In Acute Stroke, Can CT Perfusion-Derived Cerebral Blood Volume Maps Substitute for Diffusion-Weighted Imaging in Identifying the Ischemic Core?
In Acute Stroke, Can CT Perfusion-Derived Cerebral Blood Volume Maps Substitute for Diffusion-Weighted Imaging in Identifying the Ischemic Core?
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DOI：
10.1371/journal.pone.0133566
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发表时间：
2015-07-20
期刊：
影响因子：
3.7
通讯作者：
Yoo, Albert J.
中科院分区：
文献类型：
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作者：
Copen, William A.;Morais, Livia T.;Yoo, Albert J.
背景和目的在疑似急性缺血性卒中患者的治疗中，越来越多的证据表明测量不可逆损伤的“缺血核心”体积的重要性。“在临床环境中进行这项工作的金标准方法是弥散加权磁共振成像（DWI），但许多作者认为，来自计算机断层扫描灌注成像（CTP）的局部脑血容量（CBV）图可以替代DWI。我们试图确定DWI和CTP衍生的CBV图在测量核心容积方面是否等效。方法58例疑似脑卒中患者在症状发作6小时内接受了CTP和DWI检查。我们使用三种方法测量低CBV病变体积：“客观绝对”，即CBV低于六个已发表的绝对阈值（0.9-2.5 mL/100 g）的组织体积;“客观相对”，其六个阈值（51%-60%）是平均对侧CBV的分数;和“主观”，其中两名放射科医生（R1，R2）主观概述病变。我们评估了每种方法、阈值和放射科医师检测梗死的敏感性和特异性，以及每种方法高估或低估DWI核心体积的程度。此外，在后续CT或MRI的32例患者的子集中，我们测量的CBV或DWI定义的核心病变的比例超过了后续梗死体积，和最大量，这发生在72%（42/58）的患者DWI是积极的。CBV图在识别DWI阳性患者方面的灵敏度/特异性对于两种客观方法和所有阈值均为100%/0%，对于R1为43%/94%，对于R2为83%/44%。客观绝对阈值的平均核心高估为156-699 mL，客观相对阈值的平均核心高估为127-200 mL。对于R1和R2，平均+/- SD主观高估分别为-11 +/- 26 mL和-11 +/- 23 mL，但个体患者的主观容积与DWI容积的差异高达117和124 mL。评价者之间关于CBV图上是否存在梗死的一致性较差（kappa = 0.21）。由6个客观绝对CBV阈值定义的核心病变超过81%-100%患者的随访梗死体积，高达430-1002 mL。在91%的患者中，客观相对阈值产生的核心估计值超过随访体积，高达210-280 mL。在18%和26%的病例中，R1和R2定义的主观病变分别超过随访体积71和15 mL。只有1的23 DWI病变（4%）超过最终梗死体积，由3 mL. ConclusionCTP衍生CBV地图不能可靠地替代DWI测量核心体积，甚至建立哪些患者有DWI病变。
Background and PurposeIn the treatment of patients with suspected acute ischemic stroke, increasing evidence suggests the importance of measuring the volume of the irreversibly injured "ischemic core." The gold standard method for doing this in the clinical setting is diffusion-weighted magnetic resonance imaging (DWI), but many authors suggest that maps of regional cerebral blood volume (CBV) derived from computed tomography perfusion imaging (CTP) can substitute for DWI. We sought to determine whether DWI and CTP-derived CBV maps are equivalent in measuring core volume.Methods58 patients with suspected stroke underwent CTP and DWI within 6 hours of symptom onset. We measured low-CBV lesion volumes using three methods: "objective absolute," i.e. the volume of tissue with CBV below each of six published absolute thresholds (0.9-2.5 mL/100 g), "objective relative," whose six thresholds (51%-60%) were fractions of mean contralateral CBV, and "subjective," in which two radiologists (R1, R2) outlined lesions subjectively. We assessed the sensitivity and specificity of each method, threshold, and radiologist in detecting infarction, and the degree to which each over-or underestimated the DWI core volume. Additionally, in the subset of 32 patients for whom follow-up CT or MRI was available, we measured the proportion of CBV- or DWI-defined core lesions that exceeded the follow-up infarct volume, and the maximum amount by which this occurred.ResultsDWI was positive in 72% (42/58) of patients. CBV maps' sensitivity/specificity in identifying DWI-positive patients were 100%/0% for both objective methods with all thresholds, 43%/94% for R1, and 83%/44% for R2. Mean core overestimation was 156-699 mL for objective absolute thresholds, and 127-200 mL for objective relative thresholds. For R1 and R2, respectively, mean +/- SD subjective overestimation were -11 +/- 26 mL and -11 +/- 23 mL, but subjective volumes differed from DWI volumes by up to 117 and 124 mL in individual patients. Inter-rater agreement regarding the presence of infarction on CBV maps was poor (kappa = 0.21). Core lesions defined by the six objective absolute CBV thresholds exceeded followup infarct volumes for 81%-100% of patients, by up to 430-1002 mL. Core estimates produced by objective relative thresholds exceeded follow-up volumes in 91% of patients, by up to 210-280 mL. Subjective lesions defined by R1 and R2 exceeded follow-up volumes in 18% and 26% of cases, by up to 71 and 15 mL, respectively. Only 1 of 23 DWI lesions (4%) exceeded final infarct volume, by 3 mL.ConclusionCTP-derived CBV maps cannot reliably substitute for DWI in measuring core volume, or even establish which patients have DWI lesions.