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Identifying MRI markers associated with early response following laser ablation for neurological disorders: preliminary findings.

Tiwari P, Danish S, Madabhushi A - PLoS ONE (2014)

Bottom Line: Although highly promising, the long-term effects of laser ablation as a viable treatment option for neurological disorders have yet to be rigorously studied and quantified.In this work, we present a quantitative framework for monitoring per-voxel thermal-induced changes post-LITT over time on multi parametric MRI.On a cohort of six GBM studies we found that (a) it may be important for the initial treatment-related changes to subside to more reliably capture MRI markers relating to tumor recurrence, and (b) T1w MRI and T2-GRE may better differentiate changes that may correspond to tumor recurrence from patients with no recurrence, as compared to T2w-MRI, and FLAIR.

View Article: PubMed Central - PubMed

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

ABSTRACT
There is a renewed interest in MR-guided laser interstitial thermal therapy (LITT) as a minimally invasive alternative to craniotomy for local treatment of various brain tumors and epilepsy. LITT allows for focused delivery of laser energy monitored in real time by MRI, for precise ablation of the lesion. Although highly promising, the long-term effects of laser ablation as a viable treatment option for neurological disorders have yet to be rigorously studied and quantified. In this work, we present a quantitative framework for monitoring per-voxel thermal-induced changes post-LITT over time on multi parametric MRI. We demonstrate that voxel-by-voxel quantification of MRI markers over time can enable a careful and accurate (a) characterization of early LITT-related changes (if and when they are exaggerated and when they subside), and (b) identification and monitoring of MRI markers that potentially allow for better quantification of response to LITT therapy. The framework was evaluated on two distinct cohorts of patients (GBM, epilepsy), who were monitored post-LITT at regular time-intervals via multi-parametric MRI. On a cohort of six GBM studies we found that (a) it may be important for the initial treatment-related changes to subside to more reliably capture MRI markers relating to tumor recurrence, and (b) T1w MRI and T2-GRE may better differentiate changes that may correspond to tumor recurrence from patients with no recurrence, as compared to T2w-MRI, and FLAIR. Similarly, our preliminary analysis of four epilepsy studies suggests that (a) early LITT changes (attributed to swelling, edema) appear to subside within 4-weeks post-LITT, and (b) ADC may be more reflective of early treatment changes (up to 1 month), while T1w may be more reflective of early delayed treatment changes (1 month, 3 months), while T2-w and T2-FLAIR appeared to be more sensitive to late treatment related changes (6-months post-LITT) compared to the other MRI protocols under evaluation.

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Checker-box representation of co-registration across different MR sequences at different time-points with respect to pre-LITT T1w MRI for (a) different pre-LITT MRI acquisitions, (b) 24-hour post-LITT MRI acquisitions, (c) 1-month post-LITT MRI acquisitions, and (d) 3-month post-LITT MRI acquisitions.Note the perfect alignment of the boundaries across different protocols and time-points. Pair-wise co-registration with respect to one reference MR sequence (T1w MRI) allows for quantitative comparison of different protocols at different time-points.
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pone-0114293-g004: Checker-box representation of co-registration across different MR sequences at different time-points with respect to pre-LITT T1w MRI for (a) different pre-LITT MRI acquisitions, (b) 24-hour post-LITT MRI acquisitions, (c) 1-month post-LITT MRI acquisitions, and (d) 3-month post-LITT MRI acquisitions.Note the perfect alignment of the boundaries across different protocols and time-points. Pair-wise co-registration with respect to one reference MR sequence (T1w MRI) allows for quantitative comparison of different protocols at different time-points.

Mentions: A 3D affine transformation [29] with 12 degrees of freedom, encoding rotation, translation, shear, and scale, was employed to accurately align post-LITT MRI with reference to pre-LITT (at time-point ) T1w MRI, , which yielded a registered 3D MRI volume, at every time-point , being the total number of time points evaluated post-LITT, for every MRI protocol, . Since MRIs are acquired at different time-points, the number of slices for different MRI protocols and resolution across acquisition may be different across pre-, and post-LITT MRI protocols. Hence, during co-registration, the 3D volume is appropriately resampled and interpolated, to account for varying voxel sizes and resolutions between different time-points and protocols. Note that all the different MP-MRI acquisitions are aligned to the pre-treatment frame of reference pre-LITT T1-w MRI to enable per-voxel quantitative comparisons across different time-points and protocols post-LITT (Fig. 4).


Identifying MRI markers associated with early response following laser ablation for neurological disorders: preliminary findings.

Tiwari P, Danish S, Madabhushi A - PLoS ONE (2014)

Checker-box representation of co-registration across different MR sequences at different time-points with respect to pre-LITT T1w MRI for (a) different pre-LITT MRI acquisitions, (b) 24-hour post-LITT MRI acquisitions, (c) 1-month post-LITT MRI acquisitions, and (d) 3-month post-LITT MRI acquisitions.Note the perfect alignment of the boundaries across different protocols and time-points. Pair-wise co-registration with respect to one reference MR sequence (T1w MRI) allows for quantitative comparison of different protocols at different time-points.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4263602&req=5

pone-0114293-g004: Checker-box representation of co-registration across different MR sequences at different time-points with respect to pre-LITT T1w MRI for (a) different pre-LITT MRI acquisitions, (b) 24-hour post-LITT MRI acquisitions, (c) 1-month post-LITT MRI acquisitions, and (d) 3-month post-LITT MRI acquisitions.Note the perfect alignment of the boundaries across different protocols and time-points. Pair-wise co-registration with respect to one reference MR sequence (T1w MRI) allows for quantitative comparison of different protocols at different time-points.
Mentions: A 3D affine transformation [29] with 12 degrees of freedom, encoding rotation, translation, shear, and scale, was employed to accurately align post-LITT MRI with reference to pre-LITT (at time-point ) T1w MRI, , which yielded a registered 3D MRI volume, at every time-point , being the total number of time points evaluated post-LITT, for every MRI protocol, . Since MRIs are acquired at different time-points, the number of slices for different MRI protocols and resolution across acquisition may be different across pre-, and post-LITT MRI protocols. Hence, during co-registration, the 3D volume is appropriately resampled and interpolated, to account for varying voxel sizes and resolutions between different time-points and protocols. Note that all the different MP-MRI acquisitions are aligned to the pre-treatment frame of reference pre-LITT T1-w MRI to enable per-voxel quantitative comparisons across different time-points and protocols post-LITT (Fig. 4).

Bottom Line: Although highly promising, the long-term effects of laser ablation as a viable treatment option for neurological disorders have yet to be rigorously studied and quantified.In this work, we present a quantitative framework for monitoring per-voxel thermal-induced changes post-LITT over time on multi parametric MRI.On a cohort of six GBM studies we found that (a) it may be important for the initial treatment-related changes to subside to more reliably capture MRI markers relating to tumor recurrence, and (b) T1w MRI and T2-GRE may better differentiate changes that may correspond to tumor recurrence from patients with no recurrence, as compared to T2w-MRI, and FLAIR.

View Article: PubMed Central - PubMed

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

ABSTRACT
There is a renewed interest in MR-guided laser interstitial thermal therapy (LITT) as a minimally invasive alternative to craniotomy for local treatment of various brain tumors and epilepsy. LITT allows for focused delivery of laser energy monitored in real time by MRI, for precise ablation of the lesion. Although highly promising, the long-term effects of laser ablation as a viable treatment option for neurological disorders have yet to be rigorously studied and quantified. In this work, we present a quantitative framework for monitoring per-voxel thermal-induced changes post-LITT over time on multi parametric MRI. We demonstrate that voxel-by-voxel quantification of MRI markers over time can enable a careful and accurate (a) characterization of early LITT-related changes (if and when they are exaggerated and when they subside), and (b) identification and monitoring of MRI markers that potentially allow for better quantification of response to LITT therapy. The framework was evaluated on two distinct cohorts of patients (GBM, epilepsy), who were monitored post-LITT at regular time-intervals via multi-parametric MRI. On a cohort of six GBM studies we found that (a) it may be important for the initial treatment-related changes to subside to more reliably capture MRI markers relating to tumor recurrence, and (b) T1w MRI and T2-GRE may better differentiate changes that may correspond to tumor recurrence from patients with no recurrence, as compared to T2w-MRI, and FLAIR. Similarly, our preliminary analysis of four epilepsy studies suggests that (a) early LITT changes (attributed to swelling, edema) appear to subside within 4-weeks post-LITT, and (b) ADC may be more reflective of early treatment changes (up to 1 month), while T1w may be more reflective of early delayed treatment changes (1 month, 3 months), while T2-w and T2-FLAIR appeared to be more sensitive to late treatment related changes (6-months post-LITT) compared to the other MRI protocols under evaluation.

Show MeSH
Related in: MedlinePlus