Article

Advancements in MRI for prostate cancer

September is National Prostate Cancer Awareness Month and for good reason. More than 3 million men worldwide every year are affected by prostate cancer.1 Researchers and physicians have been trying to find the source, cause and treatment options of prostate cancer. Magnetic resonance imaging (MRI) frequently sees new technology and techniques. As such, MRI has become a valuable medical imaging method for the monitoring and treatment of prostate cancer.

Prostate biopsy

A physician may suspect that their patient may have prostate cancer if the patient has an abnormal prostate-specific antigen (PSA) blood test or digital rectal exam.2 When this occurs, the doctor may request a prostate biopsy to determine whether cells within the prostate are malignant. The biopsy is most commonly done using ultrasound as a guide.

Recent research has examined the use of MRI as a tool to guide prostate biopsy.3,4 Because of this, direct MRI-guided biopsy has begun to influence the field more and more. In some cases, MRI can be an important tool to learn more information.3 In others, MRI may improve the detection of significant prostate cancer, while reducing the number of biopsy cores during each procedure.4

A study of 127 patients with unknown or untreated prostate cancer with a Gleason score of 6 was conducted spanning from August 2013 to January 2018.3 This study included MRI-guided biopsy of all 127 of these patients to determine the progression of their pre-established prostate cancer. The MRI-guided biopsy showed that 93 of these patients had a higher Gleason score of 7, and 84 of these patients had a higher diagnosis. The accuracy for patients who had previous negative ultrasound-guided biopsies was 66%, with higher rates for both biopsy-naive patients (83%) and those undergoing surveillance (90%). The authors of this study believe that MRI provides important supplementary information in some situations.3

A retrospective review of seven randomized clinical trials was conducted to evaluate the impact of MR prebiopsy imaging combined with MR targeted biopsy compared to ultrasound-guided biopsy.4 The authors found that prebiopsy magnetic resonance imaging combined with targeted biopsy was associated with improved detection of clinically significant prostate cancer, as well as reduced numbers of biopsy cores per procedure. The study also notes that prebiopsy MRI combined with MR targeted biopsy could help physicians to potentially avoid unnecessary biopsies.4 This is in part due to the large proportion of individuals undergoing biopsy who have no prostate cancer or have a low-risk disease that does not require treatment.

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Predicting aggressiveness of prostate cancer

Alongside prostate biopsy guidance, MRI may help predict how aggressive a patient's prostate cancer is. Although this is still being researched, a team of researchers believe that radiomics and an algorithm using machine learning could help to predict this.5

Radiomics aims to extract quantitative features from medical images using data characterization algorithms.6 This data is then analyzed and could be used to improve decision support. Quantitative measurements are important to radiologists, because they provide a more clear understanding of the disease, as well as providing support for their beliefs.

The team developed an application with the goal of detecting prostate cancer lesions and predicting their aggressiveness based on multi-parametric MRI (mpMRI). The program analyzed the scans of 40 consecutive biopsy-confirmed prostate cancer patients. Each of these patients underwent biopsy four weeks after the dynamic contrast enhanced MRI exams. The time-signal-intensity curve from the study showed that lesion segmentation was performed on the first and the strongest phases of enhancement on the original DCE-MRI images. About 1,029 quantitative radiomics features were automatically calculated from each lesion. The application's performance matched that of three experienced radiologists for lesion detection with no statistically significant differences.6 The team believes the application may help to predict prostate cancer aggressiveness non-invasively, accurately and automatically.

MRI may provide better insight into prostate cancer when it is used prior to and as a guide during biopsy compared to ultrasound-guided biopsy. Furthermore, combining images taken during mpMRI with an application rooted in radiomics and machine learning can lead to a potential prediction method for prostate cancer aggressiveness, though this is still being researched. In turn, MRI could lead to a better understanding of the disease and its progression for the over 3 million men affected by prostate cancer each year and their doctors.

References:

  1. September is Prostate Cancer Awareness Month. PCF.orghttps://www.pcf.org/blue/. Last accessed September 19, 2019.
  2. Prostate biopsy. MayoClinic.orghttps://www.mayoclinic.org/tests-procedures/prostate-biopsy/about/pac-20384734. Last accessed September 19, 2019.
  3. Impact of Direct MRI-Guided Biopsy of the Prostate on Clinical Management. AJRonline.orghttps://www.ajronline.org/doi/abs/10.2214/AJR.18.21009. Last accessed September 18, 2019.
  4. Comparison of Multiparametric Magnetic Resonance Imaging and Targeted Biopsy With Systematic Biopsy Alone for the Diagnosis of Prostate Cancer: A Systematic Review and Meta-analysis. JAMANetwork.comhttps://jamanetwork.com/journals/jamanetworkopen/fullarticle/2747475?utm_source=miragenews&utm_medium=miragenews&utm_campaign=news. Last accessed September 16, 2019.
  5. Prediction of prostate cancer aggressiveness with a combination of radiomics and machine learning-based analysis of dynamic contrast-enhanced MRI. Clinical Radiologyhttps://www.sciencedirect.com/science/article/abs/pii/S0009d926019303551. Last accessed September 12, 2019.
  6. Radiomics. Radiopaediahttps://radiopaedia.org/articles/radiomics?lang=us. Last accessed September 13, 2019.