before we start in imaging modules , its types , benefits over each other
you should know the name of sections of imaging
coronal - frontal plane
horizontal -or axial , transverse plane
sagittal or longitudinal plane
median plane
parasagittal plane
a rapid comparison between ct and mri
ct over mri ?
ct better in head trauma , lower cost needed . fresh hemorrhage , speed needed , skull fracture , calcified lesion , claustrophobic - obese >300Ib patient , patient have pacemaker or metallic fragment in heart or eye
mri over ct ?
mri better in subtle area of tumor , infarction , demyelination , brainstem or cerebellar lesion , old hemorrhage , anatomical detail needed
*ct prone to shadowing artifact
*fast mri technique , when available is nearly as fast as ct
*large bore bariatric MRI scanners are now available for these types of pateint
terminology used in imaging :
ct(density) : increased attenuation (hyperdense) , decreased attenuation(hypodense)
mri(intensity) : increased signal intensity (hyperintensity appear bright) , decreased low signal intensity (appear dark)
US(echogenicity) : increased echogenicity (sonodense), decreased echogenicity (sonolucent)
nuclear medicine : increase tracer uptake , deceased tracer uptake
barium study : radioopaque , radiolucent
fracture vs sutures in ct brain
fracture : greater than 3mm in width , widest at center and narrow at end , runs through both outer and inner lamina of bone , hence appears darker , usually over tempo-parietal area , usually run in staight line , angular turns
suture : less than 2mm width , same width throughout , lighter on x ray compared with fracture lines , at specific anatomic location , not run in straight line , curvaceous turns
types of contrast media used in imaging
for gases(air , co2 ):
water soluble : urografin ultravist
non water soluble : barium , lipidol
in double contrast enema :
water soluble : iv use as : IVU , CT , ANGIO
non water soluble : oral/rectal only GIT techniques , fat soluble for HSG(hystrosalpingography)
benefits of special patient position in imaging over another :
lateral decubitus view of the abdomen : horizontal view - air fluid level will be visible , free air will rise over liver
supine abdomen : vertical - air fluid level not visible , free air will rise to undersurface of anterior abdominal wall and may not be visible until large amounts are present
upright chest : horizontal - pneumothorax if present will usually be visible at apex of lung , air fluid level (in cavities) will be visible
cross table lateral examination of knee :horizontal -fat fluid level (lipohemarthrosis) if present will be visible
supine examination of knee : vertical - fat fluid level won't be visible
