Periventricular T2/FLAIR Hyperintense Lesions

Troy Hutchins, MD

Karen L. Salzman, MD

DIFFERENTIAL DIAGNOSIS

Common

Aging Brain, Normal
Arteriolosclerosis
Multiple Sclerosis
ADEM
Diffuse Axonal Injury (DAI)
Metastases, Parenchymal

Less Common

Radiation and Chemotherapy
Periventricular Leukomalacia (PVL)
Lyme Disease
Vasculitis
Obstructive Hydrocephalus
Drug Abuse
CADASIL
Susac Syndrome

Rare but Important

Metachromatic Leukodystrophy (MLD)
X-Linked Adrenoleukodystrophy
Mucopolysaccharidoses
TORCH Infections

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Periventricular T2/FLAIR hyperintense lesions are often nonspecific, with significant overlap among etiologies
These questions help narrow differential
- How old is the patient?
- Volume loss vs. mass effect?
- Are there T2 * GRE “black dots”?
- Is there enhancement?
- Is the corpus callosum (CC) involved?
- Are the basal ganglia involved?

Helpful Clues for Common Diagnoses

Aging Brain, Normal
- Smooth, thin rim of periventricular hyperintensity, wide sulci, prominent ventricles
- Sparing of cortex, subcortical/deep white matter (WM) & basal ganglia (BG)
Arteriolosclerosis
- Patchy confluent & focal lesions; subcortical/deep WM & BG involved; ± cortical infarcts
- GRE: Associated “black dots” (overlap with chronic hypertension & amyloid)
Multiple Sclerosis
- Linear/ovoid callosal & perpendicular callososeptal lesions
  - Infratentorial (esp. brachium pontis, brainstem), optic nerve, spinal cord
- T1 MR: Hyperintense rim: Chronic plaque
- T1 C+ MR: Enhancement with active disease: Nodular > ring > semilunar
ADEM
- Lesions have less mass effect than expected for size; BG lesions common
- T1 C+ MR: Enhancement & appearance may mimic MS; often need f/u exam
- Clinical: Viral prodrome or recent vaccination; monophasic
Diffuse Axonal Injury (DAI)
- GRE: Multiple “black dots” at gray/white interface, CC, deep gray matter, brainstem
- Clinical: Trauma patient
Metastases, Parenchymal
- T1 C+ MR: Multiple enhancing masses at gray/white interface
- T2/FLAIR: Hyperintensity has mass effect (vasogenic edema)

Helpful Clues for Less Common Diagnoses

Radiation and Chemotherapy
- Numerous appearances based on injury
  - Periventricular leukoencephalopathy: Confluent T2 hyperintensity, spares subcortical U-fibers & CC
  - PRES: Symmetric posterior circulation subcortical/periventricular T2 hyperintensity
  - Radiation necrosis: Vasogenic edema surrounds irregular, enhancing lesion(s)
Periventricular Leukomalacia (PVL)
- Early: Periventricular cystic changes
- Late: Undulating ventricular borders, ventriculomegaly, WM volume loss
- Clinical: Preterm birth, spastic diplegia, visual & cognitive impairment
Lyme Disease
- T1 C+ MR: Multiple enhancing cranial nerves; CN7 common
- WM lesions may be identical to MS
- Clinical: Meningoencephalitis, ± history of skin rash (erythema migrans); higher prevalence in New England
Vasculitis
- Restricted diffusion in acute phase
- T2/FLAIR MR: Ranges from normal to patchy asymmetric hyperintensity in multiple small vessel territories
- DSA: Regions of alternating stenosis & dilatation primarily involving 2nd, 3rd order branches
Obstructive Hydrocephalus
- Periventricular “halos”: Fingers of CSF-like hyperintensity most pronounced at ventricular horns
- Ventricles dilated without sulcal widening or cortical volume loss
Drug Abuse
- Confluent periventricular WM; corticospinal tract & deep grey matter; often hemorrhagic
- Cerebellar involvement in absence of hypertension, characteristic of inhaled heroin (“chasing the dragon”)
- Can cause a vasculitis
CADASIL
- Subcortical lacunar infarcts & leukoencephalopathy in young adult
- Anterior temporal pole & external capsule lesions highly sensitive/specific
- Frontal lobe has highest lesion load
Susac Syndrome
- Central CC > callososeptal lesions
- WM lesions may be identical to MS
- Clinical triad: Encephalopathy, hearing loss, branch retinal artery occlusions

Helpful Clues for Rare Diagnoses

Metachromatic Leukodystrophy (MLD): Confluent “butterfly-shaped” cerebral hemispheric WM T2 hyperintensity
X-Linked Adrenoleukodystrophy: Enhancing peri-trigonal WM demyelination
Mucopolysaccharidoses: T2 hyperintensity surrounds dilated MPS-filled PVS
TORCH Infections: Variable WM T2 hyperintensity, ± calcification