双能CT的临床应用课件.ppt

Dual-energy CT revisited with multidetector CT: review of principlesand clinical applications Mu?turay Kar?aalt?ncaba, Aykut Akta? ? Turkish Society of Radiology 2010 Fig. 1. a, b. Axial DECT images acquired at the level of the pulmonary artery demonstrate the relationship between a Hounsfield unit measurement and kVp. Region of interest (ROI) measurements of the aorta on 140 and 80-kVp images yielded 312 H and 595 H, respectively. The iodine contrast density in the image was almost double that of the 80-kVp image. Fig. 11. a–f. DECT colonoscopy iodine (a, c, e) and virtual non-contrast (b, d, f) images acquired by dual-source CT (a, b) and gemstone spectral imaging (c–f) show the absence of a polipoid lesion. Note the lack of FOV restriction on the images obtained by fast kVp switching (c–f). The iodine DECT colonoscopy image (e) shows an absence of fluid enhancement in the right colon segments. Fig. 12. a–d. Coronal DECT images obtained by dual-source CT. A contrast enhancement in the septa of the left renal cystic lesion is evident on the iodine map (a). Note the absence of calcification on the virtual noncontrast image (b). An enhancement of the solid renal mass in the left lower pole is clearer on the iodine map (c) in comparison to the virtual non-contrast image (d). Fig. 14. a–d. Axial water (a), gray-scale iodine (b) and colored iodine (c) (70 keV) DECT images obtained by fast kVp switching show a left ovarian mass. Spectral curves (d) for the solid (red) and cystic (pink) parts of the ovarian tumor are evident. Limitations of dual-energy MDCT The major limitations of DECT are restrictions of the field of view (with dual-source CT), high radiation dose, noise in the 80-kVp images and the evaluation of patients with a high BMI. An increased radiation dose can be justified when unenhanced CT images are eliminated from the CT protocols. The use of iterative reconstruction techniques can facilitate the wider use of DECT applications by decreasing the no