KEY FACTS Terminology Excessive accumulation of intraspinal fat causing cord compression and neurologic deficits Imaging Thoracic spine: 58-61% T6-T8, dorsal to spinal cord Epidural fat ≥ 7 mm thick Lumbar spine: 39-42% L4-L5, surrounding thecal sac Y-shaped configuration to lumbar thecal sac on axial imaging Mass effect on thecal sac and nerve roots Follows fat signal intensity on all sequences Fat suppression to confirm adipose tissue,…

KEY FACTS Terminology Dilatation of arachnoid and dura of spinal posterior nerve root sheath, containing nerve fibers a.k.a. Tarlov cyst Imaging Occur anywhere along spine Most common in lower lumbar spine and sacrum S2 and S3 nerve roots most commonly involved Thin-walled cyst mass Contents follow cerebrospinal fluid (CSF) density/signal intensity No enhancement ± neural foraminal widening (bone remodeling) Top Differential Diagnoses Facet synovial cyst Nerve…

KEY FACTS Terminology Cerebrospinal fluid (CSF) flow-related phenomenon due to time of flight (TOF) effects and turbulent flow Imaging Location: Intrathecal, subarachnoid space Most prominent in cervical and thoracic spine Low or high signal intensity Ill-defined margins Top Differential Diagnoses Vascular malformation, type I dural arteriovenous fistula Vascular malformation, type IV arteriovenous fistula CSF drop metastases Clinical Issues Time of flight effects Dark CSF signal Positive…

KEY FACTS Terminology Uncommon complication following intrathecal chemotherapy Transient or permanent paraplegia Initially described following intrathecal methotrexate (MTX) in pediatric acute lymphoblastic leukemia patients Imaging Smooth linear enhancement of conus pia, anterior cauda equina nerve roots Unenhanced T1W, T2W images normal Top Differential Diagnoses Guillain-Barré syndrome Cerebrospinal fluid (CSF) disseminated metastases Postradiation radiculopathy Pathology Intrathecal MTX, arabinoside (Ara-C) standard prophylaxis, and treatment agents for pediatric CNS…

KEY FACTS Terminology Transformation of cellular vertebral marrow into fatty marrow following therapeutic irradiation Imaging Sharp demarcation between irradiated and untreated marrow (margins of radiation port) Corresponds to site of irradiation and extent of radiation field Marrow signal intensity within radiotherapy portal similar to subcutaneous fat on T1WI May demonstrate associated compression fractures Top Differential Diagnoses Normal fatty marrow Vertebral hemangioma Pathology Marrow changes on MR…

KEY FACTS Terminology Chronic progressive radiation myelitis Delayed radiation myelopathy Imaging Spindle-shaped cord swelling with irregular, focal rind of enhancement (early) Focal cord atrophy (late) Clinical signs may reflect longer segment of damage than demonstrated on MR Top Differential Diagnoses Transverse myelitis Multiple sclerosis Spinal cord infarct Astrocytoma Syrinx Pathology Demyelination, lipid-laden microphages, swollen astrocytes, endothelial damage, necrosis, local Ca++ deposition, hyalinosis of intramedullary vessel walls…

KEY FACTS Terminology Metastatic lesion from primary carcinoma in another organ (including brain) Imaging Focal, enhancing cord lesion(s) with extensive edema Typically small (< 1.5 cm) T1WI: Enlarged cord T2WI/PD/STIR: Focal high signal represents diffuse edema Rarely syrinx T1WI C+: Focal enhancement T2* GRE: Hypointensity due to hemorrhagic components Top Differential Diagnoses Demyelinating disease Multiple sclerosis Acute disseminated encephalomyelitis Primary cord tumor Inflammatory granuloma Tuberculosis Sarcoidosis…

KEY FACTS Terminology Slow-growing glioma arising from ependymal cells of conus, filum terminale, cauda equina Imaging Usually spans 2-4 vertebral segments May fill entire lumbosacral thecal sac Ovoid, lobular, sausage-shaped CT/radiographs ± osseous canal expansion, thinned pedicles, vertebral scalloping May enlarge, extend through neural foramina T1WI: Isointense→ hyperintense to cord T2WI: Almost always hyperintense to cord Hypointensity at tumor margin = hemosiderin T1WI C+: Intense enhancement…

KEY FACTS Terminology Neoplasm arising from ependyma lining spinal cord central canal Imaging Circumscribed, enhancing hemorrhagic cord mass with surrounding edema Associated cysts common Cervical > thoracic > conus T1WI: Isointense or slightly hypointense to spinal cord T2WI: Hyperintense relative to spinal cord Cap sign: Hemosiderin at cranial or caudal margin Most tumors enhance Top Differential Diagnoses Astrocytoma Hemangioblastoma Demyelinating disease Idiopathic transverse myelitis Pathology Arises…

KEY FACTS Terminology Primary neoplasm of astrocytic origin within spinal cord Imaging Fusiform expansion of cord with enhancing component of variable morphology Almost always enhances Cervical > thoracic Usually ≤ 4 segments Occasionally multisegmental, even holocord (more common with pilocytic astrocytoma) ± cyst/syrinx (fluid slightly T1 hyperintense to cerebrospinal fluid) Hyperintense on proton density and T2WI MR Myelopathy should be evaluated with contrast-enhanced MR Top Differential…

KEY FACTS Terminology Spread of malignant tumor through subarachnoid spaces of brain and spinal cord Imaging Smooth or nodular enhancement along cord, cauda equina Located at any point along CSF pathway 4 basic patterns Solitary focal mass at bottom of thecal sac or along cord surface Diffuse, thin, sheet-like coating of cord/roots (“carcinomatous meningitis”) Rope-like thickening of cauda equina Multifocal discrete nodules along cord/roots Top Differential…

KEY FACTS Terminology Neoplasm containing Schwann cells, fibroblasts, myxoid material, and peripheral nerve fibers Imaging Locations: Extradural/paraspinal, intradural extramedullary Variable involvement of spinal root, neural plexus, peripheral nerve, or end organs Different neurofibroma morphologies Localized Diffuse Plexiform Size varies from small circumscribed mass to large plexiform neurofibroma (NF) involving multiple body compartments Plexiform neurofibroma pathognomonic for neurofibromatosis type 1 (NF1) Target sign on T2WI suggestive but…

KEY FACTS Terminology Typical (“benign”) meningioma = WHO grade I Imaging Location Supratentorial (90%) – Parasagittal/convexity (45%), sphenoid (15-20%) – Olfactory groove (5-10%), parasellar (5-10%) Infratentorial (8-10%) (CPA most common site) Multiple meningiomas in 1-9% of cases General features Extraaxial mass with broad-based dural attachment > 90% enhance homogeneously, intensely CT Hyper- (70-75%), iso- (25%), hypodense (1-5%) Hyperostosis, irregular cortex, ↑ vascular markings Ca++ (20-25%) (diffuse,…

KEY FACTS Terminology Neurinoma, neurilemmoma (outdated terms) Neoplasm of nerve sheath (Schwann cells) Imaging 70-75% intradural extramedullary Most common intradural extramedullary mass 15% completely extradural 15% transforaminal, “dumbbell” masses Size varies from small intradural mass to large intraspinal or paravertebral mass (“giant schwannoma”) extending ≥ 2 vertebral segments Bone remodeling due to large intraspinal or intraforaminal tumor common Cystic change common Calcifications, hemorrhage are rare Uniform,…

KEY FACTS Terminology Multifocal malignant proliferation of monoclonal plasma cells within bone marrow Imaging Skeletal survey is initial diagnostic imaging evaluation Diffuse osteopenia and multiple lytic lesions NECT (bone algorithm) Multifocal lytic lesions Vertebral destruction and fractures MR patterns Normal Focal marrow involvement Diffuse marrow involvement Variegated pattern (micronodular, “salt and pepper”) Compression fractures with variable central canal narrowing FDG PET Identifies active multiple myeloma; useful…

KEY FACTS Terminology Solitary monoclonal plasma cell tumor of bone or soft tissue Diagnosis of solitary bone plasmacytoma (SBP) requires Solitary lesion, biopsy showing plasma cells Negative skeletal survey, negative MR spine, pelvis, proximal femora/humeri Negative clonal cells in marrow aspirate No anemia, hypercalcemia, or renal involvement suggesting systemic myeloma Imaging Axial skeleton > extremities Thoracic vertebral body most common site Radiographs/CT Lytic, multicystic-appearing lesion ±…

KEY FACTS Terminology Extramedullary leukemic tumors Synonyms: Granulocytic sarcoma, chloroma Imaging Best diagnostic clue: Homogeneous enhancing tumor(s) in patients with known or suspected myeloproliferative disorder Meningeal (dural-based or pial) > intraparenchymal lesions NECT: Hyperdense CECT: Moderate uniform enhancement MR T2/FLAIR iso- to hypointense Restricted diffusion on DWI Top Differential Diagnoses Metastatic neuroblastoma Meningioma Extraaxial hematoma Extramedullary hematopoiesis Langerhans cell histiocytosis Pathology CNS leukemia presents in 3…

KEY FACTS Terminology Lymphoreticular neoplasms with myriad of specific diseases and cellular differentiation Imaging Multiple types with variable imaging manifestations Epidural lymphoma: Thoracic > lumbar > cervical Enhancing epidural mass ± vertebral involvement Osseous lymphoma: Long bones > spine Bone destruction (“ivory” vertebra, rare), vertebra plana Lymphomatous leptomeningitis Smooth/nodular pial enhancement Intramedullary lymphoma: Cervical > thoracic > lumbar Poorly defined, enhancing mass Secondary > primary involvement…

KEY FACTS Terminology Most common benign neoplasm of spine Vascular/fatty marrow with fewer but thicker trabeculae Imaging CT: Well-circumscribed, hypodense lesion with coarse vertical trabeculae (corduroy appearance on sagittal, “white polka dots” on axial CT) MR: Circumscribed lesion, hyperintense on both T1 and T2WI, with hypointense vertical striations Usually intraosseous, may have epidural component Atypical hemangiomas may have reduced T1 signal due to paucity of fat…

KEY FACTS Terminology Spread of primary tumor to spine, where bone destruction exceeds bone production Imaging Multiple osteolytic lesions in spine Compression fracture with bowing of posterior cortex, osteolysis extending into neural arch, extraosseous soft tissue Lesion distribution proportional to red marrow (lumbar > thoracic > cervical) Radiography requires 50-70% bone destruction and tumor size > 1 cm for detection Bone scan can give false-negatives with…