MRI TRUS/FUSION BIOPSIES: IS MRI ACCURATE IN PREDICTING HIGH
GRADE PROSTATE CANCER ?
Riccardo Lombardo, Andrea Cantiani, Cosimo De Nunzio, Christof Kastner²
Dipartimento di Urologia, Ospedale Sant’Andrea, Roma
²Department of Urology, Addenbrooke’s Hospital, Cambridge
Purpose: The aim of our study was to determine accuracy of MRI in detecting significant cancer in
MRI/TRUS fusion prostate biopsies in patients with previous negative biopsies at increase risk of
prostate cancer.
Materials and Methods: A consecutive series of patients underwent transperinal targeted prostate
biopsies using MRI/TRUS Fusion technology after previous negative biopsies . Each patient
underwent pelvic 3 T MRI (T1, T2, DWI and ADC map) before biopsy and lesions on the MRI
were characterized as non suspicious, suspicious or very suspicious. If lesions were present on MRI,
they were contoured and fused to a live transrectal ultrasound image in order to target the suspected
lesions. In addition to these targeted biopsies additional sector biopsies were taken. If no lesions
were identified standard sector biopsies were taken. Age, PSA, DRE, prostate volume, number of
cores and Gleason score on histological analysis were recorded. The prostate was divided in 12
sectors and each sector was analyzed to see correlation between MRI and Histology. Low grade
disease was defined as gleason 7 (3+4) or lower and high grade was defined as gleason 7 (4+3) or
higher.
Results: 108 patients were analyzed retrospectively. At the time of biopsy, median age was 64
(IQR=58/68) years, median PSA was 9.6 (IQR=6.6/13.2)ng/ml, median prostate volume was 55
(IQR=39/82)ml and the median number of cores for each biopsy was 30 (IQR=27/33) . Overall 5/108 (5%)
complications were recorded, out of them 4 were acute urinary retentions and 1 bleeding that didn’t require
intervention. A total of 1082 sectors were analyzed and out of them 172/1082(15%) were positive on MRI.
Positive sectors were: 30/172 (17%) score 3, 53/172 (31%) score 4 and 89/172 (52%) score 5 while no score
2 was given. Out of all 161/1082 (15%) had cancer and 99/161 (61%) had low grade disease while
62/161(39%) had high grade disease. In the analysis per sector MRI reached a negative predictive value of
89%, a positive predictive value of 36% and an accuracy of 79%. On univariate analysis age(p=0.000),
PSA(p=0.000) and score (p=0.000) correlated with the presence of cancer. Moreover on univariate analysis
Age (p=0.000), PSA (p=0.000) and score (0.0020) correlated with high grade disease. On multivariate
analysis Age was found to increase by 6.1% per unit the risk of having cancer, PSA increased it by 3.1 %
and score on MRI by 6.2%. Risk of high grade disease is increased by 8.6% per unit of age and by 7.5% per
unit of PSA.
Discussion:. The high negative predictive value could avoid unnecessary biopsies or decrease
number of biopsies with lower morbidity rates. Moreover MRI score could be included in
normograms in order to improve detection of significant cancer. However improving and
standardization in prostate MRI reading is still necessary.
Conclusion : The use of MRI/TRUS fusion biopsy is a very good option for patients with previous
negative biopsies and ongoing suspicion of cancer.