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ORIGINAL ARTICLES
Published online: 2020-03-18
Submitted: 2020-02-03
Accepted: 2020-02-26
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Comparison of color difference formulas to best distinguish resected areas of malignant brain tumors from their background using 5-aminolevulinic acid fluorescence

T. Szmuda, S. Ali, P. Słoniewski
DOI: 10.5603/FM.a2020.0035
·
Pubmed: 32207850

open access

Ahead of Print
ORIGINAL ARTICLES
Published online: 2020-03-18
Submitted: 2020-02-03
Accepted: 2020-02-26

Abstract

Background: Fluorescence-guided surgery (FGS) with 5-aminolevulinic acid (5-ALA) his proven to assist neurosurgeons to achieve a more complete brain tumour resection. However, 5-ALA-guided surgery is limited since it is often difficult to distinguish the colour difference between the resected areas of malignant brain tumours from their background. Our aim was to evaluate which colour difference formula was the most optimal to distinguish between malignant brain tumors from the background healthy tissue using 5-ALA fluorescence.

Materials and methods: 37 patients with a primary or secondary malignant brain tumour ingested 5-ALA before the surgery. A 400 nm light was used to excite the fluorescence. Surgical videos were recorded for all the patients and a total of 183 samples were obtained from the fluorescent areas and their respective backgrounds. Three colour differences formulas—contrast ratio (CR), CIELab (ΔE*) and CIEDE2000—were applied to the videos and compared using hot-cold maps. Baseline demographics, the tumour’s location, the tumour’s side, and tumour’s World Health Organisation (WHO) grade was also analysed for correlations relating to the fluorescence. Chi-square and the Student’s t-test were used for univariate relations. The three channels of the CIELAB colour space (L*, a* and b*) were analysed together and separately (since L* of fluorescent areas was significantly higher than the background).

Results: ΔE* resulted in good discrimination of a* and b*, and moderate but acceptable discrimination of L*. CIEDE2000 distinguished differences in a* and b*, although, not in L*.

The CR distinguished only L*, whereas the probability of discriminating a* and b* channels failed. Neither age, sex, tumour location, tumour size or the WHO grade influenced the a*, b* and L* colour values (p >0.05). Colour differences measured by ΔE* and CIEDE2000 correlated together (r=0.99, p<0.01), whereas CR correlated only with ΔE (r=0.21, p=0.01) but not with CIEDE2000 (r=0.07, p=0.32).

Conclusions: ΔE* obtained the best colour discrimination between the resected areas of malignant brain tumours and the background when compared to CR and CIEDE2000. Therefore, ΔE* may be the best formula to help neurosurgeons distinguish the colour differences when operating malignant brain tumours with 5-ALA fluorescence.

Abstract

Background: Fluorescence-guided surgery (FGS) with 5-aminolevulinic acid (5-ALA) his proven to assist neurosurgeons to achieve a more complete brain tumour resection. However, 5-ALA-guided surgery is limited since it is often difficult to distinguish the colour difference between the resected areas of malignant brain tumours from their background. Our aim was to evaluate which colour difference formula was the most optimal to distinguish between malignant brain tumors from the background healthy tissue using 5-ALA fluorescence.

Materials and methods: 37 patients with a primary or secondary malignant brain tumour ingested 5-ALA before the surgery. A 400 nm light was used to excite the fluorescence. Surgical videos were recorded for all the patients and a total of 183 samples were obtained from the fluorescent areas and their respective backgrounds. Three colour differences formulas—contrast ratio (CR), CIELab (ΔE*) and CIEDE2000—were applied to the videos and compared using hot-cold maps. Baseline demographics, the tumour’s location, the tumour’s side, and tumour’s World Health Organisation (WHO) grade was also analysed for correlations relating to the fluorescence. Chi-square and the Student’s t-test were used for univariate relations. The three channels of the CIELAB colour space (L*, a* and b*) were analysed together and separately (since L* of fluorescent areas was significantly higher than the background).

Results: ΔE* resulted in good discrimination of a* and b*, and moderate but acceptable discrimination of L*. CIEDE2000 distinguished differences in a* and b*, although, not in L*.

The CR distinguished only L*, whereas the probability of discriminating a* and b* channels failed. Neither age, sex, tumour location, tumour size or the WHO grade influenced the a*, b* and L* colour values (p >0.05). Colour differences measured by ΔE* and CIEDE2000 correlated together (r=0.99, p<0.01), whereas CR correlated only with ΔE (r=0.21, p=0.01) but not with CIEDE2000 (r=0.07, p=0.32).

Conclusions: ΔE* obtained the best colour discrimination between the resected areas of malignant brain tumours and the background when compared to CR and CIEDE2000. Therefore, ΔE* may be the best formula to help neurosurgeons distinguish the colour differences when operating malignant brain tumours with 5-ALA fluorescence.

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Keywords

5-aminolevulinic acid; glioma surgery; colour perception; CIEDE2000; fluorescence

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About this article
Title

Comparison of color difference formulas to best distinguish resected areas of malignant brain tumors from their background using 5-aminolevulinic acid fluorescence

Journal

Folia Morphologica

Issue

Ahead of Print

Published online

2020-03-18

DOI

10.5603/FM.a2020.0035

Pubmed

32207850

Keywords

5-aminolevulinic acid
glioma surgery
colour perception
CIEDE2000
fluorescence

Authors

T. Szmuda
S. Ali
P. Słoniewski

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