Background Ground-glass opacification (GGO) is a common but non-specific radiological pattern on multislice spiral computed tomography (MSCT) scans which can refer to the interstitial or vascular involvement. Due to polymorphism of pulmonary pathology in patients with systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) GGO requires a multi-stage differential diagnosis the result of which will significantly affect the treatment regimen - a choice between antibiotic or cytostatic and high-dose hormonal therapy.
Objectives The aim of this study was to optimize the ability of MSCT for differentiating between interstitial and vascular involvement and detecting pulmonary thrombosis using newly developed post-processing techniques.
Methods 120 patients, aged 39.5 ± 13.7, with moderate-severe lupus activity were administrated a complex of laboratory, pulmonary function and imaging tests. It is the first time when post-processing techniques (PPTs) such as MPR (Multiplanar reformations), MIP (Maximum intensity projection), mIP (Minimum intensity projection) and especially color mapping were used for evaluation of vascular involvement on native MSCT scans of patients with SLE and APS. The criteria of pulmonary vasculitis on color maps were described as enhanced peripheral vascularization (vessel caliber enlargement and increase in vessel tortuosity) and perivascular edema. The criteria of pulmonary thrombosis - areas of micro-infarctions in the peripheral regions of lungs. CT angiography and pulmonary perfusion scintigraphy were chosen as methods of gold standard. Reconstructed scans were compared with native CT scans, CT angiograms and perfusion scans done by three diagnosticians.
Results Statistics showed that the mean area under the receiver operating characteristic curve value increased significantly from 0.713 without the PPTs to 0.925 with the PPTs (P<0.05) in differentiating between vasculitis and pneumonic infiltration and increased significantly from 0.527 without the PPTs to 0.724 with the PPTs (P<0.05) in detecting thrombosis. Compared with CT angiogram and perfusion scans no differences in the involved regions were detected. Variants that were associated with enhanced peripheral vascularization on color maps in a significant manner were: rate of diffusion capacity (p=0.006), hypocomplementemia (p=0.01), hypoxemia (p=0.003), pulmonary hypertension (p=0.01). The presence of lupus anticoagulant in patients with SLE was associated with the development of pulmonary thromboembolism (p=0.001) and pulmonary vasculitis complicated with thrombosis in situ (p=0.04).
Conclusions PPTs are a useful addition to native MSCT scans in detecting early signs of pulmonary vasculitis, differentiating between vasculitis and pneumonic infiltration and evaluation of treatment-related changes. It equips radiologists to more easily detect areas with thrombosis especially thrombosis in situ due to pulmonary vasculitis.
Disclosure of Interest None declared
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