How would I code this report...51600/74455 or just 74455?

Urinary tract infection. renal transplant and removal of native kidneys

The bladder was catherized under sterile conditions by the radiology nurse. Contrast was instilled under fluroscopic observation. Multiple AP and oblique views of the bladder were obtained during bladder filling and during urination.

Finding: Contrast refluxes into a markedly dilated system of the left renal transplant. There is marked calyceal dilation and blunting. Findings are compatible with grade 5 vesicoureteral reflux.

My thoughts are just to code 74455-26, because the radiology nurse catherized the bladder.
If this is correct would I add a modifier 52?

Thank you for your help.