Thoracic MR Imaging Technical Considerations and Clinical Applications

Mamdouh Mahfouz MD

Prof. of Radiology

Cairo University

www.ssregypt.com

CLOSED MAGNET

CLOSED MAGNET

OPEN MAGNET

EXTERMITY MAGNET

H

H

H

H

H

H

K

H

H

P C

Na

N

H

O

H

H2O

Water represents 75-80% of the human body

O H H

MR Imaging

Magnet

Radio frequency coil

Hydrogen Atom [proton]

H H H H H H H H

MR Imaging

Hydrogen Atom [proton]

H

H

H

H

H

H

H

H

MR Imaging

Hydrogen Atom [proton]

H

H

H

H

H

H

H

H

Adequate Mobile

H

SIGNAL

LOW

HIGH

INTERMEDIATE

DARK, HYPOINTENSE

BRIGHT, HYPERINTENSE

GRAY, ISOINTENSE

MR images depend on the movement of hydrogen protons in response to the applied radiofrequency

Cortical bone

Mature fibrous tissue

Calcifications

Non mobile hydrogen

AIR

Lung &

Sinuses

Minimal hydrogen

H

Amount

Motion Minimal hydrogen [air] → no signal

Non mobile hydrogen [cortical bone] → no signal Fast hydrogen [flowing blood] → no signal

The image will depend on

T2 T1

Air

Cortical bone

Fibrous tissue

Calcifications

Flowing blood

Each structure [lesion] in the human body has a characteristic signal

T2 T1 Subacute blood

Each structure [lesion] in the human body has a characteristic signal

T2 T1 Subacute blood

Each structure [lesion] in the human body has a characteristic signal

T2 T1

T2 T1

Fluid

Fat

T1

T1

T2

T2

Fat

Blood

T1 T2

Small cell lung cancer

CT versus MRI

MR imaging has dramatically changed the practice of medicine

Neurology and orthopedics

Thoracic Imaging

Chest X – ray

Screening,

Emergency medicine,

Intensive care units

CT Scan

MR imaging

Assessment of vascular abnormalities [aorta,

pulmonary arteries, veins, SVC,…]

Evaluation of mediastinal masses

Staging of bronchogenic carcinoma

Diagnosis of chest wall pathology

MAJOR CLINICAL APPLICATIONS

Aortic dissection

Vessels appear usually black due to the signal void of flowing blood

Flow sensitive techniques

Saccular aortic aneurysm

Pulmonary embolism

Bronchogenic carcinoma

chest wall invasion + nodes

Bronchogenic Carcinoma with mediastinal invasion

Bronchogenic Carcinoma , SVC invasion

Superior mediastinal lipoma

Pericardial cyst

T1 T2

Bronchiectasis

سبحانك اللهم و بحمدك نشهد ان ال اله اال انت نستغفرك و نتوب اليك

Thank you

Contrast injection

Modality Item

-

+

CT

MR > CT

Diffuse lung diseases

Focal lung diseases

Staging of bronchogenic carcinoma

Lung parenchyma

• Nodules, miliary shadows CT - • Masses, cysts CT = MR

Contrast injection

Modality Item

-

+

+

-

+ + +

CT

MR > CT

CT = MR

MR ≥ CT

CT = MR

CT≥ MR

MR≥ CT

CT = MR

Diffuse lung diseases

Focal lung diseases

Staging of bronchogenic carcinoma

Masses/ cysts

Lymph nodes

vessels

Hernia and diaphragmatic lesions

Primary lesions

Invasion by lung or mediastinal lesions

Pleural masses and effusion

Lung parenchyma

• Nodules, miliary shadows CT - • Masses, cysts CT = MR +

Mediastinum

• Aorta MR ± • Pulmonary arteries CT = MR ± • Pulmonary veins MR ≥ CT ± • peripheral vessels - (X ray) -

Pleural and chest wall

Contrast injection

Modality Item

-

+

+

-

+ + +

CT

MR > CT

CT = MR

MR ≥ CT

CT = MR

CT≥ MR

MR≥ CT

CT = MR

Diffuse lung diseases

Focal lung diseases

Staging of bronchogenic carcinoma

Masses/ cysts

Lymph nodes

vessels

Hernia and diaphragmatic lesions

Primary lesions

Invasion by lung or mediastinal lesions

Pleural masses and effusion

Lung parenchyma

• Nodules, miliary shadows CT - • Masses, cysts CT = MR +

Mediastinum

• Aorta MR ± • Pulmonary arteries CT = MR ± • Pulmonary veins MR ≥ CT ± • peripheral vessels - (X ray) -

Pleural and chest wall

Intramural hematoma in the descending aorta

MR pulse sequences

T1 weighted images

T2 weighted images

Gradient images

Spin echo images

Fast spin echo images

T1 weighted images with fat suppression

T1 weighted images with contrast [Gd- DTPA]

Molecular O2 enhanced MR imaging

?

THE END

Current applications

Lung cancer

Superior structure tumor

Invasion of vessels [No contrast material]

Mediastinum Pericardium Chest wall [90% sensitivity] Spine

Lymph node deposits

Adrenal metastases

Differentiation of tumors from obstructive atelectasis

Evaluation after surgery or radiotherapy

Aortic dissection

Tumour

Empyema

Bronchogenic carcinoma

invading the pulmonary artery

Bronchogenic carcinoma

Chondrosarcoma of the chest wall

Assessment of chest wall lesions