Correlation Between Minimum Apparent Diffusion Coefficient (ADC_min) and Tumor Cellularity: A Meta-analysis.

Area of Science:

• Radiology and Imaging
• Oncology
• Medical Physics

Background:

• Diffusion-weighted imaging (DWI) is an MRI technique evaluating water diffusion for insights into tissue microstructure and cell density.
• Increased cell density restricts water diffusion, decreasing the apparent diffusion coefficient (ADC).
• ADC has sub-parameters including ADC minimum (ADCmin), ADC mean (ADCmean), and ADC maximum (ADCmax).

Purpose of the Study:

• To conduct a meta-analysis summarizing correlation coefficients between ADCmin and tumor cellularity.
• To evaluate the potential of ADCmin as a parameter for estimating tumor cellularity based on large patient data.

Main Methods:

• MEDLINE database search for studies correlating ADC and cell count in tumors up to September 2016.
• Inclusion of 12 publications involving 317 patients, focusing exclusively on ADCmin data.
• Spearman's correlation coefficient was used for analysis; Pearson coefficients were converted to Spearman's.

Main Results:

• A pooled correlation coefficient (ρ) of -0.59 (95% CI: -0.72 to -0.45) was found between ADCmin and cellularity.
• Significant heterogeneity was observed (Tau²=0.04, p<0.0001; I²=73%).
• The overall effect was statistically significant (Z=8.67, p<0.00001).

Conclusions:

• ADCmin demonstrates a moderate correlation with tumor cellularity.
• The correlation coefficient for ADCmin is not superior to that of ADCmean.
• ADCmin does not appear to be a better indicator of tumor cellularity compared to ADCmean.