T1 Hyperintense Parenchymal Lesion(s)



T1 Hyperintense Parenchymal Lesion(s)


Anne G. Osborn, MD, FACR



DIFFERENTIAL DIAGNOSIS


Common



  • Mineral Deposition



    • Physiologic Calcification


    • Trace Element Deposition


  • MR Artifacts, Flow-Related


  • Intracerebral Hematoma (Late Subacute)


Less Common



  • Multiple Sclerosis


  • Metastases


  • Cerebral Amyloid Disease


  • Cavernous Malformation


  • Neurocutaneous Syndromes



    • Neurofibromatosis Type 1


    • Tuberous Sclerosis Complex


Rare but Important



  • Hypoxic-Ischemic Injury



    • HIE, NOS


    • Cerebral Infarction, Chronic


    • Cortical Laminar Necrosis


  • Acute Hypertensive Encephalopathy, PRES


  • Encephalitis



    • Herpes Encephalitis


    • Encephalitis (Miscellaneous)


  • Melanin Deposition



    • Melanoma Metastases


    • Meningeal Melanocytoma


    • Neurocutaneous Melanosis


  • Thrombotic Microangiopathies (HUS/TTP)


  • Fabry Disease


  • Fahr Disease


  • Fungal Diseases


  • Kernicterus


  • Leukemia


  • Dermoid Cyst (Ruptured)


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Short T1 on T1WI scan related to



    • Deposition of paramagnetic substances



      • Methemoglobin


      • Non-heme iron (e.g., ferritin)


    • Mineral deposition (e.g., calcium)



      • Calcification


      • Trace element deposition


    • Fat


    • Melanin


    • Proteinaceous materials


    • Increased lipid or cholesterol content


    • Melanin


    • Hypoxic-ischemic injury as well as nonhemorrhagic cerebral infarction


    • Remyelination/hypermyelination


    • Macrophage infiltration



      • Phagocytosis, paramagnetic free radicals


Helpful Clues for Common Diagnoses



  • Mineral Deposition



    • Bilateral, symmetrical


    • Basal ganglia most common location


  • MR Artifacts, Flow-Related



    • Look for propagation across image


    • Entry phenomena, phase artifact


  • Intracerebral Hematoma (Late Subacute)



    • Age-related causes



      • Young patients: Vascular malformation, neurocutaneous syndrome, blood dyscrasias, metabolic disorders


      • Elderly patients: Hypertension (basal ganglionic), amyloid (lobar, peripheral) hemorrhagic metastases


    • Check history



      • Trauma: Hemorrhagic DAI, contusions (typical locations)


      • Infection: Abscess, encephalitis


Helpful Clues for Less Common Diagnoses



  • Multiple Sclerosis



    • Look for hazy “rim” or “ghost” of T1 shortening around chronic lesions


  • Metastases



    • Hemorrhagic (renal cell, melanoma)


    • Melanoma (hemorrhagic vs. intrinsic T1 shortening from melanin)


  • Cerebral Amyloid Disease



    • Lobar, cortical/subcortical


    • Hemorrhages of different ages


  • Cavernous Malformation



    • Can be single or multiple, large or small, homogeneous or “popcorn” appearance


  • Neurocutaneous Syndromes



    • Neurofibromatosis Type 1



      • Basal ganglia, internal capsules


      • Symmetric T1 shortening due to myelin clumping or microscopic calcification


    • Tuberous Sclerosis Complex



      • Subependymal nodules often hyperintense on noncontrast T1WI


      • Cortical tubers hyperintense early (unmyelinated brain), variable later


      • Streaky or wedge-shaped white matter hyperintensities (unmyelinated brain)



      • Taylor-type cortical dysplasias may initially be hyperintense (unmyelinated brain)


Helpful Clues for Rare Diagnoses



  • Hypoxic-Ischemic Lesions



    • Hemorrhagic transformation in ischemic stroke (cortex > basal ganglia)


    • Hypotension → cortical laminar necrosis (gyriform T1 shortening)


    • Heat stroke → thermal injury, T1 shortening in external capsules, paraventricular thalami, cerebellum


  • Acute Hypertensive Encephalopathy, PRES



    • Gross hemorrhage rare; petechial uncommon


    • Typically occipital lobes


  • Encephalitis



    • Herpes encephalitis



      • Hemorrhagic cortical necrosis


      • “Sequential bilaterality” in temporal lobes highly suggestive


      • May also involve cingulate gyrus, subfrontal region


    • Other: West Nile may cause basal ganglionic necrosis, T1 shortening

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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on T1 Hyperintense Parenchymal Lesion(s)

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