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

Abstract

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 (K_trans), rate constant (K_ep), extravascular extracellular space volume fraction (V_e) and initial area under the curve (_iAUC). DWI signal intensity and apparent diffusion coefficient (ADC) values were evaluated.

Results: E_peak, WIR, K_trans , K_ep 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: K_trans ≤0.135 min^-1, K_ep ≤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.

Keywords: DCE-MRI; Ktrans; Leydig cell tumours; Seminomas; Testicular tumours.