Diffusion-weighted MRI for nodal staging of head and neck squamous cell carcinoma: impact on radiotherapy planning.
OBJECTIVE
To evaluate the use of diffusion-weighted magnetic resonance imaging (DW-MRI) for nodal staging and its impact on radiotherapy (RT) planning.


METHODS
Twenty-two patients with locally advanced head and neck squamous cell carcinoma underwent contrast-enhanced computed tomography (CT), as well as MRI (with routine and DW sequences) prior to neck dissection. After topographic correlation, lymph nodes were evaluated microscopically with prekeratin immunostaining. Pathology results were correlated with imaging findings and an RT planning study was performed for these surgically treated patients. One set of target volumes was based on conventional imaging only, and another set was based on the corresponding DW-MRI images. A third reference set was contoured based solely on pathology results.


RESULTS
A sensitivity of 89% and a specificity of 97% per lymph node were found for DW-MRI. Nodal staging agreement between imaging and pathology was significantly stronger for DW-MRI (kappa = 0.97; 95% confidence interval [CI], 0.84-1.00) than for conventional imaging (kappa = 0.56; 95% CI, 0.16-0.96; p = 0.019, by McNemar's test). For both imaging modalities, the absolute differences between RT volumes and those obtained by pathology were calculated. Using an exact paired Wilcoxon test, the observed difference was significantly larger for conventional imaging than for DW-MRI for nodal gross tumor volume (p = 0.0013), as well as for nodal clinical target volume (p = 0.0415) delineation.


CONCLUSIONS
These results suggest that DW-MRI is superior to conventional imaging for preradiotherapy nodal staging of head and neck squamous cell carcinoma, and provides a potential impact on organsparing and tumor control.
Dirix
Piet
P
Department of Radiation Oncology, Leuvens Kankerinstituut (LKI), University Hospitals Leuven, Campus Gasthuisberg, Leuven, Belgium. piet.dirix@uzleuven.be
Vandecaveye
Vincent
V
De Keyzer
Frederik
F
Op de Beeck
Katya
K
Poorten
Vincent Vander
VV
Delaere
Pierre
P
Verbeken
Eric
E
Hermans
Robert
R
Nuyts
Sandra
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000473:pathology* / Q000601:surgery; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007633:Keratins; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection / Q000379:methods; D009367:Neoplasm Staging / Q000379:methods*; D011446:Prospective Studies; D011498:Protein Precursors; D011880:Radiotherapy Planning, Computer-Assisted; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods
D011498:Protein Precursors; C004818:prekeratin; D007633:Keratins