Contrast enhanced breast MRI: Spatial displacement from prone to supine patient's position. Preliminary results

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.

Intraoperative Supine Breast MRI for Residual Tumor Assessment after Breast-Conserving Therapy in Early-Stage Breast Cancer

Purpose To evaluate the diagnostic performance of intraoperative supine MRI (isMRI) in identifying residual tumor burden immediately after breast-conserving therapy (BCT). Materials and Methods This single-institution prospective study (April 2012-December 2022) included 43 consecutive participants with stage 0-II breast cancer. Three participants with multicentric disease were excluded from the final analysis. Preoperative supine MRI was performed after standard preoperative prone MRI to compare tumor sizes and distances to the nipple, chest wall, and skin. After lumpectomy, the saline-filled surgical cavity was assessed for residual tumor at 3-T isMRI in the operating suite. Diagnostic accuracy of isMRI findings in identifying residual tumor at resection margins was assessed using histopathology of shave margin specimens as the reference standard. Performance metrics of isMRI and re-excision rates were analyzed at per-participant and per-margin levels. Results Forty participants (median age, 58.5 years; range, 40-76 years) with 44 breast cancers (36 unifocal and four multifocal) underwent BCT, all with a single lumpectomy site. Margin assessment using isMRI yielded accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 80%, 50%, 93%, 75%, and 81% per participant, respectively; and 93%, 52%, 97%, 65%, and 96% per margin. Second re-excision was avoided in two of six (33%) participants with true-positive isMRI readings, decreasing the final re-excision rate from 18% to 13%. Histopathology of six false-negative isMRI cases revealed residual invasive carcinomas, all smaller than 0.3 cm, or intermediate-to-high grade ductal carcinoma in situ. Conclusion Intraoperative assessment for residual tumor after BCT using isMRI demonstrated promising accuracy to guide targeted margin clearance within the same operation. Keywords: Breast, MR-Imaging, MR-Dynamic Contrast Enhanced, Oncology Supplemental material is available for this article. © RSNA, 2025.

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.

Improving Lesion Location Reproducibility in Handheld Breast Ultrasound

Interoperator variability in the reproducibility of breast lesions found by handheld ultrasound (HHUS) can significantly interfere with clinical care. This study analyzed the features associated with breast mass position differences during HHUS. The ability of operators to reproduce the position of small masses and the time required to generate annotations with and without a computer-assisted scanning device (DEVICE) were also evaluated. This prospective study included 28 patients with 34 benign or probably benign small breast masses. Two operators generated manual and automated position annotations for each mass. The probe and body positions were systematically varied during scanning with the DEVICE, and the features describing mass movement were used in three logistic regression models trained to discriminate small from large breast mass displacements (cutoff: 10 mm). All models successfully discriminated small from large breast mass displacements (areas under the curve: 0.78 to 0.82). The interoperator localization precision was 6.6 ± 2.8 mm with DEVICE guidance and 19.9 ± 16.1 mm with manual annotations. Computer-assisted scanning reduced the time to annotate and reidentify a mass by 33 and 46 s on average, respectively. The results demonstrated that breast mass location reproducibility and exam efficiency improved by controlling operator actionable features with computer-assisted HHUS.

Improvement of Breast Cancer Detection Using Dual-Layer Spectral CT

This study aimed to investigate the diagnostic performance of breast mass detection on monoenergetic image data at 40 keV (MonoE40) and on iodine maps (IM) compared with conventional image data (CI). In this prospective single-center case-control study, 50 breast cancer patients were examined using contrast-enhanced dual-layer spectral CT. For qualitative and quantitative comparison of MonoE40 and IM with CI image data, four blinded, independent readers assessed 300 randomized single slices (two slices for each imaging type per case) with or without cancerous lesions for the presence of a breast mass. Detection sensitivity and specificity were calculated and readers rated their subjective diagnostic certainty. For statistical analysis of sensitivity and specificity, a paired t-test and ANOVA were used (significance level p = 0.05). A total of 50 female patients (median age 51 years, range 28-83 years) participated. IM had the highest overall scores in sensitivity and specificity for breast cancer detection, with 0.97 ± 0.06 and 0.95 ± 0.07, respectively, compared with 0.90 ± 0.04 and 0.92 ± 0.06 in CI. MonoE40 yielded a sensitivity of 0.96 ± 0.02 and specificity of 0.94 ± 0.08. All differences in sensitivity and specificity between MonoE or IM and CI were statistically significant (p < 0.001). The superiority of IM sensitivity and specificity was most pronounced in patients with dense breasts. Spectral CT improved the detection of breast cancer with higher sensitivity and specificity compared to conventional image data in our study.

Feasibility of online non-rigid motion correction for high-resolution supine breast MRI

PURPOSE

Conventional breast MRI is performed in the prone position with a dedicated coil. This allows high-resolution images without breast motion, but the patient position is inconsistent with that of other breast imaging modalities or interventions. Supine breast MRI may be an interesting alternative, but respiratory motion becomes an issue. Motion correction methods have typically been performed offline, for instance, the corrected images were not directly accessible from the scanner console. In this work, we seek to show the feasibility of a fast, online, motion-corrected reconstruction integrated into the clinical workflow.

METHODS

Fully sampled T2 -weighted (T2 w) and accelerated T1 -weighted (T1 w) breast supine MR images were acquired during free-breathing and were reconstructed using a non-rigid motion correction technique (generalized reconstruction by inversion of coupled systems). Online reconstruction was implemented using a dedicated system combining the MR raw data and respiratory signals from an external motion sensor. Reconstruction parameters were optimized on a parallel computing platform, and image quality was assessed by objective metrics and by radiologist scoring.

RESULTS

Online reconstruction time was 2 to 2.5 min. The metrics and the scores related to the motion artifacts significantly improved for both T2 w and T1 w sequences. The overall quality of T2 w images was approaching that of the prone images, whereas the quality of T1 w images remained significantly lower.

CONCLUSION

The proposed online algorithm allows a noticeable reduction of motion artifacts and an improvement of the diagnostic quality for supine breast imaging with a clinically acceptable reconstruction time. These findings serve as a starting point for further development aimed at improving the quality of T1 w images.

Panoramic Magnetic Resonance Imaging of the Breast With a Wearable Coil Vest

BACKGROUND

Breast cancer, the most common malignant cancer in women worldwide, is typically diagnosed by x-ray mammography, which is an unpleasant procedure, has low sensitivity in women with dense breasts, and involves ionizing radiation. Breast magnetic resonance imaging (MRI) is the most sensitive imaging modality and works without ionizing radiation, but is currently constrained to the prone imaging position due to suboptimal hardware, therefore hampering the clinical workflow.

OBJECTIVES

The aim of this work is to improve image quality in breast MRI, to simplify the clinical workflow, shorten measurement time, and achieve consistency in breast shape with other procedures such as ultrasound, surgery, and radiation therapy.

MATERIALS AND METHODS

To this end, we propose "panoramic breast MRI"-an approach combining a wearable radiofrequency coil for 3 T breast MRI (the "BraCoil"), acquisition in the supine position, and a panoramic visualization of the images. We demonstrate the potential of panoramic breast MRI in a pilot study on 12 healthy volunteers and 1 patient, and compare it to the state of the art.

RESULTS

With the BraCoil, we demonstrate up to 3-fold signal-to-noise ratio compared with clinical standard coils and acceleration factors up to 6 × 4. Panoramic visualization of supine breast images reduces the number of slices to be viewed by a factor of 2-4.

CONCLUSIONS

Panoramic breast MRI allows for high-quality diagnostic imaging and facilitated correlation to other diagnostic and interventional procedures. The developed wearable radiofrequency coil in combination with dedicated image processing has the potential to improve patient comfort while enabling more time-efficient breast MRI compared with clinical coils.

Ultrasound diagnosis of non-mass MRI-detected lesions

Magnetic resonance imaging (MRI)-detected lesions are often category 2 or 3 lesions on initial ultrasound examination. In addition, in the case of new non-mass lesions detected on MRI, one would expect to find lesions with ductal dilatation with minimal secretory accumulation, single short lesions with ductal dilatation, cyst-like lesions less than 5 mm in size, mammary gland-like lesions less than 8 mm in size, and very indistinct lesions. Detection is expected to be even more difficult. Currently, there are no clear uniform criteria for the indication of second-look ultrasonography (US) for MRI-detected lesions, so it is not possible to make a general comparison, but recent studies have indicated that the ratio of mass to non-mass MRI-detected lesions is 7:3. And it has been pointed out that the percentage of malignancy is about 30% for each. Before about 2012, the US detection rate was about 70%, and MRI-guided biopsies of undetected lesions showed a small percentage of malignant lesions. Therefore, some observers believe that lesions not detected on US should be followed up, while others believe that MRI-guided biopsy should be performed. Recently, however, the use of surrounding anatomical structures as landmarks for second-look US has increased the detection rate to as high as 87-99%, and the percentage of malignancy remains the same. In addition, recent surveillance of high-risk breast cancer requires careful management of MRI-detected lesions. In this review, we will discuss the literature on MRI-detected lesions and describe ultrasound techniques to accurately detect small lesions and reliably reveal pale lesions based on their structural differences from their surroundings.

Soft Tissue Monitoring of the Surgical Field: Detection and Tracking of Breast Surface Deformations

OBJECTIVE

Deformable object tracking is common in the computer vision field, with applications typically focusing on nonrigid shape detection and usually not requiring specific three-dimensional point localization. In surgical guidance however, accurate navigation is intrinsically linked to precise correspondence of tissue structure. This work presents a contactless, automated fiducial acquisition method using stereo video of the operating field to provide reliable three-dimensional fiducial localization for an image guidance framework in breast conserving surgery.

METHODS

On n = 8 breasts from healthy volunteers, the breast surface was measured throughout the full range of arm motion in a supine mock-surgical position. Using hand-drawn inked fiducials, adaptive thresholding, and KAZE feature matching, precise three-dimensional fiducial locations were detected and tracked through tool interference, partial and complete marker occlusions, significant displacements and nonrigid shape distortions.

RESULTS

Compared to digitization with a conventional optically tracked stylus, fiducials were automatically localized with 1.6 ± 0.5 mm accuracy and the two measurement methods did not significantly differ. The algorithm provided an average false discovery rate <0.1% with all cases' rates below 0.2%. On average, 85.6 ± 5.9% of visible fiducials were automatically detected and tracked, and 99.1 ± 1.1% of frames provided only true positive fiducial measurements, which indicates the algorithm achieves a data stream that can be used for reliable on-line registration.

CONCLUSIONS

Tracking is robust to occlusions, displacements, and most shape distortions.

SIGNIFICANCE

This work-flow friendly data collection method provides highly accurate and precise three-dimensional surface data to drive an image guidance system for breast conserving surgery.

Incorporating heterogeneity and anisotropy for surgical applications in breast deformation modeling

BACKGROUND

Simulating soft-tissue breast deformations is of interest for many applications including image fusion, longitudinal registration, and image-guided surgery. For the surgical use case, positional changes cause breast deformations that compromise the use of preoperative imaging to inform tumor excision. Even when acquiring imaging in the supine position, which better reflects surgical presentation, deformations still occur due to arm motion and orientation changes. A biomechanical modeling approach to simulate supine breast deformations for surgical applications must be both accurate and compatible with the clinical workflow.

METHODS

A supine MR breast imaging dataset from n = 11 healthy volunteers was used to simulate surgical deformations by acquiring images in arm-down and arm-up positions. Three linear-elastic modeling approaches with varying levels of complexity were used to predict deformations caused by this arm motion: a homogeneous isotropic model, a heterogeneous isotropic model, and a heterogeneous anisotropic model using a transverse-isotropic constitutive model.

FINDINGS

The average target registration errors for subsurface anatomical features were 5.4 ± 1.5 mm for the homogeneous isotropic model, 5.3 ± 1.5 mm for the heterogeneous isotropic model, and 4.7 ± 1.4 mm for the heterogeneous anisotropic model. A statistically significant improvement in target registration error was observed between the heterogeneous anisotropic model and both the homogeneous and the heterogeneous isotropic models (P < 0.01).

INTERPRETATION

While a model that fully incorporates all constitutive complexities of anatomical structure likely achieves the best accuracy, a computationally tractable heterogeneous anisotropic model provided significant improvement and may be applicable for image-guided breast surgeries.

Can Supine Breast Magnetic Resonance Imaging After a Dynamic Contrast-Enhanced Breast Magnetic Resonance Imaging Provide Information for Supine Procedures?

METHODS

A retrospective analysis was conducted on 75 lesions in 50 patients with pathologically proven breast cancer who underwent MRI in prone and supine positions between December 2019 and December 2020. The transverse, anteroposterior, and craniocaudal dimensions (in millimeters) of the tumor in the x-, y-, and z-axes were measured. Distances from the center of the tumor to the chest wall and the adjacent skin were measured on transverse and reformatted sagittal images. In cases where multifocal lesions were present, the transverse, anteroposterior, and craniocaudal distances between the tumor centers in the x-, y-, and z-axes were measured. Differences between measurements in supine and prone MRI were evaluated with the Mann-Whitney U and the Wilcoxon tests. P values of less than 0.05 were considered to indicate a statistically significant difference.

RESULTS

The analysis revealed 31 MRIs with 1 and 20 with multifocal lesions. The x-axis dimension of the lesions in prone and supine positions did not significantly differ (P = 0.198) between the 2 positions. A significant difference in the y- and z-axes dimensions was observed between the prone and supine position (P = 0.00 for both). The distance from the tumor to the chest wall and the adjacent skin showed significant difference (P = 0.00 for both). For multifocal lesions, the distance between the lesions showed a significant difference on the y-axis (P = 0.00).

CONCLUSIONS

This study showed a significant difference in the tumor size, location, and tumor-to-tumor distances due to change of patient position, from the standard prone MRI to the supine position in the operating room, resulting in distortion, spatial repositioning, and convergence of the lesions. Supine MRI may be considered in providing a less extensive surgery.

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.

Computational Imaging to Compensate for Soft-Tissue Deformations in Image-Guided Breast Conserving Surgery

OBJECTIVE

During breast conserving surgery (BCS), magnetic resonance (MR) images aligned to accurately display intraoperative lesion locations can offer improved understanding of tumor extent and position relative to breast anatomy. Unfortunately, even under consistent supine conditions, soft tissue deformation compromises image-to-physical alignment and results in positional errors.

METHODS

A finite element inverse modeling technique has been developed to nonrigidly register preoperative supine MR imaging data to the surgical scene for improved localization accuracy during surgery. Registration is driven using sparse data compatible with acquisition during BCS, including corresponding surface fiducials, sparse chest wall contours, and the intra-fiducial skin surface. Deformation predictions were evaluated at surface fiducial locations and subsurface tissue features that were expertly identified and tracked. Among n = 7 different human subjects, an average of 22 ± 3 distributed subsurface targets were analyzed in each breast volume.

RESULTS

The average target registration error (TRE) decreased significantly when comparing rigid registration to this nonrigid approach (10.4 ± 2.3 mm vs 6.3 ± 1.4 mm TRE, respectively). When including a single subsurface feature as additional input data, the TRE significantly improved further (4.2 ± 1.0 mm TRE), and in a region of interest within 15 mm of a mock biopsy clip TRE was 3.9 ± 0.9 mm.

CONCLUSION

These results demonstrate accurate breast deformation estimates based on sparse-data-driven model predictions.

SIGNIFICANCE

The data suggest that a computational imaging approach can account for image-to-surgery shape changes to enhance surgical guidance during BCS.

Contrast-Enhanced Mammography Versus MRI in the Evaluation of Neoadjuvant Therapy Response in Patients With Breast Cancer: A Prospective Study

BACKGROUND. Contrast-enhanced mammography (CEM) is rapidly expanding as a credible alternative to MRI in various clinical settings. OBJECTIVE. The purpose of this study was to compare CEM and MRI for neoadjuvant therapy (NAT) response assessment in patients with breast cancer. METHODS. This prospective study included 51 patients (mean age, 46 ± 11 [SD] years) with biopsy-proven breast cancer who were candidates for NAT from May 2015 to April 2018. Patients underwent both CEM and MRI before, during, and after NAT (pre-NAT, mid-NAT, and post-NAT, respectively). Post-NAT CEM included a 6-minute delayed acquisition. One breast radiologist with experience in CEM reviewed CEM examinations; one breast radiologist with experience in MRI reviewed MRI examinations. The radiologists assessed for the presence of an enhancing lesion; if an enhancing lesion was detected, its size was measured. RECIST version 1.1 response assessment categories were derived. Pathologic complete response (pCR) was defined as absence of both invasive cancer and ductal carcinoma in situ (DCIS). RESULTS. Of 51 patients, 16 achieved pCR. CEM yielded systematically lower size measurements compared with MRI (mean difference, -0.2 mm for pre-NAT, -0.7 mm for mid-NAT, and -0.3 mm for post-NAT). All post-NAT imaging tests yielded systematically larger size measurements compared with pathology (mean difference, 0.8 mm for CEM, 1.2 mm for MRI, and 1.9 mm for delayed CEM). Of 12 patients with residual DCIS, an enhancing lesion was detected in seven on post-NAT CEM, eight on post-NAT MRI, and nine on post-NAT delayed CEM. Agreement of RECIST response categories between CEM and MRI, expressed as kappa coefficient, was 0.791 at mid-NAT and 0.871 at post-NAT. For detecting pCR by post-NAT imaging, sensitivity and specificity were 81% and 83% for CEM, 100% and 86% for MRI, and 81% and 89% for delayed CEM. Sensitivity was significantly higher for MRI than CEM (p = .001) and delayed CEM (p = .002); remaining comparisons were not significant (p > .05). CONCLUSION. After NAT for breast cancer, CEM and MRI yielded comparable assessments of lesion size (both slightly overestimated vs pathology) and RECIST categories and showed no significant difference in specificity for pCR. MRI had higher sensitivity for pCR. Delayed CEM acquisition may help detect residual DCIS. CLINICAL IMPACT. Although MRI remains the preferred test for NAT response monitoring, the findings support CEM as a useful alternative when MRI is contraindicated or not tolerated.

Dynamic contrast-enhanced breast magnetic resonance imaging findings that affect the magnetic resonance-directed ultrasound correlation of non-mass enhancement lesions: a single-center retrospective study

OBJECTIVE

Our single-center retrospective study aimed to evaluate the relationship between magnetic resonance (MR)-directed ultrasound (MDUS) detectability and MRI findings of non-mass enhancement (NME) lesions, regarding the morphologic and enhancement features, the distance from the skin and nipple, and the presence of concomitant landmarks.

METHODS

A total of 350 MRI-detected NME lesions that were determined between January 2015 and May 2019 and subsequently underwent MDUS were analyzed. The MRI findings, biopsy results, and follow-up outcomes of lesions were recorded. The correlation between the MRI findings of the lesions and MDUS detectability was analyzed.

RESULTS

114 (32.6%) of the 350 lesions had a counterpart in the MDUS. Respectively, 66 (37.9%), 38 (43.2%) and 59 (38.3%) of the lesions detected in MDUS were larger than 20 mm in size, with a distance of less than 20 mm to the nipple and 15 mm to the skin. The lesion size and lesion distance to the nipple and skin were significantly associated with a ultrasound correlate (p < 0.05). The MDUS detection rate was significantly higher in NME lesions with MR findings including diffuse distribution (p < 0.001), clustered-ring enhancement pattern (p < 0.001), washout kinetic curve (p = 0.006), and MR-BIRADS category 5 (p < 0.001). Multivariate logistic regression showed that only the clustered-ring enhancement pattern was significantly associated with an MDUS correlation (p < 0.001).

CONCLUSION

Statistically significant correlations were found between the size, distance to the nipple and skin, distribution pattern, enhancement pattern and kinetic curve of the NME lesions on MRI and ultrasound detectability.

ADVANCES IN KNOWLEDGE

We found that clustered-ring enhancement patterns were significantly more frequent in MR-directed ultrasound detectable lesions.

Tips for finding magnetic resonance imaging-detected suspicious breast lesions using second-look ultrasonography: a pictorial essay

Second-look ultrasonography (US) is a targeted breast US examination that evaluates suspicious lesions detected on magnetic resonance imaging (MRI). It is a useful tool for determining the probability of malignancy and facilitating US-guided biopsy. Lesions detected on MRI and US should be correlated accurately, which is challenging in some cases. This article documents second-look US and MRI findings that are correlated with the pathology, and suggests helpful approaches for correlating between the two modalities.

Evaluation of an MRI/US fusion technique for the detection of non-mass enhancement of breast lesions detected by MRI yet occult on conventional B-mode second-look US

PURPOSE

The aim of this study was to verify the utility of second-look ultrasound (US) using real-time virtual sonography (RVS), a magnetic resonance imaging (MRI)/US fusion technique, in identifying MRI-detected breast lesions with non-mass enhancement (NME).

METHODS

Consecutive patients who had one or more NME lesions detected by MRI yet occult on the subsequent second-look US in conventional B (cB)-mode imaging were enrolled in the study between June 2015 and April 2020. Supine MRI of the lesions was performed and, using its data, second-look US using RVS was performed.

RESULTS

Twenty patients with 21 NME lesions were included. The overall median lesion size on prone MRI was 23 mm (range, 5-63 mm). Supine MRI identified all the 21 NME lesions, and second-look US using RVS successfully detected 18 (86%) of them. RVS-guided biopsy was performed for histopathological evaluation, showing that nine of the 18 lesions were benign and the other nine malignant. Of the nine malignant lesions, two (22%) were invasive cancer and seven (78%) were ductal carcinoma in situ. In four of five patients who underwent prone MRI for preoperative evaluation, the diagnosis was benign and surgery was conducted as originally planned. In the other patient, the diagnosis was malignant and contralateral breast-conserving surgery was added. Three (14%) of the 21 NME lesions had no RVS correlates and were judged to be benign after 24-month follow-up.

CONCLUSION

The results suggest that second-look US using RVS helps identify MRI-detected NME lesions that are occult on cB-mode second-look US.

Utility of 70-kV single-energy CT in depicting the extent of breast cancer for preoperative planning

PURPOSE

To evaluate the detectability of breast cancer and visibility of the tumor extent using 70-kV single-energy contrast-enhanced (CE) breast computed tomography (70-kV CECT) compared with CE breast magnetic resonance imaging (CEMR).

METHODS

Between 2013 and 2015, 110 patients with 112 breast cancer lesions who underwent breast surgery after undergoing both 70-kV CECT and CEMR were enrolled. The major axis lengths of the breast lesion were measured and compared with the pathologically determined major axes. Agreement in the measured major axes was evaluated using the intra-class correlation coefficient (ICC).

RESULTS

Both 70-kV CECT and CEMR depicted all breast cancer lesions. The mean major axis was 3.0 (95% confidence interval [CI], 2.5-3.4) cm on CECT and 2.9 (2.6-3.3) cm on CEMR. The mean differences between the pathologically and radiologically measured major axes on 70-kV CECT and CEMR were 0.9 (0.7-1.1) and 1.0 (0.8-1.2) cm, respectively. The accuracy of the radiological major axes compared with the pathological major axes was 82.1% and 80.4% on CECT and CEMR, respectively (p = 0.81). The major axes on the two modalities demonstrated moderate agreement (ICC = 0.69, 95% CI 0.58-0.77). Pathologically and radiologically measured major axes on 70-kV CECT and CEMR demonstrated excellent agreement (ICC = 0.91, 95% CI 0.93-0.96).

CONCLUSIONS

Low-tube voltage (70-kV) CECT is the preferred modality to identify breast cancer lesions and tumor extent for preoperative planning because it has a similar diagnostic ability to CEMR and can be performed in the supine position.

Solving the preoperative breast MRI conundrum: design and protocol of the MIPA study

Despite its high diagnostic performance, the use of breast MRI in the preoperative setting is controversial. It has the potential for personalized surgical management in breast cancer patients, but two of three randomized controlled trials did not show results in favor of its introduction for assessing the disease extent before surgery. Meta-analyses showed a higher mastectomy rate in women undergoing preoperative MRI compared to those who do not. Nevertheless, preoperative breast MRI is increasingly used and a survey from the American Society of Breast Surgeons showed that 41% of respondents ask for it in daily practice. In this context, a large-scale observational multicenter international prospective analysis (MIPA study) was proposed under the guidance of the European Network for the Assessment of Imaging in Medicine (EuroAIM). The aims were (1) to prospectively and systematically collect data on consecutive women with a newly diagnosed breast cancer, not candidates for neoadjuvant therapy, who are offered or not offered breast MRI before surgery according to local practice; (2) to compare these two groups in terms of surgical and clinical endpoints, adjusting for covariates. The underlying hypotheses are that MRI does not cause additional mastectomies compared to conventional imaging, while reducing the reoperation rate in all or in subgroups of patients. Ninety-six centers applied to a web-based call; 36 were initially selected based on volume and quality standards; 27 were active for enrollment. On November 2018, the target of 7000 enrolled patients was reached. The MIPA study is presently at the analytic phase. Key Points • Breast MRI has a high diagnostic performance but its utility in the preoperative setting is controversial. • A large-scale observational multicenter prospective study was launched to compare women receiving with those not receiving preoperative MRI. • Twenty-seven centers enrolled more than 7000 patients. The study is presently at the analytic phase.

Breast tumor movements analysis using MRI scans in prone and supine positions

We quantitatively evaluated breast tumor movement and volume changes between magnetic resonance imaging (MRI) scans in prone and supine positions. Twenty-seven breast tumor patients who received neoadjuvant systemic therapy (NST) for breast-conserving surgery were studied. Before and after NST, MRI scans in prone and supine positions were performed immediately. Tumor segmentation, volume, and position of tumors were evaluated in both positions. Average tumor volumes in prone and supine positions did not significantly differ (p = 0.877). Tumor movement from prone to supine positions from the origin of the bottom center of the sternum was strongly correlated with the distance from the tumor center to the chest wall (r = 0.669; p < 0.05). Tumor changes from prone to supine positions measured from the origin of the nipple depended on the location of the tumor in the breast. The prone-to-supine movement of all tumors from the origin of the bottom center of the sternum tended to move outward from the sagittal centerline of the body on the coronal plane, to the inside of the body on the sagittal plane, and outward and downward close to the body on the axial plane, which might help in planning operations using prone MRI in supine-position breast cancer surgery.

Dual-Energy CT for Locoregional Staging of Breast Cancer: Preliminary Results

OBJECTIVE. The objective of this study was to demonstrate the feasibility of dual-energy CT (DECT) for locoregional staging of breast cancer and differentiation of tumor histotypes. MATERIALS AND METHODS. From January 2016 to July 2017, a total of 31 patients (mean [± SD] age, 55.8 ± 14.8 years) with breast cancer diagnosed by needle biopsy who underwent preoperative contrast-enhanced DECT for staging purposes were selected from a retrospective review of institutional databases. Monochromatic images obtained at 40 and 70 keV were evaluated by two readers who determining the number of hypervascularized tumors present and the largest tumor diameter for each breast. The attenuation values and iodine concentration of tumors and normal breast tissue and the ratios of these findings in each tissue type were recorded. Cancers were classified as ductal carcinoma in situ, invasive ductal carcinoma, and invasive lobular carcinoma. The reference standard was the final pathologic finding after surgery. RESULTS. A total of 64 tumor lesions were found at histopathologic analysis versus 67 on DECT for 34 breasts (three bilateral cancers were included). Nonparametric statistics were used. The largest lesion diameter observed DECT was 33.2 ± 20.5 mm versus 31.8 ± 20.5 mm on pathologic analysis, and cancer distribution was correctly classified for 31 of 34 (91%) cases. ROC curves derived from lesion iodine concentration showed that the optimal thresholds for distinguishing infiltrating carcinomas (invasive lobular and ductal carcinomas) and from other lesions were 1.70 mg/mL (sensitivity, 94.9%; specificity, 93.0%; AUC value, 0.968). ROC curves derived from the ratio of the iodine concentration in lesions to that in normal breast parenchyma showed that 6.13 was the optimal threshold to distinguish invasive ductal carcinoma from other lesions (sensitivity, 87.0%; specificity, 81.1%; AUC value, 0.914). CONCLUSION. DECT is feasible and seems to be a reliable tool for locoregional staging of breast cancer.

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.

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.

Feasibility of mapping breast cancer with supine breast MRI in patients scheduled for oncoplastic surgery

OBJECTIVES

To prospectively determine the feasibility of preoperative supine breast MRI in breast cancer patients scheduled for oncoplastic breast-conserving surgery.

METHODS

In addition to a diagnostic prone breast MRI, a supplementary supine MRI was performed with the patient in the surgical position including skin markers. Tumours' locations were ink-marked on the skin according to findings obtained from supine MRI. Changes in tumours' largest diameter and locations between prone and supine MRI were measured and compared to histology. Nipple-to-tumour and tumour-to-chest wall distances were also measured. Tumours and suspicious areas were surgically removed according to skin ink-markings. The differences between MRI measurements with reference to histopathology were evaluated with the paired-sample t test.

RESULTS

Fourteen consecutive patients, 15 breasts and 27 lesions were analysed. Compared to histology, prone MRI overestimated tumour size by 47.1% (p = 0.01) and supine MRI by 14.5% (p = 0.259). In supine MRI, lesions' mean diameters and areas were smaller compared to prone MRI (- 20.9%, p = 0.009 and - 38.3%, p = 0.016, respectively). This difference in diameter was more pronounced in non-mass lesions (- 31.2%, p = 0.031) compared to mass lesions (- 9.2%, p = 0.009). Tumours' mean distance from chest wall diminished by 69.4% (p < 0.001) and from nipple by 18.2% (p < 0.001). Free microscopic margins were achieved in first operation in all patients.

CONCLUSIONS

Supine MRI in the surgical position is feasible and useful in the precise localisation of prone MRI-detected lesions and provides a helpful tool to implement in surgery. Supine MRI more accurately determines tumours' size and location and might have an important role to diminish overestimations.

KEY POINTS

• Breath-hold supine breast MRI is feasible using commercially available coils and sequences. • Size and area of lesions on MRI were consistently smaller when measured from the supine position as compared to the prone position. • Supine breast MRI is useful in the precise preoperative localisation of prone MRI-detected lesions. •.

Pre-Operative Planning Using Real-Time Virtual Sonography, an MRI/Ultrasound Image Fusion Technique, for Breast-Conserving Surgery in Patients with Non-Mass Enhancement on Breast MRI: A Preliminary Study

The purpose of this retrospective study was to evaluate the effect of pre-operative planning using real-time virtual sonography (RVS), a magnetic resonance imaging (MRI)/ultrasound (US) image fusion technique on breast-conserving surgery (BCS) in patients with non-mass enhancement (NME) on breast MRI. Between 2011 and 2015, we enrolled 12 consecutive patients who had lesions with NME that exceeded the US hypo-echoic area, in which it was particularly difficult to evaluate the tumor margin. During pre-operative planning before breast-conserving surgery, RVS was used to delineate the enhancing area on the breast surface after additional supine breast MRI was performed. We analyzed both the surgical margin positivity rate and the re-operation rate. All NME lesions corresponded to the index cancer. In all patients, the diameter of the NME lesion was greater than that of the hypo-echoic lesion. The median diameters of the NME and hypo-echoic lesions were 24 mm (range: 12-39 mm) and 8.0 mm (range: 4.9-18 mm), respectively (p = 0.0002). After RVS-derived skin marking was performed on the surface of the affected breast, lumpectomy and quadrantectomy were conducted in 7 and 5 patients, respectively. The surgical margins were negative in 10 (83%) patients. Two patients with positive margins were found to have ductal carcinoma in situ in 1 duct each, 2.4 and 3.2 mm from the resection margin, respectively. None of the patients required additional resection. Although further prospective studies are required, the findings of our preliminary study suggest that it is very well possible that the use of RVS-derived skin marking during pre-operative planning for BCS in patients with NME would have resulted in surgical outcomes similar to or better than those obtained without the use of such marking.

A system for automatic monitoring of surgical instruments and dynamic, non-rigid surface deformations in breast cancer surgery

When negative tumor margins are achieved at the time of resection, breast conserving therapy (lumpectomy followed with radiation therapy) offers patients improved cosmetic outcomes and quality of life with equivalent survival outcomes to mastectomy. However, high reoperation rates ranging 10-59% continue to challenge adoption and suggest that improved intraoperative tumor localization is a pressing need. We propose to couple an optical tracker and stereo camera system for automated monitoring of surgical instruments and non-rigid breast surface deformations. A bracket was designed to rigidly pair an optical tracker with a stereo camera, optimizing overlap volume. Utilizing both devices allowed for precise instrument tracking of multiple objects with reliable, workflow friendly tracking of dynamic breast movements. Computer vision techniques were employed to automatically track fiducials, requiring one-time initialization with bounding boxes in stereo camera images. Point based rigid registration was performed between fiducial locations triangulated from stereo camera images and fiducial locations recorded with an optically tracked stylus. We measured fiducial registration error (FRE) and target registration error (TRE) with two different stereo camera devices using a phantom breast with five fiducials. Average FREs of 2.7 ± 0.4 mm and 2.4 ± 0.6 mm with each stereo-camera device demonstrate considerable promise for this approach in monitoring the surgical field. Automated tracking was shown to reduce error when compared to manually selected fiducial locations in stereo camera image-based localization. The proposed instrumentation framework demonstrated potential for the continuous measurement of surgical instruments in relation to the dynamic deformations of a breast during lumpectomy.

Second-look US Using Real-time Virtual Sonography, a Coordinated Breast US and MRI System with Electromagnetic Tracking Technology: A Pilot Study

Our aim was to retrospectively evaluate the utility of second-look ultrasound (US) using real-time virtual sonography (RVS) for detection of conventional B-mode (cB-mode) occult magnetic resonance imaging (MRI)-detected breast lesions. Between July 2011 and May 2015, 53 consecutive patients who underwent second-look US to identify lesions detected by prone MRI were enrolled in this study. Second-look US using RVS was performed for cB-mode occult MRI-detected breast lesions after an additional supine MRI. In the 53 patients, 59 lesions were initially detected by prone MRI, followed by second-look US. Of the 59 lesions, 20 (34%) were identified by second-look US using cB-mode. Of the 39 (66%) cB-mode occult lesions, 38 (97%) were detected in supine MRI and 33 (85%) were detected by second-look US using RVS. MRI morphology types of the 33 lesions were as follows: mass, 16; non-mass enhancement, 5; and focus, 12. US-guided biopsy under RVS or excisional biopsy demonstrated that of the 33 lesions, 8 (24%) were malignant and the remaining 25 (76%) were benign. A total of 53 (90%) MRI-detected lesions were sonographically identified using both cB-mode and RVS (p < 0.001). All five remaining US-occult lesions could be followed up under RVS after the enhancing area was marked on the breast surface using RVS. Although further prospective studies are required, the findings of our pilot study suggest that second-look US using RVS with additional supine MRI may improve the sonographic and histopathologic detection rate of cB-mode occult MRI-detected breast lesions.

Supine Breast MRI Using Respiratory Triggering

RATIONALE AND OBJECTIVES

This study aims to evaluate if navigator-echo respiratory-triggered magnetic resonance acquisition can acquire supine high-quality breast magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Supine respiratory-triggered magnetic resonance imaging (Trig-MRI) was compared to supine non-Trig-MRI to evaluate breathing-induced motion artifacts (group 1), and to conventional prone non-Trig-MRI (group 2, 16-channel breast coil), all at 3T. A 32-channel thorax coil was placed on top of a cover to prevent breast deformation. Ten volunteers were scanned in each group, including one patient. The acquisition time was recorded. Image quality was compared by visual examination and by calculation of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and image sharpness (IS).

RESULTS

Scan time increased from 56.5 seconds (non-Trig-MRI) to an average of 306 seconds with supine Trig-MRI (range: 120-540 seconds). In group 1, the median values (interquartile range) of SNR, CNR, and IS improved from 11.5 (6.0), 7.3 (3.1), and 0.23 (0.2) cm on supine non-Trig-MRI to 38.1 (29.1), 32.8 (29.7), and 0.12 (0) cm (all P < 0.01) on supine Trig-MRI. All qualitative image parameters in group 1 improved on supine Trig-MRI (all P < 0.01). In group 2, SNR and CNR improved from 14.7 (6.8) and 12.6 (5.6) on prone non-Trig-MRI to 36.2 (12.2) and 32.7 (12.1) (both P < 0.01) on supine Trig-MRI. IS was similar: 0.10 (0) cm vs 0.11 (0) cm (P = 0.88).

CONCLUSIONS

Acquisition of high-quality supine breast MRI is possible when respiratory triggering is applied, in a similar setup as during subsequent treatment. Image quality improved when compared to supine non-triggered breast MRI and prone breast MRI, but at the cost of increased acquisition time.

Predictive detection areas for identifying additional MRI-detected breast lesions on second-look ultrasonography

PURPOSE

Identifying an additional MRI-detected breast lesion on second-look ultrasonography (US) is technically challenging because of lesion displacement with the patient's position change. The aim of this study is to help identify MRI-detected lesions on second-look US by developing a probing area, called "the predictive detection area" (PDA), and by assessing the PDA.

METHODS

We measured the nipple-to-lesion distances (NLDs) for 16 breast lesions on prone- and supine-position MRI sets and calculated the difference and angle between the two NLD vectors, representing the lesion displacement. The minimum and maximum differences and angles were chosen to form the PDA. Another 22 breast lesions, detected in the prone MRI, were identified on US by probing the PDA to evaluate the probability of existence.

RESULTS

The width between the minimum and maximum differences in two NLDs and the angle to form the PDA for the upper-inner, upper-outer, and lower-outer quadrants were 23.0 mm and 95.0°, 29.0 mm and 41.0°, and 18.0 mm and 17.0°, respectively. The respective probabilities of existence were 100, 80, and 100%.

CONCLUSIONS

The PDA had a high probability of existence and was acceptably accurate; therefore, the PDA in a second-look US has the potential to help operators to quickly identify additional MRI-detected lesions.

Magnetic Resonance Imaging-Directed Ultrasound Imaging of Non-Mass Enhancement in the Breast: Outcomes and Frequency of Malignancy

OBJECTIVES

This study was performed to determine the frequency, predictors, and outcomes of ultrasound (US) correlates for non-mass enhancement.

METHODS

From January 2005 to December 2011, a retrospective review of 5837 consecutive breast magnetic resonance imaging examinations at our institution identified 918 non-mass enhancing lesions for which follow-up or biopsy was recommended. Retrospective review of the images identified 879 of 918 lesions (96%) meeting criteria for non-mass enhancement. Patient demographics, pathologic results, and the presence of an adjacent landmark were recorded. Targeted US examinations were recommended for 331 of 879 cases (38%), and 284 of 331 women (86%) underwent US evaluations.

RESULTS

The US correlate rate for non-mass enhancement was 23% (64 of 284). An adjacent landmark was significantly associated with a US correlate (P < .001). Biopsy was recommended for 43 of 64 correlates (67%). Ultrasound-guided biopsy was performed on 39 of 43 (91%); 7 of 39 (18%) were malignant. No correlate was seen for 220 of 284 lesions (77%). At magnetic resonance imaging-guided biopsy, 14 of 117 (12%) were malignancies. For all biopsied non-mass enhancements, the malignancy rate was 18% (55 of 308) and was significantly more prevalent in the setting of a known index cancer (P < .001), older age (P < .001), the presence of a landmark (P = .002), and larger lesion size (P = .019).

CONCLUSIONS

Non-mass enhancement with an adjacent landmark is more likely to have a US correlate compared to non-mass enhancement without an adjacent landmark. Non-mass enhancement in the setting of a known index cancer, older age, a landmark, and larger lesion size is more likely to be malignant. However, no statistical difference was detected in the rate of malignancy between non-mass enhancement with (18%) or without (12%) a correlate. Absence of a correlate does not obviate the need to biopsy suspicious non-mass enhancement.

Clinical Utility of Real-Time MR-Navigated Ultrasound with Supine Breast MRI for Suspicious Enhancing Lesions Not Identified on Second-Look Ultrasound

This study evaluated the usefulness of magnetic resonance (MR)-navigated ultrasound (US) for evaluation of magnetic resonance imaging (MRI)-detected lesions not visible on second-look US and analyzed differences in lesion-to-nipple distance between supine and prone positions. Of the 831 consecutive patients who were diagnosed with breast cancer and examined with breast MRI from June 2013 to September 2015, 40 lesions in 37 patients who underwent MR-navigated US for MRI-detected lesions that were not visible on second-look US were included. First, MRI was performed in a prone position using a 1.5-T imager, and second, MRI was performed in a supine position for MR-navigated US. Of 40 lesions, 31 (78%) were identified with MR-navigated US, whereas 5 (13%) lesions disappeared on supine MRI and 4 (10%) exhibited no correlation on MR-navigated US. Of 31 lesions with pathologic confirmation, 7 (23%) were malignant, 2 (6%) were high-risk lesions and 22 (71%) were benign lesions. Comparison of the US findings of benign and malignant lesions revealed that orientation of the lesion differed significantly (p = 0.045), whereas lesion shape, margin and echo pattern did not significantly differ between the two groups (p = 0.088, p = 0.094 and p = 0.412, respectively). Median difference in lesion-to-nipple distance on supine and prone MRI was 8 mm (0-34 mm) in the horizontal direction and 5 mm (0-39.5 mm) in the vertical direction. Thirteen lesions exhibited a >1-cm difference in both horizontal and vertical directions. In conclusion, MR-navigated US was useful for the evaluation of MRI-detected lesions that were not visible on second-look US in breast cancer patients.

Retroareolar Carcinomas in Breast Ultrasound: Pearls and Pitfalls

Breast Ultrasound (US) is an important tool for both screening and diagnostic examinations. Although breast US has benefitted from significant recent technical improvements, its use for the retroareolar region is known to be more challenging than for other locations. The retroareolar location was defined by Giess et al. in 1998 as the region where any lesion is situated at less than two cm from the nipple and/or involves the nipple-areolar complex on mammogram. Understanding of the complex anatomy and physiology of the nipple-areolar region is important to avoid misinterpretation and misdiagnosis. The ability for the breast imager to manage difficulties related to the retroareolar area is paramount by adjusting settings (compounding, frequency, Doppler) and utilizing specific manoeuvers. Cases illustrating difficulties encountered in diagnosis of retroareolar carcinomas are presented.

Breast findings incidentally detected on body MRI

OBJECTIVES

To evaluate breast findings incidentally detected on body MRI.

METHODS

A retrospective review of the institutional database identified 1752 body MRI performed between January 2015 and September 2015. MRI of women with breast tissue visible in the field-of-view were reviewed for breast findings. Breast findings were classified with the breast imaging reporting and data system (BI-RADS) lexicon. The standard statistic, costs of additional work-up, and the clinical relevance were used to describe breast findings, and we calculated 95 % exact confidence intervals (CIs).

RESULTS

440 body MRI of 440 women (mean age: 57 ± 20 years) included breast tissue in the field-of-view. A total of 41 breast findings were identified in 41 patients. Breast findings were classified BI-RADS 2 N = 25, BI-RADS 3 N = 13, BI-RADS 4 N = 3. A total of 3.6 % [95 % CI 1.6 %, 5.6 %] women with breast tissue visible on MRI had a recommendation for further imaging work-up for a breast finding. The 18.7 % (3 of 16) of these patients had a clinically important finding (breast cancer). Further imaging evaluation increased costs of €108.3 per patient with a breast finding.

CONCLUSIONS

Clinically important breast findings could be detected on body MRI in up to 0.7 % (3 of 440) of women.

Supine breast US: how to correlate breast lesions from prone MRI

OBJECTIVE

To evaluate spatial displacement of breast lesions from prone MR to supine ultrasound positions, and to determine whether the degree of displacement may be associated with breast density and lesion histotype.

METHODS

380 patients underwent breast MR and second-look ultrasound. The MR and ultrasound lesion location within the breast gland, distances from anatomical landmarks (nipple, skin and pectoral muscle), spatial displacement (distance differences from the landmarks within the same breast region) and region displacement (breast region change) were prospectively evaluated. Differences between MR and ultrasound measurements, association between the degree of spatial displacement and both breast density and lesion histotypes were calculated.

RESULTS

In 290/380 (76%) patients, 300 MR lesions were detected. 285/300 (95%) lesions were recognized on ultrasound. By comparing MR and ultrasound, spatial displacement occurred in 183/285 (64.3%) cases while region displacement in 102/285 (35.7%) cases with a circumferential movement along an arc centred on the nipple, having supine ultrasound as the reference standard. A significant association between the degree of lesion displacement and breast density was found (p < 0.00001) with a significant higher displacement in case of fatty breasts. No significant association between the degree of displacement and lesion histotype was found (p = 0.1).

CONCLUSION

Lesion spatial displacement from MRI to ultrasound may occur especially in adipose breasts. Lesion-nipple distance and circumferential displacement from the nipple need to be considered for ultrasound lesion detection.

ADVANCES IN KNOWLEDGE

Second-look ultrasound breast lesion detection could be improved by calculating the lesion-nipple distance and considering that spatial displacement from MRI occurs with a circumferential movement along an arc centred on the nipple.

Real-time virtual sonography examination and biopsy for suspicious breast lesions identified on MRI alone

OBJECTIVES

The purpose of our study was to assess whether there is a potential additional value of real-time virtual sonography (RVS) to second-look ultrasound (US) examination and biopsy for breast lesions identified on MRI alone.

METHODS

A retrospective review of the records of 70 consecutive patients (78 lesions) with breast abnormalities identified on MRI alone was performed. All suspicious enhancing lesions were subsequently evaluated with second-look US. Lesions not observed on second-look US underwent RVS. Pathological findings were confirmed by subsequent percutaneous biopsy or excision.

RESULTS

Of the 78 MRI-detected lesions, second-look US correlation was made in 50 (64 %), including 22 malignant and 28 benign lesions. The remaining 28 lesions (36 %) were scheduled to undergo RVS. Four lesions were not visible on the second breast MRI. The remaining 24 lesions were RVS correlated and underwent RVS-guided biopsy; these included seven malignant and 17 benign lesions. Overall, 74 of 74 (100 %) true MRI-detected lesions were confirmed by histological results without using MRI-guided breast biopsy. The cancer rate was 29 %.

CONCLUSIONS

RVS can increase the sonographic detection and biopsy rate of lesions identified on breast MRI alone.

KEY POINTS

• All 74 MRI-detected lesions were confirmed without using MRI-guided biopsy. • Four lesions were not visible on second breast MRI. • RVS can increase sonographic detection of lesions identified on breast MRI alone. • RVS-guided breast biopsy can be an alternative to MRI-guided biopsy.

Additional findings at preoperative breast MRI: the value of second-look digital breast tomosynthesis

OBJECTIVES

To evaluate second-look digital breast tomosynthesis (SL-DBT) for additional findings (AFs) at preoperative MRI compared with second-look ultrasound (SL-US).

METHODS

We included 135 patients with breast cancer who underwent digital mammography (DM), DBT, US, and MRI at two centres. MR images were retrospectively evaluated to find AFs, described as focus, mass, or non-mass; ≤10 mm or >10 mm in size; BI-RADS 3, 4, or 5. DM and DBT exams were reviewed looking for MRI AFs; data on SL-US were collected. Reference standard was histopathology or ≥12-month negative follow-up. Fisher exact test and McNemar test were used.

RESULTS

Eighty-four AFs were detected in 53/135 patients (39%, 95%CI 31-48%). A correlate was found for 44/84 (52%, 95%CI 41-63%) at SL-US, for 20/84 (24%, 95%CI 11-28%) at SL-DM, for 42/84 (50%, 95%CI 39-61%) at SL-DBT, for 63/84 (75%, 95%CI 64-84%) at SL-DBT, and/or SL-US, the last rate being higher than for SL-US only, overall (p < 0.001), for mass or non-mass, ≤ or >10 mm, BI-RADS 4 or 5, or malignant lesions (p < 0.031). Of 21 AFs occult at both SLs, 17 were malignant (81%, 95%CI 58-94%).

CONCLUSIONS

When adding SL-DBT to SL-US, AFs detection increased from 52% to 75%. MR-guided biopsy is needed for the remaining 25%.

KEY POINTS

• Detection rate of MRI AFs using SL-US was 52% • Adding SL-DBT, the detection rate of MRI AFs significantly increased to 75%. • Over 80% of the remaining 25% MRI AFs were malignant. • MR-guided biopsy should be used when SL-US and SL-DBT are inconclusive.

Prediction of prone-to-supine tumor displacement in the breast using patient position change: investigation with prone MRI and supine CT

BACKGROUND

One of the challenges for clinical use of preoperative breast magnetic resonance imaging (MRI) is how to transfer prone MRI information to the operating theater with a supine surgical position. The aim of this study was to retrospectively evaluate tumor displacement in the breast by changing the patient position from prone to supine (prone-to-supine tumor displacement), using preoperative prone MRI and supine computed tomography (CT).

METHODS

Preoperatively, 55 Japanese women with 57 breast cancer lesions underwent breast MRI in the prone position and breast CT in the supine position. Tumor positions in both the prone and supine positions were measured on X-, Y-, and Z-coordinates by fixing the nipple to the origin (0, 0, 0). As an indicator of the mobility of the breast, the ratio of the breast projection between the prone MRI and supine CT (prone-to-supine projection ratio) was calculated. The direction and distance of prone-to-supine tumor displacement was analyzed by dividing the breast into four quadrants according to the tumor position.

RESULTS

When changing the patient position from prone to supine, tumors located in the inner-upper and inner-lower quadrants tended to move radially toward the center of the nipple. The movement distance of the tumors in the inner-lower and outer-lower quadrants was very strongly correlated with the prone-to-supine breast projection ratio (r ≥ 0.8, p < 0.05). Conversely, in the outer-upper quadrant, the direction of tumor displacement was variable, and the distance of tumor displacement did not correlate with the prone-to-supine projection ratio.

CONCLUSIONS

The present study showed that prone-to-supine tumor displacement in the breast differs depending on tumor location. The inner-lower quadrant of the breast may be the most predictable area for prone-to-supine tumor displacement.

Second-look US: how to find breast lesions with a suspicious MR imaging appearance

Breast magnetic resonance (MR) imaging has high sensitivity in breast cancer diagnosis. The probability of malignancy for additional detected lesions is higher in patients with breast cancer than in the population without malignancy, which is why biopsy or further study should be considered for additional detected lesions. Because of the shortcomings of MR imaging-guided biopsy, second-look ultrasonography (US) may be the preferred next step. Detecting target lesions at second-look US and correlating lesions between the two modalities may be challenging. Using axial MR imaging to localize the lesion with respect to the nipple and the lesion-to-nipple distance can narrow the scan range at US. Evaluating the lesion's location relative to the mammary zones and surrounding tissues, as well as noting its depth, characteristics, and nearby landmarks, will aid in lesion correlation. Doppler imaging, tissue harmonic imaging, and other US techniques can be used to identify subtle lesions. Although malignant breast lesions may appear probably benign at second-look US, decision making for biopsy must be based primarily on MR imaging findings. In sonographically occult, MR imaging-detected lesions with suspicious MR imaging features, the probability of malignancy is much higher than 2%, and MR imaging-guided biopsy must be performed.

Real-time virtual sonography (RVS)-guided vacuum-assisted breast biopsy for lesions initially detected with breast MRI

PURPOSE

To report on our initial experiences with a new method of real-time virtual sonography (RVS)-guided 11-gauge vacuum-assisted breast biopsy for lesions that were initially detected with breast MRI.

MATERIALS AND METHODS

RVS-guided 11-gauge vacuum-assisted biopsy is performed when a lesion with suspicious characteristics is initially detected with breast MRI and is occult on mammography, sonography, and physical examination. Live sonographic images were co-registered to the previously loaded second-look spine contrast-enhanced breast MRI volume data to correlate the sonography and MR images.

RESULTS

Six lesions were examined in six consecutive patients scheduled to undergo RVS-guided 11-gauge vacuum-assisted biopsy. One patient was removed from the study because of non-visualization of the lesion in the second-look spine contrast-enhanced breast MRI. Five patients with non-mass enhancement lesions were biopsied. The lesions ranged in size from 9 to 13 mm (mean 11 mm). The average procedural time, including the sonography and MR image co-registration time, was 25 min. All biopsies resulted in tissue retrieval. One was fibroadenomatous nodules, and those of four were fibrocystic changes. There were no complications during or after the procedures.

CONCLUSION

RVS-guided 11-gauge vacuum-assisted breast biopsies provide a safe and effective method for the examination of suspicious lesions initially detected with MRI.

Magnetic resonance image-guided versus ultrasound-guided high-intensity focused ultrasound in the treatment of breast cancer

Image-guided high-intensity focused ultrasound (HIFU) has been used for more than ten years, primarily in the treatment of liver and prostate cancers. HIFU has the advantages of precise cancer ablation and excellent protection of healthy tissue. Breast cancer is a common cancer in women. HIFU therapy, in combination with other therapies, has the potential to improve both oncologic and cosmetic outcomes for breast cancer patients by providing a curative therapy that conserves mammary shape. Currently, HIFU therapy is not commonly used in breast cancer treatment, and efforts to promote the application of HIFU is expected. In this article, we compare different image-guided models for HIFU and reviewed the status, drawbacks, and potential of HIFU therapy for breast cancer.