Structural dissociation of attentional control and memory in adults with and without mild traumatic brain injury.

Memory and attentional control impairments are the two most common forms of dysfunction following mild traumatic brain injury (TBI) and lead to significant morbidity in patients, yet these functions are thought to be supported by different brain networks. This 3 T magnetic resonance diffusion tensor imaging (DTI) study investigates whether microstructural integrity of white matter, as measured by fractional anisotropy (FA) within a small set of individually localized regions of interest (ROIs), is associated with these cognitive domains in normal adults and adults with mild TBI. Results in a sample of 23 normal controls reveal a significant correlation between attentional control and FA within a ROI in the left hemisphere anterior corona radiata. Furthermore, the controls demonstrate a correlation between memory performance and FA in a ROI placed in the uncinate fasciculus. Next, to examine whether these relationships are found in the pathological ranges of attention, memory and microstructural white matter integrity associated with mild TBI, these analyses were applied to a group of 43 mild TBI patients. Results, which generally demonstrated a wider range of attention, memory and FA scores, replicated the correlation between attentional control and FA in left hemisphere anterior corona radiata, as well as the correlation between memory performance and FA in the uncinate fasciculus. These two sets of brain-behaviour relationships were highly specific, as shown by a lack of correlation between attention and uncinate fasciculus FA and the lack of correlation between memory performance and anterior corona radiata FA. Furthermore, a 'correlational double dissociation' was demonstrated to exist between two distinct frontal structures independently associated with attention and memory, respectively, via a series of multiple regression analyses in both normal controls and adults with mild TBI. The results of the multiple regression analyses provide direct evidence that tract-specific variation in microstructural white matter integrity among normal controls and among mild TBI patients can account for much of the variation in performance in specific cognitive domains. More generally, such findings suggest that diffusion anisotropy measurement can be used as a quantitative biomarker for neurocognitive function and dysfunction.

Increased sensitivity to traumatic axonal injury on postconcussion diffusion tensor imaging scans in National Football League players by using premorbid baseline scans.

OBJECTIVE: Statistical challenges exist when using diffusion tensor imaging (DTI) to assess traumatic axonal injury (TAI) in individual concussed athletes. The authors examined active professional American football players over a 6-year time period to study potential TAI after concussion and assess optimal methods to analyze DTI at the individual level. METHODS: Active American professional football players recruited prospectively were assessed with DTI, conventional MRI, and standard clinical workup. Subjects underwent an optional preseason baseline scan and were asked to undergo a scan within 5 days of concussion during gameplay. DTI from 25 age- and sex-matched controls were obtained. Both semiautomated region-of-interest analysis and fully automated tract-based spatial statistics (TBSS) were used to examine DTI at individual and group levels. Statistical differences were assessed comparing individual DTI data to baseline imaging versus a normative database. Group-level comparisons were also performed to determine if longer exposure to professional-level play or prior concussion cause white matter microstructural integrity changes. RESULTS: Forty-nine active professional football players were recruited into the study. Of the 49 players, 7 were assessed at baseline during the preseason and after acute concussion. An additional 18 players were assessed after acute concussion only. An additional 24 players had only preseason baseline assessments. The results suggest DTI is more sensitive to suspected TAI than conventional MRI, given that 4 players demonstrated decreased fractional anisotropy (FA) in multiple tracts despite normal conventional MRI. Furthermore, the data suggest individual assessment of DTI data using baseline premorbid imaging is more sensitive than typical methods of comparing data to a normative control group. Among all subjects with baseline data, 1 reduced FA tract (± 2.5 standard deviations) was found using the typical normative database reference versus 10 statistically significant (p < 0.05) reduced FA tracts when referencing internal control baseline data. All group-level comparisons were statistically insignificant (p > 0.05). CONCLUSIONS: Baseline premorbid DTI data for individual DTI analysis provides increased statistical sensitivity. Specificity using baseline imaging also increases because numerous potential etiologies for reduced FA may exist prior to a concussion. These data suggest that there is a high potential for false-positive and false-negative assessment of DTI data using typical methods of comparing an individual to normative groups given the variability of FA values in the normal population.

Reproducibility of postprocessing of quantitative CT perfusion maps.

OBJECTIVE: The purpose of this study was to assess interobserver and intraobserver variability in evaluation of the reproducibility of quantitative data obtained in semiautomated postprocessing of CT perfusion data sets by observers of different levels of skill and experience and in fully automated postprocessing. MATERIALS AND METHODS: Twenty CT perfusion data sets were postprocessed by a neuroradiologist using an automated postprocessing program and by five observers (neuroradiology attending, neurology attending, radiology resident, senior and junior CT technologists) who received a brief training session in use of software for semiautomated postprocessing. For assessment of intraobserver variability, each observer repeated postprocessing of 10 CT perfusion data sets. Standard regions of interest were placed on identical locations for each observer's cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) maps of three brain regions: an ischemia-infarct region, normal cortical gray matter, and white matter. RESULTS: The variability in mean quantitative values of CBF, CBV, and MTT was 2.5-9.5% among all observers. Greater variability (20.4%) was introduced with the automated program. High correlation was found among all possible pairings of observers (r = 0.87-0.99). Low correlation was observed between automated postprocessing and postprocessing by all observers. Intraobserver variability in quantitative CT perfusion data ranged from 0.29% to 10.8%. High intraobserver correlation (r = 0.91-0.99) was found for the observers. CONCLUSION: Quantitative CBF, CBV, and MTT data obtained from postprocessing of CT perfusion data sets are reproducible among observers with varying levels of skill and experience. Observer interaction with the software is an important component for correct identification of user-defined parameters. Establishing a uniform and standard postprocessing technique is essential for maintaining good reproducibility.

Diffusion changes in patients with systemic lupus erythematosus.

BACKGROUND AND PURPOSE: Systemic lupus erythematosus (SLE) is an autoimmune disease in which almost all the organs are involved. Neuropsychiatric SLE is of one of the major concerns in the clinical evaluation of this disease. Routine magnetic resonance imaging (MRI) findings are often nonspecific or negative. In this study, we explored the use of diffusion tensor imaging in assisting with the diagnosis of SLE. METHODS: Data from 34 SLE patients (age range, 18-73 years) and 29 age-matched volunteers (age range, 29-64 years) were analyzed. MRI was performed on a 1.5-T clinical MR scanner with a quadrature head coil. The average diffusion constant (D(av)) and diffusion anisotropy maps [fractional anisotropy (FA)] were determined on a pixel-by-pixel basis. Regional diffusion measurements were made by region of interest in the genu and splenium of the corpus callosum (CC), anterior and posterior limb of the internal capsule (IC) and frontal lobe and thalamus. The diffusion distribution was fitted to a triple-Gaussian model. The mean of the brain tissue distribution was determined as a mean diffusion constant for the whole brain (BD(av)). Student's t test was used to determine the diffusion difference between SLE patients and control subjects. The SLE patients were separated into two groups according to their MRI results. A P value lower than .05 was considered to be statistically significant. RESULTS: Twenty of the 34 SLE patients with abnormal MRI results showed findings dominated by nonspecific white matter disease. The BD(av) and D(av) values of the frontal lobe, splenium CC and anterior IC were significantly higher in all SLE patients as compared with the control subjects. The SLE patients with normal MRI results also showed higher BD(av) and D(av) values in the frontal lobe, splenium and anterior and posterior limbs of the IC as compared with the control subjects. There was no significant difference in the D(av) values of the thalamus between the SLE patients and the control subjects. The BD(av) value in the SLE patient group was robustly correlated with the D(av) values of the frontal lobe, splenium and thalamus. These correlations were found to be similarly significant for the SLE patients with normal MRI findings. The diffusion anisotropy measurements showed that splenium CC had the highest FA value in both the control subjects and SLE patients. Overall, SLE patients had lower FA values in the genu and splenium CC as compared with the control subjects. In the group of patients with normal MRI findings, the FA values of the genu and splenium CC as well as the anterior IC were also lower than those in the control subjects. Pearson's correlation statistics revealed robust correlations between the measurements of D(av) and FA values in the SLE patient group. CONCLUSION: Quantitative diffusion imaging and diffusion anisotropy showed early changes in the brains of the SLE patients. Increased BD(av) and D(av) values of the frontal lobe as well as decreased anisotropy in the genu CC and anterior IC may represent preclinical signs of central nervous system involvement of SLE even when the routine MRI findings are negative or nonspecific. Quantitative diffusion analysis may prove to be useful in detecting the initial brain involvement of SLE and may enable monitoring of early disease progression and treatment efficacy.

Chronic Post-Concussion Neurocognitive Deficits. I. Relationship with White Matter Integrity.

We previously identified visual tracking deficits and associated degradation of integrity in specific white matter tracts as characteristics of concussion. We re-explored these characteristics in adult patients with persistent post-concussive symptoms using independent new data acquired during 2009-2012. Thirty-two patients and 126 normal controls underwent cognitive assessments and MR-DTI. After data collection, a subset of control subjects was selected to be individually paired with patients based on gender and age. We identified patients' cognitive deficits through pairwise comparisons between patients and matched control subjects. Within the remaining 94 normal subjects, we identified white matter tracts whose integrity correlated with metrics that indicated performance degradation in patients. We then tested for reduced integrity in these white matter tracts in patients relative to matched controls. Most patients showed no abnormality in MR images unlike the previous study. Patients' visual tracking was generally normal. Patients' response times in an attention task were slowed, but could not be explained as reduced integrity of white matter tracts relating to normal response timing. In the present patient cohort, we did not observe behavioral or anatomical deficits that we previously identified as characteristic of concussion. The recent cohort likely represented those with milder injury compared to the earlier cohort. The discrepancy may be explained by a change in the patient recruitment pool circa 2007 associated with an increase in public awareness of concussion.

Entrustable Professional Activities: Ten Things Radiologists Do.

RATIONALE AND OBJECTIVES: Learner assessment in medical education has undergone tremendous change over the past two decades. During this time frame, the concept of Entrustable Professional Activities (EPAs) was introduced to guide the faculty when making competency-based decisions on the level of supervision required by trainees. EPAs are gaining momentum in medical education as a basis for decisions related to transitioning from residency training to clinical practice. The purpose of this article is twofold: (1) define EPAs for radiology (EPA-R) and (2) illustrate radiology-specific examples of these EPAs. MATERIALS AND METHODS: A multi-institutional work group composed of members of the Alliance of Directors and Vice Chairs of Education in Radiology convened at the 2015 Association of University Radiologists annual meeting to discuss radiology EPAs. The EPAs initially developed by the Accreditation Council for Graduate Medical Education (ACGME) Radiology milestone work group and the resultant ACGME Radiology milestones formed the basis for this discussion. RESULTS: A total of 10 radiology EPAs and illustrative vignettes were developed to help radiology educators and trainees better understand milestone assessment and how this translates to the necessary skills and responsibilities of practicing radiologists. Examples of EPA mapping to the ACGME subcompetencies and methods of assessment were included. CONCLUSIONS: EPAs offer an opportunity to improve our approach to training by increasing our focus on how we provide appropriate supervision to our residents and assess their progress. In this work, through suggested lists and vignettes, we have attempted to establish the framework for further discussion and development of EPA-Rs.

Developmental delay in children: assessment with proton MR spectroscopy.

BACKGROUND AND PURPOSE: The cause of developmental delay frequently is unknown, and clinicians and families can be frustrated by the lack of neuroimaging correlation especially when considering therapeutic options and long-term prognosis. We sought to determine if proton MR spectroscopy can depict abnormalities in patients with developmental delay who have structurally normal brain MR images. METHODS: Children with developmental delay who were older than 2 years (mean age, 5.0 years; range, 3.0-10.0 years) and those aged 2 years or younger (mean age, 1.5 years; range, 0.5-2.0 years) and age-matched control subjects for each patient group underwent brain MR imaging and proton MR spectroscopy. A point-resolved spectroscopy sequence (2000/144 [TR/TE]) was used. Voxels (8 cm(3)) were placed in the subcortical white matter of the frontal and parieto-occipital lobes bilaterally. N-acetylaspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were assessed. RESULTS: All patients had normal brain MR images. In children with developmental delay who were aged 2 years or younger, no statistically significant differences were detected in the NAA/Cr or Cho/Cr ratios compared with those of the control subjects. In children with developmental delay who were older than 2 years, decreases in the NAA/Cr ratio were observed in frontal (P <.001) and parieto-occipital (P <.017) subcortical white matter, and elevations in the Cho/Cr ratio were detected in the frontal (P <.24) and parieto-occipital (P <.002) subcortical white matter compared with age-matched control subjects. CONCLUSIONS: In children with developmental delay who are older than 2 years, proton MR spectroscopy depicted abnormalities in the NAA/Cr and Cho/Cr ratios. Proton MR spectroscopy should be performed as part of the neuroimaging evaluation of developmental delay. Further studies will be needed to determine if abnormalities detected with proton MR spectroscopy can be used as a diagnostic tool and neuroimaging marker to assess long-term functional outcome.

Diffusion imaging in obstructive hydrocephalus.

BACKGROUND AND PURPOSE: Hydrocephalus causes transependymal resorption of spinal fluid that in turn produces periventricular interstitial edema. This study was performed to determine if diffusion imaging can demonstrate this interstitial edema in the periventricular region in patients with obstructive hydrocephalus and if it can be used to assess the treatment response. METHODS: Twenty-one patients with obstructive hydrocephalus were evaluated with MR diffusion imaging before and after treatment. The change in ventricular size was measured by using the frontal and occipital horn ratio. The signal intensity abnormalities in periventricular white matter were scored. Average diffusion constants (D(av)) in the periventricular white matter were measured before and after treatment and compared with normal values. Post-treatment resolution of MR imaging abnormalities and changes in ventricular volume were compared with changes in D(av). RESULTS: D(av) measured from periventricular white matter was increased in hydrocephalic patients compared with age-matched control subjects by a mean of 6.9% (P <.02). After treatment, D(av) decreased by an average of 6.0%: D(av) decreased in 11 patients (53%), it remained essentially unchanged in seven (33%), and it increased in three (14%). CONCLUSION: For patients with obstructive hydrocephalus, diffusion is usually increased in the periventricular white matter. Therefore, increased D(av) may be a clinically useful sign of hydrocephalus, and it may prove useful in cases with equivocal clinical or imaging findings. Measurement of D(av) may be valuable in assessing the treatment response in these patients because D(av) usually decreases toward normal levels with successful treatment.

Temporal evolution of diffusion after spontaneous supratentorial intracranial hemorrhage.

BACKGROUND AND PURPOSE: The evolution of apparent diffusion coefficient abnormalities during supratentorial intracranial hemorrhage in normal appearing brain tissue has not been described. Recent investigations using diffusion imaging have revealed increased apparent diffusion coefficient in perihematomal tissue. We report brain tissue abnormalities beyond the visibly abnormal region ipsilateral and contralateral to the hematoma. This preliminary effort should generate meaningful clinical prognostic indicators for moderate size hemorrhages in large scale studies. METHODS: Using the neurology patient encounter database at a tertiary care hospital, we retrospectively identified patients who presented with acute focal neurologic deficits, had CT scans of the head that confirmed spontaneous intracranial hemorrhage, and had a MR images obtained within the first 6 hr to 30 days postictus. The regions identified as targets of this investigation were the hemorrhage and surrounding T2 signal intensity abnormality and the visibly normal supratentorial cerebral tissue. RESULTS: Ninety-five patients were admitted during a period of 25 months. Fifteen patients met the criteria for the study. Elevated whole brain diffusion was shown as early as 6 hr after intracranial hemorrhage. This increase in diffusion was comparable in both hemispheres. Diffusion values in the lesion (hematoma plus T2 signal intensity abnormality) increased slowly with peak increases noted 2 to 3 days after the ictus. CONCLUSION: Diffuse early cerebral response occurs in normal appearing brain tissue both ipsilateral and contralateral to the visibly abnormal hematoma, manifested by increased apparent diffusion coefficient. This response is present before the local response is fully developed. Supratentorial intracranial hemorrhage results in an early diffuse brain response with increased apparent diffusion coefficient in normal appearing brain.

Increased diffusion in the brain of professional boxers: a preclinical sign of traumatic brain injury?

BACKGROUND AND PURPOSE: Professional boxing is associated with chronic, repetitive head blows that may cause brain injuries. Diffusion-weighted imaging is sensitive to microscopic changes and may be a useful tool to quantify the microstructural integrity of the brain. In this study, we sought to quantify microscopic alterations associated with chronic traumatic brain injury in professional boxers. METHODS: MR and diffusion-weighted imaging were performed in 24 boxers and in 14 age- and sex-matched control subjects with no history of head trauma. Using distribution analysis, the average diffusion constant of the entire brain (BD(av)) and diffusion distribution width (sigma) were calculated for each subject; findings in professional boxers were compared with those of control subjects. In the boxer group, correlations between diffusion changes and boxing history and diffusion changes and MR imaging findings were assessed. RESULTS: The measured diffusion values in the boxer group were significantly higher than those measured in the control group (BD(av), P <.0001; sigma, P <.01). In the boxer group, a robust correlation was found between increased BD(av) and frequency of hospitalization for boxing injuries (r = 0.654, P <.05). The most common MR finding in the boxer group was volume loss inappropriate to age followed by cavum septum pellucidum, subcortical white matter disease, and periventricular white matter disease. CONCLUSION: Boxers had higher diffusion constants than those in control subjects. Our data suggest that microstructural damage of the brain associated with chronic traumatic brain injury may elevate whole-brain diffusion. This global elevation can exist even when routine MR findings are normal.

Sellar collision tumor involving metastatic lung cancer and pituitary adenoma: radiologic-pathologic correlation and review of the literature.

Collision tumors of the sella turcica involving metastases to pituitary adenomas are rare. We report a case of a collision tumor involving metastatic lung cancer with an emphasis on the neuroimaging and histopathological studies. A review of the literature including the diagnostic and management implications as well as pathogenetic mechanisms is also discussed.

Safety and maximum tolerated dose of superselective intraarterial cerebral infusion of bevacizumab after osmotic blood-brain barrier disruption for recurrent malignant glioma. Clinical article.

OBJECT: The authors assessed the safety and maximum tolerated dose of superselective intraarterial cerebral infusion (SIACI) of bevacizumab after osmotic disruption of the blood-brain barrier (BBB) with mannitol in patients with recurrent malignant glioma. METHODS: A total of 30 patients with recurrent malignant glioma were included in the current study. RESULTS: The authors report no dose-limiting toxicity from a single dose of SIACI of bevacizumab up to 15 mg/kg after osmotic BBB disruption with mannitol. Two groups of patients were studied; those without prior bevacizumab exposure (naïve patients; Group I) and those who had received previous intravenous bevacizumab (exposed patients; Group II). Radiographic changes demonstrated on MR imaging were assessed at 1 month postprocedure. In Group I patients, MR imaging at 1 month showed a median reduction in the area of tumor enhancement of 34.7%, a median reduction in the volume of tumor enhancement of 46.9%, a median MR perfusion (MRP) reduction of 32.14%, and a T2-weighted/FLAIR signal decrease in 9 (47.4%) of 19 patients. In Group II patients, MR imaging at 1 month showed a median reduction in the area of tumor enhancement of 15.2%, a median volume reduction of 8.3%, a median MRP reduction of 25.5%, and a T2-weighted FLAIR decrease in 0 (0%) of 11 patients. CONCLUSIONS: The authors conclude that SIACI of mannitol followed by bevacizumab (up to 15 mg/kg) for recurrent malignant glioma is safe and well tolerated. Magnetic resonance imaging shows that SIACI treatment with bevacizumab can lead to reduction in tumor area, volume, perfusion, and T2-weighted/FLAIR signal.

Spontaneous intracranial hypotension followed by dural sinus thrombosis: a case report.

SIH is an underdiagnosed condition with variable clinical and radiological presentations that leads to engorged dural sinuses and promotes stasis predisposing for dural sinus thrombosis (DST). We describe a young female patient who presented with clinical and imaging signs of SIH alone followed by a superimposed DST 10 days later. We discuss the pathophysiological mechanisms that may have led to this constellation, and review the literature to-date along with diagnostic and management implications.

ACR Appropriateness Criteria on low back pain.

Acute low back pain with or without radiculopathy is one of the most common health problems in the United States, with high annual costs of evaluation and treatment, not including lost productivity. Multiple reports show that uncomplicated acute low back pain or radiculopathy is a benign, self-limited condition that does not warrant any imaging studies. Guidelines for recognition of patients with more complicated status can be used to identify those who require further evaluation for suspicion of more serious problems and contribute to appropriate imaging utilization.

Distribution of microstructural damage in the brains of professional boxers: a diffusion MRI study.

PURPOSE: To investigate and localize cerebral abnormalities in professional boxers with no history of moderate or severe head trauma. MATERIALS AND METHODS: Diffusion tensor imaging (DTI) was used to determine the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in the brains of 81 professional male boxers and 12 male control subjects. Voxel-based analysis (VBA) of both the diffusion and anisotropy values was performed using statistical parametric mapping (SPM). From this objective analysis, regions of microstructural abnormalities in the brains of the boxers were located. RESULTS: Increases in the ADC, and decreases in FA were identified in deep white matter (WM), while decreases in ADC were identified in cortical gray matter (GM). Regions of positive correlation between ADC and age were also found in both the boxer and control groups, although the regions and strength of the correlation were not the same in each group. CONCLUSION: Using VBA, we localized previously unreported abnormalities in the brains of professional boxers. These abnormalities are assumed to reflect cumulative (chronic) brain injury resulting from nonsevere head trauma.

The diagnostic utility of FLAIR imaging in clinically verified amyotrophic lateral sclerosis.

PURPOSE: To explore the overall diagnostic ability of magnetic resonance (MR) fluid-attenuated inversion recovery (FLAIR) imaging for clinically verified amyotrophic lateral sclerosis (ALS). MATERIALS AND METHODS: Abnormal signal intensity in FLAIR images of 18 patients with ALS and 18 age-matched normal controls were scored and compared. Six patients had serial MR imaging scans within 97 days. Mann Whitney U statistics and ANOVA were used for statistical analysis. RESULTS: Hyperintensity in the subcortical white matter (SWM) and the dark line along the posterior rim of the precentral gyri were found more frequently in patients with ALS. The scores for these two signs were significantly different from those of normal controls. Hyperintensity in the corticospinal tract (CST) was found in both ALS and normal controls, but the difference was not statistically significant. ANOVA on the serial FLAIR studies revealed no significant difference in the scores among the series. The hyperintensity in SWM had a sensitivity of 56% and specificity of 94%, while the dark line in the motor cortex had a 74% sensitivity and 67% specificity. CONCLUSION: Hyperintensity in SWM and the dark line along the posterior rim of the precentral gyri appeared more frequently in the patients with ALS. SWM hyperintensity has a better specificity in association with clinically verified ALS, while the motor dark line has a better sensitivity. No correlation was found between the FLAIR findings and progression of the disease.

Atherosclerotic disease distribution in carotid and vertebrobasilar arteries: clinical experience in 100 patients undergoing fluoro-triggered 3D Gd-MRA.

PURPOSE: To determine how often three-dimensional gadolinium-enhanced magnetic resonance angiography (3D Gd-MRA) shows disease outside of the standard two-dimensional time-of-flight magnetic resonance angiography (2D TOF-MRA) imaging volume. MATERIALS AND METHODS: One hundred consecutive patients with known or suspected cerebrovascular disease were examined using fluoro-triggered 3D Gd-MRA with a 1.5 Tesla scanner. All vessel segments from the aortic arch to the circle of Willis were independently evaluated for the presence of occlusive disease, ulceration, aneurysm, and anatomic variations by two radiologists blinded to clinical information. Branch vessel and circle of Willis visibility were also assessed. Kappa statistics were calculated to determine interobserver agreement. RESULTS: Interobserver agreement for the degree of stenosis was good to excellent (kappa = 0.83-1.0). Disagreement was more frequent in the cases of mild stenoses and was less frequent for stenoses > or = 50%. In 38% of the patients, 3D Gd-MRA demonstrated either ulcerated plaques in carotid arteries (N = 14) or stenosis > or = 50% in great vessel (N = 20) and/or vertebral artery (N = 38) origins, none of which can be readily evaluated on standard TOF-MRA. CONCLUSION: Fluoro-triggered 3D Gd-MRA provides a comprehensive evaluation of the carotid arteries including all vessel segments from the aortic arch to the circle of Willis.