Evaluation of 99mTc-erythromycin and 99mTc-streptomycin sulphate for the visualization of inflammatory lesions

^99mTc-erythromycin (E) and ^99mTc-streptomycin sulphate (SS) were prepared with >98% labelling efficiency. The labels were stable up to 24 h of testing, using ITLC-SG strips and acetone and saline as solvents. The biodistributions of both radiopharmaceuticals versus ⁶⁷Ga-citrate were studied in mice with turpentine-induced abscesses at 6 days post-induction. The mice were sacrificed at 1, 3 and 6 h post-injection of 15 MBq of ^99mTc-E or ^99mTc-SS. Mice injected with ⁶⁷Ga-citrate were sacrificed at 4 and 24 h. The maximum abscess-to-muscle ratios obtained by biodistribution studies were 2.36 ± 1.04 (6 h), 2.38 ± 0.38 (6 h) and 4.76 ± 2.04 (4 h) with ^99mTc-E, ^99mTc-SS and ⁶⁷Ga-citrate, respectively. The maximum abscess-to-contralateral tissue ratios by ROIs over respective areas on scintigrams were 2.38 ± 0.16 (6 h), 3.21 ±0.14 (3 h) and 3.24 ± 0.92 (24 h) for Tc-E, ^99mTc-SS and ⁶⁷Ga-citrate, respectively. The uptake mechanism might be infiltration into interstitial space due to increased capillary permeability.