超顺磁性氧化铁纳米粒子在脑磁共振成像中的应用

超顺磁性氧化铁纳米粒子的磁性及生物相容性,使其在生物医学多个领域的应用研究都逐渐发展起来。本文介绍磁共振成像（MRI）及脑功能磁共振成像（fMRI）基本原理。列举不同性能的磁性氧化铁粒子作为磁共振成像对比剂在脑科学应用中的研究进展。表面结合单克隆抗体、蛋白质、多肽、核苷酸分子或其它特殊聚合物的磁性氧化铁粒子具有吸收特异性（靶向性）,结合MRI可实现对脑部病变前期改变、药物输运及治疗的监测,对细胞、生物分子包括mRNA的成像及探测。经葡聚糖或聚乙二醇修饰的超顺磁性氧化铁纳米粒子血液半衰期较长,可作为对比剂用于脑fMRI成像。控制氧化铁纳米粒子的粒度及表面修饰物的物理化学性质、提高饱和磁化强度、借以接枝以各种靶向性的物质、开发具有荧光-磁性等多种性能的复合纳米粒子及掌握纳米粒子与生物分子、细胞、及生物组织之间的相互作用,则需要更深入的研究。     

SPIO纳米颗粒在肝癌磁共振早期诊断的基础研究进展

原发性肝癌(primary hepatic carcinoma,PHC)的早期发现和诊断是肝癌诊疗领域中的重要课题之一。近些年来,对分子影像学(Molecular Imaging)研究的不断深入,为肝细胞癌的早期检测和早期诊断提供了一种全新的思维方法。相对于传统的磁共振对比剂钆剂,超顺磁性氧化铁(superparamagnetic iron oxide,SPIO)具有很多优点,能够产生磁共振负性强化。在生物医学领域,超顺磁性氧化铁的应用很多,可以作为载体应用在多个方面,例如靶向探针的载体、携带药物的载体等,作为科研热点在分子影像学方面被充分关注。本文通过总结既往的研究,对SPIO纳米颗粒在肝癌磁共振早期诊断的基础研究进展进行综述。     

MR imaging enhancement with superparamagnetic iron oxidein chronic liver disease: influence of liver dysfunction andparenchymal pathology

Purpose: To analyze the influence of liver dysfunction and parenchymal pathology on the accumulation of superparamagnetic iron oxide (SPIO). Methods: We evaluated MR images of 13 patients having small hepatic neoplasms before and after administration of SPIO (10 μmol/kg). Biopsy and laboratory data confirmed the presence of severe cirrhosis in two patients, mild cirrhosis in four, chronic hepatitis in five, and normal livers in two. Degrees of liver dysfunction or liver parenchymal pathology were correlated with reductions in signal intensity of the liver and spleen after administration of SPIO. Signal intensity reduction was evaluated using a 1.5 Tesla MR unit. Results: Response to SPIO of the liver and spleen did not correlate with liver parenchymal pathology, although reductions in signal intensity of the liver were somewhat small in severely cirrhotic livers. There were slight correlations between signal intensity alterations of the liver and laboratory data such as the indocyanine green retention rate (correlation coefficient 0.47), albumin (0.36), total bilirubin (0.36), and serum glutamic oxaloacetic transaminase (GOT) (0.46). Signal intensity reduction of spleen did not correlate with liver function tests except for serum GOT. In patients with cirrhosis, heterogeneous structures were detected in the nontumorous portions of the liver. However, these did not prevent the diagnosis of small hepatomas. Conclusion: The uptake of SPIO showed some correlation with liver function but not with chronic liver parenchymal pathology. SPIO provided sufficient contrast between tumor and surrounding liver parenchyma among patients with chronic liver disease. Received: 22 August 1994/Accepted after revision: 27 January 1995     

Fast T2-weighted liver MR imaging: comparison among breath-hold turbo-spin-echo, HASTE, and inversion recovery (IR) HASTE sequences

Background: To evaluate the diagnostic efficacy of fast T2-weighted magnetic resonance (MR) imaging sequences on image quality, hepatic lesion detection, and lesion conspicuity. Methods: Three breath-hold, fast T2-weighted sequences with turbo-spin-echo (TSE), half-Fourier acquisition single-shot TSE (HASTE), and inversion recovery (IR) HASTE techniques were examined for 43 lesions in 20 consecutive patients. Evaluation was performed qualitatively on image quality and lesion detectability and quantitatively on lesion conspicuity by using lesion/liver signal-intensity and contrast-to-noise ratios. Results: Artifacts were significantly less present on the HASTE sequence (p < 0.01). Both TSE and HASTE sequences detected 39 lesions (91% each); the IR HASTE sequence detected 37 (86%). IR HASTE sequence showed a significantly higher signal-intensity ratio than did the others (p < 0.01). Conclusions: Breath-hold TSE versus breath-hold HASTE or IR HASTE is still the most robust sequence in lesion detection, image quality, and lesion conspicuity. However, the HASTE sequence offers good lesion detection and image quality, and the IR HASTE has a better signal-intensity ratio. Received: 15 January 1999/Accepted: 24 March 1999     

超顺磁性氧化铁标记骨髓间充质干细胞移植治疗兔脊髓损伤的磁共振活体示踪

目的通过蛛网膜下腔置管,将超顺磁性氧化铁(SPIO)标记后的骨髓间充质干细胞(MSCs)移植入兔脊髓损伤模型,观察脊髓损伤MR活体示踪移植细胞的可行性。方法制作兔SCI模型,并在蛛网膜下腔置管以备移植。将实验用大白兔随机分为三组:A组为移植SPIO标记细胞;B组为移植未标记细胞;C组不移植细胞只注射PBS液做对照组。在细胞移植后3d、7d、14d、21d,进行MR活体示踪,并做病理学检测进行对照。结果 SPIO标记的MSCs移植入脊髓损伤模型后7d,MR扫描的T2WI上脊髓损伤区域出现点状低信号影;14d后T2WI上脊髓损伤区域的点状低信号影增多,21d后T2WI上脊髓损伤区域的点状低信号影减少。脊髓损伤区域组织切片行普鲁士蓝染色,发现局部组织上出现大量含蓝色铁颗粒的细胞,其细胞变化规律与MR示踪结果一致。结论蛛网膜下腔移植的SPIO标记MSCs可定向迁移到脊髓损伤区域,利用MR可对移植细胞进行活体示踪。     

Icteric-type hepatoma: magnetic resonance imaging and magnetic resonance cholangiographic features

Background: We evaluated the imaging features of magnetic resonance imaging (MRI) and magnetic resonance cholangiography (MRC) of icteric-type hepatoma and correlated these with the findings of endoscopic retrograde cholangiography (ERC), percutaneous cholangiography, and surgery. Methods: Thirteen patients with viral hepatitis complicated by cirrhosis of the liver and obstructive jaundice underwent MRC and dynamic MRI. Five patients received percutaneous transhepatic cholangiography and drainage; one of these patients also underwent resection of the left hepatic lobe. Another patient received MRC followed by thrombectomy and T-tube insertion. ERC and endoscopic nasobiliary drainage were performed in another patient for bile diversion. Results: Primary liver tumors and dilatation of biliary system were demonstrated in all patients. No capsule formation could be found in any primary liver tumors. MRI showed the simultaneous presence of an intraluminal tumor in the portal trunk and common hepatic duct in eight patients. Three different MRC features were found: (a) an oval defect in the hilar bile duct(s) with dilated intrahepatic ducts (n= 9), (b) dilated intrahepatic ducts with missing major bile ducts (n= 2), and (c) localized stricture of the hilar bile duct(s) (n= 2). Conclusion: The presence of one or more of the following features in multiplanar MRI and MRC help to identify this rare, specific type of hepatocellular carcinoma: (a) the presence of an intraluminal tumor in both the portal trunk and the common hepatic duct, (b) enhancement of the intraluminal tumor in the common hepatic duct on the arterial phase, (c) type I MRC feature, and (d) hemobilia, blood clot within the gallbladder, and/or type II MRC feature. Received: 12 January 2000/Revision accepted: 12 July 2000     

Biopsy-based calibration of T2* magnetic resonance for estimation of liver iron concentration and comparison with R2 Ferriscan

Background

There is a need to standardise non-invasive measurements of liver iron concentrations (LIC) so clear inferences can be drawn about body iron levels that are associated with hepatic and extra-hepatic complications of iron overload. Since the first demonstration of an inverse relationship between biopsy LIC and liver magnetic resonance (MR) using a proof-of-concept T2* sequence, MR technology has advanced dramatically with a shorter minimum echo-time, closer inter-echo spacing and constant repetition time. These important advances allow more accurate calculation of liver T2* especially in patients with high LIC.

Methods

Here, we used an optimised liver T2* sequence calibrated against 50 liver biopsy samples on 25 patients with transfusional haemosiderosis using ordinary least squares linear regression, and assessed the method reproducibility in 96 scans over an LIC range up to 42 mg/g dry weight (dw) using Bland-Altman plots. Using mixed model linear regression we compared the new T2*-LIC with R2-LIC (Ferriscan) on 92 scans in 54 patients with transfusional haemosiderosis and examined method agreement using Bland-Altman approach.

Results

Strong linear correlation between ln(T2*) and ln(LIC) led to the calibration equation LIC = 31.94(T2*)^-1.014. This yielded LIC values approximately 2.2 times higher than the proof-of-concept T2* method. Comparing this new T2*-LIC with the R2-LIC (Ferriscan) technique in 92 scans, we observed a close relationship between the two methods for values up to 10 mg/g dw, however the method agreement was poor.

Conclusions

New calibration of T2* against liver biopsy estimates LIC in a reproducible way, correcting the proof-of-concept calibration by 2.2 times. Due to poor agreement, both methods should be used separately to diagnose or rule out liver iron overload in patients with increased ferritin.     

Hepatic MR imaging: comparison of RARE derived sequences with conventional sequences for detection and characterization of focal liver lesions

Background: We compared two T2-weighted turbo spin echo (TSE) sequences with a T2-weighted conventional SE (CSE) sequence to determine whether sequences derived from rapid acquisition with relaxation enhancement such as TSE could replace CSE for the detection and subsequent characterization of focal liver lesions. Methods: A total of 55 consecutive patients with 107 liver lesions underwent magnetic resonance imaging examinations at 1.5 Tesla, with a constant imaging protocol. TSE pulse sequences were acquired with eight echo trains (repetition time [TR], 4718 ms; echo time [TE], 90 ms; acquisition time [TA], 4.03 min; and a symmetric k-space ordering scheme) and 11 echo trains (TR, 4200 ms; TE, 140 ms; TA, 4.40 min; and an asymmetric k-space ordering scheme) and compared with CSE (TR, 2300 ms; TE, 45/90 ms; TA, 9.53 min). Images were analyzed qualitatively by scoring image quality and artifacts and counting focal liver lesions by independent reading with consensus obtained for discrepancies. Quantitative analysis was performed by measuring signal-to-noise (S/N), contrast-to-noise (C/N), and tumor–liver signal intensity (T/L) ratios. Results: T2-weighted TSE sequences provided better subjective image quality and reduced artifacts as compared with the T2-weighted CSE sequence. CSE and TSE sequences exhibited no statistically significant differences in liver S/N, lesion–liver C/N (CSE TE, 90 ms: 18.6 ± 14.0; TSE TE, 90 ms: 16.5 ± 12.9) and the detectability of focal liver lesions. Heavily T2-weighted TSE with a TE of 140 ms allowed correct characterization of focal liver lesions based on a T/L ratio of 3.0 in 84% of patients. Conclusions: T2-weighted TSE sequences are as suited as CSE for the detection (TE, 90 ms), and appear to be superior for the characterization (TE, 140 ms), of focal hepatic lesions. Whether a single sequence, such as a double-echo TSE or a single-echo TSE sequence with a TE between 110 and 120 ms, might perform both functions as well or better than CSE is unknown. However, because of time savings, TSE eventually may be preferred over CSE. Received: 13 December 1994/Accepted after revision: 31 March 1995     

MR imaging of cervical carcinoma: comparison among T2-weighted,dynamic, and postcontrast T1-weighted images with histopathological correlation

Background: To identify the reasons for misdiagnosis of the degree of stromal invasion by uterine cervical cancer with various magnetic resonance sequences. Methods: T2-weighted, dynamic, and postcontrast T1-weighted images were obtained in the sagittal plane in 20 patients with uterine cervical cancer. After evaluating these sequences for the degree of stromal invasion, histologic specimens were directly correlated with these images. Results: The degree of stromal invasion was correctly diagnosed in 15 of the 20 cases on T2-weighted images, in 12 on dynamic images, and in eight on postcontrast T1-weighted images. All misdiagnoses were due to overestimation. Histologically, peritumoral stroma showed inflammation or edema in two patients, whereas no histological abnormality was found in the other patients. A hyperintense rim, i.e., a peritumoral enhanced ring-shaped structure, was observed on the enhanced images of five patients. The hyperintense rim corresponded to the periphery of the tumor in three patients and to the cervical stroma in two patients. Conclusion: T2-weighted images permitted the most accurate evaluation of stromal invasion by uterine tumors. Overdiagnosis may be due to an abnormal intensity of the cervical stroma, which was observed more frequently on dynamic and postcontrast T1-weighted images than on T2-weighted images. Received: 10 November 1995/Accepted after revision: 13 March 1996     

Late hyperenhancement in gadolinium-enhanced magnetic resonance imaging: comparison of hypertrophic cardiomyopathy patients with and without nonsustained ventricular tachycardia

Aim To assess the extent of hyperenhancement in hypertrophic cardiomyopathy (HCM) patients with nonsustained ventricular tachycardia (NSVT) in comparison to patients without NSVT. Design In HCM patients, NSVT in Holter monitoring is a risk factor for sudden cardiac death; however, its positive predictive value is low. Varying risk of sudden death related to NSVT may be dependent on the heterogeneous extent of the arrhythmogenic substrate, which seems to be visible as hyperenhancement in gadolinium-enhanced magnetic resonance imaging (MRI). Methods Hyperenhancement was assessed in 47 HCM patients (30 males and 17 females, mean age 42 ± 12 years): 32 patients had NSVT, 15 patients had no NSVT. The extent of hyperenhancement was calculated by software and expressed as a mass. Results In HCM patients with NSVT 97% had some extent of hyperenhancement on MRI, ranging from 1 to 76 g. The mean mass of hyperenhanced myocardium was 19 ± 18 g (8.1 ± 7.6% of total left ventricular mass). In HCM patients without NSVT, a significantly lower percentage of patients (60%) had hyperenhancement (P < 0.05). However, the amount of hyperenhanced myocardium was not significantly different (13 ± 19 g, 6.3 ± 9.1% of total left ventricular mass; P < 0.05). Conclusions Hyperenhancement was visible in almost all HCM patients with NSVT (97%) and in a significantly lower percentage of patients without NSVT (60%). Whether this finding explains the increased risk of sudden death in case of NSVT is not clear, since the extent of hyperenhancement was not significantly different between the two groups.     

前列腺癌的MRI诊断：T2WI、DWI、MRS及其综合应用

目的以病理结果为参照,探讨T2WI、DWI及MRS三种成像方法及其综合应用对前列腺癌定性诊断的价值。方法 42例患者在1.5T磁共振仪上采用体部矩阵线圈结合脊柱矩阵线圈行T2WI、DWI及3DCSI1H-MRS扫描,所有病例均经直肠穿刺活检证实。按照前列腺6分区法将所得图像数据分区评估测量,采用5分制针对各分区评分,并与病理结果对照。对三种扫描方法各自所得数据以及三种方法综合评分分别做ROC曲线分析比较,计算各组方法诊断的敏感性、特异性及准确性等。结果 42例病例中15例经穿刺证实为前列腺癌,27例为前列腺良性病变。252个分区均得到病理证实,其中201个为良性,51个为恶性。各组诊断方法的敏感性、特异性及ROC曲线下面积（Az）如下：T2WI：88.2%、67.2%和0.848±0.030,最佳诊断界值为3;DWI：82.4%、81.6%和0.860±0.033,最佳诊断界值为4;MRS：84.3%、98.0%和0.961±0.016,最佳诊断界值为5;三者综合：96.1%、96.5%和0.978±0.009,最佳诊断界值为4。结论 T2WI、DWI及MRS三种方法均可以独立有效诊断前列腺癌。三种成像方法结合诊断前列腺癌的准确性显著高于三种成像技术独立诊断,其诊断结果与病理分析一致性较好。在三种成像技术中,MRS的诊断价值较高。     

1H-MRS和MR双回波技术活体半定量评价酒精性与非酒精性脂肪肝大鼠模型

目的探讨磁共振质子波谱成像（1H-MRS）技术和同、去相位（IP/OP）序列在酒精性脂肪肝（ALD）和非酒精性脂肪肝（NAFLD）大鼠模型中定量测定脂肪含量的价值。方法 120只雄性S-D大鼠随机分为对照组、实验组（高脂组、酒精组和酒精加高脂组）,在第0,4,8,12周时进行IP/OP和1H-MRS扫描,计算IP/OP的FI（fatindex）指数和1H-MRS水、脂的RLC（relativelipidcontent）指数,将FI与RLC与病理结果对照。结果各组的FI指数和RLC均与病理学结果相关（P〈0.01,r=0.54～0.96）,RLC与病理的相关性（r=0.89～0.96）高于FI（r=0.54～0.85）。FI在正常与轻度、轻度与中度脂肪肝间无统计学差异,RLC在正常、轻、中、重度分级间均存在统计学差异（F=65.072,P〈0.01）。非酒精性脂肪肝的RLC和FI与病理的相关程度相近（rRLC=0.886,rFI=0.854）,酒精性脂肪肝的RLC与病理的相关性优于FI（rRLC=0.95～0.96,rFI=0.54～0.65）。结论对于轻度脂肪肝和ALD模型,1H-MRS比IP/OP诊断准确度更高;对于中重度和/或NAFLD模型,1H-MRS和IP/OP诊断价值相近。     

主动脉瓣反流的定量评估:实时三维彩色多普勒血流成像与MRI对照研究

目的探讨实时三维彩色多普勒血流成像(RT-3DCDFI)定量评估主动脉瓣反流的价值。方法选取17例单纯性主动脉瓣反流。实时三维超声心动图采集全容积数据库和三维彩色血流信号数据库,导入TomTec三维图像工作站脱机测量左室舒张末期容积(LVEDV)、左室收缩末期容积(LVESV)和主动脉瓣彩色反流束容积(RJV),并计算左室每搏量(LVSV)和RJV/LVSV(%)。MRI测量LVEDV、LVESV和RJV,并计算LVSV和RJV/LVSV(%)。RT-3DCDFI和MRI的测值行相关性分析。结果RT-3DCDFI和MRI评价主动脉瓣反流的测值相关性良好,其中RJV测值相关性为r=0.92,Y=0.88X 3.32,P<0.0001,二者间的均数差为-2.0ml,标准差为9.5ml;RJV/LVSV(%)测值的相关性为r=0.88,Y=1.16X-10.74,P<0.0001,二者间的均数差为-2.8%,标准差为7.9%。结论RT-3DCDFI可对主动脉瓣反流进行准确定量评估,为临床评价主动脉瓣反流提供了一种简便、可靠的新方法。     

MR imaging of advanced gastric cancer: comparison of various MR pulse sequences using water and gadopentetate dimeglumine as oral contrast agents

Background: To evaluate clinical usefulness of oral contrast agents (gadopentetate dimeglumine and water) and to assess proper magnetic resonance (MR) imaging in evaluating advanced gastric cancer (AGC) by comparing different MR imaging techniques. Methods: Fifteen patients with AGC were imaged with a 1.0-T MR imager and body-array coil. All patients underwent surgery or laparascopic biopsy. Fast low-angle shot (FLASH), half-Fourier single-shot turbo spin-echo (HASTE), and true fast imaging with steady-state precession time (FISP) images were obtained after ingestion of 900 mL tap water in each patient, followed by postcontrast FLASH images after additional ingestion of gadopentetate dimeglumine (Gd-DTPA). Qualitative analysis including T-staging of AGC and scoring of imaging quality and quantitative analysis were performed prospectively. Results: In image quality and diagnostic accuracy of T-staging, FLASH imaging showed results slightly superior to those of other imaging modalities, and there was no great difference between using water and Gd-DTPA as an oral contrast agent. As for cancer-to-gastric lumen contrast-to-noise ratio (CNR), HASTE and true FISP imaging were superior to FLASH imaging with Gd-DTPA (p < 0.0001). In cancer-to-pancreas CNR, FLASH imaging without Gd-DTPA showed the best result. Conclusions: The use of Gd-DTPA as a positive contrast agent may not be imperative, and T1-weighted FLASH imaging in combination with true FISP imaging with ingestion of tap water can be very useful in evaluating AGC with MR imaging. Received: 29 October 1998/Revision accepted: 27 January 1999     

Liver MR imaging: comparison of respiratory triggered fast spin echo with T2-weighted spin-echo and inversion recovery

Background: The purpose of this study was to compare a fast spin-echo sequence combined with a respiratory triggering device (R. trig. FSE) with conventional T2-weighted spin-echo (CSE) and inversion recovery (STIR) sequences for the detection of focal hepatic lesions. Methods: We performed a prospective study of 33 consecutive patients with known or suspected hepatic tumors. All patients underwent R. trig. FSE, CSE, and STIR imaging at 1.5 T. Acquisition times were 10.7 min for the CSE sequence and ranged from 12 to 15 min for STIR and from 5 to 7 min for R. trig FSE. For each sequence, liver–spleen contrast-to-noise ratio (CNR) and liver–lesion CNR were determined quantitatively. Image artifact and sharpness were graded by using a four-point scale on each sequence by two independent readers. Both readers also independently identified hepatic lesions (up to a maximum of eight per patient). For patients with focal lesions, the total number of lesions detected (on each sequence) and the minimum size of detected lesions were also determined by each reader. Results: No significant difference was detected between R. trig. FSE and CSE or STIR in either liver–spleen CNR or liver–lesion CNR. R. trig. FSE images were equivalent to CSE and superior to STIR in sharpness (p < 0.01) and presence of artifact (p < 0.01). R. trig. FSE detected a higher number of lesions (reader 1: n = 92, reader 2: n = 86) than CSE (reader 1: n = 70, reader 2: n = 69) and a significantly higher number than STIR (reader 1: n = 71, reader 2: n = 76). Lesion structure was significantly better defined with R. trig. FSE than with STIR (p < 0.01) and CSE (p < 0.05). Conclusions: Compared with CSE and STIR, R. trig. FSE produces hepatic images of comparable resolution and detects an increased number of focal hepatic lesions in a shorter period of time. Received: 5 April 1995/Accepted: 2 May 1995     

T2-weighted MR imaging for hepatic hemangiomas: comparison of breath-hold and non-breath-hold turbo spin-echo pulse sequences with phased-array multicoil

Background: We compared T2-weighted and heavily T2-weighted breath-hold turbo spin-echo (TSE) sequences with T2-weighted non-breath-hold TSE sequence to evaluate hepatic hemangiomas on magnetic resonance (MR) with a phased-array multicoil. Methods: Twenty-two patients with 27 hemangiomas were studied at 1.0-T scanner by using T2-weighted and heavily T2-weighted breath-hold TSE sequences (18 s each) and non-breath-hold T2-weighted TSE sequences with use of a phased-array multicoil. Images were quantitatively analyzed for tumor-to-liver signal-difference-to-noise ratios (SD/Ns) and tumor-to-liver signal intensity ratios (T/Ls) and qualitatively analyzed for tumor conspicuity and motion-induced image artifacts. Results: Quantitatively, T2-weighted breath-hold TSE images showed the highest SD/Ns among the three sequences, although the differences from the heavily T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were not statistically significant (p= 0.61 and 0.06, respectively). Heavily T2-weighted breath-hold TSE images showed the highest T/Ls among the three sequences. The differences from the T2-weighted breath-hold TSE sequence and the T2-weighted non-breath-hold TSE sequence were statistically significant (p < 0.001). Qualitatively, breath-hold TSE images were superior to non-breath-hold TSE images in terms of tumor conspicuity (p < 0.01) and motion artifacts (p < 0.01). Conclusion: T2-weighted breath-hold TSE sequence is superior to T2-weighted non-breath-hold TSE sequence in the evaluation of hepatic hemangiomas on MR with a phased-array multicoil. Received: 7 April 1997/Accepted: 28 May 1997     

氢质子磁共振波谱及磁共振R2*成像在肝纤维化诊断及分期中价值的初步探讨

目的:评估氢质子磁共振波谱(1H-MRS)、磁共振(MR)R2*成像在诊断肝脏纤维化中的应用价值,并确认其对肝纤维化分期(F0～F6)的准确性。方法:对24例经组织学证实的肝纤维化患者(平均年龄为33岁)和5例健康人(平均年龄为33岁)进行R2*成像、1H-MRS成像,计算正常肝脏及纤维化肝脏R2*值(8回波、16回波、16回波抑脂序列)、脂质(Lip)和胆碱(Cho)的峰值及峰下面积。结果:8回波、16回波R2*值、脂质峰值及峰下面积在不同肝纤维化各分期间差异具有统计学意义(P<0.05),并与肝纤维化分期存在正相关性,可以区分轻、中、重度肝纤维化。当诊断肝纤维化分期≥F3,Lip峰下面积(LipAre)、Lip峰值(LipAmp)及R2*(8回波)、R2*(16回波)、R2*(16回波抑脂)值的曲线下面积分别为0.967、0.900、0.844、0.833、0.778,特异度分别为86.7%、60.0%、73.3%、66.7%、80.0%,灵敏度为100%、100%、100%、100%、83.3%。当诊断肝纤维化分期≥F1,LipAre、LipAmp、R2*(8回波)、R2*(16回波)、R2*(16回波抑脂)值的曲线下面积分别为0.643、0.592、0.827、0.827、0.816,特异度分别为100%、71.4%、100%、85.7%、100%,灵敏度为57.1%、42.9%、71.4%、78.6%、64.3%。结论:1H-MRS、MRR2*成像可用于临床评估肝纤维化,是帮助区分轻(F0～F2)、中(F3～F4)、重度(F5～F6)肝纤维化较为灵敏及特异的检测方法,并可为检出需要进行治疗的临床明显肝纤维化患者提供诊断依据。     

Solitary necrotic nodule of the liver: imaging and correlation with pathologic features

We describe two cases of solitary necrotic nodule of the liver, an uncommon nonmalignant lesion that can mimic a metastasis. The nodule appeared hypoechoic, or targetlike, on sonography, hypodense without contrast enhancement on computed tomography, and hypointense on magnetic resonance imaging, including diffusion-weighted images. These features, peculiar when considered together, are explained by the coagulative type of necrosis. Received: 13 October 2001/Accepted: 7 November 2001     

Usual and unusual causes of extrahepatic cholestasis: assessment with magnetic resonance cholangiography and fast MRI

Cholestasis may result from hepatocellular (intrahepatic) disease or biliary tract (extrahepatic) abnormalities. Etiologies causing extrahepatic cholestasis are extremely diverse and invasive procedures, such as endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC), were previously required to establish the diagnosis. Due to refinements of magnetic resonance imaging (MRI) techniques, the patient with extrahepatic cholestasis currently can be evaluated noninvasively, and the information revealed frequently exceeds the findings obtained by ERCP and PTC. In this essay, we illustrate the classic MR cholangiographic (MRC) and MRI features of a variety of disorders causing extrahepatic cholestasis, including non-neoplastic disorders of the biliary tract (congenital abnormalities, infectious processes, iatrogenic disorders, and postsurgical complications) and neoplastic conditions (e.g., tumors of the pancreas, biliary tree, liver, ampulla, and regional lymph nodes). In most cases, familiarity with the key MRC features in addition to information obtained via cross-sectional MR images provide sufficient information for adequate lesion characterization.     

Angiomyolipoma of the liver with least amount of fat component: imaging features of CT, MR, and angiography

We report two cases of angiomyolipoma of the liver, where small amounts of fat on computed tomography, magnetic resonance imaging, and angiography made distinguishing this tumor from other hypervascular tumors difficult. Recognizing the imaging features of no capsule, hypervascularity of the tumor including the fat component, and early venous drainage may be helpful for correctly diagnosing angiomyolipoma of the liver. Received: 20 June 2001/Accepted: 1 August 2001