Size-matching in lung transplantation by computed tomography for end-stage interstitial disease: a retrospective analysis

Abstract

Background: Size matching between donors and recipients is a major issue in lung transplantation (LTx), especially in patients with restrictive lung disease (RLD). This study aims to evaluate computed tomography (CT) as an additional method for defining the total lung capacity (TLC) in patients with end-stage interstitial disease awaiting LTx.

Methods: Clinical data and CT scans from patients who underwent a first LTx from January 2014 to July 2018 in Bichat Hospital, Paris, were prospectively included in a database. CT TLC (ctTLC) was retrospectively calculated after semi-automatic contouring of the parenchyma and compared with measured TLC (mTLC) and predicted TLC (pTLC) values.

Results: The study group included 89 patients (male:female =68:21; mean age, 59.5±10.0 years). The time between pulmonary function tests (PFTs) and CT scan was 162±270 days [median, 67 days; interquartile range (IQR), 0-233 days]. ctTLC was inferior to mTLC and pTLC (respectively 2,979±1,001 mL, 3,530±1,077 and 6,381±955 mL, P<0.001). The relative difference between CT lung volume (ctLV) and measured lung volume (mLV) was higher on the left than on the right side (25.4% vs. 16.3%, respectively, P=0.11). After exclusion of two outliers, we found a significant correlation between ctTLC and mTLC (r=0.762, P<0.001).

Conclusions: CT volume is a feasible method to assess TLC in patients with end-stage interstitial disease awaiting LTx. This study highlights potential size-mismatch for graft selection before LTx and opens the perspective of a prospective trial evaluating impact of size-matching by donor-recipient (D-R) ctTLC ratio on postoperative outcomes.

Keywords: Lung transplantation (LTx); computed tomography scan (CT scan); interstitial lung disease (ILD); total lung capacity (TLC).

Figure 1

Frequency distribution of CT volume of the right lung and left lung. *, P<0.001. CT, computed tomography.

Figure 2

Frequency distribution of pTLC, mTLC, and ctTLC. *, P<0.001. pTLC, predicted total lung capacity; mTLC, measured total lung capacity; ctTLC, computed tomography total lung capacity.

Figure 3

Three-modality assessment of right and left lung volume. *, P<0.001. pRLV, predicted right lung volume; mRLV, measured right lung volume; ctRLV, computed tomography right lung volume; pLLV, predicted left lung volume; mLLV, measured left lung volume; ctLLV, computed tomography left lung volume.

Figure 4

Linear regression of ctTLC according to mTLC for both lungs together and separately. (A) All patients, n=89. ctTLC vs. mTLC: Pearson r=0.466 with P<0.001; ctRLV vs. mRLV: Pearson r=0.483 with P<0.001; ctLLV vs. mLLV: Pearson r=0.499 with P<0.001. (B) After exclusion of two outliers on CT measurements (one pneumothorax, one emphysema of upper lobes), n=87. ctTLC vs. mTLC: Pearson r=0.762 with P<0.001; ctRLV vs. mRLV: Pearson r=0.4189 with P<0.001; ctLLV vs. mLLV: Pearson r=0.503 with P<0.001. ctTLC, computed tomography total lung capacity; mTLC, measured total lung capacity; ctRLV, computed tomography right lung volume; mRLV, measured right lung volume; ctLLV, computed tomography left lung volume; mLLV, measured left lung volume.