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Interlobular septal thickening in idiopathic bronchiectasis: a thin-section CT study of 94 patients.

PURPOSE
To retrospectively establish the prevalence of interlobular septal thickening at thin-section computed tomography (CT) in patients with bronchiectasis and to retrospectively examine the relationship between septal thickening and various CT features of bronchiectasis and functional parameters.


MATERIALS AND METHODS
Institutional review board approval or informed consent are not required for such a retrospective study. Thin-section CT scans of 94 patients (29 men, 65 women; age range, 18-82 years) with idiopathic bronchiectasis confirmed at thin-section CT and without any history or condition that causes bronchiectasis were assessed independently by two observers. The presence and signs of bronchiectasis, extent and distribution of septal thickening at global and lobar levels, and presence of emphysema were recorded. Univariate and multiple regression analyses were used to identify relationships between individual parameters of bronchiectasis, the extent of septal thickening, and functional indices.


RESULTS
Interlobular septal thickening was present in 56 (60%) of 94 patients with idiopathic bronchiectasis, excluding those with trivial septal thickening (34 of 94, 36%). At a lobar level, 69% (514 of 748) of lobes with bronchiectasis had septal thickening. There was strong correlation between the extent of septal thickening and the extent (r = 0.61, P < .001) and severity (r = 0.54, P < .001) of bronchiectasis. Stepwise regression analysis showed a relationship between the extent of septal thickening and the extent of bronchiectasis (P < .001). Septal thickening was not linked to functional indices of obstruction or restriction.


CONCLUSION
At thin-section CT, interlobular septal thickening is a frequent finding in patients with idiopathic bronchiectasis.