Dynamic Nuclear Polarization MRI - Essay Example

?Dynamic Nuclear Polarization MRI Introduction: The research paper at hand focuses on MRI, in specific terms with dynamic nuclear polarization MRI. First, the paper will define MRI and dynamic nuclear polarization, and then it will talk about the relation between the two. Next it will give a history about the development as well as uses of MRI, that is, in terms of how much it has been beneficial in various fields. The paper will then focus on the uses of polarizationMRI, its potential, and also different recommendations to reach thispotential in the future. Through the analysis of various research materials, it becomes clear that MRI has advanced profoundly over the last few decades. However, the medical fraternity is yet to tap its full potential by applying this technique for various tests and investigations for diagnosis of diseases. Definition: Magnetic Resonance Imaging (MRI) is one of the most increasingly used clinical diagnostic tools, and it works by using a “strong magnetic field” to produce “high- resolution anatomical information with excellent soft-tissue contrast” (Metcalfe et al 2013: 2). Dynamic Nuclear Polarization(DNP), which is based on the overhauser effect, is a commonly employed method,in the medical field in terms of MRI, which “allows polarization enhancement by two-four orders of magnitude” without a rise in the “polarizing field strength” (Zotev et al n.d., 1). As is evident from the above, both MRI and DNP are basically related to the medical or clinical field, and they are primarily exercised in order to reach a particular diagnosis after examining the symptoms present in a patient’s problem areas.There are different kinds of approaches within MRI, namely, “Dynamic Contrast Enhanced (DCE) MRI, Diffusion Weighted (DW) MRI, Magnetic Resonance Spectroscopic Imaging (MRSI),” gradient echo pulse sequence as well as dynamic nuclear polarization MRI (Metcalfe et al 2013: 2). Although there are various techniques to MRI, the paper shows how polarization is advanced and rises above other techniques to provide accurate imaging of different tissues. History of MRI: MRI, the non-invasive clinical diagnostic tool, owes its origins to some physics experiments that were carried out to measure “properties of the nuclear spins of hydrogen atoms” over 60 years ago (Nacher 2007: 1). These experiments not only observed the magnetic characteristics of atomic nuclei through the use of both liquid and solid samples,but also found a way to record these properties and further develop on them. Soon Nuclear Magnetic Resonance (NMR) was discovered, and this pioneered a lot of changes in the fields of physics and also chemistry over the following 20 years.Although NMR rose as a “powerful investigative tool” in various spheres, it was only in “1973” that it was used to “generate true (2-D) images”with the help of a “magnetic field gradient” (Nacher 2007: 2). Thus, researchers carried out various studies and scientists conducted different experiments, which were all significant contributions in the field of MRI, and ultimately MRI was developed as a tool employed in clinical trials. Backed by the curious minds of researchers as well as the profit seeking appetite of business giants, the first commercial MRI scanner was launched in “1983,” and it only further developed to become a “routine diagnostic tool,” its popularity skyrocketing ever since (Nacher 2007: 3). Compared to its counterparts that utilize invasive approaches, such as proton imagingwhere gadolinium based contrast agents are used, MRI does not cause any problem to patients suffering from certain diseases. For instance, patients with “impaired renal function” cannot be given contrast mediaas it would cause further problems for them (Zhou 2012: 134). However, it is not possible to develop high quality images of certain tissues just by using traditional MRI techniques. Thus, in order to combat this issue, new techniques were discovered and this included DCE MRI, DW MRI, MRSI, MRI with polarized gases etc. Comparison of Different MRI Techniques: The different approaches or techniques of MRI can be basically classified under two heads, namely, proton based MRI and MRI with polarized gases. The proton based technique is the most commonly used approach in MRI, and it involves developing images of body tissues with respect to hydrogen protons. Hydrogen is the most abundant element found in the body of a living being and it exists in the form of both water and fat, thus it is quite easy to perform imaging using Hydrogen.In practical application, how MR works here is that it changes “sequence parameters” and through this it shows the “differences in either “longitudinal” (T1) or “transverse” (T2) relaxation times of fat and water, producing large variations in contrast” (Metcalfe et al 2013: 2). Although the T1 and T2 imaging methods are highly useful in various clinical applications, they do not provide “sensitive or specific diagnosis and localization of either prostate or breast cancer”(Metcalfe et al 2013: 2). Therefore, in order to enhance the capabilities of MRI, various “advanced techniques” were developed, which not only gave images, but also helped attain clinical information such as “tumor response” (Metcalfe et al 2013: 2).These newly developed approaches came to be known as “functional MRI,” and this maybe defined as “techniques that probe the status of the tumor itself” (Metcalfe et al 2013: 3). The different techniques that come under functional MRI are as abovementioned DW, DCE, MRSI etc. MRI primarily is carried out by examining the nuclear spin of proton atoms, however, in the case of certain organs, due to high amount of air distributed throughout the tissues, the protons lose their density. Thus, in such cases, conventional MRI is not enough to get the most visible pictures that depict “high spatial and temporal resolution” (Salerno et al 2001: 33). However, MRI when coupled with noble gas produces tremendous imaging that not only shows the structure of the respective organs clearly, but also reveals significant data about them, which is then used for accurate pathological inferences. The use of noble gas for MRI has taken clinical diagnosis to the next level, as it helps in examining complicated tissue structure of organs such as lungs as well as the human brain. This was so because it was impossible to get such clear and revealing images with the use of traditional proton based MRI sequences. It was in “1994” that a “Princeton-Stony Brook collaboration” demonstrated that the noble gases Helium and Xenon could be used to “image the lung airways” (Nacher 2007: 14).The technique was further enhanced by hyperpolarization, which is a “high, out of equilibrium nuclear polarization” that solves the problem of low density in MRI by providing a “high enough magnetization” (Nacher 2007: 15). Through hyperpolarization, the “sensitivity” of MRI is increased from “1000 to 10000 times” by introducing a nuclei whose “spin population” has been “driven to a very high degree” (Metcalfe et al 2013: 4). Thus, it is this very fact that makes polarization prove more beneficial than other techniques for imaging organs such as lungs and brain, where the air volume is quite high. Various Uses of Polarization MRI and Proton Based MRI: The first and foremost area where MRI is highly beneficial is in cancer management apart from other clinical diagnosis that it provides. MRI is considered as the “superior imaging modality for diagnostic purposes when assessing the brain,” as it gives a “better visualization of tumor” than in other imaging techniques (Metcalfe et al 2013: 5). Thus, MRI helps in performing “high-precision intracranial radiotherapy” in terms of the brain (Metcalfe et al 2013: p5). MRI has also proven to be beneficial for the treatment of arteriovenous malformations with the help of the technique called magnetic resonance angiography. In case of head and neck, MRI helps in detecting “lymphogenicmetastesis in head and neck cancer patients” (Metcalfe et al 2013: 7). In the case of patients suffering from breast cancer, when they undergo MRI, the imaging is much more sensitive than when done in mammography, thus even the slightest breast abnormalities are easily available through MRI. Different studies have revealed that nuclear polarization in terms of Helium gas is very promising as Helium ventilation differentiates “healthy lungs from those with pathologies such as chronic obstructive pulmonary disease (COPD), asthma and cystic fibrosis (CF)” etc (Salerno et al 2001: 33). MRI further plays the significant role of a “patient-specific ITV for planning of lung cancers for radiotherapy” (Metcalfe et al 2013: 10).MRI is highly useful not only for diagnosis, but also tumor delineation, differentiating functional normal tissues etc, which is very important for radiotherapy treatment planning. The other branch of MRI, functional MRI, is seen to further help in identifying the different functional organs at risk (fOAR). Potential of Polarization MRI: It is seen that nuclear polarization of gases is yet to be clinically approved for use in the US, however, various developments of the same will prove its feasibility and soon use of polarized gas based MRI can be fully approved. The current challenges faced in polarization of gases is the large amount of gas that needs to be used in the process, thus the economic feasibility of the same is in question. Thus with the reduction in the amount of gas used, as well as developing ways to recycle the gas may make it economically viable, and thus be deemed standard procedure in clinical practice. MRI, specifically polarization MRI has a lot of untapped potential in the medical and clinical field as well as other relative fields.One of its potential is characterized by the deployment of MRI to “avoid normal tissues in lung cancer radiotherapy planning,” and this is seen to be an “emerging area of research” (Metcalfe et al 2013: 10). It can be done with the help of “inert hyperpolarized helium-3 gas,” which when inhaled, shows the lung functioning by “selective display of ventilated air spaces” (Metcalfe et al 2013: 10). Furthermore, hyperpolarized gas MRI sequences have the potential to “provide a comprehensive morphologic and functional assessment of the lung” (Salerno et al 2001: 33). Another potential seen for nuclear polarization MRI is the “dissolved-phase imaging,” which can be attained when the polarization levels of Xenon reach “those currently achievable”Helium (Salerno et al 2001: 42). Moreover, various investigations have proved that “dynamic imaging of ventilatory function” with the use of hyperpolarized gases has the “potential to provide unique information on the physiology and pathophysiology of the lung” (Salerno et al 2001: 667).MRI is not the currently prescribed the standard methodology “for diagnosis of prostrate cancer,” and this may change in the following years, owing to the constant research and developments taking place in the medical field (Metcalfe et al 2013: 11).On the other hand, the systematic progression of MRI is the “clinical prototyping of hybrid MRI-linear accelerator systems that will provide the ultimate in adaptive radiotherapy” (Metcalfe et al 2013: 14). Recommendations to Achieve its Potential: The potential of dynamic nuclear polarization or hyperpolarization MRI can be reached first if further studies and researches are conducted focusing on the same.There is a need for appropriate technology to be developed that will enable efficient as well as cost effective method for production of the polarized gas materials, and furthermore storage facilities should be created that would help store these gases in order to recycle them later. Furthermore, there is a need for “coherent strategies to standardize and harmonize methods for hyperpolarized MR data acquisition and dis- play”(Kurhanewicz et al 2011: 93). On the other hand, researchers must also develop a consensus that would “validate these emerging HP methods to help accelerate clinical research” (Kurhanewicz et al 2011: 93). Conclusion: The paper at hand focuses on MRI in terms of dynamic nuclear polarization MRI. The definitions of the terms have been provided and a history of the development of the techniques has also been given. The paper then compares polarization MRI techniques with other techniques. Later on the various current uses of polarization MRI have been detailed and the next section talks about the potential for polarization MRI. Lastly recommendations have been provided that will help reach the full potential of polarization MRI. Therefore, the paper makes it clear that MRI is highly useful and DNP MRI is more beneficial than other MRI approaches, as it is a better prognostic clinical tool. However, MRI is yet to advance more and reach its full potential and evidently, as it has developed through all these decades, the constant efforts and commitment of researchers will help it develop further. References Kurhanewicz, J., Vigneron, D. B., Brindle, K., Chekmenev, E. Y., Comment, A., Cunningham, C. H., Deberardinis, R. J., Green, G. G., Leach, M. O., Rajan, S. S., Rizi, R. R., Ross, B. D., Warren, W. S., Malloy, C. R.2011. Analysis of Cancer Metabolism by Imaging Hyperpolarized Nuclei: Prospects for Translationto Clinical Research. Cancer Metabolism by Imaging Hyperpolarized Nuclei, Vol.13(2): pp.81-97. Retrieved November 3, 2013, from Metcalfe, P., Liney, G. P., Holloway, L.,Walker, A., Barton, M., Delaney, G. P., Vinod, S., Tome, W. 2013.The Potential for an Enhanced Role For MRI in Radiation-therapy Treatment Planning.Technology in Cancer Research and Treatment.Retrieved November 3, 2013, from < http://www.tcrt.org/mc_images/category/4331/93-metcalfe_tcrt_aop_2013.pdf > Nacher, P. J., 2007. Magnetic Resonance Imaging: From Spin Physics to Medical Diagnosis. Quantum Spaces. Retrieved November 3, 2013, from Salerno, M., Altes, T. A., Mugler III, J. P., Nakatsu, M., Hatabu, H., Lange, E. E. 2001.Hyperpolarized Noble Gas MR Imaging of the Lung: Potential Clinical Applications. European Journal of Radiology, Vol.40: pp.33-44. Retrieved November 3, 2013, from Salerno, M., Altes, T. A., Brookeman, J. R., Lange, E. E., Mugler III, J. P. 2001. Dynamic Spiral MRI of Pulmonary Gas Flow Using Hyperpolarized 3He: Preliminary Studies in Healthy and Diseased Lungs. Magnetic Resonance in Medicine, Vol.46: pp.667-677. Retrieved November 3, 2013, from Zhou, Xin. 2012. Hyperpolarized Xenon Brain MRI. Advances in Brain Imaging. Retrieved November 3, 2013, from Zotev, V. S., Owens, T., Matlashov, A. N., Savukov, I. M., Gomez, J. J., Espy, M. A., n.d.Microtesla MRI with Dynamic Nuclear Polarization.Laureate Institute for Brain Research. Retrieved November 3, 2013, from Read More