Nilesh K. Desai

Performance of spin-echo and gradient-echo T1-weighted sequences for evaluation of dural venous sinus thrombosis and stenosis.

OBJECTIVE Dural venous sinus abnormalities are clinically important but can potentially be overlooked using various MRI techniques. This study evaluates the diagnostic accuracy of spin-echo (SE) T1-weighted imaging, 3D gradient-recalled echo (GRE) T1-weighted imaging, and contrast-enhanced MR venography (MRV) for the detection of dural venous sinus thrombosis and transverse sinus (TS) stenosis. MATERIALS AND METHODS Seventy-three patients underwent MRI evaluation with unenhanced and contrast-enhanced axial SE T1-weighted imaging, contrast-enhanced sagittal 3D GRE T1-weighted imaging, and contrast-enhanced MRV sequences. Three neuroradiologists each evaluated these 219 total datasets in a randomized blinded fashion for the presence or absence of TS stenosis and for dural venous sinus thrombosis in each of 10 venous sinus segments (730 total segments). Diagnostic performance characteristics and kappa statistics were calculated for each technique. RESULTS Thirteen patients (37 segments) had suspected dural venous sinus thrombosis by one or more readers; of those 13 patients, nine (23 segments) were thought to have definite thrombosis on contrast-enhanced MRV. Compared with contrast-enhanced MRV, the positive predictive value (PPV) and negative predictive value (NPV) for thrombosis were 60% and 97%, respectively, for both unenhanced and contrast-enhanced SE T1-weighted imaging and 100% and 98% for 3D GRE T1-weighted imaging. Kappa values calculated per venous segment were as follows: 0.41 for SE T1-weighted imaging, 0.72 for 3D GRE T1-weighted imaging, and 0.95 for contrast-enhanced MRV. Thirty patients (58 segments) had TS stenosis suspected by one or more readers; of those 30 patients, TS stenosis was deemed to be definite on contrast-enhanced MRV in 25 patients (50 segments). Compared with contrast-enhanced MRV, the PPV and NPV were 75% and 80%, respectively, for SE T1-weighted imaging and 91% and 92% for 3D GRE T1-weighted imaging for the detection of stenosis. Kappa values calculated per patient were -0.038 for SE T1-weighted imaging, 0.58 for 3D GRE T1-weighted imaging, and 0.98 for contrast-enhanced MRV. CONCLUSION Contrast-enhanced 3D GRE T1-weighted imaging is superior to SE T1-weighted imaging for the detection of dural venous sinus thrombosis and TS stenosis but does not substitute for dedicated MRV. Hyperintensity on unenhanced SE T1-weighted imaging is unreliable for the detection of dural venous sinus thrombosis.

Screening CT Angiography for Pediatric Blunt Cerebrovascular Injury with Emphasis on the Cervical "Seatbelt Sign"

The authors investigated the significance of several clinical and imaging risk factors, most specifically the “cervical seatbelt sign,” in the anterior neck in pediatric patients with suspected blunt cerebrovascular injury as seen by CTA. They found that this common indication for neck CTA was not associated with blunt cerebrovascular injury. With the exception of Glasgow Coma Scale score, no single risk factor was statistically significant in predicting vascular injury. BACKGROUND AND PURPOSE: There are no standard screening guidelines to evaluate blunt cerebrovascular injury in children. The purpose of this retrospective study was to understand the clinical and radiologic risk factors associated with pediatric blunt cerebrovascular injury on CTA of the neck with primary attention to the cervical “seatbelt sign.” MATERIALS AND METHODS: Radiology reports from 2002 to 2012 were queried for the examination “CTA neck.” The electronic medical record was reviewed for mechanism of injury, Glasgow Coma Scale score, and physical examination findings. Radiology reports from adjunct radiographic studies were reviewed. CTA neck examinations with reported blunt cerebrovascular injury were reviewed to confirm imaging findings. Patients with penetrating injury or those without a history of trauma were excluded. RESULTS: Four hundred sixty-three patients underwent CTA of the neck; 137 had blunt trauma. Forty-two of 85 patients involved in a motor vehicle collision had a cervical seatbelt sign; none had blunt cerebrovascular injury. Nine vessels (4 vertebral arteries, 4 ICAs, 1 common carotid artery) in 8 patients ultimately were diagnosed with various grades (I–IV) of blunt cerebrovascular injury, representing 5.8% (8/137) of the population screened for blunt neck trauma. The mean Glasgow Coma Scale score was significantly lower (P = .02) in the blunt cerebrovascular injury group versus the non-blunt cerebrovascular injury group. Although not statistically significant, patients with blunt cerebrovascular injury had a higher tendency to have additional traumatic injuries, primarily basilar skull fractures (P = .05) and intracranial hemorrhage (P = .13). CONCLUSIONS: A common indication for neck CTA, the cervical seatbelt sign, was not associated with blunt cerebrovascular injury. With the exception of Glasgow Coma Scale score, no single risk factor was statistically significant in predicting vascular injury in this series.

Pontine Tegmental Cap Dysplasia The Neurotologic Perspective

Objectives. Pontine tegmental cap dysplasia (PTCD) is a rare congenital malformation. Clinical and imaging findings in 3 patients and the authors’ experience with bilateral cochlear implantation in 1 patient are described. Study Design. Retrospective review. Setting. Two tertiary medical centers. Subjects and Methods. Three patients were evaluated by an otolaryngologist and underwent magnetic resonance imaging (MRI) of the temporal bones and brain. High-resolution computed tomography (CT) scanning of the temporal bones was performed in 2 patients. Imaging findings of the brain, the presence and course of resolvable cranial nerves, the membranous labyrinth, and internal auditory canals were reviewed. Clinical data were reviewed. Results. All patients demonstrated typical brain characteristics of PTCD. Mild, bilateral cochlear dysplasia was noted in 2, and all had a normal vestibular labyrinth. The cochleovestibular nerves were universally absent bilaterally. The facial nerves were subjectively deficient bilaterally in 1 patient, unilaterally in the second patient, and normal in the third. An accessory canal for the seventh cranial nerve, referred to as a duplicated internal auditory canal, was present in all patients. Auditory brainstem response testing revealed profound bilateral sensorineural hearing loss in all of the patients; none suffered facial weakness. A single patient underwent bilateral cochlear implantation with only minimal response. Conclusion. The authors report 3 cases of PTCD with emphasis on imaging of the seventh and eighth cranial nerves and clinical neurotologic findings. All patients manifested duplicated internal auditory canals, a previously unreported finding in PTCD. Bilateral profound sensorineural hearing loss is due to absence of the cochleovestibular nerve. Prognosis for cochlear implantation is poor.

The Role of Magnetic Resonance Imaging in Diagnosing Optic Nerve Hypoplasia

PURPOSE To establish objective lower limits of normal optic nerve (ON) size in children based on high-resolution orbital magnetic resonance imaging (MRI). DESIGN Case-control study of patients with ON hypoplasia vs normal controls. METHODS A neuroradiologist made 4 measurements of each ON at 2 locations (5 mm posterior to the optic disc and just posterior to the optic canal) in patients with ON hypoplasia and controls aged 0-17 years from an academic eye center and childrens hospital. Primary analyses were performed using mixed linear models. RESULTS Measurements were made in 26 cases of clinically confirmed ON hypoplasia and 31 controls (median age: ON hypoplasia, 1 year; controls, 5.5 years). Nine of 26 cases (35%) and 19 of 31 controls (61%) underwent high-resolution T2-weighted imaging of the orbits. Mean ON diameter was 1.36 mm (95% CI: 1.19-1.54; P < .001) smaller for clinically hypoplastic ONs than for controls. Optic nerve diameter increased by 0.05 mm per year of age (95% CI: 0.03-0.07; P < .001). A lower bound to the 95% prediction interval for normal optic nerves was (2.24 mm + 0.052 × [age in years]) mm and excluded all but 1 case. CONCLUSIONS Age was independently associated with normal ON size by MRI and should be taken into consideration when evaluating ON hypoplasia, based on MRI criteria. We have provided a formula to assist clinicians in objectively determining if ON hypoplasia is present.

Transverse sinus stenosis in adult patients with Chiari malformation type I.

OBJECTIVE Transverse sinus stenosis is an imaging finding very highly associated with elevated intracranial pressure (ICP). Patients with the Chiari I malformation may potentially have elevated ICP due to impairment of CSF flow at the foramen magnum. This study evaluated whether patients with Chiari I malformation have transverse sinus stenosis and other imaging findings indicative of elevated ICP. MATERIALS AND METHODS Thirty patients with Chiari I malformation treated surgically and 76 control subjects were identified retrospectively. All control subjects and all patients with Chiari I malformation (preoperatively) underwent standardized contrast-enhanced brain MRI including a contrast-enhanced 3D T1-weighted sequence from which curved reformats of the transverse sinuses were generated. Two different readers blinded to the diagnosis then independently evaluated these curved reformats for severity of transverse sinus stenosis. Orbital and skull-base findings previously described in association with elevated ICP were also evaluated. Frequency of MRI findings between the two groups was compared. RESULTS Patients with Chiari I malformation had significantly greater frequency of unilateral or bilateral transverse sinus stenosis than did control subjects (p < 0.001). There was complete interreader agreement on presence or absence of transverse sinus stenosis by patient (κ = 1.0 [95% CI, 0.89-1.0]). Logistic regression analysis controlling for age, sex, and body mass index found that transverse sinus stenosis significantly predicted Chiari I malformation versus control status (odds ratio, 11.2 [95% CI, 2.1-59.0]; p = 0.004) but that no other features were significantly associated with the Chiari I malformation. Patients with Chiari I malformation who had transverse sinus stenosis had significantly greater pituitary flattening than did those without transverse sinus stenosis (p = 0.02). CONCLUSION Patients with Chiari I malformation have higher likelihood of transverse sinus stenosis, which may reflect associated elevated ICP.

Utility of double inversion recovery MRI in paediatric epilepsy

Detecting focal abnormalities in MRI examinations of children with epilepsy can be a challenging task given the frequently subtle appearance of cortical dysplasia, mesial temporal sclerosis and similar lesions. In this report, we demonstrate the utility of double inversion recovery MRI in the detection of paediatric epileptogenic abnormalities, promoted primarily by increased lesion conspicuity due to complementary suppression of both cerebrospinal fluid and normal white matter signal.

Site for Bone-Anchored Hearing System for Children Younger than 5 Years

Objective To describe in children younger than the present US FDA–approved 5 years of age the thickest part of the temporal bone available for placement of a bone-anchored hearing system. Children with unilateral hearing loss, as with aural atresia, have deficits in at least language comprehension and oral expression. The early provision of hearing to the atretic ear may minimize the potential for auditory deprivation. Study Design Point prevalence descriptive study. Setting Tertiary referral pediatric hospital. Subjects and Methods Thirty-eight patients less than 6 years old with congenital aural atresia had undergone temporal bone computed tomography (CT). Bone thickness lateral (ie, superficial) to the sinodural angle, in the topmost axial CT slice that included any adjacent petrous ridge, was measured. Results The mean bone thicknesses lateral to the sinodural angles of the atretic ears were 5.1, 5.0, 5.9, 5.2, 5.2, and 4.8 mm for the <1, 1-, 2-, 3-, 4-, 5-year-olds, respectively; of the non-atretic ears, thicknesses were 4.1, 4.9, 5.5, 6.7, 4.3, and 4.7 mm. Conclusion Based on this small case series, bone thickness lateral (ie, superficial) to the sinodural angle is sufficient for many children suffering from aural atresia to have bone-anchored hearing devices implanted younger than age 5 years. Use of the sinodural site would require a magnetic bone-anchored hearing system, which could be repositioned posteriorly at age 5 years when pinna construction and atresiaplasty endeavors typically begin.

An Imaging Approach to Diffuse White Matter Changes

White matter disorders represent a large, heterogeneous group of disorders that span the continuum of congenital metabolic disorders to acquired processes, such as chronic ischemic microvascular white matter disease. Magnetic resonance imaging has dramatically revolutionized the diagnostic evaluation of patients with these disease processes.

Neurodegeneration with Brain Iron Accumulation in an Eleven-Year-Old Jamaican Male

We present a case of an eleven-year-old boy presenting with progressive extrapyramidal signs and dementia. His imaging findings demonstrated the classic eye-of-the-tiger sign on T2W magnetic resonance imaging. He was diagnosed with pantothenate kinase-associated neurodegeneration (PKAN). This is a rare autosomal recessive inborn error of coenzyme A metabolism, caused by mutations in PANK2. This is the first reported case of PKAN from the Caribbean.

A Case of Neurosarcoidosis with Labyrinthine Involvement

Sarcoidosis is a chronic granulomatous disease of unknown aetiology, which may involve any organ system. It most commonly occurs in adults with childhood involvement being rare. Central nervous system involvement is seen in up to 25% and typically involves meningeal disease resulting in multiple cranial neuropathies. Other common clinical findings include seizures, headache, dementia, and pituitary dysfunction. Imaging plays a central role in the diagnosis with typical findings including pachymeningeal and leptomeningeal enhancing lesions. Other imaging findings include lacunar and major territory infarcts, hypothalamic and infundibular thickening, hydrocephalus, and cranial nerve enhancement. We present a case of an eight-year-old male patient with progressive headache, visual disturbance, unilateral sensory hearing loss, and multiple cranial neuropathies. Imaging findings demonstrated the classic pachymeningeal and leptomeningeal enhancement along much of the skull base, as well as enhancement of the right and left second and eighth cranial nerves. Extensive inflammatory changes were noted in the temporal bones and paranasal sinuses. There was also enhancement of the right and left labyrinths. Sinus biopsy confirmed sarcoidosis. We present the first case to our knowledge of sarcoid labyrinthitis.