Relationship between KRAS mutation and diffusion tensor imaging features in brain metastases due to colorectal cancer; preliminary study
Mehmet Ali Gultekin, Haci Mehmet Turk, Temel Fatih Yilmaz, Abdusselim Adil Peker, Mehmet Besiroglu, Atakan Topcu, Ganime Coban, Dilek Hacer Cesme.
Identifying Kirsten rat sarcoma (KRAS) mutation status is important for metastatic colorectal cancer treatment. Validating KRAS mutation profile on neuroimaging without histopathologic analysis would be beneficial. We aimed to differentiate Kirsten rat sarcoma (KRAS) gene mutation profile according to diffusion tensor imaging (DTI) metrics obtained from colorectal brain metastases (CRBM). Total of 8 patients with 17 CRBM included with known KRAS gene mutation status. All patients were categorized into two groups according to the KRAS mutation status as positive (+) (n: 5, 11 lesions) and negative (-) (wild type) (n: 3, 6 lesions). DTI values of the BMs were evaluated by consensus of two radiologists. Apparent diffusion coefficient (ADC), normalized apparent diffusion coefficient (nADC) and fractional anisotropy (FA) values of the two groups were compared. For comparison the Mann-Whitney U test was used. KRAS mutation (+) group showed significantly lower ADC and nADC values on CRBM rather than the wild-type. Comparison of the FA values of the two groups did not reveal any statistical significance. In conclusion, decreased ADC and nADC values of CRBM are correlated with presence of KRAS mutation. Lower ADC and nADC values obtained from CRBM can be utilized to insight KRAS mutation profile.
Key words: Kirsten rat sarcoma gene mutation, diffusion tensor imaging, colorectal cancer, brain metastasis