ill-defined retrocardiac opacity, likely represents atelectasis as the ct of the abdomen and pelvis from the same day demonstrated clear lungs. apparent mediastinal widening which could be related to positioning, but can be further assessed if clinically indicated. consider repeat exam with pa and lateral views at full inspiration and upright position to confirm findings. findings discussed with dr. <unk> <unk> phone at <num> p.m. on <unk>.