成人环状软骨水平的下咽部正常CT表现及临床意义

Normal CT manifestations of hypopharynx at the level of cricoid cartilage in adults

目的探讨CT图像上环状软骨水平的下咽部的正常表现及其临床意义。方法回顾性分析84名正常成人下咽部的CT图像，将下咽部分成梨状窝区、咽后壁区和环后区，把下咽部的环后区划分为如下3个层面，即环状软骨上缘层面（经环杓关节水平）；环状软骨中部层面；环状软骨下缘层面。分别测量环后区的前后径、横径及其前、后壁的厚度；观察黏膜下脂肪层的变化，并对周围相毗邻的其他结构和脂肪组织进行观察、分析。测量数据采用t检验和χ^2检验进行统计学分析。结果环后区的后壁较同层面的前壁厚（0．9±0．4）mm。男性环后区的横径较女性宽（4.5±0．3）mm；横径在性别上差异有统计学意义[在环状软骨上缘层面，男性的横径为（38．6±3．3）mm，女性的为（34．4±2．5）mm，t=6．26，P〈0．05；在环状软骨中部层面，男性的横径为（33．6±3．6）mm，女性的为（28.9±2.8）mm，t=6．36，P〈0．01；在环状软骨下缘层面，男性的横径为（28．6±3．1）mm，女性的为（24．0±2．1）mm，t=7．52，P〈0．01]。环状软骨上缘水平的环后区的横径较环状软骨下缘水平的横径宽（10．1±2．4）mm。黏膜下的脂肪层从环状软骨上缘[显示率为81．0％（68／84）]至环状软骨下缘[显示率为23、8％（20／84）]逐渐减少。在环后区周围毗邻的脂肪组织中，每一层面环后区后侧的脂肪组织显示的概率最小，而其左侧的脂肪组织最易显示，这种差异具有统计学意义[在环状软骨上缘层面，环后区左、右、后方毗邻脂肪组织的显示率分别为77.4％（65／84）、72.6％（61／84）、28．6％（24／84），χ^2=24．64，中部层面，各显示率分别为89.3％（75／84）、75.0％（63／84）、34．5％（29／84），χ^2=24．76，在环状软骨下缘层面，各显示率分别为95．2％（80／84）、88．1％（74／84）、52．4％（44／84），χ^2=13．59，P值均〈0．01]。结论环状软骨水平的下咽部的正常CT表现及变化在对下咽部疾病的诊查中起着重要作用。

Objective To approach the normal manifestations of the hypopharynx of the adults at the level of cricoid cartilage as seen on CT images, and to evaluate their clinical value. Methods Eighty-four CT images of the normal hypopharynx were reviewed. The hypopharynx was divided into three regions ： （ 1 ） the piriform sinus, （2） the retropharynx area, and （ 3 ） the postcricoid region. The postcricoid region of hypopharynx was subdivided into three levels as follows ： （ 1 ） the upper margin slice of the cricoid cartilage at the cricoarytenoid joint level, （2） the middle portion slice of the cricoid cartilage, and （ 3 ） the inferior margin slice of the cricoid cartilage. The anteroposterior and transverse diameters, and anterior and posterior wall thicknesses in the postcricoid region were measured. Depiction of the layers of the musculature and adjacent fat planes was evaluated. Statistical comparisons of measured results were made by using t test and χ^2 test. Results The posterior wall tended to be （0. 9 ± 0.4 ） mm thicker than the anterior wall. The average transverse extension of the postcricoid musculature was （4. 5±0. 3） mm shorter in female than that in male at CT images. There were statistically significant differences related to sex （ at the upper margin level of the cricoid cartilage： the transverse extension was （38. 6 ± 3.3 ）mm in male, （34.4 ± 2. 5 ） mm in female, t = 6. 26,P 〈 0. 05 ; at the middle portion level of the cricoid cartilage ： （ 33. 6 ± 3. 6） mm in male, （28.9±2. 8） mm in female t = 6.36, P 〈 0.01; at the inferior margin level of the cricoid cartilage： （ 28.6± 3. 1 ） mm in male, （ 24. 0 ± 2. 1 ） mm in female, t = 7.52, P 〈 0. 01 ）. The transverse diameter tended to taper （ 10. 1 ± 2.4 ） mm from the upper cricoid slice level to the lower cricoid slice level. Demonstration of the intramural fat planes of the postcricoid region decreased from the upper [ 81.0% （68/84） ] to the lower region [ 23.8% （ 20/84 ）] of the cricoid cartilage. In fat planes around the postcricoid region at all levels, the posterior fat plane was seen least frequently, and the left-sided fat plane was seen most frequently. There was a statistically significant difference at every level （at the upper margin level of the cricoid cartilage, the visibilities of the left-sided, the right-sided, and the posterior fat plane around the postcricoid region were 77.4% （ 65/84 ）, 72.6% （ 61/84 ）, and 28. 6% （ 24/84 ）, χ^2 = 24. 64, P 〈0. 01 ; at the middle portion level of the cricoid cartilage, the visibilities were 89.3% （75/84）, 75.0% （63/84）, and 34. 5% （29/84） , χ^2 =24. 76, P 〈0. 01 ; at the inferior margin level of the cricoid cartilage： the visibilities were 95. 2% （ 80/84）, 88. 1% （ 74/84 ）, and 52. 4% （ 44/84 ）, χ^2 = 13.59, P 〈 0. 01. Conclusion Knowledge of the normal appearances and variations of the hypopharynx at the level of cricoid cartilage is essential in detecting abnormalities in this area.