Quantification of hemi-hepatic ischemia using real-time multispectral oxygenation imaging with single snapshot imaging of optical properties (SSOP).

Background
Identifying liver ischemia is crucial in liver surgery. This study aimed to develop a hemi-hepatic ischemia model for assessing liver ischemia using single snapshot imaging of optical properties (SSOP), a noninvasive optical imaging modality that provides real-time measurements of tissue oxygen saturation (StO2).
Materials And Methods
Twelve swine were randomly assigned to two groups: One undergoing total vascular inflow occlusion (TVIO) and the other undergoing hepatic artery occlusion (HAO). Preoperative 3D CT scans were used to locate the left-sided hepatic arteries and portal veins, which were clamped during surgery. Real-time SSOP imaging was conducted to measure StO2 in three lobes-the left lateral lobe (LL), left medial lobe (LM), and right medial lobe (RM)-as well as capillary lactate levels and Doppler blood flow. Measurements were recorded at baseline (T0), during ischemia (T1, 30 min after clamping), and during reperfusion (T2, 30 min after declamping).
Results
In the TVIO group, SSOP imaging revealed a distinct demarcation line on the liver surface. StO2 levels measured by SSOP significantly decreased from T0 to T1, dropping by 29.8% in the LL (46.0 ± 5.1 vs. 16.2 ± 5.1%, p = 0.011) and 36.3% in the LM (42.7 ± 5.9 vs. 6.4 ± 4.0%, p = 0.001). Additionally, capillary lactate levels increased substantially in the LL (1.3 ± 0.4 vs. 8.5 ± 2.4 mmol/L, p = 0.041) and in the LM (1.3 ± 0.4 vs. 8.2 ± 2.1 mmol/L, p = 0.021). In contrast, the HAO group showed a less pronounced reduction in StO2: 13.6% in the LL (32.7 ± 6.4 vs. 19.1 ± 5.4%, p = 0.007) and 19.8% in the LM (35.3 ± 8.2 vs. 15.5 ± 5.8%, p = 0.011), with no significant increase in capillary lactate levels. An inverse correlation was found between StO2 and capillary lactate levels (r = - 0.76, p < 0.001).
Conclusion
SSOP is a real-time, contrast-free imaging technique that effectively evaluates liver ischemia by accurately measuring tissue oxygenation, as validated by perfusion biomarkers.