Unit 1 Flashcards
Conventional Tomography
Used to evaluate structures or abnormalities.
Blurs out objects above and below plane of interest
Fulcrum/pivot is level of interest
Computed Tomography (CT, CAT)
Most images obtained in axial plane
Excellent spatial relationships
Based on tissue attenuation
Components - Gantry houses tube and sensors; table; x-ray generator; data processor
Cross-sectional cuts 0.2-1.3cm
Tissues expressed in Hounsfield Units (Hu)
Bone Scintigraphy
Radionuclide bone scanning (skeleton, heart, lung, kidneys, brain)
Organ/system uptake of Technetium-99m methylene diphosphate (99mTc-MDP) is MC radioactive agent
Extremely sensitive; lacks specificity
Look for “hot spots”
Magnetic Resonance Imaging (MRI)
Based on re-emission of an absorbed radiofrequency while pt is in strong magnetic field
Spin echo T1 & T2 images, STIR, FLAIR, FSE, GRE are ex. Of pulse sequences
T1 is fat sequence; T2 is water sequence
Categorical Approach to Bone Disease Pneumonic: CATBITES
Congenital Arthritis Trauma Blood Infection Tumor Endocrine, nutritional, metabolic Soft tissue
Number of lesions: Solitary lesion
Simple Bone Cyst (SBC)
Osteosarcoma
Number of Lesions: Multiple Lesions (Multiplicity)
Metastatic Disease
Multiple Myeloma
HME (Hereditary Multiple Exostosis)
Enchondromatosis
Monostotic
Single bone
Suggests tumor or infection
Polyostotic
Multiple bones
Osteoma (location)
Frontal sinus (skull; common location)
Hemangioma (location)
Spine (MC benign tumor of spine)
Bone marrow tumors
Myeloma
Lymphoma
Chordoma (location)
Cranial and caudal cord limits
Remnants of primitive notochord
Most tumors are radiolucent
Diaphyseal tumors
Ewing’s Sarcoma
Multiple Myeloma
Diametaphyseal tumors
NOF (Non-Ossifying Fibroma)
Metaphyseal tumors
Osteosarcoma (malignant)
Simple Bone Cyst (SBC; benign)
Epiphyseal tumors
Chondroblastoma
Metaphyseal-Epiphyseal Tumors
Giant-Cell tumor
Axial orientation: Central
Centrally located on both AP and Lat Views
Ex: SBC, Chondrosarcoma, Fibrous Dysplasia
Axial orientation: Eccentric
Still medullary in location, but not centered in 1 view
Ex: Giant Cell, Chondromyxoid fibroma, ABC (Aneurysmal Bone Cyst)
Axial orientation: Cortical
Overlies the cortex on at least one view; may see cortical thickening, expansion, destruction, periosteal response
Ex: Osteoid osteoma, FCD (Fibrous Cortical Defect)
Axial orientation: Parosteal
Close approximation but definite separation from majority of underlying bone; notable lesion in soft tissue w/ little bony abnormality
Ex: Juxtacortical chondroma, parosteal osteosarcoma
Axial orientation: Extraosseous (Soft Tissue)
Distant location from bone or adjacent cleft separates mass from cortical surface
Ex: Myositis ossificans (aka Heterotopic Bone Formation)
Size and shape of lesion: malignant
Most malignant or aggressive lesions tend to be large at time of discovery ( >6cm). Exceptions: Fibrous dysplasia; SBC, ABC, Giant-Cell.
Slow-growing lesions usually progress along long-axis of bone. Fast growing tumors are often pleomorphic or round-ish in shape.
Behavior of Lesion
Bone lesions may be osteolytic, osteoblastic, or mixed.
Majority of bone tumors are osteolytic.
~30-50% of cancellous bone must be destroyed to see on x-ray.
Three patterns of destruction: geographic; moth-eaten; permeative
Pattern of Bone Destruction: Geographic
Least aggressive pattern.
Circumscribed & uniformly lytic
Usually solitary >1cm
Usually sharply marginated
May be trabeculated (soap bubble appearance)
Indicative of slow-growing lesion (usually benign)
Ex: ABC (Aneurysmal Bone Cyst)
Pattern of Bone Destruction: Moth-Eaten
Multiple small or moderate sized lucencies that may or may not be poorly marginated (2-5cm) “Punched-out” appearance Longer ZOT (zone of transition) Indicative of aggressive lesions Metastasis Ex: NHL (Non-Hodgkin’s Lymphoma)
Pattern of Bone Destruction: Permeative
Multiple holes <1mm in size
Poorly demarcated, not easily separated from normal bone
Areas of destruction my coalesce
Wide ZOT
Indicative of very aggressive lesion
Ex: NHL (Non-Hodgkins Lymphoma); Multiple Myeloma
Margination
Refers to margin of lesion
Ex: Imperceptible, sharp, wide, narrow
Sharp Margination
AKA: Narrow ZOT; definite
Line of demarcation between lesion and normal bone is well-defined; may be sclerotic
Indicative of slow-growing process
Ex: Fibrous dysplasia; SBC
Imperceptible Margination
AKA: Wide ZOT; ill-defined; hazy
Gradation between lesion and normal bone occurs gradually with no distinct line of demarcation
Indicated aggressive or malignant process
Ex: Metastasis; Infections
Cortical Integrity: Appearances
Key factor in assessing growth rate
Cortical Expansion Cortical Erosion Cortical Thinning Cortical Destruction Cortical Saucerization Cortical Thickening
Cortical Expansion
Result of progressive endosteal erosion together with periosteal bone formation.
Bulging of an intact cortex; slow continued growth, generally benign
Ex: Giant-Cell (when it extends to articular surface); ABC
Cortical Erosion
Slow growing medullary tumors with lobulated or scalloped appearance
Endosteal scalloping - cartilaginous and fibrous tumors, myeloma
Ex: Enchondroma; Chondrosarcoma
Cortical Destruction
Strong indicator of aggressive bone disease.
Easier to identify than destruction w/in medulla
May see moth-eaten permeative destruction
Periosteal response and/or soft tissue mass
Cortical Thinning
Thinning w/out loss of integrity, usually denotes slow growth
Ex: osteoporosis, tumors (localized)
Cortical Thickening
Thickening of cortex. May be localized
Ex: osteoid osteoma; stress fx; Paget Disease
Cortical Saucerization
Saucerized destruction of cortex
Ex: Ewing’s Sarcoma
Tumor Matrix Types: Osseous
Tumor New Bone
- New bone produced by osteogenic tumors
- fluffy, cloud-like appearance
- Ex: Osteosarcoma; calcification of osteoid
Reactive New Bone
- Body lays down new bone in response to stimulus
- Ex: Degenerative Sclerosis; metastasis
Tumor Matrix Types: Cartilage
Endochondral calcification of chondroid nodules.
Stippled, flocculent, arc or ring-like, popcorn-like, comma shaped
Ex: Chondrosarcoma, endochondroma, osteochondroma
Tumor Matrix Types: Fibrous
Radilucent or slightly hazy. Smoky, hazy, ground glass* due to calcification of osteoid.
Often difficult to identify
Ex: Fibrous dysplasia
Tumor Matrix Types: Fat
If intraosseous, it is hard to identify on plain-film
Periosteal Response
Bone forming irritants include: blood, pus neoplasm, edema, granulation tissue
New bone is formed by cambium layer; generally a 10-21 day latent period
Laminated Periosteal Response
AKA: Layered, onion-skin, lamellated
Alternating layers of radiopacity and lucency (may eventually form solid appearance). Cyclical variation in growth
Ex: Ewing’s Sarcoma, Osteosarcoma
Spiculated Periosteal Response
AKA: Perpendicular, brushed whiskers, hair-on-end, sunburst
Fine linear spiculations of new bone radiating from point source. Usually indicative of very aggressive bone tumors.
Ex: Osteosarcoma
Codman’s Triangle
AKA: Codman’s Angle, periosteal cuff, periosteal buttress
Periosteal new bone at peripheral lesion-cortex junction
Results from subperiosteal extension of lesion
