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Best Brain Imaging Tests

Posted on May 28, 2013 | No Comments on Best Brain Imaging Tests

No matter how true the statement “our world is getting sicker” is, there is still hope behind these daunting fads. Alongside the intensification of health problems and aggravation of health risks are the continuous notable industrial and technological advancements—particularly in the medical field.

It can be noted that various ultra-modern medical equipment are already made available in the market for hospitals to use. These sets of equipment correspond to specific health needs of each patient.

One specific patient population consists of those with diabetes who are at high risk of cognitive deficits or dysfunction. What imaging tests would be best to look at these patients’ brains?

Brain disorders and tests
Dr. Josephine Torres-Tuason, a diplomate of the Philippine College of Physicians, fellow of the Philippine Neurological Association, and section head of the Neurology Department of the Asian Hospital and Medical Center (AHMC), explains that patients with diabetes “are really prone to small vessel disease”.

Small subcortical and periventricular infarcts, which can turn into “silent small strokes” once in a while, are very rampant among patients with diabetes. And because these silent strokes are so small, Dr. Tuason affirms, “They don’t manifest clinically. What happens here is, over the years of having diabetes, especially those with uncontrolled cases, they develop small strokes and once they become really plenty, they coalesce and develop some complications.”

“That’s the time that they develop some neurological manifestations,” outlines Dr. Tuason.

These so-called neurological symptoms could be in the form of weakness, gait problems, and memory loss
or dementia. According to Dr. Tuason, to appreciate these abnormalities, “It’s better that we do neuro imaging. And the best, of course, is MRI (Magnetic Resonance Imaging).”

The MRI is a radiology technique that uses a magnetic field, radio waves and a computer to create detailed images of body tissues and organs. It can even make 3D images that can be viewed from many different angles. This scan can be used to detect or screen for diseases in the body such as stroke and tumors of the brain.

In particular, Dr. Tuason explains that among patients with diabetes, “if they present problems with memory loss or weakness, blurred speech, or any neurological deficit that may pertain to the brain, I request for an MRI.”

She asserts that in utilizing MRI, “There’s a clearer view of what’s going on. And these are the things that we usually see—periventricular or subcortical infarcts.”

According to Dr. Tuason, there are two major things in which MRI could be used for: (1) for detecting or evaluating general chronic diseases or illnesses in the brain, and (2) looking for lesions in the brain stem or the posterior fossa.

She asserts, “With MRI, I could get a more lucid view of the cases.” Further, AHMC Chairman of the Department of Radiology Dr. Vicente Romano outlines that MRI is advisable to use for screening or looking into soft tissues. “MRI is much better to use because it is more specific since it has tissue differentiation,” he says.

While MRI is better to use for screening in chronic brain diseases, Dr. Tuason states that for acute problems like cerebral hemorrhage, head trauma, and acute infarcts, CT Scan (Computerized (or computed) tomography) is recommended.

“Since it’s easier to undergo CT Scan, we usually use that for patients with acute problems. Like if the patient is restless and if you’re trying to rule out acute stroke and you want immediate intervention, we use this test,” explains Dr. Tuason.

There are, however, specific cases wherein neither an ordinary MRI nor CT Scan is advisable to use—such as diagnosing or treating aneurysm.

Dr. Tuason clarifies that aneurysm is a vascular disease that “cannot be normally seen through an average MRI or CT Scan.” While clinicians can have tell-tale signs of a ruptured aneurysm when they see hemorrhage in the subarachnoid space, which can be appreciated better on CT Scan, “you will still have high index of suspicion that it may be secondary to a ruptured aneurysm. The next step here is an angiography—so of course the gold standard is a four-vessel cerebral angiogram wherein you have to sedate the patient and insert a needle in the inguinal area and then visualize the brain.”

CT angiogram (Computed Tomography Angiography), “is the counterpart of MRA for CT Scan,” explains Dr. Tuason. While it is acceptable to use for screening patients, “the problem with this is you have to give a dye to patients wherein some are allergic to it and react negatively.”

That is why in requesting for CT angiogram, Dr. Tuason says they have to be very careful about giving dye for imaging, particularly among patients with diabetes, since it has a side effect on the kidney. “If the patient has diabetes, we always get the creatinine level because the dye is toxic to the kidney and can cause renal failure,” maintains Dr. Tuason.

She stresses, however, that if a clinician just wants to know whether the patient has aneurysm or not; for routine purposes only, “he can opt for the non-invasive way of diagnosing it through the MRA (Magnetic Resonance Angiography).”

MRA, explains Dr. Tuason, is the same procedure with MRI; the only disparity is that it will look at a different aspect of the brain.

“MRI will look at the brain parenchyma. MRA will look at the blood vessel in the brain. So it’s in the MRA wherein you can see aneurysm and arteriovenous malformations or AVM,” she says.

Functional vs. Structural
When it comes to determining and treating the morphologic anatomy of the brain, Dr. Romano says structural brain imaging tests, which include MRI, CT Scan, and angiography, are used.

Specifically, these tests are utilized to detect “visible abnormalities of cerebral structure, such as brain tumors, blood clots, malformations or scar tissue that might be causing seizures, and helps establish the etiology of the disease.”

Meanwhile, functional brain imaging tests “identify abnormalities in brain metabolism”. These include the single photon emission computed tomography (SPECT), positron emission tomography (PET), and functional MRI (fMRI).

Dr. Tuason, however, claims that though functional brain imaging techniques are already on hand, “They are not often used; not unless the case is very hard to manage.”

Dr. Romano adds, “This is among the latest developments in the field. Medyo bago lang ‘yan (This is quite new).”

Which is best?

Now which among the brain imaging tests is the best?” It depends on the case,” explains Dr. Tuason.

There are various things clinicians should take into consideration prior to requesting for what kind of test their patients are best to undergo—one is the financial capability of the patients.

“Here in the Philippines, you always consider the financial aspect. If the patient’s case can be detected through a CT Scan, it’s way cheaper, then go. But, if you’re going to deal with chronic diseases, MRI should be done,” she explains.

None can really say which one is the best, as what both doctors claim, each brain imaging test corresponds to the differing and distinctive needs of each patient.

“We need both,” Dr. Tuason maintains.

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