in the last three decades , magnetic resonance imaging ( mri ) has been used for noninvasive assessment of the prostate and surrounding structures . initially , prostate mri was only based on morphologic assessment , using t1-weighted imaging ( t1wi ) and t2-weighted imaging ( t2wi ) sequences . its role was primarily for loco - regional staging of the prostate cancer as it provided limited capability to distinguish between benign pathological tissue and clinically insignificant tumors from significant prostate cancer . to increase the diagnostic accuracy , anatomic t2wi and functional mri sequences - such as dynamic contrast enhanced mri ( dce - mri ) , diffusion - weighted imaging ( dwi ) with its derivate apparent - diffusion coefficient ( adc ) map and hydrogen 1 mr spectroscopic imaging ( mrsi ) - were combined in an integrated multiparametric mri ( mp - mri ) examination . the technological advances , combined with a growing interpreter experience , have substantially improved the detection of clinically significant prostate cancer , which is critical for reducing mortality , and increased confidence in ruling out benign diseases and dormant malignancies , in order to reduce unnecessary biopsies and treatment . in 2012 the european society of urogenital radiology ( esur ) working group developed the guidelines for mp - mri of the prostate . the acquisition protocols were then proposed , in order to provide the prostate imaging reporting and data system ( pi - rads ) , which relays the probability of cancer risk and its aggression . recently , the pi - rads version 2 was developed , including the following changes : ( a ) the concept of a dominant sequence depending on the location of the lesion ; ( b ) the statement that dce - mri should be scored positive if early focal enhancement is present and negative , if not or if diffuse enhancement is noticed , instead of using the curve - type analysis described in pi - rads version 1 ; ( c ) for positive dce - mri results , the pi - rads score should be increased by one point , if it makes a clinically relevant difference ; ( d ) finally , an overall pirads score , on a scale of 15 is assigned , according to the revised rules from pi - rads version 2 . in the second version of pi - rads , clinically significant cancer is defined on pathology as gleason score 7 ( including 3 + 4 with prominent gleason 4 component ) , and/or volume 0.5 cc , and/or extraprostatic extension . this definition is intended to standardize reporting of mp - mri and correlation with pathology for clinical and research applications . the aim of this study is to evaluate the diagnostic performance of mp - mri at 1.5-tesla ( 1.5-t ) , for the detection of clinically significant prostate cancer . a total of 90 patients with clinically suspected prostate cancer were examined by mp - mri , between october 2013 and february 2016 , in a prospective single - center study . we included in this study patients with clinically significant prostate cancer proved on biopsy or prostatectomy . the patients with a history of positive prostate biopsy and the patients who were treated for prostate cancer were excluded . finally , 39 patients - mean age 68.02 years ( ranging from 51 to 78 years ) were included in this study . written informed consent was obtained from all the patients included in the study , in order to use their laboratory , imaging and histopathologic data . the study was carried out in agreement with the code of ethics of the world medical association ( helsinki declaration ) for experiments involving human subjects . all patients were examined by using a 1.5-tesla equipment ( magnetom avanto , siemens healthcare , erlangen , germany ) . the same mp - mri protocol was used for all patients : axial t2wi , sagittal t2wi , coronal t2wi , axial dwi with adc map , axial t2 fat - sat , coronal t1wi and axial dce - mri ( table i ) . for dce - mri a bolus injection of 0.1 mmol / kg body weight of gadolinium - based contrast agent followed by a saline flush of 20 ml was given . the examinations were read by a radiologist with 3 years of experience in prostate - mri . the images were analyzed using the syngo vb17 software with the commercially available applications ( siemens medical solutions , erlangen , germany ) and osirix viewer . suspected lesions were noticed in mri reports and were categorized according to the pi - rads 2 lexicon ; a pirads score was assigned for all mr abnormalities . for 17 patients examined between october 2013 and december 2014 , the version 1 pi - rads score   was initially used . once the pi - rads version 2 scoring system was available , a revised pi - rads score was reported for these patients without modifying the initial mri report . the transition from pi - rads version 1 to pi - rads version 2 was made in order to use the same scoring system for all of the patients examined in the study . the mr findings were reported as  positive  if pirads 3 , pirads 4 or pirads 5 lesions were present and  negative  if only pirads 1 or pirads 2 findings were identified . a standardized multiparametric - mri reporting scheme - modified after rothke et al .   - all 39 patients underwent a standard 12 core transrectal ultrasonography ( trus)guided biopsy ; additional targeted cores were picked up in 7 patients , from mr suspected lesions . during the study period , 4 of 39 patients with prostate cancer underwent radical prostatectomy . antibodies used were p63 ( clone 7jul , novocastra ) , high molecular weight cytokeratin ( clone 34betae12 , novocastra ) and also alpha - methylacyl - coa racemase ( amacr , p504s , clone epmu1 , novocastra ) . antigen retrieval was performed with a pressure cooker and hier method . a pathologist with 8 years of experience in prostate pathology examined the slides , using an olympus bx43 microscope . the clinically significant cancer was defined , according to pi - rads version 2 system , as gleason score 7 , and/or volume 0.5 cc , and/or extraprostatic extension . when prostatectomy was not performed and only biopsy result was available , we defined a clinically significant prostate cancer core as gleason score 7 , and/or having a cancer length greater than 5 mm . the standard of reference was settled by the results of systematic trus - guided biopsy : a patient was considered  true positive  if biopsy specimens showed pathologically positive results and  true negative  if biopsy result was negative . numerical variables were descriptive presented . for testing normality distribution of the numerical variables we used the kolmogorov - smirnov test . for comparison of numerical variables , the student test , mann - whitney and kruskal - wallis ( depending on its distribution ) were used . a total of 90 patients with clinically suspected prostate cancer were examined by mp - mri , between october 2013 and february 2016 , in a prospective single - center study . we included in this study patients with clinically significant prostate cancer proved on biopsy or prostatectomy . the patients with a history of positive prostate biopsy and the patients who were treated for prostate cancer were excluded . finally , 39 patients - mean age 68.02 years ( ranging from 51 to 78 years ) were included in this study . written informed consent was obtained from all the patients included in the study , in order to use their laboratory , imaging and histopathologic data . the study was carried out in agreement with the code of ethics of the world medical association ( helsinki declaration ) for experiments involving human subjects . all patients were examined by using a 1.5-tesla equipment ( magnetom avanto , siemens healthcare , erlangen , germany ) . the same mp - mri protocol was used for all patients : axial t2wi , sagittal t2wi , coronal t2wi , axial dwi with adc map , axial t2 fat - sat , coronal t1wi and axial dce - mri ( table i ) . for dce - mri a bolus injection of 0.1 mmol / kg body weight of gadolinium - based contrast agent followed by a saline flush of 20 ml was given . the examinations were read by a radiologist with 3 years of experience in prostate - mri . the images were analyzed using the syngo vb17 software with the commercially available applications ( siemens medical solutions , erlangen , germany ) and osirix viewer . suspected lesions were noticed in mri reports and were categorized according to the pi - rads 2 lexicon ; a pirads score was assigned for all mr abnormalities . for 17 patients examined between october 2013 and december 2014 , once the pi - rads version 2 scoring system was available , a revised pi - rads score was reported for these patients without modifying the initial mri report . the transition from pi - rads version 1 to pi - rads version 2 was made in order to use the same scoring system for all of the patients examined in the study . the mr findings were reported as  positive  if pirads 3 , pirads 4 or pirads 5 lesions were present and  negative  if only pirads 1 or pirads 2 findings were identified . a standardized multiparametric - mri reporting scheme - modified after rothke et al .   - all 39 patients underwent a standard 12 core transrectal ultrasonography ( trus)guided biopsy ; additional targeted cores were picked up in 7 patients , from mr suspected lesions . during the study period , antibodies used were p63 ( clone 7jul , novocastra ) , high molecular weight cytokeratin ( clone 34betae12 , novocastra ) and also alpha - methylacyl - coa racemase ( amacr , p504s , clone epmu1 , novocastra ) . a pathologist with 8 years of experience in prostate pathology examined the slides , using an olympus bx43 microscope . the clinically significant cancer was defined , according to pi - rads version 2 system , as gleason score 7 , and/or volume 0.5 cc , and/or extraprostatic extension . when prostatectomy was not performed and only biopsy result was available , we defined a clinically significant prostate cancer core as gleason score 7 , and/or having a cancer length greater than 5 mm . the standard of reference was settled by the results of systematic trus - guided biopsy : a patient was considered true positive  if biopsy specimens showed pathologically positive results and  true negative  if biopsy result was negative . numerical variables were descriptive presented . for testing normality distribution of the numerical variables we used the kolmogorov - smirnov test . for comparison of numerical variables , the student test , mann - whitney and kruskal - wallis ( depending on its distribution ) were used . the mean age of the examined patients was 68.026.38 years , ranging between 51 and 78 years . 10.3% of patients were between 5059 years , 43.6% ranged from 60 to 69 years and 46.2% were older than 70  table ii . the mean psa taken from blood samples was 22.6939.34 ng / ml , with a median psa of 12.95 ng / ml . patients were categorized based on psa value as follows : patients with psa < 10 ng / ml  38.5% ( 15 ) , patients with psa ranging from 10 to 20 ng / ml  28.2% ( 11 ) and with psa > 20 ng / ml  33.3% ( 13 ) . in our series , 8 patients ( 20.5% ) had prior negative biopsies and 31 patients ( 79.5% ) had no previous biopsies ; we found no statistically significant difference regarding the psa values between these two groups 25 patients had mr abnormalities , which were stratified according to the pi - rads 2 lexicon : focal abnormalities ( 1 ) , lesions ( 3 ) , masses ( 4 ) , nodules ( 5 ) , diffuse ( 4 ) , multifocal ( 4 ) , regional abnormalities ( 4 ) . pirads 5 was the dominant score ( 35.9 % ) in our mri reports ( figure 2 ) . we found a statistically significant difference regarding the distribution of pirads score between the psa groups ( p=0.011 )  table iv . all 39 patients underwent the standard transrectal ultrasonography ( trus)guided biopsy ; 7 patients had additional targeted cores on mr suspected lesions . 20 patients had positive biopsies and gleason 7 was the dominant score ( 35.9 % )  table v. there was no statistically significant difference regarding the gleason score distribution between the psa groups . we found a statistically significant difference between the mri reports in the psa groups ( p=0.016 )  table vi . the psa groups differed significantly regarding the biopsy results ( p=0.003 )  table vii . sensitivity , specificity , positive predictive value and negative predictive value were calculated among the whole group ( table viii ) . the highest incidence of prostate cancer was for males between 7079 years ( 46.2% ) . the result is consistent with data provided by the cancer report in north - western region of romania . in our study , the mri reports were positive for 25 ( 64.1% ) of 39 patients , of which 12 patients had high psa levels ( 20 ng / ml )  table vi . we found a statistically significant difference between the mri reports and the psa groups ( p=0.016 ) . pirads 1 and pirads 2 lesions were found more frequently in patients with psa value < 10 ng / ml ( 9 of 15 patients ) . in the group with psa20 ng / ml , pirads 4 and pirads 5 lesions were predominant ( 12 of 13 patients ) . a statistically significant difference regarding the distribution of pirads score between psa groups was found ( p=0.011 ) . .   demonstrated that the benefit of mri and targeted biopsy increases with the increasing level of psa . recent studies that included patients with psa levels > 10 ng / ml , reported the sensitivity , specificity , accuracy , ppv and npv for the detection of prostate cancer using combined mri , between 6995% , 6396% , 6892% , 7586% and 8095% , respectively [ 914 ] . in our series of patients , trus - guided biopsies were positive in 20 patients ( 51.3% ) of which 11 had a psa  20 ng / ml . 19 patients ( 48.7% ) had negative biopsies , 12 of them having low psa levels ( < 10 ng / ml ) . we found a statistically significant difference between the biopsy results and the psa groups ( p=0.003 ) . our overall sensitivity and specificity for mp - mri detection of clinically significant prostate cancer detection were 100% and 73.68% , respectively . evaluated the clinical value of dwi and dce - mri in combination with t2wi for the detection of prostate cancer , in a series of 83 consecutive male patients , taking as reference the systematic biopsy results . they reported a sensitivity of 95% , a specificity of 74% and an accuracy of 86% . in a retrospective study of 2011 , tamada et al .   reported a sensitivity of 83% and a specificity of 80% for combined mri techniques ( t2wi , dce - mri and dwi ) in prostate cancer detection , on a per - patient basis . their study evaluated a series of 50 patients and reference test was the12 cores trus - guided systematic biopsy . the accuracy , ppv and npv reported were 82% , 91% and 67% , respectively . .   found great variations in the detection of clinically significant prostate cancer in a systematic review of the literature from 2015 . 12 studies ( 1981 patients ) were included in this meta - analysis of which 5 were prospective studies . six studies were performed at 3-t scanner , two studies used a 1.5-t unit , and four studies alternately used 1.5- and 3-tesla equipments . the selected studies performed prostate mri with at least two functional techniques ( dw - mri , dce - mri or mrsi ) in addition to anatomical t2wi . sensitivity ranged from 58 to 96% , specificity from 23 to 87% and accuracy from 44 to 87% . the npv and ppv for the detection of clinically significant disease ranged from 63 to 98% and from 34 to 68% , respectively . the authors have concluded that mp - mri is able to detect significant prostate cancer in biopsy - nave males and men with prior negative biopsies . the high npv of mp - mri is important to the clinician because mp - mri could be used to rule out significant disease . in our study , the positive predictive value and the negative predictive value were 80% and 100% , respectively . eight of 39 patients had prior negative biopsies . in 4 patients the mri report was positive and in 3 cases the prostate cancer was confirmed by trus - guided biopsy ( two patients had gleason 7 and one had gleason 6 ) . assessed the performance of multiparametric mri in patients with prior negative trus - guided biopsy and showed that mp - mri had good performance for detecting and ruling out clinically significant prostate cancer , with a se of 90% and a npv of 95% . they concluded that mp - mri can be used as a triage test in the population with persistently elevated psa levels following a negative biopsy and thereby identify patients who can avoid unnecessary prostate biopsy . a published study in 2014 by itatani et al .   reported a clinical npv for mp - mri of 89.6% for clinically significant prostate cancer , over a longitudinal follow - up period of 5 years . therefore , the authors concluded that mp - mri can to rule out clinically significant prostate cancer before biopsy   some potentially influential factors need to be discussed . a limit of our study is the lack of accurate correlation between the mr localization of suspicious lesions and the trus - guided biopsy . using the mr - in bore biopsy or the mri - ultrasound fusion techniques could exceed this limit . some recent studies have shown that the detection of more clinically significant cancers in the mri - guided biopsy compared with systematic biopsy , improve the biopsy performance and the diagnostic benefits [ 17,2023 ] . the positive mri was reported per patient and not per lesion and this might potentially influenced our data . another limit of this study was that we used only one reader for mp - mri examinations . therefore , studies on larger groups of patients , with multiple readers are needed to confirm our data . our results show that 1.5 t mp - mri has a high sensitivity for the detection of clinically significant prostate cancer and high negative predictive value in order to rule out significant disease .
background and aimmultiparametric - magnetic resonance imaging ( mp - mri ) is the main imaging modality used for prostate cancer detection . 
 the aim of this study is to evaluate the diagnostic performance of mp - mri at 1.5-tesla ( 1.5-t ) for the detection of clinically significant prostate cancer.methodsin this ethical board approved prospective study , 39 patients with suspected prostate cancer were included . 
 patients with a history of positive prostate biopsy and patients treated for prostate cancer were excluded . 
 all patients were examined at 1.5-t mri , before standard transrectal ultrasonography 
 guided biopsy.resultsthe overall sensitivity , specificity , positive predictive value and negative predictive value for mp - mri were 100% , 73.68% , 80% and 100% , respectively.conclusionour results showed that 1.5 t mp - mri has a high sensitivity for detection of clinically significant prostate cancer and high negative predictive value in order to rule out significant disease .