Diagnostic Value Of Contrast-enhanced Harmonic Endoscopic Ultrasound In Submucosal Tumors Of Upper Digestive Tract

Objective: Submucosal tumours（SMTs）of the upper gastrointestinal tract are common in clinical practice and are classified as benign or malignant according to their biological characteristics and clinical course,with different treatment strategies and prognosis.Gastrointestinal stromal tumor is the most common SMTs with malignant potential.There are numerous imaging methods available,but there is still a lack of uniform diagnostic criteria.This study focuses on the value of conventional examination methods CT,endoscopic ultrasound（EUS）and the new technique of contrast-enhanced harmonic endoscopic ultrasound（CEH-EUS）for the differential diagnosis of benign and malignant SMTs in the upper gastrointestinal tract and for the assessment of the malignant potential of GIST.Methods: Retrospective analysis of clinical data of patients who visited the Second Hospital of Anhui Medical University for upper gastrointestinal SMTs from August2018 to November 2021,underwent preoperative CT,EUS or CEH-EUS,and were surgically treated to obtain a complete histopathological diagnosis.Results: The study ultimately included 158 patients with pathologically confirmed benign tumours in 65 cases,including 52 smooth muscle tumours,5 inflammatory fibrous tumours,3 Bruch’s adenomas,1 lipoma,2 cysts and 2 nerve sheath tumour,plus93 GIST.Among them,108 cases underwent EUS and CT.The positive rate of CT for tumours less than 20 mm in length was only 23.2%,and enhanced CT showed mostly heterogeneous enhancement of GIST,with a statistical difference（P < 0.05）and a diagnostic accuracy of 78.0%.45 cases underwent undergoing ultrasound microprobe and 63 cases underwent longiludinal endoscopic ultrasound,GIST under EUS were more frequently seen in the stomach,originating in the intramural layer,and are larger,with a smaller long-to-short ratio,more surface mucosal erosions or ruptures,more internal echogenicity,more doppler-rich flow and more intratumour-specific manifestationsthan benign tumours,with statistical differences（P<0.05）.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of ultrasound microprobe and longitudinal ultrasound diagnosis for the differential diagnosis of benign tumours from GIST were 100%,88.5%,88.9%,61.5%,100%,and95.9%,71.4%,90.1%,92.2%,83.3%,respectively.50 cases underwent CEH-EUS,of which 36 were GIST and 14 were benign tumours.GIST showed high enhancement in the arterial phase at CEH-EUS（32/36）and benign SMTs showed low or no enhancement（11/14）,the difference was statistically significant（P<0.05）,Its sensitivity,specificity,accuracy,positive predictive value and negative predictive value for identifying benign and malignant SMTs were 88.9%,92.9%,90.0%,97.0% and 76.5%respectively.The 36 GIST were divided into 24 cases in the low risk group（including 6 cases of very low risk and 18 cases of low risk）and 12 cases in the high risk group（including 10 cases of medium risk and 2 cases of high risk）according to the primary location,size and mitotic index of the GIST.Compared to the low-risk group,irregular vessels were seen in 10/12 cases and heterogeneous enhancement was seen in 11/12 cases in the high-risk group,with statistically significant differences（P<0.05）.The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of irregular vessels and heterogeneous enhancement in predicting malignant potential were 83.3%,87.5%,86.1%,76.9%,and 91.3% and 91.7%,79.2%,83.3%,68.8% and95.0% respectively.Conclusion: EUS has a high diagnostic value in differentiating benign SMTs from GIST in the upper gastrointestinal tract,especially in small tumours due to CT,and EUS in combination with CT can provide a more comprehensive assessment for better treatment.EUS combined with ultrasonography not only improves the ability to identify SMTs in the upper gastrointestinal tract,but also further improves the assessment of the preoperative malignant potential of GIST.CEH-EUS improves the ability to identify benign and malignant SMTs in the upper gastrointestinal tract and further improves the assessment of the preoperative malignant potential of GIST.