Imaging of infectious arthritis

Septic arthritis is a disabling and potentially life-threatening condition that requires prompt diagnosis and treatment. Radiologists play a vital role in both the diagnosis and management of these patients and, therefore, need to be aware of the imaging findings in both acute and chronic septic arthritis. Because early diagnosis and intervention are major determinants in final outcome, it is vitally important that these patients be evaluated and diagnosed expeditiously.     

类风湿性关节炎的影像学表现

目的探讨类风湿性关节炎的影像特征,提高其诊断准确率。方法对经临床及实验室确诊的56例类风湿性关节炎患者的影像学表现进行回顾性分析。结果在56例的X线片上,手足小关节附近软组织呈梭形肿胀见于7例。表现为骨质疏松、关节间隙狭窄、骨性关节面骨皮质边缘不规整43例。骨质疏松、破坏、缺损、关节半脱位、骨性强直6例。结论类风湿性关节炎的影像学表现具有一定特征,临床、影像、实验室相结合可提高本病的诊断准确率。     

Imaging of bone erosion in rheumatoid arthritis

Rheumatoid arthritis (RA) is the most common type of inflammatory arthritis, with a prevalence of 1% in the United States. Recently introduced disease-modifying antirheumatic drugs have been extremely successful in preventing irreversible joint damage, particularly if initiated early. Accordingly, accurate and early diagnosis of RA has become imperative. This shift places increased demands on imaging to identify even the slightest traces of erosive joint damage and predict future structural and functional deterioration. Unfortunately, conventional radiography has been shown to be insensitive for bone erosions, particularly in early stages of the disease. Computed tomography (CT) is rarely used, but its tomographic perspective offers advantages over projectional radiography. Ultrasound (US) detects more erosions than radiography does and also can evaluate synovitis. Scintigraphy also can detect inflammation and bone turnover at sites of active erosion. It lacks spatial resolution but offers greater anatomical coverage, making whole-body assessments possible. Of all imaging modalities, however, magnetic resonance imaging (MRI) shows the greatest sensitivity for detecting and monitoring bone erosions and also can detect and follow pre-erosive features of RA, such as synovitis, bone marrow edema or osteitis, and tendinous and ligamentous abnormalities. In this article, we review the appearance of bone erosions on conventional radiography and alternative imaging modalities including MRI, CT, US, and scintigraphy. We also review alternative acquisition techniques for MRI in RA and discuss the utility of fat suppression and contrast enhancement.     

痛风性关节炎的影像学诊断及进展

痛风性关节炎特征性的影像学表现是目前诊断痛风的重要依据,并且正逐渐成为无创性诊断痛风的热门研究方向.早期用于诊断痛风性关节炎的影像学检查方法为普通X线平片,随着双能量CT等高端影像设备的出现及应用,其对痛风更准确、更敏感的定性及定量诊断日益为临床所关注.就不同影像学检查技术对痛风性关节炎的诊断价值及各自技术优势和限度予以综述.     

Imaging features of psoriatic arthritis and Reiter's syndrome

Psoriatic arthritis and Reiter's Syndrome are seronegative spondyloarthropathies with characteristic, yet nonspecific, radiographic findings. Radiographic diagnosis is based upon recognition of the classic morphologic changes and knowledge of the articular distribution. Other imaging modalities such as computed tomography (CT), radionuclide imaging, magnetic resonance (MR) imaging, and ultrasonography are also utilized and play specific roles in the evaluation of Psoriatic arthritis and Reiter's Syndrome.     

Imaging of inflammatory arthritis with technetium-99m-labeled IgG

The accumulation of nonspecific polyclonal human immunoglobulin G (IgG) radiolabeled with 99mTc was compared to that of [99mTc]albumin and [99mTc]nanocolloid in rats with collagen induced arthritis. Serial scintigrams were acquired directly, 4 and 24 hr after injection. A clearly discernable image of the site of synovitis was seen with [99mTc]IgG as early as 4 hr postinjection. The relative intensity of the inflammatory lesion was maximal at 24 hr. Discrimination between arthritic and nonarthritic joints as well as correlations between the relative intensity of the arthritic joint and clinical indices of joint inflammation were superior with IgG compared to albumin or nanocolloid. These studies show that localization and severity of inflammatory joint disease can be detected with radiolabeled nonspecific IgG.     

Enteropathic arthritis in the sacroiliac joint. Imaging and differential diagnosis

OBJECTIVES: A new high resolution computed tomography (HRCT) scoring system of sacroiliac joint (SIJ) involvement in enteropathic arthritis is introduced. PATIENTS AND METHODS: SIJ's of 100 patients were studied. A total of 25 patients presented with pain syndrome, 25 with suspicious seronegative spondylarthritis, 25 with inflammatory bowel diseases and 25 without joint or bowel diseases, as a control group. HRCT was carried out in all 100 patients. For comparison, a plain film radiography (PFR), conventional CT (slices of 10 mm) and bone scan were used. RESULTS: Quantitative differences: In the pain syndrome group, there were no erosions identified neither intraarticular calcifications. Disc degeneration was seen in 12/25 cases. In 4/25 patients, vacuum phenomena appeared in the SIJ. In 3/25 patients, ventral capsular calcification occurred in the ventral sacroiliac ligament (anterior capsule complex). In the seronegative spondylarthritis group, 16/25 patients had positive findings, while PFR documented erosions only in 3/25 cases. In the bowel diseases group, erosions were detected in 17/25 cases with HRCT, while the plain film was positive only in three cases and in seven cases the findings were questionable. Intraarticular calcification with erosion was documented in three cases and in seven cases without erosion. The bone scan was positive in 7/25 of this cases, but in 5/7 there was mismatching with HRCT. Important new finding was the HRCT detected erosion which was not detected on BS but was obvious on Anti-Granulocyte-Antibody scintigraphy. In the control group, only degenerative changes were seen in 4/25 cases and no erosions. CONCLUSION: HRCT is: (1) the reliable imaging of definitive (often 'cold stage') sacroileitis; (2) gives optimal detection of erosion; and (3) appears to be the only method in the documentation of calcifications in the posterior ligamental portion of the SIJ.     

Imaging cell death with radiolabeled annexin V in an experimental model of rheumatoid arthritis.

Rheumatoid arthritis is associated with chronic synovial inflammation due to the abnormal accumulation of macrophages and autoreactive T lymphocytes in joints. The autoreactive cells cause an inflammatory proapoptotic response to self-antigens resulting in eventual bone, cartilage, and soft-tissue loss and destruction. The goal of our study was to determine the timing and intensity of apoptosis in joints using 99mTc-labeled annexin V, an in vivo marker of apoptosis, in a murine model of immune arthritis. METHODS: We used 99mTc-annexin V and autoradiography to study the extent and severity of apoptosis in the front and rear paws of DBA/1 mice with type II collagen-induced rheumatoid arthritis. RESULTS: Compared with control values (n = 10), there was a significant (P < 0.002) nearly 3-fold increase in uptake of 99mTc-annexin V in the front foot pads, rear toes, rear foot pads, and heels at the time of maximal extremity swelling as determined by serial caliper measurements at 4 wk after inoculation with type II bovine collagen (n = 9). The front toes had a 5- to 6-fold increase in uptake compared with control values (P < 0.001). Histologic analysis revealed only scattered rare lymphocytes in the periarticular soft tissues, without joint destruction. Dual autoradiography with 125I-bovine serum albumin as a control showed that 99mTc-annexin V localization was specific. Treatment with methylprednisolone for 1 wk (n = 8) at 4 wk after immunization with type II collagen decreased 99mTc-annexin V uptake by 3- to 6-fold compared with control values (P < 0.002). CONCLUSION: 99mTc-annexin V can detect collagen-induced immune arthritis and its response to steroid therapy before joint destruction.     

Imaging of pulmonary disease in rheumatoid arthritis using J001X scintigraphy: Preliminary results

The purpose of this study was to determine the ability of technetium-99m J001X scintigraphy to image active pulmonary involvement in patients suffering from rheumatoid arthritis (RA). J001X is a fully characterized acylated poly(1,3)galactoside, isolated fromKlebsiella membranes, which is able to bind recruited macrophages after aerosol administration. J001X scintigraphy was compared with high-resolution computed tomography (HRCT), pulmonary function tests (PFTs) and bronchoalveolar lavage (BAL) in 15 patients suffering from RA. Patients were considered to have pulmonary involvement when they had an interstitial syndrome on HRCT and a decrease of 20% in TCO/VE (transfer coefficient) on PFTs and/or an abnormal BAL (lymphocytosis higher than 20% and/or percentage of neutrophils higher than 10%). Pulmonary involvement was present in eight patients, and absent in seven. Of the eight patients with pulmonary involvement, all had abnormal BAL, two had an interstitial syndrome on HRCT, two had decreased TCO/VE and three had positive J001X scintigraphy. Of the seven patients without pulmonary involvement, six had normal BAL (not available in one), two had an interstitial syndrome on HRCT, one had decreased TCO/VE and two had positive J001X scintigraphy. According to our gold standard of pulmonary involvement, the sensitivity of J001X scintigraphy for the detection of pulmonary involvement in RA was 37.5%, the specificity was 71.4% and the positive predictive value was 60%. The ability of J001X scintigraphy to detect active pulmonary involvement during RA appears unclear in this study but it may detect processes unnoticed by the other modalities. These patients will be followed 12 and 24 months later and the changes in J001X scintigraphy, HRCT and PFTs will be compared to demonstrate whether J001X scintigraphy is able to assess an active process in the pulmonary involvement during RA and to specify its predictive value.     

Imaging of lesions in a murine rheumatoid arthritis model with a humanized anti-interleukin-6 receptor antibody

Rheumatoid arthritis (RA) has been attributed to the abnormal production of cytokine interleukin-6 (IL-6), which has a variety of physiological activities. In vivo IL-6-receptor imaging provides useful suggestions regarding the mechanism of anti-IL-6-receptor antibody action and indicates a basic therapeutic strategy for treating RA. Therefore, this study was designed to establish a method for radiolabeling anti-IL-6-receptor antibodies and to investigate the feasibility of using radiolabeled anti-IL-6-receptor antibodies in the scintigraphic imaging of lesions in an animal RA model. Anti-IL-6-receptor antibodies were conjugated with a bifunctional chelating agent, hydrazinonicotinamide (HYNIC), and radiolabeled with technetium-99m (99mTc) using the ligand exchange reaction of 99mTc-tricine complex. The binding affinity was estimated using the U266 cell line. Whole body scintigraphy, biodistribution and autoradiography were undertaken in mice containing synovial cells that had been transplanted from an RA patient. Our findings showed that the antibodies accumulated in the implanted tissue. When radiolabeled anti-IL-6-receptor antibodies are used in scintigraphic imaging, the distribution of the IL-6-receptors is associated with the inflammatory cell infiltration that is seen in the early stage of RA. Accordingly, imaging with humanized anti-IL-6-receptor antibodies appears to be useful for detecting early pathophysiological conditions and assessing the efficacy of antibody treatment as well as the prognosis of patients with RA.     

Imaging of carrageenan-induced local inflammation and adjuvant-induced systemic arthritis with [11C]PBR28 PET

Introduction[¹¹C] PBR28 binding to translocator protein (TSPO) was evaluated for imaging of acute and chronic inflammation using two established rat models.MethodsAcute inflammation was induced by local carrageenan injection into the paw of Fisher 344 rats (model A). T-cell mediated adjuvant arthritis was induced by heat-inactivated Mycobacterium butyricum injection in Lewis rats (model B). Micro-PET scan was performed after injection of approximately 35 MBq [¹¹C]PBR28. In model A, volumes of interest (VOIs) were defined in the paw of Fisher 344 rats (n=6) with contralateral sham treatment as control. For model B, VOIs were defined in the tail, sacroiliac joints, hips, knees and thigh muscles of M. butyricum treated animals (n=8) and compared with sham-treated controls (n=4). The peak ¹¹C-PBR28 SUV (SUV_peak) and area under the curve (AUC_SUV) of 60-minute time-activity data were calculated. Immunohistochemistry for CD68, a macrophage stain, was performed from paw tissues. In addition, the [¹¹C]PBR28 cell uptake was measured in lipopolysaccharide (LPS)-stimulated and non-stimulated macrophage cultures.ResultsLPS-stimulated macrophages displayed dose-dependent increased [¹¹C]PBR28 uptake, which was blocked by non-labeled PBR28. In both models, radiotracer uptake of treated lesions increased rapidly within minutes and displayed overall accumulative kinetics. The SUV_peak and AUC_SUV of carrageenan-treated paws was significantly increased compared to controls. Also, the [¹¹C]PBR28 uptake ratio of carrageenan-treated vs. sham-treated paw correlated significantly with CD68 staining ratios of the same animals. In adjuvant arthritis, significantly increased [¹¹C]PBR28 SUV_peak and AUC_SUV values were identified at the tail, knees, and sacroiliac joints, while no significant differences were identified in the lumbar spine and hips.ConclusionsBased on our initial data, [¹¹C]PBR28 PET appears to have potential for imaging of various inflammatory processes involving macrophage activation.     

Imaging rheumatoid arthritis specifically with technetium 99m CD4-specific (T-helper lymphocytes) antibodies

CD₄ expressing T-lymphocytes are involved in the pathogenesis of rheumatoid arthritis, so the possibility of using radiolabelled CD₄-specific antibodies to localise diseased joints was studied. Prospectively six patients with rheumatoid arthritis were investigated. Five of them received 200–300 g of a 555 MBq technetium 99m CD₄-specific antibody (MAX.16H5) and were examined with three phase bone scans. Max.16H5 (IgG1) was labelled according to the mercaptoethanol (Schwarz) method. Lymphocytes of one patient were isolated on a Ficoll-Hypaque gradient and labelled with the antibody in vitro. Scans were performed 1.5 h, 4 and 24 h post injection in anterior and posterior views. In all patients, diseased joints could be clearly imaged at as early as 1.5 h. The localisation of the diseased joints correlated (P<0.01) with the clinical signs, with the early methylene diphosphonate (MDP) scan (P > 0.01) and only weakly with the late bone scan (P > 0.05). According to these data we conclude that^99mTc-labelled CD₄-specific antibodies specifically image actively diseased joints in rheumatoid arthritis.Supported by the Johannes und Frieda Marohn-Stiftung at the University of Erlangen-Nürnberg     

Imaging rheumatoid arthritis specifically with technetium 99m CD4-specific (T-helper lymphocytes) antibodies

CD4 expressing T-lymphocytes are involved in the pathogenesis of rheumatoid arthritis, so the possibility of using radiolabelled CD4-specific antibodies to localise diseased joints was studied. Prospectively six patients with rheumatoid arthritis were investigated. Five of them received 200-300 micrograms of a 555 MBq technetium 99m CD4-specific antibody (MAX.16H5) and were examined with three phase bone scans. Max.16H5 (IgG1) was labelled according to the mercaptoethanol (Schwarz) method. Lymphocytes of one patient were isolated on a Ficoll-Hypaque gradient and labelled with the antibody in vitro. Scans were performed 1.5 h, 4 and 24 h post injection in anterior and posterior views. In all patients, diseased joints could be clearly imaged at as early as 1.5 h. The localisation of the diseased joints correlated (P less than 0.01) with the clinical signs, with the early methylene diphosphonate (MDP) scan (P less than 0.01) and only weakly with the late bone scan (P greater than 0.05). According to these data we conclude that 99mTc-labelled CD4-specific antibodies specifically image actively diseased joints in rheumatoid arthritis.     

Imaging rheumatoid arthritis joints with technetium-99m labelled specific anti-CD4− and non-specific monoclonal antibodies

A direct comparison of the joint-imaging properties of inflammation-specific- and non-specific monoclonal antibodies (Mabs) was possible in a patient suffering from long-standing, severe rheumatoid arthritis (RA). This patient received an anti-CD4^– and an anti-carcinoembryonic antigen (anti-CEA) Mab, both labelled with technetium-99m, 9 days apart from each other. The anti-CD4 Mab was superior to the isotype-matched anti-CEA Mab in imaging inflamed joints. In the knee joint, the target-to-background ratio of the synovial membrane (SM) activity in comparison to that of adjacent large vessels was 1.22 (SM/muscle 1.55) for the anti-CD4 Mab and 0.53 (SM/muscle 0.92) for the anti-CEA Mab, in both cases 4 h after injection of the immunoglobulin. Since the CD4 antigen is present on the surface of T-helper lymphocytes and macrophages infiltrating the inflamed synovial membrane, imaging with the anti-CD4 Mab may allow more specific detection of inflammatory infiltrates in RA. Correspondence to: R.W. Kinne