Could IVIM and ADC help in predicting the KRAS status in patients with rectal cancer?
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To evaluate the diagnostic potential of DW-MRI relative parameters for differentiation of rectal cancers with different Kirsten rat sarcoma viral oncogene homologue (KRAS) mutation status.
Fifty-one patients with rectal cancer underwent diffusion-weighted MR imaging with eight b values. ADCs (including Max-ADC, Min-ADC and Mean-ADC) and IVIM parameters (D, pure diffusion; f, perfusion fraction; D*, pseudodiffusion coefficient) were respectively calculated by mono- and bi-exponential analysis. Patients were stratified into two groups: KRAS wild type and mutant. The DW-MRI-derived parameters between the KRAS wild-type group and KRAS mutant group were compared using the Mann-Whitney U test. Receiver-operating characteristic (ROC) analysis of discrimination between KRAS wild-type and KRAS mutant rectal cancer was performed for the DW-MRI-derived parameters.
Max-ADC, Mean-ADC and D values were significantly lower in the KRAS mutant group than in the KRAS wild-type group, whereas a higher D* value was demonstrated in the KRAS mutant group. According to the ROC curve, Mean-ADC and D* values showed moderate diagnostic significance with the AUC values of 0.756 and 0.710, respectively. The cut-off values for Mean-ADC and D* were 1.43 × 10-3mm2/s and 26.58 × 10-3mm2/s, respectively.
Rectal cancers had distinctive diffusion/perfusion characteristics in different KRAS mutation statuses. The DW-MRI-derived parameters, specifically Mean-ADC and D*, show a moderate diagnostic significance for KRAS status.
• Rectal cancers with different KRAS mutation statuses demonstrated distinctive diffusion/perfusion characteristics.
• Max-ADC, Mean-ADC and D values were lower in the KRAS mutant group.
• A higher D* value was demonstrated in the KRAS mutant group.
• IVIM-DW MRI may potentially help preoperative KRAS mutant status prediction.
KeywordsRectal cancer Magnetic resonance imaging Diffusion Perfusion Mutation
Apparent diffusion coefficient
Epidermal growth factor receptor
Intravoxel incoherent motion
Kirsten rat sarcoma viral oncogene homologue
Magnetic resonance imaging
National Comprehensive Cancer Network
Region of interest
Turbo spin echo
This work was supported by grants from the National Natural Science Foundation of China (no. 81501469) and the Health Industry Special Scientific Research Project of the National Health and Family Planning Commission of the People’s Republic of China (no. 201402019).
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Hongliang Sun.
Conflict of interest
The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article.
Statistics and biometry
One of the authors has significant statistical expertise.
No complex statistical methods were necessary for this paper.
Written informed consent was waived in this study.
Institutional Review Board approval was obtained.
• performed at one institution
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