Performance of long-term CT monitoring in diagnosing bronchiolitis obliterans after lung transplantation

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Abstract

Aim

The purpose of the study was to evaluate the ability of CT, including expiratory scans with minimum intensity projection in predicting the development of bronchiolitis obliterans syndrome after lung transplantation.

Materials and methods

Forty consecutive patients, 29 bilateral and 11 single lung transplanted, were followed-up with regular scans for a median of 36 months. Air trapping was evaluated on expiratory scans constructed from two short spiral scans with minimum intensity projection-technique, one at the level of the carina and the other midway between the right diaphragm and the carina. Air trapping was scored on a 16-point scale. Bronchiolitis obliterans syndrome was diagnosed according to established clinical criteria and quantified spirometrically.

Results

Bronchiolitis obliterans syndrome developed in 17 patients (43%) after a median of 12 months. Air trapping and bronchiectasis was seen before the diagnosis of bronchiolitis obliterans syndrome in only two and one patient, respectively. Interobserver agreement for air trapping score was good (kappa = 0.65). Air trapping scores performed significantly better than that achieved by chance alone in determining the presence of bronchiolitis obliterans syndrome (P = 0.0025). An air trapping score of 4 or more provided the best results with regard to sensitivity and specificity in diagnosing bronchiolitis obliterans syndrome. The sensitivity, specificity, positive and negative predictive values of an air trapping of 4 or more in the diagnosis of bronchiolitis obliterans syndrome were 77, 74, 68 and 81%, respectively.

Conclusion

Expiratory CT scans with minimum intensity projection-reconstruction did not predict the development of bronchiolitis obliterans syndrome in most patients. The findings seriously limit the clinical usefulness of long-term CT monitoring for diagnosing bronchiolitis obliterans syndrome after lung transplantation.

Section snippets

Patients

Of all adult patients transplanted between December 1996 and March 2001 in our hospital, 40 (21 women and 19 men) had survived for 11 months or more (Table 1). They were all included in the present study. The median age of the patients at transplantation was 51 years (range 18–61 years). In the bilaterally transplanted (BLT) group (29 patients, 16 women and 13 men), the median age was 50 years (range 18–61 years), and in the single lung transplanted (SLT) group (11 patients, 5 women and 6 men)

Results

Patients were followed-up for a median of 36 months (range 11–84 months). A total of 292 inspiratory, technically successful HRCT examinations were performed and examined. Expiratory scans with MinIP-reconstruction had been performed in 225 of these examinations. The number of expiratory scans with MinIP-reconstruction was lower than inspiratory HRCT scans because expiratory scans were not performed in any patient at the 1 month's and in 10 patients at the 3 months’ follow-up examination. At

Discussion

Early diagnosis of BOS in lung transplanted patients is important, because prompt initiation of therapy may help to preserve lung function [3]. However, in most of our patients, air trapping was detected concomitantly with or later than the development of BOS as diagnosed clinically with the aid of respiratory function tests. Therefore, CT according to our protocol had limited clinical value in the early diagnosis of BOS. Our findings were in agreement with previous studies, which documented

Acknowledgement

We thank Arnold Berstad for helpful assistance in reviewing the manuscript.

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