Early MRI in the management of clinical scaphoid fracture

The incidence of MRI detected scaphoid and other wrist fractures was determined in a clinical setting in patients with suspicion of scaphoid injury and negative initial radiographs. The influence on subsequent patient management was examined. Patients attending Accident and Emergency over a 25 month period with suspected scaphoid fracture and normal scaphoid series plain films were referred for wrist MRI. Scans comprising T(1) weighted spin echo and short tau inversion recovery (STIR) coronal sequences were performed in a dedicated extremity low field MRI scanner within 14 days of injury. Subsequent effects on patient management were ascertained by clinician completed questionnaire. 195 patients were scanned. There were 37 scaphoid fractures (19%), 28 distal radius fractures (14%), 9 fractures of other carpal bones (5%) and 119 studies with no fracture. The management of 180 patients (92%) was altered as a result of the MRI scan. Occult fractures are present in almost two fifths of patients with suspected scaphoid fracture and normal initial plain films. Half of these are scaphoid fractures. MRI allows an early definitive diagnosis to be made, changing patient management in over 90% of cases and should be regarded as the gold standard investigation in this population.     

MRI动态增强扫描在评估颈动脉斑块稳定性中的应用

目的:采用MRI动态增强扫描(DCE-MRI)测算厚壁斑块、薄壁斑块与破裂斑块容积传输常数(Ktrans),评估新生血管,为易损斑块的早期诊断提供依据。方法:怀疑有动脉粥样硬化斑块的41例患者均行MRI平扫及动态增强扫描。根据MRI平扫图像对斑块进行分类,其中厚壁斑块15个,薄壁斑块9个,破裂斑块11个。根据DCE-MRI图像后处理获得各型斑块容积传输常数(Ktrans)。结果:厚壁斑块与薄壁、破裂斑块Ktrans值比较,差异均有统计学意义(均P0.05),薄壁斑块与破裂斑块Ktrans值之间,差异无统计学意义(P0.05)。结论:Ktrans值反映了不同类型斑块新生血管及炎性浸润的不同,可作为早期评估斑块稳定性的一个指标。     

定量动态增强磁共振在乳腺肿块样腺病中的应用价值

目的：探讨定量动态增强磁共振(DCE-MRI)在诊断乳腺肿块样腺病中的应用价值。方法收集54例依据乳腺磁共振半定量增强检查方法 BI-RADS 诊断为4、5类的肿块样病灶,测量其定量灌注参数包括容量转移常数(Ktrans )、单位体积组织中血管体积(Vp )值。依据病理结果分为腺病组、乳腺癌组,将腺病组对侧腺体作为正常对照组。将腺病组和正常腺体组及腺病组和乳腺癌组 Ktrans 、Vp 值分别进行组间的两两秩和检验,绘制腺病组和乳腺癌组 Ktrans 值的受试者工作特征曲线(ROC),寻找最佳诊断界值并计算其敏感度、特异度。结果腺病组(n=21)的 Ktrans 、Vp 值分别为(0.289±0.163)min-1、(0.0428±0.045);乳腺癌组(n=33)的 Ktrans 、Vp 值分别为(0.959±0.451)min-1、0.057±0.079;正常腺体(n=21)的 Ktrans 、Vp 值分别为(0.048±0.022)min-1、0.016±0.019。腺病组与正常腺体组的 Ktrans 、Vp 值差异均有统计学意义(Z 值分别为-5.733、-2.844,P 值为0.000、0.004,P <0.05),乳腺癌与腺病组Ktrans 值差异有统计学意义(Z 值为-5.421,P 值为0.000,P<0.05),乳腺癌与腺病组 Vp 值差异无统计学意义(Z=-0.009,P =0.993,P >0.05)。Ktrans 值的 ROC 曲线下面积(AUC)为0.941,界值为0.304 min-1时,敏感度、特异度分别为93.9%、85.7%。结论定量DCE-MRI Ktrans 值作为辅助诊断的定量参数对鉴别乳腺肿块样腺病有较高的参考价值。     

增强后液体衰减反转恢复序列MRI在颅内肿瘤诊断中的应用

目的 评价增强后液体衰减反转恢复序列（FLAIR）在颅内肿瘤诊断中的应用价值。方法 104例颅内肿瘤，经手术、病理证实共有病灶124个。分别行增强前、后T1WI和FLAIR扫描。由2名有经验的放射科医生对所有病例进行评价。评价内容包括：增强例数、增强病灶个数及强化病灶部位；对比度及增强率；病变大小和范围。结果行统计学分析。结果 104例中，增强后FLAIR（CEFLAIR）成像、增强SE T1WI（CET1WI）均显示98例有强化。CEFLAIR成像检出了117个强化灶，CE T1W1检出了120个。4个病灶仅在CEFLAIR显示而CET1WI未显示。另有7个病灶仅在CET1WI显示而CEFLAIR未显示。两者之信噪比（SNR）差异无统计学意义（t=1．10，P=0．270），脑灰白质对比度（GMC）、对比噪声比（CNR）及强化率（CER）差异均有统计学意义（t值分别为2．46、7．10、9．67，P值分别为0．015、0．000、0．000）。在显示病灶大小上，CEFLAIR成像明显大于CET1WI（t=4．13，P=0．000），在病灶范围上，有62例CEFLAIR成像较CET1WI大。CEFLAIR成像对位于脑沟、凸面、侧脑室旁及侧脑室内病灶的检出优于CET1WI，而对大脑半球及第四脑室内的病灶的显示不如CET1WI。结论 CEFLAIR成像与CET1WI比较，强化病灶数，两者无明显差别，强化程度CET1WI明显高于CEFLAIR成像，但两者对不同部位病灶的显示有明显差异，CEFLAIR成像显示病灶大小和范围明显大于CET1WI。两种序列相互补充，建议将CEFLAIR成像序列列为增强后常规序列。     

动态增强MRI在评价前列腺肿瘤微血管生成的临床应用

血管生成是前列腺癌(PCa)发生、发展及转移的关键因素.动态增强磁共振成像(DCE-MRI)是静脉注射小分子质量的钆螯合物通过T1WI 及T2*WI 技术来无创地反映肿瘤组织复杂的血流动力学情况(如灌注异常,微血管的高通透性等),从而了解前列腺肿瘤血管的生成及微血管密度情况.就DCE-MRI 与前列腺肿瘤组织中微血管生成的相关性进行综述.     

MRI evaluation of myocardial viability

Cardiac magnetic resonance imaging (MRI) has become an accurate noninvasive imaging procedure for the study of postischaemic residual cardiac function, thanks to the evolution of MRI machines, postprocessing software and, above all, sequences. After infarction, and in chronic myocardial ischaemia, the degree of contractile dysfunction is one of the main determinants of longterm survival. The identification and quantification of viable dysfunctional myocardium and the possibility of improving its contractility after revascularisation improves patient prognosis and quality of life. In current clinical practice, myocardial viability is evaluated with stress echocardiography and nuclear methods. Thanks to its intrinsic characteristics and to the delayed-enhancement technique (DE-MRI), MRI has recently emerged as the only noninvasive modality able to provide a three-dimensional (3D) evaluation of cardiac viability with a multiparametric approach.     

Assessment of ameloblastomas using MRI and dynamic contrast-enhanced MRI

We retrospectively evaluated magnetic resonance images (MRI) and dynamic contrast-enhanced MRI (DCE-MRI) of ameloblastomas. MRI and DCE-MRI were performed for 10 ameloblastomas. We obtained the following results from the MRI and DCE-MRI. (a) Ameloblastomas can be divided into solid and cystic portions on the basis of MR signal intensities. (b) Ameloblastomas show a predilection for intermediate signal intensity on T1WI, high signal intensity on T2WI, and well enhancement in the solid portion; they also show a homogeneous intermediate signal intensity on T1WI and homogeneous high signal intensity on T2WI, and no enhancement in the cystic portion. (c) The mural nodule or thick wall can be detected in ameloblastomas lesions. (d) CI curves of ameloblastomas show two patterns: the first pattern increases, reaches a plateau at 100-300 s, then sustains the plateau or decreases gradually to 600-900 s, while the other increases relatively rapidly, reaches a plateau at 90-120 s, then decreases relatively rapidly to 300 s, and decreases gradually thereafter. There was no difference in the CI curve patterns among primary and recurrent cases, a case with glandular odontogenic tumor in ameloblastoma or among histopathological types such as plexiform, follicular, mixed, desmoplastic, and unicystic type.     

Quantitative analysis of vertebral bone marrow perfusion using dynamic contrast-enhanced MRI: initial results in osteoporotic patients with acute vertebral fracture

Purpose:

To evaluate the potential of quantitative dynamic contrast‐enhanced MRI (DCE‐MRI) in vertebral bone marrow (vBM) of patients with acute osteoporotic vertebral compression fractures.

Materials and Methods:

Twenty‐six patients with acute osteoporotic fractures (16 female, 10 male, median age 72, range 48–89) and 10 subjects without known history of osteoporosis (6 female, 4 male, median 65, range 31–77) were examined 2D‐DCE‐MRI. Region of interest (ROI) data in fractured (n = 26) and normal‐appearing vertebrae (n = 271) were analyzed with a two‐compartment tracer‐kinetic‐model, providing estimates of at least three independent parameters: plasma flow (PF), plasma volume (PV), and extraction flow (EF). Parameters were correlated with dual x‐ray absorptiometry (DXA) (n = 15) and quantitative computed tomography (QCT) densitometry (n = 10).

Results:

Mean PF was significantly higher in fractures than in normal‐appearing vertebrae (69.37 vs. 11.72 mL/100 mL/min). Similarly, mean PV and EF differed significantly. Mean PF was significantly decreased in normal‐appearing vBM osteoporotic patients compared to the control group. Mean PF and PV were significantly decreased in lumbar compared to thoracic vertebrae. PV showed a significant correlation with QCT.

Conclusion:

Perfusion parameters were decreased significantly in normal‐appearing vBM of patients. Furthermore, significant perfusion alterations were observed in acute osteoporotic vertebral fractures compared to normal‐appearing vertebrae. J. Magn. Reson. Imaging 2011;33:676–683. © 2011 Wiley‐Liss, Inc.     

子宫腺肌瘤的磁共振成像动态增强特征

目的探讨子宫腺肌瘤的磁共振成像(MRI)动态增强特征。方法选取23例经病理证实为子宫腺肌瘤的患者作为研究对象,均行常规MRI平扫、动态增强扫描,选取瘤灶及邻近的子宫内膜为感兴趣区域,计算各感兴趣区域在增强16、32、48、64、128 s时相强化速率(Sp),用配对样本t检验分析各时相瘤灶与其邻近的子宫内膜强化速率的差异;分析两者的时间-信号强度曲线(TIC)的特征。结果子宫腺肌瘤与子宫内膜的各时相Sp差异无统计学意义(P>0.05),同一患者的子宫腺肌瘤与邻近子宫内膜的TIC形态近似,且表现为早期急速上升至峰值,后为持续的平台期。结论 MRI动态增强有助于子宫腺肌瘤的诊断及鉴别诊断。     

Feasibility of multiple-mouse dynamic contrast-enhanced MRI.

Dynamic contrast-enhanced (DCE-) MRI is often used to evaluate the response to experimental antiangiogenic therapies in small animal models of cancer. Unfortunately, DCE-MRI studies often require a substantial investment of both time and money to achieve the desired level of statistical significance. Multiple-mouse MRI has previously been used to improve imaging efficiency, but its feasibility for DCE-MRI has not been investigated. The purpose of this work was to determine if multiple-mouse DCE-MRI is feasible when using gadolinium-based contrast agents with a low molecular weight. A population of tumor-bearing mice was scanned using two four-element arrays and a single-coil configuration on a 4.7T, 40 cm bore Bruker Biospec MRI scanner. Pharmacokinetic parameters were calculated and compared to determine if a significant difference between methodologies existed. With both four-animal imaging configurations, animal throughput accelerations of just less than three were achieved and quantitative data were not significantly different than from single-animal acquisitions.     

Usefulness of gadolinium-enhanced MR imaging in the evaluation of the vascularity of scaphoid nonunions

OBJECTIVE: The objective of this article is to identify the role of gadolinium-enhanced MR imaging in the preoperative evaluation of the vascular status of the proximal fragment in scaphoid nonunions. SUBJECTS AND METHODS: Thirty consecutive patients (27 men and three women; age range, 19-52 years; mean age, 28 years) with nonunion of the scaphoid were prospectively examined with unenhanced and gadolinium-enhanced MR imaging. MR images and surgical findings were classified in four groups according to the vascular status of the proximal fragment (normal bone, moderate ischemic bone, severe ischemic bone, and avascular necrosis). Sensitivity, specificity, and accuracy of unenhanced and gadolinium-enhanced MR studies were calculated. Surgical findings were used as the gold standard. The postoperative rate of union at 12 months was evaluated for each group. RESULTS: Unenhanced MR imaging showed a global sensitivity of 36%, specificity of 78%, and accuracy of 68% in the preoperative evaluation of the vascular status of the proximal fragment. Correlation with the surgical findings was not statistically significant (p < 0.149). Global sensitivity, specificity, and accuracy of gadolinium-enhanced MR imaging were 66%, 88%, and 83%, respectively. Correlation with the surgical findings was good (p < 0.0001). Gadolinium-enhanced sequences allowed accurate diagnosis and enabled the creation of prognostic groups having better correlation with surgical findings and postoperative results. CONCLUSION: Gadolinium-enhanced MR imaging is the most reliable imaging method for investigating the vascularity of the proximal pole in scaphoid nonunions.     

Neurovascular MRI with dynamic contrast-enhanced subtraction angiography

The first generation of digital subtraction MR angiography using thick-slab contrast-enhanced 2D projection techniques has confirmed the potential of MRI to produce noninvasive subsecond angiograms of the craniocervical circulation. As time-resolved techniques become more sophisticated and 3D acquisitions can be obtained with high isotropic spatial resolution we may start to see the demise of catheter angiography as a diagnostic procedure.     

Role of dynamic contrast-enhanced and diffusion weighted MRI in evaluation of hepatocellular carcinoma after chemoembolization

Purpose

To assess the role of dynamic contrast- enhanced and diffusion-weighted (DWI) MRI in the evaluation of the response of hepatocellular carcinoma (HCC) after chemoembolization.

定量动态增强MRI在乳腺癌中的研究进展

MRI具有良好的软组织分辨力,在乳腺良恶性肿瘤的鉴别以及早期评价乳腺癌治疗效果及预后中具有独特的优势,而动态增强MRI定量分析作为一种MR技术的新方法,可以准确地监测乳腺癌病灶内微血管灌注及渗透情况,并从细胞分子水平上反映出肿瘤的生物学行为。现就定量动态增强MRI的基本原理、数据采集方法、临床应用现状及技术上的局限性进行综述。     

动态增强MRI在肺肿瘤中应用的研究进展

动态增强MRI作为一种无创、快速的功能性检查技术,对肿瘤组织内部微血管情况和生物学活性的良好的反映能力。所以,在肿瘤的早期诊断与判断预后方面显示出了独特的优势,该技术已经逐渐的应用于临床,并显示出良好的效果。本文主要对动态增强MRI技术在肺肿瘤的早期诊断、鉴别诊断、判断预后等方面的应用进行综述。     

动态增强磁共振在糖尿病中的研究进展

糖尿病(diabetes mellitus,DM)是当今世界最大的公众健康问题之一.我国已成为DM第一大国[1].糖尿病血管病变是常见的DM并发症之一,也是导致DM病人死亡的主要原因之一.动态增强磁共振成像(dynamic contrast-enhanced magnetic resonance imaging,DCE-MRI)可定量描述病变内血管参数[2],是糖尿病血管病变诊断及DM疗效评价的重要工具.本文就DCE-MRI在DM中的研究进展做一简要综述.     

动态对比增强MRI对前列腺癌的诊断价值

动态对比增强磁共振成像(DCE-MRI)是近年发展起来的一项新技术,能够无创地反映肿瘤的血管生成及毛细血管通透性等血流动力学信息,在前列腺癌的检出、定位、治疗后疗效监测、指导穿刺活检等方面的应用越来越广泛,就DCE-MRI的基本原理及临床应用进行综述。     

Fundamentals of tracer kinetics for dynamic contrast-enhanced MRI

Tracer kinetic methods employed for quantitative analysis of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) share common roots with earlier tracer studies involving arterial-venous sampling and other dynamic imaging modalities. This article reviews the essential foundation concepts and principles in tracer kinetics that are relevant to DCE MRI, including the notions of impulse response and convolution, which are central to the analysis of DCE MRI data. We further examine the formulation and solutions of various compartmental models frequently used in the literature. Topics of recent interest in the processing of DCE MRI data, such as the account of water exchange and the use of reference tissue methods to obviate the measurement of an arterial input, are also discussed. Although the primary focus of this review is on the tracer models and methods for T(1) -weighted DCE MRI, some of these concepts and methods are also applicable for analysis of dynamic susceptibility contrast-enhanced MRI data.     

Alterations in renal morphology and function after ESWL therapy: evaluation with dynamic contrast-enhanced MRI

Contrast-enhanced gradient-echo MRI was used to evaluate morphological and functional alternations in the kidneys after extracorporeal shock wave lithotripsy (ESWL). Dynamic MRI with a temporal resolution of 10 s per image was performed by repeated imaging in the coronal plane after administration of gadolinium-DTPA (0.1 mmol/kg) before and after ESWL for renal calculi in 25 patients. Before ESWL 22 patients had normally functioning kidneys, characterised by a marked decrease in signal intensity in the renal medulla 30–40 s after the onset of cortical perfusion. After ESWL 8 patients had functional abnormalities: in 2 cases the medullary signal decrease was disturbed throughout the whole organ, while 6 kidneys demonstrated regional loss of concentrating ability in the medulla. Morphological alterations (oedema with blurred contours and loss of corticomedullary differentiation; parenchymal haemorrhage and haemorrhage in a cortical cyst; subcapsular, perirenal and pararenal haematoma) were detected in 9 cases. Haemorrhage was encountered more often after administration of more than 2500 shock waves; however, no such correlation was seen in the kidneys with functional disturbances following ESWL therapy. MRI proved to be a sensitive method for the assessment of morphological and functional alterations after ESWL, but longer follow-up studies are required to identify the clinical impact of these early changes.