Osteoarthritis (OA) is a debilitating disease generally of old age manifested as degeneration of articular cartilage. With no definitive treatment available, ongoing research aims at early detection and use specific noninvasive imaging markers to monitor therapeutic efficacy of disease modifying osteoarthritic drug (DMOAD) to reverse or/and arrest the disease process. Articular cartilage degradation and loss, as well as bone remodelling, are typical biomarkers of OA. As a result, an ideal imaging technique for early detection of OA is required, which must be sensitive to both soft tissue and bone health. PET/MRI is emerging as an imaging tool which can be used to study the underlying pathogenesis of OA as it enables us to assess molecular activity with PET markers while also linking them to qualitative and quantitative MRI indices of OA. In this regard recent work was exploring the role of 18F-Na Fluoride which is a marker of bone remodelling together with MRI in early detection of OA on simultaneous PET/MRI. In this article we intend to present different patterns of OA (mild to severe stages of OA) that we had observed on 18F-Sodium Fluoride (18F-NaF) PET/MRI.

The objective was to dynamically monitor the progression of atherosclerotic plaques in ApoE-/- mice with 18F-NaF PET imaging. The ApoE-/- mice were used to develop atherosclerosis models, and the C57BL/6 J mice were used as control. 18F-NaF PET was performed when the mice were 12, 20, and 30 weeks of age. Serum lipids and lipoproteins profiles, inflammatory cytokines, and calcification factors were tested by ELISA. The lipid distribution, morphology, and calcification of plaque were evaluated by Oil Red O, HE, and alizarin red staining. The correlation between imaging and the extent of calcification was analyzed by Pearson correlation analysis. The uptake of 18F-NaF in the aorta was gradually increased with each weekly extension. Compared with the ApoE-/- mice at the age of 12 weeks and 20 weeks, the levels of lipoprotein, inflammatory cytokines, and calcification factors were higher at 30 weeks. In Oil Red O, HE, and alizarin red staining, the extent of the lipid area and calcification increased with time. The correlation analysis showed that the uptake of 18F-NaF in the aorta was related to the extent of calcification. 18F-NaF may dynamically monitor the progression of atherosclerotic plaques and ongoing microcalcification formation.

UNASSIGNED: Unilateral condylar hyperplasia (UCH) of the mandible, or Hypercondylia, is a pathological condition that determines an abnormal growth of the affected condyle.Bone SPECT with Tc99m-diphosphonates is a successful tool in the diagnosis of UCH. EANM guidelines also suggest the use of 18F-NaF PET/CT, though it leads to a higher radiation exposure.
UNASSIGNED: As UCH patients are young, we aimed to develop a low dose 18F-Fluoride PET/CT protocol and compare it to a standard injected activity scan, to assess if the image quality remains unchanged.
UNASSIGNED: We prospectively enrolled 20 patients (7 males, 13 females, mean age 23.2) with UCH, who underwent 18F-NaF PET/CT to assess the hypercondylia. We administered a low activity of 18F-NaF (2.9 MBq/kg) in 15 patients and a standard activity (5.3 MBq/kg) in 5 patients. Activity range was chosen according to 2015 EANM guidelines.To determine if the scans with low radiotracer activity were \"diagnostic\" such as those with standard activity, two expert nuclear medicine physicians, unaware of the administered activity, independently reviewed the scans and expressed a final qualitative judgment in terms of \"diagnostic\"/\"non-diagnostic\" scan. Furthermore, we compared the effective dose of a low injected activity PET/CT to the standard one and to a Bone SPECT performed with standard injected activity of Tc99m-diphosphonates.
UNASSIGNED: Reviewers classified 19 of 20 scans as \"diagnostic\". Only one of them was classified as \"non diagnostic\" due to condylar arthrosis that disturbed the correct evaluation of condylar radiotracer uptake. The effective dose of a 18F-Fluoride PET/CT, in patient of 70 kg, is about 3.5 mSv in scans performed with 2.9 MBq/kg [0.017 mSv/MBq × 2.9 MBq/kg × 70 kg] and about 6.3 mSv in ones performed with 5.3 MBq/kg [0.017 mSv/MBq × 5.3 MBq/kg × 70 kg]. The effective dose of 99mTc-MDP bone SPECT is about 3.2 mSv [0.0043 mSv/MBq × 740 MBq of 99mTc-MDP].
UNASSIGNED: 18F-NaF PET/CT performed with a low radiotracer activity allows a good assessment of UCH similar to that performed with an ordinary activity. The effective radiation dose of a low-injected activity PET/CT is significantly lower than an ordinary-injected activity and is not significantly higher than the most used Bone SPECT. Moreover PET/CT is performed in 1.5 h while Bone SPECT requires at least 3.5 h.
UNASSIGNED: The 18F-Fluoride PET/CT procedure could be performed with 2.9 MBq/Kg (minimum 185 MBq, recommended at least 200 MBq) of 18F-NaF to minimize the effective radiation dose received, maintaining the quality of the scan. Further studies including a larger number of patients and clinical follow-up are needed to confirm our preliminary findings.