Grayscale median (GSM) post-processing, posterizing, and color mapping for carotid ultrasound

Factors related to atherosclerotic plaques may indicate instability, such as ulcerations, intraplaque hemorrhages, lipid core, thin or irregular fibrous cap, and inflammation. The grayscale median (GSM) value is one of the most widespread methods of studying atherosclerotic plaques and it is therefore important to comprehensively standardize image post-processing. Post-processing was performed using Photoshop 23.1.1.202. Images were standardized by adjusting the grayscale histogram curves, setting the darkest point of the vascular lumen (blood) to zero and the distal adventitia to 190. Posterization and color mapping were performed. A methodology that presents the current state of the art in an accessible and illustrative way should contribute to the dissemination of GSM analysis. This article describes and illustrates the process step by step.

Keywords:
carotid artery diseases; carotid stenosis; Doppler ultrasound; afterimage; computer-assisted image interpretation

Authorship

Pedro Luciano Mellucci Filho

conception and design

analysis and interpretation

data collection

writing the article

final approval of the article

overall responsibility

Universidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.Universidade Estadual PaulistaBrasilBotucatu, SP, BrasilUniversidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.

http://orcid.org/0000-0002-9679-7207

Matheus Bertanha

writing the article

critical revision of the article

final approval of the article

Universidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.Universidade Estadual PaulistaBrasilBotucatu, SP, BrasilUniversidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.

http://orcid.org/0000-0002-6851-2841

Rodrigo Gibin Jaldin

analysis and interpretation

final approval of the article

Universidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.Universidade Estadual PaulistaBrasilBotucatu, SP, BrasilUniversidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.

http://orcid.org/0000-0003-0455-9162

Winston Bonetti Yoshida

critical revision of the article

final approval of the article

Universidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.Universidade Estadual PaulistaBrasilBotucatu, SP, BrasilUniversidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.

http://orcid.org/0000-0002-2921-3777

Marcone Lima Sobreira

analysis and interpretation

writing the article

final approval of the article

Universidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.Universidade Estadual PaulistaBrasilBotucatu, SP, BrasilUniversidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.

http://orcid.org/0000-0003-2271-5878

Conflicts of interest: No conflicts of interest declared concerning the publication of this article.

Correspondence Pedro Luciano Mellucci Filho Universidade Estadual Paulista - UNESP, Faculdade de Medicina de Botucatu - FMB, Departamento de Cirurgia e Ortopedia Av. Professor Mário Rubens Guimarães Montenegro, S/N - Unesp Campus Botucatu CEP: 18618-687 - Botucatu (SP), Brasil Tel.: +55 (18) 99737-8864 E-mail: pedro.lmf@hotmail.com

Author information PLMF - Vascular surgeon and vascular sonographer, Sociedade Brasileira de Angiologia e Cirurgia Vascular (SBACV), Colégio Brasileiro de Radiologia (CBR); Vascular surgeon, Serviço de Cirurgia Vascular e Endovascular, Faculdade de Medicina, Universidade Estadual Paulista (FMB-UNESP). MB - PhD, Universidade Estadual Paulista (UNESP); Assistant professor, Serviço de Cirurgia Vascular e Endovascular, Faculdade de Medicina, Universidade Estadual Paulista (FMB-UNESP). RGJ - PhD, Universidade Estadual Paulista (UNESP); Preceptor, Serviço de Cirurgia Vascular e Endovascular, Faculdade de Medicina, Universidade Estadual Paulista (FMB-UNESP). WBY - Tenured professor, Universidade Estadual Paulista (UNESP); Senior professor, Serviço de Cirurgia Vascular e Endovascular, Faculdade de Medicina, Universidade Estadual Paulista (FMB-UNESP). MLS - Tenured professor, Universidade Estadual Paulista (UNESP); Chief, Serviço de Cirurgia Vascular e Endovascular, Faculdade de Medicina da Universidade Estadual Paulista (FMB-UNESP).

Author contributions Conception and design: PLMF Analysis and interpretation: PLMF, RGJ, MLS Data collection: PLMF Writing the article: PLMF, MB, MLS Critical revision of the article: MB, WBY Final approval of the article*: PLMF, MB, RGJ, WBY, MLS Statistical analysis: N/A Overall responsibility: PLMF *All authors have read and approved of the final version of the article submitted to J Vasc Bras.

SCIMAGO INSTITUTIONS RANKINGS

Universidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.Universidade Estadual PaulistaBrasilBotucatu, SP, BrasilUniversidade Estadual Paulista - UNESP, Botucatu, SP, Brasil.

Figures | Tables

Figures (11)
Tables (1)

Thumbnail

Figure 1
Standardization of image files for grayscale analysis, with 300 dpi resolution and 8-bit grayscale color mode. Pathway: File > New.

Thumbnail

Figure 2
Careful adjustment of the gray channel curves, showing the color of the adventitia in the acquired image at 141, adjusted to 190, which affects the entire image histogram. Pathway: Image > Adjustments> Curves.

Thumbnail

Figure 3
Image and histogram before curve adjustment. Pathway: Window > Histogram.

Thumbnail

Figure 4
Image and histogram after curve adjustment. Pathway: Window > Histogram.

Thumbnail

Figure 5
Selection and analysis of the histogram for the region of the atherosclerotic plaque, providing the grayscale median. Pathway: Window > Histogram. Tools > Lasso Tool.

Thumbnail

Figure 6
Progressive posterization of an image (A > B > C > D), with reduction of the gray gradient available and simplification of the image. Pathway: Image > Adjustments > Posterize.

Thumbnail

Figure 7
Simplified histogram after posterization of the image. Pathway: Window > Histogram.

Thumbnail

Figure 8
Image resulting from color remapping of a grayscale image.

Thumbnail

Figure 9
Color gradient used in conversion and remapping of the image. Pathway: Layer > New Adjustment Layer > Gradient Map.

Thumbnail

Figure 10
Image resulting from color remapping of a grayscale image.

Thumbnail

Figure 11
Selection of the region of interest (atherosclerotic plaque) and removal of the color remapping from the remainder of the image. Pathway: Tools > Lasso Tool. Select inverse, delete.

Thumbnail

Table 1
Grayscale median (GSM) values and intervals observed by Lal et al.,¹³13 Lal BK, Hobson RW 2nd, Pappas PR, et al. Pixel distribution analysis of B-mode ultrasound scan images predicts histologic features of atherosclerotic carotid plaques. J Vasc Surg. 2002;35(6):1210-7. http://dx.doi.org/10.1067/mva.2002.122888. PMid:12042733.
http://dx.doi.org/10.1067/mva.2002.12288... according to the echogenicity of each tissue.

Figure 1 Standardization of image files for grayscale analysis, with 300 dpi resolution and 8-bit grayscale color mode. Pathway: File > New.

Figure 2 Careful adjustment of the gray channel curves, showing the color of the adventitia in the acquired image at 141, adjusted to 190, which affects the entire image histogram. Pathway: Image > Adjustments> Curves.

Figure 3 Image and histogram before curve adjustment. Pathway: Window > Histogram.

Figure 4 Image and histogram after curve adjustment. Pathway: Window > Histogram.

Figure 5 Selection and analysis of the histogram for the region of the atherosclerotic plaque, providing the grayscale median. Pathway: Window > Histogram. Tools > Lasso Tool.

Figure 6 Progressive posterization of an image (A > B > C > D), with reduction of the gray gradient available and simplification of the image. Pathway: Image > Adjustments > Posterize.

Figure 7 Simplified histogram after posterization of the image. Pathway: Window > Histogram.

Figure 8 Image resulting from color remapping of a grayscale image.

Figure 9 Color gradient used in conversion and remapping of the image. Pathway: Layer > New Adjustment Layer > Gradient Map.

Figure 10 Image resulting from color remapping of a grayscale image.

Figure 11 Selection of the region of interest (atherosclerotic plaque) and removal of the color remapping from the remainder of the image. Pathway: Tools > Lasso Tool. Select inverse, delete.

Table 1 Grayscale median (GSM) values and intervals observed by Lal et al.,¹³13 Lal BK, Hobson RW 2nd, Pappas PR, et al. Pixel distribution analysis of B-mode ultrasound scan images predicts histologic features of atherosclerotic carotid plaques. J Vasc Surg. 2002;35(6):1210-7. http://dx.doi.org/10.1067/mva.2002.122888. PMid:12042733.
http://dx.doi.org/10.1067/mva.2002.12288... according to the echogenicity of each tissue.

	GSM
	Median	Interval
Blood	2	0-4
Fat	12	8-26
Muscle	53	41-76
Fibrotic tissue	172	112-196
Calcium	221	211-255

How to cite

copy

Sociedade Brasileira de Angiologia e de Cirurgia Vascular (SBACV) Rua Estela, 515, bloco E, conj. 21, Vila Mariana, CEP04011-002 - São Paulo, SP, Tel.: (11) 5084.3482 / 5084.2853 - Porto Alegre - RS - Brazil
E-mail: secretaria@sbacv.org.br

Acompanhe os números deste periódico no seu leitor de RSS

Versão para download de PDF

PDF

Português
Inglês

Versões e tradução automática

Versão original do texto

English
Português

Tradução automática

Google Translator
Microsoft Translator

Como citar

RIS

BIBTEX

Outros formatos de citação e exportação:

SciELO - Scientific Electronic Library Online
Rua Dr. Diogo de Faria, 1087 – 9º andar – Vila Clementino 04037-003 São Paulo/SP - Brasil
E-mail: scielo@scielo.org

Leia a Declaração de Acesso Aberto

Métricas

Grayscale median (GSM) post-processing, posterizing, and color mapping for carotid ultrasound

PlumX

Mensagem

[1] Conflicts of interest: No conflicts of interest declared concerning the publication of this article.