Multiple Hyperdense Parenchymal Lesions

Anne G. Osborn, MD, FACR

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Hyperdense parenchymal lesions
- ↑ Attenuation compared to normal brain
Caused by
- Clotted blood, most common
- Nonhemorrhagic hypercellular mass (electron dense), less common
- Calcification (excluded from this differential diagnosis)

Helpful Clues for Common Diagnoses

Cerebral Contusion
- Peripheral (cortex) > deep lesions
- Anteroinferior frontal, temporal lobes most common sites
- Patchy superficial hemorrhages ± low density edema
- Focal traumatic subarachnoid hemorrhage often associated
Diffuse Axonal Injury (DAI)
- Punctate/linear hemorrhages at gray-white junction most common
- Other: Corpus callosum, deep gray nuclei, midbrain/brainstem
- T2* scan (GRE/SWI) helpful
Hypertensive Intracranial Hemorrhage
- Solitary hematoma > patchy/multifocal hemorrhage
- Deep > superficial lesions
  - Nearly 2/3 striatocapsular
  - Thalamus 15-25%
- Look for multifocal “microbleeds” (1-5%), best seen on MR with GRE/SWI sequence
  - Basal ganglia, cerebellum (vs. cortical, peripheral in amyloid)
Cerebral Amyloid Disease
- Causes 15-20% of primary nontraumatic intracranial hemorrhage in older patients
- Classic = lobar hemorrhages of different ages
- Most common manifestation actually “microbleeds”
  - Do T2* (GRE or SWI) scan to detect
Metastases, Parenchymal
- Electron dense (hypercellular or hemorrhagic)
- Some enhancement usually present
Cavernous Malformations
- Multiple (familial) lesions
- NECT often normal unless acute intralesional hemorrhage
- Iso-/hyperdense ± Ca++
- Mass effect absent unless hemorrhage
- Do MR with T2* (GRE or SWI) for optimal imaging

Helpful Clues for Less Common Diagnoses

Cerebral Infarction, Subacute
- Hemorrhagic transformation
  - Typically 2-3 days after ischemic infarct
  - Patchy petechial hemorrhages in cortex, basal ganglia
Thrombosis, Cortical Venous
- With or without dural sinus thrombosis
- Patchy cortical/subcortical petechial hemorrhages
Acute Hypertensive Encephalopathy, PRES
- Most common: Patchy hypodense cortical/subcortical foci
  - Occipital lobes > basal ganglia > brainstem, cerebellum
- Less common: Petechial hemorrhages (gross hematomas rare)
Anticoagulation Complications
- Mixed density hemorrhages
- Fluid-fluid levels, unclotted blood
Glioblastoma Multiforme
- Necrosis, hemorrhage common
  - Low density center, thick irregular high density hypercellular rim
- Multifocal GBM, “butterfly” GBM of corpus callosum
  - Both can appear to have separate hyperdense regions
  - Can be either hemorrhage or hypercellular regions
Lymphoma, Primary CNS
- Iso-/hyperdense lesions in corpus callosum, basal ganglia, periventricular WM
- Frank hemorrhage? Suspect HIV/AIDS
Tuberous Sclerosis Complex
- 98% have Ca++ subependymal nodules
- Some cortical, subcortical tubers calcify
- Occasional noncalcified cortical, subcortical hyperdensities seen

Helpful Clues for Rare Diagnoses

Tuberculomas
- Meningitis > parenchymal lesions
- Mildly hyperdense (rim > solid) ± edema
- Healed granulomas may calcify
Neurosarcoid
- Infiltrates along perivascular spaces → parenchymal mass
- May cause focal patchy hyperdense mass(es)
Leukemia
- Most parenchymal hyperdensities are hemorrhages
- Hypercellular parenchymal masses (chloromas) < extra-axial tumor
Thrombotic Microangiopathies (HUS/TTP)
- Thrombocytopenia, intravascular hemolysis characteristic of 3 disorders
  - Malignant hypertension (often with HUS)
  - Disseminated intravascular coagulation (DIC)
  - Thrombocytopenic thrombotic purpura (TTP)
- Patchy petechial hemorrhages, predominately cortical
Thrombolysis Complications
- 10-15% hemorrhage
  - Petechial > gross lobar
- Post-procedural T1 C+ MR may predict hemorrhagic transformation (HT)
  - If present, risk of HT ↑
Parasites, Miscellaneous
- Cysts > hyperdensities
- Consider travel history, especially in endemic area
- Beware: Conglomerate parasitic masses can mimic brain tumor!
Acute Hemorrhagic Leukoencephalopathy
- Fulminant variant of ADEM
- Hyperintensities in/along perivascular spaces
- Microhemorrhages > gross lesions
- CT, MR may not show hemorrhage