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Biomedical subjects

A Gelet

Publications and source records attributed to A Gelet.

At least 19 recordsLinked to original sources
PubMed2006

Bloodless partial nephrectomy with a new high-intensity collimated ultrasonic coagulating applicator in the porcine model.

OBJECTIVES: To evaluate the long-term hemostatic efficacy of a new high-intensity collimated ultrasonic (HICU) applicator for open subhilar partial nephrectomy (PN) in the porcine model. METHODS: An applicator was designed with a planar 3.78-MHz HICU transducer and a reflector to optimize the delivery of acoustic energy to coagulate renal tissue. Six female pigs underwent right PN, followed at day 7 by left PN. The 6 pigs were killed on day 14. The treatment consisted of delivering HICU to a lower pole subhilar location, under a vascular clamp, then releasing the clamp, and cutting the kidney lower pole. The immediate and delayed hemostatic efficacy, treatment parameters, blood loss, complications, and renal function were evaluated at each surgical event and at necropsy. RESULTS: Perfect hemostasis was achieved with all 12 kidneys, with a mean treatment time of 7.2 minutes (range 5 to 9.2). The mean proportion of resected parenchyma was 21% (range 14% to 32%). No renal function impairment and no major complications were recorded. At necropsy, no secondary hematoma was observed, and three urinomas (25%) were found. CONCLUSIONS: Our HICU applicator has shown promising results during PN in the pig model with no other method of hemostasis. More studies are needed to refine our probe for laparoscopic surgery, improve its ergonomics, and extend our experiments to human laparoscopic nephron-sparing surgery.

Animals↗
PubMed2005

Elastography for the follow-up of high-intensity focused ultrasound prostate cancer treatment: initial comparison with MRI.

We previously developed an ultrasonic elastography imaging system that may provide a simple and cost-effective solution to monitor high-intensity focused ultrasound (HIFU) treatments. The objective of this clinical study was to evaluate the reliability of our system in assessing the volume of HIFU lesions in the prostate, using a comparison with magnetic resonance imaging (MRI). Elastograms were obtained in 20 patients after HIFU treatment for prostate cancer and gadolinium-enhanced T1- and T2-weighted MRI was performed. Lesion boundaries were manually outlined and the volume was calculated. A statistically significant correlation of rho = 0.62 (p = 0.022) was found between elastographic and MRI measurements of lesion volume, with elastographic measurements that generally underestimated the volume measured in MRI. Some basic physics (hypoechoic areas) and instrumentation (frame rate and band width) issues that were detrimental to image quality in vivo are reported, along with propositions to improve the technique. Because of these issues and, although good correspondence between elastographic and MRI measurements was found in some patients, elastographic measurements were unable to predict MRI measurements in a single individual. Nevertheless, the results confirmed the potential of elastography for monitoring HIFU treatment of the prostate. Further investigation will be conducted using better suited ultrasound equipment and performing real-time elastogram calculations.

Elasticity↗
PubMed2004

Principles and results of high-intensity focused ultrasound for localized prostate cancer.

Focused ultrasound holds promise in a large number of therapeutic applications. It has long been known that high-intensity focused ultrasound (HIFU) can kill tissue through coagulative necrosis. However, it is only in recent years that practical clinical applications are becoming possible, with the development of high-power ultrasound arrays and noninvasive monitoring methods. In the last decade, HIFU have been adapted and used to treat localized prostate cancer and it is now commercially available in Europe. In this article, preclinical studies and clinical development of prostate HIFU as well as early clinical results from our center and international studies are reviewed. Early results demonstrated that prostate HIFU is efficient to obtain local control for low- and intermediate-risk localized prostate cancer; however, long-term follow-up is still needed to estimate the efficacy of prostate HIFU in terms of specific cancer mortality. This makes HIFU a viable alternative in patients not candidate for radical therapy.

Humans↗
PubMed2003

Detection of bladder dysplasia using 5-aminolaevulinic acid-induced porphyrin fluorescence.

OBJECTIVE: To report results of a clinical investigation on the detection of bladder dysplasia and in situ carcinoma by using fluorescence induced by 5-aminolaevulinic acid (ALA). PATIENTS AND METHODS: The study included 50 patients with a primary bladder lesion, who had a bladder instillation of 50 mL of 3% ALA solution >or= 1 h before transurethral resection of the tumour. Random biopsies were taken using white-light cystoscopy, then using blue light to induce fluorescence; positive zones were noted and biopsied. The primary lesion was then resected. The frequency of dysplasia detected by ALA-induced fluorescence was evaluated, as was the risk of recurrence with a follow-up of >or= 2 years. RESULTS: In all patients the tumours were positive; in 21 fluorescence distant from the tumour was detected. The pathological report of the biopsies showed 11 cases of dysplasia, six of carcinoma in situ and four of inflammatory lesions. In 29 patients there was no fluorescence and quadrant biopsies were normal in all but three with moderate dysplasia. Within the minimum follow-up patients with bladder dysplasia detected by ALA-induced fluorescence had a higher risk of recurrence. CONCLUSION: ALA-induced fluorescence of the bladder significantly enhanced the detection of dysplasia and in situ carcinoma. However, this technique requires further investigation using well-characterized instrumentation and study protocols to determine any effect on treatment choice.

Aminolevulinic Acid↗
PubMed2001

[Retroperitoneal foreign body mimicking pararenal tumor].

We report the case of a 48 year-old woman presently with a pararenal tumor, with a history of pyelotomy in 1978 for the extraction of a renal pelvic stones. Results of surgery showed a foreign body. The clinical and diagnostic aspects of retained surgical gauze have been discussed and the need for radio-opaque markers in them have been emphasized.

Diagnosis, Differential↗
PubMed2001

[Recanalization of pelvic ureter in prostatic neoplastic obstruction: endoscopic and radiologic approach].

UNLABELLED: Obstruction of the lower ureter by pelvic cancer requires a palliative treatment. Percutaneous derivation is often performed as an emergency. If obstruction is limited to the peri-meatic area (a few mm or a cm) resection of the ureteral orifice can be enough to catheterize the obstructed ureter. Stenting of the ureter can be done even if the obstruction is longer, using the extra vesical repermeabilization. METHODS: A guide wire is passed via the nephrostomy, and ureteral stent is passed over the guide wire. Dye additionned with methylene blue is injected tovisualize the lower extremity of the ureter. A regular resectoscope is placed transuretraly, and resection is conducted using X ray localisation with a C arm and several incidences. The tissue resected first is usually extravesical, in the adipous perivesical tissue. Dissection of this area can be performed bluntly with the tip of the resectoscope until the ureter is reached. At this time, the resectoscope is used to open the lower extremity of the ureter, localized with the C arm. It is important to open widely the ureter, so as to be sure to catheterize easily this opening with a ureteral catheter. A double J can then be passed easily. Tunnel of several cm can be performed using this technique. RESULTS: Seven patients with pelvic cancer with obstruction of the last cm of the pelvic ureter were included in this series. They were recurrent prostate cancer already treated with hormone therapy, stage T3, T4. All procedures were performed under rachianesthesia or general anesthesia according to general status. After this procedure normal miction were obtain in all patients and nephrostomies were removed. This technique is possible for extended pelvic obstruction. Blunt dissection with the endoscope is usualy blood less. This palliative procedure can be done in patients with poor general condition and allows for a better quality of life than nephrostomy or urinary diversions.

Aged↗
PubMed2001

Transrectal high intensity focused ultrasound for the treatment of localized prostate cancer: factors influencing the outcome.

OBJECTIVES: Efficacy evaluation of high intensity focused ultrasound (HIFU) treatment for localized prostate cancer and identification of the factors affecting the outcome. PATIENTS AND METHODS: 102 patients with prostate cancer stage T1-T2 and noncandidates for radical prostatectomy have been treated with HIFU (Ablatherm, EDAP-Technomed). The disease progression (failure) was strictly defined by any positive sample at control biopsies, whatever the prostate-specific antigen (PSA) level, or by 3 consecutive increases in PSA levels in case of negative biopsies. RESULTS: At inclusion, patients' baseline characteristics were (mean +/- standard deviation): age 70.8 (+/-6.13) years, PSA 8.38 (+/-4.8) ng/ml, prostate volume 33.3 (+/-16.71) cm3. The population mean follow-up was 19 months (3-76 months). The overall success rate was 66%. Statistically significant variations of the overall success with a more favorable outcome were observed when (1) the initial PSA level was < or =10 ng/ml (73 vs. 50%, p = 0.02), (2) the Gleason score was < or =6 (81 vs. 46%, p<0.001) and (3) the pretreatment sextant biopsy evidenced 1-4 positive samples (68 vs. 40%, p = 0.01). CONCLUSION: Results observed after HIFU treatment in localized prostate cancer are now challenging those obtained after radiation therapy. The success rate is influenced by disease-related prognostic factors.

Aged↗
PubMed2001

MRI appearance of prostate following transrectal HIFU ablation of localized cancer.

OBJECTIVES: To evaluate the accuracy of gadolinium-enhanced MRI in gauging the extent of the tissue damage induced by transrectal high intensity focused ultrasound (HIFU) therapy and to assess how well the results obtained with this modality correlate with histological findings (control biopsies). METHODS: Twenty-one patients with biopsy-proven prostate cancer (T1-T2-T3a, Nx, M0) who gave informed consent were included in the protocol. They underwent pre- and postoperative (2-5 days after HIFU treatment) MR examinations. Fifteen patients also underwent a follow-up MR examination 1-5 months postoperatively. MR findings were compared with the results of postoperative transrectal biopsy examinations. RESULTS: The prostate volume increased after the HIFU session from 43.9+/-18.6 to 52.1+/-21 cm(3) by day 2 (p<0.001). On fat-saturated gadolinium-enhanced T1-weighted images, the treated area appeared as a hypointense zone surrounded by a peripheral rim of enhancement in all patients. A positive correlation (r = 0.75) was found between the volume of the hypointense zone measured at days 2-5 (30+/-11 cm(3), 67% of the posttreatment prostate volume) and the theoretical target volume (22+/-5 cm(3), 61% of the initial prostate volume). MRI showed that the anterior part of the base was not reached by the ultrasound beam. The mean volume of the untreated zone (prostate without any MRI modifications) was 8 cm(3) (range, 0.4-36). No correlation was found between the MRI appearance of the treated area and the intensity of the necrosis or the presence of foci of residual, viable cancer. CONCLUSION: Gadolinium-enhanced MRI is an accurate way of determining the extent of tissue damage induced in HIFU ablative therapy, but cannot predict histological results.

Aged↗
PubMed2001

[Emphysematous pyelonephritis: report of 3 cases].

Emphysematous pyelonephritis (EPN) is a rare form of renal suppuration defined by the presence of pus and gas or bacterial origin within the renal parenchyma. It is associated with a high mortality in the absence of rapid and effective treatment. Emergency nephrectomy constitutes the reference treatment. Percutaneous drainage associated with medical treatment is an alternative in patients with localized or bilateral lesions or in the case of solitary kidney. The authors report 3 cases of EPN treated by percutaneous drainage combined with medical treatment for a localized lesion in two cases and nephrectomy in one case of disseminated multilocular lesion with an uneventful course in all three cases.

Emphysema↗
PubMed2001

[Treatment of uretero-intestinal and uretero-vesical stenoses with the Acucise balloon catheter].

OBJECTIVE: Acucise balloon catheter has been proposed as an alternative to open surgery for the treatment of strictures of the ureteropelvic junction because of its low morbidity and the short hospital stay following the endoscopic procedure. The objective of this study was to evaluate the results of this technique applied to patients developing strictures after surgical reimplantation of the ureterovesical (UV) or uretero-intestinal (UI) junction. MATERIAL AND METHODS: Between March 1997 and January 2000, 12 strictures (11 patients) were treated by Acucise balloon catheter via an antegrade and/or retrograde approach with double J stenting for an average of 6 weeks (range: 4 to 12 weeks): 6 uretero-ileal strictures (3 Bricker, 1 uretero-ileoplasty, 1 enterocystoplasty and 1 Kock pouch) and 6 ureterovesical strictures (Lich-Grégoir or Faquin UV reimplantations after gynaecological, vascular or endoscopic surgery). The median postoperative follow-up was 16 months (range: 10 months-36 months). A good result was defined by the absence of recurrence of the stricture evaluated both clinically and radiologically (regression of stasis measured by IVU and/or ultrasonography). RESULTS: The mean operating time was 70 min and the mean hospital stay was 4.8 days (range: 3 and 14 days). Only one intraoperative complication was observed (migration of the double J stent to the kidney). The operation was successful in 8 patients (75%). The success rate was 83% for ureterovesical strictures and 50% for uretero-ileal strictures. A history of previous irradiation appeared to be a factor of failure. CONCLUSION: The Acucise procedure is a minimally invasive and effective (75% success rate) treatment option for the treatment of postoperative stricture after ureteric reimplantations. In our department, this option is considered to be first-line treatment, as surgical reimplantation is reserved for failures of the endoscopic technique.

Adult↗
PubMed2000

Transrectal high-intensity focused ultrasound: minimally invasive therapy of localized prostate cancer.

BACKGROUND AND PURPOSE: Criteria for determining the durability of the response to transrectal high-intensity focused ultrasound (HIFU) ablation of prostate cancer have been established by calculating progression-free probability. PATIENTS AND METHODS: A series of 82 patients (mean age 71 +/- 5.7 years) with biopsy-proven localized (stage T1-T2) cancer who were not suitable candidates for radical surgery underwent transfectal HIFU ablation with the Ablatherm machine. The mean follow-up was 17.6 months (range 3-68 months). The mean serum prostate specific antigen (PSA) value and mean prostate volume were 8.11 +/- 4.64 ng/mL and 34.9 +/- 17.4 cm3, respectively. Progression was rigidly defined as any positive biopsy result, regardless of PSA concentration, or three successive PSA increases for patients with a negative biopsy (PSA velocity > or = 0.75). Times to specific events (positive biopsy and PSA elevation) were analyzed with the Kaplan-Meier survival method. RESULTS: Overall, 62% of the patients exhibited no evidence of disease progression 60 months after transrectal HIFU ablation. In particular, the disease-free rate was 68% for the moderate-risk group of 50 patients (PSA < 15.0 ng/mL, Gleason sum < 8, prostate volume < 40 cm3, and number of positive biopsies < 5). For the low-risk group of 32 patients (PSA < 10 ng/mL and Gleason sum < 7), the disease-free survival rate was 83%. CONCLUSION: Transrectal HIFU prostate ablation is an effective therapeutic alternative for patients with localized prostatic adenocarcinoma.

Adenocarcinoma↗
PubMed2000

Modeling of high-intensity focused ultrasound-induced lesions in the presence of cavitation bubbles

The classical "Bio Heat Transfer Equation (BHTE)" model is adapted to take into account the effects of oscillating microbubbles that occur naturally in the tissue during high-intensity focused ultrasound (HIFU) treatment. First, the Gilmore-Akulichev model is used to quantify the acoustic pressure scattered by microbubbles submitted to HIFU. Because this scattered pressure is not monochromatic, the concept of harmonic attenuation is introduced and a global attenuation coefficient is estimated for bubble-filled tissues. The first results show that this global attenuation coefficient varies significantly with respect to several parameters such as the frequency and the density of microbubbles in the medium, but also with respect to the incident acoustic pressure which thus becomes a transcendental function. Under these conditions, a layer-by-layer modeling, in the direction of propagation, is proposed to calculate the ultrasonic beam. Finally, the BHTE is solved and the HIFU-induced lesions are estimated by the calculation of the thermal dose. Using this model, it can be observed first that, when the firing power increases, the lesion develops clearly in the direction of the transducer, with a shape agreeing with in vivo experimentation. Next, it is observed that the lesion can be significantly modified in size and position, if an interface (skin or inner wall) is simulated as a zone with multiple cavitation nuclei. With a firing power increase, it is also shown how a secondary lesion can appear at the interface and how, beyond a certain threshold, this lesion develops at the main lesion expense. Finally, a better in-depth homogeneity of lesions is observed when the acoustic frequency of HIFU is increased.

Journal Article↗
PubMed2000

Severe bleeding after nephrolithotomy: results of hyperselective embolization.

From 1984 to 1998, 808 patients underwent percutaneous nephrolithotomy for removal of renal calculi. Although the technique is safe and effective, complications, including hemorrhages, have been reported. Eight patients (1%) are described in whom severe bleeding following percutaneous nephrolithotomy was uncontrolled by usual methods and treated by hyperselective embolization. Renal arteriography has shown arteriovenous fistula in 3 patients, pseudo aneurysm in 4 and both in1 patient. Embolization allowed definitive treatment of these lesions in 7 of our 8 patients. The failure of embolization in 1 patient imposed a partial nephrectomy. Patients with normal renal function did not suffer significant change in the serum creatinine after treatment (percutaneous nephrolithotomy + embolization), and all but 1 patient have maintained normal blood pressure. In the authors' opinion, hyperselective embolization is the least invasive and best treatment for massive hemorrhage after percutaneous nephrolithotomy.

Adult↗
PubMed1999

Treatment of localised prostate cancer with transrectal high intensity focused ultrasound.

With the advent of PSA dosing, an increasing number of prostate cancers are being detected at a local stage. Since 1989, our group has been developing a research project with the aim of establishing treatment of localised prostate cancer by means of HIFU. The treatment is performed transrectally, using ultrasound imaging guidance only. The quality of HIFU treatment depends on four factors: the intensity of the transmitted pulse, the exposure time, the signal frequency, and the time between two firing bursts. The lesions are created by a thermal effect. Their slightly conical form is due to the absorption of ultrasound by tissue, enhanced by cavitation bubbles. Results obtained since 1993 demonstrate that transrectally administered HIFU treatment achieves local control of localised prostate cancer in 80% of cases, with 70% complete success and 30% partial response. The use of an annular array probe with variable focus and frequency should significantly improve results in the future. Finally, real time visual display of the damaged tissue via differential imaging of the attenuation coefficient should give the surgeon an instant appreciation of the result of the sequence. It would thus be possible to repeat treatment of insufficiently covered zones in the same session.

Absorption↗
PubMed1999

Ureteropelvic junction obstruction: use of helical CT for preoperative assessment--comparison with intraarterial angiography.

PURPOSE: To evaluate helical computed tomography (CT) in the preoperative assessment of crossing arteries in kidneys with ureteropelvic junction (UPJ) obstruction and to compare the results with those obtained by means of angiography. MATERIALS AND METHODS: Forty-one consecutive patients with symptomatic UPJ obstruction in 42 obstructed kidneys underwent renal helical CT and renal intraarterial digital subtraction angiography (DSA; flush aortography and bilateral selective renal injections). The helical CT and DSA images were interpreted in a blinded manner by two readers, and the results were compared. RESULTS: DSA showed 126 renal arteries in the 41 patients; 56% of patients had supernumerary renal arteries. Helical CT depicted 121 (96%) of these 126 renal arteries prospectively. Retrospectively, 124 (98%) renal arteries were visible on CT images. Twelve (29%) of the 42 kidneys with UPJ obstruction had identifiable arteries crossing the UPJ on DSA images. If DSA is used as the standard of reference, CT angiography was 100% sensitive and 96.6% specific for depicting these crossing arteries. CONCLUSION: Renal helical CT seems suitable to replace intraarterial DSA in the preoperative assessment of crossing arteries in kidneys with UPJ obstruction.

Adult↗
PubMed1999

Local control of prostate cancer by transrectal high intensity focused ultrasound therapy: preliminary results.

PURPOSE: We conducted a phase I/II study to evaluate the efficacy of transrectal high intensity focused ultrasound in the treatment of localized prostate cancer and to assess associated complications. The efficacy of a new high intensity ultrasound device was evaluated using post-treatment prostate specific antigen (PSA) levels and histological results from prostate biopsies as end points. MATERIALS AND METHODS: A total of 113 transrectal high intensity focused ultrasound sessions were performed in 50 patients with localized prostate cancer, who were not suitable candidates for radical prostatectomy. Of these patients 2 underwent salvage ultrasound treatment for locally recurrent cancer following definitive radiation therapy. Mean plus or minus standard deviation patient age, PSA and prostate volume were 70.7+/-4.54 years, 9.61+/-7.42 ng./ml. and 37.3+/-19.1 cc. The 2 different high intensity ultrasound prototypes were successfully used, and the latter prototype included several safety devices to reduce morbidity. Median followup was 24 months (range 3 to 46). Control parameters were changes in PSA and random control sextant biopsies at 1 to 3, 3 to 12, 12 to 24, 24 to 36 and 36 to 48 months. RESULTS: For the evaluation of therapy patients were divided into 4 groups. Group 1 (complete response) included 28 patients (56%) with no residual cancer and PSA less than 4 ng./ml. (mean 0.93), group 2 (biochemical failure) 3 patients (6%) with no residual cancer and PSA greater than 4 ng./ml. (mean 6.22), group 3 (biochemical control) 9 patients (18%) with residual cancer (mean positive biopsy 1.1 of 6) and PSA less than 4 ng./ml. (mean 0.90), and group 4 (failures) 10 patients (20%) with residual cancer (mean positive biopsies 1.9 of 6) and PSA greater than 4 ng./ml. (mean 8.9). Of the 10 cases in group 4 hormone therapy was required in 3 and radiotherapy in 5. Complication rate with the first prototype device was 50% and it decreased to 17% with the second prototype. CONCLUSIONS: Morbidity associated with high intensity focused ultrasound treatment is currently minimal. Local control of the localized prostate cancer was observed in groups 1, 2 and 3 (80%). Repeat sessions were deferred in groups 2 and 3 based on changes in PSA. These preliminary data suggest that high intensity focused ultrasound represents a valid alternative treatment strategy for patients with localized prostate cancer who are unsuitable for surgery.

Aged↗