Bile-Duct-Sparing Yttrium-90 Radiation Segmentectomy for a Caudate Lobe Neuroendocrine Tumor Metastasis Using Arterial Flow Redirection: A Case Report
John P. Moody, R. Ethan Evans, Vansh Varma, Tweheyo Ronald, Ranjana Sah, Amogh Verma, Kiyon Naser-Tavakolian, Abin Sajan, Junaid Raja, Venkatesh P. KrishnasamyIntroduction
Radiation segmentectomy delivers ablative yttrium-90 (Y-90) activity to a limited hepatic angiosome for selected neuroendocrine tumor liver metastases. Caudate lobe treatment is technically distinctive because its variable arterial supply may communicate with branches supplying the central biliary tree. Failure to recognize such perfusion can expose the bile duct to nontarget radiation and microsphere deposition.
Case Presentation
A 46-year-old man with a small-bowel neuroendocrine tumor metastatic to the liver, previously treated with right hepatectomy, developed a new 0.8 × 0.8-cm caudate lesion on surveillance imaging. His Eastern Cooperative Oncology Group (ECOG) performance status was 0, and his Albumin-Bilirubin (ALBI) grade was 1. During Y-90 mapping, angiography and cone-beam computed tomography demonstrated a small tumor-feeding branch arising from the proximal caudate artery; the more distal caudate artery also supplied the common bile duct. Technetium-99m macroaggregated albumin (MAA) SPECT/CT demonstrated activity in the intended treatment territory and adjacent common bile duct. Because the tumor-feeding branch could not be catheterized ultraselectively, the distal caudate artery beyond the tumor-feeder origin was coil embolized to redirect flow away from the biliary supply while preserving access to the tumor-feeding branch. Y-90 glass microspheres were administered, and post-treatment SPECT/CT demonstrated activity confined to the targeted caudate territory without detectable activity in the common bile duct. Voxel-based dosimetry demonstrated a D95 of 670 Gy and V400 of 100%. MRI at 1 and 10 months and DOTATATE PET/CT at 14 months demonstrated sustained complete response without biliary stricture or obstruction.
Conclusion
Mapping angiography, cone-beam CT, MAA SPECT/CT, and selective arterial flow redirection can be integrated when caudate tumor perfusion overlaps with central biliary arterial supply. Recognizing shared perfusion before Y-90 delivery may permit modification of the treatment angiosome and reduce unintended biliary irradiation in appropriately selected anatomy.