Dual-and Multi-Energy CT: Principles, Technical Approaches, And Clinical Applications

Dual energy CT,also known as spectral CT, is a computed tomography technique that uses two separate x-ray photon energy spectra, allowing the interrogation of materials that have
different attenuation properties at different energies.One source-based approach for dual- energy imaging is through implementation of a dual-source system, in which two independent
source-detector pairs are mounted to the same gantry at about a 90° offset. While one X-ray tube operates at a low tube potential, the other tube operates at a high tube potential (e.g., 70 kV vs. 120 kV). This scanner design has several notable advantages for dual-energy imaging.In general, unenhanced images can be avoided by using DECT for body and neurological applications; iodine can be removed from the image, and a virtual, non-contrast (water) image can be obtained. Neuroradiological applications allow for the removal of bone and calcium from the carotid and brain CT angiography. Thorax applications include perfusion imaging in patients with pulmonary thromboemboli and other chest diseases, xenon ventilation-perfusion imaging and solitary nodule characterization. Cardiac applications include dual-energy cardiac perfusion, viability and cardiac iron detection. Abdominal applications include the detection and characterization of liver and pancreas masses, the diagnosis of steatosis and iron overload, DECT colonoscopy and CT cholangiography. Urinary system applications are urinary calculi characterization (uric acid vs. non-uric acid), renal cyst characterization and mass characterization. Musculoskeletal applications permit the differentiation of gout from pseudogout and a reduction of metal artifacts. Recent introduction of iterative reconstruction techniques can increase the use of DECT techniques DECT is a promising technique with potential clinical applications.