Absence of Axoglial Paranodal Junctions in a Child With CNTNAP1 Mutations, Hypomyelination, and Arthrogryposis

Leukodystrophies and genetic leukoencephalopathies are a heterogeneous group of heritable disorders that affect the glial-axonal unit. As more patients with unsolved leukodystrophies and genetic leukoencephalopathies undergo next generation sequencing, causative mutations in genes leading to central hypomyelination are being identified. Two such individuals presented with arthrogryposis multiplex congenita, congenital hypomyelinating neuropathy, and central hypomyelination with early respiratory failure. Whole exome sequencing identified biallelic mutations in the CNTNAP1 gene: homozygous c.1163G>C (p.Arg388Pro) and compound heterozygous c.967T>C (p.Cys323Arg) and c.319C>T (p.Arg107*). Sural nerve and quadriceps muscle biopsies demonstrated progressive, severe onion bulb and axonal pathology. By ultrastructural evaluation, septate axoglial paranodal junctions were absent from nodes of Ranvier. Serial brain magnetic resonance images revealed hypomyelination, progressive atrophy, and reduced diffusion in the globus pallidus in both patients. These 2 families illustrate severe progressive peripheral demyelinating neuropathy due to the absence of septate paranodal junctions and central hypomyelination with neurodegeneration in CNTNAP1-associated arthrogryposis multiplex congenita.

Cerebral Diffusivity Changes in Fetuses with Chiari II Malformation

OBJECTIVES

Chiari II malformation is a congenital abnormality characterized by a small posterior fossa with downward displacement of the hindbrain into the foramen magnum. Diffusion-weighted imaging (DWI) can be used to quantitatively characterize brain injury and physiological maturation. We aim to evaluate DWI parameters of the infra- and supratentorial brain in fetuses with Chiari II malformation.

METHODS

MRI and US studies of 26 fetuses with Chiari II malformation and 15 controls were evaluated for the presence/severity of hydrocephalus, myelomeningocele level, and brain apparent diffusion coefficient (ADC) values. Cerebral flow impedance parameters (resistance and pulsatile indexes, resistance index [RI], and pulsatility index [PI] respectively) from concurrently preformed fetal US were also evaluated.

RESULTS

Of the Chiari II group, 16 fetuses had hydrocephalus. There was increasing severity of lateral ventriculomegaly in the high compared to low spinal dysraphism subgroups. There were significant lower ADC values in the frontal (p = 0.01) and temporal lobes (p = 0.05) in Chiari II group compared with normal, regardless of the presence or severity of hydrocephalus. Fetuses with Chiari II showed significantly lower RI and PI values.

CONCLUSIONS

Abnormal ADC values indicate supratentorial microstructural changes in fetuses with Chiari II malformation. Further investigation of the role of diffusion imaging metrics in evaluating abnormal brain development, parenchymal damage and efficacy of fetal surgery is needed.

"Cerebral Palsy" in a Patient With Arginase Deficiency

Inborn errors of metabolism (IEMs) are thought to present in infancy with acute decompensation including feeding intolerance and vomiting, lethargy, and coma. Most practitioners assume that children will be diagnosed in their first months of life. However, certain IEMs present more insidiously, and occasionally children fail to receive newborn screening resulting in delayed diagnoses, as metabolic and genetic disorders are overlooked causes of cognitive and neurologic deficits. Although signs and symptoms may be present but subtle, careful and detailed history taking, particularly of a child's diet and neurologic medical history, in addition to certain physical examination findings may suggest a diagnosis that is later supported by laboratory and radiographic testing. We present the case of an 11-year-old girl who presented with a diagnosis of cerebral palsy, seizure disorder, and concerns of fatigue and increasing seizure frequency. During hospitalization, she was found to have hyperammonemia, and a diagnosis of arginase deficiency was made. More thorough review of her previous records may have raised suspicion for IEM earlier.

Clival Malformations in CHARGE Syndrome

BACKGROUND AND PURPOSE

CHARGE syndrome is a multisystemic congenital disorder, most commonly including coloboma, heart malformations, choanal atresia, developmental delay, and genital and ear anomalies. The diagnostic criteria for CHARGE syndrome have been refined with time. However, limited reports describe skull base and craniocervical junction abnormalities. Recently, a coronal clival cleft has been identified in association with CHARGE syndrome. The aim of our study was to assess the prevalence of clival pathology in CHARGE syndrome.

MATERIALS AND METHODS

In this retrospective study, the CT/MR imaging data base at a single academic children's hospital was queried for the phrase "CHARGE syndrome" during a 17-year period (2001-2017). Electronic medical records were reviewed to confirm the diagnosis. Images were assessed for skull base anomalies, specifically clival hypoplasia and dysplasia.

RESULTS

The search yielded 42 examinations (21 CTs and 21 MRIs) from 15 distinct patients (mean age, 4.1 ± 5.6 years; range, 2 days to 19 years). CHARGE syndrome diagnosis was confirmed either by clinical and genetic testing (n = 6) or by clinical diagnosis only (n = 9). A coronal clival cleft was identified in 87% of patients (37 examinations, n = 13 patients), either partial (53%) or complete (33%). Clival hypoplasia without clefting was present in all 5 examinations from the remaining 2 patients.

CONCLUSIONS

Clival pathology is universal in CHARGE syndrome. Coronal clival clefts are extremely common, representing a useful additional diagnostic finding. Detection of a clival cleft should alert the radiologist to examine the palate, choana, eyes, ears, and olfactory centers for other signs of CHARGE syndrome.

Increased cerebral blood flow on arterial spin labeling magnetic resonance imaging can localize to seizure focus in newborns: A report of 3 cases

Arterial spin labeling (ASL) magnetic resonance imaging (MRI) can assess cerebral blood flow (CBF) without using radiolabeled tracers. It is unknown whether regional increases in CBF on ASL MRI correlate with seizure location in newborns. We report 3 newborns with focal seizures localized on continuous video electroencephalogram (cEEG), anatomical brain MRI, and ASL MRI. Each patient underwent pseudocontinuous ASL with segmented 3-dimensional fast spin echo readout as part of standard care. Case 1 is a term male infant presenting with left temporal status epilepticus and recurrent cEEG seizures from an idiopathic large left intraventricular hemorrhage. ASL images demonstrated left mesial temporal lobe increased CBF. Case 2 is a late preterm male infant presenting with recurrent cEEG seizures due to focal right megalencephaly. Ictal EEG and ASL images coincided with the focal dysplasia. Case 3 is a dysmorphic term female infant with nonconvulsive partial status epilepticus identified by focal increased CBF of the left temporal lobe on ASL images. The area of increased CBF was within an area of extensive left hemisphere dysplasia. To our knowledge, this is the first report of regional increases in CBF on ASL MRI correlating with ictal cEEG in newborns.

Hyponatremia: An Unusual Presentation in a Neonate With Chromosome 1q21.1 Deletion Syndrome

Chromosome 1q21.1 deletion syndrome is associated with a wide variety of clinical features including mild to moderate mental retardation, microcephaly, cardiac abnormalities, and cataracts. We report an unusual case of a premature neonate with persistent hyponatremia, markedly elevated plasma arginine vasopressin level (32.7 pg/mL), and clinical findings consistent with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). The patient, who also had microcephaly and dextrocardia, was subsequently diagnosed with chromosome 1q21.1 deletion syndrome. Further evaluation revealed hypothalamic abnormalities, features not previously described with this syndrome. To our knowledge, this is the first report of SIADH associated with congenital hypothalamic anomalies in a neonate with chromosome 1q21.1 deletion syndrome. We also report our experience using tolvaptan, a vasopressin receptor antagonist, in this patient to effectively maintain eunatremia.

Neuroimaging findings in Pallister-Killian syndrome

Pallister-Killian syndrome (PKS) is a rare chromosomal duplication disorder caused by additional copies of the short arm of chromosome 12 (12p). Clinically PKS is characterized by craniofacial dysmorphism with neonatal frontotemporal alopecia, hypertelorism, and low-set ears as well as kyphoscoliosis, severe intellectual disability, epilepsy, and abnormal muscle tone. Comprehensive high-resolution brain MR findings of PKS in childhood have not been previously illustrated in the medical literature. We present detailed neuroimaging findings from a child with PKS and thoroughly review previously reported structural brain abnormalities in this patient population. MRI abnormalities common to PKS include cerebral volume loss, malformations of cortical development, corpus callosum dysgenesis, white matter disease, and craniofacial malformations. In our patient, new findings of perisylvian with occipital polymicrogyria, vermian dysplasia, brachium pontis signal abnormality, dural anomalies, and unilateral atlas assimilation were noted. Micrencephaly and cortical dysplasia provide a likely explanation for severe intellectual disability and epilepsy in this patient population.

Black Toenail Sign in MELAS Syndrome

BACKGROUND

Mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome is a mitochondrial disorder often causing progressive brain injury that is not confined to large arterial territories. Severe insults ultimately lead to gyral necrosis affecting the cortex and juxtacortical white matter; the neuroimaging correlate is partial gyral signal suppression on T2/FLAIR sequences that resemble black toenails. We aimed to characterize the imaging features and the natural history of MELAS-related gyral necrosis.

MATERIALS AND METHODS

Databases at two children's hospitals were searched for brain magnetic resonance imaging studies of individuals with MELAS. Examinations with motion artifact and those lacking T2/FLAIR sequences were excluded. The location, the cumulative number, and the maximum transverse diameter of necrotic gyral lesions were assessed using T2-weighted images and T2/FLAIR sequences. Wilcoxon signed-rank test was employed to evaluate the relationship between disease duration and the number of necrotic lesions.

RESULTS

One hundred twenty-four examinations from patients with 14 unique MELAS patients (16 ± 3 years) were evaluated. Six of the eight patients who developed brain lesions also developed gyral necroses (mean 13, range 0 to 44). Necrotic lesions varied in maximal diameter from 4 to 25 mm. Cumulative necrotic lesions correlated with disease duration (P < 0.001).

CONCLUSIONS

The black toenail sign signifying gyral necrosis is a common imaging feature in individuals with MELAS syndrome. The extent of gyral necrosis correlates with disease duration.

Cortical venous disease severity in MELAS syndrome correlates with brain lesion development

PURPOSE

MELAS syndrome is a mitochondrial disorder typified by recurrent stroke-like episodes, seizures, and progressive brain injury. Abnormal mitochondria have been found in arterial walls implicating a vasculogenic etiology. We have observed abnormal cortical vein T2/FLAIR signal in MELAS patients, potentially representing wall thickening and sluggish flow. We sought to examine the relationship of hyperintense veins and brain lesions in MELAS.

METHODS

Imaging databases at two children's hospitals were searched for brain MRIs from MELAS patients. Artifact, sedated exams, and lack of 2D-T2/FLAIR sequences were exclusion criteria. Each exam was assigned a venous score based on number of T2/FLAIR hyperintense veins: 1 = <10, 2 = 10 to 20, 3 = >20. Cumulative brain lesions and venous score in MELAS and aged-matched normal exams were compared by Mann-Whitney test.

RESULTS

A total of 106 exams from 14 unique MELAS patients (mean 16 ± 3 years) and 30 exams from normal aged-matched patients (mean 15 ± 3 years) were evaluated. Median venous score between MELAS and control patients significantly differed (3 versus 1; p < 0.001). In the MELAS group, venous score correlated with presence (median = 3) or absence (median = 1) of cumulative brain lesions. In all 8 MELAS patients who developed lesions, venous hyperintensity was present prior to, during, and after lesion onset. Venous score did not correlate with brain lesion acuity.

CONCLUSION

Abnormal venous signal correlates with cumulative brain lesion severity in MELAS syndrome. Cortical venous stenosis, congestion, and venous ischemia may be mechanisms of brain injury. Identification of cortical venous pathology may aid in diagnosis and could be predictive of lesion development.

The association among prematurity, cochlear hyperintensity, and hearing loss

Background Prematurity is a major risk factor for neonatal hearing loss. Recent advancements in magnetic resonance imaging (MRI) have made it possible to evaluate structural details of the membranous labyrinths in premature infants that have heretofore been inaccessible. Objective We compared the prevalence of abnormal cochlear signal intensity in premature and term neonates and evaluated for a potential link with hearing loss. Materials and methods We retrospectively reviewed 148 consecutive MR exams performed in premature (< 37 weeks' gestation) and term neonates performed over a 30-month period. Cochlear signal alteration was evaluated on three-dimensional T1-weighted imaging (T1WI) sequences. Each patient's electronic medical record was reviewed to document demographics, symptomatology, physical exam findings, and potential medical variables that could contribute to cochlear signal alteration. Results Cochlear hyperintensity on T1WI was present in 6.8% patients ( n = 10) overall, but was much more common in preterm than term patients (12.2% (9 of 74) vs. 1.4% (1 of 74), respectively; p value < 0.05; Fisher's exact test). Overall, 14.9% ( n = 15) of the patients with hearing test results failed the screening Auditory Brainstem Response exam. However, failure was much more common among patients with cochlear hyperintensity on T1W1 than those with normal findings (56% (5 of 9) vs. 11% (10 of 92), respectively; p value < 0.01; Fisher's exact test). Conclusion Cochlear hyperintensity on T1WI is more common in preterm than term neonates, and potentially associated with hearing loss. Cochleae should be closely scrutinized in all premature infants; signal alterations should prompt further diagnostic inquiry and possible early otolaryngology referral.

Biotin-thiamine responsive basal ganglia disease: Identification of a pyruvate peak on brain spectroscopy, novel mutation in SLC19A3, and calculation of prevalence based on allele frequencies from aggregated next-generation sequencing data

Biotin-thiamine responsive basal ganglia disease is an inborn error of metabolism caused by mutations in SLC19A3, encoding a transporter of thiamine across the plasma membrane. We report a novel mutation identified in the homozygous state in a patient with typical brain MRI changes. In addition, this patient had markedly elevated CSF pyruvate, a low lactate-to-pyruvate molar ratio, and an abnormal pyruvate peak at 2.4 ppm on brain magnetic resonance spectroscopy. Using aggregated exome sequencing data, we calculate the carrier frequency of mutations in SLC19A3 as 1 in 232 individuals in the general population, for an estimated prevalence of the disease of approximately 1 in 215,000 individuals. The disease is thus more frequent than previously recognized, and the presence of a pyruvate peak on spectroscopy could serve as an important diagnostic clue.

Cerebral modulation of the autonomic nervous system in term infants

OBJECTIVE

Central topography of autonomic nervous system (ANS) function has yet to be fully deciphered. In adults it has been shown to lateralize sympathetic and parasympathetic influence predominantly to the right and left cerebral hemispheres, respectively. We examined functional topography of central ANS in newborn subjects utilizing spectral analysis of heart rate variability (HRV), an established measure of ANS function.

STUDY DESIGN

We studied newborns with hypoxic-ischemic encephalopathy participating in a prospective study undergoing a therapeutic hypothermia protocol.We included subjects with continuous heart rate data over the first 3 h of normothermia (post rewarming) and brain magnetic resonance imaging, which was reviewed and scored according to a 4 region scheme. HRV was evaluated by spectral analysis in the low-frequency (0.05 to 0.25 Hz) and high-frequency (0.3 to 1 Hz) ranges. The relationship between injured brain regions and HRV was studied using multiple regressions.

RESULTS

Forty eight newborns were included. When examined in isolation, right hemisphere injury had a significant negative effect on HRV (-0.088; 95% CI: -0.225,-0.008). The combination of posterior fossa region injury with right hemispheric injury or left hemispheric injury demonstrated significant positive (0.299; 95% CI: 0.065, 0.518) and negative (-0.475; 95% CI: -0.852, -0.128) influences on HRV, respectively. The association between brain injury location and HRV in the high-frequency range did not reach significance.

CONCLUSION

Our data support the notion that lateralized cerebral modulation of the ANS, specifically of its sympathetic component, is present in the term newborn, and suggest complex modulation of these tracts by components of the posterior fossa.

Patterns of Brain Injury in Newborns Treated with Extracorporeal Membrane Oxygenation

BACKGROUND AND PURPOSE

Neonates treated with extracorporeal membrane oxygenation are at risk for brain injury and subsequent neurodevelopmental compromise. Advances in MR imaging and improved accessibility have led to the increased use of routine MR imaging after extracorporeal membrane oxygenation. Our objective was to describe the frequency and patterns of extracorporeal membrane oxygenation-related brain injury based on MR imaging findings in a large contemporary cohort of neonates treated with extracorporeal membrane oxygenation.

MATERIALS AND METHODS

This was a retrospective study of neonatal patients treated with extracorporeal membrane oxygenation from 2005-2015 who underwent MR imaging before discharge. MR imaging and ultrasound studies were reviewed for location and type of parenchymal injury, ventricular abnormalities, and increased subarachnoid spaces. Parenchymal injury frequencies between patients treated with venoarterial and venovenous extracorporeal membrane oxygenation were compared by χ² tests.

RESULTS

Of 81 neonates studied, 46% demonstrated parenchymal injury; 6% showed infarction, mostly in vascular territories (5% anterior cerebral artery, 5% MCA, 1% posterior cerebral artery); and 20% had hemorrhagic lesions. The highest frequency of injury occurred in the frontal (right, 24%; left, 25%) and temporoparietal (right, 14%; left, 19%) white matter. Sonography had low sensitivity for these lesions. Other MR imaging findings included volume loss (35%), increased subarachnoid spaces (44%), and ventriculomegaly (17% mild, 5% moderate, 1% severe). There were more parenchymal injuries in neonates treated with venoarterial (49%) versus venovenous extracorporeal membrane oxygenation (29%, P = .13), but the pattern of injury was consistent between both modes.

CONCLUSIONS

MR imaging identifies brain injury in nearly half of neonates after treatment with extracorporeal membrane oxygenation. The frontal and temporoparietal white matter are most commonly affected, without statistically significant laterality. This pattern of injury is similar between venovenous and venoarterial extracorporeal membrane oxygenation, though the frequency of injury may be higher after venoarterial extracorporeal membrane oxygenation.

Reduced subarachnoid fluid diffusion in enlarged subarachnoid spaces of infancy

Background and purpose Enlargement of the subarachnoid spaces in infancy (ESSI) is a common cause of macrocephaly without proven explanation. We have observed subarachnoid diffusion to be decreased in these patients. We aim to quantify the diffusivity of ventricular and subarachnoid cerebrospinal fluid in ESSI patients, to determine if diffusion characteristics deviate from normocephalic infants, and to propose a unique mechanism for ESSI. Materials and methods 227 consecutive brain magnetic resonance exams from different macrocephalic children were retrospectively reviewed after institutional review board waiver. Patients with noncommunicating hydrocephalus, substantial ventriculomegaly, atrophy, structural bone and/parenchymal abnormalities, abnormal brain signal, hemorrhages, meningitis, and normal imaging were excluded. A total of 53 exams from macrocephalic patients and 21 normocephalic subjects were analyzed. Mean quantitative apparent diffusion coefficient (ADC) values were obtained from the ventricular frontal horn and frontal subarachnoid spaces. The subarachnoid:ventricular ADC ratios were compared using a Mann-Whitney U-test. Results The mean age was 13 +/-8 months (macrocephalic cohort) and 13 +/- 6 months (normocephalic cohort). The subarachnoid fluid mean ADC was 2.50+/-0.26 × 10^-3 mm²/s in the macrocephalic group and 2.84+/-0.29 × 10^-3 mm²/s in the normocephalic group. The ventricular fluid mean ADC was 2.97+/-0.37 × 10^-3 mm²/s and 2.74 +/-0.32 × 10^-6 mm²/s, respectively. The mean quantitative ADC ratios in the macrocephalic group were 0.85, significantly smaller than the normocephalic group (1) ( z = -6.3; p = 0). Conclusion Subarachnoid space fluid diffusivity is reduced in patients with enlarged subarachnoid spaces of infancy. We propose insufficient frontotemporal capillary protein resorption to be the initiating factor in ESSI, leading to unbalanced osmotic/hydrostatic pressures, and secondary congestion.

Repeat surgery for focal cortical dysplasias in children: indications and outcomes

OBJECTIVE Focal cortical dysplasia (FCD) is a common cause of medically intractable epilepsy that often may be treated by surgery. Following resection, many patients continue to experience seizures, necessitating a decision for further surgery to achieve the desired seizure outcomes. Few studies exist on the efficacy of reoperation for intractable epilepsy due to FCD in pediatric cohorts, including the definition of prognostic factors correlated with clinical benefit from further resection. METHODS The authors retrospectively analyzed the medical records and MR images of 22 consecutive pediatric patients who underwent repeat FCD resection after unsuccessful first surgery at the Children's National Health System between March 2005 and April 2015. RESULTS Accounting for all reoperations, 13 (59%) of the 22 patients achieved complete seizure freedom and another 5 patients (23%) achieved significant improvement in seizure control. Univariate analysis demonstrated that concordance in electrocorticography (ECoG) and MRI localization (p = 0.005), and completeness of resection (p = 0.0001), were associated with seizure freedom after the first reoperation. Patients with discordant ECoG and MRI findings ultimately benefited from aggressive multilobe lobectomy or hemispherectomy. Repeat lesionectomies utilizing intraoperative MRI (iMRI; n = 9) achieved complete resection and seizure freedom in all cases. CONCLUSIONS Reoperation may be clinically beneficial in patients with intractable epilepsy due to FCD. Patients with concordant intraoperative ECoG and MRI localization may benefit from extended resection of residual dysplasia at the margins of the previous lesional cavity, and iMRI may offer benefits as a quality control mechanism to ensure that a complete resection has been accomplished. Patients with discordant findings may benefit from more aggressive resections at earlier stages to achieve better seizure control and ensure functional plasticity.

Coronal clival cleft in CHARGE syndrome

CHARGE syndrome is a genetic disorder with multi-systemic congenital anomalies, most commonly including coloboma, heart malformations, choanal atresia, developmental delay, and genital and ear anomalies. The diagnostic criteria for CHARGE syndrome has been refined over the years. However, there are limited reports describing skullbase and craniocervical junction abnormalities. These osseous malformations are often under recognized, especially on MRI. We report here a case of CHARGE syndrome with colobomas, cleft lip and palate, patent ductus arteriosus, undescended testes, and a coronal clival cleft which has not been previously depicted in CHARGE syndrome. The presence of a coronal clival cleft should alert the radiologist to examine the ears, eyes, palate, choana, and olfactory centers for other signs of CHARGE syndrome.

Fetal anemia, cerebellar hemorrhage and hypoplasia associated with congenital Parvovirus infection

We report a case of fetal cerebellar hemorrhage and hypoplasia, identified by fetal MRI after intrauterine blood transfusion at 21 weeks' gestation for treatment of severe anemia due to congenital Parvovirus infection. Postnatal MRI confirmed atrophy of bilateral cerebellar hemispheres and inferior vermis. Cerebellar capillaries may be extremely susceptible to hemodynamic changes in the setting of intrauterine blood transfusion due to severe anemia. Although the correlation between fetal intracranial anomalies and Parvovirus infection remains unclear, in this population, a detailed evaluation of the brain parenchyma should be considered prior to and after intrauterine blood transfusion.

Lesional perfusion abnormalities in Leigh disease demonstrated by arterial spin labeling correlate with disease activity

BACKGROUND

Leigh disease is a metabolic disorder of the mitochondrial respiratory chain culminating in symmetrical necrotizing lesions in the deep gray nuclei or brainstem. Apart from classic gliotic/necrotic lesions, small-vessel proliferation is also characteristic on histopathology. We have observed lesional hyperperfusion on arterial spin-labeling (ASL) sequence in children with Leigh disease.

OBJECTIVE

In this cross-sectional analysis, we evaluated lesional ASL perfusion characteristics in children with Leigh syndrome.

MATERIALS AND METHODS

We searched the imaging database from an academic children's hospital for "arterial spin labeling, perfusion, necrosis, lactate, and Leigh" to build a cohort of children for retrospective analysis. We reviewed each child's medical record to confirm a diagnosis of Leigh disease, excluding exams with artifact, technical limitations, and without ASL images. We evaluated the degree and extent of cerebral blood flow and relationship to brain lesions. Images were compared to normal exams from an aged-matche cohort.

RESULTS

The database search yielded 45 exams; 30 were excluded. We evaluated 15 exams from 8 children with Leigh disease and 15 age-matched normal exams. In general, Leigh brain perfusion ranged from hyperintense (n=10) to hypointense (n=5). Necrotic lesions appeared hypointense/hypoperfused. Active lesions with associated restricted diffusion demonstrated hyperperfusion. ASL perfusion patterns differed significantly from those on age-matched normal studies (P=<.0001). Disease activity positively correlated with cerebral deep gray nuclei hyperperfusion (P=0.0037) and lesion grade (P=0.0256).

CONCLUSION

Children with Leigh disease have abnormal perfusion of brain lesions. Hyperperfusion can be found in active brain lesions, possibly associated with small-vessel proliferation characteristic of the disease.