Clinical role of (18)~F-fluorodeoxyglucose positron emission tomography/computed tomography in post-operative follow up of gastric cancer: Initial results

AIM: To evaluate the clinical role of 18F-fluorodeo-xyglucose positron emission and computed tomography (18F-FDG PET/CT) in detection of gastric cancer recurrence after initial surgical resection. METHODS: In the period from January 2007 to May 2008, 23 patients who had previous surgical resection of histopathologically diagnosed gastric cancer underwent a total of 25 18F-FDG PET/CT scans as follow-up visits in our center. The standard of reference for tumor recurrence consisted of histopathologic confirmation or clinical follow-up information for at least 5 mo after PET/CT examinations. RESULTS: PET/CT was positive in 14 patients (61%) and negative in 9 (39%). When correlated with final diagnosis, which was confirmed by histopathologic evidence of tumor recurrence in 8 of the 23 patients (35%) and by clinical follow-up in 15 (65%), PET/CT was true positive in 12 patients, false positive in 2, true negative in 8 and false negative in 2. Overall, the accuracy of PET/CT was 82.6%, the negative predictive value (NPV) was 77.7%, and the positive predictive value (PPV) was 85.7%. The 2 false positive PET/CT findings were actually chronic inflammatory tissue lesions. For the two patients with false negativePET/CT, the f inal diagnosis was recurrence of mucinous adenocarcinoma in the anastomosis in one patient and abdominal wall metastasis in the other. Importantly, PET/CT revealed true-positive findings in 11 (47.8%) patients who had negative or no definite findings by CT. PET/CT revealed extra-abdominal metastases in 7 patients and additional esophageal carcinoma in one patient. Clinical treatment decisions were changed in 7 (30.4%) patients after introducing PET/CT into their conventional post-operative follow-up program. CONCLUSION: Whole body 18F-FDG PET/CT was highly effective in discriminating true recurrence in post-operative patients with gastric cancer and had important impacts on clinical decisions in a considerable portion of patients.

^(18)F-fluorodeoxyglucose positron emission tomography in the diagnosis of small pancreatic cancer

AIM:To investigate the role of 18 F-fluorodeoxyglucose positron emission tomography(FDG-PET) in the diagnosis of small pancreatic cancer. METHODS:This study involved 31 patients with proven invasive ductal cancer of the pancreas.The patients were divided into 3 groups according to the maximum diameter of the tumor:TS1(maximum tumor size≤2.0 cm) ,TS2(>2.0 cm and≤4.0 cm) or TS3-4(>4.0 cm) .The relationships between the TS and various diagnostic tools,including FDG-PET with dual time point evaluation,were analyzed. RESULTS:The tumors ranged from 1.3 to 11.0 cm in diameter.Thirty of the 31 patients(97%) had a positive FDG-PET study.There were 5 patients classified as TS1,15 as TS2 and 11 as TS3-4.The sensitivity of FDG-PET,computed tomography(CT) and magnetic resonanceimaging(MRI) were 100%,40%,0%in TS1,93%,93%,89%in TS2 and 100%,100%,100%in TS3-4. The sensitivity of FDG-PET was significantly higher in comparison to CT and MRI in patients with TS1(P< 0.032) .The mean standardized uptake values(SUVs) did not show a significant difference in relation to the TS(TS1:5.8±4.5,TS2:5.7±2.2,TS3-4:8.2±3.9) ,respectively.All the TS1 tumors(from 13 to 20 mm) showed higher SUVs in FDG-PET with dual time point evaluation in the delayed phase compared with the early phase,which suggested the lesions were malignant. CONCLUSION:These results indicate that FDG-PET with dual time point evaluation is a useful modality for the detection of small pancreatic cancers with a diameter of less than 20 mm.

Predictive value of ^(18)F-fluorodeoxyglucose PET/CT for transarterial chemolipiodolization of hepatocellular carcinoma

AIM： To investigate the correlation of 18F-fluorodeoxy- glucose （18F-FDG） positron emission tomography （PET） with clinical features and the prediction of treatment response. METHODS： A total of 83 hepatocellular carcinoma （HCC） patients undergoing 18F-FDG PET before transar- terial chemolipiodolization with systemic chemo-infusion between October, 2006 and May, 2009 were retrospec-tively enrolled. The patients included 68 men and 15 women （mean age, 60 ~ 10.7 years）. The effect of 18F- FDG-monitored PET uptake on clinical features and on the evaluated treatment response was ascertained with modified Response Evaluation Criteria in Solid Tumors. The PET parameters of maximal standardized uptake value of the tumor （Tsuvmax）, the ratio of the tumor maximal standardized uptake value （SUV） to the liver maximal SUV （Tsuvmax/Lsuwax） and the ratio of tumor maximal SUV to the liver mean SUV （msuvmax/LSUVrnean） were tested as predictive factors. RESULTS： Among the 3 SUV parameters, the TSUV- =maxdLsuvmean ratio （cutoff value of 1.90） was significantly associated with tumor burden including tumor size, tu- mor number, α-fetoprotein levels and tumor stage （P 〈 0.001, P = 0.008, P = 0.011, P 〈 0.001, respectively）. The objective response rates in patients with a high SUV ratio （≥ 1.90） were significantly better than those with a low SUV ratio （〈 1.90） （P = 0.020）. The overall survival rates of patients exhibiting a low Tsuvmax/Lsu- Vmean ratio （〈 1.90） and those with a high SUV ratio （≥1.90） was 38.2 and 10.3 mo, respectively （P 〈 0.01）. However, the time to progression showed no significant difference between the groups （P = 0.15）. CONCLUSION： 18F-FDG PET can be an important predictor of HCC treatment. In particular, the Tsuvmax/ Lsuwean ratio （cutoff value of 1.90） can provide useful information in treatment prognosis for HCC patients treated with Iocoregional therapy.

^(18)F-Fluorodeoxyglucose positron emission tomography/computed tomography comparison of gastric lymphoma and gastric carcinoma

AIM To compare ^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography(^(18)F-FDG PET/CT) features in gastric lymphoma and gastric carcinoma.METHODS Patients with newly diagnosed gastric lymphoma or gastric carcinoma who underwent ^(18)F-FDG PET/CT prior to treatment were included in this study. We reviewed and analyzed the PET/CT features of gastric wall lesions,including FDG avidity,pattern(focal/diffuse),and intensity [maximal standard uptake value:(SUVmax)]. The correlation of SUVmax with gastricclinicopathological variables was investigated by χ~2 test,and receiver-operating characteristic(ROC) curve analysis was performed to determine the differential diagnostic value of SUVmax-associated parameters in gastric lymphoma and gastric carcinoma. RESULTS Fifty-two patients with gastric lymphoma and 73 with gastric carcinoma were included in this study. Abnormal gastric FDG accumulation was found in 49 patients(94.23%) with gastric lymphoma and 65 patients(89.04%) with gastric carcinoma. Gastric lymphoma patients predominantly presented with type Ⅰ and type Ⅱ lesions,whereas gastric carcinoma patients mainly had type Ⅲ lesions. The SUVmax(13.39 ± 9.24 vs 8.35 ± 5.80,P < 0.001) and SUVmax/THKmax(maximal thickness)(7.96 ± 4.02 vs 4.88 ± 3.32,P < 0.001) were both higher in patients with gastric lymphoma compared with gastric carcinoma. ROC curve analysis suggested a better performance of SUVmax/THKmax in the evaluation of gastric lesions between gastric lymphoma and gastric carcinoma in comparison with that of SUVmax alone.CONCLUSION PET/CT features differ between gastric lymphoma and carcinoma,which can improve PET/CT evaluation of gastric wall lesions and help differentiate gastric lymphoma from gastric carcinoma.

Prognostic value of pre-and post-transplantation 18F-fluorodeoxyglucose positron emission tomography results in non-Hodgkin lymphoma patients receiving autologous stem cell transplantation

Objective： High-dose chemotherapy （HDC） followed by autologous stem cell transplantation （ASCT） is the standard of care in the upfront or relapsed/refractory setting in some patients with non-Hodgkin lymphoma （NHL）. However, a proportion of patients do not respond to ASCT. lSF-fluorodeoxyglueose （FDG） positron emission tomography （PET）/computed tomography （CT） has been widely used for staging, response evaluation, and prognosis prediction. Here, we investigated the prognostic role of PET/CT in NHL patients before and after ASCT. Methods： A retrospective study was conducted at Peking University Cancer Hospital. All NHL patients who underwent ASCT between March 2010 and July 2016 were identified. Patients who had PET/CT scan before and after ASCT were included. Deauville criteria （5-point scale） were used to interpret PET scans. Univariate and multivariate survival analyses were performed using Cox regression. The predictive value of PET scanning was estimated by comparing the area under the receiver operating characteristic （ROC） curve. Results： In total, 79 patients were enrolled in this study. In univariate analysis, pre- and post-ASCT PET result was identified as prognostic factors for 3-year progression-free survival （PFS） and overall survival （OS）. Patients with negative pre-ASCT PET result demonstrated significantly better PFS （84.2% vs. 54.2%） and OS （89.2% vs. 63.6%） than patients with positive pre-ASCT PET result. PFS （91.6% vs. 25.3%） and OS （96.5% vs. 36.8%） were also significantly different between patients with negative and positive post-ASCT PET result. Multivariate analysis also showed a significant association between survival and post-ASCT PET result. ROC analysis revealed that the predictive value of post-ASCT PET result was superior to that of pre-ASCT PET result alone. Combined pre- and post-ASCT PET result is better for predicting outcomes in patients with NHL receiving transplantation. Deauville criteria score 〉3 was identified as the best cutoffvalue for post-ASCT PET. Conclusions： Post-ASCT PET result was more important than pre-ASCT PET result in predicting outcomes for NHL patients who underwent ASCT. The prognostic significance can be improved when combining pre- ASCT PET result with post-ASCT PET result. Deauville criteria can be used for interpreting PET scans in this scenario.

Positron emission tomography/computed tomography with ^(18)F-fluorodeoxyglucose identifies tumor growth or thrombosis in the portal vein with hepatocellular carcinoma

Patients suffering from hepatocellular carcinoma (HCC) with tumor thrombus in the portal vein generally have a poor prognosis. Portal vein tumor thrombus must be distinguished from portal vein blood thrombus, and this identification plays a very important role in management of HCC. Conventional imaging modalities have limitations in discrimination of portal vein tumor thrombus. The application of positron emission tomography (PET) with 18F-fluorodeoxyglucose (18F-FDG) for discrimination between tumor extension and blood thrombus has been reported in few cases of HCC, while portal tumor thrombosis and portal vein clot identified by 18F-FDG PET/CT in HCC patients has not been reported so far. We present two HCC cases, one with portal vein tumor thrombus and one thrombosis who were identified with 18F-FDG PET/CT. This report illustrates the complimentary value of combining the morphological and functional imaging in achieving a correct diagnosis in such clinical situations.

Dynamic ^(18)F-fluorodeoxyglucose positron emission tomography/CT in hibernoma: enhanced tracer uptake mimicking liposarcoma

We report on two cases of patients with fat-equivalent masses in computed tomography(CT),referred to our department for dynamic positron emission tomography/CT(dPET/CT)with18F-fluorodeoxyglucose(18FFDG)in order to investigate their dignity.Both qualitative and quantitative information,as derived from dPET/CTs,couldn’t exclude a high-grade liposarcoma:Visual evaluation,revealed a large hypermetabolic focus of intense18F-FDG uptake in each patient(average SUVs 8.3 and 11.3).Regression-based parametric imaging demonstrated an enhanced distribution volume,which correlates to perfusion,and a high phosphorylation rate that correlates to cell viability.Kinetic analysis,based on a two-tissue compartment model demonstrated an enhanced FDG transport k1and an enhanced phosphorylation rate k3.A non-compartmental approach based on fractal dimension revealed also enhanced values.However,final diagnosis was based on biopsy,which revealed hibernoma,a benign brown fat tumor.Brown adipose contains increased numbers of mitochondria and a high-rate of glucose metabolism.Therefore,they have increased FDG uptake.The evaluation of lipomatous lesions on CT,with high FDG uptake,should include the possibility of hibernoma as a differential diagnosis.

^(18)F-fluorodeoxyglucose positron emission tomography/computed tomography in intrahepatic cholangiocarcinoma: could it be a new paradigm?

Intrahepatic cholangiocarcinoma(iCCA)is the second most common type of liver cancer after hepatocellular carcinoma,accounting for 15%of all primary liver neoplasms.In particular,iCCA is the most lethal tumor of these types,with the greatest increase in incidence in Western countries over the last decade(1,2).Local resection is the only treatment that can achieve cure,but resection rates remain low and survival is still limited to less than 1 year in the presence of locally unresectable or distant metastases(3).Its incidence and mortality have increased in recent years,and the total number of new cases is expected to increase up to 10-fold over the next two to three decades.In recent years,new treatments for iCCA have been developed and overall survival has improved.

Multiple primary malignant tumors of upper gastrointestinal tract:A novel role of ^(18)F-FDG PET/CT

AIM: To evaluate the capacity of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for detecting multiple primary cancer of upper gastrointestinal (UGI) tract. METHODS: Fifteen patients (12 without cancer histories and 3 with histories of upper GI tract cancer) were investigated due to the suspicion of primary cancer of UGI tract on X-ray barium meal and CT scan. Subsequent whole body 18F-FDG PET/CT scan was carried out for initial staging or restaging. All the patients were fi nally confi rmed by endoscopic biopsy or surgery. The detection rate of multiple primary malignant cancers was calculated based on 18F-FDG PET/CT and endoscopic examinations.RESULTS: 18F-FDG PET/CT scan was positive in 32 suspicious lesions, 30/32 were true positive primary lesions, and 2/32 were false positive. In 15 suspicious lesions with negative 18F-FDG PET/CT scan, 12/15 were true negative and 3/15 were false negative. Among the 15 patients, 12 patients had 29 primary synchronous tumors confirmed by pathology, including 8 cases of esophageal cancers accompanied with gastric cancer and 4 of hypopharynx cancers with esophageal cancer. The other 3 patients had 4 new primary metachronous tumors, which were multiple primary esophageal cancers. PET/CT imaging detected local lymph node metastases in 11 patients. Both local lymph node metastases and distant metastases were detected in 4 patients. On a per-primary lesion basis, the sensitivity, specificity, accuracy, negative predictive value and positive predictive value of 18F-FDG PET/CT for detecting multiple primary cancer of UGI tract were 90.9%, 85.7%, 89.4%, 80% and 93.7%, respectively. CONCLUSION: The whole body 18F-FDG PET/CT may play an important role in evaluating the multiple primary malignant tumors of UGI tract cancer.

Early detection of response to imatinib therapy for gastrointestinal stromal tumor by using 18F-FDG-positron emission tomography and computed tomography imaging

A 41-year old female with metastatic gastrointestinal stromal tumor was referred to 18F-FDG-positron emission tomography and computed tomography （PET/CT） scan before and after one-month treatment with imatinib （Glivec, Gleevec, Novartis, Basel, Switzerland）, a tyrosine kinase inhibitor （400 mg/d）. Metabolic response was evaluated before and after one month of therapy. The decrease of the maximum standardised uptake value （SUV） was 79% （from 9.8 to 2.1）. Positron emission tomography demonstrated complete metabolic response after one-month of imatinib treatment. Additionally, the previous lesion was compared with the coronal computerized tomographic image. There was no difference in the size of the tumor before and after therapy according to CT images. However, metabolic activity was inhibited. 18F-FDG-PEr is a valuable method for the detection of response to one-month imatinib treatment in patients with gastrointestinal stromal tumors.

Clinical usefulness of ^(18) F-FDG PET/CT in the restaging of esophageal cancer after surgical resection and radiotherapy

AIM： To evaluate the clinical usefulness of lSF-fluorodeoxyglucose positron emission and computed tomography QSF-FDG PET/CT） in restaging of esophageal cancer after surgical resection and radiotherapy. METHODS： Between January 2007 and Aug 2008, twenty histopathologically diagnosed esophageal cancer patients underwent 25 PET/CT scans （three patients had two scans and one patient had three scans） for restaging after surgical resection and radiotherapy. The standard reference for tumor recurrence was histopathologic confirmation or clinical follow-up for at least ten months after ^18F-FDG PET/CT examinations. RESULTS： Tumor recurrence was confirmed histopathologically in seven of the 20 patients （35%） and by clinical and radiological follow-up in 13 （65%）. ^18F-FDG PET/CT was positive in 14 patients （68.4%） and negative in six （31.6%）. ^18F-FDG PET/CT was true positive in 11 patients, false positive in three and true negative in six. Overall, the accuracy of ^18F-FDG PET/CT was 85%, negative predictive value （NPV） was 100%, and positive predictive value （PPV） was 78.6%.The three false positive PET/CT findings comprised chronic inflammation of mediastinal lymph nodes （n = 2） and anastomosis inflammation （n = 1）. PET/ CT demonstrated distant metastasis in 10 patients. ^18F-FDG PET/CT imaging-guided salvage treatment in nine patients was performed. Treatment regimens were changed in 12 （60%） patients after introducing ^18F-FDG PET/CT into their conventional post-treatment follow-up program. CONCLUSION： Whole body ^18F-FDG PET/CT is effective in detecting relapse of esophageal cancer after surgical resection and radiotherapy. It could also have important clinical impact on the management of esophageal cancer, influencing both clinical restaging and salvage treatment of patients.

Role of pre-transplant 18F-FDG PET/CT in predicting hepatocellular carcinoma recurrence after liver transplantation

The last two decades have seen a paradigm shift in the selection of patients with hepatocellular carcinoma(HCC)for liver transplantation.Microvascular invasion and differentiation have been the most significant factors affecting post-transplant recurrence;however,because of inherent disadvantages of pre-transplant biopsy,histological criteria never gained popularity.Recently,the selection criteria evolved from morphological to biological criteria,such as biomarkers and response to loco-regional therapy.With the introduction of multimodality imaging,combination of computed tomography with nuclear medicine imaging,particularly,18F-fluorodeoxyglucose positron emission tomography fulfilled an unmet need and rapidly became a critical component of HCC management.This review article will focus on the use of 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography in the pre-transplant evaluation of HCC patients with special discussion on its ability to predict HCC recurrence after liver transplantation.

Highly metabolic thrombus of the portal vein:^(18)F fluorodeoxyglucose positron emission tomography/computer tomography demonstration and clinical significance in hepatocellular carcinoma

AIM： To assess the ability of ^18F-fluorodeoxyglucose positron emission tomography/computer tomography （^18F-FDG PET/CT） to differentiate between benign and malignant portal vein thrombosis in hepatocellular carcinoma （HCC） patients.METHODS： Five consecutive patients who had HBV cirrhosis, biopsy-proven HCC, and thrombosis of the main portal vein and/or left/right portal vein on ultrasound （US）, computer tomography （CT） or magnetic resonance imaging （MRI） were studied with ^18F-FDG PET/CT. The presence or absence of a highly metabolic thrombus on ^18F-FDG PET/CT was considered diagnostic for malignant or benign portal vein thrombosis, respectively. All patients were followed-up monthly with US, CT or MRI. Shrinkage of the thrombus or recanalization of the vessels on US, CT or MRI during follow-up was considered to be definitive evidence of the benign nature of the thrombosis, whereas enlargement of the thrombus, disruption of the vessel wall, and parenchymal infiltration over follow-up were considered to be consistent with malignancy. ^18SF-FDG PET/CT, and US, CT or MRI results were compared.RESULTS： Follow-up （1 to 10 mo） showed signs of malignant thrombosis in 4 of the 5 patients. US, CT or MRI produced a true-positive result for malignancy in 4 of the patients, and a false-positive result in 1. ^18F-FDG PET/CT showed a highly metabolic thrombus in 4 of the 5 patients. ^18F-FDG PET/CT achieved a true-positive result in all 4 of these patients, and a true-negative result in the other patient. No false-positive result was observed using ^18F-FDG PET/CT.CONCLUSION： ^18F-FDG PET/CT may be helpful in discriminating between benign and malignant portal vein thrombi. Patients may benefit from ^18F-FDG PET/CT when portal vein thrombi can not be diagnosed exactly by US, CT or MRI.

Feasibility of sentinel lymph node biopsy omission after integration of ^(18)F-FDG dedicated lymph node PET in early breast cancer: a prospective phase II trial

Objective:Sentinel lymph node biopsy(SLNB)is currently the standard of care in clinically node negative(cN0)breast cancer.The present study aimed to evaluate the negative predictive value(NPV)of 18F-FDG dedicated lymph node positron emission tomography(LymphPET)in cN0 patients.Methods:This was a prospective phase II trial divided into 2 stages(NCT04072653).In the first stage,cN0 patients underwent axillary LymphPET followed by SLNB.In the second stage,SLNB was omitted in patients with a negative preoperative axillary assessment after integration of LymphPET.Here,we report the results of the first stage.The primary outcome was the NPV of LymphPET to detect macrometastasis of lymph nodes(LN-macro).Results:A total of 189 patients with invasive breast cancer underwent LymphPET followed by surgery with definitive pathological reports.Forty patients had LN-macro,and 16 patients had only lymph node micrometastasis.Of the 131 patients with a negative LymphPET result,16 patients had LN-macro,and the NPV was 87.8%.After combined axillary imaging evaluation with ultrasound and LymphPET,100 patients were found to be both LymphPET and ultrasound negative,9 patients had LN-macro,and the NPV was 91%.Conclusions:LymphPET can be used to screen patients to potentially avoid SLNB,with an NPV>90%.The second stage of the SOAPET trial is ongoing to confirm the safety of omission of SLNB according to preoperational axillary evaluation integrating LymphPET.

Clinical value of ^(18)F-FDG PET/CT in assessing suspicious relapse after rectal cancer resection

AIM:To evaluate the value of 18F-fluorodeoxyglucose positron emission tomography/computed tomography(18F-FDG PET/CT) in the restaging of resected rectal cancer.METHODS:From January 2007 to Sep 2008,21 patients who had undergone curative surgery resection for rectal carcinoma with suspicious relapse in conventional imaging or clinical findings were retrospectively enrolled in our study.The patients underwent 28 PET/CT scans(two patients had two scans,one patient had three and one had four scans).Locoregional recurrences and/or distant metastases were confirmed by histological analysis or clinical and imaging follow-up.RESULTS:Final diagnosis was confirmed by histopathological diagnosis in 12 patients(57.1) and by clinical and imaging follow-up in nine patients(42.9).Eight patients had extrapelvic metastases with no evidence of pelvic recurrence.Seven patients had both pelvic recurrence and extrapelvic metastases,and two patients had pelvic recurrence only.18F-FDG PET/CT was negative in two patients and positive in 19 patients.18F-FDG PET/CT was true positive in 17 patients and false positive in two.The accuracy of 18F-FDG PET/CT was 90.5,negative predictive value was 100,and positive predictive value was 89.5.Five patients with perirectal recurrence underwent 18F-FDG PET/CT image guided tissue core biopsy.18F-FDG PET/CT also guided surgical resection of pulmonary metastases in three patients and monitored the response to salvage chemotherapy and/or radiotherapy in four patients.CONCLUSION:18F-FDG PET/CT is useful for evaluating suspicious locoregional recurrence and distant metastases in the restaging of rectal cancer after curative resection.

Prognostic value of post-treatment ^(18)F-FDG PET/CT for advanced head and neck cancer after combined intra-arterial chemotherapy and radiotherapy

Objective：To clarify the prognostic value of post-treatment 18F-fluorodeoxyglucose （FDG） positron emission tomography （PET）/computed tomography （CT） in patients with advanced head and neck squamous cell carcinoma （HNSCC） after combined intra-arterial chemotherapy and radiotherapy （IACR）.Methods：Thirty-six patients with HNSCC who underwent IACR were recruited.The period from the end of IACR to the last post-treatment 18F-FDG PET/CT examination was 8-12 weeks.Both patient-based and lesion-based analyses were used to evaluate the PET/CT images.For lesion-based analysis,36 regions （12 lesions of recurrences and 24 scars at primary sites） were selected.The Kaplan-Meier method was used to assess the overall survival （OS） stratified by 18F-FDG uptake or visual interpretation results.Results：Twelve patients with recurrence were identified by six months after IACR.The sensitivity and specificity in the patient-based analysis were 67％ （8/12） and 88％ （21/24）,respectively.The mean OS was estimated to be 12.1 months （95％ CI,6.3-18.0 months） for the higher maximum standardized uptake value （SUVmax） group （n=7） and 44.6 months （95％ CI,39.9-49.3 months） for the lower SUVmax group （n=29）.OS in the higher SUVmax group （cut-off point,6.1） or positive visual interpretation group was significantly shorter than that in the lower SUVmax or negative visual interpretation group （P＜0.001 and P＜0.05,respectively）.Conclusions：The SUVmax and visual interpretation of HNSCC on post-IACR 18F-FDG PET/CT can provide prognostic survival estimates.

Optimal Threshold of Stimulated Serum Thyroglobulin Level for ^(18)F-FDG PET/CT imaging in Patients with Thyroid Cancer

This study was to explore the optimal threshold of thyroid-stimulating hormone(TSH)-stimulated serum thyroglobulin(s-Tg) for patients who were to receive18F-fluorodeoxyglucose(18F-FDG) PET/CT scan owing to clinical suspicion of differentiated thyroid cancer(DTC) recurrence but negative post-therapeutic 131I whole-body scan(131I-WBS). A total of 60 qualified patients underwent PET/CT scanning from October 2010 to July 2014. The receiver operating characteristic(ROC) curve analyses showed that s-Tg levels over 49 μg/L led to the highest diagnostic accuracy of PET/CT to detect recurrence, with a sensitivity of 89.5% and a specificity of 90.9%. Besides, bivariate correlation analysis showed positive correlation between s-Tg levels and the maximum standardized uptake values(SUVmax) of18F-FDG in patients with positive PET/CT scanning, suggesting a significant influence of TSH both on Tg release and uptake of18F-FDG. So, positive PET/CT imaging is expected when patients have negative 131I-WBS but s-Tg levels over 49 μg/L.

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.

^11C-methionine and ^18F-fluorodeoxyglucose positron emission tomography/CT in the evaluation of patients with suspected primary and residual/recurrent gliomas

Background ^18F-fluorodeoxyglucose （FDG） is the most widely used radiotracer in tumor imaging,but its use for brain gliomas and recurrence is limited by the high ^18F-FDG uptake in normal brain tissue.^11C-methionine （MET） has low uptake in the normal brain tissue,providing potential advantages over ^18F-FDG.The aim of the study was to investigate the diagnostic value of ^11C-MET compared to ^18F-FDG positron emission tomography and computed tomography （PET/CT） in patients with suspected primary and residual/recurrent gliomas.Methods Eighty paired PET/CT scans using ^11C-MET and 18F-FDG were performed on 44 newly diagnosed patients with suspected gliomas and 36 post-operative patients with suspected residual/recurrent tumors.PET/CT results were evaluated by visual and semiquantitative analysis.The sensitivity,specificity and accuracy for detection of gliomas and residual/recurrent tumors were calculated using visual analysis.Tumor to contralateral normal gray matter （T/G） ratio was calculated for semiquantitative analysis.Results Final pathology of the 44 newly diagnosed patients included 26 gliomas （14 high-grade and 12 low-grade tumors） and 18 non-glioma benign lesions.Residual/recurrent gliomas were verified in 28 patients and excluded in 8/36 post-operative patients by subsequent histopathologic examination and/or clinical follow-up for more than six months.The sensitivity,specificity and accuracy of 11C-MET PET/CT were 88.5%,83.3% and 86.4% for gliomas and 96.4%,87.5% and 94.4% for residual/recurrent gliomas,respectively.The sensitivity,specificity and accuracy of 18F-FDG PET/CT were 50.0%,88.9% and 65.9% for gliomas and 46.4%,100.0% and 58.3% for residual/recurrent gliomas,respectively.11C-MET had a higher sensitivity than 18F-FDG （83.3% vs.33.3%,P=0.031） in low-grade gliomas,but had no significant difference in sensitivity from 18F-FDG for high-grade gliomas （92.9% vs.64.3%,P=0.219）.11C-MET T/G uptake ratios in high-grade gliomas,low-grade gliomas and benign lesions were 1.94±0.53,1.78±0.61 and 1.06±0.34,respectively.18F-FDG T/G uptake ratios in high-grade gliomas,low-grade gliomas and benign lesions were 1.05±0.37,0.66±0.14 and 0.63±0.17,respectively.Conclusions 11C-MET PET/CT is superior to 18F-FDG PET/CT in detecting and delineating gliomas and residual/recurrent tumors,especially low-grade gliomas and residual/recurrent lesions present in gray matter,but its role in non-invasive grading of the tumors is limited.

Clinical applications of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography in carcinoma of unknown primary

Background Carcinoma of unknown primary （CUP） encompasses a heterogeneous group of tumors with varying clinical features. The management of patients of CUP remains a clinical challenge. The purpose of this study was to evaluate the clinical applications of integrated 18F-fluorodeoxyglucose positron emission tomography/computed tomography （FDG PET/CT） information in patients with CUP, including detecting the occult primary tumor and effecting on disease therapy.