海洋中的凝集网与透明胞外聚合颗粒物

透明胞外聚合颗粒物(TEP)是海洋中大量存在的能被爱尔新蓝(alcian blue)染色的由酸性多糖组成的透明胶状颗粒物,主要来源于浮游植物,由于其透明的特性而被长期忽视。TEP同时具有胶体和颗粒物的特性。作为胶体,TEP为细菌提供了栖息场所与降解基质,同时TEP可以吸收痕量元素,以改变这些元素的生物地球化学过程。作为颗粒物,TEP可以聚集并沉降,由于其高的碳含量,会在很大程度上影响海洋的碳通量。由于TEP可以被中型浮游动物所摄食,所以TEP可以连接并缩短微食物环和经典食物链,在海洋生态系统中起很重要的作用。介绍了TEP的定义、测量方法、来源、形成、及其与浮游植物的关系和其生态功能。     

Primary pleural synovial sarcoma with diffuse pleural involvement: A case report

Synovial sarcoma (SS) is a mesenchymal tumor which generally affects the soft tissues of the extremities. Primary pleural synovial sarcoma (PPSS) is a very rare and aggressive subtype of SS. A 73-year-old male patient presented with chest-back pain and dyspnea. Hypermetabolic diffuse pleural lesions were detected in ¹⁸F-FDG PET/CT performed after pleural nodular thickenings were observed on CT. As the result of the molecular analysis performed in the excisional biopsy, SYT-SSX mutation was detected and the patient was diagnosed as SS. Pazopanib treatment was commenced. We are reporting a very rare case of PPSS with diffuse pleural involvement.     

Optimization of 18F-Choline PET/CT acquisition in prostate cancer: Preliminary results concerning the length of the acquisition

ObjectiveFCH-PET/CT protocol for prostate cancer assessment consists of an early and late acquisition. Concerning the early acquisition, this study compares contrast-to-noise ratio of tumoral lesions between 5 and 10 minutes post-injection in order to shorten the time of this early acquisition.Materials and methodsPatients with proven prostate cancer referred for initial staging or recurrence were prospectively included. Patients underwent 10 minutes of pelvic dynamic acquisition for the early phase and late phase was performed at 60 minutes post-injection. Contrast-to-noise of lesions at 5 and 10 min post-injection were compared.ResultsForty-nine patients with 77 lesions were analyzed. No significant difference of prostatic lesions contrast-to-noise ratio was found between 5 min and 10 min post-injection (median contrast-to-noise ratio was respectively 38 and 42, P = 0.128).ConclusionThese results could have an impact on clinical practice with FCH-PET/CT early acquisition shortened to 5 min post-injection for patients with prostate cancer.     

Clinical authorization of amyloid PET in France: Towards a more precise diagnosis of Alzheimer's disease

The recent clinical authorization of amyloid PET in France represents a crucial step for the nuclear medicine community involved in the diagnosis of Alzheimer's disease (AD). At the era of ATN (Amyloid, Tau, Neurodegeneration) biomarkers, amyloid PET fills a need in patients with an atypical or mixed clinical presentation, in particular young patients (<65 years old), when the lumbar puncture is contraindicated or not feasible for technical reasons. Importantly, a negative amyloid PET scan discards the diagnosis of AD. Furthermore, early phase imaging of amyloid PET allows to estimate the perfusion neuronal state, increasing the diagnostic value of such PET radiotracer. Its role could be further developed in routine care for the selection and monitoring of promising disease modifiers therapies.     

Differential diagnosis between progression and radionecrosis in brain metastases after stereotactic radiosurgery using hybrid FDG-PET and MRI coregistered images

IntroductionDual phase 18 FDG brain PET is helpful to assess brain metastases (BM) as tracer will build up in metastases or tumor recurrences while its retention remains stable within normal tissue or inflammatory processes. This is useful when MRI can’t discriminate brain tumor recurrence (TR) rom radionecrosis (RN) after stereotaxic radiosurgery (SRS) for BM. Many studies have sought to improve diagnostic performance by associating FDG-PET and MRI with interesting results but many biases, mostly within image post-processing. Coregistered MRI and dual phase FDG-PET images could alleviate these biases and be used to extract prognostic biomarkers.Materials and methodsWe retrospectively evaluated patients treated with SRS for BM which developed a contrast-enhanced MRI lesion with non-conclusive diagnosis for TR or RN. All patients underwent MRI and FDG-PET at least 3 months after their last SRS session. Dual FDG-PET consisted in an “early” and “delayed” acquisition, respectively 30 minutes and 4 h after injection. MRI included permeability and perfusion sequences. PET and MRI data were all coregistered on the contrast enhanced T1 MRI images. Semi-automated Volumes of Interest (VOI) of the tumor were drawn on the BM and a reference contralateral white-matter ROI (WM) was drawn for standardization; every metric was calculated inside these ROIs, in particular the tumor SUVmax and its variation in time. A 20% increase in the tumor SUVmax was in favor of TR while a modification of less than 100% was in favor of RN. Imaging metrics were then evaluated for their association with TR or RN based on histological, radiological and clinical criteria after at least 6 months follow-up.ResultsNine patients were ruled out as TR and 6 as RN. After standardization, there was a significant difference between groups for VP (P = 0.042), Washin (P = 0.035), Peak Enhancement (P = 0.037), standardized delayed SUVmax (P = 0.008) and RI (P = 0.016). Semi-quantitative analysis found respectively for PET and MRI a Sensitivity of 100% and 87.5% and a Specificity of 100% and 85.71%.ConclusionCoregistered PET-MRI images accurately discriminate between TR and RN. With FDG being the most commonly used PET radiotracer, this protocol remains easily transposable and should be encouraged to obtain non-invasive prognostic and clinically relevant biomarkers.