Distribution Characteristics of Colorectal Peritoneal Carcinomatosis Based on the Positron Emission Tomography/Peritoneal Cancer Index

Application of Imaging Indicators Based on 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Colorectal Peritoneal Carcinomatosis

Objective

The imaging features of peritoneal carcinomatosis (PC) with different locations and pathological types of colorectal cancer (CRC) on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) were analyzed and discussed.

Methods

The PET/CT data of 132 patients with colorectal peritoneal carcinomatosis (CRPC) who met the inclusion and exclusion criteria between May 30, 2016, and December 31, 2019, were collected and analyzed. Observations included the location and pathological type of CRC, the peritoneal cancer index (PCI), standardized uptake maximum value (SUV_max), and retention index (RI) of the CRPC. Statistical analysis was performed using SPSS 20.0 software, and P < 0.05 was considered statistically significant.

Results

(1) The range of the PCI in the 132 patients studied was 2–30, with a mean value of 7.40 ± 8.14. The maximum long diameter of the CRPC lesions ranged from 0.6 to 12.1 cm, with an average of 3.23 ± 1.94 cm. The SUV_max ranged from 1.2 to 31.0, with a mean value of 9.65 ± 6.01. The SUV_max and size correlation coefficient for maximal CRPC lesions was r = 0.47 (P < 0.001). The RI range of the 72 patients who underwent time-lapse scanning was -10.0–112.2%, with RI quartiles of 13.5–48.9%; RI was ≥5% in 65 cases and <5% in seven cases. (2) The patients were grouped by the location of their CRC: the right-sided colon cancer (RCC, n = 37), left-sided colon cancer (LCC, n = 44), and rectal cancer groups (RC, n = 51). There were significant differences in the CRC pathological types (P = 0.009) and PCI scores (P = 0.02) between the RCC and RC groups and the RI between the RCC group and the other two groups (P < 0.001). (3) There were 88 patients organized into three groups by the pathology of their CRC: the moderately well-differentiated adenocarcinoma (group A, n = 57), poorly differentiated adenocarcinoma (group B, n = 16), and mucinous adenocarcinoma groups (group C, n = 15 cases, including one case of signet-ring cell carcinoma). There were significant differences in the CRC position (P = 0.003) and SUV_max (P = 0.03) between groups A and C.

Conclusion

The PCI, SUV_max, and RI of peritoneal metastatic carcinoma caused by CRC in different locations and pathological types vary. Mucinous adenocarcinoma and poorly differentiated adenocarcinoma are relatively common in the right colon, and the PCI of peritoneal metastatic carcinoma is fairly high, but the SUV_max and RI are somewhat low.