TY - JOUR
T1 - Pulmonary atelectasis
T2 - Signal patterns with MR imaging
AU - Herold, Christian J.
AU - Kuhlman, Janet E.
AU - Zerhouni, Elias A.
PY - 1991/3
Y1 - 1991/3
N2 - To assess the signal characteristics of different types of pulmonary atelectasis on magnetic resonance (MR) images, the authors studied obstructive atelectasis (OA) in 17 patients and nonobstructive atelectasis (NOA) in 25 patients. All patients underwent electrocardiographically gated MR imaging studies of the thorax with standard spin-echo sequences. No signal differences were observed between either type of atelectasis on T1-weighted images. Conversely, OA and NOA appeared significantly different on spin-density-weighted images (P < .001) and on T2-weighted studies (P < .0001). On T2-weighted images, all 17 cases of OA appeared hyperintense, whereas 22 of 25 cases of NOA demonstrated a very low signal intensity. Differences in the pathophysiology of OA and NOA presumably account for this observation. In OA, alveolar air is totally resorbed and secretions accumulate in the obstructed lung. The resulting increase in free fluid prolongs the T2 relaxation times and leads to high signal intensity on T2-weighted images. In NOA, the short T2 relaxation time of lung tissue in the absence of secretions and potential magnetic susceptibility effects due to residual air are likely to be responsible for the low T2 signal pattern.
AB - To assess the signal characteristics of different types of pulmonary atelectasis on magnetic resonance (MR) images, the authors studied obstructive atelectasis (OA) in 17 patients and nonobstructive atelectasis (NOA) in 25 patients. All patients underwent electrocardiographically gated MR imaging studies of the thorax with standard spin-echo sequences. No signal differences were observed between either type of atelectasis on T1-weighted images. Conversely, OA and NOA appeared significantly different on spin-density-weighted images (P < .001) and on T2-weighted studies (P < .0001). On T2-weighted images, all 17 cases of OA appeared hyperintense, whereas 22 of 25 cases of NOA demonstrated a very low signal intensity. Differences in the pathophysiology of OA and NOA presumably account for this observation. In OA, alveolar air is totally resorbed and secretions accumulate in the obstructed lung. The resulting increase in free fluid prolongs the T2 relaxation times and leads to high signal intensity on T2-weighted images. In NOA, the short T2 relaxation time of lung tissue in the absence of secretions and potential magnetic susceptibility effects due to residual air are likely to be responsible for the low T2 signal pattern.
KW - Lung, MR studies, 60.1214
KW - Lung, collapse, 60.74
UR - http://www.scopus.com/inward/record.url?scp=0026011324&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0026011324&partnerID=8YFLogxK
U2 - 10.1148/radiology.178.3.1994407
DO - 10.1148/radiology.178.3.1994407
M3 - Article
C2 - 1994407
AN - SCOPUS:0026011324
SN - 0033-8419
VL - 178
SP - 715
EP - 720
JO - RADIOLOGY
JF - RADIOLOGY
IS - 3
ER -