Normal CT manifestations of hypopharynx at the level of cricoid cartilage in adults / 中华放射学杂志

ABSTRACT

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 ttest and x2 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. d±2. 5) mm in female, t = 6. 26,P < 0. 05 ; at the middle portion level of the crieoid 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) nun 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 levelDemonstration 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) ,x<'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) ,x<'2> =24. 76, P <0. 01 ; at the inferior margin level of the cricoid cartilagethe visibilities were 95.2% (80/84), 88. 1% (74/84), and 52. 4% (44/84), x<'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.