CT of the ChestCT of the Chest
Dorith Shaham, M.D.
Department of Radiology
Hadassah Medical Center
Indications for Chest CTIndications for Chest CT
• To evaluate abnormalities shown on CXR
• To demonstrate or exclude a suspected CXR abnormality
• To demonstrate an abnormality in a patient with a normal CXR
Types of Chest CTTypes of Chest CT
• Standard chest CT– Without IV contrast– With IV contrast
• CT-angiography– PCTA (r/o PE)– Coronary CTA
• HRCT• CT-guided intervention
– Biopsy– Pleural drainage
• Low-dose CT
IV contrastIV contrast
• Not used for pulmonary parenchimal abnormalities– Inherent high contrast
• Always used for CT-angiography• May be used for evaluation of
– Mediastinum – Hilum– Pleura
Metastatic Lung Ca Metastatic Lung Ca (Adenocarcinoma)(Adenocarcinoma)
Rt. Hilar mass and small pleural effusionRt. Hilar mass and small pleural effusion
Without IV contrast
Anterior Mediastinal Mass : Anterior Mediastinal Mass : Germ cell tumorGerm cell tumor
Without IV contrast With IV contrast
Chest CT Chest CT with IV contrastwith IV contrast
SVC syndrome
ThrombusVenous collaterals
CT-AngiographyCT-Angiography
Pulmonary Embolism:Pulmonary Embolism:Imaging ModalitiesImaging Modalities
• Chest X-ray
• V/Q scan
• Computed tomographyComputed tomography– Helical (spiral) CTHelical (spiral) CT
• MRI
• Pulmonary angiography: the “gold standard”
69- year old female with 69- year old female with shortness of breathshortness of breath
Ventilation-perfusion (V/Q) scanVentilation-perfusion (V/Q) scan
• Perfusion scan: distribution of blood flow– Macroaggregated human serum albumin (10-100
micron) labeled with Tc-99m
• Ventilation scan: distribution of alveolar ventilation– Radioactive inert gas: X-133
• V/Q mismatchV/Q mismatch: abnormal perfusion and normal ventilation
Interpretation of V/Q scanningInterpretation of V/Q scanning
• Probability stratification approach (based on the assumption that the only reason for performing a V/Q scan is to diagnose PE):– High probability– Intermediate probability/ indeterminate– Low probability– Normal
Prospective Investigation of Pulmonary Prospective Investigation of Pulmonary Embolism DiagnosisEmbolism Diagnosis (PIOPED) (PIOPED)
• Multi-institutional study conducted in the mid-80’s,
• Purpose: to determine the sensitivity and specificity of V/Q scan compared with pulmonary angiogram
• 933 patients with suspected PE – 931 had V/Q scan
– 755 had pulmonary angiography
• Study patients were followed clinically for 1 Y
PIOPED STUDYPIOPED STUDY
• High sensitivity of V/Q scan:
98% of patients with PE had abnormal scans (low, intermediate or high probability)
• Low specificity: 10%
• Non-diagnostic V/Q scans: 72%
CTPACTPA
• Direct visualization of clot
• Imaging of associated findings– Pulmonary infarction– Pleural effusion
• Imaging of alternative diagnosis
Pulmonary EmbolismPulmonary Embolism
Pulmonary Embolism Pulmonary Embolism with Infarctionwith Infarction
Atelectasis
Infarction
Pulmonary EmbolismPulmonary Embolism
Combined PCTA/CTVCombined PCTA/CTV
• No additional contrast injection
• Rapid examination
• Imaging of portions of the deep venous system that are inadequately imaged by Duplex (pelvic veins, adductor canal)
HL: Massive PE
HL: Bilateral DVT
PIOPED IIPIOPED II
• To determine the sensitivity, specificity, positive/negative predictive value of spiral CT for the diagnosis of PE.
• Reference for PE: various combinations of– V/P scan– Venous U/S– Pulmonary angiography– Contrast venography
PIOPED IIPIOPED II
• 824 patients with suspected PE
• CTPA alone:– Sensitivity: 83%– Specificity: 96%– PPV: 96% (concordant high/low clinical probability),
92% (intermediate clinical probability)
PIOPED IIPIOPED II
• Combined CTPA + CTV:– Sensitivity: 90%– Specificity: 95%
• Additional testing is necessary when clinical probability is inconsistent with imaging results
N Engl J Med 2006;354:2317-27
15-year old male with chest pain15-year old male with chest pain
Intramural hematoma
Pericardial effusion
Small right pleural effusion
Collateral blood flow
Coarctation of the aorta with enlarged internal mammary arteries
CT Coronary AngiographyCT Coronary Angiography
High Resolution CT (HRCT)High Resolution CT (HRCT)
HRCT: HRCT: TechniqueTechnique
• Narrow slice width
• “Bone” reconstruction algorithm
• Small field of view
HRCT: Ground glass opacityHRCT: Ground glass opacity
HRCTChest CT
HRCT: scanning protocolsHRCT: scanning protocols
• 1-mm slices every 10-mm/ Contiguous 1-mm slices
• Supine/ Prone
• Full inspiration/ Expiration
HRCT: patterns of lung diseaseHRCT: patterns of lung disease
• Reticular and short linear
• Nodular
• Increased lung opacity (“ground glass”)
• Decreased lung density– Cysts– Emphysema– Bronchiectasis
CT vs. HRCTCT vs. HRCT
Multiple tiny perilymphatic nodulesSarcoidosis
HRCT: BronchiectasisHRCT: Bronchiectasis
CT-guided Needle BiopsyCT-guided Needle Biopsy
IndicationsIndications
• Evaluation of – Solitary pulmonary nodule– Multiple pulmonary nodules– Mediastinal/hilar masses/lymphadenopathy– Chest wall masses
• Retrieval of organisms from infectious lung lesions
• Staging of tumors (lung cancer, extrathoracic)
ContraindicationsContraindications
• An uncooperative patient
• Bleeding diathesis– INR>1.3– Platelet count<50,000 mm3
• Severe underlying lung disease– emphysema
• Intractable cough
Image GuidanceImage Guidance
• CT• Fluoroscopy
– visualization in 2 projections
• Ultrasound– chest wall– pleura– anterior mediastinum– lung periphery
Advantages of CT-guided BiopsyAdvantages of CT-guided Biopsy
• Needle path that avoids– aerated lung– fissures– large vessels– bullae– vital cardiovascular structures
• Differentiation of necrotic vs. viable portions of tumor– I.V. contrast
Biopsy NeedlesBiopsy Needles::Westcott and TurnerWestcott and Turner
Biopsy Needles:Biopsy Needles: Cutting Spring-AcivatedCutting Spring-Acivated
Lung Biopsy: SPNLung Biopsy: SPN(Squamous cell ca.)(Squamous cell ca.)
Lung Biopsy: Lung Biopsy: Multiple nodulesMultiple nodules((Alveolar soft part sarcoma)Alveolar soft part sarcoma)
Rib Biopsy: Multiple myelomaRib Biopsy: Multiple myeloma
Cytologic SpecimenCytologic Specimen
CT-guided biopsy: ComplicationsCT-guided biopsy: Complications
• Pneumothorax
• Hemorrhage
Drainage of Intrathoracic Drainage of Intrathoracic CollectionsCollections
IndicationsIndications
• Malignant pleural effusion
• Empyema/ parapneumonic effusions
• Lung abscess
Contraindications (relative) Contraindications (relative)
• Clotting deficiency– INR < 1.5– Thrombocytopenia (< 50,000 cells/ml)– Anticoagulation therapy
Catheter PlacementCatheter Placement
• One step (trocar)
• Seldinger technique
Drainage Catheters: Drainage Catheters: One Step
Drainage CathetersDrainage Catheters: Seldinger technique
Drainage of Empyema: PostpartumDrainage of Empyema: Postpartum
Low-dose CT: Lung cancer Low-dose CT: Lung cancer screeningscreening
Baseline Findings- ELCAPBaseline Findings- ELCAP
• Low dose CT greatly increases the likelihood of detection of NCN and early lung cancer compared with chest radiography– NCN:NCN: 3 times as commonly– Malignant tumors:Malignant tumors: 4 times as commonly– Stage I tumors:Stage I tumors: 6 times as commonly
Henschke et al, Lancet 1999; 354:99-105
Low-dose CTLow-dose CT
Low-dose CT: Lung cancerLow-dose CT: Lung cancer
Low-dose CT and HRCTLow-dose CT and HRCT
1 year later
HRCT 3 months later: HRCT 3 months later: Lung cancerLung cancer
I-ELCAP results I-ELCAP results ((N Engl J Med 2006;355:1763-71)N Engl J Med 2006;355:1763-71)
• 31,567 asymptomatic persons at risk for lung cancer screened using low-dose CT (1993-2005)
• Stage I lung cancer diagnosed in 412/484 (85%)
• 10-year survival in stage I lung cancer– Overall: 88%– Surgical resection in 1 month: 92%
National Lung Screening Trial (NLST)National Lung Screening Trial (NLST) ( (N Engl J Med 2011;365:395-409)N Engl J Med 2011;365:395-409)
• Started in 2002• >53,000 current and former heavy smokers, ages 55
to 74• compared the effects of two screening procedures for
lung cancer – – low-dose helical computed tomography (CT) – standard chest X-ray
• 20% fewer lung cancer deaths among trial participants screened with low-dose helical CT– Lung cancer deaths in CT-screened: 354, in CXR
screened: 442 (p=0.0041)