The effects of image reconstruction algorithms on topographic characteristics,diagnostic performance and clinical correlation of metabolic brain networks in Parkinson’s disease

PurposeThe purpose of this study was to evaluate the effects of different image reconstruction algorithms on topographic characteristics and diagnostic performance of the Parkinson’s disease related pattern (PDRP).MethodsFDG-PET brain scans of 20 Parkinson’s disease (PD) patients and 20 normal controls (NC) were reconstructed with six different algorithms in order to derive six versions of PDRP. Additional scans of 20 PD, 25 atypical parkinsonism (AP) patients and 20 NC subjects were used for validation. PDRP versions were compared by assessing differences in topographies, individual subject scores and correlations with patient’s clinical ratings. Discrimination of PD from NC and AP subjects was evaluated across cohorts.ResultsThe region weights of the six PDRPs highly correlated (R ≥ 0.991; p < 0.0001). All PDRPs’ expressions were significantly elevated in PD relative to NC and AP subjects (p < 0.0001) and correlated with clinical ratings (R ≥ 0.47; p < 0.05). Subject scores of the six PDRPs highly correlated within each of individual healthy and parkinsonian groups (R ≥ 0.972, p < 0.0001) and were consistent across the algorithms when using the same reconstruction methods in PDRP derivation and validation. However, when derivation and validation reconstruction algorithms differed, subject scores were notably lower compared to the reference PDRP, in all subject groups.ConclusionPDRP proves to be highly reproducible across FDG-PET image reconstruction algorithms in topography, ability to differentiate PD from NC and AP subjects and clinical correlation. When calculating PDRP scores in scans that have different reconstruction algorithms and imaging systems from those used for PDRP derivation, a calibration with NC subjects is advisable.     

Illustrations cliniques en cardiologie

The examples and clinical cases presented in this section are not intended to be considered as absolute models in terms of image quality or device parameter settings. They must initiate an individual analysis according to CT parameters and image quality. Nevertheless, they present practically different CT levels which can be used according to the clinical context and the type of device.     

Quantification of atherosclerotic plaque activity and vascular inflammation using [18-F] fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT)

Conventional non-invasive imaging modalities of atherosclerosis such as coronary artery calcium (CAC) and carotid intimal medial thickness (C-IMT) provide information about the burden of disease. However, despite multiple validation studies of CAC, and C-IMT, these modalities do not accurately assess plaque characteristics, and the composition and inflammatory state of the plaque determine its stability and, therefore, the risk of clinical events. [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG) imaging using positron-emission tomography (PET)/computed tomography (CT) has been extensively studied in oncologic metabolism. Studies using animal models and immunohistochemistry in humans show that FDG-PET/CT is exquisitely sensitive for detecting macrophage activity, an important source of cellular inflammation in vessel walls. More recently, we and others have shown that FDG-PET/CT enables highly precise, novel measurements of inflammatory activity of activity of atherosclerotic plaques in large and medium-sized arteries. FDG-PET/CT studies have many advantages over other imaging modalities: 1) high contrast resolution; 2) quantification of plaque volume and metabolic activity allowing for multi-modal atherosclerotic plaque quantification; 3) dynamic, real-time, in vivo imaging; 4) minimal operator dependence. Finally, vascular inflammation detected by FDG-PET/CT has been shown to predict cardiovascular (CV) events independent of traditional risk factors and is also highly associated with overall burden of atherosclerosis. Plaque activity by FDG-PET/CT is modulated by known beneficial CV interventions such as short term (12 week) statin therapy as well as longer term therapeutic lifestyle changes (16 months). The current methodology for quantification of FDG uptake in atherosclerotic plaque involves measurement of the standardized uptake value (SUV) of an artery of interest and of the venous blood pool in order to calculate a target to background ratio (TBR), which is calculated by dividing the arterial SUV by the venous blood pool SUV. This method has shown to represent a stable, reproducible phenotype over time, has a high sensitivity for detection of vascular inflammation, and also has high inter-and intra-reader reliability. Here we present our methodology for patient preparation, image acquisition, and quantification of atherosclerotic plaque activity and vascular inflammation using SUV, TBR, and a global parameter called the metabolic volumetric product (MVP). These approaches may be applied to assess vascular inflammation in various study samples of interest in a consistent fashion as we have shown in several prior publications.     

Comparison of the biological effects of F at different intracellular levels

We herein examined the biological effects of cells treated with ¹⁸F labeled drugs for positron emission tomography (PET). The relationship between the intracellular distribution of ¹⁸F and levels of damaged DNA has yet to be clarified in detail. We used culture cells (Chinese Hamster Ovary cells) treated with two types of ¹⁸F labeled drugs, fluorodeoxyglucose (FDG) and fluorine ion (HF). FDG efficiently accumulated in cells, whereas HF did not. To examine the induction of DNA double strand breaks (DSB), we measured the number of foci for 53BP1 that formed at the site of DNA DSB. The results revealed that although radioactivity levels were the same, the induction of 53BP1 foci was stronger in cells treated with ¹⁸F-FDG than in those treated with ¹⁸F-HF. The clonogenic survival of cells was significantly lower with ¹⁸F-FDG than with ¹⁸F-HF. We concluded that the efficient accumulation of ¹⁸F in cells led to stronger biological effects due to more severe cellular lethality via the induction of DNA DSB.     

Equivalent dose rate from patients after whole-body FDG-PET/CT

Introduction

¹⁸F-fluorodeoxyglucose PET/CT (FDG-PET/CT) is an imaging modality routinely used in oncology, hematology, as well as in infectious and inflammatory diseases. Frequently, patients and their accompanying persons may be apprehensive concerning risks of radiation exposure after performing this examination, particularly when it concerns nearby young adolescents or pregnant women. Our objective was to clearly explain about radiation protection instructions for patients after performing whole-body FDG-PET/CT based on the Equivalent Dose Rate (EDR) estimation at our nuclear medicine department.

Précautions,pièges et artefacts en TEP/TDM au 18FDG : généralités et cas particulier des pathologies de la tête et du cou

The PET/CT imaging with 18F-FDG is an essential diagnostic tool in the management of many diseases today. However, because of its functional and metabolic nature, it requires for its realization the respect of certain precautions to avoid abnormal images or false negative tests. Moreover, in the context of head and neck diseases, knowledge of anatomy and physiological uptakes appears essential for quality interpretation. In this paper, we illustrate with several personal circumstances or particular clinical situations from literature, the potential pitfalls and artifacts that could lead to misinterpretation.     

Évaluation de l’exactitude de latéralisation du foyer épileptogène par la tomographie par émission de positons au 18f-fluorodésoxyglucose dans le bilan préopératoire de l’épilepsie temporale : analyse visuelle simple et par index d’asymétrie inter-hémisphérique par soustraction d’images,analyse quantitative par statistical parametric mapping

IntroductionInter-ictal 18F-2-fluoro-deoxy-D-glucose-positron emission tomography (FDG-PET) plays a key role for the preoperative evaluation of patients with pharmacoresistant temporal lobe epilepsy. PET images are usually analyzed visually, a way that is reported to provide a high diagnostic value but that remains subjective, depending on the expertise and experience of the observer. By contrast, the voxel-based quantitative analyses, such as statistical parametric mapping (SPM), are objective and therefore, observer independent methods of analyses. In this study, the accuracy of the analyses of brain FDG-PET images to lateralize the temporal lobe epileptogenic zone was compared between: (1) a conventional visual method, (2) a quantitative SPM analysis, and (3) a visual analysis of inter-hemispheric asymmetry (IHA) obtained after images substraction.Materials and methodsFDG-PET scans of 31 patients presenting a severe temporal epilepsy and whom the temporal foci had been accurately lateralized (successful subsequent surgical treatment) were retrospectively analysed by (1) a consensual visual analysis from two experienced observers; (2) SPM analysis with voxel-wise comparisons of FDG-PET images of patients with those of age-matched healthy controls, using various statistical threshold (P) and cluster (k) values; and (3) visual assessment by the two same observers of images obtained for assessing the IHA. For this purpose, a flipped image was initially obtained by reversing in the left-right direction the FDG-PET images, which had been previously spacially normalized with the SPM template. Then, flipped and non-flipped images were substracted.ResultsThe temporal hypometabolic area was accurately identified: (1) by the conventional visual analysis in 87 % of patients and with a satisfactory interobserver reproducibility (interobserver Cohen's coefficient = 0.79); (2) by SPM analysis, in 90 % of patients (when using optimal thresholds of 0.01 for P value and of 50 voxels (400 mm³) for k value); and (3) with the visual analysis of IHA in 97 % of patients with an excellent interobserver reproductibility (interobserver Cohen's coefficient = 1).ConclusionIn patients presenting severe temporal epilepsy, visual assessment of FDG-PET images from IHA seems more accurate for lateralizing the epileptogenic temporal areas when compared with either conventional visual or quantitative SPM analyses. Moreover, this method is very easy to use in clinical practice, contrary to the quantitative method using SPM     

Review article: FDG-PET in inflammatory diseases

Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) has for the past several years demonstrated its high value in oncology. The physiopathology of FDG explains its increasingly frequent use for inflammatory diseases such as vasculitis (giant cell arteritis or Takayasu's arteritis) as well as for granulomatous diseases (sarcoidosis, tuberculosis). The value of FDG-PET lies in its usefulness for the diagnosis of systemic diseases which includes a whole body analysis as well as a therapeutic evaluation. This review article will attempt to identify and illustrate the main features of this functional imaging.     

Value of 111In-Pentetreotide scintigraphy and 18F-FDG PET for clinical prognosis of patients with neuroendocrine neoplasms

Despite the existence of biological markers of aggressiveness, the clinical course of gastro-entero-pancreatic (GEP) neuroendocrine neoplasms (NEN) remains difficult to predict. Discrepancies between imaging data generated with ¹¹¹In-pentetreotide scintigraphy and ¹⁸F-FDG-PET could reflect the degree of cellular de-differentiation. NEN patients with both types of studies were identified retrospectively from the SwissNET database, which is collecting information on Swiss NEN patients since 2008. Progression free survival (PFS) and overall survival (OS) were assessed depending on functional imaging results. Correlation between histological grading (according to the WHO 2010 classification) and functional imaging status was also assessed. We identified 31 patients with both imaging studies, either on the primary tumor site (21/31) or for metastases (21/31), with 12/31 on both sites. Mean follow-up was 36 months (95% CI 27–45). 21 patients had a metastatic disease at diagnosis and 11 died at follow-up. 7/31 (22%) were NET G1, 16/31 (52%) were NET G2 and 8/31 (26%) were NEC G3. Only ¹⁸F-FDG PET status almost reached statistical significance (P = 0.054) with histological grading. Progression free-survival was significantly poorer in the ¹⁸F-FDG positive group (n = 21), with a median time for progression of 8 months, compared to 51 months in the negative group (n = 10) with a HR of 3.2 (97.5% CI 1.1–9.5, P = 0.04). Overall survival tended to be worse with a positive PET and a negative ¹¹¹In-pentetreotide scintigraphy status with a HR 1.63 (97.5%CI 0.11–21, P = 0.08). ¹¹¹In-pentetreotide scintigraphy status was not found to be predictive of survival nor progression.ConclusionThese data demonstrate the poorer prognostic value of a positive ¹⁸F-FDG-PET imaging in this cohort of patients.     

Carcinoma of unknown primary in the head and neck: The evaluation of the effectiveness of 18F-FDG-PET/CT,own experience

AimThe aim of the present study was to estimate the clinical effectiveness of ¹⁸F-FDG-PET/CT in the detection of the primary tumor in patients with histologically proven squamous cell carcinoma cervical lymph nodes metastasis from an unknown primary.Background¹⁸F-fluorodeoxyglucose positron emission tomography combined with CT (¹⁸F-FDG-PET/CT) is believed to be very helpful in localization of primary tumor in CUP Syndrome patients.Material and method41 patients referred to Poznan Medical University Department of Head and Neck Surgery from January 2010 to December 2013 with CUP Syndrome were included in the study. All patients presented fine-needle biopsy proven squamous cell carcinoma metastasis of the upper-, or mid neck lymph nodes. The final results were obtained from the histopathologic reports of tissue samples from anatomical regions suspected for primary tumor, additional imaging exams as well as clinical follow-up data.ResultsThe ¹⁸F-FDG-PET/CT successfully detected primary tumor in 7 out of 41 patients (17%). In two more cases the primary tumor was indicated in the lung. 24 of 41 patients (58.5%) analyzed in our study remained without evidence of a primary tumor. In 4 cases (9.75%) we did not reveal any pathology within the localizations indicated by PET/CT on panendoscopy. In 4 cases we obtained histological confirmation of neoplasm on panendoscopy despite the negative results of PET/CT examinations.ConclusionWe may suppose a relatively high usefulness of ¹⁸F-FDG-PET/CT in the diagnosis process of CUP Syndrome patients. High NPV may indicate patients with no symptoms of primary tumor, which allows to avoid extensive resection or extra imaging.