Carole A. Ridge MD, Presenter: Nothing to Disclose

Angela J. Frank MD, Abstract Co-Author: Nothing to Disclose

Diana Litmanovich MD, Abstract Co-Author: Nothing to Disclose

Maryam Shahrzard, Abstract Co-Author: Nothing to Disclose

Phillip M. Boiselle MD, Abstract Co-Author: Nothing to Disclose

Alexander A. Bankier MD, Abstract Co-Author: Author with royalties, Reed Elsevier Consultant, Olympus Corporation

Richard Schwartzstein MD, Abstract Co-Author: Consultant, Respironics, Inc

To analyze the utility of CT in assessing treatment response and clinical outcome in patients with chronic MAC infection.

For this IRB-approved study, our hospital information system was searched to identify a cohort of 19 patients treated for proven chronic MAC infection between 1999 and 2010. Twenty three asymptomatic untreated patients with proven MAC infection served as controls (5 men, 37 women, mean age=78.2 years). Two radiologists reviewed 2 consecutive thoracic CT of 19 symptomatic patients before and after antimicrobial therapy for the study cohort and 2 consecutive thoracic CT in the 23 controls. Scans were randomized and radiologists were blinded to knowledge of treatment. A CT scoring system assessed findings that may be associated with MAC infection. Readers assigned a score from 1-3 according to severity for each finding, to a maximum score of 21 (7x3) including: 1) severity and 2) extent of bronchiectasis, 3) bronchial wall thickening, 4) centrilobular nodules, 5) macronodules, 6) consolidation, 7) cavitary nodules. Statistical analysis utilized a t-test as the data was normally distributed. Numerical data were expressed as mean ± standard deviation. P < 0.05 was considered statistically significant.

Mean CT severity score decreased in the treated group (-0.29 ± 2.06) and increased in the control group (0.96 ± 1.98) (p=0.05). Percentage change for specific CT findings in the treated group were observed for bronchial wall thickening (11%), centrilobular nodules (17%), macronodules (-25%), consolidation (-10%), and cavitary nodules (-100%) between pre and post-treatment CT scans. Percentage change for specific CT findings in the control group were observed for bronchial wall thickening (84%), centrilobular nodules (14%), macronodules (10%), consolidation (-33%), and cavitary nodules (-85%) on surveillance CT (Figure 1).

CT detects differences between treated and untreated patients with MAC at a statistically significant level but similar trends were observed in both treated and control groups. Changes in CT findings should not be used in isolation in therapeutic decision making for chronic MAC infection.

Asymptomatic untreated patients with chronic MAC infection can exhibit thoracic CTchanges that mimic treatment effect. CT features alone should not prompt treatment in asymptomatic patients.

Ridge, C, Frank, A, Litmanovich, D, Shahrzard, M, Boiselle, P, Bankier, A, Schwartzstein, R, Assessing Treatment Response in Mycobacterium Avium Complex Infection: Clinical Utility of Chest CT.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12033184.html