Transrectal ultrasonography (TRUS)
The third pillar of prostate screening is transrectal ultrasonography (TRUS). As a rule, sonographic changes in the prostate cannot be allocated to a dignity; hypoechogenic lesions in the peripheral zone are most likely to be suspicious.
Overall, only about 50% of all tumours appear to be hypoechogenic in sonography, with the remaining 50% being iso- or hyperechogenic. The sensitivity of sonography alone is well below the sensitivity of a combined PSA test and DRE, which is why TRUS cannot be used as a sole examination method in cancer diagnosis. If a prostate carcinoma is present, transrectal ultrasonography can help identify the clinical stage (capsule infiltration, locally advanced tumour).
Sonography: Horizontal section incl. volume calculation
MRI (magnetic resonance imaging)
As regards new prostate cancer diagnoses, MRI is currently the most reliable imaging method to identify the local stage. However, this examination method is quite time-consuming and expensive and its sensitivity varies greatly in dependence on the examiner’s experience. Its sensitivity for extraprostatic tumour growth to be diagnosed by means of MRI is between 50% and 90%, which reflects the high examiner-dependent variability.
Where an MRI is performed with a 1.5 tesla MRI scanner, an endorectal coil should be used (not necessary with 3 tesla MRI scanners), because this allows for any irregularities or extension beyond the prostatic capsule or a seminal vesicle infiltration to be displayed more even more accurately.
Diffusion MRI with endorectal coil: Suspicious small hypointense lesion on the left at the transition from the central to the peripheral zone in the mid-third of the prostate