脑血肿内血红蛋白与其MR成像关系的研究

目的：探讨脑血肿内血红蛋白与其ＭＲ成像的关系。材料与方法：用２５条犬建立２５个各期龄脑血肿模型进行ＭＲ成像观察，并对１９个血肿模型进行了血红蛋白的生化检测。结果：本研究进一步证实了血红蛋白的演变规律：氧合血红蛋白（ＨｂＯ２）→脱氧血红蛋白（ＤＨｂ）→高铁血红蛋白（ＭＨｂ）→含铁血黄素（Ｈ－Ｓ）。在演变过程中，ＨｂＯ２含量逐渐减少，ＤＨｂ在急性期含量最多并逐渐减少，而ＭＨｂ含量则逐渐增多，并在亚急性晚期和慢性期含量高达９０％以上。结论：脑血肿各阶段血红蛋白的形式及含量与其ＭＲ成像有直接的对应关系。     

脑血肿在低场MR中影像演变规律的研究──动物脑血肿模型观察结果

目的：了解脑血肿在低场ＭＲ中的影像演变规律。材料与方法：制作动物（狗）脑血肿模型共５个，３个为小模型，２个为大模型，按计划扫描。ＭＲ仪场强为０．０６４Ｔ。结果：与中高场ＭＲ仪结果相比较，急性期血肿于所有序列信号均较高，Ｔ２ＷＩ未见到低信号征象。慢性期末见低信号环。残腔期呈Ｔ１长Ｔ２信号，未见＂黑腔＂。此两期出现时间提前。超急性期表现与中高场机所见基本相同。仅１个大模型的亚急性期表现为＂周高中低＂信号，且存在时间较短。结论：脑血肿在低场强ＭＲ中的演变规律与中高场强机大体一致，不同之处主要在急性期、慢性期和残腔期的信号表现。造成的原因主要是Ｔ２ＰＲＥ效应与磁场强度有关。动物脑血肿模型更适用于早期血肿的研究。     

应用低场磁共振成像诊断高血压脑出血的探讨

讨论了２６３例高血压脑出血超急性期及急性期血肿在低磁场磁共振成像中的信号特征，在Ｔ１加权像表现为高信号，Ｔ２加权像为混杂信号，与中、高磁场ＭＲＩ图像有所不同。低磁场ＭＲＩ对显示超急性期及急性期脑出血有较高的诊断敏感性和准确性。     

硬膜下血肿的MRI诊断(附30例报告)

目的：评价ＭＲＩ对硬膜下血肿的诊断价值。方法：回顾分析３０例各期硬膜下血肿的ＭＲＩ表现。结果：１０例（３３．３％）为双侧同时发生硬膜下血肿。血肿多呈“新月形”，呈“双凸形”者，在冠状位，横轴位及矢状位观察分别为１４，４和６例。血肿急性期（≤２ｄ）呈等Ｔ１长Ｔ２信号；亚急性（３～１４ｄ）及慢性期（＞１４ｄ）呈短Ｔ１长Ｔ２信号，部分中心可见少许等Ｔ１信号。结论：ＭＲＩ检查各期硬膜下血肿均有明显的阳性改变，且慢性期血肿在ＣＴ上呈等或低密度，故笔者认为硬膜下血肿应首选ＭＲＩ检查。     

低场强MR对急性脑出血的诊断初探

目的探讨低场强ＭＲ用于急性脑出血检查的可行性以及其血肿的Ｔ１ＷＩ、Ｔ２ＷＩ的信号特点。材料与方法７例脑外伤,３例高血压性出血患者,均在急性期和超急性期内,用 ０． ２Ｔ西门子 Ｐ８ＭＲ机,ＳＥ系列,Ｔ１ＷＩ：ＴＲ／ＴＥ＝３００／１５、Ｔ２ＷＩ：ＴＲ／ＴＥ＝２５００／１２０ｍｓ。结果１０例病员其脑内血肿在Ｔ１ＷＩ均表现为等或等低混合信号,在Ｔ２ＷＩ均为均匀高或欠均匀高信号,部分通过ＣＴ验证。结论在急性期和超急性期的脑内血肿,Ｔ１ＷＩ表现为等或等低信号,Ｔ２ＷＩ为明显高信号。     

脑出血的低场强MRI信号变化及诊断价值

目的：报道脑出血的低场强ＭＲＩ信号变化及诊断价值。材料与方法：收集分析２５例脑出血的低场强ＭＲＩ表现，就血红蛋白在低场强ＭＲＩ中的信号变化进行研究，分析脑出血低场强ＭＲＩ特殊表现的理论依据，结合文献提出脑出血的低场强ＭＲＩ的诊断价值和限度。结果与结论：①亚急性期和慢性期开始阶段脑出血，Ｔ１ＷＩ出现高信号，ＭＲＩ具有特征性，可明确诊断；②由于ＭＲ能显示具有流空效应的异常血管和含铁血黄素沉积，对了解出血的原因大有帮助；③可多方位成像，对血肿定位准确；④无骨质伪影，对近颅底脑组织结构显示清，小脑、脑于等部位出血在ＭＲＩ上易于显示；⑤超急性期和急性期出血在低场强ＭＲＩ上缺乏特征性；⑥成像速度慢，达不到快速诊断的要求。     

脑静脉畸形MRI诊断

探讨脑静脉畸形的ＭＲＩ表现。材料与方法９例脑静脉畸形均有ＭＲＩ及ＭＲＡ检查,ＭＲＩ行常规平扫及轴位增强扫描。ＭＲＡ采用２Ｄ－ＴＯＦ或３Ｄ－ＭＯＴＳＡ法。结果小脑４例,额叶３例,颞叶１例,大脑大静脉瘤伴中线血管畸形１例。典型者引流静脉显示长Ｔ１短Ｔ２低信号流空影,髓静脉网呈长Ｔ１低信号长Ｔ２高信号。增强扫描呈“海蛇头”样表现,即多支细小扩张的髓静脉呈辐射状向１牺或２条上流静脉汇聚。ＭＲＡ可显示髓静脉     

弥漫性骨髓疾病的MRI诊断：附22例分析

本文分析了２２例经骨髓穿刺证实的弥漫性骨髓疾病的ＭＲＩ表现。其中儿童急性淋巴细胞性白血病（ＡＬＬ）１６例，成人髓细胞性白血病１例，神经母细胞瘤骨髓转移２例，多发性骨髓瘤２例，高雪氏病１例。对１６例ＡＬＬ进行了定量研究（Ｔ１和Ｔ２值测定）。对上述各种疾病的病理改变及ＭＲＩ表现进行了讨论。结果表明ＭＲＩ对评价弥漫性骨髓疾病具有重要临床价值。     

肿瘤样脑炎的MRI表现和Gd－DTPA增强的诊断价值

目的：研究肿瘤样脑炎的ＭＲＩ表现和Ｇｄ－ＤＴＰＡ增强的诊断价值。材料和方法：报告９例肿瘤样脑炎的ＭＲＩ所见，并与１８例脑星形细胞瘤的增强磁共振成像（ＣＥＭＲＩ）表现进行对比分析。结果：肿瘤样脑炎的非增强磁共振成像（ＮＣＭＲＩ）表现为长Ｔ１、长Ｔ２信号，缺乏特征性，其ＣＥＭＲＩ表现为（１）斑片状高信号，大小不一，强弱不一，散在分布。（２）单个或多个结节状增强，（３）脑膜线状增强。（４）血管壁套状增强。脑星形细胞瘤的典型ＭＲＩ表现为结节状增强或为伴有中心坏死的不规则花环状增强。结论：ＣＥＭＲＩ能反映肿瘤样脑炎的炎性渗出、肉芽肿形成、硬膜充血和血管周围炎的病理特点，对肿瘤样脑炎和脑星形细胞瘤的鉴别诊断有重要意义。     

小肝癌的磁共振成像诊断

笔者分析了经病理组织学证实的１８例小肝癌与７例非囊肿，非血管瘤良性病变（≤３．０ｃｍ）的ＭＲＩ（１．０Ｔ）表现。结果表明：Ｔ_１ＷＩ上稍低信号，等或稍高质子密度，Ｔ_２ＷＩ上稍高信号，内部信号不均匀，Ｔ_２值＜９０ｍｓ是小肝癌典型的ＭＲＩ表现。Ｔ_１ＷＩ稍低信号，等或稍低质子密度，Ｔ_２ＷＩ等或稍低信号是本组良性病变的ＭＲＩ征象。ＭＲＩ对本组病例的定性准确率约９２％。ＭＲＩ对小肝癌的诊断和鉴别诊断具有重要价值。     

Acute and subacute intracerebral hemorrhages: comparison of MR imaging at 1.5 and 3.0 T--initial experience

PURPOSE: To assess and describe the appearance of intracerebral hemorrhage (ICH) at 3.0-T magnetic resonance (MR) imaging as compared with the appearance of this lesion type at 1.5-T MR imaging. MATERIALS AND METHODS: Sixteen patients with 21 parenchymal ICHs were examined. ICHs were classified as hyperacute, acute, early subacute, late subacute, or chronic. Patients underwent 1.5- and 3.0-T MR imaging with T2-weighted fast spin-echo, fluid-attenuated inversion-recovery (FLAIR), and T1-weighted spin-echo (1.5-T) and gradient-echo (3.0-T) sequences within 4 hours of each other. The central (ie, core) and peripheral (ie, body) parts of the ICHs were analyzed quantitatively by using contrast-to-noise ratio (CNR) calculations derived from signal intensity (SI) measurements; these values were statistically evaluated by using the Mann-Whitney U test. Two readers qualitatively determined SIs of the cores and bodies of the ICHs, degrees of apparent susceptibility artifacts, and lesion ages. The chi(2) test was used to determine statistically significant differences. RESULTS: With the exception of the bodies of late subacute ICHs at 3.0-T T2-weighted imaging, which had increased positive CNRs and SI scores (P .05). With the exception of minor susceptibility artifacts seen in acute and early subacute ICHs at 3.0-T T1-weighted gradient-echo imaging, no susceptibility artifacts were noticed. The ages of most lesions were identified correctly without significant differences between the two field strengths (P >.05), with the exception of the ages of acute ICHs, which were occasionally misinterpreted as early subacute lesions at 3.0 T. CONCLUSION: At 3.0 T, all parts of acute and early subacute ICHs had significantly increased hypointensity on FLAIR and T2-weighted MR images as compared with the SIs of these lesions at 1.5 T. However, 1.5- and 3.0-T MR images were equivalent in the determination of acute to late subacute ICHs.     

Diffusion-Weighted MR Imaging of Intracerebral Hemorrhage

Objective

To document the signal characteristics of intracerebral hemorrhage (ICH) at evolving stages on diffusion-weighted images (DWI) by comparison with conventional MR images.

Materials and Methods

In our retrospective study, 38 patients with ICH underwent a set of imaging sequences that included DWI, T1-and T2-weighted imaging, and fluid-attenuated inversion recovery (FLAIR). In 33 and 10 patients, respectively, conventional and echo-planar T2* gradient-echo images were also obtained. According to the time interval between symptom onset and initial MRI, five stages were categorized: hyperacute (n=6); acute (n=7); early subacute (n=7); late subacute (n=10); and chronic (n=8). We investigated the signal intensity and apparent diffusion coefficient (ADC) of ICH and compared the signal intensities of hematomas at DWI and on conventional MR images.

Results

DWI showed that hematomas were hyperintense at the hyperacute and late subacute stages, and hypointense at the acute, early subacute and chronic stages. Invariably, focal hypointensity was observed within a hyperacute hematoma. At the hyperacute, acute and early subacute stages, hyperintense rims that corresponded with edema surrounding the hematoma were present. The mean ADC ratio was 0.73 at the hyperacute stage, 0.72 at the acute stage, 0.70 at the early subacute stage, 0.72 at the late subacute stage, and 2.56 at the chronic stage.

Conclusion

DWI showed that the signal intensity of an ICH may be related to both its ADC value and the magnetic susceptibility effect. In patients with acute stroke, an understanding of the characteristic features of ICH seen at DWI can be helpful in both the characterization of intracranial hemorrhagic lesions and the differentiation of hemorrhage from ischemia.     

联合MRI常规与弥散成像判断多发性硬化斑块的病理基础

目的：研究MRI常规与弥散成像（DWI，DTI）联合应用，在判定多发性硬化斑块病理基础中的价值。材料和方法：对14例脑部多发性硬化病例进行联合MRI常规及弥散加权（DWI）、弥散张量成像（DTI）。其中1例为继发进展型（SP型），13例为好转－复发型（RR型）。首次发作期（急性斑块）成像者5例，缓解期（慢性斑块）成像者9例。分析常规MRI T1WI、T2WI及DWI、DTI成像后所获得的ADC图、FA图上的信号改变，量化分析DTI成像中的平均D值及各向异性指数AI值。结果：急性与慢性MS斑块MRI表现明显不同。急性MS斑块较大，斑块内信号不均匀，大致可以分为两部分：中心为数毫米至2cm不等的圆形或卵圆形异常信号影，呈T1WI低、T2WI高信号，推测病理为脱髓鞘或轴索丢失。周围为片状不规则形T1WI略低、T2WI略高信号影，考虑为水肿。发作MS斑块DWI可呈现高信号，e指数ADC图亦可呈现高信号，但范围后者明显小于前者。斑块中心平均D值升高、AI值明显下降，周围ADC值亦升高，但不如前者明显，AI值无明显改变，支持常规MRI关于斑块病理的推测。慢性MS斑块较小，多呈小片状或宽条状分布于侧脑室旁，T1WI呈略低信号、T2WI高信号。DWI呈近等信号、e指数ADC图呈等或略低信号。斑块平均D值不同程度升高，AI值下降，提示为脱髓鞘或轴索丢失，而无水肿存在。结论：联合MRI常规与弥散成像可以判断多发性硬化斑块的病理，从而进一步加深了对MS斑块病理的认识。     

First-line investigation of acute intracerebral hemorrhage using dynamic magnetic resonance angiography

Purpose: To report the initial experience of magnetic resonance (MR) digital subtraction angiography (MR-DSA) in the dynamic assessment of the cerebral circulation in acute non-traumatic intracerebral hemorrhage (ICH).

Material and Methods: Twelve patients with acute ICH were investigated within 6 days of the ictus using a dynamic contrast-enhanced 2-D MR angiogram that produces subtracted images with a temporal resolution of 1-2 frame/s. The MR-DSA examinations were assessed for evidence of an intracranial vascular abnormality and were compared with (i) the routine MR sequences, (ii) non-dynamic time-of-flight MR angiography, and (iii) catheter angiogram performed during the same admission.

Results: All 12 MR-DSA examinations were considered to be technically satisfactory. MR-DSA detected an intracranial vascular abnormality in 7 patients (3 arteriovenous malformations, 2 aneurysms, 1 dural arteriovenous fistula, and 1 venous thrombosis). All abnormalities were confirmed by catheter angiography with the exception of one patient with venous sinus thrombosis found on MR imaging that did not undergo catheter angiography. All four arteriovenous shunts were detected by MR-DSA by virtue of early venous filling.

Conclusion: MR-DSA can be performed satisfactorily in the setting of acute ICH and provides an alternative method to catheter angiography for identifying shunting vascular abnormalities such as arteriovenous malformations and fistulae, as well as large aneurysms and venous occlusions. MR-DSA is a contrast-medium-based technique that does not suffer from the T1 shortening effects of acute hemorrhage that can obscure abnormalities on conventional flow-based non-dynamic techniques.     

MR imaging of recent non-traumatic intracranial hemorrhage: early experience at 3 T

Magnetic resonance imaging (MRI) using 3.0 T scanners in the clinical environment is in its infancy and is only available at a limited number of sites worldwide. There is great interest amongst radiologists about the perceived benefits of clinical imaging at 3.0 T; however, it remains to be seen whether the theoretical advantages will bring real gains. MRI in patients with non-traumatic intracranial hemorrhage (ICH) is difficult, yet, these patients benefit from non-invasive angiography. Conventional catheter angiography (CCA) remains the reference standard for excluding/confirming the presence of intracranial vascular abnormalities, but MR angiography at 3.0 T may offer opportunities for significant changes in patient management. We present our experiences of using 3.0 T MR angiography in 27 patients with acute or early subacute ICH.     

实验性脑血肿周围组织脑血流变化的CT灌注成像与病理学研究

目的探讨血肿周围组织病理发展进程及其与血肿周围局部脑血流变化的关系。方法采用自体血注射法制备大鼠脑出血模型,对70只大鼠于术后1h、3h、6h、12h、24h、48h和72h7个时间点,利用GELightspeed螺旋CT扫描机灌注成像及计算机辅助系统制作大鼠脑CT灌注参数图,对血肿周围局部脑血流量(rCBF)、局部脑血容量(rCBV)和对比剂平均通过时间(MTT)脑血液动力学参数进行定量测量,并与大鼠脑TTC染色、HE-染色以及超微结构改变进行比较。结果大鼠脑血肿周围可见明显的低灌注梯度,血肿周围rCBF和rCBV显著降低,MTT延长。TTC染色血肿周围未见白色梗死区。HE-染色可见血肿周围区星形细胞肿胀,神经细胞变性、坏死,出血灶周边毛细血管增生伴炎细胞浸润。电镜观察显示,注血早期血肿周围组织星形细胞肿胀,神经细胞改变不明显,髓鞘板层松散;随着注血后时间延长,血肿周围组织损伤呈渐进性加重,星形细胞肿胀明显,神经细胞出现变性,髓鞘板层发生局部断裂、崩解。结论大鼠脑注血早期血肿周围局部脑血流的显著降低引发了血肿周围及远隔区脑组织的缺血性损伤,注血后急性期血肿周围组织细胞损伤呈进行性加重,血肿周围存在涉及多种细胞损伤机制的半暗带。     

Functional diffusion map as an imaging predictor of functional outcome in patients with primary intracerebral haemorrhage

Objective

Predicting outcome in patients with primary intracerebral haemorrhage (ICH) in the acute stage can provide information to determine the best therapeutic and rehabilitation strategies. We prospectively investigated the predictive value of the functional diffusion map (fDM) in the acute stage of ICH.

Methods

47 patients with ICH were enrolled for clinical evaluation and MRI within 24 h of symptom onset and 5 days after ICH. Functional diffusion mapping prospectively monitored the apparent diffusion coefficient (ADC) maps of perihaematomal oedema. Consequently, the change in perihaematomal oedema was classified into three categories: increased, decreased, or no significant change. Clinical outcomes were evaluated 6 months after ICH according to the modified Rankin Scale. Correlation between clinical outcome and the fDMs was performed.

Results

Among the clinical variables, thalamic haematoma, serum glucose level and National Institutes of Health Stroke Scale scores were significantly different between the good- and poor-outcome groups. The percentage of oedematous tissue undergoing significant change between baseline and Day 5 was also significantly different between the groups.

Conclusion

fDMs allow for spatial voxel-by-voxel tracking of changes in ADC values. It may be feasible to use fDMs to predict the functional outcome of patients with ICH during the acute stage.

Advances in knowledge

The use of fDMs for stroke study is demonstrated. fDMs may be more suitable to reflect the pathophysiological heterogeneity within oedemas and may facilitate another thinking process for imaging study of stroke and other neurological diseases.Primary intracerebral haemorrhage (ICH) is associated with greater mortality and more severe neurological deficits than any other subtype of stroke [1]. Given the emphasis placed on the early introduction of rehabilitation programmes for improving function, prediction of functional outcome in the acute stage of ICH is important. Perihaematomal oedema develops immediately after ICH and peaks several days to weeks later [2,3]. Whether or not perihaematomal oedema contributes to ICH-induced neurological deficits and patient outcome is still controversial and warrants further investigation [4,5]. The pathophysiology of perihaematomal oedema is complicated and may provide valuable clues [4,6]. Diffusion MRI, a technique that can probe tissue microstructure by measuring the diffusion properties of water within tissues, has been used to study perihaematomal injury in patients with ICH, but the results have been inconsistent [7-12].By monitoring changes in the apparent diffusion coefficient (ADC) over time, functional diffusion maps (fDMs) have been developed to monitor regional variations (both increases and decreases) in ADC values in order to provide early stratification of the clinical brain tumour response. Based on the relative change in the ADC value, fDMs can further classify the regions of interest (ROIs) into three categories, which correlate highly with pathological change [13].Given the inconsistent results of previous studies of perihaematomal injury by diffusion-weighted imaging, the diffusion changes within oedematous tissue should be rapid and heterogeneous. In this study, we hypothesised that the early diffusion changes in perihaematomal oedema may correlate with functional outcome in patients with ICH, and that the fDM approach may be a predictive imaging biomarker in the acute stage of ICH.     

Diffusion-weighted imaging provides support for secondary neuronal damage from intraparenchymal hematoma

It is controversial whether an intracerebral hematoma (ICH) causes ischemia of surrounding brain. By virtue of its high sensitivity to acute cerebral infarction, diffusion-weighted imaging (DWI) helps answer this question. We used this technique to assess the parenchyma surrounding ICH for restricted diffusion. Echoplanar DWI (b 1000 s/mm(2)) and conventional MRI sequences were performed in 30 subjects (symptom duration 7-75 h) with primary ICH, mean volume: 13+/-15 cm(3). We calculated mean apparent diffusion coefficients (ADC) within high signal regions around the hematoma on DWI or T2-weighted images and within the ICH itself, comparing them to the contralateral brain. We used the Student's t -test to examine for differences between these regions and linear regression to relate changes to the age of the ICH. A thin rim of high signal on DWI and a wider rim on T2-weighted images surrounded all hematomas. The ADC within the rim on DWI showed a maximum reduction of 40%, in two patients imaged within 10 h of symptom onset. They rose during the first day (r(2)=0.84; P <0.03) and then showed a mild decrease, becoming the same as ADC in other areas of the brain (r(2)=0.5; P <0.03). The rim on T2-weighting showed a mean increase of 50% and ADC within the ICH were reduced by a mean of 38%; these variations showed no relationship with ICH age and no group showed any relationship with ICH size. The ADC within the three regions was significantly different from each other. The presence of restricted diffusion in the parenchyma surrounding ICH provides support for secondary neuronal damage.     

Discrimination of Tumorous Intracerebral Hemorrhage from Benign Causes Using CT Densitometry

BACKGROUND AND PURPOSE:Differentiation of tumorous intracerebral hemorrhage from benign etiology is critical in initial treatment plan and prognosis. Our aim was to investigate the diagnostic value of CT densitometry to discriminate tumorous and nontumorous causes of acute intracerebral hemorrhage.MATERIALS AND METHODS:This retrospective study included 110 patients with acute intracerebral hemorrhage classified into 5 groups: primary intracerebral hemorrhage without (group 1) or with antithrombotics (group 2) and secondary intracerebral hemorrhage with vascular malformation (group 3), brain metastases (group 4), or primary brain tumors (group 5). The 5 groups were dichotomized into tumorous (groups 4 and 5) and nontumorous intracerebral hemorrhage (groups 1–3). Histogram parameters of hematoma attenuation on nonenhanced CT were compared among the groups and between tumorous and nontumorous intracerebral hemorrhages. With receiver operating characteristic analysis, optimal cutoffs and area under the curve were calculated for discriminating tumorous and nontumorous intracerebral hemorrhages.RESULTS:Histogram analysis of acute intracerebral hemorrhage attenuation showed that group 1 had higher mean, 5th, 25th, 50th, and 75th percentile values than groups 4 and 5 and higher minimum and 5th percentile values than group 2. Group 3 had higher 5th percentile values than groups 4 and 5. After dichotomization, all histogram parameters except maximum and kurtosis were different between tumorous and nontumorous intracerebral hemorrhages, with tumors having lower cumulative histogram parameters and positive skewness. In receiver operating characteristic analysis, 5th and 25th percentile values showed the highest diagnostic performance for discriminating tumorous and nontumorous intracerebral hemorrhages, with 0.81 area under the curve, cutoffs of 34 HU and 44 HU, sensitivities of 65.6% and 70.0%, and specificities of 85.0% and 80.0%, respectively.CONCLUSIONS:CT densitometry of intracerebral hemorrhage on nonenhanced CT might be useful for discriminating tumorous and nontumorous causes of acute intracerebral hemorrhage.

The incidence of intracerebral hemorrhage (ICH) is 10–20 cases per 100,000 worldwide.^1–3 ICH has a high mortality rate with case-fatality rates of 34.6% at 7 days and 59.0% at 1 year.⁴ Intracerebral hemorrhage is classified as either primary or secondary on the basis of the underlying cause of bleeding. Primary ICH accounts for 78%–88% of ICH cases and is caused by spontaneous rupture of small vessels associated with chronic hypertension or amyloid angiopathy.⁵ Secondary ICH can occur in association with vascular malformations or tumors.¹ Tumors account for 10% of all spontaneous ICH cases.^6,7 Earlier discrimination of tumorous etiology from nontumorous causes of acute ICH might be helpful to determine appropriate imaging follow-up and avoid delays in long-term management of tumorous ICH, though acute management would not differ.Nonenhanced CT (NECT) is the standard investigation tool for acute ICH. Because most patients with ICH with tumors have a solid enhancing portion, contrast-enhanced CT or contrast-enhanced MR imaging are indicated when secondary ICH with tumor is suspected.^8–10 However, enhancement of secondary ICH can be obscured by surrounding high attenuation or various T1 signal intensities from hematoma; these make diagnosis of secondary ICH difficult.^10–12 Dual-energy CT offers better differentiation between ICH of tumor and nontumor etiology because of better visualization of the enhancing lesion within a high-attenuation hemorrhage.^13,14 However, dual-energy CT is less available than single-energy CT. Thus, a more practical tool with widespread availability in the emergency setting is necessary for early and better discrimination of acute ICH from tumorous-versus-nontumorous causes.We hypothesized that the attenuation of tumorous ICH differs from that of nontumorous ICH on NECT with the presence of solid lesions. We investigated the diagnostic value of CT densitometry of acute ICH to discriminate tumorous and nontumorous causes of acute ICH.     

Investigation of apparent diffusion constant as an indicator of early degenerative disease in articular cartilage

PURPOSE: To investigate the apparent diffusion constant (ADC) as a prospective magnetic resonance imaging (MRI) marker of early degeneration in articular cartilage. MATERIALS AND METHODS: Early degenerative changes were studied using in vitro MRI on cartilage-bone specimens excised from human femoral condyles. The loss of proteoglycans developed in vivo due to a degenerative process was compared with a gadolinium diethylenetriamine pentaacetate anion (Gd-DTPA(2-)) enhanced decrease of T(1) relaxation times, and with an increase of ADCs and T(2) relaxation times. RESULTS: Contrast enhanced T(1) values decreased and the diffusion constants increased in cartilage regions with depleted proteoglycans. The relative changes in diffusion constants were smaller than those of Gd-DTPA(2-) enhanced T(1), and in some proteoglycan-depleted regions no changes in the diffusion constants were detected. T(2) relaxation times showed considerable spatial variability that did not correlate with proteoglycan concentration. CONCLUSION: In contrast to Gd-DTPA(2-) enhanced T(1), which reflects changes in chemical composition, diffusion constants may reflect structural degradation of the cartilage matrix.