Why Mediastinal MRI? More Specific Uses. MRI of Mediastinal Masses Jeanne B. Ackman, MD ANTERIOR MEDIASTINUM. Anterior Mediastinal Masses

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1 MRI of Mediastinal Masses Jeanne B. Ackman, MD Why Mediastinal MRI? MRI of Mediastinal Masses Jeanne B. Ackman, MD Associate Radiologist and Director of Thoracic MRI Massachusetts General Hospital Instructor, t Harvard Medical School Higher soft tissue contrast than CT No radiation exposure Why Mediastinal MRI? Lesion characterization Cystic versus solid, fibrous, proteinaceous, hemorrhagic, grossly or microscopically fatty Relationship to adjacent neurovascular and bony structures Enhancement pattern Presence of restricted diffusion More Specific Uses Thymic evaluation (cyst vs. solid, chem shift MR) Screening for lymphadenopathy Screening for paragangliomas (SDHD¹ mutation) Follow-up of probably benign lesions without radiation exposure ¹SDHD = Succinate dehydrogenase complex, subunit D, integral membrane protein Anterior Mediastinal Masses ANTERIOR MEDIASTINUM Thymus Thyroid Germ cell tumor Lymphoma Lung cancer Hemangioma Lymphangioma Pericardial cyst (or fat pad) Other 616

2 Chest CT without IV Contrast, 2011 Thymic masses 53 y.o. woman s/p lumpectomy and chemo-xrt for breast cancer 7 years prior In-Phase T1 Opposed-Phase T1 Pre-contrast (VIBE) Pre-contrast (VIBE) Coronal HASTE T2 CG Post-contrast (VIBE) Post-contrast (VIBE) T2 Opposed-Phase T1 Opposed-Phase T1 2 years later, in 2013 CG Thymic hyperplasia with simple thymic cyst 617

3 Chemical Shift MR Helps l distinguish i normal/hyperplastic l thymus from thymic tumors/lymphoma IN ADULTS In- and out-of-phase imaging:inaoka i & Takahashi, Radiology, 2007 CSR = OP SI THYMUS / OP SI PARASPINAL M. IP SI THYMUS / IP SI PARASPINAL M. IP = in-phase OP = opposed-phase SI = signal intensity as measured by ROI CSR of = normal/hyperplastic CSR of = tumor, in most cases 21 y.o. woman with arrhythmia & anterior mediastinal mass on outside CT In-phase T1 Out-of-phase T1 Thymectomy revealed histologically normal thymus! CSR = 1.0 Ackman JB, Mino-Kenudson M, Morse CR. Nonsuppressing normal thymus on chemical shift magnetic resonance imaging in a young woman. Journal of Thoracic Imaging. 2012; 27(6):W Recent Thymic Research Statistically ti ti significant ifi sex difference in normal thymic appearance between young men and women Thymus of young women (compared to men) higher h attenuation ti (p <.0001) fuller, more quadrilateral shape (p <.0001) May increase likelihood of misinterpretation of normal thymus as a mass in young women Ackman JB, Kovacina B, Carter BW, et al. Sex difference in normal thymic appearance between men and women, years of age. Radiology. 268:245-53, ROI = yo m w medullary thyroid CA whose chest CT showed anterior mediastinal mass interpreted as thymic neoplasm Chest CT with IV contrast 618

4 Coronal SSFSE T2 Sagittal SSFSE Fat Sat T2 Pre-contrast (LAVA) Post-contrast (LAVA), 20s Axial Axial Post-contrast (LAVA), 5 min Post-contrast (LAVA), 5 min, subtracted Thymic cyst Use caution Chest CT with IV contrast 61 y.o. woman with left anterior pleuritic chest pain Coronal SSFSE T2 Post-contrast (LAVA), 1 minute 619

5 Chest CT with IV contrast SSFSE T2, Coronal Thymic carcinoma This slide is courtesy of Melissa L. Rosado de Christenson, MD, FACR Section Chief, Thoracic Radiology Professor of Radiology University of Missouri-Kansas City Cystic thymoma 67 year-old woman, incidental finding on CXR Chest CT with IV Contrast In-phase T1 Out-of-phase T1 Fat Sat 620

6 ROI = 288 ROI = 86 Post-contrast (LAVA), 20 s ROI = 313 Pre-contrast, LAVA Thymoma Type AB Post-contrast (LAVA), 1 min ROI = 201 Post-contrast (LAVA), 5 min Chest CT with IV contrast Lymphoma Pre-contrast (VIBE) Post-contrast (VIBE),1 minute In-phase T1 Out-of-phase T1 Post-contrast (VIBE), 3 minute Post-contrast (VIBE), 5 minute 621

7 True FISP T2 HASTE 29 year-old pregnant woman with Hodgkins Lymphoma Thyroid In-phase T1 Out-of-phase T1 Chest CT with IV Contrast Axial In-Phase T1 Axial In-Phase T1 Post-LAVA Fat Sat T1, 20 sec Post-LAVA Fat Sat T1, 20 sec Post-LAVA Fat Sat T1, 5 min Post-LAVA Fat Sat T1, 5 min 622

8 Metastatic papillary thyroid cancer MIDDLE MEDIASTINUM (to mediastinum and a right level IV cervical lymph node) Middle Mediastinal Masses Foregut duplication cyst Esophageal mass Hemangioma Lymphangioma Hilar pseudomass on CXR Other Foregut duplication cyst CT topogram CT with IV contrast Pre-contrast (VIBE) Post-contrast (VIBE), 1 min ROI = 38 HU Post-contrast (VIBE), 3 min Post-contrast (VIBE), 1 min subtraction 623

9 Foregut duplication i cyst (likely Esophageal ) Esophageal mass Chest CT with IV contrast Axial In-Phase T1 Pre-contrast (LAVA) Post-contrast (LAVA) 63 y.o. woman with breast cancer Leiomyoma Hemangioma (endoscopic FNA results also supportive) 624

10 Axial In-Phase T1 Axial Chest CT with IV Contrast Coronal HASTE T2 Axial Pre-Contrast Axial Post-Contrast, 20 sec Axial Post-Contrast, 1 min Axial Post-Contrast, 5 min Hemangioma Middle mediastinal pseudomass Prominent hilum in a young woman 625

11 Coronal FIESTA Axial FIESTA Coronal SSFSE T2 Coronal SSFSE T2 Hilar pseudomass Prominent but normal PA in a young woman POSTERIOR MEDIASTINUM Posterior Mediastinal Masses Foregut duplication cyst Neurogenic tumor Confounder: Posterior mediastinal or Pleural? Other Ganglioneuroma 55 year old woman with cough and recent pneumonia 626

12 Chest CT with IV contrast HASTE T2, coronal Chest CT with IV contrast ROI = 38 HU Pre-contrast (VIBE) Post-contrast (VIBE), 20 s Post-contrast (VIBE), 1 min Post-contrast (VIBE), 5 min Ganglioneuroma Nerve sheath tumors Neurofibroma 627

13 Coronal HASTE T2 Coronal HASTE T2 Pre-contrast (VIBE) Post-contrast (VIBE), 20 sec Axial In-Phase T1 Axial Post-contrast (VIBE), 5 min Post-contrast (VIBE), 5 min subtracted Multiple l neurofibromas with target sign Schwannoma Chest CT with IV Contrast Pre-contrast (LAVA) Post-contrast (LAVA), 20 s ROI = 21 HU Post-contrast (LAVA), 1 min Post-contrast (LAVA), 3 min, Sagittal 628

14 HASTE T2, Coronal Fat Sat, Sagittal Schwannoma (solid) Pre-contrast (VIBE) Post-contrast (VIBE), 1 min Post-contrast (VIBE), Sagittal, 3 min Post-contrast (VIBE), Coronal, 5 min Tandem schwannomas (cystic and solid) Confounder 60 yo f w/ lesion incidentally found on Abd CT to f/u longstanding pancreatic cyst Outside Chest CT with IV Contrast 629

15 Pre-contrast (LAVA) Post-contrast (LAVA), 5 min Fat Sat, Coronal Post-contrast (LAVA), 5 min subtraction Why Mediastinal MRI? Complex intrapleural bronchogenic cyst Increase diagnostic specificity More accurately place lesion in a compartment, sometimes changing ddx completely Change surgical approach and offer more precise roadmap Spare patient unnecessary diagnostic intervention and unnecessary radiation Reassure patient re: benignity References Ackman JB. A practical guide to nonvascular thoracic magnetic resonance imaging. In press. JThoracImaging. 29:17-29, Inaoka T, Takahashi K, et al. Thymic hyperplasia and thymus gland tumors: differentiation with chemical shift MR imaging. Radiology. 243:869-76, Jeung, M-Y, Gasser B, et al. Imaging of cystic masses of the mediastinum. Radiographics. 22: S79-93, Nakagawa g M, Hara M, et al. Pleural bronchogenic cysts: imaging findings. J Thorac Imaging. 23: , Sakai S, Murayama S, et al. Differential diagnosis between thymoma and non-thymoma by dynamic MRimaging. i Acta Radiol. 43: ,