Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping as a quantitative imaging biomarker for prediction of immunohistochemical receptor status, proliferation rate, and molecular subtypes of breast cancer.

BACKGROUND: Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping is one of the most useful additional MRI parameters to improve diagnostic accuracy and is now often used in a multiparameric imaging setting for breast tumor detection and characterization. PURPOSE: To evaluate whether different ADC metrics can also be used for prediction of receptor status, proliferation rate, and molecular subtype in invasive breast cancer. STUDY TYPE: Retrospective. SUBJECTS: In all, 107 patients with invasive breast cancer met the inclusion criteria (mean age 57 years, range 32-87) and underwent multiparametric breast MRI. FIELD STRENGTH/SEQUENCE: 3 T, readout-segmented echo planar imaging (rsEPI) with IR fat suppression, dynamic contrast-enhanced (DCE) T1 -weighted imaging, T2 -weighted turbo-spin echo (TSE) with fatsat. ASSESSMENT: Two readers independently drew a region of interest on ADC maps on the whole tumor (WTu), and on its darkest part (DpTu). Minimum, mean, and maximum ADC values of both WTu and DpTu were compared for receptor status, proliferation rate, and molecular subtypes. STATISTICAL TESTS: Wilcoxon rank sum, Mann-Whitney U-tests for associations between radiologic features and histopathology; histogram and q-q plots, Shapiro-Wilk's test to assess normality, concordance correlation coefficient for precision and accuracy; receiver operating characteristics curve analysis. RESULTS: Estrogen receptor (ER) and progesterone receptor (PR) status had significantly different ADC values for both readers. Maximum WTu (P = 0.0004 and 0.0005) and mean WTu (P = 0.0101 and 0.0136) were significantly lower for ER-positive tumors, while PR-positive tumors had significantly lower maximum WTu values (P = 0.0089 and 0.0047). Maximum WTu ADC was the only metric that was significantly different for molecular subtypes for both readers (P = 0.0100 and 0.0132) and enabled differentiation of luminal tumors from nonluminal (P = 0.0068 and 0.0069) with an area under the curve of 0.685 for both readers. DATA CONCLUSION: Maximum WTu ADC values may be used to differentiate luminal from other molecular subtypes of breast cancer. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:836-846.

Abbreviated MRI of the Breast: Does It Provide Value?

MRI of the breast is the most sensitive test for breast cancer detection and outperforms conventional imaging with mammography, digital breast tomosynthesis, or ultrasound. However, the long scan time and relatively high costs limit its widespread use. Hence, it is currently only routinely implemented in the screening of women at an increased risk of breast cancer. To overcome these limitations, abbreviated dynamic contrast-enhanced (DCE)-MRI protocols have been introduced that substantially shorten image acquisition and interpretation time while maintaining a high diagnostic accuracy. Efforts to develop abbreviated MRI protocols reflect the increasing scrutiny of the disproportionate contribution of radiology to the rising overall healthcare expenditures. Healthcare policy makers are now focusing on curbing the use of advanced imaging examinations such as MRI while continuing to promote the quality and appropriateness of imaging. An important cornerstone of value-based healthcare defines value as the patient's outcome over costs. Therefore, the concept of a fast, abbreviated MRI exam is very appealing, given its high diagnostic accuracy coupled with the possibility of a marked reduction in the cost of an MRI examination. Given recent concerns about gadolinium-based contrast agents, unenhanced MRI techniques such as diffusion-weighted imaging (DWI) are also being investigated for breast cancer diagnosis. Although further larger prospective studies, standardized imaging protocol, and reproducibility studies are necessary, initial results with abbreviated MRI protocols suggest that it seems feasible to offer screening breast DCE-MRI to a broader population. This article aims to give an overview of abbreviated and fast breast MRI protocols, their utility for breast cancer detection, and their emerging role in the new value-based healthcare paradigm that has replaced the fee-for-service model. Level of Evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:e85-e100.

MRI-based quantification of residual fibroglandular tissue of the breast after conservative mastectomies.

PURPOSE: Skin-sparing and nipple-sparing mastectomies (SSM; NSM) remove the breast's fibroglandular tissue (FGT), thereby reducing breast cancer risk. The postoperative presence of residual FGT (RFGT) is associated with remaining cancer risk. This study evaluated the role of MRI in the quantitative assessment of RFGT and its impact on the estimation of the remaining breast cancer risk. METHODS: The postoperative MRI scans (following EUSOMA recommendations) of 58 patients who had undergone SSM or NSM between 2003 and 2013, as well as preoperative MRI scans that were available in 25 of these patients, were retrospectively evaluated for the presence and location of RFGT by three radiologists. Two different observers quantitatively assessed the volume and percentage of retromamillary and other RFGT (RFGTrm and RFGTother) were assessed. The Fisher's exact test, the Student's t-test, and intraclass coherence were used to compare patient groups and to assess reproducibility. RESULTS: RFGT was found in 20% of all breasts and significantly more frequently after NSM than SSM (50% vs. 13%, p = .003). RFGTrm and RFGTother were more prevalent after NSM (p < 0.001; p = .127). RFGT ranged from 0.5 to 26% of the preoperative FGT, with higher percentages after NSM than SSM (p = .181). CONCLUSIONS: The prevalence and percentage of RFGT found on MRI indicate a considerable remaining postoperative breast cancer risk in some women.

Management of atypical lobular hyperplasia, atypical ductal hyperplasia, and lobular carcinoma in situ.

Atypical hyperplasia and lobular carcinoma in situ are rare proliferative breast lesions, growing inside ducts and terminal ducto-lobular units. They represent a marker of increased risk for breast cancer and a non-obligate precursor of malignancy. Evidence available on diagnosis and management is scarce. They are frequently found incidentally associated with other lesions, but can be visible through mammography, ultrasound or magnetic resonance. Due to the risk of underestimation, surgical excision is often performed. The analysis of imaging and histopathological characteristics could help identifying low-risk cases, for which surgery is not necessary. Chemopreventive agents can be used for risk reduction. Careful imaging follow up is mandatory; the role of breast MRI as screening modality is under discussion.

The hydrolipidic ratio in age-related maturation of adipose tissues.

The hydrolipidic ratio (HLR) expresses the amount of water and fat in a tissue. HLR can be studied non-invasively in the living organism and can be mapped in different areas of the body with high spatial and temporal resolution. In the present work we have evaluated the HLR in different adipose tissue depots in young or adult rats using tissue arrays of fat fragments by 1H-spectroscopy. In young animals, the highest percentage of water (33%) was found in the interscapular brown adipose tissue (iBAT). Mesenteric fat (mWAT) also appeared highly hydrated (24%). The deposits composed of epididymal, retroperitoneal and pelvic white adipose tissue (eWAT, rWAT and pWAT, respectively) contained an amount of water ranging from 14% to 17%. In adult animals, a reduction of the water content was found in all the depots. In e/r/pWAT, the age-related maturation was characterized by large changes in adipocyte diameter accompanied by a small change in HLR. In the iBAT, the maturation was accompanied by small change in adipocyte diameter and a greater diminution of HLR. mWAT showed an intermediate pattern between e/r/pWAT and iBAT. In all the studied depots, an age-related increase in leptin expression was found. This increase was relatively low in iBAT (40%) and high in the e/r/pWAT (204-273%). The work expand the knowledge about the physiological significance of the HLR by 1H-spectroscopy.