Meningiomas are the most frequent nonglial primary brain tumors and represent about 30% of brain tumors. Usually, diagnosis and treatment planning are based on neuroimaging using mainly MRI or, rarely, CT. Most common treatment options are neurosurgical resection and radiotherapy (eg, radiosurgery, external fractionated radiotherapy). For follow-up after treatment, a structural imaging technique such as MRI or CT is used. However, these structural imaging modalities have limitations, particularly in terms of tumor delineation as well as diagnosis of posttherapeutic reactive changes. Molecular imaging techniques such as PET can characterize specific metabolic and cellular features which may provide clinically relevant information beyond that obtained from structural MR or CT imaging alone. Currently, the use of PET in meningioma patients is steadily increasing. In the present article, we provide recommendations for the use of PET imaging in the clinical management of meningiomas based on evidence generated from studies being validated by histology or clinical course.

https://www.zora.uzh.ch/id/eprint/141046/1/N-O-D-17-00255_R2b.pdf

PET imaging in patients with meningioma - Report of the RANO/PET Group

Background: Recent studies have suggested that (18)fluoro-deoxyglucose (FDG) positron emission tomography (PET) may be useful in the work-up of patients with fever of unknown origin (FUO), but its exact diagnostic yield has not been established. Methods: From January 1999 through December 2001, 74 (67%) of 110 prospectively collected patients who fulfilled the revised criteria of classic FUO underwent a FDG-PET scan. The diagnostic yield of this technique was assessed after diagnostic work-up and follow-up. Abnormal FDG-PET scans that pointed to the final diagnosis were categorized as helpful; all other scans were considered noncontributory. Results: A final diagnosis was established in 39 (53%) of the 74 patients who underwent FDG-PET. Fifty-three (72%) of the 74 FDG-PET scans were abnormal; 19 scans (36% of the abnormal scans or 26% of the total number of scans) were helpful. In the 39 patients with a final diagnosis, 49% of the scans were helpful. A diagnosis was established in 31 (58%) of the 53 patients with an abnormal scan and in 8 (38%) of the 21 patients with a normal scan (P=0.2). Baseline clinical variables (age and sex, as well as periodicity, duration, and height of the fever) and inflammatory parameters (erythrocyte sedimentation rate, C-reactive protein, and hemoglobin) did not predict the usefulness of FDG-PET. Conclusions: FDG-PET contributed positively to the diagnosis in a quarter of our patients with classical FUO. This number is lower than that found in previous studies. Yet, against the background of the wide array of heterogeneous disorders that make up the FUO spectrum and the low number of final diagnoses established (in only 53% of cases), the diagnostic yield of FDG-PET is encouraging. Therefore, the use of FDG-PET should be considered whenever a baseline work-up fails to reveal the cause of a prolonged, febrile illness.

Contribution of 18 fluoro-deoxyglucose positron emission tomography to the work-up of patients with fever of unknown origin

Hepatocellular carcinoma (HCC) is an increasing health problem, representing the second cause of cancer-related mortality worldwide. The major risk factor for HCC is cirrhosis. In developing countries, viral hepatitis represent the major risk factor, whereas in developed countries, the epidemic of obesity, diabetes and nonalcoholic steatohepatitis contribute to the observed increase in HCC incidence. Cirrhotic patients are recommended to undergo HCC surveillance by abdominal ultrasounds at 6-mo intervals. The current diagnostic algorithms for HCC rely on typical radiological hallmarks in dynamic contrast-enhanced imaging, while the use of α-fetoprotein as an independent tool for HCC surveillance is not recommended by current guidelines due to its low sensitivity and specificity. Early diagnosis is crucial for curative treatments. Surgical resection, radiofrequency ablation and liver transplantation are considered the cornerstones of curative therapy, while for patients with more advanced HCC recommended options include sorafenib and trans-arterial chemo-embolization. A multidisciplinary team, consisting of hepatologists, surgeons, radiologists, oncologists and pathologists, is fundamental for a correct management. In this paper, we review the diagnostic and therapeutic management of HCC, with a focus on the most recent evidences and recommendations from guidelines.

Diagnostic and therapeutic management of hepatocellular carcinoma.

Dysregulated cellular metabolism is a characteristic feature of malignancy that has been exploited for both imaging and targeted therapy. With regard to imaging, deranged glucose metabolism has been leveraged using 18F-FDG PET. Metabolic imaging with 18F-FDG, however, probes only the early steps of glycolysis; the complexities of metabolism beyond these early steps in this single pathway are not directly captured. New imaging technologies-both PET with novel radiotracers and MR-based methods-provide unique opportunities to investigate other aspects of cellular metabolism and expand the metabolic imaging armamentarium. This review will discuss the underlying biology of metabolic dysregulation in cancer, focusing on glucose, glutamine, and acetate metabolism. Novel imaging strategies will be discussed within this biologic framework, highlighting particular strengths and limitations of each technique. Emphasis is placed on the role that combining modalities will play in enabling multiparametric imaging to fully characterize tumor biology to better inform treatment.

https://jnm.snmjournals.org/content/jnumed/59/9/1340.full.pdf

Imaging Cancer Metabolism: Underlying Biology and Emerging Strategies

[11C]-acetate positron emission tomography is used to assess oxidative metabolism in various tissues including the heart, tumor, and brown adipose tissue. For brown adipose tissue, a monoexponential decay model is commonly employed. However, no systematic assessment of kinetic models has been performed to validate this model or others. The monoexponential decay model and various compartmental models were applied to data obtained before and during brown adipose tissue activation by cold exposure in healthy men. Quality of fit was assessed visually and by analysis of residuals, including the Akaike information criterion. Stability and accuracy of compartmental models were further assessed through simulations, along with sensitivity and identifiability of kinetic parameters. Differences were noted in the arterial input function between the warm and cold conditions. These differences are not taken into account by the monoexponential decay model. They are accounted for by compartmental models, but most models proved too complex to be stable. Two and three-tissue models with no more than four distinct kinetic parameters, including blood volume fraction, provided the best compromise between fit quality and stability/accuracy. For healthy men, a three-tissue model with four kinetic parameters, similar to a heart [11C]-palmitate model seems the most appropriate based on model stability and its ability to describe the main [11C]-acetate pathways in BAT cells. Further studies are required to validate this model in women and people with metabolic disorders.

/pdf/determination-of-a-pharmacokinetic-model-for-11c-acetate-in-2yv4sz2k2c.pdf

Determination of a pharmacokinetic model for [11C]-acetate in brown adipose tissue.

Objective: The kinetic analysis of 11C-acetate PET provides more information than routine one time-point static imaging. This study aims to investigate the potential of dynamic 11C-acetate hepatic PET imaging to improve the diagnosis of hepatocellular carcinoma (HCC) and benign liver lesions by using compartmental kinetic modeling and discriminant analysis.

Methods: Twenty-two patients were enrolled in this study, 6 cases were with well-differentiated HCCs, 7 with poorly-differentiated HCCs and 9 with benign pathologies. Following the CT scan, all patients underwent 11C-acetate dynamic PET imaging. A three-compartment irreversible dual-input model was applied to the lesion time activity curves (TACs) to estimate the kinetic rate constants K1-k3, vascular fraction (VB) and the coefficient α representing the relative hepatic artery (HA) contribution to the hepatic blood supply on lesions and non-lesion liver tissue. The parameter Ki (=K1×k3/(k2 + k3)) was calculated to evaluate the local hepatic metabolic rate of acetate (LHMAct). The lesions were further classified by discriminant analysis with all the above parameters.

Results: K1 and lesion to non-lesion standardized uptake value (SUV) ratio (T/L) were found to be the parameters best characterizing the differences among well-differentiated HCC, poorly-differentiated HCC and benign lesions in stepwise discriminant analysis. With discriminant functions consisting of these two parameters, the accuracy of lesion prediction was 87.5% for well-differentiated HCC, 50% for poorly-differentiated HCC and 66.7% for benign lesions. The classification was much better than that with SUV and T/L, where the corresponding classification accuracy of the three kinds of lesions was 57.1%, 33.3% and 44.4%.

Conclusion: 11C-acetate kinetic parameter K1 could improve the identification of HCC from benign lesions in combination with T/L in discriminant analysis. The discriminant analysis using static and kinetic parameters appears to be a very helpful method for clinical liver masses diagnosis and staging.

/pdf/kinetic-analysis-of-dynamic-11-c-acetate-pet-ct-imaging-as-a-3bkuzxzxqe.pdf

Kinetic analysis of dynamic (11)C-acetate PET/CT imaging as a potential method for differentiation of hepatocellular carcinoma and benign liver lesions.

Objectives
Fever of unknown origin (FUO) remains a challenge in clinical practice. Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is helpful in diagnosing the etiology of FUO. This paper aims to develop a completely automatic classification method based on PET/CT data for the computer-assisted diagnosis of FUO.

/pdf/pet-index-of-bone-glucose-metabolism-pibgm-classification-of-395p6w80qb.pdf

PET Index of Bone Glucose Metabolism (PIBGM) Classification of PET/CT Data for Fever of Unknown Origin Diagnosis

Diffuse increased ¹⁸F-FDG activity is commonly caused by malignant involvement. We describe here cases of diffuse, uniformly increased ¹⁸F-FDG activity due to nonmalignant illnesses in 2 patients: one had parvovirus B19 infection, whereas the other had porphyria, a heme synthesis disorder.

Youjing Zheng

Papers

Kinetic analysis of dynamic (11)C-acetate PET/CT imaging as a potential method for differentiation of hepatocellular carcinoma and benign liver lesions.

PET Index of Bone Glucose Metabolism (PIBGM) Classification of PET/CT Data for Fever of Unknown Origin Diagnosis

Diffuse Hepatic FDG Activity From Nonmalignant Etiologies.