MR Perfusion to Determine the Status of Collaterals in Patients with Acute Ischemic Stroke: A Look Beyond Time Maps.

BACKGROUND AND PURPOSE: Patients with acute stroke with robust collateral flow have better clinical outcomes and may benefit from endovascular treatment throughout an extended time window. Using a multiparametric approach, we aimed to identify MR perfusion parameters that can represent the extent of collaterals, approximating DSA. MATERIALS AND METHODS: Patients with anterior circulation proximal arterial occlusion who had baseline MR perfusion and DSA were evaluated. The volume of arterial tissue delay (ATD) at thresholds of 2-6 seconds (ATD2-6 seconds) and >6 seconds (ATD>6 seconds) in addition to corresponding values of normalized CBV and CBF was calculated using VOI analysis. The association of MR perfusion parameters and the status of collaterals on DSA were assessed by multivariate analyses. Receiver operating characteristic analysis was performed. RESULTS: Of 108 patients reviewed, 39 met our inclusion criteria. On DSA, 22/39 (56%) patients had good collaterals. Patients with good collaterals had significantly smaller baseline and final infarct volumes, smaller volumes of severe hypoperfusion (ATD>6 seconds), larger volumes of moderate hypoperfusion (ATD2-6 seconds), and higher relative CBF and relative CBV values than patients with insufficient collaterals. Combining the 2 parameters into a Perfusion Collateral Index (volume of ATD2-6 seconds × relative CBV2-6 seconds) yielded the highest accuracy for predicting collateral status: At a threshold of 61.7, this index identified 15/17 (88%) patients with insufficient collaterals and 22/22 (100%) patients with good collaterals, for an overall accuracy of 94.1%. CONCLUSIONS: The Perfusion Collateral Index can predict the baseline collateral status with 94% diagnostic accuracy compared with DSA.

Synthetic MRI for Clinical Neuroimaging: Results of the Magnetic Resonance Image Compilation (MAGiC) Prospective, Multicenter, Multireader Trial.

BACKGROUND AND PURPOSE: Synthetic MR imaging enables reconstruction of various image contrasts from 1 scan, reducing scan times and potentially providing novel information. This study is the first large, prospective comparison of synthetic-versus-conventional MR imaging for routine neuroimaging. MATERIALS AND METHODS: A prospective multireader, multicase noninferiority trial of 1526 images read by 7 blinded neuroradiologists was performed with prospectively acquired synthetic and conventional brain MR imaging case-control pairs from 109 subjects (mean, 53.0 ± 18.5 years of age; range, 19-89 years of age) with neuroimaging indications. Each case included conventional T1- and T2-weighted, T1 and T2 FLAIR, and STIR and/or proton density and synthetic reconstructions from multiple-dynamic multiple-echo imaging. Images were randomized and independently assessed for diagnostic quality, morphologic legibility, radiologic findings indicative of diagnosis, and artifacts. RESULTS: Clinical MR imaging studies revealed 46 healthy and 63 pathologic cases. Overall diagnostic quality of synthetic MR images was noninferior to conventional imaging on a 5-level Likert scale (P < .001; mean synthetic-conventional, -0.335 ± 0.352; Δ = 0.5; lower limit of the 95% CI, -0.402). Legibility of synthetic and conventional morphology agreed in >95%, except in the posterior limb of the internal capsule for T1, T1 FLAIR, and proton-density views (all, >80%). Synthetic T2 FLAIR had more pronounced artifacts, including +24.1% of cases with flow artifacts and +17.6% cases with white noise artifacts. CONCLUSIONS: Overall synthetic MR imaging quality was similar to that of conventional proton-density, STIR, and T1- and T2-weighted contrast views across neurologic conditions. While artifacts were more common in synthetic T2 FLAIR, these were readily recognizable and did not mimic pathology but could necessitate additional conventional T2 FLAIR to confirm the diagnosis.

Form and function of the intervertebral disc in health and disease: a morphological and stain comparison study.

Multiple histologic measurements are commonly used to assess degenerative changes in intervertebral disc (IVD) structure; however, there is no consensus on which stains offer the clearest visualization of specific areas within the IVD. The objective of this study was to compare multiple tinctorial stains, evaluate their ability to highlight structural features within the IVD, and investigate how they influence the capacity to implement a degeneration scoring system. Lumbar IVDs from seven human autopsy specimens were stained using six commonly used stains (Hematoxylin/Eosin, Toluidine Blue, Safranin-O/Fast Green, Extended FAST, modified Gomori's Trichrome, and Picrosirius Red Alcian Blue). All IVDs were evaluated by three separate graders to independently determine which stains (i) were most effective at discerning different structural features within different regions of the IVDs and (ii) allowed for the most reproducible assessment of degeneration grade, as assessed via the Rutges histological scoring system (Rutges et al. A validated new histological classification for intervertebral disc degeneration. Osteoarthritis Cartilage, 21, 2039-47). Although Trichrome, XFAST and PR/AB stains were all effective at highlighting different regions of whole IVDs, we recommend the use of PR/AB because it had the highest degree of rater agreement on assigned degeneration grade, allowed greater resolution of degeneration grade, has an inferential relationship between color and composition, and allowed clear differentiation of the different regions and structural disruptions within the IVD. The use of a standard set of stains together with a histological grading scheme can aid in the characterization of structural changes in different regions of the IVD and may simplify comparisons across the field. This collection of human IVD histological images highlights how IVD degeneration is not a single disease but a composite of multiple processes such as aging, injury, repair, and disease, each of which are unique to the individual.

Ultra-High-Field MR Neuroimaging.

At ultra-high magnetic fields, such as 7T, MR imaging can noninvasively visualize the brain in unprecedented detail and through enhanced contrast mechanisms. The increased SNR and enhanced contrast available at 7T enable higher resolution anatomic and vascular imaging. Greater spectral separation improves detection and characterization of metabolites in spectroscopic imaging. Enhanced blood oxygen level-dependent contrast affords higher resolution functional MR imaging. Ultra-high-field MR imaging also facilitates imaging of nonproton nuclei such as sodium and phosphorus. These improved imaging methods may be applied to detect subtle anatomic, functional, and metabolic abnormalities associated with a wide range of neurologic disorders, including epilepsy, brain tumors, multiple sclerosis, Alzheimer disease, and psychiatric conditions. At 7T, however, physical and hardware limitations cause conventional MR imaging pulse sequences to generate artifacts, requiring specialized pulse sequences and new hardware solutions to maximize the high-field gain in signal and contrast. Practical considerations for ultra-high-field MR imaging include cost, siting, and patient experience.

Tauopathy PET and amyloid PET in the diagnosis of chronic traumatic encephalopathies: studies of a retired NFL player and of a man with FTD and a severe head injury.

Single, severe traumatic brain injury (TBI) which elevates CNS amyloid, increases the risk of Alzheimer's disease (AD); while repetitive concussive and subconcussive events as observed in athletes and military personnel, may increase the risk of chronic traumatic encephalopathy (CTE). We describe two clinical cases, one with a history of multiple concussions during a career in the National Football League (NFL) and the second with frontotemporal dementia and a single, severe TBI. Both patients presented with cognitive decline and underwent [(18)F]-Florbetapir positron emission tomography (PET) imaging for amyloid plaques; the retired NFL player also underwent [(18)F]-T807 PET imaging, a new ligand binding to tau, the main constituent of neurofibrillary tangles (NFT). Case 1, the former NFL player, was 71 years old when he presented with memory impairment and a clinical profile highly similar to AD. [(18)F]-Florbetapir PET imaging was negative, essentially excluding AD as a diagnosis. CTE was suspected clinically, and [(18)F]-T807 PET imaging revealed striatal and nigral [(18)F]-T807 retention consistent with the presence of tauopathy. Case 2 was a 56-year-old man with personality changes and cognitive decline who had sustained a fall complicated by a subdural hematoma. At 1 year post injury, [(18)F]-Florbetapir PET imaging was negative for an AD pattern of amyloid accumulation in this subject. Focal [(18)F]-Florbetapir retention was noted at the site of impact. In case 1, amyloid imaging provided improved diagnostic accuracy where standard clinical and laboratory criteria were inadequate. In that same case, tau imaging with [(18)F]-T807 revealed a subcortical tauopathy that we interpret as a novel form of CTE with a distribution of tauopathy that mimics, to some extent, that of progressive supranuclear palsy (PSP), despite a clinical presentation of amnesia without any movement disorder complaints or signs. A key distinguishing feature is that our patient presented with hippocampal involvement, which is more frequently seen in CTE than in PSP. In case 2, focal [(18)F]-Florbetapir retention at the site of injury in an otherwise negative scan suggests focal amyloid aggregation. In each of these complex cases, a combination of [(18)F]-fluorodeoxyglucose, [(18)F]-Florbetapir and/or [(18)F]-T807 PET molecular imaging improved the accuracy of diagnosis and prevented inappropriate interventions.

Diffusion-weighted MRI "claw sign" improves differentiation of infectious from degenerative modic type 1 signal changes of the spine.

BACKGROUND AND PURPOSE: Modic type 1 degenerative signal changes can mimic/suggest infection, leading to additional costly and sometimes invasive investigations. This retrospective study analyzes the utility and accuracy of a novel, diffusion-weighted "claw sign" for distinguishing symptomatic type 1 degeneration from vertebral diskitis/osteomyelitis. MATERIALS AND METHODS: Seventy-three patients with imaging features resembling type 1 degeneration were classified clinically into 3 groups: true degenerative type 1 changes (n = 33), confirmed diskitis/osteomyelitis (n = 20), and radiologically suspected infection later disproved clinically (n = 20). A claw sign was defined on DWI as well-marginated, linear, regions of high signal situated within the adjacent vertebral bodies at the interface of normal with abnormal marrow. Two blinded neuroradiologists independently rated the presence of the claw sign, along with T2 disk signal and disk and endplate enhancement to determine the utility of each for identifying degeneration versus infection. RESULTS: When the 2 neuroradiologists identified a definite claw, 38 of 39 patients (97%) and 29 of 29 patients (100%) proved to be infection-free. When the readers identified a probable claw, 14 of 14 patients (100%) and 16 of 19 patients (84%) proved to be infection-free. Conversely, when the readers identified the absence of claw sign (diffuse DWI pattern), there was proved infection in 17 of 17 cases (100%) and 13 of 14 cases (93%). CONCLUSIONS: In patients with type 1 signal changes of the vertebral disk space, a claw sign is highly suggestive of degeneration and its absence strongly suggests diskitis/osteomyelitis.

Illustrated review of the embryology and development of the facial region, part 2: Late development of the fetal face and changes in the face from the newborn to adulthood.

The later embryogenesis of the fetal face and the alteration in the facial structure from birth to adulthood have been reviewed. Part 3 of the review will address the molecular mechanisms that are responsible for the changes described in parts 1 and 2.

Illustrated review of the embryology and development of the facial region, part 3: an overview of the molecular interactions responsible for facial development.

SUMMARY: Parts 1 and 2 of this review discussed the complex morphogenesis of the face. However, the molecular processes that drive the morphology of the face were not addressed. Part 3 of this review will present an overview of the genes and their products that have been implicated in the developing face.

[How to prepare an oral presentation and a conference]. / ¿Cómo preparar una comunicación oral y una conferencia?

The final aim of any scientific presentation is to transmit information clearly and effectively in a way that enables the members of the audience to assimilate it but also stimulates their intellects. The success of an oral presentation depends not only on the content of the presentation, but also on the speaker's skills in transmitting the information and making it attractive. To rise to the challenge posed by these objectives, presenters must work through different preparatory phases such as identifying the aims of the talk, preparing the contents of the talk, designing the presentation, and rehearsing the talk. This special article provides some useful recommendations for successful scientific presentations. It is intended for both new and experienced presenters.

Illustrated review of the embryology and development of the facial region, part 1: Early face and lateral nasal cavities.

The early embryological development of the face has been reviewed. One repeating theme to note is the serial closing and then the re-opening of a space. This is seen in the separation of the nasal and oral cavities, the nostrils, and in part 2 the developing eyelids fusing and then re-opening. Part 2 will discuss the further facial development as well as the changes in facial bone appearance after birth.

Crista galli pneumatization is an extension of the adjacent frontal sinuses.

BACKGROUND AND PURPOSE: The crista galli is part of the ethmoid bone and, as such, it could be expected that aeration of the crista would come from ethmoid cells. After observing crista pneumatization from the frontal sinuses in several cases, we undertook this study to establish how often crista galli pneumatization came from the frontal sinuses rather than from the ethmoid complex. MATERIALS AND METHODS: Two hundred consecutive CT scans of the paranasal sinuses were studied in adult patients to obtain the incidence of crista galli pneumatization and the cell of origin for this phenomenon. A second group of 132 children, 0-7 years of age, was studied to see if any crista galli pneumatization occurred before frontal sinus development. A third group of 79 children, 7-12 years of age, was also studied to see when crista pneumatization occurred in children whose frontal sinuses had already extended into the squamosal portion of the frontal bone. RESULTS: Of the 200 adult cases, there were 26 patients (13%) with crista galli pneumatization, all from either the left or right frontal sinuses. In the second group of children 0-7 years of age, there were no cases of crista pneumatization. In the third group of children 7-12 years of age, there were 4 cases of crista galli pneumatization, all from well-developed frontal sinuses. CONCLUSIONS: Our study indicates that crista galli pneumatization is virtually exclusively from either the left or right frontal sinuses and not from displaced ethmoid complex cells in the frontal recess. This finding may have surgical implications when disease is present in the crista galli.

The jugular foramen: imaging strategy and detailed anatomy at 3T.

BACKGROUND AND PURPOSE: The purpose of this study was to assess how well the anatomy of the jugular foramen (JF) could be displayed by 3T MR imaging by using a 3D contrast-enhanced fast imaging employing steady-state acquisition sequence (CE-FIESTA) and a 3D contrast-enhanced MR angiographic sequence (CE-MRA). MATERIALS AND METHODS: Twenty-five patients free of skull base lesions were imaged on a 3T MR imaging scanner using CE-FIESTA and CE-MRA. Two readers analyzed the images in collaboration, with the following objectives: 1) to score the success with which these sequences depicted the glossopharyngeal (CNIX) and vagus (CNX) nerves, their ganglia, and the spinal root of the accessory nerve (spCNXI) within the JF, and 2) to determine the value of anatomic landmarks for the in vivo identification of these structures. RESULTS: CE-FIESTA and CE-MRA displayed CNIX in 90% and 100% of cases, respectively, CNX in 94% and 100%, and spCNXI in 51% and 0% of cases. The superior ganglion of CNIX was discernible in 89.8% and 87.8%; the inferior ganglion of CNIX, in 73% and 100%; and the superior ganglion of CNX, in 98% and 100% of cases. Landmarks useful for identifying these structures were the inferior petrosal sinus and the external opening of the cochlear aqueduct. CONCLUSIONS: This study protocol is excellent for displaying the complex anatomy of the JF and related structures. It is expected to aid in detecting small pathologies affecting the JF and in planning the best surgical approach to lesions affecting the JF.

Zonal frequency analysis of the gyral and sulcal extent of cerebral infarcts. Part III: Middle cerebral artery and watershed infarcts.

We tested the hypothesis that frequency analysis of the anatomic zones affected by single anterior (A), posterior (P), and middle (M) cerebral artery (CA), multivessel, and watershed infarcts will disclose specific sites (peak zones) most frequently involved by each type, sites most frequently injured by multiple different types (vulnerable zones), and overlapping sites of equal relative frequency for two or more different types of infarct (equal frequency zones). We adopted precise definitions of each vascular territory. CT and MRI studies of 50 MCA, 20 ACA-MCA, three PCA-MCA, and 30 parasagittal watershed infarcts were mapped onto a standard template. Relative infarct frequencies in each zone were analyzed within and across infarct types to identify the centers and peripheries of each, vulnerable zones, and equal frequency zones. These data were then correlated with the prior analysis of 47 ACA, PCA, dual ACA-PCA, and ACA-PCA-MCA infarcts. Zonal frequency data for MCA and watershed infarcts, the sites of peak infarct frequency, the sites of vulnerability to diverse infarcts, and the overlapping sites of equal infarct frequency are tabulated and displayed in standardized format for direct comparison of different infarcts. This method successfully displays the nature, sites, and extent of individual infarct types, illustrates the shifts in zonal frequency and lesion center that attend dual and triple infarcts, and clarifies the relationships among the diverse types of infarct.

Inferior central sulcus: variations of anatomy and function on the example of the motor tongue area.

We wanted to define the position of the primary motor tongue area (MTA) by using functional magnetic resonance imaging (fMRI) to display the MTA in relation to the inferolateral segment of the central sulcus (CS). The anatomy of the inferolateral segment was analyzed in 24 healthy subjects, using the magnetization prepared rapid acquisition gradient echo sequence. The position of the MTA was defined in 11 subjects by using fMRI to identify the sites of maximal activation for each subject in relation to that subject's own CS. The MTA was then displayed in three orthogonal planes, and in lateral surface reformations. The inferolateral segment displayed two distinct curves in 33 of 48 (69%) hemispheres, three curves in 6%, and four curves in 23%. Significant paradigm correlated activations were found in every hemisphere. Thereof 89 local maxima were determined, with 84 (94%) located in the region of the CS. Sixty-seven (80%) of the 84 CS activations lay along the two lowest curves of the CS. In 86% of cases, activations situated in the middle and deep portion of the anterior bank of the CS were encompassed within the three axial sections centered on the cella media of the lateral ventricles. In conclusion, the variability of the inferior CS segment precluded the assignment of the MTA to a specific anatomic configuration. However, the position of the MTA could be approximated by the intersection between the CS and the three axial planes through, just above, and just below the cella media of the lateral ventricles.

Vascular territories and watersheds: a zonal frequency analysis of the gyral and sulcal extent of cerebral infarcts. Part I: the anatomic template.

Our purpose was to establish a template of upper cerebral anatomy suitable for analysis of infarct distribution and for comparison among infarct types. We made a standard diagram of the key gyri and sulci of the supraventricular and occipital regions, partitioned the gray matter and white matter into specific zones useful for analyzing infarcts by CT and MRI, and numbered each zone uniquely in to establish a template suitable for tabulating the precise regions affected by each infarct and for analyzing differences among infarcts. The template provides a method for extracting a standardized set of data from CT or MRI performed at any angle, reconfiguring those data into a standard image, and characterizing the specific portions of infarcted brain in terms of unique numbers suitable for tabulation, collation and comparison. Standardization of the format provides for later computer analysis of increasing numbers of diverse infarcts. This method may be extended to any other type of pathology, although successful analysis of different lesions may require partitioning the gray and white matter zones in different ways.

Distension technique to improve computed tomographic evaluation of oral cavity lesions.

BACKGROUND: The apposing mucosa of the oral cavity makes the computed tomographic identification of a clinically obvious mass difficult. Contrast distension techniques have been used in radiology to evaluate for presence of a "hidden" mass. OBJECTIVE: To illustrate the utility of distending the oral cavity with air, water, or contrast to display otherwise obscure oral cavity lesions. PATIENTS AND METHODS: In 3 normal subjects and 5 patients with biopsy-proved oral cavity lesions, serial contiguous 3-mm axial and coronal computed tomographic scans were obtained before and after distension of the oral cavity using intraoral air or water. Air distension was achieved by having the subjects perform a modified Valsalva maneuver during the scan acquisitions. Fluid distension was obtained using approximately 40 mL of water. RESULTS: In each case, the contrast successfully distended the oral cavity, separating the mucosal surfaces. Gingivobuccal lesions that were obscured by apposition of the lips and cheeks to the gums and teeth, or by apposition of the tongue to the inner margins of the gums and teeth, were clearly demonstrated. Lesions involving or extending into the retromolar trigone were also well demonstrated using this distension technique. CONCLUSIONS: Computed tomographic display of the anatomy and pathology of the oral cavity can be improved simply by distending the oral cavity using air or water as a contrast medium. This technique successfully shows lesions that are obscured by the apposing surfaces of the vestibule and the oral cavity proper, improving computed tomographic diagnosis.

The motor cortex: anatomic substrates of function.

This article provides a firm foundation in the gross and microscopic anatomy of the motor cortex. It reviews the sites, Brodmann regions, normal function, and deficits associated with the primary motor cortex, supplementary motor area, presupplementary motor area, and the cingulate motor area in preparation for understanding the functional MR imaging studies that are reviewed in the later articles.

Functional magnetic resonance imaging: factors modulating the cortical activation pattern of the motor system.

The use of functional MR imaging (fMRI), especially in a clinical setting, requires knowledge and control of the physiologic factors that can affect the hemodynamic response of the brain. In this article, the authors review the influence of elementary parameters of the motor system such as hemispheric dominance, rate, and force of action, and complexity of a paradigm in determining the cortical fMRI signal change.