RESUMO
PURPOSE: A method and computer tool to estimate percentage magnetic resonance (MR) imaging (MRI) breast density using three-dimensional T(1)-weighted MRI is introduced, and compared with mammographic percentage density [X-ray mammography (XRM)]. MATERIALS AND METHODS: Ethical approval and informed consent were obtained. A method to assess MRI breast density as percentage volume occupied by water-containing tissue on three-dimensional T(1)-weighted MR images is described and applied in a pilot study to 138 subjects who were imaged by both MRI and XRM during the Magnetic Resonance Imaging in Breast Screening study. For comparison, percentage mammographic density was measured from matching XRMs as a ratio of dense to total projection areas scored visually using a 21-point score and measured by applying a two-dimensional interactive program (CUMULUS). The MRI and XRM percent methods were compared, including assessment of left-right and interreader consistency. RESULTS: Percent MRI density correlated strongly (r = 0.78; P < 0.0001) with percent mammographic density estimated using Cumulus. Comparison with visual assessment also showed a strong correlation. The mammographic methods overestimate density compared with MRI volumetric assessment by a factor approaching 2. DISCUSSION: MRI provides direct three-dimensional measurement of the proportion of water-based tissue in the breast. It correlates well with visual and computerized percent mammographic density measurements. This method may have direct application in women having breast cancer screening by breast MRI and may aid in determination of risk.
Assuntos
Neoplasias da Mama/patologia , Imageamento Tridimensional , Imageamento por Ressonância Magnética/métodos , Adulto , Composição Corporal , Neoplasias da Mama/diagnóstico por imagem , Feminino , Humanos , Interpretação de Imagem Assistida por Computador , Mamografia , Pessoa de Meia-Idade , Projetos PilotoRESUMO
INTRODUCTION: A UK multicenter study compared the performance of contrast enhanced-magnetic resonance imaging with X-Ray Mammography in women at high-risk of breast cancer commencing in 1997. Selection criteria were used to identify women with at least 0.9% annual risk of breast cancer. METHODS: Women at high breast cancer risk, with a strong family history and/or high probability of a BRCA1/BRCA2/TP53 mutation, were recruited from 22 centers. Those not known as gene carriers were asked to give a blood sample, which was tested anonymously for mutations. Women ages 35 to 49 years were offered annual screening for 2 to 7 years. Study eligibility at entry was assessed retrospectively by detailed examination of pedigrees and overall eligibility accounting for computer risk assessment and mutation results. RESULTS: Seventy-eight of 837 (9%) women entered for screening were ineligible using the strict entry criteria. Thirty-nine cancers were detected in 1,869 women-years in study (incidence 21 per 1,000). Including 3,561 further years follow-up, 28 more breast cancers were identified (12 of 1,000). Incidence rates for 759 eligible women were 22 of 1,000 in study and 13 of 1,000 in total follow-up, compared with 9 of 1,000 and 4 of 1,000, respectively, in 78 ineligible women. Breast cancer rates were higher for BRCA2 than BRCA1 after testing anonymized samples in this selected population at 65 of 1,000 in study and 36 of 1,000 in total follow-up for BRCA2 compared with 44 of 1,000 and 27 of 1,000 for BRCA1. CONCLUSIONS: Strict enforcement of study criteria would have minimally improved the power of the study, whereas testing for BRCA1/2 in advance would have substantially increased the detection rates.
Assuntos
Testes Anônimos/métodos , Neoplasias da Mama/diagnóstico , Testes Genéticos/métodos , Seleção de Pacientes , Adulto , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/genética , Meios de Contraste , DNA/genética , Feminino , Genes BRCA1 , Genes BRCA2 , Genes p53 , Predisposição Genética para Doença , Humanos , Incidência , Imageamento por Ressonância Magnética/métodos , Mamografia , Pessoa de Meia-Idade , Linhagem , Vigilância da População/métodos , Estudos Retrospectivos , Fatores de Risco , Reino Unido/epidemiologiaRESUMO
PURPOSE: To evaluate prospectively the accuracy of a lesion classification system designed for use in a magnetic resonance (MR) imaging high-breast-cancer-risk screening study. MATERIALS AND METHODS: All participating patients provided written informed consent. Ethics committee approval was obtained. The results of 1541 contrast material-enhanced breast MR imaging examinations were analyzed; 1441 screening examinations were performed in 638 women aged 24-51 years at high risk for breast cancer, and 100 examinations were performed in 100 women aged 23-81 years. Lesion analysis was performed in 991 breasts, which were divided into design (491 breasts) and testing (500 breasts) sets. The reference standard was histologic analysis of biopsy samples, fine-needle aspiration cytology, or minimal follow-up of 24 months. The scoring system involved the use of five features: morphology (MOR), pattern of enhancement (POE), percentage of maximal focal enhancement (PMFE), maximal signal intensity-time ratio (MITR), and pattern of contrast material washout (POCW). The system was evaluated by means of (a) assessment of interreader agreement, as expressed in kappa statistics, for 315 breasts in which both readers analyzed the same lesion, (b) assessment of the diagnostic accuracy of the scored components with receiver operating characteristic curve analysis, and (c) logistic regression analysis to determine which components of the scoring system were critical to the final score. A new simplified scoring system developed with the design set was applied to the testing set. RESULTS: There was moderate reader agreement regarding overall lesion outcome (ie, malignant, suspicious, or benign) (kappa=0.58) and less agreement regarding the scored components. The area under the receiver operating characteristic curve (AUC) for the overall lesion score, 0.88, was higher than the AUC for any one component. The components MOR, POE, and POCW yielded the best overall result. PMFE and MITR did not contribute to diagnostic utility. Applying a simplified scoring system to the testing set yielded a nonsignificantly (P=.2) higher AUC than did applying the original scoring system (sensitivity, 84%; specificity, 86.0%). CONCLUSION: Good diagnostic accuracy can be achieved by using simple qualitative descriptors of lesion enhancement, including POCW. In the context of screening, quantitative enhancement parameters appear to be less useful for lesion characterization.