The feasibility of MR elastography with transpelvic vibration for localization of focal prostate lesion

Abstract

We aimed to evaluate the feasibility of MR elastography (MRE) using a transpelvic approach. Thirty-one patients who underwent prostate MRE and had a pathological diagnosis were included in this study. MRE was obtained using a passive driver placed at the umbilicus and iliac crests. The shear stiffness, clinical data, and conventional imaging findings of prostate cancer and benign prostatic hyperplasia (BPH) were compared. Inter-reader agreements were evaluated using the intraclass coefficient class (ICC). Prostate MRE was successfully performed for all patients (100% technical success rate). Nineteen cancer and 10 BPH lesions were visualized on MRE. The mean shear stiffness of cancer was significantly higher than that of BPH (5.99 ± 1.46 kPa vs. 4.67 ± 1.54 kPa, p = 0.045). One cancer was detected on MRE but not on conventional sequences. Six tiny cancer lesions were not visualized on MRE. The mean size of cancers that were not detected on MRE was smaller than that of cancers that were visible on MRE (0.8 ± 0.3 cm vs. 2.3 ± 1.8 cm, p = 0.001). The inter-reader agreement for interpreting MRE was excellent (ICC = 0.95). Prostate MRE with transpelvic vibration is feasible without intracavitary actuators. Transpelvic prostate MRE is reliable for detecting focal lesions, including clinically significant prostate cancer and BPH.

Figure 1

Flowchart of patient inclusion.

Figure 2

A 69-year-old man with prostate cancer confirmed after radical prostatectomy. (a) T2-weighted axial MR image showing a low-signal intensity lesion in the left apical transitional zone of the prostate. (b, c) Diffusion-weighted image (b = 1500 s/mm²) and ADC map show diffusion restriction in the corresponding area (ADC value, 0.528 × 10⁻³ m²/s). (d) Elastogram shows that the mean stiffness of the tumor is 6.218 kPa.

Figure 3

A 75-year-old man with benign prostatic hyperplasia confirmed using MRI-US fusion targeted biopsy. (a) T2-weighted axial MR image showing a well-encapsulated hypointense nodule in the right mid-transitional zone of the prostate. (b, c) Diffusion-weighted image (b = 1500 s/mm²) and ADC map show diffusion restriction in the corresponding area (ADC value, 0.735 × 10⁻³m²/s). (d) Elastogram shows that the mean stiffness of the tumor is 3.982 kPa.

Figure 4

A 64-year-old man was diagnosed with prostate cancer in the right lobe after radical prostatectomy. (a–c) There is no evidence of clinically significant prostate cancer on conventional prostate MRI (from left to right: axial T2WI, DWI, and ADC). (d) Elastogram shows a tumor in the right apical peripheral zone of the prostate, with a mean stiffness of 7.512 kPa.