Aluminum‐27 nuclear magnetic resonance spectroscopy and imaging of the human gastric lumen

Abstract

Aluminum NMR is proposed as a new imaging and spectroscopy modality. Its potential is exemplified by in vivo studies of the human stomach. The dissolution kinetics of aluminum-containing drugs at physiological doses and their removal from the human stomach have been followed by 27Al magnetic resonance spectroscopy (MRS). Aluminum concentrations as low as 0.5 mg Al3+ in the human stomach can be detected. The time course of gastric emptying has been visualized with 27Al magnetic resonance imaging (MRI) under normal conditions and in the presence of an antimuscarinic agent, which reduces the gastric motor function. 27Al MRI is the only direct method to visualize the gastric pH. 27Al MRI opens new possibilities for medical and pharmaceutical science.

Gastrointestinal transit times in mice and humans measured with 27Al and 19F nuclear magnetic resonance

“…Recently, new GI contrast agents to selectively delineate the stomach and the bowel were developed (10,14). These contrast agents are based on the use of X-nuclei, i.e., 27 Al and 19 F, which are directly imaged by non-proton MRI (10,14).…”

“…In principle, equivalent assessments using MR methods should be feasible if the radioisotopes are substituted with magnetic active nuclei. It has been shown that 27 Al-MRI and 27 Al-MR spectroscopy (MRS) of Al 3ϩ released from aluminum-containing antiacidics can be used to selectively delineate the stomach (14). 27 Al has a quadrupolar moment that leads to quadrupole splittings that normally broaden the resonance beyond detection.…”

“…However, if the 27 Al nucleus experiences a highly symmetric environment, the quadrupolar splitting vanishes and the Al 3ϩ resonance has a linewidth of only a few Hz. This is the case for Al 3ϩ in aqueous solution at a pH below 3.5-a condition typically found in the stomach but not in the remainder of the GI tract (14). Al 3ϩ readily binds to cation-exchange resins in analogy to the radioisotopes used for ␥-scintigraphy.…”

In vivo magnetic resonance methods in pharmaceutical research: current status and perspectives

“…In vitro 27 Al MRS studies of aluminium containing antacid preparations in hydrochloric acid have shown that Al 3 is released from these drugs. 265 The oral uptake of aluminium-containing drugs in pharmaceutical doses and the time course of gastric emptying could be visualized in vivo using 27 Al MRI, 264 indicating the potential of the method for pharmaceutical applications.…”

“…Indeed, 27 Al MRI was applied to visualize gastric pH and as little as 0.5 mg Al 3 could be detected in the human stomach. 264 Aluminium-containing drugs have found widespread medical applications as adstringents, antacids and antiulcer agents. In vitro 27 Al MRS studies of aluminium containing antacid preparations in hydrochloric acid have shown that Al 3 is released from these drugs.…”