phantom A, without the use of external markers, only two of six correlated lesions showed overlap with an average lesion d_COM of 6.8 ± 2.8 mm. With use of three external fiducial markers, five of six lesions overlapped and average d_COM improved to 4.9 ± 2.4 mm. For deformable mapping of Phantom B without external markers analysis, four lesions were correlated of seven with overlap between only one of seven lesions, and an average lesion d_COM of 9.7 ± 3.5 mm. With three external markers, all seven possible lesions were correlated with overlap between four of seven lesions. The average d_COM was 8.5 ± 4.0 mm.

CONCLUSION

This work demonstrates the potential for a deformable mapping technique to relate corresponding lesions in DBT and ABUS images by showing improved lesion correspondence and reduced lesion registration errors with the use of external fiducial markers. The technique should improve radiologists' characterization of breast lesions which can reduce patient callbacks, misdiagnoses and unnecessary biopsies.

Three-Dimensional Surface Point Cloud Ultrasound for Better Understanding and Transmission of Ultrasound Scan Information

Ultrasound is notoriously plagued by high user dependence. There is a steep drop-off in information in going from what the sonographer sees during image acquisition and what the interpreting radiologist is able to view at the reading station. One countermeasure is probe localization and tracking. Current implementations are too difficult and expensive to use and/or do not provide adequate detail and perspective. The aim of this work was to demonstrate that a protocol combining surface three-dimensional photographic imaging with traditional ultrasound images may be a solution to the problem of probe localization, this approach being termed surface point cloud ultrasound (SPC-US). Ultrasound images were obtained of major vessels in an ultrasound training phantom, while simultaneously obtaining surface point cloud (SPC) 3D photographic images, with additional scanning performed on the right forearm soft tissues, kidneys, chest, and pelvis. The resulting sets of grayscale/color Doppler ultrasound and SPC images are juxtaposed and displayed for interpretation in a manner analogous to current text-based annotation or computer-generated stick figure probe position illustrations. Clearly demonstrated is that SPC-US better communicates information of probe position and orientation. Overall, it is shown that SPC-US provides much richer image representations of probe position on the patients than the current prevailing schemes. SPC-US turns out to be a rather general technique with many anticipated future applications, though only a few sample applications are illustrated in the present work.

Volume Navigation Technique for Ultrasound-Guided Biopsy of Breast Lesions Detected Only at MRI

OBJECTIVE

The purpose of this study is to assess the utility of a volume navigation technique (VNT) for ultrasound-guided biopsy of MRI-detected, but sonographically ambiguous or occult, breast lesions.

SUBJECTS AND METHODS

Within a recruitment period of 13 months (January 1, 2014, through February 1, 2015), 22 patients with 26 BI-RADS category 4 or 5 lesions that were detected at MRI but missed at second-look ultrasound were reimaged using a rapid sequence and a flexible body coil in a 3-T MRI scanner. Patients were supine, with three skin markers placed on the breasts. MRI volume data were coregistered to real-time ultrasound in a dedicated platform, and MRI-detected lesions (six masses, 11 nonmass enhancements, eight foci, and one architectural distortion) were sought using VNT-guided ultrasound. Five needle biopsy specimens were obtained either from each sonographically detected lesion (n = 11) or from VNT-guided sonographically localized breast volume corresponding to the MRI-detected, but still ultrasound-occult, lesions (n = 15).

RESULTS

Histopathologic analysis revealed 18 benign and six malignant lesions. The remaining two lesions, both of which appeared as masses at MRI, were high risk and were upgraded to carcinoma after excisional biopsy. All malignant lesions underwent curative surgery; the final histopathologic diagnoses remained unchanged. Of the six malignant lesions, one was a mass, three were nonmass enhancements, and two were enhancing foci at MRI. Three malignant lesions were occult at ultrasound, and three were discerned as subtle hypoechoic changes. No benign lesion was sonographically visualized as a mass, and none progressed, with 56% disappearing at MRI performed during the follow-up period (mean, 14 months).

CONCLUSION

Coregistration of MRI and real-time ultrasound enables sonographic localization of breast lesions detected at MRI only. VNT is a feasible alternative to MRI-guided biopsy of ultrasound-occult breast lesions.

Detection and Removal of Ceramic Clip Markers from Breast Tissue by Ultrasound-Guided, Vacuum-Assisted Minimally Invasive Biopsy in a Turkey Breast Model

This article explores the ability of sonographically guided, vacuum-assisted minimally invasive biopsy (VAB) to detect and remove ceramic clip markers from breast tissue. This is a feasibility pre-study for a clinical study using vacuum-assisted biopsy to predict pathologic complete response of breast cancer. Twenty-six ceramic clip markers were placed in five turkey breasts. Clip markers were then detected sonographically and removed using VAB by experienced physicians. Quality of visibility was graded by the performing doctors. The specimens were examined macroscopically to see if they contained the clip marker. The main outcome measure was the accuracy of VAB to detect and remove the clip marker. The VAB device was inspected for any damage possibly caused by hitting the clip marker. The clip markers were detected in 25 cases (96.2%). Twenty clip markers (76.9%) were removed completely by VAB and five (19.2%) were partially removed. One clip marker (3.8%) was not removed. On average, detection of the clip marker took 67 s and the biopsy took 178 s. Quality of visibility was mostly graded as very good (14 cases/53.8%) or good (nine cases/34.6%), and in all of these cases the clip marker was at least partially removed. The clip marker was visible and removed in the vast majority of the cases. VAB is able to remove the clip marker in integrity without causing damage to the system.