99Tcm-HIG accumulates in the synovial tissue of rats with adjuvant arthritis by binding to extracellular matrix proteins

Molecular Imaging of Inflammatory Arthritis and Related Disorders

Rheumatic disorders comprise a number of diseases that range from benign, mildly symptomatic degenerative disease to severe systemic disorders such as giant-cell vasculitis with dramatic consequences such as acute blindness. The former is relatively common, whereas the latter is rare. In between, commonly encountered disorders such as rheumatoid arthritis and the various spondyloarthritides, with or without peripheral enthesitis, are daily challenges for the caring physician. Clinical evaluation is of utmost importance and is constantly described under the form of specialist guidelines in all parts of the world. Objective assessment of inflammatory arthritis and related disorders is of interest both for the care of the individual patient and for the assessment of the effects of the many novel experimental therapies proposed in this field, most of them being very expensive. High-resolution ultrasound, CT and spectral CT, MRI using various sequences, and molecular imaging using either gamma camera imaging (including SPECT-CT) or PET-CT are all proposed for a better assessment of these diseases. This review focuses on the several nuclear medicine techniques that are or may become useful to helping provide better patient care in this field and is mainly oriented to inflammatory rheumatic disorders, excluding mechanical degenerative diseases.

Detection of orchitis and sacroiliitis due to brucellosis by 99mTc polyclonal human immunoglobulin scintigraphy

Here, we report 1 case of Brucella orchitis detected by 99mTc human immunoglobulin scintigraphy and confirmed by testicular ultrasound. A 29-year-old farmer was admitted to our hospital with fever, fatigue, arthralgia, and painful scrotal swelling that had appeared 12 days before admission. Clinically, right sacroiliitis was recorded through the Fabere test Unilateral sacroiliitis and orchitis were detected by 99mTc human immunoglobulin scintigraphy. Hypoechoic left testicular lesions and swelling of the concurrent epididymis were seen on a testicular ultrasound examination. Wright agglutination test and blood specimen culture for Brucella species were positive.

The Agreement Between Blood Pool - Delayed Bone Scintigraphy and Tc-99m Human Immunoglobulin G (HIG) Scintigraphy in the Determination of the Presence and Severity of Inflammatory Arthritis

OBJECTIVE

In this study, it was aimed to investigate the agreement between early phase of bone scintigraphy - human immunoglobulin scintigraphy (EPBS-HIG) and late phase bone scintigraphy - HIG (LPBS-HIG) in the determination of the presence and also the severity of inflammatory arthritis.

MATERIAL AND METHODS

Twenty-eight patients (23 female, 5 male; between 19 to 80 years of age) with inflammatory arthritis were included in the study. Tc-99m HIG and blood pool/late phase bone scintigraphies were performed in all patients. In scintigraphic examinations, the joints were scored with the degree of accumulation of the radiopharmaceutical by the semiquantitative analysis (0=Background activity, 1=Faint uptake, 2=Moderate uptake, 3=Marked uptake) which is called as visually active joint score as severity index of the disease. To estimate the agreement between EPBS - HIG and LPBS - HIG in the determination of the presence and severity of inflammatory arthritis, 2x2 kappa coefficients were calculated.

RESULTS

Our results showed good agreement between EPBS - HIG for the presence of inflammation (kappa: 0.72) but not for the severity of the disease (kappa: 0.29), poor agreement between LPBS - HIG for both the presence (kappa: 0.51) and severity (kappa: 0.01) of inflammatory arthritis.

CONCLUSION

The blood pool scintigraphy could be used in the investigation of the presence of inflammatory arthritis because the good agreement with HIG and the lower cost but not for the severity of the disease Conflict of interest:None declared.

Determination of inflammation of reflex sympathetic dystrophy at early stages with Tc-99m HIG scintigraphy: preliminary results

The pathogenesis of reflex sympathetic dystrophy (RSD) is not completely understood. However, an excessive regional inflammation, sensitization of primary somatosensory afferents, and sensitization of spinal neurons are considered to have a role in the pathogenesis of RSD. The underlying pathophysiology relating the clinical picture may help to determine the pharmacotherapeutic approach for an individual patient. Scintigraphy using radiolabelled human polyclonal non-specific immunoglobulin (HIG) has been recognized as a useful tool for the localization of inflammatory disorders. Thirty-six consecutive RSD patients associated with hemiplegia were included in this study. All the patients in this study had three phases bone scan and Tc-99m HIG scintigraphy. On admission, of 36 patients with positive bone scan, 30 had positive Tc-99m HIG scan. All the patients were symptomatic at the time of bone scanning. On the contrary, 24 out of 36 patients subsequently became asymptomatic at an 8-month re-evaluation period. Tc-99m HIG scintigraphy is a non-invasive complementary method for the determination of ongoing inflammatory reactions which also aids the clinicians to predict the response to anti-inflammatory therapy at the very early phase of RSD associated with hemiplegia. This preliminary study may be a source of inspiration for further studies with larger series and longer follow-up .

Tc-99m polyclonal human immunoglobulin scintigraphy in brucellosis

The aim of this study was to evaluate the accuracy of Tc-99m polyclonal human immunoglobulin (HIG) scintigraphy for the diagnosis of brucellosis, and to compare its effectiveness in the diagnosis of osteoarticular involvement in comparison with bone scanning. Of 30 patients with brucellosis, Tc-99m HIG detected osteoarticular involvement in 18 (60%) patients, in whom the sacroiliac joints were affected most commonly (n = 13; 72.2%), with statistically predominant bilateral involvement (p < 0.05). By bone scanning, the rate of osteoarticular involvement was 70% (21 of 30 patients), and the joints affected most commonly were sacroiliac (15 of 21 patients; 71.4%). Although bilateral involvement was observed mostly by bone scanning, there was no significant difference between the rate of bilateral and unilateral involvement. The anatomical distribution of osteoarticular complications, as detected by Tc-99m HIG and bone scintigraphy, did not differ significantly. With Tc-99m HIG, orchitis was detected in two patients and paravertebral abscess in one patient. Since bone scanning did not detect these soft tissue complications, Tc-99m HIG scintigraphy might be useful for the detection of both osteoarticular and soft tissue complications resulting from brucellosis.

99mTc-dextran scintigraphy to detect disease activity in patients with rheumatoid arthritis

AIM

To test the applicability of Tc-dextran joint scintigraphy in the assessment of disease activity in patients with rheumatoid arthritis (RA), and to compare it with the clinical disease activity scores and laboratory parameters.

METHODS

Twenty-seven patients with RA were investigated using Tc-dextran joint scintigraphy. The images were evaluated semi-quantitatively and the regional uptakes of the radiopharmaceutical were calculated for the knee, wrist and ankle joints. The clinical and laboratory parameters were collected and fully analysed. An articular Ritchie index (a tender joint score), the number of swollen joints (Sw), the number of tender joints, the morning stiffness (h), the total Ritchie articular index (R), the visual analogue scale (VAS) and the Disease Activity Score (DAS) were determined for all patients.

RESULTS

Compared with controls, patients with RA had significantly higher regional Tc-dextran uptake in the knee, wrist and ankle joints (P=0.001). The regional Tc-dextran uptake showed no correlation with the patient's age, gender, duration of disease, number of swollen joints (Sw), number of tender joints, morning stiffness (h), VAS, total Ritchie articular index and DAS, or any laboratory parameters. There was a significant correlation between the regional Tc-dextran uptake for individual joints and the articular Ritchie index of the right and left wrist (r=0.42, P=0.03; r=0.45, P=0.02), right and left knee (r=0.66, P<0.0001; r=0.80, P<0.0001) and right and left ankle (r=0.47, P=0.014; r=0.76, P<0.0001), respectively.

CONCLUSIONS

This study demonstrates that Tc-dextran scintigraphy is a sensitive method to detect active joint inflammation and could be useful in the management of patients with RA.

Biological imaging for the diagnosis of inflammatory conditions

Radiopharmaceuticals used for in vivo imaging of inflammatory conditions can be conveniently classified into six categories according to the different phases in which the inflammatory process develops. The trigger of an inflammatory process is a pathogenic insult (phase I) that causes activation of endothelial cells (phase II); there is then an increase of vascular permeability followed by tissue oedema (phase III). Phase IV is characterised by infiltration of polymorphonuclear cells, and a self-limiting regulatory process called apoptosis is observed (phase V). If the inflammatory process persists, late chronic inflammation takes place (phase VI). In some pathological conditions, such as organ-specific autoimmune diseases, chronic inflammation is present early in the disease. The aim of nuclear medicine in the field of inflammation/infection is to develop noninvasive tools for the in vivo detection of specific cells and tissues. This would allow early diagnosis of initial pathophysiological changes that are undetectable by clinical examination or by other diagnostic tools, and could also be used to evaluate the state of activity of the disease during therapy. These potential applications are of great interest in clinical practice. In this review, we describe the various approaches that have been developed in the last 25 years of experience. Recent advances in the diagnosis of inflammatory processes have led to the development of specific radiopharmaceuticals that are intended to allow specific stage-related diagnosis.

Value of combined 67Ga and 99Tc(m)-human immunoglobulin G whole-body scanning in malignant lymphoma

Human immunoglobulin G labelled with 99Tc(m) (99Tc(m)-HIG) is an agent introduced for the localization of inflammatory lesions. There is also a limited number of reports concerning the uptake of this agent by malignant lesions. The aim of this study was to evaluate the uptake of 99Tc(m)-HIG by lymphoma. Twenty-three patients (five female, 18 male) with known Hodgkin's or non-Hodgkin's lymphoma for a period of 2-6 years (mean 4.2 years) and which, by using computed tomography (CT), showed recurrence, were included in the study. The patients were aged between 32 and 68 years (mean 38 +/- 5 years). No evidence of inflammation or infection was seen in any of these patients. CT, 99Tc(m)-HIG and a 67Ga scan were performed in the same week. CT showed abdominal involvement in 17 patients, pelvic involvement in 11, and thorax involvement in 11. 99Tc(m)-HIG showed higher sensitivity (94.1%) in the abdomen, a similar sensitivity (63.6%) in thorax, but lower (18.1%) in pelvic area than for 67Ga. 99Tc(m)-HIG was found to be more useful for the evaluation of abdominal involvement compared to 67Ga due to gastrointestinal excretion of the latter. The resolution of 67Ga was better than 99Tc(m)-HIG in thorax and pelvis. Using 99Tc(m)-HIG and 67Ga together in lymphoma may increase sensitivity.

Tc-99m polyclonal human immunoglobulin G imaging in Graves' ophthalmopathy

PURPOSE

The authors evaluated the utility of Tc-99m-labeled human immunglobulin G (HIG) in determining the severity of orbital inflammation and the relation of orbital Tc-99m HIG uptake and clinical parameters in patients with Graves' ophthalmopathy.

MATERIALS AND METHODS

Images were obtained in 23 patients (13 women, 10 men; mean age, 51+/-10 years) with Graves' ophthalmopathy. Planar orbital images were obtained and SPECT was performed using a triple-detector gamma camera 4 hours after 370 MBq (10 mCi) Tc-99m HIG injection. Tc-99m HIG uptake was classified using transaxial and coronal slices as 1, mild; 2, moderate; and 3, severe. The clinical severity of orbital disease was categorized, according to the criteria described by Feldon and Unsold, as class I, mild involvement; class II, moderate; and class III, severe. Disease was considered to be clinically inactive if symptoms and signs were stable or improved in the last two examinations performed at least 6 months apart.

RESULTS

Sixteen patients were clinically inactive, and seven patients were active. The mean Tc-99m HIG classes were 1.5+/-0.5 and 2.6+/-0.5, respectively (P = 0.02). There was not a good correlation between the clinical classification and Tc-99m HIG classification, whereas the presence of active disease showed a good correlation with Tc-99m HIG classification (r = 0.703; P = 0.0002).

CONCLUSIONS

Tc-99m HIG imaging showed possible ongoing subclinical inflammation in the orbits of the patients with Graves' ophthalmopathy regardless of the clinical classification. Tc-99m HIG SPECT seems a promising procedure for evaluating the presence of active orbital inflammation.

Radiolabelled interleukin-1 receptor antagonist for detection of synovitis in patients with rheumatoid arthritis

OBJECTIVES

To investigate the distribution of radiolabelled interleukin-1 receptor antagonist (IL-1ra) in patients with rheumatoid arthritis (RA) and to assess whether this cytokine is suitable for scintigraphic visualization of synovitis.

METHODS

In patients with active RA, scintigraphy was performed after a single i. v. dose of [(123)I]IL-1ra. Clearance and organ distribution of radiolabelled IL-1ra were studied. To assess whether radiolabelled IL-1ra targets the synovial IL-1 receptors, the scintigraphic images obtained with IL-1ra were compared with those obtained by the use of a non-specific control agent. In addition, autoradiography was performed in mice with antigen-induced arthritis that were injected with either radiolabelled IL-1ra or a size-matched, non-receptor-binding protein.

RESULTS

Radiolabelled IL-1ra allowed clear visualization of inflamed joints. Specificity in the detection of synovitis was high, whereas a number of painful and swollen joints were not visualized by scintigraphy. The procedure was well tolerated and [(123)I]IL-1ra was rapidly cleared from the circulation (t(1/2)alpha 11 min, t(1/2)beta 612 min) and excreted mainly in the urine. The definition of synovial contours by IL-1ra scintigraphy was not better than that observed with a non-specific agent. Although radiolabelled IL-1ra retained its affinity for IL-1 receptors, no binding to synovium was observed by autoradiography.

CONCLUSIONS

Radiolabelled IL-1ra allows the visualization of synovitis in patients with RA. However, neither the imaging nor the autoradiographic studies indicate that joint accumulation of radiolabelled IL-1ra is due to specific IL-1 receptor targeting. IL-1ra has proved its therapeutic value in RA, but with the dose schedule in this study it does not behave as a specific radiopharmaceutical that is suitable for scintigraphic detection of inflammation.

Comparison of Tc-99m MDP, Tc-99m HSA and Tc-99m HIG uptake in rheumatoid arthritis and its variants

Tc-99m polyclonal immunoglobulin-G has been shown to be a successful agent in the depiction of active inflammation in rheumatoid arthritis (RA). The objective of this study was to compare the uptake behaviors of Tc-99m HIG and Tc-99m MDP in RA and variants of rheumatoid arthritis (VRA). Seventeen patients with RA and 8 patients with VRA presenting with active inflammation were included in this study. Ten subjects with well-diagnosed degenerative joint disease constituted the control group. All joints in patients were also imaged with Tc-99m HSA to evaluate the vascularization status of the joints. Tc-99m HIG and HSA scans were obtained at 2, 4 and 24 hours after the injection of 555 MBq Tc-99m HIG and 296 MBq Tc-99m HSA. Conventional bone scans were performed 4 hours after the injection of 740 MBq Tc-99m MDP. Target-to-background (T/B) ratios were obtained exclusively over the joint regions. Tc-99m HIG T/B ratios of the active joints in RA were significantly higher than those of the non-active joints and the control group (p < 0.05). Tc-99m HIG T/B ratios in active joints showed a progressive increase between 2 and 24 hour images (p < 0.05). In contrast, Tc-99m HSA T/B ratios decreased in all active joints significantly (p < 0.05) except the ankle joint region (p > 0.05). The T/B ratios in Tc-99m MDP bone scans were higher in all active joints than in non-active RA joints and joints of controls but significantly differences were only detected in wrist and elbow joints. All clinically active joints in VRA patients accumulated Tc-99m HIG and HSA, and showed increased Tc-99m MDP uptake. These joints had a very similar Tc-99m HIG retention pattern to the RA joints. The detection rate of active joint inflammation with Tc-99m HIG was much higher than that with Tc-99m MDP. The increasing Tc-99m HIG uptake ratio between 2 and 24 hours in contrast to Tc-99m HSA indicates the presence of other binding mechanisms besides increased vascularity in RA.

Orthopedic pathology of the lower extremities: scintigraphic evaluation in the thigh, knee, and leg

Radionuclide imaging (RI) of the osseous and nonosseous structures of the thigh, knee, and leg provide important diagnostic and prognostic information upon which the orthopedic surgeon can base treatment planning and management decisions. 99mTc-MDP scintigraphy is essential in overuse injuries such as stress fractures and shin splints. RI is important in assessing complications of trauma. It is the only imaging modality able to assess the magnitude of physeal stimulus caused by femoral fractures and to predict a favorable or unfavorable outcome of leg length by semiquantitative analysis; SPECT imaging can detect and locate decreased metabolism associated with posttraumatic closure of the physeal plate to predict growth arrest and deformities. Three-phase bone imaging (TPBI) is essential to differentiate hypervascular from avascular nonunions and follow delayed union. In osteonecrosis of the knee, bone scintigraphy precedes radiography changes even in stage l of the disease. 99mTc-MDP and 99mTc-HIG imaging are powerful tools in determining the outcomes of osteoarthritis and rheumatoid arthritis, respectively. Bone scintigraphy can also detect chronic ligament and acute and chronic meniscal lesions. The combined use of TPBI, gallium-67 citrate imaging, and indium-111 or 99mTc-HMPAO labeled leukocytes is important to diagnose and differentiate acute from chronic osteomyelitis, and to detect infected knee prostheses. Thallium-201 chloride imaging and 99mTc-sestamibi imaging have an important role in the assessment of tumor response to chemotherapy and in the quantification of tumor viability.

Orthopaedic manifestations of systemic disease

Nuclear medicine studies can be initiated to detect or evaluate systemic diseases such as inflammatory arthritis or Paget's disease. This is usually because of the strengths of nuclear medicine studies such as high sensitivity, an ability to easily image the whole body, and typical diagnostic patterns of abnormalities. In other instances, a systemic disease may be incidentally suggested by a scintigram such as osteoporosis or hyperparathyroidism; or a focal abnormality such as a vascular necrosis may be detected that should indicate a systemic condition should be sought. Although most nuclear medicine studies have high sensitivity for disease, specificity is often less and, for a particular scan abnormality, several conditions may have to be considered. Familiarity with the varying patterns of abnormality associated with different disease is therefore vital to correct assessment.

99mTc-labelled immunoglobulin scintigraphy in arthritis: an analysis of synovial fluid activity

The distribution of 99mTc-labelled human polyclonal non-specific immunoglobulin G (HIG) in the synovial fluid was studied in 14 patients with rheumatoid and non-rheumatoid arthritides. Analysis included the determination of the total activity per ml synovial fluid 6 h post-injection (p.i.) of the tracer as well as of the protein- and cell-bound fractions. At 6 h p.i., > 60% of the injected dose remained in plasma as protein-bound radioactivity. Values in the synovial fluid ranged between 0.001 and 0.009% of the injected dose per ml. Importantly, the synovial fluid to plasma ratio was consistently < 1 (range: 0.09-0.43), which is in the range of ratios observed for endogenous proteins in vivo. Similar values were obtained in samples of synovial tissue obtained at surgery in two patients. These data are consistent with the hypothesis that labelled HIG accumulates in the extracellular fluid (both within the synovial tissue and fluid) by non-specific mechanisms (such as increased blood pool and capillary permeability) and does not equilibrate with circulating plasma proteins in accordance with basic knowledge of synovial physiology. In addition, it was found that most of the activity remained bound to the proteins in the fluid and that cell-binding occurred to a very low degree that cannot be considered an important mechanism of uptake of this radiolabelled agent in vivo. These results provide the first evidence in an in vivo human setting that radiolabelled HIG accumulates mainly by non-specific mechanisms in inflamed joints.

A comparison between 111In-anti-E-selectin mAb and 99Tcm-labelled human non-specific immunoglobulin in radionuclide imaging of rheumatoid arthritis

We have developed and validated a method for imaging inflammation using a monoclonal antibody (1.2B6) against E-selectin, an endothelial-cell specific adhesion molecule. This study was undertaken to compare 111In-1.2B6 with 99Tcm-labelled non-specific IgG (99Tcm-HIG) in the detection of synovitis in 11 patients with rheumatoid arthritis (RA). Imaging was performed 4 h and 20-24 h post-injection (pi) of 555 MBq 99Tcm-HIG and 15 MBq 111In-1.2B6. Scintigraphic results were compared with clinical scores of joint involvement. Joint uptake was semiquantitated. The scintigraphic appearances with both tracers correlated well, although 111In-1.2B6 at 24 h showed the highest detection rate. Taking joint tenderness or swelling as evidence of clinical activity, the sensitivity of 111In-1.2B6 at 4 h and 24 h was 69% and 82%, respectively, compared with 69% and 62% for 99Tcm-HIG. 111In-1.2B6 also displayed abnormal activity over a number of joints that appeared silent on clinical examination. Joint-to-soft tissue ratios were higher for 111In-1.2B6 at 24 h (4.0 +/- 1.9; p < 0.0001 vs all) than at 4 h (2.4 +/- 1.4) or than for 99Tcm-HIG at 4 h and 24 h (1.6 +/- 0.5 and 2.3 +/- 0.7, respectively). Net 111In counts over joints increased significantly between 4 h and 24 h (mean change: 54 +/- 40%). This study demonstrates that 111In-1.2B6 scintigraphy is a sensitive method by which to assess RA activity and that targeting is more intense and specific than using 99Tcm-HIG. However, the optimum time for 111In-1.2B6 scintigraphy is 24 h whereas good results are already obtained with 99Tc-HIG at 4 h pi. Current efforts are directed at developing 99Tcm-labelled 1.2B6 for imaging endothelial activation.

Isotope imaging

Patients with a wide variety of rheumatological conditions can be usefully investigated by nuclear medicine techniques and particularly by bone scintigraphy. This aspect of nuclear medicine work is increasing and the trend can be expected to continue. The principal conditions that can be imaged are sports medicine injuries, osteomyelitis, avascular necrosis, reflex sympathetic dystrophy syndrome, enthesopathies and bio-mechanical stress lesions, inflammatory arthropathies, metabolic bone disease and miscellaneous bone conditions such as costo-chondritis. Single photon emission tomography (SPECT) has provided new indications for bone scintigraphy such as the evaluation of spondylolysis and facet syndrome in the spine and of meniscal tears and ligamental lesions.

Technetium-99m labelled human immunoglobulin scintigraphy predicts rheumatoid arthritis in patients with arthralgia

The ability of 99mTc-IgG scintigraphy to predict the development of rheumatoid arthritis (RA) in 47 patients with arthralgia was investigated. 99mTc-IgG scintigraphy and the serum test for rheumatoid factor (RF), measured at the beginning of a year long study, were compared for their ability to predict RA. During the study 8 patients developed RA. The specificity and positive predictive values of RF in predicting RA were 79% and 50% respectively; and for 99mTc-IgG scintigraphy 97% and 88%. The sensitivity and negative predictive values of RF were 100% and of 99mTc-IgG-scintigraphy 88% and 97% respectively. In conclusion, 99mTc-IgG scintigraphy has additional value to RF with respect to the prediction of the development of RA in patients with arthralgia.