Abstract
BackgroundWe investigate the use of different denoising filters on low signal-to-noise ratio cardiac images of the rat heart acquired with a birdcage volume coil at 7T. Accuracy and variability of cardiac function parameters were measured from manual segmentation of rat heart images with and without filtering.MethodsTen rats were studied using a 7T Varian system. End-diastolic and end-systolic volumes, ejection fraction and left ventricle mass (LVM) were calculated from manual segmentation by two experts on cine-FLASH short-axis slices covering the left ventricle. Series were denoised with an anisotropic diffusion filter, a whole variation regularization or an optimized Rician non-local means (ORNLM) filtering technique. The effect of the different filters was evaluated by the calculation of signal-to-noise (SNR) and contrast-to-noise (CNR) ratios, followed by a study of intra- and inter-expert variability of the measurement of physiological parameters. The calculated LVM was compared to the LVM obtained by weighing the heart ex vivo.ResultsThe SNR and the CNR increased after application of the different filters. The performance of the ORNLM filter was superior for all the parameters of the cardiac function, as judged from the inter- and intra-observer variabilities. Moreover, this filtering technique resulted in the lowest variability in the LVM evaluation.ConclusionsIn cardiac MRI of rats, filtering is an interesting alternative that yields better contrast between myocardium and surrounding tissues and the ORNLM filter provided the largest improvements.
Highlights
We investigate the use of different denoising filters on low signal-to-noise ratio cardiac images of the rat heart acquired with a birdcage volume coil at 7T
We investigated the effect of three filtering techniques applied to low-signal to noise ratio (SNR) cine images of the rat heart acquired with a birdcage volume coil
The mean total time for processing a data set is roughly equal to 0.72 min for the anisotropic filter, to 0.63 min for the total variation regularization and to 10 min for optimized Rician non-local means (ORNLM)
Summary
We investigate the use of different denoising filters on low signal-to-noise ratio cardiac images of the rat heart acquired with a birdcage volume coil at 7T. Accuracy and variability of cardiac function parameters were measured from manual segmentation of rat heart images with and without filtering. MRI has become the gold-standard for the non-invasive examination of these models This is despite challenges imposed by an elevated heart rate We investigated the effect of three filtering techniques applied to low-SNR cine images of the rat heart acquired with a birdcage volume coil. The main goal was to determine whether evaluation of the cardiac function with a birdcage volume coil could be improved by applying filtering technique as post-processing
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