Table 5 Quantitative and qualitative interpretations of ICG fluorescence in different clinical scenarios

Acute Mesenteric Ischemia

QT

Fluorescence Intensity Measurement

Measures fluorescence intensity over time. Low or absent fluorescence indicates severe ischemia and necrosis

Time-to-Peak Fluorescence (TTP)

Measures the time for fluorescence to peak after ICG injection. Prolonged TTP indicates compromised blood flow

QL

Pattern of Fluorescence Distribution

Visual inspection identifies ischemic areas. Patchy or absent fluorescence indicates varying degrees of ischemia

Dynamic Visualization

Real-time visualization allows assessment of immediate tissue response, highlighting regions of poor perfusion

Bowel Obstruction

QT

Fluorescence Signal Strength

Evaluates perfusion by quantifying fluorescence signal strength. Lower signal suggests impaired blood flow

Slope of Fluorescence Intensity (SFI)

Measures the rate of fluorescence intensity increase post-ICG injection. A reduced slope indicates compromised perfusion

QL

Delayed Fluorescence Appearance

Delayed appearance suggests partial obstruction, while absence of fluorescence indicates complete obstruction and ischemia

Uniformity of Fluorescence

Assesses the uniformity of fluorescence; non-uniformity may indicate compromised blood flow, guiding intervention

Incarcerated Hernia

QT

Peak Fluorescence Intensity (PFI)

Measures perfusion status in the bowel segment within the hernia. Low PFI suggests ischemia or strangulation

Area Under the Curve (AUC)

Quantifies fluorescence intensity over time. A smaller AUC suggests reduced blood flow and tissue viability

QL

Fluorescence Onset and Homogeneity

Assesses timing and spread of fluorescence. Delayed or incomplete fluorescence indicates compromised perfusion

Real-Time Fluorescence Dynamics

Intraoperative visualization helps assess immediate perfusion status, identifying areas of compromised tissue

Bowel Anastomosis

QT

Quantified Fluorescence Intensity

Measures fluorescence intensity at the anastomotic site. Higher values indicate better perfusion

Fluorescence Decay Rate

Measures the rate of fluorescence intensity decrease. Indicates venous return and tissue perfusion adequacy

QL

Symmetry and Continuity of Fluorescence

Assesses symmetry and continuity of fluorescence across the anastomosis to ensure adequate perfusion and reduce risks

Timing of Fluorescence Peak

Observes peak timing at the anastomotic site to assess blood supply. Delayed or uneven fluorescence may require revision