Pelvic lymph node topography for radiotherapy treatment planning from ferumoxtran-10 contrast-enhanced magnetic resonance imaging.
OBJECTIVE
To define a population-based pelvic lymph node clinical target volume (CTV) for radiotherapy treatment planning using magnetic resonance (MR) imaging and the ultrasmall superparamagnetic iron oxide lymph node contrast agent ferumoxtran-10.


METHODS
A total of 55 eligible patients with endometrial, cervical, prostate, or bladder cancer underwent MR imaging sessions before and after contrast administration on 2 consecutive days. Ferumoxtran-10 was administered immediately after the first scan. The three-dimensional spatial distribution of the pelvic lymph nodes was determined in relation to adjacent vessels and other musculoskeletal landmarks, from which guidelines for determining a nodal CTV in individual patients were developed.


RESULTS
On average, 30 lymph nodes (range, five to 62 nodes) were identified in each patient. The distribution of nodal distances to the closest artery or vein was observed to vary in different anatomic regions. Symmetrical three-dimensional margins of expansion around the distal para-aortic (12 mm), common iliac (10 mm), external iliac (9 mm), and internal iliac (10 mm) vessels, drawn in continuity with a 12-mm expansion anterior to the sacrum and a 22-mm expansion medial to the pelvic sidewall, were shown to encompass the majority of detectable lymph nodes in most patients.


CONCLUSIONS
Use of MR lymphography with ferumoxtran-10 provides an objective description of lymph node locations for radiotherapy planning. Use of this nodal CTV model in clinical practice could ensure a high probability of encompassing the regions at risk of harboring metastatic disease while minimizing the dose to adjacent normal tissues.
Dinniwell
Robert
R
Radiation Medicine Program, Princess Margaret Hospital/Ontario Cancer Institute, University Health Network, Toronto, Canada.
Chan
Philip
P
Czarnota
Gregory
G
Haider
Masoom A
MA
Jhaveri
Kartik
K
Jewett
Michael
M
Fyles
Anthony
A
Jaffray
David
D
Milosevic
Michael
M
D000368:Aged; D000369:Aged, 80 and over; D001012:Aorta, Abdominal / Q000033:anatomy & histology; D003287:Contrast Media; D003911:Dextrans; D016889:Endometrial Neoplasms / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D052203:Ferrosoferric Oxide; D006801:Humans; D007083:Iliac Artery / Q000033:anatomy & histology; D007084:Iliac Vein / Q000033:anatomy & histology; D007501:Iron; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D008488:Medical Illustration; D008875:Middle Aged; D010087:Oxides; D010386:Pelvic Neoplasms / Q000473:pathology*; D010388:Pelvis; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy; D001749:Urinary Bladder Neoplasms / Q000473:pathology / Q000532:radiotherapy; D002583:Uterine Cervical Neoplasms / Q000473:pathology / Q000532:radiotherapy
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide