Severe CNS involvement in a subset of long-term treated children with infantile-onset Pompe disease.

INTRODUCTION: The standard of care for patients with infantile-onset Pompe disease (IOPD) is enzyme replacement therapy (ERT), which does not cross the blood brain barrier. While neuromuscular manifestations of IOPD are well-described, central nervous system (CNS) manifestations of this disorder are far less characterized. Here we describe severe CNS-related neurological manifestations including seizures and encephalopathy in six individuals with IOPD. METHOD: We identified six children with IOPD who developed CNS manifestations such as seizures and/or encephalopathy. We studied their brain magnetic resonance imaging scans (MRIs) and graded the severity of white matter hyperintensities (WMHI) using the Fazekas scale scoring system as previously published. Longitudinal cognitive measures were available from 4/6 children. RESULTS: All six IOPD patients (4 males/2 females) had been treated with ERT for 12-15 years. Seizures and/or encephalopathy were noted at a median age at onset of 11.9 years (range 9-15 years). All were noted to have extensive WMHI in the brain MRIs and very high Fazekas scores which preceded the onset of neurological symptoms. Longitudinal IQ scores from four of these children suggested developmental plateauing. DISCUSSION: Among a subset of IOPD patients on long-term ERT, CNS manifestations including hyperreflexia, encephalopathy and seizures may become prominent, and there is likely an association between these symptoms and significant WMHI on MRI. Further study is needed to identify risk factors for CNS deterioration among children with IOPD and develop interventions to prevent neurological decline.

Lessons Learned From AJR Neuroradiology Manuscript Reviews: Informative Advice for Prospective Authors in All Fields of Radiology.

OBJECTIVE. Comments from manuscript reviews are helpful for guiding a decision about publication and also afford a source of valuable information about how to improve a manuscript. This article is a compendium of comments from reviews of AJR Neuroradiology/Head and Neck Imaging manuscripts that, collectively, serve as a guide for writing a manuscript in any field of radiology. The comments provide examples of previously published AJR guidelines for a manuscript that will have a high likelihood of being published. CONCLUSION. Reviewers devote substantial time and effort to manuscript reviews and provide them to authors at no cost. Their comments provide an important and valuable supply of instruction for authors. Those comments often reflect criteria for judging the worth of a manuscript and reflect sound principles for composing a manuscript. Authors are encouraged to avail themselves of these resources.

A Shorter Invitation Period for AJR Manuscript Reviewers: Impact on Time to Completion of Reviews.

OBJECTIVE. The objective of this article was to study the effect of decreasing the time allowed an American Journal of Roentgenology (AJR) reviewer to consider an invitation to review on time for two invitees to accept an invitation and time for both reviewers to return reviews. MATERIALS AND METHODS. Neuroradiology manuscripts submitted between September 2015 and June 2017 were randomly assigned in a blinded manner to one of two groups. The groups allowed either a 3-day or a 1-day period for invited reviewers to accept the invitation to review. The AJR manuscript database was examined to determine the effect of the invitation acceptance period on time needed for two reviewers to accept an invitation, the number of reviewers who needed to be contacted before two accepted, and the period of time required for both reviewers to submit their review. The differences were then analyzed using a two-sample t test. RESULTS. A total of 87 manuscripts were sent to reviewers who had 1 day to respond to the invitation and 114 manuscripts were sent to reviewers with a 3-day invitation. The mean length of time for two reviewers to accept invitations was 6.65 days in the 1-day group and 10.24 days in the 3-day group (p = 0.04). The mean number of reviewers contacted before two accepted was 6.14 in the 1-day group and 6.36 in the 3-day group (p = 0.71). The mean number of days before two completed reviews were submitted by the 1-day group was 27.97 days, and the mean number for the 3-day group was 31.53 days (p = 0.04). CONCLUSION. The results suggest that allowing a shorter time for prospective reviewers to consider an invitation can decrease the time needed for the required number of reviewers to accept an invitation to review and for completed reviews to be submitted.

Peering Into Peer Review: AJR Neuroradiology Reviewers Discuss Their Approaches to Assessing a Manuscript.

OBJECTIVE. This article provides comments from a small group of highly qualified reviewers of the American Journal of Roentgenology (AJR) regarding their approach to assessing manuscripts. The objective is to educate authors about the issues to which reviewers particularly attend and about errors that will decrease the likelihood of publication. CONCLUSION. By following the advice provided in this article, authors should be able to compose better manuscripts and reviewers should be able to generate better reviews.

Magnetic resonance perfusion for differentiating low-grade from high-grade gliomas at first presentation.

BACKGROUND: Gliomas are the most common primary brain tumour. They are graded using the WHO classification system, with Grade II-IV astrocytomas, oligodendrogliomas and oligoastrocytomas. Low-grade gliomas (LGGs) are WHO Grade II infiltrative brain tumours that typically appear solid and non-enhancing on magnetic resonance imaging (MRI) scans. People with LGG often have little or no neurologic deficit, so may opt for a watch-and-wait-approach over surgical resection, radiotherapy or both, as surgery can result in early neurologic disability. Occasionally, high-grade gliomas (HGGs, WHO Grade III and IV) may have the same MRI appearance as LGGs. Taking a watch-and-wait approach could be detrimental for the patient if the tumour progresses quickly. Advanced imaging techniques are increasingly used in clinical practice to predict the grade of the tumour and to aid clinical decision of when to intervene surgically. One such advanced imaging technique is magnetic resonance (MR) perfusion, which detects abnormal haemodynamic changes related to increased angiogenesis and vascular permeability, or "leakiness" that occur with aggressive tumour histology. These are reflected by changes in cerebral blood volume (CBV) expressed as rCBV (ratio of tumoural CBV to normal appearing white matter CBV) and permeability, measured by Ktrans. OBJECTIVES: To determine the diagnostic test accuracy of MR perfusion for identifying patients with primary solid and non-enhancing LGGs (WHO Grade II) at first presentation in children and adults. In performing the quantitative analysis for this review, patients with LGGs were considered disease positive while patients with HGGs were considered disease negative.To determine what clinical features and methodological features affect the accuracy of MR perfusion. SEARCH METHODS: Our search strategy used two concepts: (1) glioma and the various histologies of interest, and (2) MR perfusion. We used structured search strategies appropriate for each database searched, which included: MEDLINE (Ovid SP), Embase (Ovid SP), and Web of Science Core Collection (Science Citation Index Expanded and Conference Proceedings Citation Index). The most recent search for this review was run on 9 November 2016.We also identified 'grey literature' from online records of conference proceedings from the American College of Radiology, European Society of Radiology, American Society of Neuroradiology and European Society of Neuroradiology in the last 20 years. SELECTION CRITERIA: The titles and abstracts from the search results were screened to obtain full-text articles for inclusion or exclusion. We contacted authors to clarify or obtain missing/unpublished data.We included cross-sectional studies that performed dynamic susceptibility (DSC) or dynamic contrast-enhanced (DCE) MR perfusion or both of untreated LGGs and HGGs, and where rCBV and/or Ktrans values were reported. We selected participants with solid and non-enhancing gliomas who underwent MR perfusion within two months prior to histological confirmation. We excluded studies on participants who received radiation or chemotherapy before MR perfusion, or those without histologic confirmation. DATA COLLECTION AND ANALYSIS: Two review authors extracted information on study characteristics and data, and assessed the methodological quality using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. We present a summary of the study characteristics and QUADAS-2 results, and rate studies as good quality when they have low risk of bias in the domains of reference standard of tissue diagnosis and flow and timing between MR perfusion and tissue diagnosis.In the quantitative analysis, LGGs were considered disease positive, while HGGs were disease negative. The sensitivity refers to the proportion of LGGs detected by MR perfusion, and specificity as the proportion of detected HGGs. We constructed two-by-two tables with true positives and false negatives as the number of correctly and incorrectly diagnosed LGG, respectively, while true negatives and false positives are the number of correctly and incorrectly diagnosed HGG, respectively.Meta-analysis was performed on studies with two-by-two tables, with further sensitivity analysis using good quality studies. Limited data precluded regression analysis to explore heterogeneity but subgroup analysis was performed on tumour histology groups. MAIN RESULTS: Seven studies with small sample sizes (4 to 48) met our inclusion criteria. These were mostly conducted in university hospitals and mostly recruited adult patients. All studies performed DSC MR perfusion and described heterogeneous acquisition and post-processing methods. Only one study performed DCE MR perfusion, precluding quantitative analysis.Using patient-level data allowed selection of individual participants relevant to the review, with generally low risks of bias for the participant selection, reference standard and flow and timing domains. Most studies did not use a pre-specified threshold, which was considered a significant source of bias, however this did not affect quantitative analysis as we adopted a common rCBV threshold of 1.75 for the review. Concerns regarding applicability were low.From published and unpublished data, 115 participants were selected and included in the meta-analysis. Average rCBV (range) of 83 LGGs and 32 HGGs were 1.29 (0.01 to 5.10) and 1.89 (0.30 to 6.51), respectively. Using the widely accepted rCBV threshold of <1.75 to differentiate LGG from HGG, the summary sensitivity/specificity estimates were 0.83 (95% CI 0.66 to 0.93)/0.48 (95% CI 0.09 to 0.90). Sensitivity analysis using five good quality studies yielded sensitivity/specificity of 0.80 (95% CI 0.61 to 0.91)/0.67 (95% CI 0.07 to 0.98). Subgroup analysis for tumour histology showed sensitivity/specificity of 0.92 (95% CI 0.55 to 0.99)/0.42 (95% CI 0.02 to 0.95) in astrocytomas (6 studies, 55 participants) and 0.77 (95% CI 0.46 to 0.93)/0.53 (95% CI 0.14 to 0.88) in oligodendrogliomas+oligoastrocytomas (6 studies, 56 participants). Data were too sparse to investigate any differences across subgroups. AUTHORS' CONCLUSIONS: The limited available evidence precludes reliable estimation of the performance of DSC MR perfusion-derived rCBV for the identification of grade in untreated solid and non-enhancing LGG from that of HGG. Pooled data yielded a wide range of estimates for both sensitivity (range 66% to 93% for detection of LGGs) and specificity (range 9% to 90% for detection of HGGs). Other clinical and methodological features affecting accuracy of the technique could not be determined from the limited data. A larger sample size of both LGG and HGG, preferably using a standardised scanning approach and with an updated reference standard incorporating molecular profiles, is required for a definite conclusion.

Assessment of quantitative magnetic resonance imaging metrics in the brain through the use of a novel phantom.

OBJECTIVE: Multisite and longitudinal neuroimaging studies are important in uncovering trajectories of recovery and neurodegeneration following traumatic brain injury (TBI) and concussion through the use of diffusion tensor imaging (DTI) and other imaging modalities. This study assessed differences in anisotropic diffusion measurement across four scanners using a human and a novel phantom developed in conjunction with the Chronic Effects of Neurotrauma Consortium. METHOD: Human scans provided measurement within biological tissue, and the novel physical phantom provided measures of anisotropic intra-tubular diffusion to serve as a model for intra-axonal water diffusion. Intra- and inter-scanner measurement variances were compared, and the impact on effect size was calculated. RESULTS: Intra-scanner test-retest reliability estimates for fractional anisotropy (FA) demonstrated relative stability over testing intervals. The human tissue and phantom showed similar FA ranges, high linearity and large within-device effect sizes. However, inter-scanner measures of FA indicated substantial differences, some of which exceeded typical DTI effect sizes in mild TBI. CONCLUSION: The diffusion phantom may be used to better elucidate inter-scanner variability in DTI-based measurement and provides an opportunity to better calibrate results obtained from scanners used in multisite and longitudinal studies. Novel solutions are being evaluated to understand and potentially overcome these differences.

Clinical outcomes of children with abnormal newborn screening results for Krabbe disease in New York State.

BACKGROUND: Early infantile Krabbe disease is rapidly fatal, but hematopoietic stem cell transplantation (HSCT) may improve outcomes if performed soon after birth. New York State began screening all newborns for Krabbe disease in 2006. METHODS: Infants with abnormal newborn screen results for Krabbe disease were referred to specialty-care centers. Newborns found to be at high risk for Krabbe disease underwent a neurodiagnostic battery to determine the need for emergent HSCT. RESULTS: Almost 2 million infants were screened. Five infants were diagnosed with early infantile Krabbe disease. Three died, two from HSCT-related complications and one from untreated disease. Two children who received HSCT have moderate to severe developmental delays. Forty-six currently asymptomatic children are considered to be at moderate or high risk for development of later-onset Krabbe disease. CONCLUSIONS: These results show significant HSCT-associated morbidity and mortality in early infantile Krabbe disease and raise questions about its efficacy when performed in newborns diagnosed through newborn screening. The unanticipated identification of "at risk" children introduces unique ethical and medicolegal issues. New York's experience raises questions about the risks, benefits, and practicality of screening newborns for Krabbe disease. It is imperative that objective assessments be made on an ongoing basis as additional states begin screening for this disorder.Genet Med 18 12, 1235-1243.

Imaging of Herpesvirus Infections of the CNS.

OBJECTIVE: Herpesviridae are a family of DNA viruses remarkable for their ability to both promote acute infection and enter a latent phase with potential of reactivation. Herpes infections are ubiquitous throughout the human life span, regardless of the degree of immunocompetence. CONCLUSION: We review the virology and clinical manifestations of each herpesvirus, with emphasis on recent advances in knowledge and characteristic neuroimaging findings important for diagnosis and appropriate clinical management.

Imaging of Cerebrovascular Disease in Pregnancy and the Puerperium.

OBJECTIVE: The purpose of this article is to review the unique physiologic changes that characterize pregnancy and the puerperium, some that substantially affect the cerebrovascular system. Conditions that can cause neurologic deterioration and share features with preeclampsia-eclampsia include postpartum angiopathy, reversible cerebral vasoconstriction syndrome, posterior reversible encephalopathy syndrome, and amniotic fluid embolism. Other conditions not specific to this patient group include cerebral venous thrombosis, cervicocephalic arterial dissection, ischemic stroke, and hemorrhagic stroke, which can pose specific diagnostic and therapeutic challenges. CONCLUSION: Radiologists must be familiar with the imaging findings of cerebrovascular complications and pathologic entities encountered during pregnancy and the puerperium. Ongoing improvements in understanding of molecular changes during pregnancy and the puerperium and advances in diagnostic tests should allow radiologists to continue to make important contributions to the care of this patient population.

Indocyanine green-loaded nanoparticles for image-guided tumor surgery.

Detecting positive tumor margins and local malignant masses during surgery is critical for long-term patient survival. The use of image-guided surgery for tumor removal, particularly with near-infrared fluorescent imaging, is a potential method to facilitate removing all neoplastic tissue at the surgical site. In this study we demonstrate a series of hyaluronic acid (HLA)-derived nanoparticles that entrap the near-infrared dye indocyanine green, termed NanoICG, for improved delivery of the dye to tumors. Self-assembly of the nanoparticles was driven by conjugation of one of three hydrophobic moieties: aminopropyl-1-pyrenebutanamide (PBA), aminopropyl-5ß-cholanamide (5ßCA), or octadecylamine (ODA). Nanoparticle self-assembly, dye loading, and optical properties were characterized. NanoICG exhibited quenched fluorescence that could be activated by disassembly in a mixed solvent. NanoICG was found to be nontoxic at physiologically relevant concentrations and exposure was not found to inhibit cell growth. Using an MDA-MB-231 tumor xenograft model in mice, strong fluorescence enhancement in tumors was observed with NanoICG using a fluorescence image-guided surgery system and a whole-animal imaging system. Tumor contrast with NanoICG was significantly higher than with ICG alone.

Principles of T2 *-weighted dynamic susceptibility contrast MRI technique in brain tumor imaging.

Dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) is used to track the first pass of an exogenous, paramagnetic, nondiffusible contrast agent through brain tissue, and has emerged as a powerful tool in the characterization of brain tumor hemodynamics. DSC-MRI parameters can be helpful in many aspects, including tumor grading, prediction of treatment response, likelihood of malignant transformation, discrimination between tumor recurrence and radiation necrosis, and differentiation between true early progression and pseudoprogression. This review aims to provide a conceptual overview of the underlying principles of DSC-MRI of the brain for clinical neuroradiologists, scientists, or students wishing to improve their understanding of the technical aspects, pitfalls, and controversies of DSC perfusion MRI of the brain. Future consensus on image acquisition parameters and postprocessing of DSC-MRI will most likely allow this technique to be evaluated and used in high-quality multicenter studies and ultimately help guide clinical care.

Posterior structural brain volumes differ in maltreated youth with and without chronic posttraumatic stress disorder.

Magnetic resonance imaging studies of maltreated children with posttraumatic stress disorder (PTSD) suggest that maltreatment-related PTSD is associated with adverse brain development. Maltreated youth resilient to chronic PTSD were not previously investigated and may elucidate neuromechanisms of the stress diathesis that leads to resilience to chronic PTSD. In this cross-sectional study, anatomical volumetric and corpus callosum diffusion tensor imaging measures were examined using magnetic resonance imaging in maltreated youth with chronic PTSD (N = 38), without PTSD (N = 35), and nonmaltreated participants (n = 59). Groups were sociodemographically similar. Participants underwent assessments for strict inclusion/exclusion criteria and psychopathology. Maltreated youth with PTSD were psychobiologically different from maltreated youth without PTSD and nonmaltreated controls. Maltreated youth with PTSD had smaller posterior cerebral and cerebellar gray matter volumes than did maltreated youth without PTSD and nonmaltreated participants. Cerebral and cerebellar gray matter volumes inversely correlated with PTSD symptoms. Posterior corpus callosum microstructure in pediatric maltreatment-related PTSD differed compared to maltreated youth without PTSD and controls. The group differences remained significant when controlling for psychopathology, numbers of Axis I disorders, and trauma load. Alterations of these posterior brain structures may result from a shared trauma-related mechanism or an inherent vulnerability that mediates the pathway from chronic PTSD to comorbidity.

Spontaneous brain parenchymal hemorrhage: an approach to imaging for the emergency room radiologist.

Spontaneous intracranial hemorrhage is a neurological emergency commonly encountered by the emergency radiologist. This article reviews the approach to spontaneous brain parenchymal hemorrhage, including common causes and the role of various neuroimaging modalities in the diagnostic workup. We emphasize the need for a primary survey directed at conveying information needed for emergent clinical management of the patient and a secondary survey directed at identifying the etiology of the hemorrhage.

Segmentation of the canine corpus callosum using diffusion-tensor imaging tractography.

OBJECTIVE: We set out to determine functional white matter (WM) connections passing through the canine corpus callosum; these WM connections would be useful for subsequent studies of canine brains that serve as models for human WM pathway disease. Based on prior studies, we anticipated that the anterior corpus callosum would send projections to the anterior cerebral cortex whereas progressively posterior segments would send projections to more posterior cortex. MATERIALS AND METHODS: A postmortem canine brain was imaged using a 7-T MRI system producing 100-µm-isotropic-resolution diffusion-tensor imaging analyzed by tractography. Using regions of interest (ROIs) within cortical locations, which were confirmed by a Nissl stain that identified distinct cortical architecture, we successfully identified six important WM pathways. We also compared fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity, and axial diffusivity in tracts passing through the genu and splenium. RESULTS: Callosal fibers were organized on the basis of cortical destination (e.g., fibers from the genu project to the frontal cortex). Histologic results identified the motor cortex on the basis of cytoarchitectonic criteria that allowed placement of ROIs to discriminate between frontal and parietal lobes. We also identified cytoarchitecture typical of the orbital frontal, anterior frontal, and occipital regions and placed ROIs accordingly. FA, ADC, radial diffusivity, and axial diffusivity values were all higher in posterior corpus callosum fiber tracts. CONCLUSION: Using six cortical ROIs, we identified six major WM tracts that reflect major functional divisions of the cerebral hemispheres, and we derived quantitative values that can be used for study of canine models of human WM pathologic states.

Neurodevelopmental outcomes of umbilical cord blood transplantation in metachromatic leukodystrophy.

Metachromatic leukodystrophy (MLD) is an inherited demyelinating disease that causes progressive neurologic deterioration, leading to severe motor disability, developmental regression, seizures, blindness, deafness, and death. The disease presents as a late-infantile, juvenile, or adult form. Hematopoietic stem cell transplantation has been shown to slow disease progression. The purpose of this longitudinal study was to evaluate long-term treatment outcomes after unrelated donor umbilical cord blood (UCB) transplantation in pediatric patients according to disease burden and age at onset (ie, late-infantile versus juvenile). Engraftment, survival, treatment-related toxicity, graft-versus-host disease, neurophysiologic measures, and neurodevelopmental function were assessed. To evaluate whether signal intensity abnormalities on magnetic resonance imaging (ie, modified Loes scores) predict post-transplant cognitive and gross motor development, a general linear mixed model was fit to the data. Twenty-seven patients underwent transplantation after myeloablative chemotherapy; 24 patients engrafted after the initial transplantation. Seven patients died of infection, regimen-related toxicity, or disease progression. Twenty patients (6 with late-infantile onset and 14 with juvenile onset) were followed for a median of 5.1 years (range, 2.4 to 14.7). We found that patients with motor function symptoms at the time of transplant did not improve after transplantation. Brainstem auditory evoked responses, visual evoked potentials, electroencephalogram, and/or peripheral nerve conduction velocities stabilized or improved in juvenile patients but continued to worsen in most patients with the late-infantile presentation. Pretransplant modified Loes scores were highly correlated with developmental outcomes and predictive of cognitive and motor function. Children who were asymptomatic at the time of transplantation benefited most from the procedure. Children with juvenile onset and minimal symptoms showed stabilization or deterioration of motor skills but maintained cognitive skills. Overall, children with juvenile onset had better outcomes than those with late-infantile onset. As in other leukodystrophies, early intervention correlated with optimal outcomes. We conclude that UCB transplantation benefits children with presymptomatic late-infantile MLD or minimally symptomatic juvenile MLD.

Increasing rate of detection of wrong-patient radiographs: use of photographs obtained at time of radiography.

OBJECTIVE: The objective of our study was to evaluate whether facial and chest photographs obtained simultaneously with radiographs increase radiologists' detection rate of labeling errors. MATERIALS AND METHODS: We obtained simultaneous portable radiographs and photographs of 34 patients. We generated 88 pairs of chest radiographs (one recent radiograph, one prior radiograph) and compiled a set of 20 pairs for reader review. Two, three, or four mismatched pairs (i.e., pairs containing radiographs of different patients) were introduced into each list. Ten radiologist readers blinded to the presence of mismatches interpreted the 20 radiograph pairs. Readers then reviewed a second set of 20 pairs containing mismatches but photographs of the patients obtained at the time of imaging were attached to the radiographs. Readers were not instructed regarding the purpose of the photographs. The mismatch detection rate and time for interpretation was recorded for both sessions. The two-tailed Fisher exact test was used to evaluate differences in mismatch detection rates between sessions, with a p value of less than 0.05 being considered significant. RESULTS: The error detection rates without (3/24 = 12.5%) and with (16/25 = 64%) photographs significantly differed (p = 0.0003). The average interpretation times without and with photographs were 35.73 and 26.51 minutes, respectively (two-tailed Student t test, p = 0.1165). CONCLUSION: The use of photographs increased the detection of errors without a concomitant increase in film interpretation time, which may translate into improvements in patient safety without an increase in interpretation time.

Influence of analysis technique on measurement of diffusion tensor imaging parameters.

OBJECTIVE: We compared results from various methods of analysis of diffusion tensor imaging (DTI) data from a single dataset consisting of 10 healthy adolescents. SUBJECTS AND METHODS: All subjects were imaged on a single 3-T MRI system (single-shot echo-planar imaging pulse sequence; b value, 1000 s/mm(2)). We measured fractional anisotropy (FA), apparent diffusion coefficient (ADC), and axial and radial diffusivity values using 64-pixel rectangular regions of interest (ROIs) in the right side, midline, and left side of the central portion of the splenium of the corpus callosum for fixed (i.e., at same sites in all subjects) and targeted (i.e., at sites of highest FA values) locations. We compared results with those obtained using 64-pixel oval ROIs and 100-pixel rectangular ROIs in the same locations. Finally, we compared results from ROI-based methods and from tractography. All comparisons used the Wilcoxon signed rank test and the intraclass correlation of individual values. RESULTS: Compared to tractography, the average of mean ROI-based values was significantly higher for fixed (approximately 14%) and targeted (approximately 39%) FA values and was significantly lower for ADC (approximately 16%) and radial diffusivity (approximately 38%) values. For solely ROI-based comparisons, statistically significant differences were found in the following comparisons: 64- versus 100-pixel ROI, oval versus rectangular ROI, targeted FA left of midline versus mean targeted FA value, and targeted ROI right of midline versus mean targeted FA value. CONCLUSION: Markedly different values were obtained when using either ROI- or tractography-based techniques or ROI analysis techniques that differ only relatively slightly.

Perfusion MRI: the five most frequently asked technical questions.

OBJECTIVE: This and its companion article address the 10 most frequently asked questions that radiologists face when planning, performing, processing, and interpreting different MR perfusion studies in CNS imaging. CONCLUSION: Perfusion MRI is a promising tool in assessing stroke, brain tumors, and patients with neurodegenerative diseases. Most of the impediments that have limited the use of perfusion MRI can be overcome to allow integration of these methods into modern neuroimaging protocols.

Perfusion MRI: the five most frequently asked clinical questions.

OBJECTIVE: This article addresses questions that radiologists frequently ask when planning, performing, processing, and interpreting MRI perfusion studies in CNS imaging. CONCLUSION: Perfusion MRI is a promising tool in assessing stroke, brain tumors, and neurodegenerative diseases. Most of the impediments that have limited the use of per-fusion MRI can be overcome to allow integration of these methods into modern neuroimaging protocols.

Brain trauma, PET scans and forensic complexity.

Positron Emission Tomography (PET) is a medical imaging technique that can be used to show brain function. Courts have admitted PET scan evidence in cases involving brain damage, injury, toxic exposure, or illness ("brain trauma") and to support claims of diminished cognitive abilities and impulse control. Despite the limited data on the relationships between PET, brain trauma and behavior, many courts admit PET scan evidence without much critical analysis. This article examines the use of PET as proof of functional impairment and justification of abnormal behavior by explaining its diagnostic use and limitations, the limited support for claims of its relationship to behavior, and evidentiary considerations that should govern its admission into court as evidence. The authors urge courts to consider PET evidence, claims of experts, and the scope of the proposed testimony with greater deference to the clinical scope of PET, as outlined by the American College of Radiology's appropriateness criteria and the Working Group Report of the American Psychiatric Association.