| The current diagnostic pathway for prostate cancer has resulted in 19 overdiagnosis and consequent overtreatment as well underdiagnosis and 20 missed diagnoses in many men. Multiparametric MRI (mpMRI) of the 21 prostate has been identified as a test that could mitigate these diagnostic 22This Review, will describe the current status of the role of mpMRI in 86 prostate cancer diagnosis, starting with the basic principles of MRI, and its 87 clinical application and finally considering the future direction of this 88 technology in prostate cancer. 89 90[H1] Basics of multiparametric MRI 91 [H2] Principles and sequences 92When mpMRI was first considered for prostate cancer diagnosis, in 93 the middle 1980s, its use was focused on to T1-weighted and T2-weighted 94 sequences 23 . The rapid improvement of mpMRI technology has led to the 95 addition of further sequences such as diffusion-weighted imaging (DWI), 96 dynamic contrast-enhanced imaging (DCEI) (Fig 1, 2), and/or magnetic 97 resonance spectroscopy imaging (MRSI) 23 (Fig 2, 3). These advances 98 resulted in a multitude of contrast mechanisms that can be considered 99 together for improved diagnostic accuracy for prostate cancer 24 . 100 101[H3] T1-weighted imaging 102 T1-weighted imaging is used mainly for evaluation of regional lymph 103 nodes and bone structures 25 . In the context of prostate evaluation, its utility 104 is the ability to detect biopsy-related haemorrhage that can obscure or mimic 105 cancers 26 . In order to reduce postbiopsy artifacts, a delay of at least 6-8 106 weeks after biopsy is typically recommended. Currently, no consensus exists 107 concerning this clinical practice, indeed haemorrhage artifacts can still 108 persist beyond this time period. 25 . This sequence is of limited value for 109 detection of prostate cancer foci as presence of prostate cancer is not 110 associated with notableT1-weighted imaging changes 21 . 111 7 112[H3] T2-weighted imaging 113 T2-weighted imaging is a fundamental sequence in mpMRI of the 114 prostate, providing a highly defined anatomical image of the zonal 115 architecture of the prostate gland with excellent soft-tissue contrast 27 (Fig 4). 116 T2-weighted imaging reflects the water content of the tissue, which is related 117 to the cellularity 21 . 118In the normal prostate, the peripheral zonethe part of the prostate 119 present at birthappears homogeneously hyperintense on T2-weighted 120 imaging owing to its high glandular ductal tissue content 21 . Prostate cancer 121 is characterized by high cellularity and low water content and, therefore, will 122 appear hypointense on imaging 21 (Fig 2Aa, 2Ba). The decrease in intensity 123 is positively associated with the aggressiveness of cancer 28 . The transition 124 zone, which starts to form after puberty through the process of prostatic 125 epithelial and stromal hyperplasia, tends to exhibit high cellular density, and 126 appears heterogeneously hypointense 25 . For this reason, and because there is 127 no nonmalignant prostate against which to refe...

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