[en] Objective: Evaluate the accuracy of co-registration of PET and CT (PET-CT) images on line with phantom, and utilize it on patients to provide clinical evidence for target delineation in radiotherapy. Methods: A phantom with markers and different volume cylinders was infused with various concentrations of ¹⁸FDG, and scanned at 4 mm by PET and CT respectively. After having been transmitted into GE eNTEGRA and treatment planning system (TPS) workstations, the images were fused and reconstructed. The distance between the markers and the errors were monitored in PET and CT images respectively. The volume of cylinder in PET and CT images were measured and compared by certain pixel value proportion deduction method. The same procedure was performed on the pulmonary tumor image in ten patients. Results: eNTEGRA and TPS workstations had a good length linearity, but the fusion error of the latter was markedly greater than the former. Tumors in different volume filled by varying concentrations of ¹⁸FDG required different pixel deduction proportion. The cylinder volume of PET and CT images were almost the same, so were the images of pulmonary tumor of ten patients. Conclusions: The accuracy of image co-registration of PET-CT on line may fulfill the clinical demand. Pixel value proportion deduction method can be used for target delineation on PET image. (authors)

[en] 3'-Deoxy-3'-Fluorothymidine (¹⁸F-FLT) is synthesized by 'BAThy' method at Tracerlab FX_f-N system. By using 5'-O-benzoyl-2,3-anhydro-thymidine (BAThy) as the precursor, ¹⁸F-FLT is obtained by two step reactions, including the nucleophilic fluoration and hydrolysis. The synthesis can be completed about 50 min. The radiochemical yield and radiochemical purity are about 10% and 95%, respectively. The procedure is guide simple and automated synthesis. (authors)

[en] Objective: To investigate the breast cancer and sentinel lymph node (SLN) with both ¹⁸F-FDG PET/CT and ⁹⁹Tc^m-SC SLN detection. Methods: 32 patients with breast mass without palpable lymph node involvement clinically were examined with ¹⁸F-FDG PET/CT. The breast masses and tissue of residual cavity were excised. 18 out of 32 patients were detected with ⁹⁹Tc^m-SC SPECT image and y -probe was applied to detect SLN during the operation. Histoimmunochemical and pathological analysis were also done after operation. Results: (1) The sensitivity, specificity and accuracy of primary breast lesion in 32 patients with ¹⁸F-FDG PET/CT image were 95.2%, 100% and 96.9%, respectively. (2) The lymph node metastasis were found in 5 out of 32 patients with PET/CT. The sensitivity, specificity and accuracy were 72.7%, 90.5% and 84.3%, respectively. (3) SPECT images showed SLN clearly in all of 18 patients. 1 out of 5 patients with metastatic SLN pathologically were also found axillary lymph nodes metastasis. No axillary lymph nodes metastasis were found in all the negative SLN patients. (4) Both of the majority negative coincidence and positive coincidence results were found in SLN detection and PET/CT image. Conclusion: SLN detection could predict the pathological state of following station of axillary lymph node. The effect in displaying primary breast lesion was superior to that of metastatic lymph node in PET/CT. There was better concordance in negative lymph node metastasis both with SLN detection and PET/CT but little false positive and false negative results could be found. (authors)

[en] Objective: Under different standard uptake value(SUV), to assess gross tumor volume (GTV) definition for non-small cell lung cancer (NSCLC) with 18-fluoro-deoxy-glueose positron emission tomography(¹⁸FDG PET) both under definite threshold (42 percent threshold) and various relative threshold (threshold SUV/maximum SUV) derived from the linear regressive function, threshold SUV=0.307 x (mean target SUV) + 0.588, with computer tomography(CT). Methods: Of 20 patients with non-small cell lung cancer, the CT GTV (GTV_CT), PET GTV with 42 percents threshold (GTV_42%) and PET GTV with relative threshold (GTV_relate) were obtained and compared. Results: The mean GTV_42%, mean GTV_relate and mean GTV_CT was (13 812.5±13 841.4), (24 325.3±22 454.7) and (28350.9± 26 079.8) mm³, respectively, with the difference in mean GTV among these three methods significant (F =. 10, P<0.01). The GTV_42% was smaller than the GTV_relate and the GTV_CT (P<0.01), with insignificant difference between GTV_relate and GTV_CT (P = 0.125 ). Conclusion: The relative threshold is more suitable to define the gross tumor volume than the definite threshold. (authors)

[en] Objective: The aim of this study was to assess the value of fusion SPECT perfusion and CT images acquired separately at 2 time-points in evaluating regional lung function of patients with stage III non-small cell lung cancer (NSCLC). Methods: Thirty-two patients with untreated stage III NSCLC under- went pulmonary function test (PFT), CT and SPECT imaging. Two series of images were registered by software fusion based on external markers by Philips Pinnacle3 planning treatment system. The SPECT/CT fusion images were graded by comparing lung perfusion defect with the area of radiological abnormality. Grade 0: no lung perfusion defect in the area of radiological abnormality. Grade 1: the area of lung perfusion defect was similar to the size of radiological abnormality. Grade 2: the area of lung perfusion defect was bigger than that of radiological abnormality, and extended to 1 pulmonary lobe. Grade 3: the area of lung perfusion defect exceeded 1 pulmonary lobe. Statistically significant difference was evaluated by Pearson χ²-test using SPSS 13.0 software. Results: In 32 patients with stage III NSCLC, 31 patients had lung perfusion defects. There were 13 patients with grade 1, 8 with grade 2, 10 with grade 3. There was statistically significant difference between central lung cancer and peripheral lung cancer (χ²=10.49.5, P<0.05); 8 patients had PFT abnormality. There was also statistically significant difference between the positive rate of SPECT/CT fusion images and PFT [96.9% (31/32) vs25.0%(8/32), χ²=34.724, P<0.05]. Conclusion: The fusion of SPECT lung perfusion and CT images acquired separately at 2 different time-points is a feasible technique for assessing the regional lung function of patients with stage III NSCLC, thereby offering more in- formation for surgical planning, prediction of postoperative lung function and optimization of radiation treatment plans. (authors)

[en] Objective: The aim of this study was to investigate the radiation dose caused by ¹⁸F-flu- orodeoxyglucose (FDG) in PET/CT examination and to optimize the concerned radiation protection. Methods: Thirty patients from our conventional PET/CT examination were simple randomly selected, and they all underwent whole body PET/CT imaging. The radioactive dose of injected ¹⁸F-FDG was recorded. The internal radiation dose was calculated and the external radiation dose from patients was measured with the 451P-DE-SI ion chamber survey meter. The staff's dose was recorded with thermoluminescent detector (TLD). All dosimetry data were processed and analyzed statistically with Excel 2003. Results: The injected radioactive dose of ¹⁸F-FDG was (432.9 ± 51.8) MBq, and effective dose equivalent received per patient was (8.23 ± 0.99) mSv. The correlation coefficient (r) of the dose equivalent rate and distance was -0.994 by power function curve fitting, and that of dose equivalent rate and time was -0.988 by exponential curve fitting. The staff's dose was lower than the annual dose limit. Conclusions: The patient's internal radiation dose caused by ¹⁸F-FDG in PET/CT examination is low, nonetheless, the clinician should always consider optimizing and minimizing the necessary radiation received by the patients. The patients having been injected with ¹⁸F-FDG should stay in one place to decrease their radiation to the public. From the medical point of view in optimizing radiation exposure, there may still be a potential to lower the injected ¹⁸F-FDG activity. (authors)

[en] Objective: To observe the tumor hypoxia changes with serial ⁹⁹Tc^m-4,9-diaza-3,3,10,10-tetramethyldodecan-2, 11-dione dioxime (HL91) SPECT images during radiotherapy in non-small cell lung cancer (NSCLC) patients. Methods: 20 patients with pathologically proved NSCLC during three-dimensional conformal radiotherapy were enrolled into the study. ⁹⁹Tc^m-HL91 SPECT imaging were performed at 1-2 d before radiotherapy, during radiotherapy (30-40 Gy), and 1-2 d after radiotherapy respectively. anterior, posterior and lateral planar images were performed 2,4 and 6h after injected 740 MBq ⁹⁹Tc^m-HL91 intravenously. Regions of interest (ROI) were drawn in the tumor and contralateral position and the ratios of tumor to normal (T/N) were calculated. The hypoxia changes were analyzed. Results: The T/N value of radiotherapy patients were gradually decreased during and after radiotherapy. The average T/N value before, during and after radiotherapy were 1.56 ± 0.19, 1.40 ± 0.12 and 1.29 ± 0.13 respectively. There ws significant statistical difference between these three groups (P=0.01). Conclusions: Preliminary results showed that there was changed hypoxia during radiotherapy for NSCLC. It provided a valuable method to detect reoxygenation in human tumor. (authors)

[en] Objective: To determine the prognostic value of standardized uptake value (SUV) of fluorodeoxyglucose(FDG) by positron emission tomography and computed tomography (PET-CT) in non-small cell lung cancer (NSCLC). Methods: Forty-eight patients (39 male, 9 female) with stage III NSCLC were reviewed. All patients had at least two repeated FDG PET-CT scans either before and after therapy and the maximum standardized uptake value (SUV_max) of the primary lung lesion was calculated. Results: Of the 45 eligible patients, after a median follow-up of 22.5 months (rang, 13 to 35 months), 24 patients had local and regional recurrence or metastasis and 21 remain disease-free. The mean SUV_max of patients who had local recurrence or metastasis before and after treatment was 12.30 ± 3.17 and 5.35 ± 2.29, respectively. The mean SUV_max of patients who had no local recurrence or metastasis before and after treatment was 8.46 ± 3.00 and 2.82 ± 0.63, respectively. Significant differences (t_before=4. 15, P_before< 0.01; P_after=4.88, P_after<0.01) in SUV_max were observed either before and after treatment. However, the percent change of SUV_max between pretreatment and post-treatment were not significantly different (t=1.99, P> 0.05). Using the SUVbefore of 9.0 yielded 92% sensitivity, 62% specificity, 73% positive predictive value and 87% negative predictive value in predicting regional recurrence or metastasis. While using the SUVafter of 4.3 yielded 71% sensitivity, 100% specificity, 100% positive predictive value and 72% negative predictive value. Conclusions: PET-CT may have the potentials to predict response to therapy and the SUV_max is a significant predictor for recurrent or metastasis in patients of NSCLC. (authors)

[en] Objective: To assess the prognostic value of tumor burden measured by ¹⁸F-fluoro deoxy glucose-positron emission tomography (FDG PET) imaging for stage III NSCLC). Methods: Fifty-six patients with lung cancer were analyzed, to whom staging PET-CT scans before treatment concurrent chemoradiotherapy and 2-year follow-up were performed. , Relationship between overall survival (OS) and metabolic tumor volume (MTV) and maximum standardized uptake value (SUV_max) were determined. Results: The estimated median OS for the cohort were 14.5 months. Kaplan-Meier analysis showed that MTV had a significant effect on OS (χ² =5.42, P =0.014). No significant relationship was found between SUV_max and OS (χ² = 0.74, P = 0.391). According to multivariate Cox regression analysis, MTV and SUV_max were associated with increased death (χ² = 5.54, P = 0.019; χ² = 4.47, P = 0.031). Conclusions: This study shows that higher tumor burden assessed by PET MTV is an independent unfavorable prognostic factor in lung cancer, MTV is valuable for predicting overall survival and could be a prognostic factor. (authors)

[en] Objective: It was realized that static PET imaging might not be accurate at fixed time point after ¹⁸F-FDG administration. The dual phase ¹⁸F-FDG PET was employed in this study in order to differentiate malignant from benign lesions. Methods: Fifty-two patients with difficulty in interpreting the nature of their lesions at routine imaging underwent delayed whole body ¹⁸F-FDG PET at 2 h post-injection. Visual inspection of PET images and SUV compared with pathological finding were used for evaluation. Resuits: Of 43 cases with increased SUV in delay imaging, 39 were confirmed malignant and 4 benign. And 7 of 9 cases with decreased SUV were confirmed benign and 2 malignant. The dual phase PET imaging in this group of patients had sensitivity of 95.1%, specificity 63.6%, accuracy 88.5%, positive predictive value 90.7%, and negative predictive value 7/9. Conclusion: In differentiating malignant from benign lesions, dual phase PET was more accurate than single static imaging. (authors)