Multiparametric MRI in prostate cancer management

Abstract

Prostate cancer is the second most common cancer in men worldwide. The clinical behaviour of prostate cancer ranges from low-grade indolent tumours that never develop into clinically significant disease to aggressive, invasive tumours that may progress rapidly to metastatic disease and death. Therefore, there is an urgent clinical need to detect high-grade cancers and to differentiate them from the indolent, slow-growing tumours. Conventional methods of cancer detection-such as levels of prostate-specific antigen (PSA) in serum, digital rectal examination, and random biopsies-are limited in their sensitivity, specificity, or both. The combination of conventional anatomical MRI and functional magnet resonance sequences-known as multiparametric MRI (mp-MRI)-is emerging as an accurate tool for identifying clinically relevant tumours owing to its ability to localize them. In this Review, we discuss the value of mp-MRI in localized and metastatic prostate cancer, highlighting its role in the detection, staging, and treatment planning of prostate cancer.

Figure 1 |

A 61-year-old man with serum PSA of 23.85 ng/ml. a | Axial T2W–MRI, b | apparent diffusion coefficient map of diffusion-weighted MRI, and c | raw DCE–MRI demonstrate a 1 cm right apical mid-peripheral zone lesion (asterisk). d | Magnetic resonance spectroscopy shows an elevated choline-to-citrate ratio in the right mid-base anterior transitional zone compared with the normal left peripheral zone. Subsequent TRUS–MRI fusion-guided biopsy revealed a Gleason 4 + 4 tumour within that lesion. Abbreviations: DCE–MRI, dynamic contrast-enhanced MRI; PSA, prostate-specific antigen; T2W–MRI, T₂-weighted MRI; TRUS, transrectal ultrasound.

Figure 2 |

A 59-year-old man with serum PSA of 24.7 ng/ml. a | Axial T2W–MRI, b | apparent diffusion coefficient map of DW–MRI, and c | raw DCE–MRI demonstrate a large 5 cm lesion, which affects almost the entire prostate (asterisk). d,e | The lesion has extracapsular extension and invades the rectum (asterisk). f | Seminal vesicles are invaded bilaterally (asterisk). g | Magnetic resonance spectroscopy shows an elevated choline-to-citrate ratio (asterisk). Subsequent TRUS/MRI fusion-guided biopsy revealed a Gleason 5 + 5 tumour within the prostate. Abbreviations: DCE–MRI, dynamic contrast-enhanced MRI; DW–MRI, diffusion-weighted MRI; PSA, prostate-specific antigen; T2W–MRI, T₂-weighted MRI; TRUS, transrectal ultrasound.

Figure 3 |

Curve types representing enhancement patterns on DCE–MRI. Type 1 represents progressive enhancement, type 2 rapid enhancement with plateauing, and type 3 represents rapid enhancement followed by a rapid wash out of the contrast material. Abbreviations: DCE–MRI, dynamic contrast-enhanced MRI; SI, signal intensity.

Figure 4 |

Flowchart showing the utility of mp-MRI in various clinical scenarios of prostate cancer. MRI can be used as a cancer staging tool after a positive biopsy before definitive treatment, to identify target lesions before a targeted biopsy, as a way to monitor active surveillance patients and as a guide for patients with prior negative biopsies but rising serum PSA levels. MRI also has a role in the follow up of patients with a PSA recurrence after treatment. Abbreviations: DRE, digital-rectal examination; mp-MRI, multiparametric MRI; PSA, prostate-specific antigen; RP, radical prostatectomy; RT, radiotherapy; TRUS, transrectal ultrasound.