Correlation Between CT Features And Prognosis Of Adenoid Cystic Carcinoma Of The Palate

Objective: To analyze the characteristic CT manifestations of adenoid cystic carcinoma(ACC)in the palate,and to analyze the correlation between the characteristics of adjacent neural foramen invasion and the prognosis of patients,and to explore the value of CT in the diagnosis and prognosis evaluation of ACC in the palate.Methods: 92 patients with ACC in palatal region who were initially diagnosed in our hospital and confirmed by surgery and pathology were analyzed retrospectively from January 2009 to January 2019.All patients were examined with plain and enhanced CT before operation,and the CT morphology,plain and enhanced CT value,and the adjacent anatomic foramen invasion were recorded.The data of clinical characteristics and followup were collected,the survival curve was drawn by Kaplan Meier method,and the difference of survival period was compared by log rank test.Multivariate Cox proportional risk model was used to evaluate the value of CT in predicting the prognosis of patients with palatal ACC.Results: 92 cases of ACC were included,including 40 males and 52 females.The ratio of males to females was 1:1.3.The clinical manifestations included 69 cases of painless nodule or mass,10 cases of painful ulcer,9 cases of pain in upper and posterior teeth,2cases of physical examination,and 2 cases of minor bleeding in the palate.Plain CT showed the density shadow of soft tissue in the palate with unclear boundary.The value of plain CT ranged from 18 to 51 hu.Enhanced CT showed uneven enhancement in 58cases(63.0%),which could be seen as ethmoidal enhancement;even enhancement in 21cases(20.6%);no enhancement in 13 cases(14.2%).In 55 cases(59.7%)of the tumors,there were multiple adjacent neuroanatomic foramen invasion on CT.When pterygopalatine fossa was involved(33/92,35.9%),the greater palatine foramen was involved(55/92,59.7%);when foramen rotundum was involved(25/92,27.1%),the greater palatine foramen was involved(55/92,59.7%)and the pterygopalatine fossa was involved(33/92,35.9%)as well.Among them,55 cases(59.7%)involved the great palatine foramen,33 cases(35.9%)involved the pterygopalatine fossa and 25 cases(27.1%)involved the round foramen.The five-year and disease-free survival rates of 92 ACC patients were 95.2% and 86.4%,respectively.Multivariate Cox analysis indicated that the involvement of foramen rotundum on CT was a variable factor(HR = 7.8,P =0.05)affecting the overall survival time and disease-free survival time of ACC in the palatine region(HR = 4.1,P = 0.004),while the involvement of pterygopalatine fossa and greater palatine foramen were non-variable factors(P > 0.05).Kaplan Meier survival analysis showed that there was a significant difference between the overall survival time(P = 0.02,95% CI: 81.6-96.3)and disease-free survival time(P = 0.001,95% CI: 76.3-81.6)in the presence or absence of foramen rotundum on CT.Conclusion: ACC in the palatal region can be seen as ethmoidal enhancement,homogeneous enhancement or no enhancement on enhanced CT.The tumor has the CT characteristics of growth along the foramen of anatomy of the peripheral nerve,such as palatal foramen,pterygopalatine fossa and foramen rotundum.When CT shows that the foramen rotundum is invaded,it may affect the prognosis of ACC patients in the palatal region.