磁共振弥散张量成像鉴别诊断超急性与急性缺血性脑梗死

目的 评价磁共振弥散张量成像(DTI)在超急性与急性缺血性脑梗死鉴别诊断中的临床应用价值。方法 回顾分析我院经临床及MRI诊断的单侧超急性期(18例)和急性期(27例)缺血性脑梗死患者的DTI图像。分析DTI序列各项异性指数(FA)、容积比各项异性(VRA)、平均弥散系数(DCavg)及衰减指数(Exat)参数图,并选取病灶、近病灶边缘脑组织(BTCI)及相应对侧为ROI,记录各ROI参数值并计算病灶-对侧各参数相对值。同时以病灶及对侧ROI为种子点重建弥散张量纤维束图。比较病灶、BTCI与相应对侧间各参数值的差异,分析病灶-对侧各参数相对值在超急性与急性脑梗死间的差异。结果 急性缺血性脑梗死DTT DCavg、DTT FA图均可观察到纤维束损伤表现;超急性脑梗死仅DTT DCavg图可观察到损伤表现,DTT FA图未见明显改变。超急性和急性脑梗死病灶DCavg值均低于对侧,Exat值均高于对侧(P均<0.05),而FA和VRA值仅在急性期低于对侧(P<0.05)。超急性期脑梗死BTCI区FA、VRA和Exat值较对侧增高(P<0.05),DCavg值较对侧降低(P<0.05)。急性期脑梗死病灶-对侧FA、VRA和DCavg相对值均低于超急性期(P<0.05)。对于鉴别超急性和急性脑梗死,ROC曲线分析示病灶-对侧FA、VRA和DCavg相对值最佳诊断界值分别为0.852、0.886和0.541;对应诊断敏感度均为100%,特异度分别为90.5%、100%和71.4%。结论 临床可将FA、VRA、DCavg及Exat值综合运用于发病时间不明确的超急性与急性缺血性脑梗死的鉴别诊断,从而有助于选择合理的治疗方案。

Diffusion tensor imaging in differential diagnosis of hyper-acute and acute ischemic cerebral infarction

Objective To evaluate the clinical application value of diffusion tensor imaging (DTI) in differential diagnosis of hyper-acute and acute ischemic cerebral infarction.Methods DTI images of unilateral hyper-acute (18 cases) and acute (27cases) ischemic cerebral infarction diagnosed by clinic and MRI were analyzed retrospectively.ROIs were set on infarction lesions,brain tissue close to infarction lesions (BTCI) and corresponding contra,and DTI parameters of fractional anisotropy (FA),volume ratio anisotropy (VRA),average diffusion coefficient (DCavg) and exponential attenuation (Exat) were recorded,the relative parameters value of infarction lesion to contra were calculated.Meanwhile,the DTT images based on the seed points (infarction lesion and contra) were reconstructed.Parameter value of infarction lesions,BTCI and corresponding contra were compared,and the differences of relative parameters values between hyper-acute and acute cerebral infarction were analyzed.Results Both DTT DCavg and DTT FA images of acute ischemic cerebral infarction could showed the manifestation of fasciculi damaged.However,only DTT ADavg showed the damage in hyper-acute ischemic cerebral infarction.The DCavg value of hyper-acute and acute cerebral infarction lesions was lower and the Exat value was higher than contra (P<0.05).Compared with contra,the FA and VRA value of cerebral infarction lesions reduced in acute infarction (P<0.05).Compared with contra,the FA,VRA and Exat value of BTCI increased and DCavg value decreased in hyper-acute infarction (P<0.05).The relative FA,VRA and DCavg value of acute infarction lesion to contra were all lower than thoes of hyper-acute (P<0.05).For the differential diagnosis of hyperiacute and acute cerebral infarction,ROC curve showed the best diagnosis cut off value of relative FA,VRA and DCavg were 0.852,0.886 and 0.541,respectively.The corresponding diagnostic sensitivity were all 100%,diagnostic specificity were 90.5%,100% and 71.4%,respectively.Conclusion The FA,VRA,DCavg and Exat value can be used in differential diagnosis of hyper-acute and acute ischemic cerebral infarction without clear onset time,and help to select the reasonable treatment protocols.