Technetium-99m nanocolloid scintigraphy in rheumatic inflammation in children

Technetium-99m HSA (human serum albumin) is a nanometer-sized albumin-based inert colloid, which has a specific ability to accumulate in inflamed soft tissue lesions. With a particle size smaller than 30 nm, Tc-99m HSA spills into the extravascular space in the sites of inflammation because of the changed capillary permeability. The conventional tracer in joint scintigraphy, technetium-99m methylene diphosphonate (Tc-99m-MDP) is a boneseeking compound, which strongly accumulates in the epiphyseal area of growing bones. This makes the estimation of the inflammatory process in the joints of growing children difficult. The nanocolloid compound has not this disturbing tendency. This fact makes the joint scans more specific and the detection of inflammatory lesions is easier especially in children. In our study Tc-99m HSA is used for the detection of rheumatic inflammation in children with juvenile rheumatoid arthritis. We examined 24 children with juvenile rheumatoid arthritis, age 3-19 years, 20 girls and 4 boys, who all had clinically active inflammation in the joints or in the tendon sheets. The uptake pattern of nanocolloid parallels the severity of the inflammatory process in periarticular tissues and tendon sheets. In suspicious cases, the comparison with the contralateral area helps in the detection of the lesion. Therefore, when investigating paired joints, the scintigraphy of symmetrical parts is necessary.