Clinical study
Indirect Computed Tomography Venography of the Lower Extremities Using Single-Source Dual-Energy Computed Tomography: Advantage of Low-Kiloelectron Volt Monochromatic Images

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Abstract

Purpose

To study the performance of dual-energy indirect computed tomography (CT) venography from single-source dual-energy CT in the assessment of lower extremity deep venous thrombosis (DVT).

Materials and Methods

In a retrospective study, 110 patients suspected to have pulmonary embolism (PE) underwent dual-energy CT venography on a single-source dual-energy CT scanner as a part of CT pulmonary angiography protocol at 3 minutes after injection of contrast material. Two radiologists evaluated 50-kiloelectron volt (keV) and 70-keV monochromatic images reconstructed from a dual-energy CT scan for image quality, image noise, venous contrast, and confidence level in interpretation for DVT using a scale of 1–5. In addition, a combined 50-keV and 70-keV data set was assessed for confidence level in image interpretation. Attenuation, contrast-to-noise ratio (CNR), 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 dose was measured for dual-energy CT venography protocol.

Results

A diagnosis of DVT was made in 8 of 110 patients (7.27%). The subjective image quality was comparable between 50-keV and 70-keV images (4.3 vs 4.5; P > .05). The subjective venous contrast opacification (4.7 vs 3.5; P = .0036) and confidence (4.8 vs 3.9; P = .0028) in image interpretation were superior at 50 keV. Confidence level for interpretation on combined 50-keV and 70-keV series (score 4.7) was similar to that for 50-keV series (score 4.8). Compared with 70-keV data, 50-keV data yielded 90% increase in intravascular CT attenuation (207.4 Hounsfield units [HU] ± 39.0 vs 106.8 HU ±7.6; P <.0001) and higher CNR (10.7 ± 4.07 vs 7.2 ± 4.1; P = .0001) of the deep veins. However, objective noise at 50 keV was higher (14.8 HU vs 6.5 HU; P = .0031). Because of inadequate contrast opacification, 6% of CT venography studies were deemed suboptimal for rendering a diagnostic interpretation on 70-keV images, but these images were considered acceptable at 50 keV. The mean effective radiation dose for the dual-energy CT venography examination was 4.2 mSv.

Conclusions

Optimal image quality with substantially higher venous attenuation is provided by 50-keV monochromatic images from dual-energy CT venography acquisition compared with 70-keV images. The 50-keV monochromatic images increase the confidence in the image interpretation of DVT and decrease the number of indeterminate studies.

Section snippets

Study Design

This retrospective study was approved by the institutional review board, and the requirement to obtain an informed consent was waived. The study was performed in patients referred for suspected PE based on moderate to high clinical probability. From December 2009 to August 2010, 110 patients underwent combined CT pulmonary angiography and dual-energy CT venography. Patients with known allergy to iodinated contrast material, pregnant women, and patients with impaired renal function (estimated

DVT and PE

In the study cohort of 110 patients (56 men and 54 women; mean age, 66 y [range, 34−89 y];, mean weight, 83.86 kg [range, 73–113 kg]), 23 patients (20.90%) had VTE detected on dual-energy CT venography or CT pulmonary angiography. Of patients, 19 (17.27%) had PE, and 4 of these also had DVT. Frequency of DVT in patients with PE was 21.05%. Eight (7.27%) patients had DVT; four of these also had PE. Frequency of PE in patients with DVT was 50%. With the addition of CT venography to CT pulmonary

Discussion

Incorporating CT venography into a CT pulmonary angiography protocol allows detection of PE and DVT of the pelvis and lower extremities in a single examination. It requires only 2–3 minutes of additional time, obviating an additional contrast injection and delay in provision of results (8, 10, 11). CT venography has been shown to have similar performance as that of lower extremity ultrasound for detecting DVT, and many institutions worldwide at the present time use protocols with CT venography

References (40)

  • P.A. Loud et al.

    Deep venous thrombosis with suspected pulmonary embolism: detection with combined CT venography and pulmonary angiography

    Radiology

    (2001)
  • E.E. Coche et al.

    Using dual-detector helical CT angiography to detect deep venous thrombosis in patients with suspicion of pulmonary embolism: diagnostic value and additional findings

    AJR Am J Roentgenol

    (2001)
  • M.D. Cham et al.

    Deep venous thrombosis: detection by using indirect CT venographyThe Pulmonary Angiography-Indirect CT Venography Cooperative Group

    Radiology

    (2000)
  • D.F. Yankelevitz et al.

    Optimization of combined CT pulmonary angiography with lower extremity CT venography

    AJR Am J Roentgenol

    (2000)
  • B. Ghaye et al.

    Pitfalls in CT venography of lower limbs and abdominal veins

    AJR Am J Roentgenol

    (2002)
  • H. Nazaroglu et al.

    64-MDCT pulmonary angiography and CT venography in the diagnosis of thromboembolic disease

    AJR Am J Roentgenol

    (2009)
  • M.D. Cham et al.

    Thromboembolic disease detection at indirect CT venography versus CT pulmonary angiography

    Radiology

    (2005)
  • M.C. Godoy et al.

    Single-acquisition dual-energy multidetector computed tomography: analysis of vascular enhancement and postprocessing techniques for evaluating the thoracic aorta

    J Comput Assist Tomogr

    (2010)
  • B.M. Yeh et al.

    Dual-energy and low-kVp CT in the abdomen

    AJR Am J Roentgenol

    (2009)
  • S.P. Kalva et al.

    Using the K-edge to improve contrast conspicuity and to lower radiation dose with a 16-MDCT: a phantom and human study

    J Comput Assist Tomogr

    (2006)

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    D.V.S. has received grant support from GE Healthcare. None of the other authors have identified a conflict of interest.

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    Copyright © 2012 SIR. Published by Elsevier Inc. All rights reserved.