Dual energy ct in clinical practice pdf

Authors: Carlo N. De Cecco, Andrea Laghi, U. Joseph Schoepf, Felix G. The aim of this book is fourfold: to describe the basic principles of Dual Energy CT DECT imaging, to explain how post-processing is utilized, to critically appraise the strengths and weaknesses of the technique in oncologic imaging, and above all, to demonstrate the contribution of DECT in the management of. Authors: Patricia M.

Carrascosa, Ricardo C. Cury, Mario J. This is the first textbook in DECT focussing especially on the cardiovascular field. DECT was developed many years ago but has recently spread its clinical utility. Many new applications have been developed over the last years and the cardiovascular system has benefited from these advances. New protocols will be used. Dual-energy CT is a novel, rapidly emerging imaging technique which offers important new functional and specific information.

With implementation of the technology in commercially available scanners, many clinical applications are now feasible. In this book, physicists and specialists from different CT manufacturers provide an insight into the technological basis of, and the different approaches to, dual-energy CT. Renowned medical scientists in the field explain the pathophysiological and molecular background of the technique, discuss its applications, provide detailed advice on how to obtain optimal results, and offer hints regarding clinical interpretation.

The main focus is on the use of dual-energy CT in daily clinical practice, and individual sections are devoted to imaging of the vascular system, the thorax, the abdomen, and the extremities.

Evaluations and recommendations are based on personal experience and peer-reviewed literature. Plenty of carefully chosen high-quality images are included to illustrate the clinical benefits of the technique.

The editors intend the book for technicians and radiologists. It is well organized and well suited for clinical physicists and research scientists …. There is no direct competition for this book …. For anyone with anorak tendencies or an interest in the future of CT, I would recommend they seek out a copy …. It provides the reader with a sufficient and comprehensive physical and technical background.

Matthias Kerl, Radiology, Vol. Skip to main content Skip to table of contents. Advertisement Hide. This service is more advanced with JavaScript available. Motion-related, beam-hardening, and partial averaging artifacts; image noise; and low serum uric acid levels have been attributed to these discrepant findings, and therefore, large-scale clinical studies with adequate pathologic correlates are needed To avoid missing or misinterpreting small urinary stones subjacent to ureteral stents in patients with urolithiasis, radiologists should note that silicone stents appear red similar to urate stones and polyurethane stents appear blue similar to nonurate stones with default settings on both dual-source DECT and split-filter DECT images Acquisition of VUE images can preclude acquisition of TUE images, thus reducing the radiation dose and improving workflow Incomplete iodine removal is most commonly observed when the iodine concentration is very high Frequent examples include a residual iodine in arteries or portal veins on arterial phase VUE CT images Fig 23 ; b iodinated contrast media in the renal collecting system on delayed or excretory phase VUE CT images Fig 24 ; c incomplete subtraction of a high-concentration, high-attenuating contrast media bolus in the subclavian veins Fig 25 , superior vena cava, or right atrium; and d inhomogeneous subtraction of high-attenuating enteric contrast media.

This phenomenon can be explained as the saturation effect, in which attenuation values of a highly concentrated iodine column reach close to the maximum attenuation values on the Hounsfield scale, minimizing the difference in attenuation between low- and high-kVp CT images. As a result, iodine with saturated attenuation values is categorized as noniodine and is still displayed. Streaks from the high-attenuating iodinated contrast media bolus can also impair assessment of pulmonary perfusion and can lead to a false-positive or false-negative result Lipiodol is a drug delivery vehicle that is commonly used in transarterial chemoembolization procedures.

It is an iodized poppy seed oil mg of iodine per milliliter that preferentially accumulates in treated hepatocellular carcinomas and correlates with treatment response and recurrence. The lack of visualization of lipiodol at VUE CT is not an artifact, because iodine is rightfully being removed from the image. However, the concentration of lipiodol varies widely after transarterial chemoembolization, so that lower concentrations of lipiodol can be removed at VUE CT, while it remains in areas with higher concentrations This heterogeneous subtraction of lipiodol may hinder the use of VUE CT images for evaluation after transarterial chemoembolization Fig Lipiodol on VUE DECT images in a year-old man with hepatocellular carcinoma who was treated with transarterial chemoembolization with lipiodol.

Because lipiodol is visualized on MD iodine CT images, detection of arterially enhancing foci that suggest a recurrent or residual tumor would be hard to discern on these images. Thus, the VUE image may not be a suitable surrogate for evaluation of hepatocellular carcinoma treated with transarterial chemoembolization. This means that calcium-containing voxels are seen as hyperattenuating regions on both MD iodine and VUE CT images, and iodine-containing voxels are seen as hyperattenuating regions on MD iodine and virtual noncalcium CT images.

In clinical routine, voxels that display high attenuation on both contrast-enhanced and VUE CT images are recognized as calcium. However, when a calcific object is too small or not highly attenuating, the VUE reconstruction process can result in removal or reduced attenuation of calcium eg, small urinary stones or calcification in a tumor.

Studies 54 — 56 have demonstrated that urinary calculi smaller than 2. This can also lead to ambiguity in assessment for endoleaks in patients with a calcified intramural thrombus. Even if calcium is visualized, the reduced blooming of calcium and metallic clips Fig 27 57 , 58 on VUE CT images can affect sensitivity for detection of gallstones, urinary stones Fig 27 , and calcified parenchymal lesions or can lead to a discrepancy in the size of the stones or lesions between TUE and VUE images The integrity and placement of stents and grafts is evaluated on unenhanced images because they display high attenuation.

To our knowledge, studies have anecdotally reported this finding 60 , but the performance of VUE CT for assessment of stent integrity has not been evaluated. Removal of foreign materials on VUE images in a year-old man. Reduced attenuation of foreign materials on VUE images in a year-old man. Reliable and valid estimation of attenuation on unenhanced images is important in several clinical settings, especially for characterization of renal and adrenal lesions and evaluation of fatty liver.

This can affect characterization of lesions with borderline attenuation values. Overestimation of adrenal lesion attenuation can reduce sensitivity but not affect specificity A potential clue to assess the validity of attenuation on VUE CT images is to look for residual iodine on the images.

Quantitative challenge on VUE images in a year-old man. Virtual noncalcium CT images have been used most commonly for identification of bone marrow edema, marrow malignancy, and disk displacements. Choosing an appropriate calcium suppression index during postprocessing of dual-layer DECT images can facilitate visualization of the subcortical region At rapid kVp-switching DECT, MD water hydroxyapatite images are shown to be susceptible to scatter artifacts, because the artifactual voxels are classified as water attenuation and are thus accentuated on these images On the other hand, MD water cortical bone CT images have been shown to mitigate artifacts seen at the bone—soft-tissue interface At dual-source DECT, virtual noncalcium images are based on decomposition of voxels into yellow marrow, red marrow, and bone.

Because marrow types are the basis of material decomposition on this platform in addition to the acquisition parameters and decomposition ratio , skeletal site, age, and prior treatment with radiation can influence qualitative and quantitative interpretation because of associated changes in bone marrow composition DECT has evolved from the research realm into a widely accepted advanced CT technique for numerous clinical applications.

Although some pitfalls are common to both conventional and DECT images, the physical basis and decomposition process used to generate DECT reconstruction images introduce pitfalls to imaging interpretation and appearance that are specific to DECT with all commercially available DECT technologies. Recognizing the potential pitfalls of DECT is necessary for appropriate and accurate interpretation of the results of this increasingly important imaging tool.

K have provided disclosures; the other authors, the editor, and the reviewers have disclosed no relevant relationships. Disclosures of Conflicts of Interest. Activities related to the present article: disclosed no relevant relationships. Other activities: disclosed no relevant relationships.

Activities not related to the present article: royalties from Elsevier. Activities not related to the present article: board membership with GE Healthcare, royalties from Elsevier. National Center for Biotechnology Information , U.

January-February ; 41 1 : 98— Published online Jan 7. Yeh , MD, Frank J. Simeone , MD, Dushyant V. Sahani , MD, and Avinash R. Author information Article notes Copyright and License information Disclaimer. Corresponding author. Avinash R. Kambadakone: ude. Address correspondence to A. Abstract Dual-energy CT DECT is a tremendous innovation in CT technology that allows creation of numerous imaging datasets by enabling discrete acquisitions at more than one energy level.

Open in a separate window. Introduction Tremendous advances in the last decade have led to substantial evolution in dual-energy DECT techniques.

Kilovolt Peak Images Kilovolt peak images are reconstructed from a polychromatic acquisition and have similar characteristics to those from conventional single-energy CT. MD Images Available on all platforms, these DECT images selectively display the material in question in gray scale or with color overlay. Artifacts and Pitfalls of VMC Images Low—kiloelectron voltage imaging is used to reduce or improve image contrast or reduce the dose of contrast media, and high—kiloelectron voltage images are used to alleviate beam-hardening artifacts from metals.

Pseudoenhancement Pseudoenhancement is artifactual high attenuation observed because of a combination of beam hardening, partial volume averaging, scatter, or crosstalk. Out-of-Field Artifacts When anatomy extends beyond the maximum field of view 50 cm , out-of-field artifacts occur on polychromatic single-energy CT images. Figure 1a. Figure 1b. Figure 1c. Figure 2a. Figure 2b. Figure 2c.

Figure 3a. Figure 3b. Figure 3c. Figure 3d. Artifacts and Pitfalls of MD Images MD images highlight materials of interest that are defined by a user and are created with a material decomposition technique. Figure 4. Figure 5. Figure 6a. Figure 7a. Figure 8. Figure 6b. Figure 6c. Figure 7b. Figure 7c. Figure 9a. Figure 9b. Figure 9c. MD Iodine CT Images These are most commonly used to distinguish between enhancing and nonenhancing lesions and improve visualization of both hyper- and hypovascular masses.

Figure 10a. Figure 11a. Figure 10b. Figure 10c. Figure 10d. Figure 11b. Figure 12a. Figure 12b. Figure 13a. Figure 14a. Figure 13b. Figure 14b. Figure Figure 17a. Figure 17b. Figure 19a. Figure 19b. Figure 19c. Figure 19d. Figure 20a. Figure 20b. Figure 20c. Figure 20d. Figure 21a. Figure 21b. Figure 21c. Figure 21d. Figure 21e. MD Urate Images These images are used for evaluating the presence of monosodium urate crystals in patients with gout and for determining the composition of urinary stones to differentiate uric acid from non—uric acid stones.

Figure 22a. Figure 22b. Figure 23a. Figure 24a. Figure 25a. Figure 23b. Figure 24b. Figure 24c. Figure 24d. Figure 24e. Figure 24f. Figure 25b. Figure 26a. Figure 26b. Figure 26c. Figure 26d. Figure 27a. Figure 27b. Removal of Foreign Materials The integrity and placement of stents and grafts is evaluated on unenhanced images because they display high attenuation.

Figure 28a.