Quantitative Assessment of Breast Parenchymal Uptake on ¹⁸F-FDG PET/CT: Correlation with Age, Background Parenchymal Enhancement, and Amount of Fibroglandular Tissue on MRI

Abstract

Background parenchymal enhancement (BPE), and the amount of fibroglandular tissue (FGT) assessed with MRI have been implicated as sensitive imaging biomarkers for breast cancer. The purpose of this study was to quantitatively assess breast parenchymal uptake (BPU) on 18 F-FDG PET/CT as another valuable imaging biomarker and examine its correlation with BPE, FGT, and age. Methods: This study included 129 patients with suspected breast cancer and normal imaging findings in one breast (BI-RADS 1), whose cases were retrospectively analyzed. All patients underwent prone 18 F-FDG PET/CT and 3-T contrast-enhanced MRI of the breast. In all patients, interpreter 1 assessed BPU quantitatively using SUV max . Interpreters 1 and 2 assessed amount of FGT and BPE in the normal contralateral breast by subjective visual estimation, as recommended by BI-RADS. Interpreter 1 reassessed all cases and repeated the BPU measurements. Statistical tests were used to assess correlations between BPU, BPE, FGT, and age, as well as inter-and intrainterpreter agreement. Results: BPU on 18 F-FDG PET/CT varied among patients. The mean BPU SUV max ± SD was 1.57 ± 0.6 for patients with minimal BPE, 1.93 ± 0.6 for mild BPE, 2.42 ± 0.5 for moderate BPE, and 1.45 ± 0.3 for marked BPE. There were significant (P , 0.001) moderate to strong correlations among BPU, BPE, and FGT. BPU directly correlated with both BPE and FGT on MRI. Patient age showed a moderate to strong indirect correlation with all 3 imaging-derived tissue biomarkers. The coefficient of variation for quantitative BPU measurements with SUV max was 5.6%, indicating a high reproducibility. Interinterpreter and intrainterpreter agreement for BPE and FGT was almost perfect, with a κ-value of 0.860 and 0.822, respectively. Conclusion: The results of our study demonstrate that BPU varied among patients. BPU directly correlated with both BPE and FGT on MRI, and BPU measurements were highly reproducible. Patient age showed a strong inverse correlation with all 3 imaging-derived tissue biomarkers. These findings indicate that BPU may serve as a sensitive imaging biomarker for breast cancer prediction, prognosis, and risk assessment.

Does breast MRI background parenchymal enhancement indicate metabolic activity? Qualitative and 3D quantitative computer imaging analysis

“…While many studies have explored the importance of BPU in diagnosing, staging, and following treatment therapy in breast cancer, one previously published study examined the relationship between BPU and BPE. In that study, Leithner et al found a correlation between BPU and qualitative measurements of MRI BPE. Similarly, in our study we show a correlation between qualitative assessment of BPE and BPU.…”

“…Thus far, what MRI BPE really represents has not been clearly delineated. Possible increased metabolic activity was proposed by Pike and Pearce and recently shown in a single study by Leithner et al In their study, they utilized only qualitative BPE data to correlate with BPU, which can be prone to both inter‐ and intrareader variability. The purpose of this study was to use more objective 3D quantitative measurements of BPE, in addition to qualitative BPE measurement to confirm the association of BPE and BPU.…”

Multiparametric 18F-FDG PET/MRI of the Breast: Are There Differences in Imaging Biomarkers of Contralateral Healthy Tissue Between Patients With and Without Breast Cancer?

“…To our knowledge, this is the first study using 18 F-FDG PET to examine patients with benign and malignant tumors for differences in BPU of the contralateral tumor-free breast. In contrast to both BPE and FGT, which are usually assessed through subjective visual estimation, BPU can be easily quantified, is highly reproducible (17,27,28), and therefore may serve as a more stable, noninvasive imaging biomarker. In a recent study that assessed the correlation and reproducibility of quantitatively measured BPU with qualitatively evaluated BPE and FGT as well as age, there were significant direct correlations between BPU and BPE, and between BPU and FGT, of the healthy contralateral breast (17), with almost perfect inter-and intrarater agreement for all parameters.…”

“…Thus, 141 patients (140 female; mean age, 57 6 14.3 y; range, 18-86 y) with a tumor-free contralateral breast on mammography, ultrasound, MRI, and 18 F-FDG PET/MRI (BI-RADS 1) were included in this retrospective analysis. Several patients have been previously analyzed and reported in a different context (17,19,22).…”

“…Like MRI, PET using the radiotracer 18 F-FDG provides information on tissue glucose metabolism and, hence, the physiologic activity of breast parenchyma (17). FGT shows varying degrees of 18 F-FDG uptake, that is, breast parenchymal uptake (BPU), which correlates with both BPE and FGT (17,18) and therefore might also serve as another important imaging biomarker in breast cancer.…”