Abstract
PurposeTo compare CT, MRI, and [18F]-fluorodeoxyglucose positron emission tomography ([18F]-FDG PET/MRI) for nodal status, regarding quantity and location of metastatic locoregional lymph nodes in patients with newly diagnosed breast cancer.Materials and methodsOne hundred eighty-two patients (mean age 52.7 ± 11.9 years) were included in this prospective double-center study. Patients underwent dedicated contrast-enhanced chest/abdomen/pelvis computed tomography (CT) and whole-body ([18F]-FDG PET/) magnet resonance imaging (MRI). Thoracal datasets were evaluated separately regarding quantity, lymph node station (axillary levels I–III, supraclavicular, internal mammary chain), and lesion character (benign vs. malign). Histopathology served as reference standard for patient-based analysis. Patient-based and lesion-based analyses were compared by a McNemar test. Sensitivity, specificity, positive and negative predictive values, and accuracy were assessed for all three imaging modalities.ResultsOn a patient-based analysis, PET/MRI correctly detected significantly more nodal positive patients than MRI (p < 0.0001) and CT (p < 0.0001). No statistically significant difference was seen between CT and MRI. PET/MRI detected 193 lesions in 75 patients (41.2%), while MRI detected 123 lesions in 56 patients (30.8%) and CT detected 104 lesions in 50 patients, respectively. Differences were statistically significant on a lesion-based analysis (PET/MRI vs. MRI, p < 0.0001; PET/MRI vs. CT, p < 0.0001; MRI vs. CT, p = 0.015). Subgroup analysis for different lymph node stations showed that PET/MRI detected significantly more lymph node metastases than MRI and CT in each location (axillary levels I–III, supraclavicular, mammary internal chain). MRI was superior to CT only in axillary level I (p = 0.0291).Conclusion[18F]-FDG PET/MRI outperforms CT or MRI in detecting nodal involvement on a patient-based analysis and on a lesion-based analysis. Furthermore, PET/MRI was superior to CT or MRI in detecting lymph node metastases in all lymph node stations. Of all the tested imaging modalities, PET/MRI showed the highest sensitivity, whereas CT showed the lowest sensitivity, but was most specific.
Highlights
With more than 2 million cases in 2020, breast cancer is the most commonly diagnosed cancer worldwide [1]
This study demonstrates the diagnostic superiority of [18F]-FDG patients underwent (PET/)magnet resonance imaging (MRI) over MRI and computed tomography (CT) in determining the correct nodal status in axillary, supraclavicular, and internal mammary lymph nodes in patients with newly diagnosed breast cancer
As no adequate reference standard was available for a total of 4 lymph nodes along the internal mammary chain, two different scenarios were calculated: if the 95% CI intervals of both calculation bases are taken as a basis, it can be assumed that PET/MRI is superior to MRI with regard to overall accuracy
Summary
With more than 2 million cases in 2020, breast cancer is the most commonly diagnosed cancer worldwide [1]. This article is part of the Topical Collection on Oncology - Chest. Extended author information available on the last page of the article significant prognostic factors at initial diagnosis of breast cancer [2, 3]. Locoregional lymph nodes are defined as ipsilateral axillary, supraclavicular, and internal mammary lymph nodes [4]. The likelihood of lymphatic drainage from the breast to axillary, internal mammary, infraclavicular, and supraclavicular lymph nodes are reported to be 98.2%, 35.3%, 1.7%, and 3.1% [5], but the location of lymph node metastases significantly depends on primary tumor location [6].
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