Evaluation of the Use of Gadolinium Enhanced Images - Dissertation Example

?Evaluation of the Use of Gadolinium Enhanced Images to Obtain Magnetic Resonance Venography (MRV) for the Detection of Sagittal Sinus Thrombosis Abstract: This paper seeks to compare the efficiency between the use of magnetic resonance venography (MRV) with and without gadolinium for the detection of sagittal sinus thrombosis disease, a disease characterized by blood clot in the brain veins. The use of contrast agents can entail many side effects on the patient’s health and will also necessitate additional exam time as well as cost. Therefore, this study tests MRV without gadolinium as an alternative technique by using the blood flow as a natural contrast media. A sample comprising 10 to 20 patients with suspected sagittal sinus thrombosis will be examined for testing the hypothesis being proposed by this study, by evaluating the process of MRV with and without using contrast agents. Results from the tests using both methods will be analyzed by different radiologists and by using Imagej software. Evaluation of the Use of Gadolinium Enhanced Images to Obtain Magnetic Resonance Venography (MRV) for the Detection of Sagittal Sinus Thrombosis Introduction: Sagittal Sinus Thrombosis (SST) is a heart stroke that is caused due to blood clot in the cerebral hemisphere and may manifest itself as a “dense triangle, the dense or filled delta sign” and also it may also involve an “ischemic infraction” with haemorrhages on certain occasions (Antanassova et al. 2012, p.137). The major causes of the disease include genetic prothrombotic conditions such as antithrombin deficiency, protein C and protein S deficiency, Factor V Leiden mutation, prothrombin mutation, homocysteinemia due to gene mutation, acquired prothrombotic condition such as nephritic syndrome, antiphospholid antibodies, homocysteinemia, pregnancy, puerperium, infections like otitis, mastoiditis, sinusitis, meningitis, systemic infectious disease, sarcoidosis, inflammatory bowel disease, Behcet’s syndrome, hematologic conditions such as polycythemia, thrombocythemia, leukaemia, anaemia, and drugs such as oral contraceptives, Asparaginase (130). The use of sophisticated magnetic resonance imaging (MRI) has enabled a better understanding of the “venous occlusion pathophysiology” (130). Therefore, technology has a key role to play in the detection, diagnosis and treatment of the disease based on clinical suspicion. Earlier technology such as catheter angiography, used for intracranial venous system imaging, can be prone to risk factors such as “transient or permanent neurologic complications” and, therefore, 2D magnetic resonance venography (MRV) has been developed, which became popular as it does not involve any invasive procedures (Fu et al. 2010, p. 131). However, it suffers from a limitation of possible “artifactual intravascular signal loss” due to the “saturation of spins or tortuosity and turbulent flow” in sagittal sinus (131). Therefore, in order to overcome the issue contrast enhancement technology has been adopted, which involves the use of 3D gadolinium-enhanced elliptic centric-ordered (3D GEC) MRV (131). Being flow-insensitive, it has the ability to eliminate “flow-related artefacts” that are common to 2D TOF MRV (131). 3D GEC MRV also facilitates reduction of repetition time and “higher spatial resolution” to the images apart from requiring less scanning time (131). However, sophisticated technology often comes with the limiting cost factors and, hence, may not be a feasible proposition for all patients and the use of gadolinium can also have side effects. Objectives of the Study: Research evidence suggests that cerebral venous sinus thrombosis (CVST) is a serious health problem that affects young as well as aged people and is “more common” in developed countries (Azin & Ashjazadeh 2008, p. 82). With a fatality rate of “14.8%” the disease is found in a higher percentage of women than in men, especially due to consumption of oral contraceptives and during pregnancy (86). Due to “increased awareness of the diagnosis” in recent past, coupled with sophisticated techniques in neuroimaging and better treatment facilities, the prognosis of the disease has improved considerably (Stam 2005, p. 1791). Clinical manifestation of the disease can be highly varied but unusual headache or “stroke-like symptoms” in the young to middle aged population must be investigated to rule out the disease, which is usually done through the use of MRI along with MRV (1794). This procedure can show any “hyperintense signal” from the thrombosed sinuses and any abnormal signal with an absence of flow on MRV will suggest the diagnosis of thrombosis (1794). However, if these facilities are not readily available in the clinical setting, alternatives such as CT scan are suggested for initial investigation but the results are not fully reliable. Thus, it can be construed that the procedures of MRI and MRV are highly crucial in the successful diagnosis of SST. There is a general belief that the use of injection such as gadolinium contrast can produce better outcomes for the detection of SST. However, issues like side effects and cost factor are major constraints in its use for this purpose. Thus, it will be of interest not only to the scientific and academic community to determine whether MRV with the use of such elements make any significant difference in the quality of test outcomes or if it can be done by not using it, without compromising the reliability of the results. The purpose of the study, therefore, is to compare the efficacy of brain MRV images by using and without using the injection of gadolinium contrast in the detection of Sagittal Sinus Thrombosis (SST). Thus, it can help in reducing the costs of the procedures as well as rule out negative side effects. Materials and Methods: The study proposes to test the procedures in a sample population of 10 to 20 patients with SST. The material used will include MRI machine of a recent edition of the Invivo 8-Channel Neurovascular Array that is compatible with the GE 1.5T Signa Infinity with Excite Technology. The 8NANGIO MED coil will be used for the contrast. Each patient will be subjected to an MRI routing examination initially with and without gadolinium contrast agent. This will be followed by four sequences of MRV with and without contrast agent. The timeframe of the examination will be about 45 minutes. Thus, the tests will facilitate MRV test results with and without the use of contrast for obtaining the images. The test results so obtained from all the patients will be compared to see the differences in each case. The evaluation of the differences in the result obtained will be done by using the services of expert radiologists to identify the difference in the resolution between two types of images and to determine whether such differences can have any significant impact on the analysis of the test result. In addition, the results obtained from the sample population will also be subjected to an analysis by using ImageJ software as a scientific measurement to study the differences. The objective is to justify the use of contrast media in these cases and to assess whether it is a worthy proposition to inject the patient with contrast media, which may have side effects apart from consuming time and additional high cost. This will also help in determining whether it is necessary to use it or whether best results can be achieved even without using contrast media. Background Information: As discerned from various research papers reviewed during the course of this study, it has been seen that SST is a major health concern in the modern world, which entails mortality if not timely detected, diagnosed and treated. Procedures such as MRI and MRV play a significant role in the detection and diagnosis of the problem and with the help of modern technology these are being commonly used in the modern clinical settings. There has been a general belief that using gadolinium contrast will facilitate better results in MRI and MRV tests. However, research evidence also suggests that MRV is a relatively easy and safe process that produces “accurate” results even when done “without contrast” (Stein n.d, p. 86). On the other hand, the use of contrast agents can have negative impacts on the patients such as side effects and additional high costs apart from being time consuming. Thus, there appears to exist the need to conduct a study on the specific procedures and the results they can produce when tests are done with the use of contrast agents and without using such agents. Thus, the study is justified as it will benefit patients and hospitals as well as those with academic interests. i) Definition of SST and elaboration of the main symptoms and consequences. In simple terms, sinus or cerebral vein thrombosis is a “blood clot in the veins that drains the blood from the brain” (Moll 2011, p. 3). Therefore, sagittal sinus thrombosis or cerebral venous sinus thrombosis, is a form of heart stroke that occurs as a result of blood clot in the cerebral hemisphere, which affects “young adults and children,” unlike usual heart diseases which affect older adults (Stam 2005, p. 1791). There are two types of sagittal sinus thrombosis, namely the superior sagittal sinus thrombosis and the inferior sagittal sinus thrombosis. The former affects the top parts of the cerebral hemispheres due to clotting of blood in the cortical vein, whereas the latter occurs as a result of clotting in the inferior sagittal sinus vein which affects the lower parts of the brain. Sagittal sinus thrombosis can often prove to be fatal as it causes cerebral haemorrhage, thus draining blood from the brain and leading to death. The main symptoms include headache, which is the most common, seizures, and paraplegia, which is usually a disturbance in the functioning of motor and sensory nerves caused due to an injury in the spinal cord or by a condition known as the spina bifida. Other symptoms are hemiparesis, which causes impairment in the functioning of muscles in the arms, legs, face etc in one side of the body, nuchal rigidity that is difficulty in the movement of neck often due to spasm and pain, intracranial pressure, loss of consciousness, which may further evolve to “comatose condition and corticospinal deficits” (Crombe et al. 2003, p. 257). Some of the less common symptoms include “fever, bulbar deficits, sensory deficits, epilepsy, cerebellar symptoms like static and kinetic troubles” etc (Crombe et al. 2003, p. 257). Therefore, these are the main symptoms that show if an individual is suffering from cerebral venous thrombosis. The common cause of venous thrombosis in infants is shock and dehydration, whereas in older children it is due to infections including mastoiditis, and also coagulopathy, which is the inability of the blood to clot. In adults, the major cause is coagulopathy, whereas in women, thrombosis occurs due to pregnancy and oral birth contraception. Other causative factors are identified to be presence of tumour, proximal blood vessels undergoing different trauma etc. Therefore, the aforementioned factors are seen to contribute to the occurrence of the disease of sagittal sinus thrombosis. ii) Identification of what is MRI/MRV and explanation of its process and its coils: Magnetic Resonance Imaging is a highly useful “medical diagnosis tool” that facilitates clear images of internal body parts through non-invasive means and it is widely being employed for the diagnosis of diseases such as STT in recent years (Nacher 2007, p. 1). It uses the “magnetic properties of hydrogen and its interaction” with the external magnetic field and radio waves for producing the images (Faulkner 1996, p. 2). A “strong magnetic field,” which is measured in terms of units known as “Tesla,” is imperative for performing MRI and three types of magnets such as “permanent, resistive and superconductive” are used in the process (2). During the process of scanning, the patient is usually laid on a table between “two plates of magnets” and the magnetic field is produced by these magnets which are constructed from a wire coil (2). (here you can briefly add how can we obtain image of blood flow before you describe it in detail later.) iii) Explanation of what is Neurovascular Coil-GE-1.5 Tesla. The following link will be used to define and to describe it in detail: (You can use more than one source I gave you the link to know which coil I am going to use) (GE Neurovascular Array Coil – Exicte HD 1.5T 2013). The Use of MRI in SST and its Implications: (I see some of them are similar to what you will write in the previous paragraph .Are you going here to describe them in detail ) 1) What is MRI contrast (Gadolinium, component, side effects/Cost) The modern day MRI scanning can primarily be done in two methods, firstly without using contrast agents and the second, using contrast agents. MRI contrast involves using some extra component such as a dye for the scan, thus enabling better imaging in the process. The most commonly employed diagnostic agents or dyes make use of Gadolinium, which is a “rare earth metal” that acts as a “contrast enhancer,” thus making the areas of the body under scan “more visible” (Questions and Answers on the Review of Gadolinium-Containing Contrast Agents 2010, p. 1). MRI, as a “diagnostic imaging modality,” renders several benefits, as it is “non-invasive, delivers no radiation burden” and has excellent “spatial resolution” (Caravan 2006, p. 1). This coupled with the increased visibility that contrast agents offer, MRI scans help in detecting what the exact problem a patient is suffering from and therefore enable appropriate diagnosis. In clinical imaging, basically the hydrogen atoms constituting water present in tissues are observed, thus the use of contrast agents “catalytically shortens the relaxation times of bulk water protons,” making tissues visible more accurately (Caravan 2006, p. 1). Some of the Gadolinium based contrast agents used in MRI scans are “gadopentetate dimeglumine (Magnevist), gadoterate meglumine (Dotarem), gadoteridol (ProHance) gadodiamide (Omniscan), gadobenate dimeglumine (MultiHance), gadobutrol (Gadovist) and gadoversetamide (OptiMARK), Vasovist (gadofosveset)” etc (Runge n.d., p. 1). While some of these agents are ionic in nature, some are non-ionic, and based on their thermodynamic property and kinetic stability different agents are used in different MRI scans. While the contrast agents seem highly relevant in making body tissues more visible, due to the chemical properties of the substances used in dyeing, people often seem to suffer from various side effects. Mild reactions to contrast agents include “nausea, headaches, dizziness, hives, rash, chills, pallor” etc, whereas moderate reactions include “tachycardia/ bradycardia, bronchospasm, wheezing, dyspnea, pronounced cutaneous reaction, laryngeal edema, pulmonary edema, hypertension” and so on. However, sometimes side effects can be highly wide ranging and even cause life-threatening issues such as “cardiopulmonary arrest, clinically manifest arrhythmias, profound hypotension, unresponsiveness and convulsions” (Robbins & Pozniak 2010, p. 4). Adding to the issue of side effects caused by contrast based MRI scans are the high costs incurred in the process. The use of contrast agents and dyes undoubtedly leads to increased cost because gadolinium, as mentioned before, is a rarely found chemical substance. Furthermore, various alternatives can be used to perform scans instead of MRI, such as computed tomography (CT) scans, ultrasound, x-rays, digital subtraction angiography etc. In the case of scans for brain, CT venography is a powerful tool, which facilitates the assessment of sinus thrombosis with cost effectiveness. However, despite the low costs of other scans, MRI is the best alternative as it provides imaging with the highest spatial resolution, thus enabling to pick up even the smallest difference in the tissues. Even within MRI scans, there is the option of performing it with contrast agents or without. Although it is a fact that MRI scans making use of contrast agents are very expensive as compared to scans without contrast agent, the relevance of the use of such agents cannot be overlooked, as they significantly increase visibility of soft tissues, organs, bones etc. 1) What is SST disease? (Explain specifically in the context of the effects of MRI on it) SST is a complicated disease that induces intracranial bleeding thus forcing the victim into a fatal state if the thrombosis is not detected in time. The detection of the cerebral thrombosis greatly depends on the imaging as well as the interpretation of the images. Only high quality imaging with great spatial resolution can enable such detection, thus MRI scans with contrast agents are the best option. Furthermore, MR venography specifically helps in studying all the soft tissues of the brain, thus detecting the slightest change present in the area under study. Despite the side effects and costs incurred due to undergoing contrast based MRI scans, the fact remains that such scans provide greater chance of pinpointing what the exact disease is and which all tissues have been affected. Furthermore, in the case of cerebral venous sinus thrombosis, without use of contrast agents, it is highly difficult to spot or diagnose the problem as a sinus thrombosis in the first place. Doctors and radiologists dismiss most CVST cases as other diseases that have similar symptoms such as CVST. The following figure is the anatomy of venous brain that depicts the major veins in the brain. A blood clot in any of these veins causes intracranial bleeding and results in diseases such as superior sagittal sinus thrombosis, inferior sagittal sinus thrombosis, dural sinus thrombosis, intracranial venous thrombosis etc. The blood clot in superficial veins are easily visible, however, the in the case of deep veins, visibility is more difficult. It is especially in such cases that MR venography with contrasted media becomes highly significant. However, the problem with contrast agents is that the gadolinium based dyes are injected into the blood, and even after several days toxic components such as gadolinium are not removed from the blood stream, thus resulting in various side effects. (Figure anatomy of venous brain) (Venous Drainage of the Brain 2012). 2) Describe MRI machine (1.5 Tesla). (MRI main component figure) 3) The typical scanning parameters for these cases in MRI 4) Describe MRI sequences such as axial and sagittal T2, axial T1, Sagittal FLAIR, axial Flair, brain diffusion. 5) Describe technique of how can we image the blood flow in the brain 6) The different modality (CT, MRI, etc) for diagnosing patient with sagittal sinus thrombosis and what is its indications. Data Analysis: a) Using expert radiologists to evaluate the difference in the resolution between two types of images b) Using IMAGEJ software to evaluate which type of MRV (with or without contrast) will be the best for a better visualization for the disease. Conclusion with an Evaluation of the Whole Project: Reference List Atanassova, P. A., Massaldjieva, R. I., Chalakova, N. T., & Dimitrov B. D. 2012. Cerebral Venous Sinus Thrombosis – Diagnostic Strategies and Prognosis Models: A Review. In Tech. Retrieved June 19, 2013 from Azin, H. & Ashjazadeh, N. 2008. Cerebral Venous Sinus Thrombosis – Clinical Features, Predisposing and Prognostic Factors. Acta Neurologica Taiwanica, Vol.17 (2): pp. 82-87. Retrieved June 20, 2013, from Caravan, P. 2006. Strategies for Increasing the Sensitivity of Gadolinium Based MRI Contrast Agents. Chemical Society Reviews. Retrieved June 23, 2013 from Crombe, D., Haven, Fr., Gille, M 2003. Isolated Deep Cerebral Venous Thrombosis Diagnosed on CT and MR Imaging: A Case Study and Literature Review. JBR-BTR. 86: 257-261. Retrieved June 19, 2013 from Faulkner, W. 1996. Basic Principles of MRI. Outsource, Inc. Retrieved June 21, 2013, from Fu et al. 2010. Comparison of Real-Time Three-Dimensional Gadolinium-Enhanced Elliptic Centric-Ordered MR Venography and Two-Dimensional Time-of-Flight MR Venography of the Intracranial Venous System. Journal of Chinese Medical Association, Vol. 73(3): pp.131-138. Retrieved June 19, 2013, from GE Neurovascular Array Coil – Excite HD 1.5T. 2013. Invivo. Retrieved June 19, 2013 from Moll, S 2011. Sinus and Cerebral Vein Thrombosis. Clot Connect. Retrieved June 19, 2013 from Nacher, P. J. 2007. Magnetic Resonance Imaging: From Spin Physics to Medical Diagnosis. Quantum Space. Retrieved June 21, 2013, from Questions and Answers on the Review of Gadolinium-Containing Contrast Agents. 2010. EMEA. Retrieved June 23, 2013, from Robbins, JB & Pozniak, MA. 2010. Contrast Media Tutorial. Amertican College of Radiology. Retrieved June 23, 2013, from Runge, VM. n.d. Contrast Agents: Safety Profile. Texas A&M University Health Science Center. Retrieved June 23, 2013, from Stam, J 2005. Thrombosis of the Cerebral Veins and Sinuses. The New England Journal of Medicine. Massachusetts Medical Society. Retrieved June 19, 2013 from Stein, B. n.d. Magnetic Resonance Venography. Hartford Hospital & Center for Minimally Invasive Therapy. Retrieved June 21, 2013, from Venous Drainage of the Brain. 2012. Medical Books Online. Retrieved June 23, 2013 from Read More