Figure 1. There is evidence of left vesico-ureteric junction obstruction, with delayed passage of FDG, and moderate hydroureter and hydronephrosis.

Figures 2, 3. At the antero-superior aspect of the vaginal vault, there is a soft tissue density mass that is hypermetabolic (SUV_max 5.5, with increase on delayed scanning, not shown). There is invasion of the posterior bladder wall, and diffuse bladder wall thickening. There is gas and fluid in both the vaginal vault and bladder.

Residual/ recurrent cervical carcinoma with vesico-vaginal fistula formation.

Vesicovaginal fistulae may be due to gynaecologic malignancy, radiotherapy and inflammatory diseases of the bowel, amongst others. The CT findings of gas in both the vaginal vault (expected) and bladder (not expected); and fluid in both the vaginal vault (not expected) and bladder (expected), effectively demonstrates the fistulous communication between the vaginal vault and the bladder. Fused FDG-PET/CT images confirm this through the demonstration of hypermetabolic fluid in the vaginal vault, consistent with urine. The main importance of the fused images in this case however, is the added information provided by the presence of a hypermetabolic mass, not seen on CT imaging alone, consistent with residual/ recurrent disease.