Ultrasonography for classifying lymphatic sclerosis types and deciding optimal sites for lymphatic-venous anastomosis in patients with lymphoedema,

Visualising lymphatic flow dynamics during complex physical therapy: A photoacoustic imaging study

Background

Complex physical therapy (CPT), which combines compression and exercise therapies, is the cornerstone of lymphedema treatment. However, assessing lymphatic flow in living humans is challenging owing to the small size and transparent nature of lymphatic vessels. Herein, we introduce a novel approach utilising photoacoustic imaging (PAI) to visualise lymphatic flow dynamics under CPT conditions. Compared with existing modalities, PAI offers superior details, enabling real-time evaluation of lymphatic vessels during compression and exercise. Real-time evaluation of lymphatic flow may enable advanced research on optimal perioperative compression therapy and exercise therapy.

Methods and Results

Herein, PAI was used to assess lymphatic flow in four healthy subjects. Detailed images of lymphatic and blood vessels were obtained using photoacoustic lymphangiography, which utilises indocyanine green as a light absorber. The participants underwent simulated compression using a transparent film dressing, with a pressure of approximately 20 mmHg. Exercise stress was applied to mimic CPT conditions. Compression facilitated the collapse of superficial veins while lymphatic vessels remained intact. Additionally, the lymphatic pumping frequency was the highest during combined compression and exercise, highlighting the synergistic effect of these therapies on lymphatic flow.

Conclusion

Our findings underscore the potential of PAI in elucidating the mechanisms underlying the efficacy of CPT. PAI may enable comprehensive assessments of vascular changes during CPT by allowing simultaneous delineation of veins and lymphatic vessels. While our study represents a significant step forward, its limitations, including small sample size and exercise regimen specificity, warrant further investigations.

Application of preoperative ultrasound combined with indocyanine green lymphography in lymphaticovenular anastomosis of the lower limb-A retrospective study research

BackgroundWe evaluated the application of preoperative ultrasound (US) combined with indocyanine green (ICG) lymphography in lymphaticovenular anastomosis (LVA) of the lower limb.Methods66 patients with lower limb lymphedema were selected as study subjects and divided into research (n = 35) and control groups (n = 31). The patients were treated with LVA using ICG lymphography combined with US and simple ICG lymphography as the positioning method. The number of lymphatic vessels anastomosed, diameter, depth, and searching time were compared.ResultsThe number of anastomotic lymphatic vessels in the research group was more than in the control group (p < .05). Compared with the lymphatic vessels under ICG lymphography, the lymphatic vessels under US locating had less search time, larger diameter, and deeper depth (p < .05).ConclusionUS combined with ICG lymphography in preoperative can increase the number of lymphatic vessels and shorten the time to find lymphatic vessels.

Efficacy study of lymphaticovenular anastomosis via the lymphosome-based four-incision approach for lower limb lymphedema

OBJECTIVE

Lower limb lymphedema (LLL) is a chronic condition with impaired lymphatic drainage. Lymphaticovenular anastomosis (LVA) is a promising microsurgical treatment for LLL. Refined surgical techniques, such as optimal incision placement and precise lymphatic vessel identification, are essential for better clinical outcomes. For patients with LLL, we performed an LVA via the lymphosome-based four-incision approach. We standardized incision positioning and identified lymphatic vessels for LVA to improve surgical outcomes.

METHODS

A retrospective study was conducted on 59 patients with LLL who underwent LVA. Among them, 32 patients in the study group received LVA using the four-incision approach, and 27 patients in the control group underwent LVA with empirically determined incision placement. All patients were followed up for 12 months after the operation. The outcome measures included the number of lymphatic-to-venous anastomoses, surgical duration, Lymphedema Functioning, Disability, and Health Questionnaire for Lower Limb Lymphedema and Lower Extremity Lymphedema Index, Patient Health Questionnaire-9 items, and subcutaneous thickness.

RESULTS

At the 6-month and 12-month follow-ups, there was a significant interaction between the two groups of patients in terms of Lower Extremity Lymphedema Index and Lymphedema Functioning, Disability, and Health Questionnaire for Lower Limb Lymphedema (P < .05). The Patient Health Questionnaire-9 items showed no interaction between the two groups (P > .05). After treatment, the subcutaneous thickness in the study group was lower than that in the control group (P < .05). There were no significant differences between the two groups regarding surgical duration and the number of lymphatic-to-venous anastomoses (P > .05).

CONCLUSIONS

LVA via the lymphosome-based four-incision approach can significantly enhance the quality of life, limb volume, and subcutaneous thickness in patients with LLL. This study presents new incision selection criteria for LVA and underlines the necessity of comprehensively addressing patients' mental health.

Concordance between preoperative imaging methods in patients with limb lymphedema undergoing supermicrosurgical lymphaticovenular anastomosis

OBJECTIVE

Supermicrosurgical lymphaticovenular anastomosis (LVA) is increasingly being recognized as a first-line treatment of limb lymphedema because it is minimally invasive and highly effective. Lymphoscintigraphy and indocyanine green (ICG) lymphography are the two most commonly performed diagnostic imaging examinations to establish the indication and plan the procedure for patients affected by limb lymphedema. In a small group of patients, the information between these two imaging tools can be discordant, showing different anatomical drainage pathways or the absence of drainage and dermal backflow in one examination and valid drainage pathways in the other. The purpose of this study is to examine the types of possible discrepancies between lymphoscintigraphy of the superficial system and ICG lymphography and to describe the surgical outcomes after LVA for patients presenting with such discrepancies.

METHODS

We retrospectively reviewed the data of all patients who underwent LVA for upper or lower limb lymphedema between July 2015 and July 2023. From this series, we identified a group of patients with nonconcordant imaging results from lymphoscintigraphy and ICG lymphography before lymphatic surgery. Nonconcordant findings were described in terms of "pattern discordance" and "pathway discordance." The surgical outcome was measured by the change in the mean circumference of the limb after surgery. The changes between the preoperative and postoperative limb measures were analyzed using the Student t test. P values < .05 were considered significant.

RESULTS

A total of 28 patients with limb lymphedema exhibited inconsistencies between preoperative lymphoscintigraphy of the superficial system and ICG lymphography. Among these patients, 14 experienced pattern discordance, 13 had pathway discordance, and 1 patient had both. After LVA, we observed a significant reduction in the average circumference of the affected limb in the analyzed group.

CONCLUSIONS

The discrepancy in the information between lymphoscintigraphy and ICG lymphography in the preoperative study of patients affected by limb lymphedema is rare but possible. This phenomenon is still not fully explained; however, our results suggest that it does not correlate with the outcome of supermicrosurgical LVAs.

Lymphatic Mapping with Multi-Lymphosome Indocyanine Green Lymphography in Legs with Lymphedema

It is observed that the locations of the most functional lymphatic vessels in the lymphedematous limbs can differ significantly from those in healthy limbs. The aim of this study was to elucidate the lymphatic map of lymphedematous limbs. We retrospectively analyzed 59 patients (118 limbs) with lower limb lymphedema. Fifty-five were women and four were men. The mean age and duration of lymphedema was 62.4 and 7.7 years, respectively. For the lateral thigh lymphosome, we injected indocyanine green (ICG) at the lateral knee and measured the distance (Dt) between the anterior superior iliac spine (ASIS) and the point where the lymphatic vessels crossed the reference line (the line connecting the ASIS and the patellar center). For the lateral calf lymphosome, we injected ICG at the lateral ankle and measured the distance (Dc) between the inferior patellar border and the point where the lymphatic vessels crossed the reference line (the anterior border of the tibia). In the lateral thigh, the mean Dt was 30.4 ± 0.6 cm (range, 0-41 cm) and the distribution peaked at approximately 30 cm from the ASIS. In the calf, the mean Dc was 13.1 ± 0.9 cm (range, -11 to 32 cm). The distribution of lymphatic vessel locations was highly variable. We could establish the lymphatic map in the lymphedematous legs. The distribution of lymphatic vessels in the thigh and lower legs had one and two peaks, respectively.

Supermicrosurgical lymphovenous anastomosis

Lymphedema impairs patients' function and quality of life. Currently, supermicrosurgical lymphovenous anastomosis (LVA) is regarded as a significant and effective treatment for lymphedema. This article aims to review recent literature on this procedure, serving as a reference for future research and surgical advancements. Evolving since the last century, LVA has emerged as a pivotal domain within modern microsurgery. It plays a crucial role in treating lymphatic disorders. Recent literature discusses clinical imaging, surgical techniques, postoperative care, and efficacy. Combining advanced tools, precise imaging, and surgical skills, LVA provides a safer and more effective treatment option for lymphedema patients, significantly enhancing their quality of life. This procedure also presents new challenges and opportunities in the realm of microsurgery.

Evolution and Application of Ultrasound for Flap Planning in Upper Extremity Reconstruction

Accurate preoperative localization of dominant perforators provides crucial information about their location and diameter, leading to reduced surgical time, improved flap viability, and decreased complications. Ultrasound has increased in popularity in recent years, with the advantages of providing reproducible, accurate, cost-effective, and real-time information while reducing radiation exposure. Precise preoperative mapping of perforators allows for rapid and safe elevation of suprafascial, thin, and superthin flaps. This review focuses on the role of ultrasound as a tool for preoperative flap planning in the upper extremities.

Lymphatic Mapping for LVA with Noncontrast Lymphatic Ultrasound: How We Do It

Recently, lymphatic ultrasonography has received increasing attention. Although there are several reports on contrast-enhanced lymphatic ultrasound as a preoperative examination for lymphaticovenous anastomosis (LVA), we have been reporting the usefulness of preoperative noncontrast lymphatic ultrasound. In this article, the detailed procedure for conducting lymphatic ultrasound during the preoperative examination of LVA is thoroughly described. The only items required for lymphatic ultrasound are an ultrasound device, an echo jelly, a straw for marking, and a marker. We use an ordinary ultrasound device with an 18-MHz linear probe. We apply the Doppler, Crossing, Uncollapsible, Parallel, and Superficial fascia index to identify the lymphatic vessels. While imagining the course of the lymph vessels, we position the probe perpendicular to the long axis of the lymphatic vessels. When a vessel is found under the superficial fascia, the probe is moved proximally to trace the vessel's path. If the vessel transverses a nearby vein without connecting to it, it is most likely a lymphatic vessel. To confirm, we ensure that the vessel does not exhibit coloration in the Doppler mode. As LVA is most effective when the dilated lymph vessels are anastomosed, we use lymphatic ultrasound to identify the most dilated lymphatic vessels in each lymphosome, and mark incision lines where suitable veins are in close proximity. No contrast agent is required; therefore, medical staff such as nurses and ultrasound technicians can autonomously conduct the test.

Preoperative photoacoustic versus indocyanine green lymphography in lymphaticovenular anastomosis outcomes for lower extremity lymphedema: A pilot study

BACKGROUND

Identification of the proper lymphatics is important for successful lymphaticovenular anastomosis (LVA) for lymphedema; however, visualization of lymphatic vessels is challenging. Photoacoustic lymphangiography (PAL) can help visualize lymphatics more clearly than other modalities. Therefore, we investigated the usefulness of PAL and determined whether the clear and three-dimensional image of PAL affects LVA outcomes.

METHODS

We recruited 22 female patients with lower extremity lymphedema. The operative time, number of incisions, number of anastomoses, lymphatic vessel detection rate (number of functional lymphatics identified during the operation/number of incisions), and limb volume changes preoperatively and 3 months postoperatively were compared retrospectively. The patients were divided according to whether PAL was performed or not, and results were compared between those undergoing PAL (PAL group; n = 10) and those who did not (near-infrared fluorescence [NIRF] group, n = 12).

RESULTS

The mean age of the patients was 55.9 ± 15.1 years in the PAL group and 50.7 ± 14.9 years in the NIRF group. One patient in the PAL group and three in the NIRF group had primary lymphedema. Eighteen patients (PAL group, nine; and NIRF group, nine) had secondary lymphedema. Based on preoperative evaluation using the International Society of Lymphology (ISL) classification, eight patients were determined to be in stage 2 and two patients in late stage 2 in the PAL group. In contrast, in the NIRF group, one patient was determined to be in stage 0, three patients each in stage 1 and stage 2, and five patients in late stage 2. Lymphatic vessel detection rates were 93% (42 LVAs and 45 incisions) and 83% (50 LVAs and 60 incisions) in the groups with and without PAL, respectively (p = 0.42). Limb volume change was evaluated in five limbs of four patients and in seven limbs of five patients in the PAL and NIRF groups as 336.6 ± 203.6 mL (5.90% ± 3.27%) and 52.9 ± 260.7 mL (0.71% ± 4.27%), respectively. The PAL group showed a significant volume reduction. (p = .038).

CONCLUSIONS

Detection of functional lymphatic vessels on PAL is useful for treating LVA.

Imaging Modalities for Evaluating Lymphedema

Lymphedema is a progressive condition. Its therapy aims to reduce edema, prevent its progression, and provide psychosocial aid. Nonsurgical treatment in advanced stages is mostly insufficient. Therefore-in many cases-surgical procedures, such as to restore lymph flow or excise lymphedema tissues, are the only ways to improve patients' quality of life. Imaging modalities: Lymphoscintigraphy (LS), near-infrared fluorescent (NIRF) imaging-also termed indocyanine green (ICG) lymphography (ICG-L)-ultrasonography (US), magnetic resonance lymphangiography (MRL), computed tomography (CT), photoacoustic imaging (PAI), and optical coherence tomography (OCT) are standardized techniques, which can be utilized in lymphedema diagnosis, staging, treatment, and follow-up. Conclusions: The combined use of these imaging modalities and self-assessment questionnaires deliver objective parameters for choosing the most suitable surgical therapy and achieving the best possible postoperative outcome.

Usefulness of 33 MHz Linear Probe in Lymphatic Ultrasound for Lymphedema Patients

Background: Lymphatic ultrasound has recently been reported useful in the treatment of lymphedema. However, no conclusions have been reached regarding the best probe for lymphatic ultrasound. Methods: This was a retrospective study. Fifteen limbs of 13 patients with lymphedema in whom we could not find dilated lymphatic vessels on lymphatic ultrasound with an 18 MHz probe but later could find them with 33 MHz probe were included. All patients were women, and the mean age was 59.5 years. We performed lymphatic ultrasound in four areas per limb by applying an index of D-CUPS, as we previously reported. We measured the depth and diameter of the lumen of the lymphatic vessels. We also diagnosed the degree of lymphatic degeneration based on the normal, ectasis, contraction, and sclerosis type (NECST) classification. Results: We found lymphatic vessels in 22/24 (91.7%) areas in the upper limbs and 26/36 (72.2%) areas in the lower limbs. The mean depth and diameter of the lymphatic vessels were 5.2 ± 0.28 mm and 0.33 ± 0.029 mm, respectively. Based on the NECST classification, 68.2% of the upper limbs and 56.0% of the lower limbs were of the ectasis type. We found functional lymphatic vessels in 6/6 (100%) of the upper limbs and 5/7 (71.4%) of the lower limbs, which indicated lymphaticovenous anastomosis (LVA) in these 11 patients. Conclusion: Using 33 MHz probe, we could detect functional lymphatic vessels in most patients. Even if lymphatic vessels were not found with the 18 MHz probe, LVA could be performed using a higher frequency probe.

The relationship between the degree of subcutaneous fluid accumulation and the lymphatic diameter

BACKGROUND

The relationship between the fluid accumulation in the subcutaneous tissue and the lymphatic degeneration in the lymphedematous limbs has not been elucidated, and we have evaluated it in the current study.

METHODS

Twenty-five patients (50 limbs) were included in this retrospective study. We performed lymphatic ultrasound by separating the limbs into four lymphosomes: the saphenous (medial) thigh, saphenous (medial) calf, lateral thigh, and lateral calf. In each lymphosome, the lymphatic diameter, the degree of lymphatic degeneration, and the fluid accumulation in the subcutaneous tissue were evaluated. The lymphatic vessels were detected based on the index of D-CUPS (Doppler, Crossing, Uncollapsibe, Parallel, and Superficial fascia). Lymphatic degeneration was diagnosed based on the NECST (Normal, Ectasis, Contraction, and Sclerosis Type) classification.

RESULTS

All patients were women with a mean age of 62.7 years. Lymphatic vessels were detected using lymphatic ultrasonography in 50 saphenous (medial) thigh lymphosomes, 43 saphenous (medial) calf lymphosomes, 34 lateral thigh lymphosomes, and 22 lateral calf lymphosomes. The fluid accumulation tended to be more acute in the more severe stages of lymphedema. As for the NECST classification, the normal type was observed only in the areas without fluid accumulation. Among the other areas, the percentage of contraction type was the largest in the area with slight edema and decreased in the areas with severe edema.

CONCLUSION

The lymphatic vessels were dilated to a greater extent in legs with more severe fluid accumulation. Therefore, there is no hesitation needed to perform lymphaticovenous anastomosis because of severe lymphedema.

Ultrasound-guided lymphaticovenous anastomosis without indocyanine green lymphography mapping: A preliminary report

BACKGROUND

Although indocyanine green (ICG) lymphography is the standard preoperative examination for lymphaticovenous anastomosis (LVA), it cannot be performed in patients allergic to ICG. This report aimed to clarify the effects of LVA with lymphatic ultrasound and without ICG lymphography.

METHOD

Lymphatic ultrasound was performed preoperatively on six limbs of four patients with lower limb lymphedema who were allergic to ICG to detect the lymphatic vessels. All patients were women and had secondary lymphedema after uterine cancer treatment, with a mean age of 57.0 years (range; 47-68 years). The severity of lymphedema was stage 2a in two limbs, stage 2b in three limbs, and stage 3 in one limb. During the preoperative lymphatic ultrasound, we searched for the dilated lymphatic vessels in the saphenous, lateral calf, and lateral thigh lymphosomes. The incision sites were determined based on the ultrasonographic findings, and LVA was performed under local anesthesia. The surgical results were evaluated based on the limb volume calculated from the circumferences.

RESULT

Totally, 13 skin incisions were made, and the lymphatic vessels consistent with the ultrasonographic findings were found in all locations. The mean number of the lymphatic vessels anastomosed per limb was 2.2 (range; 1-4). The mean diameter of the lymphatic vessel was 0.69 mm (range; 0.3-1.0 mm). No complications were observed in the perioperative period. The mean follow-up period was 386.8 days. The mean preoperative and postoperative limb volumes were 5468 ml (range; 4552-6378 ml) and 5027.4 ml (range; 4353-5561 ml). Limb volume decreased in all six limbs.

CONCLUSION

The effectiveness of performing LVA by identifying the lymphatic vessels using lymphatic ultrasound was demonstrated. More medical institutions will be able to perform LVA in the future, even without ICG devices.

Lymphaticovenular anastomoses training model for multiple stages of lymphedema by using efferent lymphatic plexus of the mesenteric lymph node of rats

INTRODUCTION

Lymphaticovenular anastomosis (LVA) has transformed lymphedema treatment and has become an important part of the surgical therapy. LVA requires supermicrosurgical skills and unique nontraumatic techniques as the lymphatic vessel diameter of varies with the progression of lymphedema from 0.3 to 0.8 mm. However, even though several supermicrosurgical vessel anastomosis training models have been reported, only few focus on LVA including both various sizes of lymphatic vessels and lymphatic dissection. We report the establishment of a novel in-vivo LVA training model using the rat efferent lymphatic plexus of the mesenteric lymph node.

MATERIALS AND METHODS

Lymphatic vessels in the efferent lymphatic plexus of the mesenteric lymph node and mesenteric veins of 10 male Wistar rats, 572-850 g, were used for LVA in an intima-to-intima coaptation manner using 12-0 nylon suture with 4-6 stitches in an end-to-end fashion. Postoperative patency was evaluated with indigo carmine blue after completion of anastomosis. Diameters of lymphatic vessels in the plexus and recipient veins were measured.

RESULTS

The diameters of lymphatic vessels in efferent lymphatic plexus of the mesenteric lymph nodes and mesenteric veins used as recipients were measured in all 10 male rats. The mean number of lymphatic vessels included in efferent lymphatic plexus of the mesenteric lymph nodes was 7.5 (range, 5-11) and the mean diameter of the lymphatic vessels was 0.34 mm (range, 0.1-1.2 mm). The mean diameter of lymphatic vessels used for LVA was 0.46 mm (range, 0.25-0.7 mm). The mean diameter of the recipient veins was 0.49 mm (range, 0.35-0.7 mm). The postoperative patency rate after LVA was 100% (10/10).

CONCLUSION

We reported the establishment of LVA model involving the use of the efferent lymphatic plexus of the mesenteric lymph node and mesenteric veins in rats.

The Use of Ultrasound Imaging for Upper Extremity Lymphedema after Breast Cancer: A Systematic Review

BACKGROUND

 The aim of this study was to analyze the different applications of ultrasound (US) in upper extremity lymphedema (UEL) after breast cancer.

METHODS

 A systematic review of the literature was performed in line with the PRISMA statement using MEDLINE/PubMed databases from January 1970 to December 2021. Articles describing the application of US in patients with UEL after breast cancer were included. The quality of the study, the level of reproducibility, and the different applications and type of US technique were analyzed.

RESULTS

 In total, 30 articles with 1,193 patients were included in the final review. Five different applications were found: (1) diagnosis of UEL (14 studies found a direct correlation between lymphedema and morphological and/or functional parameters); (2) staging/severity of UEL (9 studies found a direct correlation between the clinical stage and the soft-tissue stiffness/texture/thickness); (3) therapeutic assessment (3 studies found an improvement in the circulatory status or in the muscle/subcutaneous thickness after conservative treatments); (4) prognosis assessment of UEL (1 study found a correlation between the venous flow and the risk of UEL); and (5) surgical planning (3 studies determined the location of the lymphatic vessel for lymphovenous anastomosis [LVA] surgery).

CONCLUSION

 Morphological and functional parameters have been correlated with the diagnosis, stage, therapeutic effect, prognosis of UEL, and surgical planning of LVA.

Measurement of lymphatic vessel depth using photoacoustic imaging

OBJECTIVES

Information regarding the depth of lymphatic vessel is important for lymphatic surgeons because rapid identification of functional lymphatic vessels and veins is necessary to perform good lymphaticovenular anastomosis, which is a surgical procedure for lymphedema cases. Photoacoustic lymphangiography (PAL) may be useful for such identification because it allows the assessment of the depth of lymphatic vessels. Thus, we aimed to measure the lymphatic vessel depth using images obtained by PAL.

METHODS

This study included healthy individuals and patients with lymphedema. In all participants, indocyanine green dissolved in dextrose was injected subcutaneously into the first and fourth webs of the foot and the lateral malleolus, and PAL was performed on the medial side of the lower leg. The lymphatic vessel depth was measured from the ankle joint, 10 cm above the medial malleolus, and 20 cm above the medial malleolus on PAL in the cross-sectional view and was compared between the participant groups.

RESULTS

The healthy group (mean age, 43.3 ± 12.9 years) included 21 limbs of 4 male and 16 female healthy individuals (bilateral limbs of 1 patient were considered). The lymphedema group (mean age, 62.0 ± 11.7 years) included 17 limbs of 3 male and 14 female patients with lymphedema. The average lymphatic vessel depths from the ankle joint, 10 cm above the medial malleolus, and 20 cm above the medial malleolus were 2.6, 4.7, and 5.6 mm in the healthy group and 3.6, 7.3, and 7.4 mm in the lymphedema group, respectively. Lymphatic vessels were significantly deeper in the lymphedema group than in the healthy group at all measurement locations.

CONCLUSIONS

Using PAL, we determined the lymphatic vessel depth in living bodies. By searching for the lymphatic vessels based on our findings, even surgeons who are relatively inexperienced with lymphatic surgery may be able to identify functional lymphatic vessels more efficiently.

Comparative Analysis of Preoperative High Frequency Color Doppler Ultrasound versus MR Lymphangiography versus ICG Lymphography of Lymphatic Vessels in Lymphovenous Anastomosis

BACKGROUND

 Despite the extensive use of various imaging modalities, there is limited literature on comparing the reliability between indocyanine green (ICG) lymphography, MR Lymphangiogram (MRL), and high frequency color Doppler ultrasound (HFCDU) to identify lymphatic vessels.

METHOD

 In this study of 124 patients, the correlation between preoperative image findings to the actual lymphatic vessel leading to lymphovenous anastomosis (LVA) was evaluated. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and simple detection were calculated. Subgroup analysis was also performed according to the severity of lymphedema.

RESULTS

 Total of 328 LVAs were performed. The HFCDU overall had significantly higher sensitivity for identifying lymphatic vessels (99%) over MRL (83.5%) and ICG lymphography (82.3%)(p < 0.0001). Both ICG lymphography and HFCDU had 100% specificity and PPV. The NPV was 3.6%, 6.5% and 57.1% respectively for MRL, ICG lymphography, and HFCDU. All modalities showed high sensitivity for early stage 2 lymphedema while HFCDU showed a significantly higher sensitivity for late stage 2 (MRL:79.7%, ICG:83.1%, HFCDU:97%) and stage 3 (MRL:79.7%, ICG:79.7%, HFCDU:100%) over the other two modalities (p < 0.0001).

CONCLUSION

 This study demonstrated while all three modalities are able to provide good information, the sensitivity may alter as the severity of lymphedema progresses. The HFCDU will provide the best detection for lymphatic vessels throughout all stages of lymphedema. However, as each modality provides different and unique information, combining and evaluating the data according to the stage of lymphedema will be able to maximize the chance for a successful surgical outcome.

LED-based photoacoustic imaging for preoperative visualization of lymphatic vessels in patients with secondary limb lymphedema

Lymphedema is the accumulation of protein-rich fluid in the interstitium (i.e., dermal backflow (DBF)). Preoperative imaging of the lymphatic vessels is a prerequisite for lymphovenous bypass surgical planning. We investigated the visualization of lymphatic vessels and veins using light-emitting diode (LED)-based photoacoustic imaging (PAI). Indocyanine-green mediated near-infrared fluorescence lymphography (NIRF-L) was done in fifteen patients with secondary limb lymphedema. Photoacoustic images were acquired in locations where lymphatic vessels and DBF were observed with NIRF-L. We demonstrated that LED-based PAI can visualize and differentiate lymphatic vessels and veins even in the presence of DBF. We observed lymphatic and blood vessels up to depths of 8.3 and 8.6 mm, respectively. Superficial lymphatic vessels and veins can be visualized using LED-based PAI even in the presence of DBF showing the potential for pre-operative assessment. Further development of the technique is needed to improve its usability in clinical settings.

Imaging of the Lymphatic Vessels for Surgical Planning: A Systematic Review

BACKGROUND

Secondary lymphedema is a common complication after surgical or radiotherapeutic cancer treatment. (Micro) surgical intervention such as lymphovenous bypass and vascularized lymph node transfer is a possible solution in patients who are refractory to conventional treatment. Adequate imaging is needed to identify functional lymphatic vessels and nearby veins for surgical planning.

METHODS

A systematic literature search of the Embase, MEDLINE ALL via Ovid, Web of Science Core Collection and Cochrane CENTRAL Register of Trials databases was conducted in February 2022. Studies reporting on lymphatic vessel detection in healthy subjects or secondary lymphedema of the limbs or head and neck were analyzed.

RESULTS

Overall, 129 lymphatic vessel imaging studies were included, and six imaging modalities were identified. The aim of the studies was diagnosis, severity staging, and/or surgical planning.

CONCLUSION

Due to its utility in surgical planning, near-infrared fluorescence lymphangiography (NIRF-L) has gained prominence in recent years relative to lymphoscintigraphy, the current gold standard for diagnosis and severity staging. Magnetic resonance lymphography (MRL) gives three-dimensional detailed information on the location of both lymphatic vessels and veins and the extent of fat hypertrophy; however, MRL is less practical for routine presurgical implementation due to its limited availability and high cost. High frequency ultrasound imaging can provide high resolution imaging of lymphatic vessels but is highly operator-dependent and accurate identification of lymphatic vessels is difficult. Finally, photoacoustic imaging (PAI) is a novel technique for visualization of functional lymphatic vessels and veins. More evidence is needed to evaluate the utility of PAI in surgical planning.

Lymphatic refill in ultrasound and lymphatic washout after lymphaticovenous anastomosis

BACKGROUND

Lymphaticovenous anastomosis (LVA) drains lymph accumulated in the lymphatic vessels into the veins (lymphatic washout). A method to identify the ideal lymphatic vessels to achieve washout has not been established. This study examined the relationship between lymphatic washout, lymphatic ultrasonographic findings, and surgical outcomes.

METHODS

We reviewed consecutive patients who underwent LVA for lower limb lymphedema between September 2020 and March 2021. Patients who lacked data were excluded. Preoperative ultrasonography was performed to measure the lymphatic diameter. After the probe was pressed against the skin and released, the reaction of the lymphatic vessels was classified as either refilled, crushed, undecidable, or solid. Intraoperatively, whether lymphatic washout was observed or not, was recorded and compared to preoperative findings using the chi-square test. In 54 limbs from 32 patients, the total number of LVA, number of anastomoses with washout, number of refills detected by ultrasound, and severity of lymphedema were compared with the surgical result (postoperative limb volume change) by multiple regression analysis (49 limbs whose pre-or postoperative circumference data were lacking or who underwent intensive compression therapy postoperatively were excluded).

RESULTS

Sixty-five patients were reviewed. After excluding six patients with missing data, 59 patients (103 limbs) were included. The median patient age was 63 years (interquartile range, 51-76 years). We performed LVA at 217 sites (mean, 2.1 anastomoses per limb). "Refilled" lymphatics were observed at 156 sites (71.6%) and significantly thicker than those classified as "undecidable" (p = .020 in the lower leg and p < .001 in the thigh). In the thigh, "refilled" lymphatics had a higher rate of a washout than those classified as "undecidable." In Pearson's correlation coefficient for the surgical result, as the number of washout positive LVA increased, the limb volume tended to decrease postoperatively (correlation coefficient: -0.25). However, multiple regression analysis did not identify any factors that significantly affected the surgical outcomes.

CONCLUSION

"Refilled" lymphatic vessels had a higher rate of intraoperative lymphatic washout after anastomosis.

A Systematic Stepwise Method to Perform a Supermicrosurgical Lymphovenous Anastomosis

BACKGROUND

Lymphovenous anastomosis (LVA) has become an increasingly common treatment for patients with extremity lymphedema. In this article, we present our current strategy for patient selection, preoperative planning, and a series of intraoperative clues that may help to perform a supermicrosurgical LVA. Technical considerations are presented using a systematic step-by-step method to make this procedure more reproducible and straightforward.

PATIENTS AND METHODS

We conducted a review of patients operated between January 2015 and June 2018 using the aforementioned approach. Data were collected prospectively, and all procedures were performed by the senior author. Preoperative assessment included lymphoscintigraphy, indocyanine green lymphography, noncontrast magnetic resonance lymphography and high-frequency ultrasonography. Lymphovenous anastomosis was decomposed into a sequential 6-step approach considering the main aspects that determine a successful anastomosis.

RESULTS

Lymphovenous anastomosis was performed in 229 patients, including 677 anastomoses. Median follow-up was 33 months (range, 13-51 months). A median of 3.1 (range, 1-7) LVA were performed on 2.7 (range, 1-6) incision sites per patient. Median time for dissection of lymphatic(s) and vein(s) was 8.7 minutes (1-18 minutes) with a median time of 27.2 minutes (range, 13-51 minutes) for a complete LVA. Lymphatic detection rate was 100% (677 of 677) and vein detection rate was 99.7% (675 of 677), with 31.0% (210 of 677) of reflux-free veins. For upper-extremity lymphedema (47 of 229; 20.6%), volume reduction was achieved in 100% (47 of 47) of the cases, with a median volume reduction rate of 67% (range, 7-93%). In lower-extremity lymphedema (182 of 229; 79.4%), volume reduction was achieved in 86.8% (158 of 182) of the cases, with a median volume reduction rate of 41% (range, 7-81%). Cellulitis episodes decreased from 2.1 to 0.2 episodes/year after LVA (P < 0.05).

CONCLUSIONS

Acceptable success rates were obtained using a sequential strategy for planning and execution of supermicrosurgical LVA for secondary extremity lymphedema. We believe including a stepwise approach may help to simplify this procedure, especially for surgeons in their early practice.

The accuracy of lymphatic ultrasound in measuring the lymphatic vessel size in lower limb lymphedema patients

BACKGROUND

Lymphatic ultrasound is a newly developed method to observe the lymphatic vessels. In this study, we compared the diameter of lymphatic vessels observed on preoperative ultrasound with the actual lymphatic diameter (LD) of lymphatic vessels observed intraoperatively.

METHODS

The study included 32 lower limbs in 17 patients with lower limb lymphedema. Lymphatic ultrasound was performed using a commonly used ultrasound device, Noblus ultrasound system, with an 18 MHz linear probe on preoperative day 1. We tracked the lymphatic vessels along the great saphenous vein, at the lateral calf, and at the lateral thigh, based on the lymphosome principle. We measured the cross-sectional height (CSH) and the cross-sectional width (CSW) of lymphatic vessels using ultrasound at the incision sites. Intraoperatively, we measured the diameter of the lymphatic vessel. Based on lymphatic degeneration, lymphatic vessels were categorized into four types using the normal-, ectasis-, contraction-, and sclerosis-type (NECST) classification.

RESULTS

We evaluated 68 lymphatic vessels. The mean CSH, CSW, and LD were 0.65 ± 0.35 mm, 1.3 ± 0.41 mm, and 0.79 ± 0.35 mm, respectively. The correlation coefficient between the CSH and the LD was 0.36 and that between the CSW and LD was 0.24. A significant difference was observed in CSH between the ectasis and contraction types (p = 0.0025).

CONCLUSIONS

We can somehow predict the size of the lymphatic vessels with CSH in the lymphatic ultrasound, whereas CSW is not reliable.

Treatment of Early-Stage Gynecological Cancer-Related Lower Limb Lymphedema by Lymphaticovenular Anastomosis-The Triple Incision Approach

Background and Objectives: Lower extremity lymphedema (LEL) is one of the most relevant chronic and disabling sequelae after gynecological cancer therapy involving pelvic lymphadenectomy (PL). Supermicrosurgical lymphaticovenular anastomosis (LVA) is a safe and effective procedure to treat LEL, particularly indicated in early-stage cases when conservative therapies are insufficient to control the swelling. Usually, preoperative assessment of these patients shows patent and peristaltic lymphatic vessels that can be mapped throughout the limb to plan the sites of skin incision to perform LVA. The aim of this study is to report the efficacy of our approach based on planning LVA in three areas of the lower limb in improving early-stage gynecological cancer-related lymphedema (GCRL) secondary to PL. Materials and Methods: We retrospectively reviewed the data of patients who underwent LVA for the treatment of early-stage GCRL following PL. Patients who had undergone groin dissection were excluded. Our preoperative study based on indocyanine green lymphography (ICG-L) and color doppler ultrasound (CDU) planned three incision sites located in the groin, in the medial surface of the distal third of the thigh, and in the upper half of the leg, to perform LVA. The primary outcome measure was the variation of the mean circumference of the limb after surgery. The changes between preoperative and postoperative limbs’ measures were analyzed by Student’s t-test. p values < 0.05 were considered significant. Results: Thirty-three patients were included. In every patient, three incision sites were employed to perform LVA. A total of 119 LVA were established, with an average of 3.6 for each patient. The mean circumference of the operated limb showed a significant reduction after surgery, decreasing from 37 cm ± 4.1 cm to 36.1 cm ± 4.4 (p < 0.01). Conclusions: Our results suggest that in patients affected by early-stage GCRL secondary to PL, the placement of incision sites in all the anatomical subunits of the lower limb is one of the key factors in achieving good results after LVA.

Lymphatic Mapping Using US Microbubbles before Lymphaticovenous Anastomosis Surgery for Lymphedema

Background Lymphaticovenous anastomosis (LVA) surgery is an effective surgical treatment of secondary lymphedema in the extremities, but indocyanine green (ICG) fluorescent lymphography, the reference standard for imaging target lymphatic vessels, has several limitations. More effective methods are needed for preoperative planning. Purpose To evaluate whether contrast-enhanced US (CEUS) can be used to identify target lymphatic vessels for LVA surgery in patients with secondary upper extremity lymphedema and compare the results with those from ICG fluorescent lymphography. Materials and Methods In this single-center retrospective review, CEUS with intradermal injection of microbubbles was performed in patients before LVA surgery in the upper extremities between October 2019 and September 2021. All patients had secondary upper extremity lymphedema from breast cancer treatment. Technical success rate was defined as lymphatic vessels identified with use of CEUS that led to successful LVAs. Descriptive statistics were used. Results All 11 patients were women (mean age, 56 years ± 8 [SD]). The median number of microbubble injection sites was 11 (range, 8-14). CEUS helped identify lymphatic vessels in all 11 women, including in six women in whom ICG fluorescent lymphography could not be performed or failed to help identify any targets. Thirty-five explorations (median, three per patient; range, two to four) were performed, and 24 LVAs (median, three per patient; range, zero to four) were created. Of the anastomoses, 33% (eight of 24) were mapped with use of both CEUS and ICG fluorescent lymphography, 58% (14 of 24) with CEUS only, and 8% (two of 24) with ICG fluorescent lymphography only. Among the 33 explorations on targets mapped with CEUS, an anastomosis could be made at 22 sites, for a technical success rate of 67%. Seven women had at least one additional LVA created from the use of CEUS. Conclusion Contrast-enhanced US is a promising tool for identifying lymphatic vessels in the upper extremities, especially when indocyanine green fluorescent lymphography fails to depict targets or cannot be used. Published under a CC BY 4.0 license.

Surgical Applications of Lymphatic Vessel Visualization Using Photoacoustic Imaging and Augmented Reality

Lymphaticovenular anastomosis (LVA) is a widely performed surgical procedure for the treatment of lymphedema. For good LVA outcomes, identifying lymphatic vessels and venules is crucial. Photoacoustic lymphangiography (PAL) is a new technology for visualizing lymphatic vessels. It can depict lymphatic vessels at high resolution; therefore, this study focused on how to apply PAL for lymphatic surgery. To visualize lymphatic vessels, indocyanine green was injected as a color agent. PAI-05 was used as the photoacoustic imaging device. Lymphatic vessels and veins were visualized at 797- and 835-nm wavelengths. First, it was confirmed whether the branching of the vasculature as depicted by the PAL was consistent with the actual branching of the vasculature as confirmed intraoperatively. Second, to use PAL images for surgical planning, preoperative photoacoustic images were superimposed onto the patient limb through augmented reality (AR) glasses (MOVERIO Smart Glass BT-30E). Lymphatics and venule markings drawn using AR glasses were consistent with the actual intraoperative images obtained during LVA. To anastomose multiple lymphatic vessels, a site with abundant venous branching was selected as the incision site; and selecting the incision site became easier. The anatomical morphology obtained by PAL matched the surgical field. AR-based marking could be very useful in future LVA.

Application of Photoacoustic Imaging for Lymphedema Treatment

Background  Lymphatic vessels are difficult to identify using existing modalities as because of their small diameter and the transparency of the lymph fluid flowing through them.

Methods  Here, we introduce photoacoustic lymphangiography (PAL), a new modality widely used for lymphedema treatment, to observe limb lymphatic vessels. The photoacoustic imaging system used in this study can simultaneously visualize lymphatic vessels and veins with a high resolution (0.2 mm) and can also observe their three-dimensional relationship with each other.

Results  High-resolution images of the lymphatic vessels, detailed structure of the dermal back flow, and the three-dimensional positional relationship between the lymphatic vessels and veins were observed by PAL.

Conclusion  The clear image provided by PAL could have a major application in pre- and postoperative use during lymphaticovenular anastomosis for lymphedema treatment.

Long-term Use of Ultrasound for Locating Optimal LVA Sites: A Descriptive Data Analysis

BACKGROUND

 Preoperative mapping of lymphatic vessels for lymphovenous anastomosis (LVA) surgery is frequently performed by indocyanine green (ICG) lymphography solely; however, other imaging modalities, such as ultrasound (US), might be more efficient, particularly for Caucasian patients. We present our preoperative assessment protocol, experience, and approach of using US for locating optimal LVA sites.

MATERIAL AND METHODS

 Fifty-six (16 males) lymphedema patients who underwent LVA surgery were included in this study, 5 of whom received two LVA operations. In total, 61 LVA procedures with 233 dissected lymphatic vessels were evaluated. Preoperative US was performed by the author S.M. 2 days before intraoperative ICG lymphography. Fluid-predominant lymphedema regions were scanned more profoundly. Skin incisions followed preoperative US and ICG lymphography markings. Detection of lymphatic vessels was compared between ICG lymphography and the US by using the intraoperative verification under the microscope with 20 to 50x magnification as the reference standard.

RESULTS

 Among the dissected lymphatic vessels, 83.3% could be localized by US, and 70% were detectable exclusively by it. In all, 7.2% of US-detected lymphatic vessels could not be found and verified intraoperatively. Among the lymphatic vessels found by US, only 16% were apparent with ICG before skin incision. In total, 23.2% of the dissected lymphatic vessels could be visualized with ICG lymphography preoperatively. Only 9.9% of the lymphatic vessels could be found by ICG alone.

CONCLUSION

 High-frequency US mapping accurately finds functional lymphatic vessels and matching veins. It locates fluid-predominant regions for targeted LVA surgeries. It reveals 3.6 times as many lymphatic vessels as ICG lymphography. In our practice, it has an integral role in planning LVA procedures.

Strategy of harvesting extended thoracodorsal artery perforator flaps for resurfacing the large soft-tissue defects of extremities

BACKGROUND

The authors presented their strategy to harvest extended thoracodorsal artery (TDA) perforator flaps for resurfacing the large soft-tissue defects of extremities.

MATERIALS AND METHODS

Thirty-three free extended TDA perforator flaps were harvested in 33 patients. The mean flap size was 145.2 cm². The maximal flap length and the width were 30 cm and 10 cm, respectively. The color Doppler sonography (CDS) was used for preoperative assessment of perforators. Indocyanine green angiography (ICGA) was used for intraoperative assessment of flap viability in three patients.

RESULTS

The vascular thrombosis, donor-site scar widening, and delayed recipient-site wound healing were not significantly related to the patient and flap characteristics. Flap tip or partial necrosis was significantly related to age and peripheral vascular disease. True positive rate, false negative rate, and positive predictive value of CDS for perforator identification were not different significantly between attending surgeon and residents. In the distance discrepancy of CDS, significant difference was found based on the classifications of perforator size, perforator type, and sonographic operator. The ICGA identified a hypoperfused distal area in a 30 cm long flap.

CONCLUSION

The CDS locates the TDA perforators more precisely when scanned by experienced hands, in larger size or septocutaneous perforators. Using reliable and more perforators, applying muscle-sparing technique, considering suprafascial course of perforator and proper flap orientation are helpful in harvesting extended TDA perforator flaps. ICGA is an option for assessing flap viability, especially in elders and patients with peripheral vascular diseases.

Lymphatic Dysfunction Detected by Multi-lymphosome Indocyanine Green Lymphography and Lymphatic Ultrasound

Investigation into the cause of lower extremity edema is essential for successful treatment; however, it is sometimes difficult to diagnose. In this case report, we present a patient with bilateral lower extremity edema in whom abnormalities were detected with multi-lymphosome indocyanine green (ICG) lymphography and lymphatic ultrasound. An 87-year-old woman underwent total hysterectomy and pelvic lymphadenectomy for uterine cancer when she was 55 years old. Ten years ago, she was prescribed with a diuretic agent for bilateral edema of the lower extremities; however, the edema did not subside. Conventional general examination, including blood tests, electrocardiography, echocardiography, duplex ultrasound for the legs, and lymphoscintigraphy, did not show any significant abnormalities that may occur with lower limb edema. We performed multi-lymphosome ICG lymphography by injecting ICG in the first web space of the foot, the lateral ankle, and the lateral thigh. This helped us detect lymphatic dysfunction in both lower extremities. Additionally, we performed lymphatic ultrasound and found dilated lymphatic vessels in both lower limbs, indicating lymphatic accumulation within these vessels. Injecting ICG into multiple lymphosomes appears to be useful in diagnosing the causes of lower extremity edema as well as evaluating the lymphatic function of those lymphosomes. Furthermore, lymphatic ultrasound can be used to scan the whole lower extremity because it does not rely on the flow of a contrast agent to produce an image. We believe that combining these diagnostic examinations will make it possible to diagnose patients who have previously been misdiagnosed due to insufficient screening measures.

Evaluation of lymphatic vessel diameters in healthy people using lymphatic ultrasound examination

OBJECTIVE

The aim of this study was to examine lymphatic diameters in lower limbs of healthy volunteers in different body positions using lymphatic ultrasound examinations.

METHODS

Thirty-five healthy volunteers participated in this study. Those who had a history of varicose veins in the leg, deep venous thrombosis, or surgery on their legs or abdomen were excluded. We measured the vertical width of the lymphatics with a 33 MHz linear ultrasound probe, at 20 cm above the knee (thigh) and 10 cm below the knee (lower leg). First, the participants were placed supine, then sitting, and then standing. We performed lymphatic ultrasound examinations in each body position. The Student t test was used to compare lymphatic vessel diameters in the supine, sitting, and standing positions. The significance level was set at .05.

RESULTS

Among 35 healthy volunteers, 17 were men and 18 were women. Mean age was 30.9 (range, 23-55) years. The mean body mass index was 21.3 kg/m² (range, 29.0-16.1 kg/m²). We could not detect lymphatic vessels in 1 thigh and 3 lower legs, leaving 69 thighs and 67 lower legs for evaluation. In the thigh, the mean lymphatic diameters in the supine and standing positions were 0.154 mm and 0.150 mm, respectively, which were not significantly different. In the lower leg, the mean lymphatic diameters in the supine, sitting, and standing positions were 0.160 mm, 0.163 mm, and 0.164 mm, respectively, which were not significantly different. In the thigh, the mean lymphatic diameter in the supine position was larger in the men (0.17 mm) than in the women (0.14 mm) (P = .022). Similarly, in the lower leg, the mean lymphatic diameter in the supine position was greater in the men (0.19 mm) than in the women (0.14 mm) (P = .0044). There was no correlation between the supine lymphatic diameters and the age or body mass index of the participants.

CONCLUSIONS

In healthy legs, lymphatic diameters do not change with body positioning. Supine lymphatic vessel diameters are greater in men than in women.

Supermicrosurgical Suture-Stent Technique for A Lymphaticovenular Bypass

Background: Lymphaticovenular anastomosis (LVA) is a challenging procedure and requires a sophisticated supermicrosurgical technique. The aim of this study was to evaluate and establish a discrete supermicrosurgical anastomosis method using the “suture-stent technique”. Methods: Forty-eight LVA sites of twenty patients with lower extremity lymphedema who had undergone LVA between July 2020 and January 2021 were included in this study. LVA was performed with the conventional technique or with the suture-stent technique. The patency of the anastomoses was evaluated using an infrared camera system intraoperatively. The success rate on the first try and the final success rate for each group were compared. Results: After full application of the exclusion criteria, 35 LVAs of 16 patients including 20 limbs were included in the analysis. The ratio of good patency findings after anastomosis in the suture-stent technique group was 100%. The incidences of leakage or occlusion on the first try were statistically greater in the conventional technique group (29.4%) than in the suture-stent technique group (0%) (p = 0.0191). All anastomoses achieved good patency in the final results. Conclusion: With its minimal risk of catching the back wall during the anastomosis, the suture-stent technique can be considered an optimal anastomosis option for LVA.

Genital lymphaticovenous anastomosis (LVA) and leg LVA to prevent the recurrence of genital acquired lymphangiectasia

BACKGROUND

Genital acquired lymphangiectasia (GAL) commonly recurs after simple resection. This study aimed to elucidate the efficacy of lymphaticovenous anastomosis (LVA) in the genital region or legs for preventing GAL recurrence after resection.

METHODS

We retrospectively investigated 25 female patients who underwent GAL resection and LVA, lymphoscintigraphy, and indocyanine green (ICG) lymphography. Isotope or ICG was injected into the leg. Medicine accumulating in the genitals indicates lymphatic flow from the legs to the genitals (type 1). In some cases, we injected ICG into the anus to detect lymphatic flow from the anus to the genitals (type 2). Based on the findings, we selected LVA site (genital or leg).

RESULTS

The mean patient age was 61.4 (range, 42-81) years. Seventeen patients underwent leg LVA only, while eight patients underwent genital LVA. The mean follow-up period was 285 (range, 87-365) days. GAL recurrence was observed in 10 patients (40.0%): three of eight (37.5%) who underwent genital LVA versus seven of 17 (41.2%) who underwent leg LVA. Among patients with type 2 lymphatic vessels, GAL recurrence was observed in two of six (33.3%) who underwent genital LVA versus five of nine (55.6%) who underwent leg LVA.

CONCLUSION

Genital LVA prevented GAL recurrence in patients with type 2 lymphatic flow. Detecting the direction of lymphatic flow around GAL is essential to its successful treatment.

Use of photoacoustic imaging to determine the effects of aging on lower extremity lymphatic vessel function

OBJECTIVE

Aging is one of the causes of primary lymphedema. However, the effects of aging on the lymphatic system are still not completely understood. We investigated the effects of aging on the lymphatic vessels in the lower extremities of healthy volunteers using photoacoustic imaging.

METHODS

Healthy volunteers who underwent photoacoustic lymphangiography between March 2018 and January 2019 were enrolled. To visualize lymphatics, indocyanine green (ICG, 5.0 mg/mL) was injected subcutaneously into the first and fourth web spaces of the foot and under the lateral malleolus. Subsequently, near-infrared fluorescence lymphography was performed to confirm good ICG flow, and photoacoustic lymphangiography was performed on the medial side of the lower leg. Neodymium-doped yttrium aluminum garnet laser irradiation at 797 and 835 nm, the optimal wavelengths for visualizing ICG and blood, was applied. The number of lymphatic vessels shown at areas 10 cm (L10) and 20 cm (L20) cranially from the internal malleolus was counted.

RESULTS

Nineteen healthy volunteers (4 males and 15 females) were enrolled in the study. Their mean age was 42.9 ± 12.8 years. One volunteer was bilaterally imaged; 15 left lower limbs and 5 right lower limbs were imaged. The number of lymphatic vessels visualized increased with age. There were strong positive correlations between age and L10 (R = 0.729, P < .001) and between age and L20 (R = 0.570, P = .009).

CONCLUSIONS

Photoacoustic imaging indicates that the number of lymphatic vessels increases with age. Lymphatic stasis resulted in visualization of not only normal drainage pathways but also nonfunctional lymphatic pathways.

Changing the Paradigm: Lymphovenous Anastomosis in Advanced Stage Lower Extremity Lymphedema

BACKGROUND

Traditionally, lymphovenous anastomosis is not routinely performed in patients with advanced stage lymphedema because of difficulty with identifying functioning lymphatics. This study presents the use of duplex ultrasound and magnetic resonance lymphangiography to identify functional lymphatics and reports the clinical outcome of lymphovenous anastomosis in advanced stage lower extremity lymphedema patients.

METHODS

This was a retrospective study of 42 patients (50 lower limbs) with advanced lymphedema (late stage 2 or 3) that underwent functional lymphovenous anastomoses. Functional lymphatic vessels were identified preoperatively using magnetic resonance lymphangiography and duplex ultrasound.

RESULTS

An average of 4.64 lymphovenous anastomoses were performed per limb using the lymphatics located in the deep fat underneath the superficial fascia. The average diameter of lymphatic vessels was 0.61 mm (range, 0.35 to 1 mm). The average limb volume was reduced 14.0 percent postoperatively, followed by 15.2 percent after 3 months, and 15.5 percent after 6 months and 1 year (p < 0.001). For patients with unilateral lymphedema, 32.4 percent had less than 10 percent volume excess compared to the contralateral side postoperatively, whereas 20.5 percent had more than 20 percent volume excess. The incidence of cellulitis decreased from 0.84 per year to 0.07 per year after surgery (p < 0.001).

CONCLUSION

This study shows that functioning lymphatic vessels can be identified preoperatively using ultrasound and magnetic resonance lymphangiography; thus, lymphovenous anastomoses can effectively reduce the volume of the limb and improve subjective symptoms in patients with advanced stage lymphedema of the lower extremity.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Classification of the lymphatic pathways in each lymphosome based on multi-lymphosome indocyanine green lymphography: Saphenous, calf, and thigh (SCaT) classification

BACKGROUND

The anatomy of the lymphatic vessels in the extremities is not completely understood. The aim of this study was to elucidate the patterns of the lymphatic pathways of each lymphosome in lymphedematous legs.

METHODS

We performed a retrospective study on 630 lymphosomes from 105 patients with leg lymphedema. The mean age of the subjects was 58.9 (range: 20-91) years, and the mean duration of lymphedema was 8.8 (range: 1-91) years. In indocyanine green (ICG) lymphography, we injected ICG into the multi-lymphosome: the first web space of the foot (saphenous lymphosome), lateral ankle (lateral calf lymphosome), and lateral knee (lateral thigh lymphosome). We established the saphenous, calf, and thigh (SCaT) classification based on the lymphatic location: lymphatic vessels on the medial side (type 1) and lymphatic vessels in other locations (type 2).

RESULTS

In the saphenous lymphosome, 157 lymphatics (95.5%) were type 1. In the lateral calf lymphosome, 164 lymphatics (29.9%) were type 1. In the lateral thigh lymphosome, 148 lymphatics (16.9%) were type 1. The percentage of type 2 lymphatic vessels increased as the lymphoscintigraphic staging progressed.

CONCLUSIONS

The lymphatic vessels in the lymphedematous legs shifted from the medial to the lateral side and finally disappeared in all lymphosomes as lymphedema worsened. We propose the SCaT classification to describe the condition of the lymphatic vessels in each lymphosome with the hope that it becomes a common staging system for sharing information on lymphedema severity among interdisciplinary medical professionals.

Comparison of Various Kinds of Probes for Lymphedematous Limbs

Recently, there has been a growing interest in the use of lymphatic ultrasound in the preoperative investigation of lymphaticovenous anastomosis. The device used for the performance of lymphatic ultrasound varies among surgeons. In this case report, we compared several probes (18 MHz, 24 MHz, and 33 MHz linear probes) in 2 cases, to detect the lymphatic vessels in the lymphedematous limbs. In the upper limb lymphedema case, the lymphatic vessels were located at a depth of <5 mm. They could be better observed with the 33 MHz probe than with the 18 MHz probe. The probe with a high frequency (33 MHz) and high resolution seemed to be suitable for superficial layers <5 mm in depth. On the other hand, the probe of 33 MHz was not appropriate for the lymphedematous lower limb because the lymphatic vessels are usually located at around a depth of 1 cm. When comparing the 18 MHz and 24 MHz probes in observing the lymphatic vessels in the lower limb, the 24 MHz probe seemed more suitable because of its higher resolution. Among these options, the 33 MHz probe was suitable for lymphedematous upper limbs, and the 24 MHz probe was suitable for lymphedematous lower limbs.

Imaging technology of the lymphatic system

The lymphatic system plays critical roles in tissue fluid homeostasis and immunity and has been implicated in the development of many different pathologies, ranging from lymphedema, the spread of cancer to chronic inflammation. In this review, we first summarize the state-of-the-art of lymphatic imaging in the clinic and the advantages and disadvantages of these existing techniques. We then detail recent progress on imaging technology, including advancements in tracer design and injection methods, that have allowed visualization of lymphatic vessels with excellent spatial and temporal resolution in preclinical models. Finally, we describe the different approaches to quantifying lymphatic function that are being developed and discuss some emerging topics for lymphatic imaging in the clinic. Continued advancements in lymphatic imaging technology will be critical for the optimization of diagnostic methods for lymphatic disorders and the evaluation of novel therapies targeting the lymphatic system.

Visualization of Lymphatic Vessels Using Photoacoustic Imaging

Lymphedema occurs when interstitial fluid and fibroadipose tissues accumulate abnormally because of decreased drainage of lymphatic fluid as a result of injury, infection, or congenital abnormalities of the lymphatic system drainage pathway. An accurate anatomical map of the lymphatic vasculature is needed not only for understanding the pathophysiology of lymphedema but also for surgical planning. However, because of their limited spatial resolution, no imaging modalities are currently able to noninvasively provide a clear visualization of the lymphatic vessels. Photoacoustic imaging is an emerging medical imaging technique that provides unique scalability of optical resolution and acoustic depth of penetration. Moreover, light-absorbing biomolecules, including oxy- and deoxyhemoglobin, lipids, water, and melanin, can be imaged. Using exogenous contrast agents that are taken up by lymphatic vessels, e.g., indocyanine green, photoacoustic lymphangiography, which has a higher spatial resolution than previous imaging modalities, is possible. Using a new prototype of a photoacoustic imaging system with a wide field of view developed by a Japanese research group, high-resolution three-dimensional structural information of the vasculatures was successfully obtained over a large area in both healthy and lymphedematous extremities. Anatomical information on the lymphatic vessels and adjacent veins provided by photoacoustic lymphangiography is helpful for the management of lymphedema. In particular, such knowledge will facilitate the planning of microsurgical lymphaticovenular anastomoses to bypass the excess fluid component by joining with the circulatory system peripherally. Although challenges remain to establish its implementation in clinical practice, photoacoustic lymphangiography may contribute to improved treatments for lymphedema patients in the near future.

Diagnosis of Lymphatic Dysfunction by Evaluation of Lymphatic Degeneration with Lymphatic Ultrasound

Background: The standard examination for diagnosing lymphedema is lymphoscintigraphy, which has a disadvantage in versatility and radiation exposure. We have reported the usefulness of echography in observing the lymphatic degeneration. The purpose of this study was to investigate the usefulness of lymphatic ultrasound in diagnosing lymphedema. Methods and Results: The study included 14 patients (28 lower limbs) who underwent lymphaticovenous anastomosis for lower limb lymphedema. Preoperative echography with a common 18-MHz linear probe was used to detect lymphatic vessels. We evaluated abnormal expansion or sclerosis of lymphatic vessels in the medial legs, which indicated the presence of lymphedema. We proposed the method "D-CUPS" on how to detect and observe the lymphatic vessels. We then performed indocyanine green (ICG) lymphography to diagnose lymphedema. The results of examination were compared. Stage 1 lymphedema was diagnosed in 9 limbs, Stage 2a in 7, Stage 2b in 8, and Stage 3 in 4. Lymphatic vessel detection was possible in all 28 medial thighs and in 27 medial lower legs. The sensitivity and specificity for diagnosis of lymphedema based on echography of the medial leg were 95.0% and 100.0%, respectively. The accuracy rate was 94.6%. We could detect lymphatic vessels with echography in 39 of 54 areas that failed detection using lymphoscintigraphy or ICG lymphography (72.2%). Conclusion: The location and degeneration of lymphatic vessels in lymphedematous limbs can be evaluated with a commonly used ultrasound device. Although exclusion of comorbidities is still necessary, lymphatic ultrasound has potential for use in diagnosis of lymphedema or lymphatic dysfunction.

Lymphaticovenous anastomosis for advanced-stage lower limb lymphedema

BACKGROUND

Early-stage lymphedema patients are said to be candidates for lymphaticovenous anastomosis (LVA). The progressions in the preoperative examinations have made it possible to find the suitable lymphatic vessels even in advanced-stage lymphedema. The aim of this study was to elucidate the surgical effect of LVA in cases of advanced-stage lymphedema.

METHODS

We evaluated 42 limbs of 34 patients with lymphoscintigraphic type 4 or 5. A mean disease duration was 7.5 ± 6.5 years. We performed multi-lymphosome indocyanine green (ICG) lymphography preoperatively to detect the saphenous lymphatics, the lateral calf lymphatics, and the lateral thigh lymphatics. We also performed ultrasound to detect the subcutaneous veins and the dilated lymphatic vessels. The pre- and postoperative evaluation was made by the sum of circumference measurements at 6 points per limb.

RESULTS

The mean number of anastomosis per limb was 2.8 (range, 1-5). Of the 41 limbs for which we performed ICG lymphography, we found the saphenous lymphatics in 29 limbs (70.7%), lateral calf lymphatics in 28 limbs (68.3%), and lateral thigh lymphatics in 21 limbs (51.2%). We found at least 1 linear pattern in ICG lymphography for 39 limbs (95.1%). The mean pre- and postoperative circumference (sum of 6 points) were 221.7 ± 4.9 cm and 215.9 ± 4.9 cm, which was significantly reduced (p < .01).

CONCLUSIONS

LVA was effective for advanced-stage lymphedema patients. An adequate preoperative examination with plural imaging methods seems helpful for achieving a successful surgical result.

Compression Pressure Variability in Upper Limb Multilayer Bandaging Applied by Lymphedema Therapists

Background: Multilayer bandaging (MLB) is often used for lymphedema treatment. Even experienced lymphedema therapists have difficulty applying bandages correctly. The aim of this study was to demonstrate upper limb MLB pressure variability applied by lymphedema therapists. Methods and Results: Twenty-four lymphedema therapists were asked to apply MLB to the healthy volunteer's upper limb. The participants consisted of 20 females and 4 males with a mean age of 43.4 (range: 24-62) years. They included licensed massage therapists, nurses, a judo therapist, an occupational therapist, and a medical doctor. Twenty therapists (83.3%) had clinical experience applying MLB. Compression pressure was measured with PicoPress at 5 cm proximal to the wrist, immediately after the application (phase 1) and after exercise (phase 2). The mean MLB pressure was 67.7 ± 5.0 mmHg in phase 1 and 55.3 ± 4.1 mmHg in phase 2, which were significantly different (p = 1.2 × 10^-10). There was a weak negative correlation between how long the therapist had been practicing MLB and MLB pressure (R = 0.29). Seventeen participants (70.8%) expressed that they had a target pressure in mind when performing MLB. Among the 17 participants, there was no correlation between the target and actual pressures (R = -0.055). Only three participants (17.6%) had an actual MLB pressure within 5 mmHg of their target. Conclusions: The mean MLB pressure was 55.3 ± 4.1 mmHg, which was thought to be too high for the upper limb. Education about applying appropriate MLB pressures to the limbs is necessary.

Magnetic resonance lymphography as three-dimensional navigation for lymphaticovenular anastomosis in patients with leg lymphedema

BACKGROUND

Precise mapping of functional lymphatic vessels is essential for successful lymphaticovenular anastomosis (LVA). This study aimed to clarify the precision of magnetic resonance lymphography (MRL) in detecting lymphatic vessels prior to LVA.

METHODS

Eighteen patients with leg lymphedema were recruited for this prospective study. All patients underwent MRL before LVA to obtain three-dimensional coordinates of lymphatic vessels from MRL images. The precision of MRL for detecting lymphatic vessels was evaluated and compared with those of other contrast techniques.

RESULTS

Twenty legs from 18 patients were analyzed. A total of 40 skin incisions were made, 32 of which were determined by MRL. The precision of MRL to detect lymphatic vessels was 94%. With the addition of MRL, the number of lymphatic vessels identified preoperatively was increased as compared with indocyanine green lymphography (ICG-L) alone. Assuming a detection sensitivity of MRL for lymphatic vessels of 1, those of other contrast techniques were 0.90 for ICG-L under microscopy, 0.73 for patent blue staining, and 0.43 for ICG-L before incision. Whereas ICG-L before incision could not detect lymphatic vessels at depths greater than 17.0 mm, all deeper anastomosed lymphatic vessels were identified by MRL.

CONCLUSION

Lymphatic vessels enhanced on MRL can be reliably identified intraoperatively. MRL is a promising preoperative examination in LVA that can selectively depict suitable lymphatic vessels even in deep tissue layers.

Change of the Lymphatic Diameter in Different Body Positions

Background: Until now, lymphatic ultrasound was performed with the patients in the prone position. The aim of this study was to evaluate the change in the lymphatic diameter in different body positions. Methods: We performed a retrospective study. We performed indocyanine green (ICG) lymphography and lymphatic ultrasound as a pre-operative examination for lymphaticovenous anastomosis (LVA). ICG was injected at three lymphosomes per limb (the saphenous lymphatics, lateral thigh lymphatics, and lateral calf lymphatics). For the lymphatic ultrasound, a commonly used ultrasound device with an 18 MHz linear probe was employed. We measured the lymphatic diameter in the designed LVA sites in prone, sitting, and upright position. Results: We investigated 61 limbs of 31 female patients with lower limb lymphedema. The mean age was 62.0 (range: 42-86) years. We measured the lymphatic diameter at 78 sites in the thigh and 76 sites in the lower leg. In the thigh, the mean lymphatic diameters in the supine and upright positions were 0.43 ± 0.02 mm and 0.40 ± 0.02 mm, respectively, with no significant difference (p = 0.10). In the lower leg, the mean lymphatic diameters in the supine, sitting, and upright positions were 0.68 ± 0.04 mm, 0.63 ± 0.04 mm, and 0.63 ± 0.04, respectively. A significant decrease was noted between the supine and sitting positions (p = 0.02). Conclusions: The lymphatic diameter in the lymphedematous lower limbs tended to decrease when the patients changed their body position from supine to the sitting or upright positions.

A Novel Approach to Subcutaneous Collecting Lymph Ducts Using a Small Diameter Wire in Animal Experiments and Clinical Trials

Background: While performing microsurgery, including lymphaticovenous anastomosis (LVA) for chronic limb lymphedema, it is a common procedure to identify the subcutaneous collecting lymph ducts with near-infrared fluorescence lymphangiography (NIR) using indocyanine green. However, due to limitations such as minimum observable depth, only a few lymphatic ducts can be identified with this procedure. Hence, we developed a new smaller-diameter "lymphatic wire" (LW) that could be inserted directly into lymphatic collecting ducts of the limbs, enabling accurate identification and localization. Methods and Results: First, used the LW on the hind limbs of 6 swine, and 36 porcine lymphatic collecting ducts were identified, the outer diameter of which varied from 0.3-0.7 mm (mean 0.41 ± 0.11 mm). We could insert the LW after creating a side opening in 30 of these ducts. We encountered no difficulties during the procedure. In the pathological examination, adverse events such as valve dysfunction and perforation were not identified. Based on the results, a clinical evaluation of the LW was performed in two patients with lower extremity lymphedema, and the LW helped us identify lymphatic ducts in the subcutaneous layer, even at the sites where the NIR had proved ineffective. Conclusion: Based on our results, we suggest that the procedure for identifying lymphatic vessels using the newly developed LW is a useful technique that can be utilized before performing a LVA for lymphedema. However, further clinical study is required to develop this device and technique, for wider clinical application in the future.

Application of imaging in lymphedema surgical therapies

Lymphedema is a chronic, progressive disease caused by primary or secondary reasons. It is currently uncurable and conservative compression therapy is generally applied. Lymphovenous anastomosis and vascularized lymph node transfer (VLNT) are two main surgical treatment that are used in addition to conservative therapy. Lymphovenous anastomosis involves the anastomosing remaining functional lymphatic vessels to vein. When the lymphatic vessels are greatly damaged and in no case can they be used for anastomosis, VLNT provide the affected area with lymph nodes from elsewhere to restore the drainage function. During all these procedures, a clear image to identify related lymphatic structures and venous vessels can be greatly useful for preoperative planning, intraoperative navigation, and postoperative evaluation. Lymphoscintigraphy used to be the gold standard in evaluating lymphedema and mapping lymphatic systems. But due to the downside of radiation, invasive operation and complication, other modalities are gaining attention. In this article, we reviewed the application of Indocyanine green (ICG) lymphography, ultrasound, magnetic resonance lymphography (MRL), and single-photon emission computed tomography-computed tomography (SPECT-CT) in the field of surgical therapy in lymphedema.

Subcutaneous Lymphatic Vessels in the Lower Extremities: Comparison between Photoacoustic Lymphangiography and Near-Infrared Fluorescence Lymphangiography

Background Detailed visualization of the lymphatic vessels would greatly assist in the diagnosis and monitoring of lymphatic diseases and aid in preoperative planning of lymphedema surgery and postoperative evaluation. Purpose To evaluate the usefulness of photoacoustic imaging (PAI) for obtaining three-dimensional images of both lymphatic vessels and surrounding venules. Materials and Methods In this prospective study, the authors recruited healthy participants from March 2018 to January 2019 and imaged lymphatic vessels in the lower limbs. Indocyanine green (5.0 mg/mL) was injected into the subcutaneous tissue of the first and fourth web spaces of the toes and below the lateral malleolus. After confirmation of the lymphatic flow with near-infrared fluorescence (NIRF) imaging as the reference standard, PAI was performed over a field of view of 270 × 180 mm. Subsequently, the number of enhancing lymphatic vessels was counted in both proximal and distal areas of the calf and compared between PAI and NIRF. Results Images of the lower limbs were obtained with PAI and NIRF in 15 participants (three men, 12 women; average age, 42 years ± 12 [standard deviation]). All participants exhibited a linear pattern on NIRF images, which is generally considered a reflection of good lymphatic function. A greater number of lymphatic vessels were observed with PAI than with NIRF in both the distal (mean: 3.6 vessels ± 1.2 vs 2.0 vessels ± 1.1, respectively; P < .05) and proximal (mean: 6.5 vessels ± 2.6 vs 2.6 vessels ± 1.6; P < .05) regions of the calf. Conclusion Compared with near-infrared fluorescence imaging, photoacoustic imaging provided a detailed, three-dimensional representation of the lymphatic vessels and facilitated an increased understanding of their relationship with the surrounding venules. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Lillis and Krishnamurthy in this issue.

Multilymphosome injection indocyanine green lymphography can detect more lymphatic vessels than lymphoscintigraphy in lymphedematous limbs

BACKGROUND

Sometimes, injecting indocyanine green (ICG) or isotope at distal limbs is insufficient especially in cases with low lymphatic function. The purpose of this study was to elucidate the usefulness of multi-lymphosome injection ICG lymphography.

METHODS

Two hundred and six lower limbs of 103 patients were included. ICG lymphography was performed by injecting ICG in three lymphosomes per limb: dorsum of foot (saphenous lymphatics), the proximal side of the lateral condyle (lateral calf lymphatics), and the lateral side of the superior edge of the knee (lateral thigh lymphatics). We observed the presence or absence of a linear pattern at each injection site with a near-infrared camera. Lymphoscintigraphy was performed by injecting an isotope in the first web space, conventionally. Whole body scintigrams were taken 60 min after injection.

RESULTS

In multi-lymphosome ICG lymphography, the lateral thigh lymphatics were observed as a linear pattern in 75.2% of patients, the lateral calf lymphatics in 72.8%, and the saphenous lymphatics in 84.5% of patients. There was not a significant difference between secondary and primary lymphedema (p = 0.57, 0.77, and 0.56 in the lateral thigh, the lateral calf, and the saphenous lymphatics, respectively). Among the 12 limbs classified as Type 5, at least one linear pattern was found in 10 limbs (83.3%).

CONCLUSIONS

We observed a linear pattern in 83.3% of the limbs that were lymphoscintigraphic Type 5 by using multi-lymphosome ICG lymphography. There is a possibility that the results of this study can increase the number of patients eligible for lymphatico-venous anastomosis (LVA) and increase the success rate of LVA.