RESUMO
OBJECTIVE: Fibrosis from chest irradiation could lower the apparent diffusion coefficient (ADC) of breast tissue. ADC values of normal breast tissue in high-risk women who underwent mantle radiation before age 30 years were compared with a screening control group matched for breast fibroglandular tissue (FGT). METHODS: In this retrospective study, we reviewed 21 women with a history of mantle radiation who underwent breast MRI examinations between 2008 and 2013, and 20 nonirradiated patients (control group) imaged during the same period with matching FGT and similar age. The women were dichotomized into low FGT (10/20, 50%) and high-FGT (10/20, 50%) groups, based on BI-RADS descriptors. All MRI examinations included diffusion-weighted imaging (DWI) (b = 0, 1000); ADC maps were generated and evaluated on PACS workstations by two radiologists in agreement. Region of interest markers were placed on ADC maps in visualized breast tissue in the retroareolar region of each breast. The ADC value was averaged for the right and left breast in each patient included in the study. The Wilcoxon signed-rank test was used to compare the ADC values in the irradiated patients and the matched control patients. RESULTS: The median breast ADC was lower in the irradiated group (1.32 × 10-3mm2/sec) than in the control group (1.62 × 10-3mm2/sec; P = 0.0089). Low FGT in the irradiated group had a lower median ADC (1.25 × 10-3mm2/sec) than it did in the control group (1.53 × 10-3mm2/sec). Irradiated high-FGT breasts had a median ADC (1.52 × 10-3mm2/sec), as compared with nonirradiated control patients with high FGT (1.82 × 10-3mm2/sec). CONCLUSION: Previously irradiated breasts have lower ADC values than do nonirradiated breasts.
RESUMO
PURPOSE: To assess the utility of screening magnetic resonance (MR) imaging in the detection of otherwise occult breast cancers in women with a history of lobular carcinoma in situ (LCIS). MATERIALS AND METHODS: This HIPAA-compliant study received institutional review board approval. The need for informed consent was waived. Retrospective review of the database yielded 670 screening breast MR studies obtained between January 2003 and September 2008 in 220 women with a history of LCIS. MR and mammographic findings were reviewed. Number of cancers diagnosed, method of detection, and tumor characteristics were examined. The cumulative incidence of developing breast cancer as detected with MR imaging and mammography was calculated. Breast density was examined as a prognostic factor in the cumulative incidence analysis. RESULTS: Biopsy was recommended in 63 lesions seen in 58 (9%) of 670 screening MR studies. Eight additional lesions were identified at short-term follow-up MR imaging for a total of 71 lesions in 59 patients. Twelve cancers (20%) were identified in 60 lesions sampled. Biopsy was recommended in 26 additional lesions identified at mammography; biopsy was performed in 25 of these lesions and revealed malignancy in five (20%). Overall, 17 cancers were detected in 14 patients during the study period. Of these, 12 were detected with MR imaging alone, and five were detected with mammography alone. Of the 12 cancers detected at MR imaging, there were nine invasive cancers and three cases of ductal carcinoma in situ (DCIS). Of the five cancers detected at mammography, two were invasive and three were DCIS. CONCLUSION: MR imaging is a useful adjunct modality with which to screen women with a history of LCIS at high-risk of developing breast cancer, resulting in a 4.5% incremental cancer detection rate. Sensitivity in the detection of breast cancers with a combination of MR imaging and mammography was higher than sensitivity of either modality alone.
