Objective To illustrate the CT,MRI and PET-CT features of spinal osteoblastoma,and provide an important reference for the preoperative diagnosis and assessment.Methods The imaging and clinical data in 16 cases of spinal osteoblastoma confirmed by surgery and pathology were analyzed retrospectively.Results Age of onset in 11 cases ranged from 10 to 29 years old,5 cases from 30 to 51 years old.Tumors were originated from the spine appendage in 13 cases,and from the vertebral bodies in 3 cases.Tumors presented as expansive bone destruction in 6 cases,and as osteolytic bone destruction in 10 cases.13 cases were diagnosed as benign diseases and 3 cases as invasive ones.Calcification or ossification was seen in all cases,with sclerotic margin of variable thickness and peripheral patchy high density of bone sclerosis.The soft tissue mass was found in 15 cases and intraspinal involvement was showed in 13 cases.The tumors showed isointensity or hypointensity on T 1WI,isointensity or hyper-intensity on T2WI in 13 cases,and showed heterogenous enhancement after contrast administration in 13 cases.PET-CT depicted the nodular or lobulated distribution of radioactive tracer with high radioactive concentration,with increment in standardized uptake value in 5 cases.Conclusion The typical imaging signs of spinal osteoblastoma were expansile,osteolytic bone destruction of the spine appendage,accompanying the soft tissue mass,with a speckled or nodular pattern of calcification or ossification within the lesions.Inhomogeneous signal intensity and inhomogeneous enhancement on MRI and nodular or lobulated high radioactive concentration for the tumors on PET-CT are found.

Objective To investigate the CT and MRI features of supratentorial primitive neuroectodermal tumors (sPNET)in adults,and to analyze the reasons of misdiagnosis.Methods The CT and MRI features of 1 5 patients with sPNET confirmed by pathology were analyzed retrospective.13 of 15 patients were underwent plain and contrast enhanced MRI,4 patients were also performed CT scan and the other 2 patients were underwent CT plain scan only.Results Nine of 1 5 lesions were located in the temporal and/or frontal lobe,with clear margin in 12 lesions,and mild to moderate peritumoral was noted in most cases.The solid portion of the lesions were hyperdense on CT,isointense or slightly hypointense on T1WI,and isointense or hyperintense on T2WI compared to the gray matter.Calcification (2/6),necrosis or cystic degeneration(1 3/1 5),hemorrhage (8/1 5)and flow void signal (1 1/1 3)were seen.Twelve lesions showed significantly heterogeneous enhancement and 7 lesions showed irregular ring-enhancement.The solid parts in 5 lesions showed hyperintensity on diffusion-weighted imaging. Preoperatively,the lesions were misdiagnosed as glioma in 10 cases,ependymoma in 2 cases,meningioma in 1 case and germ cell tumor in 1 case, respectively;and 1 case was not diagnosed definitely.Conclusion Supratentorial PNET in adults has characteristic CT and MRI features,and the main reasons accounting for misdiagnosis are its extraordinary low incidence and that radiologists do no master its imaging features.

Objective To investigate the diagnostic value of six MRI characteristic features for diagnosing central neurocytoma (CN).Methods MRI data of 30 cases of CN and 68 cases of non-CN located in lateral ventricles were retrospectively analyzed.Six characteristic MRI features,including scalloping sign,broad-based attachment sign,soapbubble sign,peripheral cyst sign,fluid-fluid level sign and gemstone sign were scored based on a five-point scale.ROC curve was used to assess the diagnostic value of each MRI sign.Results The scalloping sign showed the highest area under the curve (AUC) value (0.82) among all 6 signs (all P＜0.05),followed by broad-based attachment,soap-bubble andperipheral cyst signs (AUC 0.73-0.75),higher than that of fluid-fluid level sign and gemstone sign (all P＜0.05).The scalloping sign exhibited the highest specificity (84.56 ％),followed by fluid-fluid level (77.94 ％),gemstone (74.26 ％) and peripheral cyst (70.34％) sign.The soap-bubble sign (83.89％) was the most sensitive sign,followed by broad-based attachment sign (76.11％) and peripheral cyst sign (75.00％).Conclusion The scalloping sign is the most valuable indicator for CN among six characteristic MRI features.