The use of a simple and wireless Lenz lens for in ovo MR imaging at ultra-high field

A Lenz lens is a detachable, passive structure used to enhance the RF-field (B1-field), significantly improving local sensitivity by concentrating the passively induced B1-field from a confined region, and thereby increasing signal-to-noise ratio (SNR). Attaining higher sensitivity or SNR is crucial in MRI, as it directly impacts image quality, specifically spatial resolution and acquisition time. In this study, we present the design of a novel yet simple and wireless Lenz lens with a diameter of approximately 10 mm in the focusing part, intended to improve MR image quality at 7 T. The performance of the proposed lens was evaluated in in ovo MR measurements, with the specific aim of improving the MR image quality of a tumour implanted on the chorioallantoic membrane of a chick embryo, a region that is challenging to image using conventional MRI coils due to its location. The use of the lens resulted in a significant increase (approximately 75%) in SNR within the region-of-interest covered by the lens, whereas only negligible changes were observed in the areas outside its coverage, relative to that conducted without the lens.