g ferretti anterior and middle mediastinal mass jfim hanoi 2015
TRANSCRIPT
Imaging of anterior and middle mediastinal
masses
G Ferretti S Lantuejoul Radiologie Centrale et Imagerie Médicale Anatomopathologie CHU Grenoble
Objectives
n To present the last version of mediastinal compartments
n To show the useful signs to characterize mediastinal masses on CT or MR
n To describe the more common masses based on density or signal and location
Detection of mediastinal masses: CXR
n displaced n enlarged n abnormal contours
• lines • bands • interfaces
Based on: n Mass effect n Abnormal contours of the mediastinum
Mediastinal lines: limites
Les lignes médiastinales ne sont pas constamment visibles (Proto JTI 1987; 2: 47) :
1. Ligne médiastinale postérieure 15%
2. Ligne médiastinale antérieure 60%
3. Interface aortique descendant 100%
4. Ligne paravertébrale gauche 65%
5. Ligne paravertébrale droite 40%
6. Bande para trachéale droite 97%
7. Bouton azygos 98%
8. Bande para oesophagienne 90%
n Several traditional mediastinal division schemes exist based upon arbitrary landmarks on the lateral chest radiograph (anatomy, surgical, radiology)
n However, CT has replaced CXR and this group proposed a new division of the mediastinum based on CT landmarks
n Localization of a tumor within one of the compartments of the mediastinum n Narrows the differential diagnosis n Gives a probability of malignancy of the tumor n Assist in planning histological sampling n Assist in planning surgery
International thymic malignancy interest group
Number of Compartments
n This clinical classification defines 1. a prevascular (anterior) compartment 2. a visceral (middle) compartment 3. a paravertebral (posterior) compartment
n with anatomic boundaries defined clearly by CT
ITMIG compartiments of mediastinum
n prevascular (anterior)
n visceral (middle) n paravertebral (posterior)
n Posterior limit of the anterior mediastinum is the anterior aspect of the pericardium as it wraps around in a curvilinear fashion (thus any vessels contained within the pericardium are located in the middle mediastinum)
n contents of the prevascular compartment : the thymus, fat, lymph nodes, and the left brachiocephalic vein.
n Boundaries of visceral mediastinum n anteriorly—the anterior aspect of the pericardium
n posteriorly—a vertical line connecting a point on the thoracic vertebral bodies 1 cm posterior to the anterior margin of the spine
Localization of Mediastinal Abnormalities: CT MRI two tools are useful: 1. the “center method.” the center of a mediastinal
lesion localizes the abnormality to a specific compartment.
2. the “structure displacement tool.” Very large
mediastinal masses can displace organs from other compartments, usually those that abut the compartment from which the tumor originated.
Carter BW JTO 2014;9:s97-s101
Goals imaging Ø Identification and localization Ø Description and characterization Ø Accurate differential diagnosis - short list Ø Recommendation of a cost effective
imaging and patient management Ø guiding biopsies Ø planning surgery
Ø Follow-up
Thacker PG J Thorax Imaging 2015;30:247-264
CT ü Non contrast ü Arterial phase ü Venous phase ü MIP
MRI ü T1 ü T2 / T2 fat sat ü T1 Gd ü MR angiography ü Cardiac gating
Quality control
US Nuclear medicine
PET CT MIBG
CXR
Juanpere S Insight Imaging 2013;4:29-52
CT / MR Fat or fatty lesion
Tissue density
Water containing
Lymph node Vascular origin
Bowel structure
1-Localization Center method
Structure displacement tool
2-Characterization
Fat containing lesions1.6–2.3% of all primary mediastinal tumours
Attenuation – 40 to –130 HU Hyper signal T1
Glazer AJR 1992
anterior mediastinum lipomatosis
60 yo man CXR before aortic surgery. Middle mediastinum lipoma
Giant thymolipoma
18 yo man 3 months coughing
Teratoma benign
Heterogeneity of teratomas Common combinations of internal
components of mature teratomas: n soft tissue, fluid, fat and calcification 39% n soft tissue, fluid and fat 24% n soft tissue and fluid 15% n non-specific cystic lesions 15% Mature and immature teratomas have the
same presentation
Takahashi K J Magn Reson Imaging 2010; 32:1325–1339
Liposarcoma n Usually symptomatic n Can range from
predominantly fatty mass to solid mass with little or no macroscopic fat
n Differential: lipoma, thymolipoma, mediastinal germ cell tumor.
Fat containing masses
Anterior mediastinum • teratoma • lipoma • thymolipoma • hibernoma
Anterior cardiophrenic angle • fat • Morgani’s hernia • teratoma • lipoma • thymolipoma
Posterior mediastinum • fat hernia
All compartments • lipomatosis • liposarcoma
Cysts and cystic lesionsMediastinal primary cysts: 15–20% of all primary mediastinal masses
Water attenuation (not always) Low signal T1 hyper signal T2
Cyst: no/tiny wall, no tissue thickening, no enhancement of the wall, various density / signal
Cystic tumor
Kim JCAT 2003
Bronchogenic cyst
30 yo woman Esophageal Duplication
Foregut duplication cysts (middle compartment) n Embryologic origin: Bronchogenic, esophageal,
neurenteric
n 11% of pediatric / 20% of adult mediastinal masses n only the presence of a vertebral cleft +
mediastinal cyst is specific: neurenteric cyst n Round / oval smoothly marginated mass n Tiny / no wall n 50%: hyperintense T2WI or near 0 HU n Hemorrhage or infection: higher density /signal
and increase in size
1995 2001
Pericardial cyst
Congenital thymic cyst. KYSTE EPITHELIAL thymique bénin de 55 mm de grand axe, développé sur un parenchyme thymique siège de multiples micro-kystes développés au dépens des
corpuscules de Hassal plus ou moins calcifiés. Pas d'élément suspect de malignité.
homme 68 ans 4214
This is not a cyst: the wall is thick and enhanced
Thymoma with cystic component
découvert fortuite préopératoire absence de myasthénie
thymectomie élargie 6*10cm exérèse macroscopique complète
Thymoma with cystic portion 65 yo man
CT for asbestosis exposure Thymoma
Thymic cyt n 1% of all mediastinal masses n Congenital or acquired (inflammation HIV) n Rare well defined mass with smooth walls, non
enhancing n CRX: occult n CT: not always water density: differential solid
mass n MR > CT: hypo intense on T1 WI and hyper
intense on T2WI; lack of internal enhancement Ackman JB AJR 2011;197:w15-w20
Lympadenopathy central necrosis tuberculosis
Cystic masses True cysts • Bronchogenic / esophageal • Thymic • Pericardial • Lymphangioma • Hydatidosis
Masses with cystic component • Thymoma • Teratoma • Lymphoma • Neurogenic T • LAP (BK, metastases)
Pseudo-cysts • pancreatic
Localized • Pleurisy • Pericarditis
other • Meningocele • lymphocele
Vascular masses
Aneurism of the descending aorta
Oesophageal varices
Soft tissue masses of anterior mediastinum
Strollo Chest 1997 Thacker PG JTO 2014; 30 :247-267
11 ans 17 ans
36 ans 52 ans
Thymus appearance varies with age
Normal Thymus on CT n Detection: frequency
n < 30 yo: 100% n 30-50 yo: 70% n > 50 yo: 20%
n Thickness n < 18 mm if age < 25 y but < 13 mm if age > 25 y
n Smoothly marginated homogeneous gland, no compression. Convex external borders if > 25 y
n Densité n Gradual fatty replacement
Nasseri F Radiographics 2010;30:413-428
26 5 2006
13 2 2006 True thymic hyperplasia after stopping chemotherapy.
Diffuse symmetric enlargement of the gland, smooth contour and normal vessels
32 yo woman myasthenia gravis since 4 years 14 mm thick thymus with contrast enhancemement: Thymoma? Hyperplasia? Thymectomy : 28gr thymus with Follicular lymphoid hyperplasia
Woman 53 yo (5100) Thymoma
43 yo man myasthenia gravis (4426) CT: lesion anterior mediastinum 6 x 3.8 cm No fat plane between tumor and aorta Central calcification thymectomy was possible thymoma B3
B3 thymoma with pleural metastases
Pericardial extent of a thymoma
Thymoma n Rare in children (1-2% prevascular Tumors) n Frequent in adults > 40yo n Thymic epithelial tumor with lymphocytes n 40% of patients have paraneoplastic syndrome:
myasthenia n At histology : invasive / non invasive based of the
integrity of the capsule n CT/MR are not able to precisely define invasive vs.
noninvasive thymoma +++
CT and thymoma n 2 radiological types : presurgical staging
n T1 : well limited mass surrounded of mediastinal fat, of limited size and various density: encapsulated thymoma at imaging that may be encapsulated thymomas or thymomas with limited extracapsular extension at pathology. Surgery without biopsy
n T II : not well limited mass, large size, heterogeneous attenuation, with signs of macroscopic extracapsular extension (medistinum, pleura, pericardial, distant). Surgery may not be curative. Surgery? TT biopsy?
Inaoka T Radiology 2007 243:869-876
Myasthenia and thymus n At pathology, the thymus of myastenic patients
shows: n 65% follicular lymphoid hyperplasia n 15% thymoma n 20% normal thymus
n 30-50% of thymomas are linked with myasthenia
n Synchronous ou asynchronous n 25% of patients (woman) are better after thymectomy
Harvard CWH Drugs 1983;26:174-84
Mizuno T Surg Today 1997;27:275-77
MRI n After CT in some cases n Not > to CT for local extension or for
prognostic value
Thymic carcinoma 5691
Man 69 yo Paralysie diaphragmatique droite
24 yo man. Mass + AFP : 75000 (Yolk Sac Tumor)
Nonteratomatous germ cell T (NTGCT) n Seminomatous T of anterior M
n Large homogenous, lobulated, tumors n compression of mediastinum
n Nonseminomatous T of anterior M n Large heterogeneous tumors n Invasion of adjacent structures, ADP
n Accuracy of CT MRI is not good for histology n Role +++ of biology n Elevation of α-fetoprotein (AFP) and/or human chorionic gonadotropin
(HCG) support the diagnosis Oldenburg J Ann Oncol 2013;24:125-132
Ectopic goiter
Mediastinal goiter n direct contiguous growth of a goitre into
the anterior or superior mediastinum. n encapsulated and lobulated mass with
inhomogeneous appearance (cystic, calcifications, contrast enhancement)
n Intrathoracic thyroid mass from heterotopic thyroid tissue without any connection to the thyroid in the neck is extremely rare
Lymphoma 2-10% of anterior masses in patients >40 yo n Hodgkin disease (Reed Sternberg cells) ~70%
n mediastinal 60%, young patients,
n NHL T- or B-lymphocytes ~30% n Large prevascular mass n Separate/confluent lymphadenopathy or large mass
displacing adjacent structures. No calcification before treatment
n Role of PET CT > CT / MRI except for DWI MRI Mayerhoefer ME Clin Cancer Res 2014;20:2984-93
38 yo woman Hodgkin disease
20yo w NHL
Tumor of anterior mediastinum n Thymus
n Epithelial T n Thymoma n Carcinoma
n Germ cell T n Lymphoma n Thymic Carcinoid n Thymolipoma n Cysts
n other n Para thyroid
Adenoma n Lymphangioma n Endothoracic Goiter
OMS 2004
Conclusion n New anatomic classification n Role of CT
n Fat within tumor ? n Cyts vs. cystic tumors n Surgical vs. non surgical tumors
n Role of biology n Choice of appropriate biopsy technique