Abstract: Objective:To summarize the CT characteristics of tumor deposition adjacent to colorectal cancer (CRC), and provide the evidences for differential diagnosis.
Methods:The retrospective crosssectional study was conducted. The clinicopathological data of 26 CRC patients who were admitted to the Wuxi Second People′s Hospital of Nanjing Medical University from May 2015 to April 2017 were collected. Patients underwent preoperative multislice spiral CT scan and doublephase enhanced scan, and then received open surgery. Observation indicators: (1) characteristics of multislice spiral CT scan; (2) differential comparisons; (3) followup. Followup using telephone interview was performed to detect patients′ prognosis once every 3 months up to May 2017. Measurement data with normal distribution were represented as ±s. Comparisons between groups and among groups were respectively analyzed using the t test and the oneway ANOVA. Pairwise comparison was done using the SNK method.
Results: (1) Characteristics of multislice spiral CT scan: of 26 patients, 17 underwent double contrast enhanced scans of chest, abdomen and pelvic and 9 underwent double contrast scans of abdomen and pelvic. Primary tumors of 18 and 8 patients respectively located in the colon and rectum. Fortyone tumor deposits of 26 patients were collected, with number of tumor deposits of 1.6±0.9 per case, and number of tumor deposits <3 and ≥3 respectively were found in 20 and 6 patients. Tumor deposits were often isolated in the fat spaces around the rectum or colon and unconnected with the surrounding primary tumor or lymph node. Distance to the center of primary tumor was (2.6±1.0)cm (range, 0.2-5.0 cm), the distance <2.6 cm and ≥2.6 cm were respectively detected in 22 and 19 patients. Thirtythree tumors showed signs of lobulation, 22 showed signs of burr and 7 showed liquefaction necrosis, and there was a combination of multiple imaging characteristics in the same tumor deposit. The maximum width, minimum width, maximum diameter, plain scan value of CT, CT enhancement values in the arterial phase and venous phase in 41 tumor deposits were respectively (1.15±0.60)cm, (1.11±0.44)cm, (1.13±0.49)cm, (27±13)HU, (28±14)HU and (49±19)HU. Of 41 tumor deposits, 34 demonstrated homogeneous density in the plain scan, and obviously enhancement in early enhanced scan, with homogeneous enhancement; 7 demonstrated heterogeneous density in the plain scan, with internal liquefaction necrosis, and enhanced scans showed no enhancement in the areas of necrosis and obviously early enhancement in the areas of nonnecrosis. (2) Differential comparisons: 26 patients underwent open surgery, including 8 with right hemectomy, 2 with transverse colon resection, 4 with left semicolon resection, 2 with simple sigmoid resection, 2 with abdominoperineal resection of rectal cancer and 8 with low anterior rectal resection, and all patients received postoperatively individualized treatment. Fiftytwo lymph nodes with distance to center of primary tumor < 5.0 cm that were confirmed by pathological examination were collected, including 19 metastatic lymph nodes. Of 41 tumor deposits, 33 were irregular, and 8 were regular and roundlike or ovallike shape. Of 19 metastatic lymph nodes, 16 were regularly roundlike shape, 1 showed irregular shape and edge blur, and 2 were irregular with a mutual integration. The maximum width, minimum width and maximum diameter of 19 metastatic lymph nodes were respectively (1.09±0.33)cm, (1.01±0.23)cm and (1.05±0.20)cm, with statistically significant differences in the above indicators between metastatic lymph nodes and tumor deposits (t=5.48, 4.80, 7.75, P<0.05). The plain scan value of CT, CT enhancement values in the arterial phase and venous phase were respectively (12±7)HU, (18±12)HU, (42±15)HU in 19 metastatic lymph nodes and (33±6)HU, (31± 15)HU, (53±14)HU in 26 primary tumors, showing statistically significant differences in the plain scan value of CT and CT enhancement values in the arterial phase among tumor deposits, metastatic lymph nodes and primary tumors (F=24.43, 4.46, P<0.05), and no statistically significant difference in CT enhancement value in the venous phase (F=2.41, P>0.05). There were statistically significant differences in the plain scan value of CT and CT enhancement values in the arterial phase between tumor deposits and metastatic lymph nodes (q=5.48, 2.50, P<0.05) and between metastatic lymph nodes and primary tumors (q=6.82, 2.84, P<0.05), and no statistically significant difference between tumor deposits and primary tumors (q=2.15, 0.65, P>0.05). Of 19 metastatic lymph nodes, 11 demonstrated homogeneous density in plain scan, with a lower density compared with tumor deposits and primary tumors, and relatively homogeneous enhancement in the arterial phase of enhanced scan; 8 demonstrated heterogeneous density with internal liquefaction necrosis, and ringshaped enhancement in enhanced scan with no enhancement in the areas of necrosis. The density and enhancement range in the arterial phase and venous phase of tumor deposits were similar to primary tumors. (3) Followup: 24 patients were followed up for 1-25 months, with a followup rate of 92.3%(24/26) and a median time of 17 months. Of 24 patients, 2 were dead, and survival time were respectively 9 months and 21 months; 22 had good survival.
Conclusions: Multislice spiral CT examination of tumor deposits demonstrates larger and irregular shape, with the signs of lobulation and burr, and the density in plain scan is similar to the primary tumor, with obviously enhancement in early enhanced scan. The metastatic lymph nodes are mostly roundlike shape, diameter is smaller than that of tumor deposits, density in the plain scan and CT enhancement values in the arterial phase are lower than that of tumor deposits.