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Biomedical subjects

G Frija

Publications and source records attributed to G Frija.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Teleradiology].

Explore the source record for details and available documents.

Humans↗
PubMed1998

Contrast agents in magnetic resonance imaging of the liver: present and future.

New contrast agents are being developed by drug companies to better image the liver magnetic resonance imaging (MRI). They can be divided into hepatobiliary agents (Gd-EOB-DTPA, Gd-BOPTA, Mangafodipir) and nanoparticulate agents directed to the reticulo-endothelial system (ferumoxides, SHU 555A). After intravenous injection, all these agents concentrate in the liver and induce profound signal changes. Particulate agents induce predominantly a darkening of the liver parenchyma, while hepatobiliary agents induce a brightening. In both cases, liver-lesion conspicuity is enhanced, leading to a better visualization of the lesion. After a description of the principal pharmacokinetic characteristics of the compounds, this review paper summarizes the utility of the agents in the detection and characterization of focal liver diseases.

Contrast Media↗
PubMed1998

Symptomatic hepatic cysts: treatment with single-shot injection of minocycline hydrochloride.

PURPOSE: To assess the efficacy of percutaneous minocycline hydrochloride sclerotherapy in symptomatic hepatic cysts. MATERIALS AND METHODS: From November 1992 to June 1994, seven of eight consecutive adults with large symptomatic hepatic cysts (diameter, 55-130 mm) were treated with a single intracystic injection of minocycline hydrochloride in an ambulatory procedure. Five patients had a solitary cyst, and two had polycystic liver disease. The target cyst was punctured under ultrasound guidance and local anesthesia with a 22-gauge Chiba needle. Half of the cyst content was aspirated before injection of 100-500 mg of minocycline hydrochloride diluted in 5-25 mL of saline. The minocycline hydrochloride was left in the cyst at the end of the procedure. RESULTS: After a mean follow-up of 28 months (range, 24-42 months), all five patients with solitary cysts were asymptomatic and four had documented complete cyst regression; the two patients with multiple hepatic cysts showed only transient clinical improvement. CONCLUSION: Single-shot injection of minocycline hydrochloride is an effective treatment for symptomatic solitary hepatic cysts but is less effective in polycystic liver disease.

Anti-Bacterial Agents↗
PubMed1998

Liver imaging with ferumoxides (Feridex): fundamentals, controversies, and practical aspects.

Superparamagnetic nanoparticles (Feridex) have been recently made available to the radiological community as a contrast agent for MR imaging of the liver. This article reviews the principal physicochemical characteristics of this new compound, with an emphasis on the explanation of the contrast obtained (either positive or negative enhancement) that depends on the local concentration and the sequence used. The clinical use of Feridex is detailed, both for lesion detection and characterization. Finally, some guidelines for image optimization are given.

Contrast Media↗
PubMed1998

[What is bright on T1 MRI scans?].

The list of entities associated with a high signal intensity on T1-weighted images is extensive and classically includes fat, proteins, hemorrhage, melanin and gadolinium. However, additional entities may be responsible for abnormally high signal intensity on T1-weighted images. These include ion deposition in metabolic disorders, free radicals, increased proton density, flow phenomena, some artifacts, and new contrast agents. The aim of this article is to display both the common and uncommon causes for a high T1 signal intensity and to discuss the underlying mechanisms or attributable pathophysiology for this phenomenon.

Artifacts↗
PubMed1997

A gerbil model for rhombencephalitis due to Listeria monocytogenes.

Rhombencephalitis due to Listeria monocytogenes is a frequent complication of human listeriosis, inducing a high mortality and severe neurological sequelae despite antibiotic therapy. However, there is no animal model which consistently reproduces clinical rhombencephalitis. Here, we present a model of Listeria rhombencephalitis in gerbils. Animals were inoculated in the middle ears with a low infective dose of L. monocytogenes, thus creating prolonged otitis media with persistent bacteremia. Gerbils developed a severe rhombencephalitis with circling syndrome, paresia, ataxia, rolling movements. The invasion of the central nervous system was visualized on living animals by resonance magnetic imaging and characterized by bacterial growth in the brain, reaching about 10(7) bacteria in the rhombencephalum by day 12 of infection. The histological lesions were mainly located in the brainstem, and consisted in coalescent, necrotic abscesses with perivascular sheaths, mimicking those observed in human rhombencephalitis. Bacteria were detected by electronmicroscopy inside infectious foci, either free in necrotic material or inside inflammatory cells, mainly polymorphonuclear cells. This gerbil model of Listeria rhombencephalitis will be useful to study the molecular mechanisms allowing bacteria to cross the blood-brain barrier, and to evaluate the intracerebral efficacy of antibiotics.

Animals↗
PubMed1997

Measurement of liver blood volume using a macromolecular MRI contrast agent at equilibrium.

Liver regional blood volume (LRBV) is altered by several disease states and various drugs. Preliminary studies in the rat, using research MR imaging instruments at 2T and vascular contrast agents, have suggested that MRI may be used to measure LRBV. Our goal was to develop a technique for measuring LRBV using a clinical machine at 1.5 T. This study was performed in the rabbit, using CarboxyMethylDextran Gd-DTPA, a macromolecular contrast agent with a molecular weight of 158 kDa. MRI was performed at 1.5 T, in the plane of the inferior vena cava, with and without flow compensation, before contrast injection and in the steady state after injection. Accuracy and stability of LRBV measurement, over 2 h and with various doses (0.01-0.05 mmol/kg), was tested against a standard Evan's Blue dye-indicator technique. LRBV was 28 +/- 2 mL/100 g when measured by MRI with flow compensation, which is in good agreement with the literature and with the 26 +/- 6 mL/100 g, measured by the Evan's Blue dilution technique. Measurements varied less than 7% over time and less than 9% over the range of doses. LRBV was overestimated using a sequence without flow compensation especially when large doses of contrast agent were injected. This noninvasive MRI technique provides a simple method for measuring liver LRBV and offers new prospects for future physiological and pathological studies.

Animals↗
PubMed1997

Liver positive enhancement after injection of superparamagnetic nanoparticles: respective role of circulating and uptaken particles.

Superparamagnetic nanoparticles have both high r1 and r2 relaxivities responsible for positive or negative enhancement properties. The aim of this study was to investigate to what extent perfusion (circulating particles) and uptake (clustered particles) mechanisms contribute to liver positive or negative enhancement using two different particles, superparamagnetic iron oxides (ferumoxides, AMI 25) and ultrasmall superparamagnetic iron oxides (ferumoxtran, AMI-227). Uptake kinetics were studied after intravenous injection of 20 micromol Fe/kg ferumoxtran on a washout liver model. Livers of 82 rats were surgically isolated and washed with saline infusion. Imaging was performed ex vivo at 0.5T with T1- and T2-weighted sequences. Enhancement kinetics of the liver were studied in vivo using MRI up to 180 min post injection of 20 micromol Fe/kg ferumoxtran (time response study) or 10, 20, 40 micromol Fe/kg ferumoxtran and 20 micromol Fe/kg ferumoxides (dose response study.) Particle uptake occurred early and resulted in a negative enhancement of the washed livers 15 min after injection of both T1 and T2 sequences. In vivo, a positive enhancement was only seen during the first five min with the lowest dose of ultrasmall superparamagnetic iron oxides and the T1 sequence. Uptake and clustering of the particles induced a negative liver enhancement. During the first minutes after injection, when uptake has not significantly occurred, perfusion imaging of the liver at a dose of 10 micromol Fe/kg results in a positive enhancement with T1-weighted sequences.

Analysis of Variance↗
PubMed1997

[Pseudotumor aspect of ovarian vein thrombosis].

Ovarian vein thrombosis is an unusual puerperal illness (1 in 600 deliveries) which usually recovers spontaneously or under treatment. We report a rare follow-up observation of a puerperal ovarian vein thrombophlebitis, first diagnosed by computed tomography, which evolved to a 6 x 10 cm pseudotumoral cavernoma mass after 18 months.

Adult↗
PubMed1997

[False radiologic pneumoperitoneum. The value of emergency abdominal computed tomography].

We report 2 cases of false pneumoperitoneum. The diagnosis was suspected on an upright chest or abdominal plain films. The absence of clinical signs and symptoms of peritoneal irritation suggested a wrong radiological diagnosis. Emergency CT scan definitely eliminated a pneumoperitoneum and suggested the right diagnosis in both cases. This exam may play the decisive role in preventing needless emergency laparotomy.

Aged↗
PubMed1996

Capillary leakage of a macromolecular MRI agent, carboxymethyldextran-Gd-DTPA, in the liver: pharmacokinetics and imaging implications.

Capillary leakage of a macromolecular contrast agent, Carboxymethyl Dextran-Gd-DTPA (CMD-Gd-DTPA) was characterized in a highly permeable system, the liver, to assess its potential as a blood pool marker. Its elimination kinetics in hepatic lymph were compared in nephrectomized rabbits with that of a tracer of extra cellular fluid space, Gd-DOTA. Four parameters were defined: volume of distribution, normalized initial leakage rate (ILRn), maximum ratio of lymph and plasma concentrations (max Cl/Cp), and the time to obtain this maximum ratio. The effect of this leakage was studied on MR images by comparing liver contrast enhancement after injection and after almost total removal of the contrast agent from the blood by exchange transfusion. Capillary leakage of CMD-Gd-DTPA was detected in lymph. Compared to Gd-DOTA, it was slower (ILRn = 0.36 10(-5) l min-1 for CMD-Gd-DTPA and ILRn = 2.6 10(-5) l min-1 for Gd-DOTA), less abundant (max Cl/Cp was 80% for CMD-Gd-DTPA and 100% for Gd-DOTA). Liver enhancement remained stable, which indicated that the leakage did not modify the enhancement induced by the intravascular fraction of the contrast agent. These results obtained in a highly permeable capillary model indicate that this agent can be used as a selective blood pool enhancer.

Animals↗
PubMed1996

Efficacy and safety of iobitridol versus iohexol for contrast-enhanced CT of the head.

PURPOSE: The efficacy and adverse reactions of iobitridol versus iohexol in contrast-enhanced CT (CECT) of the head were investigated. MATERIAL AND METHODS: This double-blind randomized parallel study compared the clinical and biological safety of iobitridol and iohexol (350 mgI/ml), administered intravenously (1 ml/kg) to 276 patients undergoing CECT of the head. Vital signs were assessed just before after injection, and 24 hours after. A biologic examination was performed before and after injection. Both groups were comparable at inclusion. RESULTS AND CONCLUSION: The within-group variation for vital signs after injection and 24 hours after was not clinically relevant and no significant difference was evident between treatment groups. The incidence of adverse events was similar in both groups (11.0% for iobitridol and 7.1 % for iohexol), consisting most often of a sensation of warmth. Biologic parameters remained stable and did not differ significantly between groups. The quality of imaging was rated good or excellent in 70% of cases and a very high diagnostic discrimination was achieved (98%). Iobitridol compared favorably with iohexol for head CECT.

Adolescent↗