Magnetic Resonance Imaging of the Skin with Optimized RF Coils – SKIN-COILS

The skin, providing many essential functions to the body, can be affected by a variety of diseases that represent the 4th leading cause of non-fatal disease burden. To date, research efforts did not address the needs in dermatology and severe difficulties in differential diagnosis remain. Specifically, differentiating arteriolosclerotic ulcers of Martorell (ASUM) from other types of leg ulcers is challenging while of upmost importance to identify appropriate treatments. To address this health issue, non-invasive skin imaging methods are highly required to provide high resolution images of the skin layers and information on the deeper lying vasculature. Among non-invasive imaging methods, MRI is perfectly suited to study the skin as it provides higher spatial resolution (~100 µm) and more anatomical details than ultrasound, greater penetration depth (~10 cm) than optical methods and a wider FOV than both, while achieving a unique soft tissue contrast and access to functional information. Despite the theoretically high potential of MRI for skin imaging, to date, no suitable MR solutions are available due to both the lack of sensitivity of the MR radiofrequency system and the lack of specific acquisition protocols leading to strong SNR-related limitations.
In this context, this project targets the development of a dedicated hard- and software package featuring highly sensitive RF coils and tailored acquisition protocols for high-field clinical MR systems (3 T) capable of providing high-resolution images of the skin and the underlying vasculature of great value for both, medical applications and investigations on healthy skin. To this end we will exploit a novel coil concept, recently introduced by the applicants’ groups, referred to as “multi-loop coil (MLC)”. This concept exploits the use of small loops operated in series and has been shown to improve the sensitivity in comparison to standard coils (by a factor of 2 to 4) at short distance inside the sample while maintaining a large lateral FOV and, therefore, appears particularly promising for skin MR.
In order to achieve the goals of this project, several fundamental scientific advances with MLC coils will be addressed so as to overcome the limiting factors identified in our preliminary study.
In a nutshell, the first work package (WP1) of this project targets the improvement of the magnetic efficiency of MLCs, through the use of multi-layer structures and optimized geometries, together with the reduction of the two main noise sources in MRI by exploiting monolithic design and shielding rings principle.
In WP2, selected MLC designs studied in WP1 will be directly implemented to develop a clinically applicable MLC-array optimized for skin MRI enabling the investigation of local skin conditions (i.e., ulcers) and related pathologies of the skin vasculature. In parallel, we will develop a highly spatially selective local transmit coil to produce optimized excitation profiles for skin MRI. WP2 will end with a series of bench and MR test of the full RF set up so as to asses and validate patient safety and obtain certification for use on human.
WP3 will imply leading dermatologist to closely define the imaging targets and requirements for SKIN-COILS and then focus on the development of dedicated MR acquisition sequences with respect to pathology-related requirements, facilitating in-vivo high-resolution anatomical skin images and angiography in a clinical 3 T scanner with patient compatible acquisition time. Finally, the performance of the novel hard- and software package developed in this ambitious project will be evaluated in a pilot study conducted together with leading dermatologists on healthy volunteers and skin ulcer patients (WP4), and the added diagnostic value will be quantified.