F-fluoro-2-deoxy-D-glucose Research Articles

Dapagliflozin improves myocardial flow reserve in patients with type 2 diabetes: the DAPAHEART Trial: a preliminary report

ObjectiveCardiovascular (CV) outcome trials have shown that in patients with type 2 diabetes (T2D), treatment with sodium-glucose cotransporter-2 inhibitors (SGLT-2i) reduces CV mortality and hospital admission rates for heart failure (HF). However, the mechanisms behind these benefits are not fully understood. This study was performed to investigate the effects of the SGLT-2i dapagliflozin on myocardial perfusion and glucose metabolism in patients with T2D and stable coronary artery disease (coronary stenosis ≥ 30% and < 80%), with or without previous percutaneous coronary intervention (> 6 months) but no HF.MethodsThis was a single-center, prospective, randomized, double-blind, controlled clinical trial including 16 patients with T2D randomized to SGLT-2i dapagliflozin (10 mg daily) or placebo. The primary outcome was to detect changes in myocardial glucose uptake (MGU) from baseline to 4 weeks after treatment initiation by [(18)F]2-deoxy-2-fluoro-D-glucose (FDG) PET/CT during hyperinsulinemic euglycemic clamp. The main secondary outcome was to assess whether the hypothetical changes in MGU were associated with changes in myocardial blood flow (MBF) and myocardial flow reserve (MFR) measured by 13N-ammonia PET/CT. The study was registered at eudract.ema.europa.eu (EudraCT No. 2016-003614-27) and ClinicalTrials.gov (NCT 03313752).Results16 patients were randomized to dapagliflozin (n = 8) or placebo (n = 8). The groups were well-matched for baseline characteristics (age, diabetes duration, HbA1c, renal and heart function). There was no significant change in MGU during euglycemic hyperinsulinemic clamp in the dapagliflozin group (2.22 ± 0.59 vs 1.92 ± 0.42 μmol/100 g/min, p = 0.41) compared with the placebo group (2.00 ± 0.55 vs 1.60 ± 0.45 μmol/100 g/min, p = 0.5). Dapagliflozin significantly improved MFR (2.56 ± 0.26 vs 3.59 ± 0.35 p = 0.006 compared with the placebo group 2.34 ± 0.21 vs 2.38 ± 0.24 p = 0.81; pint = 0.001) associated with a reduction in resting MBF corrected for cardiac workload (p = 0.005; pint = 0.045). A trend toward an increase in stress MBF was also detected (p = 0.054).ConclusionsSGLT-2 inhibition increases MFR in T2D patients. We provide new insight into SGLT-2i CV benefits, as our data show that patients on SGLT-2i are more resistant to the detrimental effects of obstructive coronary atherosclerosis due to increased MFR, probably caused by an improvement in coronary microvascular dysfunction.Trial registration EudraCT No. 2016-003614-27; ClinicalTrials.gov Identifier: NCT03313752

PET-CT in Clinical Adult Oncology—IV. Gynecologic and Genitourinary Malignancies

Concurrently acquired positron emission tomography and computed tomography (PET-CT) is an advanced imaging modality with diverse oncologic applications, including staging, therapeutic assessment, restaging and longitudinal surveillance. This series of six review articles focuses on providing practical information to providers and imaging professionals regarding the best use and interpretative strategies of PET-CT for oncologic indications in adult patients. In this fourth article of the series, the more common gynecological and adult genitourinary malignancies encountered in clinical practice are addressed, with an emphasis on Food and Drug Administration (FDA)-approved and clinically available radiopharmaceuticals. The advent of new FDA-approved radiopharmaceuticals for prostate cancer imaging has revolutionized PET-CT imaging in this important disease, and these are addressed in this report. However, [18F]F-fluoro-2-deoxy-d-glucose (FDG) remains the mainstay for PET-CT imaging of gynecologic and many other genitourinary malignancies. This information will serve as a guide for the appropriate role of PET-CT in the clinical management of gynecologic and genitourinary cancer patients for health care professionals caring for adult cancer patients. It also addresses the nuances and provides guidance in the accurate interpretation of FDG PET-CT in gynecological and genitourinary malignancies for imaging providers, including radiologists, nuclear medicine physicians and their trainees.

Method to determine the statistical technical variability of SUV metrics

BackgroundThe Standardized Uptake Value (SUV) Max, SUVMean, and SUVPeak are metrics used to quantify positron emission tomography (PET) images. In order to assess the significance of a change in these metrics for diagnostic purposes, it is relevant to know their variation. The sources of variation can be biological or technical. In this study, we present a method to determine the statistical technical variation of SUV in PET images.ResultsThis method was tested on a NEMA quality phantom with spheres of various diameters with a full-length acquisition time of 150 s per bed position and foreground-to-background activity ratio of F18-2-fluoro-2-deoxy-d-glucose (FDG) of 10:1. Our method divides the 150 s acquisition into subsets with statistically independent frames of shorter reconstruction length. SUVMax, Mean and Peak were calculated for each reconstructed image in a subset. The coefficient of variation of SUV within each subset has been used to estimate the expected coefficient of variation at 150 s reconstruction length. We report the largest coefficient of variation of the SUV metrics for the smallest sphere and the smallest variation for the largest sphere. The expected variation at 150 s reconstruction length does not exceed 6% for the smallest sphere and 2% for the largest sphere.ConclusionsWith the presented method, we aim to determine the statistical technical variation of SUV. The method enables the evaluation of the effect of SUV metric choice (Max, Mean, Peak) and lesion size on the technical variation and, therefore, to evaluate its relevance on the total variation of the SUV value between clinical studies.

FDG Uptakes at Unilateral Axillary and Supraclavicular Lymph Nodes and Deltoid Muscle on [18F] FDG PET/CT After COVID-19 Vaccination: A Potential Pitfall for Metastatic Lymph Nodes in Colon Cancer Patient

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the ongoing global pandemic. It can manifest a wide range of complications depending upon the severity of infection and comorbidities of the patient. Vaccines are very important measure to provide protection against COVID-19. We report a case of 73-year-old female who underwent [&lt;sup&gt;18&lt;/sup&gt;F]F-2-fluoro-2-deoxyd-glucose (FDG) positron emission tomography/computed tomography (PET/CT) and contrast-enhanced CT for staging of her rectosigmoid colon cancer and was found to have hypermetabolic uptakes in the deltoid muscle of the left shoulder and hypermetabolic left axillary and supraclavicular lymph nodes due to adenovirus vectored vaccine (ChAdOx1 nCoV-19, AstraZeneca) administrated 18 days ago prior to PET/CT scan.

Diagnostic classification of solitary pulmonary nodules using support vector machine model based on 2-[18F]fluoro-2-deoxy-D-glucose PET/computed tomography texture features

This study aimed to evaluate the diagnostic value of a support vector machine (SVM) model built with texture features based on standard 2-[F]fluoro-2-deoxy-D-glucose (F-FDG) PET in patients with solitary pulmonary nodules (SPNs) at a volume larger than 5 mL. The PET results of 82 patients diagnosed with SPNs between 2014 and 2018 were retrospectively analysed. The volumes of interest (VOIs) of the SPNs were automatically segmented using threshold techniques from the standard PET imaging. Then, a large number of texture features were extracted from the VOIs using texture-analysis software. Next, an optimized SVM machine-learning model that was trained on standard PET images using texture features was employed to identify the optimal discrimination between malignant and benign nodules. Diagnostic models based on the maximum standardized uptake value (SUVmax) and the metabolic tumour volume (MTV) were compared with the SVM model with regard to the SPN diagnostic power. Compared with the SUVmax and MTV models, the texture-based SVM model provided an improvement of approximately 20% in diagnostic accuracy, positive predictive value, negative predictive value and the area under the operating characteristic curve. The receiver operating characteristic curve of the SVM model showed a significant improvement compared with the MTV model (P = 0.0345 < 0.05) and the SUVmax model (P = 0.01 < 0.05). Standard F-FDG PET imaging can increase the differentiation of benign and malignant SPNs with volumes larger than 5 mL using an SVM model based on texture features.

Clinicopathologic parameters associated with the FDG-avidity in staging of early gastric cancer using 18F-FDG PET.

This study investigated the clinicopathologic factors associated with 2-[18F]fluoro-2-deoxy-d-glucose (18F-FDG) uptake of early gastric cancer (EGC) and used them to design a clinical scoring method to predict FDG-avidity of EGC.Two hundred twenty-nine retrospectively enrolled patients underwent preoperative 18F-FDG positron emission tomography/computed tomography (PET/CT). Histologic information was obtained by gastrectomy (n = 195) or endoscopic mucosal dissection (n = 34). The association between clinicopathologic factors and 18F-FDG uptake by the primary tumor was determined. The results were used to develop a clinical scoring method.18F-FDG uptake was detected in 49 (17.5%) patients. According to univariate analysis, location, gross type, World Health Organization classification, Lauren classification, size, depth of invasion, and lymphatic invasion were significant variables affecting 18F-FDG uptake (all P < .05). According to multivariate analysis, location (lower 3rd, P = .035), gross type (0–I, 0–IIa, P < .001), size (≥2.5 cm, P = .026), and depth of invasion (submucosa, P = .007) were significantly associated with FDG-avidity. A clinical scoring system, ranged from 0 to 4, was developed by giving one score to 4 independent variables. A cut-off value of 2.5 showed good prediction of FDG-avidity in EGCs, with a sensitivity and specificity of 65.0% and 85.2%, respectively.18F-FDG uptake by EGC depends on location, gross type, size, and depth of invasion of the primary tumor. A clinical scoring system based on clinicopathologic variables can predict the FDG-avidity of primary tumors in patients with EGC.

FDG-PET/CT for Detecting an Infection Focus in Patients With Bloodstream Infection: Factors Affecting Diagnostic Yield.

To investigate the diagnostic performance of F-fluoro-2-deoxy-D-glucose (FDG) PET/ CT for the detection of an infection focus in patients with a bloodstream infection (BSI) and to identify factors influencing the diagnostic yield of FDG-PET/CT. This retrospective single-center study included 185 consecutive patients with a BSI who underwent an FDG-PET/CT scan for the detection of an infection focus between 2010 and 2017. The final diagnosis at hospital discharge was used as reference standard. Diagnostic performance of FDG-PET/CT for the detection of an infection focus was assessed, and logistic regression analyses were performed to identify factors associated with FDG-PET/CT yield. An infection focus was identified on FDG-PET/CT in 120 (64.8%) of 185 patients. FDG-PET/CT achieved a sensitivity of 80.2%, specificity of 79.6%, positive predictive value of 90.8%, and a negative predictive value of 61.4% for detecting an infection focus in patients with a BSI. Blood cultures positive for enterococci (odds ratio, 0.14; P = 0.019) and days of antibiotic treatment before FDG-PET/CT (odds ratio, 0.94 per day increase; P = 0.014) were statistically significant independent predictors of a lower odds of detecting an infection focus on FDG-PET/CT. In patients who received antibiotics for less than 7 days before FDG-PET/CT, an infection focus was found in 71% (56/79). In patients who received antibiotics for 8 to 14 days before FDG-PET/CT, an infection focus was found in 52% (22/42). After 15 to 21 days of antibiotic treatment, an infection focus was found in 61% (8/13), and for 22 days or more, this declined to 38% (5/13). FDG-PET/CT is a useful method for detecting an infection focus in patients with BSI. However, longer duration of antibiotic treatment before FDG-PET/CT and bacteremia with enterococci reduce the diagnostic yield of FDG-PET/CT. These factors should be taken into account when considering an FDG-PET/CT scan for this indication.

Variations of the liver standardized uptake value in relation to background blood metabolism: An 2-[18F]Fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography study in a large population from China.

To investigate the influence of background blood metabolism on liver uptake of 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG) and search for an appropriate corrective method.Positron emission tomography/computed tomography (PET/CT) and common serological biochemical tests of 633 healthy people were collected retrospectively. The mean standardized uptake value (SUV) of the liver, liver artery, and portal vein (i.e., SUVL, SUVA, and SUVP) were measured. SUVL/A was calculated as SUVL/SUVA, while SUVL/P was calculated as SUVL/SUVP. SUV of liver parenchyma (SUVLP) was calculated as SUVL − .3 × (.75 × SUVP + .25 × SUVA). The coefficients of variation (CV) of SUVL, SUVL/A, SUVL/P, and SUVLP were compared to assess their interindividual variations. Univariate and multivariate analyses were performed to identify vulnerabilities of these SUV indexes to common factors assessed using serological liver functional tests.SUVLP was significantly larger than SUVL (2.19 ± .497 vs 1.88 ± .495, P < .001), while SUVL/P was significantly smaller than SUVL (1.72 ± .454 vs 1.88 ± .495, P < .001). The difference between SUVL/A and SUVL was not significant (1.83 ± .500 vs 1.88 ± .495, P = .130). The CV of SUVLP (22.7%) was significantly smaller than that of SUVL (22.7%:26.3%, P < .001), while the CVs of SUVL/A (27.2%) and SUVL/P (26.4%) were not different from that of SUVL (P = .429 and .929, respectively). Fewer variables independently influenced SUVLP than influenced SUVL, SUVL/A, and SUVL/P; Only aspartate aminotransferase, body mass index, and total cholesterol, all P-values <.05.The activity of background blood influences the variation of liver SUV. SUVLP might be an alternative corrective method to reduce this influence, as its interindividual variation and vulnerability to effects from common factors of serological liver functional tests are relatively lower than the commonly used SUVL.

Clinical relevance of 18F-FDG PET/CT lower-limb imaging in patients with malignant cutaneous melanoma.

The aim of this study was to assess the clinical relevance of imaging the lower limbs when using 2-(F)-fluoro-2-deoxy-D-glucose (F-FDG) positron emission tomography with computed tomography (PET/CT) for malignant cutaneous melanoma in patients without previously known or suspected primary or metastatic melanoma lesions in the lower limbs. We retrospectively assessed 880 consecutive F-FDG PET/CT scans performed for adult patients in a context of suspected melanoma spanning a period of 5 years. All scans were correlated with the associated patient records (clinical history, physical examinations, and pathology reports), as well as follow-up imaging examinations, up until at least 6 months after the end of the study. Among the 461 whole-body scans included for analysis, 109 reported unusual activity in the lower limbs, but with at most 21 scans showing lower-limb lesions attributed to melanoma on follow-up. No scan showed melanoma lesions exclusively in the lower limbs, and in no case did imaging the lower limbs upstage a patient. Imaging the lower limbs changed the actual clinical management of the melanoma for only one patient, with precautionary local radiation therapy administered following the detection of an asymptomatic distal femur bone metastasis in an otherwise plurimetastatic patient headed for palliative care. Our study, the largest of its kind, confirms that, when using F-FDG PET/CT for staging, restaging, or surveillance of malignant cutaneous melanoma in patients without previously known or suspected lower-limb melanoma lesions, imaging the lower extremities offers little additional clinically relevant information and stopping the scan at the proximal thighs has essentially no clinical impact.

F-18 FDG PET/CT imaging of cardiac and vascular inflammation and infection.

Inflammation forms an important core of the aetiopathogenic process involved in many diseases affecting the heart and the blood vessels. These diseases include infections as well as inflammatory non-infectious cardiovascular conditions. The common feature of this is invasion of the heart or blood vessel by inflammatory cells. F-18 2-fluoro 2-deoxy-D glucose (FDG) is an analogue of glucose and like glucose it is taken up by activated inflammatory cells that accumulate at the site of infection. This has formed the basis of the use of F-18 FDG PET/CT in the non-invasive evaluation of human inflammatory diseases. This review is based on the published academic articles as well as our clinical experience. F-18 FDG PET/CT is a useful imaging modality in the evaluation of cardiovascular inflammatory disorders. Accumulation and distribution of F-18 FDG at the site of inflammation/infection corresponds to severity of the inflammation/infection and extent of involvement. Most studies evaluating utility of F-18 FDG PET/CT in imaging cardiovascular inflammation are small observational studies hence are potentially prone to bias. Being a hybrid metabolic and morphologic imaging technique, F-18 FDG PET/CT offers combined advantage of complementary anatomic and metabolic information in disease process. This makes it a useful modality in the diagnosis, determination of extent of disease, prognostication as well as treatment monitoring. Larger prospective studies are needed to validate the superiority of F-18 FDG PET/CT imaging over conventional anatomic imaging modalities.

Cerebral Glucose Metabolism and Dopaminergic Function in Patients with Corticobasal Syndrome.

The corticobasal syndrome (CBS) is a clinical diagnosis that comprises a group of rare neurodegenerative diseases manifesting in movement disorder and cognitive impairment. While diagnosis is based upon clinical criteria, there have been a number of molecular imaging studies, albeit in rather small cohorts. Therefore, we investigated the pattern of cerebral glucose metabolism, as well as dopamine transporter (DAT) availability in a large and clinically well-defined cohort. Thirty-four patients fulfilling either the Armstrong or the Boeve criteria were assessed with [18 F]-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) and/or [123 I]-Ioflupane single-photon-emission-computed tomography (SPECT) for DAT availability. A small subset of patients had also undergone D2/3 receptor imaging. Imaging data were analyzed using both statistical parametric mapping and a volume-of-interest-based approach relative to data from healthy controls. Significant reductions of the cortical glucose metabolism were observed in the central region and the adjacent frontal and parietal association areas contralateral to the side with predominant motor symptoms. Reductions were also evident in the basal ganglia, notably in the putamen contralateral to the clinically affected side, and in the bilateral thalamus. DAT availability was reduced bilaterally, most distinctly on the side contralateral to the main motor symptoms. We replicated and refined earlier findings of impaired glucose metabolism and nigrostriatal degeneration in CBS, highlighting asymmetric cortical and subcortical hypometabolism, symmetrically reduced metabolism in the thalamus, and only a slightly asymmetric reduction in DAT, while D2/3 receptors seem to be mainly preserved. These results provide systematic evidence for the usefulness of FDG PET and dopaminergic SPECT imaging to characterize CBS.

The Effect of Endogenous Adenosine on Neuronal Activity in Rats: An FDG PET Study

ABSTRACT2–18F‐fluorodeoxy‐D‐glucose (FDG) is a glucose analog that is taken up by cells and phosphorylated. The amount of FDG accumulated by cells is a measure of the rate of glycolysis, which reflects cellular activity. As the levels and actions of the neuromodulator adenosine are dynamically regulated by neuronal activity, this study was designed to test whether endogenous adenosine affects tissue accumulation of FDG as assessed by positron emission tomography (PET) or by postmortem analysis of tissue radioactivity. Rats were given an intraperitoneal injection of the adenosine A1 receptor antagonist 8‐cyclopentyl‐1,3‐dipropyl‐xanthine (DPCPX, 3 mg/kg), the adenosine kinase inhibitor ABT‐702 (3 mg/kg), or vehicle 10 minutes prior to an intravenous injection of FDG (15.4 ± 0.7 MBq per rat). Rats were then subjected to a 15 minute static PET scan. Reconstructed images were normalized to FDG PET template for rats and standard uptake values (SUVs) were calculated. To examine the regional effect of active treatment compared to vehicle, statistical parametric mapping analysis was performed. Whole‐brain FDG uptake was not affected by drug treatment. Significant regional hypometabolism was detected, particularly in cerebellum, of DPCPX‐ and ABT‐702 treated rats, relative to vehicle‐treated rats. Thus, endogenous adenosine can affect FDG accumulation although this effect is modest in quiescent rats.

Molecular imaging as a tool to investigate heterogeneity of advanced HER2-positive breast cancer and to predict patient outcome under trastuzumab emtansine (T-DM1): the ZEPHIR trial

Only human epidermal growth factor receptor (HER)2 status determined by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) has been validated to predict efficacy of HER2-targeting antibody-drug-conjugate trastuzumab emtansine (T-DM1). We propose molecular imaging to explore intra-/interpatient heterogeneity in HER2 mapping of metastatic disease and to identify patients unlikely to benefit from T-DM1. HER2-positive mBC patients with IHC3+ or FISH ≥ 2.2 scheduled for T-DM1 underwent a pretreatment HER2-positron emission tomography (PET)/computed tomography (CT) with (89)Zr-trastuzumab. [(18)F]2-fluoro-2-deoxy-D-glucose (FDG)-PET/CT was performed at baseline and before T-DM1 cycle 2. Patients were grouped into four HER2-PET/CT patterns according to the proportion of FDG-avid tumor load showing relevant (89)Zr-trastuzumab uptake (>blood pool activity): patterns A and B were considered positive (>50% or all of the tumor load 'positive'); patterns C and D were considered negative (>50% or all of the tumor load 'negative'). Early FDG-PET/CT was defined as nonresponding when >50% of the tumor load showed no significant reduction of FDG uptake (<15%). Negative (NPV) and positive predictive values (PPV) of HER2-PET/CT, early FDG response and their combination were assessed to predict morphological response (RECIST 1.1) after three T-DM1 cycles and time-to-treatment failure (TTF). In the 56 patients analyzed, 29% had negative HER2-PET/CT while intrapatient heterogeneity (patterns B and C) was found in 46% of patients. Compared with RECIST1.1, respective NPV/PPV for HER2-PET/CT were 88%/72% and 83%/96% for early FDG-PET/CT. Combining HER2-PET/CT and FDG-PET/CT accurately predicted morphological response (PPV and NPV: 100%) and discriminated patients with a median TTF of only 2.8 months [n = 12, 95% confidence interval (CI) 1.4-7.6] from those with a TTF of 15 months (n = 25, 95% CI 9.7-not calculable). Pretreatment imaging of HER2 targeting, combined with early metabolic response assessment holds great promise for improving the understanding of tumor heterogeneity in mBC and for selecting patients who will/will not benefit from T-DM1. NCT01565200.

Increased 18F-FDG uptake suggests synovial inflammatory reaction with osteoarthritis: preliminary in-vivo results in humans.

The aim of this prospective study was to compare the metabolic activity of the knee joints of a group of patients with painful knees clinically (such as recurrent joint pain, joint instability, and functional limitations) consistent with osteoarthritis and those of another group of patients without such complaints, using [F]-2-fluoro-2-deoxy-D-glucose (F-FDG)-PET imaging. A total of 97 patients who participated in either painful joint prosthesis or diabetic foot research studies involving F-FDG-PET scans were asked to complete a knee pain questionnaire. The patients were asked whether they experienced pain in any joint, and if so, which joints were affected. A total of 18 knee joints without prosthesis were reported to be painful. The maximum standardized uptake values (SUVmax) of the middle joint space and lateral synovial tissue of these 18 knees were measured and compared with those of a set of patients with control asymptomatic knees. The average SUVmax of the middle part of the joint space in the painful knees was 1.35±0.59 compared with an average SUVmax value of 0.86±0.14 in the control group (P=0.0176). The average SUVmax of the synovium in the lateral part of the painful joints was 1.17±0.49 compared with 0.73±0.31 in the control group (P=0.0161). These data indicate that increased F-FDG uptake is associated with knee pain in osteoarthritis patients and that there is a positive relationship between the two parameters.

Involvement of Subcortical Brain Structures During Olfactory Stimulation in Multiple Chemical Sensitivity.

Multiple chemical sensitivity (MCS) patients usually react to odour compounds and the majority of neuroimaging studies assessed, especially at the cortical level, many olfactory-related correlates. The purpose of the present study was to depict sub-cortical metabolic changes during a neutral (NC) and pure (OC) olfactory stimulation by using a recently validated (18)F-2-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography/computer tomography procedure in 26 MCS and 11 healthy (HC) resting subjects undergoing a battery of clinical tests. Twelve subcortical volumes of interest were identified by the automated anatomical labeling library and normalized to thalamus FDG uptake. In both groups, when comparing OC to NC, the within-subjects ANOVA demonstrated a relative decreased metabolism in bilateral putamen and hippocampus and a relative increased metabolism in bilateral amygdala, olfactory cortex (OLF), caudate and pallidum. The between-groups ANOVA demonstrated in MCS a significant higher metabolism in bilateral OLF during NC. As in HC subjects negative correlations were found in OC between FDG uptake in bilateral amygdala and hippocampus and odor pleasantness scale, the latter positively correlated with MCS subjects' bilateral putamen FDG uptake in OC. Besides FDG uptake resemblances in both groups were found, for the first time a relative higher metabolism increase in OLF in MCS subjects at rest with respect to HC was found. When merging this aspect to the different subcortical FDG uptake correlations patterns in the two groups, the present study demonstrated to describe a peculiar metabolic index of behavioral and neurological aspects of MCS complaints.

Presence of macronodules in thoracic sarcoidosis: prevalence and computed tomographic findings

To assess the prevalence and radiological findings of macronodules in patients with thoracic sarcoidosis. Data was collected regarding 226 patients with pathologically proven thoracic sarcoidosis. Among them, macronodules defined as well-defined nodules greater than 5 mm were found in 58 patients. The macronodules were evaluated by their number, size, margin, shape, lobar location, distance from the pleura, and temporal change. Patients were classified into two groups, patients with macronodules (n = 58) and without macronodules (n = 168). The level of serum angiotensin-converting enzyme (ACE), systemic involvement, and the maximum standardized uptake value (maxSUV) on (18)F-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) in both groups were then compared. A total of 216 macronodules were identified in 58 patients. The mean number of macronodules per patient was 3.3, and the mean size was 6.3 mm. Most of the macronodules were located in lower lobes (63.4%) and showed round-to-ovoid (95.8%) shape. The mean distance from the pleura was 5 mm. In 76% of the 63 nodules that were followed using CT scanning, any interval changes in size was also accompanied by the same change in mediastinal lymphadenopathy. On comparison of the two groups, the presence of lymphadenopathy, parenchymal involvement, and the maxSUV of thoracic lymphadenopathy were shown to be statistically different. Well-defined macronodules greater than 5 mm were not uncommonly seen in patients with thoracic sarcoidosis. The macronodules are usually located in the lower lobes near the pleura, and the interval changes in mediastinal lymphadenopathy may be associated with similar changes in the size of nodules.

Patient doses from PET-CT procedures.

Positron emission tomography (PET) was installed for the first time in Bulgaria in 2009, and nowadays two hybrid PET-computed tomography (CT) systems are in operation. The aim of this work is to estimate patient doses from PET-CT procedures and to explore potential for optimisation. Data were retrospectively collected for 50 patients examined with the system Philips Gemini TF and for 58 patients examined with the system GE Discovery 600. Whole-body examinations with radiopharmaceutical (18)F-2-fluoro-2-deoxy-D-glucose (FDG) were performed on all patients. Patient effective doses from the CT component of the examination were calculated with CT Expo software and compared with doses estimated applying the National Radiological Protection Board (NRPB) conversion coefficients. Effective doses from the PET component were calculated applying the ICRP 80 conversion coefficients. For the first system, average effective doses from CT component were 8.0 and 8.9 mSv, applying CT Expo and NRPB coefficients, respectively, and 4.9 mSv from PET component. For the second system, the corresponding values were 7.8, 8.7 and 5.9 mSv. These results for patient effective doses are relatively lower or comparable to other similar surveys. Reasons for the observed differences are analysed and presented.

Diffusely increased bone marrow FDG uptake in recently untreated lymphoma: incidence and relevance

To determine the incidence of diffusely increased bone marrow (18) F-fluoro-2-deoxy-D-glucose (FDG) uptake at positron emission tomography (PET) in recently untreated lymphoma and to assess the frequency of lymphoma-positive bone marrow biopsies (BMBs) in these patients. FDG-PET scans of all patients presenting with newly diagnosed or relapsed lymphoma were reviewed. Patients with non-focal diffusely increased bone marrow FDG uptake, who had not received therapy within 3months, were identified. The incidences of diffusely increased bone marrow FDG uptake and the frequencies of positive posterior iliac crest BMBs among those cases were calculated. The incidences of diffusely increased bone marrow FDG uptake in all lymphomas, and in Hodgkin lymphoma, aggressive non-Hodgkin lymphoma (NHL), indolent NHL, and mantle cell NHL separately, were 4.2% (23/542), 9.3% (7/75), 3.4% (8/239), 3.3% (7/214), and 7.1% (1/14), respectively, and frequencies of positive BMBs among these subgroups were 55.0% (11/20), 0.0% (0/7), 83.3% (5/6), 83.3% (5/6), and 100% (1/1), respectively. The incidence of diffusely increased bone marrow FDG uptake in recently untreated lymphoma is low, albeit higher in Hodgkin lymphoma than in NHL. BMB in such patients is likely to be negative in Hodgkin lymphoma, but positive in the majority of NHL cases.

Predictive Efficacy of Interim Positron Emission Tomography/Computed Tomography (PET/CT) for the Treatment of Aggressive Lymphoma.

The prognostic value of whole-body positron emission tomography/computed tomography (PET/CT) with 18F-fluoro-2-deoxy-D-glucose (FDG) shortly after the onset of induction chemotherapy or mid treatment could help to predict long-term clinical outcomes in patients with Hodgkin's or Non-Hodgkin's lymphoma. However, FDG is not a tumor-specific substance, and it may accumulate to the point of being detected in a variety of benign conditions or at physiologic anatomical sites, which may give rise to false-positive interpretation. In an attempt to standardize the reporting criteria for interim PET/CT, the First International Workshop on Interim PET in Lymphoma suggested visual response criteria with the Deauville five-point scale, and the standardized uptake value (SUV) has been investigated in comparison with this visual system. A quantitative approach using the measurement of maximal SUV (SUVmax) or the reduction rate of SUVmax (ΔSUVmax) might be more appropriate in early-response PET/CT for reducing false-positive rates or for decreasing interobserver variability in interpretation. In this review, the predictive efficacy of PET/CT is discussed for the treatment of aggressive lymphoma, especially in terms of an interim PET/CT-based prognostic model.

Synthesis and preliminary biological evaluation of S-11C-methyl-D-cysteine as a new amino acid PET tracer for cancer imaging.

S-(11)C-methyl-L-cysteine (LMCYS) is an attractive amino acid tracer for clinical tumor positron emission tomography (PET) imaging. D-isomers of some radiolabeled amino acids are potential PET tracers for tumor imaging. In this work, S-(11)C-methyl-D-cysteine (DMCYS), a D-amino acid isomer of S-(11)C-methyl-cysteine for tumor imaging was developed and evaluated. DMCYS was prepared by (11)C-methylation of the precursor D-cysteine, with an uncorrected radiochemical yield over 50% from (11)CH3I within a total synthesis time from (11)CO2 about 12min. In vitro competitive inhibition studies showed that DMCYS uptake was primarily transported through the Na(+)-independent system L, and also the Na(+)-dependent system B(0,+) and system ASC, with almost no system A. In vitro incorporation experiments indicated that almost no protein incorporation was found in Hepa 1-6 hepatoma cell lines. Biodistribution studies demonstrated higher uptake of DMCYS in pancreas and liver at 5min post-injection, relatively lower uptake in brain and muscle, and faster radioactivity clearance from most tissues than those of L-isomer during the entire observation time. In the PET imaging of S180 fibrosarcoma-bearing mice and turpentine-induced inflammatory model mice, 2-(18)F-fluoro-2-deoxy-D-glucose (FDG) exhibited significantly high accumulation in both tumor and inflammatory lesion with low tumor-to-inflammation ratio of 1.40, and LMCYS showed low tumor-to-inflammation ratio of 1.64 at 60min post-injection. By contrast, DMCYS showed moderate accumulation in tumor and very low uptake in inflammatory lesion, leading to relatively higher tumor-to-inflammation ratio of 2.25 than (11)C-methyl-L-methionine (MET) (1.85) at 60min post-injection. Also, PET images of orthotopic transplanted glioma models demonstrated that low uptake of DMCYS in normal brain tissue and high uptake in brain glioma tissue were observed. The results suggest that DMCYS is a little better than the corresponding L-isomers as a potential PET tumor-detecting agent and is superior to MET and FDG in the differentiation of tumor from inflammation.