PET/CT images demonstrate an intensely FDG-avid anterior mediastinal mass with ill-defined margins, as well as FDG-avid lymphadenopathy in the left greater than right paratracheal and prevascular nodal stations. Several FDG-avid cardiophrenic lymph nodes are also noted.

There is also asymmetric increased FDG activity in the right vocal chord:

This patient was diagnosed with primary mediastinal B cell lymphoma, with left vocal chord paralysis identified on laryngoscopy.

Vocal chord hypermetabolism on PET/CT is seen contralateral to the paralyzed/paretic vocal chord, due to compensatory muscular overactivity (primarily cricoarytenoid muscles). This study demonstrated very subtle medialization of the left vocal chord on CT images:

Asymmetric FDG activity may be the first sign of vocal chord paralysis in cases where anatomic findings (medialized vocal chord, dilation of ipsilateral piriform sinus or laryngeal ventricle) may be subtle. Causes include injury to the recurrent laryngeal nerve due to prior radiation/surgery, chemotherapy, and tumor infiltration (the presumed etiology in this untreated patient). The left side is more often affected due to the longer course of the recurrent laryngeal nerve.

Paquette CM, et al. Radiographics 2012;32:721-740.
Kamel EM, et al. Radiology 2002;224:153-156.

This graphic demonstrates PET/CT findings of different vocal chord pathology: