Achim H. Kaim

F-18 FDG whole-body PET for the assessment of disease activity in patients with rheumatoid arthritis

Purpose of Report: F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) can be used to image synovitis in patients with rheumatoid arthritis (RA). The aim of this study was to evaluate if a simple scoring system based on visual assessment of FDG joint uptake correlates with the clinical assessment of patients with RA undergoing antiinflammatory treatment. Materials and Methods: Seven patients with active RA underwent whole-body FDG PET and clinical assessment before and after treatment with the antitumor necrosis factor alpha antibody (infliximab). A PET total joint score, ie, the sum of all scores based on FDG uptake intensity between zero and 4 in 28 joints, was correlated with a total joint score based on the clinical disease activity in the same joints using a Spearman rank correlation. Results: The PET based total joint score was similarly high before onset as was the clinical total joint score. The decrease of FDG joint uptake in the follow-up PET scans correlated significantly with the clinical assessment. Additionally, synovial FDG uptake was found in extraarticular sites such as tendon sheaths and bursae. Conclusions: Visual assessment of FDG uptake shows a significant correlation with clinical evaluation of disease activity in patients with RA undergoing antiinflammatory treatment.

Imaging of chronic posttraumatic osteomyelitis

Abstract. Posttraumatic osteomyelitis is frequently characterized by chronicity and recurrent activation of infection. The diagnosis is usually made on the basis of clinical, laboratory, and imaging examinations. The conventional radiograph is the basic imaging study that provides important information about skeletal deformity, bone quality, identification of metallic implants, and consolidation of the former fracture site. Other imaging techniques are required to determine the grade of activity, to define the extent of infection and to delineate small sequestra, intraosseus fistula and abscesses. A variety of more sophisticated modalities, such as modern cross-sectional imaging and radionuclide studies, are available, and the decision to choose the most suitable method can be very difficult. This review gives an overview of definition, epidemiology, and pathophysiology of chronic posttraumatic osteomyelitis and discusses the value of currently used imaging modalities.

Chronic complicated osteomyelitis of the appendicular skeleton: Diagnosis with technetium-99m labelled monoclonal antigranulocyte antibody-immunoscintigraphy

Chronic post-traumatic osteomyelitis (OM) represents a particular challenge for nuclear medicine and radiology since clinical and biochemical parameters are frequently unreliable. The aim of this study was to investigate the value of combined bone scan (BS) and immunoscintigraphy (IS) with technetium-99m labelled monoclonal antigranulocyte antibody (MAB) in patients with suspected chronic OM of the appendicular skeleton. Twenty-four patients (17 females and 7 males) with suspected chronic post-traumatic OM were evaluated with three-phase BS/99mTc-MAB-IS. The final diagnosis was established by means of bone culture and histology in 19 cases and clinical follow-up in five cases. The studies were reviewed by two independent and experienced observers; the interobserver agreement was calculated by kappa statistics. The sensitivity, specificity and accuracy of BS alone were 92%, 18% and 58%, respectively. Combined BS/99mTc-MAB-IS. had a sensitivity, specificity and accuracy of 84%, 72% and 79%, respectively. Of 24 studies, 11 were true-positive, two false-negative, eight true-negative and three false-positive. Two patients presented with unexpected ectopic haematopoietic bone marrow in the appendicular skeleton that caused falsepositive results. A high degree of interobserver agreement was found (κ=0.85). It is concluded that combined BS/99mTc-MAB-IS. represents a very sensitive and reproducible method with an acceptable specificity for the investigation of chronic OM. Problems may occur in the differentiation of low-grade OM from aseptic inflammation. Another problem is ectopic marrow that may occur in the appendicular skeleton due to a chronic inflammatory stimulus. A former intramedullary intervention in the femur with displacement of haematopoietic marrow may also lead to an ectopic location.

Correlation of signal intensity ratio on orbital MRI-TIRM and clinical activity score as a possible predictor of therapy response in Graves’ orbitopathy—a pilot study at 1.5 T

IntroductionThis study seeks to describe the predictive value of the signal intensity ratio (SIR) in magnetic resonance imaging-turbo inversion recovery magnitude (MRI-TIRM) in patients with Graves’ orbitopathy (GO) with regard to predictability of therapy response.MethodsIncluded in this prospective pilot study were 36 consecutive patients with GO and 25 control subjects. Patients were clinically assessed according to the European Group on Graves’ Orbitopathy recommendations with active GO defined by a clinical activity score (CAS) ≥ 3. On magnetic resonance (MR) imaging, muscle inflammation was measured with a region of interest set within the brightest extra-ocular muscle both on coronal turbo inversion recovery magnitude (TIRM) and on fat suppressed gadolinium-enhanced T1-weighted sequences. To calculate the SIR, the measured signal intensity was set in proportion to that of the ipsilateral temporalis muscle.ResultsSignal intensity ratio in coronal T2-weighted TIRM sequences in either group ranged from 1.22 to 4.92 (mean 2.04) in patients with GO and from 1.18 to 2.4 (mean 1.63) in controls without GO. The observed differences were significant on the TIRM sequences (right eye p = 0.023; left eye p = 0.022), whereas, no significant differences could be detected on the T1-weighted sequences (right eye p = 0.396; left eye p = 0.498). A cut off value of SIR > 2.5 for a CAS ≥ 4 to discriminate active from inactive patients was statistically calculated.ConclusionT2 relaxation time is a reliable tool in detecting active GO. The difference in T2-SIR versus T1-SIR is helpful to distinguish inflammatory oedema of the extra ocular muscles from intra-orbital congestion due to reduced venous outflow.