Low dose radiation 18F-fluoride PET/CT in the assessment of Unilateral Condylar Hyperplasia of the mandible: preliminary results of a single centre experience.

BACKGROUND: 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. AIM: 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. MATERIALS AND METHODS: 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. RESULTS: 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]. DISCUSSION: 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. CONCLUSIONS: 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.

Cysts of the atlantoaxial joint: excellent long-term outcome after posterolateral surgical decompression. Report of two cases.

Articular cysts of the atlantoaxial joint are infrequently described and probably an underreported cause of upper cervical spinal cord compression. The authors report on two patients with cysts located posteriorly of the dens in whom a C-1 and partial C-2 hemilaminectomy with subtotal resection of the cyst provided adequate and stable decompression 1 year postoperatively. The clinical and magnetic resonance imaging features and the surgical approach are discussed after a review of the literature.

Immunological abnormalities in intravenous drug abusers and relationship to the prolonged generalized lymphadenopathy syndrome in Italy.

The prolonged generalized lymphadenopathy syndrome (PGL) has been considered a prodromal condition to the Acquired immunodeficiency syndrome (AIDS), but the clinical, virological and immunological characteristics of patients who will develop AIDS are not known. We report on the immunological profile of intravenous drug abusers with or without PGL in Northeastern Italy. We found a reduction of lymphocyte-absolute numbers with reversal of the T4/T8 ratio and decreased Leu-11b+ cells. The response to mitogens and natural killer activity are compromised in PGL patients. Neutrophil function is reduced both in drug abusers with or without lymphadenopathy. The serological investigations revealed a high prevalence of antibodies against HTLV III and the Epstein-Barr viruses. The recognition of immune dysfunction in the intravenous drug abusers appears to be important since these patients develop AIDS and these abnormalities may precede AIDS.

Lymph node immunohistology in intravenous drug abusers with persistent generalized lymphadenopathy.

Lymph node biopsy specimens from 16 intravenous drug abusers with persistent generalized lymphadenopathy were evaluated by immunohistochemical methods using a panel of antisera to detect different cell populations. The 11 cases that we tested on cryostat sections showed an increased number of Leu-2a-positive cells (cytotoxic-suppressor phenotype) in the follicular centers and a significantly reduced helper-to-suppressor T-cell mean ratio when compared with control tissues. In these 11 patients the peripheral helper-suppressor ratio was at the lower normal limit or inverted. Ten cases tested for anti-human T-cell lymphotropic virus type III antibodies were positive. In all 16 cases, immunohistology of paraffin-embedded sections demonstrated a polyclonal B population; 12 of 15 patients tested had polyclonal hypergammaglobulinemia, mostly IgG. The mixed-cell population of the lymph node sinuses was composed mostly of Leu-M1-positive and lysozyme-positive cells and, to a lesser extent, by alpha 1-antichymotrypsin-positive and S100 protein-positive cells. It seems that many of the immunologic dysfunctions found in these patients appear to be reflected in a fairly repetitive immunohistologic pattern.