Type 2 diabetes mellitus is the leading cause of chronic kidney disease. Clinical measures of kidney function often detect dysfunction after irreversible damage has occurred. This highlights an unmet need for a biomarker that can enable earlier detection of disease. Quantification of renal metabolic rate of oxygen is a promising metric because it increases by 40-65% during the early stages of diabetic kidney disease. Here, we propose a “difference method” to quantify bilateral renal metabolic rate of oxygen by imaging above and below the renal vessels and exploiting conservation of blood flow rate and mass.