X ray findings of TB Spine vs Bony Metastasize

Bony metastasize

-Often involve pedicle as well as wall of vertebral body
-Lytic lesion
-No true destruction of disc space


TB Spine

-Destruction of intervetebral disc and adjacent vertebral body
-Early course there will be narrowing of disc space + erosion of adjoining surface of vertebral body.
-Later, bone destruction may lead to collapse of the vertebral body, forming the gibbus (sharp angulations)
-Paravetebral abscess may present
-Bony fusion of vertebral bodies across obliterated disc space when healing occurs.

Reference:

1.Peter Armstrong, Martin Wastie & Andrea Rockall, “Diagnostic Imaging 5th edition”, Blackwell Publishing, 2004.

Hounsfield Unit

Sir Godfrey Hounsfield

The Hounsfield unit (HU) scale is a linear transformation of the original linear attenuation coefficient measurement in one in which the radiodensity of distilled water at standard pressure and temperature (STP) is defined as zero Hounsfield units (HU), while the radiodensity of air at STP is defined as -1000 HU.

For a material X with linear attenuation coefficient μX, the corresponding HU value is therefore given by where is the linear attenuation coefficient of water.

Thus, a change of one Hounsfield unit (HU) represents a change of 0.1% of the attenuation coefficient of water since the attenuation coefficient of air is nearly zero.

It is the definition for CT scanners that are calibrated with reference to water.



+1000 = Bone
+80 = Liver
+55 = Muscle
0 = water (cyst)
-1000 = Air

value below is slightly different. taken from this website

Bone	1000
Liver	40 - 60
White matter	~20-30 HU
Grey matter	~37-45 HU
Blood	40
Muscle	10 - 40
Kidney	30
Cerebrospinal fluid	15
Water	0
Fat	-50 - -100
Air	-1000

Describing fracture on X- Ray

1) Identification data (Name, gender, date taken, etc)

2) Pediatrics or adult (remember that baby has LOT OF BONES and NOT YET DEVELOP WELL)

3) View

a) The rule of two (Common is AP and Lateral)

b) Shoulder (AP, Y view, axillary)

c) Elbow (AP, Lateral, Internal& external oblique)

d) Wrist and hand (PA, Lateral, PA oblique)

e) Hip (AP, Lateral, AP Pelvis)

f) Knee (AP, lateral, skyline)

g) Ankle and foot (AP, Lateral, Oblique)

4) Site of X ray taken (eg: left knee joint, pelvis, Right forearm, etc)

5) Extra articular VS intra articular

6) Anatomical description of fracture

a) Type (simple, spiral, comminuted, transverse, greenstick, oblique, compound)

b) Comminution (non comminuted, mildly comminuted, severely comminuted)

c) Location (Name of the bone and location eg; distal right radial shaft, proximal 1/3 left humeral shaft)

d) Displacement (angulation, translation, shortening)

7) Any soft tissue involvement (swelling, gas under tissue)

8) Any foreign body (metal appears more opaque than bone, wood piece)