Central bronchiectasis in allergic bronchopulmonary aspergillosis: comparative evaluation of computed tomography of the thorax with bronchography

Abstract

Demonstration of central bronchiectasis (CB) with normal peripheral bronchi is an essential requirement for the diagnosis of allergic bronchopulmonary aspergillosis (ABPA). Although the results of bronchography remain the gold standard for demonstration of central bronchiectasis they are not always diagnostic. Moreover, it is an unpleasant invasive procedure which may be difficult to perform in a patient of allergic bronchopulmonary aspergillosis with acute severe asthma. In an attempt to find a safe and effective alternative to demonstrate central bronchiectasis computed tomography (CT) of the thorax was evaluated against bronchography. Twenty one patients with allergic bronchopulmonary aspergillosis underwent computed tomography of the thorax followed by bronchography. Of the 378 bronchopulmonary segments available for analysis, 42 had to be excluded because of consolidation or non-filling of the contrast dye, leaving 336 segments for evaluation. CB was identified on CT in all 21 patients. Detailed analysis of the visualized segments revealed that computed tomography (using 8 mm contiguous scans) identified 146 of the 212 segments showing central bronchiectasis on bronchography (sensitivity 70%) and 114 of the 124, read as normal on bronchography (specificity 92%). Supplemental 4 mm scans, used in 8 out of 21 patients improved the overall sensitivity of computed tomography to 83%, whilst the specificity remained unchanged at 92%. Thus, computed tomography of the thorax, being more acceptable to the patient, has the potential of being the investigation of choice for the demonstration of central bronchiectasis in patients with allergic bronchopulmonary aspergillosis.

Chest radiographic and computed tomographic manifestations in allergic bronchopulmonary aspergillosis

“…Hansell et al [33] were the first to describe CB arbitrarily as dilated bronchi within a point midway radially from the hilum to the chest wall. Subsequently, authors have used different definitions including subjective criteria based on proximity to the hilum [13] , and dilated bronchi within the medial two-thirds of the point radially from the hilum to the chest wall [14,16,17] . Although believed to be a characteristic finding in ABPA, the significance of CB as a specific diagnostic marker for ABPA is debatable as it has been shown that almost 40% of the involved lobes have bronchiectasis extending to the periphery [19,21,22] .…”

“…To compare the HRCT chest findings of our study with those described in the literature, we have also performed a systematic review of PubMed and EmBase using free text search terms: allergic bronchopulmonary aspergillosis, ABPA. Our search yielded 3133 references of which 10 studies have reported HRCT chest findings of ABPA (Table 4) [ [13][14][15][16][17][18][19][20][21][22] . The studies have used different protocols for performance of CT, and most studies have used the definition of CB as dilated bronchi present within the medial two-thirds of the lung fields.…”

“…Currie et al [13] (1987 Neeld et al [14] (1990 Shah et al [15] (1992) Angus et al [16] (1994) Panchal et al [17] (1994) [18] (1994) Panchal et al [19] (1997) [20] (1999) 44 1 [21] (2000) of bronchiectasis extending to the periphery has also been variably described [13,14,16,18,19,22] . Most studies were retrospective and included patients who had already received glucocorticoids for treatment of ABPA [13,14,16,[19][20][21] .…”

“…The findings on HRCT chest scan include CB, mucus plugging with bronchocele formation, centrilobular nodules and others [12] . Few studies have reported HRCT chest findings in patients with ABPA [13][14][15][16][17][18][19][20][21][22] . Most of these studies have focused their attention on detection of CB rather than describing the CT findings.…”

Allergic Bronchopulmonary Aspergillosis Presenting as Lobar or Total Lung Collapse

“…Computed tomography has a sensitivity of 83% and a specificity of 92% in detecting central bronchiectasis in patients with ABPA [23]. Computed tomography appearances can be sub-divided into bronchial, parenchymal and pleural abnormalities.…”