Helical CT Diagnosis of PTE

Bill Lee

Pulmonary Thromboembolism: Spectrum of Findings on CT

Creaves S, et. al.American Journal of Roentgenology

1995;165:1359-1363

PTE

• Filling defect in pulm. art. post-contrast • Widenening, blunting, abrupt termination of

arteries • Lung parenchyma distal to thrombus may be

oligemic (decrease in vessel number or caliber +/- decrease in pulm. attenuation)

• Thrombosis of multiple small pulm aa. – patchy decrease in attenuation (“mosaic oligemia”)

PTE

• Pulmonary infarcts – triangular to polyhedral focal region of increased parenchymal attenuation distal to thrombus

• “Vascular sign” – thickened or thrombosed vessel leading to apex of infarct

• Pleural effusion – often hemorrhagic, likely secondary to pulm. necrosis

“Mosaic oligemia” Pulmonary Infarct

Vascular sign (w/PTE) and infarct PTE and pleural fluid

PTE

• False + and false – from insufficient pulmonary artery contrast enhancement

• False + from confusing adjacent lymph nodes with art. thrombi

“Pseudothrombus” = right hilar lymphadenopathy (arrowhead), PTE in left descending pulmonary art. (arrow)

“Pseudothrombus”• Streamlining

0 Sec Post 30 Sec Post

NCSU Cases

• 10y, MC Silky Terrier• Hepatocarcinoma• Met Check• Normal thorax• link

NCSU Cases

• Adjust window and level– Lung parenchyma (W≈1500, L≈-500)– PTE (W≈500, L≈0)

• Review transverse, sagittal and dorsal plane images

• Review different post-contrast times– Often good pulm. art. opacification at ≈ 1 min.

• 1mm images best for small lesions

NCSU Cases

• 8 Y, MC, Border Collie• Increased resp. rate• Exercise intolerance• Hypoxemia• Transverse , 75 sec post

NCSU Cases

• 10 y, MC Beagle• Suspect glucagonoma• Previous heartworm dz possible• Dorsal

NCSU Cases

• 8y, FS, Golden Retriever• Adrenal mass• Hyperadrenocorticism• Dorsal

CT Angiography for Diagnosis of Pulmonary Embolism: State of the Art

Schoepf U, et. al.Radiology, 2004;230:329-337

• Surpassed scintigraphy as first-line imaging test for PTE

• Many advantages of CT over other imaging– med. and parenchymal struct. can be evaluated– thrombus can be directly visualized– interobserver agreement for CT better than scint.– more cost-effective than algorithms that do not

include CT

• Historical limitation of this modality - detection of small peripheral emboli (single–detector row CT)

• Multislice helical CT= increased speed, decreased motion artifact (entire thorax in single breath hold), increased spatial resolution, isotropic voxels & 3D reformatting

• = improved detection of small peripheral emboli

16 slice CT – thrombus in small peripheral vessel w/ associated infarct

16 slice CT, volume rendered image

16 slice CT, 0.75 mm slices, volume rendered image

16 slice CT, 0.75 mm slices, volume rendered image

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