Italian culture is renowned for auto design. Arguably, many of the world’s most stunning cars were produced in the boot-shaped country by Ferrari, Maserati, Lamborghini and others. Their designers have been second to none, merging objective engineering and efficiency with subjective art. The autos they produced have often won not only historic races, but pure admiration for their sleek beauty.
Multiparametric MRI (mpMRI) is also a marriage of engineering, efficiency, and art. Radiologists rely on cutting edge equipment to produce objectively accurate high-resolution images in the shortest possible time; then, they add their subjective art of interpretation based on experience. Just as with racecars, speed counts—but it’s a race against time when it comes to prostate cancer (PCa).
mpMRI has revolutionized PCa diagnosis. It is now the standard of care when it comes to eliminating unnecessary biopsies, qualifying patients for Active Surveillance (AS) and monitoring them, planning treatment, guiding ablation treatments, and confirming/following up treatment results.
Multiparametric MRI uses at least 3 imaging sequences called parameters. The 3 main workhorses are:
- T2-weighted imaging (T2) for prostate and neighboring anatomy
- Diffusion-weighted imaging (DWI) for telltale restricted water movement in tissues
- Dynamic contrast enhanced (DCE) involving an IV-administered gadolinium-based contrast agent during the MRI scan to visualize blood flow for signs of abnormal tumor blood vessels
Each sequence defines specific tissue characteristics. When integrated, the scans are visually analyzed and evaluated by radiologists. Increasingly, their analysis is augmented by Artificial Intelligence (AI) tools that are trained to recognize image features that the human eye can’t perceive.
mpMRI has altered the PCa detection, diagnosis and treatment landscape the way Humvees changed personnel and light cargo transport in conflict zones—they deliver the goods. However, mpMRI is relatively expensive in terms of healthcare dollars. Acquisition times are long, especially if DCE is included, and not every patient can tolerate the contrast agent. Imagine a Humvee on the starting grid along with aerodynamically beautiful Italian cars in a classic Le Mans marathon. Not only does the Hummer look incongruous, but it will quickly be outpaced by its sleek competitors. In the race against diagnostic time, clinicians and researchers are looking for a sleeker, more efficient MRI formula.
Italians explore “less-is-better” options
At the start of 2021, a team of Italian urology/radiology clinicians published their consideration of less-is-better alternatives to mpMRI.[i] The goal is to increase availability, reduce radiology workloads, tailor scans to individual patient needs, and economize. It’s like asking, “Can we take a Humvee and sleek it down so it performs faster without losing delivery power—and still preserve the art of interpretation?” In short, can we get the same imaging “bang for the buck” using shorter or fewer sequences?
Proposed alternatives in which less is better
The research team explored ways to streamline mpMRI. Their proposed alternatives include the following:
- Non-contrast biparametric MRI is called “bi-parametric” since it uses only T2 and DWI sequences. While an argument can be made that contrast increases the sensitivity for detecting clinically significant PCa, the authors point out that for most MRI exams the use of DCE is redundant. However, it may have the most merit for evaluating suspicious lesions in the peripheral zone of the gland.
- Reduced acquisition time means shortening the time-consuming capture of T2 images in separate imaging planes. A technique called a three-dimensional volumetric T2 sequence compresses the scan time needed to generate a 3-D picture from separate planes. This method offers better delineation of suspicious lesions.
- Abbreviated protocols eliminate certain imaging planes yet preserving core information for certain clinical questions. The authors point to a 2017 study of an abbreviated protocol of 542 men in which T2 and DWI were used only in the transverse plane, reducing a 34.5-minute scan to just under 9 minutes. However, more research is needed to validate this method, and also to find out if it can be used for other diagnostics such as clinical staging.
- Application of Artificial Intelligence in the form of Computer-Assisted Diagnosis (CAD). Well-trained computer programs have the potential to identify clinically significant PCa faster than radiologists while utilizing any of the above three methods. Studies are ongoing, with varying programs/algorithms and inconsistent results, but some studies have demonstrated compelling results. Again, more research is needed.
- Different-is-better methods about which the authors write, “…there is a parallel pathway of prostate MRI development, searching for objective and reproducible MRI-related biomarkers for the prediction of PCa aggressiveness or overcoming inter-reader variability.”[ii] A subspecialty of imaging + AI called radiomics, and hybrid methods like PET/MRI are steps in this direction.
The goal of such research is a noble one. It’s in everyone’s best interest to make MRI more cost-effective and more widely available to PCa patients, without sacrificing accurate results. At our own Center, we stay up to date on research, and are in the vanguard of incorporating Artificial Intelligence (AI) in our imaging and diagnostics. We know that shorter imaging protocols together with precision AI analytics will benefit patients everywhere. It’s a team effort, and we are 100% on board with the work of our Italian colleagues and all those around the globe.
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] Girometti R, Cereser L, Bonato F, Zuiani C. Evolution of prostate MRI: from multiparametric standard to less-is-better and different-is better strategies. Eur Radiol Exp. 2019 Jan 28;3(1):5. https://eurradiolexp.springeropen.com/articles/10.1186/s41747-019-0088-3