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* MRI acquires imaging data by detecting varying signal intensities from tissues based on the proton content of that tissue
* MRI acquires imaging data by detecting varying signal intensities from tissues based on the proton content of that tissue
* '''mpMRI is the combination of multiple MRI sequences usually consisting of T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), dynamic contrast enhanced (DCE) imaging and magnetic resonance spectroscopic imaging.'''
* '''mpMRI is the combination of multiple MRI sequences usually consisting of T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), dynamic contrast enhanced (DCE) imaging and magnetic resonance spectroscopic imaging.'''
* '''<span style="color:#ff0000">Imaging sequences</span>'''
 
** '''The primary diagnostic parameters are T2WI and DWI'''
====== '''<span style="color:#ff0000">Imaging sequences</span>''' ======
** '''<span style="color:#ff0000">T1WI</span>'''
* '''The primary diagnostic parameters are T2WI and DWI'''
*** Captures the movement of protons in the z-axis
* '''<span style="color:#ff0000">T1WI</span>'''
*** '''Often used to look at normal anatomical details.'''
** Captures the movement of protons in the z-axis
*** '''<span style="color:#ff0000">Optimal sequence to identify areas of hemorrhage within the prostate</span>'''
** '''Often used to look at normal anatomical details.'''
**** '''<span style="color:#ff0000">Blood has high signal intensity on T1</span>, against a homogenous low signal background.'''
** '''<span style="color:#ff0000">Optimal sequence to identify areas of hemorrhage within the prostate</span>'''
*** '''<span style="color:#ff0000">Prostate cancer has low signal intensity on T1'''
*** '''<span style="color:#ff0000">Blood has high signal intensity on T1</span>, against a homogenous low signal background.'''
** '''<span style="color:#ff0000">T2WI</span>'''
** '''<span style="color:#ff0000">Prostate cancer has low signal intensity on T1'''
*** Captures the movement of protons in the xy-axis (transverse)
* '''<span style="color:#ff0000">T2WI</span>'''
*** Primary means of visualization of zonal and anatomical features of the prostate.
** Captures the movement of protons in the xy-axis (transverse)
*** '''<span style="color:#ff0000">Optimal sequence to measure lesions in the transition zone</span>'''
** Primary means of visualization of zonal and anatomical features of the prostate.
*** '''Due to its high water content, the peripheral zone normally displays high signal intensity. By contrast, <span style="color:#ff0000">prostate cancer has low signal intensity on T2</span> allowing for identification of suspicious lesions'''
** '''<span style="color:#ff0000">Optimal sequence to measure lesions in the transition zone</span>'''
**** As 70% of all prostate cancers occur within the peripheral zone, the tissue characteristics allow for T2WI to detect a significant number of tumors in this zone
** '''Due to its high water content, the peripheral zone normally displays high signal intensity. By contrast, <span style="color:#ff0000">prostate cancer has low signal intensity on T2</span> allowing for identification of suspicious lesions'''
**** '''Various conditions such as prostatitis, hemorrhage, atrophy, scars and post-treatment changes have low signal intensity on T2 and can mimic cancer on T2WI.'''
*** As 70% of all prostate cancers occur within the peripheral zone, the tissue characteristics allow for T2WI to detect a significant number of tumors in this zone
***** Post-biopsy hemorrhage can interfere with tumor detection, since areas of hemorrhage appear similar to tumor on T2WI. For this reason, it is recommended to wait an interval of at least 6-8 weeks after prostate biopsy for resolution of hemorrhage or hematoma before performing prostate MRI.
*** '''Various conditions such as prostatitis, hemorrhage, atrophy, scars and post-treatment changes have low signal intensity on T2 and can mimic cancer on T2WI.'''
*** '''Low signal intensity tumors on T2WI of the central gland are more difficult to distinguish from the similarly hypointense stromal hyperplasia, ie benign prostatic hyperplasia'''
**** Post-biopsy hemorrhage can interfere with tumor detection, since areas of hemorrhage appear similar to tumor on T2WI. For this reason, it is recommended to wait an interval of at least 6-8 weeks after prostate biopsy for resolution of hemorrhage or hematoma before performing prostate MRI.
*** Central zone also displays intermediate signal intensity while seminal vesicles display high signal intensity
** '''Low signal intensity tumors on T2WI of the central gland are more difficult to distinguish from the similarly hypointense stromal hyperplasia, ie benign prostatic hyperplasia'''
** '''<span style="color:#ff0000">Diffusion weighted imaging (DWI)</span>'''
** Central zone also displays intermediate signal intensity while seminal vesicles display high signal intensity
*** Measures the diffusion of water protons within tissue
* '''<span style="color:#ff0000">Diffusion weighted imaging (DWI)</span>'''
*** The images are acquired by sequentially applying multiple magnetic field gradients, known as b-values, to calculate apparent diffusion coefficient values and construct ADC maps. The higher the b-value, the stronger the diffusion effects
** Measures the diffusion of water protons within tissue
*** '''ADC values are calculated by the software and displayed as a parametric map reflecting the degree of diffusion of water molecules through different tissues.'''
** The images are acquired by sequentially applying multiple magnetic field gradients, known as b-values, to calculate apparent diffusion coefficient values and construct ADC maps. The higher the b-value, the stronger the diffusion effects
**** Protons are mobile in normal water-rich glandular tissue but have restricted movement in densely packed water-poor tissue such as that found in tumors.
** '''ADC values are calculated by the software and displayed as a parametric map reflecting the degree of diffusion of water molecules through different tissues.'''
**** '''Normal glandular prostate tissue''' allows unrestricted free water movement and '''displays isointense regions on ADC maps''', which results in '''prostate cancer appearing as a decreased signal, ie restricted diffusion, on the ADC map and as high signal intensity focus on high b-value images.'''
*** Protons are mobile in normal water-rich glandular tissue but have restricted movement in densely packed water-poor tissue such as that found in tumors.
*** '''<span style="color:#ff0000">Tumors with the higher restriction (low ADC values) tend to be higher grade</span>'''
*** '''Normal glandular prostate tissue''' allows unrestricted free water movement and '''displays isointense regions on ADC maps''', which results in '''prostate cancer appearing as a decreased signal, ie restricted diffusion, on the ADC map and as high signal intensity focus on high b-value images.'''
*** '''<span style="color:#ff0000">Optimal sequence to evaluate suspicious lesions in the peripheral zone</span>'''
** '''<span style="color:#ff0000">Tumors with the higher restriction (low ADC values) tend to be higher grade</span>'''
** '''<span style="color:#ff0000">Dynamic contrast enhancement (DCE)</span>'''
** '''<span style="color:#ff0000">Optimal sequence to evaluate suspicious lesions in the peripheral zone</span>'''
*** '''DCE imaging uses a series of T1WI obtained shortly after injection of an intravenous gadolinium based contrast agent to''' '''<span style="color:#ff0000">measure the vascularity of prostate tissue</span>'''.
* '''<span style="color:#ff0000">Dynamic contrast enhancement (DCE)</span>'''
**** Tumors have increased vascularity due to neo-angiogenesis and, therefore, take up the contrast agent more rapidly than normal tissue. Moreover, this contrast washes out of tumor regions quickly leading to a steep wash-in-wash-out enhancement curve.
** '''DCE imaging uses a series of T1WI obtained shortly after injection of an intravenous gadolinium based contrast agent to''' '''<span style="color:#ff0000">measure the vascularity of prostate tissue</span>'''.
*** While DCE imaging has a high sensitivity, there remains a variability in the evaluation methods questioning it’s value; preferentially detects larger and higher-grade cancer foci
*** Tumors have increased vascularity due to neo-angiogenesis and, therefore, take up the contrast agent more rapidly than normal tissue. Moreover, this contrast washes out of tumor regions quickly leading to a steep wash-in-wash-out enhancement curve.
** '''<span style="color:#ff0000">Magnetic resonance spectroscopic imaging (MRSI)</span>'''
** While DCE imaging has a high sensitivity, there remains a variability in the evaluation methods questioning it’s value; preferentially detects larger and higher-grade cancer foci
*** '''Uses the relative concentration of cellular metabolites in the prostate, specifically citrate and choline, to detect prostate cancer.'''
* '''<span style="color:#ff0000">Magnetic resonance spectroscopic imaging (MRSI)</span>'''
**** '''Citrate is a marker of normal prostatic tissue, whereas high levels of choline can be found in cancerous cells owing to increased cell turnover, which, in turn, leads to an increased choline-to-citrate ratio in patients with prostate cancer'''
** '''Uses the relative concentration of cellular metabolites in the prostate, specifically citrate and choline, to detect prostate cancer.'''
*** '''<span style="color:#ff0000">When combined with T2WI, MRSI has been found to have the highest sensitivity of all MRI sequences (92%) in detecting prostate cancer.</span>'''
*** '''Citrate is a marker of normal prostatic tissue, whereas high levels of choline can be found in cancerous cells owing to increased cell turnover, which, in turn, leads to an increased choline-to-citrate ratio in patients with prostate cancer'''
*** While MRSI is a promising imaging sequence, it requires an extra 10 to 15 minutes of examination time. Also, for this phase an endorectal coil (see below) is mandatory at 1.5T and optional at 3T. For these reasons, MRSI is less commonly performed than other mpMRI sequences in prostate MRI studies.
** '''<span style="color:#ff0000">When combined with T2WI, MRSI has been found to have the highest sensitivity of all MRI sequences (92%) in detecting prostate cancer.</span>'''
** '''Biparametric MRI'''
** While MRSI is a promising imaging sequence, it requires an extra 10 to 15 minutes of examination time. Also, for this phase an endorectal coil (see below) is mandatory at 1.5T and optional at 3T. For these reasons, MRSI is less commonly performed than other mpMRI sequences in prostate MRI studies.
*** A limitation of mpMRI for implementation as an adjunct tool for prostate cancer screening is the time required to complete the study, including the placement of an endorectal coil and the use of gadolinium based contrast agents requiring intravenous access. To overcome these limitations, it has been suggested that a '''limited mpMRI study incorporating only non-contrast T2WI and DWI series be performed.'''
* '''Biparametric MRI'''
*** This biparametric MRI requires less than half the in-bore magnet time to perform compared with the complete mpMRI, can be performed without an endorectal coil, and obviates the need for intravenous access and contrast administration.
** A limitation of mpMRI for implementation as an adjunct tool for prostate cancer screening is the time required to complete the study, including the placement of an endorectal coil and the use of gadolinium based contrast agents requiring intravenous access. To overcome these limitations, it has been suggested that a '''limited mpMRI study incorporating only non-contrast T2WI and DWI series be performed.'''
* '''<span style="color:#ff0000">Magnet strength</span>'''
** This biparametric MRI requires less than half the in-bore magnet time to perform compared with the complete mpMRI, can be performed without an endorectal coil, and obviates the need for intravenous access and contrast administration.
** '''mpMRI can be performed at field strengths of 1.5T or 3T with or without an endorectal coil.'''
 
*** 3T magnets reduce image acquisition time and improve spatial resolution
====== '''<span style="color:#ff0000">Magnet strength</span>''' ======
*** Greater magnet strength does not necessarily mean greater cancer detection rates.
* '''mpMRI can be performed at field strengths of 1.5T or 3T with or without an endorectal coil.'''
* '''<span style="color:#ff0000">Endorectal coil</span>'''
** 3T magnets reduce image acquisition time and improve spatial resolution
** '''Standard clinical field strengths of 1.5T do not provide sufficient signal-to-noise ratio for clinical diagnosis of prostate cancer. To compensate for this deficiency, the use of surface and/or endorectal coil arrays has been proposed <span style="color:#ff0000">to increase the SNR</span>'''
** Greater magnet strength does not necessarily mean greater cancer detection rates.
** An ERC can lead to deformation of the gland which may affect the image registration for targeted biopsy or radiation planning, although concerns regarding alterations in prostate volume have largely been dispelled.
 
** The absolute benefit of an ERC may be offset by patient discomfort, additional time required for proper placement and verification, and associated cost
====== '''<span style="color:#ff0000">Endorectal coil</span>''' ======
** '''There is consensus regarding the use of a surface body coil and an endorectal coil at 1.5T but controversy remains regarding the need for an endorectal coil at 3T.'''
* '''Standard clinical field strengths of 1.5T do not provide sufficient signal-to-noise ratio for clinical diagnosis of prostate cancer. To compensate for this deficiency, the use of surface and/or endorectal coil arrays has been proposed <span style="color:#ff0000">to increase the SNR</span>'''
*** '''<span style="color:#ff0000">The highest signal-to-noise ratio (SNR) is achieved at 3T with an endorectal coil</span> but acceptable results can be achieved at 3T without an endorectal coil.'''
* An ERC can lead to deformation of the gland which may affect the image registration for targeted biopsy or radiation planning, although concerns regarding alterations in prostate volume have largely been dispelled.
* '''<span style="color:#ff0000">Prostate imaging and reporting archiving data system'''
* The absolute benefit of an ERC may be offset by patient discomfort, additional time required for proper placement and verification, and associated cost
** '''The PI-RADS score provided guidance for interpretation of different sequences and prostate zones'''
* '''There is consensus regarding the use of a surface body coil and an endorectal coil at 1.5T but controversy remains regarding the need for an endorectal coil at 3T.'''
***'''<span style="color:#ff0000">Positive predictive values ISUP grade group ≥2 based on PI-RADS score:</span>[https://pubmed.ncbi.nlm.nih.gov/35393568/]'''
** '''<span style="color:#ff0000">The highest signal-to-noise ratio (SNR) is achieved at 3T with an endorectal coil</span> but acceptable results can be achieved at 3T without an endorectal coil.'''
****'''<span style="color:#ff0000">PI-RADS 3: 12–15%</span>'''
 
****'''<span style="color:#ff0000">PI-RADS 4: 39–48%</span>'''
====== <span style="color:#ff0000">Prostate Imaging and Reporting Archiving Data System (PI-RADS) ======
****'''<span style="color:#ff0000">PI-RADS 5: 72%</span>'''
* '''Provides guidance for interpretation of different sequences and prostate zones'''
** Lesions in the peripheral zone appear round or irregular, and are focally hypointense, whereas transition zone lesions are non-circumscribed and moderately hypointense, and may exhibit a characteristic ‘‘erased charcoal’’ sign.
*'''Lesions are scored, ranges from 1-5, with increasing liklihood of having clinically significant disease'''
**'''<span style="color:#ff0000">Positive predictive values ISUP grade group ≥2 based on PI-RADS score:</span>[https://pubmed.ncbi.nlm.nih.gov/35393568/]'''
***'''<span style="color:#ff0000">PI-RADS 3: 12–15%</span>'''
***'''<span style="color:#ff0000">PI-RADS 4: 39–48%</span>'''
***'''<span style="color:#ff0000">PI-RADS 5: 72%</span>'''
* Lesions in the peripheral zone appear round or irregular, and are focally hypointense, whereas transition zone lesions are non-circumscribed and moderately hypointense, and may exhibit a characteristic ‘‘erased charcoal’’ sign.
 
====== '''<span style="color:#ff0000">Test Characteristics''' ======
 
* '''<span style="color:#ff00ff">Cochrane Systematic Review and Meta-analysis (2019)</span>'''
* '''<span style="color:#ff00ff">Cochrane Systematic Review and Meta-analysis (2019)</span>'''
**'''MRI compared with template‐guided biopsy'''
** '''MRI compared with template‐guided biopsy'''
***'''Detection of grade 2 or higher prostate cancer'''
***'''Detection of grade 2 or higher prostate cancer'''
****'''Sensitivity: 0.91 (95% CI 0.83 to 0.95)'''
****'''Sensitivity: 0.91 (95% CI 0.83 to 0.95)'''
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****'''Specificity: 0.35 (95% CI 0.26 to 0.46)'''
****'''Specificity: 0.35 (95% CI 0.26 to 0.46)'''
**[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483565/ Drost, Frank‐Jan H., et al.] "Prostate MRI, with or without MRI‐targeted biopsy, and systematic biopsy for detecting prostate cancer." ''Cochrane Database of Systematic Reviews'' 4 (2019).
**[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6483565/ Drost, Frank‐Jan H., et al.] "Prostate MRI, with or without MRI‐targeted biopsy, and systematic biopsy for detecting prostate cancer." ''Cochrane Database of Systematic Reviews'' 4 (2019).
*'''<span style="color:#ff0000">Randomized trials evaluating MRI in Prostate Cancer</span>'''
*'''<span style="color:#ff00ff">PROMIS (2017)</span>'''
**'''<span style="color:#ff00ff">PROMIS (2017)</span>'''
** '''<span style="color:#ff0000">Objective: evaluate sensitivity/specificity of prostate MRI vs. standard TRUS biopsy,</span> with template prostate mapping biopsy as gold standard reference'''
*** '''<span style="color:#ff0000">Objective: evaluate sensitivity/specificity of prostate MRI vs. standard TRUS biopsy,</span> with template prostate mapping biopsy as gold standard reference'''
** Population: 576 men with a clinical suspicion of prostate cancer (elevated serum PSA (up to 15 ng/mL) within previous 3 months, suspicious digital rectal examination, suspected organ confined stage T2 or lower on rectal examination, or family history) and no previous prostate biopsy
*** Population: 576 men with a clinical suspicion of prostate cancer (elevated serum PSA (up to 15 ng/mL) within previous 3 months, suspicious digital rectal examination, suspected organ confined stage T2 or lower on rectal examination, or family history) and no previous prostate biopsy
** '''Intervention: prostate MRI followed by template prostate mapping biopsy as gold standard reference and then standard TRUS biopsy'''
*** '''Intervention: prostate MRI followed by template prostate mapping biopsy as gold standard reference and then standard TRUS biopsy'''
***MRI was done with 1.5 Tesla magnet
****MRI was done with 1.5 Tesla magnet
***Patients with positive MRI did not undergo targeted biopsy
****Patients with positive MRI did not undergo targeted biopsy
** Primary outcomes: sensitivity and specificity of prostate MRI vs. standard TRUS biopsy for detection of clinically significant prostate cancer
*** Primary outcomes: sensitivity and specificity of prostate MRI vs. standard TRUS biopsy for detection of clinically significant prostate cancer
***Clinically significant prostate cancer defined as Gleason score ≥4 + 3 or a maximum cancer core length 6 mm or longer
****Clinically significant prostate cancer defined as Gleason score ≥4 + 3 or a maximum cancer core length 6 mm or longer
**'''<span style="color:#ff0000">Results:</span>'''
***'''<span style="color:#ff0000">Results:</span>'''
*** '''<span style="color:#ff0000">mpMRI displayed a moderate sensitivity</span>''' (88%) and negative predictive value (76%), '''<span style="color:#ff0000">but poor specificity</span>''' (45%) and positive predictive value (65%).
**** '''<span style="color:#ff0000">mpMRI displayed a moderate sensitivity</span>''' (88%) and negative predictive value (76%), '''<span style="color:#ff0000">but poor specificity</span>''' (45%) and positive predictive value (65%).
**Authors' interpretation: MP-MRI, used as a triage test before first prostate biopsy, could reduce unnecessary biopsies by ≈25% (based on negative-predictive value). MP-MRI can also reduce over-diagnosis of clinically insignificant prostate cancer and improve detection of clinically significant cancer.
***Authors' interpretation: MP-MRI, used as a triage test before first prostate biopsy, could reduce unnecessary biopsies by ≈25% (based on negative-predictive value). MP-MRI can also reduce over-diagnosis of clinically insignificant prostate cancer and improve detection of clinically significant cancer.
**[https://pubmed.ncbi.nlm.nih.gov/28110982/ Ahmed, Hashim U., et al.] "Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study." The Lancet 389.10071 (2017): 815-822.
***[https://pubmed.ncbi.nlm.nih.gov/28110982/ Ahmed, Hashim U., et al.] "Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study." The Lancet 389.10071 (2017): 815-822.
 
** '''<span style="color:#ff00ff">PRECISION (2018)</span>'''
====== '''<span style="color:#ff0000">Advantages</span>''' ======
*** Objective: can MRI be used to increase detection of clinically significant prostate cancer and decrease detection of clinically insignificant prostate cancer
 
*** '''Design: Non-inferiority trial'''
* '''Compared to pathway of elevated PSA to TRUS-guided biopsy without MRI, pathway of elevated PSA to MRI with targeted biopsy'''  
*** '''<span style="color:#ff0000">Population: 500 men with clinical suspicion of prostate cancer based on elevated PSA or abnormal DRE</span>'''
** '''Improves identification of anterior tumors'''
*** '''<span style="color:#ff0000">Randomized to MRI +/- targeted biopsy vs. standard TRUS–guided biopsy</span>'''
** '''Reduces over diagnosis of clinically insignificant prostate cancer'''
**** '''Men in the MRI group underwent a targeted biopsy (without standard biopsy cores) if the MRI was suggestive of prostate cancer; men whose MRI results were not suggestive of prostate cancer were not offered biopsy'''
** '''Increases diagnosis of clinically significant prostate cancer'''
*** '''Outcomes'''
*** '''Up to 20% of negative MRI have clinically significant prostate cancer'''
**** '''Primary: proportion of men who received a diagnosis of clinically significant cancer'''
* '''<span style="color:#ff00ff">PRECISION (2018)</span>'''
**** Secondary: proportion of men who received a diagnosis of clinically insignificant cancer
** Objective: in males with clinical suspicious of prostate cancer, determine whether prostate MRI with targeted biopsy only can increase detection of clinically significant prostate cancer and decrease detection of clinically insignificant prostate cancer
*** '''<span style="color:#ff0000">Results:</span>'''
** '''Design: Non-inferiority trial'''
**** '''<span style="color:#ff0000">MRI-targeted biopsy was non-inferior and superior to detecting clinically significant cancer</span>''' (absolute risk difference 12%, 38% MRI vs. 26% standard TRUS)
** '''<span style="color:#ff0000">Population: 500 males with clinical suspicion of prostate cancer based on elevated PSA or abnormal DRE</span>'''
**** '''<span style="color:#ff0000">MRI-targeted biopsy was associated with fever patients being diagnosed with clinically insignificant cancer</span>''' (absolute risk difference -13%)
** '''<span style="color:#ff0000">Randomized to standard TRUS–guided biopsy vs. MRI +/- targeted biopsy</span>'''
*** Authors’ conclusion: Using MP-MRI to triage men might allow 27% of patients avoid a primary biopsy and diagnosis of 5% fewer clinically insignificant cancers. If subsequent TRUS-biopsies were directed by MP-MRI findings, up to 18% more cases of clinically significant cancer might be detected compared with the standard pathway of TRUS-biopsy for all. MP-MRI, used as a triage test before first prostate biopsy, could reduce unnecessary biopsies by a quarter. MP-MRI can also reduce over-diagnosis of clinically insignificant prostate cancer and improve detection of clinically significant cancer.
*** '''Males in the MRI group underwent a targeted biopsy (without standard biopsy cores) if the MRI was suggestive of prostate cancer; if MRI results were not suggestive of prostate cancer, males were not offered biopsy'''
*** [https://pubmed.ncbi.nlm.nih.gov/29552975/ Kasivisvanathan, Veeru, et al.] "MRI-targeted or standard biopsy for prostate-cancer diagnosis." New England Journal of Medicine 378.19 (2018): 1767-1777.
** '''Outcomes'''
** '''<span style="color:#ff00ff">MRI-FIRST (2019)</span>'''
*** '''Primary: proportion of males who received a diagnosis of clinically significant cancer'''
*** Objective: determine whether MRI prior to biopsy increases detection of clinically significant prostate cancer
*** Secondary: proportion of males who received a diagnosis of clinically insignificant cancer
*** '''Population: 275 patients with clinical suspicion of prostate cancer'''
** '''<span style="color:#ff0000">Results:</span>'''
*** '''Intervention: MRI followed by standard systematic biopsy then targeted biopsy of up to 2 lesions on MRI. Patients with negative multiparametric MRI (Likert score ≤2) had systematic biopsy only.'''
*** '''<span style="color:#ff0000">MRI-targeted biopsy was non-inferior and superior to detecting clinically significant cancer</span>''' (absolute risk difference 12%, 38% MRI vs. 26% standard TRUS)
*** '''Primary outcome: detection of clinically significant prostate cancer'''
*** '''<span style="color:#ff0000">MRI-targeted biopsy was associated with fever patients being diagnosed with clinically insignificant cancer</span>''' (absolute risk difference -13%)
*** '''Results:'''
** Authors’ conclusion: Using MP-MRI to triage men might allow 27% of patients avoid a primary biopsy and diagnosis of 5% fewer clinically insignificant cancers. If subsequent TRUS-biopsies were directed by MP-MRI findings, up to 18% more cases of clinically significant cancer might be detected compared with the standard pathway of TRUS-biopsy for all. MP-MRI, used as a triage test before first prostate biopsy, could reduce unnecessary biopsies by a quarter. MP-MRI can also reduce over-diagnosis of clinically insignificant prostate cancer and improve detection of clinically significant cancer.
**** '''No difference in detection of clinically significant prostate cancer''' (30% systematic biopsy vs. 32% targeted biopsy)
** [https://pubmed.ncbi.nlm.nih.gov/29552975/ Kasivisvanathan, Veeru, et al.] "MRI-targeted or standard biopsy for prostate-cancer diagnosis." New England Journal of Medicine 378.19 (2018): 1767-1777.
**** Clinically significant prostate cancer would have been missed in 5% of patients had systematic biopsy not been done, and in 8% of patients had targeted biopsy not been done
* '''<span style="color:#ff00ff">STHLM3 - MRI-targeted vs. standard biopsy in prostate cancer screening</span>'''
*** '''Obtaining a multiparametric MRI before biopsy in biopsy-naive patients can improve the detection of clinically significant prostate cancer compared to systematic biopsy alone but does not seem to avoid the need for systematic biopsy'''
**'''Population: 1532 males aged 50-74 years with screening PSA > 3 ng/mL'''
*** [https://pubmed.ncbi.nlm.nih.gov/30470502/ Rouvière, Olivier, et al.] "Use of prostate systematic and targeted biopsy on the basis of multiparametric MRI in biopsy-naive patients (MRI-FIRST): a prospective, multicentre, paired diagnostic study." The Lancet Oncology 20.1 (2019): 100-109.
***Screening population in STHLM3, compared to patients referred for abnormal PSA or DRE in PRECISION
**'''MRI may identify more clinically significant disease, avoid clinically insignificant disease, and help tailor treatment; however, up to 20% of negative MRI have clinically significant prostate cancer'''
**'''Randomized to standard TRUS-guided biopsy vs. MRI and if MRI positive then standard biopsy with targeted biopsy'''
***'''<span style="color:#ff00ff">STHLM3 - MRI-targeted vs. standard biopsy in prostate cancer screening</span>'''
***If MRI negative, biopsies were not performed unless Stockholm3 test scores ≥25% or greater
****'''Population: 1532 males aged 50-74 years with screening PSA > 3 ng/mL'''
** Primary outcome: proportion of males diagnosed with clinically significant cancer (Gleason score ≥7)
****'''Randomized to standard biopsy vs. MRI, with targeted and standard biopsy if the MRI results suggested prostate cancer'''
** Secondary outcome: proportion of males diagnosed with clinically insignificant cancers (Gleason score 6).
**** Primary outcome: proportion of males diagnosed with clinically significant cancer (Gleason score ≥7)
** Results
**** Secondary outcome: proportion of males diagnosed with clinically insignificant cancers (Gleason score 6).
*** MRI non-inferior to diagnose clinically significant disease (21% MRI vs. 18% standard biopsy)
**** Results
*** Significantly fewer clinically insignificant disease with MRI (4% MRI vs. 12% standard biopsy)
***** MRI non-inferior to diagnose clinically significant disease (21% MRI vs. 18% standard biopsy)
** [https://pubmed.ncbi.nlm.nih.gov/34237810/ Eklund, Martin, et al.] "MRI-targeted or standard biopsy in prostate cancer screening." ''New England Journal of Medicine'' (2021).
***** Significantly fewer clinically insignificant disease with MRI (4% MRI vs. 12% standard biopsy)
 
**** [https://pubmed.ncbi.nlm.nih.gov/34237810/ Eklund, Martin, et al.] "MRI-targeted or standard biopsy in prostate cancer screening." ''New England Journal of Medicine'' (2021).
====== <span style="color:#ff0000">Disadvantages</span> ======
*** '''Use of MRI in prostate cancer diagnosis as per the 2017 Cancer Care Ontario Guidelines</span>'''
 
**** '''<span style="color:#ff0000">Biopsy-naïve: MRI should not be considered standard of care'''
* '''Availability/cost'''
**** '''<span style="color:#ff0000">Prior negative biopsy: MRI followed by targeted biopsy may be considered</span>'''
* '''Interobserver reproducibility remains a challenge.'''
** '''MRI better at identifying anterior tumours'''
* '''Learning curve related to reading and to performing fusion biopsies'''
** '''MRI interobserver reproducibility remains a challenge.'''
* '''Use of MRI for tumor staging remains controversial.'''
** '''MRI has a learning curve related to reading and to performing fusion biopsies'''
** Variable sensitivities (13-91%) and specificities (49-97%) have been reported for predicting extra-capsular extension.
** '''Use of MRI for tumor staging remains controversial.'''
 
*** Variable sensitivities (13-91%) and specificities (49-97%) have been reported for predicting extra-capsular extension.
 
Modalities under investigation
'''Targeted biopsy only vs. targeted and systematic'''
 
* '''<span style="color:#ff00ff">MRI-FIRST (2019)</span>'''
** Objective: determine whether biopsy of MRI detected lesions increases detection of clinically significant prostate cancer compared to standard biopsy; can we omit standard biopsy and do only targeted biopsy (and no biopsy if MRI negative?)
** '''Design: paired-diagnostic study (non-randomized)'''
**'''Population: 275 patients with clinical suspicion of prostate cancer'''
** '''Intervention: MRI followed by standard systematic biopsy then targeted biopsy of up to 2 lesions on MRI. Patients with negative multiparametric MRI (Likert score ≤2) had systematic biopsy only.'''
** '''Primary outcome: detection of clinically significant prostate cancer'''
** '''Results:'''
*** '''No difference in detection of clinically significant prostate cancer''' (30% systematic biopsy vs. 32% targeted biopsy)
*** Clinically significant prostate cancer would have been missed in 5% of patients had systematic biopsy not been done, and in 8% of patients had targeted biopsy not been done
** '''Obtaining a multiparametric MRI before biopsy in biopsy-naive patients can improve the detection of clinically significant prostate cancer compared to systematic biopsy alone but does not seem to avoid the need for systematic biopsy'''
** [https://pubmed.ncbi.nlm.nih.gov/30470502/ Rouvière, Olivier, et al.] "Use of prostate systematic and targeted biopsy on the basis of multiparametric MRI in biopsy-naive patients (MRI-FIRST): a prospective, multicentre, paired diagnostic study." The Lancet Oncology 20.1 (2019): 100-109.
 
* '''Use of MRI in prostate cancer diagnosis as per the 2017 Cancer Care Ontario Guidelines</span>'''
** '''<span style="color:#ff0000">Biopsy-naïve: MRI should not be considered standard of care'''
** '''<span style="color:#ff0000">Prior negative biopsy: MRI followed by targeted biopsy may be considered</span>'''
 
====== Modalities under investigation ======
* Positron Emission Tomography (PET)
* Positron Emission Tomography (PET)
** One potential advantage of PSMA PET over mpMRI is that interpretation is not influenced by biopsy-related artifacts such as hemorrhage or inflammation
** One potential advantage of PSMA PET over mpMRI is that interpretation is not influenced by biopsy-related artifacts such as hemorrhage or inflammation
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