Hypermetabolism of Compensatory Laryngeal Muscles in Unilateral Vocal Cord Palsy: Comparison Study between Speech and Silence with Normal Subjects by Co-registered PET-CT Fusion Images / 핵의학분자영상

ABSTRACT

PURPOSE: There are a few case reports on asymmetric vocal cord uptake on FDG-PET in patients with unilateral vocal cord paralysis, which could be a potential pitfall in the interpretation of FDG-PET images. We evaluated the metabolic activity of laryngeal muscles of patients with unilateral vocal cord paralysis in comparison to normal controls during both speech and silence. METHODS: Eleven patients with unilateral vocal cord palsy (thyroidectomy=7, lung cancer=1, others=3) and 12 normal controls underwent FDG-PET with usual protocol. They were divided into two groups respectively; one group read books aloud for 20 minutes (phonation group) and the other kept silence (non-phonation groups) after FDG injection. Recent neck CT scan were co-registered with FDG-PET to produce PET-CT fusion images to elaborate small laryngeal muscles. RESULTS: In patients with unilateral vocal cord palsy, contralateral non-paralyzed vocal cord showed hypermetabolism mainly on thyroarytenoid muscle, more intensely with phonation group (SUV=5.88+/-2.65) than with non-phonation group (SUV=2.30+/-0.39). Normal control subjects showed hypermetabolism (3.68+/-0.96) in interarytenoid muscle and symmetric mild hypermetabolism in both lateral cricoarytenoid muscles in only phonation group. CONCLUSION: FDG-PET with fusion images using CT scan in patients with unilateral vocal cord paralysis showed hypermetabolism of contralateral non-paralyzed thyroarytenoid muscle, suggesting compensatory action during phonation. Phonation during FDG-PET study enhanced FDG uptake on different laryngeal muscles between patients with unilateral vocal cord paralysis and normal subjects.