Differentiation between completely hyalinized uterine leiomyomas and ordinary leiomyomas: Three-phase dynamic magnetic resonance imaging (MRI) vs. diffusion-weighted MRI with very small b-factors

Purpose To assess the possibility of differentiating between completely hyalinized leiomyomas and ordinary leiomyomas by using diffusion‐weighted (DW) magnetic resonance imaging (MRI) (DWI) employing very small b‐factors (b = 1.51 and 55.3 seconds/mm2) in comparison with three‐phase dynamic MRI. Materials and Methods The subjects were 25 patients with 52 histopathologically confirmed uterine leiomyomas. All leiomyomas were divided into two histopathologic subtypes (5 completely hyalinized leiomyomas and 47 ordinary leiomyomas). For each leiomyoma, the enhancement index (EI) at three‐phase dynamic MRI and apparent diffusion coefficient (ADC) were obtained and then compared. Results The EIs at second and third dynamic phases clearly differentiated the two types of leiomyomas without overlap of values. ADCs also clearly differentiated the two types of leiomyomas without overlap of values. Moreover, there were significant positive correlations between ADCs and EIs at all dynamic phases (r = 0.41–0.50, P < 0.01). Conclusion Not only three‐phase dynamic MRI but also DWI with very small b‐factors could be useful for differentiating completely hyalinized leiomyomas from ordinary leiomyomas. J. Magn. Reson. Imaging 2004;20:97–104. © 2004 Wiley‐Liss, Inc.