Bone Metabolism after Total Hip Revision Surgery with Impacted Grafting: Evaluation using H215O and [18F]fluoride PET; A Pilot Study

Purpose: To evaluate bone blood flow and bone formation in patients after total hip revision surgery with impacted bone grafting using H2 15O and [18F]fluoride positron emission tomography (PET). Procedures: To asses bone blood flow and bone metabolism in bone allograft after impaction grafting, four patients treated with total hip revision surgery were enrolled prospectively in this study. Six patients scheduled for primary hip arthroplasties were included as a control group. The study protocol consisted of three H2 15O and [18F]fluoride PET scans in each patient. Results: Bone blood flow increased significantly compared to the preoperative state in patients treated for primary hip arthroplasty. In patients undergoing revision surgery, bone blood flow was twofold to threefold higher compared to the preoperative state, but did not reach significance. Bone metabolism in patients undergoing revision was threefold higher 2 weeks postoperatively compared to the primary hip group. We found a significant correlation between Ki and bone blood flow. Conclusions: Allogeneic bone grafts induce a higher rate of local periprosthetic bone formation compared to periprosthetic bone formation after a primary total hip placement. In vivo coupling between bone blood flow and bone metabolism suggests that bone metabolism in allogeneic bone grafts may partly rely on bone blood flow adaptations

tumor atelectasis gives rise to a solid appearance in pulmonary adenocarcinomas on hr ct

Abstract Introduction Ground glass opacities on HR-CT scan, if malignant on histological examination, correlate with adenocarcinoma in situ. Solid appearance on HR-CT is often considered an invasive component. This study aims to compare radiological features on HR-CT and histological features of primary adenocarcinomas in resection specimens in order to demonstrate the presence of tumor atelectasis in ground glass nodules, part solid and solid nodules. Materials and Methods HR-CT imaging was evaluated, and lung nodules were classified as ground glass nodule, part solid nodule and solid nodule, while adenocarcinomas were classified according to WHO classification. Lepidic growth pattern with collapse was considered if reduction of air in the histological section was present, with maintained pulmonary architecture (without signs of pleural or vascular invasion). Results Radiological and histological features were compared in 47 lesions of 41 patients. The number of ground glass, part solid and solid nodules were 2, 8 and 37, respectively. Lepidic growth pattern with collapse was observed in both ground glass nodules, 7 out of 8 (88%) part solid and 24 out of 37 (65%) solid lesions. Remarkably, more than 50% of adenocarcinomas with solid appearance on HR-CT showed a pre-existing pulmonary architecture with adenocarcinoma with a predominant lepidic growth pattern. In these cases, the solid component can be explained by tumor related collapse in vivo (tumor atelectasis on radiology). Conclusion Tumor atelectasis is a frequent finding in pulmonary adenocarcinomas and results in solid appearance on HR-CT. A solid appearance on HR-CT can not only be attributed to invasion, as has been the assumption until now

The correlation between clinical, nuclear and histologic findings in a patient with Von Recklinghausen's disease

<p>Abstract</p> <p>Background</p> <p>Malignant peripheral nerve sheath tumours (MPNST) are known to develop in patients with Neurofibromatosis type I (NF1) resulting in a decreased overall survival. The association between NF1 and the development of such MPNST has been investigated in detail. The biological behaviour however of multiple disseminated neurofibromas in patients with NF1 and the risk factors for malignant transformation remain unknown. Clinical signs are unreliable and additional imaging techniques are therefore required. Of such, positron emission tomography using [¹⁸F]-2-fluoro-2-deoxy-D-glucose (¹⁸FDG PET) is used to detect malignant changes in neurofibromas.</p> <p>Case presentation</p> <p>A case is presented of a patient suffering from NF1 with clinical signs of malignant change and accumulation of ¹⁸FDG in multiple neurofibromas. Histopathological examination of 20 lesions however, did not reveal any malignant features. There was no statistically significant relation between¹⁸FDG accumulation and malignant change, but rather with pain, size and growth.</p> <p>Conclusion</p> <p>This case adds to the knowledge of the diverse biological behaviour of neurofibromas in patients with NF1</p

Should vascular wall F-18-FDG uptake be adjusted for the extent of atherosclerotic burden?

Vascular wall 18F-FDG uptake is often used as a surrogate marker of atherosclerotic plaque inflammation. A potential caveat is that vascular wall 18F-FDG uptake is higher simply because more atherosclerosis is present. To determine if the degree of inflammation is high or low relative to the extent of atherosclerosis, vascular wall 18F-FDG uptake may require statistical adjustment for a non-inflammatory marker reflecting the extent of atherosclerosis, e.g. calcification. Adjustments is probably needed if (1) vascular wall 18F-FDG uptake correlates sufficiently strongly with arterial calcification and (2) adjustment for extent of calcification affects determinants of vascular 18F-FDG uptake. This study addresses these questions. 18F-FDG PET/low-dose-CT scans of 99 patients were used. Cardiovascular risk factors were assessed and PET/CT scans were analysed for standardized 18F-FDG uptake values and calcification. ANOVA was used to establish the association between vascular 18F-FDG uptake and calcification. Multiple linear regression (with and without calcification as independent variable) was used to show whether determinants of vascular 18F-FDG uptake were affected by the degree of calcification. 18F-FDG uptake was related to increased calcification in the aortic arch, descending and abdominal aorta. However, 18F-FDG uptake showed considerable overlap between categories of calcification. Age and body mass index were main determinants of vascular 18F-FDG uptake. In multiple regression analyses, most standardized beta coefficients of these determinants were not affected by adjustment for the degree of calcification. Although vascular 18F-FDG uptake is related to total atherosclerotic burden, as reflected by vascular calcification, the association is weak and unlikely to affect the identification of determinants of atherosclerotic inflammation implicating no need for adjustment in future studies

Observer Variation of 2-Deoxy-2-[F-18]fluoro-d-Glucose-Positron Emission Tomography in Mediastinal Staging of Non-Small Cell Lung Cancer as a Function of Experience, and its Potential Clinical Impact

Purpose: To test the extent of variation among nuclear medicine physicians with respect to staging non-small cell lung cancer with positron emission tomography (PET). Procedures: Two groups of nuclear medicine physicians with different levels of PET experience reviewed 30 PET scans. They were requested to identify and localize suspicious mediastinal lymph nodes (MLN) using standardized algorithms. Results were compared between the two groups, between individuals, and with expert reading. Results: Overall we found good interobserver agreement (kappa 0.65). Experience with PET translated into a better ability to localize MLN stations (68 % vs. 51%, respectively), and experienced readers appeared to be more familiar with translating PET readings into clinically useful statements. Conclusions: Although our results suggest that clinical experience with PET increases observers _ ability to read and interpret results from PET adequately, there is room for improvement. Experience with PET does not necessarily improve the accuracy of image interpretation

FDG PET and PET/CT: EANM procedure guidelines for tumour PET imaging: version 1.0

The aim of this guideline is to provide a minimum standard for the acquisition and interpretation of PET and PET/CT scans with [18F]-fluorodeoxyglucose (FDG). This guideline will therefore address general information about [18F]-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET/CT) and is provided to help the physician and physicist to assist to carrying out, interpret, and document quantitative FDG PET/CT examinations, but will concentrate on the optimisation of diagnostic quality and quantitative information