Abstract:

Objective To explore the value of apparent diffusion coefficient (ADC) in differentiating stages and in determining ischemic penumbra of acute cerebral infarction. Methods A total of 62 patients who were diagnosed as acute cerebral infarction by clinical and imaging and underwent magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) examinations were enrolled into study. All cases were divided into <6 h group, 6~24 h group, 24~48 h group and 48~72 h group according to the period after onset by MRI detection. ADC values of the lesions, contralateral normal area, lesion center and edge in each time period were measured. Results Ten cases who’s onset time were less than 6 hours, the positive rate of conventional MRI was 0 (0/10) while the DWI detection rate was 100% (10/10); 52 cases who’s onset time were from 6~72 h, which included 6~24 h (27 cases), 24~48 h (13 cases), 48~72 h (12 cases), the positive rate of conventional MRI was 88.4% (46/52) while the DWI positive detection rate was 100%

(52/52). The ADC values of the lesions and contralateral normal area in each time period were: <6 h (0.601±0.079, 1.261±0.085) ×10-3mm2/s, 6~24 h (0.623±0.097, 1.152±0.083) ×10-3mm2/s, 24~48 h (0.635±0.103, 1.036±0.112) ×10-3mm2/s, 48~72 h (0.631±0.082, 1.225±0.097) ×10-3mm2/s; ADC values of the lesions and contralateral normal area in different time had significant difference (P =0.006, 0.007, 0.008 and 0.017). ADC values showed no significant differences in different groups. The ADC values of lesion center and edge were: <6 h (0.547±0.089, 0.624±0.096) ×10-3mm2/s, which had significant difference (P =0.027); 6~24 h (0.572±0.074, 0.647±0.107) ×10-3mm2/s, which had significant difference (P =0.032); 24~48 h (0.615±0.104, 0.636±0.082) ×10-3mm2/s, which had no significant difference; 48~72 h (0.631±0.081, 0.625±0.102) ×10-3mm2/s, which had no significant difference. Conclusion DWI can find the responsible lesions of acute cerebral infarction early and accurately, and it also can identify the lesion center and edge (<24 h), the edge of lesion may be ischemic penumbra, but it has little significance in differentiating different stages of acute cerebral infarction (0~3 d).

Key words: Cerebral infarction; Magnetic resonance imaging; Diffusion-weighted imaging

摘要：

目的 探索表观弥散系数（apparent d iffusion c oefficient，ADC）在急性缺血性卒中患者分期及判断缺 血半暗带中的价值。 方法 收集经临床和影像确诊为急性缺血性卒中的患者，根据行磁共振成像（magnetic r esonance i magi ng，MRI）检查距起病时间的长短分为＜6 h组，6～24 h组，24～48 h组，48～72 h组，所有患者在 治疗前行MRI弥散加权像（diffusion-wei ghted i magi ng，DWI）检查，评估DWI图像及常规MRI图像显示病变 的情况，测定各时间段病灶的ADC、健康对侧相应位置的ADC值、病灶中心及边缘的ADC值。 结果 共纳入62例患者，发病时间<6 h的病例10例，常规MRI图像阳性检出率为0（0/10），DWI阳性检 出率为100%（10/10）；发病6～24 h的病例27例、24～48 h的病例13例、48～72 h的病例12例，总共52例， 其中常规MRI阳性检出率为88.4%（46/52），DWI阳性检出率为100%（52/52）。不同时间段病灶侧ADC 值与健侧ADC值分别为：＜6 h组（0.601±0.079，1.261±0.085）×10-3mm2/s，6～24 h组（0.623±0.097， 1.152±0.083）×10-3mm2/s，24～48 h组（0.635±0.103，1.036±0.112）×10-3mm2/s，48～72 h组 （0.631±0.082，1.225±0.097）×10-3mm2/s；不同时间段病灶侧ADC值与健侧ADC值之间均有显著性 差异（P分别为0.006，0.007，0.008和0.017）。不同时间段组病灶侧ADC值之间无显著差异。不同时 间段组病灶中心及边缘的ADC值分别为：＜6 h组（0.547±0.089，0.624±0.096）×10-3mm2/s，两者之 间有显著性差异（P =0.027）；6～24 h组（0.572±0.074，0.647±0.107）×10-3mm2/s，两者之间有显 著性差异（P =0.032）；24～48 h组（0.615±0.104，0.636±0.082）×10-3mm2/s，两者之间无显著差异； 48～72 h组（0.631±0.081，0.625±0.102）×10-3mm2/s，两者之间无显著差异。 结论 DWI的ADC值可以早期准确发现急性缺血性卒中的责任病灶，而且可以区分<24 h梗死灶的中 心和边缘，边缘区可能为缺血半暗带，但对于急性缺血性卒中（0～3 d）的细化分期意义不大。

关键词: 脑梗死; 磁共振成像; 弥散加权成像