核素排便造影在小儿便秘诊断中的应用价值

Scintigraphic assessment of the anorectal function in children with idiopathic constipation

目的 研究核素排便造影方法在小儿便秘诊断和疾病程度判定方面的应用价值。方法 对 2 5例特发性便秘患儿和 11例正常儿进行核素排便造影检查。根据直肠肛管排空曲线可计算出残留率、排空率和半排时间等反映排便能力的客观指标 ,根据采集的直肠肛管图像可获得反映耻骨直肠肌功能的静息、收缩和排便状态下的直肠肛管角。所有患儿同时进行结肠传输实验和X线排便造影检查。结果 便秘患儿直肠肛管排空曲线平直或下降缓慢 ,而正常儿的排空曲线为快速弧形下降曲线。便秘患儿排便能力明显下降 ,正常儿半排空时间、排空率和残留率分别是 1 97± 0 86min、78 30 %± 12 0 3%和 2 0 5 0 %± 7 6 7% ,而便秘患儿这三项分别为 15 16± 3 6 7min、4 4 84 %± 14 0 0 %和 5 3 5 2 %± 15 0 2 % ,两组差异有显著意义 (P <0 0 5 )。根据结肠传输实验结果有 6例患儿为慢传输型便秘 ,17例为出口梗阻型便秘 ,出口梗阻型便秘患儿的排便能力明显低于慢传输型便秘。结论 核素排便造影可以对便秘进行准确诊断和疾病程度判定 ,同时也能对耻骨直肠肌功能进行准确评价 ,而且具有操作简单、安全、受放射线照射量很低等优点 ,是评价直肠肛管排便功能的重要客观检测方法。

Objective The ability of the rectum to evacuate is valuable information in patients with constipation, or those who find defecation difficult. However, few published studies are available to evaluate this ability in most common examinations of anorectal function. A new, low-radiation, real-time scintigraphic technique has been used by several investigators to outline the 'neo-rectum' following ileoanal pouch anastomosis and the efficiency of rectal evacuation in adult patients with constipation. There was no similar report about the abilities of rectal evacuation in children with constipation. The aim of this study was to investigate the value and reliability of isotope defecography as an objective method for evaluation of anorectal function in patients with chronic idiopathic constipation. Methods Twenty five patients (10 were male and 15 were female, range of age was 5-15 years, mean age 8.99 years) suffering from chronic idiopathic constipation and 11 normal children were assessed by isotope defecography. The radiopharmaceuticals used were rehydrated potato labelled with 200 MBq 99mTcO - 4. The volume of the potato paste used in each subject was determined by prior balloon proctometrogram studies, which measured the maximum rectal capacity. The patient was seated upright on a commode, and the computer was then set for the dynamic acquisition of 3-second images over 5 min per session. Using a region of interest program on computer, the dynamic radioactivity in anorectum during defecation showed as emptying curves by computer. The half defecation time, the rectal emptying rate and the residual rate could be calculated from the rectal emptying curves. The anorectal angles were measured from the images of anorectum during resting, squeezing and evacuation. All patients underwent X-ray defecography and colonic transit time measurement simultaneously. Results The rectal emptying curves showed a prompt evacuation in normal children, but it disappeared in most of patients with idiopathic constipation. The abilities of evacuation were damaged severely in patients. In normal group the half defecation time, the rectal emptying rate and the residual rate were 1.97±0.86 minutes, 78.30%±12.03% and 20.50%±7.67%, respectively, whereas they were 15.16±3.67 minutes, 44.84%±14.00% and 53.52%±15.02%, respectively, in patients group. There were significant differences between two groups (P<0.05). According to the results of colonic transit time there were 6 patients with slow transit constipation, 17 patients with outlet dysfunction and 2 patients with normal colonic transit time. The abilities of evacuation were more seriously impaired in patients with outlet dysfunction compared with those patients with slow transit constipation. For the isotope defecography the mean anorectal angles at resting in patient group and normal group were 109±12°and 101±17°. There were no significant differences in anorectal angles between patient group and normal group or by both methods of isotope defecography and X-ray defecography. The correlation coefficients for anorectal angles at resting, squeezing and evacuation were 0.87, 0.82 and 0.73, respectively. Conclusion The isotope defecography can be used to evaluate the anorectal function and the ability of defecation dynamically, also it was simple and safe because of the low dose radiation involved.