Boram Yi MD, Presenter: Nothing to Disclose

Joo Sung Sun MD, Abstract Co-Author: Nothing to Disclose

Young Gi Min MD, Abstract Co-Author: Nothing to Disclose

Kyung Joo Park MD, Abstract Co-Author: Nothing to Disclose

To evaluate the usefulness of ultra low dose chest CT (uLDCT) as initial imaging study for sharp fish-bone esophageal foreign body (EFB).

A total of 38 subjects who visited emergency room with an obvious history and symptoms of sharp fish-bone EFB were included in this study.uLDCT were acquired at 20mAs with ATCM and 100kVp or 120kVp on a 64 MDCT scanner (Based on BMI). All uLDCT data were reconstructed twice, once with FBP and once with iDose4 IR, then 2 sets of CT data were randomly arranged and reviewed by 3 readers who were blinded to the result. Readers independently reviewed 3-mm thickness transverse and coronal images. Readers also scored subjective image quality (4 point scale). One reader measured objective image noise (SD of circular ROI, 10 pixels in diameter at the following level: right common carotid artery of the thoracic inlet; pulmonary trunk; D-aorta of lug base). Positive findings were defined as identification of high-density foreign body, secondary findings (soft tissue swelling, pneumomediastinum). ROC analysis was used to evaluate diagnostic performance of uLDCT. Intraclass correlation coefficient (ICC) was measured for analysis of inter-observer consistency.

Thirty-three fish bone EFBs were identified and removed by 31 esophagogastroscopy, and 2 operations. Among 5 cases of true negative, false positive lesions were frequently recorded as the cervical EFB when reviewing CT data using FBP than CT data using iDose4 IR. uLDCT provided radiation dose reduction by average 0.82 mGy of CTDIvol and 32.7 mGy*cm of DLP (0.46mSv). Significant noise reduction (objective and subjective) of mediastinum was achieved using iDose4 IR technique (p<0.0001). Diagnostic performance of uLDCT for fish-bone EFB was good to excellent in all readers (AUC=0.879-0.985 using iDose4 IR and 0.827-0.976 using FBP). ICC for Inter-observer consistency was very excellent (iDose4 IR=0.97 and FBP=0.91).

Very low dose CT using iDose4 provided satisfactory diagnostic image quality for identifying fish-bone EFB with reduced radiation dose, therefore uLDCT would be adequate as first imaging modality for sharp fish-bone EFB. iDose4 IR would be useful to reduce image noise of mediastinum mimicking EFB.

Very low dose chest CT using iDose4 IR would be first imaging modality for initial evaluation of sharp fish bone esophageal foreign body before flexible endoscopic removal.

Yi, B, Sun, J, Min, Y, Park, K, Usefulness of Ultra Low-dose (sub mSv) Chest CT Using iDose4 Iterative Reconstruction for Initial Evaluation of Sharp Fish-bone Esophageal Foreign Body.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13019872.html