AE hepatic lesions: correlation between calcifications at CT and FDG-PET/CT metabolic activity.

PURPOSE: To correlate the presence of calcifications in alveolar echinococcosis (AE) hepatic lesions to the metabolic activity in 18 fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT). METHODS: Our institutional review board approved this study. 61 patients (29 women, 32 men, aged from 15 to 86 years) were included in the study. Images of FDG-PET/CT were interpreted by two independent nuclear medicine physicians. AE hepatic lesions were classified as AE lesions with or without hypermetabolic activity. The presence of calcifications was assessed on unenhanced CT scans by two independent radiologists blinded with regard to the metabolic activity of the AE hepatic lesions. Every single calcification the size of which was < 3 mm and non-measurable calcifications which were forming areas with a powdery appearance were considered as microcalcifications. All other types of calcifications were reported as macrocalcifications. Statistical analysis was performed and p value < 0.05 was considered as statistically significant. RESULTS: Microcalcifications and macrocalcifications were present at CT in 95% (58/61) AE hepatic lesions and 43% (26/61) AE hepatic lesions, respectively. Hypermetabolic activity was present at FDG-PET/CT in 93% (57/61) AE hepatic lesions. 98% (56/57) of the AE hepatic lesions presenting with hypermetabolic activity at FDG-PET/CT showed microcalcifications at CT (p = 0.01) when only 40% (23/57) showed macrocalcifications at CT (p = 0.3). 100% (23/23) of the AE hepatic lesions with hypermetabolic activity at FDG-PET/CT and macrocalcifications at CT showed also microcalcifications at CT. CONCLUSIONS: Hypermetabolic activity of AE hepatic lesions at FDG-PET/CT is strongly correlated to the presence of microcalcifications at CT, independently of the presence of macrocalcifications.

Hints for control of infection in unique extrahepatic vertebral alveolar echinococcosis.

The prognosis of vertebral alveolar echinococcosis (AE) is poor. We report on the unique outcome of a patient with preexisting liver cirrhosis, in whom a diagnosis of vertebral AE was established on vertebral histopathology (D4 corporectomy in 2010 for paraplegia). Therapeutic drug monitoring of albendazole (ABZ) showed that a low dosage was appropriate. The patient recovered and ABZ withdrawal was decided in 2014, with no relapse 18 months later. In this patient, infection was purely or mainly localized in the dorsal spine, and this may have been favored by liver cirrhosis. A longer follow-up is, however, needed to confirm cure.

Utility of 18F-fluoro-dexoxyglucose positron emission tomography for the diagnosis of polymyalgia rheumatica: a controlled study.

OBJECTIVES: To compare (18)F-fluoro-dexoxyglucose PET/CT (FDG-PET/CT) findings in patients with polymyalgia rheumatica (PMR) and controls without rheumatologic disease. METHODS: We retrospectively included 50 patients with a diagnosis of PMR as well as 53 patients with a neoplasm as a control group. All patients underwent FDG-PET/CT. Seventeen hotspots were analysed. We performed a semi-quantitative analysis of FDG uptake (4-point score from 0 to 3). The cut-offs for the number of sites with high activity and for FDG uptake score were assessed using receiver operating characteristics curves and odds ratios (ORs). RESULTS: The two groups were comparable for the median patient age (69.3 years for PMR vs 68.1 for controls). Significant differences between the two groups were found for FDG uptake score (1.12 vs 0.34, P < 0.00001) and for the number of sites with significant uptake (score ⩾ 2): 6.36 sites vs 1.49 sites (P < 0.00001). The presence of three or more sites with significant uptake was correlated with the diagnosis of PMR with 74% sensitivity and 79% specificity (OR = 10.8). For the FDG uptake score, the cut-off was 0.53 (sensitivity 80%, specificity 77%, OR = 13.6). We found significant differences in all sites for FDG uptake score and the number of sites with significant uptake, particularly marked for shoulders, ischial tuberosities and interspinous bursitis (P < 0.00001 for FDG uptake score). CONCLUSION: Our results suggest that the number of sites with significant FDG uptake and the uptake score could be relevant criteria for the diagnosis of PMR.

Alveolar echinococcosis: correlation between hepatic MRI findings and FDG-PET/CT metabolic activity.

OBJECTIVE: To correlate the appearance of alveolar echinococcosis (AE) hepatic lesions in magnetic resonance imaging (MRI) as defined by Kodama, to the metabolic activity visualized in 18-fluoro-deoxyglucose positron emission tomography combined with computed tomography (PET/CT). MATERIALS AND METHODS: Forty-two patients diagnosed with AE and who underwent both MRI and PET/CT were included. The forty-two hepatic lesions were divided into five types according to Kodama's classification by three independent readers blinded with regard to the PET/CT information. Concerning PET/CT, two independent readers, unaware of the MRI information, considered the results as positive when an increased FDG-uptake was observed at 1 or 3 h after FDG-injection, and as negative when no increased uptake was noted. Inter-observer agreement was assessed by using κ statistics. RESULTS: Forty-two lesions were counted and the mean diameter of overall evaluated lesions was 6.3 cm. One lesion (2.4%) was categorized as type 1, 11 (26.2%) as type 2, 24 (57.1%) as type 3, 3 (7.1%) as type 4, and 3 (7.1%) as type 5. The inter-observer analysis found a κ coefficient of 0.96. All type-1, 90.9% of type-2 and 87.5% of type-3 lesions showed an increased FDG-uptake on PET/CT images. All non-microcystic AE liver lesions (types 4 and 5) showed no abnormal increased FDG-uptake on PET/CT images. The inter-observer analysis at 1 and 3 h found a κ coefficient of 0.95 and 0.92, respectively. CONCLUSIONS: In patients with AE liver lesions, the absence of microcysts on MRI is strongly correlated to a metabolically inactive disease.

Increased incidence and characteristics of alveolar echinococcosis in patients with immunosuppression-associated conditions.

BACKGROUND: An increased incidence of alveolar echinococcosis (AE) in patients with immunosuppression (IS) has been observed; our aim was to study this association and its characteristics. METHODS: Fifty AE cases with IS-associated conditions (ISCs) before or at AE diagnosis were collected from the French AE registry (1982-2012, 509 cases). There were 30 cancers, 9 malignant hematological disorders, 14 chronic inflammatory diseases, 5 transplants, and 1 case of AIDS; 9 patients had ≥2 ISCs. Characteristics of the 42 IS/AE cases and the 187 non-IS/AE cases diagnosed during the period 2002-2012 were statistically compared. RESULTS: There was a significant increase in IS/AE cases over time. Risk factors did not differ between IS/AE and non-IS/AE patients. However, AE was more frequently an incidental finding (78% vs 42%) and was diagnosed at earlier stages (41% vs 23%) in IS/AE than in non-IS/AE patients. Serology was more often negative (14% vs 1%) and treatment efficacy was better (51% regression after 1-year treatment vs 27%) in IS/AE patients. All IS/AE patients but 7 took IS drugs; 7 received biotherapeutic agents. When not concomitant, AE occurred in IS patients within a 48-month median time period. Atypical presentation and abscess-, hemangioma-, and metastasis-like images delayed AE diagnosis in 50% of IS/AE patients, resulting in inappropriate treatment. Liver images obtained for 15 patients 1-5 years before diagnosis showed no AE lesions. Albendazole efficacy was good, but 19 of 48 treated patients experienced side effects. CONCLUSIONS: Patients with immunosuppression are at increased risk for occurrence, delayed diagnosis, and progression of AE.

30-yr course and favorable outcome of alveolar echinococcosis despite multiple metastatic organ involvement in a non-immune suppressed patient.

We report the 30-yr history of a well-documented human case of alveolar echinococcosis, with a lung lesion at presentation followed by the discovery of a liver lesion, both removed by surgery. Subsequently, within the 13 years following diagnosis, metastases were disclosed in eye, brain and skull, as well as additional lung lesions. This patient had no immune suppression, and did not have the genetic background known to predispose to severe alveolar echinococcosis; it may thus be hypothesized that iterative multi-organ involvement was mostly due to the poor adherence to benzimidazole treatment for the first decade after diagnosis. Conversely, after a new alveolar echinococcosis recurrence was found in the right lung in 1994, the patient accepted to take albendazole continuously at the right dosage. After serology became negative and a fluoro-deoxy-glucose-Positron Emission Tomography performed in 2005 showed a total regression of the lesions in all organs, albendazole treatment could be definitively withdrawn. In 2011, the fluoro-deoxy-glucose-Positron Emission Tomography showed a total absence of parasitic metabolic activity and the patient had no clinical symptoms related to alveolar echinococcosis.The history of this patient suggests that multi-organ involvement and alveolar echinococcosis recurrence over time may occur in non-immune suppressed patients despite an apparently "radical" surgery. Metastatic dissemination might be favored by a poor adherence to chemotherapy. Combined surgery and continuous administration of albendazole at high dosage may allow alveolar echinococcosis patients to survive more than 30 years after diagnosis despite multi-organ involvement.

Should possible recurrence of disease contraindicate liver transplantation in patients with end-stage alveolar echinococcosis? A 20-year follow-up study.

Liver transplantation (LT) is currently contraindicated in patients with residual or metastatic alveolar echinococcosis (AE) lesions. We evaluated the long-term course of such patients who underwent LT and were subsequently treated with benzimidazoles. Clinical, imaging, serological, and therapeutic data were collected from 5 patients with residual/recurrent AE lesions who survived for more than 15 years. Since 2004, [(18) F]-2-fluoro-2-deoxyglucose (FDG)-positron emission tomography (PET) images were available, and the levels of serum antibodies (Abs) against Echinococcus multilocularis-recombinant antigens were evaluated. Median survival time after LT was 21 years. These patients were from a prospective cohort of 23 patients with AE who underwent LT: 5 of 8 patients with residual/recurrent AE and 4 of 9 patients without residual/recurrent AE were alive in September 2009. High doses of immunosuppressive drugs, the late introduction of therapy with benzimidazoles, its withdrawal due to side effects, and nonadherence to this therapy adversely affected the prognosis. Anti-Em2(plus) and anti-rEm18 Ab levels and standard FDG-PET enabled the efficacy of therapy on the growth of EA lesions to be assessed. However, meaningful variations in Ab levels were observed below diagnostic cutoff values; and in monitoring AE lesions, images of FDG uptake taken 3 hours after its injection were more sensitive than images obtained 1 hour after its injection. In conclusion, benzimidazoles can control residual/recurrent AE lesions after LT. Using anti-rEm18 or anti-Em2(plus) Ab levels and the delayed acquisition of FDG-PET images can improve the functional assessment of disease activity. The potential recurrence of disease, especially in patients with residual or metastatic AE lesions, should not be regarded as a contraindication to LT when AE is considered to be lethal in the short term.

Circulating cell-free DNA in patients with alveolar echinococcosis.

Alveolar echinococcosis (AE) is a parasitic disease, due to Echinococcus multilocularis. Often compared to liver cancer, it develops by infiltration from its primary site to the surrounding tissue, and can then metastasize to other organs. Detection of circulating cell-free DNA (ccfDNA) is a useful analytical tool in oncology, for diagnosis, prognosis, and therapy monitoring. This study sought to investigate the presence of ccfDNA in patients with AE, and its potential usefulness for the evaluation of treatment efficiency. To achieve these aims, a quantitative PCR and a droplet digital PCR were developed to detect E. multilocularis ccfDNA. An AE animal model identified, for the first time, the presence of large quantities of ccfDNA. Samples from patients with AE (n = 31) were then analyzed twice, at diagnosis, and after three months of chemotherapy: about 25% were positive, almost always with very low concentrations of ccfDNA. These results confirmed that E. multilocularis produces ccfDNA, as solid tumors do, but detection may not yet be sufficient for AE diagnosis nor for the evaluation of treatment efficiency, due to the low levels of ccfDNA detected in patient serum.

Imaging aspects and non-surgical interventional treatment in human alveolar echinococcosis.

Alveolar echinococcosis (AE) of the liver caused by the metacestode of the fox tapeworm Echinococcus multilocularis is characterized by a multivesicular structure surrounded by an extensive fibro-inflammatory host reaction. The lesions behave like a slow-growing liver cancer, without sharp limits between the parasitic tissue and the liver parenchyma. Invasion of biliary and vascular walls is another hallmark of this severe disease. Moreover, the poor vascularization of the parasitic mass often leads to necrosis in the central part of the lesion. This explains why liver abscess due to superimposed bacterial infection of the necrotic area may occur in this disease. Currently, a range of imaging techniques can be used at the different stages of management of AE. For diagnosis, ultrasonography remains the first line examination. For a more accurate disease evaluation, aiming to guide the surgical strategy, computerized tomography, Magnetic Resonance (MR) imaging, including cholangio-MR imaging are of importance, providing useful complementary information. More recently, Positive-Emission Tomography using [18F] fluoro-deoxyglucose has been developed for the follow-up of inoperable AE patients under long-term benzimidazoles therapy. This approach seems very promising to assess inflammatory activity and thereby to indirectly depict parasitic activity. Non-surgical interventional procedures, mainly percutaneous biliary and/or centro-parasitic abscesses drainages, are currently a major aspect in the care of incurable AE patients and have largely contributed to the improvement of survival in this situation during the past 20 years. They may also be used as a bridge before a curative surgical procedure in symptomatic patients presenting a life-threatening bacterial and/or fungal infection. It is also very useful in inoperable patients to overcome similar infectious episodes.

Current interventional strategy for the treatment of hepatic alveolar echinococcosis.

INTRODUCTION: The use of various types of invasive interventions combined with anti-infective drugs in the therapeutic strategy of alveolar echinococcosis (AE) has changed during the last 30 years. Areas covered: This article reviews the current respective indications of surgical, percutaneous and perendoscopic interventions in AE and proposes an integrative therapeutic strategy. Expert commentary: Hepatic resection is indicated whenever it is feasible and curative; palliative surgery should be avoided; percutaneous procedures are best adapted to the drainage of the necrotic cavity present in advanced cases; perendoscopic procedures with stenting are best adapted to alleviating the biliary complications that are common and life-threatening in AE patients. Continuous administration of albendazole or mebendazole, without interruption is mandatory in all cases, temporarily (recommended duration: 2 years) after radical lesion resection in patients without immune suppression; for life in all other cases. Long-term follow-up is essential.

Deletion of Fibrinogen-like Protein 2 (FGL-2), a Novel CD4+ CD25+ Treg Effector Molecule, Leads to Improved Control of Echinococcus multilocularis Infection in Mice.

BACKGROUND: The growth potential of the tumor-like Echinococcus multilocularis metacestode (causing alveolar echinococcosis, AE) is directly linked to the nature/function of the periparasitic host immune-mediated processes. We previously showed that Fibrinogen-like-protein 2 (FGL2), a novel CD4+CD25+ Treg effector molecule, was over-expressed in the liver of mice experimentally infected with E. multilocularis. However, little is known about its contribution to the control of this chronic helminth infection. METHODS/FINDINGS: Key parameters for infection outcome in E. multilocularis-infected fgl2-/- (AE-fgl2-/-) and wild type (AE-WT) mice at 1 and 4 month(s) post-infection were (i) parasite load (i. e. wet weight of parasitic metacestode tissue), and (ii) parasite cell proliferation as assessed by determining E. multilocularis 14-3-3 gene expression levels. Serum FGL2 levels were measured by ELISA. Spleen cells cultured with ConA for 48h or with E. multilocularis Vesicle Fluid (VF) for 96h were analyzed ex-vivo and in-vitro. In addition, spleen cells from non-infected WT mice were cultured with rFGL2/anti-FGL2 or rIL-17A/anti-IL-17A for further functional studies. For Treg-immune-suppression-assays, purified CD4+CD25+ Treg suspensions were incubated with CD4+ effector T cells in the presence of ConA and irradiated spleen cells as APCs. Flow cytometry and qRT-PCR were used to assess Treg, Th17-, Th1-, Th2-type immune responses and maturation of dendritic cells. We showed that AE-fgl2-/- mice exhibited (as compared to AE-WT-animals) (a) a significantly lower parasite load with reduced proliferation activity, (b) an increased T cell proliferative response to ConA, (c) reduced Treg numbers and function, and (d) a persistent capacity of Th1 polarization and DC maturation. CONCLUSIONS: FGL2 appears as one of the key players in immune regulatory processes favoring metacestode survival by promoting Treg cell activity and IL-17A production that contributes to FGL2-regulation. Prospectively, targeting FGL2 could be an option to develop an immunotherapy against AE and other chronic parasitic diseases.

Poststress motionlike artifacts caused by the use of a dual-head gamma camera for (201)Tl myocardial SPECT.

UNLABELLED: When performing (201)Tl myocardial SPECT using a dual-head gamma camera on patients after exercise stress, we have observed in some a sudden increase in the counting rate between the 16th and 17th images. This increase provoked motionlike artifacts, which increased the number of false-positive findings. The aim of our study was to determine possible causes for this leap in activity. METHODS: We performed myocardial SPECT using a dual-head gamma camera on 110 patients after exercise stress: in 38 patients approximately 5 min after injection (group 1), in 43 patients approximately 14 min after injection (group 2), and in 29 patients twice, at approximately 5 and 20 min after injection (group 3). We also performed dynamic data acquisition for 10 min on 18 patients after exercise stress. We compared activity in the heart region in image series obtained after exercise stress and at rest. RESULTS: Daily quality control tests eliminated the possibility of any malfunctions of the gamma camera. Careful image analysis showed no visible patient motion. Our results showed that upward creep of the heart could not be a cause of the described phenomenon. After exercise stress, a > or = 5% activity leap in the heart region on the 16th and 17th frames was more frequent in group 1 than in group 2. Two consecutive acquisitions after exercise stress showed that the leap was >5% in 24 patients (83%) and 12 patients (41%) at the first and second acquisitions, respectively (group 3). In all patients, the leap was <5% at rest. Dynamic studies showed that the activity in the heart region steadily decreased in all patients after exercise stress. We suggest that decreasing (201)Tl concentrations in myocardium or blood could be a major reason for the described artifacts. CONCLUSION: We proposed that the pharmacokinetics of (201)Tl-chloride be evaluated within a short time after injection in humans after exercise stress. Now, in our department, we have begun acquisition approximately 12 min after (201)Tl administration, and the above-mentioned phenomenon has not appeared. However, to avoid the artifacts caused by early redistribution of (201)Tl, acquisition must not begin too late.

Virtual firm in biomedical education: a very successful experience.

In May 2006, the Institut Superieur d'Ingenieurs de Franche-Comté (ISIFC) launched its own virtual firm, which was named Biotika® by students. Virtual means that this company has no real legal status. It is a pedagogic model; however, the situation scenario for the ISIFC student engineers is real. They are currently working in real conditions on the development of new medical devices and on the modernization of medical products. The need for these innovative medical devices was identified by the students during their second-year (6 weeks) internship in hospitals. Biotika® is open between March and December every year. The students are "recruited" following an imitation job interview and each is then entrusted with a mission (engineer, project manager etc.) in one of the company's four departments: Research & Design, Quality-regulatory affairs, Clinical investigations, and Public relations-marketing. The personnel of Biotika® work on the development of innovative medical devices and/or the preparation of CE or FDA certification for 2 days per week. Since its launch, Biotika® has developed eight products and obtained many grants and prizes from French research and governmental organizations. It is also certified ISO 13485.

Echinococcus metacestode: in search of viability markers.

Epidemiological studies have demonstrated that most humans infected with Echinococcus spp. exhibit resistance to disease. When infection leads to disease, the parasite is partially controlled by host immunity: in case of immunocompetence, the normal alveolar echinococcosis (AE) or cystic echinococcosis (CE) situation, the metacestode grows slowly, and first clinical signs appear years after infection; in case of impaired immunity (AIDS; other immunodeficiencies), uncontrolled proliferation of the metacestode leads to rapidly progressing disease. Assessing Echinococcus multilocularis viability in vivo following therapeutic interventions in AE patients may be of tremendous benefit when compared with the invasive procedures used to perform biopsies. Current options are F18-fluorodeoxyglucose-positron emission tomography (FDG-PET), which visualizes periparasitic inflammation due to the metabolic activity of the metacestode, and measurement of antibodies against recEm18, a viability-associated protein, that rapidly regresses upon metacestode inactivation. For Echinococcus granulosus, similar prognosis-associated follow-up parameters are still lacking but a few candidates may be listed. Other possible markers include functional and diffusion-weighted Magnetic Resonance Imaging (MRI), and measurement of products from the parasite (circulating antigens or DNA), and from the host (inflammation markers, cytokines, or chemokines). Even though some of them have been promising in pilot studies, none has been properly validated in an appropriate number of patients until now to be recommended for further use in clinical settings. There is therefore still a need to develop reliable tools for improved viability assessment to provide the sufficient information needed to reliably withdraw anti-parasite benzimidazole chemotherapy, and a basis for the development of new alternative therapeutic tools.

Transcriptional profiles of cytokine/chemokine factors of immune cell-homing to the parasitic lesions: a comprehensive one-year course study in the liver of E. multilocularis-infected mice.

Pathogenesis of chronically developing alveolar echinococcosis (AE) is characterized by a continuous, granulomatous, periparasitic infiltration of immune cells surrounding the metacestode of Echinococcus multilocularis (E.multilocularis) in the affected liver. A detailed cytokine and chemokine profile analysis of the periparasitic infiltrate in the liver has, however, not yet been carried out in a comprehensive way all along the whole course of infection in E. multilocularis intermediate hosts. We thus assessed the hepatic gene expression profiles of 18 selected cytokine and chemokine genes using qRT-PCR in the periparasitic immune reaction and the subsequent adjacent, not directly affected, liver tissue of mice from day 2 to day 360 post intra-hepatic injection of metacestode. DNA microarray analysis was also used to get a more complete picture of the transcriptional changes occurring in the liver surrounding the parasitic lesions. Profiles of mRNA expression levels in the hepatic parasitic lesions showed that a mixed Th1/Th2 immune response, characterized by the concomitant presence of IL-12α, IFN-γ and IL-4, was established very early in the development of E. multilocularis. Subsequently, the profile extended to a combined tolerogenic profile associating IL-5, IL-10 and TGF-ß. IL-17 was permanently expressed in the liver, mostly in the periparasitic infiltrate; this was confirmed by the increased mRNA expression of both IL-17A and IL-17F from a very early stage, with a subsequent decrease of IL-17A after this first initial rise. All measured chemokines were significantly expressed at a given stage of infection; their expression paralleled that of the corresponding Th1, Th2 or Th17 cytokines. In addition to giving a comprehensive insight in the time course of cytokines and chemokines in E. multilocularis lesion, this study contributes to identify new targets for possible immune therapy to minimize E. multilocularis-related pathology and to complement the only parasitostatic effect of benzimidazoles in AE.

Neuropsychological and neuroimaging phenotype induced by a CAMTA1 mutation.

BACKGROUND/AIMS: CAMTA1 mutations have recently been reported in families with intellectual disability and/or non-progressive congenital ataxias. The objective of this study was to describe the neuropsychological and neuroimaging phenotype of CAMTA1 mutation. METHODS: We performed neuropsychological examinations, MRI and FDG-PET imaging in three patients with autosomal dominant mild intellectual disabilities and ataxia induced by a CAMTA1 intragenic deletion at 1p36.31p36.23. RESULTS: Neuropsychological tests showed similar findings in two patients, with low information processing speed, slow memory consolidation, phonological disorders, working memory deficits, but mainly preserved executive function. Bilateral parietal and medial temporal abnormalities were found on brain MRI. Diffuse parieto-occipital and local left temporo-parietal decrease of FDG uptake was observed on PET images. CONCLUSION: These results suggest that CAMTA1 mutation may induce an unusual neuropsychological profile and parieto-temporal developmental abnormalities. We recommend screening for CAMTA1 mutations in patients with autosomal dominant mild intellectual disability presenting with similar a phenotype.

Innovation in hepatic alveolar echinococcosis imaging: best use of old tools, and necessary evaluation of new ones.

Hepatic Alveolar Echinococcosis (HAE), caused by larvae of Echinococcus multilocularis, is a rare but potentially lethal parasitic disease. The first diagnostic suspicion is usually based on hepatic ultrasound exam performed because of abdominal symptoms or in the context of a general checkup; HAE diagnosis may thus also be an incidental finding on imaging. The next step should be Computed Tomography (CT) or Magnetic Resonance Imaging (MRI). They play an important role in the initial assessment of the disease; with chest and brain imaging, they are necessary to assess the PNM stage (parasite lesion, neighboring organ invasion, metastases) of a patient with AE. Performed at least yearly, they also represent key exams for long-term follow-up after therapeutic interventions. Familiarity of radiologists with HAE imaging findings, especially in the endemic regions, will enable earlier diagnosis and more effective treatment. Fluorodeoxyglucose Positron Emission Tomography (FDG-PET) is currently considered to be the only noninvasive, albeit indirect, tool for the detection of metabolic activity in AE. Delayed acquisition of images (3 hrs after FDG injection) enhances its sensitivity for the assessment of lesion metabolism and its reliability for the continuation/withdrawal of anti-parasite treatment. However, sophisticated equipment and high cost widely limit PET/CT use for routine evaluation. Preliminary studies show that new techniques, such as contrast-enhanced ultrasound (US), Dual Energy CT or Spectral CT, and Diffusion-Weighted MRI, might also be useful in detecting the blood supply and metabolism of lesions. However, they cannot be recommended before further evaluation of their reliability in a larger number of patients with a variety of locations and stages of AE lesions.

Development of a specific tracer for metabolic imaging of alveolar echinococcosis: A preclinical study.

Positron emission tomography (PET)-computed tomography (CT) using [18F]-fluorodeoxyglucose (FDG) (FDG-PET/CT) is a valuable method for initial staging and follow up of patients with alveolar echinococcosis (AE). However, the cells responsible for FDG uptake have not been clearly identified. The main goal of our study was to evaluate the uptake of PET tracers by the cells involved in the host-parasite reaction around AE lesions as the first step to develop a specific PET tracer that would allow direct assessment of parasite viability in AE. Candidate molecules ([18F]-fluorotyrosine (FET), [18F]-fluorothymidine (FLT), and [18F]-fluorometylcholine (FMC), were compared to FDG by in vitro studies on human leukocytes and parasite vesicles. Our results confirmed that FDG was mainly consumed by immune cells and showed that FLT was the best candidate tracer for parasite metabolism. Indeed, parasite cells exhibited high uptake of FLT. We also performed PET/CT scans in mice infected intraperitoneally with E. multilocularis metacestodes. PET images showed no FDG or FLT uptake in parasitic lesions. This preliminary study assessed the metabolic activity of human leukocytes and AE cells using radiolabeling. Future studies could develop a specific PET tracer for AE lesions to improve lesion detection and echinococcosis treatment in patients. Our results demonstrated that a new animal model is needed for preclinical PET imaging to better mimic human hepatic and/or periparasitic metabolism.

Granulosa cell tumor of the ovary with high FDG uptake.

Granulosa cell tumor (GCT) of the ovary is a rare tumor accounting for 2%-5% of ovarian malignancies. Although the usefulness of 18F-FDG PET/CT is well demonstrated in the staging and follow-up of the great majority of ovarian cancers, GCTs are known to cause false-negative results on FDG PET because of very low FDG avidity. We present a case of a GCT in which an 18F-FDG PET/CT proved very useful in the detection of recurrence.