Traumatic brain injury: diffusion-weighted MR imaging findings.

BACKGROUND AND PURPOSE: Diffuse axonal injury (DAI) accounts for a significant portion of primary intra-axial lesions in cases of traumatic brain injury. The goal of this study was to use diffusion-weighted MR imaging to characterize DAI in the setting of acute and subacute traumatic brain injury. METHODS: Nine patients ranging in age from 26 to 78 years were examined with conventional MR imaging (including fast spin-echo T2-weighted, fluid-attenuated inversion-recovery, and gradient-echo sequences) as well as echo-planar diffusion-weighted MR imaging 1 to 18 days after traumatic injury. Lesions were characterized as DAI on the basis of their location and their appearance on conventional MR images. Trace apparent diffusion coefficient (ADC) maps were computed off-line with the diffusion-weighted and base-line images. Areas of increased signal were identified on the diffusion-weighted images, and regions of interests were used to obtain trace ADC values. RESULTS: In the nine patients studied, isotropic diffusion-weighted images showed areas of increased signal with correspondingly decreased ADC. In one case, decreased ADC was seen 18 days after the initial event. CONCLUSION: Decreased ADC can be demonstrated in patients with DAI in the acute setting and may persist into the subacute period, beyond that described for cytotoxic edema in ischemia.     

应用DWI和ADC预测弥漫性轴索损伤患者昏迷时间

目的:探讨磁共振扩散成像(DWI)和表观扩散系数(ADC)在预测弥漫性轴索损伤(DAI)患者昏迷时间的应用。方法:将57例伤后2h~20d、临床与影像诊断均符合弥漫性轴索损伤(DAI)的患者,进行磁共振常规 T1WI、T2WI和DWI检查,在其DWI表观扩散系数图上测定兴趣区ADC值。昏迷时间预测模型的建立采用逐步回归分析。结果:分析结果显示预测模型预测的昏迷时间与患者实际昏迷的时间非常接近。结论:昏迷时间预测模型可为临床提供昏迷时间预测。     

Whole-brain apparent diffusion coefficient in traumatic brain injury: correlation with Glasgow Coma Scale score

BACKGROUND AND PURPOSE: Patients with traumatic brain injury (TBI) and low Glasgow coma scale (GCS) scores may have severe injury associated with cellular disruption that can be studied with whole-brain apparent diffusion coefficient (ADC) histograms. We retrospectively studied this hypothesis and correlated ADC with GCS. METHODS: Twenty-one patients (37.81 +/- 41.3 years) with TBI were enrolled: Group A had normal MR imaging findings but low GCS scores (n = 6). Group B had brain stem injury with low GCS scores (n = 6). Group C had cortical lesions with normal GCS scores (n = 5), and group D had cortical lesions with low GCS scores (n = 4). Eleven control subjects were enrolled (32.7 +/- 19.2 years). Whole-brain ADC maps and histograms were generated and normalized for each subject. Mean and peak ADCs were determined. A one-sided t test was performed for each parameter. Average GCS scores and corresponding peak and mean ADCs were correlated. RESULTS: Peak histogram values significantly differed between controls and groups A, B, and D (P <.0019, P <.00129, and P <.0148, respectively). In groups A and D, values were significantly skewed compared with control values. Mean ADC was significantly different between the control ADC and group A (P <.013) but not group C. In each group, peak ADC and GCS score were strongly correlated (R(2) = 0.67). CONCLUSION: Whole-brain peak ADCs and GCS scores are significantly correlated in patients with TBI. Although conventional MR images were normal, ADC independently indicated TBI and better represents the degree of neurologic dysfunction.     

弥漫性轴索损伤影像学分析

目的探讨弥漫性轴索损伤(DAI)影像学表现及诊断价值。方法回顾性分析2010年9月~2015年9月26例DAI患者临床与CT、低场MRI资料,其中男性19例,女性7例;年龄16~65岁,平均34.6岁。患者均有创伤史,道路交通伤22例,高处坠落伤3例,重物打击伤1例。伤后均立即出现昏迷或持续昏迷,入院时格拉斯哥昏迷量化表(GCS)评分,重度(≤8分)4例,中度(9~12分)6例,轻度(13~15分)16例。结果 26例均使用CT及低场MRI诊断,主要表现为颅内不同部位单发或多发点状病变,DAI病灶分为出血灶和非出血灶,主要分布在灰白质交界区、基底节区、丘脑、深部白质、胼胝体等区域。低场MRI敏感性明显高于CT(χ2=14.567,P=0.012),各序列中GRE-T2*WI对出血灶检出数(97.59%)最高,DWI对非出血灶检出数(95.18%)最高。结论 CT及低场MRI对DAI的早期诊断很有价值,低场MRI能弥补CT检查阴性颅脑损伤而症状较重患者,能明显提高颅脑损伤的检出率、诊断率,能有效避免漏诊,提示预后。     

Traumatic brain stem injury: MR imaging

Eighty-seven patients with acute (n = 70) or chronic (n = 17) head injuries were prospectively studied with magnetic resonance (MR) imaging and computed tomography (CT) to characterize the frequency and nature of traumatic brain stem injury (BSI). Forty-eight traumatic lesions were identified in 36 patients. Of 36 patients, 35 had neurologic findings that corroborated the radiographic impression of BSI. T1- and T2-weighted MR images demonstrated a significantly higher number of lesions than did CT. Patients with BSI had a significantly higher frequency of corpus callosum and diffuse axonal "shear" lesions. The number of cortical contusions and extraaxial hematomas was similar in both groups. The mean Glasgow Coma Scale (GCS) scores at admission were significantly lower in patients with evidence of BSI on MR images. Patients with primary BSI had lower initial GCS scores, a longer duration of coma, more diffuse axonal "shear" lesions, and a higher frequency of corpus callosum injury than patients with secondary BSI. The location of primary and secondary lesions was significantly different. Overall, MR imaging was more helpful than CT in detecting, localizing, and characterizing BSI.     

3T磁敏感成像在弥漫性轴索损伤中的应用及与GCS评分的相关性

目的探讨3 T磁敏感加权成像(SWI)及扩散加权成像(DWI)对弥漫性轴索损伤(DAI)的诊断价值及其与格拉斯哥昏迷量表(GCS)评分的相关性。资料与方法对40例DAI患者,均行常规T1WI、T2WI、液体衰减反转恢复(FLAIR)、DWI及SWI,对所得数据在工作站用软件进行图像后处理,并分析、统计。结果在40例DAI患者中,磁共振常规序列共发现36个出血灶,在DWI上共发现44个出血灶,在SWI上共发现376个出血灶,GCS评分13～15分25例,9～12分11例,≤8分4例,GCS评分较低者其出血灶数较多,且出血灶范围较大者其GCS评分亦较低。结论在DAI患者中,SWI能较常规序列及DWI上显示更多脑内微小出血灶,GCS评分高低与出血灶数目多少及大小有明显相关性。SWI可为临床早期诊断DAI和在治疗方案的制定及评估预后中提供很大帮助。     

Diffusion-weighted MRI in diffuse axonal injury of the brain

The goal of this study was to identify and describe the different types and patterns of tissue injury which are encountered by diffusion-weighted imaging (DWI) in diffuse axonal injury (DAI) of the brain. The DWI data sets of 98 patients who suffered from a closed-head injury were retrospectively evaluated. Medical records were reviewed to rule out pre-existing neurological diseases. Lesions were studied for their DWI signal characteristics and lesion size or extension. Traumatic lesions were classified into three categories depending on their signal characteristica on DWI and apparent diffusion coefficient (ADC) maps: type 1, DWI- and ADC-hyperintense most likely representing lesions with vasogenic edema; type 2, DWI-hyperintense, ADC-hypointense indicating cytotoxic edema; type 3, central hemorrhagic lesion surrounded by an area of increased diffusion. According to the size and extent of lesions, injury was classified into three groups: group A, focal injury; group B, regional/confluent injury; and group C, extensive/diffuse injury. Our study showed that diffusion-weighted imaging differentiates between lesions with decreased and increased diffusion in patients with DAI. Different degrees of tissue injury extent were noticed. Future prospective studies should study if this additional information can be used as a predictor of injury reversibility, final outcome and prognosis.     

联合多种MRI序列评估弥漫性轴索损伤

目的:探讨弥漫性轴索损伤(DAD在MR扩散加权成像,T2加权液体衰减翻转恢复序列(T2- FLAIR)及增强梯度回波T2*加权血管成像序列(ESWAN)上的影像学特征及各序列的诊断价值,合理规划DAI患者的MRI检查方案.方法:10例DAI患者在伤后两周内行DWI、T2-FLAIR及ESWAN检查,DWI为3个垂直方向...     

磁敏感加权成像在脑外伤中的应用

目的:评价高分辨率的磁敏感加权成像(SWI)技术检测脑外伤患者中出血性病灶的能力.方法:34例成年脑外伤患者,根据临床格拉斯哥昏迷评分(GCS)分为轻度及中重度脑外伤.所有的患者行CT、常规MRI及弥散张量成像(DTI)和SWI检查,分别检测各方法所示患者脑内出血灶数量.结果:SWI共显示1040个出血灶,较常规序列及DTI显示更多,差异有明显统计学意义.SWI病灶数与GCS评分有明显相关性(r=-0.533,P=0.001).结论:SWI较常规MRI及DTI能检测出更多及更小的出血灶,可以进一步提高对弥漫性轴索损伤(DAI)的诊断,帮助临床医生早期诊断、治疗、治疗监测及评估预后情况.     

Conspicuity of diffuse axonal injury lesions on diffusion-weighted MR imaging

OBJECTIVE: (1) To detect diffuse axonal injury (DAI) lesions by diffusion-weighted imaging (DWI), as compared with fluid-attenuated inversion recovery (FLAIR) imaging and (2) to evaluate hemorrhagic DAI lesions by b0 images obtained from DWI, as compared with gradient-echo (GRE) imaging. METHODS: We reviewed MR images of 36 patients with a diagnosis of DAI. MR imaging was performed 20 h to 14 days (mean, 3.7 days) after traumatic brain injury. We evaluated: (1) conspicuity of lesions on DWI and FLAIR and (2) conspicuity of hemorrhage in DAI lesions on b0 images and GRE imaging. RESULTS: DWI clearly depicted high-signal DAI lesions. The sensitivity of DWI to lesional conspicuity in DAI lesions was almost equal to that of FLAIR. The sensitivity of b0 images to identification of hemorrhagic DAI lesions was inferior to that of GRE. CONCLUSION: DWI is as useful as FLAIR in detecting DAI lesions. GRE imaging is still the superior tool for the evaluation of hemorrhagic DAI.     

Diffusion-weighted imaging in the evaluation of watershed hypoxic-ischemic brain injury in pediatric patients

The purpose of our study was to determine the usefulness of echo-planar diffusion-weighted imaging (EPDI) in the evaluation of watershed hypoxic-ischemic brain injury in pediatric patients. Eighteen patients ranging in age from 3 weeks to 12 years were evaluated for evidence of ischemic/infarction changes on conventional MR and EPDI. Included in the study group were five patients with sickle cell disease, four with congenital heart disease, four with hypotensive episodes with various etiologies, three with sepsis, and two with encephalitis or meningitis. Patients were examined 2 h to 6 days after the initial insult, with follow-up studies in four patients at 1 to 62 days after the initial examination. After conventional MR imaging (T1, FSE T2, and FLAIR), diffusion-weighted MR imaging was performed using high-speed, single-shot EP techniques with TR 6000, TE 144, matrix 96 × 128, FOV 23.3 × 31 and five b values of 0, 160, 360, 640, and 1,000 s/mm². EPDI demonstrated abnormally increased signal in watershed ischemic/infarction zones in all initial cases. Apparent diffusion coefficients (ADC) were obtained in 59 lesions. When compared with radiographically normal (on EPDI) contralateral brain parenchyma, 45 demonstrated a relatively decreased ADC, while eight had normal ( ± 10 %) and six had increased ADC. In four cases, signal abnormalities on EPDI were not seen or exceeded that seen with conventional MR imaging. In the remaining cases, signal abnormalities were obvious on EPDI and more subtle on conventional MR imaging. Follow-up studies demonstrated resolution of abnormal EPDI signal with persistent abnormalities on conventional imaging in some cases, while others revealed an increase in size or number of EPDI signal abnormalities, suggesting ongoing acute ischemic/infarctive changes. EPDI is a rapid, sensitive technique for detecting watershed ischemic/infarction changes in pediatric patients with hypoperfusion episodes, at times before such changes are apparent on conventional MR images and/or are clinically apparent. Received: 5 January 2001/Accepted: 1 February 2001     

MR imaging with quantitative diffusion mapping of tacrolimus-induced neurotoxicity in organ transplant patients

Our objective was to investigate brain MR imaging findings and the utility of diffusion-weighted (DW) imaging in organ transplant patients who developed neurologic symptoms during tacrolimus therapy. Brain MR studies, including DW imaging, were prospectively performed in 14 organ transplant patients receiving tacrolimus who developed neurologic complications. In each patient who had abnormalities on the initial MR study, a follow-up MR study was performed 1 month later. Apparent diffusion coefficient (ADC) values on the initial MR study were correlated with reversibility of the lesions. Of the 14 patients, 5 (35.7%) had white matter abnormalities, 1 (7.1%) had putaminal hemorrhage, and 8 (57.1%) had normal findings on initial MR images. Among the 5 patients with white matter abnormalities, 4 patients (80.0%) showed higher than normal ADC values on initial MR images, and all showed complete resolution on follow-up images. The remaining 1 patient (20.0%) showed lower than normal ADC value and showed incomplete resolution with cortical laminar necrosis. Diffusion-weighted imaging may be useful in predicting the outcomes of the lesions of tacrolimus-induced neurotoxicity. Electronic Publication     

弥散加权成像在弥漫性轴索损伤伤情判断和预后评价中的应用价值

目的 探讨弥散加权成像(DWI)对弥漫性轴索损伤(DAI)患者伤情判断和预后评估的价值. 方法 回顾性分析29例DAI患者临床影像学资料及伤后6个月随访结果,比较DWI与常规MRI序列脑内病灶的检出数,分析DWI中不同部位病灶数与患者相应GCS、GOS评分的关系. 结果 (1)29例各序列脑内DAI病灶平均检出数为:DWI(19.24±5.72)个,FLAIR(14.41±4.50)个,T2WI(10.58±3.79)个,T1WI(4.83±2.11)个.DWI的病灶检出数最高,与其他序列比较差异有统计学意义(P<0.05).(2)脑中轴(胼胝体、基底节区、脑干)病灶数与GCS、GOS评分旱负相关(P<0.05),总病灶数及外周病灶数与GCS、GOS评分均无相关性(P>0.05).结论 DWI为DAI病灶检出的敏感序列,脑巾轴病灶检出数可作为DAI患者伤情判断和预后评估的客观指标.     

Diffusion-weighted echo-planar MR imaging of CNS involvement in systemic lupus erythematosus

RATIONALE AND OBJECTIVES: The purpose of this study was to determine the range of findings at diffusion-weighted magnetic resonance (MR) imaging in patients with systemic lupus erythematosus (SLE) and central nervous system involvement. MATERIALS AND METHODS: Diffusion-weighted MR images were reviewed in 20 patients with SLE and correlated with clinical symptoms and findings at computed tomography, conventional MR imaging, MR angiography, or conventional angiography. RESULTS: Diffusion-weighted MR imaging showed acute or subacute lesions in nine of 20 patients (45%). In the other 11, it showed no abnormal findings or chronic lesions. In four of the nine patients with lesions, diffusion-weighted imaging primarily showed hyperintense lesions with decreased apparent diffusion coefficient (ADC), which indicates acute or subacute infarcts. In four other patients, it primarily showed iso- or slightly hyperintense lesions with increased ADC, suggesting vasogenic edema. In two of these four patients, the findings were consistent with hypertensive encephalopathy. In the other two, small hyperintense foci on diffusion-weighted images with decreased ADC were seen within the vasogenic edema. These foci presumably represent microinfarcts associated with SLE vasculopathy. In the ninth patient, diffusion-weighted imaging showed a small linear hyperintense lesion with normal ADC in the left parietooccipital region. CONCLUSION: Diffusion-weighted imaging shows primarily two patterns of acute or subacute parenchymal lesions in patients with SLE: acute or subacute infarction and vasogenic edema with or without microinfarcts.     

磁敏感加权成像在弥漫性轴索损伤中的应用价值

目的通过比较磁敏感加权成像(susceptibility weighted imaging,SWI)与常规MRI序列对弥漫性轴索损伤(diffuse axonal injury,DAI)病灶的显示情况,探讨SWI对DAI的诊断价值;比较SWI及常规MRI序列在检测DAI病灶数目及体积方面的差别,探讨SWI显示DAI病灶数目、体积与患者格拉斯哥昏迷评分(glasgow coma score,GCS)之间的相关性。资料与方法对36例临床确诊为DAI的患者分别行常规MRI及SWI扫描;常规MRI与SWI在显示病灶数目及体积方面分别采用U检验及配对t检验。结果 SWI显示DAI病灶分布于皮髓质交界以及白质区域,呈"斑点"状、"串珠"状、"线条"状明显低信号病灶;常规MRI序列检出96个病灶,SWI检出511个病灶,两种方法在检测病灶数目方面差异具有统计学意义(Z=-6.801,P=0.000)。常规序列检测病灶总体积约29.09 cm3,SWI显示病灶总体积约为66.95 cm3,两种方法在检测病灶总体积方面差异具有统计学意义(t=-7.916,P=0.000)。SWI显示病灶数目与患者GCS之间存在负相关性(r=-0.796,P=0.000);SWI显示病灶体积与患者GCS之间存在负相关性(r=-0.652,P=0.000)。结论 SWI在显示DAI病灶及评价患者病情方面优于常规MRI序列。     

磁共振DWI和ADC值在包膜期脑脓肿与坏死囊变性脑肿瘤鉴别诊断中的应用

目的探讨磁共振扩散加权成像(DWI)及表观扩散系数(ADC)值在包膜期脑脓肿与坏死囊变脑肿瘤鉴别中的临床应用价值。方法经手术病理证实的包膜期脑脓肿15例和坏死囊变脑肿瘤20例患者均经常规MRI扫描和DWI扫描,对比分析包膜期脑脓肿及坏死囊变脑肿瘤的DWI和ADC图表现,并测量脑脓肿脓腔及脑肿瘤坏死囊变区内的平均ADC值,进行统计学分析。结果包膜期脑脓肿脓腔在DWI上表现为高信号,ADC图呈低信号;脑肿瘤坏死囊变区在DWI上表现为低信号,ADC图呈高信号。所有脑脓肿的平均ADC值为(0.69±0.18)×10-3mm2/s,坏死囊变脑肿瘤的平均ADC值为(2.43±0.16)×10-3mm2/s,两者比较有显著性差异(P<0.01)。结论 DWI与ADC值测量能准确反映包膜期脑脓肿与坏死囊变脑肿瘤的不同液态性质,对其鉴别诊断有重要价值。     

背景抑制磁共振弥散成像(D WIBS)技术在肝脏局灶性占位性病变中的初步应用

目的:探讨背景抑制磁共振弥散成像(DWIBS)技术在肝脏局灶性占位性病变中的应用价值。方法:回顾性分析肝脏局灶性占位性病灶25例49个。其中肝细胞癌9例12灶,肝转移瘤6例18灶,肝囊肿7例16灶,肝血管瘤3例3灶的背景抑制磁共振弥散成像(b=600s/mm2),测量各病灶的表观弥散系数(ADC)值并进行比较,利用3D-MIP重建及黑白翻转技术,观察病变显示效果。结果:在b=600s/mm2的图像中,肝脏恶性肿瘤多表现为高信号;肝脏良、恶性肿瘤间差异具有统计学意义(P<0.05);肝细胞癌与肝转移瘤组间、肝囊肿与肝血管瘤组间无统计学差异(P>0.05)。背景抑制的DWI经MIP重建及黑白翻转技术,病变周围组织信号被抑制,得到类PET图像,25例49个病灶,均清晰显示。结论:背景抑制磁共振弥散加权成像在显示病灶方面有一定优势;应用DWI结合ADC值对于肝脏良、恶性占位病变有一定鉴别价值。     

Imaging findings in diffuse axonal injury after closed head trauma

Even in patients with closed head trauma, brain parenchyma can be severely injured due to disruption of axonal fibers by shearing forces during acceleration, deceleration, and rotation of the head. In this article we review the spectrum of imaging findings in patients with diffuse axonal injuries (DAI) after closed head trauma. Knowledge of the location and imaging characteristics of DAI is important to radiologists for detection and diagnosis. Common locations of DAI include: cerebral hemispheric gray-white matter interface and subcortical white matter, body and splenium of corpus callosum, basal ganglia, dorsolateral aspect of brainstem, and cerebellum. In the acute phase, CT may show punctate hemorrhages. The true extent of brain involvement is better appreciated with MR imaging, because both hemorrhagic and non-hemorrhagic lesions (gliotic scars) can be detected. The MR appearance of DAI lesions depends on several factors, including age of injury, presence of hemorrhage or blood-breakdown products (e. g., hemosiderin), and type of sequence used. Technical aspects in MR imaging of these patients are discussed. Non-hemorrhagic lesions can be detected with fluid attenuated inversion recovery (FLAIR), proton-density-, or T2-weighted images, whereas gradient echo sequences with long TE increase the visibility of old hemorrhagic lesions. Received 17 September 1997; Revision received 2 December 1997; Accepted 15 December 1997     

Diffusion tensor imaging as potential biomarker of white matter injury in diffuse axonal injury

BACKGROUND AND PURPOSE: Multiple biomarkers are used to quantify the severity of traumatic brain injury (TBI) and to predict outcome. Few are satisfactory. CT and conventional MR imaging underestimate injury and correlate poorly with outcome. New MR imaging techniques, including diffusion tensor imaging (DTI), can provide information about brain ultrastructure by quantifying isotropic and anisotropic water diffusion. Our objective was to determine if changes in anisotropic diffusion in TBI correlate with acute Glasgow coma scale (GCS) and/or Rankin scores at discharge. METHODS: Twenty patients (15 male, five Female; mean age, 31 years) were evaluated. Apparent diffusion coefficients (ADCs) and fractional anisotropy (FA) values were measured at multiple locations and correlated with clinical scores. Results were compared with those of 15 healthy control subjects. RESULTS: ADC values were significantly reduced within the splenium (Delta18%, P =.001). FA values were significantly reduced in the internal capsule (Delta14%; P <.001) and splenium (Delta16%; P =.002). FA values were significantly correlated with GCS (r = 0.65-0.74; P <.001) and Rankin (r = 0.68-0.71; P <.001) scores for the internal capsule and splenium. The correlation between FA and clinical markers was better than for the corresponding ADC values. No correlation was found between ADC of the internal capsule and GCS/Rankin scores. CONCLUSION: DTI reveals changes in the white matter that are correlated with both acute GCS and Rankin scores at discharge. DTI may be a valuable biomarker for the severity of tissue injury and a predictor for outcome.     

Acute bilateral basal ganglia lesions in diabetic uraemia: diffusion-weighted MRI

Methods We studied four patients with diabetes mellitus and chronic renal failure who developed sudden choreic movement disorders. The clinical manifestations, laboratory findings, MR imaging findings, and clinical outcome in each patient were evaluated. Results All four patients had long-term diabetes mellitus and severe azotaemia. Brain MR findings consisted of bilateral symmetric basal ganglia lesions, with decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images. All three patients who underwent diffusion-weighted MR imaging (DWI) showed signal intensities similar to those of the surroundings in regions corresponding to increased signal intensity on T2-weighted images, with slightly increased apparent diffusion coefficient (ADC) values. Two of the patients showed small focal areas of restricted diffusion within the basal ganglia lesions. After haemodialysis, follow-up MR imaging in all patients demonstrated that the basal ganglia lesions had regressed markedly, with some residual changes. The movement disorders also improved in all patients. Conclusion A syndrome associated with acute bilateral basal ganglia lesions in diabetic uraemic patients is rare, with reversible changes demonstrated by clinical and imaging findings. DWI showed that the bilateral basal ganglia lesions in this syndrome were primarily vasogenic in origin, although there were small foci of cytotoxic oedema within the lesions.