1.1 Introduction
Stroke is defined as a neurological condition that occurs when there is a sudden interruption of blood supply to the brain, leading to cell death due to lack of oxygen and nutrients. This interruption is either caused by a blockage of blood flow, known as ischemic stroke, or by the rupture of a blood vessel, known as hemorrhagic stroke. Stroke is a medical emergency that requires rapid diagnosis and treatment to reduce the risk of long-term disability or death (World Health Organization, 2023). Globally, stroke remains a leading cause of death and disability, placing a significant burden on healthcare systems, particularly in low and middle income countries where access to advanced diagnostic tools is limited (Feigin et al., 2022).
In modern medical practice, neuroimaging plays a vital role in the accurate diagnosis and management of stroke. Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are the two primary imaging modalities used in evaluating patients with suspected stroke. CT scanning uses X-ray technology to produce detailed images of the brain and is widely used in emergency settings due to its speed, availability, and effectiveness in detecting acute intracranial hemorrhage. It is often the first imaging tool used when stroke is suspected because it is fast and helps to quickly rule out bleeding in the brain (American Stroke Association, 2022).
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are significance of the study, scope of work, research hypothesis and questions, limitation of the study and definition of terms.
1.2 Background of Study
Stroke is a major public health concern globally and remains one of the leading causes of death and long-term disability. It is a neurological disorder that occurs when there is an interruption of blood flow to the brain, resulting in damage to brain cells due to oxygen deprivation. According to World Health Organization (2023), stroke is responsible for millions of deaths annually and contributes significantly to global disability-adjusted life years. The burden of stroke is particularly high in low and middle income countries where access to timely diagnosis and advanced imaging technologies is limited (World Health Organization, 2023).
Feigin et al. (2022) asserted that, stroke is one of the most devastating neurological conditions worldwide, and they reported that the incidence of stroke is rising in developing regions due to increasing risk factors such as hypertension, diabetes, obesity, and unhealthy lifestyles. They further asserted that early diagnosis and rapid intervention are critical in reducing stroke-related mortality and morbidity. In clinical practice, accurate diagnosis of stroke type, whether ischemic or hemorrhagic, is essential for determining appropriate treatment strategies.
According to American Stroke Association (2022), neuroimaging plays a central role in the evaluation of suspected stroke patients. The authors stated that Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are the most commonly used imaging modalities in stroke diagnosis. CT is widely used in emergency settings because it is fast, widely available, and highly effective in detecting acute hemorrhagic stroke. MRI, on the other hand, provides superior soft tissue contrast and is more sensitive in detecting early ischemic changes in the brain.
Osborn (2017) reported that CT imaging remains the first line of investigation in most emergency departments due to its speed and ability to quickly rule out intracranial hemorrhage. He asserted that CT is particularly useful in acute settings where time is critical, as it provides rapid imaging results that guide immediate clinical decisions. However, he contended that CT has limitations in detecting early ischemic stroke within the first few hours of onset, which may lead to delayed diagnosis in some cases.
According to Sacco et al. (2013), ischemic stroke accounts for the majority of stroke cases globally, and they stated that early detection is crucial for the administration of thrombolytic therapy. They affirmed that MRI, particularly diffusion-weighted imaging (DWI), is more sensitive than CT in detecting early ischemic changes within minutes of stroke onset. This makes MRI a valuable tool in stroke diagnosis, especially when early intervention is required to prevent irreversible brain damage.
According to Kidwell et al. (2019), MRI has demonstrated higher diagnostic accuracy in identifying small infarcts, posterior circulation strokes, and transient ischemic attacks compared to CT. The authors reported that MRI provides better visualization of brain tissue abnormalities and is more effective in differentiating stroke subtypes. However, they asserted that MRI is often underutilized in emergency settings due to its high cost, longer scanning time, and limited availability in many healthcare institutions.
In Nigeria, the challenges associated with stroke diagnosis are more pronounced due to limited healthcare infrastructure. According to Adeloye et al. (2020), the burden of stroke in sub-Saharan Africa is increasing rapidly, and they stated that delayed diagnosis and inadequate imaging facilities contribute significantly to poor patient outcomes. They contended that many tertiary hospitals rely heavily on CT scanning due to its accessibility, while MRI is often reserved for complex cases or when CT findings are inconclusive (Adeloye et al., 2020).
At the Lagos University Teaching Hospital (LUTH), both CT and MRI are used in the diagnosis of stroke, but their utilization is influenced by several factors including availability, patient affordability, and urgency of clinical presentation. According to Oladipo and Akinyemi (2021), they reported that CT is frequently used as the first imaging modality in suspected stroke cases due to its speed and emergency readiness. They further affirmed that MRI is typically used for detailed evaluation when more precise brain imaging is required. However, despite the availability of both imaging modalities, there remains a need for a comparative evaluation of their diagnostic effectiveness within the Nigerian healthcare context. According to Bradley (2016), the choice between CT and MRI should be guided by clinical urgency, diagnostic accuracy, and resource availability. He stated that understanding the strengths and limitations of both modalities is essential for improving stroke management outcomes.
This study is set against the backdrop of the increasing burden of stroke in Nigeria, the limitations in diagnostic imaging resources, and the need for evidence-based comparison of CT and MRI in stroke diagnosis within a tertiary healthcare setting such as Lagos University Teaching Hospital.
1.3 Statement of Problems
Investigation revealed that stroke remains one of the leading causes of morbidity and mortality worldwide, and its rapid and accurate diagnosis is critical for effective management and improved patient outcomes. In clinical practice, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) are the two major neuroimaging modalities used in the evaluation of stroke. At the Lagos University Teaching Hospital (LUTH), as in many healthcare facilities in developing countries, the choice of imaging modality is often influenced by availability, cost, urgency, and clinical presentation rather than purely diagnostic superiority. CT imaging is widely available and is frequently the first-line imaging technique used in suspected acute stroke cases due to its speed and effectiveness in detecting intracranial hemorrhage. However, MRI is known to provide higher sensitivity in detecting early ischemic changes and subtle brain abnormalities that may not be visible on CT scans.
In addition, inconsistencies in diagnostic outcomes between CT and MRI have raised concerns among clinicians regarding the most effective imaging approach for stroke patients. While CT is often preferred in emergency situations due to its rapid acquisition time, MRI provides superior tissue contrast and better visualization of posterior fossa lesions and small infarcts. Studies have also shown that reliance on a single imaging modality may result in incomplete assessment of stroke severity and type, which directly affects treatment decisions (WHO, 2023; American Stroke Association, 2022).
Furthermore, infrastructural challenges such as limited MRI machines, frequent power supply issues, and high patient workload further complicate effective neuroimaging services in tertiary hospitals in Nigeria. CT scanners, although more widely available, do not always provide sufficient detail for comprehensive stroke evaluation, particularly in early ischemic stages. It is against this backdrop that this study seeks to compare the effectiveness of Computed Tomography and Magnetic Resonance Imaging in the diagnosis of stroke patients at Lagos University Teaching Hospital.
1.4 Aim and Objectives of Study
The aim of this study is to evaluate and compare Computed Tomography and Magnetic Resonance Imaging in stroke diagnosis at Lagos University Teaching Hospital.
To achieve this aim, the study has the following objectives:
- Assess the effectiveness of CT in detecting stroke cases at LUTH.
- Evaluate the effectiveness of MRI in detecting stroke cases at LUTH.
- Compare the diagnostic accuracy of CT and MRI in identifying ischemic stroke.
- Compare the diagnostic accuracy of CT and MRI in identifying hemorrhagic stroke.
- Determine the challenges affecting the use of CT and MRI in stroke diagnosis at LUTH.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- How effective is CT in detecting stroke cases at LUTH?
- How effective is MRI in detecting stroke cases at LUTH?
- How does CT compare with MRI in diagnosing ischemic stroke?
- How does CT compare with MRI in diagnosing hemorrhagic stroke?
- What are the challenges affecting the use of CT and MRI in stroke diagnosis at LUTH?
1.6 Research Hypotheses
In order to pursue the objective of this study, the following generalized statements have been designed to guide and aids in obtaining the result for the experiment to be conducted. For this work, the null hypothesis will be represented with H0 while the alternative hypothesis will be represented with hypothesis H1.
Hypothesis 1
- H0: There is no significant difference between CT and MRI in detecting stroke cases at LUTH.
- H1: There is a significant difference between CT and MRI in detecting stroke cases at LUTH.
Hypothesis 2
- H0: There is no significant difference between CT and MRI in diagnosing ischemic stroke.
- H1: MRI is significantly more effective than CT in diagnosing ischemic stroke.
Hypothesis 3
- H0: There is no significant difference between CT and MRI in diagnosing hemorrhagic stroke.
- H1: CT is significantly more effective than MRI in diagnosing hemorrhagic stroke.
1.7 Significance of Study
It is believed that at the completion of the study, the findings will improve clinical decision making in stroke diagnosis at Lagos University Teaching Hospital by providing evidence-based comparison between CT and MRI. The study will also assist radiologists in selecting the most appropriate imaging method for different stroke types.
Furthermore, the findings will enhance early detection of stroke, which is critical in reducing mortality and disability rates associated with delayed diagnosis in Nigeria. In addition, the findings will support hospital management in improving imaging service delivery and resource allocation between CT and MRI units.
Lastly, the findings will contribute to academic literature on neuroimaging in stroke diagnosis within developing countries.
1.8 Scope of Study
The study focuses on the comparative analysis of Computed Tomography and Magnetic Resonance Imaging in stroke diagnosis at Lagos University Teaching Hospital (LUTH), Idi-Araba, Lagos State, Nigeria. It is limited to stroke patients who undergo CT and MRI scanning within the radiology department of LUTH.
1.9 Limitations of the Study
During the course of this study, there were some problems encountered which stood as limitations to the research work. Some of the limitations include:
- Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
- Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
- Initial Cooperation Delay from Respondents: A particular limitation of this work came as a result of the respondent refusal to offer their cooperation at the initial time they were contacted. This contributed in making the success of this research study difficult.
1.10 Definition of Terms
Stroke:
Stroke is a medical condition that occurs when blood supply to part of the brain is interrupted or reduced, leading to brain cell damage (World Health Organization, 2023). It includes ischemic and hemorrhagic types depending on the cause of blood flow disruption.
Computed Tomography (CT):
CT is an imaging technique that uses X-rays and computer processing to create detailed images of the brain and is commonly used for rapid detection of intracranial abnormalities, especially hemorrhagic stroke (Osborn, 2017).
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