Photoacoustic Imaging Reveals Early Hemodynamic Changes in Diabetic Nephropathy: Hemoglobin Rise Prior to Oxygen Saturation Drop.

OBJECTIVE: This study employed photoacoustic imaging (PAI) to dynamically monitor renal oxygen saturation (sO2) and hemoglobin concentration (HbT) in a spontaneous Type 2 diabetes model (db/db mice) for early detection of diabetic nephropathy (DN). METHODS: db/db mice with fasting blood glucose (FBG) levels above 11.1 mmol/L (the model group) and C57BL/6 mice (the control group) were assessed at 8, 16, and 32 weeks of age. Evaluations included physiology, biochemistry, histology, and PAI. RESULTS: Histology confirmed progressive renal injury in db/db mice from 16 weeks. PAI quantification revealed a significant increase in HbT in db/db mice as early as 8 weeks, prior to a significant sO2 decrease observed at 16 weeks. CONCLUSION: The rise in renal HbT precedes the fall in sO2, identifying it as an early hemodynamic biomarker. PAI demonstrates significant potential for the noninvasive early diagnosis of DN.