Archive for category Radiology

Biochemical and structural magnetic resonance imaging in chronic stroke and the relationship with upper extremity motor function – Full Text

Abstract

Background

Recovery of upper extremity (UE) motor function after stroke is variable from one to another due to heterogeneity of stroke pathology. Structural and biochemical magnetic resonance imaging of the primary motor cortex (M1) have been used to document reorganization of neural activity after stroke.

Objective

To assess cortical biochemical and structural causes of delayed recovery of UE motor function impairment in chronic subcortical ischemic stroke patients.

Methodology

A cross-sectional study with fifty patients were enrolled: thirty patients with chronic (> 6 months) subcortical ischemic stroke suffering from persistent UE motor function impairment (not improved group) and twenty patients with chronic subcortical ischemic stroke and improved UE motor function (improved group). We recruited a group of (16) age-matched healthy subjects. Single voxel proton magnetic resonance spectroscopy (1H-MRS) was performed to measure N-acetylaspartate (NAA) and glutamate+glutamine (Glx) ratios relative to creatine (Cr) in the precentral gyrus which represent M1of hand area in both ipsilesional and contralesional hemispheres. Brain magnetic resonance imaging (MRI) to measure precentral gyral thickness is representing the M1of hand area. UE motor function assessment is using the Fugl Meyer Assessment (FMA-UE) Scale.

Results

The current study found that ipslesional cortical thickness was significantly lower than contralesional cortical thickness among all stroke patients. Our study found that ipsilesional NAA/Cr ratio was lower than contralesional NAA/Cr among stroke patients. UE and hand motor function by FMA-UE showed highly statistically significant correlation with ipsilesional cortical thickness and ipsilesional NAA/Cr ratio, more powerful with NAA/Cr ratio.

Conclusion

We concluded that persistent motor impairment in individuals with chronic subcortical stroke may be at least in part related to ipsilesional structural and biochemical changes in motor areas remote from infarction in form of decreased cortical thickness and NAA/Cr ratio which had the strongest relationship with that impairment.

Introduction

Motor impairment of one side of the body is a major cause of disability in activities of daily living. Recovery from strokes varies from one patient to another due to the heterogeneity of the stroke pathology and rehabilitation strategies. While most stroke patients recover spontaneously, many are left with permanent neurological impairments [1].

Understanding the brain pathologies associated with upper extremity (UE) impairment after stroke, the underlying mechanisms of injury, and the processes associated with recovery is important for achieving good recovery and successful rehabilitation. Advancements in neuroimaging technology have made this possible. Structural and biochemical brain imaging of primary motor cortices has been used to document the reorganization of neural activity after stroke. Ipsilesional and contralesional primary motor cortices, as well as the dorsal premotor cortex, have been identified as areas that can undergo substantial post-stroke neuroplasticity [2].

Single voxel proton magnetic resonance spectroscopy (1H-MRS) is a non-invasive tool to measure the levels of certain metabolites. In acute stroke, the presence of a measurable lactate peak demonstrates a shift from aerobic to anaerobic metabolism in the brain. Previous studies have shown that this is a temporary effect, and levels return to an almost undetectable state within 3 weeks [3].

Biochemical changes have also been observed chronically within ipsilesional normal-appearing grey matter and have been associated with morphological changes in stroke patients [4].

N-Acetylaspartate (NAA) is a metabolite found exclusively in neurons and their processes. It is considered a putative marker of their integrity with specific roles in the central nervous system, including myelin synthesis, neuronal energetics, neuronal osmoregulation, and axonal–glial signaling [5].

In individuals with chronic stroke, lower NAA and higher myo-inositol (an astrocyte marker) concentrations have been reported within ipsilesional and contralesional primary motor cortices [6].

A positive correlation has been drawn between NAA, glutamate (Glu: the principle excitatory neurotransmitter in the human central nervous system), and UE function in a chronic stroke population [7].

Structural changes in regional cortical thickness have also been observed in individuals in the subacute phase (3 months of recovery) after subcortical ischemic stroke and have been linked to functional activation changes in individuals with chronic stroke [89].

The purpose of this study is to assess cortical, biochemical, and structural causes of delayed recovery of UE motor function impairment in patients with chronic, subcortical ischemic stroke.

Subjects and methods

A cross-sectional study with fifty patients were enrolled: thirty patients with chronic (> 6 months) subcortical ischemic stroke suffering from persistent upper extremity motor function impairment (not improved group) and twenty patients with chronic subcortical ischemic stroke and improved upper extremity motor function (improved group).

All patients were recruited from El Sahel Teaching Hospital outpatient clinics.

Inclusion criteria

  1. 1.Eligible right handed patients aged between 50 and 70 years old.
  2. 2.Single clinically diagnosed chronic (> 6 months) subcortical ischemic stroke presented with UE motor impairment at the acute stage.
  3. 3.Radiologically apparent healthy precentral gyrus grey matter.

Exclusion criteria

  1. 1.Patients with disturbed consciousness level.
  2. 2.Patients with aphasia, cognitive impairment, UE apraxia, sensory deficit, or ataxia.
  3. 3.Patients with history of previous stroke.
  4. 4.Patients who had any contraindication for MRI or 1H-MRS.
  5. 5.Patients who underwent neuro-rehabilitation through transmagnetic brain stimulation or transcranial direct current brain stimulation.
  6. 6.Patients with uncontrolled diabetes mellitus.
  7. 7.Patients with chronic renal or hepatic failure.

We recruited right-handed age-matched (16) healthy subject group to be references for our results regarding Egyptian people.

Methods

All participants subjected to:

  1. 1.Full medical history and neurological examination.
  2. 2.Routine lab and imaging.
  3. 3.(1H-MRS) to measure NAA and Glx concentration as ratios of their peak heights to Cr peak height as a stable internal reference (NAA/Cr and Glx/Cr) in ipsilesional and contralesional precentral gyrus which represent the M1 of hand area (landmark of precentral gyrus), determined anatomically by the area that faces and forms the “middle knee” of the central sulcus, located just at the cross point between the precentral sulcus and the central sulcus, which is topographically located at the level of the distal end of the superior frontal sulcus and is therefore also visible on the cortical surface [10] (Fig. 1).
  4. 4.MRI brain to (a) quantify cortical thickness of the precentral gyrus representing the M1of hand area in both ipsilesional and contralesional hemispheres through Picture Archiving and Communication System (PACS), presented in millimeters (mm) and (b) assess white matter disease by fazekas scale which divides the white matter in periventricular (PVWM) and deep white matter (DWM) through fluid attenuated recovery (FLAIR) film with the higher score means more severity.
  5. 5.UE motor function assessment using the Fugl Meyer Assessment (FMA-UE) Scale [11].
  6. 6.Modified rankin scale (mRS) to assess disability degree in stroke patients ranging from 0 to 5 with higher score indicating more disability [12].
figure1
Precentral gyrus, which represents the M1 of hand area (landmark of precentral gyrus), determined anatomically by the area that faces and forms the “middle knee” of the central sulcus, located just at the cross point between the precentral sulcus and the central sulcus, which is topographically located at the level of the distal end of the superior frontal sulcus and is therefore also visible on the cortical surface

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Continue —-> https://ejnpn.springeropen.com/articles/10.1186/s41983-020-00183-2

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[ARTICLE] Imaging in neuro-oncology – Full Text

Imaging plays several key roles in managing brain tumors, including diagnosis, prognosis, and treatment response assessment. Ongoing challenges remain as new therapies emerge and there are urgent needs to find accurate and clinically feasible methods to noninvasively evaluate brain tumors before and after treatment. This review aims to provide an overview of several advanced imaging modalities including magnetic resonance imaging and positron emission tomography (PET), including advances in new PET agents, and summarize several key areas of their applications, including improving the accuracy of diagnosis and addressing the challenging clinical problems such as evaluation of pseudoprogression and anti-angiogenic therapy, and rising challenges of imaging with immunotherapy.

The roles of imaging in neuro-oncology primarily consist of diagnosis, prognosis, and treatment response assessment of central nervous system (CNS) tumors. Imaging assessment is currently an important surrogate endpoint for clinical trials. With ongoing evaluation and discovery of novel treatment agents, including immunotherapy agents, the ability to accurately assess progression and discern treatment-related changes is a central goal of neuro-oncologic imaging. In this review, we will summarize several clinically available imaging techniques as well as some novel methods under development, and provide an up-to-date review of some clinical challenges in treatment of glioblastomas where imaging can have important roles.

Diffusion-weighted magnetic resonance imaging (DW-MRI) can characterize tissues based on the differences in the degree of free movement of protons. It has been shown that the cellularity or cell density of tumor is associated with apparent diffusion coefficient (ADC), a calculated metric from DW-MRI.1 This property allows one to distinguish between both tumor subtypes and tumor grades (low versus high). More recently, high b-value DW-MRI, using a b-value >3000 s/mm2, has been demonstrated to be superior to standard DW-MRI in distinguishing tumor tissue from normal brain parenchyma.2 DW-MRI data can also be further quantified to generate imaging markers using techniques such as diffusion kurtosis imaging (DKI),3 histogram curve-fitting,4 and functional diffusion map (fDM).5 Restriction spectrum imaging (RSI) is an DW-MRI technique that can isolate the diffusion properties of tumor cells from extracellular process such as edema, potentially improving specificity of tumor detection and characterization.6 Diffusion tensor imaging (DTI) measures the directionality of proton motion as fractional anisotropy (FA), which is often altered in the presence of brain tumors.7 Applications of these methods will be reviewed in the following sections.

Perfusion-weighted magnetic resonance imaging (PW-MRI) techniques assess blood flow to tissue by calculating parameters derived from the time–intensity curve. Using the normal brain as reference, these techniques can detect pathological alterations of tissue vascularity that commonly occur among brain tumors due to increased vascular permeability as well as intravascular blood volume because of tumor-induced angiogenesis. Dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) quantifies first-pass bolus of paramagnetic contrast agent,8,9 and is currently the most common perfusion-weighted imaging method in clinical use. Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) can characterize vascular permeability within or surrounding tumors by using pharmacokinetic models to quantify the movement of contrast agents crossing the blood–brain barrier.1012 DCE-MRI has an advantage over DSC-MRI due to its greater signal-to-noise ratio and spatial resolution, although imaging acquisition time is also longer. Perfusion imaging measurements are highly dependent on imaging acquisition parameters and postprocessing techniques, including variations in postprocessing software tools.13 Clinical application of this technique therefore requires efforts in standardization, particularly in multicenter settings.

Magnetic resonance spectroscopy (MRS) measures concentrations of metabolites within tissues noninvasively.14 The single-voxel spectroscopy (SVS) method collects average MRS data within a target region of interest selected on standard MRI images. The multivoxel spectroscopy (MVS) method can obtain two- or three-dimensional maps of the region of interest to detect voxel-wise spatial changes of specific metabolites. Both SVS and MVS approaches have been evaluated in tumor diagnosis, grading, pre-therapy planning and post-therapy assessment. One major limitation of the technique is its operator dependency, requiring experienced staff to manually select regions of interest during acquisition. It is also less sensitive to lesions with volume <1.5 cm3.

18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is an important imaging tool in oncology.15 Similar to systemic cancers, brain tumors often exhibit increased metabolic activity resulting in elevated 18F-FDG uptake that can be detected by PET.16 The role of FDG-PET in brain tumor imaging, however, has been quite limited due to its relative lack of specificity and high background uptake by the normal brain. This limitation is particularly important for small lesions, as currently the resolution of PET imaging is limited to 5 mm. More recently, amino acid PET tracers including 11C-methionine, 18F-fluorothymidine (FLT), 18F-fluoro-ethyl-tyrosine (FET), and 18F-dihydroxyphenylalanine (DOPA) have been developed and evaluated for brain tumor imaging. This class of radiotracers is avidly taken up by malignant brain tumors that have higher cellular proliferation compared to the normal brain.1720 The advantage of high lesion-to-background uptake ratio makes amino acid PET suitable for imaging of brain tumors, including applications such as predicting tumor grade, detecting recurrent tumor, and assessing treatment response. Novel PET radiotracer (18)F-fluoromisonidazole (18F-FMISO) has been evaluated as a marker of tissue hypoxia before and after treatment.21,22

With increasing computing speed and availability of pre-engineered algorithms, imaging data can be analyzed for voxel-level intensity variations to generate texture-type features that can be correlated with tumor biology or treatment response. This approach can be applied to any imaging modality individually or simultaneously through spatial co-registration. As a result, imaging features can be regarded as tumor phenotypes and this type of biomarker can be summarized by the term ‘radiomics’.23 Screening or combining a large number of radiomic features allows generation of models that can aid oncologic diagnosis, prognostication, and treatment response prediction. This approach has been successful in a number of systemic cancers.2428 The radiomic approach is particularly suitable for evaluating high-grade gliomas, a tumor type that is well known for its genetic heterogeneity and highly complex imaging phenotypes.

Imaging plays a key role in the diagnosis of brain tumors and has become one routine management step during preoperative evaluation to aid determination of tumor grade and prognosis. It can also provide important spatial information on tumor tissue characteristics for some tumor subtypes that can influence surgical and radiation treatment planning. In addition, imaging has shown increasing ability to detect tumor genetic profile that can further provide valuable prognostic and predictive information for optimal treatment planning. Finally, imaging findings are often combined with clinical data such as age, gender, and presenting symptoms and signs to increase the accuracy of diagnosis for various tumor types, as well as identifying non-tumor mimics.

One common clinical dilemma during preoperative diagnosis of brain tumors is to distinguish between high-grade glioma and lymphoma. Standard management of CNS lymphoma is nonsurgical and biopsy is the preferred approach if lymphoma is suspected preoperatively, whereas maximal surgical resection provides the best prognosis for high-grade glioma. On conventional imaging sequences, these tumor types commonly exhibit contrast enhancement and peritumoral edema, which make it challenging to differentiate. Lymphomas typically exhibit low ADC values due to high cellularity.29,30 However, this histological feature can be seen in high-grade gliomas and metastases.

Quantitatively, the FA and ADC values of primary cerebral lymphoma are significantly lower than those of glioblastoma.31,32 There is also evidence that DSC-MRI and DCE-MRI parameters of the enhancing regions of the tumor can discriminate between lymphomas and glioblastomas as well as between lymphomas and metastasis,32,33 although a direct comparison of DCE-MRI and DW-MRI shows that ADC measurement is superior to DCE-MRI in differentiating the two tumor types.34 Detection of intratumoral microhemorrhage using the susceptibility-sensitive MRI technique also allows differentiation of glioblastoma and primary CNS lymphomas.35 Texture features generated from post-contrast images of lymphoma and glioblastoma also allow diagnostic differentiation.36

Analysis of nonenhancing signal abnormalities surrounding brain lesions can provide independent diagnostic information. ADC values measured within fluid-attenuated inversion recovery (FLAIR) abnormalities surrounding the enhancing regions can differentiate high-grade gliomas from solitary metastases.37,38 The difference could be due to the presence of tumor infiltration by glioma, resulting in higher cellularity than tumor-induced edema.39 This is also supported by MRS and DSC-MRI measurements of the peritumoral region showing higher choline to N-acetylaspartic acid (NAA) ratio and greater vascularity among high-grade gliomas compared to brain metastases.32,40,41 Combined evaluation of both the enhancing and nonenhancing regions can potentially enhance diagnostic accuracy.32,42 Beyond the margins of signal abnormalities outlined by conventional MRI, including T1- and T2-weighted imaging, MRS can identify regions of brain containing tumor and improve surgical resection and patient outcome.43,44

Molecular data of gliomas have demonstrated prognostic significance and have been incorporated into the 2016 World Health Organization (WHO) criteria.45 The imaging characteristics of brain tumors can be directly related to a specific set of tumor genomics, providing opportunities to noninvasively predict tumor genotype preoperatively. Radiomic models have been developed based on conventional MRI, DTI, and DSC-MRI for predicting gene expression profiles of newly diagnosed glioblastomas.46 Specific genetic alterations of tumors can also be predicted by analysis of MRI data and predictive models have been generated for O6-methylguanine-DNA methyltransferase (MGMT) methylation status,47,48 epidermal growth factor (EGFR) amplification status,25,49 and EGFR receptor variant III status.50 Isocitrate dehydrogenase 1/2 (IDH) mutations are commonly present in low-grade gliomas as well as secondary glioblastomas. These mutant tumors accumulate 2-hydroxyglutarate (2HG), an onco-metabolite that can be detected by MRS (Figure 1).51 Measurement of 2HG concentration allows diagnosis of IDH mutant tumor preoperatively and also opportunities to monitor tumor activity during treatment.52,53 Static and dynamic FET-PET measurements have also been correlated with IDH and 1p/19q status.54 More recently, multimodal MRI imaging can be evaluated by machine learning algorithms to generate predictive models for IDH status in gliomas.5557

Continue —-> Imaging in neuro-oncology – Hari Nandu, Patrick Y. Wen, Raymond Y. Huang, 2018

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[ARTICLE] Advances in brain imaging in multiple sclerosis – Full Text

Brain imaging is increasingly used to support clinicians in diagnosing multiple sclerosis (MS) and monitoring its progression. However, the role of magnetic resonance imaging (MRI) in MS goes far beyond its clinical application. Indeed, advanced imaging techniques have helped to detect different components of MS pathogenesis in vivo, which is now considered a heterogeneous process characterized by widespread damage of the central nervous system, rather than multifocal demyelination of white matter. Recently, MRI biomarkers more sensitive to disease activity than clinical disability outcome measures, have been used to monitor response to anti-inflammatory agents in patients with relapsing–remitting MS. Similarly, MRI markers of neurodegeneration exhibit the potential as primary and secondary outcomes in clinical trials for progressive phenotypes. This review will summarize recent advances in brain neuroimaging in MS from the research setting to clinical applications.

 

In the last decade, magnetic resonance imaging (MRI) has emerged as a fundamental imaging biomarker for multiple sclerosis (MS). Currently, MRI plays a key role in several aspects of the disease including diagnosis,1 prognosis2 and treatment response assessment.3

Over the last few years, developments in brain imaging acquisition and post-processing have advanced the field and have made tremendous contributions to our understanding of disease-specific pathogenetic mechanisms.4 This has improved the accuracy of MS diagnosis and differentiation from other inflammatory diseases of the central nervous system (CNS).5 Furthermore, promising imaging biomarkers are now used to reflect pathological processes occurring in progressive MS.6 This has culminated in the recent use of advanced imaging technique measures as outcomes in phase II and III MS clinical trials of disease-modifying and neuroprotective therapies.7

There is expanding scientific literature on brain imaging in MS. Therefore, we constrained our review to the clinical advances in human brain MRI achieved over the last 5 years in the MS field. Although positron emission tomography (PET)8 and optical coherence tomography (OCT)9 are currently emerging as key tools in the understanding of MS pathophysiology and in monitoring the disease, these neuroimaging techniques were not included in our search criteria.

The aim of this review was to describe advances in brain MRI imaging used to support the diagnosis of MS and to characterize the pathological mechanisms underlying clinical activity and progression. Finally, we intended also to present the recent impact of these advances on clinical trials in MS. For these purposes, the review was conducted using literature from Embase and PubMed using the following keywords: multiple sclerosis; magnetic resonance imaging; brain; pathogenesis; diagnosis; progression. As regards clinical trials, we focused on completed phase II and III trials in relapsing–remitting MS (RR-MS) or progressive MS using clinical trials databases, such as ClinicalTrials.gov and ClinicalTrialsRegister.eu.

Recent advances in neuroimaging considering different brain locations are listed in Figure 1.

                        figure

Figure 1. Advances in brain imaging in multiple sclerosis in different brain locations.
CVS, central vein sign; DGM, deep grey matter; DMD, disease-modifying drug; ihMT, inhomogeneous magnetization transfer; MRI, magnetic resonance imaging; MRS, magnetic resonance spectroscopy; MWF, myelin water fraction; NODDI, neurite orientation dispersion and density imaging; PET, positron emission tomography; qMT, quantitative magnetization transfer; SEL, slowly expanding lesion; TSC, total sodium concentration.

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Continue —-> Advances in brain imaging in multiple sclerosis – Rosa Cortese, Sara Collorone, Olga Ciccarelli, Ahmed T. Toosy, 2019

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[BOOK] Learning Radiology: Recognizing the Basics – William Herring – Google Books

Front Cover

Elsevier Health SciencesApr 14, 2011 – Medical – 318 pages

Learning Radiology: Recognizing the Basics, 2nd Edition, is an image-filled, practical, and clinical introduction to this integral part of the diagnostic process. William Herring, MD, a skilled radiology teacher, masterfully covers everything you need to know to effectively interpret medical images. Learn the latest on ultrasound, MRI, CT, and more, in a time-friendly format with brief, bulleted text and abundant high-quality images. Then ensure your mastery of the material with additional online content, bonus images, and self-assessment exercises at http://www.studentconsult.com.

Identify a wide range of common and uncommon conditions based upon their imaging findings.Quickly grasp the fundamentals you need to know through easy-access bulleted text and more than 700 images.

Arrive at diagnoses by following a pattern recognition approach, and logically overcome difficult diagnostic challenges with the aid of decision trees.

Learn from the best, as Dr. Herring is both a skilled radiology teacher and the host of his own specialty website, http://www.learningradiology.com.

Easily master the fundamental principles of MRI, ultrasound, and CT with new chapters that cover principles of each modality and the recognition of normal and abnormal findings.

Know the basics and be more confident when interpreting diagnostic imaging studies

via Learning Radiology: Recognizing the Basics – William Herring – Google Books

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[BLOG POST] Brain Imaging: What Are the Different Types? – BrainLine

Positron Emission Topography
Positron Emission Topography (PET) measures brain metabolism. Different applications of PET allow one to “see” pathology associated with Alzheimer’s disease, for instance, that cannot be visualized any other way. Used in a different way, PET also allows doctors to see how different areas of the brain use oxygen or glucose – both very important to understanding not just what the damage might look like but also how the brain provides energy to itself.
T1-Weighted MRI
The T1-Weighted MRI is the standard imaging test and part of every general MRI exam. It provides doctors with a very clear view of brain anatomy and structure. It can also show damage in brain injury but generally only when the damage is very significant.
T2-Weighted MRI
The T2-Weighted MRI is also a standard part of every MRI exam. But unlike T1-weighted imaging, the T2 allows visualization of severe diffuse axonal injury such as what is expected following severe TBI.
Diffusion Weighted Magnetic Resonance Imaging
Diffusion Weighted MRI (DWI) shows alterations in tissue integrity. In ischemic injury — such as many types of stroke or when blood is not able to get to all parts of the brain — there is a chemical reaction in the cells. As the cells die because of lack of blood flow (with oxygen), there is an increase in sodium and this changes (increases) the amount of water in the tissue. DWI is very sensitive to this change. In fact, using DWI, doctors can identify a stroke or ischemic injury within seconds of occurrance.
Fluid-Attenuated Inversion Recovery MRI
Fluid-Attenuated Inversion Recovery (FLAIR) MRI is also sensitive to water content in brain tissue. This is very useful in patients who have reductions in brain tissue following an injury. Most commonly, however, FLAIR is used to visualize alterations in tissue in diseases such as multiple sclerosis.
Diffusion Tensor Imaging
Diffusion Tensor Imaging (DTI) shows white matter tracts in brain tissue. These tracts allow different parts of the brain to talk to each other. Think of the brain as if it were a computer. With DTI doctors can see and measure the “cables” connecting parts of the brain. DTI can provide information about damage to parts of the nervous system as well as about connections among brain regions.
Gradient Record MRI
Gradient Record MRI (GRE) shows blood or hemorrhaging in the brain tissue. This is very important in acute head injury. CT scans are also very useful in this stage but sometimes miss very small bleeds ― or so called microbleeds ― in the brain. MRI and types of MRI more sensitive to blood can identify these and allow doctors to monitor the patient.
Functional MRI
Functional MRI (fMRI) is a newer type of MRI that takes advantage of the iron in blood and the fact that when neurons fire there is ― eventually ― an increase in local iron in the areas where the neurons fired. For this imaging test, doctors ask patients to do something while in the MRI machine like opening and closing their right hand for 30 seconds and then opening and closing their left hand for 30 seconds. Then, the doctors model the change in signal associated with an increase in blood related to that task. So, areas involved in opening the right hand will show increased signal. This allows images to be created that reveal how the brain does tasks. This is potentially useful in TBI when the brain structures all appear normal but the brain is functioning in a different way. It is important to know that fMRI is not approved for clinical use for diagnosis of TBI.

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[WEB PAGE] fMRI vs. SPECT Scan for the Brain: Know Your Options

By: Dr. Mark Allen PhD on February 3rd, 2020

If you’re struggling to recover after a brain injury, dealing with healthcare providers is often a frustrating process. Unless you have a clear, severe injury, they might be dismissive of your symptoms or just may not have enough treatment options to help you. Oftentimes, they’ll order an MRI or a CT scan.

But MRI and CT scans will only show structural damage. So, they’re helpful if you have a severe traumatic brain injury, but if you’ve had a mild traumatic brain injury (mTBI, aka concussion), they likely won’t show anything. If your structural MRI scan comes back as normal, many doctors won’t do much in the way of follow-up.

However, that doesn’t mean you’re out of options. If you’re here, you’ve probably heard of SPECT scans and functional MRI. These imaging tests can show dysfunction resulting from an mTBI.

But which one is right for you? In this post, we’ll explain:

  • What SPECT imaging and fMRIs actually are
  • What it’s like to get a SPECT scan or fMRI
  • What they can show, and what that means for your diagnosis.

Note: If you’re experiencing symptoms that won’t go away after a concussion, we can help. On average, our patients improve by 75% after treatment. To learn about diagnosis and treatment options, sign up for a free consultation.

All About Brain SPECT Scans

A cartoon graphic of a woman lying down in an fMRI machine.

What is a SPECT Scan?

SPECT stands for “single photon emission computed tomography.” That’s a mouthful, so here’s what it translates to:

Patients are injected with a radioactive isotope that emits gamma rays (electromagnetic radiation emitted by a decaying atom). As the isotope (also known as a radioactive tracer) travels through the patient’s bloodstream, it continues to emit radiation. (We know how that sounds, but it really is a safe level of radiation).

A special “gamma camera” is positioned above the patient and able to detect the gamma rays emitted by the isotope. A computer then triangulates in 3-dimensional space where the gamma rays are coming from.

In other words, it looks at multiple data points to figure out where the isotope was in your body when the radiation was emitted.

Over time, collecting multiple “images” can show physicians if blood flow in your body has been impacted by your condition.

Note: You may be more familiar with a PET scan (positron emission tomography). The imaging technique is very similar to SPECT scanning, since both use radioactive tracers to investigate blood flow. PET has greater resolution and fewer image artifacts, but it has other drawbacks.

What Can a SPECT Scan Show?

A SPECT scan for the brain shows an average over 10 - 15 min of scanning, but an fMRI can show each second of brain activity.

SPECT scans can be used to look at the heart, brain, and a few other things. In the brain, it can be used in evaluating conditions such as neurodegenerative diseases, stroke, seizures, tumors, and other brain trauma. In the heart, it’s most commonly used to view how well the heart is moving the blood that comes through it.

Because of the delay between when the isotope emits gamma rays and when the camera records them, combined with the inaccuracy of having to triangulate their position, SPECT images are an average over time rather than an instantaneous picture. In many cases, it can take 10-15 minutes to get that average image.

Because of that, it can identify certain conditions better than others. If you’ve had a concussion, brain SPECT imaging can confirm whether you have or have not sustained brain dysfunction after the injury. Unfortunately, it often can’t provide more detailed information about specific regions and how they were affected.

How Long Does a SPECT Scan Take?

The time you spend on a SPECT scan depends somewhat on where you’re getting the scan and why you’re getting the scan. They generally range from 1-2 hours (including the time needed for the injection).

The actual scan itself can take as few as 30 minutes.

How Much Does a SPECT Scan Cost?

SPECT scans are one of the more affordable ways to image the brain, but prices can fluctuate a lot based on location, the purpose of the scan, and what additional interpretation is involved.

According to MDsave, brain SPECT scans range from $1,300 to over $3,500.

Does a SPECT Scan Have Any Side Effects?

The main possible side effect of a SPECT scan is having an allergic reaction to the injected isotope. Some people can have bruising and soreness around the site of the injection as well.

If you’re nervous about the radiation, that’s understandable. As far as Western medicine is concerned, however, it’s perfectly harmless. Most people get more radiation from being on a plane at 30,000 feet in the air than they would from a SPECT brain scan.

All About Brain fMRI Scans

fMRI scan

What is an fMRI?

fMRI scans (functional nuclear magnetic resonance imaging) work through a combination of radio waves and magnets. Engineers have figured out how to magnetize soft tissues — such as the brain — very precisely. When you send radio waves through those magnetized tissues, the magnetic field changes the radio wave.

Sensors detect even minimal changes in the radio waves to form a 3D image of the scanned tissue. The only limits to how fine the imaging can become are human ingenuity and engineering skill.

In a structural MRI, that information is used to examine the physical integrity of the brain (or any other organ being imaged). It should show any physical brain damage you’ve sustained. A functional MRI is used to observe blood flow. Since increased cerebral blood flow is tied to increased brain activity, fMRI can show how the brain calls for resources during a given task.

If you’re trying to understand the difference between a structural MRI and a functional MRI, in terms of what it means for patients, this article will help.

What Can an fMRI Show?

A detailed fMRI scan

fMRIs can show detailed images of blood flow in internal organs. In brain imaging, this means doctors and researchers can see how the brain is managing its oxygen supply and whether the right regions respond in the right way when given a certain task.

For example, we found that patients who have post-concussion syndrome (the condition in which symptoms don’t go away after a concussion) will show tell-tale signs of hyperactivity and hypoactivity in the affected brain regions. Thanks to fMRI, we’re able to pinpoint for post-concussion patients which areas of the brain are dysfunctional and in what way.

To learn more about how we do that, you can read about functional neurocognitive imaging (fNCI), the specific type of fMRI we use.

How Long Does an fMRI Take?

Because fMRI is used more in the research setting than the clinical setting as yet, scan times can vary dramatically. The more you need to know, the longer the scan will take.

At Cognitive FX, an fNCI takes about 45 minutes. During that time, patients take six different cognitive tests while we image their brain to learn how it responds to that stimulation.

How Much Does fMRI Cost?

That depends on who you’re asking — researchers might pay hundreds of dollars per hour for access to one, but if you’re part of a clinical trial, it might be free. That said, if you’re looking to get a brain fMRI for diagnostic purposes, you’ll be charged for both the scan and whatever diagnostic analysis is performed.

At Cognitive FX, charges for an fNCI can run from $3,500 to $5,250, depending on several factors (such as whether you pay in full at the visit or via a payment plan, get the scan as part of a treatment package, etc.).

Does an fMRI Have Any Side Effects?

fMRI does not have any side effects per se, but there are situations in which you might not be able to use it. Some types of foreign metal objects in your body (such as surgical implants, braces, or even permanent eye-liner) may prohibit you from entering the MRI scanner. However, the imaging facility will provide you with full details before you commit to undergoing the scan.

If you have extreme anxiety or fear of enclosed spaces, that would also pose a challenge. fMRI is completed in an enclosed space and is very loud (you are given earplugs, headphones, and cushioning to make the noise more tolerable).

SPECT vs. fMRI: Which is Better?

fMRI vs SPECT scans

fMRI is a higher quality test than SPECT, for a few reasons. However, which functional neuroimaging test you need depends on your situation.

The spatial and temporal resolution of fMRI is significantly better: fMRI can see things down to a few millimeters, whereas SPECT resolution is on the centimeter scale. 

In other words, fMRI has at least 10x better spatial resolution.

When it comes to temporal (time) resolution, there’s no comparison. SPECT gives an image from 10-15 minutes of activity at a time. fMRI, on the other hand, can give a second-by-second picture of how your brain reacts to given stimuli.

While both methods can show if your brain has been affected by a concussion, fMRI can tell you which parts of your brain were affected (Thalamus? Basal ganglia? Prefrontal cortex?) and how (hyperactive or hypoactive). The latter information is far more useful: If we know which areas of the brain are affected, we can tailor treatment to target those regions. This insight into how your brain function has been impacted by injury is invaluable during treatment.

SPECT makes more sense than fMRI in the case of easier-to-see conditions such as stroke and seizure. Since a SPECT scan is typically cheaper than fMRI, there’s no reason not to use it when it will do the job. But for concussion diagnosis, fMRI provides much more robust, clinically useful data.

fMRI for Concussion Diagnosis

All that being said, it’s important to mention that neither fMRI nor SPECT can be used to diagnose a concussion unless the doctor reading the scans has the right information and tools available.

At Cognitive FX, we do a type of fMRI called fNCI, or functional neurocognitive imaging. It’s what allows us to pinpoint which brain regions were affected (as mentioned above).

fNCI uses the same technology of an fMRI, but the imaging process involves having patients perform standardized tasks while in the MRI machine. Over years of research, we built a database of healthy and unhealthy brains performing these tasks. We know which areas of the brain are supposed to be active during these tasks, and how much or little these areas should respond to each separate task.

When we give a patient an fNCI, we analyze the images of their brain to see which areas of their brain are not working optimally. This process allows for accurate diagnosis of injuries that hinder brain function (such as concussion, but sometimes other conditions like brain dysfunction from carbon monoxide poisoning.)

After the test, we meet with patients to discuss their results and how that will affect their treatment. Patients get an overall score and several pages breaking down how each brain region we scanned performed. Here’s an example that one of our patients agreed to share:

Exam 1: Matrix Reasoning Test Findings for Olivia

From Olivia’s story: “The fNCI showed that my thalamus was hypoactive and my basal ganglia was completely out to lunch. 3 standard deviations from normal basically means that there was no activation seen in that area on the fMRI. All the work was being routed around it — causing fatigue and stress on the rest of my brain. The inferior frontal gyrus was trending toward hyperactive (using too many resources for given tasks).”

Because fNCI is a kind of fMRI, the test is noninvasive and harmless. There is no radiation, however, the same restrictions around metal apply.

What You Can Do About Concussion Recovery

For many patients, concussion symptoms resolve after about two weeks. But for others, those symptoms just won’t seem to go away. If that describes your situation, you may have post-concussion syndrome. We’ve listed some of the symptoms in the chart below:

Post-Concussion Symptoms list

Your best bet is to seek treatment from a doctor or clinic that specializes in post-concussion treatment. If you’d like to know more about how we can help you, sign up for a free consultation.

Or, if you’d like to learn about choosing a clinic, here’s our post on the best concussion clinics in the U.S.

Active Recovery

In the meantime, there are things you can do to improve your chances at a good recovery. Do your best to fit these into every day:

  1. Plenty of rest (if you’re having difficulty, this post on post-concussion sleep may help).
  2. Light physical activity for 30 minutes per day (at whatever level you can tolerate without causing symptoms). Here’s our guide to exercising safely after a concussion.
  3. Cognitive activities like reading or logic puzzles, as tolerated.
  4. Work or school activities, as tolerated.

Conclusion

Knowing whether you need an fMRI or SPECT scan comes down to a matter of how much you need to know in order to receive effective treatment. If you’re suffering from post-concussion syndrome, a SPECT scan is better than nothing, but an fMRI is significantly more useful than a SPECT scan.

If you’ve been suffering from lingering symptoms after a concussion and haven’t found relief, you’re not imagining things: 10-20% of people who have had a concussion endure lingering symptoms that do not go away without treatment. We’ve written at length about some of the more common issues our patients face, such as headachesmemory problemsrelentless fatigue, and more.

To learn more about treatment options and what you can do next, sign up for a free consultation.  

via fMRI vs. SPECT Scan for the Brain: Know Your Options

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[WEB SITE] SPECT scan – Mayo Clinic

Overview

A single-photon emission computerized tomography (SPECT) scan lets your doctor analyze the function of some of your internal organs. A SPECT scan is a type of nuclear imaging test, which means it uses a radioactive substance and a special camera to create 3-D pictures.

While imaging tests such as X-rays can show what the structures inside your body look like, a SPECT scan produces images that show how your organs work. For instance, a SPECT scan can show how blood flows to your heart or what areas of your brain are more active or less active.

Why it’s done

The most common uses of SPECT are to help diagnose or monitor brain disorders, heart problems and bone disorders.

Brain disorders

SPECT can be helpful in determining which parts of the brain are being affected by:

  • Dementia
  • Clogged blood vessels
  • Seizures
  • Epilepsy
  • Head injuries

Heart problems

Because the radioactive tracer highlights areas of blood flow, SPECT can check for:

  • Clogged coronary arteries. If the arteries that feed the heart muscle become narrowed or clogged, the portions of the heart muscle served by these arteries can become damaged or even die.
  • Reduced pumping efficiency. SPECT can show how completely your heart chambers empty during contractions.

Bone disorders

Areas of bone healing or cancer progression usually light up on SPECT scans, so this type of test is being used more frequently to help diagnose hidden bone fractures. SPECT scans can also diagnose and track the progression of cancer that has spread to the bones.

Risks

For most people, SPECT scans are safe. If you receive an injection or infusion of radioactive tracer, you may experience:

  • Bleeding, pain or swelling where the needle was inserted in your arm
  • Rarely, an allergic reaction to the radioactive tracer

SPECT scans aren’t safe for women who are pregnant or breast-feeding because the radioactive tracer may be passed to the developing fetus or the nursing baby.

Risks of radiation

Your health care team uses a small amount of radiation in order to perform a SPECT scan, and the test is not associated with any long-term health risks. Talk to your doctor if you’re concerned about your exposure to radiation during a SPECT scan.

How you prepare

How you prepare for a SPECT scan depends on your particular situation. Ask your health care team whether you need to make any special preparations before your SPECT scan.

In general, you should:

  • Leave metallic jewelry at home.
  • Inform the technologist if you’re pregnant or breast-feeding.
  • Bring a list of all the medications and supplements you take.

What you can expect

During the test

Receiving a radioactive substance

You’ll receive a radioactive substance through an intravenous (IV) infusion into a vein in your arm. The tracer dose is very small. You may feel a cold sensation as it enters your body. You may be asked to lie quietly in a room for 20 minutes or more before your scan while your body absorbs the radioactive tracer. In some cases, you may need to wait several hours or, rarely, several days between the injection and your SPECT scan.

Your body’s more-active tissues will absorb more of the radioactive substance. For instance, during a seizure, the area of your brain causing the seizure may retain more of the radioactive tracer, which allows doctors to pinpoint the area of your brain causing your seizures.

Undergoing the SPECT scan

The SPECT machine is a large circular device containing a camera that detects the radioactive tracer your body absorbs. During your scan, you lie on a table while the SPECT machine rotates around you. The SPECT machine takes pictures of your internal organs and other structures. The pictures are sent to a computer that uses the information to create 3-D images of your body.

How long your scan takes depends on the reason for your procedure.

After the test

Most of the radioactive tracer leaves your body through your urine within a few hours after your SPECT scan. Your doctor may instruct you to drink more fluids, such as juice or water, after your SPECT scan to help flush the tracer from your body. Your body breaks down the remaining tracer over the next few days.

Results

A radiologist or doctor with advanced training in nuclear medicine will analyze the results of your SPECT scan and send them to your doctor. Pictures from your scan may show colors that tell your doctor what areas of your body absorbed more of the radioactive tracer and which areas absorbed less. For instance, a brain SPECT image might show a lighter color where brain cells are less active and darker colors where brains cells are more active. Some SPECT images show shades of gray, rather than colors.

Ask your health care team how long to expect to wait for your results.

Clinical trials

Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.

via SPECT scan – Mayo Clinic

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[Abstract + References] Demystification of AI-driven medical image interpretation: past, present and future

Abstract

The recent explosion of ‘big data’ has ushered in a new era of artificial intelligence (AI) algorithms in every sphere of technological activity, including medicine, and in particular radiology. However, the recent success of AI in certain flagship applications has, to some extent, masked decades-long advances in computational technology development for medical image analysis. In this article, we provide an overview of the history of AI methods for radiological image analysis in order to provide a context for the latest developments. We review the functioning, strengths and limitations of more classical methods as well as of the more recent deep learning techniques. We discuss the unique characteristics of medical data and medical science that set medicine apart from other technological domains in order to highlight not only the potential of AI in radiology but also the very real and often overlooked constraints that may limit the applicability of certain AI methods. Finally, we provide a comprehensive perspective on the potential impact of AI on radiology and on how to evaluate it not only from a technical point of view but also from a clinical one, so that patients can ultimately benefit from it.

Key Points

• Artificial intelligence (AI) research in medical imaging has a long history

• The functioning, strengths and limitations of more classical AI methods is reviewed, together with that of more recent deep learning methods.

• A perspective is provided on the potential impact of AI on radiology and on its evaluation from both technical and clinical points of view.

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via Demystification of AI-driven medical image interpretation: past, present and future | SpringerLink

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