Assessment of Capillary Permeability Using Radiolabeled Albumin and 3D CZT-ring Gamma Camera

A 71-year-old woman receiving paclitaxel, carboplatin, and pembrolizumab for breast carcinoma developed severe diarrhea, followed by hypovolemic shock with generalized edema, raising suspicion of immune checkpoint inhibitor-related capillary leak syndrome. Dynamic scintigraphy was performed using intravenous technetium-99m-labeled human serum albumin combined with induced transient venous stasis. Baseline 3D CZT SPECT imaging showed symmetrical vascular activity. Cuff inflation induced a progressive unilateral increase in tracer uptake consistent with albumin extravasation, followed by incomplete washout. Volumetric leak imaging enabled precise localization of capillary leakage. This case illustrates the potential of 3D CZT-ring cameras for dynamic functional assessment of vascular permeability.