Italian association of nuclear medicine molecular imaging and therapy (AIMN) practical guide on white blood cells labelling for imaging infections and inflammations: technical procedure, quality controls and national regulations

Scintigraphy using radiolabelled white blood cells (WBCs) is a valuable tool for differentiating infection from sterile inflammation with high accuracy. Established guidelines for WBCs labelling, quality controls (QCs), acquisition protocols, and interpretation criteria solidify its role as a preferred nuclear medicine imaging method in various clinical settings. WBCs radiolabelling is an extemporaneous preparation, which can be performed using open procedure or closed systems (Leukokit® and WBC marker kit®) and, therefore, subject to the rules described by current European Regulations regarding Good Manufacturing Practice (GMP), Italian Standards of Good Preparation for Nuclear Medicine and Standard Operating Procedure (SOP). It is necessary to employ qualified personnel and perform several QCs to ensure the sterility, non-pyrogenicity and stability of the final preparation, as well as QCs to verify autologous leukocyte integrity and functionality over time. The regulatory landscape has changed significantly in recent decades, particularly following the 2001 directive extending GMP principles to all radiopharmaceutical preparations. This document, developed by the Infection and Inflammation Study Group of the Italian Association of Nuclear Medicine Molecular Imaging and Therapy (AIMN), aims to summarize various labelling methods for WBCs, addressing regulatory, technical, and quality assurance requirements.