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Hình. 5. AML với chất béo không bị phát hiện. Một khối mô mềm (mũi tên) (M) IS exophytic từ các khía cạnh sau của quả thận bên phải (K). Mặc dù tìm WS này Pathologically Chứng minh để trở AML năm, chất béo không có WS phát hiện ở hình ảnh, Ngay cả trên xem xét lại quá khứ. | Cross-sectional Imaging Evaluation of Renal Masses 97 Fig. 5. AML with no detectable fat. A soft tissue mass arrow M is exophytic from the posterior aspect of the right kidney K . Although this finding was pathologically proved to be an AML no fat was detected at imaging even on retrospective review. the corticomedullary nephrographic and excretory phases with little or no respiratory or patientmotion artifacts 7 . Multiphase imaging of the kidney thus permits not only high-resolution imaging of the renal parenchyma but also that of its vasculature and collecting systems 8 . Comprehensive evaluation of renal masses by CT requires a dedicated renal CT protocol. The various phases of CT imaging of the kidney include precontrast arterial 15-25 second delay corticome-dullary 35-80 second delay nephrographic 85-180 second delay and excretory 3 minutes or more phases 7 . Preliminary noncontrast scans are used to detect calcifications and allow quantification of enhancement on the postcontrast scans. However unenhanced scans alone are inadequate for lesion characterization because no information exists regarding lesion vascularity enhancement. In addition the precontrast phase provides the lowest sensitivity for detecting renal masses. Fig. 6. Multiplanar reformation of the kidney. Isotropic scan acquisition and data reconstruction results in multiplanar image quality comparable to the source axial images. In this case of multicentric RCC the distribution of three renal masses arrows can be seen on a single coronal image. During the corticomedullary phase CMP contrast resides in the cortical capillaries peritubular cells proximal convoluted tubules and columns of Bertin 9 . Optimal time delay for the CMP phase depends on the rate of injection the amount of contrast material administered and the patient s cardiac output. Advantages of the CMP include the differentiation of normal variants of renal parenchyma from renal masses and the better depiction of tumor .
