Clinical Study On The Application Value Of Magnetic Resonance Imaging Scan Before Prophylactic Cranial Irradiation In Limited-stage Small Cell Lung Cancer

Objective: Prophylactic cranial irradiation(PCI)can reduce the incidence of brain metastasis in limited-stage small cell lung cancer(LS-SCLC)and improve overall survival.A considerable number of patients had brain metastasis(BM)at the time of PCI,even though no metastasis was found in the enhanced head scan at the initial treatment and no central nervous system symptoms were observed before PCI.The purpose of this study was to evaluate the diagnostic value of enhanced magnetic resonance imaging scan for brain metastasis before the upcoming PCI of LS-SCLC.Methods:A retrospective analysis was performed on LS-SCLC patients treated in the First hospital of Bethune,Jilin University from January 2013 to July 2018,who were included in the study with the following characteristics: 1)4-6 cycles of platinum-containing chemotherapy combined with chest radiotherapy,achieved CR or PR after radiotherapy and chemotherapy,and PCI was planned within 3 months after the end of the systematic treatment;2)no brain metastasis was found by using head enhanced MRI at the initial diagnosis,and head enhanced MRI was performed again before PCI.Results: A total of 236 patients with LS-SCLC(142 males,60.2%)were included in this study,with an average age of 55.8years old.37 patients(15.7%)with brain metastasis were found in head enhanced MRI before PCI,including 28 patients with no symptoms,accounting for 75.7% of the number of patients with brain metastasis.The brain metastases in 37.8% of the patients were not visible under CT scan.There were 26 patients with 1-2 brain metastases and 11 patients with brain metastases?3,with an average size of 10.7mm and 63.6% of the lesions were less than or equal to 10 mm.The median time interval from the diagnosis of SCLC(calculated according to the time of the first chemotherapy)to BM was 6.7 months(201d,range: 148-251d),during which an average of 2.3 MRI examinations were performed.Conclusion: In LS-SCLC,the occurrence of brain metastasis should be highly vigilant before PCI,even in patients without central nervous system symptoms.In this part of the population,brain metastases tend to be small,and CT examination is not easy to find,and it is strongly recommended to use enhanced MRI for examination.