Searcharxiv⌕ Search

arXiv subjects

Florian Büther

Publications and source records attributed to Florian Büther.

2 recordsLinked to original sources

BMND: Direct Poisson Denoising by N-Dimensional Block Matching and Collaborative Filtering

Poisson denoising of scientific data requires methods that account for signal-dependent noise while accommodating different data dimensionalities and preserving quantitative intensity information. We present BMND, a dimension-independent extension of block matching and collaborative filtering for Gaussian and Poisson observations. Building on the two-stage structure of BM3D and BM4D, BMND processes Poisson data directly, without a variance-stabilizing transform, by combining noise-aware patch matching with propagation of signal-dependent noise variances through collaborative filtering and aggregation. A dimension-independent reference-patch traversal scheme supports arrays with an arbitrary number of axes. An optional aggregation-aware mass conservation preserves the observed total intensity after weighted overlap-add. We evaluate the framework on one-dimensional physiological signals, two-dimensional images, and three-dimensional volumes, using controlled noise experiments and measured fluorescence microscopy acquisitions. The experiments demonstrate improved reconstruction quality from noise-aware matching and Wiener filtering, while low-count phantom experiments show reduced denoising-induced intensity loss through mass conservation. The framework provides a unified, non-learning-based approach to denoising across arbitrary data dimensions and is released as an open-source library.

cs.CV↗

Estimation of Physiological Motion Using Highly Accelerated Continuous 2D MRI

Patient motion is well-known for degrading image quality during medical imaging. Especially positron emission tomography (PET) is susceptible to motion due to its usually long scan times. In hybrid PET/MRI (magnetic resonance imaging), simultaneously acquired dynamic MRI data can be used to correct for motion. Usually, MRI model-based motion correction approaches are applied to the PET data. However, these approaches may fail for non-predictable, irregular motion. We propose a novel approach for the continuous and real-time tracking of motion using highly accelerated, dynamic MRI for an accurate motion estimation. For this purpose, a TurboFLASH sequence is utilized in single-shot mode with additional exploiting GRAPPA acceleration. Sampling frequency for one slice is up to 26 ms and 520 ms for one 3D volume of 20 coronal slices. Principal component analysis and a phase-sensitive resorting of slices is performed to restore temporal consistency of the volumes. Motion is estimated from these volumes using hyper-elastic registration. The approach is validated with the help of a dynamic thorax phantom as well as with eleven healthy volunteers. Phantom ground-truth data demonstrates that the approach produces an accurate motion estimation. Volunteer validation proves that the approach is also valid for different respiratory amplitudes including highly irregular breathing. The approach could be proved to be promising for a continuous PET motion correction.

physics.med-ph↗