Systemic approach to Chest CT Hidayatullah Hamidi 4th year radiology resident, FMIC, Kabul April 2016 www.afrad.org

آنِ دیگران را از خویش می خواهند بدان ای عزیز که رنج مردم از سه چیز است چون رزق تو از دیگران جداست؛ پس این همه رنج بیهوده چراست؟ از وقت ‍پیش می خواهند از قسمت بیش می خواهند آنِ دیگران را از خویش می خواهند خواجه عبدالله انصاری

Review of chest CT requires: Airway Lungs Pleura Mediastinum Heart Vessels Hila Bones and soft tissue Diaphragm & sub diaphragm knowledge of normal CT anatomy systematic approach characterizing the abnormality Looking for DDx

Windowing Lung Mediastinum Bone

Post processing MPR: For sagittal and coronal views MIP: Projects highest attenuation voxels (Nodules) MiniIP: lowest attenuation pixel values(airway/emphysema) 3D VRT: Displays volume of tissue in 3D

HU

Chick list

Airways: Trachea and Bronchi 1 Airways: Trachea and Bronchi Shape, course, wall thickening, dilatation, narrowing, luminal mass, calcification… Wall thickness 1-3 mm Diameter: M: 13-25 mm coronal and 13-27 mm sagittal F: 10-21 mm coronal and 10-23 mm sagittal Tracheal index: Coronal/ sagittal diameter ≈1 Bronchi: Thin wall, diameter similar to adjacent arteries

2 Lungs Paired, symmetrical, lobar division, architecture Normal attenuation values: (Inspi –700 to –900 HU) Complete aeration Fully apposed to chest wall Vascular markings (diminish from center to periphery)

Abnormalities Pattern High attenuation Low attenuation Reticular Nodular Distribution: Upper/lower Central/peripheral

3 Pleura Normally very thin, usually not visible on CT Thickening, enhancement, nodularity, effusion, calcification

4 Mediastinum Centered Components: esophagus, Thymus, Heart, great vessels Compartments: Anterior, middle, posterior Hilar region: any mass or lymphadenopathy

4a Heart Position, configuration, size, chambers, Normal marks: Internal diameter of LV is larger than RV Convexity of IVS is directed toward RV Atria: smooth, thin walled and similar size Thin interatrial septum Myocardium: uniform thickness with homogenous enhancement.

Pericardium Thickness: ≤ 3 mm No noticeable enhancement Effusion, calcification, nodularity

4b Thoracic vessels Origin, course, size, configuration Veins: BSVs, IVC, SCV, PVs Arteries: AA, BCA, Left CCA, LSCA, PAs

Aorta

SVC Mixing of contrast with unopacified blood often creates artifactual filling defects

PAs MPA: <3.2 cm or smaller than AA

4c Thoracic Lymph Nodes Size and location

Diaphragm/sub-diaphragmatic area 5 Diaphragm/sub-diaphragmatic area Shape Contour abnormalities CP angles Position Any abnormality in the included sections of abdomen

6a Thoracic skeleton Ribs, clavicle, sternum, scapula, spine Position Contours Symmetry Any bone expansion/destruction Any lesion

6b Soft tissues Configuration Symmetry Density

Sample of normal Chest CT report Findings: Both lungs are normally aerated and are applied to the chest wall on all sides. There is no sign of circumscribed pleural thickening and no fluid collection. Pulmonary structure is normal showing normal vascular markings. There are no intrapulmonary nodules or consolidation The mediastinum is centered and of normal width. No evidence of any mass lesion. The hilar region on each side is unremarkable, and the main bronchi appear normal. The heart is normal in size and configuration. The cardiac chambers are of normal size. Major intrathoracic vessels and imaged portions of the supra-aortic vessels are unremarkable. The thoracic skeleton and thoracic soft tissues show no abnormalities. Conclusion: No abnormal CT findings

References CT of the Airways, Boiselle, Phillip M., Lynch, David, 2008 Normal Findings in CT and MRI, Torsten B, Moeller, 2000 Brent P. Little, MD, Approach to Chest Computed Tomography; Clin Chest Med 36 (2015) 127–145

Post presentation evaluation

Find the abnormality Saber-sheath trachea :TI <0,5 COPD

Lunate trachea: TI >1

Pattern of abnormality?

pattern and distribution in lung? Central Ground glass Peripheral Consolidation Lower lung Honeycombing Upper lung Traction broncheictasis

Distribution of small nodules

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