Testicular tumors: discriminative value of conventional MRI and diffusion weighted imaging

Abstract

To explore the feasibility of using conventional MRI features combined with apparent diffusion coefficient (ADC) values for the differential diagnosis of testicular tumors.A total of 63 patients with pathologically confirmed testicular tumors were enrolled in this study. In particular, there were 46 cases of malignant lesions and 17 cases of benign lesions. All patients underwent conventional magnetic resonance imaging (MRI) and diffusion weighted imaging. Multivariate logistic regression models and receiver operating characteristic curves were constructed to assess diagnostic accuracies.T2-homogeneity, intratumoral septa, and peritumoral infiltration were more common in the malignant group, and capsule sign was more common in the benign group (P < .05 for all). The mean ADC value of the malignant group was lower than that of the benign group (P < .05). When the ADC value ≤ 0.90 × 10-3 mm2/s, the diagnosis tended to be malignancy. The conventional MRI model could achieve better diagnostic accuracy than ADC values alone (P < .05). Compared with the conventional MRI model, the specificity and accuracy of the full model (ADC and conventional MRI model) increased by 9.8% and 3.2%, respectively. T2-homogeneity and T2-hypointensity were more common in seminoma and lymphoma, cystic changes were more common in nonseminomatous germ cell tumor (NSGCT), and intratumoral septa was more common in seminoma (P < .05 for all). The ADC value of NSGCT was larger than seminoma, and lymphoma was the smallest (P < .05 for all). Cystic changes, T2-hypointensity, intratumoral septa, and ADC value were independent factors for differentiating the seminoma, NSGCT, and lymphoma subgroups.A combination of conventional MRI features and ADC values can improve the diagnostic efficiency for differentiating benign and malignant testicular tumors, and can additionally distinguish different subtypes of malignant testicular tumors.

Figure 1

Flow chart depicting the patient screening process with exclusion criteria.

Figure 2

Images of a 47-year-old man with seminoma in right testis. (A) Axial fat-suppressed T2-weighted image shows a hypointense multinodular tumor with focal necrosis and hypointense septa (arrow). (B) Axial arterial phase fat-saturated gadolinium-enhanced T1-weighted image displays that the fibrous septa is more enhanced than the remaining tumor tissue (arrow). (C) Axial diffusion-weighted imaging (DWI) reveals a hyperintense mass with a mean apparent diffusion coefficient (ADC) value of 0.71 × 10⁻³ mm²/s (D).

Figure 3

ROC curves of the ADC value model, conventional MRI model, and ADC value combined with conventional MRI model (full model) were used to distinguish benign and malignant testicular tumors. The AUCs of ADC (black line), conventional MRI model (green line) and full model (red line) were 0.739, 0.919, and 0.946, respectively. ADC = apparent diffusion coefficient.

Figure 4

Images of a 41-year-old man with NSGCT in right testis. (A) Axial fat-suppressed T2-weighted image shows a hyperintense multinodular tumor with focal necrosis (arrow). (B) Axial DWI presents with heterogenous hyperintense signal with a mean ADC value of 0.83 × 10⁻³ mm²/s (C). ADC = apparent diffusion coefficient.

Figure 5

Images of a 63-year-old man with lymphoma in the bilateral testises. (A) Axial fat-suppressed T2-weighted image shows bilateral round-like tumors with hypointense signal. (B) Axial arterial phase fat-saturated gadolinium-enhanced T1-weighted image displays bilateral tumors with homogeneous enhancement and invasion of the right spermatic cord (arrow). (C) The bilateral masses present with heterogenous hyperintense signal on the DWI and heterogenous hypointense signal on the ADC image (D) with a mean value of 0.35 × 10⁻³ mm²/s (right), 0.48 × 10⁻³ mm²/s (left). ADC = apparent diffusion coefficient.