Dual-Energy CT: Spectrum of Thoracic Abnormalities

Abstract

Recent studies have demonstrated that dual-energy computed tomography (CT) can provide useful information in several chest-related clinical indications. Compared with single-energy CT, dual-energy CT of the chest is feasible with the use of a radiation-dose-neutral scanning protocol. This article highlights the different types of images that can be generated by using dual-energy CT protocols such as virtual monochromatic, virtual unenhanced (ie, water), and pulmonary blood volume (ie, iodine) images. The physical basis of dual-energy CT and material decomposition are explained. The advantages of the use of virtual low-monochromatic images include reduced volume of intravenous contrast material and improved contrast resolution of images. The use of virtual high-monochromatic images can reduce beam hardening and contrast streak artifacts. The pulmonary blood volume images can help differentiate various parenchymal abnormalities, such as infarcts, atelectasis, and pneumonias, as well as airway abnormalities. The pulmonary blood volume images allow quantitative and qualitative assessment of iodine distribution. The estimation of iodine concentration (quantitative assessment) provides objective analysis of enhancement. The advantages of virtual unenhanced images include differentiation of calcifications, talc, and enhanced thoracic structures. Dual-energy CT has applications in oncologic imaging, including diagnosis of thoracic masses, treatment planning, and assessment of response to treatment. Understanding the concept of dual-energy CT and its clinical application in the chest are the goals of this article.

Dual-Energy CT: New Horizon in Medical Imaging

“…By this method, characteristically wedge-shaped iodine-deficient lung lesions are detected, which are not apparent on conventional pulmonary CT angiography (Fig. 7) (262728). In pulmonary thromboembolism, dual-phase dual-energy PBV map can be used to differentiate between acute and chronic phases by identifying delayed systemic collateral flow at the expense of higher radiation dose (29).…”

“…Iodine map is helpful not only to distinguish a particularly hyperdense, cystic lesion or hematoma from enhancing lesion, but also to clearly delineate the extent of bowel ischemia (141825); in addition, malignant tumors may be more accurately differentiated from benign tumors based on the degree of iodine enhancement (19). Treatment response may be assessed quantitatively by measuring the iodine concentration in enhancing tumors in oncologic patients (14182831). …”

“…14) (284652). As in virtual monoenergetic imaging, further noise optimization is necessary for material decomposition images to improve their image quality in all dual-energy approaches.…”

“…12A). Workflow issues including difficulties in CT scheduling, increased reconstruction time, increased number of images, and increased interpretation time, substantially increase the radiologists' workload and hinder the use of dual-energy CT imaging in daily routine (28). …”

An attempt to evaluate intraductal components of breast cancer by dual energy computed tomography

“…Contrastenhanced SECT is mainly used to estimate the presence of metastatic tumours and regional lymphadenopathy, as an IC of breast cancer is a fine structure with attenuation similar to that of normal breast tissue and is difficult to distinguish in SECT images. Dual-Energy CT (DECT) is an advancement in CT technology, and it has been shown to have potential for the detection and characterisation of abdominal and pulmonary diseases [15][16][17][18][19][20][21][22][23]. Additionally, DECT images reconstructed at low photon energies have a high contrast enhancement effect with high resolution in soft tissues [17,22,23].…”