18F-FDG PET Scans Research Articles

Modest utility of quantitative measures in 18F-fluorodeoxyglucose positron emission tomography scanning for the diagnosis of aortic prosthetic graft infection

The clinical dilemma in suspected aortic graft infection (AGI) is how to noninvasively obtain a reliable proof of infection. In addition to confirming the presence of infection, obtaining information regarding the extent of infection to select a proper strategy for reoperation is also necessary. Therefore, developing a more reliable noninvasive physiologic approach to detect infected prostheses is required. (18)F-fluorodeoxyglucose positron emission tomography scanning ((18)F-FDG PET) has been suggested to have a pivotal role in the detection of AGI. In this study, we assessed the contribution of two (semi) quantitative parameters-maximal standardized uptake value (SUVmax) and tissue-to-background ratio (TBR)-and of two visual parameters-fluorodeoxyglucose (FDG) distribution patterns and visual grading scale-in the final confirmation of the diagnosis of AGI. Patients with a central aortic prosthetic graft and symptoms clinically suggestive of AGI were gathered from a prospectively maintained database. Included were those who underwent (18)F-FDG PET scanning combined with computed tomography angiography and in whom periprosthetic samples were taken at some stage in the diagnostic process. AGI was considered proven in case of a positive culture and compared with a group with negative cultures. Positive predictive values (PPVs) and negative predictive values (NPVs) were calculated. Receiver operating characteristics curves were used to assess the ability of SUVmax and TBR to identify the presence and absence of AGI (ie, accuracy). In 37 of 77 patients with suspected AGI, (18)FDG-PET and perigraft material for culturing was obtained. The tissue culture was positive in 21 of these 37 patients (56.7%). Mean ± standard deviation SUVmax for proven infection was 8.1 ± 3.7 (range, 3.6-18.5) and TBR was 5.9 ± 2.7 (range, 1.7-13.0). The area under the curve for SUVmax was 0.78 (95% confidence interval, 0.63-0.93). A cutoff value of 8 yielded a PPV of 80% and a NPV of 54%. The area under the curve for TBR was 0.70 (95% confidence interval, 0.52-0.87). A cutoff value of 6 yielded a PPV of 73% and NPV of 52%. The PPVs for the visual grading scale and (18)F-FDG distribution patterns were 75% and 61%, respectively; the NPVs were 77% and 67%, respectively. Our study, performed in a small sample of patients suspected of AGI, showed that the diagnostic abilities of quantitative and visual (18)F-FDG PET parameters are modest.

Relationship Between Metabolic Tumor Volume and Rituximab Pharmacokinetic Parameters in Non-Hodgkin’s Lymphoma

The pharmacokinetics (PK) of the monoclonal antibody rituximab in B-cell lymphomas presents a high interindividual variability. In the pivotal study, inverse correlation between rituximab concentration and tumor burden estimated by the measurement of tumor bulk at baseline has been observed (Berinstein and al., Ann. Oncol. 1998). Using a pharmacokinetic/pharmacodynamic (PK/PD) model, it has been demonstrated in a murine model of lymphoma-expressing CD20 that tumor burden influences rituximab concentration (Dayde and al., Blood 2009). The aim of the present study was to evaluate the relationship between rituximab pharmacokinetic (PK) parameters and metabolic tumor volume (MTV) in patients with a previously untreated CD20-positive non-Hodgkin’s lymphoma.Twenty-five patients (12 follicular and 13 diffuse large B-cell lymphoma) received a combination of rituximab (dose of 375 mg/m2) with 6 to 8 cycles of CHOP. All patients provided written informed consent for the study. Rituximab serum levels were measured using a validated enzyme-linked immunosorbent assay (ELISA). Tumor volume delineations were performed on 18F-FDG PET-scan at baseline (Planet Onco, Dosisoft, France). Rituximab PK was assessed using population compartmental modelling. A relationship between MTV and survival was described.Estimations of typical (interindividual standard deviation) systemic clearance (CLc) and volume of distribution (Vc) were 0.00972 L.h-1 and 3.12 L, respectively. Median MTV was 600 mL (range, 7 - 6217 mL). The central volume of distribution and the systemic clearance increased with MTV (p<0.05) (Table). A high MTV (>600 mL) was significantly associated with decreased event-free survival (p<0.05).This pilot study is the first to describe a correlation between initial imaging-calculated metabolic tumor volume as a continuous variable and rituximab PK parameters in patients treated with R-chemotherapy for B-cell lymphomas. An increase in MTV leaded to a decrease in exposure to rituximab. Further prospective investigations on rituximab PK and dose adjustments in relationship with tumor burden are needed. Increased rituximab dose should be considered in patients with high tumor burden.TableEstimated pharmacokinetic parametersParameter (units)EstimatePrecision (%)pVc (L)3,1210b Vc (MTV) (L)0,00012360,0059Cl (L.h-1)0,0097214b Cl (MTV) (L.h-1)0,000146460,03 DisclosuresPaintaud:LFB and Pierre-Fabre Laboratoire: Consultancy; Roche Pharma, Chugai, Pfizer, Novartis, Janssen: Research Funding. Gyan:Roche: Research Funding.

Clinical NECR in 18F-FDG PET scans: optimization of injected activity and variable acquisition time. Relationship with SNR

The injected activity and the acquisition time per bed position for 18F-FDG PET scans are usually optimized by using metrics obtained from phantom experiments. However, optimal activity and time duration can significantly vary from a phantom set-up and from patient to patient. An approach using a patient-specific noise equivalent count rate (NECR) modelling has been previously proposed for optimizing clinical scanning protocols. We propose using the clinical NECR on a large population as a function of the body mass index (BMI) for deriving the optimal injected activity and acquisition duration per bed position. The relationship between the NEC and the signal-to-noise ratio (SNR) was assessed both in a phantom and in a clinical setting. 491 consecutive patients were retrospectively evaluated and divided into 4 BMI subgroups. Two criteria were used to optimize the injected activity and the time per bed position was adjusted using the NECR value while keeping the total acquisition time constant. Finally, the relationship between NEC and SNR was investigated using an anthropomorphic phantom and a population of 507 other patients. While the first dose regimen suggested a unique injected activity (665 MBq) regardless of the BMI, the second dose regimen proposed a variable activity and a total acquisition time according to the BMI. The NEC improvement was around 35% as compared with the local current injection rule. Variable time per bed position was derived according to BMI and anatomical region. NEC and number of true events were found to be highly correlated with SNR for the phantom set-up and partially confirmed in the patient study for the BMI subgroup under 28 kg m−2 suggesting that for the scanner, the nonlinear reconstruction algorithm used in this study and BMI < 28 kg m−2, NEC, or the number of true events linearly correlated with SNR2.

595P - The Impact of Complete Metabolic Response in the Treatment of Metastatic Colorectal Cancer

ABSTRACT Aim: Molecular imaging with 18F-FDG PET scan is increasingly used for monitoring of treatment response in metastatic colorectal cancer. While there is no widely accepted standard for defining partial response, metabolic complete response (mCR) appears as a more reproducible endpoint. We performed a retrospective study to evaluate the impact of mCR on both treatment outcomes and treatment plan. Methods: Patients who were referred to our department for further management of colorectal cancer from Jan 2008 to Dec 2011 were retrospectively reviewed. They were included for subsequent analysis if [1] achieved mCR on 18F-FDG PET scan during first-line therapy, [2] serial PET scans (>= 2) available for demonstration of change in 18F-FDG avidity. The primary endpoint was progression-free survival (PFS). Secondary endpoint were overall survival (OS), time-to-mCR (TTm) and impact of mCR on subsequent treatment plan. Results: Among the 1007 patients referred to us, 356 patients (35%) received systemic therapy for metastatic disease and 202 of them (20%) had PET scan done during the course of systemic therapy. Forty-three patients achieved mCR and 37 of them fulfilled all the criteria for subsequent analysis. mCR was achieved after a median of 4 cycles of systemic therapy (Range 3-12 cycles) after a median TTm of 14weeks (95% CI 12.5-15.5). Subsequent treatment was not altered in 21 patients (56.7%) who had planned drug holiday after six months of therapy. Six and ten of the remaining patients received maintenance therapy and consolidation treatment (resection or radiotherapy), respectively. After a median follow up time of 33 months, the median PFS and OS was 14.4 months (95% CI 10.3 to 18.6) and 47.1 months (95% CI 36.8 to 57.4), respectively. Normal initial CEA ( Conclusions: Favorable outcomes were observed in patients who achieved mCR on 18F-FDG PET scan. Its current impact on treatment decision remains elusive and further studies warranted. Disclosure: All authors have declared no conflicts of interest.

Brain PET Metabolic Abnormalities in a Case of Varicella-Zoster Virus Encephalitis

The role of brain 18F-FDG PET in the diagnostic evaluation of encephalitis has been recently suggested, especially in limbic encephalitis, but descriptions are mainly limited to small case reports. However, the evaluation of cerebral metabolism by 18F-FDG PET has never been described for varicella-zoster virus encephalitis. We report the first case of varicella-zoster virus encephalitis in which 18F-FDG PET revealed brain metabolic abnormalities. Brain metabolic PET imaging was analyzed by comparing the patient's brain 18F-FDG PET scans to that of 12 healthy subjects. Compared with healthy subjects, significant hypometabolism and hypermetabolism were found and evolved over time with treatment.

Quantifying metabolic heterogeneity in head and neck tumors in real time: 2-DG uptake is highest in hypoxic tumor regions.

PurposeIntratumoral metabolic heterogeneity may increase the likelihood of treatment failure due to the presence of a subset of resistant tumor cells. Using a head and neck squamous cell carcinoma (HNSCC) xenograft model and a real-time fluorescence imaging approach, we tested the hypothesis that tumors are metabolically heterogeneous, and that tumor hypoxia alters patterns of glucose uptake within the tumor.Experimental DesignCal33 cells were grown as xenograft tumors (n = 16) in nude mice after identification of this cell line's metabolic response to hypoxia. Tumor uptake of fluorescent markers identifying hypoxia, glucose import, or vascularity was imaged simultaneously using fluorescent molecular tomography. The variability of intratumoral 2-deoxyglucose (IR800-2-DG) concentration was used to assess tumor metabolic heterogeneity, which was further investigated using immunohistochemistry for expression of key metabolic enzymes. HNSCC tumors in patients were assessed for intratumoral variability of 18F-fluorodeoxyglucose (18F-FDG) uptake in clinical PET scans.ResultsIR800-2-DG uptake in hypoxic regions of Cal33 tumors was 2.04 times higher compared to the whole tumor (p = 0.0001). IR800-2-DG uptake in tumors containing hypoxic regions was more heterogeneous as compared to tumors lacking a hypoxic signal. Immunohistochemistry staining for HIF-1α, carbonic anhydrase 9, and ATP synthase subunit 5β confirmed xenograft metabolic heterogeneity. We detected heterogeneous 18F-FDG uptake within patient HNSCC tumors, and the degree of heterogeneity varied amongst tumors.ConclusionHypoxia is associated with increased intratumoral metabolic heterogeneity. 18F-FDG PET scans may be used to stratify patients according to the metabolic heterogeneity within their tumors, which could be an indicator of prognosis.

Feasibility of 18F-FDG PET as a noninvasive diagnostic tool of muscle denervation: a preliminary study.

The purpose of this study was to confirm glucose hypermetabolism in denervated muscle and investigate the feasibility of (18)F-FDG PET scanning for the detection of muscle denervation. A sciatic neuropathy model in rats was created by nerve resection of the left sciatic nerve and sham operation on the other side. Eight days after denervation, small-animal PET/CT scans of the hindlimbs were acquired. Muscle denervation was confirmed by electrophysiologic and histologic study. All rats showed increased (18)F-FDG uptake in the muscles of the left (denervated) lower legs. The calculated maximum lesion-to-normal counts ratio of the left lower leg anterolateral (left, 11.02 ± 2.08; right, 1.81 ± 0.40, n = 6, P < 0.01) and posterior (left, 9.81 ± 4.58; right, 1.87 ± 0.44, n = 6, P < 0.01) compartment were significantly increased. The electrophysiologic and histologic study verified muscle denervation. Glucose hypermetabolism in muscle denervation is an obvious phenomenon. (18)F-FDG PET scanning can be used to visualize muscle denervation.

18F-FDG PET as a Monitoring Tool to Assess Treatment Response in Bilateral Adrenal Histoplasmosis

A 60-year-old woman with clinical and biochemical features suggestive of adrenal insufficiency was found to have bilateral adrenal masses on CT scan and was subjected to F-FDG PET scan. The scan showed hypermetabolic mediastinal nodes in addition to intense tracer uptake in bilateral adrenal masses. CT-guided adrenal biopsy grew Histoplasma capsulatum on Sabouraud dextrose agar culture. A second F-FDG PET scan after 6 months of appropriate antifungal therapy showed a significant decrease in intensity of uptake consistent with the clinical outcome.

TU-F-12A-05: Sensitivity of Textural Features to 3D Vs. 4D FDG-PET/CT Imaging in NSCLC Patients

Purpose: Neighborhood Gray-level difference matrices (NGLDM) based texture parameters extracted from conventional (3D) 18F-FDG PET scans in patients with NSCLC have been previously shown to associate with response to chemoradiation and poorer patient outcome. However, the change in these parameters when utilizing respiratory-correlated (4D) FDG-PET scans has not yet been characterized for NSCLC. The Objectives: of this study was to assess the extent to which NGLDM-based texture parameters on 4D PET images vary with reference to values derived from 3D scans in NSCLC. Methods: Eight patients with newly diagnosed NSCLC treated with concomitant chemoradiotherapy were included in this study. 4D PET scans were reconstructed with OSEM-IR in 5 respiratory phase-binned images and corresponding CT data of each phase were employed for attenuation correction. NGLDM-based texture features, consisting of coarseness, contrast, busyness, complexity and strength, were evaluated for gross tumor volumes defined on 3D/4D PET scans by radiation oncologists. Variation of the obtained texture parameters over the respiratory cycle were examined with respect to values extracted from 3D scans. Results: Differences between texture parameters derived from 4D scans at different respiratory phases and those extracted from 3D scans ranged from −30% to 13% for coarseness, −12% to 40% for contrast, −5%more » to 50% for busyness, −7% to 38% for complexity, and −43% to 20% for strength. Furthermore, no evident correlations were observed between respiratory phase and 4D scan texture parameters. Conclusion: Results of the current study showed that NGLDM-based texture parameters varied considerably based on choice of 3D PET and 4D PET reconstruction of NSCLC patient images, indicating that standardized image acquisition and analysis protocols need to be established for clinical studies, especially multicenter clinical trials, intending to validate prognostic values of texture features for NSCLC.« less

Ultra Staging to Unmask the Prescribing of Adjuvant Therapy in Cancer Patients: The Future Opportunity to Image Micrometastases Using Total-Body 18F-FDG PET Scanning

Ultra Staging to Unmask the Prescribing of Adjuvant Therapy in Cancer Patients: The Future Opportunity to Image Micrometastases Using Total-Body ¹⁸F-FDG PET Scanning

18F-FDG PET Scanning in Pulmonary Amyloidosis

(18)F-FDG PET plays an important role in the evaluation of patients with lung malignancies but can lead to false-positive and false-negative results. Very little is known about (18)F-FDG PET scanning in amyloidosis. A computer-assisted search of medical records was conducted to identify subjects with pulmonary amyloidosis (confirmed by biopsy) who were seen at the Mayo Clinic during a 15-y period between January 1, 1997, and December 31, 2011, and had a PET scan available for current review. Eighteen patients were diagnosed to have amyloidosis by lung biopsy (15 surgical, 2 transthoracic needle, and 1 bronchoscopic). The mean age of the patients was 64.8 y (range, 32-80 y). Seventeen patients had primary amyloidosis, including 5 with Sjögren syndrome, 1 with rheumatoid arthritis, and 1 with multiple myeloma. The most common abnormal findings on the chest CT scan were pulmonary nodules (n = 14), followed by cysts (n = 6) and reticular opacities (n = 4). Eight patients had positive (18)F-FDG PET results (intrathoracic (18)F-FDG uptake), including 4 patients with coexisting mucosa-associated lymphoid tissue lymphoma (maximal standardized uptake value [SUVmax] range, 3.1-6.7) and 1 patient with a pleural plasmacytoma (SUVmax, 7.2); the remaining 3 patients had amyloid only (SUVmax range, 2.1-3.2). Ten patients with negative PET results included 3 additional patients with mucosa-associated lymphoid tissue lymphoma. Positive (18)F-FDG PET results, especially with an SUVmax of more than 3, in patients with pulmonary amyloidosis should raise suspicion about associated lymphoma or plasmacytoma, but negative PET results do not exclude the presence of such neoplasms.

The metabolic brain network in patients with Parkinson's disease based on (18)F-FDG PET imaging: evaluation of neuronal injury and regeneration.

Over the past two decades, the development of functional imaging methods has greatly promoted our understanding on the changes of neurons following neurodegenerative disorders, such as Parkinson's disease (PD). The application of a spatial covariance analysis on 18F-FDG PET imaging has led to the identification of a distinctive disease-related metabolic pattern. This pattern has proven to be useful in clinical diagnosis, disease progression monitoring as well as assessment of the neuronal changes before and after clinical treatment. It may potentially serve as an objective biomarker on disease progression monitoring, assessment, histological and functional evaluation of related diseases. PD is one of the most common neurodegenerative disorders in the elderly. It is characterized by progressive loss of dopamine neurons in the substantia nigra pars compacta. Throughout the course of disease, the most obvious symptoms are movement-related, such as resting tremor, muscle rigidity, hypokinesia and postural instability (Worth, 2013). Currently, a definite diagnosis of PD is made by clinical evaluation with at least 2 years of follow-up (Hughes et al., 2002; Bhidayasiri and Reichmann, 2013), due to the overlap of motor symptoms between early PD and atypical parkinsonism including multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). However, this classic diagnostic criterion does not benefit the early diagnosis of disease. The prognostic outcome and treatment option are substantially different between PD and atypical parkinsonism. Thus it is critical to develop biomarkers for earlier and more accurate diagnosis of PD. Generally, appropriate diagnostic biomarker for PD ought to cover several key characteristics: (i) minimal invasiveness to detect the biomarker in easily accessible body tissue or fluids, (ii) excellent sensitivity to explore the patients with PD, (iii) high specificity to prevent false-positive results in PD-free individuals, and (iv) robustness against potential affecting factors. A PD-related spatial covariance pattern (PDRP) with quantifiable expression on 18F-FDG PET imaging has been gradually detected using a spatial covariance method during the last two decades and it has been demonstrated to be the right diagnostic biomarker for PD (Eidelberg et al., 1994). PDRP has proven not only to be effective in early discrimination of PD from atypical parkinsonian disorders, but also to be able to assess the disease progression and treatment response. Thus it is considered as a multifunctional biomarker. In this review, we aim to provide an overview of the development in pattern-based biomarker for PD.

Nuclear imaging in proliferative angiopathy

This 37-year-old man was referred for an F-FDG PET scan of the brain. His medical history mentioned a large arteriovenous malformation (AVM) related to a slowly progressive angiopathy in the right hemisphere, which was left untreated. Recently, he had complained of recurrent transient hyperaesthesia of his left hand and face. MRI showed an elaborate, diffuse vascular network in the right hemisphere, both supraand infratentorial, without signs of acute ischaemia or infarction. Digital subtraction angiography (DSA) showed an extensive vascular malformation with low-grade arteriovenous shunting in the right hemisphere, right hemicerebellum and to a lesser extent in the medial part of the occipital lobe on the left side. To evaluate the brain metabolism of the right hemisphere, an F-FDG PET scan of the brain was performed. The scan showed diffuse moderate to severe hypometabolism of the entire right hemisphere, the basal ganglia and less pronounced the left side of the cerebellum, the latter suggesting a crossed cerebellar diaschisis. The left hemisphere showed normal metabolism. Cerebral proliferative angiopathy is a rare entity, marked by a diffuse lobar or holohemispheric network of arteriovenous shun t ing , and d i f f e r s f rom othe r AVMs in i t s angiomorphology, histology, epidemiology, natural history and clinical presentation [1]. After establishing the diagnosis by MRI and DSA [2], FDG PET may be useful to assess the degree and extent of cerebral metabolic involvement in patients with AVM [3].

Complete somatostatin-induced insulin suppression combined with heparin loading does not significantly suppress myocardial 18F-FDG uptake in patients with suspected cardiac sarcoidosis

BackgroundCardiac 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography preceded by extended fasting is used to demonstrate active cardiac sarcoidosis. However, physiological insulin-dependent myocardial 18F-FDG uptake often obscures 18F-FDG uptake in sarcoid lesions. We therefore aimed to completely suppress physiological myocardial 18F-FDG uptake by pharmaceutically blocking endogenous insulin secretion while elevating free fatty acids (FFAs). Methods and resultsSix patients with suspected cardiac sarcoidosis were studied in a randomized cross-over design: (1) 12 hours fasting followed by 2 hours saline infusion (SALINE), and (2) 12 hours fasting followed by 2 hour infusions of somatostatin (300 μg/hour) and heparin (70 mIE/kg/minutes) (SOMA). 18F-FDG PET scans were performed post-infusion. Glucose, insulin, and FFA levels were measured and left ventricle SUV-values were recorded. During the SALINE infusion, insulin, glucose, and FFAs remained stable. By design, the SOMA infusions rapidly (<60 minutes) suppressed insulin completely, while FFA levels peaked at 1.13 ± 0.23 mM. However, SOMA infusions only suppressed cardiac 18F-FDG uptake insignificantly globally [SUVmean (g/mL): 4.0 ± 3.3 (SALINE) vs 2.4 ± 1.2 (SOMA), P = .15] and regionally. ConclusionsComplete insulin suppression combined with markedly increased circulating FFAs does not completely suppress physiological myocardial 18F-FDG uptake and thus conveys no extra diagnostic value compared with extended fasting.

Metabolic Imaging of Deep Brain Stimulation in Anorexia Nervosa

Anorexia nervosa (AN), a disorder of unknown etiology, has the highest mortality rate of any psychiatric disorder. Drawing the brain metabolic pattern of AN may help to target the core biological and psychological features of the disorder and to perfect the diagnosis and recovery criteria. In this study, we used 18F-FDG PET to show brain metabolic network for AN. Glucose metabolism in 6 AN patients and 12 age-matched healthy controls was studied using 18F-FDG PET. SPM2 was used to compare brain metabolism in AN patients with that in healthy controls. Four of 6 AN patients took deep brain stimulation (DBS) targeted in nucleus accumbens (NAcc). About 3 to 6 months after the surgery, the 4 AN patients took another 18F-FDG PET scan to assess the change in brain glucose metabolism. The SPM (statistical parametric mapping ) analysis showed hypermetabolism in the frontal lobe (bilateral, BA10, BA11, BA47), the limbic lobe (bilateral, hippocampus, and amygdala), lentiform nucleus (bilateral), left insula (BA13), and left subcallosal gyrus (BA25). It also showed hypometabolism in the parietal lobe (bilateral, BA7, BA40). The hypermetabolism in frontal lobe, hippocampus, and lentiform nucleus decreased after NAcc-DBS. The changes in brain glucose metabolism illustrated the brain metabolic pattern in AN patients. Furthermore, the pattern can be modulated by NAcc-DBS, which confirmed specificity of the pattern. The regions with altered metabolism could interconnect to form a network and integrate information related to appetite. Our study may provide information for targeting the potential candidate brain regions for understanding the pathophysiology of AN and assessing the effects of existing and future treatment approaches.

Factors affecting bilateral temporal lobe hypometabolism on 18F-FDG PET brain scan in unilateral medial temporal lobe epilepsy

Bilateral temporal lobe hypometabolism (BTH) on 18F-FDG PET brain scan is frequently seen in unilateral medial temporal lobe epilepsy (mTLE). This study aimed to identify the factors that influence BTH in patients with mTLE in order to minimize the significant factor(s) prior to performing a FDG-PET brain scan. Forty patients with unilateral mTLE who underwent 18F-FDG PET scan for presurgical epilepsy workup were included. Bilateral temporal lobe hypometabolism of the anterior and medial parts of the temporal lobe was identified by a semiquantitative visual scale. Lateralization of TLE was identified by either intracranial EEG (22/40 cases) and/or improvement of seizure 2years after temporal lobectomy (37/40 cases). The factors analyzed included basic demographic characteristics (age, sex, occupation, years of education, and handedness), history related to seizure (age at epilepsy onset and epilepsy duration, history of febrile seizure and head injury, frequency of seizure with impaired cognition in the last 3months, presence of secondarily generalized tonic–clonic seizure, automatism side, presence of postictal confusion, and side of MRI temporal abnormality), information during video-EEG monitoring (clinical lateralization, interictal scalp EEG lateralization (interictal epileptiform discharge), and ictal scalp EEG lateralization), and information during the FDG-PET study (duration from the last seizure (≤2days or >2days), last seizure type, and the presence of slow waves or sharp waves during the FDG uptake period). Significant factors related to BTH were analyzed using multivariate analysis. Only the ≤2-day duration from the last seizure to the PET scan shows a significant effect (p=0.021) on BTH finding with 15 times greater incidence compared to a duration >2days. Bilateral temporal lobe hypometabolism, which causes conflict in lateralizing the epileptogenic zone in temporal lobe epilepsy, can be avoided by performing PET scan more than 2days after the last seizure.

Impact of Clinical and Dosimetric Factors on Pericardial Effusion in Patients With Stage I Esophageal Cancer Treated With Definitive Chemoradiation Therapy

Purpose/Objective(s): The aim of this study was to quantitatively evaluate the value of diagnostic information provided by both F-FDG and F-FLT PET and quantitatively investigated whether F-FLT PET had a better performance compared with F-FDG PET in esophageal squamous cell carcinoma (ESCC) staging and delineation. Materials/Methods: Twenty-six patients with newly diagnosed ESCC and underwent pretreatment F-FDG and F-FLT PET were included in this study. The indices such as the standardized uptake value (SUV), gross tumor length and extracted texture parameters between F-FDG and F-FLT PET were compared, respectively. Moreover, the indices’ relationship between F-FDG and F-FLT PET mentioned above, were analyzed using Spearman’s correlation coefficient and Paired T-test. Subsequently all patients received esophagectomy and the extracted PET indices’ capability in ESCC pathological staging were assessed by Kruskal-Wallis test and Mann-Whitney test. In addition, tumor delineation length on F-FDG (SUV threshold 2.5) and F-FLT (SUV threshold 1.4) PET were validated by pathologic gross tumor length. Results: F-FDG highly correlated with F-FLT possessing a high correlation coefficient value r approximate 0.8 and p < 0.001 in SUVmax or SUVmean. F-FDG uptake was significantly higher than F-FLT with respect to average SUVmax(F-FDG: 11.48, F-FLT: 6.07) or average SUVmean (F-FDG: 6.09, F-FLT: 3.80), with Paired T-test result p < 0.001. In terms of texture parameters’ relationship Entropy and Correlation (two derived texture parameters) showed statistically significant difference. Both of F-FDG and F-FLT PET SUV, some of texture parameters, gross tumor length and shape feature showed statistically significant difference with respect to their feasibility in ESCC staging. The mean standard deviation pathologic longitudinal tumor length was 5.52 2.56 cm and delineation length for F-FDG and F-FLT were 5.60 2.32 cm and 5.49 2.43 cm, respectively. Conclusions: The F-FDG and F-FLT PET scans have their own advantages in ESCC staging and tumors were well identified as the nonphysiologic distribution of radiotracers intensity typically higher than normal tissues on either PET scans. Delineation on the two types of PET with proper threshold can both provide accuracy estimation of pathologic tumor length. Those different indices extracted from PET scans can be potentially employed to differentiate AJCC and TNM in ESCC stage. Author Disclosure: C. Ma: None. Y. Yin: None.

Sentinel Lymph Node Biopsy in pediatric soft tissue sarcoma patients: Utility and concordance with imaging

BackgroundThe purpose of this study was to report our experience with sentinel lymph node biopsy (SLNB) for pediatric soft tissue sarcomas to add to the limited literature about its feasibility, utility, and concordance with pre-operative imaging, including CT and 18F-FDG PET (PET) scanning. MethodsMedical records of patients with a sarcoma who underwent SLNB as part of their treatment for a soft tissue sarcoma at our institution from 2000 to 2011 were identified and reviewed. ResultsEight patients underwent SLNB for soft tissue sarcoma during the study period. Two patients had positive SLNBs; both of these patients had rhabdomyosarcoma. Three patients with pathologically enlarged lymph nodes on CT scan underwent PET functional imaging prior to SLNB. The PET suggested the presence of nodal disease in all three patients; however, only one of these patients had a positive SLNB. ConclusionsOur series confirms that SLNB is feasible in pediatric sarcoma patients. Small numbers preclude definitive conclusions regarding the utility of SLNB compared with PET, however our data suggest functional imaging alone may not be sufficient to definitively determine lymph node status in these patients. Surgical lymph node sampling may still need to be performed to accurately identify nodal status in pediatric patients with soft tissue sarcoma.

Diagnosis of pulmonary sarcoidosis

To summarize and highlight recent advances in the field of the diagnosis of pulmonary sarcoidosis. Several techniques have emerged as important tools in the context of a clinical and radiological situation compatible with pulmonary sarcoidosis. Among them, computed tomography (CT) scan can not only exhibit characteristic imaging, but also contribute to an increased yield of tissue sampling through transbronchial biopsies. CT is also essential to the detection of mediastinal lymphadenopathy as potential targets of endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA). The latter is a well-tolerated and highly sensitive procedure which might become the first-line diagnostic tool in sarcoid patients with hilar or mediastinal lymph nodes. 18F deoxy-fluoro-glucose (18F-FDG) PET has a remarkable sensitivity in the detection of occult sites of the disease and a high value in guiding biopsy to these active sites. A combined imaging modality using both F-FDG PET and CT scan, more sensitive than PET alone, is now the standard of care in patients requiring histological sampling of active lesions. The finding of noncaseating granulomas remains crucial to the diagnosis of sarcoidosis. The methods described here markedly enhance the diagnostic yield of tissue sampling along with low risks of complications.

18F-Flumazenil: A γ-Aminobutyric Acid A–Specific PET Radiotracer for the Localization of Drug-Resistant Temporal Lobe Epilepsy

Studies report that (11)C-flumazenil (FMZ) PET more specifically localizes the epileptogenic zone in patients with medically refractory focal epilepsy than (18)F-FDG PET. However, practical aspects of (11)C use limit clinical application. We report a phase I/IIa study assessing the clinical use of (18)F-FMZ PET for the localization of the epileptogenic zone in patients with drug-resistant temporal lobe epilepsy (TLE). Receptor binding was quantified using kinetic modeling that did not require arterial sampling. Dynamic (18)F-FMZ PET and static interictal (18)F-FDG PET scans were compared in healthy controls (n = 17 for (18)F-FMZ and n = 20 for (18)F-FDG) and TLE patients with mesial temporal sclerosis on MR imaging (MTS, n = 12) and with normal MR imaging (NL TLE, n = 19). Masked visual assessment of images was undertaken. Parametric images of (18)F-FMZ binding potential (BPND) were generated using the simplified reference tissue model. Region-of-interest analysis on coregistered MR images and statistical parametric mapping were used to quantify (18)F-FMZ BPND and (18)F-FDG uptake in the temporal lobe. The visual assessment of static standardized uptake value images showed (18)F-FMZ PET to have high specificity (16/17 [94%]) and moderate sensitivity (21/31 [68%]) for the localization of the epileptogenic zone, with a more restricted abnormality than (18)F-FDG PET. However, the (18)F-FMZ standardized uptake value images were falsely localizing in 3 of 31 patients (10%). Region-of-interest analysis demonstrated reductions in ipsilateral hippocampal (18)F-FMZ BPND in patients with either MTS or NL TLE, compared with controls subjects. Ipsilateral hippocampal (18)F-FMZ BPND was independent of both hippocampal volume and (18)F-FDG uptake, whereas ipsilateral hippocampal volume was correlated with (18)F-FDG uptake (r(2) = 0.69, P < 0.0001). Statistical parametric mapping analysis demonstrated decreased uptake in 14 of 31 (45%) cases with (18)F-FMZ PET and 18 of 29 (62%) with (18)F-FDG PET. Cluster size was significantly smaller on (18)F-FMZ than (18)F-FDG images (37 vs. 160 voxels, P < 0.01). (18)F-FMZ PET has potential as a clinical tool for the localization of the epileptogenic zone in the presurgical evaluation of drug-resistant TLE, providing information complementary to (18)F-FDG PET, with a more restricted region of abnormality.