F-labeled Fluorodeoxyglucose Research Articles

First Extensive Analysis of 18F-Labeled Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography in a Large Cohort of Patients With HIV-Associated Hodgkin Lymphoma: Baseline Total Metabolic Tumor Volume Affects Prognosis.

18F-labeled fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG PET-CT) data in HIV-associated Hodgkin lymphoma (HIV-HL) are scarcely reported. In addition to the description of the characteristics of both baseline and interim 18F-FDG PET-CT examinations (PET1 and iPET, respectively), the aim of this study was to assess the prognostic value of PET1 and previously identified clinical parameters in this population. PET1 of 109 patients with HIV-HL, treated with doxorubicin, bleomycin, vinblastine, and dacarbazine chemotherapy regimen since 2007, and 104 iPET were centrally reviewed. All the patients were enrolled in an ongoing prospective single-center cohort of HIV-associated lymphoma. Most patients had a disseminated disease according to the Ann Arbor classification (30% stage III and 43% stage IV), with especially bone marrow and liver as extranodal localizations. After a median follow-up of 6.7 years, 12 patients relapsed (11%) and 13 died (12%). Five-year progression-free survival (PFS) was 75.1%, and 5-year overall survival was 86.1%. Median total metabolic tumor volume (TMTV) was 121.4 cm3. The optimal TMTV cutoff identified for prognostic analysis was 527 cm3, with a 2-year PFS of 71% in the 20 patients with TMTV > 527 cm3, compared with 91% in the 89 patients with TMTV ≤ 527 cm3 (P = .004). On multivariate analysis, a high TMTV was the only parameter independently associated with PFS. In this large series of HIV-HL patients with a homogeneous management, high TMTV on PET1 examination was associated with a poor prognosis.

Usefulness of 18 F-Labeled Fluorodeoxyglucose-Positron Emission Tomography for the Diagnosis of Lymphoma in Primary Sjögren's Syndrome.

The usefulness of positron emission tomography-computed tomography (PET-CT) with 18 F-labeled fluorodeoxyglucose (18 F-FDG) for the diagnosis of lymphoma in patients with primary Sjögren's syndrome (SS) is unclear, since the abnormalities it reveals may be due to systemic manifestations of SS. This study was undertaken to compare 18 F-FDG-PET-CT in patients with primary SS with lymphoma and those without lymphoma in order to identify patterns associated with lymphoma. A retrospective study was conducted in 2 centers and included patients who met the American College of Rheumatology/European League Against Rheumatism 2016 criteria for primary SS and had undergone PET-CT. Two independent readers who were blinded with regard to lymphoma diagnosis analyzed PET-CT scans. Abnormalities were compared between patients with and those without lymphoma. Of the 45 patients included, 15 had lymphoma. Compared to patients without lymphoma, the mean size (P = 0.048) and maximum standardized uptake value (SUVmax) (P = 0.001) of the parotid glands were higher in patients with lymphoma. FDG uptake in the lymph nodes was observed in 53.3% of the patients with lymphoma and 43.3% of the patients without lymphoma, with no difference in the number of sites, uptake pattern, or mean SUVmax. Focal pulmonary uptake (nodules or condensations) was observed in 5 of the patients with lymphoma (33.3%) but only 1 patient without lymphoma (3.3%) (P = 0.01). Having an SUVmax in the parotid gland of ≥4.7 and/or the presence of focal pulmonary lesions was highly suggestive of lymphoma (sensitivity 80%, specificity 83.3%). Some systemic manifestations of primary SS (lymphadenopathy, pulmonary involvement, and salivary gland involvement) can be visualized by PET-CT. Involvement of the lymph nodes and parotid glands is commonly observed with a similar frequency in SS patients with and those without lymphoma. An SUVmax in the parotid glands of ≥4.7 and/or the presence of focal lung lesions are associated with the diagnosis of lymphoma.

ST09, a Novel Thioester Derivative of Tacrine, Alleviates Cognitive Deficits and Enhances Glucose Metabolism in Vascular Dementia Rats

Chemical entities containing mercapto group have been increasingly attractive in the therapy of central nerve system (CNS) diseases. In the recent study, we screened a series of mercapto-tacrine derivatives with synergistic neuropharmacological profiles in vitro. We investigated the effect and mechanism of ST09, a thioester derivative of tacrine containing a potential mercapto group, on the vascular dementia (VaD) model of rat induced by bilateral common carotid arteries occlusion (2-VO). ST09 and its active metabolite ST10 retained excellent inhibition on acetylcholinesterase (AChE) activity. ST09 significantly attenuated the 2-VO-induced impairment in spatial acquisition performance and inhibited the 2-VO-induced rise of AChE activity. In the VaD model, ST09 attenuated the oxidative stress and decreased the apoptosis in the cortex and hippocampus. Compared with donepezil, ST09 exhibited a better effect on the regeneration of free thiols in 2-VO rats. Interestingly, ST09, not donepezil, greatly improved glucose metabolism in various brain regions of 2-VO rats using functional imaging of (18) F-labeled fluoro-deoxyglucose (FDG) positron emission tomography (PET). ST09 may serve as a more promising agent for the therapy of VaD than tacrine owing to the introduction of a potential mercapto group into the parent skeleton.

Tendon Graft Healing in Multiligament Reconstructed Knee Detected by FDG-PET/CT: A Pilot Study.

The detection of graft viability is challenging in the multiligament reconstructed knee. Magnetic resonance imaging gives structural information but lacks the capability to assess biological activity of the grafts. (18)F-labeled fluorodeoxyglucose positron emission tomography combined with computer tomography is shown to be a sensitive method for imaging tissue metabolism and viability. The aim of the present study was to evaluate the feasibility of fluorodeoxyglucose positron emission tomography combined with computer tomography imaging in the detection of the replacement graft metabolism in multiligament reconstructed knees. Seven patients (17-44 years) with multiligament reconstructed knee underwent fluorodeoxyglucose positron emission tomography combined with computer tomography to evaluate the biological activity of replacement grafts. The degree of fluorodeoxyglucose uptake reported as standard uptake values from the region of interest was analyzed 3-24 months postoperatively. In all patients, the fluorodeoxyglucose positron emission tomography combined with computer tomography showed increased fluorodeoxyglucose uptake in all replacement grafts at different follow-up time points. Furthermore, fluorodeoxyglucose was higher at femoral condyles of operated knees compared to contralateral reference values. This pilot study shows a significant increase in tendon graft metabolism during two first years of postoperative healing. The fluorodeoxyglucose positron emission tomography combined with computer tomography imaging seems to be adequate method of assessment of graft metabolism and viability during postoperative healing. The clinical value of fluorodeoxyglucose positron emission tomography combined with computer tomography imaging, however, warrants further evaluation with longitudinal studies with a larger patient population.

Salutary Effects of Estrogen Sulfate for Traumatic Brain Injury

Estrogen plays an important role as a neuroprotector in the central nervous system (CNS), directly interacting with neurons and regulating physiological properties of non-neuronal cells. Here we evaluated estrogen sulfate (E2-SO4) for traumatic brain injury (TBI) using a Sprague-Dawley rat model. TBI was induced via lateral fluid percussion (LFP) at 24 h after craniectomy. E2-SO4 (1 mg/kg BW in 1 mL/kg BW) or saline (served as control) was intravenously administered at 1 h after TBI (n=5/group). Intracranial pressure (ICP), cerebral perfusion pressure (CPP), and partial brain oxygen pressure (pbtO2) were measured for 2 h (from 23 to 25 h after E2-SO4 injection). Brain edema and diffuse axonal injury (DAI) were assessed by diffusion tensor imaging (DTI), and cerebral glycolysis was measured by (18)F-labeled fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging, at 1 and 7 days after E2-SO4 injection. E2-SO4 significantly decreased ICP, while increasing CPP and pbtO2 (p<0.05) as compared with vehicle-treated TBI rats. The edema size in the brains of the E2-SO4 treated group was also significantly smaller than that of vehicle-treated group at 1 day after E2-SO4 injection (p=0.04), and cerebral glycolysis of injured region was also increased significantly during the same time period (p=0.04). However, E2-SO4 treatment did not affect DAI (p>0.05). These findings demonstrated the potential benefits of E2-SO4 in TBI.

18F]FDG-PET Standard Uptake Value as a Metabolic Predictor of Bone Marrow Response to Radiation: Impact on Acute and Late Hematological Toxicity in Cervical Cancer Patients Treated With Chemoradiation Therapy

To quantify the relationship between bone marrow (BM) response to radiation and radiation dose by using (18)F-labeled fluorodeoxyglucose positron emission tomography [(18)F]FDG-PET standard uptake values (SUV) and to correlate these findings with hematological toxicity (HT) in cervical cancer (CC) patients treated with chemoradiation therapy (CRT). Seventeen women with a diagnosis of CC were treated with standard doses of CRT. All patients underwent pre- and post-therapy [(18)F]FDG-PET/computed tomography (CT). Hemograms were obtained before and during treatment and 3 months after treatment and at last follow-up. Pelvic bone was autosegmented as total bone marrow (BMTOT). Active bone marrow (BMACT) was contoured based on SUV greater than the mean SUV of BMTOT. The volumes (V) of each region receiving 10, 20, 30, and 40 Gy (V10, V20, V30, and V40, respectively) were calculated. Metabolic volume histograms and voxel SUV map response graphs were created. Relative changes in SUV before and after therapy were calculated by separating SUV voxels into radiation therapy dose ranges of 5 Gy. The relationships among SUV decrease, radiation dose, and HT were investigated using multiple regression models. Mean relative pre-post-therapy SUV reductions in BMTOT and BMACT were 27% and 38%, respectively. BMACT volume was significantly reduced after treatment (from 651.5 to 231.6 cm(3), respectively; P<.0001). BMACT V30 was significantly correlated with a reduction in BMACT SUV (R(2), 0.14; P<.001). The reduction in BMACT SUV significantly correlated with reduction in white blood cells (WBCs) at 3 months post-treatment (R(2), 0.27; P=.04) and at last follow-up (R(2), 0.25; P=.04). Different dosimetric parameters of BMTOT and BMACT correlated with long-term hematological outcome. The volumes of BMTOT and BMACT that are exposed to even relatively low doses of radiation are associated with a decrease in WBC counts following CRT. The loss in proliferative BM SUV uptake translates into low WBC nadirs after treatment. These results suggest the potential of intensity modulated radiation therapy to spare BMTOT to reduce long-term hematological toxicity.

Role of FDG-PET in the Implementation of Involved-Node Radiation Therapy for Hodgkin Lymphoma Patients

This study examines the role of (18)F-labeled fluorodeoxyglucose positron emission tomography (FDG-PET) in the implementation of involved-node radiation therapy (INRT) in patients treated for clinical stages (CS) I/II supradiaphragmatic Hodgkin lymphoma (HL). Patients with untreated CS I/II HL enrolled in the randomized EORTC/LYSA/FIL Intergroup H10 trial and participating in a real-time prospective quality assurance program were prospectively included in this study. Data were electronically obtained from 18 French cancer centers. All patients underwent APET-computed tomography (PET-CT) and a post-chemotherapy planning CT scanning. The pre-chemotherapy gross tumor volume (GTV) and the postchemotherapy clinical target volume (CTV) were first delineated on CT only by the radiation oncologist. The planning PET was then co-registered, and the delineated volumes were jointly analyzed by the radiation oncologist and the nuclear medicine physician. Lymph nodes undetected on CT but FDG-avid were recorded, and the previously determined GTV and CTV were modified according to FDG-PET results. From March 2007 to February 2010, 135 patients were included in the study. PET-CT identified at least 1 additional FDG-avid lymph node in 95 of 135 patients (70.4%; 95% confidence interval [CI]: 61.9%-77.9%) and 1 additional lymph node area in 55 of 135 patients (40.7%; 95% CI: 32.4%-49.5%). The mean increases in the GTV and CTV were 8.8% and 7.1%, respectively. The systematic addition of PET to CT led to a CTV increase in 60% of the patients. Pre-chemotherapy FDG-PET leads to significantly better INRT delineation without necessarily increasing radiation volumes.

FDG-PET in Prosthetic Graft Infections

Graft infection following prosthetic vascular reconstruction is an uncommon but severe complication. The clinical presentation is often subtle and nonspecific and may occur long after surgery. Although defining a prosthetic vascular graft infection can be difficult, early diagnosis and treatment are essential for the correct choice of treatment to prevent further complications as well as the high morbidity and mortality associated with repeat surgery and removal of infected grafts. False-positive results may lead to unnecessary surgery while failure to diagnose graft infection may have life-threatening sequels. Scarce literature that is currently available regarding the role of (18)F-labeled fluorodeoxyglucose imaging for assessment of vascular graft infection suggests that this modality may represent reliable noninvasive imaging modality in this specific clinical setting. PET/CT increases the test specificity and thus improves diagnostic accuracy. The precise anatomic localization of increased (18)F-labeled fluorodeoxyglucose PET/CT enables accurate differentiation between graft and adjacent soft tissue infection leading to more accurate diagnosis and subsequent optimized therapeutic strategy.

Radiation Field Design and Patterns of Locoregional Recurrence Following Definitive Radiotherapy for Breast Cancer

Locoregional control is associated with breast cancer-specific and overall survival in select women with breast cancer. Although several patient, tumor, and treatment characteristics have been shown to contribute to locoregional recurrence (LRR), studies evaluating factors related to radiotherapy (XRT) technique have been limited. We investigated the relationship between LRR location and XRT fields and dose delivered to the primary breast cancer in women experiencing subsequent locoregional relapse. We identified 21 women who were previously treated definitively with surgery and XRT for breast cancer. All patients developed biopsy-result proven LRR and presented to Emory University Hospital between 2004 and 2010 for treatment. Computed tomography (CT) simulation scans with XRT dose files for the initial breast cancer were fused with (18)F-labeled fluorodeoxyglucose positron emission tomography (FDG PET)/CT images in DICOM (Digital Imaging and Communications in Medicine) format identifying the LRR. Each LRR was categorized as in-field, defined as ≥95% of the LRR volume receiving ≥95% of the prescribed whole-breast dose; marginal, defined as LRR at the field edge and/or not receiving ≥95% of the prescribed dose to ≥95% of the volume; or out-of-field, that is, LRR intentionally not treated with the original XRT plan. Of the 24 identified LRRs (3 patients experienced two LRRs), 3 were in-field, 9 were marginal, and 12 were out-of-field. Two of the 3 in-field LRRs were marginal misses of the additional boost XRT dose. Out-of-field LRRs consisted of six supraclavicular and six internal mammary nodal recurrences. Most LRRs in our study occurred in areas not fully covered by the prescribed XRT dose or were purposely excluded from the original XRT fields. Our data suggest that XRT technique, field design, and dose play a critical role in preventing LRR in women with breast cancer.

Spatial-Temporal [18F]FDG-PET Features for Predicting Pathologic Response of Esophageal Cancer to Neoadjuvant Chemoradiation Therapy

To extract and study comprehensive spatial-temporal (18)F-labeled fluorodeoxyglucose ([(18)F]FDG) positron emission tomography (PET) features for the prediction of pathologic tumor response to neoadjuvant chemoradiation therapy (CRT) in esophageal cancer. Twenty patients with esophageal cancer were treated with trimodal therapy (CRT plus surgery) and underwent [(18)F]FDG-PET/CT scans both before (pre-CRT) and after (post-CRT) CRT. The 2 scans were rigidly registered. A tumor volume was semiautomatically delineated using a threshold standardized uptake value (SUV) of ≥2.5, followed by manual editing. Comprehensive features were extracted to characterize SUV intensity distribution, spatial patterns (texture), tumor geometry, and associated changes resulting from CRT. The usefulness of each feature in predicting pathologic tumor response to CRT was evaluated using the area under the receiver operating characteristic curve (AUC) value. The best traditional response measure was decline in maximum SUV (SUVmax; AUC, 0.76). Two new intensity features, decline in mean SUV (SUVmean) and skewness, and 3 texture features (inertia, correlation, and cluster prominence) were found to be significant predictors with AUC values ≥0.76. According to these features, a tumor was more likely to be a responder when the SUVmean decline was larger, when there were relatively fewer voxels with higher SUV values pre-CRT, or when [(18)F]FDG uptake post-CRT was relatively homogeneous. All of the most accurate predictive features were extracted from the entire tumor rather than from the most active part of the tumor. For SUV intensity features and tumor size features, changes were more predictive than pre- or post-CRT assessment alone. Spatial-temporal [(18)F]FDG-PET features were found to be useful predictors of pathologic tumor response to neoadjuvant CRT in esophageal cancer.

Oncology imaging in the abdomen and pelvis: where cancer hides

As the incidence of cancer continues to increase, imaging will play an ever more important role in the detection, diagnosis, staging, surveillance, and therapeutic monitoring of cancer. Diagnostic errors in the initial discovery of cancer or at follow-up assessments can lead to missed opportunities for curative treatments or altering or reinitiating therapies, as well as adversely impact clinical trials. Radiologists must have an understanding of cancer biology, treatments, and imaging appearance of therapeutic effects and be mindful that metastatic disease can involve virtually any organ system. Knowledge of patient history and tumor biology allows for optimizing imaging protocols. The majority of cancer imaging utilizes computed tomography, where contrast enhancement characteristics of lesions can be exploited and detection of subtle lesions can involve manipulation of window width and level settings, multiplanar reconstruction, and maximum intensity projections. For magnetic resonance imaging, diffusion-weighted imaging can render lesions more conspicuous, improve characterization, and help assess therapeutic response. Positron emission tomography with (18)F-labeled fluorodeoxyglucose and sodium fluoride are invaluable in detecting occult existing and new cancerous lesions, characterizing indeterminate lesions, and assessing treatment effects. The most common anatomic "hiding places" for cancer include metastases to solid organs, such as the kidneys and pancreas, gastrointestinal tract, peritoneum and retroperitoneum, neural axis, muscular body wall, and bones. Consistent work habits, employment of appropriate technologies, and particular attention to the above anatomic areas can enhance detection, staging, and reassessments of these complex and often stealthy diseases, ensuring the radiologists' integral role in the cancer care team.

Molecular imaging: challenges of bringing imaging of intracellular targets into common clinical use

Molecular imaging (MI) takes advantage of several new techniques to detect biomarkers or biochemical and cellular processes, with the goal of obtaining high sensitivity, specificity and signal-to-noise ratio imaging of disease. The imaging modalities bearing the most promise for MI are positron emission tomography (PET), single photon emission computer tomography (SPECT) and different optical imaging techniques with high sensitivity. Also magnetic resonance imaging (MRI) with contrast agents like ultra-small superparamagnetic iron oxide particles (USPIO), magnetic resonance spectroscopy and ultrasound imaging with contrast agents may be useful approaches. MI techniques have been used in the clinic for many years, i.e. PET imaging using (18) F-labeled fluorodeoxyglucose. Animal studies have during the last years revealed great potential for MI also with several other agents. The focus of the present article is the challenges of clinical imaging of intracellular targets following intravenous injection of the agents. Thus, the great challenge of getting enough contrast agent into the cytosol and at the same time obtaining a low signal from tissue just outside the diseased area is discussed.

Tumor Metabolism and Perfusion in Head and Neck Squamous Cell Carcinoma: Pretreatment Multimodality Imaging With 1H Magnetic Resonance Spectroscopy, Dynamic Contrast-Enhanced MRI, and [ 18F]FDG-PET

To correlate proton magnetic resonance spectroscopy ((1)H-MRS), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and (18)F-labeled fluorodeoxyglucose positron emission tomography ([(18)F]FDG PET) of nodal metastases in patients with head and neck squamous cell carcinoma (HNSCC) for assessment of tumor biology. Additionally, pretreatment multimodality imaging was evaluated for its efficacy in predicting short-term response to treatment. Metastatic neck nodes were imaged with (1)H-MRS, DCE-MRI, and [(18)F]FDG PET in 16 patients with newly diagnosed HNSCC, before treatment. Short-term patient radiological response was evaluated at 3 to 4 months. Correlations among (1)H-MRS (choline concentration relative to water [Cho/W]), DCE-MRI (volume transfer constant [K(trans)]; volume fraction of the extravascular extracellular space [v(e)]; and redistribution rate constant [k(ep)]), and [(18)F]FDG PET (standard uptake value [SUV] and total lesion glycolysis [TLG]) were calculated using nonparametric Spearman rank correlation. To predict short-term responses, logistic regression analysis was performed. A significant positive correlation was found between Cho/W and TLG (ρ = 0.599; p = 0.031). Cho/W correlated negatively with heterogeneity measures of standard deviation std(v(e)) (ρ = -0.691; p = 0.004) and std(k(ep)) (ρ = -0.704; p = 0.003). Maximum SUV (SUVmax) values correlated strongly with MRI tumor volume (ρ = 0.643; p = 0.007). Logistic regression indicated that std(K(trans)) and SUVmean were significant predictors of short-term response (p < 0.07). Pretreatment multimodality imaging using (1)H-MRS, DCE-MRI, and [(18)F]FDG PET is feasible in HNSCC patients with nodal metastases. Additionally, combined DCE-MRI and [(18)F]FDG PET parameters were predictive of short-term response to treatment.

Molecular Imaging and Pharmacokinetic Analysis of Carbon-11 Labeled Antisense Oligonucleotide LY2181308 in Cancer Patients

Antisense oligonucleotides (ASOs) have potential as anti-cancer agents by specifically modulating genes involved in tumorigenesis. However, little is known about ASO biodistribution and tissue pharmacokinetics (PKs) in humans, including whether sufficient delivery to target tumor tissue may be achieved. In this preliminary study in human subjects, we used combined positron emission and computed tomography (PET-CT) imaging and subsequent modeling analysis of acquired dynamic data, to examine the in vivo biodistribution and PK properties of LY2181308 - a second generation ASO which targets the apoptosis inhibitor protein survivin. Following radiolabeling of LY2181308 with methylated carbon-11 ([(11)C]methylated-LY2181308), micro-doses (<1mg) were administered to three patients with solid tumors enrolled in a phase I trial. Moderate uptake of [(11)C]methylated-LY2181308 was observed in tumors (mean=32.5ng*h /mL, per mg administered intravenously). Highest uptake was seen in kidney and liver and lowest uptake was seen in lung and muscle. One patient underwent repeat analysis on day 15 of multiple dose therapy, during administration of LY2181308 (750mg), when altered tissue PKs and a favorable change in biodistribution was seen. [(11)C]methylated-LY2181308 exposure increased in tumor, lung and muscle, whereas renal and hepatic exposure decreased. This suggests that biological barriers to ASO tumor uptake seen at micro-doses were overcome by therapeutic dosing. In addition, (18)F-labeled fluorodeoxyglucose (FDG) scans carried out in the same patient before and after treatment showed up to 40% decreased tumor metabolism. For the development of anti-cancer ASOs, the results provide evidence of LY2181308 tumor tissue delivery and add valuable in vivo pharmacological information. For the development of novel therapeutic agents in general, the study exemplifies the merits of applying PET imaging methodology early in clinical investigations.

The Effects of Xenon Anesthesia on the Relationship Between Cerebral Glucose Metabolism and Blood Flow in Healthy Subjects: A Positron Emission Tomography Study

General anesthetics can alter the relationship between regional cerebral glucose metabolism (rCMR(glc)) and blood flow (rCBF). In this positron emission tomography study, our aim was to assess both rCMR(glc) and rCBF in the same individuals during xenon anesthesia. (18)F-labeled fluorodeoxyglucose and (15)O-labeled water were used to determine rCMR(glc) and rCBF, respectively, in five healthy male subjects at baseline (awake) and during 1 minimum alveolar anesthetic concentration of xenon. Anesthesia was based solely on xenon. Changes in rCMR(glc) and rCBF were quantified using region-of-interest and voxel-based analyses. The mean (sd) xenon concentration during anesthesia was 67.2 (0.8)%. Xenon anesthesia induced a uniform reduction in rCMR(glc), whereas rCBF decreased in 7 of 13 brain regions. The mean decreases in the gray matter were 32.4 (4.0)% (P < 0.001) and 14.8 (5.9)% (P = 0.007) for rCMR(glc) and rCBF, respectively. rCMR(glc) decreased by 10.9 (6.4)% in the white matter (P = 0.030), whereas rCBF increased by 9.2 (7.3)% (P = 0.049). The rCBF/rCMR(glc) ratio was especially increased in the insula, anterior and posterior cingulate, and in the somatosensory cortex. In general, the magnitude of the decreases in rCMR(glc) during 1 minimum alveolar anesthetic concentration xenon anesthesia exceeded the reductions in rCBF. As a result, the ratio between rCMR(glc) and rCBF was shifted to a higher level. Interestingly, xenon-induced changes in cerebral metabolism and blood flow resemble those induced by volatile anesthetics.

Preoperative staging of biliary carcinoma using 18F-fluorodeoxyglucose PET: prospective comparison with PET+CT, MDCT and histopathology

The aim of this study was to evaluate the value of positron emission tomography with (18)F-labeled fluorodeoxyglucose (FDG-PET) as a preoperative diagnostic investigation in patients with biliary carcinoma. Seventy-two patients with potentially resectable biliary carcinoma underwent preoperative multidetector-row computed tomography (MDCT) and FDG-PET. Both diagnoses were compared with subsequent histopathology and follow-up results. In 64 lesions with biliary carcinoma, 57 (89%) revealed an intense focal accumulation on FDG-PET and were interpreted as malignant. On the other hand, eight benign lesions did not show any specific accumulation. Detection rate of FDG-PET in the nodular type of the tumour (96% or 27/28) was superior to that of the infiltrating type (74% or 17/23) (p = 0.037). For the evaluation of lymph node metastasis, the overall accuracy was 69% (35/51) in both FDG-PET and MDCT: FDG-PET had a lower sensitivity (33% vs. 57%) and a higher specificity (97% vs. 79%) than MDCT, although the values were not significantly different. FDG-PET revealed all six lesions of distant metastases in six patients including two lesions missed by MDCT. FDG-PET has high detectability of biliary malignancies. Like MDCT, FDG-PET offers only modest accuracy for regional lymph node staging, but it may reveal distant metastases missed by MDCT.

Concurrent CBF and CMRGlc changes during human brain activation by combined fMRI–PET scanning

A novel approach for concurrent measurement of regional cerebral blood flow (CBF) and regional cerebral metabolic rate for glucose consumption (CMRGlc) in humans is proposed and validated in normal subjects during visual stimulation. 18F-labeled fluorodeoxyglucose was administered during the measurement of CBF by continuous arterial spin labeled magnetic resonance imaging (MRI). Subsequent positron emission tomographic (PET) scanning demonstrated the distribution of labeled deoxyglucose during the MRI acquisition. An excellent concordance between regional CBF and regional CMRGlc during visual stimulation was found, consistent with previously published PET findings. Although initially validated using a brief, non-quantitative protocol, this approach can provide quantitative CBF and CMRGlc, with a broad range of potential applications in functional physiology and pathophysiology.