Lung iodine mapping images of acute postpartum dyspnea without pulmonary thromboembolism using dual-energy CT

Postpartum dyspnea is commonly observed, but its cause is often unknown.

To investigate postpartum dyspnea, we compared lung iodine mapping (LIM) using dual-energy computed tomography (DECT) between postpartum women and women suspected of having pulmonary thromboembolism (PTE).

In this retrospective study, 109 women of reproductive age (50 postpartum women, 59 women unrelated to pregnancy) underwent DECT between March 2009 and August 2020. Among the postpartum women, 23 patients were excluded due to late-onset dyspnea (n=20: >48 h after delivery) or the presence of PTE (n=3). A total of 86 patients were divided into three groups (27 postpartum women [postpartum group], 19 women with PTE [PTE group], and 40 women without PTE [non-PTE group]). Quantitation was applied to a decreased LIM value (LIM₅; defined as <5 HU) and the relative value of LIM₅ to whole LIM volume (%LIM₅). LIM defects were classified into five patterns (0 = none, 1 = wedge-shaped, 2 = reticular/liner, 3 = diffuse granular/patchy, 4 = massive defects) based on a consensus between two readers.

There were significant differences in the LIM₅ and %LIM₅ values among the three groups. The LIM₅ and %LIM₅ were largest in the PTE group, and postpartum women showed intermediate values between the non-PTE and PTE groups. Wedge-shaped defects were prominent in the PTE group, and diffuse granular/patchy defect was a typical feature in the postpartum group.

Postpartum women with dyspnea showed granular/patchy defects on DECT with a median quantitative value between the PTE and non-PTE groups.