Virtual unenhanced second generation dual-source CT of the liver: Is it time to discard the conventional unenhanced phase?

Barrett, Tristan; Bowden, David J.; Shaida, Nadeem; Godfrey, Edmund; Taylor, Abby S.; Lomas, David J.; Shaw, Ashley

doi:10.1016/j.ejrad.2011.03.042

Cited by 49 publications

(35 citation statements)

References 19 publications

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“…Thus, materials with a high atomic number can be further differentiated from soft tissues by applying different beam energies and analyzing the differences in attenuation [8]. This principle allows clinicians to reconstruct “virtual unenhanced” images from iodine contrast-enhanced scans [9-15]. The attenuation differences of iodine between two energies can be utilized to produce an “iodine map”, which can be subsequently removed from images to create virtual unenhanced images.…”

Section: Introductionmentioning

confidence: 99%

Radiotherapy treatment planning with contrast-enhanced computed tomography: feasibility of dual-energy virtual unenhanced imaging for improved dose calculations

Yamada

Ueguchi

Ogata³

et al. 2014

Radiat Oncol

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BackgroundIn radiotherapy treatment planning, intravenous administration of an iodine-based contrast agent during computed tomography (CT) improves the accuracy of delineating target volumes. However, increased tissue attenuation resulting from the high atomic number of iodine may result in erroneous dose calculations because the contrast agent is absent during the actual procedure. The purpose of this proof-of-concept study was to present a novel framework to improve the accuracy of dose calculations using dual-energy virtual unenhanced CT in the presence of an iodine-based contrast agent.MethodsSimple phantom experiments were designed to assess the feasibility of the proposed concept. By utilizing a “second-generation” dual-source CT scanner equipped with a tin filter for improved spectral separation, four CT datasets were obtained using both a water phantom and an iodine phantom: “true unenhanced” images with attenuation values of 2 ± 11 Hounsfield Units (HU), “enhanced” images with attenuation values of 274 ± 23 HU, and two series of “virtual unenhanced” images synthesized from dual-energy scans of the iodine phantom, each with a different combination of tube voltages. Two series of virtual unenhanced images demonstrated attenuation values of 12 ± 29 HU (with 80 kVp/140 kVp) and 34 ± 10 HU (with 100 kVp/140 kVp) after removing the iodine component from the contrast-enhanced images. Dose distributions of the single photon beams calculated from the enhanced images and two series of virtual unenhanced images were compared to those from true unenhanced images as a reference.ResultsThe dose distributions obtained from both series of virtual unenhanced images were almost equivalent to that from the true unenhanced images, whereas the dose distribution obtained from the enhanced images indicated increased beam attenuation caused by the high attenuation characteristics of iodine. Compared to the reference dose distribution from the true unenhanced images, the dose distribution pass rates from both series of virtual unenhanced images were greater than 90%, while those from the enhanced images were less than approximately 50–60%.ConclusionsDual-energy virtual unenhanced CT improves the accuracy of dose distributions in radiotherapy treatment planning by removing the iodine component from contrast-enhanced images.

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Section: Introductionmentioning

confidence: 99%

Radiotherapy treatment planning with contrast-enhanced computed tomography: feasibility of dual-energy virtual unenhanced imaging for improved dose calculations

Yamada

Ueguchi

Ogata³

et al. 2014

Radiat Oncol

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“…16,18 Secondly, the present results show that there is a statistically significant difference in radiation dose between the two tubes operating at different tube potentials. This reduction in radiation dose was to be expected, but it should be considered in correlation with other results regarding image quality and diagnostic accuracy.…”

Section: Discussionmentioning

confidence: 85%

“…5,9,14 Regarding the comparison between SU and VU images, the present results confirm an excellent correlation between qualitative and quantitative assessment, in line with previous literature reports. 17,18 Although none of the VU datasets was rated as being of low quality, artefacts were present in a few cases, mostly due to misalignment of liver borders on reconstructed images due to slight motion of the organ as a result of subtle respiration and patient movement. This problem has been reported previously, 17,18 and radiologists evaluating DECT examinations should be aware and trained to recognise and interpret typical postprocessing artefacts in VU datasets in order to achieve proper image interpretation.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of image quality, radiation dose and diagnostic performance of dual-energy CT datasets in patients with hepatocellular carcinoma

Anzidei¹,

Martino²,

Sacconi³

et al. 2015

Clinical Radiology

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“…14 In comparison with the first-generation DECT, 6Y9 VU data sets from the second generation have better image quality and no significant difference between AVU and PVU series. In clinical practice, the possibility of obtaining a good quality VU data set, regardless of the acquisition phase, means a wider variety of study protocols can be used.…”

Section: Discussionmentioning

confidence: 97%

“…14 The DE arterial and portal images were acquired using the tin filter and the following parameters: detector configuration, 2 Â 40 Â 0.6 mm; pitch, 0.6; tube A voltage, 80 kV(p) and reference value, 559 mA s; and tube B voltage, 140 kV(p) and reference value, 216 mA s with online dose modulation. An acquisition of 80/140 kV(p) was used instead of the suggested 100/140 kV(p) to further reduce the total radiation dose and also to assess the impact on DE acquisition because no previous similar experiences are reported in the literature.…”

Section: Dect Protocolmentioning

confidence: 99%

Virtual Unenhanced Images of the Abdomen With Second-Generation Dual-Source Dual-Energy Computed Tomography

Cecco¹,

Darnell²,

Macías³

et al. 2013

Investigative Radiology

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1. Second-generation abdominal VU data sets yield excellent image quality but are still slightly lower than that of CU. 2. More small hypodense liver lesions were detected in VU images than in CU images; however, a significant number of small calcified lesions were not identified in VU images. 3. Second-generation abdominal VU images are still not ready to replace CU images in clinical practice. Implications for Patient Care: 1. Using VU images in abdominal studies makes it possible to reduce the total radiation dose delivered to patients who need multiphasic acquisition by avoiding precontrast scan. 2. Erroneous material subtraction and incomplete abdominal coverage represent a limit in VU data set application in clinical routine.

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Virtual unenhanced second generation dual-source CT of the liver: Is it time to discard the conventional unenhanced phase?

Cited by 49 publications

References 19 publications

Radiotherapy treatment planning with contrast-enhanced computed tomography: feasibility of dual-energy virtual unenhanced imaging for improved dose calculations

Radiotherapy treatment planning with contrast-enhanced computed tomography: feasibility of dual-energy virtual unenhanced imaging for improved dose calculations

Evaluation of image quality, radiation dose and diagnostic performance of dual-energy CT datasets in patients with hepatocellular carcinoma

Virtual Unenhanced Images of the Abdomen With Second-Generation Dual-Source Dual-Energy Computed Tomography

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