Algorithm for Reducing Overall Biological Detriment Caused by PET/CT: an Age-Based Study.

Purpose: This study is to use a simple algorithm based on patient's age to reduce the overall biological detriment associated with PET/CT. Materials and Methods: A total of 421 consecutive patients (mean age 64 ± 14 years) undergoing PET for various clinical indications were enrolled. For each scan, effective dose (ED in mSv) and additional cancer risk (ACR) were computed both in a reference condition (REF) and after applying an original algorithm (ALGO). The ALGO modified the mean dose of FDG and the PET scan time parameters; indeed, a lower dose and a longer scan time were reported in the younger, while a higher dose and a shorter scan time in the older patients. Moreover, patients were classified by age bracket (18-29, 30-60, and 61-90 years). Results: The ED was 4.57 ± 0.92 mSv in the REF condition. The ACR were 0.020 ± 0.016 and 0.0187 ± 0.013, respectively, in REF and ALGO. The ACR for the REF and ALGO conditions were significantly reduced in males and females, although it was more evident in the latter gender (all p < 0.0001). Finally, the ACR significantly reduced from the REF condition to ALGO in all three age brackets (all p < 0.0001). Conclusion: Implementation of ALGO protocols in PET can reduce the overall ACR, mainly in young and female patients.

Ageing effect on 18F-DOPA and 123I-MIBG uptake: a cross-sectional study.

BACKGROUND: The aim of this study was to investigate the relationship between age and uptake of fluorine-18-L-dihydroxyphenylalanine (F-DOPA) in the brain and myocardial uptake of iodine-123-metaiodobenzylguanidine (I-MIBG) in normal adult participants. PARTICIPANTS AND METHODS: To this end, a total of 72 healthy participants were enroled. Of these, 37 individuals (male, 21; female, 16; mean age: 60±12 years; age range: 38-85 years) underwent F-DOPA PET/CT, whereas 35 individuals (male, 19; female, 16; mean age: 61±17 years; age range: 17-87 years) underwent I-MIBG scintigraphy. For F-DOPA PET/CT, regions of interest were placed on the caudate nucleus, globus pallidus and putamen by means of the WFU Pickatlas tool implemented in SPM8 and further analysed after a normalization process. For I-MIBG scintigraphy, regions of interest were set over the upper mediastinum and a heart-to-mediastinum count ratio was calculated. The relation between age and normalized F-DOPA values or heart-to-mediastinum ratio values was examined using correlation analysis of variance and Pearson's correlation coefficient. RESULTS: We did not find any significant relationship between age and F-DOPA and I-MIBG uptake, respectively. CONCLUSION: Our findings suggest that both brain F-DOPA PET/CT and cardiac I-MIBG scintigraphy represent age-independent biomarkers whose analyses of quantitative uptake may not require adjustment for patients' age.

Coupled Imaging with [18F]FBB and [18F]FDG in AD Subjects Show a Selective Association Between Amyloid Burden and Cortical Dysfunction in the Brain.

PURPOSE: The present study was aimed to investigate the relationships between dysfunction of cortical glucose metabolism as detectable by means of 2-deoxy-2-[18F]fluoro -D-glucose ([18F]FDG) positron emission tomography/x-ray computed tomography (PET/CT) and amyloid burden as detectable by means of 4-{(E)-2-[4-(2-{2-[2-[18F]fluoroethoxy]ethoxy}ethoxy)phenyl]vinyl}-N-methylaniline (florbetaben; [18F]FBB) in a group of patients affected by Alzheimer's disease (AD). PROCEDURES: We examined 38 patients newly diagnosed with AD according to the NINCDS-ADRDA criteria. All the subjects underwent a PET/CT scan using both [18F]FDG and [18F]FBB with an average interval of 1 month. We used statistical parametric mapping (SPM8) implemented in Matlab R2012b and WFU pickatlas for the definition of a region of interest (ROI) mask including the whole cortex. These data were then normalized on the counts of the cerebellum and then used for a regression analysis on [18F]FDG scans in SPM. Furthermore, 58 control subjects were used as control group for [18F]FDG PET/CT scans. RESULTS: SPM analysis in AD patients showed a significant negative correlation between [18F] FBB and [18F] FDG uptake in temporal and parietal lobes bilaterally. Of note, these areas in AD patients displayed a marked glucose hypometabolism compared to control group. CONCLUSIONS: Combined imaging with [18F]FBB and [18FFDG shows that amyloid burden in the brain is related to cortical dysfunction of temporal and parietal lobes in AD.

Brain metabolic correlates of CSF Tau protein in a large cohort of Alzheimer's disease patients: A CSF and FDG PET study.

AIMS: Physiopathological mechanisms of Alzheimer's disease (AD) are still matter of debate. Especially the role of amyloid ß and tau pathology in the development of the disease are still matter of debate. Changes in tau and amyloid ß peptide concentration in cerebrospinal fluid (CSF) and hypometabolic patterns at fluorine-18 fluorodeoxyglucose (18F-FDG) PET scanning are considered as biomarkers of AD. The present study was aimed to evaluate the relationships between the concentrations of CSF total Tau (t-Tau), phosphorilated Tau (p-Tau) and Aß1-42 amyloid peptide with 18F-FDG brain distribution in a group of patients with AD. MATERIALS AND METHODS: We examined 131 newly diagnosed AD patients according to the NINCDS-ADRDA criteria and 20 healthy controls. The mean (±SD) age of the patients was 70 (±7) years; 57 were male and 74 were female. All patients and controls underwent a complete clinical investigation, including medical history, neurological examination, mini-mental state examination (MMSE), a complete blood screening (including routine exams, thyroid hormones and a complete neuropsychological evaluation). Structural MRI was performed not earlier than 1 month before the 18F-FDG PET/CT. The following patients were excluded: those with isolated deficits and/or unmodified MMSE (=25/30) on revisit (period of follow-up: 6, 12 and 18 months); patients who had had a clinically manifest acute stroke in the last 6 months with a Hachinsky score greater than 4; and patients with radiological evidence of subcortical lesions. All AD patients were taken off cholinesterase inhibitor treatment throughout the study. We performed lumbar puncture and CSF sampling for diagnostic purposes 2 weeks (±2 days) before the PET/CT scan. The relationship between brain F-FDG uptake and CSF biomarkers was analysed using statistical parametric mapping (SPM8; Wellcome Department of Cognitive Neurology, London, UK) implemented in Matlab R2012b using the MMSE score, sex and age, and other CSF biomarkers as covariates. RESULTS: t-Tau, p-Tau and Aß(1-42) in CSF resulted 774 ±â€¯345 pg/ml, 98 ±â€¯64 pg/ml and 348.8 ±â€¯111 pg/ml respectively. SPM analysis showed a significant negative correlation between CSF t-Tau and 18F FDG uptake in right temporal, parietal and frontal lobe (Brodmann areas, BA, 20, 40 and 8; P fdr and few corr < 0.001, ke 19534). We did not find any significant relationships with other CSF biomarkers. CONCLUSIONS: t-Tau deposition in brain is related to temporal, parietal and frontal hypometabolism in AD.

Role of Positron Emission Tomography for Central Nervous System Involvement in Systemic Autoimmune Diseases: Status and Perspectives.

In the last years, an increasing interest in molecular imaging has been raised by the extending potential of positron emission tomography [PET]. The role of PET imaging, originally confined to the oncology setting, is continuously extending thanks to the development of novel radiopharmaceutical and to the implementation of hybrid imaging techniques, where PET scans are combined with computed tomography [CT] or magnetic resonance imaging[MRI] in order to improve spatial resolution. Early preclinical studies suggested that 18F-FDG PET can detect neuroinflammation; new developing radiopharmaceuticals targeting more specifically inflammation-related molecules are moving in this direction. Neurological involvement is a distinct feature of various systemic autoimmune diseases, i.e. Systemic Lupus Erythematosus [SLE] or Behcet's disease [BD]. Although MRI is largely considered the gold-standard imaging technique for the detection of Central Nervous System [CNS] involvement in these disorders. Several patients complain of neuropsychiatric symptoms [headache, epilepsy, anxiety or depression] in the absence of any significant MRI finding; in such patients the diagnosis relies mainly on clinical examination and often the role of the disease process versus iatrogenic or reactive forms is doubtful. The aim of this review is to explore the state-of-the-art for the role of PET imaging in CNS involvement in systemic rheumatic diseases. In addition, we explore the potential role of emerging radiopharmaceutical and their possible application in aiding the diagnosis of CNS involvement in systemic autoimmune diseases.

18F-DOPA PET/CT Physiological Distribution and Pitfalls: Experience in 215 Patients.

PURPOSE: F-DOPA PET/CT is potentially helpful in the management of patients with low-grade brain tumors, movement disorders, and somatic neuroendocrine tumors. We describe the whole-body physiological distribution of F-DOPA uptake. PATIENTS AND METHODS: We examined 215 patients with F-DOPA PET/CT. Among these, 161 had brain scans and 54 had whole-body scans. RESULTS: Physiological distribution was negligible in the brain, with the exception of basal ganglia, whereas greatest activity was noted in the liver, pancreas, other exocrine glands, and the urinary system. Incidental tracer uptake sites were identified in 5.5% of patients. Some of these findings were due to inflammation, whereas in most cases, uptake was seen in benign tumors of the brain or in the endocrine or exocrine glands. CONCLUSIONS: F-DOPA uptake may be seen in inflammatory tissue or benign tumors. Correlations with history, physical examination, laboratory examination, CT, MRI, and histology are necessary for optimal diagnosis.

[Whole Body Magnetic Resonance and CT/PET in patients affected by multiple myeloma during staging before treatment]. / TC/PET e WBMRI in pazienti affetti da mieloma multiplo in stadiazione e prima di trattamento.

The diagnostic imaging plays a pivotal role in the staging of multiple myeloma (MM). Traditional imaging techniques allow a precise disease extension before treatment, but some drawbacks have been demonstrated after treatment. WBMRI and CT/PET represent alterative procedures during staging, but few comparative data are available to date. Aim of our study was to estimate the diagnostic accuracy of WB-MRI and CT/PET in 28 consecutive patients affected by MM before therapy. CT/PET was positive in 22/28 patients, whereas WB-MRI correctly identified 100% of patients. In this setting of patients WB MRI have demonstrated to be superior respect to CT/PET in term of diagnostic accuracy, especially when a diffuse disease is detected with a bone marrow aspiration with more than 40% of plasma cells. WBMRI shows a diagnostic accuracy higher than FDG-CT/PET in staging especially when diffuse. However a whole body coverage is crucial to properly manage MM patients irrespective of which technique is used.