Keywords
ICG reporting - lymphedema - standardization
Introduction
Lymphedema is being increasingly dealt by reconstructive and microsurgeons in the
wake of increasing surgical treatment modalities. The plan of management depends on
factors like level of subcutaneous fibrosis, associated skin changes, degree of increase
in limb girth and, most importantly, availability of patent lymphatics or extent of
channel destruction. Intradermal injection of indocyanine green (ICG) dye, followed
by infrared scan, is a portable, quick and safe way of delineating the lymphatics,
which does not employ any radioactive exposure. The findings can be recorded and shared
among any number of clinicians. Although lymphedema can be classified universally,
according to ICG findings, the system of reporting the findings is very exhaustive,
nonspecific and not easily reproducible ([Fig. 1]). This study proposes a reporting system for precisely locating different representations
of the dye in the lymphatics, thereby minimizing uncertainty.
Fig. 1 Lymphedema classification based on ICG lymphangiography (Source: Chang DW, Suami
H, Skoracki R. A prospective analysis of 100 consecutive lymphovenous bypass cases
for treatment of extremity lymphedema. Plast Reconstr Surg 2013; 132:1305–14).
Materials and Methods
The patient was asked to change into a hospital gown and placed in a dark room. The
Irillic.nm flourescence imaging system (Irillic, India) was prepared and camera kept
on a standby mode. Injection sites were sterilized with betadine solution. For upper
limb, first and fourth web space, radial and ulnar aspect of the volar wrist were
chosen as injection sites, whereas for lower limb, first web space and lateral to
tendoachilles were injected based on cadaveric lymphatic studies.[1]
[2] Additional injections near the elbow or knee can be given to hasten the proximal
dye uptake, and in severe lymphedema, with diffuse dermal backflow distally. An amount
of 0.5 mL of 2% lignocaine was injected, followed by 0.5 mL of Aurogreen dye (Aurolab,
India) (ICG–25 mg vial diluted with 10 mL distilled water) injected intradermally
into each site, using a 1 mL syringe with 31G needle. The patient was asked to walk
around, massage manually and open or close a fist repeatedly. The scan was repeated
every 15 minutes till the dye reached axilla or groin or dye showed no progress for
45 minutes.
The report included the following findings:
-
Linear lymphatics ([Fig. 2]).
-
Splash pattern of dermal backflow ([Fig. 3]).
-
Stardust pattern of dermal backflow ([Fig. 4]).
-
Diffuse pattern of dermal backflow ([Fig. 5]).
-
Blank zone.
Fig. 2 Linear lymphatics.
Fig. 3 Splash pattern of dermal backflow.
Fig. 4 Stardust pattern of dermal backflow.
Fig. 5 Diffuse pattern of dermal backflow.
A four-component code was created for each of the above findings as depicted below.
-
Right/Left–R/L
-
Flexor/Extensor–F/E
-
Zone/Wrist/Ankle–Z/W/A ([Table 1]) ([Fig. 6])
-
Radial/Ulnar/Medial/Lateral–R/U/M/L
Table 1
Description of the limb zones
|
Zone/wrist/ankle
|
Distance from wrist/ankle (cm)
|
|
Midpalm/midfoot
|
Midpalm/midfoot
|
|
W/A
|
0
|
|
Z1
|
4
|
|
Z2
|
8
|
|
Z3
|
12
|
|
Z4
|
16
|
|
Z5
|
20
|
|
Z6
|
24
|
|
Z7
|
28
|
|
Z8
|
32
|
|
Z9
|
36
|
|
Z10
|
40
|
|
Z11
|
44
|
|
Z12
|
48
|
|
Z13
|
52
|
|
Z14
|
56
|
Fig. 6 Marking the zones in upper limbs.
For instance, linear lymphatics on flexor aspect of the right forearm in zone 3, that
is, within 8 to 12 cm from the wrist along the radial aspect was reported as Linear
lymphatics–“RFZ3R.”’
Splash pattern on extensor aspect of the left leg in zone 7 and 8, that is, within
24 to 32 cm from the ankle along the medial aspect was reported as Splash–“LEZ7+8M”
([Table 2]).
Table 2
The proposed four-component reporting code
|
Finding
|
Right/Left
|
Flexor/Extensor surface
|
Zone
|
Border
|
|
L = lateral; M = medial; R = radial; U = ulnar.
|
|
Linear lymphatics
|
R/L
|
F/E
|
Zx
|
R/U/M/L
|
|
Splash
|
|
|
|
|
|
Stardust
|
|
|
|
|
|
Diffuse
|
|
|
|
|
|
Blank
|
|
|
|
|
The findings were charted on a reporting sheet prepared by the team, illustrating
the patient identification details, relevant history, volumetric findings, proposed
reporting format, and graphic representation of the ICG findings ([Fig. 7]). The same report was interpreted by two different clinicians, without any aid from
the primary clinician, on a series of 10 patients, and interrater reliability was
calculated using the following formula:
Fig. 7 The proposed reporting system sheet.
Results
The interrater reliability with which the ICG findings could be interpreted and charted
among the three clinicians was 98.7%.
Discussion
Several methods have been reported to detect lymphatic channels, for example, including
magnetic resonance imaging, computed tomography, ultrasonography, lymphoscintigraphy
and ICG lymphangiography.[3]
[4]
[5]
[6]
[7]
[8] ICG is a green fluorescent dye with no radioactive potential, which travels fast
in the body, being a water soluble preparation. Up to 2 cm deep lymphatics can be
visualized and assessed by ICG lymphangiography, based on the penetration level of
near infrared rays.[9] The camera handpiece consists of an excitation light source with a wavelength of
770 nm and a near infrared detector that filters and collects the fluorescence signals
above 800 nm. When ICG is excited by the light source, the emitted fluorescence is
captured and displayed in real-time using detector and a custom software. These fluorescence
signals can be stored as images and videos and reviewed later. ICG lymphangiography
findings include either fluorescent linear lymphatic channels or dermal backflow.
Linear channels represent the normal functional superficial lymphatics. Dermal backflow
is a pathological finding which presents as different patterns, as per the severity
of damage. Splash pattern represents an early stage of valve destruction, with scattered
dye and tortuous lymphatic channels. Stardust or milky way pattern is an indicator
of progression with diffuse illuminated background and scattered bright fluorescent
spots. Diffuse pattern of dermal backflow indicates a severe advanced stage of lymphedema
with wall thickening and lumen stenosis. It is seen as a widespread fluorescence with
no areas of bright spots.[2] These patterns map the areas with available lymphatics as well as areas of destruction,
thereby dictating the surgical interventions feasible. Blank zone in proximal extremities
indicates poor dye uptake and thus can either be interpreted as a higher grade of
lymphedema or supplemented with additional proximal dye injections, in order to outline
the backflow pattern in these zones. Despite being a patient and clinician friendly
investigation, the interpretation of findings following ICG lymphangiography is time
consuming and lacks standardization. The disorderly system of reporting makes it arduous
to locate and mark the exact location and extent of linear channels and dermal backflow
on any future follow-up unless the recorded findings are available. This can lead
to needless repetition of the test when the patients seek a different clinician or
center or the same clinician encounters the patient after a routine follow-up of months.
Likewise, the report can also facilitate better communication and coordination among
the surgeons and physiotherapists regarding the type and intensity of physiotherapy
needed and in outlining common treatment goals. Like the standardization of classification
of lymphedema has been in practice and enables better understanding of the severity
and progression of the disease, the findings of the lymphography, if standardized,
can ensure a quick and systematic management of lymphedema patients. This does not
substitute on table ICG marking but helps in preoperative patient counselling with
reference to the need for surgery, planning the type of surgery, guiding the physiotherapist
in decongestive physiotherapy, comparing the progress of the disease, and monitoring
postoperative progress in case the old ICG recordings are not available. As the ICG
test is a dynamic investigation whose results vary with time, this reporting system
is aimed at avoiding unplanned repeat studies before the stipulated time due to lack
of reliable information about the previous dye study. As depicted by this study, the
extent of interpretation of an ICG scan reported using the proposed symbolic representation
system among multiple clinicians was found to be reliable and obviated the need for
a repeat scan, thereby empowering consistency to a clinician’s assimilation.
