Longitudinal analysis of perfusion lung scintigrams of patients with unoperated chronic thromboembolic pulmonary hypertension

Abstract

Chronic thromboembolic pulmonary hypertension (CTEPH) is the result of single or recurrent pulmonary thromboemboli that are thought to develop into organized pulmonary arterial obstructions by recurrent embolism and in situ thrombosis. Radioisotopic ventilation-perfusion scanning (V/Q scan) is a safe and highly sensitive test for pulmonary thromboembolic disease. The aim was to assess the natural history of thrombus expansion. We performed a prospective quantitative evaluation of ventilation/perfusion scintigrams (V/Q scans) in 20 patients with severe unoperated CTEPH. The baseline V/Q scan of each patient served as a reference for the second scan 21.7 +/- 8.2 months later. Planar images with intravenous 99mTc-labeled human albumin macroaggregates were reconstructed in six standard projections. Perfusion scans were analyzed by a semi-quantitative evaluation. In parallel, hemodynamics and clinical condition were prospectively observed. Lung perfusion scintigrams analyzed by a semi-quantitative method in patients with severe unoperated CTEPH show an apparent decrease of segmental flow abnormalities over time, paralleling right ventricular decline.

Update on Chronic Thromboembolic Pulmonary Hypertension

“…95 A normal ventilation/perfusion scan virtually excludes CTEPH, although scans tend to normalize as disease progresses. 96 Despite modern multidetector CT technology, a normal CT pulmonary angiogram alone cannot safely exclude the diagnosis of CTEPH. Additional concern regarding reliance on CT includes false-positive cases from conditions mimicking CTEPH, such as mural pulmonary arterial thrombi in congenital heart disease or in severe idiopathic PAH.…”

Diagnosis and Treatment of Pulmonary Hypertension

“…11 In addition, the classical segmental perfusion defects may disappear during the CTEPH terminal stage. 12 Perfusion scintigraphy appears nonsegmented in cases of large central thrombotic masses in Eisenmenger syndrome or thrombus within aneurysm of pulmonary trunk or pulmonary artery branches in idiopathic PAH. 13 Laboratory Therapy PAH therapy is a complex strategy which might be divided into three basic steps as follows: the initial approach and application of general measures, introduction of CCB therapy (only patients with positive vasoreactivity test) and/or specific PAH therapies, and finally, the third step which entails monitoring of the initial therapy response, introduction of combined PAH therapy, patient care during the terminal disease stage, and determining indications for lung transplantation.…”

Advanced Imaging Tools Rather Than Hemodynamics Should Be the Primary Approach for Diagnosing, Following, and Managing Pulmonary Arterial Hypertension

“… 62 A normal V/Q, but not a normal CTPA, can exclude CTEPH, although scans tend to normalize as disease progresses. 63 CTEPH may be the single PH subset in which advanced imaging and not RHC may be the primary approach to diagnosis, follow-up, and management. In the example shown in Figure 1 , the correct diagnosis of CTEPH was made after an echocardiogram and a V/Q scan had been obtained.…”