MR imaging of corpus callosal injuries]

The MR imaging and CT findings of corpus callosal injury were analyzed in 32 of 224 patients with acute head injuries. MR imaging was more sensitive than CT in the detection of callosal injuries. All 9 hemorrhagic lesions were visualized on both MR imaging and CT. Fifteen of 23 nonhemorrhagic lesions were not visualized on CT, although all nonhemorrhagic lesions were visualized on MR imaging. Twenty-four lesions of the corpus callosum were located in the splenium, but no lesion was located in the rostrum. Diffuse axonal shear injuries were visualized in 25 patients with callosal injury as associated traumatic lesions. Twenty-three patients with callosal injury had low initial Glasgow Coma Scale scores (less than 9), but 9 patients had high scores. Associated diffuse axonal shear injuries, especially in the brain stem could be a possible explanation for this difference. MR imaging is useful to detect traumatic lesions of the corpus callosum.     

Trauma to the corpus callosum: MR features

The frequency, distribution, and appearance of corpus callosum injuries were evaluated with MR and CT in a prospective study of 78 patients with acute (n = 63) and chronic (n = 15) head injuries. Traumatic lesions of the corpus callosum were detected in 47% of patients. MR was significantly (p less than .001) more sensitive than CT in the detection of callosal injuries. MR and CT visualized 100% and 27%, respectively, of the traumatic callosal lesions that were detected in the study population. The majority of lesions were located in the splenium but a few were also found in the body and genu. Patients with callosal injuries had a significantly higher incidence of primary brainstem injury (p less than .02) as well as a greater number of subcortical gray-matter (p less than .05) and diffuse axonal "shear" (p less than .001) lesions. In addition, patients with callosal injuries had a significantly higher incidence of traumatic lesions of the septum pellucidum (p less than .007) and fornix (p less than .001). Intraventricular hemorrhage occurred significantly more often (p less than .002) in patients with callosal injuries, especially if traumatic lesions of the fornix or septum pellucidum were also present. Patients with callosal injuries had significantly lower initial Glasgow Coma Scale scores (mean, 6.6) than those without injuries (mean, 10.7) (p less than .001). Injury to the corpus callosum occurs much more often with nonfatal head injuries than had been believed previously.     

Prediction of recovery from a post-traumatic coma state by diffusion-weighted imaging (DWI) in patients with diffuse axonal injury

Introduction To determine whether diffusion-weighted magnetic resonance (MR) imaging findings combined with initial clinical factors indicate the depth of shearing lesions in the brain structure and therefore relate to coma duration in diffuse axonal injury (DAI). Methods A total of 74 adult patients (48 male and 26 female) with DAI were examined with conventional MR imaging and diffusion-weighted MR imaging between 2 hours and 20 days after injury. Apparent diffusion coefficient (ADC) maps were obtained and the mean ADC values of each region of interest (ROI) were measured using MRI console software. The involvement of the brainstem, deep gray matter, and corpus callosum was determined for each sequence separately as well as for the combination of all sequences. The correlations between MR imaging findings indicating the presence of apparent brain injury combined with initial clinical factors were determined. Results Clinical characteristics, such as initial score on the Glasgow coma scale (GCS), age and number of all lesions, and ADC scores were predictive of the duration of coma. Conclusion It was possible to predict post-traumatic coma duration in DAI from cerebral MR imaging findings combined with clinical prognostic factors in the acute to subacute stage after head injury. Age, ADC scores, GCS score and number of lesions were highly significant in predicting coma duration. The technique presented here might provide a tool for in vivo detection of DAI to allow the prediction of the coma duration during the early stages in patients with traumatic brain injury. This paper is funded by Guangdong Provincial Department of Science and Technology, China (Grant No. 2005B33801010).     

MR imaging of head trauma: review of the distribution and radiopathologic features of traumatic lesions

The distribution and extent of traumatic lesions were prospectively evaluated with MR imaging in 40 patients with closed head injuries. Primary intraaxial lesions were classified according to their distinctive topographical distribution within the brain and were of four main types: (1) diffuse axonal injury (48.2%), (2) cortical contusion (43.7%), (3) subcortical gray-matter injury (4.5%), and (4) primary brainstem injury (3.6%). Diffuse axonal injury most commonly involved the white matter of the frontal and temporal lobes, the body and splenium of the corpus callosum, and the corona radiata. Cortical contusions most frequently involved the inferior, lateral, and anterior aspects of the frontal and temporal lobes. Primary brainstem lesions were most commonly seen in the dorsolateral aspects of the rostral brainstem. The pattern and distribution of primary lesions seen by MR were compared with those expected from previous pathologic studies and found to be quite similar. Our data and review of the literature would also indicate that MR detects a more complete spectrum of traumatic lesions than does CT. Secondary forms of injury (territorial arterial infarction, pressure necrosis from increased intracranial pressure, cerebral herniation, secondary brainstem injury) were also visible by MR in some cases. The level of consciousness was most impaired in patients with primary brainstem injury, followed by those with widespread diffuse axonal injury and subcortical gray-matter injury. The best MR imaging planes, pulse sequences, and imaging strategies for evaluating and classifying traumatic lesions were evaluated, and the mechanisms by which traumatic stresses result in injury were reviewed. MR was found to be superior to CT and to be very effective in the detection of traumatic head lesions and some secondary forms of injury. While T2-weighted images were most useful for lesion detection, T1-weighted images proved to be most useful for anatomic localization and classification.     

Diffuse axonal injury associated with chronic traumatic brain injury: evidence from T2*-weighted gradient-echo imaging at 3 T

BACKGROUND AND PURPOSE: Diffuse axonal injury is frequently accompanied by tissue tear hemorrhages. We examined whether high field strength T2*-weighted gradient-echo imaging performed during the chronic stage of traumatic brain injury may have advantages in the evaluation of diffuse axonal injury as compared with T1- and T2-weighted MR imaging. METHODS: Prospective MR imaging of 66 patients (age range, 17-57 years) was performed using a 3-T system 3 to 292 months (median, 23.5 months) after traumatic brain injury. T1-, T2-, T2*-hypointense and T2-hyperintense foci of 1- to 15-mm diameter were registered in 10 brain regions by two readers separately. Foci that appeared hypointense both on the T1- and T2- and/or on the T2*-weighted images were defined as traumatic microbleeds. RESULTS: For 46 (69.7%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds. Hyperintense foci were observed on the T2-weighted images of only 15 (22.7%) patients. T2*-weighted imaging showed significantly more traumatic microbleeds (P =.000) than did T1- and T2-weighted imaging. Interobserver agreement was strong (kappa = 0.79, tau = 0.749, P =.000). For 14 (21.2%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds in the corpus callosum, whereas for only two (3%), hyperintense callosal lesions were seen on the T2-weighted images. Although a significant correlation existed between the total amount and callosal appearance of traumatic microbleeds and Glasgow Coma Scale scores (P =.000), no correlation existed with extended Glasgow Outcome Scale scores. CONCLUSION: T2*-weighted gradient-echo imaging at high field strength is a useful tool for the evaluation of diffuse axonal injury during the chronic stage of traumatic brain injury. Diffuse axonal injury-related brain lesions are mainly hemorrhagic. The relevance of diffuse axonal injury for long-term clinical outcome is uncertain.     

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。     

Corpus callosum lesions after closed head injury in children: MRI,clinical features and outcome

Summary Thirty-four children who sustained moderate to severe closed head injury underwent magnetic resonance imaging (MRI). Eight (24%) had MRI evidence of corpus callosum injury, most commonly within the posterior body and splenium. In contradistinction to reports in adults, there was no definite relationship between callosal injury and lower initial Glasgow Coma Scale scores, nor was there a significantly higher incidence of primary brain-stem lesions, diffuse axonal shear injury or intraventricular hemorrhage. In none of these 8 children did the initial admission computed tomography show evidence of callosal injury. Callosal injuries on MRI are not necessarily a poor prognostic finding, the majority of the 8 children showing good functional recovery.     

Traumatic lesions of corpus callosum: early multidetector CT findings

Corpus callosum is one of the common sites of brain lesion, whose involvement is an indicator of a more severe prognosis, produced by traumatic shearing stresses resulting in diffuse axonal injury (DAI). Computed tomography (CT) in acute phase is considered to have a limited role for the detection of non-hemorrhagic or petechial hemorrhagic DAI lesions. New generation multidetector CT scanners allow faster acquisition of thinner-slice images and post-processing reformations. Three patients with severe closed head trauma underwent CT examinations using a multidetector scanner, a few hours and the day after injury. The review of original images with narrow window width and integration with reconstruction of thinner slices from raw-data and post-processing multiplanar reformations (MPR) helped to detect the onset of hypodense or predominantly hypodense areas of corpus callosum, not present at admission and afterwards confirmed by MRI.     

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。     

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。     

颅脑伤后持续性植物状态100例脑组织的核磁共振变化

目的：为了明确创伤性持续性植物状态（PVS）脑损伤的部位、性质和脑组织结构的变化特征。方法：采用MRI对创伤性PVS患者100例进行病灶的定位、定性断定，且进行统计。结果：100例PVS患者中，发现病灶1154处（出血性462处，非出血性692处），每例5－19处，平均约12处病灶。弥漫性脑白质轴索损伤和胼胝体损伤94例，脑干背侧损伤87例，基底节和丘脑损伤分别为52例和32例，大脑皮层伤50例（以额、颞叶居多），海马旁伤47例。结论：创伤性PVS主要是由于弥漫性轴索损伤。统计结果表明，临床与MRI密切结合对确诊脑外伤后PVS有重要意义。     

MRI诊断非出血性脑弥漫性轴索损伤的临床价值

目的探讨MRI对非出血性脑弥漫性轴索损伤的临床应用价值.材料和方法回顾性分析36例非出血性脑弥漫性轴索损伤的MRI资料.结果全部病例行CT和MRI检查.36例非出血性挫伤灶中,位于胼胝体16例,脑干8例,小脑蚓部2例,放射冠8例,内囊4例,额、颞叶20例.CT扫描仅2例(5.6%)显示出低密度灶.MRIT1WI均呈等或略低信号,T2WI呈高信号.结论MRI是诊断非出血性脑弥漫性轴索损伤最佳的影像学手段,对临床正确诊断本病具有重要的应用价值.     

胼胝体非出血性挫伤的MRI诊断(附四例报告)

目的报告4例胼胝体非出血性挫伤的MRI表现。材料与方法回顾性分析4例胼胝体非出血性挫伤的MRI资料;3例为车祸伤,1例为坠落伤,都进行了CT和MR非增强检查。结果4例胼胝体挫伤灶2例位于压部、1例位于干部、1例累及胼胝体大部。CT扫描胼胝体区未见异常密度。MR图像上均表现为等或略低T1WI信号与明显高T2WI信号,未见出血信号。SE或FSET2WI(轴位或矢状位)对病变显示清楚,而FLAIR序列则能抑制脑脊液的高信号、使病变显示更加突出。1例4个月后MR检查显示挫伤灶演变为类似脑脊液信号的软化灶。4例中3例还合并颅内多处脑挫伤和血肿。结论胼胝体非出血性挫伤较少见,CT检查难以发现病灶MR是其最佳的影像学检查手段,轴位与矢状位SE或FSET2WI是显示挫伤灶的主要序列,FLAIR序列对病灶的显示更佳。本病典型的MRI表现是胼胝体区T1WI等或略低信号、T2WI高信号,无出血信号;胼胝体非出血性挫伤可合并颅内多发性外伤性改变。     

Acquired lesions of the corpus callosum: MR imaging

In this pictorial review, we illustrate acquired diseases or conditions of the corpus callosum that may be found by magnetic resonance (MR) imaging of the brain, including infarction, bleeding, diffuse axonal injury, multiple sclerosis, acute disseminated encephalomyelitis, Marchiafava-Bignami disease, glioblastoma, gliomatosis cerebri, lymphoma, metastasis, germinoma, infections, metabolic diseases, transient splenial lesion, dilated Virchow-Robin spaces, wallerian degeneration after hemispheric damage and focal splenial gliosis. MR imaging is useful for the detection and differential diagnosis of corpus callosal lesions. Due to the anatomical shape and location of the corpus callosum, both coronal and sagittal fluid-attenuated inversion recovery images are most useful for visualizing lesions of this structure.     

Use of multisequence 3.0-T MRI to detect severe traumatic brain injury and predict the outcome

Objective:

The aim of this study was to evaluate multisequence 3.0-T MRI in the detection of severe traumatic brain injury (sTBI) and in predicting the outcome.

Methods:

32 patients with sTBI were prospectively enrolled, and multisequence 3.0-T MRI was performed 4–8 weeks post injury. Quantitative data were recorded on each sequence. The ability to display the parenchymal lesions was compared with that of 64-slice spiral CT. The clinical and radiological results were correlated with the Glasgow Outcome Scale Extended scores 6 months after injury.

Results:

3.0-T MRI could display more lesions than CT, especially when the lesion was deeply located. The lesion volumes and diffuse axonal injury (DAI) scores were different between good and poor outcome groups on fluid attenuated inversion recovery (p < 0.05). The apparent diffusion coefficient (ADC) values of the splenium of the corpus callosum and brain stem were also different (p < 0.05). Patients with unfavourable outcome showed a significantly higher volume of haemorrhage on susceptibility-weighted imaging than those with favourable outcomes and had haemorrhages generally located more deeply. Logistic regression analysis revealed that the location of haemorrhage and the ADC values of the splenium of the corpus callosum were independent risk factors for poor outcome, with an overall predictive accuracy of 91.4%.

Conclusion:

The joint use of conventional and advanced sequences of 3.0-T MRI can comprehensively detect the pathological changes occurring after sTBI. Haemorrhagic and non-haemorrhagic DAIs in deep structures strongly suggest poor outcome.

Advances in knowledge:

This article improves the understanding of advanced MRI sequences in the detection of patients with sTBI and prediction of prognosis.     

CT and MR imaging of neuroaxonal leukodystrophy presenting as early-onset frontal dementia

CT and MR imaging showed diffuse changes of the frontal white matter and genu of the corpus callosum with minimal atrophy and no contrast enhancement in a 41-year-old woman with progressive dementia. Brain biopsy disclosed axonal spheroids and gliosis in the white matter without macrophage or inflammatory infiltration or vessel abnormalities consistent with neuroaxonal leukodystrophy. This disease can be suspected on CT and MR imaging findings but requires neuropathologic examination to be diagnosed.     

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     

The corpus callosum: white matter or terra incognita

The corpus callosum is the largest white matter structure in the brain, consisting of 200-250 million contralateral axonal projections and the major commissural pathway connecting the hemispheres of the human brain. The pathology of the corpus callosum includes a wide variety of entities that arise from different causes such as congenital, inflammatory, tumoural, degenerative, infectious, metabolic, traumatic, vascular and toxic agents. The corpus callosum, or a specific part of it, can be affected selectively. Numerous pathologies of the corpus callosum are encountered during CT and MRI. The aim of this study is to facilitate a better understanding and thus treatment of the pathological entities of the corpus callosum by categorising them according to their causes and their manifestations in MR and CT imaging. Familiarity with its anatomy and pathology is important to the radiologist in order to recognise its disease at an early stage and help the clinician establish the optimal therapeutic approach.     

MRI of head injury using FLAIR

We studied the utility of fluid-attenuated inversion-recovery (FLAIR) MRI in the investigation of head injury. We examined 56 patients with head injuries with T2-weighted spin-echo (SE) and FLAIR sequences. In all cases, the sensitivity of FLAIR images to equal or superior to that of conventional SE images to the traumatic lesions. In 9 cases, central diffuse axonal injury of the fornix and corpus callosum could be seen only on sagittal FLAIR images. Received: 1 April 1996 Accepted: 20 June 1996     

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.