Diffusion-weighted imaging (DWI) of adenomyosis and fibroids of the uterus.

Objective: Although magnetic resonance imaging is often able to distinguish between adenomyosis and fibroids, occasionally the imaging features of focal adenomyosis and fibroids overlap. Diffusion-weighted imaging (DWI) may provide useful information in differentiating pathologies. Therefore, the purpose of our study was to evaluate differences, if any, in the apparent diffusion coefficient (ADC) values of fibroids and adenomyosis.

Methods: Patients (n = 50) with uterine fibroids and adenomyosis (n = 43), who underwent pelvic MR imaging including DWI, were included in this IRB approved HIPPA compliant retrospective study. DWI was performed with b factors of 50, 400, and 800 s/mm using a 1.5 T scanner. ADC ROI measurements were placed over a fibroid, an area of adenomyosis, unaffected normal myometrium, skeletal muscle, and urine. Histogram analysis of ADC maps in 20 cases each of adenomyosis and fibroids was evaluated to assess the degree of tissue heterogeneity.

Results: The ADC values of adenomyosis and fibroids were compared using Student's t test. The mean and the standard deviation of the ADC values of the control group were as follows: fibroid 0.64 ± 0.29, adenomyosis 0.86 ± 0.30, myometrium 1.39 ± 0.36, and urine 3.01 ± 0.2 × 10(-3) mm(2)/s. There was a statistically significant difference among the ADC values of normal myometrium and fibroids (p < 0.0001), normal myometrium and adenomyosis (p < 0.0001), and fibroids and adenomyosis (p < 0.001). Histogram analysis demonstrates less heterogeneity of adenomyosis as compared to fibroids.

Conclusions: The present study shows that ADC measurements have the potential to quantitatively differentiate between fibroids and adenomyosis.