Potential Clinical Applications of 18F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Mammography in Breast Cancer

Investigation of Added Value of Imaging Performed in a Prone Position to Standard 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Imaging for Staging in Patients with Breast Cancer

Objectives:

To investigate whether additional imaging in a prone position has any value to the supine whole-body ¹⁸fluorine-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) images by comparing the visual and quantitative data about a local disease in the breast and axilla for the initial staging of breast cancer (BC).

Methods:

In this study, a total of 91 female patients with the BC were studied. Both the supine and prone images were examined based on the axial diameter, number and location of the primary tumor, local invasion signs of the tumor, the number of axillary lymph nodes with a suspected metastasis, metabolic parameters of the primary tumor and axillary lymph nodes, and registration artifacts of the PET and CT images were evaluated individually. These findings were compared with the histopathological data obtained after a surgery.

Results:

In the evaluation of a supine and prone imaging, tumor diameter and metabolic tumor volume (MTV) values of the breast lesions were greater in the supine position than in the prone position. However, there was no significant difference found between the other metabolic parameters of a primary tumor and axilla in both positions. In the supine and prone images, accuracy for skin involvement was 84% and 91.3%, respectively.

Conclusion:

In our study, we observed that, obtaining additional images in the prone position does not significantly benefit the evaluation of a local disease. The average values of the primary tumor diameter and MTV in the prone position appear to be smaller than the one in the supine position. However, the prone imaging in the patients with a newly diagnosed BC may be beneficial in selected patients and may contribute to preventing the false-positive results especially in patients with a suspected skin involvement.

[89Zr]-Pertuzumab PET Imaging Reveals Paclitaxel Treatment Efficacy Is Positively Correlated with HER2 Expression in Human Breast Cancer Xenograft Mouse Models

Paclitaxel (PTX) treatment efficacy varies in breast cancer, yet the underlying mechanism for variable response remains unclear. This study evaluates whether human epidermal growth factor receptor 2 (HER2) expression level utilizing advanced molecular positron emission tomography (PET) imaging is correlated with PTX treatment efficacy in preclinical mouse models of HER2+ breast cancer. HER2 positive (BT474, MDA-MB-361), or HER2 negative (MDA-MB-231) breast cancer cells were subcutaneously injected into athymic nude mice and PTX (15 mg/kg) was administrated. In vivo HER2 expression was quantified through [89Zr]-pertuzumab PET/CT imaging. PTX treatment response was quantified by [18F]-fluorodeoxyglucose ([18F]-FDG) PET/CT imaging. Spearman's correlation, Kendall's tau, Kolmogorov-Smirnov test, and ANOVA were used for statistical analysis. [89Zr]-pertuzumab mean standard uptake values (SUVmean) of BT474 tumors were 4.9 ± 1.5, MDA-MB-361 tumors were 1.4 ± 0.2, and MDA-MB-231 (HER2-) tumors were 1.1 ± 0.4. [18F]-FDG SUVmean changes were negatively correlated with [89Zr]-pertuzumab SUVmean (r = -0.5887, p = 0.0030). The baseline [18F]-FDG SUVmean was negatively correlated with initial [89Zr]-pertuzumab SUVmean (r = -0.6852, p = 0.0002). This study shows PTX treatment efficacy is positively correlated with HER2 expression level in human breast cancer mouse models. Molecular imaging provides a non-invasive approach to quantify biological interactions, which will help in identifying chemotherapy responders and potentially enhance clinical decision-making.

What is the Diagnostic Performance of 18F-FDG-PET/MRI in the Detection of Bone Metastasis in Patients with Breast Cancer?

Objective

To evaluate the diagnostic performance of 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/magnetic resonance imaging (MRI) in the detection of bone metastasis in patients with breast cancer.

Materials and methods

From August 2018 to January 2019, a total of 23 patients with pathologically confirmed invasive breast cancer underwent whole-body hybrid 18F-FDG -PET/MRI for initial staging and follow-up of their malignancies. The number of the bone metastasis was recorded for each patient. The total 18F-FDG-PET/MRI protocol was compared with PET only and the contrast enhanced fused (CE) component for the detection of bone metastasis.

Results

Eight (26%) of 23 patients had bone metastasis. Bone metastases were dominantly localized in the spine (63%) and pelvis (25%). In terms of the total number of detected bone metastasis, there was a statistically significant difference between 18F-FDG-PET/MRI (mean 3.57; median 0; range, 0-2) and PET only component (mean 2.87; median 0; range, 0-1) (p=0.026), but no statistically significant difference was detected between 18F-FDG-PET/MRI and whole-body CE MRI (mean 3.43; median 0; range 0-2) (p=0.083).

Conclusion

Whole-body hybrid 18F-FDG-PET/MRI is superior to PET component only, but no statistically significant difference between hybrid 18F-FDG-PET/MRI and whole-body CE MRI is found for the detection of bone metastasis in patients with breast cancer.