Significant value of 18F-FDG-PET/CT in diagnosing small cervical lymph node metastases in patients with nasopharyngeal carcinoma treated with intensity-modulated radiotherapy

Chin J Cancer. 2017 Dec 19;36(1):95. doi: 10.1186/s40880-017-0265-9.

Abstract

Background: Little is known about the nature of metastasis to small cervical lymph nodes (SCLNs) in the patients with nasopharyngeal carcinoma (NPC) examined by using 18-fluoro-2-deoxy-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT). The present study aimed to evaluate the diagnostic values of PET/CT in identifying metastasis in SCLNs in NPC patients.

Methods: Magnetic resonance images (MRI) and PET/CT scans for 470 patients with newly diagnosed, non-distant metastatic NPC were analyzed. Metastatic rates of SCLNs were defined by the positive number of SCLNs on PET/CT scans and total number of SCLNs on MRI scans. Receiver operating characteristic curve was applied to compare PET/CT-determined stage with MRI-determined stage.

Results: In total, 2082 SCLNs were identified, with 808 (38.8%) ≥ 5 and < 6 mm in diameter (group A), 526 (25.3%) ≥ 6 and < 7 mm in diameter (group B), 374 (18.0%) ≥ 7 and < 8 mm in diameter (group C), 237 (11.4%) ≥ 8 and < 9 mm in diameter (group D), and 137 (6.5%) ≥ 9 and < 10 mm in diameter (group E). The overall metastatic rates examined by using PET/CT for groups A, B, C, D, and E were 3.5%, 8.0%, 31.3%, 60.0%, and 83.9%, respectively (P < 0.001). In level IV/Vb, the metastatic rate for nodes ≥ 8 mm was 84.6%. PET/CT examination resulted in modification of N category and overall stage for 135 (28.7%) and 46 (9.8%) patients, respectively. The areas under curve of MRI-determined and PET/CT-determined overall stage were 0.659 and 0.704 for predicting overall survival, 0.661 and 0.711 for predicting distant metastasis-free survival, and 0.636 and 0.663 for predicting disease-free survival.

Conclusions: PET/CT was more effective than MRI in identifying metastatic SCLNs, and the radiologic diagnostic criteria for metastatic lymph nodes in level IV/Vb should be re-defined.

Keywords: 18-fluoro-2-deoxy-glucose positron emission tomography with computed tomography (18F-PET/CT); Intensity-modulated radiotherapy; Magnetic resonance image; Nasopharyngeal carcinoma; Small cervical lymph nodes.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Carcinoma / diagnosis*
  • Carcinoma / mortality
  • Carcinoma / radiotherapy*
  • Female
  • Fluorodeoxyglucose F18
  • Humans
  • Lymph Nodes / diagnostic imaging*
  • Lymph Nodes / pathology*
  • Lymphatic Metastasis
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms / diagnosis*
  • Nasopharyngeal Neoplasms / mortality
  • Nasopharyngeal Neoplasms / radiotherapy*
  • Neck / diagnostic imaging*
  • Neck / pathology*
  • Neoplasm Staging
  • Positron Emission Tomography Computed Tomography* / methods
  • Prognosis
  • ROC Curve
  • Radiotherapy, Intensity-Modulated*
  • Treatment Outcome
  • Young Adult

Substances

  • Fluorodeoxyglucose F18