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  • 1
    Language: English
    In: Lasers in Surgery and Medicine, 2014, Vol.46(7), p.558(5)
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://onlinelibrary.wiley.com/doi/10.1002/lsm.22262/abstract Byline: Stefan Vallo, Katrin Eichler, Kathrin Kelly, Boris Schulz, Georg Bartsch, Axel Haferkamp, Thomas J Vogl, Stephan Zangos Purpose To evaluate the clinical value of different magnetic resonance imaging (MRI) sequences for a real-time thermo-monitoring during laser-induced thermotherapy (LITT) in kidneys. Methods Twenty-eight ex vivo pig kidneys were treated with laser ablation under MR guidance in a high-field MR scanner (Magnetom Espree or Avanto Fit, Siemens, Germany). For the thermal ablation of the kidney, a neodymium yttrium-aluminum-garnet (Nd:YAG) laser was used in combination with a special protective catheter (length 43cm, 4 French) which is sealed at the distal end. First, ablation was performed for 7, 10, and 13minutes using FLASH sequences for investigation of time-dependent growth of lesion size. In the second step, we evaluated the optimal imaging sequence during a 7minutes ablation of the kidney and after cooling using four different MR sequences (Haste, FLASH, radial VIBE, and Caipirinha DIXON). Results Macroscopic lesion volume increased from 3,784[+ or -]1,525mm.sub.3 to 7,683[+ or -]5,756mm.sub.3 after the ablation from 7 to 13minutes and MR volume ranged from 2,107[+ or -]1,674mm.sub.3 to 2,934[+ or -]1,549mm.sub.3 after the ablation from 7 to 13minutes. During ablation, FLASH (132[+ or -]34%) and radial VIBE (120[+ or -]43%) sequences displayed lesion volumes most efficiently with a trend to overestimation. The Caipirinha DIXON (323[+ or -]24%) sequence overestimated the volumes significantly during real-time monitoring. The volumes measured by MRI with FLASH (61[+ or -]30%), Haste (67[+ or -]28%), or radial VIBE (48[+ or -]14%) sequences after cooling of the kidney after ablation were always underestimated. The Caipirinha DIXON (142[+ or -]2%) sequence still overestimated the lesion volume after cooling of the kidney. Conclusion LITT is a feasible ablation modality in kidney tissue. Moreover, macroscopic and MR lesion volume increases time-dependently. For online monitoring, radial VIBE and FLASH sequences seem to be most efficient. Lasers Surg. Med. 46:558-562, 2014. [c] 2014 Wiley Periodicals, Inc. Article Note: Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.
    Keywords: Magnetic Alloys – Evaluation ; Magnetic Alloys – Comparative Analysis ; Rare Earth Metals – Evaluation ; Rare Earth Metals – Comparative Analysis ; Ablation (Surgery) – Comparative Analysis ; Rare Earth Metal Compounds – Evaluation ; Rare Earth Metal Compounds – Comparative Analysis ; Diagnostic Imaging – Comparative Analysis ; Lasers – Evaluation ; Lasers – Comparative Analysis
    ISSN: 0196-8092
    E-ISSN: 10969101
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  • 2
    In: BJU International, February 2016, Vol.117(2), pp.272-279
    Description: Byline: Atiqullah Aziz, Shahrokh F. Shariat, Florian Roghmann, Sabine Brookman-May, Christian G. Stief, Michael Rink, Felix K. Chun, Margit Fisch, Vladimir Novotny, Michael Froehner, Manfred P. Wirth, Marco J. Schnabel, Hans-Martin Fritsche, Maximilian Burger, Armin Pycha, Antonin Brisuda, Marko Babjuk, Stefan Vallo, Axel Haferkamp, Jan Roigas, Joachim Noldus, Regina Stredele, Bjorn Volkmer, Patrick J. Bastian, Evanguelos Xylinas, Matthias May Keywords: bladder cancer; radical cystectomy; mortality; nomograms; outcome Objective To externally validate the pT4a-specific risk model for cancer-specific survival (CSS) proposed by May etal. (Urol Oncol 2013; 31: 1141-1147) and to develop a new pT4a-specific nomogram predicting CSS in an international multicentre cohort of patients undergoing radical cystectomy (RC) for urothelial carcinoma of the bladder (UCB) Patients and Methods Data from 856 patients with pT4a UCB treated with RC at 21 centres in Europe and North-America were assessed. The risk model proposed by May etal., which includes female gender, presence of positive lymphovascular invasion (LVI) and lack of adjuvant chemotherapy administration as adverse predictors for CSS, was applied to our cohort. For the purpose of external validation, model discrimination was measured using the receiver-operating characteristic-derived area under the curve. A nomogram for predicting CSS in pT4a UCB after RC was developed after internal validation based on multivariable Cox proportional hazards regression analysis evaluating the impact of clinicopathological variables on CSS. Decision-curve analyses were applied to determine the net benefit derived from the two models. Results The estimated 5-year-CSS after RC was 34% in our cohort. The risk model devised by May etal. predicted individual 5-year-CSS with an accuracy of 60.1%. In multivariable Cox proportional hazards regression analysis, female gender (hazard ratio [HR] 1.45), LVI (HR 1.37), lymph node metastases (HR 2.54), positive soft tissue surgical margins (HR 1.39), neoadjuvant (HR 2.24) and lack of adjuvant chemotherapy (HR 1.67, all P 〈 0.05) were independent predictors of an adverse CSS rate and formed the features of our nomogram with a predictive accuracy of 67.1%. Decision-curve analyses showed higher net benefits for the use of the newly developed nomogram in our cohort over all thresholds. Conclusions The risk model devised by May etal. was validated with moderate discrimination and was outperformed by our newly developed pT4a-specific nomogram in the present study population. Our nomogram might be particularly suitable for postoperative patient counselling in the heterogeneous cohort of patients with pT4a UCB. Article Note: A.A. and S.F.S. contributed equally to the study.
    Keywords: Bladder Cancer ; Radical Cystectomy ; Mortality ; Nomograms ; Outcome
    ISSN: 1464-4096
    E-ISSN: 1464-410X
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  • 3
    In: BJU International, April 2006, Vol.97(4), pp.822-828
    Description: To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1464-410X.2006.06038.x Byline: AXEL HACKER, STEFAN VALLO, CHRISTEL WEISS (*), THOMAS STEIN ([dagger]), PETER ALKEN, THOMAS KNOLL, MAURICE STEPHAN MICHEL Keywords: surgical procedures; minimally invasive; carcinoma; electrodes; radiofrequency ablation Abstract: OBJECTIVE To investigate the technical characteristics of a newly developed device for bipolar and multipolar radiofrequency ablation (RFA) of kidney tissue with a resistance-controlled power output. MATERIALS AND METHODS The standardized model of the isolated perfused ex vivo porcine kidney was used. Two different applicators (20 and 30 mm active length) were selected for bipolar RFA, and one pair of applicators (2 x 30 mm active length) for multipolar RFA. RF energy was applied at different power levels (20, 30, 60 W) depending on the total active length of the electrodes. Treatment times were 1, 3, 5 and 9 min. The ablation cycles were recorded in continuous digital real-time and displayed on a monitor showing pre-set power, actual applied power, applied energy, tissue resistance, and impedance. Lesion sizes were measured macroscopically. A coagulation coefficient (coagulated tissue volume per applied energy unit) was calculated. RESULTS There was a dosage-effect relationship between the generator power/treatment time and the sizes of the lesions. With increasing treatment time, less tissue volume was coagulated per unit of applied energy. The actual applied energy was lower than that calculated theoretically. The resistance and impedance values for the 30-W applicator were lower than those of the 20-W applicator. CONCLUSIONS The technical features of this RFA device, with internally cooled bipolar and multipolar applicators and a resistance-controlled power output, represents an innovative improvement in RF technology. In vivo studies are needed to confirm the expected advantages and the suitability of this device for complete and reliable ablation of renal tumours. Author Affiliation: (*)Department of Biomathematics, University Hospital Mannheim, Ruprecht-Karls University of Heidelberg, and ([dagger])Celon AG Medical Instruments, Teltow, Germany Article History: Accepted for publication 31 October 2005 Article note: Axel Hacker, Department of Urology, University Hospital Mannheim, Theodor-Kutzer-Ufer 1-3 68135 Mannheim, Germany. e-mail: axel.haecker@chir.ma.uni-heidelberg.de
    Keywords: Surgical Procedures ; Minimally Invasive ; Carcinoma ; Electrodes ; Radiofrequency Ablation
    ISSN: 1464-4096
    E-ISSN: 1464-410X
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