产后子痫并可逆性后部白质脑病综合征的MR分析

目的 探讨产后子痫并可逆性后部白质脑病综合征的MR影像.表现特点.方法 对16例经过临床和颅脑MR扫描确诊的产后子痫并可逆性后部白质脑病综合征进行回顾性分析.16例均行常规MR平扫(T1Flair、T2WI、TF2Lair及DWI),8例同时进行了MRV扫描,9例治疗后进行二次MR平扫复查.结果 MR显示:病灶位于双侧性顶、枕叶12例、单侧顶枕叶1例、额叶2例、基底节区5例,DWI多数病例表现为等或相对低信号,MRV均提示无血栓形成.9例二次MR平扫复查示明显吸收好转或基本吸收.结论 产后子痫并可逆性后部白质脑病综合征好发于顶枕叶,少数见于额叶,基底节区,T2 WI和T2Flair较为敏感.     

Cyclosporine-related reversible posterior leukoencephalopathy: MRI

Three patients aged 48, 11 and 40 years, two of whom were recent recipients of renal transplants and one of a bone marrow transplant, developed seizures, with cortical blindness in two cases. All were immunosuppressed with cyclosporine and were hypertensive at the onset of symptoms. MRI showed predominantly posterior signal changes in all three cases. The abnormalities were more conspicuous on fast FLAIR images than on conventional T2-weighted spin-echo images. Received: 13 December 1996 Accepted: 22 January 1997     

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.     

Diffuse metabolic abnormalities in reversible posterior leukoencephalopathy syndrome

Two cases of reversible posterior leukoencephalopathy syndrome were examined with proton MR spectroscopic imaging. Widespread metabolic abnormalities, consisting of increased choline and creatine levels and mildly decreased N-acetylaspartate, occurred in regions with both normal and abnormal MR imaging appearances. In one case for which proton MR spectroscopic imaging follow-up was available, all metabolite levels had returned to normal by 2 months. Proton MR spectroscopic imaging may be helpful for the diagnosis and investigation of the underlying pathophysiology of reversible posterior leukoencephalopathy syndrome.     

A brainstem variant of reversible posterior leukoencephalopathy syndrome

Reversible posterior leukoencephalopathy syndrome (RPLS) is caused by various heterogeneous factors, the commonest being hypertension, followed by nonhypertensive causes such as eclampsia, renal diseases and immunosuppressive therapy. Patients with RPLS exhibit bilateral white and gray matter abnormalities in the posterior aspects of the cerebral hemispheres. However, this syndrome may affect the brainstem predominantly, and these cases are designated as hypertensive brainstem encephalopathy. We present here two patients with reversible brainstem encephalopathy: one with hypertension and the other without hypertension. These patients presented with swelling and diffuse hyperintensities of the brainstem in fluid-attenuated inversion-recovery (FLAIR) and T2-weighted MRI, but with relatively mild clinical symptoms. They recovered without major neurological deficits, but had residual lacunar lesions in the pons. Reversible brainstem encephalopathy with characteristic MRI features was found in both hypertensive and nonhypertensive patients. These patients were diagnosed with a brainstem variant of RPLS, which is potentially fully reversible after an adequate treatment, and therefore should be carefully differentiated from other brainstem disease conditions.     

Differentiation of cytotoxic and vasogenic edema in a patient with reversible posterior leukoencephalopathy syndrome using diffusion-weighted MRI

In recent years reversible posterior leukoencephalopathy syndrome (RPLS) has become increasingly recognized. It represents an uncommon entity related to multiple pathologies, the most common being hypertensive crisis. The underlying pathophysiological mechanism is proposed to be one of vasogenic edema, without infarction; however, differentiation from cytotoxic edema can be crucial for therapeutic and clinical outcome. Diffusion-weighted magnetic resonance imaging (DWI), including calculation of the apparent diffusion coefficient (ADC), may be helpful for differentiation. We present a case of a healthy young woman in the 40th week of gestation, with no prior complications, who suddenly developed RPLS with vasogenic edema, which was differentiated with DWI and quantification of ADC. Follow-up cranial MRI showed complete remission. Pre-eclampsia could not be proven according to pathognomonic laboratory findings.     

Cisplatin neurotoxicity presenting as reversible posterior leukoencephalopathy syndrome.

Visual disturbance, hypertension, convulsions, and unconsciousness developed in a 70-year-old man after cisplatin chemotherapy and upper-limb amputation for osteosarcoma. MR imaging revealed bilateral reversible abnormalities in the occipital, parietal, and frontal white matter. Clinical and neuroradiologic features corresponded to reversible posterior leukoencephalopathy syndrome (RPLS), which some immunosuppressive and chemotherapeutic drugs have been reported to trigger. Cisplatin may be among these drugs. Our patient also had hypomagnesemia, which may have figured in the pathophysiology.     

Patterns in early diffusion-weighted MRI in children with haemolytic uraemic syndrome and CNS involvement

Objectives

Diffusion-weighted imaging (DWI) in children with diarrhoea associated haemolytic uraemic syndrome (D+HUS) and cerebral involvement was evaluated retrospectively.

Methods

DWI within 24?h of onset of neurological symptoms. The apparent diffusion coefficient (ADC) was measured in grey/white matter and correlated with clinical and laboratory findings.

Results

DWI was abnormal in all. Abnormal ADC was detected in the supratentorial white matter (6/12) and cortex (1/12), the basal ganglia (5/12), the thalami (4/12), and the cerebellum (1/12). ADC was reduced in 5/12, increased in 4/12, and both in 3/12. Mean serum sodium was lower in patients with DWI abnormalities affecting the white matter (6/12), than in those with basal ganglia/thalamic involvement (6/12). Neurological outcome was normal in 4/11 and abnormal in 7/11, and 1 patient died, outcome did not correlate to either localisation or type of DWI abnormality.

Conclusions

In D+HUS with neurological symptoms, early DWI may reveal abnormal ADC not only in the basal ganglia/thalami, but also in the white matter/cortex. Besides thrombotic microangiopathy, toxic effects of shiga toxin, azotaemia and hyponatraemia / hypoosmolality may be involved in cerebral involvement in children with D+HUS. Findings on early MRI seem not to predict clinical course or outcome.

Key Points

? DWI MR imaging may detect early CNS involvement in haemolytic uraemic syndrome ? Different pathogenetical mechanisms may contribute to the CNS disease in HUS ? Early MRI findings do not seem to allow prediction of clinical outcome     

Dynamic contrast enhanced MRI in prostate cancer

Angiogenesis is an integral part of benign prostatic hyperplasia (BPH), is associated with prostatic intraepithelial neoplasia (PIN) and is key to the growth and for metastasis of prostate cancer. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) using small molecular weight gadolinium chelates enables non-invasive imaging characterization of tissue vascularity. Depending on the technique used, data reflecting tissue perfusion, microvessel permeability surface area product, and extracellular leakage space can be obtained. Two dynamic MRI techniques (T2*-weighted or susceptibility based and T1-weighted or relaxivity enhanced methods) for prostate gland evaluations are discussed in this review with reference to biological basis of observations, data acquisition and analysis methods, technical limitations and validation. Established clinical roles of T1-weighted imaging evaluations will be discussed including lesion detection and localisation, for tumour staging and for the detection of suspected tumour recurrence. Limitations include inadequate lesion characterisation particularly differentiating prostatitis from cancer, and in distinguishing between BPH and central gland tumours.     

可逆性后部白质脑病综合征的临床特征及影像学分析

目的:探讨可逆性后部白质脑病综合征(RPLS )的临床表现及影像学特征.方法:分析5例RPLS患者的临床及影像学资料.总结该病的临床表现及影像学检查方法在疾病的诊断、治疗及预后中的作用.结果:主要临床表现为头痛,视觉障碍,恶心、呕吐,痫性发作,意识状态改变,精神异常和行为改变.影像学检查显示双侧大脑后部白质水肿,额叶、顶叶、颞叶、脑干、小脑、基底节区和大脑皮质亦可累及.MRI T1WI为略低或等信号,T2WI和FLAIR为高信号,ADC图呈高信号.结论:RPLS的发病机制为急性大脑白质血管源性水肿.绝大数RPLS患者的症状、体征和影像学检查可以完全恢复至病前水平.DWI和ADC图对于早期明确诊断和指导治疗具有非常重要的意义.     

Dynamic susceptibility contrast MRI with localized arterial input functions

Compared to gold‐standard measurements of cerebral perfusion with positron emission tomography using H₂[¹⁵O] tracers, measurements with dynamic susceptibility contrast MR are more accessible, less expensive, and less invasive. However, existing methods for analyzing and interpreting data from dynamic susceptibility contrast MR have characteristic disadvantages that include sensitivity to incorrectly modeled delay and dispersion in a single, global arterial input function. We describe a model of tissue microcirculation derived from tracer kinetics that estimates for each voxel a unique, localized arterial input function. Parameters of the model were estimated using Bayesian probability theory and Markov‐chain Monte Carlo, circumventing difficulties arising from numerical deconvolution. Applying the new method to imaging studies from a cohort of 14 patients with chronic, atherosclerotic, occlusive disease showed strong correlations between perfusion measured by dynamic susceptibility contrast MR with localized arterial input function and perfusion measured by quantitative positron emission tomography with H₂[¹⁵O]. Regression to positron emission tomography measurements enabled conversion of dynamic susceptibility contrast MR to a physiologic scale. Regression analysis for localized arterial input function gave estimates of a scaling factor for quantitation that described perfusion accurately in patients with substantial variability in hemodynamic impairment. Magn Reson Med 63:1305–1314, 2010. © 2010 Wiley‐Liss, Inc.     

Dynamic contrast enhanced perfusion MRI in mycosis fungoides

Mycosis fungoides is a malignant, cutaneous lymphoma of T-helper (TH or CD4+) cells. At presentation, the disease is usually limited to the skin, with lesions that resemble eczema or psoriasis. Neurologic involvement is uncommon. This case demonstrates the conventional MRI and dynamic contrast enhanced perfusion MRI findings in intracerebral mycosis fungoides. T1-weighted spin echo imaging demonstrated a lesion with slightly decreased signal within the body of the corpus callosum. The lesion was isointense with grey matter on axial T2-weighted imaging. Following administration of contrast, there was patchy heterogeneous enhancement. Multiple relative cerebral blood volume (rCBV) measurements were made and the minimum rCBV was 0.30 with the maximum rCBV being 1.61. The mean rCBV was 0.81 +/- 0.49 (average of 10 measurements and standard deviation).     

MR imaging of acute intermittent porphyria mimicking reversible posterior leukoencephalopathy syndrome

Reversible posterior leukoencephalopathy syndrome (PLS) is characterized by headache, altered mental function, visual disturbances and seizures. Neuroimaging studies suggest a white-matter oedema, predominantly in the posterior parietal-temporal-occipital regions of the brain. We present the case of a 30-year-old woman who had suffered her first attack of acute intermittent porphyria (AIP). Following 1 week of abdominal pain she developed several generalized seizures, and hallucinations, and exhibited a progressive deterioration of the consciousness. T2-weighted images, especially fluid-attenuated inversion recovery (FLAIR) sequences showed bilateral lesions in the posterior frontal, parietal and occipital cortex and subcortical white matter. Following treatment with haematin and a high carbohydrate diet the patient's condition improved. Follow-up magnetic resonance imaging (MRI) revealed complete resolution of the lesions. To our knowledge, this is the first report concerning a completely reversible PLS in AIP.     

Diffusion-weighted MR imaging of posterior reversible leukoencephalopathy syndrome: a pictorial essay

Posterior reversible leukoencephalopathy syndrome is characterized by reversible white matter lesions. However, ischemic injury with irreversible damage may occur. This pictorial essay illustrates MR features associated with posterior reversible leukoencephalopathy syndrome. We will emphasize the role of diffusion-weighted imaging for the discrimination of irreversible ischemic injury from reversible vasogenic edema.     

脑后部可逆性脑病综合征的CT、MRI诊断

目的：掌握脑后部可逆性脑病综合征的影像学表现,提高影像诊断水平。方法回顾分析4例脑后部可逆性脑病综合征患者的CT、MR影像表现及临床资料,并复习相关文献。结果2例患者CT 均表现为双侧大脑后循环供血区分布为主的斑片状低密度影;2例MRI表现为双侧顶枕叶基本对称分布斑片状长T1长T2信号,T2 FLAIR呈高信号, DWI呈等信号,增强无强化。结论 CT、MRI检查为脑后部可逆性脑病综合征诊断提供客观依据,在其诊断中具有重要价值,结合临床表现可对其作出准确的诊断。     

Imaging characteristics associated with clinical outcomes in posterior reversible encephalopathy syndrome

Purpose

Posterior reversible encephalopathy syndrome (PRES) is a disorder of cerebrovascular autoregulation that can result in brain edema, hemorrhage, and infarction. We sought to investigate whether certain imaging characteristics in PRES are associated with clinically significant patient outcomes.

Methods

We retrospectively reviewed all cases of PRES occurring between 2008 and 2014 at two major academic medical centers. Demographic, clinical, and radiographic data were collected. We analyzed imaging studies for vasogenic edema, hemorrhage, and diffusion restriction. We performed univariate analysis and stepwise logistic regression to assess the association between our radiologic findings of interest and clinical outcomes as defined by hospital discharge disposition and modified Rankin scale (mRS) at time of discharge.

Results

We identified 99 cases of PRES in 96 patients. The median age was 55 years (IQR 30–65) and 74% were women. In 99 cases, 60% of patients had active cancer, 19% had history of bone marrow or organ transplantation, 14% had autoimmune disease, and 8% were peripartum. Imaging at clinical presentation showed extensive vasogenic edema in 39%, hemorrhage in 36%, hemorrhage with mass effect in 7%, and restricted diffusion in 16%. In our final logistic regression models, the presence of extensive vasogenic edema, hemorrhage with mass effect, or diffusion restriction was associated with worse clinical outcome as defined by both discharge disposition (OR = 4.3; 95% CI: 1.4–36.3; p = 0.047) and mRS (OR = 3.6; 95% CI: 1.2–10.7; p = 0.019).

Conclusions

Extensive vasogenic edema, hemorrhage, and restricted diffusion on initial imaging in PRES are associated with worse clinical outcomes.

     

Diffusion-weighted imaging of the kidneys in haemolytic uraemic syndrome

Objectives

To evaluate the kidneys of patients with haemolytic uraemic syndrome (HUS) using diffusion-weighted imaging (DWI) and Doppler ultrasound (US) compared with healthy controls.

Materials and Methods

Fifteen patients (mean age 33.3 years; three male; 12 female) with diarrhoea-positive HUS and 15 healthy volunteers were prospectively evaluated with DWI and Doppler US. A total apparent diffusion coefficient (ADC_TOT), and ADCs predominantly reflecting microperfusion (ADC_LOW) and diffusion (ADC_HIGH) were calculated. Doppler US evaluated renal vascularity and flow.

Results

When compared with controls, kidneys affected by HUS showed reduced cortical ADC values (ADC_TOT 1.79±0.22 vs. 2.04±0.1x10^-3 mm²/s, P 0.001), resulting in either low corticomedullary differences (11/15 patients) or an inverted corticomedullary pattern (4/15 patients). Reduction of cortical ADC values was associated with a decrease of cortical vascularity on Doppler US (ADC_TOT, P<0.001; ADC_LOW, P 0.047). Kidneys with complete absence of the cortical vasculature on Doppler US (four patients) also demonstrated limited diffusion (ADC_HIGH, P 0.002). Low glomerular filtration rate, requirement for haemodialysis during hospitalization, and longer duration of haemodialysis were associated with decreased cortical diffusivity (ADC_TOT: P 0.04, 0.007, and <0.001, respectively).

Conclusion

DWI shows qualitative and quantitative abnormalities in kidneys affected by HUS, thereby extending the non-invasive assessment of renal parenchymal damage.

Key Points

? In HUS, DWI is feasible for functional characterization of kidney involvement. ? Kidneys affected by HUS showed reduced cortical diffusivity. ? Decreased cortical diffusivity was associated with lower kidney function. ? Requirement and duration of haemodialysis was linked to degree of cortical alterations.

     

Implications of post-gadolinium MRI results in 13 cases with posterior reversible encephalopathy syndrome

BACKGROUND: There is a relative lack of definitive information about the contrast-enhancement characteristics of lesions in posterior reversible encephalopathy syndrome (PRES). OBJECTIVE: Evaluation of contrast-enhanced MRI findings in PRES with a special emphasis on pathophysiology of post-gadolinium behavior of these lesions. MATERIALS AND METHODS: Contrast-enhanced 1.5 T MRI findings and relevant clinical data of the patients were retrospectively reviewed on 13 cases (six males, seven females; age range: 22-78; mean age 47). Although fluid attenuated inversion recovery (FLAIR) and diffusion-weighted MR images were considered for identification of the entity, primarily post-contrast T1-weighted MR images were searched for traces of enhancement in the lesions. RESULTS: No definitely enhancing lesion was identified in the MR images obtained in 6-48 h after onset of symptoms (mostly headaches, seizures and cortical visual field deficits) in this series. Severity of disease indicated by small hemorrhages, confluence of lesions or progression to cytotoxic edema did not seem to alter this result. Typical lesion characteristics were consistent with vasogenic edema on FLAIR and diffusion MR images. Acute elevation of blood pressure on chronic hypertensive background was responsible in four, eclampsia in three, uremia with blood pressure fluctuations in three, and cyclosporine-toxicity in three cases. CONCLUSION: Although occasional enhancing brain lesions have been reported in the literature on PRES, contrast-enhancement of lesions may be a factor of scan timing and underlying etiology. Prospective studies with larger series on PRES are required for better evaluation of contrast-enhancement in MRI with respect to scan timing, which in turn may help understand its pathophysiology better.     

增强MRI评价可逆性血脑屏障开放的可靠性及价值

目的评价增强ＭＲＩ在监测可逆性血脑屏障（ＢＢＢ）开放的可靠性及价值。方法３６只家兔被随机分为３组：Ａ、Ｂ两组分别经颈内动脉灌注２０％甘露醇和生理盐水，Ｃ组经耳缘静脉灌注２０％甘露醇。灌注后，立即用０．５Ｔ超导型ＭＲ机进行兔脑冠状位扫描，随后经耳缘静脉注入ＧｄＤＴＰＡ，迅速行同层间隙扫描（增强后５、１０、１５、２０分钟，之后每隔１０分钟），持续２小时。以该层双侧对称的脑实质为兴趣区，测得不同时间兴趣区信号强度（ＳＩ），求其增强率（％）。各组１０只兔于扫描前经耳缘静脉注入２％Ｅｖｅｎｓ蓝（２ｍｌ／ｋｇ），２小时后处死；另有６只分别于灌注后２．５、３小时注入Ｅｖｅｎｓ蓝，１０分钟后处死，取脑观察有无脑实质蓝染，以此来推测ＢＢＢ开放持续时间。所有脑标本送病理检查，并与对应层的ＭＲＩ进行比较。结果Ａ组１０只皆出现灌注侧脑实质增强及蓝染，Ｂ、Ｃ组无一只出现明显强化及蓝染。ＢＢＢ开放持续时间小于３小时。未发现死亡及脑实质病理改变。结论增强ＭＲＩ是监测ＢＢＢ开放过程、指导临床个体化用药的一种理想方法。     

Tumor lysis syndrome as a contributory factor to the development of reversible posterior leukoencephalopathy

Introduction Reversible posterior leukoencephalopathy syndrome (RPLS) is a recently described clinical and radiological entity comprising headache, seizures, altered level of consciousness and visual disturbances in association with transient posterior cerebral white-matter abnormalities.Method We report a young woman with Burkitt’s lymphoma who developed RPLS after combined chemotherapy administered during the tumor lysis syndrome.Results The symptoms in this patient fitted well with those of RPLS; they included abrupt alterations in mental status, seizures, headache, visual changes and characteristic neuroradiological findings. She was given further combination chemotherapy without any neurological complications, at which time she had already recovered from both RPLS and tumor lysis syndrome.Conclusion Although many etiological factors have been reported in the development of RPLS, the underlying mechanism is not yet well understood. With prompt and appropriate management, RPLS is usually reversible, and chemotherapy can be continued after complete recovery from RPLS. We suggest that tumor lysis syndrome should be considered as a contributory factor to the development of RPLS in patients for whom treatment with combined chemotherapy for hematological malignancies is planned.