Application Analysis Of Transrectal Ultrasound And MRI In Preoperative Diagnosis Of Complicated Anal Fistula

BackgroundAnal fistula is a common and frequently-occurring disease in anorectal surgery.The etiology is related to perianal abscess,perineal surgery,rectal anal injury,blood infection,etc.8% to 25% of anorectal diseases are mainly characterized by repeated swelling and pain,spontaneous Pus,itching,etc.In view of the special anatomical features,anal fistula can not be self-healing.Instead,it must undergo surgical treatment.Besides,the recurrence rate is high.Therefore,it has been listed as one of the refractory diseases of anorectal.Complex anal fistula refers to an anal fistula with two or more internal or external openings and two or more fistulas or branches and blind tubes.The internal orifice,fistula,and walking are more complicated.It is generally believed that the recurrence rate of anal fistula surgery is 4% to 10%,and the recurrence rate of complex anal fistula is as high as20% to 40%,so it is the most difficult type of anal fistula treatment.Improper treatment of the internal orifice and incomplete management of the fistula or missing branch fistula and the lack of understanding of the fistula are the serveral main causes of the recurrence of anal fistula.Therefore,proper treatment of the internal orifice,branch and dead space is of great significance in reducing postoperative recurrence.Correctly assessing the position of the internal orifice of the anal fistula,the relationship between the lesion and the sphincter,and the movement of the fistula before surgery are prerequisites for proper management during surgery.At present,the evaluation of anal fistula before clinical operation mainly depends onthe patient's symptoms,detailed local examination,fistula angiography,etc.Although there are many methods,there are problems such as low accuracy of internal mouth judgment and inability to objectively judge the relationship between fistula and sphincter.In recent years,imaging examination has been highly valued in the anorectal department.Among them,transrectal ultrasound and MRI are two common imaging methods.The former has the advantages of no trauma and high economy,it can also describe the relationship between the anal fistula and the anal sphincter.With high resolution,it can provide accurate anal sphincter anatomy information,which provides valuable guidance for surgery.But there is controversy about the application value of the two methods.This study provides an in-depth analysis of the application of intra-rectal ultrasound and MRI in the preoperative diagnosis of complex anal fistula,and a reference for the clinical selection of appropriate preoperative diagnosis methods.Part 1.The application of intra-rectal ultrasound in the diagnosis of complicated anal fistulapurposeTo explore the value of transrectal ultrasound in the diagnosis of complicated anal fistula.methodSixty patients with complicated anal fistula admitted to the Department of Anorectal Surgery in the First Affiliated Hospital of Henan University of Traditional Chinese Medicine from May 2017 to December 2018 were selected as subjects.The patients underwent transrectal ultrasound using the Hitachi HI Vision Ascendus ultrasound system.The examination was performed by two experienced physicians in the Department of Ultrasound,and the images were analyzed in a double-blind manner.The consensus wasused as the final diagnosis.The general data(age,gender,duration of disease,combined disease,previous surgical history)of the patients were counted as well as the ultrasound image features.The results of the operation were taken as the standard,and the consistency of the internal orifice,the main tube,the branch tube/abscess cavity,the abscess,the different anal fistulas of different Parks and the surgical results were compared.result1.Ultrasonographic features of fistula:(1)Transsphincter type: low echo fistula passes through the external sphincter.The extended part of the external sphincter is reflected by it,and its normal structure is destroyed.Referring to the position of the external anal sphincter,it can be divided into high and low anal fistula.(2)Intersphincter type: a weak reflex zone appeared on the longitudinal section.The original narrow INTERSPHINCTER layer was widened and deformed locally,with low echo area passing through the interspace of the sphincter,but the ultrasonographic findings indicated that the fibrous layer of the external sphincter was not penetrated;(3)sphincter type: slightly higher echo or hypoechoic fistula and the external sphincter side are close to each other,not connected to the fistula;(4)Superior sphincter type: walking above or through the puborectal muscle,the hypoechoic duct penetrated the level of the puborectal muscle.2.Ultrasound image characteristics of the inner mouth: It can be strong echo type or low echo type.(1)The destruction of the upper and lower skin tissues connected with the sphincter fistula through the absence of the internal sphincter;(2)the root-like budding of the absence of the internal sphincter;(3)the root-like budding of the anal internal sphincter,which is formed by the fistula between the sphincters;3.Ultrasound image characteristics of intrarectal probe:(1)transsphincter type: after transanal internal and external sphincter,the proximal end of fistula runs through the posterior anal space or the ischioanal space,and the external end stops at the distal end;(2)transverse sphincter type: elliptic,circular,banded hypoechoic can be seen in thetransection.Long-axis transverse ultrasonographic signs show local widening of the original narrow internal and external anal sphincter space and it is hypoechoic;(3)sphincter shape: rectal horizontal anal canal and fistula are connected,but the course is basically parallel to the long axis of the anal canal;(4)supraspinous sphincter type: the hypoechoic area with unclear boundary is located between the internal and external anal sphincters,moving toward the head side,then above the levator ani and puborectalis muscles,and then crossing the ischiorectal space to the skin surface.4.Surgical results: 80 internal orifices,71 supervisors,85 branches/abscesses were detected,and 9 patients were accompanied by abscess.The Kappa value was 0.843(>0.75,95% CI 0.754-0.932)and the consistency was 89.11%(P<0.05).25 cases of transsphincter type,21 cases of intersphincteric type and 14 cases of supersphincter type.The Kappa value was 0.719(0.4-0.75,95% CI 0.517-0.920)and the consistency was 82.00%(P <0.05).conclusionThe sphincter,anal rectum and surrounding tissues were clearly displayed by transrectal ultrasound.The internal orifice,superintendent,branch/abscess,abscess and the relationship with sphincter were consistent with the results of operation,which could provide visual and valuable imaging information for surgical intervention.Part 2 Application of intra-rectal ultrasound combined with MRI in preoperative diagnosis of complicated anal fistulapurposeTo explore the application value of transrectal ultrasound combined with MRI in preoperative diagnosis of complicated anal fistula.methodSixty patients with complicated anal fistula admitted to the Department of Anorectal Surgery in the First Affiliated Hospital of Henan University of Traditional Chinese Medicine from May 2017 to December 2018 were selected as subjects.The patients underwent transrectal ultrasound using the Hitachi HI Vision Ascendus ultrasound system.The MRI was performed on the enrolled patients using the Philips 1.5T Achieva Dual MRI scanner and the body coil.The images were analyzed by two experienced physicians under double-blind,and the final diagnosis is agreed by them.The sensitivity,accuracy and specificity of the internal,oral,branch/absic cavity detection rate and diagnosis of different Parks classification anal fistula were compared between ultrasound,MRI,and ultrasound+MRI.result1.Comparing the three methods to detect the internal mouth,main tube,branch tube/absema cavity: the surgical results were taken as the standard,the detection rates of the internal mouth and branch tube/pus cavity were compared in three methods,and the difference was statistically significant(P<0.05).For Ultrasound+MRI internal port,branch/abscess detection rate(95.00%,95.29%)was higher than single ultrasound(75.00%,80.00%)and MRI(81.25%,83.53%)examination(P<0.05);There was no significant difference in the detection rate of MRI internal and branch/abscess(P>0.05).There was no significant difference in the detection rate of the three methods and abscess(P>0.05).2.sphincter type: Ultrasound detected 20 cases of sphincter anal fistula,40 cases of non-sphincter anal fistula;MRI detected 17 cases of sphincter anal fistula,43 cases of non-sphincter anal fistula;ultrasound + MRI detected sphincter type There were 27 cases of anal fistula and 33 cases of non-sphincter anal fistula.The sensitivity of the three methods for diagnosis of sphincter anal fistula was statistically significant(P<0.05).The sensitivity of ultrasound+MRI for diagnosis of sphincter anal fistula(96.00%)was higher than the single ultrasound(68.00%)and MRI(64.00%)examination(P<0.05).The difference between accuracy and specificity of the three methods for the diagnosis of sphincter anal fistula was not statistically significant(P>0.05).3.sphincter type: ultrasound detected sphincter anal fistula in 19 cases,non-sphincter anal fistula in 41 cases;MRI detected sphincter anal fistula in 18 cases,non-sphincter anal fistula in 42 cases;ultrasound + MRI detected 21 cases of anal fistula and 39 cases of non-sphincter anal fistula.The sensitivity and accuracy of the three methods for diagnosis of sphincter anal fistula were statistically significant(P<0.05).The sensitivity and accuracy of sphincter anal fistula diagnosed by the Ultrasound+MRI(100.00%,100.00%)were higher than single ultrasound(66.67%,80.00%),MRI(71.43%,85.00%)examination(P<0.05);The difference in specificity comparison of three methods for the diagnosis of sphincter anal fistula was not statistically significant(P>0.05).4,sphincter type: Ultrasound detected 11 cases of sphincter supra-type anal fistula,49 cases of non-sphincter anal fistula;MRI detected 10 cases of sphincter anal fistula,50 cases of non-sphincter anal fistula;ultrasound + MRI detected 16 cases of anal fistula and44 cases of non-sphincter anal fistula.The sensitivity,accuracy and specificity of the three methods for the diagnosis of sphincter anal fistula were not statistically significant(P>0.05).in conclusionUltrasound+MRI can take into account the advantages of ultrasound and MRI and make up for each other,which thereby can improve the detection rate of internal mouth,branch/absic cavity,and the sensitivity of sphincter anal fistula.Besides,it can also increase the sensitivity and accuracy of sphincter anal fistula.In this way,Ultrasound+MRI is able to provide more comprehensive and accurate anatomical information,which is beneficial to reduce intraoperative sphincter injury and postoperative recurrence,and has high application value.