Preoperative assessment of parotid masses: A comparative evaluation of radiologic techniques to histopathologic diagnosis

Abstract

A double-blind, retrospective analysis of 110 sequentially operated parotid masses compared the usefulness of preoperative radiologic evaluation to histopathologic diagnosis. The radiologic assessment included 25 sialograms, 162 computed tomography scans, and 10 nuclear magnetic resonance images. The diagnosis is influenced by the following four parameters of computed tomography: tumor borders, density, homogeneity, and enhancement. Well-defined borders, a homogeneous appearance, and high density strongly favor the diagnosis of a benign tumor or a low-grade malignancy (96.7%). Ill-defined tumor borders, heterogeneity, and high density indicate mainly a high-grade or recurrent malignancy (68.8%). Ill-defined borders, a heterogeneous appearance, and mixed density identify a lymphoepithelial lesion, lymphangioma, or sialoadenitis (100%). Sialography is cost effective in the evaluation of lymphoepithelial lesions. Computed tomography sialography offers no advantages over computed tomography with intravenous contrast. High-resolution computed tomography with intravenous contrast is highly sensitive for tumor detection (97%). Magnetic resonance imaging is complementary or superior to computed tomography (100%).

Measurement of the Neutron Lifetime Using a Proton Trap

“…[5] [7] [8] [9] present work [6] beam UCN bottle Storage ring al., and is described in greater detail in previous publications [10]. A proton trap of length L intercepts the entire width of the neutron beam.…”