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Biomedical subjects

M Lafortune

Publications and source records attributed to M Lafortune.

At least 37 records · Page 2Linked to original sources
PubMed1994

Hemodynamic changes after transcatheter arterial embolization of hepatocellular carcinomas.

PURPOSE: To evaluate the serial hemodynamic changes that occur after transcatheter arterial embolization (TAE) of hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Twenty patients with HCCs treated with TAE were evaluated with color and duplex Doppler sonography before, immediately after, and 2 days after TAE. The changes in hepatic artery and portal vein velocity and flow were evaluated. RESULTS: The portal venous velocity and flow did not change significantly after TAE. The peak systolic velocity in the proximal hepatic artery decreased significantly (P < .01) immediately after TAE then returned to baseline values 2 days after TAE; the resistance index of the proximal hepatic artery increased significantly (P < .01) immediately after embolization, then returned to baseline values 2 days after TAE. Arterial signal in the distal hepatic artery, generally absent immediately after TAE, could be recorded 2 days after. CONCLUSION: There is a rapidly reversible decrease in hepatic arterial flow induced by embolization, without any change in portal venous flow.

Adult↗
PubMed1994

Iatrogenic injury to the bile duct: a working classification for radiologists.

PURPOSE: To assess the usefulness of the Bismuth classification method in the preoperative localization of iatrogenic bile duct lesions with cholangiography and to correlate these cholangiographic findings with surgical findings. MATERIALS AND METHODS: The records of 33 patients who underwent open or laparoscopic cholecystectomy and who sustained injuries to the biliary tract during the course of these procedures were reviewed retrospectively. The accuracy of the cholangiographic localization of bile duct injury was assessed with the Bismuth classification method, which is based on the localization of the traumatic lesion according to the distance from the biliary confluence. RESULTS: An exact correspondence between cholangiographic and surgical findings was found in 85% of the subjects. A minimal discrepancy was found in the remainder. There was no interobserver variation. CONCLUSION: The use of the Bismuth classification method appears to be an accurate and practical method for the grading of postoperative bile duct lesions with cholangiography.

Bile Ducts↗
PubMed1993

Hepatic artery: effect of a meal in healthy persons and transplant recipients.

Thirty healthy volunteers and 12 liver allograft recipients (two with cirrhotic changes seen at microscopy) were given a standard meal. Doppler sonography of the right and left hepatic arteries, the superior mesenteric artery, and the portal vein was performed. The change in hepatic arterial resistance was evaluated with the resistive index (RI). After the standard meal, portal venous flow increased in both the healthy volunteers and allograft recipients (more so in the latter group). Superior mesenteric arterial RI decreased in all subjects. A postprandial increase in hepatic arterial RI, likely reflecting constriction of the hepatic artery, was seen in both groups. It was absent in the two patients with recurrent transplant cirrhosis. These results show the importance of examining hepatic arterial flow in the fasting subject, since high resistance after a meal may be falsely interpreted as a sign of disease. Absence of a postprandial change in resistance of the hepatic artery could signal abnormal liver function.

Adult↗
PubMed1992

Renal arterial stenosis: slowed systole in the downstream circulation--experimental study in dogs.

To test the effect of stenosis of the renal artery on the downstream intrarenal blood flow, a snare was placed around the renal artery in 10 dogs and compressed to create stenosis while Doppler curves were obtained from interlobar arteries. Pulsed Doppler examination of the segmental and interlobar arteries was performed by means of placement of a 7.5-MHz mechanical sector transducer directly on the surface of the kidney. The following calculations were made: degree of stenosis (evaluated with aortography), acceleration index (AI) (the acceleration of systole), and resistive index. The Doppler measurements were compared with findings on angiograms. The AI for normal arteries ranged from 2.2 to 4.3, and for arteries with 75% or greater stenosis, from 1.0 to 1.3. Systolic peaks disappeared as near occlusion was achieved. These changes were reversible within seconds of release of the arterial snare. Such change is identical to change in the pulsus tardus and parvus waveforms seen in both acute and chronic severe stenosis of the renal artery in humans.

Animals↗
PubMed1992

Stenosis of the renal artery: assessment of slowed systole in the downstream circulation with Doppler sonography.

Slowing and dampening of systole in the arterial network distal to stenosis is a well-known Doppler sign of severe arterial stenosis. To determine whether this sign is present in boys and girls with such stenosis, intrarenal Doppler curves (acceleration index [AI] and resistive index [RI]) were compared with findings on renal arteriograms in 20 boys and girls; the AI was also measured in 10 boys and girls without renal disease. Statistical analysis of AI and RI measurements was performed. Eleven of 32 renal arteries were normal. The normal AI was 4.0-7.0; in arteries with greater than 75% stenosis, the AI was 0.7-1.7. In five arteries studied after angioplasty, the AI had changed from 0.7-1.5 to 4.0-5.6 at the first posttreatment examination (performed 28 hours to 1 week after angioplasty), and it remained normal during the 3-year follow-up period. In kidneys with stenotic arteries, the RIs were lower (0.43-0.54) than in healthy subjects (0.56-0.63). Regression and correlation coefficients of AI and RI measurements were statistically significant, and discrimination between normal arteries and those with greater than 75% stenosis was excellent.

Child↗
PubMed1992

Patent paraumbilical vein: anatomic and hemodynamic variants and their clinical importance.

Fifty-five of 353 patients with suspected portal hypertension studied with Doppler sonography had a patent paraumbilical vein. Of these 55 patients, 39 had the classic intrahepatic venous circulation found in Cruveilhier-Baumgarten syndrome: hepatopetal flow in all segmental portal veins and hepatofugal flow leaving the liver in a paraumbilical vein in the falciform ligament to join veins of the anterior abdominal wall. Sixteen patients had variants of the classic pattern: Flow in one or more segmental portal veins of the left lobe or the entire liver was hepatofugal. In addition, new venous channels connecting the left portal vein with the extrahepatic paraumbilical vein were found. Assessment of liver function with the Pugh score showed severe impairment in the majority of patients with a patent paraumbilical vein. Patients with the classic intrahepatic circulation had smaller esophageal varices than those with hemodynamic or anatomic variants. The presence of a patent paraumbilical vein did not prevent formation of esophageal varices in the patients studied.

Adolescent↗
PubMed1992

Development of the fetal brain in the second trimester: an anatomic and ultrasonographic demonstration.

The authors provide an anatomic and ultrasonographic description of the fetal brain from the 16th to the 27th week of development. During the second trimester the primitive brain is smooth and homogeneous and has few sulci and relatively large lateral ventricles. The cerebral hemispheres consist largely of cells migrating from the periventricular germinal matrix to the primitive cortex. The "featureless" hemispheres yield homogeneous ultrasonographic images very different from the more complex and familiar cerebral anatomy of fetuses and premature babies in the third trimester.

Brain↗
PubMed1991

Air in the portal vein: sonographic and Doppler manifestations.

Three patients with portal venous gas (one with radiographic and computed tomographic findings) had similar sonographic and Doppler patterns in the portal vein (PV). These patterns consisted of hyperechogenic foci moving within the lumen of the PV, producing sharp bidirectional spikes superimposed on the usual Doppler tracing of the PV. An injection of 0.25-0.50 cm3 of air, oxygen, nitrogen, and carbon dioxide into the jejunal vein of nine dogs yielded identical portal venous sonographic and Doppler patterns. In addition, the liver parenchyma of the dogs became hyperechogenic after the injection of gas. Gas in the PV is accompanied by the following signs: echogenic, moving foci within the lumen of the PV; sharp spikes on Doppler spectral display; and hyperechogenic foci within the liver parenchyma.

Adult↗
PubMed1991

Segmental anatomy of the liver: a sonographic approach to the Couinaud nomenclature.

The authors developed a simplified description of the segmental anatomy of the liver on the basis of the Couinaud nomenclature. This approach was demonstrated with normal in vivo sonographic images and livers dissected in corresponding planes. The branches of the portal vein, which lead to the center of individual segments, are used as key landmarks in the determination of segmental location. The hepatic veins, ligaments, fissures, and gallbladder are used as external boundaries of the segments.

Adolescent↗
PubMed1991

[Transcranial Doppler ultrasound].

Over the last decade, transcranial Doppler examination of the cerebral vessels has been made possible by the development of a high-intensity, low-frequency (2 MHz) pulse probe. The middle, the anterior and the posterior cerebral arteries, the cavernous portion of the carotid artery and the basilar artery can thus be easily studied transtemporally or transorbitally or from below the foramen magnum. The transcranial Doppler examination is already used clinically to study arteriosclerosis and in the diagnosis and follow-up of vasospasm and arteriovenous malformations. This review describes the examination procedure and summarizes and illustrates its major indications.

Basilar Artery↗
PubMed1990

Ureterovesical jets in infants and children: duplex and color Doppler US studies.

Ureteric jets were studied with conventional duplex Doppler (79 patients) and with color Doppler flow imaging (22 patients). Correlation with voiding cystourethrography (VCUG), performed ont he same day, was obtained in all patients. Thirty-six patients with normal VCUG results and normal renal and bladder ultrasound (US) studies served as the control group for 39 patients with vesicoureteric reflux (VUR) and 26 patients with urinary tract disorders other than reflux. The site of the ureteric orifice and duration, direction, and turbulence of the jets were recorded. Duration varied from 0.4 sec to 7.5 sec and depended largely on fluid intake. Duration varied in an individual patient by up to 2 sec from one jet to another. The direction of the normal jet was anteromedial and upward. Jets from refluxing ureters can appear normal. Severe renal parenchymal scarring reduced frequency and amplitude of the jets. Doppler analysis of the ureteric jet does not allow diagnosis or exclusion of VUR. Color Doppler was more sensitive in demonstrating ureteric jets than was gray-scale, real-time US and facilitated the study, but it was equally unable to help predict reflux.

Adolescent↗
PubMed1990

Fetal lobation. An anatomo-ultrasonographic correlation.

Remnants of the fusion of fetal renunculi have been mistaken for renal scars or tumors. We compared anatomic cuts of 24 cadaveric kidneys with fetal lobation (ages ranged from 16 weeks gestation to 49 years) to identical ultrasonographic sections performed in a water bath and to sonograms of healthy persons of similar ages as the cadavers. Fetal lobation was characterized as follows: there were fine, linear demarcations indenting the renal surface, separating normal lobes, consisting of a central pyramid and surrounding cortex. Separate renunculi seen in early fetal life progressively fuse throughout gestation, leaving interlobar grooves. During the third trimester, the renal surface becomes smoother and the interlobar grooves become invisible. One prominent indentation of the renal surface, the interrenuncular junction, incorporates perirenal fat and invaginates the anterior surface of the upper third of the kidney to the hilum and is the most easily visible remnant of fetal lobation. The sharply defined linear remnants of interlobar grooves should not be mistaken for scars, which are wider, less well defined and always associated with loss of renal cortex.

Adolescent↗
PubMed1989

[Doppler ultrasound and portal hypertension: quantitative analysis].

Usually, the clinical evaluation of diffuse hepatic changes only needs the answers to three important questions: is there a flow, in which direction and are the porto-caval shunts efficient? When an answer is found to these questions, the quantitative measurement of the portal flow can give complementary precisions to achieve a better physiopathological understanding of portal hypertension or blood malignancies and for the follow-up evaluation.

Adult↗