Use of Magnetic Resonance Angiography to Inform Vascularized Supraclavicular Lymph Node Transfer Jillian Lazor, M.D. 1 Catherine Chang, M.D. 2 Suhail Kanchwala, M.D. 2 Joel Stein, M.D., Ph.D. 1 EP Department of Radiology; The Hospital of the University of Pennsylvania; Philadelphia, PA 2 Department of Plastic Surgery; The Hospital of the University of Pennsylvania; Philadelphia, PA

The authors have no conflicts of interest. Disclosures

Purpose Vascularized lymph node transfer is a microsurgical technique shown to improve symptoms of lymphedema. The technique involves the transfer of a flap containing donor site lymph nodes, fat, and vessels to a site of lymphatic obstruction. At the recipient site, the flap reduces lymphedema through restoration of lymphatic flow and promotion of lymphangiogensis (1).

Purpose Superficial inguinal flaps are the most researched and commonly used, primarily for upper extremity lymphedema (1). Alternative donor sites are necessary to alleviate lower extremity lymphedema.

Purpose Right supraclavicular flaps offer an attractive alternative given fairly reliable anatomy, good cosmesis, and low risk of secondary lymphedema or nerve damage. A right supraclavicular flap includes the transverse cervical artery (TCA), transverse cervical vein, and part of the external jugular vein, which are transferred to the dorsum of the affected foot or ankle (2,3).

Purpose Schematic of a right supraclavicular flap dissection.

TCA Suprascapular Inferior thyroidal & Ascending cervical TCA classically arises from the thyrocervical trunk. Variability exists in the vascular and venous anatomy. Purpose

This study uses gadolinium-enhanced neck MRA to assess size and distribution of right supraclavicular lymph nodes in relation to the TCA, factors that could affect surgical approach. The study evaluates the hypothesis that lymph nodes are greater in number and size closer to the TCA origin and investigates variability in TCA origin and branching.

Materials and Methods We retrospectively reviewed gadolinium enhanced neck magnetic resonance angiography (MRA) examinations performed at our institution from January through September 2014.

Materials and Methods Patients with a history of supraclavicular mass or surgery, metastatic cancer, lymphoma, or systemic inflammatory disorder were excluded. Examinations degraded by patient motion or incompletely covering the supraclavicular fossa were also excluded. These criteria yielded 30 studies of unique patients.

Materials and Methods Our standard neck MRA protocol uses coronal 3D acquisitions with 0.86 or 1.2 mm slice thickness at 1.5T or 3T. Pre-contrast as well as arterial and venous phase post-contrast images are acquired.

Materials and Methods On each study, the right TCA was identified (yellow arrow) and the diameter at its origin was measured.

Materials and Methods Anatomy of the TCA and thryocervical trunk was categorized as classical or variant. Classical anatomy. TCA arises from the thyrocervical trunk (yellow arrow). Variant anatomy. TCA arises from the subclavian artery (yellow arrow).

Materials and Methods Right supraclavicular lymph nodes were identified on pre-contrast T1-weighted images as low signal intensity foci (yellow arrows) in a background of hyperintense fat and measured in long axis. Distance of each node from the TCA origin was measured in three dimensions.

Results A total of 142 lymph nodes were identified, with 4.7 ± 2.2 lymph nodes per patient. Lymph nodes averaged 5.2 ± 2 mm in size. The TCA origin measured 2.7 mm ± 0.8 mm in average diameter.

Results With respect to the TCA origin, all lymph nodes were lateral, 96% were superior, and 78% were dorsal. Distance from the TCA origin was 37 ± 13 mm on average, with a median of 38 mm. There was no trend towards increased node number or size in proximity to the TCA origin.

Results Scatterplot depicting the location of the right supraclavicular lymph nodes, in three dimensions, in our 30 patients, relative to the origin of the TCA. The origin of the TCA is defined as (0,0,0).

Results Scatterplot demonstrating long-axis size of lymph nodes (mm) vs. distance from TCA origin (mm). No correlation between size and distance is identified. Long axis size of lymph node (mm) Distance from TCA origin (mm)

Weiglein et al. Clinical Anatomy 2005 (3) Results In a prior study of 498 cadavers, Weiglein et al. describe the variability in TCA naming, origin and branching that can complicate musculocutaneous flap planning. The TCA, or superficial cervical artery (C) in their nomenclature, may arise from the thyrocervical trunk or separately from the SCA. The deep branch or dorsal scapular (D) artery as well as the suprascapular (S) artery may have the same or separate origins.

10%(3)13%(4)0% 10%(3)7%(2) 33%(10)27%(8)0% Results Using enhanced neck MRA, we were also able to identify and document the variability in origin and branching of vessels in the posterior triangle. Frequency of different variants according to the same nomenclature are indicated in blue. Note that 7 cases (23%) had separate origin of the TCA from the SCA (E and H). Differences in frequencies may be related to our smaller sample size. Weiglein et al. Clinical Anatomy 2005 (3)

Conclusions Contrast-enhanced MRA can be used to delineate the anatomy of the TCA as well as the number and location of supraclavicular lymph nodes.

Conclusions Our study identified an average of 2.1 more lymph nodes per patient than found in an ongoing study of cadaver flaps by two of our authors. This suggests that pre-surgical MRA could be helpful for determining dissection margins and maximizing lymph node harvest.

Conclusions Our study identified variant TCA anatomy including separate origin from the SCA as reported in the anatomical and surgical literature (4,5). Pre-surgical knowledge of vascular anatomy may be useful, as mean harvest time in the setting of variant TCA anatomy is minutes longer, due to deeper and more technically difficult dissection (4).

Conclusions Pre-operative MRA, therefore, could be helpful in assessing site suitability or ease of transfer based on lymph node number and vascular variability. In the future, imaging protocols could be optimized for evaluation of the right supraclavicular neck.

References 1.Raju A, Chang DW. Vascularized lymph node transfer for treatemtn of lymphedema: A comprehensive literature review. Ann Surg. 2014; 00: Althubaiti GA, Crosby MA, Chang DW. Vascularized supraclavicular lymph node transfer for lower extremity lymphedema treatment. Plast Reconstr Surg. 2013; 131: 133e-134e. 3.Weiglein AH, Moriggl B, Schalk C, et al. Arteries in the posterior triangle in man. Clin Anatomy. 2005; 18: Sapountzis S, Singhal D, Rashid A, et al. Lymph node flap based on the right transverse cervical artery as a donor site for lymph node transfer. Ann Plast Surg. 2014; 73: Cordova A, D’Arpa S, Pirrello R, et al. Anatomic study on the transverse cervical vessels perforators in the lateral triangle of the neck and harvest of a new flap: the free supraclavicular transverse cervical artery perforator flap. Surg Radiol Anat. 2009; 31: