Objective:This study compares the magnetic resonance imaging (MRI) appearance of two types of breast tissue markers to investigate the appropriate clinical application of the markers.Methods:Breast MRI of 69 patients (78 masses) with breast tissue markers had been placed were analyzed retrospectively from November 2015 to August 2018 in our hospital. The sizes and shapes of breast tissue markers were assessed in axial fat-suppressed T2-weighted images, T1-weighted images and contrast-enhanced T1-weighed images.Results:The length of the coil nickel-free stainless steel markers were greater than ribbon titanium markers, with statistical difference in fat-suppressed T2-weighted images ( P=0.039). In contrast-enhanced T1-weighted images, all coil nickel-free stainless steel markers showed >6 mm diameter and round shape, and ribbon titanium markers showed >6 mm diameter ( n=20) or ≤6 mm diameter ( n=8), and round ( n=20), dot ( n=7) or band ( n=1) shapes. The categories of sizes and shapes in two types of breast tissue markers both had statistical significance ( P<0.001, P<0.001). Conclusions:Small breast lesions with breast tissue markers are not suitable for MRI evaluation. The artifact of ribbon titanium markers is smaller than coil nickel-free stainless steel markers, so they have less impact for lesions. The choice of the breast tissue markers and image evaluation methods should depend on the different clinical conditions.

Objective To study the predictive value of magnetic resonance imaging (MRI),positron emission computed tomography (PET)and PET/MRI coregistration in intractable epilepsy of children.Methods A retrospec-tively analysis was performed based on the surgery data at the Department of Children Epilepsy Center of Peking Univer-sity First Hospital from September 2015 to March 2016.The clinical data,surgery and follow－up study data,interictal and ictal electroencephalogram,MRI,PET and PET/MRI coregistration data were collected.By comparison with the epi-leptogenic zone designed by pre－surgical workup,the accuracy of MRI,PET and PET/MRI coregistration in detecting lesion was assessed.In the patients who had no seizure during≥1 year follow－up,their sensitivity,specificity,positive predictive value,negative predictive value of MRI,PET and PET/MRI coregistration were calculated.Results (1)A total of 62 patients underwent surgery,30 boys and 32 girls. The average age on epilepsy onset was 2. 50 years (2 days－11.70 years),and average age on surgery was 5.10 years old(0.75－15.60 years old).(2)Surgical treat-ment of 62 cases included the resection of the focal or lobar (32 cases,51.6%),and the multilobar (16 cases, 25. 8%).Hemispherotomy was done in 14 cases (22.6%).During ≥1 year follow－up,seizure outcome was Engel class Ⅰ in 57 cases (91.9%)out of the 62 patients,Engel classⅡto Engel classⅣin 1 case,3 cases,and 1 case, respectively.(3)Referred to epileptogenic zone designed by presurgical workup,MRI represented 64.5%(40/62 ca-ses)results with accordance,PET and PET/MRI coregistration was 72.5%(45/62 cases)and 85.5%(53/62 cases), respectively,and the difference was significant(χ2＝7.25,P＝0.03).(4)Based on the patients of Engel class Ⅰ, their sensitivity and specificity were 66.7%,60.0% in MRI,75.4%,60.0% in PET %,and 85.9%,80.0% in PET/MRI coregistration,respectively.(5)There were 11 ＂non－lesion＂ cases of all focal cortical dysplasia in patholo-gy,and subtle structural abnormalities were de tected in 9 cases by reviewing MRI.Conclusions PET/MRI coregistra-tion can improve lesion detection of intractable epilepsy in children.