Fast FLAIR MRI in childhood white-matter abnormalities

We compared a fast fluid-attenuated inversion recovery (FLAIR) pulse sequence with a dual-echo short tau fast inversion-recovery (DESTTIR) sequence in 20 children with white matter abnormalities. Although the overall image quality of DESTTIR images was better, the lesion-to-background contrast was significantly higher with the fast FLAIR pulse sequence and lesion detection was more accurate. Received: 20 June 1997 Accepted: 1 October 1997     

Dynamic contrast-enhanced subtraction MR angiography in intracranial vascular abnormalities

We present our clinical experience with dynamic contrast-enhanced MR angiography (MRA) with subtraction for assessing intracranial vascular abnormalities. Ten patients with various cerebrovascular disorders underwent dynamic contrast-enhanced MRA on a 1.0-T system. Thirty sections (2 mm) were acquired in 29–30 s. Maximum intensity projection images and subtracted source images were compared with those obtained by conventional angiography. In all cases, the presence or absence of abnormalities in the targeted vessels, as well as the morphology of the sagittal sinuses, was clearly visualized as in conventional angiography, without any obstructions such as hyperintense hematomas or thrombi, or intraluminal turbulence. Although the temporal and spatial resolutions with current hardware are insufficient, these preliminary results suggest that dynamic contrast-enhanced MRA with subtraction may be useful for assessing vascular lesions with hemorrhage or thrombus, and the dural sinuses. Received: 4 November 1998; Accepted: 17 May 1999     

MR angiography of the supra-aortic arteries using a dedicated head and neck coil: image quality and assessment of stenoses

Our purpose was to evaluate a dedicated head and neck coil for demonstration of supra-aortic arteries with optimised magnetic resonance angiography techniques. We performed 47 examinations with a 1.5-T system. We used coronal 3D fast imaging with steady precession (FISP), axial 3D tilted optimised nonsaturating excitation (TONE) and 2D fast low-angle shot (FLASH) for the carotid bifurcation, axial 3D TONE with or without magnetisation transfer (MT) for intracranial arteries, and axial 3D FISP or TONE for the aortic arch. Evaluation included visual assessment of image quality and grading of stenoses near the carotid bifurcation; digital subtraction angiography was used as the reference method. Axial 3D TONE gave superior image quality at the carotid bifurcation, MT-TONE intracranially, and 3D FISP for the aortic arch vessels. Nevertheless, sensitivity and specificity for detection of significant stenoses were similar with coronal 3D FISP (96.3 %, 94.0 %), axial 3D TONE (92.6 %, 92.5 %) and axial 2D FLASH (96.3 %, 86.6 %). Image quality at the aortic arch needs further improvement. Received: 29 November 1996 Accepted: 7 February 1997     

烟雾病MRI和MRA诊断价值(附16例报告)

目的；评价MRI和MRA对烟雾病的诊断价值。方法：分析16例烟雾病患者的MRI、MRA表现和临床资料。MRA采用三维时间飞跃法。结果：16例患者MRA检查均显示不同程度的颈内动脉分叉以上狭窄或闭塞，其中17支后交通动脉增粗，4支眼动脉增粗；16例显示基底节区异常血管网，其中6例同时显示后部异常血管网；10例显示软脑膜吻合支增多；MRI显示脑出血或脑梗塞等脑实质改变，并能显示基底节区异常血管点状流空。结论：MRI和MRA是诊断烟雾病的有效非创伤性检查方法。对该病的诊断、筛选、随访和外科5一的评价有较大价值。     

低场MR扩散加权成像在超急性期脑梗死诊断中的应用

目的 :评价低场MR扩散加权成像 (DWI)在超急性期脑梗死 (HCI)诊断中的应用价值。方法 :对起病时间 6h内临床拟诊脑梗死的 12例患者使用 0 .2T磁共振仪行DWI和常规MRI扫描。结果 :DWI诊断HCI 8例 ,DWI阴性 4例 ;常规MRI扫描 2例符合脑梗死诊断 ,10例不符合 ,最终临床诊断为HCI 8例。DWI所见异常高信号区在以后的CT或MR随访中均见明显梗死病灶。结论 :低场DWI在HCI诊断中能得到成功运用 ,且诊断高度准确。     

MR angiography of the vein of Galen malformation

Vein of Galen malformation is a rare congenital disorder. It has been studied with most of the imaging modalities; however, there is no report in the literature on magnetic resonance (MR) angiography of the condition. This article describes two patients with the malformation studied by MR angiography—MR arteriography and MR venography.     

Magnetic resonance angiography (MRA) of the circle of Willis: a prospective comparison with conventional angiography in 54 subjects

We prospectively correlated the findings of magnetic resonance angiography (MRA) with those of transfemoral four-vessel angiography in 54 patients to investigate the direction of flow within the circle of Willis. Our primary goal was to assess the direction of flow using the size of the vessel and signal intensity, without saturation techniques. Analysis of the circle of Willis, especially the communicating arteries, was performed double-blind by two groups of two radiologists. Three types of arteries were identified: high flow or cross-cerebral circulation, patent and nonvisualised arteries. Cerebral angiography was the standard for comparison between the two methods. MRA did not reveal any arteries invisible on angiography, thus providing a specificity of 100%. The sensitivity of MRA was 89.2% for the anterior and 81.3% for the posterior communicating arteries, and 100% for the anterior, middle and posterior cerebral arteries. MRA was shown to be a useful technique for the assessment of patency of the circle of Willis.     

低场磁共振T_1FLAIR序列在颅脑肿瘤诊断中的应用

目的 :通过T1FLAIR(液体反转恢复 )序列与传统SE(自旋回波 )序列T1加权图像对比分析 ,评价T1FLAIR作为T1成像序列对颅脑肿瘤的诊断价值。方法 :对 2 3例颅脑疾病患者均用两种序列检查。结果 :在 2 3例颅脑肿瘤中 ,T1FLAIR序列对病灶显示的图像清晰度比SE序列高。结论 :在相同病变检出率的情况下 ,T1FLAIR像在显示颅脑中灰白质对比度、病变和背景对比情况及病变的边界、大小、范围方面优于传统SE序列T1加权像 ,具有重要的临床诊断价值。     

Non-enhanced MR angiography of renal artery using inflow-sensitive inversion recovery pulse sequence: A prospective comparison with enhanced CT angiography

Purpose

To prospectively evaluate the diagnostic value of non-enhanced inflow-sensitive inversion recovery (IFIR) MR angiography for the detection of renal artery stenosis (RAS), with enhanced CT angiography performed as the reference standard.

Materials and methods

Sixty consecutive patients suspected of RAS underwent both of IFIR MR and enhanced CT angiography. Subjective image quality, renal artery depiction and renal artery grading were all evaluated on artery-by-artery basis. Spearman rank correlation analysis was used to assess agreement between the two techniques. The diagnostic sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for RAS detection at IFIR MR angiography were calculated.

Results

One hundred twenty-six main renal arteries were visualized on enhanced CT and non-enhanced MR angiographic images, respectively. The Spearman rank correlation was 0.773 (P < .001) for renal artery depiction, 0.998 (P < .001) for renal arteries grading and 0.833 (P < .001) for RAS detection between the two modalities. The sensitivity, specificity, PPV and NPV of IFIR MR angiography for RAS detection demonstrated 100%, 99.0%, 92.0% and 100%, respectively.

Conclusion

Non-enhanced IFIR MR angiography had high sensitivity, specificity, PPV and NPV for RAS detection. It could be the first choice of renal artery imaging methods to avoid ionizing irradiation and renal toxicity from contrast media.     

Diagnosis of acute ischaemic stroke with fluid-attenuated inversion recovery and diffusion-weighted sequences

We evaluated the feasibility and use of diffusion-weighted and fluid-attenuated inversion-recovery pulse sequences performed as an emergency for patients with acute ischaemic stroke. A 5-min MRI session was designed as an emergency diagnostic procedure for patients admitted with suspected acute ischaemic stroke. We reviewed routine clinical implementation of the procedure, and its sensitivity and specificity for acute ischaemic stroke over the first 8 months. We imaged 91 patients (80 min to 48 h following the onset of stroke). Clinical deficit had resolved in less than 3 h in 15 patients, and the remaining 76 were classified as stroke (59) or stroke-like (17) after hospital discharge. Sensitivity of MRI for acute ischaemic stroke was 98 %, specificity 100 %. MRI provided an immediate and accurate picture of the number, site, size and age of ischaemic lesions in stroke and simplified diagnosis in stroke-like episodes. The feasibility and high diagnostic accuracy of emergency MRI in acute stroke strongly support its routine use in a stroke centre. Received: 20 May 1999 Accepted: 2 August 1999     

高场磁共振磁敏感加权成像联合液体衰减恢复序列对蛛网膜下腔出血的诊断价值

目的：评价高场磁共振磁敏感加权成像（SWI）联合液体衰减恢复序列（FLAIR）对蛛网膜下腔出血（SAH）的诊断价值。方法回顾性分析50例经磁共振诊断为蛛网膜下腔出血的患者MR表现,行常规T1WI、T2WI扫描及FLAIR、SWI序列扫描。结果50例蛛网膜下腔出血患者FLAIR及SWI均可显示,FLAIR表现为脑沟裂池内高信号,SWI为低信号,6例患者T1WI可见高信号蛛网膜下腔出血,T2WI无一例显示。结论常规MR序列诊断SAH准确率不高,FLAIR联合SWI对SAH敏感性高,诊断准确率高,可作为诊断SAH的常规序列组合。     

MRI of acute cerebral infarction: a comparison of FLAIR and T2-weighted fast spin-echo imaging

Fluid-attenuated inversion-recovery (FLAIR) sequences have been reported to provide high sensitivity to a wide range of central nervous system diseases. To our knowledge, however, FLAIR sequences have not been used to study patients with acute cerebral infarcts. We evaluated the usefulness of FLAIR sequences in this context. FLAIR sequences were acquired on a 0.5 T superconducting unit within 8 h of the onset in 19 patients (aged 26–80 years) with a total of 23 ischaemic lesions. The images were reviewed retrospectively by three neuroradiologists, and the FLAIR images were compared with T2-weighted fast spin-echo images. All but one of the ischaemic lesions involving grey matter was clearly demonstrated on FLAIR images as increased signal intensity in cortical or central grey matter. FLAIR images were particularly useful for detecting the hyperacute cortical infarcts within 3 h of onset, which were not readily detected on the spin-echo images. In 9 of 11 patients with complete proximal occlusion, the distal portion of the cerebral artery was visible as an area of high signal intensity on FLAIR images. Received: 5 June 1996 Accepted: 6 September 1996     

脑后循环缺血患者功能性后交通动脉的相位对比MR血管成像研究

目的 应用相位对比磁共振血管成像(PC MRA)定量研究脑后循环缺血(PCI)患者的功能性后交通动脉(F-PCoA)的血流动力学特征及临床意义。方法 回顾性搜集2015年4月至2017年3月南方医科大学顺德医院的PC MRA资料,临床诊断PCI且存在F-PCoA者26例(PCI组),临床排除PCI者25例(非PCI组),其中包括10例存在F-PCoA(非PCI组1)和15例不存在F-PCoA(非PCI组2)。记录基底动脉(BA)的截面积和平均流量、平均流速、最小流量、最大流量、最小流速、最大流速,并计算流量峰高(最大流量-最小流量)、流速峰高(最大流速-最小流速),记录F-PCoA的亚型、截面积、平均流量、平均流速,根据流速的正负号判断血流方向,计算F-PCoA前向后绝对流量(左侧F-PCoA前向后绝对流量+右侧F-PCoA前向后绝对流量),并进行统计分析。结果 将PCI组和非PCI组1中存在F-PCoA的36例分为3型:(1) A型:F-PCoA与解剖性后交通动脉(A-PCoA)一致30例;(2) B型:F-PCoA与A-PCoA不一致5例;(3) C型:混合型,一侧F-PCoA与A-PCoA一致但另一侧不一致1例。PCI组与非PCI组1的F-PCoA亚型构成比差异无统计学意义(χ2=0.609,P=0.737)、前向后绝对分流量差异无统计学意义(t=-0.576,P=0.568),一个心动周期内同一支F-PCoA的血流可为单向或双向,同一病例双侧F-PCoA的血流方向可相同也可不同,但PCI组的F-PCoA前向后绝对分流量曲线有更明显的主波峰。非PCI组中,非PCI组1和非PCI组2的比较,仅BA横截面积差异有统计学意义(t=-2.856,P=0.009),而性别构成、年龄分布、BA平均流量、平均流速、最小流量、最大流量、流量峰高、最小流速、最大流速及流速峰高差异均无统计学意义。结论 应用PC MRA可定量分析F-PCoA的血流方向、流速及流量等血流动力学信息,F-PCoA的前向后绝对分流量结合血流曲线的形态改变,可能为PCI诊疗提供新的辅助参考信息。     

屏气下二维冠状动脉磁共振血管造影的初步评价

目的：对二维冠状动脉（简称冠脉）磁共振血管造影（ＭＲＡ）在缺血性心脏病中的诊断价值进行初步评价。材料与方法：共１０例患者，全部经过Ｘ线冠状动脉造影（简称Ｘ线冠脉造影）检查，磁共振造影在１．５Ｔ扫描机上应用屏气下、脂肪抑制、心电门控Ｋ空间分段采集快速梯度回波技术对冠脉进行研究。结果：１０例左冠脉主干、左前降支、左旋支和右冠脉近段在ＭＲＡ上均完全显示，其冠脉ＭＲＡ左前降支、左旋支及右冠脉平均显示长度分别为６．７２±３．１６ｃｍ、３．６７±４．８１ｃｍ和７．９３±３．１２ｃｍ。与Ｘ线冠脉造影对照，ＭＲＡ发现具有血液动力学明显改变的冠脉病变（狭窄≥５０％）总的敏感性为６２．５％。结论：屏气下二维冠脉ＭＲＡ能较好显示较长节段的主要冠状动脉，对引起血液动力学明显改变的冠脉病变的显示亦有一定意义。     

三维增强MR血管成像对冠状动脉桥血管的评价

目的：探讨三维增强MR血管成像（3D CEMRA）评价冠状动脉搭桥术（CABG）桥血管开通状况的临床价值。方法：20例CABG患者共47支桥血管，用3D CEMRA方法进行了研究。MR检查距手术15d至16年。20例患者中14例CABG术后5个月至16年有胸痛症状再发，2例术后临床疑桥血管急性闭塞。对3D CEMRA资料进行评价，确认桥血管开通状况。对7例15支桥血管同时有3D CEMRA和X线血管造影者进行了双盲分析。结果：47支桥血管，3D CEMRA显示通畅25支，闭塞22支，闭塞率为46.8％。7例同时有3D CEMRA和X线血管造影者共15支桥血管，通畅8支，闭塞7支，二者显示完全一致。结论：3D CEMRA对桥血管的评价是可靠和准确的，可作为CABG术后患者一种无创性影像检查方法。     

低场磁共振FLAIR序列在皮层下动脉硬化性脑病中的应用

目的探讨低场强磁共振成像（MRI）液体衰减反转恢复（FLAIR）序列在皮层下动脉硬化性脑病（SAE）影像诊断中的应用价值。方法对65例SAE进行常规快速自旋回波（FSE）序列T2wI和FLAIR序列扫描,分析SAE在FSE及FLAIR序列中的影像表现,比较2种成像序列对SAE病变的显示效果,应用X＾2检验比较常规FSE序列T2WI及FLAIR序列图像中SAE病灶显示满意度和分级诊断的变化。结果SAEMRI表现为侧脑室前后角、体部周围、放射冠、半卯圆中心边缘模糊片状稍长T1、长T2异常信号,FLAIR序列病灶表现为高信号。FLAIR序列成像比FSE序列T2WI对SAE病灶显示满意（P〈0．05）,但对病变的分级诊断无明显差异（P〉0．05）。结论低场强条件下采用FLAIR序列诊断SAE,其效果比常规FSE序列优越,FLAIR序列可以作为一个常规序列以减少漏诊。     

Intracranial vascular stenosis and occlusion: comparison of 3D time-of-flight and 3D phase-contrast MR angiography

We compared the value of 3D time-of-flight (TOF) and phase-contrast (PC) MR angiography (MRA) for detection and grading of intracranial vascular steno-occlusive disease. Unenhanced 3D-TOF MRA and 3D-PC MRA (30–60 cm/s velocity encoding) were performed at the level of the circle of Willis in 18 patients, mean age 56 ± 10 years. Postprocessed images using a maximum-intensity projection reconstruction with multiple targetted projections were analysed. A total of 126 vessels was assessed by PC MRA and 143 by TOF MRA, with digital subtraction angiography (DSA) in 15 patients and/or transcranial Doppler sonography (TCD) in 18 as a standard. Two blinded readers reviewed the MRA, DSA and TCD examinations retrospectively. On DSA and/or TCD the two observers found 32 and 28 steno-occlusive lesions. 3D-TOF MRA was more sensitive than 3D-PC MRA (87 % and 86 % vs. 65 % and 60 %) and had a higher negative predictive value (96 % vs. 89 %). Correct grading of stenoses was achieved in 78 % by 3D-TOF and 65 % by 3D-PC MRA. Received: 24 September 1997 Accepted: 27 February 1998     

Case Report. MRI and MR angiography of basilar artery dissection in a child

MRI showed a pontine infarct and mural thickening of intermediate signal in T1-weighted images proximal to occlusion of the basilar artery in a 10-year-old boy. Two days later the mural thickening was of high signal, consistent with methaemoglobin formation and MR angiography (MRA) showed nonspecific lack of flow in the mid-segment of the basilar artery, which corresponded to a tapered occlusion at arteriography. MRI is more useful than MRA for noninvasive diagnosis of basilar artery dissection. Received: 2 August 1996 Accepted: 8 November 1996     

Rapid three-dimensional T1-weighted MR imaging with the MP-RAGE sequence.

The authors investigated the application of three-dimensional (3D) magnetization-prepared rapid gradient-echo (MP-RAGE) imaging to the acquisition of small (32 x 128 x 256) T1-weighted 3D data sets with imaging times of approximately 1 minute. A theoretical model was used to study the contrast behavior of brain tissue. On the basis of these theoretical results, 3D MP-RAGE sequences were implemented on a 1.5-T whole-body imager. Thirty-two-section 3D data sets demonstrating good signal-to-noise ratios and resolution and strong T1-weighted contrast were obtained in 1 minute. Compared with standard short TR/TE spin-echo sequences with the same imaging times and comparable sequence parameters, the 3D MP-RAGE sequence delivered increases of more than 50% in the white matter/gray matter signal difference-to-noise and white matter signal-to-noise ratios, and provided almost twice as many sections. These sequences may find a clinical role in 3D scout imaging and screening and in patients with claustrophobia or trauma.     

Degenerative diseases of the cervical spine: comparison of a multiecho data image combination sequence with a magnetisation transfer saturation pulse and cervical myelography and CT

Assessing degenerative disease in the cervical spine remains a challenge. There is much controversy about imaging the cervical spine using MRI. Our aim in this prospective study was to compare a T2*-weighted 2D spoiled gradient-echo multiecho sequence (MEDIC) with a magnetisation transfer saturation pulse with cervical myelography and postmyelographic CT. Using an assessment scale we looked at the vertebral bodies, intervertebral discs, neural foramina, anterior and posterior nerve roots, grey matter, ligamenta flava, oedema in the spinal cord and stenosis of the spinal canal. We also evaluated postmyelography CT and the MEDIC sequence for assessing narrowing of the neural foramina in a cadaver cervical spine. We examined 67 disc levels in 18 patients, showing 18 disc prolapses and 21 osteophytes narrowing the spinal canal or the neural foramina. All MRI studies showed these abnormalities findings equally well. Postmyelography CT was significantly better for showing the bony structures and the anterior and posterior nerve roots. The MEDIC sequence provided excellent demonstration of soft-tissue structures such as the intervertebral disc and ligamentum flavum. No statistical differences between the imaging modalities were found in the assessment of narrowing of the neural foramina or the extent of spinal stenosis. The cadaver measurements showed no overestimation of abnormalities using the MEDIC sequence.