CT Diagnosis of Chronic Pulmonary Thromboembolism

Abstract

Chronic pulmonary thromboembolism is mainly a consequence of incomplete resolution of pulmonary thromboembolism. Increased vascular resistance due to obstruction of the vascular bed leads to pulmonary hypertension. Chronic thromboembolic pulmonary hypertension is clearly more common than previously was thought, and misdiagnosis is common because patients often present with nonspecific symptoms related to pulmonary hypertension. Computed tomography (CT) is a useful alternative to conventional angiography not only for diagnosing chronic pulmonary thromboembolism but also for determining which cases are treatable with surgery and confirming technical success postoperatively. The vascular CT signs include direct pulmonary artery signs (complete obstruction, partial obstruction, eccentric thrombus, calcified thrombus, bands, webs, poststenotic dilatation), signs related to pulmonary hypertension (enlargement of main pulmonary arteries, atherosclerotic calcification, tortuous vessels, right ventricular enlargement, hypertrophy), and signs of systemic collateral supply (enlargement of bronchial and nonbronchial systemic arteries). The parenchymal signs include scars, a mosaic perfusion pattern, focal ground-glass opacities, and bronchial anomalies. The presence of one or more of these radiologic signs arouses suspicion and allows diagnosis of this entity. Early recognition of chronic pulmonary thromboembolism may help improve the outcome, since the condition is potentially curable with pulmonary thromboendarterectomy.

The Role of Radiation Diagnostic Techniques in the Diagnosis of Chronic Thromboembolic Pulmonary Hypertension

“…Была показана высокая диагностическая точность КТА, синхронизированной с ЭКГ [15]. Наглядно представить результаты исследова-ния помогают трехмерные реконструкции со-судистого дерева легких [20]. Типичные признаки ХТЭЛГ при проведении КТА следующие:…”

“…При расширении ПЖ соотношение диаметров правого и левого (ЛЖ) желудочков составляет более 1:1, а также отмечается выбухание межжелудочковой пере-городки в полость ЛЖ. Данные признаки могут быть выявлены даже при выполнении исследо-вания без синхронизации с ЭКГ [20]. Расшире-ние ПЖ может сопровождаться расширением кольца трехстворчатого клапана и, как следст-вие, развитием трикуспидальной недостаточ-ности, для которой характерно контрастирова-ние печеночных вен при проведении КТА.…”

Ventilation Perfusion Single Photon Emission Tomography (V/Q SPECT) in the Diagnosis of Pulmonary Embolism

“…Also, it should be pointed out that it seems difficult to justify the higher radiation dose and contrast agent of CTPA solely for follow-up purposes. There are of course some signs that permit distinction by CTPA of acute and chronic embolism but differentiation between the two conditions is far from being always easy (Castaner, Gallardo et al 2009). …”

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) – Potential Role of Multidetector-Row CT (MD-CT) and MR Imaging in the Diagnosis and Differential Diagnosis of the Disease

“…5, 6). The latter is characterized by sharply demarcated regions of hypoattenuation that is produced by hypoperfusion in lung areas distal to occluded vessels or by small-vessel arteriopathy in non-obstructed lung areas [20,21]. Hyperattenuation on the other hand is the sequelae of a compensatory increase in blood flow to patent pulmonary vessels.…”

“…9). A further specific finding of IPAH is corkscrew-like peripheral pulmonary arteries that represent intimal cellular proliferation and medial hypertrophy as part of the plexogenic arteriopathy [20,21]. Sometimes acute thromboembolism with extensive right heart impairment may cause difficulties in differentiation from CTEPH.…”