ObjectiveTo analyze the influencing factors for image quality of 18F-deoxyglucose (FDG) positron emission tomography (PET)/CT systemic tumor imaging and explore the method of control in order to improve the PET/CT image quality. MethodsRetrospective analysis of image data from March to June 2011 collected from 1 000 18F-FDG whole body tumor imaging patients was carried out. We separated standard films from non-standard films according to PET/CT image quality criteria. Related factors for non-standard films were analyzed to explore the entire process quality control. ResultsThere were 158 cases of standard films (15.80%), and 842 of non-standard films (84.20%). Artifact was a major factor for non-standard films (93.00%, 783/842) followed by patients’ injection information recording error (2.49%, 21/842), the instrument factor (1.90%, 16/842), incomplete scanning (0.95%, 8/842), muscle and soft tissue uptake (0.83%, 7/842), radionuclide contamination (0.59%, 5/842), and drug injection (0.24%, 2/842). The waste film rate was 5.80% (58/1 000), and the redoing rate was 2.20% (22/1 000). ConclusionComplex and diverse factors affect PET/CT image quality throughout the entire process, but most of them can be controlled if doctors, nurses and technicians coordinate and cooperate with each other. The rigorous routine quality control of equipment and maintenance, patients’ full preparation, appropriate position and scan field, proper parameter settings, and post-processing technology are important factors affecting the image quality.
ObjectiveTo analyze the relationship between maximum standardized uptake value (SUVmax) of primary tumor detected by 18F-FDG positron emission tomography/computed tomography (PET/CT) and clinicopathologic factors in stageⅠnon-small cell lung cancer (NSCLC), and investigate the prognostic value of PET/CT on pathological feature. MethodsWe retrospectively analyzed clinical data of 182 patients with stageⅠNSCLC who underwent 18F-FDG PET/CT scan before lobectomy or segmentectomy in China-Japan Friendship Hospital from April 2013 to June 2014. There were 121 male and 61 female patients with their ages of 34-85 (68.1±9.8) years. Clinicopathologic factors including sex, age, smoking history, histology, TNM stage, T stage, tumor size, lymphatic vessel invasion, blood vessel invasion (BVI) and visceral pleural invasion were evaluated to identify the independent factors affecting SUVmax by univariate and multivariate regression analysis. The diagnostic efficiency and best cut-off point of SUVmax were calculated by the receiver operating characteristic curve. ResultsThe univariate analysis identified that sex (P=0.015), smoking history (P=0.001), histology (P < 0.001), TNM stage (P=0.004), T stage (P=0.001), tumor size (P < 0.001), BVI (P=0.001) were factors affecting SUVmax. Only histology (P=0.001), tumor size (P=0.006), BVI (P=0.009) were found to be significant independent factors according to multivariate regression analysis. The SUVmax of primary tumor was a predictor for BVI with the highest diagnostic accuracy at a cut-off value of 4.85, the sensitivity and specificity were 65.5% and 71.7%. ConclusionThe SUVmax is correlated with histology, tumor size and BVI in stageⅠNSCLC, higher in patients with non-adenocarcinoma, lager tumor and positive BVI. Furthermore, the probability of BVI could be predicted by SUVmax of the primary tumor.
ObjectiveTo assess the use of 18-Fluorine-labelled 2-deoxy-2-fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) in the diagnosis of uveal melanoma. MethodsTwenty-three patients with uveal melanoma confirmed by histopathologic examination or imaging examination were enrolled. There were 16 male, 7 female, and the mean age was (49.8±12.3) years. All the lesions were unilateral, with 11 cases in OD, 12 cases in OS. Diagnosis was confirmed by histopathological examination of enucleated eyeballs in 15 cases, by ophthalmoscope, fundus fluorescein angiography, ocular B-mode ultrasound and magnetic resonance imaging and other imaging technology in 8 cases. 15 patients diagnosed by histopathologic examination of enucleated eyeballs were divided into three types including mixed (7 patients), spindle cell (6 patients) and epithelioid cell (2 patients) types. The mixed cell type and epithelioid cell type are considered as high-risk; spindle cell type is low-risk. All the patients were evaluated by whole body PET/CT. The location, size, shape, boundary of the lesions, and the relationship with adjacent structures were observed in CT images. 18F-FDG uptake was quantitative expression by standardized uptake value (SUV) in PET image; positive diagnosis should be made when the maximum standardized uptake value (SUVmax) was not less than 2.5. The correlation between SUVmax and maximum diameter of tumor base, tumor height was analyzed by Spearman rank correlation test. The detection rate of high-risk and low-risk patients between 18F-FDG PET and CT methods was comparative analyzed. ResultsAll the CT images showed abnormal high density ocular lesions. The shape of the lesions included 8 patients of semi sphere-like, 7 patients of flat-like, 4 patients of mushroom-like, 3 patients of round-like and 1 patient of diffuse lesions. The tumors were located in the posterior pole (9 patients), temporal equator (5 patients), nasal equator (4 patients), superior equator (1 patient), temporal ciliary body (1 patient), inferior ciliary body (1 patient), temporal iris (1 patient), and nasal iris and ciliary body (1 patient). SUVmax≥2.5 were found in 9 patients (39.13%), the largest basal diameter and height were (17.53±3.48), (11.37±3.85) mm respectively. SUVmax < 2.5 were found in 14 patients (60.87%), the largest basal diameter and height were (10.66±3.25), (5.33±2.23) mm respectively. The former's largest basal diameter and height were greater than the latter's and the difference was statistically significant (t=4.815, 4.786; P < 0.01). SUVmax was positively correlated with the largest basal diameter and height respectively (r=0.881, 0.809; P < 0.01). 15 patients (39.13%) were diagnosed by histopathological diagnosis after enucleation, of which SUVmax≥2.5 were found in 8 patients which included 6 patients of mixed type, 1 patient of epithelioid cell type, and 1 patient of spindle cell type. The detection rate of high-risk type (77.78%, 7/9) was higher than that of low-risk type (16.67%, 1/6), the difference was statistically significant (χ2=5.402, P < 0.05). Conclusions18F-FDG PET-CT examination can show large uveal melanoma tumor from cell metabolism, and may help to evaluate the prognosis of the preoperative patients. But, for small tumor, it has little value. We don't recommend 18F-FDG PET-CT is used as a routine examination for uveal melanoma.