Image Analysis as tool for Predicting Colorectal Cancer Molecular Alterations: A Scoping Review
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Original Article

Image Analysis as tool for Predicting Colorectal Cancer Molecular Alterations: A Scoping Review

Mol Imaging Radionucl Ther 2025;34(1):10-25 DOI: 10.4274/mirt.galenos.2024.86402
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Abstract

Objectives

Among the most important diagnostic indicators of colorectal cancer; however, measuring molecular alterations are invasive and expensive. This study aimed to investigate the application of image processing to predict molecular alterations in colorectal cancer.

Methods

In this scoping review, we searched for relevant literature by searching the Web of Science, Scopus, and PubMed databases. The method of selecting the articles and reporting the findings was according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses; moreover, the Strengthening the Reporting of Observational Studies in Epidemiology checklist was used to assess the quality of the studies.

Results

Sixty seven out of 2,223 articles, 67 were relevant to the aim of the study, and finally 41 studies with sufficient quality were reviewed. The prediction of Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS), Neuroblastoma RAS Viral (NRAS), B-Raf proto-oncogene, serine/threonine kinase (BRAF), Tumor Protein 53 (TP53), Adenomatous Polyposis Coli, and microsatellite instability (MSI) with the help of image analysis has received more attention than other molecular characteristics. The studies used computed tomography (CT), magnetic resonance imaging (MRI), and 18F-FDG positron emission tomography (PET)/CT with radionics and quantitative analysis to predict molecular alterations in colorectal cancer, analyzing features like texture, maximum standard uptake value, and MTV using various statistical methods. In 39 studies, there was a significant relationship between the features extracted from these images and molecular alterations. Different modalities were used to measure the area under the receiver operating characteristic curve for predicting the alterations in KRAS, MSI, BRAF, and TP53, with an average of 78, 81, 80 and 71%, respectively.

Conclusion

This scoping review underscores the potential of radiogenomics in predicting molecular alterations in colorectal cancer through non-invasive imaging modalities, like CT, MRI, and 18F-FDG PET/CT. The analysis of 41 studies showed the appropriate prediction of key alterations, such as KRAS, NRAS, BRAF, TP53, and MSI, highlighting the promise of radionics and texture features in enhancing predictive accuracy.

Keywords: Radiogenomics, colorectal cancer, molecular alterations, image processing

Introduction

Colorectal cancer is the third most common cancer in the world; it ranks second in men and third in women in terms of cancer-related deaths (, ). In 2022, a total of 1,926,118 new cancer cases and 903,859 deaths were reported (). Although the incidence of cancer has decreased in high-income countries because of continuous screenings in the elderly and changes in risk factors (, ), it is still increasing in low-income countries (, ).

 Colorectal cancer, which is caused by the accumulation of genetic and epigenetic changes in the colon epithelium, is a complex heterogeneous disease with different histopathology, (). These changes lead to the activation of oncogenes, inactivation of tumor suppressor genes, and disturbance in the regulation of signaling pathways involved in cell proliferation, differentiation, and apoptosis (). As a result of different histopathology and heterogeneity, the progress of colorectal cancer is very different in different people. Therefore, it is very important to predict disease progression to determine the appropriate treatment (). To date, many efforts have been made to identify factors affecting disease progression, such as the “Tumor”, “Nodes”, “Metastases” (TNM) classification which, from histopathology point of view, classifies cancer into four groups with different rates of disease progression (, ). However, the rate of disease progression in the TNM groups differed due to the molecular differentiation and heterogeneity within the tumor ().

One-way to predict disease progression is to pay attention to molecular alterations, such as Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS), Neuroblastoma RAS Viral (NRAS), B-Raf proto-oncogene, serine/threonine kinase (BRAF), Tumor Protein 53 (TP53), microsatellite instability (MSI) and PIK3CA (). Current methods for measuring these factors in colorectal cancer, such as DNA sequence analysis, are costly, time-consuming, and invasive (). In addition, sampling from one point of the tumor to perform genetic tests and heterogeneity in different parts of the tumor, this method may not accurately reflect the molecular alterations of colorectal cancer (). The problems of measuring molecular alterations can be overcome by predicting their values through analyzing medical images, such as computed tomography (CT) scan, magnetic resonance imaging (MRI), and 18F-FDG PET/CT, which have recently attracted the attention of researchers (). Radiogenomics, a new concept introduced in recent years, examines the relationship between molecular alterations (especially genetic alterations) of cells and images (). Non-invasive imaging provides information on tumor morphology and metabolism to some extent and can be used to identify potential biomarkers and molecular alterations in colorectal cancer (). Several studies have shown that CT scanning can predict the KRAS mutation status in colorectal cancer patients (, ).

However, the use of image processing to predict MC molecular alterations is still in its early stages (, ). Therefore, this study aimed to investigate the use of image processing to predict molecular alterations in colorectal cancer. The research questions of this study are as follows:

1. Which molecular alterations have received more attention in the field of radiogenomics?

2. Which imaging modalities are used to predict molecular alterations?

3. What is the performances of the modalities in the prediction of various molecular alterations?

Materials and Methods

In this scoping review conducted in 2024, the reporting process was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) (). All original articles published from January 01, 2013 to April 31, 2024 and indexed in Scopus, PubMed, and Web of Science databases were extracted. The inclusion criteria were original research articles in colorectal cancer. The exclusion criteria were review studies, non-English articles, studies beyond the scope of colorectal cancer, and articles with limited access.

The standard keywords and their synonyms for the three terms “molecular alterations”, “medical image” and “colorectal cancer” were determined according to medical subject headings, and a search strategy was determined for each database (, ).

Table 1. Search strategy by database

Data base

Search strategy

PubMed

((((Gene[mesh] OR Genom*[Title/Abstract] OR “molecular alterations”[Title/Abstract] OR “Genes, APC”[mesh] OR “Genes, ras”[mesh] OR “Proto-Oncogene Proteins B-raf”[mesh] OR TP53 [Title/Abstract] OR “microsatellite instability”[mesh] OR MSI[Title/Abstract]) AND ( “Tomography, X-Ray Computed” [mesh] OR “Positron emission tomography” [mesh] OR “Magnetic resonance imaging” [mesh] OR “Diagnostic imaging” [mesh] OR Radiomics [mesh])) OR “radio-genomics” [Title/Abstract] OR radiogenomics [Title/Abstract] OR “imaging genomics” [Title/Abstract] OR “radiation genomics” [Title/Abstract]) AND (Colorectal Neoplasms [mesh] OR CRC[Title/Abstract])) AND 2013/01/01: 2024/04/28 [dp]

Web of Science

((((TS=(Gene) OR TS=(Genom*)OR TS =(“ molecular alterations”)OR TS=( Cistron*)OR TS=( Genetic)OR TS=( “Genes, APC”) OR TS=( “Genes, ras”) OR TS=( RAS) OR TS=( APC) OR TS=( APC) OR TS=( “Proto-Oncogene Proteins B-raf”) OR TS=( BRAF) OR TS=( BRAF) OR TS=( “tumor protein p53”) OR TS=( TP53) OR TS=( “microsatellite instability”) OR TS=( MSI) ) AND (TS=( “Diagnostic imaging”) OR TS=( “CT scan”) OR TS=( MRI) OR TS=( “18F-FDG PET/CT”) OR TS=( “computerized tomography”) OR TS=( “Positron emission tomography”) OR TS=( “Magnetic resonance imaging”) OR TS=( Radiomics))) OR (TS=( “radio-genomics”) OR TS=( radiogenomics) OR TS=( “imaging genomics”) OR TS=( “radiation genomics”)))AND (TS=( “Colorectal Neoplasms”) OR TS=( “Colorectal cancer”) OR TS=( CRC))) AND PY=(2013-2024)

Scopus

(((TITLE-ABS-KEY(Gene) OR TITLE-ABS-KEY(Cistron*) OR TITLE-ABS-KEY(“molecular alterations”) OR TITLE-ABS-KEY(Genetic) OR TITLE-ABS-KEY(genom*) OR TITLE-ABS-KEY(“Genes, APC”) OR TITLE-ABS-KEY(APC) OR TITLE-ABS-KEY(“Genes, ras”) OR TITLE-ABS-KEY(RAS) OR TITLE-ABS-KEY(BRAF) OR TITLE-ABS-KEY(“Proto-Oncogene Proteins B-raf”) OR TITLE-ABS-KEY(“tumor protein p53”) OR TITLE-ABS-KEY(TP53) OR TITLE-ABS-KEY(“microsatellite instability”) OR TITLE-ABS-KEY(MSI)) AND (TITLE-ABS-KEY(“Diagnostic imaging”) OR TITLE-ABS-KEY(“CT scan”) OR TITLE-ABS-KEY(MRI) OR TITLE-ABS-KEY(“18F-FDG PET/CT”) OR TITLE-ABS-KEY(“computerized tomography”) OR TITLE-ABS-KEY(“Magnetic resonance imaging”) OR TITLE-ABS-KEY(“Positron emission tomography”) OR TITLE-ABS-KEY(Radiomics))) OR (TITLE-ABS-KEY(radiogenomics) OR TITLE-ABS-KEY(“radio-genomics”) OR TITLE-ABS-KEY(“imaging genomics”) OR TITLE-ABS-KEY(“radiation genomics”))) AND (TITLE-ABS-KEY(“Colorectal Neoplasms”) OR TITLE-ABS-KEY(“Colorectal cancer”) OR TITLE-ABS-KEY(CRC))) AND (PUBYEAR > 2013 AND PUBYEAR < 2024)

Table 2. Characteristics of reviewed studies

Studies

Participants

Molecular factors

Image

Statistics

Author

Type

Country/Year

Participants

Aim

Gene Oncogene/Suppressor

Modality

Analyzing techniques (features)

Technique

Lovinfosse et al. (19)

Retrospective study

Belgium/2016

151

Predicting RAS mutation as an indicator of treatment

KRAS

NRAS

RAS

18F-FDG PET/CT

Radiomics (texture features)

Spearman correlation coefficient

Yang et al. (20)

Retrospective study

China\ 2021

42

Investigating the association between EIF2S2 and 18F-FDG PET/CT

EIF2S2

GLUT1

18F-FDG PET/CT

Radiomics [SUVmax, SUVmean, total lesion glycolysis (TLG), and metabolic tumor volume (MTV)]

Spearman’s correlation coefficient

Huang et al. (21)

Cohort study

Taiwan \ 2022

71

Finding therapeutic targets using radiomic features

PECAM1

PRDM1

 AIF1

 IL10

 ISG20

 TLR8

CT scan

Radiomics (1,037 radiomic feature)

Heatmap visualization and correlation coefficient

Jo and Kim. (22)

Retrospective study

 South Korea \ 2018

75

 Investigating the association between KRAS mutations and MRI-based radiologic findings

KRAS

MRI

Axial to longitudinal tumor length (ATL/LTL)

The Mann-Whitney U test

Yang et al. (23)

Retrospective study

China \ 2017

61

 Prediction of KRAS/NRAS/BRAF mutations

KRAS

NRAS

BRAF

CT scan

Radiomics [shape features, gray-level histogram features, gray-level co-occurrence matrix (GLCM) features, gray-level run-length matrix (GLRLM) features]

t-test or the Mann-Whitney U test for continuous variables and the chi-square test for categorical variables

Xu et al. (24)

Retrospective study

China \ 2019

158

Prediction of KRAS mutation as a therapeutic indicator

KRAS

MRI

Radiomics (texture features)

Mann–Whitney U test

The chi-square test or Fisher exact test.

Li et al. (25)

Retrospective study

China \ 2021

368

Prediction of the microsatellite instability (MSI) status

MLH1

MSH2

 MSH6

PMS2

CT scan

Radiomics (intensity histogram, gray level co-occurrence matrix, gray level run length matrix, neighbor intensity difference, and shape)

Logistic regression,

Support vector machine (SVM), Random forest, Gradient

boosting machine (GBM), Naive Bayes

Crimì et al. (26)

Retrospective study

Italy \ 2022

47

Prediction of the presence of specific genetic mutations associated with CRC

MSI

CT scan

Radiomics [derived from histogram, run length matrix (RLM), gray-level co-occurrence matrix (GLCM), gray-level run length matrix (GLRLM), and neighboring gray-level dependence matrix (NGLDM)]

Mann-Whitney U test and Bonferroni correction

Cho et al. (27)

Retrospective study

Republic of Korea \ 2017

93

Prediction of KRAS mutations

KRAS

18F-FDG PET/CT

Quantitative Analysis (SUVmax, SUVmean, MTV, and TLG)

the χ2 test or Mann-Whitney U test

Chen et al. (28)

Retrospective study

Taiwan \ 2013

121

Prediction of KRAS mutations

KRAS

18F-FDG PET/CT

SUVmax, SUVmean, MTV

using a Mann-Whitney U test and logistic regression analysis

Yeo et al. (29)

Retrospective study

Republic of Korea \ 2015

46

Whether DCE-MRI correlates with angiogenesis and the biological aggressiveness of rectal cancer

EGFR

MRI

Quantitative Analysis( Ktrans, kep, ve, and iAUC)

Student’s t-test and analysis of variance (ANOVA)

Mao et al. (30)

Retrospective study

China\ 2019

49

Prediction of KRAS mutations

KRAS

18F-FDG PET/CT

Quantitative Analysis( SUVearly, SUVdelayed, DSUVmax)

Chi-square test or Mann–Whitney U test

Taguchi et al. (31)

Retrospective study

Japan \ 2019

40

Prediction of KRAS mutations

KRAS

CT scan

Quantitative Analysis [CT texture parameters (Skewness, Kurtosis, Entropy, Energy, Homogeneity,..) and 18F-FDG PET parameter) SUVmax)]

two-tailed independent t-test and the Mann-Whitney U test

Zhong et al. (32)

Retrospective study

China \ 2022

1601

Prognostic prediction model for colorectal cancer

KRAS

CT scan

Radiomics (radiomics features)

Unsupervised deconvolution analysis

Wu et al. (33)

Cohort study

China \ 2019

279

Predicting KRAS status in patients with colorectal cancer (CRC)

KRAS

CT scan

Radiomics and deep learningn (hand-crafted features and deep learning features)

using multivariable

logistic regression analysis

Seth et al. (34)

Retrospective study

Canada \ 2021

20

Investigating the association between TTE and

genetic mutations

APC

ARIDA1

TP53

AKT1

ATM

BRAF

CTNNB1

EGFR

FBXW7

KRAS

NRAS

PIK3

CAPTENSMAD

MRI

Quantitative Analysis [target tumor enhancement (weak and strong TTE)]

Kruskal-Wallis test and Mann-Whitney and/or t-test

Cui et al. (35)

Retrospective study

China \ 2020

304

prediction of KRAS mutation

KRAS

MRI

Radiomics (radiomics feature)

mainly consist of univariate statistical tests

Cao et al. (36)

Retrospective study

China\ 2020

124

prediction of KRAS mutation

KRAS

CT scan

Quantitative analysis( DESCT parameters

Including the monochromatic CT value, iodine, water, and effective atomic number

logistic regression analysis

Cui et al. (37)

Retrospective study

China \ 2019

148

prediction of KRAS mutations

KRAS

MRI

Quantitative analysis (DKI and ADC)

Student’s t-test or Mann-Whitney U test and receiver operating characteristic (ROC) curve analysis

Granata et al. (38)

Retrospective study

Italy \ 2020

106

Identification of RAS mutation in colorectal liver metastasis

KRAS

NRAS

MRI

Quantitative analysis (ADC-, IVIM- and DKI)

Wilcoxon-Mann-Whitney U tests for receiver operating

characteristic (ROC) analyses

Chen et al. (39)

Retrospective study

Taiwan \ 2015

103

Investigating the association between genetic mutations and 18F-FDG PET in colorectal cancer (CRC).

TP53

 KRAS

APC

BRAF

PIK3CA

18F-FDG PET/CT

Quantitative analysis (SUVmax, SUVmean, MTV, and TLG)

Mann-Whitney U test

and logistic regression analysis

Promsorn et al. (40)

Retrospective study

Thailand \ 2021

113

prediction of KRAS mutation status

KRAS

CT scan

Qualitative and quantitative analyses (ATL, LTL, ATL/LTL, tumor location, gross tumor patterns, tumor margins, tumor enhancement patterns, T staging, regional lymph node metastasis, distant lymph node metastasis, or distal organ metastasis)

t test

Mann-Whitney U test

Liu et al. (41)

Retrospective study

China \ 2021

134

Prediction of metastasis in colorectal cancer

ABCB1

TP53

ATM

MYC

CT scan

Radiomics (radiomics feature)

Multivariable

logistic regression analyses

Popovic et al. (42)

Retrospective study

USA \ 2020

37

Explore the predictive value of 2-[18F]FDG uptake according to KRAS mutation status

KRAS mutation

2-[18F]FDG PET/C

quantitative analysis(SUV (HERMES), SUV (MIM), PVEC)

Student’s t test

Wilcoxon rank-sum test

Logistic regression and receiver operating characteristics (ROC)

Krikelis et al. (43)

Retrospective study

Greece \ 2014

44

prediction of KRAS mutation status

GLUT1

KRAS

18F-FDG PET/CT

quantitative analyses ( SUVmax)

t-test

Kruskal–Wallis test

Fisher’s exact test of Spearman’s Rho

Chen et al. (44)

Retrospective study

Taiwan \ 2019

74

Investigating the association between genetic mutations and radionics in 18F-FDG PET/CT

 In colorectal cancer (CRC)

KRAS

TP53

APC

18F-FDG PET/CT

quantitative analyses ( SUVmax, MTV)

Receiver- operating characteristic (ROC)

Mann-Whitney U test

Spearman’s rank correlation coefficient

Zhang et al. (45)

Retrospective study

China \ 2021

83

Analyzing the association between MRI radiomic features and KRAS status in LARC patients.

KRAS

NRAS

BRAF

MRI

Radiomics (radiomics feature)

The least absolute shrinkage and selection operator (LASSO) regression

Miles et al. (46)

prospective study

United Kingdom \ 2014

33

Exploring the potential of multifunctional imaging in providing a KRAS signature

KRAS

PET/CT

quantitative analysis[18F-FDG uptake (18F-FDG maximum standardized uptake value (SUVmax)], CT texture (expressed as mean of positive pixels (MPP)]

CT Texture Analyses (CT TA) CT TA was performed using the following parameters: TexRAD

Recursive decision tree

Monte Carlo analysis

He et al. (47)

Retrospective study

China \ 2020

157

prediction of KRAS mutation status

KRAS

CT scan

Radiomics (radiomics feature)

LASSO regression-

radiomics model using a random forest classifier (RFC)

Shi et al. (48)

Retrospective study

China\ 2020

159

predicting the RAS(KRAS and NRAS) and BRAF gene mutation statuses

KRAS

NRAS

BRAF

CT scan

Radiomics( Gray Level Co-occurrence Matrix (GLCM), gray level size zone matrix (GLSZM), Gray Level Run Length Matrix (GLRLM), neighboring Gray Tone Difference Matrix (NGTDM), and gray level dependence matrix (GLDM))

Fisher’s exact test

He et al. (49)

Retrospective study

China \ 2021

85

association between KRAS/NRAS /BRAF mutations and metabolic parameters of pretreatment 18FFDG-PET/CT in colorectal cancer

KRAS

NRAS

BRAF

18F-FDG PET/CT

quantitative analyses (SUVmax)

Mann–Whitney

U test.

Sh et al. (50)

prospective study

Egypt\ 2021

 38

 correlation between 18F-FDG PET/CT imaging and KRAS expression in mCRC

KRAS mutational

18F-FDG PET/CT

quantitative analysis (maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG) and metabolic tumor volume (MTV))

independent samples t-test

Mann-Whitney U test)

Li et al. (51)

Retrospective study

China\ 2021

173

Prediction of

Microsatellite instability in colorectal tissue

Cancer

MSI-H

MSS

18F-FDG PET/CT

Radiomics (radiomics feature)

multivariate random

forest selection and univariate relevancy tests

Balanced Bagging

the area under

The curve (AUC)

Horvat et al. (52)

Retrospective study

USA\ 2019

65

To investigate associations between genetic mutations and qualitative and quantitative features on magnetic resonance imaging (MRI) in rectal adenocarcinoma

APC

TP53

KRAS

PIK3CA

BRCA2

ATM

SOX9

FLT4

MRI

Quantitative and qualitative analyses [Tumor Localization, Tumor Length (cm), Mucin Content, CRM distance (mm), CRM status, DWI restriction, Early perfusion on DCE, Metastatic lymph nodes]

Fisher’s exact test and Wilcoxon rank sum test

Badic et al. (53)

Retrospective study

Franche\ 2019

64

the relationship between imaging radiomic features and

gene expression changes

ABCB1

ABCC2

ABCG2

ALDH1A1

CD166 (ALCAM)

CDKN1A

INHBB

CT scan

Radiomics [Flatness, Sum entropy (SENTR), entropy from Gray-level-co-occurrence-matrix (EntropyGLCM E), Gray-level non-uniformity (GLNUL)]

 Kruskal-Wallis test

Ma et al. (54)

Retrospective study

USA\ 2022

230

explore whether the preoperative CT radionics can predict

Status of microsatellite instability (MSI) in colorectal cancer (CRC)

LH1,

 MSH2

 MSH6

PMS2

CT scan

Radiomics ( first-order statistics, shape, gray-level co-occurrence matrix (GLCM), gray-level dependence matrix (GLDM), gray-level size zone matrix (GLSZM), gray-level run length matrix (GLRLM), and neighboring gray-level tone difference matrix (NGTDM))

inter-class correlation

coefficient

intraclass correlation coefficient

Negreros-Osuna et al. (55)

Retrospective study

Mexico\ 2020

145

To explore the potential of radionics texture features as biomarkers of BRAF mutation

BRAF

CT scan

Radiomics (texture features: mean, SD, mean value of positive pixels (MPP), skewness, kurtosis, and entropy)

Laplacian-of-Gaussian filters

Wilcoxon rank sum

Granata et al. (56)

Retrospective study

Italy\ 2021

52

Investigating the association between RAS mutation status and radiomics-derived data using contrast-enhanced magnetic resonance imaging (CE-MRI) in liver metastases

KRAS

NRAS

MRI

Radiomics (texture features)

Wilcoxon-Mann-Whitney U Test Receiver Operating Characteristic (ROC)

Kawada et al. (57)

Retrospective study

Japan\ 2015

55

to investigate whether KRAS status is associated with 18F-FDG accumulation in metastatic CRC.

and whether 18F-FDG PET/CT can be used to predict

KRAS status of metastatic CRC.

KRAS

18F-FDG PET/CT

quantitative analysis(SUVmax)

Mann–Whit-

ney U test

Mao et al. (30)

Retrospective study

China\ 2018

49

To investigate the association between meta-

Bolic parameters of dual time point 18 F-FDG PET/CT and KRAS mutation status in colorectal liver metastases (CRLM).

KRAS

18F-FDG PET/CT

quantitative analysis (SUVearly, SUVdelayed, DSUVmax and RI)

Uni-variate

multi-variate analyses

Arslan et al. (58)

Retrospective study

Turkey\ 2020

83

Investigating the association between FDG uptake patterns and

18 F-FDG PET/CT imaging and KRAS mutation

KRAS

18F-FDG PET/CT

quantitative analyses (SUVmax)

Mann-Whitney U

Kruskal-Wallis tests

Pearson’s test.

KRAS: Kirsten Rat Sarcoma Viral Oncogene Homolog, NRAS: Neuroblastoma RAS Viral, EIF2S2: Eukaryotic Translation Initiation Factor 2 Subunit 2 GLUTI: Glucose Box 1, BRAF: B-Raf proto-onkogen, MSI: Microsatellite Instability, PECAMI: Platelet Endothelial Cell Adhesion Molecule 1, AIFI: Activated Inducible Family of Immune receptors, ISG20: Interferon-Stimulated Gene 20, TLR8: Toll-like Receptor 8, CDKN2A: Cyclin-Dependent Kinase Inhibitor 2A, ATM: Ataxia-Telangiectasia Mutated, ABCG2: ATP Binding Cassette Subfamily G Member 2, ABCB1: ATP Binding Cassette Subfamily B Member 1, AMCC2: Armadillo Motif Containing 2, ABCG2: ATP Binding Cassette Subfamily G Member 2, ALDHIA1: Aldehyde Dehydrogenase 1 Family Member A1, CD166: Cluster of Differentiation 166, INHBB: Inhibin Beta B, CDKNIA: Cyclin-Dependent Kinase Inhibitor 1A, ARIDA1: AT-rich interaction domain 1A, CTNNBI: Catenin Beta 1, FBXW7: F-box and WD-40 domain protein 7, BRAC2: Breast Cancer 2, FLT: Fms-like Tyrosine Kinase

After searching and retrieving sources based on the search strategies, duplicate articles were removed using EndNote software. Then, the titles and abstracts of the articles were checked, and irrelevant articles were removed. This screening was performed by two experts in the field of Medical Informatics, and any disagreement was resolved by consensus with a third expert. In the next step, the full texts of the articles were reviewed. Finally, articles that were in line with the purpose of the study were selected. The quality of the selected articles was measured using the Strengthening the Reporting of Observational Studies in Epidemiology checklist, and articles with insufficient quality were excluded from the study ().

The data collection tool consisted of a data extraction form including the type of study, first author’s name, country and year of publication, purpose of the study, sample size, molecular factors, type of modality, image characteristics, statistical method for prediction, and summary of findings. Furthermore, a narrative synthesis method was used for data analysis.

Statistical Analysis

In this study, basic descriptive statistics, including the sum and mean, were used to analyze the results. Additionally, when the area under the ROC curve was calculated to predict molecular alterations in the studies, the weighted average was computed based on the molecular alterations and modality.

Patient Consent Information

This systematic review was based on data from previously published studies, and new patient data were not collected. Therefore, patient consent was not required.

Results

A summary of the study review process based on the PRISMA guidelines is presented in .

Figure 1
Figure 1. The study selection process
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Molecular Factors

Research has shown that many molecular factors contribute to the treatment of colorectal cancer. Some of the key molecular factors (genes/oncogene/suppressor) in colorectal cancer are KRAS, BRAF, NRAS, PIK3CA, and TP53 (). Various molecular factors were predicted in the selected studies; however, in 68% of them, KRAS changes were investigated. The frequency of the investigated molecular factors is shown in .

Figure 2
Figure 2. Frequency of the predicted molecular factors

KRAS: Kirsten Rat Sarcoma Viral Oncogene Homolog, NRAS: Neuroblastoma RAS Viral, EIF2S2: Eukaryotic Translation Initiation Factor 2 Subunit 2 GLUTI: Glucose Box 1, BRAF: B-Raf proto-onkogen, MSI: Microsatellite Instability, PECAMI: Platelet Endothelial Cell Adhesion Molecule 1, AIFI: Activated Inducible Family of Immune receptors, ISG20: Interferon-Stimulated Gene 20, TLR8: Toll-like Receptor 8, CDKN2A: Cyclin-Dependent Kinase Inhibitor 2A, ATM: Ataxia-Telangiectasia Mutated, ABCG2: ATP Binding Cassette Subfamily G Member 2, ABCB1: ATP Binding Cassette Subfamily B Member 1, AMCC2: Armadillo Motif Containing 2, ABCG2: ATP Binding Cassette Subfamily G Member 2, ALDHIA1: Aldehyde Dehydrogenase 1 Family Member A1, CD166: Cluster of Differentiation 166, INHBB: Inhibin Beta B, CDKNIA: Cyclin-Dependent Kinase Inhibitor 1A, ARIDA1: AT-rich interaction domain 1A, CTNNBI: Catenin Beta 1, FBXW7: F-box and WD-40 domain protein 7, BRAC2: Breast Cancer 2, FLT: Fms-like Tyrosine Kinase

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Modalities

Recently, different imaging modalities have been used for predicting molecular factors in colorectal cancer. The most important modalities are MRI, CT, and positron emission tomography (PET) (). The frequency of modalities used in the included studies is presented in .

Figure 3
Figure 3. Frequency of modalities used in the included studies

PET/CT: Positron emission tomography/computed tomography, MRI: Magnetic resonance imaging

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Analyzing Technics

The reviewed studies employed various imaging modalities, such as CT, MRI, and 18F-FDG PET/CT, and utilized radionics and quantitative analysis techniques to predict molecular alterations in colorectal cancer. Key features analyzed included texture features, maximum standardized uptake value (SUVmax), SUVmean, metabolic tumor volume, total lesion glycolysis, and various radionics features derived from intensity, shape, and texture matrices like GLCM, GLRLM, GLSZM, and NGLDM. The statistical methods varied, including Spearman correlation, Mann-Whitney U test, logistic regression, and machine learning models like random forest and SVM.

Area Under the Receiver Operating Characteristic (ROC) Curve for Predicting Molecular Factors Based on Image

In 20 studies, the area under the ROC curve (AUC) was reported for predicting KRAS (n=13), MSI (n=4), BRAF (n=2), and TP53 (n=1) changes. The weighted average of this index (relative to the number of samples) for each molecular factor is presented in . presents the relationships among the three modalities used in studies on molecular factors.

Table 3. Area under the receiver operating characteristic curve of different modalities for predicting molecular factors

Molecular factors

Modality

Number of articles

Average sample size (SD of sample size)

AUC mean*

KRAS

MRI

5

153.6 (82.2)

0.77

CT scan

4

120 (48.23)

0.82

PET/CT

4

82.5 (48.9)

0.73

ALL

13

121.4 (68.5)

0.78

MSI

MRI

0

0 (0)

0

CT scan

3

215 (131)

0.80

PET/CT

1

173 (0)

0.83

ALL

4

194 (115.4)

0.81

BRAF

MRI

1

159 (0)

0.79

CT scan

1

61 (0)

0.83

PET/CT

0

0 (0)

0

ALL

2

110 (0)

0.80

TP53

MRI

0

0 (0)

0

CT scan

0

0 (0)

0

PET/CT

1

74 (0)

0.71

ALL

1

74 (0)

0.71

*AUC mean, SD: Standard deviation, AUC: Area under the curve, MRI: Magnetic resonance imaging, CT: Computed tomography, PET: Positron emission tomography, ALL: Acute lymphoblastic leukemia, MSI: Mikrosatellit Instabilitesi, BRAF: B-Raf proto-oncogene, serine/threonine kinase, TP53: Tumor Protein 53

Table 4. Relationship between molecular alterations and image quality by modality

Modality

Gene

Positive*

Negative**

Total

Number of articles

Average sample size (SD of sample size)

Number of articles

Average of sample size (SD of sample size)

Number of articles

18F-FDG PET/CT

KRAS

12

78.17 (34.24)

1

44 (0)

13

NRAS

2

118 (33)

0

0 (0)

1

EIF2S2

1

42 (0)

0

0 (0)

2

GLUT1

1

42 (0)

1

44 (0)

2

TP53

2

88.5 (14.5)

0

0 (0)

2

APC

1

74 (0)

1

103 (0)

2

BRAF

1

85 (0)

1

103 (0)

1

PIK3CA

0

0 (0)

1

103 (0)

1

MSI

1

173 (0)

0

0 (0)

1

CT scan

PECAM1

1

71 (0)

0

0 (0)

1

PRDM1

1

71 (0)

0

0 (0)

1

AIF1

1

71 (0)

0

0 (0)

1

IL10

1

71 (0)

0

0 (0)

1

ISG20

1

71 (0)

0

0 (0)

1

TLR8

1

71 (0)

0

0 (0)

6

KRAS

6

109 (43.1)

0

0 (0)

2

NRAS

2

110 (49)

0

0 (0)

3

BRAF

3

121.6 (43.33)

0

0 (0)

3

MSI

3

215 (131)

0

0 (0)

1

CDKN2A

1

134 (0)

0

0 (0)

1

TP53

1

134 (0)

0

0 (0)

1

ATM

1

134 (0)

0

0 (0)

1

MYC

1

134 (0)

0

0 (0)

1

ABCB1

1

64 (0)

0

0 (0)

1

ABCC2

1

64 (0)

0

0 (0)

1

ABCG2

1

64 (0)

0

0 (0)

1

ALDH1A1

1

64 (0)

0

0 (0)

1

CD166

1

64 (0)

0

0 (0)

1

INHBB

1

64 (0)

0

0 (0)

1

CDKN1A

1

64 (0)

0

0 (0)

1

MRI

KRAS

8

118.2 (86.8)

1

65 (0)

9

EGFR

2

33 (13.2)

0

0 (0)

2

APC

1

20 (0)

1

65 (0)

2

ARIDA1

1

20 (0)

0

0 (0)

1

TP53

2

42.5 (22.5)

0

0 (0)

2

AKT1

1

20 (0)

0

0 (0)

1

ATM

2

42.5 (22.5)

0

0 (0)

2

BRAF

1

20 (0)

1

83 (0)

2

CTNNB1

1

20 (0)

0

0 (0)

1

FBXW7

1

20 (0)

0

0 (0)

1

NRAS

3

65.4 (36.3)

1

65 (0)

4

PIK3

1

20 (0)

1

65 (0)

2

BRCA2

0

0 (0)

1

65 (0)

1

SOX9

0

0 (0)

1

65 (0)

1

FLT4

0

0 (0)

1

65 (0)

1

*Positive=There is a correlation between image features and molecular alterations, **Negetive=There is no correlation/relationship between image features and molecular alterations, KRAS: Kirsten Rat Sarcoma Viral Oncogene Homolog, NRAS: Neuroblastoma RAS Viral, EIF2S2: Eukaryotic Translation Initiation Factor 2 Subunit 2 GLUTI: Glucose Box 1, BRAF: B-Raf proto-onkogen, MSI: Microsatellite Instability, PECAMI: Platelet Endothelial Cell Adhesion Molecule 1, AIFI: Activated Inducible Family of Immune receptors, ISG20: Interferon-Stimulated Gene 20, TLR8: Toll-like Receptor 8, CDKN2A: Cyclin-Dependent Kinase Inhibitor 2A, ATM: Ataxia-Telangiectasia Mutated, ABCG2: ATP Binding Cassette Subfamily G Member 2, ABCB1: ATP Binding Cassette Subfamily B Member 1, AMCC2: Armadillo Motif Containing 2, ABCG2: ATP Binding Cassette Subfamily G Member 2, ALDHIA1: Aldehyde Dehydrogenase 1 Family Member A1, CD166: Cluster of Differentiation 166, INHBB: Inhibin Beta B, CDKNIA: Cyclin-Dependent Kinase Inhibitor 1A, ARIDA1: AT-rich interaction domain 1A, CTNNBI: Catenin Beta 1, FBXW7: F-box and WD-40 domain protein 7, BRAC2: Breast Cancer 2, FLT: Fms-like Tyrosine Kinase

Discussion

In this systematic review, 41 studies related to the use of radiogenomics in colorectal cancer for predicting molecular factors were examined. According to the results, 42% of the studies were conducted in China, and 71% of the studies were conducted between 2019 and 2022. According to recent progress in understanding the relationship between molecular factors and response to drugs, the emergence of the concept of radiogenomics, and the increase in the quality of different modalities in recent years, such studies have received much attention from researchers ().

Furthermore, most studies have investigated the association between medical images and RAS (KRAS, NRAS), BRAF, TP53, activated protein C (APC), and MSI alterations with a frequency of 35, 28, 8, 7, 5, 4, and 4, in that order. RAS mutations (KRAS/NRAS) are common in colorectal cancer and can affect treatment outcomes. These mutations are associated with resistance to anti-epidermal growth factor receptor monoclonal antibodies and limit their efficacy. Targeted therapies that specifically inhibit mutant KRAS are being developed to overcome this resistance (, ). RAS mutations have been investigated in 35 studies, and the relationship between image characteristics and molecular factors was significant in 33 studies. Moreover, 13 studies used image analysis to report the area under the ROC curve for predicting KRAS whose weighted average, relative to the number of samples, was 78%, which is in contrast with the result of the study by Kim et al. (), where the same value for 9 studies was 69%. This difference can be attributed to the research period. Additionally, regarding recent advances in imaging and image-analyzing methods, the higher level under the ROC curve in the present study can be justified.

BRAF mutations, particularly V600E mutation, are found in a subset of colon cancers and are associated with poor prognosis. In recent years, BRAF inhibitors have shown promise in the treatment of colorectal cancer (with BRAF mutation), either alone or in combination with other drugs (). BRAF mutation has been examined in 7 studies, and the relationship between image features and BRAF mutation was significant in 6 studies. In 2 studies image analyzing was used to report the area under the ROC curve for predicting BRAF whose weighted average, in relation to the number of samples, was 80%. In their study, Santhanam et al. () identified 7 studies on the relationship between 18F-FDG PET/CT characteristics and BRAF mutation in thyroid cancer, and the results indicated a significant relationship between them.

TP53 is a tumor suppressor that plays an important role in maintaining genomic stability. TP53 mutations are frequently found in colorectal cancer, and they are associated with worse prognosis and resistance to therapy. New therapies targeting TP53 mutations (such as gene therapies and small molecule inhibitors) are being investigated to overcome these challenges (). The TP53 mutation has been investigated in 5 studies where the relationship between image characteristics and TP53 mutation was significant. In another study, image analysis was used, and the area under the receiver operating characteristic curve for predicting TP53 was 71%. In their review study, Seow et al. () investigated the relationship between radiomic features and molecular factors and found a correlation between TP53 mutation and radiomic features.

MSI is observed in approximately 15% of colorectal cancers. From the treatment point of view, high MSI colorectal cancers exhibit particular responses to immunotherapy; they respond better to immune checkpoint inhibitors (). Image analysis was used in 4 studies to report the area under the receiver operating characteristic curve for MSI, with an average of 81%. Similarly, Le et al. () identified 8 studies related to the use of radionics for the prediction of MSI, and the average area under the ROC curve was 83%.

As a suppressor, APC plays an important role in the development of colon cancer and is used to identify people at risk or diagnose the disease. In addition, Wnt pathway inhibitors therapies may be appropriate for APC-mutated colorectal cancer (). APC mutation has been examined in 4 studies in which the relationship between image feature and APC changes was significant. A review study by Aghabozorgi et al. (), on the relationship between radionics features and histopathological changes indicated a relationship between APC mutation and radionics features.

MRI, CT scanning, and 18F-FDG PET/CT were used in 10, 15, and 16 studies, respectively. MRI is a non-invasive imaging technique that provides high-resolution anatomical images. It provides good soft-tissue contrast and is useful for evaluating colorectal tumor characteristics, such as size, location, and invasion depth (, ). According to the performance of MRI, this modality is mostly used for predicting RAS (KRAS/NRAS).

There was also a significant relationship between MRI and molecular factors in all selected studies, except for Horvat et al. () study in which qualitative characteristics of images were related to molecular factors; however, no significant relationship was found between quantitative characteristics and molecular factors due to the limitations presented in the study.

The analysis of radionics and quantitative features across various imaging modalities, such as CT, MRI, and 18F-FDG PET/CT, revealed the potential for predicting molecular alterations in colorectal cancer. Radiomics features, including texture and intensity metrics, can help improve the prediction accuracy. Techniques like GLCM, GLRLM, and GLSZM combined with statistical methods such as logistic regression and machine learning models demonstrate varying degrees of success in identifying key genetic mutations such as KRAS, NRAS, BRAF, TP53, and MSI. However, the heterogeneity in methodologies and sample sizes across studies underscores the need for standardized imaging protocols and radiomic analysis techniques.

Study Limitations

Because the studies were conducted considering a small sample size and were still in their early stages, multi-center prospective studies with a larger number of participants should be conducted.

Conclusion

This scoping review highlights the promising potential of radiogenomics in predicting molecular alterations in colorectal cancer through noninvasive imaging modalities. Our comprehensive analysis of 41 high-quality studies revealed that various imaging techniques, including CT scanning, MRI, and 18F-FDG PET/CT, can effectively predict key molecular changes, such as KRAS, NRAS, BRAF, TP53, and MSI. The primary focus has been on CT scanning and MRI, with texture features and radionics playing critical roles in enhancing predictive accuracy. Despite these advancements, the field is still in its nascent stages, with varying levels of predictive performance and sample sizes. The heterogeneity of methodologies and the need for larger, more diverse cohorts underscore the need for further research. Standardization of imaging protocols and radiomic analysis, along with cross-institutional collaborations, will be crucial for validating and refining these predictive models. In conclusion, radiogenomics has significant potential to revolutionize the prediction of molecular alterations in colorectal cancer, facilitating personalized treatment approaches. Continued research and technological advancements are essential for fully realizing its clinical implications and improving patient outcomes.

Footnotes

Ethics

Ethics Committee Approval: This study did not require ethical approval as it did not involve interaction with patients or human subjects.

Informed Consent: This systematic review was based on data from previously published studies, and new patient data were not collected. Therefore, patient consent was not required.

Authorship Contributions

Concept: S.M., H. E., R.R., Design: S.M., H. E., R.R., Data Collection or Processing: S.M., H.M., F.F., Analysis or Interpretation: S.M., H. E., A.H., Literature Search: S.M., A.H., H.M., F.F., R.B., Writing: S.M., H. E., R.R., R.B.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study has received no financial support.

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