Fig. 4.

Underestimation of disease burden on V/Q scan in a 53-year-old man with CTEPH. (a) A planar V/Q scan shows scattered bilateral segmental perfusion defects. (b) Coronal-oblique image from a CTPA shows numerous segmental and subsegmental areas of vascular occlusions and non-occlusive webs (white arrows). A non-obstructive layering thrombus with calcification is seen in the interlobar pulmonary artery. On V/Q scan, perfusion defects were noted in five segments. However, on CTPA, occlusive or non-occlusive disease involved the segmental and/or subsegmental vessels in all 18 segments.

Source: Image supplied by the authors.