Comparison of Whole-Body¹⁸F FDG PET/MR Imaging and Whole-Body¹⁸F FDG PET/CT in Terms of Lesion Detection and Radiation Dose in Patients with Breast Cancer

Abstract

Purpose To compare fluorine 18 (18F) fluorodeoxyglucose (FDG) combined positron emission tomography (PET) and magnetic resonance (MR) imaging with 18F FDG combined PET and computed tomography (CT) in terms of organ-specific metastatic lesion detection and radiation dose in patients with breast cancer. Materials and Methods From July 2012 to October 2013, this institutional review board–approved HIPAA-compliant prospective study included 51 patients with breast cancer (50 women; mean age, 56 years; range, 32–76 years; one man; aged 70 years) who completed PET/MR imaging with diffusion-weighted and contrast material–enhanced sequences after unenhanced PET/CT. Written informed consent for study participation was obtained. Two independent readers for each modality recorded site and number of lesions. Imaging and clinical follow-up, with consensus in two cases, served as the reference standard. Results There were 242 distant metastatic lesions in 30 patients, 18 breast cancers in 17 patients, and 19 positive axillary nodes in eight patients. On a per-patient basis, PET/MR imaging with diffusion-weighted and contrast-enhanced sequences depicted distant (30 of 30 [100%] for readers 1 and 2) and axillary (eight of eight [100%] for reader 1, seven of eight [88%] for reader 2) metastatic disease at rates similar to those of unenhanced PET/CT (distant metastatic disease: 28 of 29 [96%] for readers 3 and 4, P = .50; axillary metastatic disease: seven of eight [88%] for readers 3 and 4, P > .99) and outperformed PET/CT in the detection of breast cancer (17 of 17 [100%] for readers 1 and 2 vs 11 of 17 [65%] for reader 3 and 10 of 17 [59%] for reader 4; P < .001). PET/MR imaging showed increased sensitivity for liver (40 of 40 [100%] for reader 1 and 32 of 40 [80%] for reader 2 vs 30 of 40 [75%] for reader 3 and 28 of 40 [70%] for reader 4; P < .001) and bone (105 of 107 [98%] for reader 1 and 102 of 107 [95%] for reader 2 vs 106 of 107 [99%] for reader 3 and 93 of 107 [87%] for reader 4; P = .012) metastases and revealed brain metastases in five of 51 (10%) patients. PET/CT trended toward increased sensitivity for lung metastases (20 of 23 [87%] for reader 1 and 17 of 23 [74%] for reader 2 vs 23 of 23 [100%] for reader 3 and 22 of 23 [96%] for reader 4; P = .065). Dose reduction averaged 50% (P < .001). Conclusion In patients with breast cancer, PET/MR imaging may yield better sensitivity for liver and possibly bone metastases but not for pulmonary metastases, as compared with that attained with PET/CT, at about half the radiation dose.

Reduction of 18F-FDG Dose in Clinical PET/MR Imaging by Using Silicon Photomultiplier Detectors

“…With 185 MBq equaling an effective absorbed dose of around 3.5 mSv, 112.5 MBq would decrease the radiation burden to approximately 2.2 mSv for a whole-body PET examination (18). Other studies have already quantified the dose reduction that can be achieved with PET/MR imaging compared with PET/CT only by omitting the CT component (7). In this context, the PET component represents the more significant radiation burden and thus offers a greater potential for reduction of the injected tracer dose.…”

“…The newly available PET/magnetic resonance (MR) imaging systems can help reduce the absorbed radiation dose to patients (5)(6)(7). In these systems, the MR imaging component, which does not require the use of ionizing radiation, replaces the CT component for attenuation correction, anatomic correlation, and diagnostic lesion characterization.…”

Voxelwise analysis of simultaneously acquired and spatially correlated 18F‐fluorodeoxyglucose (FDG)‐PET and intravoxel incoherent motion metrics in breast cancer

“…Chemotherapy regimens varied accordingly with the heterogeneity in histology and prognostic factors of the tumor and included hormone therapy and cytotoxic treatment. Results from the whole body PET/MR evaluation (33) or local DCE-MRI (34) of these patients have been recently reported and in some cases provided the metastatic burden assessment considered in the present study.…”

Breast PET/MR Imaging

“…In whole-body imaging for breast cancer, PET/MR imaging has been shown to provide improved sensitivity over PET/CT 6,64,65 or PET alone, 43 particularly for breast cancers, 64 liver metastases, 64 and bone metastases 6,64,65 (Figs. 3 and 4).…”