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4.6 Indocyanine Green Near-Infrared Imaging
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Table 4.8 Dermal backflow pattern staging for the upper and lower extremities (adapted from Yamamoto et al.
Stage Upper Extremity Lower Extremity
0 No dermal backflow pattern No dermal backflow pattern
I Splash pattern around the axilla Splash pattern around the groin region
II Stardust pattern limited between the axilla and the
olecranon
III Stardust pattern exceeding the olecranon Stardust pattern extended distal to the superior border of the
IV Stardust pattern observed throughout the limb Stardust pattern extended to the whole limb
V Diffuse pattern and stardust pattern observed throughout
the limb
Stardust pattern extended proximal to the superior border of
the patella
patella
Existence of diffuse pattern with stardust pattern in the
background
63,64
)
Fig. 4.13 Strategic incision placement for lymphovenous anastomosis with ICG lymphangiography for lymphatic vessel mapping (a) and
near-infrared vein visualization (b) for superficial venule mapping. Intersection of the vessels were marked (b), and intraoperative
confirmation of successful lymphovenous anastomosis through ICG lymphangiography is performed (c).
backflow pattern, visualization of lymphatic vesse ls can be
difficult. However, Yang et al. could demonst rate in
their study that even non-ICG enhanced but lymphatic
flow-positive could be considered for a functional LVA.
(Chapter 8) Post-LVA patency can also be detected intraoperatively with ICG lymphangiography.
There have been reports on ICG lymphangiogr aphy
being an effe ctive postoperative tracking modality after
75,76
lymphatic reconstructions such as LVA.
The evaluation was performed at 1 month for up to 12 months
postoperatively demonstrating h igh correlation with the
clinical outcome.
Another potential diagnostic use of ICG lymphangiography is predictive lymphatic mapping. It was first described
by Mihara and colleagues in the preoperative assessment
77
of patients with severe unilateral lymphedema.
ICG lym-
extremity in those patients. By using fixed lines and scaling
the results to the affected limb they were able to perform
LVA successfully with a 2-cm incision. This preliminary
74
study was refined in a current study of lymphatic mapping
of the upper limb by mirroring of the healthy limb.
dictive lymphatic mapping was performed in 16 patients
with unilateral upper limb lymphedema showing stardust
or diffuse de rmal backflow pattern. They were able to
find at least three incision sites each carrying a minimum of on e lymphatic vessel suitable for LVA. In this
way, the patients received approximately three anastomoses. Predictive lymphatic mapping appears to be a
good alternative in preoperative mapping of lymphatics
in severe dermal backflow patterns. However, further
studies are needed with a long follow-up to prove its
efficacy.
phangiography was unable to detect any linear lymphatics
for LVA because of advanced dermal backflow pattern. Instead of just operating along the anatomical landmarks,
Mihara and colleagues used the anatomy of the healthy
contralateral lower extremity and transferred lymphatic
mapping patterns from the unaffected to the affected
4.6.3 Reversed Lymphatic Mapping
Free vascularized lymph node transfer (VLNT) is applied
more and more in the treatment of lymphedema.
Chapter 10 and 11)Eventhoughtheresultsarepromising,
78
Pre-
79
(see
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the risk of iatrogenic lymphedema at the donor site should
be not underestimated.
80,81,82,83,84,85
For this reason, Dayan and colleagues modified the
hitherto concept of axillary reverse mapping (ARM) by
86,87
Klimberg.
The idea behind mapping the lymphatic
drainage of the arm and the breast region is the reduction
of potential disruption of lymphatics during lymphadenectomy, thus minimizing the risk of subsequent lymphedema. For this, blue dye is injected into the arm to display
and to preserve the lymphatics, and technetium is administrated to map the drainage of the breast. Dayan and colleagues basically used this mapping technique for VLNT
in order to minimize the risk of iatrogenic lymphedema.
Instead of blue dye, they used ICG to visualize the
lymphatic drainage pattern and especially the lymph
nodes for VLNT. The injection of technetium to the limb
help identify and thus avoid the lymph nodes draining
the extremity. Reverse lymphatic mapping can be applied
for groin lymph node, axillary lymph node, and supraclavicular lymph node harvest.
For the axilla, ARM is applied for harvesting a vascularized thoracodorsal artery or lateral thoracic artery-based
lymph node transfer (▶ Fig. 4.14). Technetium is injected
into the first and second web spaces of the ipsilateral hand
of lymph node harvest about 2 hours before the surgery.
ICG is injected into about four to five areas transversely
to the chest and back about 15 to 20 cm inferior to the
axillary fold. Gamma probe identification of the axillary
nodes allows them to be spared from flap dissection or
incidental injury. ICG lymphangiography identifies the
vascularized lymph nodes at the lateral chest wall that can
be harvested safely. This procedure is done pre- and intraoperatively. For the groin, technetium, or an alternative
tracer (e.g., blue dye) is injected into the first and second
web spaces of the foot and drained to lymph nodes that
drain the lower leg. Usually these are the lymph nodes below the groin crease. These nodes can be identified with
the gamma probe and hence be avoided. Injection of ICG
to the lower abdomen identifies the lymph nodes in the
groin area that can be safely harvested.
A retrospective review of 35 patients undergoing VLNT
using reverse lymphatic mapping demonstrated no
observed cases of donor-site lymphedema.
88
colleagues showed in their meta-analysis of 189 patients
in 11 clinical studies a rate of donor-site lymphedema of
84
This is the only clinical study using ICG for ante-
1.6%.
grade and technetium for reverse lymphatic mapping.
Shortcomings of this study are lack of long-term followup, ranging only from 1 to 30 months, and further clinical
89
experience.
mapping without radioisotope.
A newer approach is reverse lymphatic
90
The idea behind is
avoiding the adverse effects of the radioisotope techneti-
88
um, thereby improving patient safety. In addition, reverse
lymphatic mapping can be applied in more institutions
that are lacking nuclear medicine and are resource
limited. By combining ICG lymphangiography and blue
dye injections coupled with anatomical expertise, the
surgeon should be able to harvest lymph nodes flaps
safely (▶ Fig. 4.15).
In a preliminary study, Aliot ta and Schwarz followed
up on 17 patients with this technique demonstrating
no iatrogenic lymphedema in the extremity associated
90
with the lymph node har vest.
They repor ted one case
of ski n necrosis fro m subdermal injection of methylene
blue that required surgical therapy. This new approach
to reverse lymphatic mapping seems to be a real alternative. It appears to be safe, cost effec tive, and can be
performed in institutions without nuclear medicine.
However, further studies are necessary to prove its
long-term outcome.
4.6.4 Conclusions
ICG lymphangiography is a necessary basic tool for preoperative diagnostics, intraoperative navigation or reverse
mapping, and postoperative follow-up after LVA or VLNT
to visualize the lymphatic rearrangement. It is considered
to be safe and reliable and to offer real-time presentation,
although it still must be regarded as an off-label use. ICG
lymphangiography facilitates the evaluation and staging of
Demiri and
42
Fig. 4.14 Target lymph nodes for a vascularized lymph node flap based on the
thoracodorsal artery or lateral thoracic
artery. Lymph nodes in the axilla should be
avoided. Injection of technetium or an
alternative tracer into the first and second
web spaces of the hand. Indocyanine green
injections transversely cross the chest and
back to identify includable lymph nodes.
(Reproduced with permission from Schünke
M, Schulte E, Schumacher U, Voll M, Wesker
K. Prometheus LernAtlas: Innere Organe.
5th ed. Thieme; 2018.)
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Fig. 4.15 Intraoperative markings (anterior edge of latissimus dorsi and inferior edge of pectoralis major muscle) for vascularized lymph node
transfer based on the thoracodorsal vessels (a). Lymph node flap with skin island based on the thoracodorsal vessels and with preservation of
the thoracodorsal nerve (b). The harvested lymph node flap with a perforator-based skin island (c) is anastomosed to the anterior tibial vessels
(d). Indocyanine green is injected intraoperatively into the skin island to demonstrate uptake of the lymph nodes (e) and again, 2 years after
the initial surgery, during a flap thinning procedure (f).
the lymphatics. The characteristic f low patterns lead to the
corresponding lymphedema management. In the preoperative assessment strategic markings of lymphatics for LVA
can lead to good outcome. It can also be applied intraoperatively to detect lymphatics more quickly, thus concentrating the surgical field for reliable LVA.
Reverse lymphatic mapping appears to be a promising
tool for safer lymph node harvest to reduce donor-site
morbidity, especially donor-site lymphedema. Further
clinical experience and long-term follow-up is necessary,
especially without radioisotopes, to underline its efficacy.
4.7 Magnetic Resonance Imaging
Carola Brussaard
The success of treating lymphedema is strongly related to
choosing the most appropriate and individual therapeutic
option for the patient. The delicate composition of the
subcutaneous tissue and the functionality and accessibility
of lymph collectors primarily determine the therapeutic
options.
Conventional MRI provides addit ional diagnostic information to clinical tests to evaluate the amount of free
movable fluids as a stage parameter with detailed mapping of the exact location, whether or not already complicated by the occurrence of hypertrophy of subcutaneous
adipose tissue as part of stage progression.
With or without the additional use of contrast agents
with intra-/subdermal injection, MRL offers additional insight into the lymphatic vasculature, allowing a high spatial
resolution of the lymphatics, including the venules. Nonfunctional MRL imaging is based on the three-dimensional
T2 and visualizes stasis of fluid or slow-moving fluid (but
stasis of fluid in a widened, nonfunctional lymph vessel is
also highlighted). Functional MRL injection of gadolinium
into the web spaces facilitates imaging of the transit of the
contrast agent in lymph vessels (three-dimensional T1
Volumetric interpolated breath-hold examination [VIBE]
with fat suppression).
Unfortunately, MRI is an expensive technique that is not
widely available. Moreover, the available scanning time
should be distributed equally among all colleagues. So, it is
essential to consider the clinical question for a patient with
lymphedema to use the most tailored sequence(s). The
surgeon should be aware that an MRL taken at different
time points may last up to 2 hours.
4.7.1 Conventional Magnetic
Resonance Imaging: Detection of Free
Movable Fluid, Fat Deposition as Stage
Parameter, and Volumetry
The application of conventional MRI in lymphedema
patients provides the opportunity to detect movable free
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fluids in the affected area. Using the short tau inversion
recovery (STIR) sequence, free movable fluid will be detected. This MR sequence uses fat-suppression technique.
As a result, a low signal intensity (SI) is obtained from the
fat in the subcutis. The fluid in the subcutaneous fat
retains a high SI on this sequence (▶ Fig. 4.16). As fat
suppression is not complete, the skin, the subcutis, the
muscles, the bone marrow, and the delineation of the
bony structures are still seen. The STIR sequence has a
moderate resolution, not enough to visualize lymphatic
vessels. This sequence has numerous applications in orthopedics, and so it is widely available. The MR sequence
takes place in a reasonable time frame of approximately
8 minutes per scan station. Two scan stations are needed
to cover an arm and three stations to cover a leg. The STIR
sequence is useful for selecting those patients who would
Fig. 4.16 Conventional magnetic resonan ce imaging short tau
inversion recovery sequence of both legs: Not e the apparent
increase in volume of the left leg compared with the right one
due to an increase in the left side’s subcutaneous fat layer. The
strings with high signal intensity in the subcutis on the left side
(bright) are mainly caused by lymphedema. The other lineshaped hyperintensities visible on the left- and right-hand
sides in both subcu tis and muscles are caused by slow-moving
fluid in veins.
benefit from an initial conservative therapeutic approach
by complete decongestive therapy (CDT) to diminish the
free fluid load in their limbs, e.g., prior to a surgical
approach (see Chapter 6 and Subchapter 7.3). Slotting a
conventional MRI ahead of a lymphangiography when in
clinical doubt of the presence of free fluid or where there
is an excess of movable fluid is advisable. Excess of free
fluid load interferes with the ability to visualize lymphatic vessels by MRL as described below.
The application of conventional MRI in lymphedema
patients may add the opportunity to detect the degree of
fat deposition, another parameter of stage migration, and
to evaluate benefit from suction-assisted lipectomy
(▶ Fig. 4.17).
The application of conventional MRI in lymphedema
patients may add the opportunity to include volumetry
to a scheduled MRI, e.g., on the T2-sequence with fat suppression. For the volumetry of a limb, the limb, or a part
of the limb, with some surrounding air is roughly circumscribed (three-dimensional). The software calculates the
number of encircled voxels. The histogram displays the SI
in the voxels. Air is always hypointense on each MR
sequence due to the lack of protons. On the T2 sequence
with fat suppression, water has a high SI. With a slider,
the reasonable minimum threshold for water’s signal
intensity is determined per patient. In a histogram, the
number of voxels originat ing from the air (low SI),
water (high SI), and other struc tures such as muscles/
blood vessels (intermediate SI) are displ ayed. The software calculates the limb’s water content (voxels with
high SI) and th e actual limb volu me (voxel with high
plus intermediate SI). As the voxel volume is known,
thepercentageofwaterandthevolumeofwaterinthe
limb can be calculated. At this moment, the optimal sequence and parameters to divide the three subgroups
(low SI, intermediate SI, and high SI) are part of scientific work to clari fy the clinical relevance of the numeric MR- volumetry relative to the subjective visible
fraction of water and fat in the subcutis as demonstrated in ▶ Fig. 4.16 and ▶ Fig. 4.17.
Conventional MRI with the STIR sequence for the assessment of free fluid load, degree of fat deposition, and for
volumetry can be performed during one acquisition sequence. The postprocessing may take 5 to 10 minutes but
summarizes all relevant information that conventional MRI
may deliver.
4.7.2 Magnetic Resonance Imaging of
Lymphatic Vessels
MRL offers additional insight into the physiological and
pathophysiological lymphatic vasculature compared with
conventional MRI. It is indicated to evaluate the most
individual and preferred approach for patients prior to
lymphedema surgery.
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Fig. 4.17 (a, b) On the left side, the shor t tau inversion recovery sequence and maximum intensity projection maximum intensity
projection of the same short tau inversion recovery series show a swollen left arm after surgery in the axilla after breast cancer
treatment. The short tau inversion recovery sequence shows no hyperintense strings in the subcutis. The maximum intensity projection
reconstruction of the short tau inversion recovery sequence show linear hyperintensities representing the larger veins in the arms. The
thickened subcutis is due to abundant fat deposition. (c, d) On the right side, images, with the same technique, of another patient with
a swollen arm after surgery, with clinically pitting edema. The images show hyperintense strings in the subcutis in the forearm, the
elbow region, and the medial side of the upper arm, representing lymphedema. The maximum intensity projection reconstruction
(d) provides an excellent overview of the location of the lymphedema. Only the patient displayed on the right side will benefit from a
therapeutic approach focused on reducing edema.
Technically, it has been differentiated into noncontrast
(nonfunctional) and contrast-enhanced (functional) MRL.
Noncontrast
In noncontrast MRL, a heavily weighted, high-resolution,
three-dimensional T2 sequence is used, performed for visualization of both standing fluid and slow-moving fluid.
The sequences used for noncontrast MRL are the same as
those used for magnetic resonance cholangiopancreaticography (MRCP). In the noncontrast MR lymphangiography,
both the lymph vessels and fluid accumulation are documented in one image (▶ Fig. 4.18). This MR sequence is
50% more time consuming than the STIR sequence, resulting in an acquisition time of approximately 12 minutes per station. The interpretation of the lymphatics
position is challenging. In the MRCP sequence, (almost)
complete fat suppression is programmed. The result is
that no SI is present from the fat in the subcutis, nor
from the bone marrow. The bones themselves always
have a low SI on each MR sequence due to the lack of
protons in the cortex. The lack of SI of the described tissues compromises the possibilities for the description
of the position of lymphatic vessels in relation to landmarks. Besides, a description of the position of lymph
vessels can be compromised due to abundant dermal
backflow since the MR signal of fluid in lymph vessels
and those of fluids due to dermal backflow are o f the
same high SI intensit y on the MRCP sequence.
Contrast-Enhanced Magnetic Resonance
Lymphangiography
In the procedure of contrast-enhanced MRL (CE-MRL),
depots of gadolinium are injected very superficially in to
the dermis and/or superficial subcutaneous tissue in all
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Fig. 4.18 Thin maximum intensity projection reconstruction
(5 mm) of a high-resolution, three-dimensional T2 sequence of a
right underarm. The lymphatic vessels are indicated by the white
arrows and are recognized as a cord of beads with a limited
meandering gradient. The localization of the lymphatic vessels in
relation to bony landmarks is difficult as due to precise fat
suppression no signal intensity derived from the subcutaneous
fat or the fat of the bone marrow remains. The fluid (high signal
intensity) in the olecranon fossa is indicated by the green arrow.
web spaces of the hand or foot. As gadolinium contrast
agents are developed for intravascular use.
Note:
Gadolinium contrast for MRL is currently considered
off-label use in most countries. Consequently, the use
of gadolinium contrast for MRL is currently
unregulated in most countries.
However, as the gadolinium contrast products were
developed initially for intravascular use, its extravasates
side effect is extensively tested. Despite the side effects
ranging from irritation to in the worst-case scenario of
tissue necrosis, gadolinium products are approved by
various inspection authorities.
The injected gadolinium contrast for CE-MRL in the
interstitial space (up to four web spaces) is resorbed not
only by the lymph collectors, but also by venules. Highresolution, three-dimensional T1 sequences, taken with
an interval of 15 minutes (15–30 minutes and when
necessary 45 minutes), show small and large venous
structures and functional lymphatic vessels in the subcutis, no matter their depth from the skin, and their
proximity in the same image. The sequence is a lso available in standardiz ed form on MR equipment a s it is also
used for imaging of other structures, e.g., the liver. The
technique also requires postprocessing with maximum
intensity projection (MIP) reconstructions. Postprocessing of a sequence usually requires 15 to 20 m inutes
(▶ Fig. 4.19).
The additional goal of the CE-MRL procedure is to visualize functional lymphatic vessels in close relation to
small venules in one image. Association of regions of interest to relevant anatomical landmarks should reduce
LVA procedure time in the operating room. The interpretation of CE-MRL might be compromised by dermal
backflow. Nevertheless, drawbacks for MRI remain its
availability, costs, and time-consum ing acquisition of interpretable sequences. Further evaluation in prospective
studies should address the following issues in this promising field of lymphedema diagnostics.
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Contrast-enhanced magnetic resonance lymphangiography (CE-MRL) —how to do it?
The procedure starts with proper skin disinfection. In CE-MRL, small extravasates of up to 0.8 ml are injected into web
spaces, resulting in a burning sensation and a little redness. The inconvenience of the burning sensation is overcome by
the subcutaneous injection of a local anesthetics, e.g., 0.2 ml of Xylocaine 1%, into web spaces 1 minute before the
injection of gadolinium. The redness disappears in the next few hours and is not painful. The patient is fully informed
about the gadolinium’soff-label use before the examination and the expected inconvenience. After the contrast depots
are created, the patient is asked whether they still experience any burning sensation. If that is the case, 0.1 ml
supplementary local anesthesia is given at the designated sites. The contrast is drained to both the functional lymphatics
and the capillary system. The time delay between the start of the injection outside the MR room and positioning on the
MR table is about 10 minutes. The patient is carefully braced overall to achieve a moderate homogeneous pressure on
the limb. The bracing prevents the patient from trembling during the examination, as the overall scan time is long. The
arm is positioned along the body with the thumb pointing ventrally. The legs are fixated so that the toes face ventrally.
▶ Fig. 4.20 shows the technical set-up for a CE-MRL of an arm. The first three-dimensional T1 sequence covers the region
from the midpoint of the hand to the upper third of the underarm. Next, two stations are scanned with the STIR
sequence and spliced, covering the whole arm. Finally, a second three-dimensional T1 sequence is performed covering
the region from 10 cm above the elbow, mostly until the distal two-thirds of the underarm. The overall scanning time
for an arm is about 20 minutes. Scanning of legs is more time consuming as they are longer and have a larger transverse
diameter, so more voxels must be scanned. The three-dimensional T1 sequence for legs takes about 7 minutes. The STIR
sequence needs three scan stations to cover the region from the feet to the midpoint of the small pelvis and lasts
29 minutes. Patients are advised to wear no support stocking after the examination for the rest of the day to give the
resorption of contrast agent ever y chance. Detailed information on each moment of the examination reduces the
patient’s stress. The examination is well tolerated.
Fig. 4.19 (a1) Coronal, (b1) axial, and (c) sagittal thin maximum intensity projection reconstructions (5 mm) of a three-dimensional T1
sequence (VIBE, Siemens Skyra, Erlangen, Germany) of the forearm, performed 30 minutes after injection of gadolinium into the web
spaces of the right hand. Functional lymphatic vessels are visible at the ulnar side as a cord of beads (white arrow). The smooth
structures represent nearby small venous vessels (blue arrows). (a2, b2) Annotation of lymph vessels (and small venous structures)
relative to an anatomical landmark (in this case the olecranon fossa). (Reproduced with permission from Zeltzer et al.
96
)
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Fig. 4.20 Screenshot for planning of contrast-enhanced
magnetic resonance lymphangiography sequences of the arm
(Siemens Skyra, Erlangen, Germany).
4.7.3 Tips and Tricks
The clinical success of MRL and its usage for improved patient care depend on close cooperation and mutual
understanding between radiologists and plastic surgeons.
Surgeons should, however, be aware of the limitations of
the examination itself, e.g., MRL imaging is hindered by
dermal backflow. Thus, when employing ICG lymphangiography, the following is recommended:
●
MRL imaging should be scheduled 1 day after manual
lymph drainage (MLD).
●
Compression garments should be worn until just before
the examination.
Radiologists mus t show interest to the surgeons’ demand to understand the surgical anatomical landmarks
and questions desired for LVA. In this way, radiologists
identify relevant positions for the planned procedure in
the operating room, addressing both functional lymphatic ve ssel (LV) and venules in proximity. Regular
multidisciplinary meetings with imaging discussions
including patients’ follow-up add a significant value.
Finally, in the radiology department itself, one or two
dedicated radiologists are needed to spend time for and
with patients with lymphatic pathologies. Patients fear injection to limbs affected with lymphedema, as they are
said to be vulnerable to infection. They must be convinced
that extensive skin disinfection will prevent this type of
possible complication. In cooperation with motivated technologists, MRL can be regarded as a standardized procedure, resulting in predictable quality.
4.8 Functional Magnetic
Resonance
Lymphangiography
Carola Brussaard, Hans Schild, and Claus Christian Pieper
Functional MRL must be regarded as the royal discipline of
MRL, providing dynamic information for the surgeon. Visualizing functional lymphatics with MRI in a swollen extremity with lymphedema is still challenging and further
evaluation of the technique is in continuous progress.
4.8.1 Technique
The procedure starts with a sub- or intradermal injection of
gadolinium-based contrast products in web spaces of toes
or fingers. We prefer to inject a local anesthetic (0.3 ml) in
the web spaces first followed by 0.8 ml of gadolinium-based
contrast medium. Undiluted gadolinium-based contrast
medium in the extravascular space causes an irritating
effect with occasional redness in the injection site. By
injecting the anesthetic first, the procedure is well tolerated.
Patients are told that the redness will disappear in the following hours. With three-dimensional, T1-weighted images
with fat suppression, the tract of the contrast in the functional lymphatics is followed from the distal to the proximal
part of the limb. After the gadolinium enters the interstitial
space, the product will be absorbed primarily by the lymphatic or the venule capillary system, causing venous enhancement as well. Therefore, some of the gadolinium will
end soon in the blood circulation system and will subsequently be excreted, mostly by the urinary tract.
The veins are well visible in the source images of the
three-dimensional, TI-weighted sequence (thin slices). The
functional lymphatics become visible after postprocessing
of the image. For visualization of functional lymphatics,
again the principle of the MIP is used. In MIP images the
maximum intensity of a position in an image is depicted
in a slice with thickness suitable for the purpose. For
visualization of functional lymphatics, slice thickness of
the MIP between 3 and 8 mm are useful (▶ Fig. 4.21).
For LVA, accurate localization of the exact position of
the functional lymphatics in relation to small veins or
venules by a coordin ate system is useful and improves
dissection time and success. With functional MRI, on
T1 sequences with fat suppression, the functional
lymphatics can be described relative to any point that is of
clinical interest. Images for localization are provided in
three orthogonal planes for the surgeon. The depth of the
functional lymphatic vessel can be described as well, indicating whether it will be visible subcutaneously with the
technique of ICG lymphangiography (see Subchapter 4.7).
An example in which those lymphatics are labelled relative
to reference points is shown in ▶ Fig. 4.19.
For identifying functional lymphatics, series enhanced with gadolinium contrast agents are required.
A three-dimensional T1 sequence with fat suppression
can demonstrate functional lymphatics nicely. The time
from contrast injection to optimal imaging depends on the
velocity of the lymph flow. A huge variation according to
the condition of the patients exists. Therefore, it is difficult
to predict the optimal imaging time with the maximal
signal intensity of the lymphatics. Furthermore, the postprocessing of the images performed at different time
points is very time consuming. A close interaction
between the surgeon and the radiologist is necessary to
benefit from the advantages of standardization and postprocessing with a coordinate system by MRI for techniques
such as LVA or lymph vessel transfer.
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Fig. 4.21 (a-d) Axial, transversal, and sagittal maximum intensity projection reconstructions of a three-dimensional T1-weighted sequence
(VIBE, Siemens Skyra, Erlangen, Germany) of a right/left upper extremity with lymphedema stage 2/3. At the ulnar side, a band with
lymphatics parallel to the forearm is visible (green arrows). They show a lower signal intensity than the straighter course of the veins (blue
arrows).
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4.8.2 Diagnosis of Peripheral
Lymphatic Leakage
Various surgical procedures, such as lymph node biopsy,
or trauma involving the lymphatic vessels of an extremity
can not only lead to secondary lymphedema, but may
also result in lymphatic leakage due to direct injury and
development of a lymphocutaneous fistula. Although
rare, lymphatic leakages are a severe complication associated with a delay of ne cessary (oncologic) therapies
as well as infectious, der matological, and psychosocial
sequelae. Initially conservative treatment (e. g., immobilization and pressure bandage) is pursued, but may
fail in several p atients due to per manent leakage.
In such cases imaging is often necessary to guide further
treatment options, such as surgical or—more recently—
interventional-radiological measures.
95,96,97
imaging techniques like MRI, CT, or ultrasound can depict
the location of subcutaneous fluid collections but can neither differentiate between a postoperative seroma and a
true lymphocele due to lymphatic leakage nor show the exact location, course, and number of leaking lymphatic vessels. Lymphoscintigraphy can demonstrate lymphatic flow
and leakage but has insufficient anatomical resolution to
depict individual lymphatic vessels. ICG lymphangiography
94
Conventional
may be able to differentiat e between leaking lymphatic
vessels and seroma, but also has its limitations due to
two-dimensional resolution. Direc t (t ranspedal) lymphangiography with iodized oil can be used for exact
anatomical evaluation of the leaking lymphatics and
has also been described to have a therapeutic effect.
However, it is technically difficult, time consuming, and
associated with severe complications (e.g., anaphylaxia,
pedal lymp hatic leakage, pulmonary oil embolization )
and thus regarded to be obsolete.
Therefore, functional MRL is incre asingly used in
the pretherapeut ic workup of patients with lymphatic
leakages to determi n e the opt i m al treatmen t st r ategy.
MRL can be performed at 1.5 T and 3.0 T. Typically, fatsuppressed, T2-weighted images are acquired to evaluate
subcutaneous fluid collections as well as extremity
edema (▶ Fig. 4.22a). Although heavily T2-weighted
three-dimensional sequences can be used to delineate
lymphatic vessels,
98
the mainstay of MR evaluation for
lymphatic leakages is contrast-enhanced transpedal
99
Contrast injection is performed in a similar way as
MRL.
for lymphedema evaluation. After contrast application,
dynamic (preferably three-dimensional), T1-weighted,
fat-suppressed images should be acquired for at least 30
to 45 minutes until contrast medium is observed at the
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Fig. 4.22 (a–f) A 75-year-old male patient
with inguinal lymphatic leakage after
inguinal lymph node dissection. The axial,
fat-suppressed, T2-weighted image
(a) demonstrates a small fluid collec tio n/
lymphocele in the right groin (white
arrowheads) with an indwelling drainage
catheter (white arrow). The maximum
intensity projection of a fat-suppressed,
three-dimensional, T1-weighted sequence
after pedal indirect lymphangiography
subdermal contrast injection (b) and the
corresponding axial images (c–f) show
continuous contrast-enhancement of
ventromedial lymph collectors as well as
leakage from several of t hese collectors in
the right groin (white arrowheads in c).
Contrast medium is also drained v ia the
indwelling catheter (white arrow in b).
Notice also contrast enhancement within
the veins (blue arrows).
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