Dual-phase F-18 FDG PET-CT in staging and lymphoscintigraphy for detection of sentinel lymph nodes in oral cavity cancers

Clin Imaging. 2015 Sep-Oct;39(5):781-6. doi: 10.1016/j.clinimag.2015.02.004. Epub 2015 Feb 12.

Abstract

Aim: Our objective was to evaluate the diagnostic role of dual-phase fluor-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography-computed tomography (PET-CT) and planar lymphoscintigraphy in patients with oral cavity cancer (OCC). We also investigated the combined impact of F-18 FDG PET-CT and sentinel lymph node biopsy (SLNB) in decision making for patients with OCC.

Methods: Sixteen patients (4 female, 12 male; age range, 29-81 years) were included in this prospective study. F-18 FDG PET-CT [1 (early) and 2 h (delayed) after injection] and planar lymphoscintigraphy (2h before the surgery) were performed for all the patients before surgery. The sensitivity, specificity, and negative and positive predictive values in F-18 FDG PET-CT for the early and the delayed scans and tumor/liver uptake (T/L) in the lymph nodes were calculated. Receiver operating characteristic curves were obtained for standardized uptake value (SUV)max and T/L.

Results: Histopathological evaluations revealed that 5 patients had metastatic lymph nodes (pN+) whereas 11 patients had benign lymph nodes (pN-). Out of 43 lymph nodes visualized as cN(+) in F-18 FDG PET-CT, 14 were pathologically positive for malignancy, whereas 29 were pathologically benign. There was no statistical difference between the N(+) and N(-) patients in terms of age, depth of primary tumor, and the number of mitoses. However, there was a significant difference between the N(+) and N(-) patients (P=.011) in terms of early and delayed F-18 FDG uptake of primary tumors. There was a statistically significant difference in the value of SUVmax between the early and the delayed scans for the malignant lymph nodes (P=.00).

Conclusion: This study indicates that F-18 FDG PET-CT is a reliable method for the correct evaluation of primary tumor and N staging in OCCs. Delayed phase of F-18 FDG imaging may increase primary lesion detectability due to higher FDG uptake in primary tumors compared to the early phase of imaging. F-18 FDG PET-CT might demonstrate skip metastasis in lymph nodes which can be missed with SLNB. Although SUV values increased in the delayed phase of F-18 PET-CT imaging in detecting lymph node metastases, the specificity and positive predictive value did not increase.

Keywords: Dual phase; F-18 FDG PET–CT; Oral cavity cancers; Planar lymphoscintigraphy.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Fluorodeoxyglucose F18*
  • Humans
  • Lymph Nodes / diagnostic imaging
  • Lymphatic Metastasis
  • Lymphoscintigraphy*
  • Male
  • Middle Aged
  • Mouth / diagnostic imaging
  • Mouth / pathology
  • Mouth Neoplasms / diagnosis*
  • Mouth Neoplasms / pathology
  • Multimodal Imaging
  • Neoplasm Staging
  • Positron-Emission Tomography*
  • Prospective Studies
  • ROC Curve
  • Sensitivity and Specificity
  • Sentinel Lymph Node Biopsy*
  • Tomography, X-Ray Computed*

Substances

  • Fluorodeoxyglucose F18