J Nucl Med. 2007; 48 (Supplement 2):288P
General Clinical Specialties: Musculoskeletal
Musculoskeletal Posters |
FDG-PET in idiopathic retroperitoneal fibrosis
Annibale Versari1,
Alessandra Palmisano2,
Alessandro Fraternali1,
Rocco Cobelli3,
Carlo Salvarani4,
Carlo Buzio2,
Diana Salvo1 and
Augusto Vaglio2
1 Nuclear Medicine, S.Maria Nuova Hospital, Reggio Emilia, Italy;
2 Clinical Medicine and Nephrology;
3 Radiology, University of Parma, Parma, Italy;
4 Rheumatology, S.Maria Nuova Hospital, Reggio Emilia, Italy
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Objectives: Idiopathic retroperitoneal fibrosis (IRF) is a rare disease characterised by a fibro-inflammatory mass which surrounds the abdominal aorta and the iliac arteries and often causes obstructive uropathy. 18F-FDG PET can assess the metabolic activity of several inflammatory diseases. We explored the ability of FDG-PET to predict response to therapy and post-treatment relapse in IRF patients (pts). Methods: We studied 24 consecutive IRF pts (m/f:16/8; median age 58 yrs, range 9-82). The treatment was oral prednisone for 1 month and then prednisone+methotrexate or tamoxifen for 8 months. CT or MRI were performed at diagnosis, after 4 months of treatment and at the end of treatment. FDG-PET was performed in all pts before treatment, and in 13/24 pts also after the end of therapy. The treatment-induced reduction in size of IRF, as assessed by CT/MRI, was defined as absent if <10%, mild if 10-50%, and marked if >50%. FDG uptake was graded from 0 to 3+. The pts were compared with 24 controls. Results: At diagnosis, 22 (92%) pts showed a pathologic FGD uptake. As compared to the CT/MRI distribution of IRF, two main FDG uptake patterns were identified: diffuse (13/22 pts, 59%), and focal (9/22 pts, 41%). Of the 13 pts with diffuse pattern, 10 had grade 3+, 2 had 2+ and 1 had 1+ uptake; the reduction in size of IRF was marked in 9/10 (90%) pts with grade 3+ and 1 of 2 pts with grade 2+ and absent in 1 with 3+, 1 with 2+ and 1 with 1+. Of the 9 pts with a focal pattern, 3 had grade 3+, 4 had 2+ and 1 had 1+ uptake. A marked response was observed in only 1/3 pts with grade 3+; 2 mild responses in 2/4 pts with grade 2+; no response in 2/3 patients with grade 3+, 2/4 with grade 2+ and 2/2 with grade 1+. Both pts without pathologic uptake showed no reduction. After the end of treatment, 6/13 pts had a residual pathological uptake whereas 7 had no uptake. Post-treatment relapses were observed in 5/6 pts with a residual uptake, and in only 1/7 pts without. Conclusions: The distribution and intensity of vascular FDG uptake may predict response to treatment in IRF patients; a post-treatment residual uptake heralds disease relapse.
