1010 AJR:212, May 2019 of the upper lobes and apical pleural thick- ening [7–10]. The NB form is defned to be present when bilateral bronchiectasis and cel- lular bronchiolitis are present mainly in the right middle lobe and lingular division of the left upper lobe, irrespective of the presence of cavities in both lungs. However, in this form, neither upper lobar volume loss nor emphy- sematous changes in the remaining lungs is present [7–10]. In the last several decades, MAC PD has changed in appearance from the fbrocavitary form to the NB form [11– 13]. Therefore, the disease presents more fre- quently with bilateral bronchiectasis and cel- lular bronchiolitis mainly in the right middle lobe and lingular division of the left upper lobe than cavitary lesions in the upper lobes. Approximately one-third of patients with CT fndings of bilateral bronchiectasis and cellular bronchiolitis are reported to have NTM pulmonary diseases. In particular, when bronchiectasis and cellular bronchiol- Unilateral Lung Involvement of Nodular Bronchiectatic Mycobacterium Avium Complex Pulmonary Diseases: Proportion and Evolution on Serial CT Studies Yeonu Choi 1 Kyung Soo Lee 1 Seon Kyoung Kim 1 Won Jung Koh 2 Choi Y, Lee KS, Kim SK, Koh WJ 1 Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Irwon-dong, 50, Gangnam-gu, Seoul 06351, Korea. Address correspondence to K. S. Lee (kyungs.lee@samsung.com). 2 Department of Medicine, Division of Respiratory and Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. Cardiopulmonary Imaging • Original Research AJR 2019; 212:1010–1017 0361–803X/19/2125–1010 © American Roentgen Ray Society T he prevalence of nontuberculous mycobacterial (NTM) pulmo- nary disease has been reported to be increasing, particularly in the United States and Canada. Mycobacteri- um avium complex (MAC) organisms ac- count for the majority of NTM species iso- lated from the NTM disease [1, 2]. MAC organisms consist mostly of two mycobacte- rial species: M. avium and M. intracellulare [3, 4]. With the advancement of molecular bi- ology, those two species are now better dif- ferentiated from each other than before [5, 6]. In consideration of imaging fndings, the MAC pulmonary disease (PD) is classifed into two forms; the so-called fbrocavitary form and nodular bronchiectatic (NB) form. The fbrocavitary form is defned to be pres- ent when a cavity (or cavities) is present in the upper lobes with fndings of emphysema- tous changes in the upper and middle lung zones and with or without a volume decrease Keywords: CT, lung infection, Mycobacterium avium, Mycobacterium avium complex, Mycobacterium intracellulare, nontuberculous mycobacteria, serial study, unilateral doi.org/10.2214/AJR.18.20589 Received August 25, 2018; accepted after revision November 16, 2018. OBJECTIVE. We aimed to explore proportion, involved organisms, and serial CT fea- tures of nodular bronchiectatic (NB) Mycobacterium avium complex (MAC) pulmonary dis- eases that manifested as unilateral lung disease. MATERIALS AND METHODS. We retrospectively identifed 674 patients with NB MAC pulmonary disease (PD) who underwent serial CT studies from January 2005 through December 2012. We selected patients with unilateral lung involvement as its initial manifes- tation. Retrospective analyses on serial CT fndings in terms of presence and extent of lung abnormalities were performed. The organism identifed (M. avium vs M. intracellulare ) and treatment status were reviewed. To fnd the factors related to progression to involve both lungs, Cox regression analysis was performed. RESULTS. Unilateral MAC PD on initial CT was found in 47 patients (7%). Among them, 10 (21%) showed disease progression on follow-up CT to involve both lungs (mean evolv- ing time, 1536 days). All 10 of these cases initially involved the right lung. Of these 10 pa- tients, eight needed antibiotic treatment because of deteriorating imaging fndings (4/8, 50%) or worsening symptoms (4/8, 50%). Initial total CT score (hazard ratio [HR], 1.414; 95% CI, 1.092–1.831; p < 0.01) and age (HR, 1.076; 95% CI, 1.004–1.154; p < 0.05) were related fac- tors for disease progression in simple Cox regression test. CONCLUSION. Unilateral lung involvement of NB MAC PD is an occasional (7%) manifestation, and disease progressed in approximately 20% of patients in our study to in- volve both lungs. The imaging factor most related to disease progression appears to disease extent on initial CT. Choi et al. CT of Mycobacterium Avium Complex Pulmonary Diseases Cardiopulmonary Imaging Original Research Downloaded from www.ajronline.org by 3.239.56.152 on 08/14/21 from IP address 3.239.56.152. Copyright ARRS. For personal use only; all rights reserved