Imaging and diagnostics Flashcards
What is McGregor’s line?
Hard palate to bottom of opisthion
What is Wackenheim’s line?
Clival canal line
What is McRae’s line?
Basion to Opisthion (FM)
What is Chamberlains Line?
Hard palate to opisthion
Name the contour lines of the spine
Anterior marginal line (AML)
posterior marginal line (PML)
spinolaminar line (SLL)
Posterior spinous line (PSL)
What is the Rule of Spence?
On AP or open-mouth odontoid X-ray, if the sum total overhang of both C1 lateral masses (so-called lateral mass displacement (LMD)) on C2 is ≥ 7 mm, the transverse atlantal ligament (TAL) is probably disrupted (when corrected for an 18% magnification factor, it has been suggested that the criteria be increased to ≥ 8.2 mm3 ).
What is a normal atlantodental interval? What does it suggest if increased?
2.5(female) - 3mm(male)
Suggests injury to Transverse atlantal ligament if increased
How many ossification centres does C1 have?
3
Usually 1 for body (appears in first year) and 1 for each neural arch (appears in 7th fetal week).
Body may have 2
How many ossification centres in C2 at birth?
4 (5 developmentally - but 2 ossification centres in dens fuse to become 1) as well as body and 2 x neural arch
What is a butterfly vertebra?
An uncommon congenital anomaly thought to arise from failure of fusion of the lateral halves of the VB due to persistent notochord tissue, producing a “butterfly” appearance on AP X-rays or coronal CT scan reconstructions. The involved VB is widened, and adjacent vertebrae may show a compensatory deformity as if to fill in some of the gap. May be associated with other spinal and rib malformations.17 On lateral views may simulate compression fracture. In severe cases, there may be significant kyphosis and/or scoliosis. Often asymptomatic, requiring no treatment. May be associated with lipomyelomeningocele.
What is the difference between Towne’s view and Waters?
Towne’s view angled down 45deg to view occiput, Water’s view perpendicular to clivus (45 deg angled up).
What are the normal measurements of the sella turcica?
Length 16mm-5mm (av 10mm)
Depth 12mm-4mm (av 8mm)
What does a J-shaped sella suggest?
Optic pathway glioma or can be congenital (Hurler’s syndrome - MPS type 1)
What is the difference between type 1 and 2 Basilar invagination?
Chiari malformation associated with Type 2, which is less likely to be reduced, associated with small post fossa volume and dens only goes above Chamberlains line. FMD appropriate treatment for type 2 where as removal of PEG and posterior fusion recommended for type 1 (no reference for this!)
What conditions are associated with a basilar invagination?
Congenital
- Downs
- Chiari
- Klippel Feil
Acquired conditions
- RA
- post traumatic
Bone softening diseases (pagets, Osteogenesis imperfecta, osteomalacia, rickets, hyperparathyroidism)
