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BACKGROUND:Vascularized lymph node transfer (VLNT) has become an increasingly popular treatment option for patients with lymphedema. Although imaging is commonly used in perforator flap planning, there is very little in the literature regarding its role in VLNT. Magnetic resonance angiography (MRA) provides a wealth of practical information directly relevant to pre-operative assessment, donor site selection, and treatment of the recipient site when performing lymph node transfer.
Pre-operative selection of the optimal donor site is complicated by variability in the quantity of lymph nodes available and their vascular supply. Recipient site assessment is also a critical step in avoiding potential pitfalls. Prior surgery and radiation may result in a vessel-depleted recipient site requiring an alteration in surgical planning. Pre-existing stenosis of the venous outflow, if unrecognized, can negatively impact the outcome of the procedure. In longstanding lymphedema, fat hypertrophy can occur. The relative fluid to fat content may be difficult to assess in the affected limb. Since only the fluid component is treated by VLNT, the presence of extensive fat hypertrophy may alter the surgical plan. Postoperatively, it is important to quantify the number of viable lymph nodes transferred to correlate the surgery with clinical outcomes.
We have performed high resolution MRA using Gadofosveset Trisodium in all patients undergoing VLNT and report on the utility of this modality in surgical decision-making and evaluating outcomes.
METHODS:MRA of recipient and potential donor sites was performed using a 1.5 Tesla MR system (GE HDx platform 15.0 or higher, Waukesha WI) with an 8-channel phased array coil. Gadofosveset trisodium (up to 10 cc) was injected peripherally at a rate of 2 cc per second. Image post-processing was performed on a separate workstation (Vital Images, Minnetonka, MN). Forty-two patients underwent imaging for VLNT from the cervical, axillary or inguinal region to the upper or lower extremity. MRA of the recipient extremity was also performed 1 year post-operatively to assess the viability and quantity of transferred nodes.
RESULTS:MRA clearly delineated both donor and recipient site anatomy which altered the surgical plan in 10 patients. Proximal high grade venous stenosis was identified in 3 patients and successfully treated with extensive lysis of the surrounding scar tissue. Five patients had vessel-depleted recipient sites requiring alteration in the anastomotic configuration including one patient requiring axillary vein reconstruction with vein graft. Donor lymph node harvest is typically performed contralateral to the recipient site, but in two patients, the ipsilateral donor site was selected because of more preferable nodal anatomy identified on MRA. Finally, the relative volume of fluid versus fat was readily seen with volume calculations performed as well. Post-operative MRA confirmed the quantity of viable lymph nodes transferred.
CONCLUSIONS:VLNT requires meticulous planning and patient selection to ensure safe and successful transfer. MRA using Gadofosveset Trisodium provides high resolution images that facilitate patient selection, surgical planning and assessment of outcomes in VLNT.