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Biomedical subjects

N Grenier

Publications and source records attributed to N Grenier.

107 records · Page 6Linked to original sources
PubMed1986

[Intra-abdominal pseudotumorous panniculitis. CAT scan aspects of a case localized in the greater omentum].

Intra-abdominal panniculitis is an inflammatory and necrotic reaction to local, general or undetermined aggressions to intra- or retro-peritoneal fatty tissue. A case localized to the greater omentum is described and findings on CT scan imaging reported: encapsulated, heterogeneous mass of fatty density with fibrous bands and with fascial thickenings. Diagnosis is based mainly on histopathology, the CT scan being incapable, despite the clinical context, of formally rejecting a diagnosis of liposarcoma.

Adipose Tissue↗
PubMed1984

[Computed x-ray tomography of abdominal lipoma and liposarcoma in adults. Apropos of 9 cases].

CT scans were performed in 9 patients with fatty tumors of the abdomen: 2 lipomas and 7 liposarcoma. Of primary retroperitoneal origin, five tumors had extended intraperitoneally. Scanning images typical for each type of tumor are described: lipomas are very hypodense and well circumscribed, with thin intratumoral septa; liposarcomas are less hypodense and contain thick septa which may coalesce and form large nodules. Scanner imaging provides precise data on tumor extension and allows early detection of recurrences of these fatty tumors.

Abdominal Neoplasms↗
PubMed1983

Anatomy of the lumbar radicular canal.

The radicular canal is defined as the lateral part of the spinal canal containing the spinal nerve root from its point of emergence through the dural envelope up to and including the intervertebral foramen. The radicular canal, resembling a hollow hemicylinder opened towards the midline, can be divided into three parts, i.e. retrodiscal, parapedicular (the lateral recess per se) and foraminal. The different walls of the canal (notably those of the lateral recess) are described. A review of the main types of roentgenographic exploration of the radicular canal are presented based on these anatomical findings. Finally, this static description of the typical lumbar radicular canal and its variations according to the lumbar or sacral level under consideration is followed by a presentation of the modifications which arise in the upright position and during extension and flexion of the lumbar spine.

Humans↗
PubMedDate not supplied

First-pass evaluation of renal perfusion with TurboFLASH MR imaging and superparamagnetic iron oxide particles.

First-pass intrarenal hemodynamics were studied with superparamagnetic iron oxide particles and a T2-weighted TurboFLASH (fast low-angle shot) magnetic resonance (MR) imaging sequence. Four groups of five rabbits each were imaged after bolus injection of 40, 100, 140, and 200 mumol/kg iron, respectively. Images were acquired every 1.2 seconds, with an acquisition time of 700 msec. The signal intensity was measured in the cortex, outer medulla, inner medulla, and globally. In preliminary pathologic applications, two rabbits were imaged after ligation of the lumbar ureter and two after embolization of the renal artery. The reproducibility of the normal dynamics was evaluated with a cross-correlation test. On the images, the intravascular progression of the iron particles could be visualized within the cortex and the two compartments of the medulla in all cases. The maximal reduction in signal intensity in the cortex and medulla increased with the dose. The relationship between signal intensity decrease and dose was not linear, and the reproducibility of the signal intensity versus time plots was acceptable only at the 140 and 200 mumol/kg doses. The decrease in signal intensity was reduced and delayed in the embolized and hydronephrotic kidneys.

Animals↗
PubMedDate not supplied

Gd-DOTA tubular transit asymmetry induced by angiotensin-converting enzyme inhibitor in experimental renovascular hypertension.

In stenosis of a renal artery, angiotensin-converting enzyme inhibitor (ACEI) can induce a decrease in ipsilateral glomerular filtration. Dynamic MR imaging with gadolinium chelate enhancement was tested to detect this glomerular filtration reduction in experimental renovascular hypertension in the rat. Thirteen rats, with surgically induced left renal artery stenosis, developed hypertension and were studied before and after intravenous injection of ACEI with sequential Gd-DOTA-enhanced MR imaging. The time to onset of the tubular phase, the time of the maximal drop of signal, and the medullary signal-time curves of both kidneys were compared. Before ACEI, tubular phases were symmetric in 11 rats and slightly asymmetric in 2. Twelve rats showed ACEI-induced changes (positive test): absence of tubular phase on the left side (n = 8) or delay (n = 4) with significant differences (P < .01). Tubular phases remained symmetric in one (negative test). Dynamic MR imaging can identify ACEI-induced Gd-DOTA tubular transit asymmetry, indicative of functionally significant renal artery stenoses, in rats.

Angiotensin-Converting Enzyme Inhibitors↗
PubMedDate not supplied

External iliac vein stenosis after segmental pancreatic transplantation: treatment by percutaneous endoprosthesis.

A stenosis of the iliac vein secondary to a fluid collection in a pancreas transplant was identified by color Doppler flow sonography. The pancreatic venous drainage was reversed to the contralateral iliac veins via venous collaterals. After two unsuccessful angioplasties of the vein stenosis, a Wallstent was positioned above the venous anastomosis, and has remained patent for 8 months. The pancreatic venous drainage became normal after the procedure.

Constriction, Pathologic↗
PubMedDate not supplied

Functional MRI of the kidney.

Functional MR imaging of the kidney has a great potential of development because the functional parameters, which can be approached noninvasively, are multiple: glomerular filtration, tubular concentration and transit, blood volume and perfusion, diffusion, and oxygenation. Until now, its limitations in clinical applications are due to the difficulties in obtaining reproducible and reliable information in this mobile organ and, sometimes, in understanding the physiologic substrate of the signal changes observed. These approaches require either endogeneous contrast agents, such as water protons (for perfusion and diffusion) or deoxyhemogobin (for oxgenation), or exogeneous contrast agents such as gadolinium chelates (for filtration and perfusion) or iron oxide particles (for perfusion). Clinical validation of these methods and evaluation of their clinical impact are now worthwhile before diffusing them in clinical practice.

Contrast Media↗
PubMedDate not supplied

MR imaging of nephropathies.

Acute and chronic nephropathies are responsible for morphologic and functional renal changes. However, radiologic techniques currently play a minor role in imaging of parenchymal nephropathies in native or transplanted kidneys. From a morphologic point of view, three-dimensional magnetic resonance (MR) volumetric biomarkers of kidney function, such as renal and cortical volumes or cystic volume, in polycystic kidney diseases play a growing role in nephrologic practice. From a functional point of view, if scintigraphic techniques remain the major sources of renal performance assessment, new MR imaging systems and specific MR contrast agents may soon provide significant developments in the evaluation of renal performance (glomerular filtration rate measurement), in the search for prognostic factors (hypoxia, inflammation, cell viability, degree of tubular function, and interstitial fibrosis), and for monitoring new cell therapies. New developments that have provided higher signal-to-noise ratio and higher spatial and/or temporal resolutions have the potential to direct new opportunities for obtaining morphologic and functional information on tissue characteristics that are relevant for various renal diseases with respect to diagnosis, prognosis, and treatment follow-up.

Humans↗
PubMedDate not supplied

MR imaging of foraminal and extraforaminal lumbar disk herniations.

Foraminal and extraforaminal disk herniations are less frequent than intraspinal herniations at the lumbar level and more difficult to diagnose. They are undetected by myelography and distinction between them and an enlarged nerve root may be difficult with CT. Thirty-three patients presenting with persistent radiculopathy and showing an image suggesting a far lateral disk herniation on CT at 34 disk levels were prospectively imaged with magnetic resonance (MR). In all cases the disk fragment was identified and its separation from the nerve root was possible. This separation was more readily visible on sagittal or angled coronal views. The exact location of the herniation in relation to the facet joints and the pedicles was best assessed with MR: Ten were purely intraforaminal, 8 extraforaminal, and 15 both. Cephalad migration was noted on the sagittal lateral facet plane in 71% of cases. Surgical correlations were available for 25 disks. Three were falsely positive for disk herniation. Enlarged foraminal veins were responsible for this appearance as confirmed by surgery in two of these. When a prediction of disruption of the lateral extension of the posterior longitudinal ligament was made, it was confirmed at surgery in 52% of cases because of extreme lateralization of the herniations.

Adult↗
PubMedDate not supplied

[Thoracic sarcoidosis with pulmonary cavitation. Apropos of a case].

The authors report an unusual case of thoracic sarcoidosis in a 21 years-old man who presents pulmonary nodules turning to cavitation. This observations and the few similar cases of the literature are analysed regarding to their clinical and radiological sequential patterns.

Adult↗
PubMedDate not supplied

[Conservative treatment of hepatic injuries. Management and course].

From January 1986 to June 1994, 252 cases of closed liver trauma were treated in an emergency setting. Non surgical conservative management, after a complete imaging work-up including CT scan in all cases, was applied in 142 cases (56.3%) with no hemodynamic complication. The spontaneous outcome in these cases was quite favourable in 131 (92.2%); all lesions had disappeared in 4 to 36 weeks. Complications were observed in only 6 cases: 2 intrahepatic abscesses managed with percutaneous drainage were not further complicated, 1 biliari fistula required surgical exploration, 1 intrahepatic bilioma was drained percutaneously, 1 disinsertion of the gallbladder was treated by laparoscopy and 1 operation for bleeding was required 48 hours after the trauma in 1 case. No deaths could be directly imputed to the liver trauma, 5 patients died from neurological causes. Non-surgical conservative treatment combined with strict prolonged surveillance is a reliable management option for patients with closed liver trauma.

Adolescent↗
PubMedDate not supplied

[Arterial and biliary complications of hepatic transplantation].

Despite progress in standardization of reconstruction procedures, arterial and biliary complications remain an important problem in liver transplantation. These complications directly affect graft survival and patient mortality. We review a series of 165 consecutive orthoptic liver transplantations performed in 146 patients including 3 children. Biliary reconstruction included bilio-biliary termino-terminal anastomosis in 88% of the cases and bilio-digestive choledoco-jejunal anastomosis in 12%. Biliary complications occurred in 15% (25/165) with more obstruction (64%, 16/25) than leakages (64%, 7/25); 28% (7/25) of these complications were related to biliary drainage (3 obstructions and 4 leakages). There were no arterial complications in the 7 patients with non-anastomotic biliary stenosis. The rate of arterial complications was 11%; with 8 stenoses, 5 thrombosis and 5 pseudoaneurysms. Among the 18 transplantations with an arterial complication, 7 (39%) also had a biliary complication. Among the 10 patients with a complete interruption of arterial blood flow (thrombosis or surgical ligature or a ruptured pseudo-aneurysm), 5 (50%) also had a biliary complication, 1 underwent early retransplantation and 2 died early. In conclusion, the biliary tree of the graft are particularly susceptible to interrupted arterial flow. Ischaemic biliary lesions predominate in the intra-hepatic biliary ducts. Biliary drainage is important.

Adolescent↗