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ABSTRACT: Background:Radiofrequency ablation (RFA) has emerged as a potential alternative for surgery in clinical oncology. This animal experiment was conducted to evaluate the feasibility of RFA in the treatment of renal tumor.Methods:Eighteen rabbits with renal implantation of VX2 tumors were divided into two groups. Group A (n = 12) was treated with RFA by using a cooled-tip RF system at 30 W for 80 to 180 seconds. Group B (n = 6) received a sham operation. The therapeutic efficacy was evaluated by survival rate, magnetic resonance imaging (MRI), and histology.Results:All animals in group B died within 3 months after tumor implantation. Total tumor eradication was achieved in 10 of 12 rabbits (83.3%) in group A, of which 5 rabbits survived longer than 6 months (absolute eradication) and another 5 rabbits were found free of viable tumor when killed (relative eradication). Two rabbits experienced local tumor relapse, lung metastasis, or both. Six-month survival rate of RFA-treated rabbits was significantly higher (P < .01) than that of control rabbits. The typical MRI appearances of the acute RFA lesion consisted of five characteristic concentric zones, which corresponded to central needle track (zone A), tumor coagulation (zone B), renal tissue coagulation (zone C), peripheral hemorrhage (zone D), and inflammatory layer (zone E) on histology.Conclusions:RFA may become a promising therapy for the treatment of renal tumor. MRI is a useful modality for assessment of renal tumor ablation.
Annals of Surgical Oncology 04/2012; 8(8):651-657. · 4.17 Impact Factor
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Stefaan Mulier,
Yicheng Ni,
Lars Frich,
Fernando Burdio,
Alban L Denys,
Jean-François De Wispelaere,
Benoît Dupas,
Nagy Habib,
Michael Hoey,
Maarten C Jansen, [......], Yi Miao,
Peter Mulier,
Didier Mutter,
Kelvin K Ng,
Roberto Santambrogio,
Dirk Stippel,
Katsuyoshi Tamaki,
Thomas M van Gulik,
Guy Marchal,
Luc Michel
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ABSTRACT: Radiofrequency (RF) ablation is used to obtain local control of unresectable tumors in liver, kidney, prostate, and other organs. Accurate data on expected size and geometry of coagulation zones are essential for physicians to prevent collateral damage and local tumor recurrence. The aim of this study was to develop a standardized terminology to describe the size and geometry of these zones for experimental and clinical RF.
In a first step, the essential geometric parameters to accurately describe the coagulation zones and the spatial relationship between the coagulation zones and the electrodes were defined. In a second step, standard terms were assigned to each parameter.
The proposed terms for single-electrode RF ablation include axial diameter, front margin, coagulation center, maximal and minimal radius, maximal and minimal transverse diameter, ellipticity index, and regularity index. In addition a subjective description of the general shape and regularity is recommended.
Adoption of the proposed standardized description method may help to fill in the many gaps in our current knowledge of the size and geometry of RF coagulation zones.
Annals of Surgical Oncology 05/2007; 14(4):1381-96. · 4.17 Impact Factor
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Stefaan Mulier, Yi Miao,
Peter Mulier,
Benoit Dupas,
Philippe Pereira,
Thierry De Baere,
Riccardo Lencioni,
Raymond Leveillee,
Guy Marchal,
Luc Michel,
Yicheng Ni
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ABSTRACT: Research on technology for soft tissue radio frequency (RF) ablation is ever advancing. A recent proposal to standardize terminology of RF electrodes only deals with the most frequently used commercial electrodes. The aim of this study was to develop a logical, versatile, and unequivocal terminology to describe present and future RF electrodes and multiple electrode systems.
We have carried out a PubMed search for the period from January 1st 1990 to July 1st 2004 in seven languages and contacted the six major companies that produce commercial RF electrodes for use in the liver. In a first step, names have been defined for the five existing basic designs of single-shaft electrode. These names had to be unequivocal, descriptive of the electrode's main working principle and as short as possible. In a second step, these basic names have been used as building blocks to describe the single-shaft electrodes in combination designs. In a third step, using the same principles, a logical terminology has been developed for multiple electrode systems, defined as the combined use of more than one single-shaft RF electrode.
Five basic electrode designs were identified and defined: plain, cooled, expandable, wet, and bipolar electrodes. Combination designs included cooled-wet, expandable-wet, bipolar-wet, bipolar-cooled, bipolar-expandable, and bipolar-cooled-wet electrodes. Multiple electrode systems could be characterized by describing several features: the number of electrodes that were used (dual, triple, etc.), the electric mode (monopolar or bipolar), the activation mode (consecutive, simultaneous or switching), the site of the inserted electrodes (monofocal or multifocal), and the type of single-shaft electrodes that were used.
In this terminology, the naming ofthe basic electrode designs has been based on objective criteria. The short and unequivocal names of the basic designs can easily be combined to describe current and future combination electrodes. This terminology provides an exact and complete description of the versatile novel multiple electrode systems.
Advances in experimental medicine and biology 02/2006; 574:57-73. · 1.09 Impact Factor
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Stefaan Mulier, Yi Miao,
Peter Mulier,
Benoit Dupas,
Philippe Pereira,
Thierry de Baere,
Riccardo Lencioni,
Raymond Leveillee,
Guy Marchal,
Luc Michel,
Yicheng Ni
[show abstract]
[hide abstract]
ABSTRACT: Research on technology for soft tissue radiofrequency (RF) ablation is ever advancing. A recent proposal to standardise terminology of RF electrodes only deals with the most frequently used commercial electrodes. The aim of this study was to develop a logical, versatile and unequivocal terminology to describe present and future RF electrodes and multiple electrode systems. We have carried out a PubMed search for the period from January 1 1990 to July 1 2004 in seven languages and contacted the six major companies that produce commercial RF electrodes for use in clinic. In a first step, names have been defined for the five existing basic designs of single-shaft electrode. These names had to be unequivocal, descriptive of the electrode's main working principle and as short as possible. In a second step, these basic names have been used as building blocks to describe the single-shaft electrodes in combination designs. In a third step, using the same principles, a logical terminology has been developed for multiple electrode systems, defined as the combined use of more than one single-shaft RF electrode. Five basic electrode designs were identified and defined: plain, cooled, expandable, wet and bipolar electrodes. Combination designs included cooled-wet, expandable-wet, bipolar-wet, bipolar-cooled, bipolar-expandable and bipolar-cooled-wet electrodes. Multiple electrode systems could be characterised by describing several features: the number of electrodes that were used (dual, triple, ...), the electric mode (monopolar or bipolar), the activation mode (consecutive, simultaneous or switching), the site of the inserted electrodes (monofocal or multifocal), and the type of single shaft electrodes that were used. In this terminology, the naming of the basic electrode designs has been based on objective criteria. The short and unequivocal names of the basic designs can easily be combined to describe current and future combination electrodes. This terminology provides an exact and complete description of the versatile novel multiple electrode systems.
European Radiology 05/2005; 15(4):798-808. · 3.22 Impact Factor
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Academic Radiology 06/2002; 9 Suppl 1:S98-101. · 1.69 Impact Factor
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ABSTRACT: Magnetic Resonance Imaging (MRI) has proved to provide noninvasive methods to investigate the functional repercussion of myocardial infarction and to measure infarct size with specific contrast agents. In this study, we evaluate whether the combination of T2-weighted and contrast-enhanced T1-weighted MRI could detect and discern necrotic and ischemic, but salvageable, myocardium.
Reperfused myocardial infarction was surgically induced in 14 dogs. T1- and T2-weighted MRI was performed 6 hours after administration of the necrosis avid contrast agent Gadophrin-2 at 0.05 mmol/kg. Gradient-echo cine MRI series were performed at baseline and at 6 hours. Quantification of myocardial infarction was performed with triphenyltetrazolium chloride staining.
There was a strong correlation between of postcontrast T1-weighted MRI and histomorphometry (r2 = 0.98, P < 0.01). T2-weighted MRI overestimated the infarct size by 10.5% +/- 4.3% of left ventricular area. A good correlation was found between hyperintense areas on T2-weighted images and the percentage of dysfunctional areas on cine MRI (r2 = 0.84, P < 0.01). In regions with increased signal intensity on T2-weighted MRI, a decreased maximal systolic thickening (11.8% +/- 4.9%, P = 0.043) was found.
In this study, the difference between the hyperintense areas on T2-weighted and enhanced T1-weighted images after myocardial infarction likely represents viable myocardium.
Investigative Radiology 02/2002; 37(2):77-85. · 4.59 Impact Factor
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ABSTRACT: Ni Y, Adzamli K, Miao Y, et al. MRI contrast enhancement of necrosis by MP-2269 and gadophrin-2 in a rat model of liver infarction. Invest Radiol 2001;36:97-103.
rationale and objectives. The mechanisms of action leading to specific localization of necrosis-avid contrast agents (NACAs) such as gadophrin-2 are not well defined. It has been suggested recently that agents with a high degree of serum albumin binding may also serve as NACAs by virtue of nonspecific hydrophobic interactions. The present MRI-histomorphology correlation study was conducted to verify the likelihood of the proposed albumin-binding mechanism by comparing an albumin-binding blood pool agent, MP-2269, with gadophrin-2 in a rat model of reperfused liver infarction.
methods. Reperfused infarction in the right liver lobe was surgically induced in six rats. Serial T1-weighted MRI was performed before and after intravenous injection of MP-2269 at 0.05 mmol/kg and repeated in the same rats 24 hours later after intravenous injection of gadophrin-2 at the same dosage (0.05 mmol/kg). The MR images were matched with corresponding histomorphological findings. The signal intensity and contrast ratio of infarcted and normal hepatic lobes were quantified and compared between the two agents during the postcontrast course.
results. Before contrast, the infarcted lobe was indiscernible from normal liver on T1-weighted MRI. Shortly after injection of both MP-2269 and gadophrin-2, a negative contrast occurred between infarcted and normal liver because of a strong liver signal intensity enhancement and an inferior uptake in the necrotic liver. On delayed phase (>60 minutes), a necrosis-specific contrast enhancement (contrast ratio 1.6) developed with gadophrin-2 but not with MP-2269. The MR images matched well with corresponding histomorphological findings.
conclusions. Although both MP-2269 and gadophrin-2 feature an albumin-binding capacity, only gadophrin-2 displayed a persistent necrosis-specific contrast enhancement in the rat model of reperfused liver infarction. Therefore, the role of albumin binding in the mechanisms of NACAs should be reevaluated.
Investigative Radiology 01/2001; 36(2):97-103. · 4.59 Impact Factor
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ABSTRACT: The present comparative study was conducted to validate a newly developed "expandable-wet" electrode for an increased lesion
size of radiofrequency ablation (RFA) on excised beef liver. The expandable-wet electrode, which allows interstitial hypertonic
saline infusion through retractable curved needles, was compared with "expanded-dry" and "unexpanded-wet" electrodes for RFA
lesion size and other parameters. A total of 120 lesions were created under 50W (groups A–C) and 90W (groups A'–C') power
control mode for 10min at each ablation site with the following groups: group A and A' of expanded-dry electrode (needles
deployed but saline uninfused); group B and B' of unexpanded-wet electrode (saline infused but needle undeployed); and group
C and C' of expanded-wet electrode (needles deployed and saline infused). Together with lower impedance and higher power output,
the lesion size in group C (5.3±0.4cm) and C' (6.0±1.0cm) were significantly larger (P<0.01) than that in group A (3.3±0.3cm) and A' (2.0±0.2cm), and group B (3.8±1.0cm) and B' (2.6±0.4cm). The RFA lesion
size can be significantly enlarged when the expandable electrode is complemented with interstitial hypertonic saline infusion.
This design may improve the efficacy of RF tumor ablation.
European Radiology 01/2001; 11(9):1841-1847. · 3.22 Impact Factor
