Serial computed tomographic and positron emission tomographic properties of injection material used for vocal fold augmentation.

OBJECTIVES/HYPOTHESIS This study aimed to demonstrate the radiological properties of hyaluronic acid (HA) and calcium hydroxylapatite (CAHA) on serial computed tomography (CT) and positron emission tomography (PET) scan. STUDY DESIGN Retrospective Case Series. METHOD Retrospective chart and imaging analysis of patients who underwent HA or CAHA injection laryngoplasty. RESULT Total of 243 patients who underwent more than one CT of PET after last injection laryngoplasty were included. Sixty-eight patients received HA injection and 175 patients received CAHA injection. In all cases HA showed hypo-density in CT and no abnormal uptake on PET. CAHA showed bright calcific density on CT scan and high uptake on PET but had disappeared with time in 18 months if injected less than 0.85 mL in amount. CONCLUSION These findings support previous clinical studies on CAHA longevity and provide proper radiological interpretation on injection materials in the vocal folds. LEVEL OF EVIDENCE IV (Case series).