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Objective To investigate the feasibility to reduce radiation doses on pediatric mutidetector abdominal CT using the adaptive statistical iterative reconstruction technique (ASIR) associated with automated tube current modulation technique(ATCM).Methods Thirty patients underwent abdominal CT with ATCM and the follow-up scan with ATCM cooperated with 40％ ASIR.ATCM was used with agedependent noise index (NI) settings: NI =9 for 0-5 year old and NI =11 for ＞ 5 years old for simple ATCM group,NI =11 for 0-5 year old and NI =15 for ＞5 years old for ATCM cooperated with 40％ ASIR group(AISR group).Two radiologists independently evaluated images for diagnostic quality and image noise with subjectively image quality score and image noise score using a 5-point scale.Interobserver agreement was assessed by Kappa test.The volume CT dose indexes (CTDIvol) for the two groups were recorded.Statistical significance for the CTDIvol value was analyzed by pair-sample t test.Results The average CTDIvol for the ASIR group was (1.38 ± 0.64) mGy,about 60％ lower than (3.56 ± 1.23) mGy for the simple ATCM group,and the CTDIvol of two groups had statistically significant differences.(t =33.483,P ＜ 0.05).The subjective image quality scores for the simple ATCM group were 4.43 ± 0.57 and 4.37 ±0.61,Kappa =0.878,P ＜ 0.01 (ASIR group: 4.70 ± 0.47 and 4.60 ± 0.50,Kappa =0.783,P ＜ 0.01),by two observers.The image noise score for the simple ATCM group were 4.03 ±0.56 and 3.83 ±0.53,Kappa =0.572,P ＜ 0.01 (ASIR group: 4.20 ± 0.48 and 4.10 ± 0.48,Kappa =0.748,P ＜ 0.01),by two observers.All images had acceptable diagnostic image quality.Conclusion Lower radiation dose can be achieved by elevating NI with ASIR in pediatric CT abdominal studies,while maintaining diagnostically acceptable images.
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Objective To investigate the CT features of inflammatory myofibroblastic tumor in children. Methods Eighteen patients with inflammatory myofibroblastic tumor proven by surgery and pathology were examined with plain and contrast medium enhancement CT scan. Results Of 18 cases,16 had isolated lesions located at lung (n =4), mesentery (n =3), kidney (n =2) and trachea (n = 1 ),left main bronchus ( n = 1 ), right thoracic cavity ( n = 1 ), peritoneum cavity ( n = 1 ), pancreas ( n = 1 ),left thigh ( n = 1 ), prostate ( n = 1 ), superclvicle soft t tissue ( n = 1 ) , bladder ( n = 1 ). The other 2 cases were with multiple lesions on omentum and mesentery, and in intraperitoneal and side of split of right hepatic lobe, respectively. The CT findings of 18 cases included 16 solid mass with calcifications in 3 of them, and 2 solid-cystic mass. After contrast enhancement, moderate or marked homogeneous or heterogeneous enhancement were shown in all the solid parts of tumor on dynamic CT. Mass can compress surround great vessel and tube-like structure. On pathological examination, the tumor was mainly composed of spindleshaped fibrous cells and inflammatory cells, and the immunohistochemically staining for SMA was observed positively. Conclusion CT can provide specific information for diagnosis of inflammatory myofibroblastic tumor, yet definite diagnosis relies on pathology.