OPEN MEDSCIENCE REVIEW | August 16, 2025
Summary: Medical imaging is central to the diagnosis, management, and research of neurological diseases. Over the past century, developments in imaging have transformed how clinicians and scientists view the brain and spinal cord. Disorders such as stroke, traumatic brain injury, multiple sclerosis, Alzheimer’s disease, Parkinson’s disease, epilepsy, brain tumours, and motor neurone disease are among the most significant health challenges globally. The ability to visualise structural and functional changes within the nervous system has led to earlier diagnosis, more accurate treatment planning, improved monitoring, and a deeper understanding of pathophysiology.
This mini-review provides a detailed discussion of the role of imaging in neurological diseases. It traces the historical development of neuroimaging, explores the principles and applications of core imaging modalities, and illustrates their role across primary conditions, including stroke, neurodegenerative disorders, demyelinating disease, infections, trauma, tumours, and peripheral neuropathies. Challenges such as cost, accessibility, incidental findings, and ethical dilemmas are examined, alongside future directions in artificial intelligence, hybrid imaging, ultra-high-field scanners, and personalised neurology. The article argues that imaging will remain indispensable as medicine advances, offering insights into the most complex organ of the human body.
Keywords: Medical Imaging, Neurological Diseases, MRI, CT, PET, Neuroimaging, Diagnosis
Introduction
Neurological diseases are a leading cause of disability and death worldwide. They encompass an array of acute and chronic conditions affecting the brain, spinal cord, and peripheral nervous system. Stroke is among the most urgent neurological emergencies, while dementia represents a significant public health crisis as populations age. Movement disorders such as Parkinson’s disease, chronic demyelinating illnesses such as multiple sclerosis, and seizure disorders such as epilepsy contribute substantially to global morbidity. Traumatic brain injury, spinal cord injury, and peripheral neuropathies add further complexity.
Historically, investigation of these conditions was primarily confined to clinical examination, patient history, and post-mortem studies. While invaluable, these approaches could not reveal the dynamic, structural, and functional processes within the living brain. The introduction of medical imaging transformed this landscape. For the first time, clinicians could non-invasively examine the central nervous system, identify pathology in life, and intervene with precision.
Today, medical imaging is indispensable in neurology. It supports diagnosis, guides therapy, monitors disease progression, and fuels research into the mechanisms of neurological disorders. It also underpins clinical trials by providing biomarkers of treatment efficacy. The pace of technological development continues to accelerate, with artificial intelligence, high-resolution imaging, and molecular tracers opening new possibilities. This article provides a comprehensive account of the role of medical imaging in neurological diseases, beginning with its historical development and then considering its application across a broad spectrum of conditions.
Historical Development of Neurological Imaging
The earliest attempts at imaging the nervous system followed Wilhelm Röntgen’s discovery of X-rays in 1895. Radiographs provided valuable information about the skull, but the brain itself remained elusive because of its soft tissue composition.
One of the first significant innovations was pneumoencephalography, introduced in 1919 by Walter Dandy. This invasive procedure involved draining cerebrospinal fluid and replacing it with air to create contrast within the ventricular system. The resulting X-rays revealed outlines of the brain’s internal structures, but the procedure was notoriously painful and carried significant risk.
Cerebral angiography, developed by Egas Moniz in the 1920s, allowed visualisation of cerebral blood vessels by injecting iodinated contrast agents. This technique was invaluable in diagnosing aneurysms, vascular malformations, and tumours with abnormal blood supply. Angiography became a cornerstone of neurovascular imaging and remains a gold standard in specific interventional contexts.
The revolution arrived in the 1970s with computed tomography (CT), developed by Sir Godfrey Hounsfield and Allan Cormack. CT provided cross-sectional images of the brain, enabling detection of haemorrhage, infarction, and tumours with unprecedented clarity and speed. Its clinical adoption was swift and transformative, particularly in stroke and trauma care.
Magnetic resonance imaging (MRI), introduced clinically in the 1980s, further advanced neuroimaging. MRI exploited the magnetic properties of hydrogen atoms to generate highly detailed images of soft tissue without ionising radiation. The flexibility of MRI sequences enabled visualisation of multiple tissue characteristics, making it invaluable for a wide array of neurological conditions.
Nuclear medicine contributed functional perspectives through positron emission tomography (PET) and single-photon emission computed tomography (SPECT). These modalities revealed metabolism, receptor activity, and molecular pathology, offering insights into conditions such as dementia and movement disorders.
Hybrid systems such as PET/CT and PET/MRI have since combined structural and functional insights. The progression from invasive, uncomfortable procedures to sophisticated multimodal technologies reflects medicine’s enduring pursuit of precision, safety, and understanding.
Core Imaging Modalities in Neurology
Computed Tomography
CT scanning remains essential in neurological emergencies. By rotating an X-ray source around the patient, CT generates cross-sectional images that can be reconstructed into three-dimensional views. Its speed and accessibility make it the first-line investigation for suspected stroke and trauma. CT is particularly effective in detecting intracranial haemorrhage, subarachnoid haemorrhage, skull fractures, and mass effect.
In acute stroke, CT quickly distinguishes haemorrhagic from ischaemic events. CT angiography further delineates vascular occlusions, aneurysms, and dissections. CT perfusion imaging provides information on cerebral blood flow, blood volume, and mean transit time, supporting decisions on reperfusion therapy. Despite radiation exposure and lower soft tissue contrast compared with MRI, CT’s rapid acquisition and availability secure its central role.
Magnetic Resonance Imaging
MRI provides unparalleled soft tissue detail. By applying magnetic fields and radiofrequency pulses, it manipulates the alignment of hydrogen nuclei and records the resulting signals. This flexibility allows a wide range of contrasts and techniques.
Structural MRI is central to detecting tumours, malformations, demyelination, and atrophy. T1- and T2-weighted sequences reveal anatomy and pathology, while contrast agents highlight active inflammation or breakdown of the blood-brain barrier.
Diffusion-weighted imaging (DWI) is highly sensitive to acute ischaemia, detecting changes within minutes of stroke onset. Diffusion tensor imaging (DTI) maps white matter tracts, informing surgical planning and research into connectivity.
Functional MRI (fMRI) assesses brain activity by detecting blood oxygenation changes associated with neuronal firing. It enables mapping of functional networks during tasks or at rest, supporting epilepsy surgery and research into cognition.
Magnetic resonance spectroscopy provides metabolic information by measuring concentrations of metabolites such as N-acetylaspartate, choline, and lactate. Perfusion MRI assesses blood flow, supporting tumour grading and stroke evaluation.
MRI’s versatility, absence of ionising radiation, and superior contrast make it indispensable across almost all neurological diseases, although limitations include cost, duration, and contraindications such as pacemakers.
Positron Emission Tomography and Single-Photon Emission Computed Tomography
PET and SPECT extend imaging beyond anatomy into metabolism and molecular biology. PET involves the injection of radiotracers that emit positrons, which interact with electrons to produce gamma rays detected by the scanner. SPECT uses gamma-emitting tracers detected directly.
FDG-PET measures glucose metabolism, revealing characteristic hypometabolic patterns in Alzheimer’s disease, frontotemporal dementia, and Parkinsonian syndromes. Dopamine transporter imaging with SPECT or PET differentiates Parkinson’s disease from essential tremor and atypical movement disorders.
Amyloid and tau PET tracers have transformed dementia research, enabling in vivo visualisation of pathological proteins. In oncology, PET identifies tumour metabolism, delineates recurrence, and guides radiotherapy planning.
Although PET and SPECT involve radiation and are resource-intensive, their molecular insights complement anatomical imaging. Hybrid systems such as PET/CT and PET/MRI integrate structural and functional perspectives in one session.
Ultrasound
Ultrasound has limited penetration through bone, but transcranial Doppler provides valuable haemodynamic information. It measures blood flow velocities in basal cerebral arteries, supporting stroke risk assessment in sickle cell disease, monitoring vasospasm after subarachnoid haemorrhage, and evaluating intracranial pressure indirectly. Advances in high-frequency probes have expanded applications in neonatal neuroimaging and peripheral nerve assessment.
Emerging Modalities
Magnetoencephalography (MEG) records magnetic fields generated by neuronal currents, providing millisecond-level temporal resolution of brain activity. Optical coherence tomography and near-infrared spectroscopy are being explored for neurological applications. Ultra-high-field MRI at seven tesla and above delivers submillimetre resolution of cortical layers and microvasculature. Artificial intelligence is increasingly integrated into imaging acquisition, analysis, and interpretation, promising enhanced speed, accuracy, and personalised insights.
Imaging in Major Neurological Diseases
Stroke
Stroke is a sudden disruption of blood supply to the brain, causing cell injury and death. It is classified as ischaemic, due to vessel occlusion, or haemorrhagic, due to vessel rupture. Imaging is essential at every stage of care.
Non-contrast CT is the standard first investigation, rapidly excluding haemorrhage and detecting early signs of infarction. CT angiography visualises vascular occlusions and collateral circulation. CT perfusion identifies salvageable penumbral tissue, guiding reperfusion therapy decisions. MRI, particularly DWI, is highly sensitive to acute ischaemia and useful for posterior fossa strokes. Perfusion-weighted MRI complements this by mapping blood flow.
Imaging also plays a role in secondary prevention, identifying vascular malformations, atherosclerotic stenosis, and embolic sources. In haemorrhagic stroke, CT defines haematoma size, location, and extension, guiding neurosurgical intervention. Thus, imaging not only enables rapid diagnosis but also directs acute therapy and long-term management.
Brain Tumours
Brain tumours, whether primary or metastatic, interfere with neural function through mass effect, infiltration, and oedema. MRI is the gold standard for their evaluation. Contrast-enhanced sequences highlight tumour vascularity and blood-brain barrier disruption. Perfusion imaging estimates tumour grade by assessing blood volume. Spectroscopy reveals metabolic signatures such as elevated choline and reduced N-acetylaspartate. DTI evaluates disruption of white matter tracts, crucial for surgical planning.
PET provides complementary information. Amino acid tracers such as 11C-methionine or 18F-FET delineate tumour boundaries more accurately than MRI. FDG-PET assesses metabolic activity, although its utility is limited by high physiological uptake in grey matter. Hybrid PET/MRI systems combine anatomical precision with metabolic insight, improving diagnostic confidence. Imaging is thus critical throughout the tumour journey, from diagnosis and surgical navigation to treatment response and recurrence monitoring.
Multiple Sclerosis
Multiple sclerosis (MS) is an autoimmune demyelinating disease characterised by relapsing or progressive neurological dysfunction. MRI is fundamental to its diagnosis and monitoring. The McDonald criteria incorporate MRI evidence of lesions disseminated in time and space. T2-weighted and FLAIR sequences demonstrate hyperintense lesions in periventricular, juxtacortical, infratentorial, and spinal cord regions. Gadolinium enhancement identifies active inflammation, distinguishing new from chronic lesions.
Longitudinal MRI tracks disease activity and therapeutic response, serving as a surrogate marker in clinical trials. Advanced techniques such as DTI and magnetisation transfer imaging reveal microstructural damage beyond visible lesions. Ultra-high-field MRI enhances detection of cortical plaques. Imaging has thus transformed MS from a clinically defined to an imaging-driven disease.
Parkinson’s Disease
Parkinson’s disease (PD) is a progressive neurodegenerative disorder marked by motor symptoms including tremor, rigidity, and bradykinesia, as well as non-motor features. Diagnosis is primarily clinical, but imaging assists in differential diagnosis and research.
MRI excludes structural mimics such as vascular parkinsonism or normal pressure hydrocephalus. Advanced MRI techniques reveal changes in the substantia nigra, including reduced neuromelanin-sensitive signal and altered diffusion metrics.
Dopamine transporter imaging using SPECT (DaTSCAN) or PET demonstrates reduced presynaptic dopaminergic function, confirming PD and differentiating it from essential tremor. FDG-PET shows characteristic patterns of hypometabolism. Research applications include tracers targeting alpha-synuclein, the pathological protein in PD, offering hope for early diagnosis.
Imaging supports surgical interventions such as deep-brain stimulation by guiding electrode placement. As disease-modifying therapies are developed, imaging biomarkers will play a key role in monitoring response.
Epilepsy
Epilepsy is defined by recurrent unprovoked seizures due to abnormal neuronal activity. Imaging is vital in identifying structural causes and planning treatment.
MRI is the modality of choice, detecting lesions such as hippocampal sclerosis, cortical dysplasia, tumours, and vascular malformations. High-resolution epilepsy protocols improve lesion detection. In refractory epilepsy, functional imaging supports surgical evaluation. FDG-PET identifies hypometabolic regions corresponding to seizure foci. Ictal SPECT, performed during seizures, reveals areas of hyperperfusion. fMRI maps the eloquent cortex to minimise post-operative deficits.
Imaging thus enables identification of surgical candidates, localisation of seizure focus, and safe resection planning. In many patients, imaging-guided surgery can lead to seizure freedom.
Alzheimer’s Disease
Alzheimer’s disease (AD) is the most common cause of dementia, characterised by progressive memory loss and cognitive decline. Imaging is central to diagnosis, research, and therapeutic trials.
Structural MRI demonstrates atrophy, particularly of the hippocampus, medial temporal lobe, and parietal regions. Volumetric analysis provides quantitative biomarkers of progression. FDG-PET shows patterns of hypometabolism in the temporoparietal cortex.
The greatest advance has been amyloid and tau PET tracers, which visualise pathological protein deposition in vivo. These biomarkers enable early diagnosis, differential diagnosis from other dementias, and enrolment in disease-modifying trials. Imaging thus bridges the gap between clinical symptoms and molecular pathology, offering hope for earlier intervention.
Imaging in Additional Neurological Disorders
Motor Neurone Disease
Motor neurone disease (MND) causes progressive degeneration of upper and lower motor neurons, leading to weakness, atrophy, and ultimately respiratory failure. Imaging primarily serves to exclude mimicking conditions such as cervical spondylotic myelopathy or tumours. Advanced MRI reveals corticospinal tract degeneration and cortical thinning. PET studies suggest metabolic changes in motor and extra-motor regions, offering insights into disease mechanisms.
Cerebral Palsy
Cerebral palsy (CP) results from perinatal brain injury or malformation, manifesting as impaired movement and posture. MRI identifies hypoxic-ischaemic injury, white matter damage, or malformations such as lissencephaly. Imaging informs prognosis and rehabilitation planning by characterising the extent and timing of injury.
Traumatic Brain Injury
Traumatic brain injury (TBI) spans mild concussion to severe trauma. CT is the initial investigation, detecting haemorrhage, fractures, and mass effect. MRI, particularly susceptibility-weighted imaging, identifies microhaemorrhages and diffuse axonal injury. DTI reveals white matter disruption invisible to conventional imaging. Long-term follow-up imaging aids prognosis and guides rehabilitation strategies.
Spinal Cord Injury and Spinal Stenosis
In spinal cord injury, MRI delineates the extent of damage, haemorrhage, and oedema, predicting neurological outcome. In spinal stenosis, CT and MRI visualise narrowing of the spinal canal, compression of nerve roots, and degenerative changes. Imaging informs surgical planning and outcome prediction.
Meningitis and Encephalitis
Infections of the central nervous system can be life-threatening. MRI reveals complications of meningitis such as infarcts, abscesses, and hydrocephalus. In encephalitis, MRI shows characteristic patterns of inflammation, for example, temporal lobe involvement in herpes simplex virus. Diffusion imaging detects early ischaemia, while contrast enhancement reveals inflammatory disruption of the blood-brain barrier.
Imaging in Peripheral and Nerve Disorders
Peripheral neuropathies are often evaluated through clinical examination and neurophysiology, but imaging contributes to identifying structural causes. MRI neurography and high-resolution ultrasound can visualise peripheral nerves and detect compressive lesions.
In Bell’s palsy, imaging excludes tumours or inflammatory lesions affecting the facial nerve. Carpal tunnel syndrome can be confirmed with an ultrasound showing median nerve swelling. In Guillain-Barré syndrome, MRI may reveal nerve root enhancement. Myasthenia gravis is primarily diagnosed immunologically, but imaging is crucial for detecting thymomas associated with the disease.
Imaging in Other Neurological and Movement Disorders
Movement and functional disorders such as dystonia, Tourette syndrome, ataxia, and chronic migraine often lack specific imaging biomarkers. MRI is necessary to exclude structural causes such as tumours or malformations. Functional imaging contributes to research into abnormal brain networks underlying these disorders. In migraine, MRI and PET studies have identified cortical spreading depression and metabolic changes, offering insights into pathophysiology.
Challenges and Limitations
While neuroimaging has transformed neurology, challenges remain. Access and cost are significant barriers, particularly in low- and middle-income countries where advanced modalities are scarce. MRI and PET require substantial infrastructure and expertise, limiting global equity.
Radiation exposure from CT and nuclear medicine necessitates judicious use, especially in children. The interpretation of increasingly complex imaging requires specialist training, and incidental findings often create uncertainty. Ethical issues arise in predictive imaging, such as amyloid PET in asymptomatic individuals at risk of Alzheimer’s disease, where no curative therapy exists.
Healthcare economics also present challenges. Advanced imaging is expensive, raising questions about cost-effectiveness in routine care. Standardisation of protocols across centres remains incomplete, complicating comparison and research.
Future Directions
The future of neuroimaging is marked by integration, precision, and personalisation. Ultra-high-field MRI provides microscopic detail of cortical layers and small lesions. Machine learning algorithms are revolutionising image analysis, enabling automated detection, classification, and prognostic modelling.
New PET tracers targeting synuclein, TDP-43, and neuroinflammation will expand molecular imaging. Hybrid systems integrating PET, MRI, and CT will become more common, offering comprehensive evaluation in one examination.
The convergence of imaging with genetics, proteomics, and fluid biomarkers heralds the era of precision neurology, where therapies are tailored to the individual. Imaging will not only diagnose but also stratify patients, monitor response, and predict outcomes.
Artificial intelligence will also enhance workflow efficiency, optimise scanner usage, and reduce interpretation times. Cloud-based image sharing and big data analysis will support multi-centre research.
The future promises earlier diagnosis, more accurate monitoring, and ultimately more effective interventions for neurological diseases.
Conclusion
Medical imaging has transformed the field of neurology. From the first radiographs of the skull to today’s multimodal, high-resolution, molecular techniques, imaging has enabled clinicians to peer into the living brain with extraordinary detail.
Across a spectrum of conditions — from acute stroke to chronic neurodegeneration, from tumours to trauma, from infections to movement disorders — imaging provides crucial information that guides diagnosis, informs therapy, and supports research. Challenges in medical imaging have transformed the field of neurology. From the first radiographs of the skull to today’s multimodal, high-resolution, molecular techniques, imaging has enabled clinicians to peer into the living brain with extraordinary clarity.
Across a spectrum of conditions — from acute stroke to chronic neurodegeneration, from tumours to trauma, from infections to movement disorders — imaging provides crucial information that guides diagnosis, informs therapy, and supports research. In stroke, CT and MRI allow minute-by-minute decision-making that can be the difference between recovery and lifelong disability. In multiple sclerosis, MRI not only confirms the diagnosis but also allows tracking of disease activity over decades, helping patients and clinicians to make informed choices about long-term therapy. In epilepsy, the ability to localise seizure foci with structural and functional imaging has opened the door to curative surgery. In dementia, molecular tracers for amyloid and tau now provide the opportunity for diagnosis before clinical symptoms are advanced, a paradigm shift that is driving drug development.
The achievements of imaging are not only technological but also humanitarian. By enabling earlier diagnosis, imaging reduces uncertainty for patients and families who might otherwise wait years for answers. By guiding therapy, imaging improves outcomes and quality of life. By fuelling research, imaging contributes to the discovery of new treatments and the refinement of old ones.
Yet imaging also reflects the inequalities of modern medicine. While some centres can deploy seven-tesla MRI and novel PET tracers, others struggle to provide basic CT scanning. The global neurological burden will only be reduced when access to imaging is widened, infrastructure is strengthened, and training is expanded. Policymakers must therefore consider imaging not as a luxury but as an essential component of neurological care.
Looking ahead, the integration of artificial intelligence, machine learning, and big data analytics with imaging promises a new era of precision neurology. Neuroimaging will increasingly combine structural, functional, metabolic, and genetic information to provide a multidimensional picture of disease. Such integration will support personalised approaches, whereby therapies are tailored not only to the disease but to the individual patient’s biology.
Ethical considerations will remain important. Predictive imaging, particularly in conditions with no cure, must be approached carefully to balance the benefits of early detection with the psychological burden of uncertain knowledge. Safeguards, counselling, and clear guidelines will be required to ensure that imaging continues to serve patients’ best interests.
Ultimately, the role of medical imaging in neurological diseases is not static but dynamic, reflecting both technological progress and evolving clinical needs. As scanners become faster, more detailed, and more widely available, the boundaries of what can be seen and understood will continue to expand. In this sense, medical imaging is more than a tool; it is a partner in the ongoing effort to reduce the burden of neurological disease and improve human health.
Disclaimer
This article is intended for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment, and should not be relied upon as a substitute for consultation with a qualified healthcare professional. Readers are advised to seek the guidance of their doctor, neurologist, or other appropriately trained health professional regarding any medical concerns, symptoms, or conditions. While every effort has been made to ensure accuracy at the time of writing, medical knowledge and imaging technologies evolve rapidly, and practices may change. The author and publisher accept no liability for any loss, injury, or damage arising from the use of the information contained in this article.
How to cite: Open MedScience Review (2025) Windows into the Brain: The Expanding Role of Medical Imaging in Neurological Disorders. Available at: https://openmedscience.com/windows-into-the-brain-medical-imaging-neurological-disorders (Accessed: 16 August 2025).
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