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Overlapping ablation using a coaxial radiofrequency electrode and multiple cannulae system: experimental study in ex-vivo bovine liver.

Choi D, Lim HK, Kim MJ, Lee J, Kim SK, Kim EY, Kim S, Kim SH - Korean J Radiol (2003 Apr-Jun)

Bottom Line: The long-axis (diagonal) and short-axis lengths on a transverse section of four-ablation zones (cakes) ranged from 8.5 to 9.7 (mean, 9.1) cm and from 3.0 to 4.1 (mean, 3.7) cm, respectively.Gross pathologic examination of three composite six-ablation zones (spheres) showed that the long-axis (diagonal) and short-axis lengths of zones ranged from 9.0 to 9.9 (mean, 9.4) cm and from 6.8 to 7.5 (mean, 7.2) cm, respectively.Using a coaxial RF electrode and multiple cannulae, together with ultrasound guidance and precise overlapping ablation techniques, we successfully created predictable thermal zones in ex-vivo bovine liver.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Kangbuk Samsung Hospital, Seoul, Korea.

ABSTRACT

Objective: To assess the sizes and configurations of thermal zones after overlapping ablations using a coaxial radiofrequency (RF) electrode and multiple cannulae in ex-vivo bovine liver.

Materials and methods: For ablation procedures, a coaxial RF electrode and introducer set was used. Employing real-time ultrasound guidance and overlapping techniques in explanted, fresh bovine liver, we created five kinds of thermal zones with one (n=10), two (n=8), four (n=3), and six ablation spheres (n=3). Following ablation, MR images were obtained and the dimensions of all thermal zones were measured on the longitudinal or transverse section of specimens. The shape of the composite ablation zones was evaluated using three-dimensional MR image reconstruction.

Results: At gross pathologic examination of ten single-ablation zones (spheres), the long-axis (transverse) and short-axis lengths of zones ranged from 3.7 to 4.4 (mean, 4.1) cm and from 3.5 to 4.0 (mean, 3.7) cm, respectively. The long-axis (transverse) and short-axis lengths of double-ablation zones (cylinders) with 23% overlap ranged from 7.0 to 7.7 (mean, 7.3) cm and from 3.0 to 3.9 (mean, 3.5) cm, respectively; those with 58% overlap ranged from 6.0 to 6.4 (mean, 6.2) cm and from 3.8 to 4.6 (mean, 4.3) cm, respectively. The long-axis (diagonal) and short-axis lengths on a transverse section of four-ablation zones (cakes) ranged from 8.5 to 9.7 (mean, 9.1) cm and from 3.0 to 4.1 (mean, 3.7) cm, respectively. Gross pathologic examination of three composite six-ablation zones (spheres) showed that the long-axis (diagonal) and short-axis lengths of zones ranged from 9.0 to 9.9 (mean, 9.4) cm and from 6.8 to 7.5 (mean, 7.2) cm, respectively. T2-weighted MR images depicted low-signal thermal zones containing multiple curvilinear and spotty regions of hyperintensity.

Conclusion: Using a coaxial RF electrode and multiple cannulae, together with ultrasound guidance and precise overlapping ablation techniques, we successfully created predictable thermal zones in ex-vivo bovine liver.

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Related in: MedlinePlus

A double-ablation zone created by overlapping ablation spheres by 23% of their diameter (interval between electrode tips: 3.2 cm).A. Photograph of longitudinal section of the specimen shows an ablation zone with a fissure (curved arrow) measuring 7.4 cm transversely and 4.0 cm longitudinally. It is delimited by three concentric areas: a pale central core, middle hemorrhagic or red rim (arrowhead), and an outer pink rim (arrow) of variable thickness that merges with normal liver.B. T2-weighted FSE (TR 3084/TE 104) coronal image depicts a low-signal zone (arrows).C. Three-dimensional ablation zone reconstructed from MR images appears as a composite ellipsoid with no definite fissure.
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Figure 4: A double-ablation zone created by overlapping ablation spheres by 23% of their diameter (interval between electrode tips: 3.2 cm).A. Photograph of longitudinal section of the specimen shows an ablation zone with a fissure (curved arrow) measuring 7.4 cm transversely and 4.0 cm longitudinally. It is delimited by three concentric areas: a pale central core, middle hemorrhagic or red rim (arrowhead), and an outer pink rim (arrow) of variable thickness that merges with normal liver.B. T2-weighted FSE (TR 3084/TE 104) coronal image depicts a low-signal zone (arrows).C. Three-dimensional ablation zone reconstructed from MR images appears as a composite ellipsoid with no definite fissure.

Mentions: Eight thermal ablation zones (cylinders) with two ablations each were created by overlapping ablation spheres by 23% and 58% of their diameter. Two different kinds of double-ablation zone were designed for the largest composite ablation zone model and cylindrical model, respectively (6). The intervals between electrode tips were 3.2 cm (23% overlap of single-ablation zones 4.1 cm in diameter) and 1.7 cm (58% overlap of single-ablation zones). The gross pathologic findings showed that the long-axis (transverse) lengths of double-ablation zones with 23% overlap ranged from 7.0 to 7.7 cm (mean, 7.3 cm; SD, 0.31 cm), and those with 58% overlap, from 6.0 to 6.4 cm (mean, 6.2 cm; SD, 0.17 cm). The short-axis (longitudinal) lengths of double-ablation zones with 23% overlap ranged from 3.0 to 3.9 cm (mean, 3.5 cm; SD, 0.23 cm) (fissure area), and those with 58% overlap, from 3.8 to 4.6 cm (mean, 4.3 cm; SD, 0.16 cm) (Figs. 4, 5). At MR imaging, the volumes of double-ablation zones with 23% overlap ranged from 60.3 to 76.4 cm3 (mean, 68.1 cm3; SD, 6.6 cm3) and those with 58% overlap, from 52.4 to 68.9 cm3 (mean, 60.2 cm3; SD, 6.8 cm3). Double-ablation zones with 58% overlap were more spherical (elliptical) than those with 23% overlap, and in the latter, fissures were evident (Fig. 4A).


Overlapping ablation using a coaxial radiofrequency electrode and multiple cannulae system: experimental study in ex-vivo bovine liver.

Choi D, Lim HK, Kim MJ, Lee J, Kim SK, Kim EY, Kim S, Kim SH - Korean J Radiol (2003 Apr-Jun)

A double-ablation zone created by overlapping ablation spheres by 23% of their diameter (interval between electrode tips: 3.2 cm).A. Photograph of longitudinal section of the specimen shows an ablation zone with a fissure (curved arrow) measuring 7.4 cm transversely and 4.0 cm longitudinally. It is delimited by three concentric areas: a pale central core, middle hemorrhagic or red rim (arrowhead), and an outer pink rim (arrow) of variable thickness that merges with normal liver.B. T2-weighted FSE (TR 3084/TE 104) coronal image depicts a low-signal zone (arrows).C. Three-dimensional ablation zone reconstructed from MR images appears as a composite ellipsoid with no definite fissure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2698069&req=5

Figure 4: A double-ablation zone created by overlapping ablation spheres by 23% of their diameter (interval between electrode tips: 3.2 cm).A. Photograph of longitudinal section of the specimen shows an ablation zone with a fissure (curved arrow) measuring 7.4 cm transversely and 4.0 cm longitudinally. It is delimited by three concentric areas: a pale central core, middle hemorrhagic or red rim (arrowhead), and an outer pink rim (arrow) of variable thickness that merges with normal liver.B. T2-weighted FSE (TR 3084/TE 104) coronal image depicts a low-signal zone (arrows).C. Three-dimensional ablation zone reconstructed from MR images appears as a composite ellipsoid with no definite fissure.
Mentions: Eight thermal ablation zones (cylinders) with two ablations each were created by overlapping ablation spheres by 23% and 58% of their diameter. Two different kinds of double-ablation zone were designed for the largest composite ablation zone model and cylindrical model, respectively (6). The intervals between electrode tips were 3.2 cm (23% overlap of single-ablation zones 4.1 cm in diameter) and 1.7 cm (58% overlap of single-ablation zones). The gross pathologic findings showed that the long-axis (transverse) lengths of double-ablation zones with 23% overlap ranged from 7.0 to 7.7 cm (mean, 7.3 cm; SD, 0.31 cm), and those with 58% overlap, from 6.0 to 6.4 cm (mean, 6.2 cm; SD, 0.17 cm). The short-axis (longitudinal) lengths of double-ablation zones with 23% overlap ranged from 3.0 to 3.9 cm (mean, 3.5 cm; SD, 0.23 cm) (fissure area), and those with 58% overlap, from 3.8 to 4.6 cm (mean, 4.3 cm; SD, 0.16 cm) (Figs. 4, 5). At MR imaging, the volumes of double-ablation zones with 23% overlap ranged from 60.3 to 76.4 cm3 (mean, 68.1 cm3; SD, 6.6 cm3) and those with 58% overlap, from 52.4 to 68.9 cm3 (mean, 60.2 cm3; SD, 6.8 cm3). Double-ablation zones with 58% overlap were more spherical (elliptical) than those with 23% overlap, and in the latter, fissures were evident (Fig. 4A).

Bottom Line: The long-axis (diagonal) and short-axis lengths on a transverse section of four-ablation zones (cakes) ranged from 8.5 to 9.7 (mean, 9.1) cm and from 3.0 to 4.1 (mean, 3.7) cm, respectively.Gross pathologic examination of three composite six-ablation zones (spheres) showed that the long-axis (diagonal) and short-axis lengths of zones ranged from 9.0 to 9.9 (mean, 9.4) cm and from 6.8 to 7.5 (mean, 7.2) cm, respectively.Using a coaxial RF electrode and multiple cannulae, together with ultrasound guidance and precise overlapping ablation techniques, we successfully created predictable thermal zones in ex-vivo bovine liver.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Kangbuk Samsung Hospital, Seoul, Korea.

ABSTRACT

Objective: To assess the sizes and configurations of thermal zones after overlapping ablations using a coaxial radiofrequency (RF) electrode and multiple cannulae in ex-vivo bovine liver.

Materials and methods: For ablation procedures, a coaxial RF electrode and introducer set was used. Employing real-time ultrasound guidance and overlapping techniques in explanted, fresh bovine liver, we created five kinds of thermal zones with one (n=10), two (n=8), four (n=3), and six ablation spheres (n=3). Following ablation, MR images were obtained and the dimensions of all thermal zones were measured on the longitudinal or transverse section of specimens. The shape of the composite ablation zones was evaluated using three-dimensional MR image reconstruction.

Results: At gross pathologic examination of ten single-ablation zones (spheres), the long-axis (transverse) and short-axis lengths of zones ranged from 3.7 to 4.4 (mean, 4.1) cm and from 3.5 to 4.0 (mean, 3.7) cm, respectively. The long-axis (transverse) and short-axis lengths of double-ablation zones (cylinders) with 23% overlap ranged from 7.0 to 7.7 (mean, 7.3) cm and from 3.0 to 3.9 (mean, 3.5) cm, respectively; those with 58% overlap ranged from 6.0 to 6.4 (mean, 6.2) cm and from 3.8 to 4.6 (mean, 4.3) cm, respectively. The long-axis (diagonal) and short-axis lengths on a transverse section of four-ablation zones (cakes) ranged from 8.5 to 9.7 (mean, 9.1) cm and from 3.0 to 4.1 (mean, 3.7) cm, respectively. Gross pathologic examination of three composite six-ablation zones (spheres) showed that the long-axis (diagonal) and short-axis lengths of zones ranged from 9.0 to 9.9 (mean, 9.4) cm and from 6.8 to 7.5 (mean, 7.2) cm, respectively. T2-weighted MR images depicted low-signal thermal zones containing multiple curvilinear and spotty regions of hyperintensity.

Conclusion: Using a coaxial RF electrode and multiple cannulae, together with ultrasound guidance and precise overlapping ablation techniques, we successfully created predictable thermal zones in ex-vivo bovine liver.

Show MeSH
Related in: MedlinePlus