目的　准确认识鼻咽癌（ＮＰＣ）咽旁间隙改变的ＣＴ征象。方法　收集病理确诊的初诊ＮＰＣ３０例，同时行治疗前的ＣＴ和ＭＲＩ检查。结果　３０例ＮＰＣ咽旁间隙表现按ＣＴ所见分为以下四种情况，与其ＭＲＩ表现作对照观察统计如下：（ｌ）ＣＴ所见咽旁间隙正常者ＭＲＩ表现为前窄后宽的三角形线条状连续高信号脂肪影；（２）咽旁间隙ＣＴ表现为变窄伴线样低密影，在ＭＲＩ上表现为咽旁间隙的高信号脂肪影受压，但仍连续无中断；（３）ＣＴ所见咽旁间隙变窄且密度增高，在ＭＲＩ上表现为高信号脂肪影极度变窄，但仍可见连续；（４）ＣＴ所见咽旁间隙消失者，在ＭＲＩ上咽旁间隙被肿块占据，翼外肌推移，其内侧脂肪间隙消失，但翼内、外肌信号正常或不正常。结论（ｌ）ＣＴ上咽旁间隙变窄，且密度增高，但仍可见低于肌肉的线样影，肿块未突破咽旁间隙；（２）ＣＴ上咽旁间隙完全消失者，肿块可能跨过咽旁间隙达颞下窝。 Objective To accurately understand the CT features of nasopharyngeal carcinoma (NPC) parapharyngeal space. Methods Totally 30 newly diagnosed NPC patients were collected and examined by CT and MRI before treatment. Results The expression of parapharyngeal space in 30 cases was divided into the following four cases according to the findings of CT. The statistics of the MRI findings were as follows: (1) The MRI findings of normal parapharyngeal space on CT showed anterior narrow strip and narrow triangular strip (2) The parapharyngeal space CT showed narrowing with line-like low density, high pressure signal of fat on the parapharyngeal space on MRI, but still without interruption; (3) CT Seen parapharyngeal space narrowing and density increased in MRI showed high signal fat thinning extremely narrow, but still visible continuous; (4) disappearance of parapharyngeal space seen by CT, parapharyngeal space on the MRI was occupied by the tumor , Pterygoid muscle shift, the fat inside the gap disappears, but the wing, the outer muscle signal normal or abnormal. Conclusion (1) The parapharyngeal space of CT is narrowed and the density is increased, but the line-like shadow below the muscle is still visible. The mass does not break the parapharyngeal space. (2) The parapharyngeal space in CT is completely disappeared and the mass may cross Parapharyngeal space up to the infratemporal fossa.