Dual Energy CT imaging of Chronic Pulmonary Embolism

SOMATOM Definition Dual Energy Scanning

Hiroaki Tanaka MD*, Masaya Yamamoto MD*, Hideyuki Saeki MD**, Taizo Morita*, Tadashi Asami*, Terue Murakami* |  2009-04-21

*Department of Radiology, Saiseikai Matsuyama Hospital, Matsuyama, Japan
**Department of Cardiovascular Internal Medicine, Saiseikai Matsuyama Hospital, Matsuyama, Japan



A 70 year-old female on dialysis treatment for chronic renal failure noticed herself becoming increasingly breathless on exertion. She was referred to our department for a chest x-ray and a chest CT. Hilar enlargement was seen on the chest plain film and a mosaic perfusion pattern was seen on the chest CT images suggesting chronic pulmonary embolism. The patient was then referred for a contrast enhanced Dual Energy CT scan to evaluate the perfused blood volume (PBV) with Dual Energy Lung PBV and for a lung perfusion scintigraphy examination with 99mTc-MAA.




On the Dual Energy CT images, mural thrombi were noted in the main pulmonary artery trunk as well as in peripheral vessels. The dual energy lung PBV images revealed perfusion defects in lung areas matching the location of the thrombi. The lung perfusion defects found on lung perfusion scintigraphy corresponded well with those found on the Dual Energy Lung PBV images.



With Dual Energy CT Lung PBV post-processing, contrast enhanced CT and perfused blood volume imaging can be combined. The simultaneous visualization of thrombi as well as lung perfusion defects is expected to improve the diagnostic accuracy of pulmonary embolism. Structural and functional evaluation of the lung may be performed in one single scan which has the potential to reduce dose to the patient.


Examination Protocol (Dual Energy Lung PBV)

Scanner SOMATOM Definition
Scan area Thorax
Scan length 369 mm
Scan time and delay 12 s and 20 s
Scan direction Cranio-Caudal
kV 140 kV / 80 kV
Effective mAs 56 mAs / 291 mAs
Rotation time 0.33 s
Slice collimation 0.6 mm
Reconstructed slice thickness 1.5 mm
Increment 1 mm
Kernel D30f
CTDI 11.57 mGy
Volume 100 ml of 300 mgI/ml
Flow Rate 3 ml/sec

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