In Idiopathic Retroperitoneal Fibrosis, Persistent FDG PET Uptake Helps Identifying Patients at Risk for Relapse

Gabriel Morin¹, Arthur Mageau¹, Khadija Benali¹, Eve Piekarski¹, Remi Bertinchamp¹, Quentin Raimbourg¹, Jean Francois Alexandra², Antoine Dossier¹, Tiphaine Goulenok¹, Damien van Gysel¹, Thomas Papo¹ and Karim Sacre², ¹Université Paris-Diderot, Paris, France, ²Bichat Hospital, Paris Diderot University, Paris, France

Meeting: 2018 ACR/ARHP Annual Meeting

Keywords: Retroperitoneal Fibrosing

Session Information

Date: Wednesday, October 24, 2018

Session Title: 6W021 ACR Abstract: Misc Rheumatic & Inflam DZ II (2970–2975)

Session Type: ACR Concurrent Abstract Session

Session Time: 11:00AM-12:30PM

Background/Purpose: Idiopathic retroperitoneal fibrosis (IRF) is a rare disease characterized by abdominal periaortic fibro-inflammatory tissue. The aim of this study was to evaluate the prognostic value of fibrosis FDG uptake using FDG/PET CT in patients with IRF

Methods: In this monocentric retrospective cohort study, all patients admitted for IRF from January 2009 to December 2017 underwent a FDG/PET CT at diagnosis and during follow up. Metabolic activity assessed by fibrosis FDG uptake was measured by generating a volume of interest to calculate the maximal standardized uptake value (SUVmax). Complete remission was defined by the disappearance of initial symptoms associated with normal CRP, increased/stabilization of eGFR and decreased/stabilization of the retroperitoneal mass on CT-scan. The primary outcome was IRF relapse rate during follow-up

Results: FDG/PET CT was performed at diagnosis, 3.1 [1-8.7] months (i.e 1^st evaluation) and 10.4 [4.9-17.5] months (i.e 2^nd evaluation) after IRF diagnosis in 23 patients (54.7 [36.9-89] years, 73.9% of men). FDG fibrosis uptake was seen in 23 (100%; SUVmax 6.5 [3.8-11.9]), 16 (69.6%; SUVmax 3.65 [2.1-5.4]) and 12 (52.2%; SUVmax 3.75 [2.7-7.8]) patients at diagnosis, 1^st and 2^nd evaluation, respectively. All but one patient had received steroids at IRF diagnosis and 21 (91.3%) were in complete remission at both 1^st and 2^nd evaluation. During a median follow-up period of 38.7 [3-107] months, 6 (26.1%) patients suffered IRF relapse that occurred 15.7 [9.2-42.8] months after diagnosis. Univariate analysis showed that CRP level at diagnosis, complete remission at 1^st and 2^nd evaluation and fibrosis FDG uptake at 2nd evaluation were associated with IRF relapse. In the multivariable analysis, only fibrosis FDG uptake at 2nd evaluation (p=0.046) was associated with IRF relapse. Sensitivity, specificity, negative predictive value and positive predictive value of fibrosis FDG uptake at 2^nd evaluation to predict IRF relapse were respectively 100%, 60%, 100% and 50%. Eventually, patients with fibrosis FDG uptake at 2^nd evaluation had a higher recurrence rate during follow up (p=0.047)

Conclusion:

In IRF, fibrosis FDG uptake during follow up is associated with clinical outcome. FDG/PET CT may help to better stratify the risk of relapse in IRF and target immunosuppressive therapy

Characteristic of patients

	Relapse (n=6)	No Relapse (n=17)	p
Age, years	53.3 [41.2-61.3]	57.1 [34.4-89]	ns
Men, n (%)	4 (66.7)	13 (76.5)	ns
Biopsy proven, n (%)	3 (50)	7 (41.2)	ns
IgG4, n (%)	1 (16.7)	2 (11.8)	ns
Abdominal pain at diagnosis, n (%)	6 (100)	14 (82.4)	ns
Constitutional symptoms at diagnosis, n (%)	4 (66.7)	9 (52.9)	ns
CRP at diagnosis, mg/L	40 [10-221]	17 [3-40]	0.0251
High CRP level at diagnosis, n (%)	5 (83.3)	7 (41.2)	ns
Serum creatinin at diagnosis, umol/L	143.5 [90-2254]	79 [54-560]	ns
High creatinin level at diagnosis, n (%)	3 (50)	7 (41.2)	ns
FDG-PET fibrosis uptake at diagnosis, n (%)	6 (100)	17 (100)	1
SUVmax at diagnosis	10.1 [5.5-11.9]	5.4 [3.2-10.7]	ns
Steroids at diagnosis, n (%)	6 (100)	16 (94.1)	1
Complete remission at 1st evaluation	4 (66.7)	17 (100)	0.0593
FDG-PET fibrosis uptake at 1st evaluation n (%)	6 (100)	10 (58.8)	ns
SUVmax at 1st evaluation	3.4 [3.1-3.7]	4.1 [2.1-5.4]	ns
Complete remission at 2nd evaluation	4 (66.7)	17 (100)	0.0593
FDG-PET fibrosis uptake at 2nd evaluation n (%)	6 (100)	6 (35.3)	0.0137
SUVmax at 2nd evaluation	5.3 [2.7-7.8]	3.4 [3.2-4.5]	0.08364
Follow up
Length, months	47.9 [26.9-106.9]	33.8 [2.8-71.5]	ns
Cumulative months of steroids	45.5 [26.9-106.9]	23.4 [2.8-56.6]	ns
Steroids withdrawal, n (%)	2 (33.3)	8 (50)	ns
Immunosuppressive drugs at any time, n (%)	4 (66.7)	0	0.0017
Death	0	2 (11.8)	ns

Patients with FDG-PET fibrosis uptake (FDG-PET+) during follow up had higher rates of relapse than patients without FDG-PET fibrosis uptake (FDG-PET-)

Disclosure: G. Morin, None; A. Mageau, None; K. Benali, None; E. Piekarski, None; R. Bertinchamp, None; Q. Raimbourg, None; J. F. Alexandra, None; A. Dossier, None; T. Goulenok, None; D. van Gysel, None; T. Papo, None; K. Sacre, None.

To cite this abstract in AMA style:

Morin G, Mageau A, Benali K, Piekarski E, Bertinchamp R, Raimbourg Q, Alexandra JF, Dossier A, Goulenok T, van Gysel D, Papo T, Sacre K. In Idiopathic Retroperitoneal Fibrosis, Persistent FDG PET Uptake Helps Identifying Patients at Risk for Relapse [abstract]. Arthritis Rheumatol. 2018; 70 (suppl 10). https://acrabstracts.org/abstract/in-idiopathic-retroperitoneal-fibrosis-persistent-fdg-pet-uptake-helps-identifying-patients-at-risk-for-relapse/. Accessed August 15, 2022.

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