Pulmonary artery sarcoma: the opportunity of the integrated imaging for an early diagnosis

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1 Pulmonary artery sarcoma: the opportunity of the integrated imaging for an early diagnosis Award: Certificate of Merit Poster No.: C-0036 Congress: ECR 2013 Type: Educational Exhibit Authors: D. Attinà, F. Niro, P. Tchouante, M. Zompatori; Bologna/IT Keywords: Thorax, Pulmonary vessels, Oncology, CT-Angiography, PET-CT, MR, Contrast agent-intravenous, Diagnostic procedure, Education, Cancer, Embolism / Thrombosis DOI: /ecr2013/C-0036 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 11

2 Learning objectives Familiarize the radiologist with the clinical and imaging characteristics of pulmonary artery sarcomas, in order to place the correct differential diagnosis with acute and chronic pulmonary embolism, in which this rare malignancy is most commonly confused. Background Pulmonary artery sarcomas (PAS) are rare malignant tumor, poorly differentiated, which originate in most cases by the totipotent intimal stem cells of the pulmonary trunk, and for this reason is referred to as "intimal sarcoma"; in the literature about 250 cases have been described [1,2]. Histopatology The intimal PASs usually are malignant mesenchymal tumors, poorly differentiated, with fibroblastic or miofibroblastic differentiation. In some cases may present specific histological patterns and be classified in osteosarcomas, rhabdomyosarcomas and angiosarcomas (most frequently). The pulmonary artery leiomyosarcomas are instead sarcomas arising from the "tunica media" of the vessel and are called "wall sarcomas" [3]. The distinction of different tumors is based exclusively on histological findings. Clinical findings PASs occur in middle age, with no specific clinical features, which may mimic other diseases such as lung cancer, mediastinal masses, and especially acute or chronic pulmonary embolism. They have a poor prognosis, so early and proper diagnosis is necessary to set the appropriate therapy. Symptoms include chest pain, cough, dyspnea, hemoptysis, pulmonary hypertension and right heart failure [4,5]. Often there are also systemic manifestations such as fever, anemia, night sweats and weight loss that are indicators of malignancy. The absence of predisposing factors for pulmonary embolism (no venous thrombosis of lower limb with echo-color-doppler, no finding suggestive of hypercoagulable state) and the progressive worsening of dyspnea in patients with intraluminal filling defect despite anticoagulation therapy are factors suggesting for PAS. Therapy and prognosis Page 2 of 11

3 PAS have a poor prognosis. Surgical resection remains the therapy of choice, preferably carried out with radical intent. However despite the surgical therapy, the average survival time is approximately 12 months [3]. In case of tumors that determine occlusion of the arterial branches with main significant hemodynamic changes, palliative surgery to relieve symptoms can be helpful. The average survival to 5 years in patients with PAS is less than 6%. Death is usually due to right heart failure by obstruction of the pulmonary arteries [6]. For these reasons, a correct early diagnosis is of fundamental importance and the radiologist is usually the first that can put the suspicion of PAS in patients with severe dyspnea and filling defect in the pulmonary artery. Imaging findings OR Procedure details Chest X-Ray is performed as the first level investigation, but it result always nonspecific. May be normal or more frequently can show an acute pulmonary embolism-like pattern, with increase of pulmonary arteries diameter, regional oligemia and parenchymal opacities suggestive of pulmonary infarcts (Figure 1a) [7].The main role of chest Xray is to exclude other diseases that may present with similar symptoms and to make suggestions for the next work-up. Scintigraphy is used in the diagnostic work-up of suspected pulmonary embolism, it detects the consequences of filling defect on pulmonary ventilation and perfusion (mismatch). It appear of limited value in the differential diagnosis, because it does not allow direct visualization of the filling defects and does not allow to evaluate their precise nature, location and extent. Trans-esophageal echocardiography is also used in the diagnostic work-up of PAS, because provides real-time details about valvular and ventricular function, the physiological significance of the lesions and their effect on other cardiac structures [8]. Pulmonary angiography is rarely used in the diagnostic phase, for best results of CT, PET and MRI. The angiographic signs are the presence of intraluminal opacification defects, abrupt termination of an arterial branch and parenchymal perfusion defects. PAS can also be present as polypoid filling defect, moving during the cardiac cycle [8]. Page 3 of 11

4 Computed Tomography (CT) allows to perform the first step in the differential diagnosis between PAS and pulmonary embolism. The characteristics of CT for diagnosis of PAS compared to acute or chronic pulmonary embolism include: -Pulmonary artery filling defects iso-hypodense on scans acquired without contrast medium (30 HU on average, hardly distinguishable from superimposed thrombotic formations), with subsequent patchy and delayed contrast enhancement in the Angio-CT, even more evident during the venous phase, with HU densitometric increasement, on average (Figures 2 and 3). - Pulmonary arteries increased in diameter, with swollen and "padded" appearance of more involved traits; an extraluminal extension of the tumor in the mediastinum or in the lung parenchyma can be observed in some cases (Figure 1b). - Pulmonary nodules with a possible "halo sign" expression of parenchymal metastases. - Signs of right ventricular pressure overload, as dilatation of the right cardiac chambers and tricuspid regurgitation of contrast medium. FDG-PET is used to differentiate between PAS and pulmonary embolism on the basis of the intensity of increased radiopharmaceutical uptake (Figure 2d, 4) [9,10].In fact FDGPET shows increased radiopharmaceutical uptake at the level of tumor filling defects with values of standardized uptake value (SUV) suggestive of malignancy. The thrombi, instead, generally do not exhibit increased activity but may have a slight increased activity in case of chronic embolism. MRI is a second level imaging technique, that allows a better characterization of the lesions on the basis of tissue characteristics and to better differentiate the thrombotic component from that neoplastic. The main disadvantages of MRI are represented by the spatial resolution still lower than TC and the necessity of a greater duration of apnea, considering that the majority of the patients examined for this condition are strongly dyspnoeic. In black-blood T1 weighted sequences after administration of paramagnetic contrast agents, typically PAS have significant contrast enhancement whereas thrombi are not, but the possible association of PAS and thrombosis may further complicate the picture (Figure 5) [11]. In order to differentiate between thrombosis and PAS it is possible to use FGRE IR sequences with inversion time of 600 ms, that show the thrombotic material signal annulment (Figure 6), while PAS usually appear isodense to muscle tissue. The intensity of contrast enhancement after contrast medium is correlated with the degree of tumor differentiation [12] and can be also used in post-intervention follow-up and monitoring, to evaluate residual or recurrent tumor. Page 4 of 11

5 Images for this section: Fig. 1: Chest X-ray (a) showed marked ectasia of the pulmonary arteries. The Angio-CT coronal reconstruction image (b) shows multiple filling defects of the pulmonary arteries, with extraluminal extension in some areas (arrows). Fig. 2: The axial CT scans before (a) and after contrast medium during the arterial (b) and venous phase (c) show filling defects with significant contrast enhancement in venous Page 5 of 11

6 phase (80 HU versus baseline 50 HU). The axial PET-TC fusion image (d) shows an increased FDG uptake (SUV 7). Fig. 3: Angiosarcoma of the left pulmonary artery. The tumor tissue shows delayed contrast enhancement: arterial phase (a) 27 HU, venous phase (b) 50 HU. Page 6 of 11

7 Fig. 4: The filling defect due to the angiosarcoma -x- is isodense in the no-contrast CT scan (a) and subsequently shows contrast enhancement (b), while the superimposed acute thrombotic material -y- is comparatively little differentiable without contrast medium (a) and not shows later contrast enhancement (b). Also the axial PET-CT fusion image (c) and the PET image with attenuation correction (d) show increased uptake of FDG at the level of tumor tissue in the right pulmonary artery, but not of the superimposed thrombotic material. Page 7 of 11

8 Fig. 5: Cardiac-gated MRI in a patient with bilateral PAS. Black-blood T1w coronal images without contrast medium (a, b) and after paramagnetic contrast medium (c, d) show a mass which occupies the pulmonary trunk and the right pulmonary artery, and also extends in the left pulmonary artery. The thrombotic material (arrow) does not show contrast enhancement, while the neoplastic tissue shows a significant c.e. (arrowheads). Page 8 of 11

9 Fig. 6: FGRE IR sequences with inversion time to 600 ms show the annulment of thrombotic material signal (arrow), while the neoplastic tissue is inhomogeneously isodense to the muscle tissue (arrowhead). Page 9 of 11

10 Conclusion PAS is a highly aggressive and rapidly evolving disease, underdiagnosed and misunderstood. Early diagnosis with the help of integrated imaging remains today the main road to pursue in order to obtain improvements in prognosis. Angio-CT images in the presence of a filling defect with contrast enhancement in the pulmonary artery should put the suspicion of malignancy and the hypothesis should be confirmed by a high uptake on CT-PET with FDG or contrast MRI hyperintensity. The presence of tumor extraluminal extension as well as distant metastases are reliable signs of differential diagnosis between PAS and pulmonary embolism, but these are manifestations of advanced cancer. For these reasons, the radiologist must be aware of the imaging characteristics of this rare disease to be able to put the suspicion of PAS in patients with severe dyspnea and filling defect in the pulmonary artery unresponsive to anticoagulation therapy. References 1. Blackmon SH, Reardon MJ (2010) Pulmonary artery sarcoma. Methodist Debakey Cardiovasc J 6: Huo L, Lai S, Gladish G et al (2005) Pulmonary artery angiosarcoma: a clinicopathologic and radiological correlation. Ann Diagn Pathol 9: Burke AP, Virmani R (1993) Sarcomas of the great vessels. A clinicopathologic study. Cancer 71: Cox JE, Chiles C, Aquino SL et al (1997) Pulmonary artery sarcomas: a review of clinical and radiologic features. J Comput Assist Tomogr 21: Simpson WL, Mendelson DS (2000) Pulmonary artery and aortic sarcomas: crosssectional imaging. J Thorac Imaging 15: De Luca F, Modolon C, Buia F et al (2012) Densitometric CT evaluation of acute and chronic thromboembolic filling defects of the pulmonary arteries before and after contrast injection. Radiol Med 117: Page 10 of 11

11 7. Pandit SA, Fiedler PN, Westcott JL (2005) Primary angiosarcoma of the lung. Annals diagn pathol 9: Scheffel H, Stolzmann P, Plass A et al (2008) Primary intimal pulmonary artery sarcoma: a diagnostic challenge. J Thorac Cardiovasc Surg 135: Kauczor HU, Schwickert HC, Mayer E et al (1994) Pulmonary artery sarcoma mimicking chronic thromboembolic disease: computed tomography and magnetic resonance imaging findings. Cardiovasc Intervent Radiol 17: Kacl GM, Bruder E, Pfammatter T (1998) Primary angiosarcoma of the pulmonary arteries: dynamic contrast-enhanced MRI. J Comput Assist Tomogr 22: Rafal RB, Nichols JN, Markisz JA (1995) Pulmonary artery sarcoma: diagnosis and postoperative follow-up with gadolinium-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging. Mayo Clin Proc 70: Kojima K, Okamoto I, Ushijima S t al (2003) Successful treatment of primary pulmonary angiosarcoma. Chest 124: Personal Information Domenico Attinà MD Cardio-Thoracic-Vascular Department Cardio-Thoracic Radiology Unit University-Hospital S.Orsola-Malpighi Via Massarenti 9, Bologna Tel.: , Fax: Page 11 of 11