表观扩散系数值对急性一氧化碳中毒后迟发性脑病的诊断价值

The diagnostic value of apparant diffusion coefficient value on the delayed encephalopathy after acute carbon monoxide poisoning

目的探讨ADC值对急性CO中毒后迟发性脑病（DEACMP）的诊断价值。方法回顾性分析经临床确诊的32例DEACMP患者的临床和MR资料，同时选取头颅MRI表现正常的健康志愿者40名作为正常对照组。所有受试者均进行常规MR扫描及DWI，分别对称性测量苍白球、白质（侧脑室周围白质、半卵圆中心）、皮层（额叶、顶叶）的平均ADC值（ADCav）。32例DEACMP患者根据常规MRI上有无异常信号分为有异常信号DEACMP组（20例）、无异常信号DEACMP组（12例），所有患者跟踪随访1年以上，13例患者无明显症状，3例偶有轻微头痛、头晕（预后较好组）；15例有智能障碍、精神异常，1例反应迟钝、生活不能自理、大小便失禁（预后不良组）。DEACMP组与正常对照组、异常信号与无异常信号DEACMP组、无异常信号DEACMP组与正常对照组、预后较好组与预后不良组间各个部位ADC值的比较采用独立样本t检验。结果32例DEACMP患者20例有异常影像表现。MRI表现可分为3个类型：（1）脑白质受累型；（2）神经核团受累型；（3）皮层受累型。12例常规MRI上无肉眼所见异常信号。32例DEACMP患者ADCav值均下降，ADCav值[侧脑室周围白质（0．62±0．06）×10^-3mm2／s、苍白球（0．67±0．05）×10^-3mm2／s、半卵圆中心（0．57±0．07）×10^-3mm2／s]较正常对照组[（0．74±0．03）×10-3、（0．74±0．04）×106-3、（0．73±0．05）×10^-3mm2／s]降低（t值分别为2．82、2．89、2．98，P值均〈0．01）；有异常信号DEACMP组的ADCav值[侧脑室周围白质（0．58±0．08）×10^-3mm2／s、半卵圆中心（0．52±0．09）×10^-3mm^2／s]与无异常信号DEACMP组[（0．66±0．05）×10^-3、（0．62±0．06）×10^-3mm2／s]比较，差异有统计学意义（t值分别为4．45、3．98，P值均〈0．01）；无异常信号DEACMP组ADCav值[侧脑室周围白质（0．66±0．05）×10^-3mm2／s，半卵圆中心（0．62±0．06）×10^-3mm2／s]与正常对照组[（0．74±0．03）×10^-3、（0．73±0．05）×10^-3mm2／s]比较，差异有统计学意义（t值分别为2．45、3．72，P值均〈0．05）。预后不良组ADCav值[侧脑室周围白质（0．56±0．02）×10^-3mm2／s、半卵圆中心（0．50±0．06）×10^-3mm2／s]与预后较好组[（0．63±0．04）×10^-3、（0．58±0．05）×10^-3mm2／s]比较，差异有统计学意义（t值分别为6．19、4．12，P值均〈0．01）。结论白质区（尤其是半卵圆中心）ADC值降低对DEACMP诊断具有重要价值，对常规MRI有异常信号的DEACMP患者，定量ADCav值可以量化中毒程度，作为DEACMP的发生、发展及预后评估的参考；对有临床症状而常规MRI上无异常信号患者，ADC值是诊断DEACMP较敏感指标。

Objective To investigate the diagnostic value of ADC on delayed encephalopathy after acute carbon monoxide poisoning （DEACMP）. Methods Forty healthy subjects with normal head MRI appearance and 32 cases with DEACMP were recruited and scanned using MRI. ADC values in bilateral globus pallidus, cerebral white matter （peri-ventricle, centrum semioval ） and cortex were measured respectively. According to conventional MRI, 32 DEACMP patients were divided into abnormal and normal signal intensity groups, and followed up more than one year. Thirteen cases without evident symptoms and 3 cases with little headache and dizziness were good prognosis group. Fifteen cases with disturbance of intelligence and mental anomaly and one case with manifested unresponsive,inability in life selif-care, urinary and fecal incontinence were poor prognosis group. Independent samples t-test was used to compared all parts of brain ADC values between DEACMP group and normal control, abnormal and normal signal intensity groups, normal signal intensity group and normal control, good and poor prognosis groups. Results According to MRI findings, DEACMP were classified into three types： type 1： showing white matter involvement ; type 2 ： showing neural nuclei involvement and type 3 ： showing brain cortex involvement. The ADC values [ peri-ventricle white matter （0. 62 ± 0. 06） ×10^-3mm2/s, the globus pallidus （ 0. 67 ± 0. 05）×10^-3mm2/s,centrum semioval（0. 57 ±0. 07） ×10^-3mm2/s] in DEACMP group were statistically different with those [（0.74±0.03）×10^-3, （0.74 ±0.04） ×10^-3,（0.73 ±0.05） ×10^-3mm2/s] in normal people （ t = 2. 82,2.89,2. 98, P 〈 0. 01 ）. The ADC values [ peri-ventficle white matter （ 0. 58 ± 0. 08） ×10^-3mm2/s,centrum semioval（0. 52 ±0. 09）×10^-3mm2/s] in 20 cases with abnormal signal on routine MR1 were statistically different with the ADC values [ （0. 66 ± 0. 05 ） ×10^-3, （ 0. 62 ± 0. 06 ）×10^-3mm2/s] in 12 cases without abnormal signal （t = 4. 45,3.98, P 〈 0. 01 ）. The ADC values had statistical significace（P 〈0. 05） between 12 eases without abnormal on routine MRI and the normal people. In comparison with 16 cases [ peri-ventricle white matter （0. 63 ± 0. 04）×10^-3mm2/s, centrum semioval （0.58±0.05） ×10^-3mm2/s] in good prognosis group, the ADC value of 16 cases[（0.56±0.02） ×10^-3, （0. 50 -± 0. 06 ） ×10^-3mm2/s ] in poor group decreased significantly （ t = 6. 19,4. 12, P 〈 0. 01 ）. Conclusions The decreased ADC values of white matter （centrum semioval particularly）is of the important in diagnosing of the DEACMP. For cases with abnormal signal on routine MRI,the ADC values can be used to evaluate the degree of poisoning, to be used as the reference of occurrence, development and to be used to evaluate the prognosis of the diseases. For the other cases with clinical symptoms but without abnormal signal on routine MRI,ADC value is a very sensitive index.