Multiparametric magnetic resonance imaging for the differentiation between benign and malignant salivary gland tumors

Abstract

To evaluate the stepwise approach in differentiating between benign and malignant salivary gland tumors using time-intensity curves (TICs) and apparent diffusion coefficients (ADCs). TICs and ADCs were analyzed on the tumor-by-tumor (overall) and pixel-by-pixel (TIC and ADC maps) bases in patients with benign (n = 52) or malignant (n = 18) salivary gland tumor. TICs were categorized into Types 1 (<20% increment ratio), 2 (>or=20% increment ratio and >120 sec peak time), 3 (>or=20% increment ratio, <or=120 sec peak time, and <30% washout ratio), or 4 (>or=20% increment ratio, <or=120 sec peak time, and >or=30% washout ratio). ADCs were classified as extremely low (<0.6 x 10(-3) mm(2)/sec), low (<1.2), intermediate (<1.8), or high (>or=1.8). Malignant tumors had small (<30%) areas with Type 1 TIC with one of the following magnetic resonance imaging (MRI) characteristics: Type 3 overall TIC patterns, Type 4 overall TIC patterns and extremely low (<0.60 x 10(-3) mm(2)/sec) overall ADCs, or Type 2 overall TIC patterns and large (>40%) areas with low or extremely low ADCs. We propose a stepwise approach by using multiparametric MRI techniques as an effective tool for differentiating between benign and malignant salivary gland tumors.