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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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Related in: MedlinePlus

Illustration of the ablation related effects on the prostate, bladder, and rectum modeled by the FEM.((a)) represents the bladder and rectum in pale blue, and prostate in teal. ((b)) represents the synthetic deformation T2. The deformed prostate is shown in yellow, and the arrows in ((b)) represent the direction of the transform (mostly due to the rectum). ((c)) represents the result of the recovered deformation . The deformed prostate is shown in semi-transparent yellow in ((b)) and ((c)). The high level of overlap between the semi-transparent yellow prostate and the teal prostate in ((c)) shows the accuracy of removing the simulated effects of the bladder and rectum motion.
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pone.0150016.g003: Illustration of the ablation related effects on the prostate, bladder, and rectum modeled by the FEM.((a)) represents the bladder and rectum in pale blue, and prostate in teal. ((b)) represents the synthetic deformation T2. The deformed prostate is shown in yellow, and the arrows in ((b)) represent the direction of the transform (mostly due to the rectum). ((c)) represents the result of the recovered deformation . The deformed prostate is shown in semi-transparent yellow in ((b)) and ((c)). The high level of overlap between the semi-transparent yellow prostate and the teal prostate in ((c)) shows the accuracy of removing the simulated effects of the bladder and rectum motion.

Mentions: Fig 3 shows the qualitative results of T2 in Fig 3(b) and the recovered deformation in Fig 3(c). In this case, the change in the rectum (pale blue, below) was the primary driving force in pushing the prostate (teal) upwards, near the apex. The pulling effect caused by bringing the rectum back to its original position caused the inverse deformation in the prostate, yielding a high overlap with the undeformed, pre-treatment prostate in Fig 3(c).


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)

Illustration of the ablation related effects on the prostate, bladder, and rectum modeled by the FEM.((a)) represents the bladder and rectum in pale blue, and prostate in teal. ((b)) represents the synthetic deformation T2. The deformed prostate is shown in yellow, and the arrows in ((b)) represent the direction of the transform (mostly due to the rectum). ((c)) represents the result of the recovered deformation . The deformed prostate is shown in semi-transparent yellow in ((b)) and ((c)). The high level of overlap between the semi-transparent yellow prostate and the teal prostate in ((c)) shows the accuracy of removing the simulated effects of the bladder and rectum motion.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0150016.g003: Illustration of the ablation related effects on the prostate, bladder, and rectum modeled by the FEM.((a)) represents the bladder and rectum in pale blue, and prostate in teal. ((b)) represents the synthetic deformation T2. The deformed prostate is shown in yellow, and the arrows in ((b)) represent the direction of the transform (mostly due to the rectum). ((c)) represents the result of the recovered deformation . The deformed prostate is shown in semi-transparent yellow in ((b)) and ((c)). The high level of overlap between the semi-transparent yellow prostate and the teal prostate in ((c)) shows the accuracy of removing the simulated effects of the bladder and rectum motion.
Mentions: Fig 3 shows the qualitative results of T2 in Fig 3(b) and the recovered deformation in Fig 3(c). In this case, the change in the rectum (pale blue, below) was the primary driving force in pushing the prostate (teal) upwards, near the apex. The pulling effect caused by bringing the rectum back to its original position caused the inverse deformation in the prostate, yielding a high overlap with the undeformed, pre-treatment prostate in Fig 3(c).

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