# Automated adaptive detection and reconstruction of quiescent cardiac phases in free-running whole-heart acquisitions using Synchronicity Maps from PHysiological mOtioN In Cine (SYMPHONIC) MRI

## TL;DR

This paper introduces SYMPHONIC, a new MRI method that automatically detects still heart phases for high-quality whole-heart imaging, even with varying heart rates.

## Contribution

The novel contribution is the development of SYMPHONIC, an automated method for adaptive detection of cardiac phases in free-running MRI.

## Key findings

- SYMPHONIC accurately detects quiescent cardiac phases in free-running MRI data.
- SYMPHONIC provides high-quality whole-heart images even with heart rate variability.
- SYMPHONIC performs comparably to manual adaptive methods in vessel sharpness.

## Abstract

To reconstruct whole-heart images from free-running acquisitions through automated selection of data acceptance windows (ES: end-systole, MD: mid-diastole, ED: end-diastole) that account for heart rate variability (HRV).

SYMPHONIC was developed and validated in simulated (N = 1000) and volunteer (N = 14) data. To validate SYMPHONIC, the position of the detected acceptance windows, total duration, and resulting ventricular volume were compared to the simulated ground truth to establish metrics for temporal error, quiescent interval duration, and volumetric error, respectively. SYMPHONIC MD images and those using manually defined acceptance windows with fixed (MANUALFIXED) or adaptive (MANUALADAPT) width were compared by measuring vessel sharpness (VS). The impact of HRV was assessed in patients (N = 6).

Mean temporal error was larger for MD than for ED and ED in both simulations and volunteers. Mean volumetric errors were comparable. Interval duration differed for ES (p = 0.04) and ED (p < 10–3), but not for MD (p = 0.08). In simulations, SYMPHONIC and MANUALADAPT provided consistent VS for increasing HRV, while VS decreased for MANUALFIXED. In volunteers, VS differed between MANUALADAPT and MANUALFIXED (p < 0.01), but not between SYMPHONIC and MANUALADAPT (p = 0.03) or MANUALFIXED (p = 0.42).

SYMPHONIC accurately detected quiescent cardiac phases in free-running data and resulted in high-quality whole-heart images despite the presence of HRV.