Single Positron Emission Computed Tomography Research Articles

Alzheimer ’s disease identification from 3D SPECT brain scans by variational analysis

The application of a radioactive tracer and following brain Single Positron Emission Computed Tomography (SPECT) is a standard technique used in neurodegenerative disease investigation. Alzheimer’s disease is the most common form of neurodegenerative disease. In this paper, a novel 3D linear classifier is developed to classify Alzheimer’s disease. The classification problem is formulated as the variational task with periodic boundary conditions, which is easy to discretize and solve using Fast Fourier Transform, and therefore, the resulting learning algorithm is very fast. Thanks to linearity of the classifier, weights obtained by 3D classifier learning are easy to visualize and bring understanding the most important features. The proposed classifier exhibits accuracy, sensitivity, and specificity of at least 90%.

99mTc-labeled iRGD for single-positron emission computed tomography imaging of triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype, with a high mortality rate. One of the main reasons for this poor prognosis is the failure of a specific diagnosis. As a tumor-homing and penetrating peptide, iRGD has not only the properties of binding to neuropilin-1 and integrin αvβ3 but also internalizing into TNBC cells. In this study, we designed and prepared 99mTc-labeled iRGD (99mTc-HYNIC-iRGD) as a single-positron emission computed tomography (SPECT) imaging probe and investigated its feasibility for the targeted diagnosis of TNBC. The results showed that the iRGD peptide had acceptable biocompatibility within the studied concentration range and could specifically bind to TNBC cells in vitro. The 99mTc-HYNIC-iRGD was readily prepared with high radiochemical purity and stability. SPECT imaging of 99mTc-HYNIC-iRGD in a TNBC tumor-bearing mouse model showed obvious tumor accumulation with rapid blood clearance and favorable biodistribution. Our findings indicate that this active-targeted strategy has great potential to be developed as a novel tool for TNBC imaging.

Responsivity of the Striatal Dopamine System to Methylphenidate-A Within-Subject I-123-β-CIT-SPECT Study in Male Children and Adolescents With Attention-Deficit/Hyperactivity Disorder.

Background:Methylphenidate (MPH) is the first-line pharmacological treatment of attention-deficit/hyperactivity disorder (ADHD). MPH binds to the dopamine (DA) transporter (DAT), which has high density in the striatum. Assessments of the striatal dopamine transporter by single positron emission computed tomography (SPECT) in childhood and adolescent patients are rare but can provide insight on how the effects of MPH affect DAT availability. The aim of our within-subject study was to investigate the effect of MPH on DAT availability and how responsivity to MPH in DAT availability is linked to clinical symptoms and cognitive functioning.MethodsThirteen adolescent male patients (9–16 years) with a diagnosis of ADHD according to the DSM-IV and long-term stimulant medication (for at least 6 months) with MPH were assessed twice within 7 days using SPECT after application of I-123-β-CIT to examine DAT binding potential (DAT BP). SPECT measures took place in an on- and off-MPH status balanced for order across participants. A virtual reality continuous performance test was performed at each time point. Further clinical symptoms were assessed for baseline off-MPH.ResultsOn-MPH status was associated with a highly significant change (−29.9%) of striatal DAT BP as compared to off-MPH (t = −4.12, p = 0.002). A more pronounced change in striatal DAT BP was associated with higher off-MPH attentional and externalizing symptom ratings (Pearson r = 0.68, p = 0.01). Striatal DAT BP off-MPH, but not on-MPH, was associated with higher symptom ratings (Pearson r = 0.56, p = 0.04).ConclusionOur findings corroborate previous reports from mainly adult samples that MPH changes striatal DAT BP availability and suggest higher off-MPH DAT BP, likely reflecting low baseline DA levels, as a marker of symptom severity.

Using Single-Photon Emission Computerized Tomography on Patients With Positive Quantitative Electroencephalogram to Evaluate Chronic Mild Traumatic Brain Injury With Persistent Symptoms.

BackgroundFollowing mild traumatic brain injury (mTBI), also known as concussion, many patients with chronic symptoms (>3 months post injury) receive conventional imaging such as computed tomography (CT) or magnetic resonance imaging (MRI). However, these modalities often do not show changes after mTBI. We studied the benefit of triaging patients with ongoing symptoms >3 months post injury by quantitative electroencephalography (qEEG) and then completing a brain single positron emission computed tomography (SPECT) to aid in diagnosis and early detection of brain changes.MethodsWe conducted a retrospective case review of 30 outpatients with mTBI. The patients were assessed by a neurologist, consented, and received a qEEG, and if the qEEG was positive, they consented and received a brain SPECT scan. The cases and diagnostic tools were collectively reviewed by a multidisciplinary group of physicians in biweekly team meetings including neurology, nuclear medicine, psychiatry, neuropsychiatry, general practice psychotherapy, neuro-ophthalmology, and chiropractic providers. The team noted the cause of injury, post injury symptoms, relevant past medical history, physical examination findings, and diagnoses, and commented on patients' SPECT scans. We then analyzed the SPECT scans quantitatively using the 3D-SSP software.ResultsAll the patients had cerebral perfusion abnormalities demonstrated by SPECT that were mostly undetectable by conventional imaging (CT/MRI). Perfusion changes were localized primarily in the cerebral cortex, basal ganglia, and cingulate cortex, and correlated with the patients' symptoms and examination findings. Qualitative and quantitative analyses yielded similar results. Most commonly, the patients experienced persistent headache, memory loss, concentration difficulties, depression, and cognitive impairment post mTBI. Because of their symptoms, most of the patients were unable to return to their previous employment and activity level.ConclusionOur findings outline the physical basis of neurological and psychiatric symptoms experienced by patients with mTBI. Increased detection of mTBI can lead to development of improved targeted treatments for mTBI and its various sequelae.

Semimechanistic Population Pharmacokinetic Modeling to Investigate Amyloid Beta Trafficking and Accumulation at the BBB Endothelium.

Elevated exposure to toxic amyloid beta (Aβ) peptides and consequent blood-brain barrier (BBB) dysfunction are believed to promote vasculopathy in Alzheimer's disease (AD). However, the accumulation kinetics of different Aβ isoforms within the BBB endothelium and how it drives BBB dysfunction are not clearly characterized. Using single positron emission computed tomography (SPECT)-computed tomography (CT) dynamic imaging coupled with population pharmacokinetic modeling, we investigated the accumulation kinetics of Aβ40 and Aβ42 in the BBB endothelium. Brain clearance was quantified after intracerebral administration of 125I-Aβ, and BBB-mediated transport was shown to account for 54% of 125I-Aβ40 total clearance. A brain influx study demonstrated lower values of both maximal rate (Vmax) and Michaelis constant (Km) for 125I-Aβ42 compared to 125I-Aβ40. Validated by a transcytosis study in polarized human BBB endothelial cell (hCMEC/D3) monolayers, model simulations demonstrated impaired exocytosis was responsible for inefficient permeability and enhanced accumulation of Aβ42 in the BBB endothelium. Further, both isoforms were shown to disrupt the exocytosis machinery of BBB endothelial cells so that a vicious cycle could be generated. The validated model was able to capture changes in Aβ steady-state levels in plasma as well as the brain during AD progression and allowed us to predict the kinetics of Aβ accumulation in the BBB endothelium.

A Novel Mouse Model to Study Image-Guided, Radiation-Induced Cardiac Injury and Identify Clinically Relevant Predictors of Toxicity

Radiation (RT)-induced cardiac injury is a significant concern in thoracic oncology patients. The aim of this study was to develop a novel mouse model for RT-induced cardiotoxicity, which could be used to identify molecular pathophysiology and clinically-targetable biomarkers of disease development. We hypothesized that partial heart +/- lung RT would elicit dose-dependent cardiac dysfunction, perfusion deficits, inflammation, and vascular injury. Female C57BL/6 mice aged 9-11 weeks were administered an intravenous contrast agent (fenestraVC, ART Advanced Research Technologies, Saint-Laurent, Q) to visualize the heart on cone-beam computed tomography imaging using the Small Animal Radiation Research Platform. A single dose of photon RT at 0, 20, 40, or 60 Gy was delivered to the cardiac apex +/- lung using a 3x3 mm collimator and stereotactic body RT, and gamma-H2AX staining was used to confirm targeting. Quantitative echocardiography and single positron emission computed tomography (SPECT) with Technicium-99 sestamibi were implemented to evaluate myocardial function and perfusion respectively. Cardiac tissue and plasma were collected for multiparametric analysis of biochemical markers of RT injury and tissue was harvested for histologic analysis. RT resulted in dose-dependent systolic and diastolic dysfunction as measured by regional hypokinesis, decreased left ventricular ejection fraction (LVEF) (p = 0.0001, 60 Gy), and increased E/E’ (ratio between early mitral inflow velocity and mitral annular early diastolic velocity) (p = 0.002, 60 Gy) on echocardiography 8 weeks post-RT. Compared to control, apical perfusion deficits were noted on SPECT 8 weeks post-RT only at a dose of 60 Gy, with quantitative analysis revealing a reduction in tracer uptake regionally (p = 0.003, 60 Gy) and globally (nonsignificant). At 2 weeks post-RT, increases in troponin T (TnT), placental growth factor (PLGF), interleukin (IL)-6, IL-10, and tumor necrosis factor alpha (TNFa) were observed in irradiated cardiac tissue or plasma, with more pronounced increases in all cytokine levels post 40 Gy partial heart and lung RT compared to 60 Gy partial heart RT alone. Histology demonstrated perivascular fibrosis (p<0.05) and vessel lumen narrowing. A mouse model of RT-induced cardiotoxicity can be generated by the in-situ focal irradiation of the heart, and can be used to integrate radiomic and biochemical markers of cardiotoxicity to inform early therapeutic intervention.Abstract 3256; TableSelect radiologic and biochemical dataPartial heart RT dose (Gy)LVEF (%)E/E’Lateral wall apical uptake on SPECT#TnT#PLGF#IL-2#IL-6#IL-10#TNFa#067.328.2-------4062.2*33.30.710.93.6***----6053.5***36.4**0.65**2.0**15.5**1.41.73.91.8*40+lung63.831.10.543.8*8.31.85.8*8.7*3.8*#Values normalized to 0 Gy *P < 0.05; **P < 0.005; ***P < 0.0005. Open table in a new tab

PET and SPECT Imaging of Brain Neoplasia Mimics

Several non-neoplastic processes, including infection, inflammation, demyelination, vasculitis, autoimmune disease, and post-treatment changes (radiation therapy or chemoradiation) can result in a mass-like, space-occupying lesion on conventional computed tomography (CT) or magnetic resonance (MR) imaging of the brain. Additionally, non-neoplastic processes can produce imaging findings that mimic nontumoral neoplastic involvement of the central nervous system. Such instances pose a substantial diagnostic dilemma for interpreting radiologists, as well as clinicians tasked with determining the appropriate diagnostic tests and therapeutic strategies for these patients. Nuclear medicine studies, including single positron emission computed tomography (SPECT) and positron emission tomography (PET), as well as hybrid SPECT/CT, PET/CT, and PET/MRI may offer important diagnostic insights into these challenging cases, often helping to differentiate these mimics from true brain neoplasms. In this review, we detail common and uncommon brain tumor mimics in specific context of PET and SPECT imaging of the brain, including the multimodality imaging appearance of tumor mimics and the potential roles these modalities may play in providing diagnostic clarity.

Choosing the best method to utilise single positron emission computed tomography (SPECT) scans in the management of unilateral condylar hyperplasia.

Facial asymmetry secondary to unilateral condylar hyperplasia can be a diagnostic challenge to oral and maxillofacial surgeons. Single positron emission computed tomography (SPECT) scans provide a useful adjunct. We report a brief summary of the evidence describing the effectiveness of different methods of analysing SPECT scans and compare it with the results of a 10-year study at Sunderland Royal Hospital. Overall, both the evidence base and our study strongly favour use of the condyle:condyle ratio over the condyle:reference bone ratio, suggesting that no further comparisons are needed.

Noninvasive Imaging of the Immune Checkpoint LAG-3 Using Nanobodies, from Development to Pre-Clinical Use.

Immune checkpoint inhibition (ICI) is a promising cancer therapy, which has progressed rapidly from a preclinical concept to clinical implementation. Commonly considered targets in ICI are CTLA-4, PD-1/PD-L1, and LAG-3, and the list grows. As ICI is generally only beneficial for a subset of patients, there is a need to select patients that are eligible for therapy as well as to monitor therapy response. There is growing interest to do this noninvasively, by molecular imaging with target-specific tracers. To this day, noninvasive imaging has focused on CTLA-4 and PD-1/PD-L1, while there is no noninvasive tool available to accurately assess LAG-3 expression in vivo. In this proof-of-concept study, we developed nanobodies, the smallest functional fragments from camelid heavy chain-only antibodies, to noninvasively evaluate mouse LAG-3 expression using single photon emission computed tomography (SPECT)/CT imaging. The in vitro characterization of 114 nanobodies led to the selection of nine nanobodies binding to mouse LAG-3. The injection of 99mTechnetium-labeled nanobodies in healthy mice showed specific uptake in immune peripheral organs like the spleen and lymph nodes, which was not observed in LAG-3 gene knock-out mice. Moreover, nanobody uptake could be visualized using SPECT/CT and correlated to the presence of LAG-3 as assessed in flow cytometry and immunohistochemistry. SPECT/CT scans of tumor bearing mice further confirmed the diagnostic potential of the nanobodies. These findings substantiate the approach to use nanobodies as a tool to image inhibitory immune checkpoints in the tumor environment.

99mTc-Labeled LyP-1 for SPECT Imaging of Triple Negative Breast Cancer.

Triple negative breast cancer (TNBC), the most aggressive breast cancer type, is associated with high mortality and recurrence rates. An active-targeted strategy based on homing peptides is an effective approach to diagnose and treat cancer as it can deliver imaging agents or therapeutic drugs into desired tissues and accumulate less into off-target tissues. As a homing peptide, LyP-1 has shown properties of targeting, internalization, and proapoptosis to TNBC. In the study, we designed a Technetium-99m- (99mTc-) labeled LyP-1 and investigated its feasibility for targeted single-positron emission computed tomography (SPECT) imaging of TNBC. The results showed that the LyP-1 peptide had acceptable biocompatibility in the studied concentration range and could specifically bind to TNBC cells in vitro. 99mTc-labeled LyP-1 showed high radiochemical purity and stability and could be used as a probe for targeted SPECT imaging of TNBC cells in vitro and in a TNBC tumor-bearing mouse model. Our findings indicate that this active-targeted strategy has great potential to be developed into a new imaging tool for TNBC diagnosis.

In Vivo Imaging of Microglia With Multiphoton Microscopy.

Neuroimaging has become an unparalleled tool to understand the central nervous system (CNS) anatomy, physiology and neurological diseases. While an altered immune function and microglia hyperactivation are common neuropathological features for many CNS disorders and neurodegenerative diseases, direct assessment of the role of microglial cells remains a challenging task. Non-invasive neuroimaging techniques, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single positron emission computed tomography (SPECT) are widely used for human clinical applications, and a variety of ligands are available to detect neuroinflammation. In animal models, intravital imaging has been largely used, and minimally invasive multiphoton microcopy (MPM) provides high resolution detection of single microglia cells, longitudinally, in living brain. In this study, we review in vivo real-time MPM approaches to assess microglia in preclinical studies, including individual cell responses in surveillance, support, protection and restoration of brain tissue integrity, synapse formation, homeostasis, as well as in different pathological situations. We focus on in vivo studies that assess the role of microglia in mouse models of Alzheimer’s disease (AD), analyzing microglial motility and recruitment, as well as the role of microglia in anti-amyloid-β treatment, as a key therapeutic approach to treat AD. Altogether, MPM provides a high contrast and high spatial resolution approach to follow microglia chronically in vivo in complex models, supporting MPM as a powerful tool for deep intravital tissue imaging.

Weight loss is associated with rapid striatal dopaminergic degeneration in Parkinson's disease

IntroductionWeight loss in Parkinson's disease (PD) is associated with poorer clinical outcomes and rapid disease progression. However, it is unclear whether a longitudinal association between weight loss and striatal dopaminergic degeneration exists. MethodsUsing data from 171 PD patients in the Parkinson's Progression Markers Initiative (PPMI) cohort, we investigated longitudinal associations of change in body mass index (BMI) with striatal dopaminergic activity on 123I-N-3-fluoropropyl-2-beta-carboxymethoxy-3beta-(4-iodophenyl) nortropane (123I-FP-CIT) single positron emission computed tomography (SPECT). We defined BMI loss as a reduction in BMI value > 5% of baseline, and categorized the PD patients into 2 subgroups (patients with and without BMI loss). Linear mixed model (LMM) analysis was employed to compare the progression of striatal dopaminergic degeneration. ResultsIn LMM analyses, BMI values in PD patients were not correlated with clinical severities of parkinsonian motor deficits, cognitive impairment and depressive mood. However, BMI values were positively associated with changes in striatal 123I-FP-CIT binding over 24 months (caudate nucleus, estimate = 9.37 × 10−3, p = 0.009; putamen, estimate = 7.04 × 10−3, p = 0.031). Patients with BMI loss exhibited greater deterioration of striatal dopaminergic activity than those without (caudate nucleus, estimate = 3.35 × 10−3, p = 0.008; putamen, estimate = 2.34 × 10−3, p = 0.025). ConclusionOur findings suggest a potential association between striatal dopaminergic activity with body weight or impairment in energy homeostasis. Body weight and its change may be a clinical biomarker reflecting striatal dopaminergic dysfunction in PD.

Dual isotope simultaneous imaging to evaluate the effects of intracoronary bone marrow-derived mesenchymal stem cells on perfusion and metabolism in canines with acute myocardial infarction.

Stem cell therapy on acute myocardial infarction (AMI) has been performed for over a decade. In the present study, cardiac perfusion, metabolism and function in dogs with AMI treated by intracoronary injection of bone marrow-derived mesenchymal stem cells (MSCs) were evaluated by dual isotope simultaneous acquisition (DISA) of single positron emission computed tomography (SPECT). Dogs (n=12, 20-30 kg) were randomly assigned to two groups: A graft study (n=6) and control group (n=6). Bone marrow mesenchymal aspirate was collected 3 weeks before surgical procedure. Stem cells were induced by 5-azacytidine for differentiation into myocytes. The dog AMI model was produced by blocking the blood stream at 1/3 of the distinct left anterior descending coronary artery for 90 min. For dogs in the grafting group, MSCs were transplanted by intracoronary injection, and for the control group, 0.9% NaCl was injected instead. At 1 and 10 weeks after MSCs were grafted, respectively, SPECT DISA was performed for each dog in the two groups with 99mTc-SPECT MIBI (925 MBq) and 18F-FDG (222 MBq) for evaluation of myocardial perfusion and metabolism. After the dogs were sacrificed, heart tissue was stained by myocyte-specific antibodies for newborn vessels, troponin T and bromodeoxyuridine (BrdU). Following induction by 5-azacytidine, the morphological features with colony formation, microfilament, as well as atrial granules and positive stainings of α-actinin, myosin and troponin I demonstrated strongly that the MSCs differentiated into myocytes. The number of viable myocardial segments was 10 in the grafting group, which was significantly greater compared with the control group. The ejection fraction of the infarcted left ventricle (LVEF,%) increased from 53.80±9.58 to 70.00±7.52 (change, 16.20±2.93) at 1 and 10 weeks after MSCs engraftment, whilst in the control group, LVEF was 50.50±8.02 and 56.50±7.24 (change, 5.50±2.69), respectively. The LVEF difference was statistically significant (P<0.05) between the graft and control groups. Furthermore, immunostaining of all the myocyte-specific antibodies (for newly born vessels, troponin T and BrdU) was positive. In conclusion, direct intracoronary injection of bone marrow MSCs into injured myocardium in the experimental dog AMI model can significantly improve cardiac function with new vessel formation and myocyte-specific biomarker expression, and in particular, the present study further shows that DISA SPECT can be used for the assessment of stem cell transplantation in the heart.

Myocardial CT perfusion for the prediction of obstructive coronary artery disease, valuable or not?

Adenosine stress myocardial computed tomography perfusion (CTP) is a relatively new myocardial perfusion imaging technique. Together with coronary CT angiography (CTA) it provides anatomic and functional information of coronary artery disease (CAD). In previous studies, the combination of these techniques demonstrated to be valuable for identifying hemodynamically significant stenoses. George et al., performed a secondary analysis on the CORE320 study and compared the diagnostic performance of CTP to single positron emission computed tomography (SPECT) myocardial perfusion imaging (MPI) to diagnose obstructive CAD (defined as ≥50% luminal stenosis). In this editorial the results and limitations of the study are discussed, as well as opportunities that this new perfusion technique brings with it.

The usefulness of bone SPECT/CT imaging with volume of interest analysis in early axial spondyloarthritis.

BackgroundThe role of conventional bone scintigraphy in diagnosing early axial spondyloarthritis (SpA) is yet controversial. Single positron emission computed tomography (SPECT) plus CT is an imaging modality that adds better anatomical information to scintigraphy of the sacroiliac (SI) joint. Our aim was to investigate the usefulness of bone SPECT/CT with volume of interest (VOI) analysis in early axial SpA patients.MethodsTwenty patients (male: female ratio = 12:8; age range = 17–65 years) presenting with inflammatory back pain meeting the Amor criteria of early axial SpA were recruited from a single center in South Korea. Bone scintigraphy was performed 180 min after intravenous injection of 1110 MBq of Tc-99 m-HDP, followed by bone SPECT/CT. The ratio between the entire SI joint and sacrum (SIS ratio) was measured by both bone SPECT/CT and bone scintigraphy. Data from 13 controls were also evaluated. Receiver operating characteristic (ROC) curve was plotted for further analysis, and the correlation between the SIS ratio and SI joint grade by plain radiography was assessed.ResultsThe SIS ratio of early axial SpA patients vs. control subjects was significantly increased in bone SPECT/CT (p < 0.001). However, no significant difference was detected in bone scintigraphy. ROC curve analysis showed a significant difference in the area under curve (AUC) of bone SPECT/CT vs. bone scintigraphy (0.862 vs. 0.523, respectively; p < 0.001). With a cut-off SIS ratio of 1.50, ROC curve analysis showed a sensitivity of 80.0% and specificity of 84.6% in bone SPECT/CT. The SIS ratio measured in SPECT/CT, but not that measured in bone scintigraphy, was significantly increased with a higher grade of SI joint changes in plain radiography (p = 0.014).ConclusionBone SPECT/CT is more useful than conventional bone scintigraphy in identifying sacroiliitis in early axial SpA patients, even with mild SI joint changes in plain radiography. By combining CT, we can accurately delineate the sacrum and SI joint uptake with our VOI method.

Neurological Research on Music Therapy for Mental Health: A Summary of Imaging and Research Methods

IntroductionCognitive neuroscience research over the past decade has produced increasingly fascinating insights into how the human brain processes music, while also enhancing our understanding of brain processes related to many mental health disorders. With these advances, music therapists have turned to cognitive neuroscience to gain understanding in neural processes that are relevant to our field. Much of the neuroscience research in music therapy has focused upon cognitive function and training in recovery from brain injury (see, for example, Leins, Spintge, &Thaut, 2009). This knowledge base continues to grow, even daily, as new research emerges.As neuroscience also delves into the causes, manifestations, and treatments of mental illness, great potential arises for research utilizing neuroimaging techniques in order to understand the effectiveness and mechanisms for music therapy interventions for this population. In this hope, we will summarize available neuroimaging methods and research designs for these purposes and will discuss existing and potential research questions relevant to music therapy and mental health. We will also discuss the limitations of such investigation, as well as ways music therapists can enter this arena through collaboration with neuroscientists. Our aim is to spark interest in this research among clinicians and highlight the potential for increased collaboration between music therapists and neuroscientists for the purpose of understanding and improving the lives of clients coping with a mental illness.imaging MethodsWe begin by describing the most commonly used imaging methods in behavioral health research: electroencephalography (EEG), magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single positron emission computed tomography (SPECT), and functional near-infrared spectroscopy (fNIRS), as well as the potential for combining more than one approach simultaneously. In describing these methods, we discuss relevant research, particularly music therapy research, where possible. We also highlight the strengths and limitations of each method, as well as potential research questions given the capabilities of each method and what is known about mental health through these methods. A summary table (Table 1 ) compares each imaging method according to several practical criteria. Figure 1 shows sample images of data and equipment for these different techniques. The accompanying Glossary provides definitions of terminology used throughout the article, and the figure in Legge (this issue) shows relevant regions of the brain discussed throughout.Electroencephalography (EEC)EEG is a widely used neurophysiological recording technique that measures electrical activity at the surface of the scalp using a standardized array of electrodes. Although it does not result in any high-resolution visual representation of neuroanatomicai structures, a typical EEG readout provides valuable information about neuron-based electrical activity in real time. Medical professionals often use EEG to diagnose and monitor pathologies such as epilepsy, encephalopathy, and sleep disorders. A standard EEG setup includes 21 electrodes (19 scalp electrodes plus two additional reference electrodes), although some variations include more or less. Any EEG recording can be represented as several different types of readouts-called montages. Different montages actually represent different ways of viewing voltage differences between the various electrodes, so selection of an appropriate montage can have important implications. For instance, the exact location of a seizure's onset may be most apparent in a particular montage.Electromagnetic waves detected by EEG occur at different frequencies, just as sound waves do. These waves are usually divided into five major bands based on frequency: delta (up to 4 Hz), theta (4-7 Hz), alpha (8-15 Hz), beta (16-31 Hz), and gamma (32 Hz and higher). …

Reporting standards in cardiac MRI, CT, and SPECT diagnostic accuracy studies: analysis of the impact of STARD criteria

Diagnostic accuracy studies determine the clinical value of non-invasive cardiac imaging tests. The 'STAndards for the Reporting of Diagnostic accuracy studies' (STARD) were published in 2003 to improve the quality of study reporting. We aimed to assess the reporting quality of cardiac computed tomography (CCT), single positron emission computed tomography (SPECT), and cardiac magnetic resonance (CMR) diagnostic accuracy studies; to evaluate the impact of STARD; and to investigate the relationships between reporting quality, journal impact factor, and study citation index. We randomly generated six groups of 50 diagnostic accuracy studies: 'CMR 1995-2002', 'CMR 2004-11', 'CCT 1995-2002', 'CCT 2004-11', 'SPECT 1995-2002', and 'SPECT 2004-11'. The 300 studies were double-read by two blinded reviewers and reporting quality determined by % adherence to the 25 STARD criteria. Reporting quality increased from 65.3% before STARD to 74.1% after (P = 0.003) in CMR studies and from 61.6 to 79.0% (P < 0.001) in CCT studies. SPECT studies showed no significant change: 71.9% before and 71.5% after STARD (P = 0.92). Journals advising authors to refer to STARD had significantly higher impact factors than those that did not (P = 0.03), and journals with above-median impact factors published studies of significantly higher reporting quality (P < 0.001). Since STARD, citation index has not significantly increased (P = 0.14), but, after adjustment for impact factor, reporting quality continues to increase by ∼1.5% each year. Reporting standards for diagnostic accuracy studies of non-invasive cardiac imaging are at most satisfactory and have improved since the introduction of STARD. Adherence to STARD should be mandatory for authors of diagnostic accuracy studies.

Measuring hepatic functional reserve using low temporal resolution Gd-EOB-DTPA dynamic contrast-enhanced MRI: a preliminary study comparing galactosyl human serum albumin scintigraphy with indocyanine green retention

To investigate if tracer kinetic modelling of low temporal resolution dynamic contrast-enhanced (DCE) MRI with Gd-EOB-DTPA could replace technetium-99m galactosyl human serum albumin (GSA) single positron emission computed tomography (SPECT) and indocyanine green (ICG) retention for the measurement of liver functional reserve. Twenty eight patients awaiting liver resection for various cancers were included in this retrospective study that was approved by the institutional review board. The Gd-EOB-DTPA MRI sequence acquired five images: unenhanced, double arterial phase, portal phase, and 4min after injection. Intracellular contrast uptake rate (UR) and extracellular volume (Ve) were calculated from DCE-MRI, along with the ratio of GSA radioactivity of liver to heart-plus-liver and per cent of cumulative uptake from 15-16min (LHL15 and LU15, respectively) from GSA-scintigraphy. ICG retention at 15min, Child-Pugh cirrhosis score (CPS) and postoperative Inuyama fibrosis criteria were also recorded. Statistical analysis was with Spearman rank correlation analysis. Comparing MRI parameters with the reference methods, significant correlations were obtained for UR and LHL15, LU15, ICG15 (all 0.4-0.6, P < 0.05); UR and CPS (-0.64, P < 0.001); Ve and Inuyama (0.44, P < 0.05). Measures of liver function obtained by routine Gd-EOB-DTPA DCE-MRI with tracer kinetic modelling may provide a suitable method for the evaluation of liver functional reserve. • Magnetic resonance imaging (MRI) provides new methods of measuring hepatic functional reserve. • DCE-MRI with Gd-EOB-DTPA offers the possibility of replacing scintigraphy. • The analysis method can be used for preoperative liver function evaluation.

Agreement between SPECT V/Q scan and CT angiography in patients with high clinical suspicion of PE

To track agreement between single positron emission computed tomography (SPECT) V/Q and CT angiography in patients with high clinical suspicion of pulmonary embolism (PE). If significant agreement occurs, a case could be made for more frequent use of chest radiography followed by SPECT V/Q scanning given its lower risk profile. Diagnosis of PE can be difficult. CT pulmonary angiography (CTA) is the preferred initial test, but may be indeterminate, is a significant source of ionizing radiation, and is contraindicated in renal insufficiency. SPECT ventilation/perfusion imaging (V/Q) is therefore preferred in certain patients. Two thousand nine hundred and twenty patients admitted to a tertiary care hospital in New York City were screened and 100 consecutive high-risk patients who required both CTA and V/Q for an initial indeterminate or negative imaging test despite a high pre-test probability were identified. The agreement between these tests was evaluated. There was no significant agreement between CTA and V/Q when positive, negative and indeterminate results were included (K=0.18, SE=0.09, p=0.051). However, in the presence of a positive finding on either test, there was substantial agreement between the two (K=0.62, SE=0.27, p=0.02). In 30 cases in which CTA was indeterminate, V/Q was diagnostic 93% of the time. In 12 cases in which V/Q was indeterminate, CTA was diagnostic 83% of the time and negative in 100% of those cases. In the presence of an indeterminate CTA in patients with high clinical suspicion of PE, SPECT V/Q often provides a diagnosis.

AB0544 The usefulness of bone spect-ct imaging with volume of interest analysis in early axial spondyloarthritis

BackgroundImaging is an important tool in diagnosing axial spondylo-arthritis (SpA). In contrast to magnetic resonance imaging, conventional bone scintigraphy has not been so helpful for early detection of axial SpA....