The effects of different body positions of low-dose expiratory phase spiral CT on the diagnosis of pulmonary air trapping after stem cell transplantation / 中华放射学杂志

ABSTRACT

Objective To explore the effects of different body positions at the expiratory phase thinsection multi-slice spiral CT on the diagnosis of pulmonary air trapping after allogeneic hematopoietic stem cell transplantation(allo-HSCT).Methods Thirty-one allo-HSCT patients underwent the expiratory phase low-dose MSCT lung scanning at supine and prone positions to detect whether they have air trapping lesion,the volume percent of air trapping region (CT value ≤-700 HU at expiratory phase) against the whole lung was measured by using GE workstation after grading.Statistical analysis on lesion detection rate was performed with McNemar test and volume percent with rank sum test.Results Air trapping regions were observed in 8 patients (25.8％,8/31) who performed CT scan at the supine position,while 15 cases (48.4％,15/31)were positive for prone position CT scan.Seven cases showed positive results at both body positions.Statistical significance in the positive detection rate at supine and prone positions was found (x2 =4.00,P =0.039).The volume fraction of the two positions was 13 for supine position and 21 for prone position with statistical significance (Z =-3.37,P =0.001).Sensitivity at prone position CT scan to detect air trapping was much higher than that at supine position CT scan.Conclusion For allo-HSCT patients with chronic rejection reaction,performing expiratory phase thin-section CT scan and prone position scan can not only improve the detection rate of lung forepart lesions,but also preliminarily evaluate the severity of the air trapping,which can provide a basis for the early diagnosis and treatment in clinics.