Nodular sarcoidosis of the liver and spleen: Appearance on MR images

Small nodular lesions in the liver and spleen have been reported as an infrequent manifestation of sarcoidosis. Five patients with this appearance on either dynamic contrast material—enhanced computed tomographic (CT) or ultrasound scans underwent magnetic resonance (MR) imaging with and without dynamic gadolinium enhancement. The lesions were relatively uniform in size, ranging from 0.5 to 1.5 cm. On CT scans, they were hypoattenuating relative to surrounding parenchyma. On MR images, the lesions were hypointense relative to background parenchyma with all sequences. No substantial enhancement was observed in the lesions, although lesion conspicuity decreased over time on serial postcontrast images. Lesion conspicuity was greatest on either T2-weighted fat-suppressed (T2FS) images or early-phase dynamic contrast-enhanced images. Abdominal adenopathy was seen in three of the five patients and was hyperintense relative to liver on T2FS images in two and intermediate in intensity in one patient.     

Inhibitory effect of amiloride and gadolinium on fine afferent nerves in the rat knee: evidence of mechanogated ion channels in joints

Synovial joints are complex sensory organs which provide continuous feedback regarding position sense and degree of limb movement. The transduction mechanisms which convert mechanical forces acting on the joint into an electrochemical signal which can then be transmitted to the central nervous system are not well understood. The present investigation examined the effect of the mechanogated ion channel blockers amiloride and gadolinium on knee joint mechanosensitivity. In deeply anaesthetised rats (sodium thiopental: 100–120 mg/kg, i.p.), single unit extracellular recordings were made from knee joint group III (Aδ) and group IV (C) primary afferents in response to mechanical rotation of the joint. Afferent firing rate was measured before and after topical application of either amiloride (0.1 mM, 1 mM) or gadolinium (250 μM) onto the receptive field of the sensory unit and recording was continued every 10 min up to a total of 50 min. With normal rotation of the knee, joint mechanosensitivity was significantly reduced by both amiloride (P<0.0001; n=10–21) and gadolinium (P=0.001; n=12) and this effect was sustained throughout the recording period. This investigation provides the first in vivo electrophysiological evidence that joint mechanotransduction involves the activation of amiloride and gadolinium-sensitive mechanogated ion channels. Future studies to determine the mechanogated ion channel subtypes present in joints and the modulation of their gating properties during inflammation may yield novel approaches for the control of arthritis pain. Funding: JJMcD is funded by the Alberta Heritage Foundation for Medical Research, the Canadian Institutes for Health Research, and the Arthritis Society of Canada.     

Characterization of the role of calcium and sodium channels in the stimulus secretion coupling of 5-hydroxytryptamine release from porcine enterochromaffin cells

Summary Strips of the porcine small intestine were incubated in vitro and the outflow of 5-hydroxytryptamine (5-HT) was determined by HPLC with electrochemical detection.Spontaneous outflow of 5-HT from the porcine small intestine was reduced by about 70% after removal of the extracellular calcium or by addition of 1 mM gadolinium. Tetrodotoxin reduced the outflow of 5-HT by 30%, an effect which has previously been shown to be caused by inhibition of an excitatory cholinergic input. The sodium channel opener veratridine (up to 100 M) did not affect the outflow of 5-HT. -Conotoxin GVIA (500 nM) or nifedipine (10 M) reduced the outflow of 5-HT only by about 50%, and their effects were not additive. The inhibitory effects of -conotoxin GVIA occurred also in the presence of tetrodotoxin. Elevation of extracellular potassium to 40 mM caused a marked and sustained increase in 5-HT outflow. High potassium evoked release of 5-HT was blocked by -conotoxin GVIA, nifedipine and gadolinium. When -conotoxin GVIA and nifedipine were present in combination, their inhibitory effects on the high potassium evoked 5-HT release vanished. BAY K 8644 (1–10 M) did not facilitate 5-HT release, but markedly reduced the spontaneous and high potassium evoked release of 5-HT.In conclusion, the enterochromaffm cells are endowed with multiple calcium channels, but voltage-sensitive calcium channels of a neuronal L-type which are sensitive to dihydropyridines and -conotoxin GVIA appear to play a major role.Abbreviations 5-HT 5-hydroxytryptamine - 5-HIAA 5-hydroxyindoleacetic acid - TTx tetrodotoxin Correspondence to K. Racke at the above address     

肺血管磁共振成像:比较二维TOF、三维TOF及Gd-DTPA增强

目的 探讨２种常用的ＭＲ血管成像方法对正常肺动脉图像质量的影响及Ｇｄ－ＤＴＰＡ知其中的作用。材料和方法：用１．０Ｔｅｓｌａ超导ＴＲＩ系统,体线圈技术,随机选择无人心肺疾患志愿者４６例,行２Ｄ ｔｕｒｂｏ ＦＬＡＳＨ和／或３Ｄ ＦＩＳＰ肺部ＭＲＡ检查共１１３次,行Ｇｄ－ＤＴＰＡ增强后２Ｄ ｔｕｒｂｌ ＦＬＡＳＨ和／或３Ｄ ＦＩＳＰ扫描共４７次。计算机测量肺动脉和背景噪声的信号强度,计算出肺动脉的信噪     

Detection of severe acute pancreatitis by contrast-enhanced magnetic resonance imaging

The aim of the study was to assess the ability of MRI to differentiate between the two forms of severity of acute pancreatitis (AP), which is important for the detection of patients who require intensive monitoring and therapy. The second objective was to evaluate whether the distinction would be possible regardless of the MRI equipment. Magnetic resonance imaging was performed before and after intravenous administration of a gadolinium (Gd) chelate at 1.0 T using the breath-hold multislice rapid gradient-echo turbo fast low-angle shot (FLASH) sequence in 14 patients, and at 1.5 T with the 2D FLASH(50) sequence with fat saturation in 18 patients with acute pancreatitis early in the course of the disease. The patients were classified according to the Atlanta classification system as having the mild (MAP) or severe (SAP) form of the disease. At 1.0 T with use of a body coil, contrast-enhanced MRI failed to distinguish mild from severe pancreatitis. At 1.5 T with a phased-array body coil, the signal intensities of the patients with SAP were statistically significantly lower than those of the MAP group. Our initial clinical experience suggests that MRI with a sufficient magnetic field gradient strength may be useful for separating the two forms of acute pancreatitis in their early phases. Received: 19 January 1999; Revised: 28 May 1999; Accepted: 22 July 1999     

Successful coronary angiography with adequate image acquisition using a combination of gadolinium and a power injector in a patient with severe iodine contrast allergy

A history of severe allergic reaction to iodine contrast leading to anaphylactic shock presents a dilemma in patients requiring cardiac catheterization. As an alternative, gadolinium has been an interesting and potentially useful agent. However, gadolinium produces poor image quality and has been associated with significant arrhythmias in small case series. Furthermore, there is no consensus about the maximal allowable dose that can be administered to a patient. In the present report, a successful combination of gadolinium contrast with a power injector that produced adequate image quality in a patient with severe allergy to iodine contrast is described. The case was complicated by the occurrence of ventricular fibrillation when damping occurred during injection of contrast into the right coronary artery. This complication has been reported previously with intracoronary gadolinium injection. The report is followed by a brief literature review.     

The use of gadolinium-based contrast agents in Ghana with a focus on residual intracranial gadolinium deposition

IntroductionThe aim of the survey was to identify current practice of the use of gadolinium-based contrast agents (GBCAs) in the wake of recent reports on gadolinium deposition in the brain following repeated administration of GBCAs.MethodA total of 13 facilities in Ghana with magnetic resonance imaging (MRI) departments were contacted via email with a two-page questionnaire.ResultsA response rate of 69.2% (n = 9) was achieved. Gadodiamide (Omniscan) was the most commonly used GBCA. Slightly more than half of respondents were aware of residual deposition of GBCAs in the brain. Majority of the respondents were aware of GBCA deposition in individuals with abnormal renal function, but not aware of its deposition in those with normal renal function. A great majority of the respondents do not record the type and dose of GBCA after each intravenous administration, and such information is not provided in MRI reports. More than half of the respondents do not check eGFR prior to the administration of GBCA even when a high-risk agent is used.ConclusionGadodiamide (Omniscan) a high-risk agent remains the most commonly used GBCA in Ghana. Awareness of current findings of GBCA deposition in the brain following repeated doses are not encouraging as revealed in this study. The need to adopt international standard guidelines into practice cannot be overemphasized in order to reduce the potential long-term effect of this deposition.     

Fibrose systémique néphrogénique

Nephrogenic systemic fibrosis is a recently described entity that occurs in patients with advanced renal failure. Its cause is probably toxic. The patients develop skin thickening, which is usually symmetrical on the limbs and sometimes extend to the trunk. Joint contractures and muscle sclerosis confine the patients to wheelchair. Systemic involvement may occur and includes cardiomyopathy, pulmonary fibrosis and diaphragmatic paralysis. The diagnosis is confirmed by the association of skin fibrosis and a cellular infiltration composed of CD34+ fibrocytes. Prognosis is severe with many deaths, rarely directly related to the disease. An improvement of lesions is possible, especially in case of resolution of the renal insufficiency. Several treatments have been evaluated, but none has shown consistent benefit. The toxic culprit is likely to be the gadolinium ions (Gd⁺⁺⁺), released from some contrast agents used in nuclear magnetic resonance imaging. Evidence of the responsibility of Gd⁺⁺⁺ is based on epidemiologic, biochemical and experimental data. Recommendations have been published for patients with renal insufficiency requiring a nuclear magnetic resonance imaging. If they are followed and efficient, it is likely that nephrogenic systemic sclerosis will disappear.