| Objective:The MRI manifestations of the surrounding structures of normal anorectal tissues,analyze the MRI manifestations of patients with perianal abscess,anal fistula,rectal cancer,hemorrhoids,proctitis,anal fissure and constipation,compare the differences between different diseases and normal tissues,and analyze the effect of MRI on the diagnosis,classification and staging of different diseases,so as to provide guidance for clinicians in MRI diagnosis and improving technical level.Method:168 patients who met the criteria from January 2020 to 2021 were collected as the research object,of which 56 patients without anorectal and perirectal tissue diseases were used as the control group,112patients with different anorectal and perirectal tissue related diseases were used as the observation group.In this group,38 patients with perianal abscess,18 patients with anal fistula,20 patients with hemorrhoids,10 patients with rectal cancer,11 patients with proctitis,8 patients with anal fissure and 7 patients with constipation.The thickness and height of the internal anal sphincter,the lower part of the external anal sphincter skin,the superficial part of the external anal sphincter and the deep part of the external anal sphincter,the average thickness of the levator ani muscle,the sciatic rectal space,the internal and external sphincter space,the lateral and anterior and posterior diameters of the pelvic rectal space,the anorectal angle and the posterior angle of the puborectalis muscle were compared in the control group.The thickness and height of the internal anal sphincter,the lower part of the external anal sphincter skin,the superficial part of the external anal sphincter,the deep part of the external anal sphincter,the average thickness of the levator ani muscle,the sciatic rectal space,the internal and external sphincter space,the lateral and anterior and posterior diameters of the pelvic rectal space,the anorectal angle and the posterior angle of the puborectalis muscle were compared between the observation group and the control group.At the same time,the accuracy of MRI diagnosis of different diseases and the coincidence rate of different disease stages and types in the observation group were statistically analyzed.Result:(1)The thickness of internal anal sphincter in normal population is(2.01±0.41)mm,the upper and lower height of internal anal sphincter is(36.76 ± 5.17)mm,the thickness of lower skin of external anal sphincter is(4.15 ± 1.58)mm,the upper and lower height is(6.68 ± 2.16)mm,the thickness of superficial external anal sphincter is(5.29 ± 1.89)mm,the upper and lower height is(20.80 ± 4.41)mm,the thickness of deep external anal sphincter is(4.71 ± 1.46)mm,and the upper and lower height is(25.99 ± 2.69)mm,The thickness of levator ani muscle was(6.68 ± 2.17)mm,the transverse diameter of sciatic rectal space was(35.07 ± 13.18)mm,the anterior posterior diameter was(41.84 ± 8.42)mm,the internal and external sphincter space in the control group was(2.44 ± 0.71)mm,the transverse diameter of pelvic rectal space was(43.75 ± 9.89)mm,the anterior posterior diameter was(46.72 ± 10.99)mm,the straight intestinal angle of anal canal was(110.99 ±19.98)°,and the posterior angle of puborectal muscle was(84.76 ± 19.68)°.(2)In the control group,there was no significant difference in the age of male patients and female patients(P>0.05);The thickness of internal anal sphincter was(2.02 ± 0.58)mm in men and the height of internal anal sphincter was(38.45 ± 4.48)mm in women,which were(1.37 ± 0.41)mm and(35.12 ± 3.71)mm respectively(P<0.05).There was no significant difference in age,sex and height of internal anal sphincter between the two groups(P>0.05);The thickness of internal anal sphincter in patients with perianal abscess,anal fistula,proctitis,anal fissure and constipation was greater than that in the control group(P<0.05);There was no significant difference in the thickness of internal anal sphincter between hemorrhoids and rectal cancer patients and the control group(P>0.05).(3)In the control group,the subcutaneous thickness of the external anal sphincter in male patients was(4.18±1.54)mm,the upper and lower height was(7.58±1.45)mm,the superficial thickness of the external anal sphincter was(5.34±1.78)mm,the upper and lower height was(21.87±3.28)mm,the deep thickness of the external anal sphincter was(4.87 ± 1.58)mm,the upper and lower height was(26.65±2.87)mm,and the subcutaneous thickness of the external anal sphincter in female patients was(4.05±1.05)mm,the upper and lower height was(5.28 ± 2.78)mm,The thickness of the superficial part of the external anal sphincter is(5.06 ± 2.01)mm,and the upper and lower height is(18.08 ± 5.87)mm.The thickness of the deep part of the external anal sphincter is(4.66 ± 1.24)mm,and the upper and lower height is(25.87±2.65)mm.In the control group,the thickness and height of the lower part of the skin of the external anal sphincter,the superficial part of the external anal sphincter and the deep part of the external anal sphincter in men were greater than those in women,and the difference was statistically significant(P<0.05).The thickness and height of the lower part of the external anal sphincter skin,the superficial part of the external anal sphincter and the deep part of the external anal sphincter in the observation group were significantly higher than those in the control group(P<0.05);There was no significant difference in the thickness and height of the lower part of the skin of the external anal sphincter,the superficial part of the external anal sphincter and the deep part of the external anal sphincter between the observation group and the control group(P>0.05).(4)In the control group,the male internal and external sphincter space was(2.56 ± 0.98)mm,the transverse diameter of sciatic rectal space was(35.57±11.21)mm,the anterior posterior diameter was(42.24±9.71)mm,the transverse diameter of pelvic rectal space was(45.89 ± 9.76)mm,and the anterior posterior diameter was(49.59±13.87)mm.The female internal and external sphincter space was(2.01±0.89)mm,the transverse diameter of sciatic rectal space was(34.56±15.56)mm,the anterior posterior diameter was(40.57 ±10.89)mm,the transverse diameter of pelvic rectal space was(42.67 ± 11.94)mm,and the anterior posterior diameter was(41.68±10.65)mm.In the control group,there was no significant difference in the transverse diameter and anterior posterior diameter of internal and external sphincter space,sciatic rectal space and pelvic rectal space between men and women(P>0.05).There was significant difference in the internal and external sphincter space between the observation group and the control group(P<0.05),and there was no significant difference in the transverse diameter and anterior posterior diameter of sciatic rectal space and pelvic rectal space between the observation group and the control group(P>0.05).There was no significant difference in the transverse diameter and anterior posterior diameter of sciatic rectal space and pelvic rectal space between the patients with perianal abscess,rectal cancer,hemorrhoids,proctitis,anal fissure and constipation and the control group(P>0.05).(5)In the control group,the thickness of levator ani muscle was(6.51 ± 2.54)mm,the anorectal angle was(111.64 ± 19.12)° and the posterior angle of puborectal muscle was(85.67 ± 16.74)° in male patients.The thickness of levator ani muscle in female patients was(6.89 ± 1.54)mm,the anorectal angle was(110.68 ± 20.17)° and the posterior angle of puborectal muscle was(83.27 ± 19.54)° respectively.There was significant difference in the thickness of levator ani muscle between men and women(P<0.05),and there was no significant difference in anorectal angle and posterior angle of puborectalis muscle(P>0.05).There was no significant difference in the thickness of levator ani muscle between the control group and the observation group(P>0.05).The angle of anorectum becomes smaller in patients with constipation,and the posterior angle of puborectalis muscle in patients with constipation increased significantly compared with the control group(P<0.05).Perianal abscess,anal fistula,rectal cancer,proctitis,hemorrhoids There was no significant difference in anorectal angle and posterior angle of puborectal muscle between the patients with anal fissure and the control group(P>0.05).(6)MRI has a high accuracy in the diagnosis of perianal abscess,anal fistula,rectal cancer and constipation in the observation group,but it has a poor effect in the diagnosis of proctitis,hemorrhoids and anal fissure.The diagnostic accuracy of MRI in different types of perianal abscess and anal fistula is high,which can reach 100%.The diagnostic accuracy of MRI in stage Ⅰ rectal cancer is low,which is 50%.The diagnostic accuracy of MRI in stageⅡ and Ⅲ rectal cancer can reach 100%.Conclusion:(1)Under MRI images,the thickness and height of the internal anal sphincter,the lower part of the external anal sphincter skin,the superficial part of the external anal sphincter,the deep part of the external anal sphincter,the average thickness of the levator ani muscle,the sciatic rectal space,the internal and external sphincter space,the lateral and anterior posterior diameters of the pelvic rectal space,the angle of the anal canal and the posterior angle of the puborectalis can be well distinguished.(2)Patients with perianal abscess and anal fistula may show thickening of the internal and external sphincter of the anus on MRI due to inflammatory stimulation and other factors;Thickening of internal anal sphincter in patients with proctitis,hemorrhoids and constipation;Anorectal angle and posterior angle of puborectal muscle in constipation patients increased;The space between internal and external sphincter was widened in patients with anal fistula.(3)MRI has high diagnostic accuracy for perianal abscess,anal fistula and other diseases,but low diagnostic accuracy for hemorrhoids,anal fissure and other diseases.(4)MRI has a high coincidence rate for the classification of perianal abscess and anal fistula,a low coincidence rate for stage I rectal cancer,and a high coincidence rate for stageⅡ and Ⅲ rectal cancer. |
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