Quantification of chronic vascular remodeling in sickle cell disease.

backgroundSickle cell disease (SCD) causes pulmonary parenchymal and vascular complications with a major impact on mortality. Quantitative computed tomography (CT) assessment of pulmonary vascular "pruning" (rarefaction of small-caliber pulmonary vessels) may provide a non-invasive tool to better understand these complications.

objectivesTo evaluate vascular pruning in SCD and its association with clinical, functional respiratory, and imaging parameters. MATERIALS AND

methodsNon-contrast chest CT scans from 73 adult patients with SCD followed at Avicenne Hospital (Paris, France) were analyzed. Pulmonary vascular volumes were quantified using the blood volume in vessels with a cross-sectional area < 5 mm² (BV5) and the ratio of BV5 to total pulmonary blood volume (TBV), measured globally and in peripheral lung regions. These biomarkers were compared with pulmonary function tests (PFTs), CT parenchymal abnormalities, and clinical history of vascular disease.

resultsIn 73 patients (mean age 33 ± 14 years; 38 women), linear opacities (78%), reticulations (53.4%), and proximal vascular abnormalities (pulmonary trunk enlargement and segmental artery dilation: 28.8% and 19.2%, respectively) were significantly associated with reduced BV5 and BV5/TBV, indicating increased pruning. Similar associations were observed in patients with a hemoglobin-corrected diffusing capacity for carbon monoxide (DLCOc) < 80%, history of pulmonary embolism (PE), and pulmonary hypertension (PH). No significant relationship was found with acute vaso-occlusive episodes. Peripheral lung analysis showed trends consistent with global measurements, with some differences in statistical significance.

conclusionPulmonary vascular pruning is observed in SCD in association with parenchymal and vascular abnormalities and may serve as an early imaging biomarker of chronic vasculopathy. KEY POINTS: Question Can automated quantitative analysis of pulmonary vessels on non-contrast chest CT reveal vascular pruning and provide imaging biomarkers of pulmonary vasculopathy in sickle cell disease? Findings CT-derived vascular pruning markers (BV5 and BV5/TBV) were associated with reduced DLCOc, history of pulmonary hypertension or embolism, and parenchymal and vascular abnormalities in SCD. Clinical relevance Quantification of vascular pruning on routine non-contrast chest CT may provide a practical, non-invasive biomarker for detecting pulmonary vasculopathy and identifying sickle cell disease patients at risk for pulmonary hypertension.