Especially, in patients with low PSA values, the diagnostic certainty was substantially higher in PET/MR (n = 76) compared to PET/CT (n = 256) as demonstrated by Maurer et al. [75] in a total of 332 patients: for PSA values 0.2–0.5 ng/ml 38.5 vs. 69.2% of positive findings on PET/CT vs. PET/MR were rated as highly suggestive for PC recurrence. This evidence concerns the gene KLK3 and pachyonychia congenita.