To improve the detection sensitivity of MRI, a Wireless Amplified NMR Detector (WAND) is developed to image surrounding vessels from inside the esophagus. This cylindrical detector is a double frequency resonator with a single metal wire that is self-connected by a pair of varactors. It can convert wirelessly provided pumping power into amplified MR signals. When the detector is inserted inside the esophagus, vessel walls of the vertebrate artery and basal artery can be identified with greatly improved clarity. This detector will be useful to characterize subtle lesions in inflamed vessels.