Hybrid FDG-PET/MR imaging of chronic osteomyelitis: a prospective case series

Abstract

Background: Magnetic resonance imaging (MRI) and 2-[18F]-fluoro-2-deoxy-Dglucose (FDG) positron emission tomography paired with computed tomography (PET/CT) are two commonly used imaging modalities in the complicated diagnostic workup of osteomyelitis. Diagnosis using these modalities relies on, respectively, anatomical (MRI) and metabolic (PET) signs. With hybrid PET/MRI being recently available, our goal is to qualitatively compare hybrid FDG PET/MRI to FDG PET/CT in the diagnosis and operative planning of chronic osteomyelitis. Methods: Five patients with suspected chronic osteomyelitis in an extremity underwent an 18 F-FDG single-injection/dual-imaging protocol with hybrid PET/CT and hybrid PET/MR. Images and clinical features were evaluated using a standardized assessment method. Standardized uptake value (SUV) measurements were performed on all images. Concordant and discordant findings between PET/MRI and PET/CT were analysed. Results: The consensus diagnoses based on PET/MRI and PET/CT images were identical for all five patients. One discrepancy between PET/MRI and PET/CT was found in the assessment of the features in one patient. PET signal intensities and target-tobackground ratios were on average highest for PET/MRI. On PET/MRI, the location of infection based on FDG uptake could clearly be correlated with certain soft tissue structures (oedema, fluid collection, or muscle), which is paramount for surgical planning. Conclusions: In the presented cases, FDG PET/MRI led to the same diagnosis and provided at least the same diagnostic information as PET/CT. PET/MRI was able to provide additional soft-tissue information for the physician planning treatment. Because of this, we suggest that PET/MRI could be used for osteomyelitis diagnosis and treatment planning.

Clinical Translation of Neutrophil Imaging and Its Role in Cancer

“…Combining these methods using hybrid imaging may offer significant advantages by exploiting the distinct benefits of each modality. For instance, [ 18 F]FDG has been used as part of a hybrid PET/MRI approach to examine musculoskeletal inflammation, providing multiparametric information on the tissue structure, function, and immunometabolic activity in a single imaging session [102,103].…”

Potential Applications of PET/CT/MR Imaging in Inflammatory Diseases

“…FDG-PET/CT performs better than MRI in the early phase (10), whereas MRI is better at assessing soft tissue abscesses associated with osteomyelitis and also for surgery planning, thus, hybrid FDG-PET/MRI is potentially even more valuable. Hulsen et al (11) proposed FDG-PET/MRI to hold at least the equal diagnostic value as FDG-PET/CT in chronic osteomyelitis. When infection sites are assessed metabolically by FDG findings correlate with MRI findings of marrow edema and soft tissue characteristics which helps in accurate debridement planning.…”

“…When infection sites are assessed metabolically by FDG findings correlate with MRI findings of marrow edema and soft tissue characteristics which helps in accurate debridement planning. Other PET radiotracers such as 11 C-methionine, 11 C-PK11195, and 68 Ga-citrate have also been tested in osteomyelitis, but with lower efficacy than FDG (12).…”

“…Aside from FDG and NaF, several novel PET tracers have also been investigated for imaging RA, e.g. 11 C-choline, 11 C-PK11195, 11 CD-deprenyl, and 68 Ga-PRGD2. In RA patients, 11 C-choline and FDG both correlate with the volume of synovial tissue on MRI (26), although 11 C-choline detects the affected joints in a shorter period of time (10 min) (27).…”

“…PET imaging of patients suffering from whiplash-associated pain disorders has revealed significantly elevated 11 CD-deprenyl uptake in the neck, serving as a marker of local persistent peripheral tissue inflammation (59). In a study by Imamoto (60), 11 C-PK11195 PET imaged activated glia in the spinal cord of neuropathic pain. While these tracers hold a great promise for elucidating the underlying pathologies and may support the development of novel therapies, there remains a need for more studies in this field.…”