Usefulness of combined PET/CT to assess regional lymph node involvement in gastric cancer.
OBJECTIVE
The aim of this study was to evaluate the value of positron emission tomography/computed tomography (PET/CT) for preoperative staging of gastric cancer and to compare the diagnostic performance of PET/CT with that of contrast-enhanced computed tomography (CECT).


METHODS
We retrospectively reviewed 74 gastric cancer patients who underwent preoperative PET/CT and CECT, and subsequent curative surgical resection between April 2007 and July 2011. Preoperative PET/CT and CECT images for primary tumors of the stomach and lymph node metastases were reviewed retrospectively. The final diagnoses of primary tumors and LN metastases were based on histopathological specimens in all patients.


RESULTS
Advanced gastric cancer was present in 65% of patients (n = 48), and the remaining patients had early gastric cancer (n = 26). Sixteen patients (22%) showed signet-ring-cell histology. For the detection of the primary tumor, the sensitivity of PET/CT was significantly higher than that of CECT (67% vs 55%, respectively; P = 0.049). For the evaluation of regional lymph node metastasis, the sensitivity, specificity, and accuracy of PET/CT and CECT were 34% and 51% (P = 0.065), 88% and 79% (P = 0.687), and 58% and 64% (P = 0.332), respectively. Neither PET/CT nor CECT detected regional lymph node metastases in early gastric cancer patients. Signet-ring-cell histology showed trends of non-FDG-avid lymph node metastases (odds ratio = 0.15, 95% confidence interval 0.17-1.37, P = 0.093).


CONCLUSIONS
The accuracy of PET/CT is low and it is not a useful tool in the staging of gastric cancer overall in early gastric cancer and in signet-ring-cell carcinoma. Furthermore, the sensitivity of PET/CT could be inferior to that of CECT in the diagnosis of regional lymph node metastasis.
Kwonoh
K
Park
Geundoo
G
Jang
Sora
S
Baek
Hunho
H
Song
D000230:Adenocarcinoma / Q000175:diagnosis; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018279:Carcinoma, Signet Ring Cell / Q000175:diagnosis; D003287:Contrast Media; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods; D011237:Predictive Value of Tests; D011379:Prognosis; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed / Q000379:methods
D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18