CASE 797 Published on 09.10.2001

Chronic pulmonary embolism

Section

Chest imaging

Case Type

Clinical Cases

Authors

T. Boehm, D. Weishaupt, P. Hilfiker

Patient

52 years, male

Categories

No Area of Interest ; Imaging Technique CT, CT, CT

No Procedure ; No Special Focus ;

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Clinical History

A 52 years old previously healthy patient presented with worsening exertional dyspnea over the preceding year.

Imaging Findings

A 52-year-old previously healthy patient presented with worsening exertional dyspnea over the preceding year. Chest X-ray was performed by the referring physician and was not conclusive. CT (Siemens VolumeZoom, collimation 4 x 2.5 mm, 140 kV, 120 mAs) showed all signs of severe pulmonary arterial hypertension : enlarged pulmonary artery trunc (3.88 cm !), enlarged right and left pulmonary artery, enlarged right ventricle, horizonal displacement of the interventricular septum and remarkable pericardial effusion. The lumen of the pulmonary artery itself was reduced bilaterally by partially recanalized, partially calcified organized thrombi. CT images in lung window settings showed the typical pattern of mosaic oligaemia with areas of hyper- and hypoattenuation. The vessel diameter was markedly smaller in areas of hypoattenuation.

Discussion

In the present case all classical CT signs (5) of chronic thrombembolic pulmonary hypertension (CTEPH) are present : 1. partially calcified, partially recanalized organized thrombi lining the pulmonary artery endothelium, 2. signs of pulmonary hypertension 3. mosaic oligaemia. The terminus CTEPH suggests that the etiology of the disorder is well known. However, it is still disputable if recurrent pulmonary embolism alone can cause pulmonary hypertension (1). Pulmonary artery thrombosis is proposed to be a more probable mechanism causing CTEPH than recurrent pulmonary embolism (1). The pathophysiology is characterized by a reduction in diameter due to thrombi adhesive to the inner wall of the pulmonary arteries (2). When a diameter reduction of 50% or more is present a severe increase in pulmonary arterial pressure occurs and the patients suffer from exertional dyspnoe. The only available therapy is thromboendarterectomy (PTE) (2). Still ten years ago PTE had a perioperative mortality of more than 20%. Now mortality rates are lower than 10%. PTE is indicated in all patients with central thrombi, even if the periphery is partially occluded. Hence, peripheral involvement makes the operation much more risky. Pulmonary angiography is still the method of choice to assess peripheral pulmonary artery involvement(2,3). Surgery should be performed in a early stage of CTEPH because higher pulmonary artery pressures worsens prognosis. Recently lung or combined heart-lung transplantation became an alternative for treatment of CTEPH (4). The patient was referred to PTE.

Differential Diagnosis List

chronic pulmonary embolism

Final Diagnosis

chronic pulmonary embolism

References

[1] Egermayer P, Peacock AJ
Is pulmonary embolism a common cause of chronic pulmonary hypertension? Limitations of the embolic hypothesis.
Eur Respir J 2000 Mar;15(3):440-8. (PMID: 10759434)

[2] Hartz RS
Surgery for chronic thromboembolic pulmonary hypertension.
World J Surg 1999 Nov;23(11):1137-47. (PMID: 10501876)

[3] van Beek EJ, Reekers JA
The value of pulmonary angiography for the differential diagnosis of pulmonary embolism.
Eur Radiol 1999;9(7):1310-6. (PMID: 10460364)

[4] Franke U, Wiebe K, Harringer W, Franke T, Wittwer T, Wahlers T, Haverich A
Ten years experience with lung and heart-lung transplantation in primary and secondary pulmonary hypertension.
Eur J Cardiothorac Surg 2000 Oct;18(4):447-52. (PMID: 11024383)

[5] Schwickert HC, Schweden F, Schild HH, Piepenburg R, Duber C, Kauczor HU, Renner C, Iversen S, Thelen M.

Pulmonary arteries and lung parenchyma in chronic pulmonary embolism: preoperative and postoperative CT findings.
Radiology 1994 May;191(2):351-7. (PMID: 8153305)

Case information

URL:	https://www.eurorad.org/case/797
DOI:	10.1594/EURORAD/CASE.797
ISSN:	1563-4086

Figure 1

axial CT images (soft tissue window)

Axial CT image at the level of the pulmonary artery trunc showing severe enlargement of the pulmonary artery (diameter 3.88 cm). A partially calcified thrombus along the dorsal wall of the left pulmonary artery causes partial obliteration of the vessel.

Axial CT image in a more caudal location showing partial obliteration of the left pulmonary artery trunc in the region of the lower lobe artery origin

Axial CT image at the level of the right ventricle showing an enlarged right ventricle and horizontal interventricular septum as indirect signs of severe pulmonary artery hypertension. Note also the pericardial effusion as a further indirect sign of increased pulmonary artery pressure.

Figure 2

sagittal MPR

Sagittal MPR showing the organized, partially recanalized and partially calcified thrombus lining the endothelium of the left pulmonary artery

Figure 3

Axial CT image, Pulmonary window settings

Axial CT images showing the typical pattern of mosaic oligaemia (=mosaic perfusion) in chronic pulmonary embolism. The "normal" areas are hyperdense (=normally perfused)in contrast to the hypoperfused (alterated by thrombi and secondary vessel wall fibrosis) areas. Note the typical smaller lumen of the pulmonary arteries in the hypoperfused regions of the lung.