PI-RADS which an acronym for Prostate Imaging-Reporting and Data System refers to a structured reporting scheme for prostate cancer.
It is based on the BIRADS classification for breast imaging.
The score is assessed on prostate MRI. Images are obtained using a multi-parametric technique including T2 weighted images, a dynamic contrast study (DCE), DWI, and possibly spectroscopy (MRS).
A score is given according to each variable. The scale is based on a score from 1 to 5 (which is given for each lesion), with 1 being most probably benign and 5 being highly suspicious of malignancy.
These paramaters include
T2 signal
for the peripheral zone (PZ)
a. uniform high signal intensity (SI) - 1 (point)
b. linear, wedge shaped, or geographic areas of lower SI, usually not well demarcated - 2
c. intermediate appearances not in categories a/b or d/e -3
d. discrete, homogeneous low signal focus/mass confined to the prostate - 4
e. discrete, homogeneous low signal intensity focus with extra-capsular extension/invasive behaviour or mass effect on the capsule (bulging), or broad (>1.5 cm) contact with the surface - 5
for the transition zone (TZ)
a. heterogeneous TZ adenoma with well-defined margins: “organised chaos” - 1
b. areas of more homogeneous low SI, however well marginated, originating from the TZ/BPH - 2
c. intermediate appearances not in categories a/b or d/e
d. areas of more homogeneous low SI, ill defined: “erased charcoal sign” - 4
e. same as d, but involving the anterior fibromuscular stroma or the anterior horn of the PZ, usually lenticular or water-drop shaped - 5
diffusion weighted imaging (DWI)
a. no reduction in ADC compared with normal glandular tissue. No increase in SI on any high b-value image (≥b800) - 1
b. diffuse, hyper SI on ≥b800 image with low ADC; no focal features, however, linear, triangular or geographical features are allowed - 2
c. intermediate appearances not in categories a/b or d/e - 3
d. focal area(s) of reduced ADC but iso-intense SI on high b-value images (≥b800) - 4
e. focal area/mass of hyper SI on the high b-value images (≥b800) with reduced ADC - 5
dynamic contrast enhanced (DCE)-MRI
type 1 enhancement curve - 1
type 2 enhancement curve - 2
type 3 enhancement curve - 3
+1 point for for focal enhancing lesion with curve type 2–3
+1 point for asymmetric lesion or lesion at an unusual place with curve type 2–3
Additional scoring can be done with MR spectroscopy for a 1.5T scanner using the citrate and choline peak (3 voxels)
citrate peak height exceeds choline peak height >2 times - 1 point
citrate peak height exceeds choline peak height times >1, <2 times - 2 points
choline peak height equals citrate peak height - 3 points
choline peak height exceeds citrate peak height >1, <2 times - 4 points
choline peak height exceeds citrate peak height >2 times - 5 points
The lesions are then graded according to a classification system.
PI-RADS I - most probably benign -
total score with T2, DCE, DWI = 3,4
total score with T2, DCE, DCE and MRS = 4,5
PI-RADS II - probably benign
total score with T2, DCE, DWI = 5,6
total score with T2, DCE, DCE and MRS = 6-8
PI-RADS III - indeterminate
total score with T2, DCE, DWI = 7-9
total score with T2, DCE, DCE and MRS = 9-12
PI-RADS IV - probably malignant
total score with T2, DCE, DWI = 10-12
total score with T2, DCE, DCE and MRS = 13-16
PI-RADS V - highly suspicious of malignancy
total score with T2, DCE, DWI = 13-15
total score with T2, DCE, DCE and MRS = 17-20
In addition to the PI-RADS score for the probability of a lesion to be significant, extra-prostatic involvement should also be scored on a five-point scale 2.
extra-capsular extension
abutment - 1
irregularity - 3
neurovascular bundle thickening - 4
bulge, loss of capsule - 4
measurable extra-capsular disease - 5
seminal vesicles
expansion- 1
low T2 signal - 2
filling in of angle - 3
enhancement and impeded diffusion - 4
distal sphincter
adjacent tumour - 3
effacement of low signal sphincter muscle - 3
abnormal enhancement extending into sphincter - 4
bladder neck
adjacent tumour - 2
loss of low T2 signal in bladder muscle - 3
abnormal enhancement extending into bladder neck - 4
It is based on the BIRADS classification for breast imaging.
The score is assessed on prostate MRI. Images are obtained using a multi-parametric technique including T2 weighted images, a dynamic contrast study (DCE), DWI, and possibly spectroscopy (MRS).
A score is given according to each variable. The scale is based on a score from 1 to 5 (which is given for each lesion), with 1 being most probably benign and 5 being highly suspicious of malignancy.
These paramaters include
T2 signal
for the peripheral zone (PZ)
a. uniform high signal intensity (SI) - 1 (point)
b. linear, wedge shaped, or geographic areas of lower SI, usually not well demarcated - 2
c. intermediate appearances not in categories a/b or d/e -3
d. discrete, homogeneous low signal focus/mass confined to the prostate - 4
e. discrete, homogeneous low signal intensity focus with extra-capsular extension/invasive behaviour or mass effect on the capsule (bulging), or broad (>1.5 cm) contact with the surface - 5
for the transition zone (TZ)
a. heterogeneous TZ adenoma with well-defined margins: “organised chaos” - 1
b. areas of more homogeneous low SI, however well marginated, originating from the TZ/BPH - 2
c. intermediate appearances not in categories a/b or d/e
d. areas of more homogeneous low SI, ill defined: “erased charcoal sign” - 4
e. same as d, but involving the anterior fibromuscular stroma or the anterior horn of the PZ, usually lenticular or water-drop shaped - 5
diffusion weighted imaging (DWI)
a. no reduction in ADC compared with normal glandular tissue. No increase in SI on any high b-value image (≥b800) - 1
b. diffuse, hyper SI on ≥b800 image with low ADC; no focal features, however, linear, triangular or geographical features are allowed - 2
c. intermediate appearances not in categories a/b or d/e - 3
d. focal area(s) of reduced ADC but iso-intense SI on high b-value images (≥b800) - 4
e. focal area/mass of hyper SI on the high b-value images (≥b800) with reduced ADC - 5
dynamic contrast enhanced (DCE)-MRI
type 1 enhancement curve - 1
type 2 enhancement curve - 2
type 3 enhancement curve - 3
+1 point for for focal enhancing lesion with curve type 2–3
+1 point for asymmetric lesion or lesion at an unusual place with curve type 2–3
Additional scoring can be done with MR spectroscopy for a 1.5T scanner using the citrate and choline peak (3 voxels)
citrate peak height exceeds choline peak height >2 times - 1 point
citrate peak height exceeds choline peak height times >1, <2 times - 2 points
choline peak height equals citrate peak height - 3 points
choline peak height exceeds citrate peak height >1, <2 times - 4 points
choline peak height exceeds citrate peak height >2 times - 5 points
The lesions are then graded according to a classification system.
PI-RADS I - most probably benign -
total score with T2, DCE, DWI = 3,4
total score with T2, DCE, DCE and MRS = 4,5
PI-RADS II - probably benign
total score with T2, DCE, DWI = 5,6
total score with T2, DCE, DCE and MRS = 6-8
PI-RADS III - indeterminate
total score with T2, DCE, DWI = 7-9
total score with T2, DCE, DCE and MRS = 9-12
PI-RADS IV - probably malignant
total score with T2, DCE, DWI = 10-12
total score with T2, DCE, DCE and MRS = 13-16
PI-RADS V - highly suspicious of malignancy
total score with T2, DCE, DWI = 13-15
total score with T2, DCE, DCE and MRS = 17-20
In addition to the PI-RADS score for the probability of a lesion to be significant, extra-prostatic involvement should also be scored on a five-point scale 2.
extra-capsular extension
abutment - 1
irregularity - 3
neurovascular bundle thickening - 4
bulge, loss of capsule - 4
measurable extra-capsular disease - 5
seminal vesicles
expansion- 1
low T2 signal - 2
filling in of angle - 3
enhancement and impeded diffusion - 4
distal sphincter
adjacent tumour - 3
effacement of low signal sphincter muscle - 3
abnormal enhancement extending into sphincter - 4
bladder neck
adjacent tumour - 2
loss of low T2 signal in bladder muscle - 3
abnormal enhancement extending into bladder neck - 4
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