磁共振动态增强和脂肪抑制技术在胰腺癌诊断中的价值

目的 了解磁共振动态增强和脂肪抑制技术在胰腺诊断中的价值。材料与方法 １８例经手术病理证实的胰腺癌患者进行了磁共振检查,采用在磁共振序列分别为：ＳＥＴ１ＷＩ、ＦＳＥＴ２ＷＩ、脂肪抑制技术ＳＥＴ１ＷＩ和动态增强ＦＭＰＳＰＧＲ等。结果 １８例胰腺癌肿瘤病灶,在ＳＥＴ１ＷＩ上呈低信号者１０例,等信号者６例,高信号者２例;ＦＳＥＴ２ＷＩ上高信号者８例,等信号者６例,低信号者４例;脂肪抑制技术ＳＥＴ１ＷＩ上     

Comparison of two superparamagnetic viral-sized iron oxide particles ferumoxides and ferumoxtran-10 with a gadolinium chelate in imaging intracranial tumors

BACKGROUND AND PURPOSE: Ultrasmall superparamagnetic iron oxide particles result in shortening of T1 and T2 relaxation time constants and can be used as MR contrast agents. We tested four hypotheses by evaluating MR images of intracranial tumors after infusion of two iron oxide agents in comparison with a gadolinium chelate: 1) Ferumoxtran in contrast to ferumoxides can be used as an intravenous MR contrast agent in intracranial tumors; 2) ferumoxtran enhancement, albeit delayed, is similar to gadolinium enhancement; 3) ferumoxtran-enhanced MR images in contrast to gadolinium-enhanced MR images may be compared with histologic specimens showing the cellular location of iron oxide particles; 4) ferumoxtran can serve as a model for viral vector delivery. METHODS: In 20 patients, ferumoxides and ferumoxtran were intravenously administered at recommended clinical doses. MR imaging was performed 30 minutes and 4 hours after ferumoxides infusion (n = 3), whereas ferumoxtran-enhanced MR imaging (n = 17) was performed 6 and 24 hours after infusion in the first five patients and 24 hours after infusion in the remaining 12. MR sequences were spin-echo (SE) T1-weighted, fast SE T2- and proton density-weighted, gradient-recalled-echo T2*-weighted, and, in four cases, echo-planar T2-weighted sequences. Representative regions of interest were chosen on pre- and postcontrast images to compare each sequence and signal intensity. RESULTS: Despite some degree of gadolinium enhancement in all tumors, no significant T1 or T2 signal intensity changes were seen after ferumoxides administration at either examination time. Fifteen of 17 patients given ferumoxtrans had T1 and/or T2 shortening consistent with iron penetration into tumor. Histologic examination revealed minimal iron staining of the tumor with strong staining at the periphery of the tumors. CONCLUSION: 1) Ferumoxtran can be used as an intravenous MR contrast agent in intracranial tumors, mostly malignant tumors. 2) Enhancement with ferumoxtran is comparable to but more variable than that with the gadolinium chelate. 3) Histologic examination showed a distribution of ferumoxtran particles similar to that on MR images, but at histology the cellular uptake was primarily by parenchymal cells at the tumor margin. 4) Ferumoxtran may be used as a model for viral vector delivery in malignant brain tumors.     

Use of half-dose gadolinium-enhanced MRI and magnetization transfer saturation in brain tumors

The aim of this study was to search if half-dose gadolinium (Gd)-enhanced MR imaging with magnetization transfer saturation (MT) can replace standard-dose T1-weighted spin echo (SE) without MT saturation in brain tumors. Thirty patients with a total of 33 brain tumors (14 gliomas, 13 meningiomas, 6 metastases) were prospectively studied using T1-weighted SE half-dose of Gd with MT, and T1-weighted SE standard-dose Gd without MT. The contrast-to-noise ratio (CNR) of the two sequences was calculated and four radiologists reviewed qualitatively the images of the two sequences. There was no significant difference between both techniques for quantitative analysis (Wilcoxon test). However, there was a good agreement between sequences to evidence an intraclass correlation coefficient (r = 0.70) of all lesions. In cases of meningioma, the agreement was better (r = 0.84). The results show a difference in the qualitative data between the two sequences, suggesting the use of the T1-weighted MR images with MT and half-dose of Gd with good results in the whole tested parameters except the lesional edema and the presence of artifacts. Half-dose T1-weighted SE with MT can replace standard-dose T1-weighted SE without MT with no loss of contrast enhancement in investigation of meningiomas and saving 50% of the contrast material.     

脑肿瘤磁化传递成像和钆剂增强协同作用的研究

目的：研究钆剂（磁显葡胺）和磁化传递（ＭＴ）成像对脑肿瘤增强效果的协同作用。材料和方法：对６０例脑肿瘤行ＳＥＴ１Ｗ和ＰＤＷ，Ｔ２ＷＭＲＩ检查后，继以行钆剂增强后ＳＥＴ１Ｗ和ＭＴＩＳＥＴ１ＷＭＲＩ。然后测定各种脑肿瘤钆剂和ＭＴＩ合用的增强效价。结果：ＭＴＩ能降低脑实质（背景）信号强度，而对肿瘤病灶的信号强度无甚影响，所以钆剂和ＭＴＩ合用的增强效果为不用ＭＴＩ者的２．２４～８倍。能使脑肿瘤病灶增强范围和突出程度有所增加，并显示更多的病灶。ＭＴＩ和半量（０．０５ｍｍｏｌ／ｋｇ）钆剂合用其增强效果相当于双倍剂量钆剂者。结论：ＭＴＩ和钆剂增强对脑肿瘤具有协同增强效果，故可用作脑肿瘤增强ＭＲＩ检查的常规方法。     

Vergleich des Kontrastverhaltens von Gadobenat-Dimeglumine und Gd-DTPA bei intraaxialen Hirntumoren Eine doppelblinde randomisierte intraindividuelle Cross-over-Studie

The purposes of the study was to assess intraaxial brain tumors by a blinded comparison of gadobenat-dimeglumine and Gd-DTPA. 27 patients with known cerebral gliomas or metastases were included into an intra-individual randomized double-blinded cross-over study. The protocol included T1 SE, T2 FSE and after contrast a series of five T1 SE sequences followed by T1 SE with MT, T1 SE, and 3D GRE sequences. Imaging data acquired at two centers were assessed on-site by the investigators and off-site by two experienced readers using quantitative and qualitative criteria. For a quantitative analysis tumor contrast and contrast-to-noise ratios were determined out of ROI in tumor, unaffected white matter, a region outside the head, and an external reference tube. For the qualitative assessment on- and off-site readers were asked to compare both MR scans for lesion contrast, lesion delineation and information upon the internal morphology and structure. In the quantitative analysis lesions examined with gadobenat-dimeglumine present a maximal 26% increase of the lesion contrast. In both, the on-site, as well as the off-site assessment the intensity of enhancement and the lesion contrast were found to be significantly better with gadobenat-dimeglumine enhanced MRI. There was a trend towards gadobenat-dimeglumine for the delineation of the lesion from the surrounding tissue and the internal lesion morphology. Based on our observations gadobenat-dimeglumine proved to be a safe and valuable contrast media for the assessment of CNS neoplasms. Compared with Gd-DTPA it provides a more intense contrast enhancement and a better tumor contrast which might be of importance for the further management of these patients.     

Delineation of gliomas with magnetic resonance imaging using Gd-DTPA in comparison with computed tomography and positron emission tomography

Fourteen patients with cerebral gliomas were investigated by MR imaging using Gd-DTPA (Magnevist), CT with the contrast agent iohexol (Omnipaque) and, as a reference, positron emission tomography (PET) using 11C-L-methionine. Tumour areas with disruption of the blood-brain-barrier (BBB) as seen on MR and CT were compared with areas increased accumulation of methionine in PET. There were 6 patients with high-grade astrocytoma (grade III-IV), 5 with low-grade astrocytoma (grade I-II) and 3 with oligodendroglioma. In 4 high-grade tumours, PET showed a larger tumour or tumour tissue in additional areas, compared with enhancement on MR and CT, while in 2 cases the tumour extension was similar in the three modalities. In the low grade tumour group, the findings on PET differed from those on post-contrast MR or CT in 7 cases. In 3 of these cases, no disruption of the BBB was seen either on MR or on CT. In 2 of our 14 patients CT showed larger enhancement extension than MR and in 2 cases MR was superior to CT in this respect. The enhancement intensity was higher on MR in 4 patients and on CT in 2 patients. No definite difference in the delineation of tumour tissue between the T1 weighted SE sequences was found. The gradient echo sequences FLASH and FISP gave limited information that was less than that provided by the T1 weighted SE sequences. A greater increase in signal intensity in T1 weighted images was usually seen 5 min post-contrast in the high-grade tumours than in the low-grade ones.     

Contrast enhancement of brain tumors at different MR field strengths: comparison of 0.5 T and 2.0 T.

PURPOSETo compare the degree of MR contrast enhancement of 0.5 T and 2.0 T in various brain tumors.METHODSMR images were studied prospectively in each of 31 patients with brain tumors (11 gliomas, 6 meningiomas, 6 neurinomas, and 8 others) before and after intravenous injection of gadopentetate dimeglumine. In every patient, both 0.5-T and 2.0-T MR studies were done within 1 week. Each patient received an initial standard dose (0.1 mmol/kg) of gadopentetate dimeglumine, followed by a subsequent 0.1-mmol/kg dose (total, double dose) in MR of each field strength. MR was done before and after each injection of the contrast agent. Degree of contrast enhancement in the lesions was assessed both visually and quantitatively.RESULTSWith standard-dose study, the tumor enhancement was visually stronger at 2.0 T than at 0.5 T in 9 gliomas. In extraaxial tumors there was visually no or minimal difference between 0.5 T and 2.0 T. Overall mean contrast-enhancement ratio and tumor and brain contrast-to-noise ratio were higher at 2.0 T than at 0.5 T by 53% and 108%, respectively. The double-dose study showed higher contrast-enhancement ratio and contrast-to-noise ratio than the standard-dose study at both field strengths, and the differences between 0.5 T and 2.0 T were almost similar to those of the standard-dose study. The degree of contrast enhancement with the standard dose at 2.0 T was comparable to that of the double dose at 0.5 T in most intraaxial tumors.CONCLUSIONThe results suggest that effect of contrast enhancement increases with the field strength. Therefore, reevaluation of optimal doses of contrast media may be needed in a variety of brain lesions at each field strength.     

Kontrastmittelunterstützte MR „Magnetization-transfer-Technik”

Aims

To improve tumor conspicuity and delineation on contrast-enhanced T1-weighted MR images with and without magnetization transfer (MT) contrast as a strategy to improve the macroscopic boost volume definition in the planning process of radiosurgery in patients with high grade gliomas or metastatic brain lesions.

Patients and Methods

Thirty-two patients (mean age 47 years) with histologically proven or suspected high grade glioma (n=12) or metastatic brain lesions (n=20) were prospectively examined by MR imaging. After the administration of gadolinium dimeglumine (0.1 mmol/kg body weight) the lesions were imaged with a T1-weighted MT-fast low angle shot (FLASH) pulse sequence and with a conventional T1-weighted SE sequence without MT saturation.

Results

The mean CNR of enhancing lesions on T1-weighted MT-FLASH was 15±5 compared to 14±4 on SE images, representing a significant (p<.01) improvement. The mean tumor diameter of malignant gliomas was significantly (p<.01) larger measured on T1-weighted MT-FLASH images compared to those obtained from T1-weighted SE images and were comparable for metastatic lesions. Lesion conspicuity and delineation were improved in 50% of patients with high grade gliomas and in 35% of patients with brain metastases. Lesion conspicuity was markedly improved in the posterior fossa. Additional contrast enhancing lesions were detected in 10% of patients with metastases on MT-FLASH images.

Conclusions

It is concluded that contrast-enhanced MT-FLASH images may improve lesion detection and delineation in the planning process of radiosurgery in patients with intracranial high grade gliomas or metastases or even alter the treatment approach.     

The contribution of gadolinium to the magnetic resonance diagnosis of spondylodiscitis]

To determine the contribution of Gd-DTPA to the evaluation of vertebral infections 16 MR examinations with i.v. Gd-DTPA injection were performed on 12 patients with diagnosis of spondylodiscitis. All patients were examined with both SE T1- and SE T2-weighted sequences. The SE T1-weighted sequence was repeated following i.v. Gd-DTPA injection (0.1 nmol/kg). Signal intensities and visibility of the lesions were evaluated with MR. For each lesion the grade of visibility on SE T1-weighted sequence was compared with the grade of visibility on SE T2-weighted sequence. Moreover, for each study the information obtained by the combined evaluation of SE T1-weighted sequence without and with Gd-DTPA was compared with the information obtained by combined SE T1- and SE T2-weighted sequences. Gd-DTPA was useful in the evaluation of lesions of the discal space, showing in all cases an area of low signal intensity with peripheral enhancement; this finding allowed, in some cases, to differentiate mild spondylodiscitis from degenerative features. Gd-DTPA was also very useful in determining the extent of the disease: in comparison with MR study without contrast media, the combined evaluation of SE T1-weighted sequence without and with Gd-DTPA better showed the extent of the disease in 7/8 cases (88%).     

增强FLAIR T2WI诊断脑膜转移瘤的价值

目的:探讨脑膜转移瘤的MRI表现及增强后FLAIR序列T2WI的诊断价值。方法:回顾性分析20例脑膜转移瘤患者的病例资料,其中硬脑膜转移瘤5例,软脑膜转移瘤15例。所有病例行常规MRI平扫及SE T1WI和FLAIR序列T2WI增强扫描并进行对比分析。结果:MRI平扫检出6例,病灶边界均显示不清;MRI增强扫描检出所有病例,SE-T1WI上病变主要表现为脑膜的线状和/或结节状强化,FLAIR T2WI对软脑膜转移瘤病灶范围的显示更清楚,可鉴别强化的血管与病变。结论:MRI增强扫描是诊断脑膜转移瘤的重要检查方法,增强后FLAIR序列T2WI与SE T1WI同时使用,可提高对软脑膜转移瘤的检出率及诊断准确性。     

The pseudocapsule in hepatocellular carcinoma: correlation between dynamic MR imaging and pathology

Nodular hepatocellular carcinoma (HCC) is characterized by the presence of a pseudocapsule (constructed usually from connective fibrous tissue) that appears hypointense on T1- and T2-weighted spin-echo (SE) and gradient-echo (GE) MR imaging sequences without a contrast medium. The presence of vascular structures inside the tumor, which are verified by histological exam, affects enhancement of the PC after administrating the contrast medium: The impregnation is more evident in the dynamic study but also persists on the delayed T1-weighted SE images. The accuracy of MR in detecting the pseudocapsule of HCC and contrast enhancement of the pseudocapsule during dynamic studies were evaluated and related to pathological findings. Thirty-seven HCC were examined in 33 patients and afterwards resected. In capsulated nodules, besides usual hematoxylin, eosin, and trichrome stainings, histochemical and immunohistochemical methods were performed. On a 1.5-T MR unit, T1- and T2-weighted SE and GE FLASH 2D sequences after intravenous injection of Gd-DTPA (dynamic study) were used. In a later phase, T1-weighted SE sequences were repeated. Histologically, the pseudocapsule (thickness 0.2–6 mm) was present in 26 of 37 nodules (70 %). The dynamic study was the most suitable technique to show the pseudocapsule, which was recognized in 80.7 % (21 of 26 nodules). In 5 of 26 cases, the pseudocapsule, not demonstrated by MR, was thinner than 0.4 mm. In 16 of 21 cases, in the early portal phase (30–60 s), the pseudocapsule had an early enhancement, which was more evident later; in 5 of 21 cases the enhancement was observed only in the late portal phase (1–2 min). At histological examination, 14 of 16 pseudocapsules with early enhancement showed a more prominent vasculature than those with enhancement in the equilibrium phase. Magnetic resonance was a reliable tool in demonstrating the pseudocapsule of HCC. The histological examination demonstrated a good correlation between the enhancement behavior and the vessel number of the pseudocapsule. Received: 28 July 1997; Revision received: 9 February 1998; Accepted: 20 March 1998     

颅内胶质瘤术后脑组织正常反应与肿瘤残存的MR影像学分析

目的 分析颅内胶质瘤术后脑组织反应性增强与肿瘤残存增强的影像学特点。方法回顾性分析２０４例胶质瘤术后的ＭＲＩ表现,其中男１４１例,女６３例,年龄１２－６８岁,平均３９．１岁。所有病例均在术前进行ＭＲＩ检查,并在术后１个月内至少行１次ＭＲＩ平扫及增强扫描,且均追踪至办化灶形成或肿瘤复发。使用Ｗｉｎｄｏｗｓ７．５版社会科学统计软件包（ｓｔａｔｉｓｔｉｃｓ ｐａｃｋａｇｅ ｆｏｒ ｓｏｃｉａｌ ｓｃｉｅ     

Pulse sequence optimization for MR imaging using a paramagnetic hepatobiliary contrast agent

Paramagnetic agents enhance contrast between tissues in magnetic resonance (MR) imaging by altering tissue relaxation times. The effect of these changes on MR image intensity depends in part on the choice of operator-controlled pulse sequence parameters. With the newly described paramagnetic hepatobiliary contrast agent, iron(III) ethylenebis-(2-hydroxyphenylglycine), Fe(EHPG)-, an in vivo experimental analysis of pulse sequence optimization was performed on the rat. We compared the enhancement of the liver divided by background noise, EL/N, of standard inversion-recovery (IR) and spin-echo (SE) T1-weighted pulse sequences and several pulse sequences theoretically predicted to have improved EL/N. Optimization of the echo time (TE = TEmin) gave a substantial (greater than 60%) increase in EL/N over the standard IR and SE pulse sequences. Images obtained with optimized repetition rate and inversion time gave only a slight additional improvement. Within the uncertainties of our relaxation measurements, the measured changes in EL/N with pulse sequence optimization corresponded well with theoretical predictions. With the experimental and theoretical data, the importance of using a short echo time to obtain maximal T1 contrast in contrast-enhanced MR imaging and the relative merits of optimized SE versus IR pulse sequences for contrast-enhanced MR imaging are discussed.     

颞叶癫痫的MRI研究

目的：探讨颞叶癫痫的ＭＲＩ 表现及其诊断价值。材料和方法：对临床诊断为颞叶癫痫４３ 例患者,行自旋回波横断面、冠状面和矢状面ＭＲＩ 研究。结果：４３ 例中,３５ 例颞叶发现有异常ＭＲ 信号,并经手术病理证实。８ 例颞叶无异常发现。术前ＭＲＩ 定位诊断正确率为１００ ％ ,定性诊断正确率为８２ ．９ ％ 。３５ 例中,９ 例胶质细胞增生,Ｔ１ ＷＩ上无明显信号异常,Ｔ２ 加权图像上呈无占位效应的高信号;１５ 例胶质瘤, 表现为病灶呈长Ｔ１ 长Ｔ２ 信号, 并伴有不同程度的占位效应,灶周水肿不明显;７ 例胆脂瘤,表现为Ｔ１ ＷＩ 上呈高于脑脊液的低信号,Ｔ２ ＷＩ 上均呈高于脑脊液的高信号;４ 例海绵状血管瘤,Ｔ１ ＷＩ 上呈等高混合信号,Ｔ２ ＷＩ 上呈明显高信号,周边有低信号环与脑实质相隔。结论：ＭＲＩ 对确定颞叶癫痫病灶的部位和病因具有重要价值。     

Diffusion-weighted MR imaging of intracerebral masses: comparison with conventional MR imaging and histologic findings

BACKGROUND AND PURPOSE: The purposes of this study were to find the role of diffusion-weighted MR imaging in characterizing intracerebral masses and to find a correlation, if any, between the different parameters of diffusion-weighted imaging and histologic analysis of tumors. The usefulness of diffusion-weighted imaging and apparent diffusion coefficient (ADC) maps in tumor delineation was evaluated. Contrast with white matter and ADC values for tumor components with available histology were also evaluated. METHODS: Twenty patients with clinical and routine MR imaging/CT evidence of intracerebral neoplasm were examined with routine MR imaging and echo-planar diffusion-weighted imaging. The routine MR imaging included at least the axial T2-weighted fast spin-echo and axial T1-weighted spin-echo sequences before and after contrast enhancement. The diffusion-weighted imaging included an echo-planar spin-echo sequence with three b values (0, 300, and 1200 s/mm(2)), sensitizing gradient in the z direction, and calculated ADC maps. The visual comparison of routine MR images with diffusion-weighted images for tumor delineation was performed as was the statistical analysis of quantitative diffusion-weighted imaging parameters with histologic evaluation. RESULTS: For tumors, the diffusion-weighted images and ADC maps of gliomas were less useful than the T2-weighted spin-echo and contrast-enhanced T1-weighted spin-echo images in definition of tumor boundaries. Additionally, in six cases of gliomas, neither T2-weighted spin-echo nor diffusion-weighted images were able to show a boundary between tumor and edema, which was present on contrast-enhanced T1-weighted and/or perfusion echo-planar images. The ADC values of solid gliomas, metastases, and meningioma were in the same range. In two cases of lymphomas, there was a good contrast with white matter, with strongly reduced ADC values. For infection, the highest contrast on diffusion-weighted images and lowest ADC values were observed in association with inflammatory granuloma and abscess. CONCLUSION: Contrary to the findings of previous studies, we found no clear advantage of diffusion-weighted echo-planar imaging in the evaluation of tumor extension. The contrast between gliomas, metastases, meningioma, and white matter was generally lower on diffusion-weighted images and ADC maps compared with conventional MR imaging. Unlike gliomas, the two cases of lymphomas showed hyperintense signal on diffusion-weighted images whereas the case of cerebral abscess showed the highest contrast on diffusion-weighted images with very low ADC values. Further study is required to find out whether this may be useful in the differentiation of gliomas and metastasis from lymphoma and abscess.     

磁共振灌注成像在急性心肌梗死诊断中的价值

目的研究磁共振灌注成像在急性心肌梗死诊断中的价值。方法使用1.5T超导型磁共振扫描仪,对29例经临床诊断的急性心肌梗死病人行灌注成像,其中17例进行冠状动脉造影术,全部病例通过AW4.0工作站处理,计算出首过时间及首过最大上升斜率,同时测定正常心肌与心室腔的首过时间及最大上升斜率。对比剂总量20ml,注射流率首过3ml/s,共9ml,以后以1ml/s注射。结果29例心肌梗死病例显示延迟病灶明显强化及首过最大上升斜率降低,28例首过时间延迟,17例行冠状动脉造影,14例发现冠状动脉狭窄,未发现冠状动脉狭窄的3例,均为心内膜下或心外膜下梗死。结论急性心肌梗死MR灌注成像具有特征性表现。     

抑脂技术和动态增强MRI在胰岛素瘤诊断中的价值探讨

目的 探讨抑脂技术和动态增强MRI在胰岛素瘤术前定位诊断中的价值。方法 12例手术病理证实的胰岛素瘤患者术前行MR检查，扫描序列包括：横断面SE T1WI，快速自旋回波(FSE)T2WI，加脂肪抑制技术的T1WI和T2WI(即T1WI FS和T2WI FS)，快速多层面扰相梯度回波(FMPSPGR)序列作动态增强扫描。结果 在常规T1WI和T2WI序列仅检出4例肿瘤，表现为T1WI稍低信号和T2WI稍高信号。在T1WI FS上7例呈均匀低信号，显示清晰；在T2WI FS上6例病灶呈不同程度的高信号。快速动态增强扫描(FMPSPGR)检出11例肿瘤，在动脉期7例肿瘤明显强化呈高信号，4例轻度强化呈稍高信号，1例无明显强化呈等信号，胰腺实质期和门脉期6例仍呈高信号，6例呈等信号。与手术后病理结果比较，动态增强MRI对胰岛素瘤术前定位诊断准确率为91．7％(11／12)。结论 动态增强MRI是胰岛素瘤术前定位诊断敏感而准确的方法。     

Ferrite-enhanced MR imaging of hepatic lymphoma: an experimental study in rats

The purpose of this investigation was to define the potential of unenhanced and ferrite-enhanced MR to detect hepatic lymphoma. Rats were implanted with diffuse and focal hepatic lymphoma. Both in vitro measurements of relaxation times and in vivo MR imaging of normal liver and of diffuse and focal hepatic lymphoma were compared. Diffuse infiltrative hepatic lymphoma showed increased T1 (45%) and T2 (41%) relaxation times in vitro, but could not be distinguished from normal control livers on in vivo spin echo (SE) images with a repetition time of 500 msec and an echo time of 30 msec (SE 500/30) or SE 1500/60 images. Focal hepatic lymphoma showed increased T1 (185%) and T2 (115%) relaxation times relative to normal liver tissue. Focal hepatic lymphoma was undetectable on unenhanced SE 500/30 MR images (contrast-to-noise ratio, C/N = 0.4) and was slightly hyperintense on SE 1500/60 images (C/N = 1.1). Ferrite (50 mumol Fe/kg) was administered to improve tissue contrast. In normal control animals, T2 of liver in vitro decreased from 29.3 +/- 3.3 msec to 11.1 +/- 1.2 msec, and image signal-to-noise ratio (S/N) of liver in vivo decreased from 16.1 +/- 2.4 to 2.8 +/- 0.3 (p less than .005). Ferrite-enhanced diffuse hepatic lymphoma showed in vitro T2 values and in vivo MR image S/N values indistinguishable from those of normal control animals. The T2 of focal hepatic lymphoma was essentially unaltered by ferrite. On SE 500/30 images, focal hepatic lymphoma became readily detectable, quantitated by a 35-fold increase in tumor-liver C/N. We conclude that clinical studies are warranted to determine the value of ferrite enhanced MR as a technique for the enhanced detection of focal hepatic lymphoma.     

神经纤维瘤病I型的MRI研究

目的：回顾神经纤维瘤病I型（NF1）患者MRI表现，分析MR扫描序列及其诊断价值，以建立合适的MR成像方案，为NF1影像诊断提供有价值的依据。方法：对30例临床确诊为NF1患者采用本组MR成像方案进行扫描，主要包括：轴面SE序列T2WI；平扫矢状面SE脉冲序列T1WI；增强轴面或矢状面SE脉冲序列T1WI；轴面或冠状面液体衰减反转恢复（FLAIR）序列，同时分析病变的发病部位、数目、形态、信号的变化和病变的强化情况等。结果：MRI可见下列3种表现：（1）多发性脑内错构瘤：30例中25例在SE脉冲序列T2WI和FlAIR脉冲序列见高信号病灶，病灶主要位于苍白球、小脑和脑干。另外，25例中20例可见海马回、海马旁回等区晕状高信号改变。（2）视通道或下丘脑胶质瘤：视神经、视交叉增粗、扭曲；视交叉或下丘脑肿块，SE脉冲序列T2WI和FlAIR序列表现为不规则分叶状混杂信号肿块，在增强SE脉冲序列T1WI有明显不规则强化。（3）脊柱多发性神经纤维瘤：SE脉冲序列T2WI和脂肪抑制短时反转恢复（STIR）序列显示高信号沿脊神经分布的多发性肿瘤。结论：MRI能够作为1种 常规的影像检查方法对NF1患者进行诊断和追踪。本组MR成像方案能较好地显示NF1的多发性或多灶性病变。     

软组织恶性纤维组织细胞瘤的临床影像学诊断

目的:回顾性分析26例恶性纤维组织细胞瘤(MFH)的临床影像学表现,讨论其影像学诊断。方法:搜集经手术病理及免疫组化证实的MFH 26例,男15例,女11例,40岁21例,占80.77%。病史3个月~5年。7例摄有X线平片。CT平扫17例,增强扫描8例。MR平扫15例,增强扫描8例。病灶大多位于大腿、小腿、前臂和臀部。23例位于深部软组织,3例位于表浅软组织。结果:21例(80.77%)呈不规则长圆形或长条形软组织肿块,直径5cm。3例X线平片表现为软组织肿块伴邻近骨质侵蚀性破坏,2例伴有骨膜增生。CT平扫多呈等、低或略低密度,仅1例高密度。CT增强均表现为明显不均匀强化,病灶边界均不清,累及邻近肌肉。CT上2个病灶内可见弧形钙化,其病灶直径均5.0cm。13例可见邻近骨骼破坏或骨膜增生。MR平扫15例,T1WI多呈等或低信号,合并出血4例。T2WI多呈高信号或混杂信号,10例病灶周围可见片状水肿信号。MR增强扫描8例,均呈明显不均匀强化,2例边界清楚,邻近肌肉受压推移,12例边界不清,邻近肌肉侵犯。6例可见邻近骨骼受侵。结论:发生于中老年人,位于下肢、前臂深部软组织的巨大肿块,尤其是呈长圆形分叶状或不规则长条状软组织肿块,边界不清,伴有邻近骨质破坏或骨膜反应,增强扫描呈明显不均匀强化者,应首先考虑恶性纤维组织细胞瘤。