18F-FDG PET/CT and contrast-enhanced CT in a one-stop diagnostic procedure: a better strategy for management of patients suffering from retroperitoneal fibrosis?

PURPOSE: Effective management of patients affected by retroperitoneal fibrosis (RPF) is an important issue because of lack of relevant parameters to objectively assess the degree of inflammation. We evaluated added value of contrast-enhanced computed tomography (CE-CT) combined with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) as a one-stop diagnostic procedure for the assessment and follow-up of patients with RPF.

MATERIALS AND

METHODS

(18)F-FDG PET and CE-CT findings were reviewed in 10 patients suffering from RPF. Maximum standard uptake values (on native and contrast-enhanced [ESUV(max)] CT) were calculated. Dimensions of periaortitis were measured on CT scans. Observed clinical changes between baseline PET scan (T0) and at 6 months follow-up (T6) were analyzed regarding differences of initial values for clinic and paraclinic parameters.

RESULTS

Patients still suffering from pain 6 months after baseline PET scan had initially higher FDG uptake (ESUV(max): 5.7 ± 0.9 vs. 2.4 ± 0.9, P < 0.01). Unlike biologic and CT parameters, FDG uptake was the most relevant parameter to measure severity of inflammation (ESUV(max) threshold: 4.3; Se = Sp = 1.0). CE-CT exclusively allowed better delineation and more accurate assessment of FDG uptake of periaortitis and its extension to adjacent structures.

CONCLUSIONS

Our results clearly show the usefulness of PET/CT for better evaluation and management of patients with fibroblast proliferation disease. Accurate determination of inflammation level is significantly improved when PET/CT and CE-CT are performed in the same study and used for better delineation of areas of residual inflammation.