ICG clearance test based on photoacoustic imaging for assessment of human liver function reserve: An initial clinical study

Liver function reserve (LFR) plays an extensive and important role in patients with liver disease. Indocyanine green (ICG) clearance test is the standard diagnostic approach for LFR evaluation which was performed by spectrophotometry or pulse dye densitometry (PDD). Spectrophotometry is the gold standard, it's invasive and not real-time. PDD is non-invasive, but accuracy of PDD is controversial. Taken spectrophotometry as the reference standard, this study investigated the accuracy of photoacoustic imaging (PAI) method for LFR assessment and compared to PDD in healthy volunteers. The results demonstrated a strong correlation between PAI method and spectrophotometry (r = 0.9649, p < 0.0001). No significant difference was shown in ICG clearance between PAI and spectrophotometry method (rate constant k1 vs. k2, 0.001158 +-0.00042 vs. 0.001491 +- 0.00045, p = 0.0727; half-life t1 vs. t2, 601.2 s vs. 474.4 s, p = 0.1450). These results indicated that PAI may be valuable as a noninvasive, accurate diagnostic tool for LFR assessment in human.