The Value Of CT And ¹⁸F-FDG PET/CT Imaging In The Diagnosis Of Pulmonary Sclerosing Pneumocytoma

Objective:?1? Retrospectively analysed the unenhanced CT findings such as halo sign, calcification, air crescent sign, lobulation and the enhanced CT findings such as overlying vessel sign, degree of enhancement and enhanced CT features,to explore the value of CT imaging and enhanced CT imaging in pulmonary sclerosing pneumocytoma.?2? Retrospectively reviewed the ¹⁸F-FDG PET/CT imaging data of pulmonary sclerosing pneumocytoma, comprehensively analysed the relationship between the size of the lesion and SUVmax, the correlation between SUVmax and clinical symptoms in patients with pulmonary sclerosing pneumocytoma and pathological features of atypical pulmonary sclerosing pneumocytoma,and explore the diagnostic value of ¹⁸F-FDG PET, ¹⁸F-FDG PET/CT and ¹⁸F-FDG PET combined with enhanced CT in pulmonary sclerosing pneumocytoma.Materials and Methods:?1? 135 patients who took CT and?or? enhanced CT examination and were pathologically confirmed to have pulmonary sclerosing pneumocytoma by surgery, fine-needle aspiration and follow-up from November 2008 to November 2015 in Tianjin Medical University Cancer Hospital. Their clinical, pathological and imaging data were retrospective reviewd. The clinical characteristics of pulmonary sclerosing pneumocytoma were summarized. Clinical and imaging data of 66 cases solid pulmonary sclerosing pneumocytoma among the 135 patients were well-preserved. The unenhanced CT imaging features such as halo sign, air-crescent sign, lobulation, calcifications were observed and summarized. By using SPSS 17.0 statistical Package, independent samples t-test was selected to compare the tumor size between the symptomatic and asymptomatic group and P<0.05 was considered as statistically significal. The enhanced CT imaging data of 46 cases solid pulmonary sclerosing pneumocytoma were well-preserved and net increased CT value ?CT and punctate or focal low density after enhancement, overlying vessel sign were comprehensively analyzed. In addition, uncommon imaging characteristics and clinical manifestations of pulmonary sclerosing pneumocytoma were summarized.?2? Well-preserved ¹⁸F-FDG PET/CT imaging data of 22 patients who took PET/CT scans in the PET/CT center of Tianjin Medical University Cancer Hospital with 23 diagnosed pulmonary sclerosing pneumocytoma from November 2008 to November 2015 were retrospectively reviewed and comparatively analyzed. Usinging SPSS 17.0 statistical package,linear regression analysis between lesion size and SUVmax were carried out. Correlation between tumor size and SUVmax in typical and atypical pulmonary sclerosing pneumocytoma respectively analyzed through linear regression analysis. Independent samples t-test were selected to compare the SUVmax between symptomatic and asymptomatic group and P<0.05 was considered as statistically significal. Atypical radiological and pathological features in pulmonary sclerosing pneumocytoma were summarized. Retrospective analysed seven cases pulmonary sclerosing pneumocytoma both took PET/CT scan and enhancement CT examination,SUVmax and net increased CT value ?CT was comprehensive analysed.Results:?1? Calcification appeared in 36.3%?24/66? of solid lesions, halo sign around the solid lesions accounted for 37.9%?25/66?, air crescent sign appeared in 9.1%?6/66? of the tumors, and lobulated lesions accounted for 9.1 %?6/66??5 cases got calcification within the lesion?. Six cases of patients with hemoptysis, among them five patient got halo sign around their lesions. Independent samples t-test showed their was no correlation between the size of the lesion and the symptoms?P = 0.543?. Enhanced CT imaging features of 46 cases of solid lesions showed that unenhanced CT value ranged from 6 to 64 HU, the mean CT value was 33 ± 12.70 HU, the enhanced CT value ranged from 63 to 148 HU, and the mean enhanced CT value was 101 ± 22.49 HU, the net increased CT value ?CT ranged from 25 to 111 HU, and ?CTmean was 68 ± 22.58 HU. overlying vessel sign appear in 82.6%?38/46? of the 46 tumors, heterogeneous enhancement accounted for 87.0%?40/46?, and punctate or focal low density accounted for 80.4%?37/46? after enhancement.?2?22 patients included 11 males and 11 females took ¹⁸F-FDG PET / CT scan and 23 lesions were found, among which 14 nodules and masses showed round, sharp edges, and the other 9 cases were irregular shape. All of the atypical PSP were found in male patients. The average lesion diameter of the 23 cases of lesions was 2.6cm?0.6 7.0 cm?, and SUVmax ranged from 0.75 to 13.80?3.85 ± 3.02?. 69.5%?16/23? of the lesions showed intense ¹⁸F-FDG uptake, four cases showed moderate uptake and 3 patients did not show significant radioactive concentration. Linear regression analysis showed there was correlation between SUVmax and the tumor size?r = 0.486, P = 0.019?. The SUVmax of the typical pulmonary sclerosing pneumocytoma ranged from 0.75 to 4.66?2.71 ± 1.27?, and linear regression analysis showed significant correlation between SUVmax and the tumor size?r = 0.769, P = 0.001?, The SUVmax of the typical pulmonary sclerosing pneumocytoma ranged from range from 1.43 to 13.8?5.62 ± 4.09?, however,there was no correlation between SUVmax and the tumor size?r = 0.438, P = 0.239?. PSP group with symptoms showed a higher mean uptake of FDG than the asymptomatic group?SUVmax was 5.68 ± 3.63 versus 2.76 ± 1.18 respectively? and independent samples t-test showed statistically significant difference between the two groups?P = 0.002?. Seven patients took both PET/CT and enhanced CT examination, the SUVmax ranged from 0.97 to 8.19, and the net increased CT value ?CT range from 25 to 101 HU,6 cases?85.7%? showed moderate to significant enhancment.Conclusion:?1?Unenhanced CT findings such as halo sign, calcification, air crescent sign and lobulation are helpful in diagnosis pulmonary sclerosing pneumocytoma, but are of limited value. Characteristic enhancement degree, heterogeneous enhancement, punctate or focal low density and overlying vessel sign after enhancement have a high diagnostic value in pulmonary sclerosing pneumocytoma.?2?¹⁸F-FDG PET metabolic characteristics were differ beween typical and atypical pulmonary sclerosing pneumocytoma, typical pulmonary sclerosing pneumocytoma showed mild to moderate metabolism and metabolic level were correlated with the size of the lesion. Imaging and metabolic characteristics of atypical pulmonary sclerosing pneumocytoma are varied, and no correlation can found between SUVmax and the size of the tumor. Diagnostic value of ¹⁸F-FDG PET combined with enhanced CT was relatively better than ¹⁸F-FDG PET and ¹⁸F-FDG PET/CT in solid pulmonary sclerosing pneumocytoma.