# The value of T1 mapping and intravoxel incoherent motion parameters in predicting PD-L1 expression and dynamically monitoring immunotherapy in advanced lung cancer

## TL;DR

This study explores how T1 mapping and IVIM-DWI imaging can predict PD-L1 expression and track immunotherapy response in lung cancer patients.

## Contribution

The study introduces T1 mapping and IVIM-DWI as potential imaging biomarkers for monitoring immunotherapy in lung cancer.

## Key findings

- T1 and ΔADC values showed high AUCs (0.871 and 0.886) in predicting immunotherapy efficacy.
- Effective immunotherapy was associated with lower T1 and higher ADC values post-treatment.
- IVIM-DWI parameters showed subtle changes during treatment, differing between effective and ineffective groups.

## Abstract

To investigate the value of T1 mapping and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) quantitative parameters in predicting PD-L1 expression and dynamically monitoring immunotherapy efficacy in advanced lung cancer.

23 patients pathologically diagnosed with advanced lung cancer were collected. Patients underwent T1 mapping and IVIM examinations pre- and post-immunotherapy. The relationship between PD-L1 expression levels and quantitative parameters was analyzed. The changes of quantitative parameters during treatment were compared between the effective and ineffective groups. The predictive value of quantitative parameters for immunotherapy efficacy was analyzed using area under the curve (AUC).

In terms of predicting PD-L1 expression, there were no significant differences in the T1, apparent diffusion coefficient (ADC), perfusion fraction (f), true diffusion coefficient (D), and pseudo-diffusion coefficient (D*) values between the positive and negative groups (all p>0.05). After immunotherapy, the effective group showed a lower T1 value (p = 0.008) and a higher ADC value (p = 0.013), with slight increases in f, D, and D* values. The ineffective group had slight increases in T1 and D values, and slight decreases in ADC, f, and D* values. Compared to the ineffective group, the effective group had a lower post-treatment T1 value (p = 0.019) and a higher ΔADC value (p = 0.031). The AUCs of the post-treatment T1 and ΔADC values in predicting immunotherapy efficacy were 0.871 and 0.886, respectively.

T1 mapping and IVIM quantitative parameters may reflect potential trends in predicting PD-L1 expression, have certain value in monitoring the dynamic changes during immunotherapy in advanced lung cancer, and are expected to provide meaningful imaging biomarkers for individualized immunotherapy decision-making.