MR Imaging Findings of Acute Gouty Arthritis

PURPOSE: The purpose of this study was to describe the clinical and MR imaging features of acute gouty arthritis and to define the characteristic findings that would be helpful for differentiating acute gouty arthritis from septic arthritis. MATERIALS AND METHODS: The authors retrospectively studied seven patients who suffered from acute gouty arthritis. The MR imaging findings were analyzed by two musculoskeletal radiologists who focused on joint effusion, subchondral bone erosion, bone marrow edema, synovial thickening (regular and even, or irregular and nodular), and the soft tissue changes (edema or abscess). The clinical records of the patients were reviewed with regard to age and gender, the clinical presentation and the laboratory findings (serum uric acid, WBC, erythrocyte sedimentation rate, C-reactive protein and synovial fluid culture). RESULTS: The patients consisted of six men and one woman whose mean age was 41 years (age range: 24-65 years). The joints involved were the knee (n=6), and ankle (n=1). Two patients had medical histories of gouty attacks that involved the first metatarsophalangeal joint. In six cases, the serum uric acid level during acute attacks was elevated. In all the patients, the affected joint became swollen, hot, erythematous and extremely tender, and this was accompanied by a high ESR and a high C-reactive protein level at the time of presentation. The results of Gram stain and culture of the synovial fluid were negative. In all patients, the MR images showed large amounts of joint effusion, thick irregular and nodular synovial thickening and soft tissue edema without subchondral bone erosions and soft tissue abscess. In one case, subchondral bone marrow edema of the medial femoral condyle was present. In five cases, there were multiple low signal foci in the joint on the spin-echo T2-weighted MR image. CONCLUSION: Even though the MR imaging findings of acute gouty arthritis are nonspecific, it should be considered as a possible diagnosis when a large amount of joint effusion, irregular and nodular synovial thickening and soft tissue edema without subchondral bone erosion, bone marrow edema or soft tissue abscess are seen in the knee or ankle joint, and especially if this is accompanied by the clinical and laboratory features of infection.

Transarticular Invasion of the Sacroiliac Joints by Malignant Pelvic Bone Tumors

PURPOSE: To describe modes of transarticular invasion, with reference to the size and location of a tumor, the anatomic characteristics of invaded cartilage, and the existence of ankylosis in SI joint. MATERIALS AND METHODS: Eleven histologically confirmed malignant pelvic bone tumors involving transarticular invasion of sacroiliac joints, were retrospectively analysed. Transarticular invasion of a joint was defined as involvement of its opposing bones. The anatomic site and size of the tumors were analysed, and invaded sacroiliac joint was divided into upper, middle and lower parts on the basis of the anatomic characteristics of the intervening cartilage: synovial hyaline or fibrous ligamentous. The existence of ankylosis was determined, and transarticular invasion directly across a joint was classified as direct invasion. Extension of tumors around a joint from its periphery to the opposing bone were considered as indirect invasion. RESULTS: All tumors were located near the sacroiliac joint, eight at the ilium and three at the sacrum. Six invasions were indirect and five were direct. Average tumor area was larger in indirect cases than in direct: 191.8 cm2 vs. 69.6 cm2. In all indirect invasions, a huge soft tissue mass abutted onto the peripheral portion of the sacroiliac joint. In five of six cases of indirect transarticular invasion, the upper part of the joint posteriorly located fibrous ligamentous cartilage. In the other, the lower part was invaded, and this involved a detour around the joint space, avoiding the invasion of intervening cartilage. Ankylosis occurred in one of the indirect cases. Among the five cases of direct invasion, there was invasion of the posteriorly located ligamentous fibrous cartilage in three without ankylosis. In the other two cases, involving ankylosis, the synovial hyaline cartilage was invaded directly at the lower part of the joint. CONCLUSION: Transarticular invasions of sacroiliac joint via fibrous cartilage are most common. Ankylosis of the sacroiliac joint facilitates hyaline cartilage invasion. We consider that in transarticular invasion of malignant pelvic bone tumors, indirect invasion is more common than direct.

MR Findings of Tuberculous Arthritis: Significance of Tuberculoma

PURPOSE: To determine the magnetic resonance (MR) imaging findings of tuberculous arthritis, and the frequency-in such cases-with which tuberculoma occurs. MATERIALS AND METHODS: MR images of 26 patients (M:F, 14:12; mean age, 46.2 years) with pathologically proven tuberculous arthritis were retrospectively reviewed. The presence of joint effusion, subchondral erosion, synovial proliferation and soft tissue abscess, and whether the inner wall of this abscess was smooth, were assessed. In particular, we determined whether a nodular lesion which showed low SI on T1WI, central low SI with peripheral high SI on T2WI, and rim enhancement on contrast study, was a tuberculoma. RESULTS: The joints involved were those of the knee (n=7), hip (n=7), shoulder (n=4), sacroiliac region (n=3), elbow (n=3), and ankle (n=2). Joint effusion was noted in 15 cases (58%), and subchondral erosion in 24(92%). synovial proliferation was found in 23 cases (88%), and soft tissue abscess in 24 (92%). The inner wall of this abscess was irregular in 17 cases (71%). A tuberculoma was present in intra- or extra-articular soft tissue in 18 cases (69%). CONCLUSION: The MR findings of tuberculous arthritis were subchondral erosion, synovial proliferation, and soft tissue abscess. The presence of a tuberculoma in intra- or extra-articular soft tissue, a specific finding in tuberculous arthritis, was noted in 69% of our cases.

MR Findings of Transient Synovitis of the Hip

PURPOSE: To evaluate the MR findings of transient synovitis of the hip in children. MATERIALS AND METHODS: Between 1993 and 1997, MR imaging was performed in 30 children(male:female=22:8) in whom transient synovitis had been clinically diagnosed. In 20 of these 30 patients, Gd-en-hanced study was also performed. The signal intensity of bone marrow of the femur, the synovial enhancement pattern and the amount of hip joint effusion in affected hips were evaluated; the last-mentioned was determined using the volume measurement method. RESULTS: In 29 patients(97 %), no abnormal signal intensity was seen in bone marrow of the femur in affected hips. Gd-enhanced MR imaging revealed synovial enhancement of affected hip joints, as follows: minimal en-hancement in eight patients(40 %), moderate enhancement in eight(40 %), and strong enhancement in four( 20%). No abnormal enhancement was demonstrated in bone marrow of the femur or adjacent soft tissue. The mean amount of joint effusion of affected hips was 2.7 +/- 1.7(range, 0.2 -18.9)ml; statistically, this was much greater than that of contralateral hip (p<0.01). CONCLUSION: The MR findings of transient synovitis of the hip in children were normal bone marrow signal intensity of the femoral head, moderate or strong synovial enhancement, and asymmetric hip joint effusion.

Dynamic MR Imaging of Internal Derangements of the Temporomandibular Joint: Correlation with Clinical Signsand Symptoms

PURPOSE: To evaluate the correlation between findings of dynamic magnetic resonance (MR) imaging of thetemporomandibular joint (TMJ) and clinical findings in patients with internal derangement of the TMJ. MATERIALS AND METHODS: Dynamic MR images of 130 joints of 65 patients (17 men and 48 women aged 14 to 74 ; mean age, 34)with internal derangement of the TMJ were obtained using a 1.5-T MR imaging system. MR findings of anteriordisplacement, disc deformity and degenerative change were correlated with clinical findings including joint pain,clicking sound, crepitation and maximal mouth opening (MMO). RESULTS: Among 62 joints with TMJ pain, 32 showedanterior displacement without reduction, 15 showed disc deformity and 19 showed degenerative change. Among 49joints in which there was a clicking sound, 24, 8 and 12 joints, respectively, showed the above-mentionedfindings, while in seven with crepitation, these same findings were evident in five, six and four joints,respectively. Bilateral and unilateral joint disorders were observed in 17 and five patients, respectively, among22 with MMO less than 30mm and in 11 and 18 of 42 patients with MMO between 30mm and 60mm. CONCLUSION: On MRimaging, patients with MMO less than 30mm usually showed bilateral joint disorders and those with crepitationshowed chronic change. This indicates that there is high association between clinical findings of internalderangement of TMJ and MR findings.

Efficacy of MR Arthrography in the Diagnosis of the Acetabular Labral Tear

PURPOSE: To determine the accuracy of magnetic resonance (MR) arthrography in the detection and staging of lesions of the acetabular labrum. MATERIALS AND METHODS: Fifteen hips of 14 patients with chronic hip pain and clinical suspicion of labral lesions were examined with direct or indirect MR arthrography and underwent subsequent arthroscopic evaluation. The study population consisted of six women and eight men aged between 40 and 59 years. Nine arthrograms were obtained intra-articular administration of gadolinium solution, and six involved articular motion exercise after intravenous administration of gadolinium solution. In 14 cases a phased-array pelvic coil was used, and a shoulder coil in one. Fat-suppressed T1-weighted images were obtained in the coronal, oblique coronal and oblique axial planes, and T1-and T2-weighted images were obtained in the axial plane. Labral lesions were graded according to the Czerny classification and evaluated on the basis of presence or absence of a tear and location (anteroinferior, anterosuperior, superior, posterosuperior, posteroinferior). The findings were then correlated with the arthroscopic findings. RESULTS: After direct and indirect MR arthography, the findings-based on the Czerny classification -were as follows : stage IA:3; IB:1; IIA:8; IIB:1; IIIA:4; IIIB:0. MR arthrography also showed that seven cases were located in the anterosuperior portion of the labrum, seven in the superior portion, and three in the posteroinferior portion. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MR arthrography for diagnosis of the labral tear was 92%, 75%, 92%, 75 %, and 88 %, respectively. CONCLUSION: In this preliminary study, MR arthrography appears to be a promising imaging modality for accurate diagnosis and useful for screening patients with chronic hip pain.

MRI of Ganglion Cysts in Uncommon Sites or with Atypical Appearance

Ganglion cysts are common lesions which are most often found around the hands and feet. Magnetic resonance (MR) imaging is seldom performed; cysts are identified incidentally on MR images obtained for the purpose of evaluating other disorders. Clinically complicated ganglions are often confused with other more serious tumors, and MR examination is thus requested. Ganglions arising from uncommon sites or showing unusual MR findings can lead to wrong diagnosis. Thus, a thorough knowledge of potential sites and of the MR findings of unusual ganglion cysts can prevent mistake s. We therefore describe the MR findings of unusual ganglion cysts, including complicated ganglions, cruciate ligament ganglion cysts, meniscal cysts, labral cysts, ganglions in shoulder notches and tarsal tunnels, and intermuscular ganglion cysts.

MR Imaging of the Temporomandibular Joint in Patient with Acute Mandibular Condylar Fracture

PURPOSE: To analyze various MR imaging findings and thus evaluate the usefulness of MR imaging of the tem-poromandibular joint in patient with acute mandibular condylar fracture. MATERIALS AND METHODS: MR imaging was performed within 1week after trauma in 25 patients (total joints s-tudied=31) in whom condylar fracture had been diagnosed by simple radiographs. We analyzed the signal intensity of bone marrow and disk, displacement of bone fragment and disk, deformity. In addition, MRI findings of retrodiskal tissue, joint capsule and joint effusion were eualuated. RESULTS: No abnormal signal intensity was noted in bone marrow or disk. Displacement of a condylar fracture fragment was observed in 24 joints(77 %) (anteromedial, 63 %; medial, 25 %; anterior, 4%; anterolateral, 4 % ; and lateral, 4 %). Disk displacement occurred in 23 joints(74 %) (anteromedial, 65 %; medial, 9 %; anterior, 18%; anterolateral, 4 %; and lateral, 4 %). In 17 joints (55 %) the disk was displaced along with the fractured condylar fragment, and disk deformity was noted in five joints(16 %). MR imaging (T2WI) revealed a capsular tear(n=1), joint effusion(n=26), and high signal intensity in the retrodiskal tissue(n=6). CONCLUSION: MR imaging provided information concerning condylar fragments, disks, retrodiskal tissue, capsules, and joint effusion. In patients with acute mandibular condylar fracture, MRI is therefore useful for evaluation of the temporomandibular joint.

MR Imaging of Osteosarcoma: Emphasis on Joint Involvment

PURPOSE: To evaluate MR imaging findings of joint involvement in patients with osteosarcoma MATERIALS AND METHODS: Among 166 patients with osteosarcoma treated between January 1993 and July 1998, 67(44 men and 23 women,mean age 20 years) whose tumors had invaded the epiphysis were included in this study. Those with preserved normalbone marrow signal intensity between the tumor and cortical bone were excluded. Tumors were located around theknee (n=52), the hip (n=7), the shoulder (n=5), the ankle (n=2), or the wrist (n=1). For all patients,pre-operative spin echo pre- and post-contrast enhanced MR images were obtained. In all cases, we assessed thepresence or abscence of intrasynovial mass, intraarticular disruption of cortical bone and articular cartilage,and joint effusion, and also evaluated the mass around the cruciate ligaments of the knee. All patients underwentsurgery and MR findings were correlated with the results of pathologic examinations. RESULTS: In six patients thetumor was found to involve the knee joint. Sensitivity and specificity for the intrasynovial mass (n= 6),intraarticular disruption of cortical bone and articular cartilage (n= 19), mass around the cruciate ligaments (n=7), and joint effusion (n= 12) were 83.3%, 100%, 83.3%, 33.3% and 98.4%, 78.7%, 95.6%, 83.6%, respectively, whileaccuracy for the intrasynovial mass and mass around the cruciate ligaments was 97% and 94.2% respectively. CONCLUSION: If MR imaging indicates the presence of a mass in the synovial cavity or around the cruciateligaments, this is suggestive MR findings of joint involvement.

A Relationship Between Amount of Joint Effusion, Disk Displacement and Presence of Pain in theTemporomandibular Joint: MR Imaging

PURPOSE: To correlate MR findings of amount of temporomandibular joint effusion with joint pain and disk displacement. MATERIALS AND METHODS: In 57 patients, 114 temporomandibular joints with symptoms of disorder(presence of clinical pain) were imaged. Closed and open mouth sagittal spin echo (SE) T1-weighted images (WI) and fast spin echo (FSE) T2-WI were obtained. We classified the amount of joint effusion into grades. Joint effusion was classified as either Grade I, II or III, as follours : in sagittal FSE T2-WI, a long diameter of joint effusion shorter than 1/3 of the diameter of the convex margin of temporal eminence was grade I; longer than 2/3 was grade III; between grade I and III was grade II. Disk displacement was classified as either with or without reduction in the open mouth position. These findings were correlated with one another and statistically analyzed. RESULTS: In 29 cases with joint pain (37%) and in 34 cases without pain (63%) there was no evidence of joint effusion; there were, however, more grade I joint effusion cases with pain (14 ; 60.9%) than without pain (9 : 39.1%). Cases of joint pain increased in proportion to grade of joint effusion, which was statistically significant (p<0.05). In joints without disk displacement, the largest grouping was that which showed no effusion (39 ; 72.2%) ; no joints showed grade III effusion. Cases of joint effusion decreased in proportion to grade of effusion. In joints with disk displacement, cases of joint effusion tended to increase in proportion to the grade of effusion. CONCLUSION: MR findings of amount of temporomandibular joint effusion correlate with joint pain and anterior disk displacement.

Volumetric measurement of the inflamed synovium of rheumatoid wrist joint for the evaluation of synovitis and remission

PURPOSE: To evaluate the changes and remission of disease activity with changes in inflamed synivial volumes of rheumatoid joints after therapy. MATERIALS AND METHODS: Seven rheumatoid arthritis patients who had been treated with antiinflammatory drugs were followed up. Using NIH imaging and a segmentation technique, pre- and post-enhanced images were measured in subtracted images. Intra- and interobserver variation were evaluated by two radiologists(A and B), using two independent measurements. For comparison, the cases were assigned to one of two groups : remission and non-remission. Changes in ESR and total joint counts(TJC) after therapy were compared with inflamed synovial volumes. RESULTS: Intraobserver variations were 3.2% and 2.7% in A and B, respectively, interobserver variation between A and B was 7.1%. Changes in inflamed synovial volumes correlated well with those in ESR (r=0.88, p<0.009) and TJC (r=0.78, p<0.037) after therapy. Changes between the remission and non-remission group were insignificant, however. CONCLUSION: Changes in inflamed synovial volumes reflect those in the activity of rheumatoid arthritis between pre- and post- treatment. This technique may be used as a tool for predicting therapeutic response in rheumatoid arthritis cases. Changes in inflamed synovial volumes are of limited value, however, in predicting the remission of rheumatoid arthritis after therapy.

Volumetric measurement of the inflamed synovium of rheumatoid wrist joint for the evaluation of synovitis and remission

PURPOSE: To evaluate the changes and remission of disease activity with changes in inflamed synivial volumes of rheumatoid joints after therapy. MATERIALS AND METHODS: Seven rheumatoid arthritis patients who had been treated with antiinflammatory drugs were followed up. Using NIH imaging and a segmentation technique, pre- and post-enhanced images were measured in subtracted images. Intra- and interobserver variation were evaluated by two radiologists(A and B), using two independent measurements. For comparison, the cases were assigned to one of two groups : remission and non-remission. Changes in ESR and total joint counts(TJC) after therapy were compared with inflamed synovial volumes. RESULTS: Intraobserver variations were 3.2% and 2.7% in A and B, respectively, interobserver variation between A and B was 7.1%. Changes in inflamed synovial volumes correlated well with those in ESR (r=0.88, p<0.009) and TJC (r=0.78, p<0.037) after therapy. Changes between the remission and non-remission group were insignificant, however. CONCLUSION: Changes in inflamed synovial volumes reflect those in the activity of rheumatoid arthritis between pre- and post- treatment. This technique may be used as a tool for predicting therapeutic response in rheumatoid arthritis cases. Changes in inflamed synovial volumes are of limited value, however, in predicting the remission of rheumatoid arthritis after therapy.

MRI Findings of Sacroiliitis in Ankylosing Spondylitis: Roles of MPGR and Delayed Post-contrast T1-weightedImages

PURPOSE: For early diagnosis of sacroiliitis in spondyloarthropathy, the MRI findings of sacroiliitis, roles of MPGR (Multiplanar Gradient Recalled Acquisition in Steady State), and delayed post-contrast T1-weighted images were evaluated. MATERIALS AND METHODS: Twenty six patients with seronegative spondyloarthropathy (probable clinical diagnosis of ankylosing spondylitis) were grouped as either less than radiographic grade I (group A) or more than grade II (group B). The MRI findings of both sacroiliac joints were evaluated in every patient, and predominant sites were determined. The two groups were then compared. In 17 patients, the number of enhancing panni seen on early and delayed post-contrast T1-weighted images was counted and compared between the two groups. RESULTS: Panni were found in all cases, and in both groups, predominant patterns of involvement were the lower and iliac aspects of the sacroiliac joints in both groups; in group A, the synovial joints and punctate pannus were predominantly involved, and in group B, the ligamentous joints as well as the synovial joints and linear pannus. In group B, more periarticular fat accumulation than periarticular osteitis was found. For the evaluation of changes in joint space, MPGR images were superior to spin echo images. For the delineation of enhancing pannus less than radiographic grade I, delayed post-contrast images were statistically superior to those which were early post-contrast. CONCLUSION: MRI can detect early sacroiliitic change according to the predominant sites of involvement, and delayed post-contrast images play a role in the diagnosis of early sacroiliitis. MPGR imaging is good for the evaluation of joint space change.

Radiologic Findings of Sacroiliitis: Emphasis on MR Findings

PURPOSE: To compare the characteristic MR findings of infectious sacroiliitis (IS) and ankylosing spondylitis(AS). MATERIALS AND METHODS: We retrospectively reviewed MR findings in eight patients with IS (pyogenic in six, tuberculosis in two) confirmed by culture and clinical follow-up, and in six with AS by HLA-B27 typing. A control group of 13 asymptomatic volunteers was formed, and they underwent MRI. Findings were analysed for morphology, degree of bone erosion, and adjacent soft tissue change. CT findings of AS in four patients and IS in four were also compared to MR findings. RESULTS: MR characteristics of IS included unilaterality (100 %), abnormal cartilage signal intensity (100 %), bone marrow change (100 %), contrast enhancement (100 %), erosion (63 %), and soft tissue change (63 %). MR findings of AS showed bilaterality (67 %), abnormal cartilage signal intensity (80%), bone marrow change (80 %), erosion (80 %), contrast enhancement (44 %) and soft tissue change (10 %). CT scan showed bony sclerosis and erosion (86 %), and abnormal joint space (71 %). CONCLUSION: MR findings of sacroiliitis were loss of thin zone of a cartilage and erosions on T1-weighted image, and increased signal intensity on T2-weighted image. MRI is regarded as a useful diagnostic method where conventional diagnosis is difficult, and is able to image cartilage abnormalities directly and noninvasively. Significant differences in MR findings between IS and AS were not noted, however.

The Roles of MR Imaging in Monitoring Therapeutic Effectiveness in Rheumatoid Arthritis: Preliminary Result

PURPOSE: It is difficult to determine objectively therapeutic response in rheumatoid arthritis. This study was carried out in order to assess the feasibility of MR imaging to determine disease status following antirheu-matoid medication. MATERIALS AND METHODS: Eight patients with rheumatoid arthritis underwent MR studies before treatment and approximately one year after the beginning of antirheumatoid medication. Coronal images were obtained, using a T1- and T2-weighted spin echo(n=8), contrast-enhanced T1-weighted images(n=8) and dynamic contrast-enhanced images(n=4). Bone erosions, synovial hypertrophy and bone marrow enhancement in pre- and post-medication studies were compared. On dynamic study, enhancement ratio(E) of pannus was measured(E=SNR at 30sec/SNR at precontrast). Changes of MRI findings and enhancement ratio between pre- and post-medication were compared with disease status as assessed by clinical index. RESULTS: In three patients, improvement of bone marrow edema and synovial hypertrophy was noted, and in addition, there was no evidence of newly developed boneerosion. In two of these patients, complete remission was noted on the basis of the ARA criteria. In another three patients, despite improvement of bone marrow edema and synovial hypertrophy and improved clinical parameters including morning stiffness and ESR, discrete and newly developed bone erosions were noted. In one patient with apoor response to antirheumatoid medication, aggravation of bone marrow edema and synovial hypertrophy was seen, but no definite change in bone erosions was noted. In the remaining one patient, no remarkable changes were seenin bone marrow edema, synovial hypertrophy or bone erosion. Clinically this patient showed no morning stiffness or elevated ESR. The enhancement ratio of pannus decreased in all 4 cases, especially where there were complete remission. CONCLUSION: Synovial extent, bone marrow enhancement, bone erosions and enhancement ratio of pannusmay be good parameters for monitoring disease activity in the follow-up of the patients with rheumatoid arthritis.

Clinical Significance of Dynamic Magnetic Resonance imaging in the Evaluation of Wrist Joint in Rheumatoid Arthritis

PURPOSE: To assess the role of contrast-enhanced dynamic Magnetic Resonance Imaging in evaluating disease activity of rheumatoid arthritis. MATERIALS AND METHODS: Forty-seven wrist joints with rheumatoid arthritis were examined prospectively. coronal images of the wrist were obtained using fat-suppression Fast multi-planar spoiled gradient recalled(FMPSPGR) acquisition in the steady state ; TR/TE=102/6.4m sec, flip angle=60.4 slices persequence, FOV=8cm, matrix=256X192 at 1.5 Tesla. Scans were carried out once before and five to eight times after an intravenous Gd-DPTA injection, at 30-second-intervals. The enhancement of synovium were measured, the enhancement ratio was calculated(postcontrast SNR/precontrast SNR) and time-enhancement ratio curves were plotted patients were divided into three groups according to the ratio of inital to peak enhancement: less than 30%; 30-80%; morethan 80%. Differences among the three groups were statistically tested using clinical indices and laboratory data as variables. RESULTS: Comparing one group with another, there were no significant differences in clinical indices and laberatory data except for the parameter of grip strength. CONCLUSION: Enhancement pattern measured in a single wrist joint was not comparable to a clinical index in predicting disease activity in rheumatoid arthritis.