Gadolinium enhancement of the cerebrospinal fluid in a patient with meningeal fibrosis and cryptococcal infection

We describe the case of a 52-year-old man, with cryptococcal meningitis and meningeal fibrosis who had undergone ventricular shunting. Gd-DTPA-enhanced T1-weighted MRI revealed diffuse meningeal enhancement. Remarkably, there was enhancement of the pia mater and posterior fossa subarachnoid space. Received: 27 February 1996 Accepted: 4 July 1996     

心脏磁共振延迟强化对尿毒症心肌病的应用初探

目的分析尿毒症患者心脏磁共振(CMR)心肌延迟强化的特征,探讨MRI增强检查对尿毒症心肌病的意义和价值。资料与方法 40例尿毒症患者、10例心肌梗死患者及5例肥厚性心肌病患者分别接受CMR增强检查,分析不同患者延迟强化心肌的特点。结果 CMR延迟增强检查,尿毒症与肥厚性心肌病组与心肌梗死组的延迟强化心肌平均信号强度指数、最大层面延迟强化心肌面积有明显差异(P<0.001)。结论 CMR延迟增强检查尿毒症患者异常强化心肌特点:延迟强化心肌分布在左心室室壁中部,呈局灶性小斑片状,且轻度强化改变,这与肥厚性心肌病有所类似。     

Magnetic resonance angiography of supratentorial tumours: comparison with selective digital subtraction angiography

We compared magnetic resonance angiography (MRA) and intra-arterial digital subtraction angiography (IADSA) in the study of brain tumours and assessed the utility of gadolinium-enhanced MRA. We studied 17 patients with supratentorial brain tumors. The entire brain was imaged with multiple overlapping thin volume acquisitions. After IV injection of gadolinium-DTPA, a single thick-slab MRA acquisition was performed. Standard three-dimensional (3D-TOF) acquisitions (in six patients) and 3D-TOF with magnetization transfer prepulse and tilted optimisation nonsaturing radiofrequency excitation pulses (in 11 patients) were used. Displacement of the anterior cerebral artery, main stem and insular branches of the middle cerebral artery was seen well on unenhanced and contrast-enhanced MRA. Displacement of the lenticulostriate and anterior choroidal arteries was seen only once, after Gadolinium. Tumour encasement of the middle cerebral artery was demonstrated in one patient. Tumour vessels were seen in 2 of 8 cases before and 3 of 8 after gadolinium; Tumour hypervascularity was seen only after gadolinium, in 3 of 8 cases. Study of the veins was possible only on gadolinium-enhanced MRA. Displacement of the venous angle was seen in 4 of 7 patients in the frontal, and in all of 8 patients on the lateral projections. Early venous drainage was not seen. Patency of the dural venous sinuses was demonstrated in all patients, but in one neoplastic occlusion of a cortical vein was recognised.     

Effects of ami-25 on liver vessels and tumors on T1-weighted turbo-field-echo images: Implications for tumor characterization

This study was devoted to tumor differentiation in liver MR T1-weighted imaging with superparamagnetic iron oxide (SPIO). Twenty-one patients with 40 liver lesions were studied at 1.5 T. Before and at least 45 minutes after SPIO administration, turbo-field-echo (TFE) T1-weighted, TFE T1 × T2*-weighted (MXT), and fat-suppressed turbo-spin-echo T2-weighted images were acquired. A quantitative analysis was performed blindly. On TFE T1-weighted images, the signal enhancement was ?33% ± 12 for the liver, ?24% ± 2 for adenomas and focal nodular hyperplasia, +60% ± 33 for the hemangiomas; metastases and cyst enhancement were not significant. After SPIO on TFE T1-weighted images, the hemangioma-to-liver signal ratio (149% ± 18) was definitely higher than the mean metastasis-to-liver signal ratio (90% ± 16). This T1-related differentiation ability lacked dramatically on TFE MXT images and, in one case, was reduced on post-SPIO TFE T1-weighted images by a long imaging delay after SPIO administration (2 hours).     

MR动态增强特征对乳腺癌诊断的价值

目的探讨乳腺癌动态增强扫描相关参数在乳腺癌诊断中的价值。方法对93例患者行MR平扫、动态增强扫描。分析形态学、增强曲线类型及最大斜率对乳腺癌的诊断价值。结果 (1)形态学表现及病理结果:105个肿块的强化形式可分为五型:①无强化9个(囊肿);②均匀强化31个(纤维腺瘤9个,乳腺癌11个,增生10个,叶状瘤1个);③不均匀强化42个(纤维腺瘤5个,增生3个,乳腺癌33个,叶状瘤1个);④边缘强化17个(乳腺癌15个,纤维腺瘤及炎症各1个);⑤网状强化2例(乳腺炎,巨乳症各1例)。⑥导管状强化4个(增生1个,导管癌3个)。(2)曲线类型及病理结果:I型曲线20个,II型曲线42个,III曲线型43个。六种表现形式①曲线信号强度基本无增加9个(囊肿);②曲线信号强度缓慢持续增加6个(增生2个,纤维腺瘤2个,慢性炎症1个,导管内癌1个);③曲线号强度早期迅速增加后仍持续缓慢增加5个(增生4个,炎性乳腺癌1个);④曲线早期信号强度迅速增加之后基本停止而形成中晚期的平台42个(增生9个,纤维腺瘤8个,叶状瘤1个,乳腺癌24个);⑤曲线早期信号强度迅速增加到达峰值,之后信号强度逐渐下降40个(增生1个,纤维腺瘤5个,叶状瘤1个,乳腺癌33个);⑥曲线早期信号强度迅速增加到达峰值,呈平台期后又迅速上升3个(均为乳腺癌)。(3)增强斜率及病理结果:62个恶性病灶的平均最大斜率为19.19±8.13,43个良性病灶平均最大斜率为9.46±6.64,二者差异有非常显著性意义(P<0.01)。以14.85为临界值,敏感性为67%,特异性为83%;以17.10为临界值,特异性为100%。结论增强形态学特征、最大斜率在良、恶性病变,尤其是II型曲线的鉴别诊断中具有重要价值。     

Gadodiamide injection at 0.1 and 0.3 mmol/kg body weight: a phase III double-blind,parallel, randomised clinical investigation of known or suspected cenctral nervous system lesions at 1.5 T

We studied 78 patients with clinically suspected central nervous system abnormalities (66 intracranial, 12 spinal) by MRI before and after adminis-tration of the nonionic contrast medium gadodiamide injection. A parallel, double-blind, randomised design was followed. Two dosages were used: 38 patients underwent studies with 0.1 mmol/kg body weight (b.w.) and 40 with 0.3 mmol/kg b. w. MRI showed abnormalities in 36 of the 38 patients receiving the lower dose and 39 of the 40 patients receiving the higher dose. In 3 patients from each group more lesions were seen following injection than before. The contrast medium improved the delineation of abnormal structures and assessment of tumour size and increased their signal intensity indices in both groups, but especially at the higher dose. Adminis-tration of gadodiamide injection provided more diagnostic information in about 75% of the patients, independently of the dose. There were no reports of discomfort, but 7 patients reported adverse events considered unrelated to the gadodiamide injection. The two doses were found to be equally safe and efficient for diagnosis.     

MR imaging of the liver: Effect of portal hypertension on hepatic parenchymal enhancement using a gadolinium chelate

The purpose of this study was to prospectively investigate the extent to which reduced portal blood flow in patients with hepatic cirrhosis and portal hypertension affects hepatic parenchymal enhancement during gadolinium-chelate-enhanced dynamic MR imaging. Breath-hold three-dimensional (3D) spoiled gradientrecalled echo (GRE) MR imaging technique obtained after intravenous administration of a gadolinium chelate was used to measure hepatic parenchymal enhancement and time to peak enhancement in 20 patients with hepatic cirrhosis and clinical evidence of portal hypertension (group 1) and in 20 control subjects without portal hypertension (group 2) who were matched for age, sex, and body weight. Mean peak hepatic enhancement values ± SD and times to peak enhancement ± SD were determined for both groups of patients. Mean peak enhancement value (±SD) was 78.7% ± 36.2 in group 1 and 91.6% ± 46.2 in group 2 (not significant). However, in the nine patients in group 1 with splenomegaly, mean peak enhancement value was 61.3% ± 14.4, whereas it was 93.0% ± 42.7 in the 11 patients without splenomegaly (P < .05). Mean time to peak enhancement was 84 seconds ± 23 in group 1 and 54.0 sec ± 25.0 in group 2 (P < .01). Our results show that mean peak enhancement value of hepatic parenchyma after intravenous administration of a gadolinium chelate is significantly altered for patients with portal hypertension and splenomegaly. In addition, the time to peak enhancement is delayed significantly when portal hypertension is present. Thus, it is possible that the optimal time for imaging the liver during the portal phase must be tailored to the status of the portal system of the patient.     

Gadolinium Deposition in the Brain: A Systematic Review of Existing Guidelines and Policy Statement Issued by the Canadian Association of Radiologists

Emerging evidence has confirmed that, following administration of a gadolinium-based contrast agent (GBCA), very small amounts of gadolinium will deposit in the brain of humans with intact blood-brain barriers. The literature is evolving rapidly and the degree to which gadolinium will deposit for a particular GBCA or class of GBCAs remains undetermined. Several studies suggest that linear GBCAs deposit more gadolinium in the brain compared with macrocyclic GBCAs; however, our understanding of the molecular composition of deposited gadolinium is preliminary, and the clinical significance of gadolinium deposition remains unknown. To date, there is no conclusive evidence linking gadolinium deposition in the brain with any adverse patient outcome. A panel of radiologists representing the Canadian Association of Radiologists was assembled to assist the Canadian medical imaging community in making informed decisions regarding the issue of gadolinium deposition in the brain. The objectives of the working group were: 1) to review the evidence from animal and human studies; 2) to systematically review existing guidelines and position statements issued by other organizations and health agencies; and 3) to formulate an evidence-based position statement on behalf of the Canadian Association of Radiologists. Based on our appraisal of the evidence and systematic review of 9 guidelines issued by other organizations, the working group established the following consensus statement. GBCA administration should be considered carefully with respect to potential risks and benefits, and only used when required. Standard dosing should be used and repeat administrations should be avoided unless necessary. Gadolinium deposition is one of several issues to consider when prescribing a particular GBCA. Currently there is insufficient evidence to recommend one class of GBCA over another. The panel considered it inappropriate to withhold a linear GBCA if a macrocyclic agent is unavailable, if hepatobiliary phase imaging is required, or if there is a history of severe allergic reaction to a macrocyclic GBCA. Further study in this area is required, and the evidence should be monitored regularly with policy statements updated accordingly.     

Contrast enhancement of the cerebrospinal fluid on MRI in two cases of spirochaetal meningitis

We report two patients with meningitis due to spirochaetal infection, both of whom showed diffusely enhancing meninges around the brain and spinal cord. In addition, there was enhancement of the cerebrospinal fluid after intravenous administration of Gd-DTPA. Received: 1 March 1998/Accepted: 21 August 1999     

Paradoxic uptake of Gd-EOB-DTPA by hepatocellular carcinoma in mice: Quantitative image analysis

To determine whether paradoxic uptake of gadoliniumethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) occurs only with highly differentiated hepatocellular carcinomas, quantitative image analysis was performed in 37 mice with 133 hepatocellular carcinomas. The results of lesion/liver signal intensity measurement and relative enhancement calculation indicate that paradoxic positive enhancement occurs independently of cellular differentiation.     

3He MR imaging of porcine paranasal sinuses

RATIONALE AND OBJECTIVES: The aim of this study was to test the effectiveness of laser-hyperpolarized helium 3 (3He) as a contrast agent for magnetic resonance (MR) imaging of porcine paranasal sinuses. MATERIALS AND METHODS: Imaging experiments were conducted on the heads of four 50-kg Yorkshire pigs after open sinus surgery was performed. Paranasal sinus MR images were obtained with laser-polarized 3He gas produced through the spin-exchange method. The gas was delivered into the sinuses through two 14-gauge plastic catheters inserted in the nostrils. The 3He MR images were then compared with spatially correlated proton MR images. RESULTS: The porcine paranasal sinuses were adequately depicted by MR imaging with hyperpolarized 3He. The signal intensity of the paranasal sinuses on the 3He MR images was related to the size of the opening joining the sinuses to the nasal cavity and was clearly time dependent. CONCLUSION: Hyperpolarized 3He MR imaging may be particularly useful for identifying the anatomic configuration of the paranasal sinuses, as well as for assessing sinus aeration. Further study of the time-dependence of 3He signal intensity may help increase understanding of gas exchange in the sinuses.     

The Optimization of Scan Timing for Contrast-Enhanced Magnetic Resonance Angiography

Objective

To determine the optimal scan timing for contrast-enhanced magnetic resonance angiography and to evaluate a new timing method based on the arteriovenous circulation time.

Materials and Methods

Eighty-nine contrast-enhanced magnetic resonance angiographic examinations were performed mainly in the extremities. A 1.5T scanner with a 3-D turbo-FLASH sequence was used, and during each study, two consecutive arterial phases and one venous phase were acquired. Scan delay time was calculated from the time-intensity curve by the traditional (n = 48) and/or the new (n = 41) method. This latter was based on arteriovenous circulation time rather than peak arterial enhancement time, as used in the traditional method. The numbers of first-phase images showing a properly enhanced arterial phase were compared between the two methods.

Results

Mean scan delay time was 5.4 sec longer with the new method than with the traditional. Properly enhanced first-phase images were found in 65% of cases (31/48) using the traditional timing method, and 95% (39/41) using the new method. When cases in which there was mismatch between the target vessel and the time-intensity curve acquisition site are excluded, erroneous acquisition occurred in seven cases with the traditional method, but in none with the new method.

Conclusion

The calculation of scan delay time on the basis of arteriovenous circulation time provides better timing for arterial phase acquisition than the traditional method.     

动态增强MRI在垂体微腺瘤诊断中的应用研究

目的　探讨动态增强MRI在垂体微腺瘤诊断中的价值。资料与方法　对 6 2例经临床及实验室检查诊断为垂体微腺瘤患者进行MRI平扫、Gd DTPA动态增强扫描及常规延迟增强扫描并分析其MRI信号特征。结果　MRI平扫、动态增强和常规延迟增强扫描微腺瘤检出率分别为 4 6 .8% (2 9/ 6 2 )、88.7% (5 5 / 6 2 )和 6 4 .5 % (4 0 /6 2 )。 3种不同的扫描方法病灶检出率有显著差异 (P <0 .0 1)。结论　MRI动态增强扫描、常规延迟增强扫描提高了病灶的检出率 ,其中以动态增强扫描病灶检出率最高。动态增强扫描可作为MRI诊断垂体微腺瘤的首选强化方法     

Characterization of Focal Liver Lesions with Superparamagnetic Iron Oxide-Enhanced MR Imaging: Value of Distributional Phase T1-Weighted Imaging

Objective

To determine the potential value of distributional-phase T1-weighted ferumoxides-enhanced magnetic resonance (MR) imaging for tissue characterization of focal liver lesions.

Materials and Methods

Ferumoxides-enhanced MR imaging was performed using a 1.5-T system in 46 patients referred for evaluation of known or suspected hepatic malignancies. Seventy-three focal liver lesions (30 hepatocellular carcinomas [HCC], 12 metastases, 15 cysts, 13 hemangiomas, and three cholangiocarcinomas) were evaluated. MR imaging included T1-weighted double-echo gradient-echo (TR/TE: 150/4.2 and 2.1 msec), T2*-weighted gradient-echo (TR/TE: 180/12 msec), and T2-weighted turbo spin-echo MR imaging at 1.5 T before and after intravenous administration of ferumoxides (15 mmol/kg body weight). Postcontrast T1-weighted imaging was performed within eight minutes of infusion of the contrast medium (distributional phase). Both qualitative and quantitative analysis was performed.

Results

During the distributional phase after infusion of ferumoxides, unique enhancement patterns of focal liver lesions were observed for hemangiomas, metastases, and hepatocellular carcinomas. On T1-weighted GRE images obtained during the distributional phase, hemangiomas showed a typical positive enhancement pattern of increased signal; metastases showed ring enhancement; and hepatocellar carcinomas showed slight enhancement. Quantitatively, the signal-to-noise ratio of hemangiomas was much higher than that of other tumors (p < .05) and was similar to that of intrahepatic vessels. This finding permitted more effective differentiation between hemangiomas and other malignant tumors.

Conclusion

T1-weighted double-echo FLASH images obtained soon after the infusion of ferumoxides, show characteristic enhancement patterns and improved the differentiation of focal liver lesions.     

Evolution of VX2 carcinoma in rabbit tibia: magnetic resonance imaging with pathologic correlation

OBJECTIVE: To evaluate the evolution of a metastatic bone tumor model with MRI-pathology correlation. MATERIALS AND METHODS: VX2 carcinoma was implanted into the tibiae of 20 rabbits. The rabbits were divided into four groups of five (Groups I-IV). MRI was repeated at 1-week interval up to the fourth week, including sagittal T1-weighted image (T1WI), T2-weighted image (T2WI), gadolinium-enhanced fat-suppressed T1WI (GdT1WI), and diffusion-weighted image (DWI). Each group was sacrificed after the imaging, then histological examination for the tibiae with an implanted tumor was performed and MRI-pathologic correlation was done. RESULTS: On MRI-pathology correlation, the corresponding findings were as follows; low SI on T1WI, T2WI-tumor cells, fibrosis (1 week); central low SI on T1WI, T2WI, GdT1WI -tumor cells with fibrosis and necrosis; peripheral high SI on T2WI, DWI, GdT1WI-edema, fibrosis (2 weeks); heterogeneous SI with central low SI on T2WI, DWI-tumor cell nests with extensive necrosis, fibrosis; high SI on T2WI along periosteum-periosteal reaction; high SI around low SI and in bone marrow on T2WI, DWI, GdT1WI-edema, fibrosis; low SI on T1WI in surrounding bone marrow-tumor extension (3-4 weeks). CONCLUSION: The evolution of VX2 carcinoma model was well depicted on MR imaging. Necrosis and extent of tumor were best depicted on enhanced, fat-suppressed T1-weighted images. Heterogeneity of the tumor, peripheral edema, and fibrosis were represented well on T2-weighted images. Diffusion-weighted imaging could have a role in depicting necrosis in the evaluation of bone tumor.     

Multilocular cystic nephroma: MR imaging appearance with current techniques,including gadolinium enhancement

The purpose of the study was to define the MRI appearance of multilocular cystic nephroma (MLCN), using current MR techniques, including gadolinium (Gd)-enhanced sequences. Seven patients with MLCN underwent MR imaging with the following sequences: T1-weighted spin echo with fat suppression (TIFS, five patients), T1-weighted spoiled gradient echo (SGE, seven patients), T2-weighted fast spin echo (two patients), and Gd-enhanced TIFS (seven patients) and SGE (seven patients). MLCN was histologically proven by resection of the mass in six patients and by observation of typical imaging features with stability in appearance over a 6-month period in one patient. Lesion morphology and signal intensity (SI) features were retrospectively evaluated. MRI features of MLCN included a solitary cystic lesion with thin internal septations in six patients and a cluster of closely grouped cysts similar in size in one patient. Individual cystic spaces demonstrated SI, varying from low to high on T1-weighted images in three patients and demonstrated low-to-intermediate SI in four patients. Herniation of the lesions into the renal collecting system and thin enhancing septa were demonstrated in all patients. A complex cystic renal lesion with enhancing septa and herniation into the renal collecting system are the characteristic MR findings of MLCN. The direct multiplanar capability of MR may optimally show the relationship of MLCN to the renal pelvis and, thus, facilitate correct diagnosis.     

少突胶质肿瘤MRI增强与肿瘤分级的相关性分析

目的：探讨颅内少突胶质瘤的MRI增强表现,分析肿瘤强化与肿瘤分级的相关性。方法：回顾性分析30例31个病理证实的颅内少突胶质肿瘤的MRI资料,观察病变强化程度、强化方式,测定肿瘤增强率并与肿瘤分级及亚型作对照研究。结果：31个颅内少突胶质肿瘤,24个为单纯型（OD）,其中分化好的（Ⅱ级）15个,间变型（Ⅲ级）9个;7个为混合型（OA）,其中Ⅱ级3个,Ⅲ级4个。平均肿瘤增强比（CER）分别为Ⅱ级OD：1．11±0．11,Ⅱ级OA：1．37±0．31,Ⅲ级OD：1．65±0．18,Ⅲ级OA：2．16±0．32,与肿瘤分级及恶性程度呈正相关（P=0．000）,在两种级别肿瘤中差异有显著性意义（P=0．002）。当分界值为CER=1．30时,判断肿瘤级别的敏感度为85％,特异度78％。三种强化方式见于19个有增强的肿瘤（Ⅲ级对Ⅱ级分别为11／13 vs 8／18）：均匀点状结节样强化（7／13 vs 7／18）、环形强化（9／13 vs 2／18）、大块强化（2／13 vs 0）。结论：MRI肿瘤增强更多见于高级别少突胶质肿瘤,平均肿瘤强化比依Ⅱ级OD,Ⅱ级OA,Ⅲ级OD,Ⅲ级OA的顺序呈上升趋势。点状、结节状强化是该肿瘤的特征性强化方式之一,环形强化的出现预示肿瘤高级别可能。