The present invention provides a method for measuring the gastric acidity of a mammal using a .sup.13C-labeled carbonate compound. Specifically, the present invention relates to a method for measuring the gastric acidity of a mammal including the following steps:

(1) using, as a test sample, expired air of a mammalian subject excreted at any point in time within 30 minutes after oral administration of a predetermined amount of a .sup.13C-labeled carbonate compound, measuring behavior of .sup.13CO.sub.2 in the expired air;

(2) comparing the behavior of .sup.13CO.sub.2 (measured .sup.13CO.sub.2 behavior) obtained in step (1) with the behavior of corresponding .sup.13CO.sub.2 (reference .sup.13CO.sub.2 behavior) that has been obtained beforehand in a control mammal; and

(3) determining the gastric acidity of the mammalian subject based on a difference between the reference .sup.13CO.sub.2 behavior and the measured .sup.13CO.sub.2 behavior obtained above.

Described herein are methods of management of functional dyspepsia in a patient by administering an amylin analogue or a CCK composition to the patient. Methods of diagnosing such patient include a standard gastric-emptying assessment using a standardized solid meal along with measurements of blood glucose levels. Another method of diagnosing such patient includes a gastric-emptying scintigraphy assessment with labeled carbohydrates or other assessments to diagnose rapid carbohydrate gastric emptying.

A method for the early detection and monitoring of the progression of cancer by detecting breath biomarkers is provided. The method comprises assessing the activity of an aldo-keto reductase by measuring the concentration of an exogenous substrate for said enzyme and/or measuring the concentration of a metabolite of said substrate in exhaled breath of a subject. Preferably, the cancer is lung cancer.

A method for predicting transplant-free survival of a patient suffering from acute liver failure (ALF) or acute liver injury (ALI), the method including: performing a .sup.13C-methacetin breath test which includes administering .sup.13C labelled methacetin to the patient; measuring exhaled breath to evaluate changes in a .sup.13CO.sub.2 to .sup.12CO.sub.2 ratio for a predetermined time after the administering; calculating a PDR-peak value of the patient; and predicting the patient as having high chances of transplant-free survival if the calculated PDR-peak value is above a threshold value or as having low chances of transplant-free survival if the PDR-peak value is below threshold value.

Described herein is a new inert fluorinated gas which can be used for fluorine-19 (.sup.19F) magnetic resonance imaging (MRI) of the lungs. Specifically, this method uses 20-79% octafluorocyclobutane (OFCB) premixed with at least 21% oxygen to acquire for example static ventilation images of the lungs, dynamic multiple breathing images of the lungs, apparent diffusion coefficient measurements (ADC) of OFCB in the lungs, and ventilation-perfusion ratio (V/Q) mapping.

Described herein are methods of management of functional dyspepsia in a patient by administering an amylin analogue or a CCK composition to the patient. Methods of diagnosing such patient include a standard gastric-emptying assessment using a standardized solid meal along with measurements of blood glucose levels. Another method of diagnosing such patient includes a gastric-emptying scintigraphy assessment with labeled carbohydrates or other assessments to diagnose rapid carbohydrate gastric emptying.

An aspect of the disclosure provides a method of evaluating the nutriture of a subject, comprising (1) calculating the ratio of the .sup.13CO.sub.2 amount to the unlabeled CO.sub.2 amount or total CO.sub.2 amount in an expired air sample obtained from the subject to which a .sup.13C-labeled amino acid was administered; and (2) comparing the ratio with a reference value to evaluate the nutriture. Another aspect of the disclosure provides a composition comprising a .sup.13C-labeled amino acid for evaluating the nutriture of a subject.

Parahydrogen Induced Polarization was employed to prepare nuclear singlet state between methylene and methyl protons in propane gas. Low-field MRI preserves this singlet state with much longer T.sub.S=4.70.5 s. Spin-Lock Induced Crossing (SLIC) transforms singlet state in observable nuclear magnetization suitable for MRI with sub-millimeter and sub-second spatial and temporal resolution respectively with signal enhancement>10,000 times. Long-lived spin states created in hyperpolarized propane-d.sub.6 gas can be detected directly at 0.0475 T. This long lifetime and non-toxic nature of propane gas could be useful for bio-imaging applications including potentially pulmonary low-field MRI. The feasibility of high-resolution low-field 2D gradient-echo MRI was demonstrated with 0.880.88 mm.sup.2 spatial and 0.7 s temporal resolution respectively at 0.0475 T. Propane is a non-toxic gas, and therefore, these results enable low-cost high-resolution high-speed MRI of gases for imaging of lungs.

Hyperpolarized samples (i.e., samples having fractional spin polarization P of at least 0.1) of a target molecular species are created through spin transfer from hyperpolarized xenon atoms or other source isotopes. Reversible nanoscale solid state contact is achieved between the hyperpolarized xenon atoms and molecules of a target species. The resulting solid state mixture is exposed to conditions of magnetic field and temperature designed to allow or even facilitate transfer of spin polarization from the xenon to the target molecules. The xenon and the target species are then separated under conditions that substantially preserve the polarization of the target species. The hyperpolarized target species can then be introduced into a subject of a nuclear magnetic resonance (NMR) experiment.