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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)–(e) Difference maps between 24-hours post-LITT and pre-LITT (baseline) for T1w (a), T2w (b), FLAIR (c), and GRE (d).Figs. 10(f)–(i) show difference maps for 2-month post-LITT with respect to baseline, (k)–(n) show difference maps for 7-month post-LITT, (p)–(s) show difference maps for 9-month post-LITT and (u)–(x) show difference maps for 11-month post-LITT with respect to baseline for T1w, T2w, GRE and FLAIR respectively. Corresponding fused multi-parametric MRI maps obtained by weighted combination of individual MRI protocols are shown in Figs. 10(j), (o), (t), (y), corresponding to differences at 24-hour, 2-months, 7-months, 9-months, and 11-months with respect to baseline scan respectively.
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pone-0114293-g010: (a)–(e) Difference maps between 24-hours post-LITT and pre-LITT (baseline) for T1w (a), T2w (b), FLAIR (c), and GRE (d).Figs. 10(f)–(i) show difference maps for 2-month post-LITT with respect to baseline, (k)–(n) show difference maps for 7-month post-LITT, (p)–(s) show difference maps for 9-month post-LITT and (u)–(x) show difference maps for 11-month post-LITT with respect to baseline for T1w, T2w, GRE and FLAIR respectively. Corresponding fused multi-parametric MRI maps obtained by weighted combination of individual MRI protocols are shown in Figs. 10(j), (o), (t), (y), corresponding to differences at 24-hour, 2-months, 7-months, 9-months, and 11-months with respect to baseline scan respectively.

Mentions: Fig. 10 shows corresponding difference maps (a), (b), (d) and (e) for each of the different MRI protocols obtained for a GBM study. Similar difference maps for each of the protocols for image intensity differences at 2-month with respect to baseline, at 7-months with respect to baseline, at 9-months with respect to baseline and at 11-months with respect to baseline are shown in Figs. 10(f)–(i), (k)–(n), (p)–(s), and (u)–(x) respectively. Figs. 10(j), (o), (t), and (y) show the corresponding fused MP-MRI difference maps obtained as a weighted combination of imaging markers as illustrated in Fig. 9(b). Corresponding temporal MP-MRI profiles for successful (shown in green) and unsuccessful treatment (shown in red) obtained by the optimal weights is shown in Fig. 8(f). Note how different MRI protocols change over time post-LITT and contribute to creating a fused MP-MRI profile that is more discriminative of successful treatment and tumor recurrence for GBM studies, as compared to individual MRI protocols (Fig. 8(a), (b), and (c)). Fig. 8(e) shows a trend of volumetric changes over time (obtained on T1w MRI). Please note the similarity in trends obtained via volumetric changes (state-of-the-art) with that obtained from plotting changes on per-pixel basis on multi-parametric MRI profile.


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)–(e) Difference maps between 24-hours post-LITT and pre-LITT (baseline) for T1w (a), T2w (b), FLAIR (c), and GRE (d).Figs. 10(f)–(i) show difference maps for 2-month post-LITT with respect to baseline, (k)–(n) show difference maps for 7-month post-LITT, (p)–(s) show difference maps for 9-month post-LITT and (u)–(x) show difference maps for 11-month post-LITT with respect to baseline for T1w, T2w, GRE and FLAIR respectively. Corresponding fused multi-parametric MRI maps obtained by weighted combination of individual MRI protocols are shown in Figs. 10(j), (o), (t), (y), corresponding to differences at 24-hour, 2-months, 7-months, 9-months, and 11-months with respect to baseline scan respectively.
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Show All Figures
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pone-0114293-g010: (a)–(e) Difference maps between 24-hours post-LITT and pre-LITT (baseline) for T1w (a), T2w (b), FLAIR (c), and GRE (d).Figs. 10(f)–(i) show difference maps for 2-month post-LITT with respect to baseline, (k)–(n) show difference maps for 7-month post-LITT, (p)–(s) show difference maps for 9-month post-LITT and (u)–(x) show difference maps for 11-month post-LITT with respect to baseline for T1w, T2w, GRE and FLAIR respectively. Corresponding fused multi-parametric MRI maps obtained by weighted combination of individual MRI protocols are shown in Figs. 10(j), (o), (t), (y), corresponding to differences at 24-hour, 2-months, 7-months, 9-months, and 11-months with respect to baseline scan respectively.
Mentions: Fig. 10 shows corresponding difference maps (a), (b), (d) and (e) for each of the different MRI protocols obtained for a GBM study. Similar difference maps for each of the protocols for image intensity differences at 2-month with respect to baseline, at 7-months with respect to baseline, at 9-months with respect to baseline and at 11-months with respect to baseline are shown in Figs. 10(f)–(i), (k)–(n), (p)–(s), and (u)–(x) respectively. Figs. 10(j), (o), (t), and (y) show the corresponding fused MP-MRI difference maps obtained as a weighted combination of imaging markers as illustrated in Fig. 9(b). Corresponding temporal MP-MRI profiles for successful (shown in green) and unsuccessful treatment (shown in red) obtained by the optimal weights is shown in Fig. 8(f). Note how different MRI protocols change over time post-LITT and contribute to creating a fused MP-MRI profile that is more discriminative of successful treatment and tumor recurrence for GBM studies, as compared to individual MRI protocols (Fig. 8(a), (b), and (c)). Fig. 8(e) shows a trend of volumetric changes over time (obtained on T1w MRI). Please note the similarity in trends obtained via volumetric changes (state-of-the-art) with that obtained from plotting changes on per-pixel basis on multi-parametric MRI profile.

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