title: Incidental extracerebral findings on brain nonenhanced magnetic resonance imaging: frequency, nondetection rate, and clinical importance.
abstract: OBJECTIVE
  This study aims to elucidate the frequency, nondetection rate, and clinical importance of incidental extracerebral findings (IECFs) on brain nonenhanced magnetic resonance imaging (MRI).
  
  
  METHODS
  A total of 8284 brain MRIs performed between January 1, 2015 and December 31, 2015 were evaluated for the presence of IECFs and the distribution of IECFs was analyzed. IECFs were categorized as E1 (clinically unimportant, e.g., sinus mucosal thickening); E2 (likely unimportant, e.g., pharyngeal mucosal symmetrical thickening); and E3 (potentially important, e.g., pharyngeal mucosal asymmetrical thickening). The nondetection rate was determined by comparing the results of the structured approach with the initial MRI reports. The medical records were examined for patients with E3 IECFs to assess clinical importance and outcome of these lesions.
  
  
  RESULTS
  A total of 5992 IECFs were found in 4469 of the 8284 patients (54.0%). E1 findings constituted 82.2% (4924/5992) of all IECFs; E2 constituted 16.6% (995/5992) and E3 constituted 1.2% (73/5992). Overall IECFs and E1 findings were significantly more common in male patients (P < 0.05). Statistically significant difference was also seen between the different age groups (P < 0.001). The nondetection rate was 56.9% (3409/5992) for overall IECFs and 32.9% (24/73) for E3 IECFs. Of the 73 patients with E3 IECFs, 34 (46.6%) received final diagnosis and appropriate treatment during the study period.
  
  
  CONCLUSIONS
  IECFs are prevalent in clinical patients on brain MR images with a nondetection rate of 32.9% for potentially important (E3) findings. The reporting of IECFs according to clinical importance is helpful for patients' management.
authors.affiliation: Department of Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 600 Yi Shan Road, Shanghai, 200233, China.
authors.forename: Ming-Liang
authors.initials: ML
authors.lastname: Wang
authors.affiliation: Department of Radiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China.
authors.forename: Li-Yan
authors.initials: LY
authors.lastname: Lu
authors.affiliation: Department of Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 600 Yi Shan Road, Shanghai, 200233, China.
authors.forename: Xiao-Er
authors.initials: XE
authors.lastname: Wei
authors.affiliation: Department of Radiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai Jiao Tong University School of Medicine, No. 600 Yi Shan Road, Shanghai, 200233, China. sjtuliwenbin@163.com.|Imaging Center, Kashgar Prefecture Second People's Hospital, Kashgar, China. sjtuliwenbin@163.com.
authors.forename: Wen-Bin
authors.initials: WB
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001927:Brain Diseases / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D033162:Incidental Findings; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged
keywords: Brain; Incidental findings; Magnetic resonance imaging; Patient care management; Prevalence