Case Report

Magnetic Resonance Lymphangiography: Clinical and Radiological Correlation

Savaş Tepe*, Ali Ertan Çapar and Ali Rıza Ercocen
Department of Oncology, Bayindir Hospital, Turkey


*Corresponding author: Savaş Tepe, Department of Oncology, Bayindir Hospital, Turkey

Published: 05 Dec, 2017
Cite this article as: Tepe S, Çapar AE, Ercocen AR. Magnetic Resonance Lymphangiography: Clinical and Radiological Correlation. Clin Oncol. 2017; 2: 1376.

Abstract

Purpose: To find correlation between the clinical and pre and postoperative findings and magnetic resonance lymphangiography (MRL) images of the lower extremities.
Methods: 10 patients with primary and secondary lymphedema of the lower legs (2 males, 8 females, range 15-80, mean age of 36) were retrospectively evaluated. Clinical correlation and pre and postoperative findings were revealed.
Results: Challenges and technique of MRL was reviewed in patients with lower extremity lymphedema.
Conclusıon: MRL is an effective and valuable method to examine lymphatics of the thigh, leg and particularly calf of the patients with lymphedema.


Introduction

Aim of this study are visualization of lymphatics using magnetic resonance imaging (MRI) as a guide, seeing the correlation of clinical findings and helping surgeon select appropriate microsurgical techniques and treatment for lymphedema.
Identification or visualization of the lymphatics has a long and remarkable historical challenge. Lymphedema is a debilitating disease caused by abnormal lymphatic flow and generally associated with malignancy and also its treatment. Lymphedema is basically described with the following; inflammation, abnormally gathered protein rich fluid, interstitial space fibrosis, and hypertrophy of the adipose tissue [1]. Lymphedema is categorized as primary (congenital) or secondary. Congenital lymphedema is less common compared to secondary which might arise from blockage of lymph vessels due to operation, trauma, infection or radiation. Breast cancer and gynecological malignancies and related surgeries are the most frequent malignancies causing secondary lymphedema [2,3].
Patients with lymphedema secondary to connective tissue diseases, infection and recurrent cellulitis are not included in this study.
Newer imaging technique with high resolution dynamic three dimensional (3D) MRL, demonstration of lymphatics, venules, lymph nodes and surgical lymphaticovenular anastomosis is a lately utilized radiological method which diagnoses presence, extent, intensity of lymphedema, maps and identifies lymphatic vessels, and guides for surgical planning. MRL maintains volumetric datasets that are high in resolution to determine the existence and intensity of lymphedema; illustrates superficial lymphatic vessels; provides anatomic and morphologic information which may differ chronic phase of the disease.


Methods

Technique
From January 2013 to August 2017 ten patients were evaluated with MRL. Informed consent was obtained from all individual participants included in the study. The research was performed according to the Declaration of Helsinki principles. MRL was applied on a 1.5 Tesla MR imaging magnet (Siemens, Magnetom Avanto, Erlangen, Germany) employing phased array surface coils. Imaging protocol used for the MRL, image post processing and interpretation of the images in our institution are as revealed. Upon clinical request MRI of the lower extremities was applied bilaterally. In the MRI magnet patients are laid feet first and lying on their backs, having the face upward. Surface coils are placed from mid foot to hip. Head coils are positioned to ankle region. First, high T2 weighted 3D sequence was used for defining the intensity and scope of lymphedema. Then intracutaneous contrast medium injected through both feet interphalangeal area 4 sites each to detect lymph vessels using 3D gradient echo (GRE) sequence images. Imaging parameters are as follows;
Pre contrast T2W Fat suppressed coronal plan, repetition time (TR) 2000 msn, echo time (TE) 693 msn, Flip Angle (FA) 150, field of view (FOV) 450 mm, section thickness 1 mm, matrix 259x320, scan time 6.5 minutes.
Post contrast T1 spoiled gradient echo (SPGR) fat saturated coronal plan, TR 4.66, TE 2.38, FA 25, FOV 450, section thickness 1.5 mm, matrix 448x448, scan time 2.4 minutes.
First EMLA (Astrazeneca, France) anesthetic cream is put on the foot distal intermetatarseal- interphalengeal area prior to injection. The contrast material is prepared while pre contrast scan acquisition is taken. During intracutaneous contrast administration, patients felt mild pain. There were no other discomfort or complications related to study. If there is a case of patient expressing pain and distention, we recommend dealing with discontent similar to contrast extravasation which may be seen after intravenous contrast injections (get vitals, evaluate for compartment syndrome tissue necrosis, raise extremity, make cold compress, monitor, advise the patient with instructions to follow additional medical care if symptoms worsen, consult surgery, report to the patient's physician, note down in the medical record). Combination of the subcutaneous injection of 2% citanest (Zenica Medical, Paris, France) 5 cc, 0.1 mmol/kg body weight gadolinium (multihance, gadobenate dimeglubine, Guerbet, France) injected to the each interdigital web space between the metatarsals approximately 2 cc each interdigital web space with a 24 G needle. The injected sites were massaged for a minute. Acquisition was done at 5, 15, 30, 45, 60 minutes, 2 hours, 4 hours, 8 and 24 hours. Following contrast administration venous enhancement always occurs. Lymphatics enhancement usually augments and slowly advances with time, whereas enhancement of the veins lessens with time, therefore kinetic of the enhancement of lymphatics versus veins are helpful to differentiate. Enhanced lymphatic channels may not be detected in standard extremities with MRL which is assumed to be related with quicker lymphatic transport in a normal extremity.


Table 1

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Table 1
Table of the patients with lower extremity lymphedema.

Figure 1

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Figure 1
Pre contrast coronal T2W MR image characteristically demonstrates muscle sparing epifascial distribution of lymphedema (arrow).

Result

Stages of lymphedema are latent (subclinical), mild, moderate and severe. Latent and mild stages could respond to conservative approach such as limb elevation and gradient compression garments. In our study MRL was performed for the patients with severe stages of lymphedema.


Patients

Table 1 of the patients with lower extremity lymphedema Before administration of the contrast agent, first pre contrast T2W magnetic resonance images are evaluated. This will provide the knowledge of distribution of lymphedema (Figure 1). Following this sequence mapping of lymphatics are in order. Starting at 5 minutes, followed by 15, 30, 45, 60 minutes, 2 hours, 4 hours, 8 and 24 hours post contrast magnetic resonance lymphangiography sequences are performed (Figure 2 and 3).
Dermal back flow is an area of progressive interstitial dispersion of the contrast medium in soft tissue due to proximal obstruction of lymph drainage or in another term poor lymphatic drainage, reflects proximal lymphatic obstruction (Figure 4).
Lymphatico venular anastomosis is performed when finding a vein in suprafascial area without venous insufficiency, neighboring lymphatics near and well mapped (Figure 5).


Discussion

Lymphaticovenous anastomosis redirects a lymphatic obstruction by conducting distal lymph flow into neighboring veins therefore is generally performed to treat lymphedema. For the regimen and to appropriately treat lymphedema, visualization of the lymphatic channels prior to surgery is important. New dedicated MR imaging sequences are able to demonstrate lymphatic channels with MRL and thus help the surgeon plan adequate microsurgery, currently lymphaticovenular anastomosis and lymph node relocation to nurture lymphangiogenesis, improve lymphatic drainage, reduce limb diameter, and avoid dermal sclerosis (Figure 6).
Comparison with other visualization techniques and methods: Available alternative imaging techniques for evaluation of lymphedema are bioelectric impedance spectroscopy, nuclear medicine lymphoscintigraphy and indocyanine green lymphography. Bioelectric impedance spectroscopy applies electrical impedance to weight the magnitude of extracellular water in an extremity. Nuclear medicine lymphoscintigraphy (NML) is frequently used method providing affirmation of unorthodox lymphatic flow to analyze lymphedema. Lymphatic dysfunction is identified as slowed asymmetric or non visualization of regional lymph nodes, unsymmetric lymphatic channels or dermal back flow. NML may not portray individual lymphatic channels since it suffers from poor spatial and temporal resolution [4]. Fluorescent indocyanine green is infused intracutaneously into the extremities for indocyanine green lymphography (ICGL) technique, and a photoelectric apparatus is utilized to detect the indocyanine green fluorescence within the superficial lymphatic routes and at places of dermal back flow. ICGL has a limited penetration depth of approximately 2 cm which is short in depth. The patient is not regarded suitable for reconstruction with LVA and becomes a possible nominee for excisitional surgery or cosmetic reduction if non functioning superficial lymphatic channels are detected with MRL.
In our MRL method we had acquisitions performed at 5, 15, 30, 45, 60 minutes, 2 hours, 4 hours, 8 and 24 hours, in order to evaluate if there are improvements or benefits examining the patients at those late intervals. However, this method is demanding and time consuming. Our findings reveal no great benefit performing the scanning after 4 hours. If time limitation is an issue, MRL examination even only the calf lymphatic vessels may be informative. Hence Lu [3] and colleagues mention that there was insignificant variance when normal and affected thighs are compared but there was a meaningful variance in transvers width and numbers of lymphatic channels between healthy and abnormal calf. They also imply that lymphatic neoperfusion or neovascularization appears more often in the abnormal calf than the abnormal thigh. This observation interestingly is about secondary LEL. On the other hand people with congenital or praecox types of primary lymphedema types are described as having hypoplastic lymph routes in the thigh and calf.
We performed MRI sequences in coronal plan for both legs at the same time. Some centers perform scan orientation in sagittal plan then transform the images at workstations to Maximum intensity projections to coronal plan. This may provide better visualization, however it is not possible to perform MRL for both legs at the same time and MRL should be performed separately unilaterally for each leg if MRL would be performed bilaterally in sagittal plan. The patient should be centered to the magnet, and the legs should be placed as nearly as possible to the scanner isocenter. This helps promote shimming and homogeneity of fatty tissue elimination.
Some limitations of the MRL must be mentioned and these are long duration of the MR examination, and infrequent difficulty in characterizing the affected lymphatic vessels when an underlying venous contamination is present. Pelvic and above knee region were insufficient to image for lymphatics due to low volume of contrast material remained in this vascular system. Therefore our study region remained mainly below the knee. White et al. [5] reported intradermal injection of rather than a subcutaneous injection for the optimal visualization of lymphatics. However Mazzei et al. [6] did not find significant differences between intradermal and subcutaneous injection approach. Mazzei logically advices the precaution adopted before the contrast medium injection to withdraw the syringe plunger in order to avoid a small vein cannulation.
What is important for the surgeon in a MRL radiology report?
As a preoperative imaging technique and in order to plan best strategy for lymph vessel reconstruction, our microsurgeons expect that a radiology MR imaging report detect and mention the intensity and magnitude of the lymphedema, depict and define the region and course of specific lymphatic vessels, distance between affected lymphatic vessel and the vein chosen for the LVA, detection and localization of lymph nodes, presence of venous contamination. When dynamic post contrast sequences are examined lymphatics present as dotted, zigzag course, interrupted contrast enhancing vessels that gradually enhance in time. If there is any dermal back flow, its existence, region and magnitude of any sites should also be indicated. Venous contamination almost always occurs. Morphologic changes and the evaluation of enhancement are applied to characterize lymph vessels versus superficial veins since amplitude of enhancement alters in time on both vessel systems. This report will guide the surgeon’s appropriate surgical repair.


Figure 2

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Figure 2
Early visualization of lymphatics at 15 minutes showing lymphatic networks, discontinuous, tortuous, beaded lymphatic vessels, whereas veins are smooth and uniform in caliber, linear and continuous (short arrow lymphatic vessels, long arrow veins).

Figure 3

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Figure 3
Same patient at 60 minutes (short arrow lymphatic vessels, long arrow veins).

Figure 4

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Figure 4
MRL at 2 hours, showing sites of dermal back flow (an area of progressive interstitial dispersion of the contrast medium in soft tissue due to proximal obstruction of lymph drainage or in another term poor lymphatic drainage, reflects proximal lymphatic obstruction ), patchy, non regular high signal intensities on contrast enhanced image (arrow).

Figure 5

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Figure 5
A region of blush (arrow) represents a site of LVA.

Figure 6

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Figure 6
MRL image at 1 hour showing transferred lymph node (arrow).

Conclusion

Main points
When we started writing this manuscript in 2013 selecting our patients, we had trouble finding related articles in the field. That was the main reason we wanted to work on this subject. Nowadays it is pleasantly surprising that some studies can be found on magnetic resonance lymphangiography (MRL).
Briefly our method was scanning all our patients with MRI for MRL in 5, 15, 30, 45, 60 minute, 2, 4, 8,16, 24 hour intervals. However this is a time consuming method and requires the patient to lay down into magnet several times for long duration. As a result we think that it is possible to get the most of necessary information in the first two hours scanning of MRL and it will not add too much extra information in the extended hours compared to the efforts and time spent.
We have scanned all our patients in the bilateral and coronal plan. If an unilateral extremity examination is requested, it may result with good quality imaging getting first a sagittal MRL sequence and then reformatting the images to coronal plans.
In addition all our patients were referred by the Aesthetic & Reconstructive Surgery Department. In close relationship we have discussed the results of pre and post operative versions of MRL with them and finally prepared an MRL report that would fulfill their needs.


References

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