Controversies in Neuroradiology
Techniques and reporting methods among topics causing debate
MRI and CT are key to diagnosing disease in patients with new symptoms, but radiology also plays a crucial role in tracking how diseases respond to treatment. That is a crucial role for the field of neuroradiology.
“Neuroradiology allows us to see diseases like tumors, infection, inflammation and demyelination without having to run a blood test or take a piece of the tissue,” said Brent Weinberg, MD, PhD, a neuroradiologist at Emory University in Atlanta. “Because it’s noninvasive, we can also use neuroradiology for follow up imaging to see how a disease responds to treatment.”
While the benefits of neuroradiology are clear, the use of subspecialized imaging can come with controversy.
“Neuroradiology itself is not controversial, but there are some topics within the subspeciality where there is significant debate on what we should or shouldn’t be doing,” Dr. Weinberg added.
One such topic is theranostics—a growing field that combines molecular imaging including PET with radionuclide therapy, particularly in the management of brain tumors.
According to Jana Ivanidze, MD, PhD, a neuroradiologist and nuclear medicine physician at Weill Cornell Medicine in New York City, by offering excellent functional visualizations of tumors based on tumor-specific characteristics, theranostics allows for diagnosis, treatment planning and response assessment.
“Theranostics broadens the role of the radiologist as an integral part of the treatment team, playing a direct role in improving patient outcomes,” Dr. Ivanidze explained.
Dr. Ivanidze emphasized that PET scans can also help guide the management of brain and skull base tumors, especially in the context of diagnosis, surgical planning and treatment monitoring. PET can be used to differentiate between tumor recurrence and treatment-related changes.
Targeted neuro-oncologic PET approaches, such as DOTATATE PET and amino acid PET, allow for excellent diagnostic accuracy in the delineation of primary and secondary brain tumors, adding key information to conventional MRI.
“These neuroradiology and molecular imaging techniques are available in clinical practice today and it’s not a question of should we be using them—but why aren’t we?” Dr. Ivanidze said.
“These neuroradiology and molecular imaging techniques are available in clinical practice today and it’s not a question of should we be using them—but why aren’t we?”
— JANA IVANIDZE, MD, PHD
Barriers to a Breakthrough Tool
Another technique in use is vessel wall (VW) MRI. An American Society of Neuroradiology (ASNR) survey found that over 50% of neuroradiology groups use the technique for intracranial vasculopathy characterization and differentiation. Furthermore, 41% of survey respondents expressed their belief that vascular wall imaging had a direct and positive impact on patient management.
“Luminal imaging such as CT or MR angiography evaluates changes in the vessel lumen like narrowing or irregularity,” explained Laura Eisenmenger, MD, a neuroradiologist at the University of Wisconsin School of Medicine and Public Health in Madison. “However, VW MRI is unique in that it evaluates the vessel wall itself, where the pathology is actually occurring.”
The question then is, if VW MRI is so beneficial, why isn’t everyone using it?
According to Dr. Eisenmenger, there are some barriers to implementing the technique. “VW MRI requires specialized sequences to produce high resolution imaging, which necessitates longer scan times,” she said.
Another challenge is that not every radiologist is comfortable reading VW MRI. Dr. Eisenmenger noted this will likely change as more educational opportunities in the technique become available.
“Despite any shortcomings, when it comes to gaining unique insights on vessel wall pathology and disease progress, next generation cerebrovascular imaging is simply a game changer,” Dr. Eisenmenger added.
Next Decade, Not Next Year
While Drs. Ivanidze and Eisenmenger see these targeted approaches as game changers that are ready for primetime, others are not quite ready to make the leap.
“One of the powers of PET/ theranostics is that it has the potential to be very sensitive and very specific,” said JP Yu, MD, PhD, also a neuroradiologist at the University of Wisconsin School of Medicine and Public Health. “Unfortunately, with clinical and quantitative MRI, we haven’t yet reached that potential.”
That’s because MRI suffers from what Dr. Yu called a ‘specificity gap’.
“While current state-of-the art clinical and quantitative imaging excel at capturing the anatomy and physiology of disease, unlike PET, they are much less specific and poorly represent neurobiology at the gene expression and cellular levels,” he explained. “Until we bridge this gap in image specificity and specifically, neurobiology, quantitative neuro MRI simply isn’t tailored for the precision medicine applications we aspire to have.”
According to Dr. Yu, the best way to start bridging this gap is to build translational imaging research programs that include molecular and cellular neuroscience as well as quantitative imaging. It also means recruiting and supporting a new generation of neurobiologists, data scientists and physicists who are excited to push the boundaries of this growing field.
“The transition from qualitative to quantitative imaging is a long one, and while we’re making progress, we’re looking at a timeframe of next decade, not next year,” he said.
Neuroradiology and Disease-Specific Structured Reporting
Techniques like theranostics for brain tumors or cerebrovascular imaging aren’t the only controversial topics in neuroradiology. The way in which those imaging techniques are reported can also cause debate.
“Because neuroradiology is used to understand disease processes, it tends to lend itself to disease-specific structured reporting,” Dr. Weinberg said.
Today, most radiology reports have a narrative and are written like a story, Dr. Weinberg noted. While they all have an introduction and conclusion, they are not always the same and may depend on the writer.
With disease-specific structured reporting on the other hand, radiologists specifically list the most important things. “For a brain tumor, you might need to report whether there is new swelling, if the tumor is bigger, smaller or the same and if there is anything else to worry about,” Dr. Weinberg explained. “Then you do that in the same order every time.”
The benefit of taking a structured approach to reporting is that it makes it easier for the doctors reading the reports to understand what is happening with a patient. However, because such reporting is indeed different, it has faced some resistance, if not outright hostility.
From emerging imaging techniques to evolving reporting standards, neuroradiology is evolving toward greater precision. While challenges remain—from technical limitations to differing opinions on best practices—the field continues to advance.
“Despite the controversies, all these neuroradiology techniques and ways of reporting aim to help radiology become more exact, have greater accuracy and help doctors and patients make better decisions,” Dr. Weinberg concluded.
For More Information
Read previous RSNA News stories on neuroradiology:
- Spotting Stroke Markers Helps Radiologists Ward off Risks for Future Adverse Events
- Top 10 Most-Feared Diagnostic Errors for Trainees in Pediatric Neuroradiology Emergencies
- Research Into MRI Contrast Agent Wins Neuroradiology Research Award