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.     

MRI联合磁共振静脉成像诊断脑静脉窦血栓形成的价值

目的:探讨MRI及磁共振静脉成像(MRV)对脑静脉窦血栓形成的诊断价值.方法:回顾性分析37例DSA确诊脑静脉窦血栓形成患者的临床资料及影像表现.37例中有30例行常规MRI检查,29例行MRV(2D TOF)检查.结果:30例常规MRI检查中28例静脉窦有异常信号,其中26例MRI表现为静脉窦T1WI、T2WI高信号,2例T1WI等信号、T2WI低信号,并部分伴有脑组织梗死、出血.29例MRV检查均发现静脉窦充盈缺损或中断.结论:MRI与MRV结合对诊断脑静脉窦血栓形成具有高度敏感性,是诊断静脉窦血栓形成的首选检查方法.     

MRI imaging of posterior reversible encephalopathy syndrome associated with pregnancy

Purpose

Our purpose is to characterize MRI, and diffusion-weighted imaging (DWI) findings in pregnant patients who were identified clinically to have PRES. We study the conversion of reversible vasogenic edema to irreversible cytotoxic edema and predict the progression to infarction.

Patients and methods

Twenty two pregnant females, aged between 20 and 46 years with gestational age between 20 and 40 weeks of gestation and with neurological manifestations had undergone conventional MRI, diffusion weighted image study, and ADC map.

Results

Lesions were mainly affecting the parieto-occipital regions, symmetrical or slightly asymmetrical distribution of the lesions in both cerebral hemispheres was found in most cases. The MRI findings in all the twenty two patients were: abnormal low SI in T1 WI, abnormal high SI on T2 and FLAIR WI. In DWI, hyperintensity with hyperintensity in ADC map was seen in 15 patients, hyperintensity with hypointensity in ADC map in 4 patients, normotensive in DWI with hyperintensity in ADC map in 3 patients.

Conclusion

The diagnosis of PRES has important therapeutic and prognostic value. The use of diffusion-weighted imaging and ADC maps allows an earlier and clearer differentiation of cytotoxic and vasogenic edema, which can predict the development of infarction.     

Parenchymal abnormalities associated with cerebral venous sinus thrombosis: assessment with diffusion-weighted MR imaging

BACKGROUND AND PURPOSE: The common entity cerebral venous sinus thrombosis is associated with the poorly characterized imaging finding of parenchymal abnormalities; diffusion-weighted imaging has offered some insight into these manifestations. We assessed the relationship between the diffusion constant from apparent diffusion coefficient (ADC) maps in patients with cerebral venous thrombosis (CVT) with follow-up imaging findings and clinical outcome. METHODS: We evaluated the medical records and T2-weighted MR images of 13 patients with CVT complicated by intraparenchymal abnormality. Diffusion-weighted (DW) images and ADC maps were evaluated for increased, decreased, or unchanged signal intensity and were compared with signal intensity of contralateral, normal-appearing brain. In addition, ADCs were obtained in nine pixel regions of interest in abnormal regions in eight of the 13 patients. RESULTS: Eight patients had superficial CVT, and five had superficial and deep CVT. CVT of deep veins was associated with deep gray nucleus and deep white matter abnormalities, whereas superficial CVT was associated with cortical and subcortical abnormalities. Twenty-four nonhemorrhagic lesions were identified in 10 of 13 patients on the basis of follow-up imaging findings. Four patients without seizures had lesions with decreased diffusion that appeared hyperintense on follow-up T2-weighted images, three patients with seizures had lesions with decreased diffusion that resolved, and seven patients had lesions with increased diffusion that resolved. Three of 10 patients had more than one lesion type. No difference was noted in mean ADCs for lesions with decreased diffusion that resolved compared with lesions with decreased diffusion that persisted. CONCLUSION: DW imaging in these patients disclosed three lesion types: lesions with elevated diffusion that resolved, consistent with vasogenic edema; lesions with low diffusion that persisted, consistent with cytotoxic edema in patients without seizure activity; and lesions with low diffusion that resolved in patients with seizure activity. This information may be important in prospectively determining severity of irreversible injury and in patient treatment.     

Dural sinus thrombosis: study using intermediate field strength MR imaging

The magnetic resonance (MR) images of six patients with thrombosis of a dural sinus were reviewed. The diagnosis had been verified by computed tomographic scans in three patients and arteriograms in two; in the sixth patient, only MR imaging was used to confirm the clinical syndrome. In all patients, high-intensity signal was seen from the thrombus within the affected dural sinus on all echoes. This persistent signal intensity allowed intravascular clot to be distinguished from normal causes of increased signal such as flow-related enhancement (entry phenomenon) and even-echo rephasing. MR imaging demonstrated the cause of the thrombosis in three patients: two were secondary to adjacent tumors, and one was secondary to unsuspected mastoiditis. Complications such as infarction were also demonstrated. Using MR imaging, one can easily and safely diagnose thrombosis of a dural sinus. MR should be the imaging method of choice in patients suspected of having thrombosis of a dural sinus.     

Acute dural venous sinus thrombosis without brain parenchymal abnormality: assessment with cerebral blood volume using dynamic susceptibility contrast magnetic resonance imaging

We report results applying the dynamic susceptibility contrast (DSC) magnetic resonance (MR) technique to a patient with dural venous sinus thrombosis (DVST) of the right transverse-sigmoid sinus without brain parenchymal abnormality. The DSC-MR technique clearly demonstrated increased regional cerebral blood volume of the right temporo-parieto-occipital region adjacent to a right transverse-sigmoid sinus thrombosis in a patient with DVST without cerebral edema or hemorrhage.     

Discrimination between different types of white matter edema with diffusion-weighted MR imaging

Brain edema can be classified into three categories: vasogenic, cytotoxic, and interstitial. The mechanism of edema is thought to be different in each type. The authors studied the movement of water molecules in each type of white matter edema in a rat model by using diffusion-weighted magnetic resonance imaging. Conventional T2-weighted imaging did not allow distinction between the three types of white matter edema; the three types of edema were, however, distinguished by using diffusion-weighted imaging. The apparent diffusion coefficient (ADC) of water was different in each type of edema. Water molecules in cytotoxic edema induced by triethyl-tin intoxication showed a smaller and less anisotropic ADC than in normal white matter. In contrast, water in vasogenic edema induced by cold injury had a larger and more anisotropic ADC than in normal white matter. Water in interstitial edema due to kaolin-induced hydrocephalus had an anisotropic and very large ADC.     

Isolated cortical venous thrombosis and ulcerative colitis.

Aseptic cortical venous thrombosis is rare without concomitant dural sinus thrombosis. Ulcerative colitis is associated with both dural sinus thrombosis and isolated cortical venous thrombosis. We describe a 26-year-old woman with ulcerative colitis who had a spontaneous cerebral hemorrhage. An overlying thrombosed cortical vein was identified on spin-echo MR images and confirmed with angiography. Signal characteristics of thrombosed cortical veins are similar to those described in dural sinus thrombosis.     

Combined aspiration thrombectomy and continuous intrasinus thrombolysis for cerebral venous sinus thrombosis: technical note and case series

Cerebral venous sinus thrombosis is an uncommon cause of stroke with high morbidity and mortality rates from venous infarction, intracranial hemorrhage, and extensive cerebral edema. Endovascular treatment with various devices has been proposed as a salvage treatment when standard medical treatment with systemic anticoagulation is ineffective, especially in long segment dural sinus thrombosis. We describe our technique of transvenous endovascular aspiration thrombectomy with large bore thrombectomy catheters, followed by placement of microcatheter for local thrombolytic infusion at the site of thrombosis. We report a retrospective study of angiographic and clinical outcome of six consecutive patients treated with this approach. Endovascular aspiration thrombectomy with large bore catheters followed by continuous local thrombolytic infusion appeared to be a safe and effective salvage treatment for selected patients with cerebral dural venous sinus thrombosis refractory to medical treatment.     

Follow-up MRI in dural arteriovenous malformations involving the cavernous sinus: emphasis on detection of venous thrombosis

Summary Six patients with a dural arteriovenous malformation (dural AVM) involving the cavernous sinus were followed up with magnetic resonance imaging in order to assess change in the lesions. Spin-echo (SE) imaging of three patients in whom the AVM appeared to have closed at least 1 month earlier (two of them spontaneously, and one after external carotid artery embolization) showed neither apparent flow void in the involved cavernous sinus nor evidence of venous thrombosis. SE images of the other three patients who had not been cured by external carotid artery embolization (two of whom were examined within a week of treatment), detected persisting arteriovenous shunts, including high-flow cortical venous drainage, seen as flow void. Two-dimensional time-of-flight MR angiography (2D TOF MRA) was performed simultaneously in three patients. Whereas shunting blood and the normal cavernous sinus were of high intensity, presumed thrombosed cavernous sinuses were isointense with stationary brain tissue. SE imaging can confirm the resolution of arteriovenous shunts, but poorly delineates ver acute and chronic thrombosis of the draining veins. In contrast, 2D TOF MRA directly demonstrates flowing blood, permitting the diagnosis of venous thrombosis; it should be included in follow-up of a dural AVM involving the cavernous sinus when venous thrombosis is suspected.     

Cerebral Venous Congestion as Indication for Thrombolytic Treatment

Purpose To carry out a retrospective analysis of patients with acute dural sinus thrombosis, and the role of cerebral venous congestion in patient management. Methods Twenty-five patients were identified with the clinical and imaging diagnosis of acute dural sinus thrombosis. The imaging diagnosis was by magnetic resonance (MR) and/or computed tomography (CT) venography. There was a female predominance with a female to male ratio of 1.5 to 1 (16 women, 9 men). The age range was from 19 to 64 years old with an average age of 37 years. The first 10 patients, who ranged in age from 21 to 64 years old (average 37 years), received only anticoagulation therapy with heparin and warfarin for periods ranging from 5 days to 2 months. The remaining 15 patients ranged in age from 19 to 57 years old (average 38 years). They either underwent subsequent thrombectomy after a trial of anticoagulation therapy, or went straight to thrombectomy. These latter 15 patients had initial evidence of cerebral venous congestion, either clinically by severe or worsening symptoms despite anticoagulation therapy, or on initial or subsequent CT or MR imaging. In our experience, the cerebral venous congestion imaging findings included intracranial hemorrhage, a hematoma, or edema. The thrombolytic treatment technique consisted of the advancement of a 6 Fr guiding catheter to the jugular bulb or sigmoid sinus from a transfemoral approach. A microcatheter was then advanced to the proximal portion of the thrombus and then either tissue plasminogen activator (tPA) or urokinase was injected to prevent clot propagation. A balloon catheter was used to perform thrombectomy since the thrombolytic agents can be injected via the inner lumen with an inflated balloon. The inflated balloon helped to keep the venous flow from washing out the thrombolytic agent, thus facilitating the agent’s effect. Results The first 10 patients received only anticoagulation therapy with heparin and warfarin for periods ranging from 5 days to 2 months. Eight of these were diagnosed with dural sinus thrombosis only, and had a stable hospital course without worsening of symptoms. These patients also did not have imaging evidence of cerebral venous congestion. The remaining 2 patients had cerebral edema on the CT scan. One had only a small amount of edema in the right cerebellum, but the other had severe edema in the bilateral basal ganglia and thalamic areas. Nine of these patients had a stable hospitalization course and experienced a symptom-free recovery, but 1 died with severe cerebral edema and hemorrhage. Seven of the remaining 15 patients were initially treated with anticoagulation therapy for periods ranging from 2 days to 2 months (average 11 days). These 7 patients were considered to have failed anticoagulation therapy since they had worsening symptoms, and 5 of these had developed hemorrhage on subsequent CT or MR imaging scans. Five of the 7 then underwent thrombectomy with the administration of tPA. Of the remaining 2, 1 underwent thrombectomy alone without the administration of tPA, and the other was given 1 million units of urokinase instead of tPA. Three of these patients had a symptom-free recovery, but 2 had residual left-sided weakness, 1 patient had a minimal gait disturbance, and another patient developed a transverse sinus arteriovenous fistula 7 months after thrombolytic therapy. The remaining 8 patients did not receive anticoagulation therapy, and went straight to treatment with thrombectomy and administration of tPA. All of these presented with worsening clinical symptoms. Six had hemorrhage on their imaging studies, 1 had new edema on a subsequent CT scan, and 1 had edema along with the dural sinus thrombosis, but experienced worsening clinical symptoms consisting of headache and atypical dystonia. Five of these 8 patients experienced a symptom-free recovery, and 3 patients had mild residual weakness. Conclusion In patients with acute dural sinus thrombosis, an indication for thrombectomy or thrombolytic therapy may be the development of cerebral venous congestion which appears to include (1) worsening or severe clinical symptoms, and/or (2) CT or MR imaging findings including intracranial hemorrhage, a hematoma, or edema. It appears that anticoagulation therapy alone is not adequate in patients with acute dural sinus thrombosis when they develop cerebral venous congestion. This may be due to a lack of sufficient collateral flow. Those patients who went straight to thrombectomy because of worsening symptoms, or the imaging findings of cerebral vascular congestion, survived with either a symptom-free recovery or only mild residual neurologic deficit. The patient with evidence of cerebral venous congestion died while on anticoagulation therapy. Thus, the presence of cerebral venous congestion in patients with dural sinus thrombosis, even while on anticoagulation therapy, appears to be an indication for thrombectomy and infusion of thrombolytic agent through a balloon catheter to the site of thrombosis. Our experience suggests that this approach appears to improve the chance of survival, with either a symptom-free recovery or a recovery with only mild residual neurologic deficit.     

DWI findings of periventricular ischemic changes in patients with leukoaraiosis.

In this report the diffusion-weighted imaging (DWI) findings and ADC values of leukoaraiosis (LA) and associated periventricular ischemic lesions were assessed. Seventy-eight patients with LA were examined with magnetic resonance imaging (MRI) and DWI. Twenty one patients (28%) were found to have focal acute white matter infarction on DWI which could not be detected and discriminated on the basis of MRI findings alone. LA and acute white matter infarction both showed hyperintensity on standard T2W MRI, whereas acute infarction revealed focal hyperintensity on DWI. Thirteen patients (16%) had chronic lacunar infarctions in the white matter. ADC values of LA, acute and chronic white matter infarctions were calculated and found to be significantly different from each other (p<0.05). It is concluded that DWI is necessary in the detection of acute periventricular white matter infarction from LA.     

Serial diffusion-weighted imaging in MELAS

Clinical features of mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) resemble those of cerebral infarcts, but the pathogenesis of infarct-like lesions is not fully understood. To characterise these infarct-like lesions, we studied two patients with MELAS using diffusion-weighted (DWI) MRI before and after stroke-like episodes and measured the apparent diffusion coefficient (ADC) in the new infarct-like lesions. These gave high signal on DWI and had much higher ADC than normal-appearing regions. The ADC remained high even 30 days after a stroke-like episode then decreased in lesions, with or without abnormality as shown by conventional MRI. We speculate that early elevation of ADC in the acute or subacute phase reflects vasogenic rather than cytotoxic edema. The ADC of the lesions, which disappeared almost completely with clinical improvement, returned to normal levels, which may reflect tissue recovery without severe damage. To our knowledge, this is the first study of DWI in MELAS. Received: 13 September 1999/Accepted: 7 January 2000     

MRI and diffusion MRI in nonparaneoplastic limbic encephalitis.

This paper reports an 65-year-old woman with nonparaneoplastic limbic encephalitis. On MRI and diffusion MRI, diffuse and symmetrical, bilateral high-signal lesions were evident in the medial temporal lobes. The affected areas were hyperintense on b= 1000 s/mm(2) (heavily diffusion-weighted or true diffusion) images, a pattern similar to cytotoxic edema. However, apparent diffusion coefficient (ADC) values read directly from corresponding ADC maps at each temporal lobe were within normal limits: 0.96 and 0.97 x 10 x (-3) mm(2)/s, respectively, excluding cytotoxic edema. The changes were shown to be resolved on a 9-month follow-up MRI.     

脑内静脉窦血栓形成MRI表现的再探讨和MR静脉成像的选择

目的：明确脑内静脉血栓形成的脑内MRI表现和MR血管造影的诊断及检查方法。材料和方法：共9例病人，男性2例，女性7例。年龄30－56岁，平均38．2岁。使用Siemens-vision-plus超导高场MRI系统，场强1．5T。采用常规SE序列，tuberSE，TOF血管成像（用于动脉血管显示），PC法20静脉血管成像和增强3D静脉血管成像（用于矢状窦显示）。结果：MR的动脉血管成像显示阳性率为0％，2D和3D静脉血管成像阳性率为100％，3D增强静脉血管造影可更好地显示阻塞的静脉。脑实质内均有阳性表现，表现为矢状窦旁白质区对称或非对称性异常改变，呈斑片状和片状，T1W为低信号，T2W为高信号。增强后脑膜强化2例。合并脑内出血5例。结论：MRI结合MR静脉血管造影，尤其增强3D静脉血管造影是诊断脑内静脉血栓形成的有效手段。     

A case of intravascular lymphomatosis with sinus thrombosis]

We report a rare case of intravascular lymphomatosis with massive tumor in the superior sagittal sinus (SSS), which caused sinus thrombosis. A 63-year-old man was incidentally found to have an enhancing mass in the superior sagittal sinus on MRI. The tumor manifested spontaneous regression during with 4 month's follow-up. Five months after the initial MR examination, T2-weighted MR images revealed a area of hyperintensity in the right occipital lobe. The area showed hypointensity on diffusion-weighted image and showed hyperintensity on ADC mapping, findings that are compatible with vasogenic edema.     

Isolated cortical venous thrombosis presenting as subarachnoid hemorrhage: a report of three cases

Cortical venous thrombosis (CVT) without concomitant dural sinus thrombosis is an uncommon disorder. Isolated CVT usually manifests on imaging studies as focal parenchymal hemorrhage or edema. We report three cases of isolated CVT that presented with unilateral, localized subarachnoid hemorrhage without parenchymal involvement.     

Utility of contrast-enhanced 3D turbo-flash MR angiography in evaluating the intracranial venous system

The objective of this study was to compare the effectiveness of contrast-enhanced 3D turbo-flash and 2D time-of-flight (TOF) magnetic resonance angiography (MRA) sequences in the visualization and evaluation of the intracranial venous system. A prospective study was carried out on 41 patients referred to our Magnetic Resonance Imaging (MRI) unit with clinical findings suggestive of dural sinus thrombosis. Contrast-enhanced 3D turbo-flash and 2D TOF MRA sequences were performed, and the dural sinuses and cerebral veins were classified into five grades according to the quality of visualization and presence of thrombosis. We found the dural sinuses and cerebral veins to be normal in all sequences in 31 patients. Thrombosis of dural sinuses was detected in ten patients, with four of these ten cases found only in the contrast-enhanced 3D turbo-flash sequence. In general, complete visualization of cerebral veins and dural sinuses was significantly better accomplished with contrast-enhanced 3D turbo-flash MRA than with 2D TOF in either coronal or sagittal/oblique planes. Although 2D TOF MRA may be superior in detecting chronic dural sinus thrombosis, contrast-enhanced 3D turbo-flash MRA sequences may offer advantages for the early diagnosis and management of acute and subacute dural sinus thrombosis.     

硬膜窦血栓形成的MRI表现(附6例分析)

目的：探讨硬膜窦血栓形成的ＭＲＩ表现。方法：６例硬膜窦血栓形成，均做了ＭＲＩ检查，其中２例用了ＳＴＩＲ，１例用了ＦＬＡＩＲ序列，３例作了增强检查（Ｇｄ－ＤＴＰＡ），５例作了ＭＲＶ。结果：右横窦栓塞２例，左横窦１例，上矢状窦３例，脑肿胀５例，静脉性脑栓塞２例，脑血肿１例。增强检查，脑皮质及皮质静脉增强１例。结论：ＭＲＩ对硬膜窦血栓形成的诊断有独特的价值。硬膜窦流空信号消失和硬膜窦狭窄、闭塞是直接征像。脑肿胀、静脉性脑梗塞、脑血肿是间接征像     

Evidence for cytotoxic edema in the pathogenesis of cerebral venous infarction

BACKGROUND AND PURPOSE: The pathogenesis of cerebral venous infarction (CVI) remains controversial, with uncertainty over whether cytotoxic edema plays a role. Recent animal studies have shown that cytotoxic edema reliably occurs in acute CVI and precedes the onset of vasogenic edema. Our hypothesis was that cytotoxic edema would also occur in acute human CVI and would be detectable as an area of restricted diffusion on diffusion-weighted images. METHODS: Twelve subjects with acute cerebral venous thrombosis confirmed by MR venography underwent both conventional MR and echo-planar diffusion-weighted imaging (maximum diffusion sensitivity [b=1000 s/mm(2)]). Images were examined for areas of CVI that were identified as T2 hyperintensity, diffusion hyperintensity, or hemorrhage. The percent change in apparent diffusion coefficient (ADC) and T2 signal as well as the T2/diffusion volume were calculated within areas of edematous CVI. Regression techniques were used to examine the relationship of these variables to symptom duration. RESULTS: Ten regions of CVI were detected in seven subjects, all showing T2 hyperintensity. Two of these regions were predominantly hemorrhagic and did not display diffusion hyperintensity. The remaining eight regions displayed diffusion hyperintensity that was associated with a decreased ADC. ADC values increased with symptom duration (r(2) = 0.96; P <.006). Both T2 hyperintensity and T2/diffusion volume peaked approximately 2 days after symptom onset. CONCLUSION: Restricted water diffusion suggesting cytotoxic edema is commonly found in subjects with acute CVI and decreases over time. This supports an important etiologic role for cytotoxic edema in the pathogenesis of CVI.