Association between apparent diffusion coefficient and KI67 in brain tumors: a systematic review

Certain histological variants of tumors have a correlation between the values of the apparent diffusion coefficients (ADC), cell density and the proliferative activity index MIB-I (Ki67). The results of studies on the relationship between the values of the ADC and the Ki67 index in brain tumors are ambiguous and largely contradictory. The purpose of this study was to perform a systematic review based on the results of clinical studies that examined the relationship between ADC values and the Ki67 proliferative activity index in brain tumors. Material and Methods. Clinical studies were searched in the databases Pubmed, EMBASE, Cohrane Library and eLibrary published from January 2000 to January 2020, which studied the relationship between ADC values and the Ki67 proliferative activity index in brain tumors. Results. A systematic review included 17 retrospective cohort nonrandomized clinical studies. The average value of the coefficient of reliable correlation between ADC and the mitotic index Ki67 in the group of meningiomas was -0.493. The indicated dependence was more often found in groups of typical (MI) and atypical (MII) brain meningiomas. The average coefficient of statistically significant correlation between the studied parameters in the group of brain gliomas was -0.443. The relationship between the ADC values and the Ki67 proliferative activity index was observed both in the glioma group of low (GI-II) and high (GIII-IV) grade of malignancy. In groups of patients with pituitary adenomas, primary lymphomas and brain metastases, the relationship between the studied parameters was not reliably confirmed. Conclusion. The use of diffusion-weighted magnetic resonance imaging techniques with subsequent calculation of ADC values can be recommended for use in the clinical practice of oncologists in order to assess the proliferative potential of brain meningiomas and gliomas.