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Biomedical subjects

D Revel

Publications and source records attributed to D Revel.

At least 109 records · Page 6Linked to original sources
PubMed1988

[Digital arteriography of the lower limbs by sequential, automatic table translation. Feasibility. Preliminary results].

Digital subtraction angiography (DSA) as a method of evaluating lower limb arteries required examination of one limb at a time up to now. Moreover repeated injections of contrast material were necessary. This problem was mainly due to the relative small image intensifier field available and to the difficulty of repositioning the patient between mask and image acquisition. The authors report the preliminary results obtained with 24 patients studied on angiographic unit equipped with: A DSA system (DG 300-CGR) using 512 X 512 matrix size, an angiographic table (Angix M 200) allowing an automatic sequential translation, a removable image intensifier using a 16 inch field below the table. Thus, all those characteristics allow DSA of lower limb arteries. Only one injection of contrast material (Ioxaglate: 80 ml at 8-10 ml/second) was used per procedure. This, usually, allows good quality examination of lower limb arteries.

Angiography↗
PubMed1987

Gadolinium-DTPA enhanced MR imaging of intramuscular abscesses.

Sterile, chemical and bacterial abscesses were induced in the paraspinal muscles of 16 rats before obtaining magnetic resonance (MR) images using a 0.35-T resistive system. Abscess intensity, T1 and T2 values were recorded before and after the intravenous administration of Gd-DTPA (0.2 mmol/kg). The MR appearances of the abscesses were correlated with histologic sections. Both sterile and bacterial abscess were detected on MR images without the use of contrast medium, particularly on the T2-weighted spin echo sequence (TE/TR 56/2000 ms). However, the inflammatory zones of abscesses markedly enhanced in intensity with a corresponding decrease in T1 values after the administration of Gd-DTPA (TE/TR 28/500 ms). A clear distinction between the necrotic center and the cellular periphery of each abscesses was evident only after contrast enhancement (TE/TR 28/500 ms). Thus paramagnetic Gadolinium-DTPA was beneficial for defining the histologic components of abscesses on spin echo MR images.

Abscess↗
PubMed1987

Magnetic resonance imaging of experimental renal hemorrhage.

Experimental renal hemorrhage was induced by injecting autologous blood into the left kidney of 13 rats. To investigate the magnetic resonance (MR) characteristics of acute renal hemorrhage and subsequent stages of resolution, repetitive MR images were obtained using a 0.35 Tesla imager during a period of 21 days postinduction. A dual spin-echo imaging (TR 500 and 2,000 msec, TE 28 and 56 msec) was used to calculate the relaxation times and record the intensities in the renal medulla and cortex. Histologic examination (n = 9) indicated that blood was dispersed intrarenally, and no encapsulated hematoma developed. The signal intensity on the T1- and T2-weighted images, as well as the relaxation times in the hemorrhagic renal parenchyma were unchanged during 21 days when compared with intact kidney values. Subcapsular fresh blood had a high signal intensity on T2-weighted images. A marked overlap of the relaxation parameters between intact kidney parenchyma and diffuse intrarenal hemorrhage was observed. Detection of dispersed intrarenal blood using spin echo MR imaging may be difficult.

Animals↗
PubMed1987

Metalloporphyrin contrast enhancement of tumors in magnetic resonance imaging. A study of human carcinoma, lymphoma, and fibrosarcoma in mice.

The diagnostic use of Mn(III)TPPS4, a paramagnetic metalloporphyrin, for MR contrast enhancement was examined in human--mouse xenograph models of carcinoma, lymphoma, and sarcoma. Spin-echo images of 15 mice, five mice for each implanted tumor type, were obtained before and at 20 minutes, and 2, 4, and 24 hours following administration of 0.09 mmol/kg of Mn(III)TPPS4. All tumors had a uniform moderate signal intensity on precontrast images. After administration of Mn(III)TPPS4, all tumors demonstrated significant enhancement of signal intensity that persisted to 24 hours. T1 relaxation times were maximally depressed at 2-4 hours and remained low to 24 hours for all three tumors. Kidney signal intensity reached a maximum at 20 minutes and remained significantly above background for 24 hours. The high relaxivity and apparent avidity of Mn(III)TPPS4 for divergent tumor histologies support the potential use of this agent for improved diagnostic specificity of MR imaging for neoplastic masses.

Animals↗
PubMed1986

Contrast-enhanced MRI of periarticular soft-tissue changes in experimental arthritis of the rat.

This study was to determine if manipulation of magnetic resonance signal intensity by means of an intravenously injected paramagnetic contrast agent is useful for the detection and characterization of periarticular inflammation. Arthritis was induced in 20 rats by means of intradermal injection of Freund's complete adjuvant. MR imaging was performed with a resistive magnet operating at 0.35 T. A double spin-echo technique with TE's of 28 and 56 ms and TR's of 0.5 and 2.0 s was used. The hindpaws of the adjuvant-injected rats were imaged on Day 8, Day 11, or Day 15 following injection of the adjuvant. The images were obtained in the transverse plane before and after intravenous injection of gadolinium-DTPA (0.2 mmol/kg). Because of their long T2 relaxation time, inflammatory lesions were characterized by high MR signal intensity on precontrast images obtained with long TR and long TE (T2-weighted images). On the other hand, because of their long T1 relaxation time, the inflammatory lesions were of relatively low intensity and not easily recognized on precontrast images obtained with short TR and short TE (T1-weighted images). Postcontrast T1-weighted images were also sensitive in detecting periarticular inflammation as a result of T1 shortening by the gadolinium-DTPA. However, in our particular model, the data did not indicate any greater MR sensitivity for detecting arthritis by means of gadolinium-DTPA enhancement.

Animals↗
PubMed1986

Changes in proton relaxation times of the rat spleen during adjuvant-induced immunologic reaction.

Possible changes in magnetic resonance (MR) relaxation times resulting from an immune reaction were evaluated in the rat spleen by means of in vitro proton spectroscopy and an established model of immune disease. Heat-killed Mycobacterium butyricum in Freund's adjuvant was injected intradermally into the tail of 28 rats. Ten normal rats served as controls. At different times following the injection of adjuvant (day 7, day 10, day 12, day 14, or day 22), the spleens were removed and weighed, and proton T1 and T2 relaxation times were measured with a 0.25-T spectrometer (10.7 MHz). Water content was also determined. Specimens of each spleen were histologically examined; this included Prussian-blue staining for detection of hemosiderin. In 22 of the 28 adjuvant-injected rats, spleen T1 values increased significantly, from a mean value of 451 msec +/- 23 S.D. (control rats) to a maximum mean value of 571 +/- 15 S.D., which occurred on day 12; this T1 increase paralleled an increase in weight and water content and a histologic appearance of granulomatous inflammation. In these rats, T2 changes were not significant. In the other six adjuvant-injected rats, spleen T2 relaxation time significantly decreased from a mean value of 42 msec +/- 5 S.D. to a mean value of 32 msec +/- 1 S.D. Histologic evaluation indicated that the origin of this T2 decrease was probably the presence of hemosiderin in the spleens of only these six rats. Mean T1 of these spleens decreased slightly, but not significantly.

Adjuvants, Immunologic↗
PubMed1986

Gd-DTPA contrast enhancement and tissue differentiation in MR imaging of experimental breast carcinoma.

Gadolinium-DTPA (Gd-DTPA) enhancement of magnetic resonance (MR) imaging was tested for diagnostic utility in evaluating carcinoma. Human breast carcinoma implanted in ten nude mice was studied before and after injection of Gd-DTPA at two different doses (0.2 and 0.5 mmol/kg body weight). Before injection, all tumors appeared homogeneous in intensity on spin-echo images; after injection, it was possible to distinguish areas of strong enhancement from areas of weak enhancement. Histologic correlations showed that the strongly enhanced areas corresponded to richly vascularized connective tissue and apparently viable tumoral tissues, while the weakly enhanced areas corresponded to nonvascularized necrotic tissue. The results indicate that intravenously administered paramagnetic agents such as Gd-DTPA may improve the specificity and diagnostic accuracy of MR imaging by permitting better differentiation of tumor elements.

Adult↗
PubMed1986

Differentiation of reversible and irreversible myocardial injury by MR imaging with and without gadolinium-DTPA.

The current study evaluated the capability of magnetic resonance (MR) imaging to distinguish myocardium subjected to reversible and irreversible ischemic injury. Nine dogs underwent left anterior descending coronary arterial occlusion for 15 minutes (reversible injury) and nine for 1 hour (irreversible injury), followed by reperfusion for 24 hours in both groups. Six dogs from each group received 0.5 mmol/kg of gadolinium-DTPA intravenously; the remaining dogs received no contrast media. In the dogs with irreversible injury but no contrast media, there were prolonged T1 and T2 of the infarcted myocardium and adequate visualization of the infarct. The percentage of contrast between normal and infarcted myocardium was greatest on T2-weighted images. In the group with irreversible injury and contrast media, Gd-DTPA produced significant T1 shortening of injured myocardium, with resultant high signal intensity of the infarct, and significantly enhanced contrast compared with the group that did not receive Gd-DTPA. In the dogs with reversible injury, there were no regional differences in intensity or relaxation times. MR has the capability to distinguish myocardium with irreversible injury from that with reversible injury. The difference of T1 between normal and reperfused infarcted myocardium is increased by Gd-DTPA; thus, contrast between these two is enhanced on MR images.

Animals↗
PubMed1986

[Comparative study of external methods (Doppler, rheography, flow using Xe) and arteriography of the legs, in the evaluation of stenoses. Statistical evaluation by the Kappa test].

On a thirty five homogeneous group of arteriosclerotic patients, the authors study by means of the Kappa test the validity of arteriographic and non invasive techniques data interpretation by two trained observers. Then they compared between the conclusion of these methods again with Kappa test. The viability of arteriographic and Doppler interpretation is good. The comparison between arteriographic and external techniques results needs strong reduction of the arteriographic data in large classifications. Doppler (with distal pressure) is the best of non invasive techniques, the others staying less selective. The good correlation between arteriography and doppler data observed in main arteries is maximum for femoral arteries and decreases in distal arteries mainly because of a poor filling due to proximal lesions.

Angiography↗
PubMed1986

[2 cases of coronary embolism. Angiographic diagnosis and anatomopathological confirmation].

The authors report two cases selected from a series of 61 cases of coronary embolism observed over an 18 year period at the Cardiovascular Hospital (Lyon) out of 4,860 autopsies of adult patients who died of cardiovascular causes. These two cases underwent coronary angiography, the results of which correlated with the autopsy findings. The authors review the causes and clinical manifestations of coronary embolism and compare their results with previously reported data, to establish the radiological features of coronary embolism. They notice the regular appearance of obstruction due to embolism and underline the importance of the associated negative signs (normality of the rest of the coronary circulation, absence of collateral vessels...) which makes the angiographic diagnosis one of elimination.

Adult↗
PubMed1985

MRI of a retained sponge in a dog.

Retained sponges after laparotomy may cause a broad spectrum of clinical symptoms and present a difficult diagnostic problem. We report a case of retained surgical sponge in a dog to illustrate the MRI findings of this infrequent but important cause of postoperative complications.

Abdomen↗
PubMed1985

Magnetic resonance imaging in the diagnosis of acute renal allograft rejection and its differentiation from acute tubular necrosis. Experimental study in the dog.

This study was designed to evaluate the potential utility of magnetic resonance imaging (MRI) for the diagnosis of acute renal allograft rejection and its differentiation from acute tubular necrosis (ATN). Eighteen canines were used. Five animals served as controls. ATN was induced in six animals by cross-clamping of the left renal artery for 90 minutes. In order to study acute renal allograft rejection, seven animals were subjected to exchange allograft transplantation of the left kidney. MRI was performed with a 0.35T superconductive magnet. A double spin-echo technique was used with varying TR and TE parameters. The spin echo images were analyzed for morphology, signal intensity, T1 and T2 relaxation times, and spin density. The most useful MRI criteria for the diagnosis of ATN and acute rejection were found to be the renal size, the intensity difference between cortex and medulla (corticomedullary contrast), and the T1 relaxation time of the cortex. Normal kidneys showed maximal corticomedullary contrast (19% +/-2) on images obtained with TR = 0.5 sec and TE = 28 msec. Cortical T1 relaxation time was 551 msec + /-73. In the ATN group, the kidneys were slightly swollen (P = ns) and the corticomedullary contrast (11% + /-3) was reduced by 42% (P less than .01). T1 of the cortex (689 + /-142) was increased by 25% (P less than .10). In acute rejection, significant renal enlargement was noted (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1985

Magnetic resonance imaging and spectroscopy of the periarticular inflammatory soft-tissue changes in experimental arthritis of the rat.

Arthritis was induced in rats by intradermal injection of Freund's complete adjuvant. MRI was performed with a resistive imager operating at 0.35 T. A spin echo (SE) technique with TR = 0.5 and 2.0 seconds, TE = 28 and 56 msec was used. Transaxial images of hindpaws and knees were obtained at different times after injection of adjuvant. In vitro proton spectroscopy of normal and arthritic hindpaws was also performed. Histologic confirmation was obtained in each case. Inflammatory soft-tissue lesions were seen as focal areas of high intensity on spin echo images obtained with TR = 2.0 seconds and TE = 56 msec and were characterized by long T1 and T2 relaxation times and high spin density. In comparison with both conventional radiography and physical examination, early soft-tissue changes were detected more frequently by MRI. This study suggests that MRI is likely to be of value for the early diagnosis of arthritis.

Animals↗
PubMed1985

[Contrast agents in magnetic resonance imaging].

The origin of nuclear magnetic resonance signal is reminded in this paper. Different ways of increasing the contrast in magnetic resonance imaging are presented, especially modifications of tissues relaxation times by the use of paramagnetic ions or nitroxides. The potential of these substances is illustrated by several examples of application in the animal.

Animals↗
PubMed1985

Magnetic resonance imaging of ischemic heart disease.

Magnetic resonance imaging (MRI) has several attributes important for evaluating ischemic heart disease. Internal cardiac anatomy is well delineated owing to inherent contrast between the blood pool and the cardiac walls. Using relaxation times and signal intensity differences, it is possible to discriminate between infarcted (acute and chronic) and normal myocardium. Gated MRI can also be used to quantitate regional myocardial infarction.

Coronary Disease↗
PubMed1984

Acute myocardial ischemia: magnetic resonance contrast enhancement with gadolinium-DTPA.

Gadolinium-DTPA (Gd-DTPA) was used to improve the diagnostic utility of magnetic resonance (MR) in detecting early ischemia, before the onset of infarction. Following one minute of left anterior descending coronary artery occlusion, 9 dogs were intravenously injected with either 0.5 mM/kg of Gd-DTPA (6 dogs) or normal saline (3 dogs). One more minute was allowed for perfusion of injectate prior to cardiectomy and MR imaging of the ex situ heart. There was no visible difference in intensity or alterations in magnetic relaxation times between normal and ischemic myocardium in the control (saline-injected) animals. The Gd-DTPA-injected dogs had a well-defined segment of high intensity representing the ischemic myocardium in the anterior wall of the left ventricle, due to significant T2 relaxation rate enhancement in the adjacent normal myocardium. Both T1 and T2 were significantly (p less than 0.01) shortened in the normal myocardium of the Gd-DTPA animals, but relatively greater T2 relaxation rate enhancement resulted in reduced intensity of normal myocardium, thus increasing contrast with ischemic myocardium. As a result of the significant shortening of T1 and T2 in the normal myocardium relative to the ischemic myocardium, improved delineation of the ischemic segment could be obtained using calculated T1 and T2 images. It is concluded that Gd-DTPA has the potential to expand the sensitivity and diagnostic utility of MR in the study of occlusive coronary artery disease.

Animals↗
PubMedDate not supplied

Influence of bolus volume and dose of gadolinium chelate for first-pass myocardial perfusion MR imaging studies.

First-pass MR myocardial perfusion measurements require a well-defined left ventricular (LV) blood pool input function. We used a peripheral intravenous (i.v.) injection of a gadolinium (Gd) chelate to obtain a well-characterized LV time-intensity curve. Using a strongly T1-weighted subsecond MR sequence, we performed cardiac MR imaging after administering an IV bolus injection of one of three different doses of the Gd chelate: a standard dose (0.1 mmol/kg, group I, n = 8); a low dose with two bolus volumes (0.01 mmol/kg, 1/10e bolus volume, group II, n = 7, and 0.01 mmol/kg diluted in saline, same bolus volume as group I, group III, n = 3); and an intermediate dose (0.05 mmol/kg, group IV, n = 5). Unlike in group I (high dose), in groups II and III (low dose), the LV curve had a well-defined first peak, followed by a downslope and a recirculation peak. With the intermediate dose (group IV), a saturation effect still remained on the LV curve. The signal intensity (SI) enhancement of the myocardium was respectively 580 +/- 77% at 0.1 mmol/kg, 362 +/- 95% at 0.05 mmol/kg, and at 0.01 mmol/kg, it was 184 +/- 33% in group II and 272 +/- 8% in group III. In conclusion, with subsecond T1-weighted MR imaging and a low dose of Gd chelate (i.e., 0.01 mmol/kg), the LV input function is a well-defined first step for MR perfusion modeling.

Contrast Media↗