Gadoteridol-enhanced MRI of the breast: can contrast agent injection rate impact background parenchymal enhancement?

BACKGROUND: Normal background parenchymal enhancement (BPE) is a dynamic parameter affected by multiple factors. PURPOSE: To determine whether contrast agent injection rate affects the degree of BPE in women undergoing breast magnetic resonance imaging (MRI). MATERIAL AND METHODS: A total of 85 patients included in our prospective study randomly received 0.1 mmol/kg gadoteridol at a rate of 3 mL/s (group A; n = 46) or 2 mL/s (group B; n = 39). Breast MRI was performed at 3T using a standard protocol including postcontrast axial 3D GRE T1-weighted sequences. Two expert breast radiologists, blinded to clinical and radiological information, independently quantified BPE on early postcontrast subtracted images, assigning a score of 1-4. Mean comparison and regression analysis were performed to assess the influence of injection rate on BPE. RESULTS: Groups were homogeneous in terms of age and final BI-RADS score. The mean BPE score was significantly lower among patients in group A (mean of two readers: 1.36 vs. 1.90; P < 0.01) with 70%-72% of patients assigned a BPE score of 1, compared with 36%-38% of patients in group B. Lower BPE scores were noted with the higher flow rate in subgroup analyses of both pre- and postmenopausal women, although the effect was more evident in premenopausal women. Regression analysis confirmed that the likelihood of a BPE 1 score was significantly increased with a higher flow rate (P < 0.01). The inter-reader agreement was excellent (0.83). CONCLUSION: A higher contrast agent injection flow rate (3 mL/s) during breast MRI significantly reduces the degree of BPE, potentially allowing improved diagnostic accuracy by reducing false-positive and false-negative findings.

Peritumoral edema as a biomarker of the aggressiveness of breast cancer: results of a retrospective study on a 3 T scanner.

PURPOSE: To determine whether there is a correlation between the presence of peritumoral edema detected on T2-weighted sequences and pathological prognostic factors and specific biological subtypes of breast cancer. METHODS: A retrospective study on 120 women with invasive breast cancer, who underwent breast MRI on a 3 T scanner over a period of 12 months, was performed. Peritumoral edema was assessed visually by two breast radiologist in consensus and patients were consequently divided into two groups. For each lesion dimensions, histology and molecular profiling were evaluated. The comparison between the two groups was performed using the χ2 test, subsequently carrying out a univariate and a multivariate logistic regression analysis. RESULTS: 41 (34.2%) invasive breast cancers with perilesional edema and 79 (65.8%) without edema were identified. A significant association between the presence of perilesional edema and a larger lesion size (p = 0.0001), grade 3 (p < 0.001) and a higher Ki-67 index (p < 0.001) was found. The multivariate analysis confirmed that a larger tumor size is independently associated with peritumoral edema. A total of 101 (84.2%) luminal-like, 8 (6.7%) HER2-positive, and 11 (9.2%) triple-negative tumors were included in the study. Peritumoral edema turned out to be less frequently associated with luminal-like lesions (p < 0.001), while the luminal A status was found to have a significant association with the absence of peritumoral edema in the univariate analysis. CONCLUSION: The detection of peritumoral edema on T2-weighted sequences should be considered as a valid additional prognostic tool in the evaluation of breast cancer, since it is associated with biologically aggressive non-luminal breast cancers, characterized by large dimension, high tumor grade, and high Ki-67 values.

MRI-guided treatment in the breast.

In the last decades, an increasing interest has developed towards non-invasive breast lesion treatments, which offer advantages such as the lack of surgery-related complications, better cosmetic outcomes, and less psychological distress. In addition, these treatments could be an option for patients with poor health who are not candidates for surgery. Non-surgical ablation can be performed under magnetic resonance (MR) or ultrasound (US) guidance. US is cheaper and easily available, while contrast-enhanced MR is more accurate, ensuring better safety and efficacy for the patient. Overall results of studies about MRI-guided tumor ablation reported complete ablation rates ranging between 20% and 100%. High-intensity focused ultrasound (HIFU or FUS) is the most studied ablative technique and it is already established as a valid technique for ablation of benign and malignant tumors in various organs. Ultrasound-guided FUS is very useful for young patients who refuse surgery or with multiple nodules; however, MR-guided FUS is more sensitive and allows a better evaluation of thermal accumulation within the ablated tissue or the adjacent structures. Most MR-guided FUS studies used a dedicated high-field MR scanner and complete tumor ablation was reported in 17-90% of cases. Other techniques using thermal tissue destruction are radiofrequency ablation (RFA) and laser interstitial thermal therapy (LITT). Only a few studies assessed the efficacy of these treatments, all were performed with open MR devices. RFA showed complete tumor ablation in 30-96% of patients, while LITT in 10-71%, but all the studies had a small number of patients. Cryoablation obtains tissue ablation by a rapid decrease of temperature, with a complete tumor removal reported in 18-52% of cases with MR guidance. No serious complications were reported with these techniques. Currently, breast conservative surgery replaced radical surgery when possible. Therefore, future research should focus on these treatments to shift towards an even less invasive approach to breast neoplasms. Level of Evidence: 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2018;48:1479-1488.

Added Value of Digital Breast Tomosynthesis Combined with Digital Mammography According to Reader Agreement: Changes in BI-RADS Rate and Follow-Up Management.

BACKGROUND: The aim of this study was to evaluate the added value of digital breast tomosynthesis (DBT) when combined with digital mammography (DM) in BI-RADS assessment and follow-up management. METHODS: From February 2014 to January 2015, 214 patients underwent DM and DBT, acquired with a Siemens Mammomat Inspiration unit. 2 expert readers independently reviewed the studies in 2 steps: DM and DM+DBT, according to BI-RADS rate. Patients with BI-RADS 0, 3, 4, and 5 were recalled for work-up. Inter-reader agreement for BI-RADS rate and work-up rate were evaluated using Cohen's kappa. RESULTS: Inter-reader agreement (κ value) for BI-RADS classification was 0.58 for DM and 0.8 for DM+DBT. DM+DBT increased the number of BI-RADS 1, 2, 4, 5 and reduced the number of BI-RADS 0 and 3 for both readers compared to DM alone. Regarding work-up rate agreement, κ was poor for DM and substantial (0.7) for DM+DBT. DM+DBT also reduced the work-up rate for both Reader 1 and Reader 2. CONCLUSION: DM+DBT increased the number of negative and benign cases (BI-RADS 1 and 2) and suspicious and malignant cases (BI-RADS 4 and 5), while it reduced the number of BI-RADS 0 and 3. DM+DBT also improved inter-reader agreement and reduced the overall recall for additional imaging or short-interval follow-up.