# Serial T1 and T2 measurements of metastatic bone lesions in prostate cancer patients: MR fingerprinting vs conventional MRI

## TL;DR

The study compares MRF and conventional MRI for measuring T1 and T2 relaxivities in prostate cancer bone metastases, finding good correlation between the two methods.

## Contribution

Demonstrates the reproducibility and correlation of MRF-derived T1 and T2 measurements in metastatic bone lesions compared to conventional MRI.

## Key findings

- MRF-derived T1 and T2 values were slightly higher than conventional MRI measurements.
- Strong Spearman correlation was observed between MRF and conventional methods for T1 and T2.
- MRF-derived delta T2 showed very strong correlation with dual spin echo post-treatment.

## Abstract

This study evaluated serial magnetic resonance fingerprinting (MRF)-derived T1 and T2 relaxivities of prostate bone metastasis compared with conventional T1 and T2 measurements.

This prospective study (July 2020 to July 2022) included MRF and conventional MRI acquisitions (T1: inversion-recovery turbo spin echo; T2: dual spin echo) from participants with bone metastasis from primary prostate cancer from two cohorts: pre-treatment (N = 34) and pre/post-treatment (N = 19). Phantom/human data were acquired on a 1.5-T scanner using an MRF sequence outputting T1 and T2 maps. Regions of interest (ROIs) of bone metastasis were drawn per visit on both MRF and conventional MRI. Inter-method reproducibility of T1 and T2 was assessed using Bland–Altman plots, reproducibility, intraclass correlation, and Spearman correlation coefficients. A delta parameter [post-treatment – pre-treatment] of method-specific T1 and T2 was reported.

Thirty-four patients with metastatic prostate cancer (mean age, 68 years ± 7 [standard deviation]) were evaluated pre-treatment; 19 participants were further scanned post-treatment. MRF-derived mean T1 and T2 in bone metastasis were slightly higher than the conventional MR measurements: 10.8% (T1) and 15.5% (T2). The reproducibility coefficient (r%) was 19.3% for T1 and 32.5% for T2, whilst the Spearman correlation coefficient was strong for both parameters (0.66, p < 0.001 and 0.70, p < 0.001). The MRF-derived delta T1 parameter was moderately correlated to the inversion-recovery method (0.59, p = 0.008), whilst the MRF-derived delta T2 was very strongly correlated to the dual spin echo method (0.80, p < 0.001).

A good correlation of MRF-derived T1 and T2 measurements with conventional quantitative methods was demonstrated in bone metastasis.