Increased pituitary volumes in patients with Sanfilippo syndrome (mucopolysaccharidosis type 3, MPS III).

PURPOSE: To evaluate apparent pituitary gland enlargement in patients with Sanfilippo syndrome observed at our institution. METHODS: Twelve patients with Sanfilippo syndrome with brain MRI were studied. Anterior, posterior, and whole pituitary volumes were estimated using the prolate ellipsoid volume calculation method (π/6 × L × W × H). Convexity along the upper pituitary margin (Elster's grade) was also measured. These values were compared to two age- and sex-matched groups (normal controls and patients with Hurler syndrome) using one-way ANOVA followed by Tukey's post hoc analysis for multiple comparisons. RESULTS: In the Sanfilippo cohort, the mean whole pituitary volume was 529.9 mm, the mean anterior pituitary volume was 333.4 mm, and the mean posterior pituitary volume was 59.1 mm with Elster's grade of 4.2. In the control cohort, the mean whole pituitary volume was 217.4 mm, the mean anterior pituitary volume was 154.8 mm, and the mean posterior pituitary volume was 28.4 mm with Elster's grade of 2.5. In the Hurler syndrome cohort, the mean whole pituitary volume was 310.0 mm, the mean anterior pituitary volume was 178.2 mm, and the mean posterior pituitary volume was 35.4 mm with Elster's grade of 3.5. CONCLUSION: In our cohort of patients with Sanfilippo syndrome, whole, anterior, and posterior pituitary volumes and degree of convexity along the upper pituitary border were all significantly greater than controls. The cause of these morphological changes is unclear, as is clinical correlation of the findings.

ACR guidance document on MR safe practices: Updates and critical information 2019.

The need for a guidance document on MR safe practices arose from a growing awareness of the MR environment's potential risks and adverse event reports involving patients, equipment, and personnel. Initially published in 2002, the American College of Radiology White Paper on MR Safety established de facto industry standards for safe and responsible practices in clinical and research MR environments. The most recent version addresses new sources of risk of adverse events, increases awareness of dynamic MR environments, and recommends that those responsible for MR medical director safety undergo annual MR safety training. With regular updates to these guidelines, the latest MR safety concerns can be accounted for to ensure a safer MR environment where dangers are minimized. Level of Evidence: 1 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:331-338.

Imaging Patterns of Toxic and Metabolic Brain Disorders.

Toxic and metabolic brain disorders are relatively uncommon diseases that affect the central nervous system, but they are important to recognize as they can lead to catastrophic outcomes if not rapidly and properly managed. Imaging plays a key role in determining the most probable diagnosis, pointing to the next steps of investigation, and providing prognostic information. The majority of cases demonstrate bilateral and symmetric involvement of structures at imaging, affecting the deep gray nuclei, cortical gray matter, and/or periventricular white matter, and some cases show specific imaging manifestations. When an appropriate clinical situation suggests exogenous or endogenous toxic effects, the associated imaging pattern usually indicates a restricted group of diagnostic possibilities. Nonetheless, toxic and metabolic brain disorders in the literature are usually approached in the literature by starting with common causal agents and then reaching imaging abnormalities, frequently mixing many different possible manifestations. Conversely, this article proposes a systematic approach to address this group of diseases based on the most important imaging patterns encountered in clinical practice. Each pattern is suggestive of a most likely differential diagnosis, which more closely resembles real-world scenarios faced by radiologists. Basic pathophysiologic concepts regarding cerebral edemas and their relation to imaging are introduced-an important topic for overall understanding. The most important imaging patterns are presented, and the main differential diagnosis for each pattern is discussed. Online supplemental material is available for this article. ©RSNA, 2019.

Controversy of posterior reversible encephalopathy syndrome: what have we learnt in the last 20 years?

Over two decades have passed since posterior reversible encephalopathy syndrome (PRES) was first described in 1996. It has becoming increasingly recognised because of improved and more readily available imaging modality. The exact pathophysiological mechanism is not completely understood and remains controversial at present. Precise diagnosis is essential to guide prompt, proper management. Our ability of differentiating it from other acute neurological disorders is likely to improve as we learnt more about the spectrum of this entity in the last 20 years. We emphasise the importance of recognising its diagnostic criteria and biomarker, which would be of great relevance to either outcome evaluation or study design. PRES has a favourable prognosis generally, but neurological sequelae and even fatalities can occur, especially in severe forms that might cause substantial morbidity and even mortality, particularly when the syndrome is complicated by intracranial haemorrhage or brain infarction. In this review, the pathophysiology, approach to diagnosis, some controversies as to the prognosis, as well as the future research direction of PRES are described.

Multivariate Prognostic Model of Acute Stroke Combining Admission Infarct Location and Symptom Severity: A Proof-of-Concept Study.

BACKGROUND: The information on topographic distribution of acute ischemic infarct can contribute to prediction of functional outcome. We aimed to develop a multivariate model for stroke prognostication, combining admission clinical and imaging variables, including the infarct topology. METHODS: Acute ischemic stroke patients without baseline functional disability who had magnetic resonance imaging within 24 hours of onset or last-seen-well were included. The admission stroke severity was determined using the National Institutes of Health Stroke Scale (NIHSS) score. The relation between infarct location and outcome was assessed using both voxel-based and visual atlas-based analyses. The disability/death was defined by a modified Rankin Scale score greater than 2 at 3-month follow-up. RESULTS: Among 198 patients included in this study, higher admission NIHSS score (P < .001), larger infarct volume (P < .001), and major arterial occlusions (P < .001) were associated with disability/death in univariate analyses. On voxel-based analysis, infarcts in the middle centrum semiovale, insula, and midbrain/pons were associated with higher rates of disability/death. In multivariate analysis, admission NIHSS score (P < .001), infarction of insula (P = .005), and midbrain/pons (P = .006) were independent predictors of disability/death. In receiver operating characteristics analysis, a simple 0-to-3 scoring system using these 3 variables had an area under the curve of .812 for prediction of disability/death (P < .001). CONCLUSIONS: Admission symptom severity, infarction of insula, and midbrain/pons were independent predictors of clinical outcome in acute ischemic stroke patients. The methodology of this hypothesis-generating study can help conceive quantitative population-based probabilistic models for prognostication or treatment triage in stroke patients, combining admission clinical and imaging findings-including infarct topography.

Potentially reversible acute cerebellar toxicity associated with Minnelide.

PURPOSE: Minnelide is an experimental antineoplastic agent that is currently the subject of a phase 1 clinical trial for the treatment of pancreatic and gastrointestinal malignancies. In this study, we documented two cases of reversible acute cerebellar toxicity (REACT) associated with Minnelide and compared its radiological manifestations with other cerebellotoxic agents. METHODS: Both patients had histories of progressive metastatic cancer and participated in a phase 1 clinical trial with Minnelide. They had an MRI examination including T2WI, FLAIR and SWI, axial and coronal DWI, and ADC map on admission and follow up. RESULTS: In each patient, the initial MRI demonstrated increased signal on FLAIR and restricted diffusion in the cerebellar cortex without involvement of deep cerebellar nuclei or supratentorial areas. The presenting symptoms and the majority of imaging findings resolved on follow up MRI. CONCLUSION: To our knowledge, Minnelide has shown an uncommon radiologic pattern of isolated cerebellar cortical involvement compared to other causes of cerebellar toxicity. Since this is a new medication, physicians' familiarity with the presenting symptoms and its temporal association with the imaging findings is important.

Susceptibility-diffusion mismatch in middle cerebral artery territory acute ischemic stroke: clinical and imaging implications.

Background Recent studies have suggested a correlation between susceptibility-diffusion mismatch and perfusion-diffusion mismatch in acute ischemic stroke patients. Purpose To determine the clinical and imaging associations of susceptibility-diffusion mismatch in patients with acute ischemic stroke in the middle cerebral artery (MCA) territory. Material and Methods Consecutive patients with MCA territory acute ischemic stroke, who had magnetic resonance imaging (MRI) performed with susceptibility-weighted imaging (SWI) and diffusion-weighted imaging (DWI) within 24 h of symptom onset or time last-seen-well, were included. Two neuroradiologists reviewed SWI scans for SWI-DWI mismatch defined by regionally increased vessel number or diameter on SWI extending beyond the DWI hyperintensity territory in the affected hemisphere. The stroke severity at admission was evaluated using the National Institutes of Health Stroke Scale (NIHSS) score. Poor clinical outcome was defined by a 3-month modified Rankin Scale (mRS) score >2. Results The SWI-DWI mismatch was identified in 44 (29.3%) of 150 patients included in this study. Patients with SWI-DWI mismatch had smaller admission infarct volumes (31.2 ± 44.7 versus 55.9 ± 117.7 mL, P = 0.045) and were younger (60.4 ± 18.9 versus 67.1 ± 15.5, P = 0.026). After correction for age, admission NIHSS score, and infarct volume, the SWI-DWI mismatch was associated with a 22.6% lower rate of poor clinical outcome using propensity score matching ( P = 0.032). In our cohort, thrombolytic therapy showed no significant effect on outcome. Conclusion The presence of SWI-DWI mismatch in acute MCA territory ischemic infarct is associated with smaller infarct volume. Moreover, SWI-DWI mismatch was associated with better outcome after correction for infarct size, severity of admission symptoms, and age.

MDCT Venographic Patterns of Dural Venous Sinus Compromise After Acute Skull Fracture.

OBJECTIVE: Prior studies have shown that skull fractures overlying the dural venous sinuses predispose the patient to an increased risk of dural venous sinus thrombosis (DVST). However, extrinsic compression may also cause sinus compromise and simulate thrombosis. This study set out to evaluate the prevalence and discernibility of DVST versus direct sinus compression in the setting of an overlying skull fracture. MATERIALS AND METHODS: All initial head MDCT venography examinations performed at a level 1 trauma center over an 8-year period were reviewed (n = 347 patients). The examinations that showed an acute fracture overlying a dural sinus were included for review (n = 107 patients). Three neuroradiologists classified the MDCT venography findings as category 0 (normal), 1 (solely sinus compression), 2 (solely intraluminal thrombus), 3 (mixed sinus compression and DVST), or 4 (indeterminate). Clinical outcomes were assessed at 30-45 days after hospital discharge. RESULTS: The percentage of patients in each category was as follows: category 0 (31-33% patients), 1 (38-46%), 2 (5-9%), 3 (8-11%), and 4 (8-13%). Categories 2-4 were more likely in the transverse sinus-sigmoid sinus complex (22-30%) and multiple dural sinuses (47-53%) than in the superior sagittal sinus (SSS) (5%). Interobserver reliability was strong (κ = 0.627-0.772; p < 0.0001). Sinus category was associated with fracture site (p = 0.014) but not with clinical outcome (p = 0.236). CONCLUSION: Sinus compromise is common in patients with overlying skull fractures. Sinus compression can be distinguished from DVST on MDCT venography and is likely more prevalent than previously estimated. The fracture site may in part determine the pattern of compromise because fractures involving the transverse sinus-sigmoid sinus complex or multiple dural sinuses seem more likely to be affected by thrombosis than fractures involving the SSS.

Interhemispheric Asymmetry in Distribution of Infarct Lesions among Acute Ischemic Stroke Patients Presenting to Hospital.

BACKGROUNDS: This study aimed to investigate the possible asymmetric distribution of acute ischemic infarct lesions between patients with right-sided stroke versus left-sided stroke. METHODS: Acute ischemic stroke patients with unilateral infarct who underwent magnetic resonance imaging scan within 24 hours of onset were included. Infarct lesions were segmented on diffusion-weighted-imaging series and coregistered on the MNI-152 brain map. After flipping all lesions to the left side, voxel-based analysis was performed to evaluate for asymmetric distribution of infarct lesions using the stroke side as an independent variable. Symptom severity at admission was evaluated using the National Institutes of Health Stroke Scale score, and early clinical outcome with the modified Rankin Scale score at discharge. RESULTS: Of the 218 patients included in this study, 110 had right-sided ischemic infarcts whereas 108 had left-sided ischemic infarcts. There was no significant difference between patients with right-sided stroke versus left-sided stroke in terms of admission symptom severity, rate of treatment, stroke risk factors, and early clinical outcome. However, voxel-based analysis showed that ischemic infarcts of insular ribbon and lentiform nucleus were asymmetrically more common on the left-sided stroke compared to the right-sided stroke. The admission symptoms were more severe among patients with left insular ribbon and lentiform nucleus infarct compared to those with infarction of mirrored right anatomical regions (P = .019). CONCLUSIONS: Acute ischemic infarcts of the left insular ribbon and lentiform nucleus are asymmetrically more common compared to mirrored counterpart regions, presumably due to more severe symptoms at presentation. Otherwise, distribution of symptomatic infarcts to the rest of the brain is roughly symmetric.

Seizure outcomes of posterior reversible encephalopathy syndrome and correlations with electroencephalographic changes.

RATIONALE: Seizures are among the most common clinical presentations of posterior reversible encephalopathy syndrome (PRES). This syndrome has rarely been reported to cause chronic epilepsy or persistent cortical dysfunction. The prognostic value of EEG findings during PRES is unknown. We retrospectively evaluated EEG characteristics in patients with PRES in a single medical center. We also evaluated the long-term outcome regarding seizure occurrence beyond the acute phase in these patients. METHODS: We searched a radiology database at the University of Minnesota from 1997 to 2012 to identify patients with clinically and radiologically diagnosed PRES. Among the patients with PRES, we reviewed MRI images, EEG findings, clinical manifestations including seizure occurrences, and clinical outcomes beyond the acute phase. RESULTS: Seventy-five patients were included in the study. Fifty-eight out of seventy-five (77.3%) patients with PRES had seizures. A total of 48 EEG studies were performed in 38 patients. Generalized slowing was the most common EEG pattern. Among the 38 patients who had EEGs, 37 (97.3%) patients had diffuse or focal slowing of the background, and 11 (28.9%) patients had IEDs. Four out of seventy-five (5.3%) patients had seizures later than one month beyond their hospitalization for PRES. None of these 4 patients had seizures before the episode of PRES. Two patients developed chronic epilepsy, with seizures occurring later than one year after the PRES. CONCLUSION: Most patients who had seizures or who had epileptiform activities in EEG during PRES did not subsequently develop chronic epilepsy. No patient developed chronic epilepsy in the absence of clinical seizures during PRES. Posterior reversible encephalopathy syndrome may infrequently be associated with subsequent development of symptomatic epilepsy.

Susceptibility-weighted imaging in stroke-like migraine attacks after radiation therapy syndrome.

INTRODUCTION: Stroke-like migraine attacks after radiation therapy (SMART) syndrome has a characteristic clinical presentation and postcontrast T1WI MRI appearance. Susceptibility-weighted imaging (SWI) may help distinguish SMART from other disorders that may have a similar postcontrast MRI appearance. METHODS: The MRI examinations of four patients with SMART syndrome are described herein, each of which included SWI, FLAIR, DWI, and postcontrast T1WI on the presenting and follow-up MRI examinations. RESULTS: In each, the initial SWI MRI demonstrated numerous susceptibility hypointensities <5 mm in size throughout the cerebrum, particularly within the periventricular white matter (PVWM), presumably related to radiation-induced cavernous hemangiomas (RICHs). By follow-up MRI, each postcontrast examination had demonstrated resolution of the gyriform enhancement on T1WI, without susceptibility hypointensities on SWI within those previously enhancing regions. CONCLUSION: These preliminary findings suggest that SWI may help identify SMART syndrome or at least help discriminate it from other disorders, by the findings of numerous susceptibility hypointensities on SWI likely representing RICHs, gyriform enhancement on T1WI, and postsurgical findings or appropriate clinical history.

Effect of patient positioning on cerebrospinal fluid opening pressure.

BACKGROUND: Prone is the preferred patient position for fluoroscopic-guided lumbar puncture (LP). Normative data for cerebrospinal fluid (CSF) opening pressure (OP) exist for lateral decubitus (LD) positioning only and have not been defined for the prone position. This study compares CSF OP values in the prone and LD positions and examines the effect of body mass index (BMI) on OP. METHODS: Patients undergoing diagnostic or therapeutic fluoroscopic-guided LP were recruited prospectively at 2 tertiary care centers from 2009 to 2012. Following prone fluoroscopic-guided LP, patients were rolled to the LD position for repeat CSF OP measurement. In addition to comparing the mean OP in each position, the relationships between OP, body position, and BMI were also explored. RESULTS: Fifty-two patients were enrolled. A mean OP difference of 1.2 cm H2O was observed (prone: 26.5 cm H2O; LD: 27.7 cm H2O; P = 0.07). No correlation between CSF OP and BMI was seen in either position. CONCLUSIONS: No statistically or clinically significant difference between prone and LD OP was identified. BMI does not appear to affect CSF OP measurement in either position.

Automated vs. manual coding of neuroimaging reports via natural language processing, using the international classification of diseases, tenth revision.

Objective: Natural language processing (NLP) can generate diagnoses codes from imaging reports. Meanwhile, the International Classification of Diseases (ICD-10) codes are the United States' standard for billing/coding, which enable tracking disease burden and outcomes. This cross-sectional study aimed to test feasibility of an NLP algorithm's performance and comparison to radiologists' and physicians' manual coding. Methods: Three neuroradiologists and one non-radiologist physician reviewers manually coded a randomly-selected pool of 200 craniospinal CT and MRI reports from a pool of >10,000. The NLP algorithm (Radnosis, VEEV, Inc., Minneapolis, MN) subdivided each report's Impression into "phrases", with multiple ICD-10 matches for each phrase. Only viewing the Impression, the physician reviewers selected the single best ICD-10 code for each phrase. Codes selected by the physicians and algorithm were compared for agreement. Results: The algorithm extracted the reports' Impressions into 645 phrases, each having ranked ICD-10 matches. Regarding the reviewers' selected codes, pairwise agreement was unreliable (Krippendorff α = 0.39-0.63). Using unanimous reviewer agreement as "ground truth", the algorithm's sensitivity/specificity/F2 for top 5 codes was 0.88/0.80/0.83, and for the single best code was 0.67/0.82/0.67. The engine tabulated "pertinent negatives" as negative codes for stated findings (e.g. "no intracranial hemorrhage"). The engine's matching was more specific for shorter than full-length ICD-10 codes (p = 0.00582x10-3). Conclusions: Manual coding by physician reviewers has significant variability and is time-consuming, while the NLP algorithm's top 5 diagnosis codes are relatively accurate. This preliminary work demonstrates the feasibility and potential for generating codes with reliability and consistency. Future works may include correlating diagnosis codes with clinical encounter codes to evaluate imaging's impact on, and relevance to care.

Central-variant posterior reversible encephalopathy syndrome: brainstem or basal ganglia involvement lacking cortical or subcortical cerebral edema.

OBJECTIVE: Although posterior reversible encephalopathy syndrome (PRES) typically involves cortical or subcortical edema of the cerebrum, only individual cases have been described of a variant involving the central brainstem and basal ganglia and lacking cortical and subcortical edema. We evaluated FLAIR and T2-weighted images of 124 patients with confirmed PRES to determine the incidence of this uncommon variant, which we refer to as the "central variant"; to determine which structures are involved in this variant; and to determine the associated causes. CONCLUSION: We found that five of the 124 patients (4%) with PRES had MR findings consistent with the central variant-that is, either brainstem or basal ganglia involvement and a lack of cortical or subcortical edema of the cerebrum. The thalami were involved in all five PRES patients with MR findings consistent with the central variant, but there was variable involvement of the posterior limb of the internal capsule (4/5), cerebellum (3/5), and periventricular white matter (3/5); in each patient, there was improvement both clinically and on MRI. The causes of PRES in these five patients were hypertension (n=2), cyclosporine (n=2), and eclampsia (n=1). The incidence of the central variant may be increasing because of an improving awareness of the diverse imaging patterns of PRES.

Accuracy of routine fat-suppressed FLAIR and diffusion-weighted images in detecting clinically evident acute optic neuritis.

BACKGROUND: Contrast-enhanced, fat-suppressed T1-weighted imaging (CET1WI) magnetic resonance imaging (MRI) is quite sensitive in detecting acute optic neuritis (ON), but ON remains a clinical diagnosis. MRI is indicated to evaluate demyelinating brain lesions rather than the optic nerves, while "routine" brain protocols typically include axial FLAIR and DWI. PURPOSE: To evaluate the accuracy of axial, fat-suppressed FLAIR and DWI sequences used for our routine brain imaging in detecting acute ON, as compared to CET1WI and the clinical diagnosis. MATERIAL AND METHODS: The clinical data and MRI examinations were retrospectively reviewed of 60 patients presenting to a neuro-ophthalmologist for various visual symptoms. Each patient underwent dedicated neuro-ophthalmologic examination, with axial 5 mm fat-suppressed FLAIR and DWI (part of "routine" brain MRI protocol), as well as 3 mm axial and coronal fat-suppressed CET1WI (part of dedicated orbit MRI protocol). Two neuroradiologists independently evaluated FLAIR and DWI, while CET1WI was reviewed by consensus. RESULTS: Thirty-one patients were clinically positive, 29 negative for ON (total = 34 positive and 86 negative nerves). The sensitivities of FLAIR, DWI, and CET1WI for ON were 75.7-77.3%, 77.3%, and 89.5%, respectively; the specificities were 90.5-93.5%, 80.4-82.7%, and 86.0%, respectively; the accuracies were 85.7-88.2%, 79.5-81.1%, and 87.0%, respectively. Inter-observer kappa was 0.783 for FLAIR, and 0.605 for DWI; intra-observer kappa was 0.746-0.816 for FLAIR, and 0.674-0.699 for DWI (each P < 0.0001). CONCLUSION: Being more specific, but not as sensitive, as dedicated CET1WI in acute ON, axial fat-suppressed FLAIR likely has additional value in evaluating for acute ON in "routine" brain MR protocols evaluating for demyelinating disease, while DWI may be hampered by artifacts.

Posterior reversible encephalopathy syndrome with a special focus on seizures.

Posterior reversible encephalopathy syndrome (PRES) is a neurological disorder characterized by headache, seizures, confusion and visual disturbances, as well as potentially reversible neuroimaging findings in most patients after proper treatment. Seizures is one of the most common clinical presentations of PRES. This review summarizes the potential pathophysiology and clinical features of PRES, as well as a multimodal approach to imaging and also briefly discusses the phenomenon of seizures in paediatric population.

The practical limits of high-quality magnetic resonance imaging for the diagnosis and classification of trigeminal neuralgia.

BACKGROUND: Neurovascular compression (NVC) has been the primary hypothesis for the underlying mechanism of classical trigeminal neuralgia (TN). However, a substantial body of literature has emerged highlighting notable exceptions to this hypothesis. The purpose of this study is to assess the reliability and diagnostic accuracy of high resolution, high contrast MRI-determined neurovascular contact for TN. METHODS: We performed a retrospective, randomized, and blinded parallel characterization of neurovascular interaction and diagnosis in a population of TN patients and controls using four expert reviewers. Performance statistics were calculated, as well as assessments for generalizability using shuffled bootstraps. RESULTS: Fair to moderate agreement (ICC: 0.32-0.68) about diagnosis between reviewers was observed using MRIs from 47 TN patients and 47 controls. On average reviewers performed no better than chance when diagnosing participants, with an accuracy of 0.57 (95% CI 0.40, 0.59) per patient. CONCLUSION: While MRI is useful in determining structural causes in secondary TN, expert reviewers do no better to only slightly better than chance with distinguishing TN with MRI, despite moderate agreement. Further, the causal role of NVC for TN is not clear, limiting the applicability of MRI to diagnose or prognosticate treatment of TN.

Toxic leukoencephalopathy following fludarabine-associated hematopoietic cell transplantation.

Toxic leukoencephalopathy has been more thoroughly investigated during the last decade because of the advance of magnetic resonance imaging (MRI) techniques. We analyzed fludarabine (Flu)-associated hematopoietic cell transplantation (HCT), resulting in severe leukoencephalopathy (n = 39/1596, 2.4%), and describe 3 clinical syndromes with unique clinical and radiographic characteristics. Posterior reversible encephalopathy syndrome (PRES) presents predominantly with seizures, persistent headache, and vision changes, along with variable mental status alterations. PRES is likely to be reversible, particularly after withholding cyclosporine (CsA). Acute toxic leukoencephalopathy (ATL) presents with cognitive dysfunction, decreased levels of consciousness, and vision changes. Other leukoencephalopathy (OLE) includes patients who behave similar to the ATL group, but with less prominent deep white matter changes on MRI. ATL and OLE are less likely to be reversible. The neurologic syndromes correlate with different MRI patterns. In PRES, subcortical and cortical involvement on MRI is associated with seizure, blurred vision, and dysarthria versus ATL and OLE, which involve deep white matter and cause mainly cognitive dysfunction. The different syndromes also carry different prognoses. All patients with Flu-associated encephalopathy had a median overall survival of only 169 days. Those with ATL had shorter overall survival (median 66 days) than patients with PRES (median 208 days). Potential risk factors for Flu-associated encephalopathy were older age, poor renal function, Flu dose, previously treated central nervous system (CNS) disease, or previous Flu-based transplant conditioning. Additional risk factors for PRES CNS toxicity are CsA use and acute hypertension. Flu pharmacokinetic studies may be useful to reduce life-threatening Flu-associated risks of neurotoxicity.

Urea Cycle Disorders: A Neuroimaging Pattern Approach Using Diffusion and FLAIR MRI.

BACKGROUND AND PURPOSE: This study aimed to assess characteristic regions of MRI involvement utilizing diffusion weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) at urea cycle disorder (UCD) diagnosis to determine the possible association between initial MRI patterns within 10 days of the first hyperammonemia episode, serum ammonia levels, and severity of neurological outcome based on clinical follow-up of >30 days. METHODS: Ten patients with UCDs (4 females; median age: 5.4 years, age range: 6 days-54 years) were included who underwent MRI during a first episode of hyperammonemia. The topographical distribution of the DWI and FLAIR abnormalities in the cerebral cortex, deep gray matter, white matter, posterior limb of internal capsule, cerebral peduncle, and cerebellum was evaluated. Possible correlations between the brain injury patterns on DWI/FLAIR images, serum ammonia levels, and severity of neurological outcome were investigated by a trend correlation. RESULTS: The UCD cohort (n = 10) involved four ornithine transcarbamoylase deficiencies, four argininosuccinic aciduria, one carbomoylphosphate synthetase deficiency, and one citrullinemia type-1. The observed trend in the distribution of DWI abnormalities as the severity of neurological sequela outcome increased was with diffuse cerebral cortex or corpus striatum involvement. Patients with initial peak serum ammonia ≥450 µmol/L had a grade 2 to 4 outcome, and those with peak ammonia <450 µmol/L had a grade 0 or 1 outcome. CONCLUSIONS: The presence of more severe neurological outcome could be associated with diffuse cerebral cortex or corpus striatum involvement on DWI and high serum ammonia levels in patients with UCD.

Role of Susceptibility-Weighted Imaging in Detecting Retinal Hemorrhages in Children with Head Trauma.

PURPOSE: This study was carried out to evaluate the utility of susceptibility-weighted imaging (SWI) in demonstrating retinal hemorrhages (RH) in pediatric head trauma. METHODS: Over a period of 7 years 67 children (age 0-4 years) with head trauma and MRI were included as either abusive head trauma (AHT) (n = 23), non-abusive head trauma (NAHT) (n = 38), or indeterminate (n = 6). Two pediatric neuroradiologists jointly reviewed the MR images for the presence of RH and sensitivity and specificity of SWI and T2WI were calculated. RESULTS: The dilated fundoscopic examination (DFE) was positive for RH in 18/23 (78.3%) of the AHT group, 5/38 (13.2%) in the NAHT group, and 4/6 (66.7%) in the indeterminate group. Regarding the SWI MRI findings, SWI was positive for RH in 13/23 (%56.5), while T2WI was positive in 6/23 (%26.1) of the AHT group. Based on utilizing DFE as a standard, the sensitivity and specificity of SWI in the detection of RH was 63% and 100%, respectively and 30% and 100%, respectively on T2WI. CONCLUSION: Our results suggest that SWI is a useful diagnostic tool for detection of RH in pediatric head trauma in whom DFE is difficult to perform.