CTICasesSmall Vessel Chronic Thromboembolic Pulmonary Hypertension (Type 4 CTEPH)
Imaging findings
CT pulmonary angiogram in a patient with severe pulmonary hypertension demonstrates a dilated main pulmonary artery and right-sided chambers with contrast reflux, but no visible central thromboemboli, webs, or arterial stenosis. Dual-energy CT blood volume maps and planar/SPECT V/Q scans reveal severe, patchy, subsegmental mismatch perfusion defects, confirming a type 4 small-vessel pattern.
Key takeaways
Type 4 chronic thromboembolic pulmonary hypertension (CTEPH) involves distal, microscopic vascular occlusion or remodeling rather than surgically accessible central thromboemboli. These patients have normal or near-normal conventional CT angiograms but display characteristic patchy, mismatched subsegmental perfusion defects on V/Q scans or dual-energy CT, and they are treated medically with targeted therapies like riociguat.
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