Background/Purpose:

Polymyalgia rheumatica (PMR) and giant cell arteritis (GCA) are two frequent overlapping diseases. The purpose of this work is to examine the relationship between these conditions by analysis of CT/PET findings. 

Methods:

Eighty consecutive patients (64 PMR diagnosed according to Bird’s criteria, 16 GCA diagnosed according to the ACR criteria, of whom 10 also had PMR) underwent simultaneous FDG-PET and CT imaging from the skull base to the knee using an integrated PET/CT scanner (Hirez; Siemens Medical Solutions, Knoxville TN, USA), after recording demographic, clinical and laboratory data. Arterial and joint uptake were scored relative to liver uptake as 0=no uptake present, 1=lower than liver uptake, 2=similar to liver uptake, 3=higher than liver uptake. All the values were further subdivided into “positive” (scores 2 and 3) and “negative” (scores 0 and 1). Fifty-five patients were women, median age was 74 years (range 50-90 years), median disease duration was 3 months (range 0.5-11 months), median morning stiffness was 52 minutes (range 0-420 minutes), median C-reactive protein (CRP) was 36 mg/L (range 2-106 mg/L). Eighty age-matched controls were enrolled, who underwent PET/CT for suspected neoplastic disease, but without autoimmune conditions or previous chemiotherapy, radiotheraphy, and glucocorticoid treatment.

Results:

Shoulders showed more frequently increased uptake (65 patients or 81.3%, bilateral in 57) (table 1), followed by the trochanteric bursae (60 patients or 75%, bilateral in 50). Among the studied arteries, an increased uptake was seen at the aortic arch and in the ascending aorta in 35 patients (43.8%). Patients had more frequently increased uptake than controls in all arterial and joint sites, except the coxofemoral joints. Among patients groups, a significant difference in uptake frequency was seen in trochanteric bursae (PMR>GCA, p=0.05), in carotid arteries (GCA>PMR, p=0.001), and in abdominal aorta (PMR+GCA>PMR, p=0.04)

Table 1. Distribution of uptake sites in patients groups and controls. *=PMR>GCA; **=GCA>PMR; ***=PMR+GCA>PMR.

	PMR n (%)	PMR+GCA n (%)	GCA n (%)	Controls n (%)	p (PMR vs. PMR+GCA vs. GCA)	p (patients vs. controls)
Patients	64	10	6	80
Shoulders	55 (86)	8 (80)	2 (33)	14 (17)	0.07	<0.0001
Sternoclavear	32 (50)	7 (70)	3 (50)	0	0.5	<0.0001
Trochanteric bursae	50 (78)	8 (80)	2 (33)	4 (5)	0.05*	<0.0001
Coxo-femoral	5 (8)	0	0	4 (5)	0.5	0.6
Ischiatic bursae	46 (72)	7 (70)	2 (33)	0	0.1	<0.0001
Cervical interspinous bursae	6 (9)	2 (20)	1 (17)	0	0.55	<0.008
Lumbar interspinous bursare	28 (44)	5 (50)	2 (33)	0	0.8	=0.0001
Carotid arteries	4 (6)	2 (20)	4 (67)	1 (1)	0.001**	<0.0001
Subclavian arteries	11 (17)	3 (30)	3 (50)	0	0.1	<0.0001
Aortic arch	26 (41)	5 (50)	4 (67)	0	0.4	<0.0001
Ascending aorta	25 (39)	5 (50)	5 (83)	1	0.1	<0.0001
Descending aorta	22 (34)	4 (40)	4 (67)	1 (1)	0.3	<0.0001
Abdominal aorta	7 (11)	4 (40)	2 (33)	0	0.04***	<0.0001
Iliac arteries	4 (6)	2 (20)	1 (2)	1 (1)	0.3	0.03
Femoral arteries	20 (31)	3 (30)	3 (50)	0	0.6	<0.0001

Conclusion:

With the limitation of the small number of GCA patients included and of the absence of histological data on the temporal arteries of PMR patients, our study suggests that in PMR and GCA similarities exceed differences. These conditions could be different forms of the same disease. PET/CT, a minimally invasive technique, is an effective and objective method to evaluate inflammation in PMR/GCA, optimally discriminating patients with PMR/GCA complex from controls.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/similarities-exceeds-differences-in-the-pattern-of-joint-and-vascular-positron-emissioncomputed-tomography-uptake-in-polymyalgia-rheumatica-and-giant-cell-arteritis/