Fluorodeoxyglucose Positron Emission Tomography Uptake Research Articles

280O Pharmacokinetics and pharmacodynamics of paxalisib in newly diagnosed glioblastoma patients with unmethylated MGMT promoter status: Final phase II study results

Paxalisib is being developed for the treatment of glioblastoma multiforme (GBM). Post hoc analysis of phase 1 fluorodeoxyglucose-positron emission tomography (FDG-PET) scans suggested that paxalisib crosses the blood-brain barrier with a uniform distribution throughout the brain. The recently completed phase 2 trial (NCT03522298) enrolled patients with newly diagnosed GBM with unmethylated MGMT promoter status following surgical resection and chemotherapy (Stupp Regimen). Study outcomes comprised maximum tolerated dose (MTD), safety, preliminary efficacy, pharmacokinetics (PK) at the MTD under fed and fasted conditions and change in FDG-PET uptake in patients with measurable disease. Patients (n=30; 70.0% males, mean age 58.5 years) received between 1 and 29 treatment cycles. At the MTD (60 mg/day), paxalisib prolonged median progression free survival (8.4 months [RANO], 8.6 months [mRANO]) and improved median overall survival (15.7 months). Paxalisib was steadily absorbed (median Tmax 2.5 and 4 hours postdose) and declined with a mean elimination half-life ranging from 20.2 to 29.0 hours. Mean half-life (20.2 to 29.0 hours) was similar across dose levels and under fed and fasted conditions. Systemic exposure to paxalisib appeared slightly higher for the 60 mg fed status compared to 60 mg fasted status. Comparison of fed versus fasted treatment was statistically significant for Cmax at the 90% level (geometric least squares mean ratios: AUC0-last 1.33, AUC0-inf 1.06, and Cmax 1.52). Ten patients underwent FDG-PET imaging, 8 (80%) had a decrease in FDG uptake on Day 3 and/or Day 7 in Cycle 1 and 4 (40%) had a metabolic partial response. PK parameters were consistent with prior clinical experience and there was no evidence of a deviation from dose-proportionality. At the MTD FDG-PET data provide evidence that paxalisib has the ability to exert biological effect in tumour tissue, irrespective of fed or fasted status. Further evaluation is ongoing in GBM AGILE (NCT03970447).

Fluorodeoxyglucose-positron emission tomography (FDG-PET) of carotid arteries and non-alcoholic fatty liver disease (NAFLD): An analytical cross-sectional study from a teaching hospital, Kerala, South India.

Evidence related to carotid artery F-fluorodeoxyglucose-positron emission tomography (FDG -PET) and non-alcoholic fatty liver disease (NAFLD) is limited from a low-resource setting. The present study aims to examine the association between FDG-PET uptakes by the carotid arteries in patients having different grades of NAFLD. An analytical cross-sectional study was done in a tertiary care center in South India for 1 year. Sonographically confirmed NAFLD patients of the age group 18 years and above were consecutively enrolled for the study after getting informed consent. Anthropometric measurements, ultrasonography for identifying the grades of fatty liver and FDG-PET were performed in the study participants. The data for the study were collected by the research personnel and entered in Microsoft Excel. The data were analyzed in the IBM SPSS version 20.0 software. A total of 24 patients were in the final analysis. The mean age of patients in this study was 56.79 (11.26) years. Among the 24 patients, 95.83% (n = 23) were males. The mean FDG-PET uptake in the carotids was 1.75 (0.42) units. The FDG uptake was higher in the moderate NAFLD group (1.46 [0.40] v/s 2.04 [0.14]) and the difference was statistically significant with P < 0.001. The FDG uptake between the coronary artery disease (CAD) with NAFLD and non CAD with NAFLD groups was not statistically significant (1.60 [0.46] v/s 1.86 [0.36], P = 0.17). The FDG uptake in CAD patients with mild and moderate NAFLD had no statistical significance between the two groups (1.43 [0.45] v/s 2.00 [0.00], P= 0.06). The findings of this study showed increased uptake of FDG-PET in carotids in subjects with moderate fatty liver when compared with those with mild fatty liver.

EP004 - Intra-individual comparison of prostate specific membrane antigen and fluorodeoxyglucose positron emission tomography uptake patterns in men with prostate cancer

EP004 - Intra-individual comparison of prostate specific membrane antigen and fluorodeoxyglucose positron emission tomography uptake patterns in men with prostate cancer

Incidence and Clinical Impact of Inflammatory Fluorodeoxyglucose Positron Emission Tomography Uptake After Neoadjuvant Pembrolizumab in Patients with Organ-confined Bladder Cancer Undergoing Radical Cystectomy

BackgroundData regarding the incidence and prognostic impact of immune-related imaging changes, assessed by 18[F] fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scan, in patients receiving immune-checkpoint inhibitors (ICIs) are lacking. We relied on the population of patients enrolled in the PURE-01 study to evaluate such changes. ObjectiveTo evaluate the role of PET/CT to visualize the immune-related adverse events (irAEs) following pembrolizumab. Design, setting, and participantsFrom February 2017 to August 2019, in 103 patients with nonmetastatic, clinical T2–4aN0M0 bladder cancer, PET/CT scan was performed before and after neoadjuvant pembrolizumab (N = 206 scans), before radical cystectomy. InterventionPET/CT before and after neoadjuvant pembrolizumab, before radical cystectomy. Outcome measurements and statistical analysisWe analyzed the occurrence of irAEs, evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0, against the development of inflammatory FDG uptake described at PET/CT (irAEs + PET/CT). Logistic regression analyses evaluated the association between irAEs + PET/CT and the pathological response to pembrolizumab. Kaplan-Meier curves tested their association with progression-free survival (PFS) after pembrolizumab and radical cystectomy. Results and limitationsForty patients (39%) developed irAEs + PET/CT in several target organs. The most frequent target organs were the thyroid (N = 18), stomach (N = 14), mediastinal lymph nodes (N = 9), and lung (N = 5). These changes were clinically evident in 18 (45%) and were not associated with the pathological response, neither in terms of complete response (ypT0N0, p = 0.07) nor as downstaging to ypT≤1N0 disease (p = 0.1), although ypT0N0 responses were numerically more frequent in patients with irAEs+ PET/CT (47.5% vs 32%). Furthermore, irAE+ PET/CT events were associated with longer, not statistically significant, 24-mo PFS: 88.3% versus 76.5% (p = 0.5). Our results warrant further validation in larger datasets. ConclusionsWe presented unique surrogate data of PET/CT that could help improve our understanding of nonclinically evident effects of ICI administration, especially in patients at the early disease stage. Patient summaryWe evaluated the utility of PET/CT to visualize the occurrence of inflammatory changes after pembrolizumab in patients with localized bladder cancer without metastases. After immunotherapy, 39% of the patients developed 18[F] fluorodeoxyglucose uptake consistent of inflammatory changes. Overall, our data improve our knowledge on the effects induced by immunotherapy, which may have a clinical impact at longer follow-up.Take Home Message● In the PURE-01 study, T2–4N0M0 muscle-invasive bladder cancer patients were staged with fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) before and after pembrolizumab.● PET/CT after pembrolizumab revealed inflammatory FDG uptake in 39% of patients, but only 45% of these cases of uptake corresponded to clinically evident adverse events.● The development of inflammatory uptake was associated with a higher pathological complete response rate and longer progression-free survival, although these differences were not statistically significant.

Correlation analysis of [18F]fluorodeoxyglucose and [18F]fluoroazomycin arabinoside uptake distributions in lung tumours during radiation therapy

Background: PET-guided dose painting (DP) aims to target radioresistant tumour regions in order to improve radiotherapy (RT) outcome. Besides the well-known [18F]fluorodeoxyglucose (FDG), the hypoxia positron emission tomography (PET) tracer [18F]fluoroazomycin arabinoside (FAZA) could provide further useful information to guide the radiation dose prescription. In this study, we compare the spatial distributions of FDG and FAZA PET uptakes in lung tumours.Material and methods: Fourteen patients with unresectable lung cancer underwent FDG and FAZA 4D-PET/CT on consecutive days at three time-points: prior to RT (pre), and during the second (w2), and the third (w3) weeks of RT. All PET/CT were reconstructed in their time-averaged midposition (MidP). The metabolic tumour volume (MTV: FDG standardised uptake value (SUV) > 50% SUVmax), and the hypoxic volume (HV: FAZA SUV > 1.4) were delineated within the gross tumour volume (GTVCT). FDG and FAZA intratumoral PET uptake distributions were subsequently pairwise compared, using both volume-, and voxel-based analyses.Results: Volume-based analysis showed large overlap between MTV and HV: median overlapping fraction was 0.90, 0.94 and 0.94, at the pre, w2 and w3 time-points, respectively. Voxel-wise analysis between FDG and FAZA intratumoral PET uptake distributions showed high correlation: median Spearman’s rank correlation coefficient was 0.76, 0.77 and 0.76, at the pre, w2 and w3 time-points, respectively. Interestingly, tumours with high FAZA uptake tended to show more similarity between FDG and FAZA intratumoral uptake distributions than those with low FAZA uptake.Conclusions: In unresectable lung carcinomas, FDG and FAZA PET uptake distributions displayed unexpectedly strong similarity, despite the distinct pathways targeted by these tracers. Hypoxia PET with FAZA brought very little added value over FDG from the perspective of DP in this population.

Evolution of [18F]fluorodeoxyglucose and [18F]fluoroazomycin arabinoside PET uptake distributions in lung tumours during radiation therapy

Background: Dose painting (DP) aims to improve radiation therapy (RT) outcome by targeting radioresistant tumour regions identified through functional imaging, e.g., positron emission tomography (PET). Importantly, the expected benefit of DP relies on the ability of PET imaging to identify tumour areas which could be consistently targeted throughout the treatment. In this study, we analysed the spatial stability of two potential DP targets in lung cancer patients undergoing RT: the tumour burden surrogate [18F]fluorodeoxyglucose (FDG) and the hypoxia surrogate [18F]fluoroazomycin arabinoside (FAZA).Materials and methods: Thirteen patients with unresectable lung tumours underwent FDG and FAZA 4D-PET/CT before (pre), and during the second (w2) and third (w3) weeks of RT. All PET/CT were reconstructed in their time-averaged midposition (MidP) for further analysis. The metabolic tumour volume (MTV: FDG standardised uptake value (SUV) > 50% SUVmax) and the hypoxic volume (HV: FAZA SUV >1.4) were delineated within the gross tumour volume (GTVCT). The stability of FDG and FAZA PET uptake distributions during RT was subsequently assessed through volume-overlap analysis and voxel-based correlation analysis.Results: The volume-overlap analysis yielded median overlapping fraction (OF) of 0.86 between MTVpre and MTVw2 and 0.82 between MTVpre and MTVw3. In patients with a detectable HV, median OF was 0.82 between HVpre and HVw2 and 0.90 between HVpre and HVw3. The voxel-based correlation analysis yielded median Spearman’s correlation coefficient (rS) of 0.87 between FDGpre and FDGw2 and 0.83 between FDGpre and FDGw3. Median rS was 0.78 between FAZApre and FAZAw2 and 0.79 between FAZApre and FAZAw3.Conclusions: FDG and FAZA PET uptake distributions were spatially stable during the 3 first weeks of RT in patients with unresectable lung cancer, both based on volume- and voxel-based indicators. This might allow for a consistent targeting of high FDG or FAZA PET uptake regions as part of a DP strategy.

Baseline F-18 FDG PET uptake of bone marrow as a survival predictor in patients with multiple myeloma

Positron emission tomography (PET) is a useful modality to diagnose multiple myeloma (MM) and assume its outcomes. Problems with Standardized Uptake Value based approaches are inter-device variations and required specific software to measure. We investigated the availability of direct visual assessment of bone marrow (BM) fluorine 18 fluorodeoxyglucose (FDG) uptakes in MM as a survival predictor.

Correlation of fine-needle aspiration with fluorodeoxyglucose positron emission tomography and ultrasonography imaging in head and neck lymph nodes

Fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established tracer technique, particularly useful for oncologic conditions. However, in the head and neck region, this modality may have limitations due to the complex anatomy and high frequency of normal variants in FDG-PET uptake resulting in diagnostic errors. Hence, FDG-PET results often require additional diagnostic investigations including ultrasonography (US), and guided fine-needle aspirations (FNAs) in order to improve diagnosis and patient care. A total of 87 cases of head and neck lymph node FNA were accessioned in the cytopathology laboratory between 2010 and 2013, 75 cases with corresponding standard uptake values (SUVs) were selected to form the current study cohort. Patient demographics, primary tumor site, size of the biopsied lymph node, PET SUV, and US findings, as well as FNA diagnoses and surgical follow-ups were reviewed. SUVs were grouped into 5 ranges: A (2.2-2.9), B (3.0-4.9), C (5.0-6.9), D (7.0-9.9), and E (10.0 +). The SUV cutoff of 5.0 was seen in the groups C, D, and E, which increased the probability of malignancy in the FNA specimens from 67% to 100%. The average size of the lymph nodes was 18.57 mm (range 6-41 mm); it was 13.4, 14.2, 19.7, 18.4, and 20.2 for groups A, B, C, D, and E, respectively. The lymph node measurements represented similarities in groups A and B (13.4, 14.2), and groups C, D, and E (19.7, 18.4, 20.2). Albeit a few exceptions, an increase in the lymph node size 14.2 to 19.7 (ie, from groups A and B to groups C, D, and E) correlated with SUV and US abnormalities. Abnormal US findings were pronounced (100%) in group E, and ranged between 67% and 73% of the cases in other groups. This study documents the usefulness of SUV range in FDG-PET results and not an absolute "cutoff" number for diagnosing suspicious head and neck lymph nodes due to an overlap in the SUVs between malignant and benign lesions. False positive and negative results may occur in hyperplastic and necrotic lymph nodes. An increase in the lymph node size generally compares well with SUVs and US abnormalities; use of US-guided FNAs in these cases can be helpful to achieve definite diagnosis.

Cerebellar metabolic involvement and its correlations with clinical parameters in vestibular neuritis.

Although vestibular neuritis (VN) cortical models are described in the literature, there is lack of knowledge regarding the exclusive cerebellar involvement. The aim of the present study was to analyze, by [18F] fluorodeoxyglucose-positron emission tomography (FDG-PET)/computer tomography, regional cerebellar FDG uptake in eight right-handed VN patients (five females; three males; mean age 48 ± 7 years) during the first few days (PET0) and after 1 month (PET1) since symptoms onset. At both phases, patients underwent otoneurological examination and filled in a battery of validated questionnaires. Twenty-six cerebellar volumes of interest (VOI) were identified by the automated anatomical labeling library and normalized to thalamus FDG-PET uptake. Mean intensity within VOIs was calculated in both phases and processed by within-subjects ANOVA. A significantly lower (p < 0.005) FDG uptake distribution was found in bilateral lobules III, VI and X and in vermis 1-2, 3, 6 and 10 at PET0 as compared to PET1 and a significant higher FDG uptake distribution was found in right crus I in the same comparison. Significant (p < 0.05) positive correlations were found between Anxiety and Bucket test scores, and normalized metabolism in right crus I (at PET0) and vermis 10 (at PET1), respectively. A negative correlation was found at PET0 between slow-phase velocity scores and normalized metabolism in right lobule X. These data show relevant changes in the pattern of cerebellar metabolism that might unravel additional central aspects of early and late VN associated to bilateral cortical responses to sensory conflict during the acute VN-related controversial inflow.

Modeling the relationship between fluorodeoxyglucose uptake and tumor radioresistance as a function of the tumor microenvironment.

High fluorodeoxyglucose positron emission tomography (FDG-PET) uptake in tumors has often been correlated with increasing local failure and shorter overall survival, but the radiobiological mechanisms of this uptake are unclear. We explore the relationship between FDG-PET uptake and tumor radioresistance using a mechanistic model that considers cellular status as a function of microenvironmental conditions, including proliferating cells with access to oxygen and glucose, metabolically active cells with access to glucose but not oxygen, and severely hypoxic cells that are starving. However, it is unclear what the precise uptake levels of glucose should be for cells that receive oxygen and glucose versus cells that only receive glucose. Different potential FDG uptake profiles, as a function of the microenvironment, were simulated. Predicted tumor doses for 50% control (TD50) in 2 Gy fractions were estimated for each assumed uptake profile and for various possible cell mixtures. The results support the hypothesis of an increased avidity of FDG for cells in the intermediate stress state (those receiving glucose but not oxygen) compared to well-oxygenated (and proliferating) cells.

FDG PET Uptake as a Predictor of Pain Response in Palliative Radiation Therapy in Patients with Bone Metastasis

Purpose To evaluate the relationship between fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) maximum standardized uptake value (SUVmax) and pain response to radiation therapy (RT) in patients with bone metastasis. Materials and Methods Institutional ethical board approval for the study was obtained, with informed consent, for this prospective study. Thirty-one patients with metastatic bone pain who underwent FDG PET/computed tomography before RT were included. Patients were diagnosed with lung (n = 16), breast (n = 7), stomach (n = 2), and head and neck cancers (n = 3), as well as unknown primary tumor (n = 3). Eighty-five painful metastatic locations with FDG PET scans geographically corresponding to 40 treatment fields were evaluated. Pain scores using visual analog scale or faces pain rating scale and SUVmax at each location were recorded. All patients were treated with a single fraction 8 Gy RT. Pain scores after RT were assessed at weeks 2, 4, 8, 12, 16, 20, and 24. The pretreatment pain scores and pain response to RT were compared with FDG PET SUVmax of each location. Pearson correlation, independent t test, one-way analysis of variance, and χ2 tests were used for statistical analysis. Results Median SUVmax and initial pain scores for all locations were 7.2 (range, 1.5–22.5) and 6 (range, 2–8), respectively. Median follow-up time was 24 (range, 3–112) weeks. Median SUVmax was 4.5 (range, 3.1–7.3), 4.75 (range, 1.5–10.3), 8.8 (range, 5.2–11.9), and 12.1 (range, 7–22.5) for pretreatment pain scores of 2, 4, 6, and 8, respectively. SUVmax was correlated with pretreatment pain scores (P < .0001). SUVmax and pretreatment pain scores were also significantly associated with pain response to RT. Median SUVmax for locations with complete response, partial response, pain progression, and indeterminate response was 5.2, 9.75, 10.8, and 6.4, respectively (P ≤ .001). Conclusion FDG PET SUVmax correlated with initial pain severity and pain response to RT and can be used as a predictive factor for treatment response in patients with painful bone metastasis treated with palliative RT. © RSNA, 2013

FDG PET Uptake as a Predictor of Pain Response in Palliative Radiation Therapy in Patients with Bone Metastasis

To evaluate the relationship between fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) maximum standardized uptake value (SUV(max)) and pain response to radiation therapy (RT) in patients with bone metastasis. Institutional ethical board approval for the study was obtained, with informed consent, for this prospective study. Thirty-one patients with metastatic bone pain who underwent FDG PET/computed tomography before RT were included. Patients were diagnosed with lung (n = 16), breast (n = 7), stomach (n = 2), and head and neck cancers (n = 3), as well as unknown primary tumor (n = 3). Eighty-five painful metastatic locations with FDG PET scans geographically corresponding to 40 treatment fields were evaluated. Pain scores using visual analog scale or faces pain rating scale and SUV(max) at each location were recorded. All patients were treated with a single fraction 8 Gy RT. Pain scores after RT were assessed at weeks 2, 4, 8, 12, 16, 20, and 24. The pretreatment pain scores and pain response to RT were compared with FDG PET SUV(max) of each location. Pearson correlation, independent t test, one-way analysis of variance, and χ(2) tests were used for statistical analysis. Median SUV(max) and initial pain scores for all locations were 7.2 (range, 1.5-22.5) and 6 (range, 2-8), respectively. Median follow-up time was 24 (range, 3-112) weeks. Median SUV(max) was 4.5 (range, 3.1-7.3), 4.75 (range, 1.5-10.3), 8.8 (range, 5.2-11.9), and 12.1 (range, 7-22.5) for pretreatment pain scores of 2, 4, 6, and 8, respectively. SUV(max) was correlated with pretreatment pain scores (P < .0001). SUV(max) and pretreatment pain scores were also significantly associated with pain response to RT. Median SUV(max) for locations with complete response, partial response, pain progression, and indeterminate response was 5.2, 9.75, 10.8, and 6.4, respectively (P ≤ .001). FDG PET SUV(max) correlated with initial pain severity and pain response to RT and can be used as a predictive factor for treatment response in patients with painful bone metastasis treated with palliative RT.

Effect of Cognitive Reserve Markers on Alzheimer Pathologic Progression

Education, occupation, premorbid intelligence, and brain size are surrogate markers for cognitive reserve. Whether these markers have biological influence on Alzheimer disease (AD) pathology is not known. We thus aimed to investigate the effect of cognitive reserve proxies on longitudinal change of AD biomarkers. A total of 819 participants with normal cognition, mild cognitive impairment, and mild AD were enrolled in the Alzheimer's Disease Neuroimaging Initiative and followed up with repeated measures of cerebrospinal fluid, positron emission tomography, and magnetic resonance imaging biomarkers. Generalized estimating equations were used to assess whether biomarker rates of change were modified by reserve proxies. Cerebrospinal fluid Aβ42 decline was slower in normal cognition participants with higher cognitive reserve indexed by education, occupation, and American National Adult Reading Test (ANART). The decline of [F] fluorodeoxyglucose positron emission tomography uptake was slower in AD participants with better performance on the ANART. Education, occupation, and ANART did not modify the rates of magnetic resonance imaging hippocampal atrophy in any group. These findings remained unchanged after accounting for APOE 4, longitudinal missing data, and baseline cognitive performance. Higher levels of reserve markers may slow the rate of amyloid deposition before cognitive impairment and preserve glucose metabolism at the dementia stage over the course of AD pathologic progression.

Uncommon Reason for High Fluorodeoxyglucose Positron Emission Tomography Uptake

Uncommon Reason for High Fluorodeoxyglucose Positron Emission Tomography Uptake

Preclinical Evaluation of Nilotinib Efficacy in an Imatinib-Resistant KIT-Driven Tumor Model

The novel KIT inhibitor nilotinib is currently being evaluated for its clinical utility in the treatment of gastrointestinal stromal tumor. However, the effects of nilotinib in cells expressing commonly occurring KIT mutations remain to be fully defined. The aim of this study was therefore to investigate the efficacy of nilotinib against cells expressing imatinib-sensitive or imatinib-resistant KIT mutations and to evaluate [(18)F] fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging as a biomarker of nilotinib response in vivo. Nilotinib inhibited the proliferation of imatinib-responsive V560G-KIT FDC-P1 and imatinib-resistant D816V-KIT FDC-P1 cells with a GI(50) of 4.9 and 630 nmol/L, respectively, whereas apoptosis studies revealed that nilotinib and imatinib were equipotent against the V560G cell line. In contrast, although 10 micromol/L nilotinib induced >50% apoptosis in the D816V cells at 16 hours, 10 micromol/L imatinib had no effect on cell survival at 24 hours. Syngeneic DBA2/J mice bearing FDC-P1-KIT tumors were evaluated for response to nilotinib by FDG-PET. V560G-KIT FDC-P1 tumor FDG uptake was significantly reduced compared with baseline levels following 2 days of nilotinib treatment. In contrast, no effect of nilotinib was observed on tumor growth or FDG-PET uptake into D816V tumors despite intratumoral drug levels reaching in excess of 10 micromol/L at 4 hours after dosing. Biomarker analysis revealed the inhibition of KIT phosphorylation in V560G but not D816V tumors. These findings show the in vivo activity of nilotinib in the treatment of tumors bearing V560G-KIT but not D816V-KIT and the utility of FDG-PET imaging to assess tumor response to this agent.

18FDG PET and Ultrasound Echolucency in Carotid Artery Plaques

The objective was to evaluate inflammation in echolucent carotid artery plaques. Ultrasound echolucency of carotid artery plaques has been proven to differentiate patients at high risk of stroke. On the other hand, positron emission tomography (PET) of plaques with the use of [(18)F]-fluorodeoxyglucose (FDG) identifies highly inflamed plaques, and the combination of molecular imaging and morphology could improve identification of vulnerable plaques. A total of 33 patients with cerebrovascular symptoms and carotid artery plaques were included prospectively for ultrasound and PET imaging. Plaque standardized gray scale medians (GSM) were measured in longitudinal ultrasound images to quantitate echolucency, and GSM values were compared with FDG PET uptake quantified by maximum standardized uptake values (SUV). Symptomatic plaques were compared with contralateral carotid artery plaques considered asymptomatic, and in 17 symptomatic patients, endarterectomized plaque specimens were analyzed for CD68 expression. There was a negative correlation between GSM and FDG SUV (r = -0.56, p < 0.01). Whereas echo-rich plaques tended to show low FDG uptake, echolucent plaques ranged from high to low inflammatory activity, as depicted with PET. Quantitative FDG SUV differentiated asymptomatic from symptomatic plaques, whereas GSM values did not. There was a positive correlation between CD68 expression and FDG uptake (r = 0.50, p = 0.04). Our results substantiate previous findings of an association between plaque FDG uptake and inflammation. Echolucent plaques exhibit a wide range of inflammatory activity, whereas echorich plaques show little inflammation. FDG PET may be useful for further stratification of echolucent plaques being either active (vulnerable) or inactive.

Postsurgical Atypical F-18 Fluorodeoxyglucose Positron Emission Tomography Uptake

False positive recognition is crucial for proper interpretation of F-18 fluorodeoxyglucose-positron emission tomography (FDG-PET) studies. A 48-year-old woman previously diagnosed with stage IIIB non-small-cell lung cancer underwent extrapleural pneumonectomy and intraoperative photodynamic therapy over a month prior to PET/CT imaging, which revealed significant tracer uptake within muscles and soft tissue in several sites contralateral to the location of surgery. The FDG-PET images of this case illustrate the importance of communication between physicians ordering and physicians reading FDG-PET/CT scans as well as atypical FDG-PET findings that could be interpreted as concerning but are, in fact, innocuous. This study also demonstrates the unusual glucose metabolic patterns which may arise after treatment, be it surgical, chemotherapeutic, or radiation.

The Significance and Management of Incidental [18F]Fluorodeoxyglucose–Positron-Emission Tomography Uptake in the Thyroid Gland in Patients with Cancer

Incidental positron-emission tomography (PET) uptake in the thyroid bed represents a diagnostic dilemma. Currently, there is no consensus regarding the significance of this finding or the most appropriate approach to management. The purpose of this study was to determine the significance of incidental fluorodeoxyglucose (FDG) uptake in the thyroid gland on [(18)F]FDG-positron-emission tomography (FDG-PET/CT) in patients being initially staged for lymphomas and/or cancers other than of thyroid origin. A retrospective review was conducted on patients who were incidentally found to have focal FDG uptake in the thyroid bed on initial staging for cancer. Patient records were assessed for age, sex, clinical presentation, standard uptake values (SUV(max)), on FDG-PET/CT, and CT findings in those patients undergoing FDG-PET/CT, fine-needle aspiration (FNA) cytology, and surgical pathologic examination. Thirty patients were identified with incidental FDG-PET uptake in the thyroid bed from 630 studies performed for evaluation of cancer between March 2004 and June 2006. Complete records were available for 18 patients (6 men, 12 women). Five (27.8%) of 18 patients with incidental focal FDG-PET/CT uptake in the thyroid gland demonstrated papillary thyroid carcinoma on final pathologic findings. The mean and SD of SUV(max) was 3.0 +/- 1.8 (range, 1.1-7.4) overall, 2.9 +/- 1.6 (range, 1.1-6.8) in the patients without malignant growth, and 3.4 +/- 2.6 (range, 1.1-7.4) in the 5 patients with papillary thyroid carcinoma. No statistical difference in SUV(max) was noted between patients with papillary thyroid carcinoma and patients with benign pathologic findings (P = .63). Incidental FDG-PET uptake in the thyroid gland in patients with cancer of nonthyroidal origin is associated with a 27.8% risk for well-differentiated thyroid carcinoma; however, there seems to be no correlation between intensity of FDG uptake and the risk for a malignant process.