Dorothee R. Fischer

18F-Fluoride PET/CT for detection of sacroiliitis in ankylosing spondylitis

PurposeThe aim of this study was to evaluate the performance of 18F-fluoride-PET/CT (PET/CT) for the diagnosis of sacroiliac joint (SIJ) arthritis in patients with active ankylosing spondylitis (AS).MethodsIncluded in the study were 15 patients with AS according to the modified New York criteria (AS group) and with active disease and 13 patients with mechanical low back pain (MLBP; control group) who were investigated with whole-body 18F-fluoride PET/CT. The ratio of the uptake in the SIJ and that in the sacrum (SIJ/S) was calculated for every joint.ResultsThe mean SIJ/S ratio of 30 quantified joints in the AS group was 1.66 (range 1.10–3.07) with PET/CT, and the mean SIJ/S ratio of 26 quantified joints in the MLBP group was 1.12 (range 0.71–1.52). The area under the receiver operating characteristic curve for SIJ arthritis was 0.84. With plain radiography as a the gold standard and taking an SIJ/S ratio of >1.3 as the threshold, the sensitivity, specificity and accuracy on a per patient basis were 80%, 77% and 79%, respectively. On a per SIJ basis, the greatest sensitivity (94%) was found in grade 3 sacroiliitis (n = 16).ConclusionOur results suggest that quantitative 18F-fluoride PET/CT may play a role in the diagnosis of sacroiliitis in active AS and is an alternative to conventional bone scintigraphy in times of molybdenum shortage.

Therapeutic impact of [18F]fluoride positron-emission tomography/computed tomography on patients with unclear foot pain

PurposeTo evaluate the therapeutic impact of [18F]fluoride positron-emission tomography/computed tomography ([18F]fluoride PET/CT) imaging on patients with unclear foot pain.MethodsTwenty-eight patients were prospectively included in this study. Therapeutic management was defined by two experienced dedicated foot surgeons before and after [18F]fluoride PET/CT imaging. Twenty-six patients underwent cross-sectional imaging [CT, magnetic resonance (MR)] prior to PET/CT. A retrospective analysis of the magnetic resonance imaging (MRI) diagnoses was performed when a therapy change occurred after PET/CT imaging.ResultsIn 13/28 (46%) patients therapeutic management was changed due to PET/CT results. Management changes occurred in patients with the following diagnoses: os trigonum syndrome; sinus tarsi syndrome; os tibiale externum syndrome; osteoarthritis of several joints; non-consolidated fragments; calcaneo-navicular coalition; plantar fasciitis; insertional tendinopathy; suggestion of periostitis; neoarticulations between metatarsal bones. Os trigonum, os tibiale externum, subtalar osteoarthritis and plantar fasciitis were only seen to be active on PET/CT images but not on MR images.Conclusion[18F]fluoride PET/CT has a substantial therapeutic impact on management in patients with unclear foot pain.

High bone turnover assessed by 18F-fluoride PET/CT in the spine and sacroiliac joints of patients with ankylosing spondylitis: comparison with inflammatory lesions detected by whole body MRI.

BackgroundThis study compares the frequency and distribution of increased activity on 18 F-fluoride PET/CT with the presence of bone marrow edema on whole-body MR imaging in the spine and sacroiliac joints (SIJ) of patients with active ankylosing spondylitis (AS).MethodsTen patients (6 men and 4 women), between 30 and 58 years old (median 44) with active AS, were prospectively examined with both whole-body MRI and 18 F-fluoride PET/CT. Patients fulfilled modified NY criteria and had a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) of at least 4. Increased radiotracer uptake in PET/CT and bone marrow edema in whole-body MRI of spine and SIJ was evaluated independently by two blinded observers for each modality. Kappa statistics were used to compare interobserver agreement as well as scores of consensus reading of the two imaging modalities.ResultsAnalysis of interobserver agreement for PET/CT yielded a kappa value of 0.68 for spinal lesions and of 0.88 for SIJ lesions. The corresponding kappa values for the MRI modality were 0.64 and 0.93, respectively. More spinal lesions were detected by MRI in comparison to PET/CT (68 vs. 38), whereas a similar number of SIJ quadrants scored positive in both modalities (19 vs. 17). Analysis of agreement of lesion detection between both imaging modalities yielded a kappa value of only 0.25 for spinal lesions and of 0.64 for SIJ lesions.ConclusionIncreased 18 F-fluoride uptake in PET/CT is only modestly associated with bone marrow edema on MRI in the spine and SIJ of patients with AS, suggesting different aspects of bone involvement in AS.

The value of 18F-FDG-PET/CT imaging for sinonasal malignant melanoma.

The aim this study was to evaluate imaging findings using position emission tomography (PET) in combination with computed tomography (CT) and 18F-fluorodeoxyglucose (18F-FDG) in sinonasal malignant melanoma (SNMM) of the head and neck in a retrospective analysis of a consecutive cohort of patients. 18F-FDG-PET/CT examinations were performed for initial staging and compared with CT or magnetic resonance tomography (MRI), and 18F-FDG-PET alone. Medical records were reviewed retrospectively with regard to the location and the size of the tumor. Furthermore, locoregional and distant metastases with a consecutive change in therapy detected by 18F-FDG-PET/CT were assessed. Ten patients suffering from sinonasal malignant melanoma were staged and followed by 18F-FDG-PET/CT imaging. A total of 34 examinations were obtained. 18F-FDG-PET/CT depicted all primary tumors adequately. Aside from one cerebral metastasis all regional and distant metastases were truly identified by using this method. In summary, if available, 18F-FDG-PET/CT is a valuable imaging modality for staging and re-staging sinonasal malignant melanoma to evaluate expansion of the primary tumor, locoregional disease, and distant metastases.

Musculoskeletal Imaging Using Fluoride PET

The convenience of (18)F-fluoride imaging is undeniable both because of its favorable tracer and because of its technical characteristics, including high image quality and short examination times leading to increased patient comfort. Depending on the activity administered, the radiation dose to patients is about comparable to higher using (18)F-fluoride for bone imaging compared with conventional scintigraphy using 99mTc-methylene diphosphonate. In times of molybdenum shortage, (18)F-fluoride represents a good alternative to 99mTc-based bone tracers. Besides malignant skeletal disease(18)F-fluoride PET/CT has in the last decade been investigated in a variety of non-oncologic musculoskeletal disorders of all parts of the skeleton. Studies included imaging of the skull with a special focus on bisphosphonate-induced osteonecrosis of the jaw in patients treated with bisphosphonates due to benign or malignant bone changes. Further studies evaluated the appendicular skeleton with emphasis on postsurgical changes including patients after knee and hip surgery and patients having received bone grafts of their limbs. Also, therapeutic effect of (18)F-fluoride PET/CT on patients with unclear foot pain was investigated. Finally imaging of the axial skeleton was analyzed including patients with ankylosing spondylitis and with Paget disease as well as patients after spine surgery including assessment of cage incorporation after cervical and lumbar spine fusion surgery. Furthermore, children suspected of child abuse as well as young patients with back pain were investigated by either (18)F-fluoride PET or PET/CT. Regarding its favorable technical aspects as well as study results presented, it is imaginable that (18)F-fluoride PET/(CT) will be increasingly used for non-oncologic musculoskeletal imaging in the future either as an adjunct or alternative to so far established imaging modalities and seems to be promising regarding decision making in the therapeutic management of patients with non-oncologic musculoskeletal disorders.

SAT0397 High bone turnover assessed by 18F-fluoride PET/CT in the spine of patients with ankylosing spondylitis: No redundancy to inflammatory lesions detected by whole body MRI

Background The current paradigm of radiographic progression in ankylosing spondylitis involves resolution of an inflammatory lesion and its replacement by fat tissue followed by cartilage metaplasia and endochondral ossification. However, syndesmophytes may also develop at sites without inflammation on baseline and follow up MRI, potentially through noninflammatory pathways. High bone turnover assessed by nuclear medicine methods may detect osteoproliferative processes regardless of their inflammatory or noninflammatory origin. Objectives To compare the frequency and distribution of increased activity on 18F-fluoride PET/CT with the presence of bone marrow edema on whole body MR imaging in patients with active ankylosing spondylitis. Methods 10 patients (6 men and 4 women, between 32 and 58 years old (median 44) with active ankylosing spondylitis were prospectively examined with both whole-body MRI and 18F-Fluoride-PET/CT. Patients fulfilled the modified New York criteria for ankylosing spondylitis and had a Bath Ankylosing Spondylitis Disease Activity Index of at least 4. Increased radiotracer uptake in PET/CT and bone marrow edema in whole body MRI of spine and sacroiliac joints were scored independently by two blinded observers for each modality. Kappa statistics were used to analyze interobserver agreement as well as consensus reading of the two imaging modalities. Results Analysis of interobserver agreement for PET/CT yielded a kappa value of 0.68 for spinal lesions and of 0.88 for SIJ lesions. The corresponding kappa values for MRI were 0.64 and 0.93 respectively. More spinal lesions were detected by MRI in comparison to PET/CT (68 vs. 38 out of 240), whereas a similar number of SIJ quadrants scored positive in both modalities (19 vs. 17 out of 80). Analysis of agreement of lesion detection between both imaging modalities yielded a kappa value of only 0.25 for spinal lesions and of 0.64 for SIJ lesions. Conclusions Increased 18F-fluoride uptake in PET/CT correlates only modestly with bone marrow edema on MRI in the spine of patients with AS. The additional information provided by F-PET/CT imaging may complement MRI for disease assessment and prediction of spinal radiological progression. Disclosure of Interest None Declared