Ajit Shankaranarayanan PhD, Global MR Neuro Applications Manager, Applications & Workflow at GE Healthcare, took some time out to answer questions about his research into brain tumors and what he thinks the future holds in the areas of detection and diagnosis. A MR physicist by training, Ajit has worked in non-contrast perfusion and motion insensitive imaging areas. His current role involves managing a global team engaged in development of advanced neuro MR applications.
Firstly how are brain tumors diagnosed and why is early detection and diagnosis so crucial in its management and treatment? How do the types of brain imaging technologies help researchers increase understanding of the causes and progression of brain tumors?
The clinical presentation of various brain tumors is best appreciated by considering the relationship of signs and symptoms to anatomy. General signs and symptoms include headaches, seizures, visual changes etc. Whether primary, metastatic, malignant, or benign, brain tumors must be differentiated from other space-occupying lesions such as abscesses, arteriovenous malformations, and infarction, which can have a similar clinical presentation. Brain imaging technologies help enable the physician to non-invasively detect and differentiate (to certain extent) the tumors. They also help facilitate effective treatment planning for the neurosurgeons.
CT/MRI scanning can help in early diagnosis, uncovering valuable information on tumor location, size and metabolic activity. How have these technologies and others contributed to the more personalized cancer treatment and management decisions?
Computed tomography (CT) and magnetic resonance imaging (MRI) have complementary roles in the diagnosis of small tumors in the brain and/or spinal cord. CT is typically faster than MRI and is therefore desirable for evaluating clinically unstable patients and is superior for detecting skull lesions, and hyperacute hemorrhage (bleeding less than 24-hours old). On the other hand, MRI has superior soft-tissue resolution and can better detect tumor enhancement, and associated findings such as edema. High-quality MRI is also the modality of choice in the evaluation of spinal cord lesions due to its high sensitivity.
For patients who have completed therapy, single-photon emission computed tomography (SPECT) and positron emission tomography (PET) may be useful in determining tumor recurrence. Biopsy confirmation to corroborate the suspected diagnosis of a primary brain tumor is critical, whether before surgery by needle biopsy or at the time of surgical resection, except in cases where it is clear that it’s a benign tumor.
Radiologic patterns may be misleading, and it is necessary to do a biopsy to rule out other causes of space-occupying lesions, such as metastatic cancer or infection. CT and MRI can be used to guide the needle to complete a biopsy in many locations in the brain.
Since the 1990s, fMRI has come to dominate the brain mapping field due to its low invasiveness, lack of radiation exposure, and relatively wide availability. What technologies do you think have surpassed functional MRI (fMRI) if any?
fMRI is an MRI method used for non-invasively looking at the function and activity in the brain by measuring blood flow. During an fMRI procedure, the patient is asked to perform a task while their brain is imaged. This enables the clinician to view functionality in the brain, for example, which parts are active or inactive. The clinician can then determine if the brain is functioning normally and localize the abnormality. Tractography is a method to map the white matter tracts of the brain using images obtained by MRI.
fMRI is a non-invasive technique used by surgeons for planning the treatment of a brain tumor (the other being tractography). I do not think any technology has surpassed fMRI for this specific utility. However within the fMRI field researchers are moving to a new technology called resting state fMRI where the patient has to just lie on the table and not participate in activities like finger tapping etc.
Effective treatments for brain tumors have developed into products that combine imaging, molecular diagnostics and healthcare IT. Does this approach demonstrate what a complex and multifaceted disorder brain tumors are? What do you think could be the biggest innovation in brain tumor research/detection/treatment that you see coming within the next decade or so?
Yes, I agree that brain tumors are complex and multifaceted and because of that, the diagnosis/treatment and follow-up requires multiple technologies to come together.
The biggest potential for innovation in brain tumor detection (as in other brain diseases) is the discovery and development of biomarkers that will enable tumor differentiation much more accurately. This is the critical step in triaging patients and I see lots of potential for innovation here. Multimodality systems will also certainly help here and we are excited to see how new technology like this will advance our understanding.
Finally from a clinical standpoint, the rapid increase in targeted and patient-specific cancer therapies is driving demand for molecular diagnostics. Could you outline any other drivers that are increasing the demand for new and effective brain tumor detection and treatment technology?
The healthcare environment now demands an outcome-based form of medicine and is a critical driver in demanding higher efficiency, specificity and sensitivity of technologies being used for detection and treatment of brain tumors.
We are working closely with key researchers to advance our understanding of industry to provide tools to enhance diagnostic capabilities. It makes sense that the diagnostic and prognostic power of imaging technologies need to be better than where we are now (for any disease). That is why integrating information from imaging and non-imaging modalities like molecular diagnostics makes for a powerful solution both for diagnostics and therapeutics.