Open Access Articles – A Novel Neuroimaging Model to Predict Early Neurological Deterioration After Acute Ischemic Stroke

Journal Name: Current Neurovascular Research

Author(s): Yen-Chu Huang*, Yuan-Hsiung Tsai, Jiann-Der Lee, Jen-Tsung Yang, Yi-Ting Pan.


Objective: In acute ischemic stroke, early neurological deterioration (END) may occur in up to one-third of patients. However, there is still no satisfying or comprehensive predictive model for all the stroke subtypes. We propose a practical model to predict END using magnetic resonance imaging (MRI).

Method: Patients with anterior circulation infarct were recruited and they underwent an MRI within 24 hours of stroke onset. END was defined as an elevation of ≥2 points on the National Institute of Health Stroke Scale (NIHSS) within 72 hours of stroke onset. We examined the relationships of END to individual END models, including: A, infarct swelling; B, small subcortical infarct; C, mismatch; and D, recurrence.

Results: There were 163 patients recruited and 43 (26.4%) of them had END. The END models A, B and C significantly predicted END respectively after adjusting for confounding factors (p=0.022, p=0.007 and p<0.001 respectively). In END model D, we examined all imaging predictors of Recurrence Risk Estimator (RRE) individually and only the “multiple acute infarcts” pattern was significantly associated with END (p=0.032). When applying END models A, B, C and D, they successfully predicted END (p<0.001; odds ratio: 17.5[95% confidence interval: 5.1– 60.8]), with 93.0% sensitivity, 60.0% specificity, 45.5% positive predictive value and 96.0% negative predictive value.

Conclusion: The results demonstrate that the proposed model could predict END in all stroke subtypes of anterior circulation infarction. It provides a practical model for clinical physicians to select high-risk patients for more aggressive treatment to prevent END.

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Most Cited Articles – “MRI of Focal Liver Lesions”

Journal: Current Medical Imaging Reviews

Author(s): Nils Albiin

cmirAbstract: Magnetic resonance imaging, MRI has more advantages than ultrasound, computed tomography, CT, positron emission tomography, PET, or any other imaging modality in diagnosing focal hepatic masses. With a combination of basic T1 and T2 weighted sequences, diffusion weighted imaging, DWI, and hepatobiliary gadolinium contrast agents, that is gadobenate dimeglumine (Gd-BOPTA) and gadoxetic acid (Gd-EOB), most liver lesions can be adequately diagnosed. Benign lesions, as cyst, hemangioma, focal nodular hyperplasia, FNH or adenoma, can be distinguished from malignant lesions. In a non-cirrhotic liver, the most common malignant lesions are metastases which may be hypovascular or hypervascular. In the cirrhotic liver hepatocellular carcinoma, HCC, is of considerable importance. Besides, intrahepatic cholangiocarcinoma and other less common malignancies has to be assessed. In this review, the techniques and typical MRI features are presented as well as the new algorithm issued by American Association for the Study of the Liver Diseases (AASLD).

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Gadolinium: The MRI Agent Linked to Brain Abnormalities

Magnetic resonance imaging (MRI) is one of the better choices if you need a diagnostic imaging procedure performed. Unlike CT scans or X-rays, an MRI does not use ionizing radiation that may cause DNA damage or cancer.

Story at-a-glance

  • The use of gadolinium-based contrast agents for enhanced MRIs has been linked to hypersensitivity in certain brain regions, with unknown consequences
  • The use of gadolinium-based contrast agents is linked to the development of Nephrogenic Systemic Fibrosis (NSF) in patients with severe kidney disease
  • The long-term effects of gadolinium-based contrast agents are unknown; only use contract agents if they are absolutely necessary (often they are optional and an MRI can be effectively performed without their use)

Instead, a strong magnetic field and radio waves produce cross-sectional images of your organs and other internal body structures. In some cases, however, a gadolinium contrast medium is used to make the images clearer (this is typically called an enhanced MRI).

There are risks involved when contrast agents are used, including potential brain abnormalities revealed by a new study, so it’s important to use extreme caution and only get an enhanced MRI if it is absolutely necessary.

Gadolinium-Based Contrast Agents Linked to Brain Hypersensitivity

Gadolinium is a paramagnetic metal ion that moves differently within a magnetic field. When used during an MRI, it may make certain tissues, abnormalities, or diseases more clearly visible.

However, because the gadolinium ion is known to be toxic, it is chemically bonded with non-metal ions when used during MRIs to allow it to be eliminated from your body before it is released in your tissues.

For the first time, a new study has shown that the gadolinium may not be immediately eliminated and may instead persist in your body.1 The study compared brain images of patients who had undergone six or more contrast-enhanced MRI brain scans with those of patients who had received six or fewer unenhanced scans.

It revealed areas of high intensity, or hyperintensity, in two brain regions (the dentate nucleus (DN) and globus pallidus (GP)), which correlated with the number of gadolinium-based enhanced MRIs.

It’s unknown at this time what the hyperintensity may mean, however hyperintensity in the DN is associated with multiple sclerosis. It’s now being suggested that this hyperintensity may be the result of the large number of enhanced MRI scans often received by multiple sclerosis patients. Hyperintensity of the GP, meanwhile, is linked with liver dysfunction. The study’s lead author noted:2

“Hyperintensity in the DN and GP on unenhanced MRI may be a consequence of the number of previous Gd-CM administrations… Because gadolinium has a high signal intensity in the body, our data may suggest that the toxic gadolinium component remains in the body even in patients with normal renal function.”

Gadolinium-Based Contrast Agents Also Linked to Life-Threatening Skin Thickening

Among patients with severe kidney disease, the use of gadolinium-based contrast agents is linked to the development of Nephrogenic Systemic Fibrosis, or NSF. NSF was first identified in 1997 and while its cause is unknown, it’s only been reported in those with kidney disease.

NSF causes skin thickening that can prevent bending and extending your joints. It can also develop in your diaphragm, thigh muscles, lung vessels, and lower abdomen. Along with causing decreased mobility of joints, NSF can be fatal.

Because of this connection, the US Food and Drug Administration (FDA) requested that the manufacturers of all five gadolinium-based contrast agents (Magnevist, MultiHance, Omniscan, OptiMARK, and ProHance) add a boxed warning and a new Warnings section to their labels to describe the risk of developing NSF.3

I recommend that everyone use caution with gadolinium-based contrast agents and only use them when absolutely essential. Even if you’re healthy, these contrast agents may cause side effects like life-threatening allergic reaction, blood clots, blood vessel irritation and skin reactions, including hives, itching, and facial swelling.

However, if you have kidney disease, using caution is particularly important. Often the use of contrast agents is optional and an acceptable MRI can be conducted without the use of a contrast. If you have been administered a gadolinium-based contrast agent and you have kidney disease, be on the alert for the following symptoms of NSF, and contact your health care provider immediately if you experience them:

Swelling, hardening, and tightening of your skin Reddened or darkened patches on the skin Burning or itching of your skin
Yellow raised spots on the whites of your eyes Stiffness in your joints; problems moving or straightening arms, hands, legs, or feet Pain deep in your hip bones or ribs
Muscle weakness

Other MRI Risks You May Not Know About

As mentioned, MRIs are preferable to CT scans because they do not use ionizing radiation. However, it’s still wise to minimize their use as much as possible, in part because the effects of exposure to MRIs’ strong magnetic field are largely unknown.

Research has shown that there are biological effects in the human body, however, including to the retina, pineal gland, and some cells in the paranasal sinuses.4Time-varying magnetic fields may also interfere with your nerve cell function and muscle fibers, while MRIs also produce acoustic noise that has been known to cause temporary (and, rarely, permanent) hearing loss.

Finally, due to the strong magnetic field produced, an MRI can become deadly if metal objects in the room are not properly secured or you have medical devices such as a pacemaker in your body. There is at least one report of a child being killed during an MRI due to an unsecured metal oxygen tank.5

The MUST-KNOW Rule if You Are Getting an MRI

But the KEY here is to avoid using MRI scans with contrast unless ABSOLUTELY necessary. Many times, physicians will order these tests just to be complete and cover their butts from a legal perspective. If that is your case, then simply refuse to have the test done with contrast. If necessary, consult with other physicians that can provide you with a different perspective.

If You Need an MRI, It Pays to Shop Around

While I always recommend your being very judicious in your use of medical diagnostic procedures, there are certainly times when it is appropriate and useful for you to have a certain test. But many people don’t realize that the fees for these procedures can vary tremendously, depending on where they are performed. Hospitals tend to be the MOST expensive option for diagnostics and outpatient procedures—sometimes by an enormous margin.

Freestanding diagnostic centers are alternative places to obtain services, such as lab studies, X-rays, and MRIs, often at a fraction of the cost charged by hospitals. You may have driven by some of these centers in your city. Private imaging centers are not affiliated with any particular hospital and are typically open for Monday through Friday business hours, as opposed to hospital radiology centers that require round-the-clock staffing.

Hospitals often charge higher fees for their services to offset the costs of their 24/7 operations. Hospitals also may charge exorbitant fees for high-tech diagnostics, like MRIs, to subsidize other poorly reimbursed services. And, hospitals are allowed to charge Medicare and other third-party insurers a “facility fee,” leading to even more price inflation. So, if you do find that you need an MRI, don’t be afraid to shop around. With a few phone calls to diagnostic centers in your area, you could save up to 90 percent over what a hospital would charge for the same service.

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