Fluorescence guided multimodal imaging enables spatially resolved identification of growth layers of Randall’s plaque-associated kidney stones

Recent studies have shown that mechanisms of kidney stone growth can be analyzed at the microscopic level by leveraging modern fluorescence microscopy. The present study aims to utilize multimodal imaging techniques on multiple Randall’s plaque stones to observe native fluorescent patterns of mineral-matrix deposition and to compare them both within and between patients. Stones were removed by basket during endoscopic procedures and were verified by micro CT as having grown on Randall’s plaque. Each stone was mounted on polystyrene and ground down to a polished planar surface. Stones were grounded repeatedly to collect as many interior planes as possible, with micro CT verification of each plane of section. Mineral composition was confirmed in selected stones using scanning electron microscopy (SEM), elemental mapping by energy dispersive spectroscopy (EDS), and infrared (IR) microscopy. Stones were then imaged using confocal microscopy for native fluorescence. Randall’s plaque exhibited a characteristic blue autofluorescent signal, potentially indicating a unique protein composition compared to the overlying stone matrix. The apatite-rich layer adjacent to Randall’s plaque showed bright yellow fluorescence, a pattern conserved across patients, suggesting the presence of a distinct urinary protein profile that may facilitate calcium oxalate monohydrate (COM) crystal attachment and, therefore, initial stone propagation. COM regions overlying Randall’s plaque retained laminated layers with alternating autofluorescence signatures, allowing visualization of growth transitions. Our findings, visualized through integrated multimodal imaging, offer insight into early stone pathogenesis of Randall’s plaque stones, and show matrix and plaque fluorescence patterns consistent across patients.