90Y microsphere treatment of unresectable liver metastases: changes in 18F-FDG uptake and tumour size on PET/CT

Purpose The intra-arterial administration of ⁹⁰Y microspheres is a new palliative treatment option for unresectable liver metastases. The aim of this study was to quantitatively assess changes in FDG uptake and tumour size following ⁹⁰Y microsphere treatment (SIR-Spheres) using ¹⁸F-fluorodeoxyglucose (FDG) PET/CT imaging.Methods Five patients with unresectable liver metastases who had failed multiple prior chemotherapy regimens received seven ⁹⁰Y microsphere treatments to a single liver lobe. All patients underwent a baseline PET/CT scan prior to treatment, as well as up to four follow-up PET/CT scans. The tumour area of 30 liver metastases was measured on CT and the FDG uptake was semiquantitatively assessed by calculation of standardised uptake values (SUVs). A total of 18 FDG-PET/CT scans were performed.Results The SUVs in the 30 treated liver metastases decreased from 6.5±2.3 at baseline to 4.2±1.8 after the first follow-up PET/CT scan (p=0.001). In contrast, the SUVs of untreated metastases increased slightly from 7.2±2.3 to 8.0±0.8. There was no difference in FDG uptake in treated versus untreated normal liver tissue. Using a previously defined threshold of 20% decrease in SUV from baseline to determine response, 20 out of 30 liver metastases were considered to have responded at the first follow-up PET/CT scan approximately 1 month after treatment. In these metastases, the SUV decreased by 47±12%, compared with a slight increase by 5.9±19% in ten non-responding metastases (p=0.0001). The changes in tumour size did not correlate with changes in FDG uptake. On the first follow-up PET/CT scan, the tumour area on CT increased by 3.1±57% in treated metastases compared with 23.3±32% in untreated metastases. A wide range of post-treatment changes of target lesions was observed on CT, including an increase in the size of hypodense lesions, necrotic features and complete resolution of CT abnormalities.Conclusion The metabolic information obtained from FDG-PET/CT seems to provide a more accurate and earlier assessment of therapy response following ⁹⁰Y microsphere treatment than does the anatomical CT information.     

Comparison of different SUV-based methods for monitoring cytotoxic therapy with FDG PET

Purpose Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) is a promising tool for monitoring cytotoxic therapy in tumours. Due to the limited data available, a standard imaging protocol for the prediction of tumour response has not yet been approved. The aim of this study was to compare commonly applied imaging protocols and calculations of the standardised uptake value (SUV) for the early prediction of histopathological response to chemotherapy.Methods Serial FDG PET scans of 43 patients with gastric carcinomas were retrospectively analysed. All patients received two consecutive scans (one bed position at 40 min p.i. and four bed positions at 90 min p.i.) at baseline and during the first cycle of cisplatinum-based chemotherapy. Reconstruction of the images was performed by filtered back-projection (FBP) and using an iterative algorithm (OSEM). SUVs were calculated with and without correction for the blood glucose level using normalisation by body weight, body surface area and lean body mass. Relative percentage changes between SUVs at baseline and follow-up were calculated and analysed for their potential to predict histopathological response to chemotherapy (ROC analysis). Response was defined as less than 10% viable tumour cells in the tumour specimen obtained by surgery 3–4 weeks after the completion of chemotherapy.Results Eight of 43 patients were histopathological responders to chemotherapy. The percentage changes in SUV_{body weight} for responders and non-responders were –52.2 (±13.2) and –25.2 (±15.2), –54.7 (±18.2) and –24.5 (±16.1), –53.9 (±24.2) and –22.7 (±21.3), and –56.7 (±21.6) and –26.1 (±18.9) for serial scans at 40-min FBP, 40-min OSEM, 90-min FBP and 90-min OSEM, respectively (responders versus non-responders: p<0.01 in each case). According to ROC analysis, neither the scan protocol nor correction for blood glucose significantly influenced the accuracy (approx. 80%) or the cut-off value (approx. –40% change in tumour SUV) for the prediction of response. Normalisation of SUVs by body surface area or lean body mass instead of body weight yielded essentially identical results.Conclusion In gastric carcinomas the prediction of response to chemotherapy on the basis of relative tumour SUV changes is not essentially influenced by any of the methodological variations investigated (time delay after FDG administration, acquisition protocol, reconstruction algorithm, normalisation of SUV). This demonstrates the robustness of FDG PET for therapeutic monitoring and facilitates the comparability of studies obtained at different institutions and with different protocols. However, whichever method is used for therapy monitoring with FDG PET, a highly standardised protocol must be observed to take the dynamics of tumour FDG uptake into account.     

Correlation of PET/CT Standardized Uptake Value Measurements Between Dedicated Workstations and a PACS-Integrated Workstation System

Purpose This study was conducted to evaluate the clinical utility of a Positron Emission Tomography/Computed Tomography (PET/CT) analysis module of a picture archiving communication system (PACS) workstation in comparison to a dedicated PET/CT interpretation workstation. Materials and Methods The study included 32 consecutive patients referred for an [¹⁸F] Fluro-2-Deoxy-D-Glucose (¹⁸F-FDG) PET/CT at our institution. Images were reviewed at dedicated PET/CT and at PACS-integrated workstations. Mean standardized uptake values (SUVs) were calculated for the liver and the lung. Maximum SUVs were recorded for the bladder and an index lesion with the highest FDG uptake. The time spent for SUV measurements was recorded. Correlation of the SUV measurements was calculated with the Pearson coefficient. Results Pearson coefficients between the workstations ranged from 0.96 to 0.99 for bladder and lesion maximum SUVs. For liver and lung average SUVs, the coefficients varied from 0.53 to 0.98. The mean time spent to perform the four SUV measurements was 122.6 s for the dedicated workstations and 134.6 s for the PACS-integrated system. Conclusion The correlation of SUV measurements between dedicated PET/CT and PACS-integrated workstations is very good, especially for maximum SUVs. For routine reading of PET/CT scans, a PACS workstation with a PET/CT analysis module offers an excellent alternative to the use of a dedicated PET/CT workstation.     

^18FDG-PET诊断胃癌及影响因素

目的 :评价18FDG PET对胃癌的诊断价值和胃肠生理性摄取等因素对诊断的影响。材料和方法 :无消化道疾病史的FDG PET查体者 3 0 3例为组 1;PET发现胃部最大SUV值≥ 3 .5 ,并在 1～ 2周内接受胃镜检查者 2 7例为组 2 ;胃镜初步诊断为胃癌且经PET检查、手术和病理检查 3 3例为组 3。用ROI方法测定胃等病灶SUV最大值 (SUVmax)和平均值(SUVave)。结果 :组 1胃部FDG摄取SUVmax为 0 .71～ 5 .7,SUVave为 0 .61～ 4.6。 16%胃SUVmax<1.5 ;5 5 %SUVmax>2 .0 ;17%SUVmax>3 .0 ;6%SUVmax>3 .5。组 2胃部SUVmax3 .5～ 5 .7,胃镜证实 19例正常 ,5例胃炎 ,3例溃疡 ;炎性及溃疡病变FDG摄取高于正常胃 (p <0 .0 5 )。PET检出组 3原发病灶 97% ( 3 1/ 3 2 ) ;远处转移 6/ 6;胃局部淋巴结转移 6/ 11。假阴性 1例 ,纠正胃镜误诊 1例 ,上调UVmax从≥ 3 .0至≥ 3 .5 ,则组 1中假阳性从 17%降至 6% ,组 3假阴性仍保持不变。结论 :提高SUV阈值可减少胃肠道生理或 /和炎性摄取对结果的影响。     

Liposome encapsulation enhancement of methotrexate sensitivity in a transport resistant human leukemic cell line

A stable mutant of human leukemia CCRF/CEM cells has recently been isolated which is transport resistant for methotrexate (MTX). Encapsulation of MTX in cationic unilamellar liposomes increased the association of the drug 5-fold with the sensitive, and 50-fold with the resistant, cells as compared to the uptake of free drug. The liposome-mediated associations of MTX with sensitive and transport deficient cell lines were similar. Cytostatic studies demonstrated that liposome encapsulation increased MTX activity 4-fold towards the transport resistant cell line. The addition of cholesterol to the vesicles decreased their effectiveness. A 4-fold increase in drug sensitivity due to encapsulation may allow such transport resistant tumor cells to become responsive to chemotherapeutic doses of MTX which are currently feasible in human clinical protocols.     

Preliminary retrospective investigation of FDG-PET/CT timing in follow-up of ablated lung tumor

OBJECTIVE: The aim of this study was to clarify the most appropriate follow-up initiation time point for positron emission tomography (PET)/computed tomography (CT) following radio frequency ablation (RFA) of lung tumors, and the cutoff values of maximum standard uptake value (SUV(max)) to evaluate local tumor progression. METHODS: We enrolled 15 patients (8 men, median age 62 years) with 60 tumors, who were treated with RFA of lung tumors and underwent fluorodeoxyglucose (FDG)-PET/CT following RFA. Local tumor progression was assessed by periodic chest CT images prior to and following intravenous administration of a contrast medium. The SUV(max) of three periods, namely, 0-3 months, 3-6 months, and 6-9 months after RFA, was evaluated. The appropriate time point for follow-up initiation and the cutoff value of SUV(max) were determined using receiver-operating characteristic (ROC) analysis. RESULTS: The median follow-up period was 357 days. Of 60 tumors, 10 showed local progression. The area under the ROC curve (Az) for the 6-9 months (P = 0.044) was the largest and almost equal to that of the 3-6 months (P = 0.024). Az for the 0-3 months was the smallest and statistically insignificant (P = 0.705). The cutoff value of 1.5 of SUV(max) at 3-9 months after RFA showed 77.8% sensitivity and 85.7-90.5% specificity. CONCLUSIONS: The appropriate follow-up initiation time point is at least 3 months following RFA. Thus, SUV(max) is a useful and reliable predictive indicator.     

屏气采集配合ultraHD重建技术改善PET/CT检查肺部代谢灶融合不良

目的比较吸气后屏气采集配合ultra HD重建法较传统自由呼吸法在改善肺部病灶PET/CT检查受呼吸运动而导致融合不良的作用大小。方法制定入组条件:患者常规PET/CT检查CT图像可见明确占位性病灶，PET有明确与之对应的高代谢灶，患者有相应的CT需屏气采集检查史且屏气效果良好，可以对技师的屏气指令做出良好配合。按上述入组条件依次抽取2019年1~6月在某三甲医院PET/CT中心检查的患者60例，将患者常规采集所得图像作为对照组；常规检查结束后立即行肺部高代谢灶单床位吸气后屏气采集配合ultra HD重建，将所得图像作为观察组。比较对照组与观察组图像的融合质量、平均标准率摄取值（SUV_avg）、40%的肿瘤代谢体积（MTV_40%），病灶与肝血池SUV_max的靶本比（T/B_max），并从成像原理的基础上加以解释分析。结果对照组融合良好17例占28.33%，观察组融合良好58例占96.67%；SUV_avg观察组为8.28±2.45、对照组为6.84±2.58，观察组明显高于对照组（χ2=10.50，P<0.05）；MTV_40%观察组为5.61±4.40、对照组为7.70±5.39，观察组明显低于对照组（χ2=5.37，P<0.05），T/B_max观察组为6.29±2.39、对照组为4.87±1.78，观察组明显高于对照组（χ2=13.71，P<0.05）。结论屏气采集配合ultra HD重建法得到的图像较传统法所得图像，融合良好占比更高；SUV_avg、MTV_40%，T/B_max测量值受部分容积效应和移动边界扩大效应的影响更小；加之更加精确的PSF在重建过程中的运用，使上述定量指标更加精确，值得肺部疾病患者临床PET/CT采集中借鉴并有针对性的酌情使用。      

Cyclization enhances function of linear anti-arthritic peptides

This study describes the biophysical and immunomodulatory features of a cyclic peptide termed C1 which consists of alternating d-, l-amino acids and is capable of inhibiting IL-2 production in vitro and reducing the induction and extent of T-cell mediated inflammation in animal models. Solid-state nuclear magnetic resonance demonstrates that the peptide orders the lipid bilayer, suggesting a transmembrane orientation, and this is supported by surface plasmon resonance indicating strong binding affinity of C1 to model membranes. In vitro cell viability and proliferation assays show that C1 does not disrupt the integrity of cell surface membranes. Permeation studies of C1 and analogs across human epidermis cells show that the stability and skin permeability are enhanced by cyclization. Treatment with C1 in an asthma and in an arthritis animal model resulted in a suppressed immune response. Cyclization may be a useful means of enhancing biological linear peptide activity and improving delivery.