The initial CT examinations were performed in the supine position using one of two CT scanners: SOMATOM Definition AS+ or SOMATOM Perspective (Siemens Healthineers, Forchheim, Germany). Non-contrast Chest CTs were performed with the acquisition from the thoracic inlet to the diaphragm. The following parameters were used: detector collimation widths of 64×0.6 mm or 128×0.6 mm; and a tube voltage of 120 kV. The tube current was regulated by an automatic exposure control system (CARE Dose 4D; Siemens Healthineers). Images of 62/114 (54%) patients were reconstructed with a slice thickness of 5mm and an interval of 5 mm. Images in 52/114 (46%) patients were reconstructed with a slice thickness of 1mm and an interval of 1mm. Images were reconstructed with a pulmonary B70F kernel and a mediastinal B30f kernel (SOMATOM Definition AS+), or pulmonary B80s kernel and a mediastinal B30s kernel (SOMATOM Perspective).
All 114 patients underwent follow-up CT examinations using the same scanners as the initial CT scans. Images of all patients were reconstructed with a slice thickness of 1mm and an interval of 1 mm. Prior to the prospectively planned 6-month follow up scan, 83 of 114 patients (73%) had CT scans at 3 months after symptom onset to monitor the evolution of their lung disease.
All CT images were reviewed in random order by three senior cardiothoracic radiologists (HSS, YQF, and JG, with 31, 13 and 10 years of experience in thoracic radiology, respectively) who were not aware of any clinical and laboratory findings or patient outcomes. The readers independently assessed the CT features using axial and multiplanar reconstructed images. The mediastinal window (center, 50; width, 350) and lung window(center, -600; width, 1200) were obtained from the picture archiving and communication system (Vue PACS, version 11.3.5.8902, Carestream Health, Canada). After independent evaluation, discussion and consensus resolved any disagreement. For each severe pneumonia patient, the predominant CT patterns according to the Fleischner Society glossary (19 (link)) were enumerated as follows: ground-glass opacities (GGO), consolidation, reticulation, emphysema, thickening of the adjacentpleura, pleural effusion, presence of nodules or masses, honey combing, bronchiectasis and interlobar pleural traction (retraction of the interlobar pleura toward the lesions). The CT evidence of fibrotic-like changes was defined as the presence of traction bronchiectasis, parenchymal bands(12 (link), 20 (link)), and/or honeycombing(19 (link))(Figure 2 ).
To quantify the extent of pulmonary abnormalities (total lesions, GGO, consolidation, reticulation and fibrotic-like changes), a semiquantitative CT score (21 (link)) was assigned on the basis of the area involved in each of the five lung lobes: 0, no involvement; 1, < 5% 2, 5%-25%;3, 26%-49%; 4, 50%-75%;and 5, >75%. The total CT severity score was calculated by summing the individual lobar scores (possible scores range from 0 to 25).
All 114 patients underwent follow-up CT examinations using the same scanners as the initial CT scans. Images of all patients were reconstructed with a slice thickness of 1mm and an interval of 1 mm. Prior to the prospectively planned 6-month follow up scan, 83 of 114 patients (73%) had CT scans at 3 months after symptom onset to monitor the evolution of their lung disease.
All CT images were reviewed in random order by three senior cardiothoracic radiologists (HSS, YQF, and JG, with 31, 13 and 10 years of experience in thoracic radiology, respectively) who were not aware of any clinical and laboratory findings or patient outcomes. The readers independently assessed the CT features using axial and multiplanar reconstructed images. The mediastinal window (center, 50; width, 350) and lung window(center, -600; width, 1200) were obtained from the picture archiving and communication system (Vue PACS, version 11.3.5.8902, Carestream Health, Canada). After independent evaluation, discussion and consensus resolved any disagreement. For each severe pneumonia patient, the predominant CT patterns according to the Fleischner Society glossary (19 (link)) were enumerated as follows: ground-glass opacities (GGO), consolidation, reticulation, emphysema, thickening of the adjacentpleura, pleural effusion, presence of nodules or masses, honey combing, bronchiectasis and interlobar pleural traction (retraction of the interlobar pleura toward the lesions). The CT evidence of fibrotic-like changes was defined as the presence of traction bronchiectasis, parenchymal bands(12 (link), 20 (link)), and/or honeycombing(19 (link))(
To quantify the extent of pulmonary abnormalities (total lesions, GGO, consolidation, reticulation and fibrotic-like changes), a semiquantitative CT score (21 (link)) was assigned on the basis of the area involved in each of the five lung lobes: 0, no involvement; 1, < 5% 2, 5%-25%;3, 26%-49%; 4, 50%-75%;and 5, >75%. The total CT severity score was calculated by summing the individual lobar scores (possible scores range from 0 to 25).
