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Quantifying Post- Laser Ablation Prostate Therapy Changes on MRI via a Domain-Specific Biomechanical Model: Preliminary Findings.

Toth R, Sperling D, Madabhushi A - PLoS ONE (2016)

Bottom Line: It combines the aggressive benefits of radiation treatment (destroying cancer cells) without the harmful side effects (due to its precise localization).Our results suggest that our new methodology is able to capture and quantify the degree of laser-induced changes to the prostate.The quantitative measurements reflecting of the deformation changes can be used to track treatment response over time.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America.

ABSTRACT
Focal laser ablation destroys cancerous cells via thermal destruction of tissue by a laser. Heat is absorbed, causing thermal necrosis of the target region. It combines the aggressive benefits of radiation treatment (destroying cancer cells) without the harmful side effects (due to its precise localization). MRI is typically used pre-treatment to determine the targeted area, and post-treatment to determine efficacy by detecting necrotic tissue, or tumor recurrence. However, no system exists to quantitatively evaluate the post-treatment effects on the morphology and structure via MRI. To quantify these changes, the pre- and post-treatment MR images must first be spatially aligned. The goal is to quantify (a) laser-induced shape-based changes, and (b) changes in MRI parameters post-treatment. The shape-based changes may be correlated with treatment efficacy, and the quantitative effects of laser treatment over time is currently poorly understood. This work attempts to model changes in gland morphology following laser treatment due to (1) patient alignment, (2) changes due to surrounding organs such as the bladder and rectum, and (3) changes due to the treatment itself. To isolate the treatment-induced shape-based changes, the changes from (1) and (2) are first modeled and removed using a finite element model (FEM). A FEM models the physical properties of tissue. The use of a physical biomechanical model is important since a stated goal of this work is to determine the physical shape-based changes to the prostate from the treatment, and therefore only physical real deformations are to be allowed. A second FEM is then used to isolate the physical, shape-based, treatment-induced changes. We applied and evaluated our model in capturing the laser induced changes to the prostate morphology on eight patients with 3.0 Tesla, T2-weighted MRI, acquired approximately six months following treatment. Our results suggest the laser treatment causes a decrease in prostate volume, which appears to manifest predominantly at the site of ablation. After spatially aligning the images, changes to MRI intensity values are clearly visible at the site of ablation. Our results suggest that our new methodology is able to capture and quantify the degree of laser-induced changes to the prostate. The quantitative measurements reflecting of the deformation changes can be used to track treatment response over time.

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Effect of physical parameters on the FEM used to compensate for the bladder/rectum motion.The X-axis represents the Young’s modulus (in log-scale). The Y-axis represents the Dice similarity coefficient between the pre-treatment, undeformed prostate () and the prostate after inducing, and then removing, a synthetic simulation of the bladder and rectum filling ().
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pone.0150016.g002: Effect of physical parameters on the FEM used to compensate for the bladder/rectum motion.The X-axis represents the Young’s modulus (in log-scale). The Y-axis represents the Dice similarity coefficient between the pre-treatment, undeformed prostate () and the prostate after inducing, and then removing, a synthetic simulation of the bladder and rectum filling ().

Mentions: An FEM model of the bladder and rectum was created for the pre-treatment image on one study IPre, and known forces at the surface were induced to generate a synthetic transformation . The forces were chosen to deform the pre-treatment bladder and rectum towards the post-treatment bladder and rectum for the same study. This yields a synthetic post-treatment . We denote as , the voxels contained within the prostate on the pre-treatment MRI scan. represents the synthetically deformed post-treatment voxels. The Dice similarity coefficient [24] between and was used to determine the accuracy of the inversion, where a Dice of 100% indicates . An analysis of the choice of Young’s modulus and its effects on the removal of the synthetic deformation is shown in Fig 2. The range of the log-scaled x-axis was from.3 kPa to 3000 kPa to highlight at what values of Young’s modulus, the accuracy significantly decreased. In the more typical biomechanical range of approximately 20-120 kPa, the resulting accuracy of the final Dice calculations were all greater than 92% in terms of accuracy.


Quantifying Post- Laser Ablation Prostate Therapy Changes on MRI via a Domain-Specific Biomechanical Model: Preliminary Findings.

Toth R, Sperling D, Madabhushi A - PLoS ONE (2016)

Effect of physical parameters on the FEM used to compensate for the bladder/rectum motion.The X-axis represents the Young’s modulus (in log-scale). The Y-axis represents the Dice similarity coefficient between the pre-treatment, undeformed prostate () and the prostate after inducing, and then removing, a synthetic simulation of the bladder and rectum filling ().
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835053&req=5

pone.0150016.g002: Effect of physical parameters on the FEM used to compensate for the bladder/rectum motion.The X-axis represents the Young’s modulus (in log-scale). The Y-axis represents the Dice similarity coefficient between the pre-treatment, undeformed prostate () and the prostate after inducing, and then removing, a synthetic simulation of the bladder and rectum filling ().
Mentions: An FEM model of the bladder and rectum was created for the pre-treatment image on one study IPre, and known forces at the surface were induced to generate a synthetic transformation . The forces were chosen to deform the pre-treatment bladder and rectum towards the post-treatment bladder and rectum for the same study. This yields a synthetic post-treatment . We denote as , the voxels contained within the prostate on the pre-treatment MRI scan. represents the synthetically deformed post-treatment voxels. The Dice similarity coefficient [24] between and was used to determine the accuracy of the inversion, where a Dice of 100% indicates . An analysis of the choice of Young’s modulus and its effects on the removal of the synthetic deformation is shown in Fig 2. The range of the log-scaled x-axis was from.3 kPa to 3000 kPa to highlight at what values of Young’s modulus, the accuracy significantly decreased. In the more typical biomechanical range of approximately 20-120 kPa, the resulting accuracy of the final Dice calculations were all greater than 92% in terms of accuracy.

Bottom Line: It combines the aggressive benefits of radiation treatment (destroying cancer cells) without the harmful side effects (due to its precise localization).Our results suggest that our new methodology is able to capture and quantify the degree of laser-induced changes to the prostate.The quantitative measurements reflecting of the deformation changes can be used to track treatment response over time.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America.

ABSTRACT
Focal laser ablation destroys cancerous cells via thermal destruction of tissue by a laser. Heat is absorbed, causing thermal necrosis of the target region. It combines the aggressive benefits of radiation treatment (destroying cancer cells) without the harmful side effects (due to its precise localization). MRI is typically used pre-treatment to determine the targeted area, and post-treatment to determine efficacy by detecting necrotic tissue, or tumor recurrence. However, no system exists to quantitatively evaluate the post-treatment effects on the morphology and structure via MRI. To quantify these changes, the pre- and post-treatment MR images must first be spatially aligned. The goal is to quantify (a) laser-induced shape-based changes, and (b) changes in MRI parameters post-treatment. The shape-based changes may be correlated with treatment efficacy, and the quantitative effects of laser treatment over time is currently poorly understood. This work attempts to model changes in gland morphology following laser treatment due to (1) patient alignment, (2) changes due to surrounding organs such as the bladder and rectum, and (3) changes due to the treatment itself. To isolate the treatment-induced shape-based changes, the changes from (1) and (2) are first modeled and removed using a finite element model (FEM). A FEM models the physical properties of tissue. The use of a physical biomechanical model is important since a stated goal of this work is to determine the physical shape-based changes to the prostate from the treatment, and therefore only physical real deformations are to be allowed. A second FEM is then used to isolate the physical, shape-based, treatment-induced changes. We applied and evaluated our model in capturing the laser induced changes to the prostate morphology on eight patients with 3.0 Tesla, T2-weighted MRI, acquired approximately six months following treatment. Our results suggest the laser treatment causes a decrease in prostate volume, which appears to manifest predominantly at the site of ablation. After spatially aligning the images, changes to MRI intensity values are clearly visible at the site of ablation. Our results suggest that our new methodology is able to capture and quantify the degree of laser-induced changes to the prostate. The quantitative measurements reflecting of the deformation changes can be used to track treatment response over time.

Show MeSH
Related in: MedlinePlus