Diagnostic Value Of MRI Apparent Diffusion Coefficient In Pineal Region Germinomas

Objective:Intracranial germinoma is a kind of malignant tumor that usually occured in children and adolescents.The pineal region is the hightest probability site with this kind of tumor appeared,and the clinical manifestations of it mainly focus on headache,nausea,vomiting,drowsiness and other symptoms induced by high intracranial pressure.The deficient diagnosis characters of intracranial germinoma affects the selection of treatment and prognosis.Intracranial germinoma is extremely sensitive to radiotherapy and can be cured clinically only by radiotherapy with correct prognosis.Therefore,it is important to make a clear diagnosis before treatment and make the best treatment plan as soon as possible.Magnetic resonance imaging（MRI）is the main method on diagnosing intracranial germinoma,but it lacks specific imaging manifestations leading to low diagnostic efficiency on disease.Diffusion weighted imaging（DWI）as a kind of functional magnetic resonance imaging,can response the tissue structure and cell inside and outside the information such as the transfer of water molecules and the movement across the membrane.DWI make the research in the characteristics of the focal organization structure by the use of MRI technology increased to the micro level,and provides the diagnosis and differential diagnosis of tumors important informations.DWI combined with apparent diffusion coefficient（ADC）are a hotspot in the study on diagnosing intracranial tumor in recent years,but the study focusing on intracranial germinoma is rarely publised.This paper through analyzing the trait of T1WI,T2WI,FLAIR,enhanced T1WI and DWI signal and ADC value in pineal germinomas and other tumors to explore the application value of DWI combined with ADC value in the diagnosis and differential diagnosis of pineal region germinomas and other tumors.Methods:From January 1st,2010 to December 31th,2016,16 case with pineal region tumors confirmed by pathology or radiosensitivity test were selected,consisted of 10 case germinomas,2 case astrocytomas,2 case pineocytomas and 2 case teratomas.All the patients experienced MR scanc with DWI sequence.Parameters in all MR sequence and the ADC value on tumors and on control area around tumor were collected.Results:There was no significant different in T1WI,T2WI,FLAIR and enhanced T1WI values between pineal region tumors（P values were 0.78,0.86,0.74 and 0.35）,while the mean value of ADC was statistically significant（P<0.05）.The ADC mean values of pineal region germinomas,astrocytomas,pineocytomas and teratomas were（824.41±205.90）×10^-6mm/s,（969.54±244.50）×10^-66 mm/s,（1209.31±43.45）×10^-66 mm/s,（1949.40±161.39）×10^-66 mm/s.Significant statistical difference was observed in pineal region tumors（P<0.05）.Significant statistical difference on the ADC value was observed between pineal region germinomas and teratomas（P<0.05）.Conclusion:（1）The measurement of ADC value is useful in diagnosing pineal region germ cell tumor.（2）DWI combined with ADC value measurement can effectively distinguish the pineal teratoma from the pineal germinoma.