Respiratory dynamic MRI for determining aortic invasion of thoracic neoplasms

Transcription

1 Respiratory dynamic MRI for determining aortic invasion of thoracic neoplasms Poster No.: C-0760 Congress: ECR 2013 Type: Educational Exhibit Authors: Y. J. Hong, J. Hur, H.-J. Lee, Y. J. Kim, B. W. Choi; Seoul/KR Keywords: Diagnostic procedure, MR, CT, Lung, Arteries / Aorta, Cancer DOI: /ecr2013/C-0760 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 14

2 Learning objectives To assess whether respiratory dynamic magnetic resonance imaging (RD MRI) improves the accuracy of conventional MRI or computed tomography (CT) in determining aortic invasion of mediastinal tumors and lung cancer. Background The invasion of lung cancer into the aorta (T4/stage IIIb) often means local resection is not possible and carries the poorest long-term outcome [1, 2]. To prevent providing palliative therapy to a curative tumor due to over-staging or ineffective and unnecessary surgery due to under-staging, accurate pre-operative assessment of aortic wall invasion is necessary. In mediastinal tumors, aortic invasion indicates a poor outcome. In thymomas, for example, aortic invasion represents stage III disease, which has a poor prognosis and high recurrence rate. Extensive en bloc resection of the aorta followed by vascular reconstruction is necessary for good results [3, 4, 5]. A previous study addressed the use of cine MRI to evaluate the invasion of lung cancer into moving structures, such as the chest wall or cardiovascular structures [6]. However, evaluation of major structures with minimal motion such as the distal aortic arch, descending thoracic aorta, superior vena cava, and pulmonary veins is limited by the absence or low levels of motion on the cine MRI [6,7]. Respiratory dynamic MRI (RD MRI) during breathing is a useful imaging technique with a high diagnostic accuracy for chest wall invasion by lung cancer [8,9]. Because of the independent motion between the chest wall and lungs during breathing, RD MRI helps to assess the chest wall invasion by lung cancer. Because the lung is a dynamic organ, we hypothesized that the aorta and the lungs also move independently during breathing. Therefore, dynamic imaging during respiration may provide additional information over static images alone in the diagnosis of tumor invasion into the aorta. The aim of this study is to assess whether RD MRI improves the accuracy of conventional MRI or CT in the determination of aortic wall invasion of mediastinal tumors and lung cancer Imaging findings OR Procedure details Patient selection Page 2 of 14

3 From June 2008 to July 2012, 90 patients with mediastinal or lung masses with suspicious cardiovascular invasion on chest CT prior to surgery undergone chest MRI. Of these, 37 who had lung masses abutting the aorta on axial images on chest MRI included. Eleven patients were excluded from this study according to the exclusion criteria as follows: (a) multiple lung metastases or other distant metastases (n=7); (b) lack of pathological results (n = 3); and (c) failure to provide informed consent (n=1). Finally, 26 patients were included for analysis. Two radiologists independently reviewed chest CT scans to evaluate aortic invasion. Differences in assessment were resolved by consensus. The study population consisted of 19 men and seven women aged 43 to 81 years (mean age 63±12.05 years). Baseline clinical characteristics, including systemic hypertension, pulmonary tuberculosis, diabetes mellitus, and smoking habits were determined from medical records and routine laboratory data. CT technique CT was performed with a 16-channel MDCT (Somatom Sensation 16, Siemens, Forchheim, Germany) or 64-channel MDCT (Sensation 64, Siemens Medical Solutions, Forchheim, Germany). Scanning was performed using the helical technique during a single breath-hold after injection of contrast material with the patients in a supine position. A total of ml of iopamidol (300 mg of iodine per milliliter; Radisense, Taejoon, Pharm, Seoul, Korea) was administered intravenously to all patients at a rate of 3-4 ml/s using a power injector (Envision CT, Medrad, USA). To obtain thin-section CT images, we used the following parameters: 120 kvp, 200 effective mas, 0.5s gantry rotation, 0.75 mm collimation, and a 0.5 mm interval. Image data were reconstructed with a thickness of 1.0 mm and an increment of 1.0 mm using a standard algorithm. The scan area ranged from the lung apices to the level of the middle portion of both kidneys. All CT images were retrieved on a picture archiving and communication system (Centricity; GE Medical Systems, Milwaukee, WI) to allow free manipulation of the images for the evaluation of lesions. MRI technique Conventional MRI images were obtained with a 1.5 T unit (Achieva, Philips Medical Systems, Netherlands). We obtained the following sequencest1-weighted axial image using 3D gradient echo sequence with and without fat suppression (THRIVE, TR/TE = 3 / 1 msec, flip angle 10, field of view 40 cm, matrix 256 x 256, and slice thickness 5mm) and post-contrast T1-weighted axial image using 3D gradient echo sequence with fat suppression (THRIVE). Respiratory dynamic (RD) MRI sequential images were acquired using Balanced FFE sequence during deep respiration (TR/TE = 2.3/1.1ms, flip angle 50, field of view 38 cm, Page 3 of 14

4 matrix 128 x 128, and slice thickness 10 mm). For examination of tumor mobility, one to five slices per plane either in coronal or sagittal planes perpendicular to the suspicious invasion site between the mass and the adjacent aorta were acquired for each patient. Therefore, 80 to one 100 sequential images during deep respiration were obtained in the coronal or sagittal planes, depending on the location of the tumor. Imaging analysis Two radiologists independently and retrospectively reviewed the CT, conventional MRI alone and in combination with RD MRI. Differences in assessment were resolved by consensus. MRIs were initially assessed without RD MRI, followed by a second review after one week that combined both conventional MRI and RD MRI in the same session. The criteria for aortic invasion of a thoracic mass on CT and conventional MRI were as follows: 1) obliteration of intervening mediastinal fat between the thoracic mass and aorta; 2) irregular indentation of aortic wall by the mass; 3) assessment of the extent and degree between the contacting area of the thoracic mass and the surrounding adjacent aorta greater than 90 º or greater than 3 cm on axial images; and 4) the presence of an obtuse angle between the mass and the aorta. CT or conventional MRI findings were classified as either negative or positive for aortic invasion. Only one positive criterion was necessary for the tumor to be classified as positive for aortic invasion. To evaluate direct invasion of the thoracic mass into the adjacent aortic wall by RD MRI, we analyzed the dynamic relationship between the tumor and the aorta in the cine-loop mode. RD MRI was determined as negative for aortic invasion when the tumor moved along the aorta freely in synchrony with breathing and as positive for aortic invasion when the tumor was fixed to the aorta with lack of synchronous motion during respiration. In combination of conventional MRI with RD MRI, if both conventional MRI and RD MRI were positive, it was considered as positive for aortic invasion. If RD MRI was negative, it was considered a negative result. The CT and MRI results were compared with pathological results. Images for this section: Page 4 of 14

5 Fig. 1: A 63-year-old woman with squamous cell carcinoma in the left lower lobe. (a) Contrast-enhanced CT images demonstrate a 3.8 cm mass in the left lower lobe abutting the descending thoracic aorta (arrow). (b) T1-weighted MRI images with fat suppression demonstrate isodense mass in left lower lobe without suspicious invasion of descending aorta (arrow). (c) Post-contrast T1-weighted MRI images with fat suppression demonstrate heterogeneously enhancing tumor without suspicious invasion of the descending thoracic aorta (arrow). Page 5 of 14

6 Fig. 2: A 63-year-old woman with squamous cell carcinoma in the left lower lobe (same patient with Figure 1.) (a) Respiratory dynamic MRI images reveal sliding motion between the tumor and the adjacent descending thoracic aorta. Tumor invasion of the descending aorta was not found at surgery. Page 6 of 14

7 Fig. 3: A 76-year-old woman with metastatic sarcoma in the left lower lobe. (a) Contrastenhanced CT images demonstrate a 5.3 cm mass in the left lower lobe with suspicious invasion of the descending thoracic aorta (arrow). (b) T1-weighted axial MRI images demonstrate heterogeneous signal intensity tumor abutting the descending thoracic aorta (arrow). There was obliteration of the fat plane between the tumor and the adjacent aorta (arrowhead) (c) Post-contrast coronal T1-wighted MRI images with fat suppression demonstrate heterogeneously enhancing tumor (arrow) with suspicious invasion of the descending thoracic aorta (arrowhead). Page 7 of 14

8 Fig. 4: A 76-year-old woman with metastatic sarcoma in the left lower lobe (same patient with Figure 3.). (a) Respiratory dynamic MRI images reveal no sliding motion between the tumor and the adjacent descending thoracic aorta. Tumor invasion of the descending aorta was found at surgery. Page 8 of 14

9 Table 1: Table 1. Clinical Characteristics of 26 Patients Page 9 of 14

10 Table 3: Table 3. Comparison of MRI Results and Pathological Results in the Determination of Proximal Aorta Invasion Page 10 of 14

11 Table 4: Table 4. Comparison of MRI Results and Pathological Results in the Determination of Descending Thoracic Aorta Invasion Page 11 of 14

12 Table 2: Table 2. Results of MRI for the Determination of Aorta Invasion in 26 Lung Cancer Patients Page 12 of 14

13 Conclusion Respiratory dynamic (RD) MRI can provide additional information and improve diagnostic accuracy of preoperative staging for predicting aortic invasion. Combining RD MRI with conventional MRI helps to avoid false-positive interpretations of conventional MRI especially for the determination of descending thoracic aortic invasion. RD MRI improves the specificity and diagnostic accuracy of conventional CT scan or MRI in the prediction of aortic invasion of thoracic neoplasms. This is especially true in patients with equivocal results from a conventional CT scan or MRI in the presence of a thoracic mass abutting the aortic wall surface without obvious aortic wall invasion. References 1. Schroder C, Schonhofer B, Vogel B (2005) Transesophageal echographic determination of aortic invasion by lung cancer. Chest 127: DiPerna CA, Wood DE (2005) Surgical management of T3 and T4 lung cancer. Clin Cancer Res 11:5038s-5044s. 3. Murakawa T, Nakajima J, Kohno T, et al (2000) Results from surgical treatment for thymoma. 43 years of experience. Jpn J Thorac Cardiovasc Surg Feb;48(2): Johnson SB, Eng TY, Giaccone G, Thomas CR Jr (2001) Thymoma: update for the new millennium. Oncologist 6(3): Minato N, Rikitake K, Ohnoshi H, Takarabe K, Ishida H (1999) Invasive thymoma with intracaval growth extending and directly invading the right atrium. J Cardiovasc Surg (Torino) Dec;40(6): Seo JS, Kim YJ, Choi BW, Choe KO (2005) Usefulness of magnetic resonance imaging for evaluation of cardiovascular invasion: evaluation of sliding motion between thoracic mass and adjacent structures on cine MR images. J Magn Reson Imaging 22: Sakai S, Murayama S, Murakami J, Hashiguchi N, Masuda K (1997) Bronchogenic carcinoma invasion of the chest wall: evaluation with dynamic cine MRI during breathing. J Comput Assist Tomogr 21: Akata S, Kajiwara N, Park J, et al (2008) Evaluation of chest wall invasion by lung cancer using respiratory dynamic MRI. J Med Imaging Radiat Oncol 52: Page 13 of 14

14 9. Lee CH, GOO JM, Kim YT, et al (2010) The clinical feasibility of using non-breathhold real-time MR-echo imaging for the evaluation of mediastinal and chest wall tumor invasion. Korean J Radiol Jan-Feb;11(1): Personal Information Page 14 of 14