Otso Arponen, Presenter: Nothing to Disclose

Amro Masarwah MD, Abstract Co-Author: Nothing to Disclose

Mikko Tapani Taina, Abstract Co-Author: Nothing to Disclose

Suvi Hanne Katriina Rautiainen MD, Abstract Co-Author: Nothing to Disclose

Mervi Kononen MSc, Abstract Co-Author: Nothing to Disclose

Reijo Sironen, Abstract Co-Author: Nothing to Disclose

Masah Sudah, Abstract Co-Author: Nothing to Disclose

Anna Sutela, Abstract Co-Author: Nothing to Disclose

Juhana Hakumaki, Abstract Co-Author: Nothing to Disclose

Ritva Liisa Vanninen MD, Abstract Co-Author: Nothing to Disclose

We compared measurements of apparent diffusion coefficient (ADC) within the whole breast tumor vs. a small intratumoral region of interest (ROI) to differentiate malignant from benign tumors and assessed whether the ADC parameters represent surrogate markers for tumor prognostic characteristics.

Approval of the institutional ethics board and institutional approval were obtained. The study protocol included 3.0T structural breast MRI and diffusion weighted imaging (DWI). Patients were selected according to the recommendations of EUSOMA and the local guidelines. Forty-nine patients (mean age, 59±12 years; range, 36−82 years) and 49 lesions (17 benign, 32 malignant) were included to this prospective study. Two observers measured the ADC values (mean, standard deviation, kurtosis and skewness) from a) the whole lesion (WL-ROI), avoiding cystic, hemorrhagic and necrotic regions b) six small intratumoral ROIs (SI-ROIs) with lowest-appearing values on ADC map. WL-ROI and SI-ROI with second-lowermost mean value were used for statistical analysis. Data on estrogen and progesterone receptors, HER2-overexpression, tumor grade, Ki-67, vascular and lymph duct invasion and metastasis to axillary lymph nodes were collected.

Using SI-ROI ADC mean values, reproducibility of the measurements proved to be excellent (κ=0.75; Intra-Class Correlation Coefficient, 0.904). In receiver operating characteristic curve analysis, area under the curve was 0.891 for observer 1 and 0.881 for observer 2. Using cut-off value of 0.602×10-3 mm2/s, sensitivity of 82.4%, specificity of 87.5% and overall accuracy (OA) of 85.7% were reached for diagnosing malignant lesions. ADC measurements from SI-ROIs proved to be more accurate than WL-ROIs (OA=67.3%, P<0.05). SI-ROI ADC values inversely correlated to the presence of axillary metastases (P=0.008), and to vascular invasion (P=0.003). There was no independent correlation between ADC values and tumor grade, estrogen, progesterone, HER2 or Ki-67 expression.

Measuring ADC values from a small intratumoral ROI is clinically more accurate than using the whole tumor ROI in assessment of breast tumors in 3.0T MRI and may help in tumor characterization.

When evaluating breast tumor MRIs, ADC measurements should be targeted to most suspicious subregion instead of the whole tumor.

Arponen, O, Masarwah, A, Taina, M, Rautiainen, S, Kononen, M, Sironen, R, Sudah, M, Sutela, A, Hakumaki, J, Vanninen, R, 3.0 Tesla Breast MRI: Analysis of Apparent Diffusion Coefficient with a Small Intratumoral ROI Improves Diagnostic Performance and Tumor Characterization.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14018650.html