NC2011-09 Chest CT - Dr. Yasumoto

Slide 1: 

CT Chest Imaging Eric Yasumoto, M.D. Department of Radiology

CT weight limits: 

CT weight limits 1.  GE LightSpeed 8 slice CT scanner (Emergency Department)- Maximum table weight of 450 lbs. (table hydraulics may fail at weights greater than 400lbs.)  Maximum AP height of 52 cm from the table.  Maximum transverse width of 68 cm. 2.  Toshiba Aquilion 64 slice CT scanner (Radiology Department)-  Maximum table weight of 450 lbs.  Maximum AP height of 56 cm from the table.  Maximum transverse width of 70 cm. 3.  GE 1.5 T  MRI scanner- Maximum table weight of 350 lbs.  Maximum AP height of 40cm.  Maximum transverse width of 56cm. Please note that the diameter of the patient is the main factor at weights near that of the table limits.  A large diameter patient may not fit into the gantry and may have a limited scanner Field of View.

Beam Hardening Artifact: 

Beam Hardening Artifact

CT Chest Protocols: 

CT Chest Protocols CT Chest Scan without contrast Study performed at 5mm thick axial sections Patients who have contrast allergies or Creatinine levels >1.5 Following up patients with known diseases, following up infiltrates, solitary pulmonary nodules, pleural effusions CT Chest Scan without contrast-High Resolution Protocol Study performed at 1mm thick axial sections spaced every 20mm in both supine and prone positioning Thin section imaging can evaluate the pulmonary interstitium Predominately used to evaluate for interstitial lung disease to evaluate interlobular septa, ground glass opacities, centrilobular nodules (UIP, NSIP, Sarcoidosis)

CT Chest with Contrast Protocols: 

CT Chest with Contrast Protocols Routine Chest CT performed at 5mm thick axial sections after administration of 100cc Isovue 300 intravenous contrast The majority of CT chest studies to better evaluate mediastinal or hilar adenopathy, can better distinguish aortic and pulmonary artery pathology relative to the rest of the mediastinum Can evaluate the vascularity of pulmonary nodules/masses for potential biopsy Evaluate pleural fluid for surrounding pleural enhancement which may indicate and empyema Routine Chest CT to evaluate for pulmonary embolism- perform 1.25 mm thick axial sections following 100cc of Isovue 370 contrast material Need 18g antecubital IV or power PICC or power Port line

IV access: 

IV access Prefer 18g antecubital peripheral IV Power injectable central line Power injectable PICC line Power injectable chest or arm port Any peripheral or central line, PICC or port can be hand injected =good for non-CT angiogram studies

Hounsfield Unit-a quantitative scale to describe CT radiodensity: 

Hounsfield Unit-a quantitative scale to describe CT radiodensity Air -1000 HU Fat -50 to -120 HU Free fluid (water) 0-15 HU Free blood 20-40 HU Clotted blood/Hematoma 40-75 HU Contrast in vessels 100-250 HU Bone >400 HU

CT window/level: 

CT window/level Each CT pixel is assigned a CT number (hounsfield unit) To distinguish the differences in CT radiodensity a hounsfield window (width) and level (center) is used Example: Soft tissue window 400, level 40 = center level is 40HU and can optimally evaluate various densities ranging from -360 to 440 HU

Slide 10: 

Soft tissue window W400L40 Lung window W1500 L-400

Soft tissue setting Bone window setting: 

Soft tissue setting Bone window setting

CT checklist: 

CT checklist Lung Heart Mediastinum/hilum Aorta Pulmonary Arteries Chest wall-bones and soft tissues Always start by looking at the scout view!

CT checklist: 

CT checklist What type of study is it? Exclude emergent findings: 1- Pneumothorax/Pneumomediastinum 2- Aneurysmal Dissection/Intramural Hematoma 3- Large Pleural Effusions 4- Large Pericardial Effusions 5- Pulmonary Embolism

Is there contrast within the vasculature?: 

Is there contrast within the vasculature?

Contrast-compare the enhancement with the vasculature: 

Contrast-compare the enhancement with the vasculature Aorta Pulm Art

Small right side non-dependent pneumothorax: 

Small right side non-dependent pneumothorax

Slide 18: 

Small left side pneumothorax

Right side pneumothorax with mild tension: 

Right side pneumothorax with mild tension

Loculated (non-dependent) pneumothorax: 

Loculated (non-dependent) pneumothorax

Pneumomediastinum: 

Pneumomediastinum

Pneumomediastinum: 

Pneumomediastinum Laryngeal rupture Esophageal rupture Asthma Pneumothorax Trauma Sinus fractures Sinus/dental/pharyngeal infections

Chest CT scan with and without contrast: 

Chest CT scan with and without contrast Aortic Dissection Protocol Study Need the Unenhanced Study to evaluate for an Intramural Hematoma or Thrombosed False lumen Need the Enhanced Study to evaluate the Intimal Flap and to evaluate for active bleeding (active contrast extravasation) 5mm thick unenhanced axial sections without contrast followed by 1.25mm thick post contrast axial sections. 100cc Isovue 370 intravenous contrast administered.

Thoracic Aortic Aneurysm: 

Thoracic Aortic Aneurysm Ascending aorta > 3.5 Descending aorta>2.6 Operative repair considered if aneurysm = 5-5.5 cm ascending-6cm descending Surgical mortality elective repair up to 5% At 5 cm, 5-7% rate of rupture per year

Slide 25: 

Figure 2. Normal diameter and upper limit of ascending and descending aorta related to age. et al. Circulation 2010;121:e266-e369 Copyright © American Heart Association

Slide 26: 

Copyright ©2010 American Heart Association WRITING GROUP MEMBERS, et al. Circulation 2010;121:e266-e369 Mean aortic diameters (in cm) at various levels measured by helical CT in 70 adults

Aortic Dissection Classification: 

Aortic Dissection Classification

Aortic dissection with intimal flap: 

Aortic dissection with intimal flap

Intimal Flap with Dense True lumen : 

Intimal Flap with Dense True lumen

Sagittal reconstruction Type A dissection: 

Sagittal reconstruction Type A dissection

Non-contrast CT-ruptured descending thoracic aneurysm with left pleural hematoma: 

Non-contrast CT-ruptured descending thoracic aneurysm with left pleural hematoma

Non-Contrast Study showing Dense Intramural Hematoma: 

Non-Contrast Study showing Dense Intramural Hematoma

Intramural Hematoma: 

Intramural Hematoma

Intimal CA++ with dense intramural hematoma: 

Intimal CA++ with dense intramural hematoma

Utility of non-contrast and post contrast for dissection CT scans: 

Utility of non-contrast and post contrast for dissection CT scans Without contrast With contrast Intramural Hematoma

Focal contained pseudoaneurysm (mycotic): 

Focal contained pseudoaneurysm (mycotic)

Slide 39: 

Figure 10a.  Traumatic pseudoaneurysm of the proximal descending thoracic aorta. Kaewlai R et al. Radiographics 2008;28:1555-1570 ©2008 by Radiological Society of North America

Dissection with intimal flap vs pseudoaneurysm: 

Dissection with intimal flap vs pseudoaneurysm

Pseudoaneurysm: 

Pseudoaneurysm

Pericardial Effusion: 

Pericardial Effusion

Pericardial Effusion-low density: 

Pericardial Effusion-low density HU=5

Pericardial Fluid: 

Pericardial Fluid

Hemopericardium: 

Hemopericardium HU=40 HU=10

Pleural empyema- gas and dense fluid in pleural space with thickening and enhancement of the visceral and parietal pleura: 

Pleural empyema- gas and dense fluid in pleural space with thickening and enhancement of the visceral and parietal pleura

Slide 47: 

Contrast-enhanced transverse CT scan shows empyema between thickened parietal (arrowheads) and visceral (arrow) pleural layers: the split pleura sign. Kraus G J Radiology 2007;243:297-298 ©2007 by Radiological Society of North America

PA>33mm suggesting pulmonary hypertension : 

PA>33mm suggesting pulmonary hypertension

Findings in Acute Pulmonary Embolism: 

Findings in Acute Pulmonary Embolism Complete Arterial Occlusion Partial Arterial Occlusion

Findings in Acute Pulmonary Embolism 2: 

Findings in Acute Pulmonary Embolism 2 Intraluminal filling defect creating acute angles with arterial wall

Right lower pulmonary artery intraluminal filling defect: 

Right lower pulmonary artery intraluminal filling defect

Non-enhancing atelectatic lung in the right lower lobe=>pulmonary infarct: 

Non-enhancing atelectatic lung in the right lower lobe=>pulmonary infarct

Chronic Pulmonary Embolism: 

Chronic Pulmonary Embolism Pulmonary Emboli resolve 65% of the time, Partial resolution 23%, No resolution 12% 8% resolve in 24 hours, 56% in 14 days, up to 77% resolve in 7 months

Differential Diagnosis of Intraluminal Filling Defects: 

Differential Diagnosis of Intraluminal Filling Defects Acute Pulmonary Embolism Chronic Pulmonary Embolism Invasive Aspergilloma Pulmonary Angiosarcoma

Chronic PE with vessel recannulation: 

Chronic PE with vessel recannulation

Chronic thrombus with calcifications: 

Chronic thrombus with calcifications

Obtuse angle with smooth margins=chronic PE partially recanalized: 

Obtuse angle with smooth margins=chronic PE partially recanalized

Obtuse angle with smooth margins=chronic PE partially recanalized vs.sharp angle of thrombus in an acute PE: 

Obtuse angle with smooth margins=chronic PE partially recanalized vs.sharp angle of thrombus in an acute PE Acute Chronic

Pulmonary Angiosarcoma: 

Pulmonary Angiosarcoma

Centrilobular area-central part of secondary lobule =terminal bronchiole, centrilobular artery and surrounding lymphatics. Interlobular septa-peripheral part of the secondary lobule = pulmonary vein and lymphatics: 

Centrilobular area-central part of secondary lobule =terminal bronchiole, centrilobular artery and surrounding lymphatics. Interlobular septa-peripheral part of the secondary lobule = pulmonary vein and lymphatics Centrilobular area

Slide 62: 

Diagram shows anatomy and dimensions of secondary lobule and pulmonary acinus. Webb W R Radiology 2006;239:322-338 ©2006 by Radiological Society of North America

Lung parenchyma consolidaton: 

Lung parenchyma consolidaton Consolidation will obscure or partially obscure normal lung parenchyma DDX: 1. Infiltrate-pneumonia 2. Contusion 3. Infarct 4. Post obstructive process 5. Neoplasm (bronchoalveolar carcinoma/pulmonary lymphoma)

Ground Glass opacity-alveolar space process NOT obscuring bronchovascular markings: 

Ground Glass opacity-alveolar space process NOT obscuring bronchovascular markings Pneumonia (PCP,CMV) ARDS/Diffuse alveolar damage Pulmonary edema Pulmonary alveolar proteinosis Pulmonary hemorrhage Hypersensitivity Pneumonitis Intersitital lung diseases-NSIP,UIP Neoplasms-atypical adenomatoid hyperplasis, bronchoalveolar carcinoma sarcoidosis

Slide 66: 

Transverse CT scan shows interlobular septal thickening and pleural effusions. Hansell D M et al. Radiology 2008;246:697-722 ©2008 by Radiological Society of North America

Interstitial Thickening: 

Interstitial Thickening Interstitial edema Lymphangitic spread of carcinoma or lymphoma Sarcoidosis Silicosis

Slide 68: 

(a) Axial high-resolution CT scan shows mediastinal lymph node enlargement and a reticular pattern produced by nodularity and thickening of interlobular septa, pleural surfaces, and fissures, features that are seen in lymphangitic carcinomatosis as well as ... Criado E et al. Radiographics 2010;30:1567-1586 ©2010 by Radiological Society of North America

Crazy Paving-ground glass opacity with interstitial thickening: 

Crazy Paving-ground glass opacity with interstitial thickening

Perilymphatic nodules: 

Perilymphatic nodules

Perilymphatic nodules: 

Perilymphatic nodules DDX: Lymphangitic Carcinomatosis Sarcoidosis Silicosis Lymphoproliferative disorders

Centrilobular nodules-includes tree-in bud appearance: 

Centrilobular nodules-includes tree-in bud appearance

Centrilobular nodules: 

Centrilobular nodules Infection-bacterial,fungal,viral Cystic fibrosis Aspiration Allergic bronchopulmonary aspergillosis Connective tissue-rheumatoid and sjogren syndrome Hypersensitivity pneumonitis Neoplastic spread of disease Gastric Breast Ewing sarcoma Renal carcinoma

Random, miliary nodules: 

Random, miliary nodules

Random, miliary nodules: 

Random, miliary nodules Miliary TB or fungal diseases Early langerhans cell histiocytosis Hematogenous mets: Melanoma Renal cell Thyroid Breast Trophoblastic disease

Solitary Pulmonary Nodule-malignant: 

Solitary Pulmonary Nodule-malignant Cancer preferentially affects upper lobes Spiculated nodules > 90% likelihood of mailgnancy Malignancy likelihood- semisolid>ground glass>solid DDx: Lung cancer Organizing pneumonia Focal fibrosis Mycobacterium Granuloma,hamartoma Solitary metastasis

Nodule enhancement: 

Nodule enhancement >15HU enhancement more concerning for non-benign lesion

PET/CT Imaging: 

PET/CT Imaging Flourodeoxyglucose is a glucose analog Best to evaluate nodules >8mm (95% sensitivity) Standardized uptake values (SUV) > 2.0-2.5 False negative Bronchoalveolar Carcinoma Carcinoid False positive Granulomatous diseases Coccidiomycosis, histoplasmosis, aspergillus Tuberculosis Acute infections Sarcoidosis

Radiology 2005, Vol 237 pg. 395 Guidelines for Management of Small nodules on CT: 

Radiology 2005, Vol 237 pg. 395 Guidelines for Management of Small nodules on CT

Slide 82: 

Semi-solid or ground glass focal lesions are concerning and need further workup/follow up.

Slide 83: 

THE END

Slide 85: 

Chart shows the system for staging of sarcoidosis on the basis of chest radiographic findings. Criado E et al. Radiographics 2010;30:1567-1586 ©2010 by Radiological Society of North America