Abstract: 【Abstract】Objective:To summarize the imaging characteristics ship of Fluorine18fluorodeoxyglucose ( 18FFDG) PET/CT examination in esophageal carcinoma and the relation between metabolic parameters and stage.
Methods:The clinical data of 53 patients with esophageal carcinoma who were admitted to the Changhai Hospital Affiliated to the Second Military Medical University between January 2012 and December 2014 were retrospectively analyzed. All the patients underwent 18FFDG PET/CT examination. The standardized uptake value 2.5 (SUV 2.5) was set as threshold value, and maximum SUV (SUVmax), average SUV (SUVavg), metabolic tumor volume (MTV) and maximum diameter of primary lesion were collected. The total lesion glycolysis (TLG) was calculated and SUVmax of lymph nodes in the metastasis area and distant metastasis carcinoma was measured. Measurement data with normal distribution were presented as ±s, and comparison between groups was evaluated with an independent sample the t test. Skew distribution data were described as M(Qn), and comparison between groups was analyzed using the MannWhitney test.
Results:(1) Tumor location and volume: one tumor was located at the cervical portion of the esophagus, 16 at the upper thoracic portion, 18 at the midthoracic portion, 13 at the lower thoracic portion, 2 at the upper thoracic portion and midthoracic portion and 3 at the midthoracic portion and the lower thoracic portion. Tumor volume was 1.6 cm×1.2 cm×2.2 cm-6.5 cm×7.0 cm×7.2 cm and maximum diameter of tumor was (6.1±2.1)cm (range, 2.5-11.2 cm). (2) Performance of PET/CT examination: of 53 patients, 51 (96.2%) had 18FFDG uptake increased, thickening esophageal wall, unclear boundary between lesions and normal tissues and luminal stenosis of the lesion, and 2 (3.8%) had local nodular 18FFDG uptake increased without thickening esophageal wall. The infringement of the surrounding tissue organs was detected in 13 patients (24.5%), with unclear boundary between lesions with primary esophageal tumors and 18FFDG uptake increased. The regional lymph nodes metastasis was detected in 41 patients (77.4%), with 18FFDG uptake increased. The distal metastasis of 14 patients (26.4%) was located in the liver and lung, with 18FFDG uptake increased. (3) Metabolic parameters of PET/CT examination: SUVmax, SUVavg, MTV and TLG in the primary esophageal lesion of 53 patients were 16.3±6.2 (range, 4.9-30.9), 6.0±1.7 (range, 3.3- 10.4), 18.14 cm3 (7.74 cm3, 28.89 cm3) and 105.37 g (42.85 g, 205.62 g), respectively. SUVmax of regional lymph nodes metastasis and distant metastasis tumors were 10.5±5.6 (range, 2.7-21.9) and  13.0± 7.1 (range, 5.8-23.5). (4) Comparisons of metabolic parameters of tumors in different N, M stages: SUVmax, MTV and TLG were 16.7±5.9, 20.92 cm3 (12.65 cm3, 35.73 cm3) and 132.87 g (65.49 g, 226.67 g) in the N1-3 stage and 15.1±7.4, 6.88 cm3 (4.40 cm3, 21.53 cm3) and 35.45 g (17.53 g, 124.23 g) in the N0 stage, respectively, with no significant difference in the SUVmax between the N1-3 stage and N0 stage（t= -0.785, P>0.05). MTV and TLG of the primary esophageal lesion in the N1-3 stage were significantly higher than that in the N0 stage (Z=-2.657,-2.614, P<0.05). SUVmax, MTV and TLG of the primary esophageal lesion were 16.9±7.4, 16.14 cm3 (8.33 cm3, 26.69 cm3) and 97.77 g (51.15 g, 153.50 g) in the M1 stage, 16.1±5.8，20.08 cm3 (7.50 cm3, 31.34 cm3) and 106.01 g (40.16 g, 214.55 g) in the M0 stage, respectively, showing no significant difference between the M1 stage and M0 stage (t=0.387, Z=-0.282, -0.383, P>0.05).
Conclusions:Imaging characteristics of 18FFDG PET/CT examination for esophageal carcinoma include the increase of 18FFDG uptake and local or extensive tube wall thickening, and N stage of primary esophageal lesion commonly located in the midthoracic portion is related to MTV and TLG. PET/CT examination shows a certain value to the primary and metastatic lesions of the esophagus.