Objective To explore the clinical significance of PET-CT in evaluating distant metastasis and M staging of nasopharyngeal carcinoma(NPC). Methods 257 NPC patients with no prior treatment were investigated with PET-CT and conventional imaging (chest X-ray, abdominal ultrasound, and bone scan). The findings of PET-CT in diagnosing distant metastasis and M staging were compared with those of conventional imaging according to the results of biopsy and follow-up. Results PET-CT disclosed 34 of 39 patients with distant malignancy compared with 22 patients disclosed by conventional imaging. The false positive rate of PET-CT was 12.8 %. On region-based analyses, PET-CT was more effective than bone scan and chest X-ray for detecting mediastinum metastasis (x2=4.063, P =0.041) and bone metastasis (x2=5.939, P=0.015), respectively. Compared with conventional imaging, PET-CT had an impact on the M staging of 19 patients (7.4 %), of which 15 patients were truly staged and 4 patients incorrectly staged. Conclusion PET-CT is superior to MRI in evaluating distant metastasis and M staging of NPC.

Purpose:The image information and technique of positron emitter nuclei generated by high energy X-ray photonuclear reactions with body tissues from MM50 is studied.It is explored to verify for dose delivery and location monitoring in tumor target after high energy photon radiation therapy with the image information.Materials and Methods:The technique is based on the photonuclear reactio-as in body tissues elemental composition ~(12)C,~(16)O and ~(14)N with high energy X-Ray,energies well above 20 MeV,resulting primarily in ~(11)C and ~(15)O but also ~(13)N.The induced positron activity distributions were scanned off-line in a PET/CT after irradiation.The activity distributions and position may be used to verify for dose delivery and location in tumor target.These radiations are similar to RT in three fields with some different dose delivery from TPS.The phantom began to be scanned off-line in a PET/CT a couple of minutes after irradiation.The scanning time is respectively 20 minutes and(2～5)mniutes for ~(12)C and ~(16)O.The levels of the beam energy are 10MV,25MV,50 MV.The extent of dose is 1.0 Gy～10.0 Gy.Since measured PET images change with time post irradiation,as a result of the different decay tim-es of the radionuclides,the signals from activated ~(12)C,~(16)O within the irradiated volume could be separated from each other.Most informationis obrained from the carbon and oxygen radionuclide's which the most abundant elements are in soft tissue.A brain phantom Rlade oneself was irradiated with high energy X-ray beams from IBA MM50.The 3D radiation treatment planning system,Nucletron-TPP 3.2,was used to calculate the delivered dose distributions.The phantom was directly simulated in the Nucletron-TPP after CT scan.PET/CT is fro-m GE Discovery LS Ⅱ.Resuits:It was confirmed that no activity was detected at 10 Mv X-ray energy,which was far below the energy threshold for photonuclear reactions.Totally 25 MV X-ray beams can produce photonuclear reactions and get to activity distributions images in PET/CT.It need to greater dose in order to good images information.For 50 MV X-ray beams,2 Gy-3 Gy dose,a normal RT dose,can get to activity distributions images.Conclusions:It was concluded that the PET-CT image acquired from the activity of the ~(15)O and ~(11)C positron emitter nuclei might provide the area and dose distribution information of 50 MV X-ray irradiation in a phantom.It can verify the in vivo dose delivery and location in tumor target after high energy X-ray RT.

Objective:To explore and compare the value of radiomic features based on 18F-fluorodeoxyglucose (FDG) PET and CT in distinguishing epidermal growth factor receptor (EGFR) mutation status in patients with lung adenocarcinoma. Methods:Pretreatment 18F-FDG PET/CT images and EGFR gene status of 114 patients (64 males and 50 females, aged range: 35-84 (average age: 61) years) with primary lung adenocarcinoma between January 2017 and December 2017 were retrospectively collected. The volume of interest was drawn manually slice by slice, then the features were extracted by the LIFEx software. The parameters were screened by least absolute shrinkage and selection operator (LASSO) method for 200 times, and ten-fold cross-validation was used to select the best tuning parameter λ. Three models, namely M PET, M CT, M PET+ CT, were constructed by binary logistic stepwise regression. The receiver operating characteristic (ROC) curve was generated and the corresponding area under the curve (AUC), sensitivity, specificity and accuracy were calculated. The AUCs of three models were compared by Delong test. Results:Totally, 53.51%(61/114) patients were with wild type EGFR and 46.49%(53/114) patients had EGFR mutation. There were 3, 3, 7 parameters selected to form M PET, M CT, M PET+ CT, respectively. The AUCs for M PET, M CT, M PET+ CT were 0.730, 0.752 and 0.866 respectively. When the cut-off values were 0.427, 0.522, 0.378 for M PET, M CT and M PET+ CT, the Youden index were up to the maximum as 0.420, 0.405, 0.630, with sensitivities of 83.0%(44/53), 58.5%(31/53), 92.5%(49/53), specificities of 59.0%(36/61), 82.0%(50/61), 70.5%(43/61) and accuracies of 70.2%(80/114), 71.1%(81/114), 80.7%(92/114), respectively. There was no significant difference between AUC of M PET and M CT ( z=-0.320, P>0.05). The differences of AUCs between M PET+ CT and M PET, M PET+ CT and M CT were statistically significant ( z values: 2.963, 2.523, both P<0.05). Conclusions:PET, CT and PET+ CT radiomic features are all associated with EGFR gene expression in lung adenocarcinoma. M PET+ CT has the highest predictive efficiency.

Objective To study positron yield quantitatively in different phantoms by means of PET imaging after high energy photon irradiation,and to investigate the feasibility of bio-dose verification by PET in high energy photon radiotherapy.Methods The phantoms (hydrogel,HDPE,inhomogeneous phantom) were scanned with PET 1 min later after exposure to 2,4,6,8 Gy dose with/using 25 and 50 MV photon irradiation.The positron account rates were recorded every minute in PET scanning process and then fitted to get the half-lives of yielded nuclides.Positron distribution in each phantom was compared with dose distribution to investigate the relationship between positron activity and dose delivered.Results The half-lives of nuclides yielded in hydrogel and HDPE were supposed to be 2.23 and 19.47 min,respectively by fitting results,which had negligible difference with half-lives of 11C (20.2 min) and 15O (2.08 min).The positron amounts induced by 50 MV photon in hydrogel and HDPE were 3.88 and 3.86 times that of 25 MV photon,and increased in proportion to dose delivered.Except for build-up region and cavity,activity distributions in depth and off-axis were similar to dose distribution.Conclusions The amount and distribution of positron induced by high energy photon are related to dose delivered,and it is feasible to do dose verification with PET imaging in high energy photon radiotherapy.

OBJECTIVETo quantitatively assess the left ventricular systolic dyssynchrony in patients with chronic heart failure based on the regional systolic dyssynchrony index (R-SDI) derived from real-time three-dimensional echocardiography (RT-3DE), and investigate the relation between R-SDI and the left ventricular systolic function.

METHODSForty-two patients with chronic heart failure (LVEF<50%) were classified into severe dysfunction group (group A, LVEF<40%) and mild dysfunction group (group B, LVEF≥40%), with 33 healthy subjects as the control group (LVEF>50%). RT-3DE was performed for each subject to obtain the left volume-time curves and the 16, 12, and 6 segment R-SDI. The value of R-SDI in assessing left ventricular systolic dyssynchrony and its correlation with LVEF were analyzed.

RESULTSThe 16, 12, and 6R-SDI were significantly higher in the chronic heart failure group than in the control group (P<0.01). The R-SDI of group A was significantly greater than those of group B in the chronic heart failure patients (P<0.01), and 16R-SDI, 12R-SDI, and 6R-SDI were inversely correlated with LVEF of the patients (r=-0.843, -0.840, and -0.841, respectively, P<0.01).

CONCLUSIONSR-SDI can be used to assess the left ventricular mechanic systolic dyssynchrony, and the degree of the dyssynchrony is inversely correlated with LVEF. RT-3DE can serve as a valuable modality for quantitative evaluation of left ventricular dyssynchrony in chronic heart failure patients.

Adult ; Aged ; Case-Control Studies ; Chronic Disease ; Echocardiography, Three-Dimensional ; methods ; Female ; Heart Failure ; diagnostic imaging ; Heart Ventricles ; diagnostic imaging ; Humans ; Male ; Middle Aged ; Systole ; Ventricular Dysfunction, Left ; diagnostic imaging ; Ventricular Function, Left