Fleur Kilburn-Toppin MBBCHIR, MA, Presenter: Nothing to Disclose

Owen Arthurs MBBChir, PhD, Abstract Co-Author: Nothing to Disclose

Patricia Ai Khoon Set MBBS, Abstract Co-Author: Nothing to Disclose

Angela Doreen Tasker MBBChir, FRCR, Abstract Co-Author: Nothing to Disclose

Multi-detector CT (MDCT) is the preferred imaging modality for the detection of pulmonary nodules. Maximum intensity projection (MIP) images may be useful in helping differentiate nodules from adjacent vessels, whilst preserving contrast to underlying lung parenchyma. Previous studies in adults show MIP images improve accuracy and speed of nodule detection compared to conventional thin-slice axial CT. The aim of this study was to evaluate the benefits of MIP images over axial images for the pediatric chest, where small thoracic size and motion artifact may be problematic.  

11 children were selected from our database of thoracic CT images from oncology patients. All had thoracic MDCT examination on a Siemens 64 multi-slice CT scanner. 2 individual readers (4 and 15 years experience) read each set of images, with 2-mm axial and 10-mm MIP images presented randomly over different reading sessions, to minimize familiarity and practice performance. Number of nodules, overall time taken, and severity of motion artifact was recorded.

11 children (mean age 11.5 years, SD 4.9, range 1.6 - 16.4 y) yielded 17 nodules in total (mean 1.5 nodules per patient; SD 1.2, range 0-4). Overall, more nodules were detected on MIP images (32 in total; mean 1.5 ± 1.1) than on axial images (29; mean 1.4 ± 1.3), although this did not reach statistical significance. MIP images took less time to read (95 ± 47 sec) than axial images (111.6 ± 49 sec), an average of 14.3% quicker. Motion artifact was recorded as severe in 3 studies, moderate in 7 and minimal in 3 studies.

This preliminary data from an ongoing study supports the idea that MIP images may give potential diagnostic benefits over axial images for the pediatric chest. This initial data suggests that MIP images yield both better and faster detection of thoracic nodules in children. Statistical significance has not been demonstrated as our sample size is too small. A larger sample size will be investigated to identify the true diagnostic advantage of MIP images.

When using MDCT to detect lung nodules in children, MIP images may be quicker to analyze and increase diagnostic yield.

Kilburn-Toppin, F, Arthurs, O, Set, P, Tasker, A, Detection of Pulmonary Nodules at Pediatric Thoracic CT: Are Maximum Intensity Projection (MIP) Images Better than Axial Images?.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11009689.html