Alpha-fetoprotein and 18F-FDG standard uptake value predict tumor recurrence after liver transplantation for hepatocellular carcinoma with portal vein tumor thrombosis:Preliminary experience

Background:Portal vein tumor thrombosis(PVTT)is regarded as a contraindication for liver transplantation(LT)in hepatocellular carcinoma(HCC).However,some of these patients may have a favorable prognosis after LT.In this study,we evaluated the biological behavior of HCC with PVTT using tumor biomarker(alpha-fetoprotein,AFP)and 18 F-FDG positron emission tomography(tumor standard uptake value)to identify a subset of patients who may be suitable for LT.Methods:Seventy-five HCC-PVTT liver recipients transplanted during February 2016 and June 2018 were analyzed.Different pre-transplant prognostic factors were identified by univariate and multivariate analyses.PVTT status was identified following Vp classification(Vp1-Vp4).Results:Three-year recurrence-free survival and overall survival rates were 40%and 65.4%in Vp2-Vp3 PVTT patients,21.4%and 30.6%in Vp4 PVTT patients(P<0.05).Total tumor diameter>8 cm,pretransplant AFP level>1000 ng/m L and intrahepatic tumor maximal standard uptake value(SUVmaxtumor>5)were independent risk factors for HCC recurrence and overall survival after LT in Vp2-3 PVTT patients.Low risk patients were defined as total tumor diameter≤8 cm;or if total tumor diameter more than 8 cm,with both pre-transplant AFP level less than 1000 ng/m L and intrahepatic tumor SUVmax less than 5,simultaneously.Twenty-two Vp2-3 PVTT HCC patients(46.8%)were identified as low risk patients,and their 3-year recurrence-free and overall survival rates were 67.6%and 95.2%,respectively.Conclusions:Patients with segmental or lobar PVTT and biologically favorable tumors defined by AFP and 18 F-FDG SUVmax might be suitable for LT.

Prognostic Value of Semi-Quantitative 18F-FDG PET/CT Parameters in Hodgkin’s Lymphoma

Objective:To assess the prognostic value of maximum standardized uptake value(SUVmax),metabolic tumor volume(MTV),and total lesion glycolysis(TLG)determined by 18F-fluorodeoxyglucose positron emission tomography-computed tomography(18F-FDG PET/CT)imaging in Hodgkin’s lymphoma patients.Methods:A total of 148 Hodgkin’s lymphoma patients diagnosed with lymph node biopsy from October 2014 to October 2015 were retrospectively analyzed followed by categorizing into good(125 cases)and poor(23 cases)prognosis groups.The chi-squared test was used to analyze the clinicopathological characteristics of Hodgkin’s lymphoma patients with the semi-quantitative 18F-FDG PET/CT parameters;the Spearman method was used to analyze the correlation between the semi-quantitative parameters and clinicopathological features of Hodgkin’s lymphoma;receiver operating characteristic curve was used to analyze the predictive value of the semi-quantitative parameters for poor prognosis of Hodgkin’s lymphoma patients.Results:Mean SUVmax,MTV,and TLG of the 148 cases of Hodgkin’s lymphoma were 7.26±2.38,12.46±3.14 cm3,and 76.83±18.56 g,respectively.Significant variations in the Ann Arbor stage and clinical classification were observed with different levels of semi-quantitative parameters(P<0.05).The semi-quantitative parameters were not correlated with age and gender(P>0.05)but positively correlated with Ann Arbor stage and clinical classification(P<0.05).These parameters in the poor prognosis group were higher than those in the good prognosis group(P<0.05).The area under the curve(AUC)of SUVmax,MTV,and TLG in predicting the poor prognosis group was 0.881,0.875,and 0.838,with cut-off values of 7.264,12.898 cm3,and 74.580g,as well as specificity of 88.8%,84.0%,and 78.4%,and sensitivity of 87.0%,87.0%,and 78.3%,respectively;the AUC of the combined prediction was 0.986,with a specificity of 97.6%and sensitivity of 86.3%.Conclusion:The semi-quantitative 18F-FDG PET/CT parameters provide valuable insights for Hodgkin’s lymphoma prognosis assessment.

Prognostic value of interim ^(18)F-FDG PET/CT in diffuse large B-cell lymphoma

Objective： Diffuse large B-cell lymphoma （DLBCL） is a heterogeneous disease. The prognostic factor currently used is not accurate enough to predict the outcomes of patients with DLBCL. The prognostic significance of interim PET/CT in DLBCL remains controversial. The aim of this study is to determine the predictive value of interim 18F-FDG PET/CT after first-line treatment in patients with DLBCL. Methods： Thirty-two patients with DLBCL underwent baseline, interim and post-treatment lSF-FDG PET/CT scans. Imaging results were analyzed for the survival of patients via software SPSS 13.0, retrospectively. Results： Thirty-one of the 32 patients were treated with R-CHOP regimen, and interim 18F-FDG PET/CT of 24 patients was performed after 2 cycles of treatment. After a median follow-up period of 16.7 months, the 2-year progression-free survival （PFS） rates were significantly different between the groups above and below SUVmax CUt-Off value of 2.5 （P=0.039）. No significant differences were found in the 2-year PFS rates if SUVm, cut-offvalues were set as 2.0 and 3.0, respectively （P=0.360; P=0.113）. Conclusions： Interim PET/CT could predict the prognosis of DLBCL patients with the SUVmax cut-off value of 2.5, but more clinical data should be concluded to confirm this conclusion.

Calculation of b value and its application in earthquake prediction

The improved calculation method of b value is presented in tills paper. The method can enlarge the role of earthquake occurrence frequency in b value calculation and thus increase the b value variation amplitude. In this case,the combination structure variation between earthquake magnitudes and corresponding frequencies could be shown clearly. According to the calculation and analysis for limited mainshocks in the complete seismicity data of selected monitored area with assigned consistent lowest magnitude, the precursor anomaly features, quantitative indexes and the calculation formula of relative subject function of b value variation have been preliminarily worked out. The prediction in short period (from 1 to 3 months) for damage earthquakes in the monitored area mentioned above can be put forward on the basis of the results of quantitative calculation and analysis.

Mathematical Proof of the Synthetic Running Correlation Coefficient and Its Ability to Reflect Temporal Variations in Correlation

The running correlation coefficient(RCC)is useful for capturing temporal variations in correlations between two time series.The local running correlation coefficient(LRCC)is a widely used algorithm that directly applies the Pearson correlation to a time window.A new algorithm called synthetic running correlation coefficient(SRCC)was proposed in 2018 and proven to be rea-sonable and usable;however,this algorithm lacks a theoretical demonstration.In this paper,SRCC is proven theoretically.RCC is only meaningful when its values at different times can be compared.First,the global means are proven to be the unique standard quantities for comparison.SRCC is the only RCC that satisfies the comparability criterion.The relationship between LRCC and SRCC is derived using statistical methods,and SRCC is obtained by adding a constraint condition to the LRCC algorithm.Dividing the temporal fluctuations into high-and low-frequency signals reveals that LRCC only reflects the correlation of high-frequency signals;by contrast,SRCC reflects the correlations of high-and low-frequency signals simultaneously.Therefore,SRCC is the ap-propriate method for calculating RCCs.

Application of Positron Emission Tomography in the Detection of Myocardial Metabolism in Pig Ventricular Fibrillation and Asphyxiation Cardiac Arrest Models after Resuscitation

Objective To study the application of positron emission tomography （PET） in detection of myocardia metabolism in pig ventricular fibrillation and asphyxiation cardiac arrest models after resuscitation. Methods Thirty-two healthy miniature pigs were randomized into a ventricular fibrillation cardiac arrest （VFCA） group （n=16） and an asphyxiation cardiac arrest （ACA） group （n=16）. Cardiac arrest （CA） was induced by programmed electric stimulation or endotracheal tube clamping followed by cardiopulmonary resuscitation （CPR） and defibrillation. At four hours and 24 h after spontaneous circulation was achieved, myocardial metabolism was assessed by PET. 18F-FDG myocardial uptake in PET was analyzed and the maximum standardized uptake value （SUVmax） was measured. Results Spontaneous circulation was 200% and 62.5% in VFCA group and ACA group, respectively. PET demonstrated that the myocardial metabolism injuries was more severe and widespread after ACA than after VFCA. The SUVrnax was higher in VFCA group than in ACA group （P〈0.01）. In VFCA group, SUVmax at 24 h after spontaneous circulation increased to the level of baseline. Conclusion ACA causes more severe cardiac metabol associated with less successful resuscitation. Myocardial sm injuries than VFCA. Myocardial dysfunction is stunning does occur with VFCA but not with ACA.

Factors predicting upstaging from clinical N0 to pN2a/N3a in breast cancer patients

BACKGROUND With sentinel node metastasis in breast cancer(BC)patients,axillary lymph node(ALN)dissection is often omitted from cases with breast-conserving surgery.Omission of lymph node dissection reduces the invasiveness of surgery to the patient,but it also obscures the number of metastases to non-sentinel nodes.The possibility of finding≥4 lymph nodes(pN2a/pN3a)preoperatively is important given the ramifications for postoperative treatment.AIM To search for clinicopathological factors that predicts upstaging from N0 to pN2a/pN3a.METHODS Patients who were sentinel lymph node(SLN)-positive and underwent ALN dissection between September 2007 and August 2018 were selected by retrospective chart review.All patients had BC diagnosed preoperatively as N0 with axillary evaluation by fluorodeoxyglucose(FDG) positron emission tomography/computed tomography and ultrasound (US)examination. When suspicious FDG accumulation was found in ALN, the presence of metastasiswas reevaluated by second US. We examined predictors of upstaging from N0 to pN2a/pN3a.RESULTSAmong 135 patients, we identified 1-3 ALNs (pN1) in 113 patients and ³4 ALNs (pN2a/pN3a) in22 patients. Multivariate analysis identified the total number of SLN metastasis, the maximaldiameter of metastasis in the SLN (SLNDmax), and FDG accumulation of ALN as predictors ofupstaging to pN2a/pN3a.CONCLUSIONWe identified factors involved in upstaging from N0 to pN2a/pN3a. The SLNDmax and numberof SLN metastasis are predictors of ≥ 4 ALNs (pN2a/pN3a) and predictors of metastasis to nonsentinelnodes, which have been reported in the past. Attention should be given to axillaryaccumulations of FDG, even when faint.

Preoperative risk factors for early recurrence in patients with resectable pancreatic ductal adenocarcinoma after curative intent surgical resection

Background: Postoperative early recurrence(ER) in patients with pancreatic ductal adenocarcinoma(PDAC) is frequently encountered after curative intent surgery. Nonetheless, clinical significance and risk factors of ER after surgery for PDAC have not been extensively investigated. The aim of this study was to determine preoperative risk predictors for ER in patients with PDAC after upfront surgery. Methods: Eighty-one consecutive patients with PDAC who underwent curative intent surgical resection at Kangbuk Samsung Hospital between January 2004 and May 2015 were enrolled. ER was defined as tumor relapse within 6 months after surgery. Results: ER occurred in 26 patients(32.1%), whereas 49 patients(60.5%) had late recurrence( ≥ 6 months after surgery), and 6 patients had no recurrence(7.4%). Univariate analysis showed that C-reactive protein(CRP) > 3.0 mg/dL, modified Glasgow prognostic score(mGPS) = 2, decrease of total lymphocyte count by > 50% of baseline value in the preoperative period, prognostic nutritional index(PNI) < 45, neutrophilto-lymphocyte ratio(NLR) ≥ 3, and preoperative maximum standardized uptake value(SUVmax) were significantly associated with ER. Multivariate logistic regression analysis revealed that CRP > 3.0 mg/dL, decrease of total lymphocyte count by > 50% of baseline value, and preoperative SUVmax were significant and independent contributors of ER in patients with resectable PDAC who underwent curative intent surgery. Conclusions: Postoperative ER for resectable PDAC was frequent with poor prognosis after curative intent upfront surgery. It is reasonable to suggest that there is a subgroup of resectable PDAC patients at highrisk of ER and neoadjuvant therapy should be considered in these patients in a clinical trial setting.

Significance of incidental focal fluorine-18 fluorodeoxyglucose uptake in colon/rectum,thyroid,and prostate:With a brief literature review

BACKGROUND Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography(F-18 FDG PET/CT),a functional imaging method,is usually performed on the entire torso,and regions of unexpected suspicious focal hypermetabolism are not infrequently observed.Among the regions,colon,thyroid,and prostate were found to be the common organs in a recent umbrella review.Some studies reported that a high rate of malignancy was shown in incidentally identified focal hypermetabolic regions and suggested that further examinations should not be ignored.AIM To investigate the malignancy rate of incidental focal FDG uptake,useful PET parameters and their cutoffs in discrimination between malignant and benign lesions.METHODS Retrospectively,the final reports of 16510 F-18 FDG PET/CT scans performed at our hospital between January 2016 and March 2022 were reviewed to identify incidentally observed FDG uptake in the colon/rectum,thyroid,and prostate.The scans of patients with current or prior malignancies at each corresponding location,without the final reports of histopathology or colonoscopy(for colon and rectum)for the corresponding hypermetabolic regions,or with diffuse(not focal)hypermetabolism were excluded.Finally,88 regions of focal colorectal hypermetabolism in 85 patients(48 men and 37 women with mean age 67.0±13.4 years and 63.4±15.8 years,respectively),48 focal thyroid uptakes in 48 patients(12 men and 36 women with mean age 62.2±13.1 years and 60.8±12.4 years,respectively),and 39 focal prostate uptakes in 39 patients(mean age 71.8±7.5 years)were eligible for this study.For those unexpected focal hypermetabolic regions,rates of malignancy were calculated,PET parameters,such as standardized uptake value(SUV),capable of distinguishing between malignant and benign lesions were investigated,and the cutoffs of those PET parameters were determined by plotting receiver operating characteristic curves.RESULTS In the colon and rectum,29.5%(26/88)were malignant and 33.0%(29/88)were premalignant lesions.Both SUVmax and SUVpeak differentiated malignant/premalignant from benign lesions,however,no parameters could distinguish malignant from premalignant lesions.Higher area under the curve was shown with SUVmax(0.752,95%CI:0.649-0.856,P<0.001)and the cutoff was 7.6.In the thyroid,60.4%(29/48)were malignant.The majority were well-differentiated thyroid cancers(89.7%,26/29).The results of BRAF mutation tests were available for 20 of the 26 welldifferentiated thyroid cancers and all 20 had the mutation.Solely SUVmax differentiated malignant from benign lesions and the cutoff was 6.9.In the prostate,56.4%(22/39)were malignant.Only SUVmax differentiated malignant from benign lesions and the cutoff was 3.8.Overall,among the 175 focal hypermetabolic regions,60.6%(106/175)were proven to be malignant and premalignant(in colon and rectum)lesions.CONCLUSION Approximately 60%of the incidentally observed focal F-18 FDG uptake in the colon/rectum,thyroid,and prostate were found to be malignant.Of the several PET parameters,SUVmax was superior to others in distinguishing between malignant/premalignant and benign lesions.Based on these findings,incidental focal hypermetabolism should not be ignored and lead physicians to conduct further investigations with greater confidence.

Assessment of incidental focal colorectal uptake by analysis of fluorine-18 fluorodeoxyglucose positron emission tomography parameters

BACKGROUND Colon and rectal cancers are among the top five cancers worldwide in terms of their incidence and mortality rates.As the treatment options for cure include surgery even in specific advanced-stage cases,the early detection of lesions is important for applying active treatment methods.Fluorine-18 fluorodeoxyglucose(F-18 FDG)positron emission tomography/computed tomography(PET/CT)is an established imaging study for many types of cancers;however,physiologic uptake in the gastrointestinal tract is a frequent finding and may interfere with lesion identification.Nevertheless,as unexpectedly observed focal colorectal F-18 FDG uptake may harbor malignant lesions,further examination must not be avoided.AIM To assess the clinical implications of unexpected focal colorectal F-18 FDG uptake by analyzing FDG PET parameters.METHODS A total of 15143 F-18 FDG PET/CT scans performed at our hospital between January 2016 and September 2021 were retrospectively reviewed to identify incidentally observed focal colorectal FDG uptake.Finally,83 regions showing focal colorectal FDG uptake with final histopathological reports from 80 patients(45 men and 35 women with mean ages of 66.9±10.7 years and 63.7±15.3 years,respectively)were eligible for inclusion in the present study.Each focal hypermetabolic colorectal region was classified as malignant,premalignant,or benign according to the histopathological report.PET parameters such as maximum and peak standardized uptake value(SUVmax and SUVpeak),metabolic tumor volume(MTV),mean SUV of the metabolic tumor volume(mSUVmtv),and total lesion glycolysis(TLG)were measured or calculated for the corresponding hypermetabolic regions.Parametric and nonparametric statistical comparisons of these parameters were performed among the three groups.Receiver operating characteristic curves were plotted to identify cut-off values.RESULTS The detection rate of incidental focal colorectal uptake was 0.53%(80/15,143).Of the 83 regions with unexpected focal colorectal hypermetabolism,28.9%(24/83)were malignant,32.5%(27/83)were premalignant,and 38.6%(32/83)were benign.Overall,61.4% of the regions had malignant or premalignant lesions.SUVmax,SUVpeak,and mSUVmtv differentiated malignant and/or premalignant lesions from benign lesions with statistical significance(P<0.05).mSUVmtv3.5 differentiated malignant from benign lesions,with the largest area under the curve(AUC)of 0.792 and a cut-off of 4.9.SUVmax showed the largest AUC of 0.758 with a cut-off value of 7.5 for distinguishing between premalignant and benign lesions.Overall,SUVmax with a cut-off value of 7.6(AUC:0.770,95% confidence interval(CI):0.668-0.872;sensitivity,0.686;specificity,0.688)was a superior parameter for distinguishing between malignant/premalignant and benign lesions or physiologic uptake.No parameters differentiated malignant from premalignant lesions.Moderate or weak positive correlations were observed between the long diameter of the malignant lesions and PET parameters such as SUVpeak and some mSUVmtv.CONCLUSION Approximately two-thirds(61.4%)of incidental focal hypermetabolic colorectal regions were malignant/premalignant lesions,for which SUVmax was an independent diagnostic parameter.Unexpected suspicious focal colorectal FDG uptake should not be avoided and consideration for further evaluation is strongly recommended not to miss the two-thirds.

Characterization of focal hypermetabolic thyroid incidentaloma: An analysis with F-18 fluorodeoxyglucose positron emission tomography/computed tomography parameters

BACKGROUND Incidentally found thyroid tumor(thyroid incidentaloma,TI)on F-18 fluorodeoxyglucose(FDG)positron emission tomography-computed tomography(PETCT)is reported in 2.5%-5%of patients being investigated for non-thyroid purposes.Up to 50%of these cases have been diagnosed to be malignant by cytological/histological results.Ultrasonography(US)and fine-needle aspiration cytology are recommended for thyroid nodules with high FDG uptake(hypermetabolism)that are 1 cm or greater in size.It is important to accurately determine whether a suspicious hypermetabolic TI is malignant or benign.AIM To distinguish malignant hypermetabolic TIs from benign disease by analyzing F-18 FDG PET-CT parameters and to identify a cut-off value.METHODS Totally,12761 images of patients who underwent F-18 FDG PET-CT for nonthyroid purposes at our hospital between January 2016 and December 2020 were retrospectively reviewed,and 339 patients[185 men(mean age:68±11.2)and 154 women(mean age:63±15.0)]were found to have abnormal,either focal or diffuse,thyroid FDG uptake.After a thorough review of their medical records,US,and cytological/histological reports,46 eligible patients with focal hypermetabolic TI were included in this study.The TIs were categorized as malignant and benign according to the cytological/histological reports,and four PET parameters[standardized uptake value(SUV)max,SUV_(peak),SUV_(mean),and metabolic tumor volume(MTV)]were measured on FDG PET-CT.Total lesion glycolysis(TLG)was calculated by multiplying the SUV_(mean) by MTV.Both parametric and non-parametric methods were used to compare the five parameters between malignant and benign lesions.Receiver operating characteristic(ROC)curve analysis was performed to identify a cut-off value.RESULTS Each of the 46 patients[12 men(26.1%;mean age:62±13.1 years)and 34 women(73.9%;mean age:60±12.0 years)]with focal hypermetabolic TIs had one focal hypermetabolic TI.Among them,26(56.5%)were malignant and 20(43.5%)were benign.SUV_(max),SUV_(peak),SUV_(mean),and TLG were all higher in malignant lesions than benign ones,but the difference was statistically significant(P=0.012)only for SUV_(max).There was a positive linear correlation(r=0.339)between SUV_(max) and the diagnosis of malignancy.ROC curve analysis for SUV_(max) revealed an area under the curve of 0.702(P<0.05,95%confidence interval:0.550-0.855)and SUV_(max) cut-off of 8.5 with a sensitivity of 0.615 and a specificity of 0.789.CONCLUSION More than half of focal hypermetabolic TIs on F-18 FDG PET-CT were revealed as malignant lesions,and SUV_(max) was the best parameter for discriminating between malignant and benign disease.Unexpected focal hypermetabolic TIs with the SUV_(max) above the cut-off value of 8.5 may have a greater than 70%chance of malignancy;therefore,further active assessment is required.

The Role of ¹⁸F-FDG PET/CT in Staging Breast Carcinoma in Hanoi Oncology Hospital, Vietnam

Purpose: This study aimed to evaluate the role of 18F-FDG PET/CT scans in staging breast carcinoma. Materials and Methods: A descriptive study on 46 patients who were diagnosed with breast carcinoma in Hanoi Oncology Hospital, Vietnam from June 2019 to June 2021. Those patients underwent 18F-FDG PET/CT scans for pre-treatment staging. Results: There was a positive correlation between the size of primary tumors and their SUV (p < 0.0001, r = 0.759). The mean SUV was reported to be 2.5 for tumors under 2 cm, 5.89 for tumors from 2 - 5 cm, 13.6 for tumors above 5 cm, and 8.23 for skin invasive lesions. In terms of regional lymph node metastasis detection, the sensitivity and specificity of 18F-FDG PET/CT were 75% and 100%, respectively. The rate of distant metastasis detection was 15.2% (7/46 patients). Metastatic lesions were found in bone, lungs, liver, and lymph nodes. There was a significant difference in SUV among organs (p < 0.001), with the highest SUV found in bone metastasis. The rates of stage I, II, III and IV diagnosed after PET/CT are 8.7%;45.7%;30.4% and 15.2% respectively, compared to 10.9%;54.3%;32.6%;2.2% before taking 18F-FDG PET/CT. After PET/CT, 17.4% patients (8/46) had their treatment plan changed. Conclusions: 18F-FDG PET/CT plays an important role in staging breast carcinoma. Determining accurately the breast carcinoma stage by 18F-FDG PET/CT could help alter treatment strategy to best suit with patients, and avoid unnecessary surgery.

Temperature variation and abrupt change analysis in the Three-River Headwaters Region during 1961-2010

In this study, a monthly dataset of temperature time series （1961-2010） from 12 meteorological stations across the Three-River Headwater Region of Qinghai Province （THRHR） was used to analyze the climate change. The temperature variation and abrupt change analysis were examined by using moving average, linear regression, Spline interpolation, Mann-Kendall test and so on. Some important conclusions were obtained from this research, which mainly contained four aspects as follows. （1） There were several cold and warm fluctuations for the annual and seasonal average temperature in the THRHR and its three sub-headwater regions, but the temperature in these regions all had an obviously rising trend at the statistical significance level, especially after 2001. The spring, summer, autumn and annual average temperature increased evidently after the 1990s, and the winter average temperature exhibited an obvious upward trend after entering the 21st century. Except the standard value of spring temperature, the annual and seasonal temperature standard value in the THRHR and its three sub-headwater regions increased gradually, and the upward trend for the standard value of winter average temperature indicated significantly. （2） The tendency rate of annual average temperature in the THRHR was 0.36℃ 10a^-1, while the tendency rates in the Yellow River Headwater Region （YERHR）, Lancangjiang River Headwater Region （LARHR） and Yangtze River Headwater Region （YARHR） were 0.37℃ 10a^-1, 0.37℃ 10a^-1 and 0.34℃10a^-1 respectively. The temperature increased significantly in the south of Yushu County and the north of Nangqian County. The rising trends of temperature in winter and autumn were higher than the upward trends in spring and summer. （3） The abrupt changes of annual, summer, autumn and winter average temperature were found in the THRHR, LARHR and YARHR, and were detected for the summer and autumn average temperature in the YERHR. The abrupt changes of annual and summer average temperatures were mainly in the late 1990s, while the abrupt changes of autumn and winter average temperatures appeared primarily in the early 1990s and the early 21st century respectively. （4） With the global warming, the diversities of altitude and underlying surface in different parts of the Tibetan Plateau were possibly the main reasons for the high increasing rate of temperature in the THRHR.

Comparison of Positron Emission Tomography Using 2-[^18F]-fluoro-2-deoxy-D-glucose and 3-deoxy-3-[^18F]-fluorothymidine in Lung Cancer Imaging

Background： The detection of solitary pulmonary nodules （SPNs） that may potentially develop into a malignant lesion is essential for early clinical interventions. However, grading classification based on computed tomography （CT） imaging results remains a significant challenge. The 2-[^18F]-fluoro-2-deoxy-D-glucose （^18F-FDG） positron emission tomography （PET）/CT imaging produces both false-positive and false-negative findings for the diagnosis of SPNs. In this study, we compared 18F-FDG and 3-deoxy-3-[^18F]-fluorothymidine （^18F-FLT） in lung cancer PET/CT imaging. Methods： The binding ratios of the two tracers to A549 lung cancer cells were calculated. The mouse lung cancer model was established （n = 12）, and micro-PET/CT analysis using the two tracers was performed. Images using the two tracers were collected from 55 lung cancer patients with SPNs. The correlation among the cell-tracer binding ratios, standardized uptake values （SUVs）, and Ki-67 proliferation marker expression were investigated. Results： The cell-tracer binding ratio for the A549 cells using the ^18F-FDG was greater than the ratio using 18F-FLT （P 〈 0.05）. The Ki-67 expression showed a significant positive correlation with the ^18F-FLT binding ratio （r = 0.824, P〈 0.01）. The tumor-to-nontumor uptake ratio of ^18F-FDG imaging in xenografts was higher than that of ^18F-FLT imaging. The diagnostic sensitivity, specificity, and the accuracy of ^18F-FDG for lung cancer were 89%, 67%, and 73%, respectively. Moreover, the diagnostic sensitivity, specificity, and the accuracy of ^18F-FLT for lung cancer were 71%, 79%, and 76%, respectively. There was an obvious positive correlation between the lung cancer Ki-67 expression and the mean maximum SUV of ^18F-FDG and ^18F-FLT （r = 0.658, P〈 0.05 and r = 0.724, P〈 0.01, respectively）. Conclusions： The ^18F-FDG uptake ratio is higher than that of ^18F-FLT in A549 cells at the cellular level.^18F-FLT imaging might be superior for the quantitative diagnosis of lung tumor tissue and could distinguish lung cancer nodules from other SPNs.