# Ultimate Intrinsic SNR in the Torso of Realistic Body Models

## TL;DR

This study explores how signal quality in MRI changes with magnetic field strength in the torso, finding that higher fields improve signal more rapidly.

## Contribution

The paper introduces a method to calculate ultimate intrinsic SNR in realistic body models across varying magnetic field strengths.

## Key findings

- uiSNR increases linearly in lower magnetic fields (0.55–3 T) with small variation in the torso.
- uiSNR increases superlinearly in higher magnetic fields (5–14 T), showing larger variation due to body heterogeneity.
- Superlinear scaling suggests potential for ultra-high-field MRI in body imaging.

## Abstract

This work aims to investigate how the ultimate intrinsic signal‐to‐noise ratio (uiSNR) varies with increasing static magnetic field B0 in the torso of realistic body models.

A dipole cloud was positioned around the realistic body model and randomly excited. The volume integral solver MARIE was used to calculate the corresponding electromagnetic fields. The uiSNR maps were calculated using these electromagnetic bases and were fitted with the power law for different B0 ranges.

The uiSNR could be reliably calculated in regions deeper than 3 cm, where convergence of uiSNR over the number of basis vectors was achieved. In a lower magnetic field range (from 0.55 to 3 T), the uiSNR increases roughly linearly versus B0 with small variation throughout the torso (Ella: uiSNR ∝ B
0
0.96±0.07, Duke: uiSNR ∝ B
0
0.98±0.10). In an upper magnetic field range (from 5 to 14 T), the uiSNR increases superlinearly in the torso (Ella: uiSNR ∝ B
0
1.86±0.25, Duke: uiSNR ∝ B
0
1.99±0.28), with a larger variation correlated to the heterogeneous structure of the body model.

The superlinear scaling exponent in the upper magnetic field range indicates the promise of applying UHF MRI for body imaging.