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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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(a)–(d) show a 2D T1w MRI slice at different time points, pre-LITT (a), 24- hours post-LITT (b), 1-month post-LITT (c), and 3-month post-LITT (d) for a seizure-free epilepsy study, while 1(e)–(h) show a 2D T2w MRI slice at pre-LITT (e), 24-hours (f), 2-months (g), and 7 months (h) respectively for a successfully treated (no signs of recurrence at the time of evaluation) GBM study.Note how changes in imaging markers subside over time in the case of a LITT procedure with successful treatment.
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pone-0114293-g001: (a)–(d) show a 2D T1w MRI slice at different time points, pre-LITT (a), 24- hours post-LITT (b), 1-month post-LITT (c), and 3-month post-LITT (d) for a seizure-free epilepsy study, while 1(e)–(h) show a 2D T2w MRI slice at pre-LITT (e), 24-hours (f), 2-months (g), and 7 months (h) respectively for a successfully treated (no signs of recurrence at the time of evaluation) GBM study.Note how changes in imaging markers subside over time in the case of a LITT procedure with successful treatment.

Mentions: More recently, LITT has also emerged as an alternative to traditional craniotomy for epilepsy, which attempts to ablate seizure focus with minimal damage to normal surrounding tissue [8]. In cases of lesional epilepsy, such as mesial temporal sclerosis (MTS), LITT can be used to ablate the focus under direct and real-time MRI monitoring [4]. Fig. 1a is an example of a sclerotic hippocampus that was targeted for ablation. The existence of imaging markers after ablation of epileptogenic foci can be explored in the context of treatment related changes (such as swelling, edema, seizure recurrence, and irreversible tissue damage) which present as early-, mid-, and delayed-effects [9], [10]. However, a quantitative study evaluating the changes in MRI imaging markers over time within the ablation zone to study LITT effects on epilepsy patients has not yet been performed.


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

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

(a)–(d) show a 2D T1w MRI slice at different time points, pre-LITT (a), 24- hours post-LITT (b), 1-month post-LITT (c), and 3-month post-LITT (d) for a seizure-free epilepsy study, while 1(e)–(h) show a 2D T2w MRI slice at pre-LITT (e), 24-hours (f), 2-months (g), and 7 months (h) respectively for a successfully treated (no signs of recurrence at the time of evaluation) GBM study.Note how changes in imaging markers subside over time in the case of a LITT procedure with successful treatment.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0114293-g001: (a)–(d) show a 2D T1w MRI slice at different time points, pre-LITT (a), 24- hours post-LITT (b), 1-month post-LITT (c), and 3-month post-LITT (d) for a seizure-free epilepsy study, while 1(e)–(h) show a 2D T2w MRI slice at pre-LITT (e), 24-hours (f), 2-months (g), and 7 months (h) respectively for a successfully treated (no signs of recurrence at the time of evaluation) GBM study.Note how changes in imaging markers subside over time in the case of a LITT procedure with successful treatment.
Mentions: More recently, LITT has also emerged as an alternative to traditional craniotomy for epilepsy, which attempts to ablate seizure focus with minimal damage to normal surrounding tissue [8]. In cases of lesional epilepsy, such as mesial temporal sclerosis (MTS), LITT can be used to ablate the focus under direct and real-time MRI monitoring [4]. Fig. 1a is an example of a sclerotic hippocampus that was targeted for ablation. The existence of imaging markers after ablation of epileptogenic foci can be explored in the context of treatment related changes (such as swelling, edema, seizure recurrence, and irreversible tissue damage) which present as early-, mid-, and delayed-effects [9], [10]. However, a quantitative study evaluating the changes in MRI imaging markers over time within the ablation zone to study LITT effects on epilepsy patients has not yet been performed.

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