High-resolution MRI of kidney microstructures at 7.05 T with an endo-colonic Wireless Amplified NMR detector.

• A wireless amplified NMR detector can sensitively image kidney from the colonic lumen. • Kidney microstructures, including medullary rays, can be clearly identified in vivo. • BOLD MRI of kidney microstructures reveal their differential hemodynamic responses. • Signal modulation by inhalation oxygen level provides insights into oxygen delivery. To map the hemodynamic responses of kidney microstructures at 7.05 T with improved sensitivity, a Wireless Amplified NMR Detector (WAND) with cylindrical symmetry was fabricated as an endoluminal detector that can convert externally provided wireless signal at 600.71 MHz into amplified MR signals at 300.33 MHz. When this detector was inserted inside colonic lumens to sensitively observe adjacent kidneys, it could clearly identify kidney microstructures in the renal cortex and renal medullary. Owing to the higher achievable spatial resolution, differential hemodynamic responses of kidney microstructures under different breathing conditions could be individually quantified to estimate the underlying correlation between oxygen bearing capability and local levels of oxygen unsaturation. The WAND's ability to map Blood Oxygen Level Dependent (BOLD) signal responses in heterogeneous microstructures will pave way for early-stage diagnosis of kidney diseases, without the use of contrast agents for reduced tissue retention and toxicity. [ABSTRACT FROM AUTHOR]