Student Projects

In clinical routine, 2D and 4D Flow MRI are typically performed with cardiac synchronization [1] using an electrocardiogram (ECG) with patch electrodes [2] to bin the data into cardiac phases. Since the ECG signal is distorted by the magneto-hydrodynamic effect [3] and may be compromised by the switching of the MRI gradient fields [4], robust gating can be challenging. Since the quality also depends on the positioning and skin contact of the patch electrodes, the setup process can be time consuming. To address these issues, alternative techniques have been developed such as self-gating techniques [5], pilot tone navigation [6] and contact finger pulse units [7]. Inspired by approaches using camera-based photoplethysmography (PPG) [8], which can be limited by frame rate and/or PPG signal-to-noise ratio, the use of a contactless fiber-optic PPG device on the forehead in a contactless fashion is proposed.

The project aims at: • Establishing a data quality baseline using contact-based forehead-PPG measurements. • Collecting data using a contactless PPG acquisition. • Collection of various PPG datasets: wavelength (green and red), skin type (Fitzpatrick scale), demographics (age, …). • Study PPG signal quality and apply classical signal processing and machine learning methods to extract triggers/gating signals from the PPG signal.

Sébastien Emery (emery@biomed.ee.ethz.ch), Marco Giordano (marco.giordano@pbl.ee.ethz.ch) , Dr. Tommaso Polonelli (Tommaso.polonelli@pbl.ee.ethz.ch), Prof. Dr. Sebastian Kozerke (kozerke@biomed.ee.ethz.ch)

Four-dimensional phase-contrast magnetic resonance imaging (4D flow MRI) enables non-invasive, time-resolved quantification of blood flow in the cerebral vasculature, which can improve the understanding, characterization, and treatment planning of such sub-acute and chronic vascular-based pathologies. 4D flow MRI provides unique insights in the complex hemodynamics of vascular pathologies such as intracranial aneurysms (IAs) and arteriovenous malformations (AVMs). However, even given the velocity vector fields for such pathologies, sophisticated data analysis and visualization is needed for relevant patient-specific insights to aid characterization and treatment planning

Given 4D flow data for IA and AVM patients (some pre and post intervention), the student will set up a data visualization and analysis pipeline. This includes replicating existing methods but has room for exploration

Luuk Jacobs (ljacobs@ethz.ch)