Читать книгу Salivary Gland Pathology - Группа авторов - Страница 59

Newer CT techniques including CT perfusion and dynamic contrast‐enhanced multi‐slice CT have been studied. Dynamic multi‐slice contrast‐enhanced CT is obtained while scanning over a region of interest and simultaneously administering IV contrast. The characteristics of tissues can then be studied as the contrast bolus arrives at the lesion and “washes in” to the tumor, reaches a peak presence within the mass, and then decreases over time, i.e. “washes out.” This technique has demonstrated differences in various histologic types of tumors, for example, with early enhancement in Warthin's tumor with a time to peak at 30 seconds and subsequent fast washout. The malignant tumors show a time to peak at 90 seconds. The pleomorphic adenomas demonstrate a continued rise in enhancement in all four phases (Yerli et al. 2007).

CT perfusion attempts to study physiologic parameters of blood volume, blood flow, mean transit time, and capillary permeability surface product. Statistically significant differences between malignant and benign tumors have been demonstrated with the mean transit time measurement. A rapid mean transit time of less than 3.5 seconds is seen with most malignant tumors, but with benign tumors or normal tissue the mean transit time is significantly longer (Rumboldt et al. 2005).