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Biomedical subjects

P Otal

Publications and source records attributed to P Otal.

At least 37 records · Page 2Linked to original sources
PubMed2000

Rapid relaxation times measurements by MRI: an in vivo application to contrast agent modeling for muscle fiber types characterization.

This paper is a description of a simulation method to evaluate the contrast in NMR imaging and its aim is to help to optimize the use of contrast media in clinical imaging. Indeed, there is a need to define objective criteria in order to choose among several contrast media the ones that are the most effective and to define their optimal conditions of use, such as: the dose to be injected, the required time after injection to obtain the best enhancement and the optimal imaging sequence parameter values. The method is based on NMR signal simulation in the presence of contrast media and requires the fast measurement of the T1 and T2 relaxation times to obtain the dynamic relaxometry variation of tissues after contrast injection. In this work the fast imaging techniques that are to be described enable the measurement of T1 and T2 with a 30sec temporal resolution on 128*256 matrix images. The accuracy of the method was assessed in rabbit muscles after the injection of two gadolinium chelates (Gd-DTPA and Gd-DOTA) with the aim of improving the in vivo characterization of fast-twitch and slow-twitch muscle fiber types. The simulation results were in close agreement with contrast image analysis and showed, for relevant clinical doses, a small efficacy for both chelates. The interest of the proposed simulation method lies in the fact that it enables to objectively compare the efficacy of different contrast agents, to forecast the efficacy of a given contrast reagent and to define the optimal dose and the optimal imaging sequence parameters that give the best contrast. This simulation method obviates numerous prior experiments to evaluate the benefit expected from different contrast media. The method, which has been evaluated here for muscle investigations is applicable to any tissue analysis and can help to guide the best condition of use of contrast agents in MR imaging.

Animals↗
PubMed2000

Aortoduodenal fistula after endovascular stent-graft of an abdominal aortic aneurysm.

Despite satisfying short- and middle-term effectiveness and feasibility, endovascular stent-grafting for abdominal aortic aneurysm is still under evaluation. We report a case of an aortoduodenal fistula after the use of this technique. Enlargement of the upper aneurysmal neck was followed by caudal migration of the major portion of the stent-graft, which resulted in kinking of the device in the aneurysmal sac. Ulcerations were found on adjacent portions of both the aneurysmal sac and the adjacent duodenum. Only the textile portion of the prosthetic contralateral limb separated the aortic lumen from the corresponding duodenal lumen. Early detection of complications after stent-grafting is essential to allow successful treatment, either surgical or endoluminal.

Angioplasty↗
PubMed2000

Transjugular intrahepatic portosystemic shunts in the treatment of refractory ascites: results in 48 consecutive patients.

PURPOSE: To assess the efficacy, morbidity, and mortality involved in the creation of transjugular intrahepatic portosystemic shunts (TIPS) in the treatment of patients with refractory ascites in Child-Pugh classes B and C. MATERIALS AND METHODS: Forty-eight consecutive patients with refractory ascites were treated with TIPS creation in a tertiary care institution. They were followed for a median of 337 days (range, 3-1376 d). RESULTS: TIPS significantly decreased the portohepatic pressure gradient (20.7 +/- 5.9 mm Hg vs. 6.8 +/- 4.1 mm Hg; P < .0001). Seventy-three percent of patients had complete or partial response. One year after TIPS creation, survival was 73% in Child class B patients and 56% in Child class C patients. Thirteen patients experienced procedural complications (portal vein thrombosis, peritoneal bleeding, acute renal failure, pneumothorax, hemoptysis, spontaneous bacterial peritonitis, and heart failure) and TIPS creation was considered the cause of death in five patients (10.4%). Primary patency was 65% at 3 months and 23% at 1 year, but shunt obstruction was accessible for a second intervention. Ten patients (21%) had de novo encephalopathy after TIPS creation. CONCLUSIONS: This series suggests that TIPS is an effective treatment for refractory ascites; however, it is a challenging procedure and serious complications--usually renal and heart failure--can be seen. A careful selection of patients is mandatory.

Ascites↗
PubMed2000

Imaging and endovascular treatment of renal artery stenosis in the diabetic patient.

Although diabetes is a classical risk factor for macroangiopathy, the prevalence of renal artery stenosis (RAS) in this type of pathology has not been clearly determined. More than 50% of RAS occur in diabetic patients (almost exclusively Type 2), whereas autopsy findings and the few clinical surveys reported indicate that the percentage of RAS within the diabetic population is close to 30%. RAS occur especially in elderly subjects with Type 2 diabetes and multiple vascular involvement, and bilateral stenoses are frequent. Diagnostic imaging of RAS can cause adverse effects in the diabetic patient if iodinated contrast media are used, especially in cases of renal insufficiency. The presence of this risk factor requires that iodinated radiological explorations be performed with due caution, or that another product be substituted as a contrast agent (CO(2) or gadolinium), or that an imaging technique without iodine be used (colour Doppler ultrasound, magnetic resonance angiography). The therapeutic management of RAS in the diabetic patient differs little from that employed for other atheromatous stenoses of the renal artery. Endovascular treatment of RAS is the technique of choice for most patients, whether diabetic or not. The existence of diabetes has little effect on therapeutic strategy, except in cases of renal insufficiency when the risk of iodine overload should limit the doses of contrast medium or require the partial or even total substitution of another agent (CO(2), gadolinium). As in the case of other RAS, the indications depend on the lesion and the clinical presentation. Similarly, the results are both clinical and anatomical, and the existence of diabetes has a limited impact on these different parameters.

Angioplasty, Balloon↗
PubMed1999

Delayed treatment of traumatic rupture of the thoracic aorta with endoluminal covered stent.

BACKGROUND: Stent grafting is emerging as a new treatment for several pathological conditions involving the thoracic aorta. We studied the feasibility and safety of this technique for delayed treatment of ruptures of the aortic isthmus. METHODS AND RESULTS: Nine patients (14 to 76 years old; mean, 37 years; male/female ratio, 8/1) underwent stent grafting of the aortic isthmus in subacute (n=5) or chronic (n=4) aortic traumatic rupture after a motor accident. In subacute ruptures, this treatment was delayed (1 to 8 months; mean, 5.4 months) because of the severity of other associated injuries. Stent grafting was technically successful (defined as complete exclusion of the pseudoaneurysmal sac) in all patients. Short-term fever and biological inflammatory syndrome occurred in 3 patients. Two major complications occurred: in 1 patient, an early occlusion of the left subclavian artery was treated by placement of 2 Palmaz stents. In another patient, an atelectasis related to an increase of preexisting compression of the left main bronchus by the pseudoaneurysmal sac was successfully treated by temporary placement of an endobronchial silicone stent. Mean follow-up was 11.6 months (range, 3 to 21 months). Thrombosis of the pseudoaneurysmal sac was found in all patients. CONCLUSIONS: In the absence of available extended follow-up about the safety and effectiveness of endovascular grafting, this approach seems to be a viable therapeutic option for traumatic rupture of the aortic isthmus, but appropriately controlled prospective studies are needed before we can recommend its widespread use.

Accidents, Traffic↗
PubMed1999

Transjugular intrahepatic portosystemic shunt in the treatment of refractory bleeding from ruptured gastric varices.

The optimal management of ruptured gastric varices in patients with cirrhosis has not been codified yet. The present study reports the use of transjugular intrahepatic portosystemic shunt (TIPS) in patients with refractory gastric variceal bleeding. Thirty-two consecutive patients were included. All had been unresponsive to vasoactive agents infusion, sclerotherapy, and/or tamponade and were considered poor surgical candidates. They were followed-up until death, transplantation, or at least 1 year (median: 509 days; range 4 to 2,230). Hemostasis was achieved in 18 out of 20 patients actively bleeding at the time of the procedure. In the whole sample of 32 patients, rebleeding rates were 14%, 26%, and 31%, respectively at 1 month, 6 months, and 1 year. De novo encephalopathy was observed in 5 (16%) patients. Seven patients experienced complications and consequently 4 of these patients died. TIPS primary patency rates were 84%, 74%, and 51%, respectively, at 1 month, 6 months, and 1 year. For the same periods of time, survival rates were 75%, 62%, and 59%. These results suggest that TIPS can be used in cirrhotic patients with refractory gastric variceal bleeding and are effective in achieving hemostasis as well as in preventing rebleeding.

Actuarial Analysis↗
PubMed1999

Aortic stent grafting and side-branch embolization in an expanding chronic type B dissection.

OBJECTIVE: This is a report of endovascular treatment of a case of type B thoracoabdominal aortic dissection in a patient with progressive dyspnea, dorsolumbar pain, and expanding aortic diameter over a 1-year period. METHODS: Pretreatment imaging evaluation showed that the false lumen supplied only the celiac trunk. Endovascular treatment combined (1) embolization of the first segment of the celiac trunk to avoid distal back-flow into the false lumen and (2) stent grafting to occlude the initial entry tear. RESULTS: The treatment resulted in technical and clinical success. The patient remains asymptomatic 12 months after treatment. CONCLUSION: Stent grafting offers an interesting therapeutic alternative to exclude the initial entry tear in aortic dissection and may be combined with other endovascular procedures.

Aortic Dissection↗
PubMed1999

High occlusion rate in experimental transjugular intrahepatic portosystemic shunt created with a Dacron-covered nitinol stent.

PURPOSE: To assess whether the use of a prosthesis covered by a Dacron sheath might prevent pseudointimal hyperplasia in a transjugular intrahepatic portosystemic shunt (TIPS). MATERIALS AND METHODS: A TIPS procedure was performed in nine pigs, after creation of a portal vein microembolization model of portal hypertension, by using a Dacron-covered nitinol stent. The first centimeter on the lower extremity of this specially made prototype was uncovered, to avoid portal vein thrombosis. Three weeks later, the seven surviving animals underwent transjugular hemodynamic and angiographic follow-up and were then killed for gross and histologic evaluation. RESULTS: Shunt insertion was possible in all pigs; two died of complications of the procedure. After 3 weeks only two shunts were patent, although a 50%-60% narrowing of the initial portion of the shunt was present; the remaining shunts were occluded. Histologic examination showed pseudointimal hyperplasia associated, in the cases of occlusion, with a luminal thrombosis. CONCLUSION: This Dacron-covered stent did not prevent pseudointima formation over the stent and resulted in a high early occlusion rate, probably related to a pronounced tissue fibrotic response likely due to Dacron-induced inflammation.

Alloys↗
PubMed1999

[Diagnosis and endovascular treatment of thoracic aortic diseases].

Recent years have seen the emergence of non-invasive imaging techniques for the morphological assessment of the thoracic aorta. This evolution results in an important reduction of the role of diagnostic angiography. Simultaneously, thanks to a tremendous technologic development, endovascular treatment techniques concern nowadays some pathologic conditions of the descending aorta. A number of reports using a variety of devices have been published in the literature concerning the treatment of dissection and aortic aneurysm. Based on mid-term results, endoluminal repair with use of stent-grafts is a feasible and safe alternative to surgery with a low rate of morbidity and mortality. In type B dissections with end-organ involvement, interventional radiology can be used either to fenestrate the flap or to stent the flap in branch arteries. Proper selection of patients by non-invasive imaging is fundamental for successful endoluminal treatment. However, there is still major concern with respect to long term results of these new treatments.

Adult↗
PubMed1998

Endovascular stents in arterial injury after radiotherapy.

We evaluated preliminary success and patency of stenting for the treatment of radiation-induced arterial diseases. Thirteen stents were placed in 8 patients to treat occlusion (n = 3), aneurysm (n = 1), residual stenosis (n = 2), multiple stenoses (n = 1), and delayed restenosis after previous balloon angioplasty (n = 1). Interventional procedure was successfully performed in 8 patients for their arterial lesions after radiotherapy. Six patients underwent interventional procedure once or twice. Two patients underwent PTA 4 times. Five of these patients demonstrated primary patency with relief of clinical symptoms with a mean follow-up of 2 years (range: 8-60 months). Clinical improvement was noted in the other patients. Our results suggest that stent placement by single or multiple techniques may have immediate effect on arterial lesions caused by radiation and can be considered as a therapeutic option of choice in these cases.

Adult↗
PubMed1998

Endovascular retrieval of two migrated venous stents by means of balloon catheters.

The usefulness of vascular stenting was demonstrated in both arterial and venous applications to restore patency and improve suboptimal results after percutaneous transluminal angioplasty. Dislodgment of venous stents with an embolization into the right cavities or the pulmonary artery, however, is one of the most feared complications of this procedure. Percutaneous removal of these migrated stents is an appealing method of replacing more invasive operative intervention with cardiopulmonary bypass, which may be very hazardous in these often severely ill patients. We describe the cases of two patients with stents that migrated into the right ventricle and the pulmonary artery. In one patient, we were able to successfully remove these stents by using an angioplasty balloon with an operative extraction from the iliac vein, thereby obviating the need for a major operative procedure.

Adult↗
PubMed1998

Modular component separation and reperfusion of abdominal aortic aneurysm sac after endovascular repair of the abdominal aortic aneurysm: a case report.

Transluminal placement of a stent graft in patients with an abdominal aortic aneurysm is a new endovascular technique that offers a potentially less invasive and less risky alternative to open surgery. Complications after stent graft placement are not infrequent, but in most cases secondary endovascular intervention is successful. We describe a late major leak in the aneurysmal sac caused by a distal migration of the iliac limb of a bifurcated graft. This late complication was successfully treated by covered stent placement, excluding and thrombosing completely the reformed aneurysm.

Aged↗
PubMed1997

[Imaging of abdominal wall eventration: role and value of x-ray computed tomography].

The role of imaging in preoperative investigation of incisional hernia was studied in a series of 332 operated patients. CT scan (220 patients) remains the reference investigation. Magnetic resonance imaging (8 patients) does not provide any supplementary information at the present time. The classical features of median and lateral incisional hernia are described and the importance of evaluation of the elasticity and strength of the abdominal wall is stressed. In the authors' experience, this evaluation has implications for pre- and intraoperative strategy.

Abdominal Muscles↗