Naveen Kulkarni MD, Presenter: Nothing to Disclose

Gaurav Shyam Desai MBBS, Abstract Co-Author: Nothing to Disclose

Mukta Joshi, Abstract Co-Author: Employee, General Electric Company, Chalfont St Giles, United Kingdom

Michelle Doyle RT, Abstract Co-Author: Nothing to Disclose

Joanne Stella, Abstract Co-Author: Nothing to Disclose

Dushyant V. Sahani MD, Abstract Co-Author: Grant, General Electric Company

Sanjeeva P. Kalva MD, Abstract Co-Author: Research grant, AngioDynamics, Inc

To study the impact of dual-energy indirect CT Venography (DE-CTV) from projection based single source dual energy CT (SS DECT) in the assessment of lower limb deep venous thrombosis (DVT) using 50keV and 70keV monochromatic images.

In an IRB-approved study, 41 patients (F:M, 23:18; age range: 38 to 82 years) suspected of pulmonary embolism underwent DE-CTV from the acetabulum to the popliteal fossa on a 64-detector SS-DECT scanner (CT 750 HD scanner, GE) as a part of CT pulmonary angiography at 3 min following contrast material injection. The scan mode was Gemstone Spectral Imaging with medium body at 0.8s rotation, helical mode, rapid kVp switching between 80 and 140 in < 0.5 msec, pitch of 1.375:1 and 5mm reconstructed slice thickness. From the DE acquisition, 50keV and 70keV image data sets were generated. Two radiologists evaluated each data set for subjective vessel contrast, image quality(5-excellent; 1-poor), image noise(scale 1-3), and diagnostic confidence(scale 1-5) in diagnosing DVT(5-excellent; 1-uninterpretable). Attenuation[HU numbers] and objective noise were measured in bilateral common femoral and popliteal veins. Data were analyzed using Student t-test and Wilcoxon rank sum test. Radiation doses were compared between standard single energy and DE-CTV protocols.  

In the study cohort 5/41(12.9%) were diagnosed with DVT. The image quality of 50keV and 70 keV images were comparable(4.63vs4.95;p>0.05). At 50 keV, a 90% increase in intravascular CT attenuation within the deep veins(205.5±42.06 HU at 50keV and 107.9±6.65 HU at 70 keV) and 64% increase in objective noise(16.97HU at 50keV and 6.65HU at 70keV) was noted. The CNR was better at 50keV(9.69±5.07) than at 70keV (6.0±3.05)[p-0.0001]. There was significant improvement in the subjective contrast opacification(4.63vs3.66) and diagnostic confidence(4.82vs3.90;P<0.05) for diagnosing DVT with 50keV as compared to the 70keV images. The effective radiation dose increased by 34.8% with DE-CTV(11.29mSv) compared to the standard single energy CTV (7.13mSv) protocols.

DE-CTV provides significantly higher venous attenuation and increases the diagnostic confidence in the diagnosis of DVT at 50keV monochromatic images.

The higher attenuation within the deep veins with DE-CTV will decrease the suboptimal CTV studies and DE-CTV will improve the diagnostic confidence in the diagnosis of DVT.

Kulkarni, N, Desai, G, Joshi, M, Doyle, M, Stella, J, Sahani, D, Kalva, S, To Study the Impact of Dual Energy Indirect CT Venography (DE-CTV) from Projection-based Single Source Dual Energy CT (SS DECT) in the Assessment of Lower Limb Deep Venous Thrombosis (DVT) Using 50keV and 70keV Monochromatic Images.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9005824.html