Sperling Prostate Center

Testing PI-RADS Accuracy

UPDATE: 10/17/2021
Originally published 4/27/2014

The blog below about PI-RADS v1.0 (Prostate Imaging Reporting and Data System, Version 1), predated a revision, PI-RADS v2.0 by a year. Four years later another revision, PI-RADS v2.1, offered more specific descriptions and definitions in order to improve agreement among readers. Thus, the blog below is outdated. Recent studies tested PI-RADS v2.1 compared with v2.0.[i]

  1. Ghafoor, et al. (2020) – For measuring prostate gland volume, agreement among readers was excellent using both v2.0 and v2.1. Gland volume accuracy was slightly better using the earlier v2.0.
  2. Xu, et al. (2020) – In terms of agreement between two readers, and diagnostic accuracy of transition zone prostate cancer (TZPC), both v2.0 and v2.1 produced excellent agreement. However, v2.1 produced better diagnostic accuracy and specificity of TZPC—as was hoped for with this later revision.[ii]
  3. Wei, et al. (2021) – A few months after the Xu study, Wei et al. affirmed Xu’s results that the key changes in v2.1 improved reader agreement and diagnostic accuracy of TZPC. This was an important study that compared five readers’ interpretations. The larger number of readers helped identify that, “Reader experience continues to affect the performance of prostate MRI interpretation with PI-RADS v2.1,” since the most experienced reader had the highest sensitivity, specificity and accuracy.[iii]

The conclusion of the Wei study meshes with our own observation that experience matters, one reason why we are confident that our pioneer work with prostate MRI, and our continuing advancement in the use of Artificial Intelligence, has given the Sperling Prostate Center the authoritative reputation it deserves for accuracy in detection and diagnosis of prostate cancer.

 
I recently posted a blog describing PI-RADS (Prostate Imaging Reporting and Data System) which is a means of standardizing prostate MRI interpretation. I found a very encouraging study[iv] that evaluates how well this scoring system stands up to actual prostate biopsies, especially when compared to an earlier scoring system called the Likert score.

The study was conducted by German researchers in the Division of Radiology at the German Cancer Research Center in Heidelberg. Lead author Matthias Roethke is widely published, especially in prostate MRI, and he heads a very credible team.

The study involved 64 patients who underwent 3T multiparametric MRI prior to having MR/TRUS fusion guided biopsies. Any suspicious lesions identified by mpMRI were then scored using the PI-RADS classification, which assigns a value of 1-5 (from probably benign (1) to probably malignant (5) for each imaging parameter (see my previous blog). The chart below shows the classification when the values are totaled:

PI-RADS Classification System

PI-RADS classification

Definition

Total T2, DWI, DCE

Total T2, DWI, DCE, MRS

I

Most probably benign

3, 4

4, 5

II

Probably benign

5, 6

6-8

III

Indeterminate

7-9

9-12

IV

Probably malignant

10-12

13-16

V

Most probably malignant

13-15

17-20

The images were also scored using a simple Likert scoring system (1-5) which lacks the fine-tune analysis that PI-RADS affords. On the imaging, a total of 95 “regions of interest” were identified. Under fusion guidance, a total of 445 biopsy needles were taken from the regions of interest, averaging less than 5 cores per patient. 128 of the biopsy samples proved positive for prostate cancer. Thus, 27 out of the 64 patients had biopsy-proven prostate cancer. The biopsy results were compared with the PI-RADS system and the Likert scores for the regions of interest.

The authors found that PI-RADS was superior in both sensitivity and specificity. I am not surprised, because PI-RADS is based on at least three parameters (T2, DWI, and DEC) that highlight different tumor characteristics. The article concludes, “The standardized ESUR PI-RADS system if beneficial to indicate the likelihood of PCa of suspicious lesions on mpMRI. It is also valuable to identify locations to be targeted with biopsy. The aggregated PI-RADS score achieved better results compared to the single five-point Likert score.”

3T mpMRI offers us an image-rich portrait of prostate tumors that no other imaging can compare with. Experienced readers who knowledgeably assign PI-RADS scores to each parameter that shows a suspicious area are doing a great service for patients. At our center, we are fortunate indeed to contribute such detection and diagnosis methods for our patients.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

[i] Ghafoor S, Becker AS, Woo S, Causa Andrieu PI et al. Comparison of PI-RADS Versions 2.0 and 2.1 for MRI-based Calculation of the Prostate Volume. Acad Radiol. 2020 Aug 17:S1076-6332(20)30450-5.
[ii] Xu L, Zhang G, Zhang D, Zhang X et al. Comparison of PI-RADS version 2.1 and PI-RADS version 2 regarding interreader variability and diagnostic accuracy for transition zone prostate cancer. Abdom Radiol (NY). 2020 Dec;45(12):4133-4141.
[iii] Wei CG, Zhang YY, Pan P, Chen T et al. Accuracy and Interobserver Agreement of PI-RADS Version 2 and Version 2.1 for the Detection of Transition Zone Prostate Cancers. AJR Am J Roentgenol. 2021 May;216(5):1247-1256.
[iv] Roethke MC, Kuru TH, SchultzeS, et al. Evaluation of the ESUR PI-RADS scoring system for multiparametric MRI of the prostate with targeted MRI-TRUS fusion-guided biopsy at 3.0 Tesla. Eur Radiol. 2014;24(2):344-352.

 

About Dr. Dan Sperling

Dan Sperling, MD, DABR, is a board certified radiologist who is globally recognized as a leader in multiparametric MRI for the detection and diagnosis of a range of disease conditions. As Medical Director of the Sperling Prostate Center, Sperling Medical Group and Sperling Neurosurgery Associates, he and his team are on the leading edge of significant change in medical practice. He is the co-author of the new patient book Redefining Prostate Cancer, and is a contributing author on over 25 published studies. For more information, contact the Sperling Prostate Center.

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