Blackberry (Rubus spp.): a pH-dependent oral contrast medium for gastrointestinal tract images by magnetic resonance imaging

In this study, seven fruits have been tested on their magnetic properties, paramagnetic metal content and contrast enhancement in magnetic resonance imaging (MRI) of phantom and in vivo. Magnetic susceptibility was determined for the fruit pulps, as well as the contents of paramagnetic metals; iron, manganese and copper. The total content of these metals was 4.3, 8.6, 11.1, 10.9, 12.3, 8.3 and 29.3 mg/kg of fruit for plum, blueberry, apple (red), pineapple, beet, grape, blackberry, respectively, and with magnetic susceptibility of −2.29±0.07, −2.43±0.07, −2.13±0.07, −1.84±0.02, −1.75±0.01, −1.78±0.06, −2.18±0.07 SI, respectively. T1- and T2-weighted MR images were performed for the seven fruits and water (χ=−9.98×10−3 SI) and in one subject. While there was no correlation between the magnetic susceptibility and contrast enhancement, there is a correlation with the total paramagnetic metal content determined with contrast enhancement in MRI. Thus, blackberry (Rubus spp.) contrast enhancement was the highest among the fruits in T1-weighted images. Furthermore, this fruit's contrast enhancement shows to be pH-dependent. These characteristics and the wide availability of the Rubus spp. suggest that it should be implemented as an oral contrast agent in images by MR to assess the function of the gastric section of the GI tract. Furthermore, it has the advantage of being a natural meal, so that it can be well tolerated by the patients and use as much as it is needed without side effects.