Financial Disclosures & Disclaimers Differentials in Pediatric Brain Imaging William T. O Brien, Sr., D.O. Program Director, Diagnostic Radiology Residency, DGMC Associate Clinical Professor of Radiology University of California, Davis School of Medicine Sacramento, CA Receive royalties from Thieme Medical Publishers Top 3 Differentials in Radiology: A Case Review, 2010 Top 3 Differentials in Neuroradiology: A Case Review, 2015 The views expressed in this material are those of the author and do not reflect the official policy or position of the U.S. Government, Department of Defense, or U.S. Air Force 2 Differentials in Pediatric Brain Imaging Learning Objectives Recognize and describe pertinent imaging findings from unknown pediatric brain cases Review differential diagnoses for common & important abnormalities within the pediatric brain Understand imaging features of various gamuts in pediatric brain imaging Unknown Cases 3 4 Unknown Cases Case #1 Unknown Cases Case #2 Adolescent 5 6 1
Unknown Cases Case #3 Unknown Cases Case #4 7 8 Unknown Cases Case #5 Unknown Cases Case #6 9 10 Case Review Case #1 11 12 2
Adolescent Confluent white matter disease in a child - Multiple sclerosis (MS) - Acute disseminating encephalomyelitis (ADEM) - Dysmyelinating disease (leukodystrophy) Additional Diagnostic Considerations: - Toxic leukoencephalopathy (chemo/radiation) - Atypical infection (PML, HIV) Diagnosis: Dysmyelinating disease (ALD) 13 14 Confluent white matter disease in a child Multiple sclerosis (MS) Occurs predominantly in young to middle-aged women May also affect children Schilder variant affects children Marburg variant is fulminant & progressive Relapsing & remitting course most common MR reveals: Ovoid lesions in characteristic locations, may be confluent Active demyelination may enhance and/or restrict diffusion Enhancement nodular or open ring Confluent white matter disease in a child Multiple sclerosis (MS) Young girl with advanced MS Numerous white matter lesions; active lesions demonstrate peripheral nodular and ring-enhancement along leading edge 15 16 Confluent white matter disease in a child Acute disseminated encephalomyelitis ADEM is a monophasic autoimmune demyelinating dz Occurs in children following a viral infection or vaccination Varies from self-limiting to fulminant encephalitis MRI reveals bilateral T2 bright white matter lesions Often similar distribution & morphology to MS Periventricular Corpus callosum Posterior fossa / brainstem / cord More likely to be confluent and extensive compared to MS Active lesions may enhance or show diffusion restriction Confluent white matter disease in a child Acute disseminated encephalomyelitis Young boy with acute onset neurological deficits FLAIR image shows bilateral, confluent regions of abnormal WM hyperintensity Abnormal signal extends into corpus callosum 17 18 3
Confluent white matter disease in a child Dysmyelinating Disease Leukodystrophies result in dysmelination Enzyme deficiencies cause accumulation of toxic metabolites Affects myelin formation & repair Patients present with visual or behavioral disturbances MR shows symmetric, confluent WM signal abnormality Metachromatic leukodystrophy is most common ALD commonly affects boys (x-linked) & adrenal glands Alexander dz has frontal lobe predominance & macrocephaly Canavan dz has increased NAA on MRS & macrocephaly Confluent white matter disease in a child Dysmyelinating Disease 12-yo boy with metachromatic leukodystrophy Axial CT shows symmetric confluent regions of WM hypoattenuation FLAIR image better depicts diffuse WM hyperintensity 19 20 Confluent white matter lesions in a child Toxic Encephalopathy Confluent white matter lesions in a child Toxic Encephalopathy Chemotherapy may result in: Relatively symmetric WM signal abnormality May involve cerebrum (incl corpus callosum), cerebellum, & brainstem Radiation therapy related WM signal abnormalities correlate to treatment field Radiation necrosis may mimic neoplasm recurrence 19-yr-old boy pre and post treatment for germinoma Pre-treatment FLAIR image is normal Post-treatment FLAIR image shows symmetric confluent WM hyperintensity including the CC Pre-treatment Post-treatment 21 22 Confluent white matter lesions in a child Atypical Infection HIV encephalopathy/dementia may present: Volume loss disproportionate for age (most common) Symmetric periventricular WM signal abnormality PML is an atypical infection (JC virus) in immunosuppressed patients (typically AIDS) Affects oligodendrocytes Results in confluent increased T2 WM signal abnormality May be bilateral but typically asymmetric Enhancement is unusual Confluent white matter lesions in a child Atypical Infection Young adult man with AIDS dementia complex FLAIR image shows symmetric confluent WM hyperintensity with frontal lobe predominance and involvement of CC 23 24 4
Confluent white matter lesions in a child Atypical Infection Confluent white matter disease in a child Differential Diagnosis Review Young adult man with AIDS and PML FLAIR image reveals asymmetric (L>R) confluent WM hyperintensity in centrum semiovale - Multiple sclerosis (MS) - Acute disseminating encephalomyelitis (ADEM) - Dysmyelinating disease (leukodystrophy) Additional Diagnostic Considerations: - Toxic leukoencephalopathy (chemo/radiation) - Atypical infection (PML, HIV) *Image courtesy of Paul Sherman, M.D. 25 26 Case #2 27 28 - Craniopharyngioma - Germ cell tumor (GCT) - Optic pathway/hypothalamic glioma Additional Diagnostic Considerations: - Hypothalamic hamartoma - Rathke cleft cyst Craniopharyngioma Most common suprasellar mass in children Two variants: Adamantinomatous (peak age 5-15) Papillary (age > 50) Pediatric variant presents as multi-cystic mass with calcifications (90%) Cystic contents may be T1 hyperintense (proteinaceous) Calcifications hyperdense on CT & variable on T2 MRI Diagnosis: Optic pathway glioma 29 30 5
Craniopharyngioma Craniopharyngioma 9-yr-old boy with cystic and solid suprasellar mass Some cystic components T1 hyperintense Solid components and septations enhance 11-yr-old boy with headaches CT shows a calcified sellar/suprasellar mass 31 32 Germ Cell Tumor GCTs most common in pediatric population Typically midline Frequently in pineal & suprasellar regions Germinomas are most common subtype Follow gray matter signal intensity Homogeneously enhance May be circumscribed or infiltrative Often seed CSF Teratomas more heterogeneous with macroscopic fat Dermoid cysts may have fat-fluid levels Germ Cell Tumor 14-yr-old boy with suprasellar germinoma T1 post contrast images show a homogeneously enhancing suprasellar mass 33 34 Germ Cell Tumor Sagittal T1 images in a patient with a germinoma show: Infiltrative sellar/suprasellar mass- isointense to gray matter Homogeneous enhancement Obstructive hydrocephalus Optic pathway/hypothalamic Glioma Low grade neoplasms (WHO Grade 1) Occur between 5-15 years of age May be sporadic or associated with NF-1 Bilateral OPGs pathognomonic of NF-1 Intraorbital OPGs cause enlargement, elongation & buckling of optic nerve Non-NF-1 cases tend to involve optic chiasm & hypothalamus Typically larger and more mass-like than intraorbital OPGs OPGs are T2 hyperintense with variable enhancement 35 36 6
Optic pathway/hypothalamic Glioma MR images shows: FLAIR hyperintense suprasellar mass Heterogeneous enhancement along optic chiasm & hypothalamus Hypothalamic Hamartoma Hypothalamic hamartomas are rare, benign lesions Children present with gelastic seizures and/or precocious puberty On MRI, hamartomas are: Isointense to gray matter on T1 Iso- to hyperintense on T2 Hamartomas do not enhance If enhancement is seen, lesion likely a glioma 37 38 Hypothalamic Hamartoma MRI in a 3-yr-old boy with precocious puberty shows: T2 hyperintense mass centered within hypothalamus Isointense to gray matter on T1 with no enhancement Rathke Cleft Cyst Rathke cleft cysts are non-neoplastic lesions Typically intrasellar lesions Many will have suprasellar extension ~10-15% have curvilinear wall calcifications on CT Lesions with high mucin content are T1 hyperintense Non-enhancing intracystic nodule may be seen Nodule often T2 hypointense 39 40 Rathke Cleft Cyst Differential Diagnosis Review MR images show an intrasellar cystic lesion: T2 hyperintense cyst with a small hypointense nodule No enhancement on T1 post-contrast image - Craniopharyngioma - Germ cell tumor (GCT) - Optic pathway/hypothalamic glioma Additional Diagnostic Considerations: - Hypothalamic hamartoma - Rathke cleft cyst 41 42 7
Case #3 43 44 - Pineal cyst - Germ cell tumor (GCT) - Pineal cell tumor Additional Diagnostic Considerations: - Tectal plate glioma Diagnosis: Germinoma Pineal Cyst Pineal cysts are common & often incidental Cysts typically less than 15 mm in size Large cysts may rarely be symptomatic Simple cysts follow fluid signal & lack enhancement Internal cerebral veins typically displaced laterally Presence of the following should question diagnosis of a cyst and prompt follow-up: Calcification Nodularity Enhancement 45 46 Pineal Cyst Sagittal T1 & FLAIR MR images show: Sub-centimeter cyst in pineal gland No nodularity, calcification, or enhancement seen Germ Cell Tumor Germinomas are most common pineal gland neoplasms Typically occur in adolescents & young adult men Symptoms related to obstructive hydrocephalus or Parinaud syndrome (paralysis of upward gaze) Hyperdense on CT due to high cellularity May contain calcifications centrally (engulfs pineal calcifications) Intermediate to isointense on T1/T2 MR Lesions avidly enhance Evaluate entire CNS for dissemination 47 48 8
Germ Cell Tumor Adolescent boy with disseminated germinoma Sagittal T1 post-contrast image shows: Avidly enhancing pineal region mass Compression of the underlying tectal plate and cerebral aqueduct CNS dissemination with callosal & suprasellar mass Adolescent with a pineal germinoma Axial CT image reveals: Hyperdense pineal mass Central calcifications Germ Cell Tumor 49 50 Pineal Cell Tumor Pineoblastomas more malignant & occur children Peak incidence in 1 st decade Seeding of CSF is common Pineocytomas have peak incidence in 3 rd -4 th decades Generally less aggressive Both hyperdense on CT due to high cellularity Calcifications occur along periphery in exploded pattern Lesions ae intermediate on T1/T2 & avidly enhance Entire CNS must be imaged for drop metastases Pineal Cell Tumor 10-month-old boy with a pineoblastoma Sagittal CT reveals: Large lobulated mixed cystic and solid pineal mass Peripheral calcification Obstructive hydrocephalus 51 52 Pineal Cell Tumor MRI shows: Intermediate T2 signal mass with hemorrhagic fluid-fluid level Avid enhancement of solid components Hydrocephalus with transependymal flow of CSF Tectal Plate Glioma Tectal plate gliomas are low-grade neoplasms May cause hydrocephalus due to aqueductal stenosis When large, may simulate a pineal gland mass MR imaging shows: T2 hyperintensity Typically no enhancement Treatment geared towards CSF diversion 53 54 9
Tectal Plate Glioma MR images in a girl with tectal plate glioma show: Increased FLAIR signal & mass effect along tectal plate Tectal plate mass with no enhancement Hydrocephalus from aqueductal stenosis Differential Diagnosis Review - Pineal cyst - Germ cell tumor (GCT) - Pineal cell tumor Additional Diagnostic Considerations: - Tectal plate glioma 55 56 Case #4 57 58 - Medulloblastoma - Juvenile pilocytic astrocytoma (JPA) - Ependymoma Additional Diagnostic Consideration: - Brainstem glioma - Atypical teratoid rhabdoid tumor (rare) Diagnosis: Ependymoma Medulloblastoma High grade PNET (WHO grade IV) Most common posterior fossa tumor in children Peak incidence in first decade Typically midline Arises from superior medullary velum (roof of 4 th ventricle) Hyperdense (90%) +/- DWI due to high cellular content Calcification in ~20% of cases T1 hypo- / T2W iso- to hyperintense Heterogeneous enhancement Drop metastases common (1/3 of cases) Image entire neuroaxis prior to surgical intervention 59 60 10
Medulloblastoma Medulloblastoma Young child with HA, N/V Axial CT reveals: Hyperdense midline posterior fossa mass Obstructive hydrocephalus O Brien WT. JAOCR 2013: 2(3): 2-12. MRI in same child shows: T2 hyperintensity Heterogeneous but avid enhancement Restricted diffusion (dark on ADC [not shown]) O Brien WT. JAOCR 2013: 2(3): 2-12. 61 62 Medulloblastoma Post-contrast T1 MR images show: CSF metastases along surface of cerebellum, brainstem, & distal cord/conus Juvenile Pilocytic Astrocytoma JPA is a low grade (WHO grade I) astrocytoma Second most common posterior fossa tumor in children Peak incidence 5-15 years of age May occur sporadically or with NF1 Arises from the cerebellar hemisphere (off-midline) Presents as a cystic mass with enhancing mural nodule Enhancement along cyst wall suggests tumor lining cyst O Brien WT. JAOCR 2013: 2(3): 2-12. 63 64 Juvenile Pilocytic Astrocytoma Axial MR images reveal: Mixed cystic and solid T2 hyperintense mass Avid enhancement of solid nodule Enhancement along cyst wall Ependymoma Peak age of onset in first decade Slow growing midline tumor Arises from the floor of fourth ventricle Characteristically squeezes thru 4th ventricle foramina Calcification seen in ~50% of cases Cystic change & hemorrhage less common Heterogeneous on T1/hyperintense on T2 Heterogeneous enhancement typically seen O Brien WT. JAOCR 2013: 2(3): 2-12. 65 66 11
Ependymoma MR images in a boy with an ependymoma show: Enhancing midline mass with extension thru foramen magnum Extension thru foramen of Luschka on left Brainstem Glioma Represents ~10-20% of pediatric brain tumors Commonly presents in 1 st & 2 nd decades Most often a diffuse, infiltrating pontine mass WHO grade II-III Imaging demonstrates: T1 hypo-/t2 hyperintense mass Variable enhancement Higher grade regions show restricted diffusion, increased enhancement, & increased perfusion Exophytic components engulf basilar or project into 4 th ventricle Prognosis is poor 67 68 Brainstem Glioma MR images in a child with DIPG show: Diffuse infiltrating FLAIR hyperintense mass Exophytic components anteriorly (engulf basilar) and posteriorly Peripheral mass-like enhancement with central necrosis Atypical Teratoid Rhabdoid Tumor Rare, aggressive embryonal tumor Composed of rhabdoid cells and PNET components Presents in first few years of life (key distinction) Majority located in posterior fossa Remainder supratentorial Imaging appearance identical to medulloblastoma: Hyperdense on CT Regions of restricted diffusion Subarachnoid seeding common at presentation Prognosis dismal (mean survival <6 months) 69 70 Atypical Teratoid Rhabdoid Tumor 2-yr-old girl with ATRT Axial CT shows: Hyperdense midline posterior fossa mass Vasogenic edema Obstructive hydrocephalus Differential Diagnosis Review - Medulloblastoma - Juvenile pilocytic astrocytoma (JPA) - Ependymoma Additional Diagnostic Consideration: - Brainstem glioma - Atypical teratoid rhabdoid tumor (rare) 71 72 12
Case #5 73 74 Posterior fossa CSF collection - Mega cisterna magna - Arachnoid cyst - Dandy-Walker variant Diagnosis: Arachnoid cyst Posterior fossa CSF collection Mega Cisterna Magna Mega cistern magna is a common normal variant CSF-filled cisterna magna is prominent Posterior fossa otherwise normal in size & morphology Typically no mass effect on subjacent parenchyma May see mild mass effect due to altered CSF flow Vessels & dural reflections seen within cisterna magna 75 76 Posterior fossa CSF collection Mega Cisterna Magna Posterior fossa CSF collection Arachnoid Cyst Developmental CSF-filled spaces (less often acquired) Majority supratentorial (middle cranial fossa) Common infratentorial locations incl CPA & cistern magna May cause hydrocephalus due to 4 th ventricle obstruction Follow CSF signal on all MR sequences Mass effect evident MR images show: Prominent posterior fossa CSF collection Dural reflections within CSF collection and not displaced 77 78 13
Posterior fossa CSF collection Arachnoid Cyst MR images demonstrate: Posterior fossa CSF collection Mass effect on cerebellum & 4 th ventricle Obstructive hydrocephalus Posterior fossa CSF collection Dandy-Walker Variant Developmental abnormality of vermis & 4th ventricle Malformation consists of: Enlarged posterior fossa Vermian agenesis or hypogenesis Posterior CSF collection communicating with dilated 4 th ventricle Malformation demonstrates torcular-lambdoid inversion Associated anomalies include: Corpus callosal agenesis/hypogenesis Neuronal migration abnormalities DW variant less severe 79 80 Posterior fossa CSF collection Dandy-Walker Malformation Posterior fossa CSF collection Differential Diagnosis Review - Mega cisterna magna - Arachnoid cyst - Dandy-Walker variant MR images in patient with DWM reveal: Inferior vermian hypoplasia Posterior fossa CSF collection in communication with 4 th vent Enlarged posterior fossa with torcular-lambdoid inversion 81 82 Case #6 83 84 14
Massive supratentorial CSF collection - Hydrocephalus - Hydranencephaly - Alobar holoprosencephaly Diagnosis: Hydranencephaly Massive supratentorial CSF collection Hydrocephalus Hydrocephalus may result from: Obstruction (aqueductal stenosis, mass) Overproduction (choroid plexus papilloma) Decreased resorption (bleed, infxn, villous immaturity) Results in macrocephaly in newborns (open sutures) Displaces & compresses parenchyma peripherally Look for thin mantle of cortex along inner table Falx typically present though may see pressure erosion Communicating hydrocephalus not as severe 85 86 Massive supratentorial CSF collection Hydrocephalus MR images in 2-wk-old girl with macrocephaly show: Massive hydrocephalus with erosion of falx Peripheral displacement of brain parenchyma Aqueductal stenosis Massive supratentorial CSF collection Hydranencephaly Refers to parenchymal liquefactive necrosis in anterior vascular distribution Results from some form of intrauterine insult Parenchyma supplied by posterior circulation spared Key findings include: Presence of the falx Intact posterior fossa & deep structures Absence of supratentorial cortical mantle Neonates present with macrocrania & neurologic function limited to the brainstem 87 88 Massive supratentorial CSF collection Hydranencephaly CT images in a 6-month-old boy reveal: Supratentorial CSF collection Intact deep/posterior structures with unfused thalami No cortical mantle Intact falx Massive supratentorial CSF collection Alobar Holoprosencephaly Holoprosencephaly is a spectrum of forebrain malformations Alobar is most severe form: Cerebral parenchyma flattened anteriorly & fused Thalami fused Large dorsal interhemispheric cyst (monoventricle) Anterior falx, corpus callosum, interhemispheric fissure, & Sylvian fissures absent Craniofacial abnormalities include hypotelorism, fused metopic suture, & cleft palate Semilobar & lobar variants are less severe forms 89 90 15
Massive supratentorial CSF collection Alobar Holoprosencephaly Massive supratentorial CSF collection Differential Diagnosis Review - Hydrocephalus - Hydranencephaly - Alobar holoprosencephaly MR images demonstrate: Interhemispheric cyst / monoventricle Fused parenchyma anteriorly Fused thalami Absent falx 91 92 Summary It is important to be able to recognize & describe pertinent imaging findings in the pediatric brain Organized gamut-based differentials are helpful in working through unknown pediatric brain cases Knowledge of key imaging features for each entity within a gamut will aid in reaching a reasonable & useful list of differentials Top 3 Differentials in Neuroradiology: A Case Review. New York: Thieme, 2015. Top 3 Differentials in Radiology: A Case Review. New York: Thieme, 2010. References 93 94 Suggested Readings The End! Banwell B, Shroff M, Ness JM, et al. MRI features of pediatric multiple sclerosis. Neurology 2007; 68 (supp 2): S46-53. Barkovich AJ, Kjos BO, Norman D, etal. Revised classification of posterior fossa cysts and cyst-like malformations based on the results of multiplanar MR imaging. AJR Am J Roentgen 1989; 153: 1289-1300. Cheon JE, Kim IO, Hwang YS, et al. Leukodystrophy in children: a pictorial review of MR imaging features. RadioGraphics 2002; 22: 461-76. Dublin AB, French BN. Diagnostic image evaluation of hydranencephaly and pictorially similar entities, with emphasis on computed tomography. Radiology 1980; 137: 81-91. Hershey BL. Suprasellar masses: diagnosis and differential diagnosis. Semin Ultrasound CT MR 1993; 14(3): 215-31. Marin SE, Callen DJA. Imaging appearance of monophasic acute disseminated encephalomyelitis. Neuroimag Clin N Am 2013; 23: 245-66. O Brien WT. Imaging of posterior fossa brain tumors in children. J Am Osteopath Coll Radiol 2013; 2(3): 2-12. Oh KY, Kennedy AM, Frias AE, et al. Fetal schizencephaly: pre- and postnatal imaging with a review of the clinical manifestations. RadioGraphics 2005; 25: 647-57. Poretti A, Meoded A, Huisman TAGM. Neuroimaging of pediatric posterior fossa tumors including review of the literature. J Magn Reson Imaging 2012; 35: 32-47. Smith AB, Rushing EJ, Smirniotopoulos JG. Lesions of the pineal region: radiologic-pathologic correlation. RadioGraphics 2010; 30: 2001-20. Ten Donkelaar HJ, Lammens M. Development of the human cerebellum and its disorders. Clin Perinatol 2009; 36(3): 513-30. 95 96 16