Echoplanar diffusion-weighted MRI with intravenous gadolinium-DTPA

It is occasionally necessary to repeat diffusion weighted imaging (DWI) after giving intravenous contrast medium (CM). However, the effects of CM on DWI and apparent diffusion coefficients (ADC) have not been fully examined. The aim of this prospective study was to investigate whether there are any diagnostically significant differences between echo-planar imaging (EPI)-DWI before and after intravenous CM. EPI-DWI was acquired twice in 203 consecutive patients before and after i.v. CM. Three blinded readers rated the diagnostic image quality. Quantitative ADC calculations were performed before and after CM in all 72 patients with lesions sufficiently large for quantification, and in 72 normal brain regions. Of the 203 patients, 127 had abnormalities on MRI, including ischaemic stroke (52), bleeding (nine), brain tumour with disturbed blood-brain barrier (BBB) (18) and other lesions (48). There were no significant signal differences on isotropic DWI before and after CM, even in lesions with definite disturbance of the BBB. No statistically significant difference between ADC of lesions and contralateral normal brain was observed.     

急性缺血性卒中的MRI早期诊断价值

目的：评价神经影像技术对早期脑梗塞的病灶显示、病变发展及其对治疗的临床应用价值。方法：35例临床初诊急性脑梗塞病人，出现症状后1．5～24h内分别行平扫CT、常规MRI、MR血管成像、弥散（DWI）和灌注（PWI）MR成像；13例行静脉内溶栓治疗并于2w内随访治疗效果。结果：35例中脑出血6例，平扫CT对急性脑梗塞征象显示率为48．3％；29例脑梗塞中，常规MRI、DWI、PWI均显示病灶；T1WI显示病灶范围最小，T2WI、FLAIR序列显示病灶范围逐渐增加；20例同时行DWI和PWI中，13例（65％）出现弥散一灌注不匹配，溶栓治疗7例症状好转（53．3％）。结论：神经影像技术中的DWI和PWI可以在脑梗塞后有效治疗时间窗内显示病灶的大小和血液动力学改变，结合CT平扫和常规MRI序列，有助于尽早溶栓治疗，减轻症状，恢复功能，提高病人生存质量。     

严重急性呼吸综合征康复患者骨缺血性坏死患病率的MRI筛查研究

目的采用MRI对康复的严重急性呼吸综合征（SARS）患者骨缺血性坏死进行筛查，探讨康复SARS患者骨缺血性坏死的患病率，及与激素使用的关系。方法用MRI对448例感染SARS的康复患者进行骨缺血性坏死筛查。所有受试者都做了双髋和双膝关节MR扫描，其中192例还扫描了肩和踝关节。采用体线圈同时扫描双侧关节，扫描序列常规做冠状面T1WI，如发现有骨缺血性坏死征象，加扫短时反转恢复（STIR）序列。178例在MR检查的同一天还行双髋关节正位和蛙式位数字X线摄影（DR）片。所有MR图像由3位高年资医生阅片，诊断有无骨缺血性坏死。由2位医生在不知道MRI结果的情况下阅读双髋关节正位和蛙式位DR片，判断有无骨缺血性坏死。448例中在“SARS临床研究数据库”有用药记载者386例，其中361人在治疗过程中使用激素并记载了剂量和时间；“SARS临床研究数据库”无用药记载的其余62例中有59例自述治疗时使用激素。结果骨缺血性坏死的MRI表现为关节面下骨髓内出现弧形或线形异常信号带，T1WI为低信号，在STIR序列上为高信号，与临床上所见的因其他疾病而使用激素或饮酒等原因引起的骨缺血性坏死表现相同。MRI筛查发现在448例中共有138例（30．8％）出现1处以上骨缺血性坏死。28例未用激素的患者中有1例出现有股骨干骨梗死征象（1／28），420例使用激素患者的MRI筛查发现137例（32．6％）出现至少1处骨缺血性坏死MRI表现，两组间差异有统计学意义（P〈0．05）。股骨头缺血性坏死101例，均有使用激素史，占激素使用者的24．0％（101／420）。膝关节骨缺血性坏死84例，占激素使用者的20．0％（84／420）。同时累及股骨头和膝关节者48例，占激素使用者的11．4％（48／420），仅发生在股骨头者53例，占激素使用者的12．6％（53／420），而仅发生于膝关节者36例，占激素使用者的8．6％（36／420）。192例双侧肩关节和踝关节MR扫描发现肱骨头缺血性坏死26例（13．5％），踝关节骨缺血性坏死13例（6．8％）。178例DR和MRI诊断股骨头坏死的阳性符合率为14．1％，DR诊断的敏感度为11．0％，特异度为97．0％。秩和检验显示骨缺血性坏死组的激素总剂量，甲泼尼龙（甲强龙）的使用时间、平均日剂量和总剂量均大于无坏死组（P〈0．05）。多因素Logistic回归分析表明甲泼尼龙日平均剂量和平均使用时间是发生骨坏死的危险因素（P〈0．05）。结论MRI筛查发现北京地区使用激素治疗的SARS患者的骨缺血性坏死患病率较高，主要发生在股骨头、膝、肩和踝关节，常累及多个部位，多数为双侧同时受累。是否使用激素、激素使用剂量和时间是发生骨坏死的危险因素。     

Clinical MRI of acute ischemic stroke

The most important service that imaging provides to patients with ischemic stroke is to rapidly identify those patients who are most likely to benefit from immediate treatment. This group includes patients who have severe neurological symptoms due to an occlusion of a major artery, and who are candidates for recanalization using intravenous thrombolysis or intra-arterial intervention to remove the occlusion. Outcomes for these patients are determined by symptom severity, the artery that is occluded, the size of the infarct at the time of presentation, and the effect of treatment. MRI provides key physiological information through MR angiography and diffusion MRI that has been proven to be of high clinical value in identify patients who are in need of immediate treatment. Perfusion MRI provides information about the ischemic penumbra, but its clinical value is unproven. In current clinical practice, the time since stroke onset is dominant over physiologic information provided by MRI in treatment decisions. This will change only when clinical trials prove that stroke physiology as revealed by MRI is superior to time from stroke onset in promoting good clinical outcomes.     

Predicting final infarct size using acute and subacute multiparametric MRI measurements in patients with ischemic stroke

PURPOSE: To identify early MRI characteristics of ischemic stroke that predict final infarct size three months poststroke. MATERIALS AND METHODS: Multiparametric MRI (multispin echo T2-weighted [T2W] imaging, T1-weighted [T1W] imaging, and diffusion-weighted imaging [DWI]) was performed acutely (<24 hours), subacutely (three to five days), and at three months. MRI was processed using maps of apparent diffusion coefficient (ADC), T2, and a self-organizing data analysis (ISODATA) technique. Analyses began with testing for individual MRI parameter effects, followed by multivariable modeling with assessment of predictive ability (R(2)) on final infarct size. RESULTS: A total of 45 patients were studied, 15 of whom were treated with tissue plasminogen activator (tPA) before acute MRI. The acute DWI and DWI-ISODATA mismatch lesion size, and the interactions of ADC, T2, and T2W imaging lesion with tPA remained in the final multivariable model (R(2) = 70%). A large acute DWI lesion or DWI < ISODATA lesion independently predicted increase in the final infract size, with predictive ability 68%. Predictive ability increased (R(2) = 83%) when subacute MRI parameters were included along with acute DWI, DWI-ISODATA mismatch, and acute T2W image lesion size by tPA treatment interaction. Subacute DWI > acute DWI lesion size predicted an increased final infarct size (P < 0.01). CONCLUSION: Acute-phase DWI and DWI-ISODATA mismatch strongly predict the final infarct size. An acute-to-subacute DWI lesion size change further increases the predictive ability of the model.     

Clinical impact of MRI perfusion disturbances and normal diffusion in acute stroke patients

Purpose

In acute ischemic stroke MR-imaging typically shows diffusion abnormalities surrounded by reduced perfusion signifying the so-called ischemic penumbra. Mismatch between diffusion and perfusion abnormalities gives indication for thrombolysis. But is there an indication for thrombolytic treatment, if there is no diffusion abnormality but pathologic perfusion combined with acute stroke symptoms?.

Material and methods

MR-imaging of 1465 patients treated on our Stroke Unit between June 2004 and May 2007 retrospectively are analyzed. 6 patients met the inclusion criteria of severe neurological symptoms, large territorial perfusion disturbances, lack of diffusion abnormalities and complete neurological recovery after treatment.

Results

In all six patients MTT measurements showed a significantly depressed perfusion in the symptomatic hemisphere (p < 0.02). Time-to-peak delay correlated with the mean transit time delay (0.949, p < 0.01). Indication for thrombolysis was based on perfusion abnormalities and clinical symptoms. Stroke symptoms could be reversed in all patients without any complication.

Conclusion

Whereas diffusion imaging could not reveal any abnormality, perfusion analysis legitimated therapy with systemic thrombolysis in heavily affected patients. This work underlines the importance of multimodal MR imaging for guiding treatment decisions in acute stroke patients.     

Comparison of CT with diffusion-weighted MRI in patients with hyperacute stroke

Tissue changes in ischaemic stroke are detectable by diffusion-weighted MRI (DWI) within minutes of the onset of symptoms. However, in daily routine CT is still the preferred imaging modality for patients with acute stroke. Our purpose of this study was to determine how early and reliably ischaemic brain infarcts can be identified by CT and DWI. Three neuroradiologists, blinded to clinical signs but aware that they were dealing with stroke, analysed the CT and DWI of 31 patients with an acute ischaemic stroke. We calculated k-values to analyse inter-rater variability. The ratings were compared with follow-up studies showing the extent of the infarct. The combined assessment of all observers gave positive findings in 77.4 % of all CT examinations, with k = 0.58. Areas of high signal were seen on all DWI studies by all observers (k = 1). Estimation of the extent of the infarct based on DWI yielded k = 0.70 and that based on CT k = 0.39. DWI was much more reliable than CT in the detection of early ischaemic lesions and we believe that it should be used in acute ischaemic stroke before aggressive therapeutic intervention. Received: 11 August 2000 Accepted: 29 November 2000     

MRI in acute subarachnoid haemorrhage; findings with a standardised stroke protocol

There is doubt as to whether acute haemorrhage is visible on MRI. We carried out MRI within 6 h of symptom onset on five patients with minor (low Hunt and Hess grades 1 or 2) subarachnoid haemorrhage (SAH) diagnosed by CT to search for any specific pattern. We used our standard stroke MRI protocol, including multiecho proton density (PD)- and T2-weighted images, echoplanar (EPI) diffusion- (DWI) and perfusion- (PWI) weighted imaging, and MRA. In all cases SAH was clearly visible on PD-weighted images with a short TE. In four patients it caused a low-signal rim on the T2*-weighted source images of PWI, and DWI revealed high signal in SAH. In the fifth patient SAH was perimesencephalic; susceptibility effects from the skull base made it impossible to detect SAH on EPI DWI and T2*-weighted images. Perfusion maps were normal in all cases. MRA and conventional angiography revealed an aneurysm in only one patient. Stroke MRI within 6 h of SAH thus shows a characteristic pattern.     

MRI of acute post-ischemic cerebral hemorrhage in stroke patients: diagnosis with T2*-weighted gradient-echo sequences

The use of T2^*-weighted sequences has been advocated for early differentiation between hematoma and ischemia in patients with acute stroke. Early hemorrhagic transformation of ischemic stroke is an adverse event which may occur under treatment and may impair the prognosis: our aim is to evaluate the ability of T2*-weighted gradient-echo sequence (T2^* GRE) to detect post-ischemic cerebral hemorrhage. The imaging procedure included: (1) baseline CT scan at admission. (2) MRI performed within 24 h of therapy onset including: (a) dual fast spin echo T2 sequence, (b) axial isotropic echoplanar diffusion-weighted imaging sequence, (c) conventional T2* GRE, and (d) 3D TOF turbo MRA. Post-ischemic cerebral hemorrhage was diagnosed if T2^* GRE detected a focal intraparenchymal area of signal loss. The diameter of this lesion had to be more than 5 mm in order to eliminate past microbleeds. (3) Patients who showed an early suspicion of bleeding on MRI promptly had a second CT scan, and, if this one was negative for bleeding, another CT scan was performed 1 day later. All the other patients had a control CT scan during the first week. Forty-five consecutive patients have been included. T2* GRE showed intracranial bleeding in seven. The diagnosis of post-ischemic cerebral bleeding was confirmed by CT in all patients. Control CT scans did not reveal any post-ischemic cerebral hemorrhage in patients with negative MRI. In one case, hemorrhage was seen earlier on MRI than on CT scan. In conclusion, T2^* GRE appeared to be at least as efficient as CT scan in the detection of early post-ischemic cerebral hemorrhage. Received: 30 October 2000/Accepted: 23 March 2001     

Mechanical thrombectomy with snare in patients with acute ischemic stroke

Introduction We evaluated the efficacy and safety of thrombus extraction using a microsnare in patients with acute ischemic stroke (AIS). Methods This was a prospective, observational, cohort study in which consecutive patients with AIS (<6 hours of ischemia for anterior circulation and <24 hours for posterior circulation) who had been previously excluded from intravenous tissue plasminogen activator (tPA) thrombolysis were included and followed-up for 3 months. Mechanical embolectomy with a microsnare of 2–4 mm was undertaken as the first treatment. Low-dose intraarterial thrombolysis or angioplasty was used if needed. TIMI grade and modified Rankin stroke scale (mRSS) score were used to evaluate vessel recanalization and clinical efficacy, respectively. Results Nine patients (mean age 55 years, range 17–69 years) were included. Their basal mean NIHSS score was 16 (range 12–24). In seven out of the nine patients (77.8%) the clot was removed, giving a TIMI grade of 3 in four patients and TIMI grade 2 in three patients. Occlusion sites were: middle cerebral artery (four), basilar artery (two) and anterior cerebral artery plus middle cerebral artery (one). The mean time for recanalization from the start of the procedure was 50 min (range 50–75 min). At 3 months, the mRSS score was 0 in two patients and 3–4 in three patients (two patients died). Conclusion According to our results, the microsnare is a safe procedure for mechanical thrombectomy with a good recanalization rate. Further studies are required to determine the role of the microsnare in the treatment of AIS.     

MRI在MRKH综合征诊断中的应用价值

目的：分析 MRK H 综合征的 MRI影像学特征,探讨 MRI在 MRK H 综合征临床诊断中的应用价值。方法回顾性分析经临床或手术证实为 MRKH 综合征的18例 MRI影像学特征。所有患者均行1.5T 或3.0T MRI 检查。患者取仰卧位,使用相控阵线圈对其进行检查。由2位经验丰富的放射科医生对所得 MRI图像进行评估并达成共识。评估内容包括阴道、子宫、卵巢的位置、形态,以及扫描范围内盆腔内的任何异常。结果18例中,除1例无子宫,1例为单侧(左侧)始基子宫,余16例均可见双侧始基子宫;33个始基子宫中,4个始基子宫分化成3层结构,即子宫内膜、结合带和肌壁。除1例双侧卵巢形态异常外,余17例患者双侧卵巢形态、大小及信号未见明显异常。所有患者阴道及宫颈缺如,其中1例阴道区可见囊性液体信号。结论 MRI在 MRK H综合征的明确诊断中发挥重要作用,可对患者手术方案的选择起指导作用。     

MRI预测急性脑梗死后出血的价值

目的探讨急性脑梗死患者MR早期增强T1WI中脑实质强化及大脑中动脉高信号（HMCA）征与继发性脑出血（HT）的关系。方法回顾性分析24例发病6．0h内[平均（4．3±1．4）h]的急性脑梗死患者首次T1WI及随后1周内复查的MRI和（或）CT资料，了解首次增强T1WI脑实质强化和HMCA征与HT的关系。早期脑实质强化为脑梗死6．0h内缺血的脑组织区域在增强T1WI出现高信号；HMCA征为增强T1WI上大脑中动脉增粗（与对侧相比）、出现边缘模糊的高信号。结果24例患者中10例发展为HT（出血组），其中6例首次T1WI可见脑实质强化，5例出现HMCA征；14例未出现HT（无出血组），均未发现脑实质强化和（或）HMCA征。2组相比，T1WI脑实质强化、HMCA征出现率差异均有统计学意义（P值均〈0．01）。结论T1WI早期脑实质强化和HMCA征有可能预测急性脑梗死后HT。     

Imaging preventable infarction in patients with acute ischemic stroke

One of the goals of neuroimaging in acute ischemic stroke is to identify those patients whose outcome will be improved by therapeutic intervention. This article will discuss the design, analysis, and interpretation of clinical research studies carried out to establish the accuracy and clinical value of neuroimaging to select such patients.     

Brain perfusion-CT in acute stroke patients

The role of neuro-imaging in the evaluation of acute stroke has changed dramatically in the past decade. Previously, neuro-imaging was used in this setting to provide anatomic imaging that indicated the presence or absence of acute cerebral ischemia and excluded lesions that produce symptoms or signs mimicking those of stroke, such as hemorrhage and neoplasms. More recently, the introduction of thrombolysis has changed the goals of neuro-imaging from providing solely anatomic information to providing physiologic information that could help to determine which patients might benefit from therapy. In particular, significant emphasis has been placed on the delineation of the ischemic penumbra, also called tissue at risk. Modern CT survey, consisting of three indissociable elements: noncontrast CT (NCT) of course, perfusion-CT (PCT) and CT-angiography (CTA), fulfill all the requirements for hyperacute stroke imaging. CTA can define the occlusion site, depict arterial dissection, grade collateral blood flow, and characterize atherosclerotic disease, whereas PCT accurately delineates the infarct core and the ischemic penumbra. CT offers a number of practical advantages over other cerebral perfusion imaging methods, including its wide availability. Using PCT and CTA to define new individualized strategies for acute reperfusion will allow more acute stroke patients to benefit from thrombolytic therapy.     

Brain perfusion-CT in acute stroke patients

The role of neuro-imaging in the evaluation of acute stroke has changed dramatically in the past decade. Previously, neuro-imaging was used in this setting to provide anatomic imaging that indicated the presence or absence of acute cerebral ischemia and excluded lesions that produce symptoms or signs mimicking those of stroke, such as hemorrhage and neoplasms. More recently, the introduction of thrombolysis has changed the goals of neuro-imaging from providing solely anatomic information to providing physiologic information that could help to determine which patients might benefit from therapy. In particular, significant emphasis has been placed on the delineation of the ischemic penumbra, also called tissue at risk. Modern CT survey, consisting of three indissociable elements: noncontrast CT (NCT) of course, perfusion-CT (PCT) and CT-angiography (CTA), fulfill all the requirements for hyperacute stroke imaging. CTA can define the occlusion site, depict arterial dissection, grade collateral blood flow, and characterize atherosclerotic disease, whereas PCT accurately delineates the infarct core and the ischemic penumbra. CT offers a number of practical advantages over other cerebral perfusion imaging methods, including its wide availability. Using PCT and CTA to define new individualized strategies for acute reperfusion will allow more acute stroke patients to benefit from thrombolytic therapy.     

MRI findings of 26 patients with Parsonage-Turner syndrome

OBJECTIVE: The objective of our study was to describe the MRI features of patients with Parsonage-Turner syndrome. Familiarity with the MRI features associated with this entity is important because radiologists may be the first to suggest the diagnosis. Twenty-six patients with Parsonage-Turner syndrome were treated at our institution between 1997 and 2005. We retrospectively reviewed the MR images of patients with clinical or electromyographic evidence (or both) of acute brachial neuritis without a definable cause. CONCLUSION: MRI of the brachial plexus and shoulder in patients with Parsonage-Turner syndrome showed intramuscular denervation changes involving one or more muscle groups of the shoulder girdle. The supraspinatus and infraspinatus muscles were the most commonly involved. MRI is sensitive for detecting signal abnormalities in the muscles of the shoulder girdle of patients with Parsonage-Turner syndrome. MRI may be instrumental in accurately diagnosing the syndrome.     

Detection of myocarditis by contrast-enhanced MRI in patients presenting with acute coronary syndrome but no coronary stenosis

PURPOSE: To prospectively assess the use of cardiac MRI with delayed contrast enhancement (DCE) for identifying patients with active myocarditis among those presenting with acute coronary syndrome (ACS) but no coronary stenosis. MATERIALS AND METHODS: A total of 27 consecutive patients (age = 45 +/- 17 years; 14 male) presenting with ACS (chest pain, positive troponin-I) and no coronary stenosis, underwent cardiac MRI 9 +/- 7 days after pain onset and 8 +/- 5 months later (N = 19). Steady-state free-precession pulse (SSFP) sequence was applied for the assessment of myocardial function and both inversion-recovery (IR) and SSFP sequences were used for analyzing the topography and extent of DCE areas. Rest sestamibi-gated-single photon emission CT (SPECT) was also systematically performed. RESULTS: Subepicardial DCE pattern typical of acute myocarditis was documented in 12 patients (44%). Ischemic DCE pattern (transmural or subendocardial focal DCE) was documented in 12 of the 15 remaining patients (44%). Patients with subepicardial DCE had: higher C-reactive protein (CRP) levels (38 +/- 32 vs. 14 +/- 24 mg/mL; P = 0.04), lower Framingham cardiovascular risk (3 +/- 3% vs. 9 +/- 5%; P < 0.001), lower incidence of perfusion SPECT defects (17% vs. 73%; P = 0.01), higher left ventricular (LV) end-diastolic volume (77 +/- 16 vs. 64 +/- 10 mL/m(2); P = 0.02), and higher regression of DCE areas at follow-up (-65 +/- 17% vs. -18 +/- 23%; P = 0.002). CONCLUSION: DCE pattern of active myocarditis can be seen in patients presenting with ACS but no coronary stenosis.     

Assessment of baseline hemodynamic parameters within infarct progression areas in acute stroke patients using perfusion-weighted MRI

Introduction

The value of perfusion MRI for identifying the tissue at risk has been questioned. Our objective was to assess baseline perfusion-weighted imaging parameters within infarct progression areas.

Methods

Patients with anterior circulation stroke without early reperfusion were included from a prospective MRI database. Sequential MRI examinations were performed on admission, 2?C3?h (H2), 2?C3?days (D2), and between 15 and 30?days after the initial MRI. Maps of baseline time-to-peak (TTP), mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were calculated. Lesion extension areas were defined as pixels showing de novo lesions between each MRI and were generated by subtracting successive lesion masks: V₀, baseline diffusion-weighted imaging (DWI) lesion; V₁, lesion extension between baseline and H2 DWI; V₂, lesion extension from H2 to D2 DWI; and V₃, lesion extension from D2 DWI to final FLAIR. Repeated measures analysis was used to compare hemodynamic parameters within the baseline diffusion lesion and subsequent lesion extension areas.

Results

Thirty-two patients were included. Baseline perfusion parameters were significantly more impaired within the acute DWI lesion compared to lesion extension areas (TTP, p?p?p?p?p?=?0.01) and TTP (p?=?0.01) was found within successive lesion growth areas.

Conclusion

A decreasing gradient of severity for TTP and MTT was observed within successive infarct growth areas.     

急性脑卒中患者合并吞咽困难的临床分析与康复治疗

目的观察急性脑卒中合并吞咽困难患者康复治疗的疗效评定及吸入性肺炎的发生率。方法将168例急性脑卒中合并吞咽困难的患者随机分为康复组和对照组,康复组在对照组应用药物治疗的同时给予综合康复训练治疗。治疗时间为1个月．以治疗前后患者吞咽功能恢复情况及吸入性肺炎的发生率作为观察指标。结果康复组患者吞咽功能恢复情况显著优于对照组,而其吸入性肺炎的发生率显著低于对照组。结论对于急性脑卒中合并吞咽困难的患者早期给予及时、系统的综合康复训练能够有效改善患者的吞咽功能,并显著减少此类患者吸入性肺炎的发生率。