M u s c ul o s kel et a l I m ag i n g • O r i g i na l R e s e a rc h

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Schoellnast et al. MRI Evaluation of Arthritis

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C E N T U R Y

MEDICAL

O F

IMAGING

Helmut Schoellnast1 Hannes A. Deutschmann1 Josef Hermann2 Gottfried J. Schaffler1 Pia Reittner1 Fritz Kammerhuber3 Dieter H. Szolar4 Klaus W. Preidler4 Schoellnast H, Deutschmann HA, Hermann J, et al.

Keywords: arthritis, bone, joint, MRI, musculoskeletal system DOI:10.2214/AJR.04.1798 Received November 19, 2004; accepted after revision May 25, 2005. 1Department

of Radiology, Medical University Graz, Graz, Austria.

2Department

of Internal Medicine, Medical University Graz, Graz, Austria.

3Division of

Radiology, Hospital of Barmherzige Brueder, Graz, Austria.

4Diagnostikum Graz Sued West, Weblinger Guertel 25, 8054

Graz, Austria. Address correspondence to K. W. Preidler. CME This article is available for 1 CME credit. See CME data for this article at www.ajronline.org or visit www.arrs.org for more information. AJR 2006; 187:351–357 0361–803X/06/1872–351 © American Roentgen Ray Society

AJR:187, August 2006

Psoriatic Arthritis and Rheumatoid Arthritis: Findings in Contrast-Enhanced MRI OBJECTIVE. Our objective was to define typical MRI findings of the wrist and the hand in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA). MATERIALS AND METHODS. Eighteen PsA and 21 RA patients with arthralgia of the wrist or hand joints underwent gadolinium-enhanced MRI of the wrist and hand. Two experienced radiologists interpreted abnormalities in consensus with respect to periarticular soft-tissue swelling, synovitis with or without effusion, periostitis, bone edema, bone erosions, bone cysts, and tenosynovitis. The distribution of the abnormalities also was evaluated. RESULTS. Erosions were statistically more frequent in patients with RA (p < 0.05). Periostitis was statistically seen more frequently in patients with PsA (p < 0.05). No statistically significant difference was found in the frequency of synovitis, bone marrow edema, bone cysts, and tenosynovitis between the two groups (p > 0.05). The radiocarpal joint, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints were significantly affected more frequently in patients with RA than in patients with PsA (p < 0.05), whereas the proximal interphalangeal joints were significantly more frequently affected in patients with PsA (p < 0.05). CONCLUSION. Periostitis and synovitis of the proximal interphalangeal joints are typical MRI findings in patients with PsA, whereas synovitis with erosions of the wrist, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints are typical findings in patients with RA. n rheumatoid arthritis (RA) and in psoriatic arthritis (PsA), the finger joints are usually the first joints affected [1, 2]. Although diagnosis is based primarily on clinical findings, it is sometimes difficult even for the trained rheumatologist to differentiate between these entities. This is especially true in cases of PsA sine psoriase. Radiographic changes in PsA are specific and differ from those in RA, but conventional radiography may also be normal in acute arthritis. Several studies that evaluated MRI in patients with RA [3–8] or with PsA [5, 9, 10] showed that MRI is more sensitive than conventional radiography in detecting early inflammatory joint processes. To our knowledge, no study has been performed comparing MRI findings of the wrist and hand in patients with PsA and RA. Therefore, the aim of our study was to define typical MRI findings in these patients.

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Materials and Methods Patient Population In a retrospective study, all patients diagnosed with PsA according to the criteria of Moll and Wright [11] and RA according to the revised American College of Rheumatology criteria [12], and who had undergone MRI of the wrist and hand in the past year as part of routine clinical care were recruited for the study. The study population consisted of 18 patients (six men and 12 women; mean age, 52 years; age range, 30–65 years) with clinically proven PsA and 21 patients (four men and 17 women; mean age, 59 years; age range, 33–80 years) with RA. Rheumatoid factor was tested for and found negative in all patients with PsA. The mean time between the onset of disease and MRI examination was 64 months in patients with PsA and 76 months in patients with RA. The indication for MRI examinations was reoccurrence of arthralgia. All examinations were part of routine clinical care and were performed within the clinical standard of our institutions. According to the guidelines of our institutional review board for retrospective studies, formal approval and informed consent were not required.

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Schoellnast et al.

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Data Acquisition MRI was performed with 1.5-T scanners (Magnetom Symphony, Siemens Medical Solutions). The slew rate was 86 T/msec; the gradient amplitude was 34 mT/m. Coronal T1-weighted spin-echo sequences (TR/TE, 440–500/20–23; bandwidth, 65 MHz; matrix size, 192 × 448; section thickness, 3 mm), transverse inversion time or coronal T1-weighted fast lowangle shot (FLASH) sequences with fat saturation (473–795/11; bandwidth, 70 MHz; flip angle, 60°; matrix size, 282 × 512; section thickness, 3–5 mm), and coronal contrast-enhanced (gadodiamide; Omniscan, Nycomed Amersham) T1-weighted spinecho sequences with fat saturation (540–648/23; bandwidth, 65 MHz; matrix size, 224 × 512; section thickness, 3 mm) were obtained. In addition, coronal T2-weighted turbo inversion recovery magnitude (TIRM) sequences (3,000/127; inversion time, 150 milliseconds; bandwidth, 130 MHz; flip angle, 170°; matrix size, 250 × 512; turbo factor, 13; section thickness, 4 mm) were available in 10 patients. The field of view was between 150 and 180 mm.

Data Analysis Data analysis was performed on a Magic View 1100 workstation (Siemens Medical Solutions) in consensus by two experienced radiologists blinded to the patients’ history. Analysis was performed with special respect to joint abnormalities (periarticular soft-tissue swelling and synovitis with or without intraarticular effusion), bone changes (bone marrow edema, focal bone erosions, bone cysts, and periostitis), and tenosynovitis. Synovitis and periostitis were defined as thickened synovial membrane or thickened periosteum with pronounced contrast enhancement compared with adjacent joints or bones, respectively. Bone erosions were diagnosed in patients who had evidence of a combination of focal bone marrow edema and destruction of the cortex. In each patient, analysis was performed for the radiocarpal joint, the midcarpal joints, the carpometacarpal joints, the metacarpophalangeal joints, the proximal interphalangeal joints, and the interphalangeal joint of the

thumb. The distal interphalangeal joints were not evaluated because they were not sufficiently depicted in many patients. Analysis of bone changes was performed for the distal radius and ulna, the carpal bones, the metacarpal bones, the proximal phalanges, and the middle phalanges. The distal phalanges were not depicted sufficiently.

Statistical Analysis Statistical analysis was performed using the SPSS software package. The significance of differences in frequency and localization between both groups was tested using the chi-square test. Two-tailed values were used, and probability values of less than 0.05 were considered significant.

Results Table 1 shows the MRI findings in patients with PsA and RA. Periostitis was statistically more frequent in patients with PsA than in patients with RA (p < 0.05). Seventy-eight percent of the patients with PsA showed periostitis; however, none of the patients with RA did (Fig. 1). Erosions were statistically more frequent in patients with RA (p < 0.05) (Fig. 2). Eighty-six percent of patients with RA showed erosions compared with 17% of patients with PsA. No statistically significant difference was noted in the frequency of synovitis (Fig. 3), bone marrow edema, bone cysts, and tenosynovitis between the two groups (p > 0.05). The radiocarpal joint, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints were significantly more frequently affected in patients with RA than in patients with PsA (p < 0.05). Thirty-nine percent of patients with RA showed synovitis, bone marrow edema, erosions, or cysts of the radiocarpal joint compared with 6% of patients with PsA. The midcarpal joints were affected in 78% of the patients with RA compared with 11% of patients with PsA. The carpometacar-

TABLE 1: Frequency of Findings in Joints and Bones of Patients with Rheumatoid Arthritis and Psoriatic Arthritis Clinical Finding

Rheumatoid Arthritis (%)

Psoriatic Arthritis (%)

Periarticular soft-tissue swelling

28

44

Synovitis

95

83

Bone marrow edema

71

83

erosionsa

86

17

Bone cysts

14

28

Periostitisa

0

78

43

56

Bone

Tenosynovitis a p < 0.05.

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pal joints were affected in 62% of patients with RA and in 17% of patients with PsA. The metacarpophalangeal joints were affected in all patients with RA compared with 72% of patients with PsA. The proximal interphalangeal joints were significantly affected more frequently in patients with PsA. Seventy-eight percent of patients with PsA had affected proximal interphalangeal joints compared with 43% of patients with RA. Discussion The diagnosis of RA or PsA is primarily based on clinical findings and laboratory tests, but sometimes it is difficult to differentiate among RA, PsA, or other chronic inflammatory joint diseases. The 1987 American Rheumatism Association (ARA) revised criteria [13] described a method to classify patients having an RA or non-RA condition based on a combination of variables that are sensitive and specific to the classification of RA. The variables are morning stiffness; soft-tissue swelling of three or more joint areas; swelling of the proximal interphalangeal, metacarpophalangeal, or radiocarpal joints; symmetric swelling; rheumatoid nodules; the presence of rheumatoid factor; and erosions in any peripheral joint on radiographs. Radiographic changes in PsA differ from those in RA, as evidenced by a lower frequency of periarticular osteopenia and a higher prevalence of distal interphalangeal erosions along with the presence of tuft changes, pencil-in-cup changes, bone proliferations, and bone ankylosis [14]. However, conventional radiography may be normal in patients with acute RA or PsA. In contrast, MRI has reportedly enabled physicians to detect bone marrow edema and active synovitis visually long before changes are detectable on conventional radiographs [3, 6, 7, 15–18]. It is reported that introducing MRI into the diagnostic criteria for early RA may contribute to a more accurate diagnosis in patients suspected of having RA. Sugimoto et al. [8] achieved a sensitivity of 96% and a specificity of 86% for the diagnosis of RA using MRI. In their study, the MRI criterion for RA was gadolinium enhancement with a bilateral distribution in the wrist, metacarpophalangeal joint, proximal interphalangeal joints, or all three. In the same patient population, ARA-revised criteria for RA showed sensitivities of 69% and 77% and specificities of 96% and 91% for the traditional format and classification tree format, respectively. McQueen et al. [15, 16] reported that a high pro-

AJR:187, August 2006

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MRI Evaluation of Arthritis portion of RA patients develop MRI erosions very early in their disease when conventional radiography is frequently normal and that MRI scans of the wrist, taken when patients first present with RA, can predict radiographic erosions at 2 years. In a study by Ostergaard et al. [17], MRI detection of new radiographic erosions preceded conventional radiography detection by a median of 2 years. Few studies have investigated MRI findings of the hand in patients with PsA [5, 10].

Offidani et al. [10] showed that in patients with psoriasis but without clinically evident arthritis, joints were frequently affected. They reported periarticular edema and synovitis/intraarticular effusion as the two most frequent findings (36% and 44%, respectively). Periostitis, a frequent finding in our patient population with PsA, was not addressed as a typical finding in the study by Offidani et al. [10]. We consider the different patient populations (absence of acute clinical arthropathy in the

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study by Offidani et al. versus acute clinical arthropathy in our study) as the reason for this. Savnik et al. [5] reported that MRI of the wrist and finger joints in inflammatory joint disease at 1-year intervals predicts bone erosions in patients with RA but not in patients with PsA. In another study [19], the authors reported a significantly higher frequency of bone marrow edema in patients with established RA (> 3 years) compared with patients with early RA (< 3 years), arthritis other than

B

Fig. 1—52-year-old man with clinically proven psoriasis. A, Coronal T1-weighted spin-echo fat-saturated MR image after administration of contrast agent (TR/TE, 620/20) reveals periosteal enhancement of proximal phalanx of third digit (arrows) as sign of periostitis. B, Radiograph obtained 2 months after MRI shows proximal phalanx of third digit (arrows) without evidence of preceding periostitis. Note that radiographs are provided for case illustration. Systematic comparison between MRI and radiographs was not performed because of lack of radiographs in temporal proximity to MRI examination.

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Schoellnast et al. Fig. 2—74-year-old woman with clinically proven rheumatoid arthritis. A, Coronal T1-weighted spin-echo MR image shows focal decreased signal intensity in head of metacarpal bone of third ray consistent with barearea bone erosion (arrow). (Fig. 2 continues on next page)

A RA (including patients with reactive arthritis, PsA, and mixed connective tissue disease), or arthralgia. However, patients with PsA (eight patients) were only a small subgroup in this study, and therefore they were not evaluated separately. Jevtic et al. [9] reported that the degree and extent of periarticular soft-tissue involvement was greater in six of 13 patients with PsA compared with patients with RA. The authors stated that the joint capsule may not be the primary target of the disease process in PsA but may become involved later in the disease course. In our study population, the difference in periarticular soft-tissue swelling between patients with PsA and those with RA was 16%, with the higher incidence in the PsA group, but the difference did not

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reach statistical significance. However, the disease duration in the study by Jevic et al. [9] was less than 2 years; and findings in an early disease course of RA and PsA cannot be transferred to established disease courses as present in our study. To our knowledge, no study has been performed comparing MRI findings in patients with PsA and RA. Our results showed statistically significant differences in MRI findings of the hand and the wrist in patients with RA and PsA. Periosteal contrast enhancement as a sign of periostitis was significantly more frequent in patients with PsA than in patients with RA. Seventy-eight percent of patients with PsA showed periostitis; however, none of the patients with RA did. Con-

versely, bone erosions were significantly more frequent in patients with RA than in patients with PsA. The frequency of findings in patients with RA is in accordance with a study by Boutry et al. [20], who reported synovitis of the wrist and metacarpophalangeal joints in 93% and 90%, respectively, of patients with early RA. In our study, 95% of patients with RA showed synovitis. Bone erosions were reported in the wrist joints in 80% and in the metacarpophalangeal joints in 77% of patients. In our study, 86% of patients with RA had bone erosions. The similar frequency of these findings despite the different patient population (early disease in the study by Boutry et al. [20] vs established disease in our study) can be explained by the fact that the patients in our study also had acute clinical arthropathy and thus also showed signs of acute arthritis. Aside from the difference in frequency of joint and bone abnormalities, patients with RA and PsA also showed significant differences in articular distribution of abnormalities. The radiocarpal joint, the midcarpal joints, the carpometacarpal joints, and the metacarpophalangeal joints were significantly more frequently affected in patients with RA than in patients with PsA, whereas the proximal interphalangeal joints were more frequently affected in patients with PsA. The frequency of proximal interphalangeal joint involvement in patients with PsA seems quite high and might be explained by the long-term disease course of our study population because it is well known that in PsA the distal interphalangeal joints are affected first, followed by the proximal interphalangeal joints and the remaining joints of the hand and the wrist. The MRI protocol in this study was the standard protocol of our institutions for diagnosis of inflammatory disorders, including T1-weighted spin-echo, T1-weighted fat-saturated FLASH, and contrast-enhanced fatsaturated T1-weighted spin-echo sequences. T2-weighted TIRM sequences were also performed but were not available in all patients. However, Schmid et al. [21] reported that STIR images and T1-weighted contrast-enhanced fat-suppressed MR images show almost identical imaging patterns in bone marrow abnormalities. One can assume that this is also valid for TIRM images. Our study has several potential limitations. First, it was a retrospective analysis of a small patient population, which might have influenced the significance of the find-

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MRI Evaluation of Arthritis

B

C

Fig. 2 (continued)—74-year-old woman with clinically proven rheumatoid arthritis. B and C, Dorsovolar (B) and oblique (C) radiographs obtained 8 days before MRI show no evidence of bone erosion (arrows) in head of metacarpal bone of third ray. Note that radiographs are provided for case illustration. Systematic comparison between MRI and radiographs was not performed because of lack of radiographs in temporal proximity to MRI examination.

ings. However, the tendency toward PsA or RA was pronounced in some findings. This is especially valid for periosteal enhancement as a sign of acute periostitis, which was a frequent finding in patients with PsA and was not found in patients with RA. This seems consistent because periosteal thickening and bone proliferations are typical signs of PsA on radiographs [12] and can be considered as later signs of periostitis. Second, only patients classified as having RA or PsA were included in our retrospective

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study; therefore, the results cannot be extrapolated to all patients who complain of arthralgia or arthritis because of the assessment of selected subjects. Prospective studies are necessary to prove whether the findings shown in our study can help differentiate these two arthritides at a subclinical or early clinical stage. Third, MRI was only performed of the wrist and hand, although RA and PsA are systemic diseases with the involvement of multiple joints, especially RA. However, the wrist and hand

joints are frequently affected in RA and affected in 85% of patients with PsA. In addition, the distal interphalangeal joints were not evaluated because of lack of sufficient depiction in many patients. That might have influenced the results because PsA predominantly affects these joints. In conclusion, MRI may not only detect radiologic features supporting the development of an inflammatory disorder but may also help discriminate between RA and PsA, particularly in those patients who present with a

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Schoellnast et al.

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B

Fig. 3—47-year-old man with clinically proven rheumatoid arthritis. A, Coronal T1-weighted, turbo spin-echo, fat-saturated MR image after administration of contrast material (TR/TE, 620/20) reveals soft-tissue swelling and contrast enhancement of synovial membrane of proximal interphalangeal joint of fourth ray as sign of synovitis (arrows). B, Radiograph obtained 10 days before MRI shows soft-tissue swelling (arrows) and narrowing of joint space of proximal interphalangeal joint of fourth ray as typical finding of arthritis. Note that radiographs are provided for case illustration. Systematic comparison between MRI and radiographs was not performed because of lack of radiographs in temporal proximity to MRI examination.

polyarthritis involving the hand and wrist joints. Further studies are necessary to prove whether the findings shown in our study can help differentiate PsA and RA at an early stage.

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