A Study to Evaluate the Impact of Apremilast on Magnetic Resonance Imaging (MRI) Outcomes in Adults With Psoriatic Arthritis

This study consists of 3 phases: * Screening Phase - up to 4 weeks * Single-arm, Open-label Treatment Phase - Weeks 0 to 48 * Participants will receive apremilast 30 mg BID (after a 5-day titration period) for the entire duration of this phase. * MRI of the most affected hand and whole body MRI (WB-MRI) will be performed at weeks 0, 24, and 48. * The hand with the greater inflammatory burden of swollen joints and/or dactylitis will be considered as the most affected hand. If both hands are equally affected, the dominant hand will be designated as the index hand. * Observational Follow-up Phase - 4 Weeks * All participants who complete the study or discontinue early will participate in the 4-week Post-Treatment Observational Follow-up Phase.