title: Anatomic distribution of fluorodeoxyglucose-avid para-aortic lymph nodes in patients with cervical cancer.
abstract: OBJECTIVE
  Conformal treatment of para-aortic lymph nodes (PAN) in cervical cancer allows dose escalation and reduces normal tissue toxicity. Currently, data documenting the precise location of involved PAN are lacking. We define the spatial distribution of this high-risk nodal volume by analyzing fluorodeoxyglucose (FDG)-avid lymph nodes (LNs) on positron emission tomography/computed tomography (PET/CT) scans in patients with cervical cancer.
  
  
  METHODS
  We identified 72 PANs on pretreatment PET/CT of 30 patients with newly diagnosed stage IB-IVA cervical cancer treated with definitive chemoradiation. LNs were classified as left-lateral para-aortic (LPA), aortocaval (AC), or right paracaval (RPC). Distances from the LN center to the closest vessel and adjacent vertebral body were calculated. Using deformable image registration, nodes were mapped to a template computed tomogram to provide a visual impression of nodal frequencies and anatomic distribution.
  
  
  RESULTS
  We identified 72 PET-positive para-aortic lymph nodes (37 LPA, 32 AC, 3 RPC). All RPC lymph nodes were in the inferior third of the para-aortic region. The mean distance from aorta for all lymph nodes was 8.3 mm (range, 3-17 mm), and from the inferior vena cava was 5.6 mm (range, 2-10 mm). Of the 72 lymph nodes, 60% were in the inferior third, 36% were in the middle third, and 4% were in the upper third of the para-aortic region. In all, 29 of 30 patients also had FDG-avid pelvic lymph nodes.
  
  
  CONCLUSIONS
  A total of 96% of PET positive nodes were adjacent to the aorta; PET positive nodes to the right of the IVC were rare and were all located distally, within 3 cm of the aortic bifurcation. Our findings suggest that circumferential margins around the vessels do not accurately define the nodal region at risk. Instead, the anatomical extent of the nodal basin should be contoured on each axial image to provide optimal coverage of the para-aortic nodal compartment.
authors: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
authors: Vinita
authors: V
authors: Takiar
authors: Hiral P
authors: HP
authors: Fontanilla
authors: Patricia J
authors: PJ
authors: Eifel
authors: Anuja
authors: A
authors: Jhingran
authors: Patrick
authors: P
authors: Kelly
authors: Revathy B
authors: RB
authors: Iyer
authors: Charles F
authors: CF
authors: Levenback
authors: Yongbin
authors: Y
authors: Zhang
authors: Lei
authors: L
authors: Dong
authors: Ann
authors: A
authors: Klopp
mesh_terms: D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000378:metabolism / Q000628:therapy; D000328:Adult; D000368:Aged; D001011:Aorta; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000378:metabolism / Q000628:therapy; D059248:Chemoradiotherapy / Q000379:methods; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000378:metabolism; D008207:Lymphatic Metastasis; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D002583:Uterine Cervical Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000628:therapy; D014682:Vena Cava, Inferior
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18