MRI lymphography is an alternative to invasive methods such as oil-contrast lymphangiography and lymphoscintigraphy.
There are 2 types of MRL:
Contrast-enhanced MRL (CERML) based on T1-weighted sequences; it involves
subcutaneous injection of paramagnetic contrast medium; safe technique,
with high spatial resolution and able to provide a good visualization of the lymphatic drainage.
Gadolinium injection in the interdigital spaces ican cause patients’ discomfort and local reactions.
Due to the recent evidence of intracranial gadolinium deposition after contrast-enhanced MR imaging,
the effort to use magnetic resonance imaging techniques that do not involve the administration of any contrast media,
especially in younger patients,
is increasingly pronounced
Non-contrast MRL (NCMRL) is a non-invasive imaging technique based on heavily T2-weighted sequences,
able to highlight the signal of static or slow-moving fluid-filled structures,
like lymphatic vessels,
with a suppression of the signal intensity of the background tissues.
The limitations of this imaging technique are:
•it cannot depict normal or hypoplastic lymphatic structures.
Only when the lymphatic fluid is impaired,
the vessel is dilated and filled with stagnated lymph,
and it becomes visible on NCMRL
•it does not provide functional information about the timing of the lymphatic drainage or the nodal uptake,
•it has limited spatial resolution,
therefore CEMRL results to be the best technique for the evaluation of distal lymphatic vesselsIts point of strenghts are: •heavily T2-weighted sequences allow the visualization of epifascial fluid components and lymphatic vessel •non-invasiveness,
non-need to administer contrast medium: this means great benefits for allergic patients and for pediatric patients,
who can safely undergo this type of examination,
and no risk related to gadolinium deposition.
•short acquisition time: in about 30 minutes,
patient positioning and imaging acquisition of the whole lower limbs are performed,
while for CEMRL a total average examination time of 1 hour and 15 minutes for the lower limb is expected and faster acquisition time means further cost reduction
Patients are asked to suspend the lymphatic drainage for 48 hours and the use of elastic stockings or bandages for 24 hours.