Background/Purpose:

Wholebody magnetic resonance imaging (WBMRI) is a new imaging modality where patients are scanned from “head to toe” in one single scan, but with a lower resolution than conventional MRI (cMRI). The purpose was to investigate the ability of WBMRI for detection of inflammation and structural damage in psoriatic arthritis (PsA) and spondyloarthritis (SpA), and to compare findings with dedicated cMRI.

Methods:

Patients with clinically active peripheral PsA (Moll and Wright, n=19) or axial SpA (ESSG, n=19) and healthy subjects (HS, n=12) were included. WBMRI was assessed for synovitis, bone marrow oedema (BME), and bone erosions at sites included in the 78-tender joint count (TJC). Furthermore, WBMRI fat infiltration, BME and bone erosions were evaluated in 23 discovertebral units (DVUs) and in sacroiliac joints (SIJ) (8 quadrants). Wholebody imaging were performed on a 3 tesla MRI unit with built-in bodycoil (sagittal and coronal T₁-weighted pre/post-contrast and STIR sequences), and 1½ tesla cMRI (SpA and HS: of spine and SIJ; PsA and HS: unilateral hand) were performed using T₁w pre/post-contrast and STIR sequences. The PsAMRIS-hand method (1) was used for scoring synovitis in finger joints in PsA and HS.

Results:

Characteristics median (range): PsA/SpA/HS age 49 (23-79)/42 (26-61)/32 (20-61) yrs. PsA/SpA disease duration: 4(0-34)/17(5-48) yrs; 78-TJC: 11(3-65)/3(0-17), 76-swollen joint count: 5(0-20)/1(0-5), and BASDAI score 45(9-85)/55(2-93) mm.

By WBMRI more than 97% of spinal DVUs and SIJ quadrants could be evaluated, whereas evaluation of peripheral joints for synovitis and BME was possible in 66 % and 55 % of joints, respectively. It was possible to evaluate 56% of the finger joints with WBMRI. BME assessed in 78 joints by WBMRI was significantly more frequent in PsA/SpA than in HS (p<0.05, see table). We found no statistically significant difference between groups in WBMRI synovitis assessed in all 78 joints, or only assessed in hand joints. In contrast, PsAMRIS-hand synovitis (scored 0-36) assessed by cMRI was higher in PsA than HS (P<0.0005).

The table shows median (range) scores of WBMRI and cMRI findings in joints, DVUs, and SIJ quadrants.   

	PsA		SpA		HS
	WBMRI	cMRI	WBMRI	cMRI	WBMRI	cMRI
78-joint: Synovitis (0-78)	12 (1-45)	–	10 (0-28)	–	10 (2-40)	–
78-joint: BME (0-78)	4 (0-25)*		2 (0-15)*	–	2 (0-5)	–
Spine: BME (0-23)	2 (0-6)*		1 (0-11)	1 (0-8)	0.5 (0-2)	0 (0-3)
Spine: Fat infiltration (0-23)	0 (0-7)		1 (0-18)	2 (0-20)*	0 (0-6)	0 (0-3)
Spine: Bone erosion (0-23)	0 (0-1)		0 (0-0)	0 (0-2)*	0 (0-1)	0 (0-1)
SIJ: BME (0-8)	0 (0-2)		0 (0-8)*	0 (0-8)*	0 (0-2)	0 (0-2)
SIJ: Fat infiltration (0-8)	0 (0-8)		0 (0-8)*	2 (0-8)*	0 (0-4)	0 (0-8)
SIJ: Bone erosion (0-8)	0 (0-6)		0 (0-8)	2 (0-8)*	0 (0-8)	0 (0-4)

Mann-Whitney test was used for comparing PsA/SpA with HS. *P<0.05.

Significant correlation was found between WBMRI and cMRI in spinal/SIJ fat infiltration (Spearman’s rho: 0.52/0.52, both P<0.005), SIJ BME (0.78, P<0.0001), and SIJ bone erosion (0.72, P<0.0001). In PsA, the sensitivity, specificity and accuracy of WBMRI synovitis in the hand were 35 %, 80% and 66 %, when cMRI was considered the gold standard reference.

Conclusion:

WBMRI showed higher scores of peripheral and axial BME in PsA and SpA, compared to HS. Highly significant correlation was found between WBMRI and conventional MRI assessments of axial BME, fat infiltration and bone erosions. WBMRI has potential value for assessing axial and peripheral disease manifestations in PsA and SpA.

Ref: 1) Østergaard, JRheum 2009

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/comparison-of-conventional-and-wholebody-magnetic-resonance-imaging-for-assessing-inflammation-and-structural-damage-in-psoriatic-arthritis-and-axial-spondyloarthritis/