EJNMMI Research (Aug 2021)

[18F]FDG-PET/CT in prone compared to supine position for optimal axillary staging and treatment in clinically node-positive breast cancer patients with neoadjuvant systemic therapy

  • Ariane A. van Loevezijn,
  • Marcel P. M. Stokkel,
  • Maarten L. Donswijk,
  • Erik D. van Werkhoven,
  • Marieke E. M. van der Noordaa,
  • Frederieke H. van Duijnhoven,
  • Marie-Jeanne T. F. D. Vrancken Peeters

DOI
https://doi.org/10.1186/s13550-021-00824-4
Journal volume & issue
Vol. 11, no. 1
pp. 1 – 9

Abstract

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Abstract Purpose Axillary staging before neoadjuvant systemic therapy in clinically node-positive breast cancer patients with tailored axillary treatment according to the Marking Axillary lymph nodes with radioactive iodine seeds (MARI)-protocol, a protocol developed at the Netherlands Cancer Institute, is performed with [18F] fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT). We aimed to assess the value of FDG-PET/CT in prone compared to standard supine position for axillary staging. Methods We selected patients with FDG-PET/CT in supine and prone position who underwent the MARI-protocol. One hour after administration of 3.5 MBq/kg, [18F]FDG-PET was performed with a low-dose prone position CT-thorax followed by a supine whole-body scan. Scans were separately reviewed by two nuclear medicine physicians and categorized by number of FDG-positive axillary lymph nodes (ALNs; cALN<4 or cALN≥4). Main outcome was axillary up- or downstaging. Results Of 153 patients included, 24 (16%) patients were up- or downstaged at evaluation of prone images: One observer upstaged 14 patients, downstaged 3 patients and reported a higher number of ALNs (3.6 vs. 3.2, p < 0.001), while staging (4 up- and 5 downstaged) and number of ALNs (2.8 vs. 2.8) did not differ for the other. Observers agreed on up- or downstaging in only 1 (1%) patient. Irrespective of supine or prone position scanning, observers agreed on axillary staging in 124 (81%) patients and disagreed in 5 (3%). Interobserver agreement was lower with prone assessments (86%, K = 0.67) than supine (92%, K = 0.80). Conclusions Axillary staging with FDG-PET/CT in prone compared to supine position did not result in concordant up- or downstaging. Therefore, FDG-PET/CT in supine position only can be considered sufficient for axillary staging.

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