These can be difficult to appreciate on static images. Often the coronals are very helpful.

Answer: Paraesophageal hernia with organoaxial position of the stomach but I will also accept Gastric voluvlus (again with organoaxial gastric rotation).

The difference here comes down to whether it is obstructed or not. Many people would stay that volvulus implies obstruction (be that true or not) so I am careful when using the word volvulus. No obstruction, no volvulus. For older folks with long standing large paraesophageal hernias, it is not uncommon to see rotation of the stomach (more commonly organoaxial - along long axis), and they may not be obstructed. One should be very specific in their report to specify if you believe it is obstructing (ie true voluvlus and needs surgery) or just incidental herniation with organoaxial positioning.

ref: https://radiopaedia.org/articles/gastric-volvulus

good review article: http://pubs.rsna.org/doi/pdf/10.1148/rg.295095011