MRI延迟强化在肥厚型心肌病中的临床意义

目的 回顾性分析肥厚型心肌病(HCM)左心室心肌肥厚MRI延迟强化与临床特征的关系.方法 收集79例HCM患者行MR检查,先常规实施心脏结构和功能检查,再进行钆对比剂延迟强化(LGE)扫描.按17节段法,分别测量心肌厚度、射血分数、左心室舒张期末容积等,并进行LGE评分.性别、胸闷等组间LGE的差异采用卡方检验,临床特征与测得数据采用Logistic回归分析,并以分析出阳性症状为参考标准评价LGE预测心脏事件的准确性,比较ROC曲线下面积.结果 79例患者共计1343节段,其中肥厚节段633个,基底段前室间隔(第2节段)肥厚节段数最多(64个),其次为第9、3和8节段,分别为58、57和57个.LGE显示受累节段433个,第2节段最多(51个),其次为第8、9和14节段,分别为39、37和36个.左心房前后直径、LGE是心房颤动的独立预测因子(HR分别为1.11和1.12,P≤0.01),ROC曲线下面积分别为0.726、0.743;LGE是非持续性室性心律失常(NSVT)的独立预测因子(HR=1.15,P≤0.01),ROC曲线下面积为0.817.结论 HCM患者心肌肥厚及LGE呈不对称性分布,LGE是HCM发生NSVT及心房颤动的独立危险因素.     

MRI of cranial chordomas: the value of gadolinium

Two intracranial chordomas are presented: a typical chordoma and a chondroid tumour. MRI with gadolinium showed different enhancement patterns, which may be related to pathological findings. The value of differentiating the two types of chordoma lies in their very different prognosis.     

神经退行性疾病脑铁负荷的MRI测量研究

铁是人体内含量最多的金属元素,在正常功能的神经元中起关键作用。铁缺乏与铁过载均可导致神经退行性疾病。神经退行性疾病中的不宁腿综合征可发现脑铁含量的减低,而阿尔茨海默病、帕金森病、亨廷顿病、多发性硬化、肌萎缩脊髓侧索硬化症等疾病发病过程都伴有铁过载。了解神经退行性疾病脑铁含量的变化对于早期疾病的诊断及临床治疗具有重要的指导意义。综述不同神经退行性疾病的脑铁含量的空间变化特点。     

High-resolution MRI of deep-seated atherosclerotic arteries using motexafin gadolinium

PURPOSE: To evaluate the potential of using motexafin gadolinium (MGd) to characterize atherosclerotic plaques of deep-seated arteries with MRI. MATERIALS AND METHODS: We exposed vascular endothelial cells (EC) and smooth muscle cells (SMC) in vitro to varying concentrations of MGd. The fluorescence properties of MGd were then exploited using confocal microscopy to image exposed cells. For an in vivo validation study, we performed surface coil-based and intravascular coil-based high-resolution MRI of the iliac arteries and the abdominal aorta of three atherosclerotic Yucatan pigs. Subsequently, MGd enhancement of the target vessel walls was quantitatively evaluated and MR images were correlated with histology of the target vessels. RESULTS: The in vitro study confirmed the intracellularization of MGd in both cell types and determined the optimum MGd dosage of 0.004 mmol/kg that produced the sufficiently high intracellular fluorescent intensity. The in vivo study showed a steady increase of MGd enhancement to approximately 25% at three hours postinjection of MGd. MRI showed areas of strong enhancement along the lumen boundary, which corresponded to fibrous tissue seen in histology. CONCLUSION: This study provides initial evidence that MGd may enhance MR vessel wall imaging for the characterization of plaque in deep-seated arteries.     

MRI of focal splenic lesions without and with dynamic gadolinium enhancement

OBJECTIVE: Our purpose was to identify the MR features of focal splenic lesions with an emphasis on enhancement patterns. The addition of a contrast-enhanced dynamic sequence to unenhanced MR images improves the study of focal splenic lesions. The analysis of the MR features along with the clinical history permits either the characterization of the most common splenic lesions or improvement in the detection of malignant diseases. CONCLUSION: Dynamic contrast-enhanced MRI improves the detection and characterization of focal splenic lesions.     

MRI of brain iron

A prominently decreased signal intensity in the globus pallidum, reticular substantia nigra, red nucleus, and dentate nucleus was routinely noted in 150 consecutive individuals on T2-weighted images (SE 2000/100) using a high field strength (1.5 T)MR system. This MR finding correlated closely with the decreased estimated T2 relaxation times and the sites of preferential accumulation of ferric iron using the Perls staining method on normal postmortem brains. The decreased signal intensity on T2-weighted images thus provides an accurate in vivo map of the normal distribution of brain iron. Perls stain and MR studies in normal brain also confirm an intermediate level of iron distribution in the striatum, and still lower levels in the cerebral gray and white matter. In the white matter, iron concentration is (a) absent in the most posterior portion of the internal capsule and optic radiations, (b) higher in the frontal than occipital regions, and (c) prominent in the subcortical "U" fibers, particularly in the temporal lobe. There is no iron in the brain at birth; it increases progressively with aging. Knowledge of the distribution of brain iron should assist in elucidating normal anatomic structures and in understanding neurodegenerative, demyelinating, and cerebrovascular disorders.     

MR延迟增强扫描在心肌炎诊断及预后评估中的应用进展

在青少年猝死病因中,心肌炎占12%,其主要病因为病毒感染,或者为病毒感染后引起的免疫性反应损伤心肌组织。目前尚无任何一种临床或者影像方法能够完全确诊心肌炎。安全、无创的MR成像能清晰显示组织解剖结构,可以定量地评价心脏功能,并能以骨骼肌信号值为参照定量评价心肌信号的改变。延迟强化征象能反映病毒性心肌炎后心肌不可逆性损伤,其诊断心肌炎的特异度高达86%。延迟增强不仅可以用于缺血性和非缺血性心肌病变的鉴别诊断,对心肌疾病尤其是心肌炎的预后评价也有重要价值。     

地中海贫血患者心脏、肝脏铁沉积的MRI定量研究

目的 定量评价地中海贫血患者心脏、肝脏铁沉积程度,探讨两者关系及临床用肝铁浓度＞ 15 mg/g干重预测心铁沉积的准确性.方法 连续搜集2010年9月至2011年6月期间103例5岁以上总输血(全血)剂量＞10 U(1 U=200 ml)地中海贫血患者资料,行心脏、肝脏MR检查并测量T2*值,采用Spearman秩相关分析其相关性.以肝脏T2*＜0.96 ms(相当于肝铁浓度＞15 mg/g干重)为标准,将患者分为两组,采用秩和检验比较各组心肌T2*值的差异.以心脏T2*＜10 ms、10 ms≤T2*＜20 ms和T2*≥20 ms为标准,将患者分为3组并采用秩和检验比较各组肝脏T2*值有无差异.绘制用肝铁浓度＞ 15 mg/g干重预测患者心脏铁沉积的ROC曲线.结果 103例地中海贫血患者的心脏T2*值中位数为24.00ms(4.70～51.10 ms),肝脏T2*值中位数为1.16 ms(0.68～14.80 ms),两者呈低度相关(r=0.453,P=0.000),且未见规律性.肝脏T2*＜0.96 ms组25例患者的心脏T2*值中位数为12.10 ms(4.70～41.70 ms),T2*≥0.96 ms组78例患者的心脏T2*值中位数为26.10 ms(4.80～51.10 ms),两组之间差异有统计学意义(Z=-3.566,P=0.000).心脏T2*＜10 ms组20例患者的肝脏T2*值中位数为1.06ms(0.68 ～3.83 ms),T2*≥20 ms组58例患者中位数为1.76 ms(0.74～14.80 ms),差异有统计学意义(Z=-3.553,P=0.000);10 ms≤T2*＜20 ms组25例患者的肝脏T2*值中位数为0.99 ms(0.69 ～ 13.59 ms),与T2*＞20 ms组间差异有统计学意义(Z=-3.951,P=0.000);心脏T2*＜10 ms组与10 ms≤T2*＜20 ms组相比,两组患者的肝脏T2*值之间差异无统计学意义(Z=-0.046,P=0.964).以肝铁浓度＞15 mg/g干重预测心脏铁沉积的ROC曲线下面积为0.771,敏感度为42.2％,特异度为89.7％.结论 多次输血地中海贫血患者的心、肝铁水平之间呈低度相关.肝铁浓度＞ 15 mg/g干重的患者心铁沉积发生率相对较高,用其预测心脏铁沉积的准确度为中等偏低.     

Usefulness of gadolinium in MRI evaluation of non surgically treated herniated disk

PURPOSE: The rationale for the use of Gadolinium (Gd) in the MRI evaluation of non surgically treated herniated disk is based on the known presence of inflammatory granulation tissue and neoangiogenesis which plays an important role in both pain and the spontaneous resorption of the hernia. The AIM: of this study was to determine the usefulness of Gd in MRI examination for detecting the inflammatory reaction around the discal hernia. MATERIALS AND METHODS: Thirty-eight patients (mean age 45 years; range 20-70 years) with non surgically treated herniated disk were evaluated with MRI between January 2000 and July 2004. T2w-FAST-SE sagittal and T1w-SE transaxial and sagittal images were acquired before and after the administration of Gd. RESULTS: Twenty out of 22 patients with acute sciatic pain (symptoms =/< 40 days) showed significant peri-hernial enhancement which facilitated the differential diagnosis with other extradural lesions, such as synovial cysts (2/22 cases), as well as the correct definition of the extension of discal hernia in the spinal canal. In the remaining 16 with chronic sciatic pain (symptoms > 6 months) the discal hernia did not show peri-hernial enhancement. CONCLUSIONS: In MRI evaluation of the herniated disk, peri-hernial enhancement is correlated with inflammatory reaction around the hernia which is associated with acute symptoms. The absence of peri-hernial enhancement in chronic herniated disk is due to the poorly vascular fibrotic tissue. Therefore, peri-hernial enhancement facilitates the differential diagnosis in uncertain cases and represents a reliable prognostic index of response to non-surgical therapy and of the possible spontaneous resorption of discal hernia.     

Superparamegnetic iron oxides for MRI

Pharmaceutical iron oxide preparations have been used as MRI contrast agents for a variety of purposes. These agents predominantly decrease T2 relaxation times and therefore cause a decrease in signal intensity of tissues that contain the agent. After intravenous adminstration, dextran-coated iron oxides typically accumulate in phagocytic cells in liver and spleen. Clinical trials have shown that iron oxide increases lesion/liver and lesion/spleen contrast, that more lesions can be depicted than on plain MRI or CT, and that the size threshold for lesion detection decreases. Decreased uptake of iron oxides in liver has been observed in hepatitis and cirrhosis, potentially allowing the assessment of organ function. More recently a variety of novel, target-specific monocrydtalline iron oxides compounds have been used for receptor and immunospecific images. Future development of targeted MRI contrast agents is critical for organ- or tissue-specific quantitative and functional MRI. Correspondence to: R. Weissleder     

Efficacy of sequential use of superparamagnetic iron oxide and gadolinium in liver MR imaging

Purpose: To evaluate the efficacy of combined (double contrast) use of superparamagnetic iron particles (SPIOs) and gadolinium (Gd) in liver MR imaging.Material and Methods: Unenhanced, Gd-enhanced, SPIO-enhanced, and both SPIO- and Gd-enhanced images were acquired at 1.5 T. Twenty patients with previously detected liver lesions were included. Fast SE-STIR, and breath-hold true FISP, fat-suppressed T1- and T2-weighted sequences were obtained with all techniques. Lesion count was assessed by consensus reading.Results: Collective evaluation of all MR sequences revealed 61 lesions in 16 patients; SPIO-enhanced MR detected lesions with a sensitivity of 95% (n=58). The sensitivity of unenhanced MR imaging was 90% (n=55). There was no statistical difference between SPIO-enhanced and unenhanced MR images. From single sequences, the greatest number of lesions was detected with the SPIO-enhanced fast SE-STIR sequence (n=56, sensitivity 92%). By using the fat-suppressed T1-weighted sequence, Gd-enhanced and both SPIO- and Gd-enhanced MR images demonstrated sensitivities of 77% (n=47) and 80% (n=49), respectively. Despite the combined use of both contrast media, this sequence was significantly less sensitive in lesion detection when compared to SPIO-enhanced imaging.Conclusion: SPIO-enhanced MR imaging was the most sensitive method in lesion detection. The benefit of the combined use of SPIO and Gd was negligible.     

MRI of cardiac iron overload

Transfusion therapy has greatly improved the survival of transfusion dependent thalassemia major (TM) patients; however, the resultant iron load damages tissues including the heart, liver and endocrine organs. Among these, heart complication still remains the leading cause of mortality. Myocardial iron deposition can occur independently of other solid organ involvement; conversely, the heart may be spared despite heavy siderosis in other tissues. Iron chelation treatment diminishes the risk of hemosiderosis; however, the chelation treatment has its own toxicities and might not be available to all patients due to costs. Close monitoring of individual organ iron concentration and function is thus important for optimization of individual patient care. This review outlines the importance and clinical significance of recently available MRI techniques for monitoring cardiac iron load. J. Magn. Reson. Imaging 2012;36:1052–1059. © 2012 Wiley Periodicals Inc.     

Extracellular biodegradable macromolecular gadolinium(III) complexes for MRI.

The clinical application of macromolecular gadolinium (Gd) complexes as MRI contrast agents is limited by the slow excretion of Gd(III) complexes and consequent long-term tissue accumulation of toxic Gd ions. To alleviate the problem of slow excretion, biodegradable polydisulfide-based macromolecular Gd(III) complexes were designed and prepared based on the disulfide-thiol exchange to allow degradation of the macromolecules by endogenous thiols and to facilitate excretion of Gd(III) complexes after the MRI examination. The in vitro degradation study showed that the polydisulfide agent was readily degraded by cysteine at plasma thiol concentrations. No cross-reaction was observed between the cysteine-34 on human serum albumin (HSA) with the agent. Concentration-dependent blood pool contrast enhancement was observed for the polydisulfide agents. The agents of both high molecular weight (35,000 Da) and low molecular weight (17,700 Da) produced significant contrast enhancement in the heart and aorta in rats at relatively high doses. Except for the bladder, the signal intensities gradually decreased over time. Significant blood pool contrast enhancement was also observed for the high molecular weight agent at a low dose (0.03 mmol-Gd/kg), but not for the agent with a lower molecular weight. The contrast enhancement in the urinary bladder increased over time for the polydisulfide agents and Gd(III)-(DTPA-BMA). Degradation products were identified by mass spectrometry in the urine samples from the rats administered with both polydisulfide agents, which confirmed that the polydisulfide agents were degraded in vivo and excreted through renal filtration. The preliminary results demonstrated the in vitro and in vivo degradability, superior blood pool contrast enhancement, and rapid clearance through renal filtration of the novel biodegradable macromolecular agent. This agent has a great potential for further preclinical and clinical development with application in contrast-enhanced blood pool and cancer MR imaging.     

Diffuse dural gadolinium MRI enhancement associated with bilateral chronic subdural hematomas

Chronic subdural hematomas (CSDHs) typically present with cognitive dysfunction and a history of trauma. Localized dural enhancement on postcontrast MRI scans associated with the surrounding membrane has been described in CSDH. We present an 83-year-old man with rapidly progressing cognitive dysfunction 4 weeks after head trauma related to a fall. MRI showed CSDHs, which in addition to localized dural gadolinium enhancement, showed a marked diffuse, symmetric, contiguous pachymeningeal enhancement of the supratentorial and infratentorial intracranial dural mater. Meningeal biopsy failed to disclose an infectious or neoplastic cause of the enhancement and instead showed fibrocollagenous change. We conclude that diffuse dural enhancement on MRI scans associated with CSDH cause does not necessarily indicate a superimposed process such as infection or malignancy. CSDH should be considered in the differential diagnosis of diffuse dural enhancement, especially when supported by appropriate clinical findings.