Session Information
Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose: MRI is often used to evaluate muscle inflammation in myositis. Muscle edema on fat-suppressed (short tau inversion recovery, STIR) sequences is thought to represent active inflammation. Dermatomyositis (DM) and polymyositis (PM) affect very often thigh muscles. However, it is unclear whether DM and PM differ in the respective involvement of the various thigh muscle groups. In this study, we aimed to assess which thigh muscle groups are preferentially inflamed in DM and PM, respectively, using MRI fat-suppressed sequences.
Methods: We analysed 72 patients from 2 Rheumatology centers (Reggio Emilia & Bari, Italy), 31 with DM and 41 with PM diagnosed according to Bohan and Peter criteria. MRI edema (1= present, 0= absent) was assessed bilaterally on STIR sequences in 17 thigh/pelvic floor muscles. An MRI composite edema score (0-17) was calculated by adding the separate scores bilaterally and dividing them by two as described in Clin Exp Rheumatol 2012; 30:570. The (single measures) intraclass correlation coefficient (ICC) between the Radiologists involved was 0.78. Fisher’s exact test was used for comparison of binomial data.
Results: Age (years, mean±SD) was similar in patients with DM (53 ± 16) and PM (56 ± 16). The F:M ratio was similar in DM (23/8) and PM (32/9). Disease duration (months, mean±SD) was shorter (20±31) in DM than in PM (52±68) (p=0.02). The Table shows the frequency (n° and %) of all thigh muscle groups involved in DM and PM.
|
TABLE |
Compartment |
DM (n=31) |
PM (n=41) |
p value |
|
|
|
|
|
|
|
Gluteus maximus |
axial |
17 (55%) |
13 (32%) |
0.06 |
|
Quadratus femoris |
axial |
9 (29%) |
1 (2%) |
0.002 |
|
Vastus lateralis |
anterior |
15 (48%) |
11 (27%) |
0.08 |
|
Ileopsoas |
axial |
8 (26%) |
3 (7%) |
0.046 |
|
Vastus medialis |
anterior |
14 (45%) |
10 (24%) |
0.08 |
|
Tensor fasciae latae |
anterior |
12 (39%) |
4 (10%) |
0.005 |
|
Rectus femoris |
anterior |
16 (52%) |
10 (24%) |
0.03 |
|
Sartorius |
anterior |
13 (42%) |
11 (27%) |
0.2 |
|
Gracilis |
medial |
15 (48%) |
8 (20%) |
0.01 |
|
Pectineus |
medial |
8 (26%) |
2 (5%) |
0.02 |
|
Adductor longus |
medial |
9 (29%) |
6 (15%) |
0.16 |
|
Adductor brevis |
medial |
12 (39%) |
5 (12%) |
0.01 |
|
Adductor magnus |
medial |
10 (32%) |
10 (24%) |
0.6 |
|
Short head biceps femoris |
posterior |
10 (32%) |
6 (15%) |
0.09 |
|
Long head biceps femoris |
posterior |
12 (39%) |
12 (29%) |
0.5 |
|
Semimembranous |
posterior |
10 (32%) |
8 (20%) |
0.3 |
|
Semitendineous |
posterior |
14 (45%) |
10 (24%) |
0.08 |
Conclusion: Compared with PM, DM affects more frequently some muscle groups. Posterior muscle groups discriminate poorly between DM and PM. These findings may be useful for differential diagnostic purposes in patients with histological DM without the typical skin rash as well as to target physiotherapy at more frequently affected muscles.
To cite this abstract in AMA style:
Pipitone N, Notarnicola A, Spaggiari L, Levrini G, Scardapane A, Iannone F, Lapadula G, Zuccoli G, Salvarani C. Different Patterns of Involvement of Thigh Muscles in Dermatomyositis and Polymyositis Using Fat-Suppressed Magnetic Resonance Sequences [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/different-patterns-of-involvement-of-thigh-muscles-in-dermatomyositis-and-polymyositis-using-fat-suppressed-magnetic-resonance-sequences/. Accessed .« Back to 2015 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/different-patterns-of-involvement-of-thigh-muscles-in-dermatomyositis-and-polymyositis-using-fat-suppressed-magnetic-resonance-sequences/