Chronic cystitis can be diagnosed through various methods. Firstly, urinary tract imaging can demonstrate reduced bladder capacity, rough or irregular bladder margins. Secondly, an ultrasound can show a reduction in bladder cavity and general thickening of the bladder wall. Additionally, a CT scan can reveal widespread irregular thickening of the bladder wall and a reduction in bladder size, with the inner and outer surfaces appearing rough. These diagnostic methods can all be used to check for cystitis, though specific situations should be evaluated on a case-by-case basis.