Diffusion-Weighted Magnetic Resonance Imaging of Patients with Breast Cancer Following Neoadjuvant Chemotherapy Provides Early Prediction of Pathological Response - A Prospective Study.

The purpose of this study was to evaluate the capacity of diffusion-weighted magnetic resonance imaging (DW-MRI) for early prediction of pathological response in breast cancer patients undergoing neoadjuvant chemotherapy (NCT). This prospective unicentric study evaluated 62 patients who underwent NCT. MRI was performed prior to the start of treatment (MR1), after the first NCT cycle (MR2), and upon completion of NCT (MR3). Pathological response was used as the gold-standard. Patients' median age was 45.5 years and the median tumor size was 40 mm. Twenty-four (38.7%) tumors presented complete pathological response (pCR). The percent increase in apparent diffusion coefficient (ADC) value between MR1 and MR2 was higher in the pCR group (p < 0.001). When the minimum increase in ADC between MR1 and MR2 was set at 25%, sensitivity was 83%, specificity was 84%, positive predictive value was 77%, negative predictive value was 89%, and accuracy was 84% for an early prediction of pCR to NCT. Meanwhile, there were no significant changes in major tumor dimensions between MR1 and MR2. In conclusion, an increase in ADC after the first cycle of NCT correlates well with pCR after the chemotherapy in our cohort, precedes reduction in tumor size on conventional MRI, and may therefore be used as an early predictor of treatment response.

Role of MRI in the staging of breast cancer patients: does histological type and molecular subtype matter?

OBJECTIVE: To assess the role of MRI in the pre-operative staging of patients with different histological types and molecular subtypes of breast cancer, by the assessment of the dimensions of the main tumour and identification of multifocal and/or multicentric disease. METHODS: The study included 160 females diagnosed with breast cancer who underwent breast MRI for pre-operative staging. The size of the primary tumour evaluated by MRI was compared with the pathology (gold standard) using the Pearson's correlation coefficient (r). The presence of multifocal and/or multicentric disease was also evaluated. RESULTS: The mean age of patients was 52.6 years (range 30-81 years). Correlation between the largest dimension of the main tumour measured by MRI and pathology was worse for non-special type/invasive ductal carcinoma than for other histological types and was better for luminal A and triple-negative than for luminal B and Her-2 molecular subtypes. Multifocal and/or multicentric disease was present in 48 patients (30.0%), and it was more common in breast carcinomas classified as Her-2 molecular subtype. There was no statistically significant difference in the frequency of multifocal and/or multicentric tumours identified only by MRI in relation to histological type or molecular subtype. CONCLUSION: The results of this retrospective study demonstrated that histological types and molecular subtypes might influence the MRI assessment of breast cancers, especially in the evaluation of tumour size. ADVANCES IN KNOWLEDGE: The real benefit of MRI for treatment planning in patients with breast cancer may be different according to the histological type and molecular subtype.

Expert witnesses: neuroradiologists' perspectives.

PURPOSE: Physician malpractice expert witnesses may testify on behalf of physicians or patients. The goal of the study was to assess the experience of neuroradiologists as expert witnesses and their attitudes about such testimony. METHODS: A survey was distributed to the 4,357 e-mail addresses of the members of the American Society of Neuroradiology with questions about expert witnesses. RESULTS: The survey found that 1,301 of 4,357 answered at least one survey question. Five hundred twenty seven of 1194 (44.1%) of respondents had experience as expert witnesses. Most offer to testify on behalf of both plaintiffs and defendant physicians (324 of 465; 69.7%). Some do not testify/review cases on behalf of a plaintiff because they do not think that physicians should testify against other physicians, even if negligence is a factor (40 of 198; 20.2%). This reason was the most common for not agreeing to be an expert witness for a plaintiff, for all age groups. Of those expressing an opinion, 312 of 874 (35.7%) of neuroradiologists feel negatively about expert witnesses, whereas 434 of 874 (49.6%) say they serve a purpose, and 105 of 874 (12.0%) feel they should be commended for their work on behalf of the justice system. CONCLUSIONS: Of neuroradiologists answering the survey, nearly half have served as expert witnesses, and most feel comfortable testifying for both plaintiffs and defendants. Substantive negative perceptions (35.7%) of expert witnesses were found.