Lymph node imaging is a useful technique, aiding the clinician in determining whether nodes are benign or malignant. Multiple modalities are used for the assessment and characterization of lymph nodes, each with its advantages and drawbacks.
Modalities
Ultrasound
size
number
shape
contour
-
internal architecture
echotexture
hilum
cystic/necrotic change
calcification
long to short axis ratio
vascularity
CT
size
shape
number
attenuation characteristics
enhancement with contrast
-
internal architecture
cystic/necrotic change
calcification
MRI
size
shape
number
cystic/necrotic change
Contrast MRI
enhancement kinetics
flow kinetics
blood volume
microvascular permeability
Diffusion-weighted imaging
pending
MR spectroscopy
adjunct technique
-
elevated choline levels have been associated with metastatic lymph nodes
active research into other metabolites is ongoing
MRI with USPIO
promising adjunct technique using ultra small superparamagnetic iron oxide particles
several patterns of uptake have been defined which are helpful in the characterization of lymph nodes
Interstitial administration of lymphangiographic contrast with MRI
a different approach which helps in the visualization of the lymphatic system on MRI
helps in identification of sentinel nodes and the course of draining lymphatics
Nuclear medicine
PET
has gained importance in identifying small nodal metastases
F-18-FDG is the main radiotracer used, and it is avidly taken up by malignant cells with high rates of glycolysis