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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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Results for three patients (one per column).The first row represents the pre-treament MRI scan (IPre). The second row represents the location of the laser during treatment. The third row represents the post-treament MRI scan (IPost). The fourth row represents a heat map of the ablation induced deformations T3. White represents regions of large deformations (2.2 mm), while transparent red represents regions of small deformations (0 mm). Small arrows represent the direction of the deformation (in all cases pointing towards the centroid of the prostate) after removing deformations due to patient alignment (T1) and surrounding tissues (T2). It can be seen that in all patients, the areas with the the largest deformations correspond to the focal laser ablation sites.
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pone.0150016.g005: Results for three patients (one per column).The first row represents the pre-treament MRI scan (IPre). The second row represents the location of the laser during treatment. The third row represents the post-treament MRI scan (IPost). The fourth row represents a heat map of the ablation induced deformations T3. White represents regions of large deformations (2.2 mm), while transparent red represents regions of small deformations (0 mm). Small arrows represent the direction of the deformation (in all cases pointing towards the centroid of the prostate) after removing deformations due to patient alignment (T1) and surrounding tissues (T2). It can be seen that in all patients, the areas with the the largest deformations correspond to the focal laser ablation sites.

Mentions: Fig 5 shows the registration result for three patients in order to determine where the shape-based changes in the prostate occurred. Each patient is represented by a column. The first row shows IPre, the second row an image of the ablation needle during treatment, and the third row shows IPost. The slight change in volume in the prostate is visible on IPost. The registration result T3 is shown in the fourth row. The arrows represent the direction of the shape-based changes, and in all cases they point inwards towards the center of the prostate close to the site of ablation. In addition, the deformation heatmap shows the magnitude of shape-based changes (∥T3(c) − c∥2), where red represents a small change and white represents a large change. These results show that a slight decrease in volume of the prostate occurred at the site of ablation, suggesting that the focal laser ablation induced necrosis caused a change in prostate morphology and shape.


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)

Results for three patients (one per column).The first row represents the pre-treament MRI scan (IPre). The second row represents the location of the laser during treatment. The third row represents the post-treament MRI scan (IPost). The fourth row represents a heat map of the ablation induced deformations T3. White represents regions of large deformations (2.2 mm), while transparent red represents regions of small deformations (0 mm). Small arrows represent the direction of the deformation (in all cases pointing towards the centroid of the prostate) after removing deformations due to patient alignment (T1) and surrounding tissues (T2). It can be seen that in all patients, the areas with the the largest deformations correspond to the focal laser ablation sites.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0150016.g005: Results for three patients (one per column).The first row represents the pre-treament MRI scan (IPre). The second row represents the location of the laser during treatment. The third row represents the post-treament MRI scan (IPost). The fourth row represents a heat map of the ablation induced deformations T3. White represents regions of large deformations (2.2 mm), while transparent red represents regions of small deformations (0 mm). Small arrows represent the direction of the deformation (in all cases pointing towards the centroid of the prostate) after removing deformations due to patient alignment (T1) and surrounding tissues (T2). It can be seen that in all patients, the areas with the the largest deformations correspond to the focal laser ablation sites.
Mentions: Fig 5 shows the registration result for three patients in order to determine where the shape-based changes in the prostate occurred. Each patient is represented by a column. The first row shows IPre, the second row an image of the ablation needle during treatment, and the third row shows IPost. The slight change in volume in the prostate is visible on IPost. The registration result T3 is shown in the fourth row. The arrows represent the direction of the shape-based changes, and in all cases they point inwards towards the center of the prostate close to the site of ablation. In addition, the deformation heatmap shows the magnitude of shape-based changes (∥T3(c) − c∥2), where red represents a small change and white represents a large change. These results show that a slight decrease in volume of the prostate occurred at the site of ablation, suggesting that the focal laser ablation induced necrosis caused a change in prostate morphology and shape.

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