Classification of Abnormal Findings on Ring-type Dedicated Breast PET for the Detection of Breast Cancer

Abstract

Aim: To investigate the usefulness of classification of ring-type dedicated breast positron-emission tomography (dbPET) findings in detection of breast cancer. Patients and Methods: A total of 709 patients with breast cancer underwent dbPET before treatment. Each finding was morphologically categorized as a focus (uptake size ≤5 mm), mass (>5 mm), or non-mass (multiple uptakes not belonging to a three-dimensional mass or without distinct mass features). Non-mass uptakes were additionally classified as linear, focal, segmental, regional, or diffuse distributions. Lesion-to-background ratios were calculated. Results: Among 910 abnormal findings, 700 (76.9%) were malignant and 210 (23.1%) were benign. Morphologically, 198 (21.8%) lesions were foci, 431 (47.4%) were masses, and 281 (30.9%) were non-masses. In multivariate analysis, mass, focal and segmental distributions of nonmass lesions and high lesion-to-background ratio were significantly related to breast cancer (all p<0.001). Conclusion: Classification of abnormal findings on dbPET using morphology and lesion-to-background ratio were useful to detect breast cancer.Breast cancer is the most common cancer among adult women worldwide, comprising 30% of all cancer in women (1). Breast cancer screening reduces breast cancer mortality and early-stage detection leads to a favorable prognosis (2). Positron-emission tomography (PET)/computed tomography (CT) using 18 F-fluorodeoxyglucose (FDG) is a molecular approach used for cancer imaging and performed for cancer screening, staging and monitoring of treatment response, as well as predicting prognosis in breast cancer medicine. However, due to the limited spatial resolution of whole-body PET/CT, it is hard to detect small breast cancers. Dedicated breast PET (dbPET) was developed for high-resolution molecular breast imaging to detect sub-centimeter breast cancers. dbPET has two scanner types: opposite and ring (3). Both types improve the sensitivity for breast cancer detection compared to that of whole-body PET (4, 5). In addition, ring-type dbPET can be used to calculate the standardized uptake value (SUV) by obtaining three-dimensional images as well as attenuation and scatter correction, unlike oppositetype dbPET (6).In mammography, ultrasonography (US), and magnetic resonance imaging (MRI), category classifications of abnormal findings, such as the Breast Imaging Reporting and Data System (BI-RADS) (7), have been developed to standardize and optimize the management of breast lesions. Categorization according to BI-RADS enables radiologists to estimate the probability of breast cancer in breast abnormalities. However, no diagnostic classifications yet exist for dbPET as a new breast imaging tool. Currently, dbPET is performed for breast cancer screening, preoperative assessment, and evaluation of therapeutic effect in breast cancer medicine simultaneously with whole-body PET (4, 8). Especially in cancer screening, category classification of dbPET is required. Because dbPET is a functional imaging modality rather t...

A Proposed Dedicated Breast PET Lexicon: Standardization of Description and Reporting of Radiotracer Uptake in the Breast

“…Satoh et al found that mass uptake was significantly associated with malignancy compared to focus in 40 unexpected uptake lesions in 35 patients [ 13 ]. Sasada et al showed that mass and focal/segmental non-mass lesions were significantly associated with breast cancer among 910 abnormal findings in 709 patients with breast cancer [ 14 ]. Masumoto et al reported that heterogeneity in tumor uptake was associated with higher nuclear grade and higher Ki67 in breast cancers [ 15 ].…”

“…In 2011, Narayanan et al first reported the value of feature analysis of breast uptake using PEM with 18 F-fluorodeoxyglucose ( 18 F-FDG), and demonstrated morphological uptake features of additional lesions in patients with breast cancer were significant predictors of malignancy [ 12 ]. In recent years, there have been several reports that suggest the usefulness of breast lesion morphological assessment using a ring-type dbPET with 18 F-FDG [ 13 , 14 , 15 , 16 ]. However, to establish and facilitate a comprehensive approach of breast cancer diagnosis using dbPET, there is now a critical need to standardize reporting and descriptors of uptake features.…”