Cardiac tumors: A pictorial MRI guide for differential diagnosis

Transcription

1 Cardiac tumors: A pictorial MRI guide for differential diagnosis Poster No.: C-1276 Congress: ECR 2013 Type: Educational Exhibit Authors: G. Ironi, A. Esposito, P. Marra, F. De Cobelli, A. Del Maschio; Milan/IT Keywords: Tissue characterisation, Neoplasia, Education and training, Diagnostic procedure, Contrast agent-intravenous, MR, Oncology, Cardiac DOI: /ecr2013/C-1276 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 34

2 Learning objectives Magnetic resonance imaging (MRI) is the technique of choice for the evaluation of cardiac masses. In order to perform a correct diagnosis the radiologist needs to know aspects concerning epidemiology, clinical presentation and specific radiological features of heart tumors and pseudomasses. Our aims are: Focus reader's attention on the rare problem of cardiac tumors Present MRI sequences used in our clinical practice for the best evaluation and characterization of cardiac masses Show specific features of the most frequent heart neoplasms, using selected images from our institution Provide a systematic guide that can help the radiologist in the differential diagnosis Page 2 of 34

3 Background 1. Epidemiology The frequency of cardiac tumors is low, but they cause significant morbidity and mortality. Neoplastic heart masses can be divided into metastatic or primary tumors. Metastatic involvement of the heart is 40 times more frequent than primary cardiac neoplasms and is often underdiagnosed. [1] Non cardiac tumors may involve the heart and pericardium by one of four pathways: retrograde lymphatic extension, hematogenous spread (eg. melanoma), direct contiguous extension (eg. bronchogenic carcinomas) or transvenous extension (eg. tumor from the kidney or liver). [1] Primary cardiac tumors are very rare; 75% of these are benign while only one fourth are malignant. [2] The commonest benign primary tumor is mixoma, while lipoma and fibroma occur less frequently. [3-5] Primary malignant tumors of the heart are predominantly sarcomatous in nature: the most common of these is angiosarcoma [6], followed by sarcomas with different mesenchymal differentiation. Another malignancy is primary cardiac lymphoma which predominantly occurs in immunocompromised subjects. [7] 2. Clinical aspects Clinical manifestations of cardiac tumors depend on their size and location: some may remain clinically silent with accidental diagnosis, large masses or intracavitary mobile tumors may result in intracardiac obstruction or systemic embolization and infiltrative or intramural lesions frequently cause arrhythmias. [4] 3. MR versus other imaging modalities Echocardiography: A variety of imaging modalities are available for the accurate evaluation of cardiac masses. Transthoracic echocardiography often is the initial imaging tool employed in assessment of suspected cardiac neoplasm because it is inexpensive, rapidly performed and ubiquitous. Important limits of this technique are operator experience, restricted field of view and difficulties in patients who have large body habitus. Transesophageal echocardiography can provide a more detailed assessment of small masses, masses within the atria and masses associated with valves, but this is more expensive and less available than transthoracic echocardiography, with the limitation of a relatively narrow field of view and of a higher discomfort for patients. Most importantly, echocardiographic approach provides limited tissue characterization which is a fundamental point for the comprehensive evaluation of cardiac masses. Page 3 of 34

4 Computed Tomography: Since the introduction of multi-detector scanners, CT has been increasingly utilized for cardiac imaging. Its major advantages consist in high spatial resolution, wide field of view, ability to detect small calcification inside cardiac masses and excellent visualization of extracardiac anatomy. However, CT has an inferior low soft tissue contrast resolution than MR and suffers from significant limitations inherent to cine studies (less temporal resolution and higher radiation exposure). Magnetic Resonance: MR imaging is becoming the modality of choice in evaluating heart neoplasms because it allows accurate confirmation about the presence of a lesion, localization, extension and overall allows tissue characterization. In addition it is non invasive and offers direct multiplanar imaging, large field of view and high spatial, contrast and temporal resolution. T1-weighted, T2-weighted, and gadolinium enhanced sequences are used for anatomic definition and tissue characterization, whereas cine stady-state free precession (SSFP) imaging is used to assess functional effects. Perfusion study is used to provide additional information about lesion vascularity and composition. Avid first pass enhancement is characteristic of highly vascular tumors, such as angiosarcoma. Delayed enhancement reflects slow contrast medium uptake and washout within areas of expanded interstitium, such as fibrous tissue. [4] Perfusion analyses are also useful in the evaluation of metastatic heart disease. As the relative contrast enhancement depends on the absolute uptake of the contrast media both by the lesion and by the surrounding tissue, the post-contrast signal enhancement of a metastasis may appear different in comparison to the primary tumor. For instance, a cardiac metastasis from hepatocellular carcinoma (Figure 11), which is known to have an early and strong enhancement, could present as a low-enhancing mass if compared to the surrounding myocardium. For this reason it should be useful to assess tumor enhancement by signal/time curves, in order to obtain reliable information about tumor vascularization and eventually to compare the vascular behavior of cardiac suspected metastasis with the primary tumor. A relative limitation of MR imaging is the low sensitivity in depicting calcification, so, in some selected cases, it should be combined with CT. 4. Differentiating malignancies from benign tumors: general radiological features Imaging evaluation of cardiac tumors is important not only for diagnosis but also for determination of prognosis and in planning therapy, including surgical resection. [3] In order to make a differential diagnosis it's important to consider several features such as specific predilection for certain cardiac chambers or valves, tumor mobility, attachment site and signal characteristics. Furthermore, it is pivotal to differentiate between benign and malignant neoplasms because the clinical approach is completely different. Features that suggest malignancy are [3, 8]: Page 4 of 34

5 invasion of extra-cardiac structures involvement of more than one cardiac chamber involvement of the right side of the heart tissue inhomogeneity poor definition of borders greater than 5 cm diameter presence of pericardial or pleural effusion In addition, as recently shown by Bauner et al., the enhancement curve after administration of contrast material may provide other criteria for the evaluation of tumor aggressiveness. [9] After a cardiac mass has been detected, imaging should be the first step aiding the clinician to choose the best clinical behavior: radiological signs of nonaggressiveness suggest that a watchful waiting approach or simple surgical resection could be safe; in a small number of cases imaging is not diriment and a biopsy should be performed. Patients with unresectable malignancies may be offered chemotherapy (eg lymphoma) or palliation (large infiltrative angiosarcoma). Page 5 of 34

6 Imaging findings OR Procedure details 1. MR tumor protocol As a multiparametric technique MR allows different approaches for the characterization of cardiac masses and the best cardiac MR protocol must be suited individually based on the location and the extent of the tumor. If not contraindicated all the patients with a suspect of heart neoplasm should be preferentially investegated with the intravenous administration of a gadolinium-based contrast agent (gadobutrol, Gadovist, Bayer Healthcare Pharma in our series). A first both morphologic and functional evaluation is achieved with cine studies that rely on the acquisition of "bright blood" balanced SSFP sequences which have both T1w and T2w effects. Cine SSFP sequences have high spatial and temporal resolution and are particularly useful to evaluate the mobility of a lesion and its impact on cardiac contractility; they also allow to depict eventual valve defects when the lesions involve such structures. Morphologic MRI provides a more accurate understanding of the size and the extent of a lesion and relies on the variable acquisition of multiplanar "black blood" T1w, T2w and/or PDw sequences usually preceded by single or multiple saturation pulses that can suppress selectively blood or fat signal to better characterize the neoplastic tissue. In particular T2w STIR sequences are sensitive to fluid and edema and can enhance myocardial and pericardial cysts or ischemic area inside the myocardium. About ten minutes after the intravenous administration of the contrast media other multiplanar IR TFE T1w sequences are acquired in order to depict the eventual fibrotic degeneration of the lesions, which is frequent in benign conditions such as fibromas, fibroelastomas and rarely mixomas. These sequences rely on the principle of the late enhancement which is due to a delayed wash out of gadolinium from a fibrotic tissue, that causes a prolonged T1 shortening effect. In addition to this morphologic and functional information, the execution of a perfusion study, which is based on the rapid acquisition of 3D T1w sequences on multiple slices early after contrast agent administration, offers information about tumor vascularization and vascular infiltration. We applied the previously described sequences on a 1.5 tesla MR scanner. All the images were collected over a period of five years (from 2008 to 2012) from the archives of our institution with the help of a highly experienced radiologist (A. Esposito). 2. Benign tumors Page 6 of 34

7 We propose schematic tables and peculiar images representative of the most frequent cardiac neoplasms (tables 1-6, figures 1-6). 3. Malignancies Tables 7-12, figures Tumor mimics Thrombus (Fig. 12) It is the most common intracardiac mass mimicking a cardiac tumor. It is more frequently located in the left atrium, commonly in the presence of atrial fibrillation, or in severely dysfunctional left ventricles. It can also be found in the right side of the heart, especially in the right atrium when there is a central venous catheter. The signal intensity characteristics of thrombus are well shown in table 13. Note that a thrombus can assume different aspects depending on its age and that, in most cases, does not enhance with gadolinium contrast material. This lack of enhancement is very useful in differentiating it from a myxoma, although an organized thrombus may show some surface enhancement. Extracardiac masses: Pericardial cyst (Fig. 13): benign congenital lesion that arises from pericardium and does not communicate with pericardial space. It is usually found at the right cardio-phrenic angle, although it may occur anywhere in the mediastinum. This well-defined lesion has the MR imaging characteristics of simple fluid (hypointense on T1-weighted images and hyperintense on T2-weighted images) and does not enhance after contrast material administration. Bronchogenic cyst Intrathoracic neoplasms Gastrointestinal hernias Normal cardiac structures: Crista terminalis of the right atrium (Fig. 14) Eustachian valve Prominent ventricular trabeculae Highly trabeculated atrial appendages Hypertrophy of papillary muscles Page 7 of 34

8 Page 8 of 34

9 Images for this section: Table 1 Page 9 of 34

10 Fig. 1: A mixoma with atypical cardiac location. A two-chambers sbtfe cine sequence (A, B) shows a well-defined hypointense mass of the right ventricle's conus arteriosus that doesn't appear to significantly affect cardiac contractility during systole. The lesion is isointense to myocardium on PDw imaging without signal loss when a fat-saturation prepulse is applied: this can help to distinguish it from a lipoma (C). On (IR-TFE) late enhancement imaging (D) the mass doesn't present residual contrast enhancement. This benign neoplasm may just require an annual follow-up by echocardiography. Page 10 of 34

11 Table 2 Fig. 2: Two simultaneous papillary fibroelastomas respectively arising from the anterior edge of the tricuspid valve and from the free wall of the right atrium. A long-axis four-chambers cine sequence (A) shows two hypointense intracavitary pedunculated lesions in the right atrium. On late-enhancement imaging only the tumor of the atrial Page 11 of 34

12 wall can be distinguished as a hypointense nodule with no evidence of residual contrast enhancement (B). Table 3 Page 12 of 34

13 Fig. 3: A large fibroma of the interventricular septum markedly hypointense on cine imaging: in A and B the diastolic and the systolic phases of the cardiac cycle are respectively shown on a short axis two-chambers plane; the intramural bulky mass which impresses both the right and the left ventricular cavities limits the contractility of the septum. However this benign tumor has a well-delimited non-infiltrative aspect. The lesion shows typical very-low signal intensity on short-t1-inversion-recovery imaging (C) and doesn't appear to have a significant contrast enhancement immediately after the intravenous administration of gadobutrol (D). Due to the hypovascular and fibrotic nature of this lesion the enhancement becomes more evident 10 minutes after the contrast agent administration with a typical hyperintensity which shows up on late-enhancement imaging (E-F). Page 13 of 34

14 Table 4 Page 14 of 34

15 Fig. 4: A hemangioma of the posterior wall of the right atrium which shows heterogeneous hyperintensity on T2w (PDw) imaging (A-B respectively on a coronal and axial plane) with higher signal intensity when a fat-saturation prepulse is applied (C, STIR). The heterogeneity of the signal intensity is usually due to hemorrhagic foci that, alone, are not predictive for malignancy. Furthermore the lesion is not associated with pericardial effusion and doesn't seem to have an infiltrative behavior. Page 15 of 34

16 Table 5 Page 16 of 34

17 Fig. 5: A lipoma arising from the interatrial septum with intracavitary extension into the right atrium appears as a well-defined non infiltrative mass: the lesion which is hyperintense on cine imaging (A-B) doesn't significantly affect atrial filling during the cardiac cycle. The soft-tissue consistence of the mass is reflected by its shape deformation during systole (A) and diastole (B). On a sagittal plane PDw imaging the tumor shows high signal intensity (C) which is completely suppressed with a fat-saturation sequence (D). Page 17 of 34

18 Table 6 Fig. 6: A paraganglioma arising from the inferior wall of the left atrium here appears as a broad-base mass with high signal intensity on sagittal plane T2w imaging both with (B) and without (A) a fat-saturation prepulse. The tumor, which usually grows within the atrial wall originates from paragangliar cells and may have an encapsulated or an infiltrative aspect with heterogeneous signal intensity due to hemorrhagic and/or necrotic foci. Page 18 of 34

19 Table 7 Table 8 Page 19 of 34

20 Table 9 Page 20 of 34

21 Fig. 7: A primary angiosarcoma of the free wall of the right atrium with metastatic spread to the lung. On cine imaging (A) the mass has a heterogeneous iso- to hyperinetense «cauliflower» aspect (due to the presence of hemorrhagic and necrotic foci) and tends to infiltrate adjacent structures and the pericardium with subsequent pericardial effusion that typically can be hemorrhagic, leading to cardiac tamponade. Due to its infiltrative behavior, the malignancy impacts negatively on cardiac contractility. On T2w-STIR images the mass shows a heterogeneous hyperintensity (B). On perfusion imaging (C) the lesion rapidly and strongly enhances with a described «sunray» aspect due to the filling of large vascular channels representative of tumoral angiogenesis. Image D shows the peculiar aspect on CT-scan of lung metastasis from angiosarcoma: a hyperdense hypervascular-hemorrhagic core is sorrounded by a ground-glass area. Page 21 of 34

22 Table 10 Fig. 8: A pericardial mesothelioma with loculated pericardial effusion. PDw imaging on axial (A) and coronal (B) planes shows a heterogeneous mostly isointense mass which seems to spread through the pericardial sheets. On gadolinium-enhanced T1w imaging on the axial plane (C) the hypointense effusion appears delimitated by thickened pericardial sheets which have a nodular and irregular aspect with an avid contrast agent uptake. Page 22 of 34

23 Table 11 Page 23 of 34

24 Fig. 9: Morphologic and cine studies of a primary cardiac lymphoma originating from the right atrio-ventricular sulcus: cine images are shown on a long-axis four-chambers (A) and on a short-axis two-chambers (B) planes. The isointense mass has an invasive aspect and is associated with a large pericardial effusion. However the lymphoma shows a typical growth that respects other structures encountered: the right coronaric artery (arrow head in image B) which is completely surrounded by the tumor doesn't seem to be compressed or infiltrated by it. Axial T2w-STIR images are characterized by a slight hyperintensity that diffusely infiltrate the myocardium. Notably, on perfusion imaging (C) the mass doesn't show a significant contrast enhancement. Page 24 of 34

25 Table 12 Page 25 of 34

26 Fig. 10: Images in the upper half of the figure show an example of trans-caval metastatic spread of a hepatoma: the tumor has an heterogeneous signal intensity and is predominantly hyperintense to the liver. On perfusion imaging (B) the mass shows a discrete contrast enhancement. C and D images illustrate a metastatic involvement of the left ventricle from a mammary angiosarcoma: this is a case of hematogenous spread. On a long-axis two-chambers cine sequence (C) the tumor appears as an isointense irregular-shaped mass with intracavitary growth. On perfusion imaging (D) the lesion enhances less than the myocardium. Page 26 of 34

27 Fig. 11: A and B show a hematogenous metastatic spread of colorectal cancer to the antero-inferior wall of the right ventricle. On cine imaging (A) the slightly hyperintense irregular-shaped mass shows an invasive behavior with involvement of the subepicardial fat of the inferior wall of the ventricle. On perfusion imaging (B) the tumor strongly enhances in the arterial phase. In the lower half of the figure there is an exemple of a direct cardiac involvement from a squamocellular carcinoma of the lung. On cine imaging (C) the tumor seems to invade through the pericardial sheets and the subepicardial fat even if the myocardium doesn't appear infiltrated. On perfusion imaging (D) it is visible a separation line between the heart and the strongly enhancing tumor. Page 27 of 34

28 Table 13 Fig. 12: An apical thrombus of the left ventricle. A and B respectively show the diastolic and the systolic phases of the cardiac cycle: the cine study is particularly useful as it demonstrates that the intracavitary mass is adjacent to an hypo-akinetic area of myocardium. Furthermore, late enhancement imaging (C) illustrates that ventricular wall near the thrombus is thinned and fibrotic, features suggestive for myocardial infarction. Page 28 of 34

29 Table 14 Page 29 of 34

30 Fig. 13: Pericardial cysts (A-B) should be primarly distinguished from loculated pericardial or pleural effusion on the base of clinical history and other imaging findings. They usually have an homogeneous slight hyperintensity on PDw imaging (A) and are markedly hyperintense on T2w imaging and cine imaging (B). Benign pericardial cysts are frequently uniloculated and located at the right cardiophrenic angle (B) with no effects on cardiac contractility. They cannot always be differentiated from pleural cysts. Cysts of the myocardium are very uncommon: C and D respectively show well-delimited high signal intensities both on T2w imaging with fat-saturation (STIR) and on cine imaging. This is an intramyocardial cyst of the lateral wall of the left ventricle associated with a discrete pericardial effusion. Page 30 of 34

31 Fig. 14: This cine "bright blood" image illustrates a prominent crista terminalis protruding into the right atrium: this structure, that physiologically varies in size and extent among individuals, could be misdiagnosed at echocardiography. Page 31 of 34

32 Conclusion Imaging evaluation of cardiac tumors plays a fundamental role as allows specific tumor characterization in many cases. When specific tumor characterization is not possible, imaging is useful for the assessment of features that, in addition to clinical data (signs, symptoms and age at presentation), can help in differentiating malignancies from benign tumors. The evaluation of tumor aggressiveness through imaging modalities is very important to formulate a prognostic assessment (as malignant tumors have a poor prognosis while benign tumor generally have a favourable prognosis) and to plan the best suited therapeutic strategy. Thanks to its ability to better characterize soft tissues MR is even superior to echocardiography and CT and it should guide patient management. Page 32 of 34

33 References 1. Chiles C, Woodard PK, Gutierrez FR, et al. (2001) Metastatic involvement of the heart and pericardium: CT and MR imaging. Radiographics 21: Chu LC, Johnson PT, Halushka MK, et al. (2012) Multidetector CT of the heart: spectrum of benign and malignant cardiac masses. Emerg.Radiol. 19: Sparrow PJ, Kurian JB, Jones TR, et al. (2005) MR imaging of cardiac tumors. Radiographics 25: Randhawa K, Ganeshan A and Hoey ET. (2011) Magnetic resonance imaging of cardiac tumors: part 1, sequences, protocols, and benign tumors. Curr.Probl.Diagn.Radiol. 40: Lam KY, Dickens P and Chan AC. (1993) Tumors of the heart. A 20-year experience with a review of 12,485 consecutive autopsies. Arch.Pathol.Lab.Med. 117: Best AK, Dobson RL and Ahmad AR. (2003) Best cases from the AFIP: cardiac angiosarcoma. Radiographics 23 Spec No: S O'Sullivan PJ and Gladish GW. (2008) Cardiac tumors. Semin.Roentgenol. 43: Syed IS, Feng D, Harris SR, et al. (2008) MR imaging of cardiac masses. Magn.Reson.Imaging Clin.N.Am. 16: , vii 9. Bauner KU, Sourbron S, Picciolo M, et al. (2012) MR first pass perfusion of benign and malignant cardiac tumours-significant differences and diagnostic accuracy. Eur.Radiol. 22: De Cobelli F, Esposito A, Mellone R, et al. (2005) Images in cardiovascular medicine. Late enhancement of a left ventricular cardiac fibroma assessed with gadoliniumenhanced cardiovascular magnetic resonance. Circulation 112: e242-3 Page 33 of 34

34 Personal Information Gabriele Ironi, Antonio Esposito, Paolo Marra, Francesco De Cobelli and Alessandro Del Maschio; - Experimental Imaging Center, San Raffaele Scientific Institute, Milan, Italy - Department of Radiology, San Raffaele University Hospital, Milan, Italy Correspondence to: - Gabriele Ironi: g.ironi@studenti.unisr.it - Antonio Esposito: esposito.antonio@unisr.it Page 34 of 34