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The progress made in hybrid PET imaging during the past decades has significantly expanded the role of this modality in both clinical and research applications. Semi-quantitative PET/CT has been the workhorse of clinical PET/CT due to its simplicity and availability. In addition to semi-quantitative PET/CT, volumetric PET and global metabolic activity have recently shown promise in a more accurate assessment of various diseases. PET/CT has been widely used in pediatric oncologic and non-oncologic diseases. Here we have highlighted few of the pitfalls in the quantitative PET/CT and their potential remedies which have potential in PET/CT evaluation of pediatric diseases.

The aim of this study was to quantify subchondral bone remodeling in the elbows, hands, knees, and feet using volumetric and metabolic parameters derived from 18F-sodium fluoride positron emission tomography (NaF-PET) and to assess the convergent validity of these parameters as an index of joint degeneration and preclinical osteoarthritis. A retrospective analysis was conducted in 34 subjects (32 males, 2 females) with metastatic bone disease who underwent full-body NaF-PET/CT scans. An adaptive contrast-oriented thresholding algorithm was applied to segment NaF-avid regions in the bilateral elbows, hands, knees, and feet of each subject, and metabolically active volume (MAV), maximum standardized uptake value (SUVmax), mean metabolic volumetric product (MVPmean), and partial volume-corrected MVPmean (cMVPmean) of the segmented regions were calculated. Global parameters for MAV, SUVmax, MVPmean, and cMVPmean were defined as the sum of the corresponding values in all the joints of a subject. Inter-rater reliability was determined with Lin’s concordance correlation, and associations of global values with subject body weight and age were assessed with Pearson correlation and Spearman correlation analyses. Inter-rater reliability was observed to be the highest in SUVmax (ρc = 0.99), followed by MVPmean (ρc = 0.96), cMVPmean (ρc = 0.93), and MAV (ρc = 0.93). MAV, MVPmean, and cMVPmean were observed to significantly increase with weight (all p

The aim of this study was to quantify subchondral bone remodeling in the elbows, hands, knees, and feet using volumetric and metabolic parameters derived fromA retrospective analysis was conducted in 34 subjects (32 males, 2 females) with metastatic bone disease who underwent full-body NaF-PET/CT scans. An adaptive contrast-oriented thresholding algorithm was applied to segment NaF-avid regions in the bilateral elbows, hands, knees, and feet of each subject, and metabolically active volume (MAV), maximum standardized uptake value (SUVmax), mean metabolic volumetric product (MVPmean), and partial volume-corrected MVPmean (cMVPmean) of the segmented regions were calculated. Global parameters for MAV, SUVmax, MVPmean, and cMVPmean were defined as the sum of the corresponding values in all the joints of a subject. Inter-rater reliability was determined with Lin's concordance correlation, and associations of global values with subject body weight and age were assessed with Pearson correlation and Spearman correlation analyses.Inter-rater reliability was observed to be the highest in SUVmax (ρc = 0.99), followed by MVPmean (ρc = 0.96), cMVPmean (ρc = 0.93), and MAV (ρc = 0.93). MAV, MVPmean, and cMVPmean were observed to significantly increase with weight (all p 0.0001) determined by Pearson correlation. In addition, Spearman rank-order analysis demonstrated a significant correlation between SUVmax and weight in addition to MAV, MVPmean, and cMVPmean and weight (all p 0.01). No significant association between age and any PET parameter was observed.These preliminary data demonstrate the feasibility and reliability of assessing bone turnover at the joints using quantitative NaF-PET. Our findings corroborate the fact that biomechanical factors including mechanical loading and weight-bearing are contributors to osteoarthritis disease progression.

The early detection of atherosclerotic disease is vital to the effective prevention and management of life-threatening cardiovascular events such as myocardial infarctions and cerebrovascular accidents. Given the potential for positron emission tomography (PET) to visualize atherosclerosis earlier in the disease process than anatomic imaging modalities such as computed tomography (CT), this application of PET imaging has been the focus of intense scientific inquiry. Although 18F-FDG has historically been the most widely studied PET radiotracer in this domain, there is a growing body of evidence that 18F-NaF holds significant diagnostic and prognostic value as well. In this article, we review the existing literature on the application of 18F-FDG and 18F-NaF as PET probes in atherosclerosis and present the findings of original animal and human studies that have examined how well 18F-NaF uptake correlates with vascular calcification and cardiovascular risk.

In recent years, multiple studies have demonstrated the value of volumetric FDG-PET/CT parameters as independent prognostic factors in patients with non-small cell lung cancer (NSCLC). We aimed to determine the optimal cut-off points of pretreatment volumetric FDG-PET/CT parameters in predicting overall survival (OS) in patients with locally advanced NSCLC and to recommend imaging biomarkers appropriate for routine clinical applications. Patients with inoperable stage IIB/III NSCLC enrolled in ACRIN 6668/RTOG 0235 were included. Pretreatment FDG-PET scans were quantified using semiautomatic adaptive contrast-oriented thresholding and local-background partial-volume-effect-correction algorithms. For each patient, the following indices were measured: metabolic tumor volume (MTV), total lesion glycolysis (TLG), SUVmax, SUVmean, partial-volume-corrected TLG (pvcTLG), and pvcSUVmean for the whole-body, primary tumor, and regional lymph nodes. The association between each index and patient outcome was assessed using Cox proportional hazards regression. Optimal cut-off points were estimated using recursive binary partitioning in a conditional inference framework and used in Kaplan-Meier curves with log-rank testing. The discriminatory ability of each index was examined using time-dependent receiver operating characteristic (ROC) curves and corresponding area under the curve (AUC(t)). The study included 196 patients. Pretreatment whole-body and primary tumor MTV, TLG, and pvcTLG were independently prognostic of OS. Optimal cut-off points were 175.0, 270.9, and 35.5 cm3 for whole-body TLG, pvcTLG, and MTV, and were 168.2, 239.8, and 17.4 cm3 for primary tumor TLG, pvcTLG, and MTV, respectively. In time-dependent ROC analysis, AUC(t) for MTV and TLG were uniformly higher than that of SUV measures over all time points. Primary tumor and whole-body parameters demonstrated similar patterns of separation for those patients above versus below the optimal cut-off points in Kaplan-Meier curves and in time-dependent ROC analysis. We demonstrated that pretreatment whole-body and primary tumor volumetric FDG-PET/CT parameters, including MTV, TLG, and pvcTLG, are strongly prognostic for OS in patients with locally advanced NSCLC, and have similar discriminatory ability. Therefore, we believe that, after validation in future trials, the derived optimal cut-off points for primary tumor volumetric FDG-PET/CT parameters, or their more refined versions, could be incorporated into routine clinical practice, and may provide more accurate prognostication and staging based on tumor metabolic features.

Radiation pneumonitis is a major dose-limiting complication in thoracic radiation therapy (RT) and presents clinically in the first few months after RT. We evaluated the feasibility of quantifying pulmonary parenchymal glycolysis (PG) as a surrogate of global lung inflammation and radiation-induced pulmonary toxicity using a novel semiautomatic lung segmentation technique in non-small-cell lung cancer (NSCLC) patients and compared PG in patients treated with photon or proton RT.We evaluated 18 consecutive locally advanced NSCLC patients who underwent pretreatment and post-treatment F-FDG PET/CT treated with definitive (median: 66.6 Gy; 1.8 Gy fractions) photon or proton RT between 2010 and 2014. Lung volume segmentation was conducted using 3D Slicer by performing simple thresholding. Pulmonary PG was calculated by summing F-FDG uptake in the whole lung.In nine patients treated with photon RT, significant increases in PG in both ipsilateral (mean difference: 1400±510; P=0.02) and contralateral (mean difference: 1200±450; P=0.03) lungs were noted. In nine patients treated with proton therapy, no increase in pulmonary PG was observed in either the ipsilateral (P=0.30) or contralateral lung (P=0.98).We observed a significant increase in global lung inflammation bilaterally as measured by quantification of PG. However, no significant change in global lung inflammation was noted after proton therapy. Future larger studies are needed to determine whether this difference correlates with lower risks of radiation pneumonitis in NSCLC patients treated with proton therapy.

The gut microbiota impacts response to immunotherapy in cancer patients. We sought to evaluate the role of physiologic colonic fluorine-18-fluorodeoxyglucose (F-FDG) uptake, a test that was recently shown to reflect colonic bacterial load, as a possible predictor for response to immunotherapy. We carried out a retrospective study in metastatic melanoma patients who received the immune checkpoint inhibitor ipilimumab as first-line therapy. All patients underwent an F-FDG PET scan before treatment initiation. The primary outcome was defined as response to treatment according to the RECIST criteria. Regions of interest were drawn on each transaxial slice around the outer boundaries of the colon. Uptake was measured using maximum and mean standardized uptake value (SUV). A nonparametric test was used to compare SUV between response groups. The study included 14 melanoma patients, of whom two (14.3%) achieved a complete response (CR) following treatment, eight (57.1%) achieved a partial response (PR), and four (28.6%) developed progressive disease (PD). The mean SUVmax was 1.33±0.04, 2.2±0.46, and 3.33±2.67 for individuals with CR, PR, and PD, respectively. The difference between individuals with CR and those without CR (PR or PD) in total colonic SUVmax was statistically significant (P=0.03). Thus, physiologic colonic F-FDG uptake may predict CR to immunotherapy in metastatic melanoma patients.

Fluorodeoxyglucose-PET is increasingly being integrated into multiple aspects of oncology. PET/computed tomography (PET/CT) has become especially important in radiation oncology. With the increasing use of advanced techniques like intensity-modulated radiation therapy and proton therapy, PET/CT scans have played critical roles in the target delineation of tumors for radiation oncologists delivering conformal treatment techniques. Use of PET/CT is well established in lung cancer and several other thoracic malignancies. This article details the current uses of PET/CT in thoracic radiation oncology with a focus on lung cancer and describes expected future roles of PET/CT for thoracic tumors.

18F-sodium fluoride (NaF) as an imaging tracer portrays calcium metabolic activity either in the osseous structures or in soft tissue. Currently, clinical use of NaF-PET is confined to detecting metastasis to the bone, but this approach reveals indirect evidence for disease activity and will have limited use in the future in favor of more direct approaches that visualize cancer cells in the read marrow where they reside. This has proven to be the case with FDG-PET imaging in most cancers. However, a variety of studies support the application of NaF-PET to assess benign osseous diseases. In particular, bone turnover can be measured from NaF uptake to diagnose osteoporosis. Several studies have evaluated the efficacy of bisphosphonates and their lasting effects as treatment for osteoporosis using bone turnover measured by NaF-PET. Additionally, NaF uptake in vessels tracks calcification in the plaques at the molecular level, which is relevant to coronary artery disease. Also, NaF-PET imaging of diseased joints is able to project disease progression in osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis. Further studies suggest potential use of NaF-PET in domains such as back pain, osteosarcoma, stress-related fracture, and bisphosphonate-induced osteonecrosis of the jaw. The critical role of NaF-PET in disease detection and characterization of many musculoskeletal disorders has been clearly demonstrated in the literature, and these methods will become more widespread in the future. The data from PET imaging are quantitative in nature, and as such, it adds a major dimension to assessing disease activity.

The combination of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) and computed tomography (CT) for dual-modality imaging (PET/CT) plays a key role in the diagnosis and staging of FDG-avid malignancies. FDG uptake by the tumor cells offers an opportunity to detect cancer in organs that appear normal at anatomic imaging and to differentiate viable tumor from posttreatment effects. Quantification of FDG uptake has multiple clinical applications, including cancer diagnosis and staging. Dedicated FDG PET/CT-based visual and quantitative criteria have been developed to evaluate treatment response. Furthermore, the level of tumor FDG uptake reflects the biologic aggressiveness of the tumor, predicting the risk of metastasis and recurrence. FDG uptake can be measured with qualitative, semiquantitative, and quantitative methods. Qualitative or visual assessment of PET/CT images is the most common clinical approach for describing the level of FDG uptake. Standardized uptake value (SUV) is the most commonly used semiquantitative tool for measuring FDG uptake. SUV can be measured as maximum, mean, or peak SUV and may be normalized by using whole or lean body weight. SUV measurements provide the basis for quantitative response criteria; however, SUVs have not been widely adopted as diagnostic thresholds for discriminating malignant and benign lesions. Volumetric FDG uptake measurements such as metabolic tumor volume and total lesion glycolysis have shown substantial promise in providing accurate tumor assessment. SUV measurement and other quantification techniques can be affected by many technical, physical, and biologic factors. Familiarity with FDG uptake quantification approaches and their pitfalls is essential for clinical practice and research.

Positron emission tomography/computed tomography (PET/CT) is an important imaging tool for management of lung cancer and can be utilized in diagnosis, staging, restaging, treatment planning and evaluating treatment response. In the past decade PET/CT has proven to be beneficial for the prediction of prognosis and outcome. PET findings before and after treatment, the quantitative PET parameters such as standardized uptake value (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) as well as delayed PET/CT imaging can be used to determine patient prognosis and outcome. Other tracers such as hypoxia and proliferation marker tracers may be used for prognostication. The prognostic factors derived from PET/CT imaging help early development of risk-adapted treatment strategies, which provides cost-effective treatment and leads to improved patient management. Here, we discuss findings of studies related to application of PET/CT in lung cancer as well as some technical updates on quantitative PET/CT in lung cancer.

The authors make a complete review of the potential clinical applications of traditional and novel magnetic resonance imaging (MRI) techniques in the evaluation of patients with Alzheimer's disease, including structural MRI, functional MRI, diffusion tension imaging and magnetization transfer imaging. RESUMO Os autores fazem uma revisão complete das potenciais aplicações clínicas de técnicas tradicional e inovadoras de ressonância magnética na avaliação de pacientes com doença de Alzheimer, incluindo ressonância magnética estrutural, técnicas funcionais de ressonância magnética, técnica de "diffusion tensor imaging" e imagem de transferência magnética.

In this Part II review, as a complement to the Part I published in this supplement, the authors cover the imaging techniques that evaluates the Alzheimer's disease according to the different metabolic and molecular profiles. In this section MR spectroscopy, FDG-PET and amyloid PET are deeply discussed.Nesta revisão Parte II, como complemento da revisão Parte I publicada nesta edição, os autores descrevem as técnicas de imagem que avaliam a doença de Alzheimer de acordo com os diferentes perfis metabólicos e moleculares que caracterizam esta doença. Nesta seção são discutidos em profundidade a espectroscopia por ressonância magnética, FDG-PET and imagem com marcadores de peptide beta amilóide.

The advent of new neuroimaging modalites in recent decades, along with the increasing prevalence of neurological disorders and a rise in life expectancy over the past century, have collectvely led to the numerous studies trying to explain the anatomical and functonal changes in the human brain following the disease. Other investgators have atempted to fnd the differences in brain structures and functons following normal aging, since understanding age-related changes in the brain might be the frst step to shed light on the pathophysiology of various neurological disorders. In this review, we describe the existng and novel quanttatve approaches of functonal positron emission tomography (PET) imaging. Moreover, we describe novel volumetric studies assessing global and regional volume changes based on advanced computerised techniques of magnetc resonance (MR) analysis such as voxel-based morphometry (VBM) and non-conventonal MR techniques such as diffusion tensor imaging (DTI) and magnetzaton transfer imaging (MTI) followed by a brief review of arterial spin labeling (ASL) imaging.

One of the most important aspects of cancer treatment is radiation therapy, which is used for a wide range of malignancies. However, this treatment modality has side effects that impose the patient to increased risks of mortality and morbidity. Total dose, fraction size, and duration of radiation therapy are among the factors contributing to toxicities. In recent decades, fluorodeoxyglucose (FDG)-PET/computed tomography (CT) has been extensively used for diagnosis, prognostication, response to treatment assessment, and management of cancers and is currently a standard modality for many cancers. This article discusses the role of PET/CT, and especially FDG-PET/CT, in radiotherapy complications.

There is growing evidence showing the importance of fluorodeoxyglucose positron emission tomography (FDG-PET) in the evaluation of vessel wall inflammation and atherosclerosis. Although this imaging modality has been increasingly used, there are various methods for image acquisition and evaluating FDG uptake activity in the vessel walls and atherosclerotic lesions, including qualitative visual scaling, semi-quantitative, and quantitative evaluations. Using each of these image acquisition protocols and measurement methods may result in different findings. In this review, we are going to describe the various image acquisition methods and common measurement strategies reflected in the literature and discuss their advantages and flaws.

Since its foundation PET has established itself as one of the standard imaging modalities enabling the quantitative assessment of molecular targets in vivo. In the past two decades, quantitative PET has become a necessity in clinical oncology. Despite introduction of various measures for quantification and correction of PET parameters, there is debate on the selection of the appropriate methodology in specific diseases and conditions. In this review, we have focused on these techniques with special attention to topics such as static and dynamic whole body PET imaging, tracer kinetic modeling, global disease burden, texture analysis and radiomics, dual time point imaging and partial volume correction.

Dual time point imaging (DTPI) and delayed time point imaging have been used for the differentiation of inflammatory and malignant processes and found to enhance the specificity of FDG PET imaging for diagnostic and prognostic purposes. It has been shown that the degree of FDG uptake at the second acquisition time point after the baseline scan increases in malignant cells; in inflammatory or infectious disorders, on the other hand, FDG uptake decreases or remains unchanged at the second time point. Many groups have investigated the application of DTPI and its potential and limitations have been discussed in detail with reference to a wide variety of malignant diseases, including those of the lung. The aim of this review is to describe the role of DTPI to assess both normal and disease states.

This review article summarizes the role of PET/CT and PET/MRI in ovarian cancer. With regard to the diagnosis of ovarian cancer, the presence of FDG uptake within the ovary of a postmenopausal woman raises the concern for ovarian cancer. Multiple studies show that FDG PET/CT can detect lymph node and distant metastasis in ovarian cancer with high accuracy and may, therefore, alter the management to obtain better clinical outcomes. Although PET/CT staging is superior for N and M staging of ovarian cancer, its role is limited for T staging. Additionally, FDG PET/CT is of great benefit in evaluating treatment response and has prognostic value in patients with ovarian cancer. FDG PET/CT also has value to detect recurrent disease, particularly in patients with elevated serum CA-125 levels and negative or inconclusive conventional imaging test results. PET/MRI may beneficial for tumor staging because MRI has higher soft tissue contrast and no ionizing radiation exposure compared to CT. Some non-FDG PET radiotracers such as 18F-fluorothymidine (FLT) or 11C-methionine (MET) have been studied in preclinical and clinical studies as well and may play a role in the evaluation of patients with ovarian cancer.

Diaschisis denotes brain dysfunction remote from a focal brain lesion. We have quantified diaschisis and investigated its prognostic value in glioma. Methods: We compared 50 18F-FDG PET/CT studies collected prospectively from 14 patients with supratentorial glioma (5 men and 9 women; age range, 35-77 y) with 10 single scans from healthy controls (age range, 43-75 y). Dedicated 3-dimensional segmentation software was used to obtain total hemispheric glucose metabolic ratios (THGr) by dividing total hemispheric 18F-FDG uptake in each diaschitic hemisphere-that is, the ipsilateral cerebral hemisphere (THGr(Ce)) and the contralateral cerebellar hemisphere (THGr(Cb))-by its respective contralateral side. Receiver-operatingcharacteristic (ROC) analysis was performed to determine optimal cut-offs for combinations of THGr(Ce) and THGr(Cb). Two independent observers obtained data for reproducibility analysis, and THGr values were compared with qualitative assessment of diaschisis performed by a PET neuroimaging specialist. Results: Qualitative analysis confirmed cerebrocerebellar diaschisis in all glioblastoma PET studies performed within 1 y of death. Healthy subjects had significantly higher THGr(Ce) values (P = 0.0007) and THGr (Cb) values (P = 0.02) than glioblastoma patients. ROC analysis yielded diaschisis thresholds of 0.62 for THGr(Ce) and 0.84 for THGr (Cb). Qualitative assessment demonstrated cerebral diaschisis in 16 of 17 (94%) cases with THGr(Ce) below the determined threshold and cerebellar diaschisis in 25 of 26 (96%) cases with THGr(Cb) below the determined threshold. When both THGr(Ce) and THGr(Cb) were below the ROC threshold, the combined diaschisis measures had a positive predictive value for survival below 1 y of 100%. When one parameter was below the threshold, it had a positive predictive value of 75%, and when both parameters exceeded thresholds, the negative predictive value for survival above 1 y was 79%. Median interrater variability was 3.3% and 5.9% for THGr(Ce) and THGr(Cb), respectively. Conclusion: The THGr measures demonstrated diaschisis in the cerebrum and cerebellum of patients with glioma. Combined cerebrocerebellar diaschisis ratios with ROC thresholds for both forebrain and hindbrain had high negative and positive predictive values for survival for less than a year. The THGr method allows comparison of data obtained at different institutions and is now open for further validation in gliomas and other cerebral diseases.

In cervical cancer (CC), fluorine18-fluorodeoxyglucose (

The aim of this study was to develop a novel method of global quantitative analysis for use in the diagnosis and treatment evaluation of temporal lobe epilepsy (TLE). We studied 16 patients diagnosed with TLE who underwent fluorine-18 fluorodeoxyglucose-PET (F-FDG-PET) and MRI at the Hospital of the University of Pennsylvania. To quantify temporal lobe hypometabolism, we averaged the mean standardized uptake value across regions of interest (ROIs) encompassing each lobe in its entirety and calculated the metabolic ratios and lateralization indices for each patient on the basis of global measurements. For comparison, we carried out a traditional 'punch biopsy' ROI analysis by averaging the mean standardized uptake value within 1 cm diameter ROIs across select slices. Both techniques were performed twice by the same rater to test intraobserver variability. An expert observer carried out visual analyses of both F-FDG-PET and MRI for reference. The global quantitative analysis identified a seizure focus lateralization in agreement with clinical evaluations for 91% of patients on both trials, with intraclass correlation coefficients of 0.97 and 0.92 for metabolic ratios and lateralization indices, respectively. The punch biopsy analysis was in agreement for 91 and 82% of patients on respective trials, with intraclass correlation coefficients of 0.90 and 0.75. Expert visual analyses carried out on F-FDG-PET and MRI were in agreement for 64 and 9% of patients, respectively. The global quantitative analysis proved to be the most accurate and reliable of the methods tested. This technique has the potential to improve metabolic analysis in TLE and other neuropsychiatric disorders.

OBJECTIVE: The goal of this study was to quantify aging effects upon the global knee joint and surrounding capsule and soft tissue inflammation using fluorine-18 fluorodeoxyglucose (18F-FDG) PET imaging. METHODS: This reanalysis of a prospective study included 64 patients who had undergone 18F-FDG-PET for evaluation of hip joint prostheses, and whose scans included the knee joints in the field of view. Mean patient age was 53 years (range: 33-84 years). A fixed-sized three-dimensional region of interest was placed around each knee joint, paying close attention to exclude the popliteal vessels. 18F-FDG-avid regions in each knee joint were then segmented using an adaptive contrast-oriented thresholding method, and metabolically active volume (MAV), mean standardized uptake value (SUV mean), partial volume-corrected SUV mean (cSUV mean), and partial volume-corrected mean metabolic volumetric product (cMVP mean = cSUV mean × MAV) of the segmented regions were calculated. Finally, global knee inflammation (GKI) for each knee joint was calculated as the sum of cMVP mean in all segmented regions. Association of GKI with age was assessed with Pearson's correlation and linear regression methods, and GKI was compared between patients at different ages - between patients younger than 55 years and those older than 55 years - using the unpaired t-test. RESULTS: The correlation coefficient of GKI with advancing age was 0.57 (P = 0.02). In the linear regression model, considering GKI as the dependent variable and age and sex as independent covariates, the β coefficient of age was 2.1 (95% confidence interval: 1.1-3.2). For patients aged younger than 55 years versus those aged older than 55 years, the mean GKI was 157 and 190 cm3, respectively (P = 0.01). CONCLUSION: Through the use of novel quantitative techniques, we were able to calculate GKI and demonstrate a significant increase in the entity of joint inflammation with advancing age. As degenerative disease is age-related and inflammation is implicated in its pathogenesis, our findings further support this association. These preliminary data suggest that this approach can potentially provide a means to objectively quantify the degree of inflammation in various joint disorders, and possibly in other knee degenerative/inflammatory diseases.

Temporal lobe epilepsy (TLE) is a prevalent neurodegenerative disease associated with various neuropsychiatric disorders and decreased quality of life. Much has been said about the use of fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG-PET), magnetic resonance imaging (MRI), and computed tomography in the qualitative assessment of TLE. However, research into the applications of quantitative measurements to treat and diagnose TLE is severely lacking in the literature. Global quantitative analysis using 18F-FDG-PET is a powerful tool in the metabolic assessment of TLE, and can more accurately identify seizure lateralization and the potential effects of treatment as compared with visual assessments and traditional biopsy region-of-interest quantification. Therefore, there is a pressing need to introduce these novel methods to the treatment of TLE. Although 18F-FDG-PET is most commonly used for visual assessments, qualitative analysis is associated with high levels of interobserver and intraobserver variability. Semiquantitative analysis using standardized uptake value is a more consistently accurate measure of the hypometabolic patterns seen in TLE patients. Novel methods of global quantitative analysis developed in our laboratory have the potential to improve TLE assessment by limiting variability and correcting for the partial volume effect. It is of great importance to adopt these techniques into the mainstream diagnosis and treatment of TLE in order to improve patient care worldwide.

Purpose: To compare the potential of five functional magnetic resonance imaging (fMRI) language paradigms in activating language areas in Persian-speaking volunteers in order to optimize these tasks for clinically useful protocol. Materials and Methods: 16 healthy right-handed Persian-speaking volunteers were studied. Each individual performed five tasks during the fMRI scan: word generation (WG), object naming (ON), word reading (WR), word production (WP), and reverse word reading (RWR). The ability of each task to activate classical language areas was assessed using group analysis. In addition, the lateralization index (LI) for each subject-task was calculated and compared. Results: We found that WP, RWR, and WG robustly activated language-related areas in the dominant hemisphere. ON and WR failed to sufficiently delineate these activation areas. Highest activation intensities in the frontal lobe (including Broca's area) were seen with WP, whereas RWR showed the highest LI among all examined tasks. Conclusion: Our results demonstrated that the Persian version of WG and newly presented WP and RWR tasks can be reliably used for localization of language-related areas in Persian speakers. This type of language evaluation may be used in presurgical planning of neurosurgical procedures in the Persian population. We recommend application of WP and RWR in future researches establishing the optimized protocol for other language speakers. J. Magn. Reson. Imaging 2011;. © 2011 Wiley-Liss, Inc.

Background and Aim: Neuroimaging techniques in audiovisual speech processing are innovative approach to neuroscience investigation that steadily influences the deep survey of highly mechanisms involved in this process. The purpose of this study was to evaluate brain activity via functional magnetic resonance imaging throughout audiovisual speech perception in Persian language.Methods: Functional MRI was used to assess 19 normal 20-30 year old women while they had been presented syllable /ka/ visually and /pa/ auditory using block design method, in which it would provide two series of imaging, functional and T1-weighted. Subsequently, the results were analyzed and compared by FSL software.Results: The results of this study pointed out that both middle and cortical regions of brain are activated in visual stimuli and its middle regions are activated in response to auditory stimuli. Hence, left anterior supramarginal, some parts of motor speech system including insular and cingulate cortex-precentral cortex were stimulated with visual stimulus and left posterior supramarginal as well as right supramarginal gyrus were stimulated with auditory stimulus. Moreover, in this investigation, McGurk effect was behaviorally proven in fifteen subjects.Conclusion: It was hypothesized that the activation of unique region, supramarginal gyrus, with both audio and visual stimuli indicated the presence of commonplace region for phonologic processing of sensory inputs. In addition, auditory stimuli develop more intense activity; and on the other hand, broaden-maximum voxel-as well as extra regions are demonstrated in response to visual stimuli. These points represent the unfamiliarity of normal individual brain to percept visual speech stimuli.

Recent data comparing germ-free to conventionally-raised mice demonstrated that energy homeostasis of colonocytes is dependent on gut microbiota through regulation of short chain fatty acids (SCFA) production and glucose utilization. We sought to evaluate 18F-FDG PET-CT as a novel technique for functional imaging of alterations in glucose metabolism as a result of the interaction between the gut microbiota and the human host. We conducted a prospective study in healthy humans that underwent 18F-FDG PET-CT and sampling of the gut microbiota before and after orally administered broad-spectrum antibiotics. The primary outcomes were total and regional physiologic colonic 18F-FDG uptake (measured as the mean and max standardized uptake values [SUVmean and SUVmax]). The study demonstrated significant increases in physiologic colonic 18F-FDG uptake in all study participants following antibiotic treatment and a 4-5log reduction of gut bacterial load. The mean increase in SUVmax was 0.63±0.37 SD (p = 0.004) and the median increase was 0.42 with an IQR of 0.40-0.81. The mean increase in SUVmean was 0.31±0.24 SD (p = 0.01) and the median increase was 0.41 with an IQR of 0.06-0.55. A likely explanation for this phenomenon is a shift in colonocyte metabolism to glycolysis due to a shortage of SCFA.

Purpose The human arterial wall is smaller than the spatial resolution of current positron emission tomographs. Therefore, partial volume effects should be considered when quantifying arterial wall F-18-FDG uptake. We evaluated the impact of a novel method for partial volume effect (PVE) correction with contrast-enhanced CT (CECT) assistance on quantification of arterial wall F-18-FDG uptake at different imaging time-points.Methods Ten subjects were assessed by CECT imaging and dual time-point PET/CT imaging at approximately 60 and 180 min after F-18-FDG administration. For both time-points, uptake of F-18-FDG was determined in the aortic wall by calculating the blood pool-corrected maximum standardized uptake value (cSUV(MAX)) and cSUV(MEAN). The PVE-corrected SUVMEAN (pvcSUV(MEAN)) was also calculated using F-18-FDG PET/CT and CECT images. Finally, corresponding target-to-background ratios (TBR) were calculated.Results At 60 min, pvcSUV(MEAN) was on average 3.1 times greater than cSUV(MAX) (P Conclusion This study demonstrated that CECT-assisted PVE correction significantly influences quantification of arterial wall F-18-FDG uptake. Therefore, partial volume effects should be considered when quantifying arterial wall F-18-FDG uptake with PET.

18F-NaF uptake has been investigated as an in vivo biomarker of coronary artery calcification (CAC) in humans. CAC increases risk of fatal cardiac events in coronary artery disease (CAD) patients, ...

Treatment of malignant pleural mesothelioma (MPM) remains very challenging. Assessment of response to treatment is necessary for modifying treatment and using new drugs. Global disease assessment (GDA) by implementing image processing methods to extract more information out of positron emission tomography (PET) images may provide reliable information. In this study we show the feasibility of this method of semi-quantification in patients with mesothelioma, and compare it with the conventional methods. We also present a review of the literature about this topic.Nineteen subjects with histologically proven MPM who had undergone fluoride-18-fluorodeoxyglucose PET/computed tomography ((18)F-FDG PET/CT) before and after treatment were included in this study. An adaptive contrast-oriented thresholding algorithm was used for the image analysis and semi-quantification. Metabolic tumor volume (MTV), maximum and mean standardized uptake volume (SUVmax, SUVmean) and total lesion glycolysis (TLG) were calculated for each region of interest. The global tumor glycolysis (GTG) was obtained by summing up all TLG. Treatment response was assessed by the European Organisation for Research and Treatment of Cancer (EORTC) criteria and the changes of GTG. Agreement between global disease assessment and conventional method was also determined.In patients with progressive disease based on EORTC criteria, GTG showed an increase of 150.7 but in patients with stable or partial response, GTG showed a decrease of 433.1. The SUVmax of patients before treatment was 5.95 (SD: 2.93) and after the treatment it increased to 6.38 (SD: 3.19). Overall concordance of conventional method with GDA method was 57%. Concordance of progression of disease based on conventional method was 44%, stable disease was 85% and partial response was 33%. Discordance was 55%, 14% and 66%.Adaptive contrast-oriented thresholding algorithm is a promising method to quantify the whole tumor glycolysis in patients with mesothelioma. We are able to assess the total metabolic lesion volume, lesion glycolysis, SUVmax, tumor SUVmean and GTG for this particular tumor. Also we were able to demonstrate the potential use of this technique in the monitoring of treatment response. More studies comparing this technique with conventional and other global disease assessment methods are needed in order to clarify its role in the assessment of treatment response and prognosis of these patients.

Studies to date have focused on 18F-sodium fluoride (18F-NaF) uptake in advanced lesions of coronary artery disease (CAD) patients [(1)][1]. However, others suggest that 18F-NaF soft-tissue uptake imaged by positron-emission tomography (PET) may occur in coronary arteries before the advanced stages

The aim of this study is to assess a software-based method with semiautomated correction for partial volume effect (PVE) to quantify the metabolic activity of pulmonary malignancies in patients who underwent non-gated and respiratory-gated 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG)-positron emission tomography (PET)/x-ray computed tomography(CT).The study included 106 lesions of 55 lung cancer patients who underwent respiratory-gated FDG-PET/CT for radiation therapy treatment planning. Volumetric PET/CT parameters were determined by using 4D PET/CT and non-gated PET/CT images. We used a semiautomated program employing an adaptive contrast-oriented thresholding algorithm for lesion delineation as well as a lesion-based partial volume effect correction algorithm. We compared respiratory-gated parameters with non-gated parameters by using pairwise comparison and interclass correlation coefficient assessment. In a multivariable regression analysis, we also examined factors, which can affect quantification accuracy, including the size of lesion and the location of tumor.This study showed that quantification of volumetric parameters of 4D PET/CT images using an adaptive contrast-oriented thresholding algorithm and 3D lesion-based partial volume correction is feasible. We observed slight increase in FDG uptake by using PET/CT volumetric parameters in comparison of highest respiratory-gated values with non-gated values. After correction for partial volume effect, the mean standardized uptake value (SUVmean) and total lesion glycolysis (TLG) increased substantially (p value0.001). However, we did not observe a clinically significant difference between partial volume corrected parameters of respiratory-gated and non-gated PET/CT scans. Regression analysis showed that tumor volume was the main predictor of quantification inaccuracy caused by partial volume effect.Based on this study, assessment of volumetric PET/CT parameters and partial volume effect correction for accurate quantification of lung malignant lesions by using respiratory non-gated PET images are feasible and it is comparable to gated measurements. Partial volume correction increased both the respiratory-gated and non-gated values significantly and appears to be the dominant source of quantification error of lung lesions.

Venous thromboembolism (VTE) mostly presenting as deep venous thrombosis (DVT) and pulmonary embolism (PE) affects up to 600,000 individuals in United States each year. Clinical symptoms of VTE are nonspecific and sometimes misleading. Additionally, side effects of available treatment plans for DVT are significant. Therefore, medical imaging plays a crucial role in proper diagnosis and avoidance from over/under diagnosis, which exposes the patient to risk. In addition to conventional structural imaging modalities, such as ultrasonography and computed tomography, molecular imaging with different tracers have been studied for diagnosis of DVT. In this review we will discuss currently available and newly evolving targets and tracers for detection of DVT using molecular imaging methods.