Validated guidelines for tumor delineation on magnetic resonance imaging for laryngeal and hypopharyngeal cancer.
BACKGROUND
Validation of magnetic resonance imaging (MRI) and development of guidelines for the delineation of the gross tumor volume (GTV) is of utmost importance to benefit from the visibility of anatomical details on MR images and to achieve an accurate GTV delineation. In the ideal situation, the GTV delineation corresponds to the histopathologically determined 'true tumor volume'. Consequently, we developed guidelines for GTV delineation of laryngeal and hypopharyngeal tumors on MRI and determined the accuracy of the resulting delineation of the tumor outline on histopathology as gold standard.


METHODS
Twenty-seven patients with T3 or T4 laryngeal/hypopharyngeal cancer underwent a MRI scan before laryngectomy. Hematoxylin and eosin sections were obtained from surgical specimens and tumor was delineated by one pathologist. GTV was delineated on MR images by three independent observers in two sessions. The first session (del1) was performed according to clinical practice. In the second session (del2) guidelines were used. The reconstructed specimen was registered to the MR images for comparison of the delineated GTVs to the tumor on histopathology. Volumes and overlap parameters were analyzed. A target margin needed to assure tumor coverage was determined.


RESULTS
The median GTVs (del1: 19.4 cm3, del2: 15.8 cm3) were larger than the tumor volume on pathology (10.5 cm3). Comparable target margins were needed for both delineation sessions to assure tumor coverage. By adding these margins to the GTVs, the target volumes for del1 (median: 81.3 cm3) were significantly larger than for del2 (median: 64.2 cm3) (p ≤ 0.0001) with similar tumor coverage.


CONCLUSIONS
In clinical radiotherapy practice, the delineated GTV on MRI is twice as large as the tumor volume. Validated delineation guidelines lead to a significant decrease in the overestimation of the tumor volume.
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Elise Anne
EA
Jager
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Hans
H
Ligtenberg
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Joana
J
Caldas-Magalhaes
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Tim
T
Schakel
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Marielle E
ME
Philippens
b Department of Radiology , University Medical Center Utrecht , Utrecht , The Netherlands.
Frank A
FA
Pameijer
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Nicolien
N
Kasperts
c Department of Pathology , University Medical Center Utrecht , Utrecht , The Netherlands.
Stefan M
SM
Willems
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Christiaan H
CH
Terhaard
a Department of Radiation Oncology , University Medical Center Utrecht , Utrecht , The Netherlands.
Cornelis P
CP
Raaijmakers
D000368:Aged; D005260:Female; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D007822:Laryngeal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D007825:Laryngectomy; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D017410:Practice Guidelines as Topic; D047368:Tumor Burden