Role of SUV and ADC values as a predictors of grade and molecular subtypes of breast malignancy

The purpose of the study is to evaluate the role of Standardized Uptake Value (SUV) and Apparent Diffusion Coefficient (ADC) values as a predictor of histologic grade and molecular subtype of breast malignancy and to evaluate the correlation of grade of malignancy with background parenchymal uptake, background parenchymal enhancement and fibroglandular tissue of the contralateral normal breast 53 patients with unilateral breast cancer were included in the study. Images from Computed Tomography (CT) and Positron Emission Tomography (PET) were analyzed measuring maximum SUV and background SUV from the contralateral normal breast by placing a single Region of interest (ROI). From Diffusion-weighted magnetic resonance imaging (DWI-MRI) images ADC values were calculated with b value 0–1200 s/mm2 and single ROI placed in an area corresponding to the ROI placed to obtain maximum SUV of the mass. Type of fibroglandular tissue and background parenchymal enhancement was categorized based on Breast Imaging-Reporting and Data System (BI-RADS)–lexicon on T1 weighted and Dynamic Contrast-Enhanced (DCE) images respectively. Necrotic and hemorrhagic areas within the mass were excluded in both positron emission tomography–computed tomography (PET-CT) and Magnetic resonance imaging (MRI) while calculating SUV and ADC. A positive correlation was found between grade and Mean SUVmax with higher values in grade 3 malignancy (11.41 ± 4.76) (p-value – 0.003). Statistically significant variation in SUVmax was seen among estrogen receptor/progesterone receptor (ER/PR) status with low values in ER/PR positive tumors (p-value < 0.05). There was significant correlation between the molecular subtypes with higher SUVmax in triple-negative tumors (12.27 ± 4.22) (p-value – 0.02). Significant variation in ADC values among different molecular subtypes was seen with higher values in human epidermal growth factor receptor (HER2)-Enriched tumors (1.032 ± 0.25) and low values in luminal A subtype (0.798 ± 0.13). Therefore, PET-CT and MRI can be used as a complementary imaging tool in assessing the aggressiveness and biological characteristics of tumors.