Dynamic contrast-enhanced and diffusion-weighted MR imaging in the characterisation of small, non-palpable solid testicular tumours.

OBJECTIVES: To explore the role of dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), using semiquantitative and quantitative parameters, and diffusion-weighted (DW) MRI in differentiating benign from malignant small, non-palpable solid testicular tumours.

METHODS: We calculated the following DCE-MRI parameters of 47 small, non-palpable solid testicular tumours: peak enhancement (PE), time to peak (TTP), percentage of peak enhancement (Epeak), wash-in-rate (WIR), signal enhancement ratio (SER), volume transfer constant (Ktrans ), rate constant (Kep ), extravascular extracellular space volume fraction (Ve ) and initial area under the curve (i AUC). DWI signal intensity and apparent diffusion coefficient (ADC) values were evaluated.

RESULTS: Epeak , WIR, Ktrans , Kep and iAUC were higher and TTP shorter in benign compared to malignant lesions (p < 0.05). All tumours had similar ADC values (p > 0.07). Subgroup analysis limited to the most frequent histologies - Leydig cell tumours (LCTs) and seminomas - replicated the findings of the entire set. Best diagnostic cutoff value for identification of seminomas: Ktrans ≤0.135 min-1 , Kep ≤0.45 min-1 , iAUC ≤10.96, WIR ≤1.11, Epeak ≤96.72, TTP >99 s.

CONCLUSIONS: DCE-MRI parameters are valuable in differentiating between benign and malignant small, non-palpable testicular tumours, especially when characterising LCTs and seminomas.

KEY POINTS: • DCE-MRI may be used to differentiate benign from malignant non-palpable testicular tumours. • Seminomas show lower Ktrans, Kep and iAUC values. • ADC values are not valuable in differentiating seminomas from LCTs. • Semiquantitative DCE-MRI may be used to characterise small, solid testicular tumours.