2-[18F]-fluoro-2-desoxy-D-glucose positron emission tomography initial staging impacts on survival in Hodgkin lymphoma

AIM:To assess the prognostic value and risk classification improvement of metabolic staging(MS)with Initial2-[18F]-fluoro-2-desoxy-D-glucose positron emission tomography(FDG-PET)in initial staging of Hodgkin’s Lymphoma(HL)patients to predict 5 years overall survival(5y-OS)and event free survival(EFS).METHODS:A total of 275 patients were included in this retrospective study,155 patients were staged with conventional anatomical staging(AS),and 120 also submitted to MS(FDG-PET).Prognostic analysis compared 5y-OS and 5y-EFS of patients staged with AS and MS.Risk-adjusted models incorporated clinical risk factors,computed tomography and FDG-PET staging.RESULTS:During the follow up of 267 evaluated patients,220(122 AS and 98 MS)achieved complete remission after first-line therapy(median follow-up:70±29 mo),treatment failure occurred in 79 patients and 34 died.The 5y-EFS for early vs advanced disease in AS patients was 79.3%and 66.7%,and 85.6%and53.6%in MS patients,respectively(P<0.01).The5y-OS for early and advanced disease with AS was91.3%and 81.5%,and 97.5%and 80.7%for patients staged with MS,respectively.Cox proportional hazards analysis demonstrated that FDG-PET added signifcant prognostic information and improved risk prediction(P=0.02).CONCLUSION:Initial staging FDG-PET could be used as an accurate and independent predictor of OS and EFS in HL,with impact in 5y-EFS and OS.

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.

[^18F]2-fluoro-2-deoxyglucose positron emission tomography/ computed tomography in predicting radiation pneumonitis

Background Prevention is presently the only available method to limit radiation-induced lung morbidity. A good predictor is the key point of prevention. This study aimed to investigate if [^18F]2-fluoro-2-deoxyglucose （FDG） uptake changes in the lung after radiotherapy could be used as a new predictor for acute radiation pneumonitis （RP）. Methods Forty-one patients with lung cancer underwent FDG positron emission tomography/computed tomography （FDG-PET/CT） imaging before and after radiotherapy. The mean standardized uptake value （SUV） was measured for the isodose regions of 0-9 Gy, 10-19 Gy, 20-29 Gy, 30-39 Gy, 40-49 Gy. The mean SUV of these regions after radiotherapy was compared with baseline. The mean SUV in patients who developed RP was also compared with that in those who did not. The statistical difference was determined by matched pair t test. The Radiation Therapy Oncology Group （RTOG） criteria were used for diagnosis and grading of RP. Results With a median follow-up of 12 months, 11 （26.8%） of the 41 patients developed grade 2 and above acute RP. The mean SUV of regions （10-19 Gy, 20-29 Gy, 30-39 Gy, 40-49 Gy） increased after radiation therapy in all 41 patients. The mean SUVs after radiation therapy were 0.54, 0.68, 1.31, 1.74 and 2.27 for 0-9 Gy, 10-19 Gy, 20-29 Gy, 30-39 Gy and 40-49 Gy, respectively. Before the radiation therapy, the mean SUV in each region was 0.53, 0.52, 0.52, 0.53 and 0.54, respectively. These patients had significantly higher FDG activities in regions receiving 10 Gy or more （P 〈0.001）. Compared with their counterparts, the elevation of SUV was significantly greater in those patients who developed acute RP subsequently. Conclusion The mean SUV of the lung tissue may be a useful predictor for the acute RP. FDG-PET/CT may play a new role in the study of the radiation damage of the lung.

Comparison of diagnostic value of PET using 18- fluoro-2-deoxyglucose, CT and MR1 in detecting skull base invasion of nasopharyngeal carcinomas

Objective： We compared positron emission tomography （PET） using 18-fluoro-2-deoxyglucose （FDG）, enhanced computed tomography （CT） and magnetic resonance imaging （MRI） in detecting skull base invasion of nasopharyngeal carcinomas （NPC） and to evaluate the value of these three methods in determining the existence of skull base invasion of nasopharyngeal carcinomas. Methods： The images of enhanced CT, MRI and PET-CT scans, performed at intervals -〈 20 days on 57 NPC patients from July 2004 to February 2007, were selected and reviewed. The endpoints of the comparison were sensitivity, specificity, accuracy, positive predictive value （PPV） and negative predictive value （NPV） of Enhanced CT, MRI and PET-CT, based on histopathologic findings or clinical imaging follow-up for at least 6 months. Results： For detecting skull base invasion of NPC, the sensitivity of enhanced CT, MRI and PET-CT were 68.18%, 84.09%, 97.67% respectively; speci- ficity were 76.92%, 69.23%, 57.14% respectively; accuracy were 70.18%, 80.7%, 87.72% respectively; PPV were 90.9%, 90.24%, 87.5% respectively; NPV were 41.67%, 56.25%, 88.89% respectively. Conclusion： PET-CT has obvious advantages in sensitivity over CT （P 〈 0.05） and MRI, better than the two methods in accuracy and NPV and may be more valuable for new patients in detecting skull base invasion of NPC patients.

Significant value of 18F-FDG-PET/CT in diagnosing small cervical lymph node metastases in patients with nasopharyngeal carcinoma treated with intensity-modulated radiotherapy

Background: Little is known about the nature of metaistasis to small cervical lymph nodes(SCLNS) in the patients with nasopharyngeal carcinoma(NPC)examined by using 18-fluoro-2-deoxy-glucose(^(18)F-FDG) positron emission tomography/computed tomography(PET/CT).The present study aimed to evaluate the diagnostic values of PET/CT in identifying metastasis in SCLNs in NPC patients.Methods: Magnetic resonance images(MRI) and PET/CT scans for 470 patients with newly diagnosed, non-distant metastatic NPC were analyzed. Metastatic rates of SCLNs were defined by the positive number of SCLNs on PET/CT scans and total number of SCLNs on MRI scans. Receiver operating characteristic curve was applied to compare PET/CT-determined stage with MRI-determined stage.Results: In total, 2082 SCLNs were identified, with 808(38.8%) ≥ 5 and < 6 mm in diameter(group A), 526(25.3%)≥ 6 and < 7 mm in diameter(group B),374(18.0%)≥ 7 and < 8 mm in diameter(group C), 237(11.4%) ≥8 and<9 mm in diameter(group D),and 137(6.5%) ≥ 9 and <10 mm in diameter(group E).The overall metastatic rates examined by using PET/CT for groups A, B,C,D, and E were 3.5%, 8.0%, 31.3%, 60.0%, and 83.9%, respectively(P< 0.001). In level IV/Vb, the metastatic rate for nodes ≥ 8 mm was 84.6%. PET/CT examination resulted in modification of N category and overall stage for 135(28.7%) and 46(9.8%) patients, respectively. The areas under curve of MRIdetermined and PET/CT-determined overall stage were 0.659 and 0.704 for predicting overall survival, 0.661 and 0.711 for predicting distant metastasis-free survival, and 0.636 and 0.663 for predicting disease-free survival.Conclusions: PET/CT was more effective than MRI in identifying metastatic SCLNs, and the radiologic diagnostic criteria for metastatic lymph nodes in level IV/Vb should be re-defined.

Postoperative reactive lymphadenitis: A potential cause of false-positive FDG PET/CT

A wide variety of surgical related uptake has been reported on F18-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography(FDG PET/CT) scan, most of which can be differentiated from neoplastic process based on the pattern of FDG uptake and/or anatomic appearance on the integrated CT in image interpretation. A more potential problem we may be aware is postoperative reactive lymphadenitis, which may mimic regional nodal metastases on FDG PET/CT. This review presents five case examples demonstrating that postoperative reactive lymphadenitis could be a false-positive source for regional nodal metastasis on FDG PET/CT. Surgical oncologists and radiologists should be aware of reactive lymphadenitis in interpreting postoperative restaging FDG PET/CT scan when FDG avid lymphadenopathy is only seen in the lymphatic draining location from surgical site.

Metformin and cancer: Technical and clinical implications for FDG-PET imaging

Metformin is the most widely used hypoglycemic agent. Besides its conventional indications, increasing evidence demonstrate a potential efficacy of this biguanide as an anticancer drug. Possible mechanisms of actions seem to be independent from its hypoglycemic effect and seemto involve the interference with key pathways in cellular proliferation and glycolysis. To date, many clinical trials implying the use of metformin in cancer treatment are on-going. The increasing use of 18F-2-fluoro-2-deoxyd-glucose positron emission tomography(FDG-PET) in cancer evaluation raises a number of questions about the possible interference of the biguanide on FDG distribution. In particular, the interferences exerted by metformin on AMP-activated protein kinase pathway(the cellular energy sensor), on insulin levels and on Hexokinase could potentially have repercussion on glucose handling and thus on FDG distribution. A better comprehension of the impact of metformin on FDG uptake is needed in order to optimize the use of PET in this setting. This evaluation would be useful to ameliorate scans interpretation in diabetic patients under chronic metformin treatment and to critically interpret images in the context of clinical trials. Furthermore, collecting prospective data in this setting would help to verify whether FDG-PET could be a valid tool to appreciate the anticancer effect of this new therapeutic approach.

Malignant Triton Tumor in the Abdominal Wall: A Case Report

Malignant triton tumor (MTT) is a rare variant of malignant peripheral nerve sheath tumor (MPNST) with rhabdomyosarcomatous differentiation. We report the case of a 54-year-old male without a history of neurofibromatosis type 1 (NF1) who had a growing abdominal wall tumor diagnosed as MTT. Computed tomography (CT), magnetic resonance imaging (MRI) and 2-[F-18]-fluoro-2-deoxy-D-glucose positron emission tomography/CT (FDG-PET/CT) were performed. The MRI and FDG-PET/CT indicated that the lateral component of the tumor was composed of many proliferative cells, corresponding to the histopathological finding of a cellular proliferation of spindle-shaped cells. In light of this case and previous reports, it is apparent that FDG-PET/CT is a helpful tool for distinguishing MTT from benign peripheral nerve sheath tumor.