Seung-Hee Choi MD, Presenter: Nothing to Disclose

Eun-Young Kang MD, Abstract Co-Author: Nothing to Disclose

Jang Su Kim, Abstract Co-Author: Nothing to Disclose

Yoon Kyung Kim MD, Abstract Co-Author: Nothing to Disclose

Ok Hee Woo MD, Abstract Co-Author: Nothing to Disclose

Hwan Seok Yong MD, Abstract Co-Author: Nothing to Disclose

Yu-Whan Oh MD, Abstract Co-Author: Nothing to Disclose

To assess the frequency of radiologic abnormalities and investigate radiologic findings in patients with laboratory-confirmed pandemic H1N1 2009 influenza virus infection

Total 9381 patients checked for pandemic H1N1 2009 influenza virus RT-PCR tests in November 2009, when the virus outbreak peaked in Seoul, Korea. 3829 out of 9381 showed positive test results. Among 3829 patients, 2410 were below age 15 and 1439 were over age 15. Of 3829 patients, 342 underwent chest radiographs (214 children and 128 adults) from 1 week before to 1 week after the day they had virologic tests. At the same period, 2 children and 11 adults received chest CT for further evaluation. Two radiologists reviewed all the images of 342 patients and evaluated for the radiologic pattern, distribution of lesion, and associated findings of their initial chest radiographs and CT scans.

Among 342 who took chest radiographs, 291 (85%) were normal and only 51 (15%) showed abnormal findings. 41 of 214 children (19%) and 10 of 128 adults (8%) showed abnormal chest radiographs. Most common findings were unilaterality (35/41, 85%), air space opacity (34/41, 83%), and one lobe involvement(30/41,73%) in children. In adults, unilaterally(7/10, 70%) and randomly (6/10, 60%) distributed air space opacity (8/10, 80%) involving more than 2 lobes (6/10, 60%) was prominent. 12 out of 13 CT were abnormal. Bilaterally and randomly distributed ground-glass opacity (GGO) and centrilobular nodules involving 2 or more lobes were common features of CT in adults. One child showed consolidation with atelectasis, effusion and lymphadenopathy involving central RLL and the other showed GGO, consolidation, centrilobular nodules in right lung.

Among infected patients, only 9% (342/3829) took chest radiographs, which means patients critically ill enough to undergo further radiologic evaluation were very few. And most patients who received chest radiographs showed normal. Children showed abnormal chest radiographs more frequently than adults. Unilateral airspace pneumonia was most common in patients with pandemic H1N1 2009 influenza viral infection.

Patients critically ill enough to undergo further radiologic evaluation were few. Only small number of patients showed abnormal findings and unilateral airspace pneumonia was most common.

Choi, S, Kang, E, Kim, J, Kim, Y, Woo, O, Yong, H, Oh, Y, Radiologic Review of an Outbreak of Pandemic H1N1 2009 Influenza Virus Infection at a University Hospital in Seoul, Korea.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9013411.html