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Differential Diagnosis of Nervous System Disorders

A few naturally occurring substances reduce T1 relaxation times depending on the degree of substance concentration: methemoglobin, melanin, lipid, protein, and minerals.

  1. METHEMOGLOBIN
    Source: intracellular (early subacute phase = 3–7 days) + extracellular (late subacute phase = 8–31 days) methemoglobin
    1. Hemorrhagic infarct
    2. Intraparenchymal hematoma (eg, amyloid angiopathy)
    3. Diffuse axonal injury
    4. Subarachnoid hemorrhage
    5. Epidural hematoma
    6. Intraventricular hemorrhage
    7. Thrombus: arterial / venous
    8. Vascular malformation (eg, cavernous malformation)
    9. Hemorrhagic neoplasm
  2. MELANIN
    Source: paramagnetic effect of stable free radicals + metal scavenging effect of melanin binding to chelated metal (= metallomelanin)
    1. Metastatic melanoma
    2. Primary diffuse meningeal melanomatosis
    3. Melanocytoma
    4. Neurocutaneous melanosis
  3. LIPID
    Source: short T1 relaxation time of H+ nuclei within lipid molecules
    1. Intracranial lipoma
    2. Teratoma
    3. Dermoid cyst
    4. Lipomatous ependymoma
    5. Chemical meningitis from ruptured dermoid
  4. PROTEIN
    Source: high SI of protein + hydration layer effect
    1. Colloid cyst
    2. Rathke cleft cyst
    3. Ectopic posterior pituitary gland
  5. MINERAL DEPOSITION
    1. Calcium concentration <30%
    2. Manganese, copper, iron
    3. Cockayne syndrome
    4. Neurodegeneration with iron accumulation (eg, Hallervorden-Spatz disease)
    5. Hepatic encephalopathy
    6. Wilson disease
  6. OTHER
    1. Type I neurofibromatosis
    2. Cholesterol granuloma
    3. Craniopharyngioma
    4. Cortical laminar necrosis

Increased T1 Signal Intensity of Sellar Region

  1. normal condition
    1. Vasopressin storage
      Source: vasopressin–neurophysin II–copeptin macroprotein complex
      Site: posterior aspect of sella turcica immediately anterior to dorsum sellae
    2. Anterior pituitary lobe hyperactivity
      Source:↑ in intracellular protein concentration
      Cause: hypersecretion during first few weeks of life in newborn, pregnancy, postpartum period, lactation

      T1-Hyperintense Intracranial Lesions by Location

      LocationLesion
      Deep gray matter nucleiCockayne syndrome: lentiform, dentate nuclei
      Pantothenate-kinase-associated neurodegeneration: bilateral globus pallidus + substantia nigra
      Hypertensive hemorrhage: putamen, external capsule, thalamus
      Hepatic encephalopathy: bilateral globus pallidus + substantia nigra
      Hypoxic-ischemic injury: lateral thalamus, posterior putamen + hippocampus
      Fabry disease: pulvinar
      Fahr disease: basal ganglia, thalamus, dentate, centrum semiovale
      Hypoparathyroidism, pseudo~, pseudopseudo~: similar to Fahr disease
      Lead, cyanide, methanol: bilateral putamen
      NF2: bilateral globus pallidus + internal capsule
      Wilson disease: basal ganglia + thalami
      Nonketotic hyperglycemia: bilateral caudate nucleus + globus pallidus
      HIV infection: caudate nucleus + putamen
      Neurodegenerative Langerhans cell histiocytosis: putamen
      Cerebral hemi-sphereAmyloid angiopathy, hemorrhagic metastasis / tumor, lipomatous ependymoma, vascular malformation, hemorrhagic contusion, hemorrhagic infarct, cortical laminar necrosis
      MidlineDermoid cyst, teratoma, lipoma, osteolipoma, hypothalamic hamartoma, pituitary microhemorrhage + apoplexy, deep cerebral vein thrombosis
      Sellar / suprasellarall above + craniopharyngioma, Rathke cleft cyst, ectopic posterior pituitary, thrombosed COW aneurysm, Langerhans cell histiocytosis
      VentriclesIntraventricular hemorrhage, 3rd ventricular colloid cyst, ruptured dermoid cyst
      Dura materLipomatous meningioma, hemorrhagic metastasis, melanoma, venous sinus thrombosis
    3. Bone
      Source: marrow fat in elderly
      Site: nonpneumatized posterior sphenoid body, dorsum sellae, posterior clinoid process
    4. Magnetic susceptibility artifact
      Source: abrupt transition between air-filled bone + dense cortical bone
      Site: just above sellar floor
    5. Flow artifact
  2. LESION IN / NEAR SELLA TURCICA
    1. blood clot / hemorrhage
      1. Pituitary apoplexy
      2. Aneurysm
    2. lesion with high protein content
      1. Rathke cleft cyst
      2. Craniopharyngioma
      3. Mucocele
      4. Cholesterol granuloma
    3. lesion with high fat content
      1. Lipoma of floor of 3rd ventricle, infundibulum, adjacent cranial nn.
      2. Dermoid cyst
      3. Lipoblastic meningioma
    4. intratumoral calcifications depending on degree of mineralization
      1. Chordoma
      2. Cartilaginous tumor (chondroma, chondrosarcoma)
    5. others
      1. Pituitary abscess (very rare)
      2. Excess manganese
        • parenteral nutrition / chronic liver deficiency
        • bilateral hyperintense T1 signal in adenohypophysis + globus pallidus
      3. Melanoma
  3. POSTTHERAPEUTIC CONDITION
    1. postoperative
      1. Blood products
      2. Surgical packing: fat, gelatin sponge
      3. Metallic artifact
      4. Mucocele
    2. medical therapy
      1. Hemorrhage: bromocriptine
      2. Hyperactive residual adenophysis