Knowledge of etiological mechanisms underlying whiplash-associated disorders (WAD) is incomplete. Localisation and quantification of peripheral musculoskeletal injury and inflammation in WAD would facilitate diagnosis, strengthen patients' subjective pain reports and aid clinical decisions, all of which could lead to improved treatment. In this longitudinal observational study we evaluated combined [11C]D-deprenyl positron emission tomography and computed tomography (PET-CT)) after acute whiplash injury and at 6 month follow-up. Sixteen adult patients (mean age 33 years) with whiplash injury grade II were recruited at the emergency department. [11C]D-deprenyl PET-CT, subjective pain levels, self-rated neck disability and active cervical range of motion were recorded within seven days after injury, and again at six month follow up. Imaging results showed possible tissue injuries after acute whiplash with an altered [11C]D-deprenyl uptake in the cervical bone structures and facet joints, associated with subjective pain locale and levels, as well as self-rated disability. At follow up, some patients had recovered, and some showed persistent symptoms, and reductions in [11C]D-deprenyl uptake correlated to reductions in pain levels. These findings help identify affected peripheral structures in whiplash injury and strengthen the idea that PET/CT detectable organic lesions in peripheral tissue are relevant for the development of persistent pain and disability in whiplash injury.