Magnetic Resonance for T-staging of nasopharyngeal carcinoma--the most informative pair of sequences.
OBJECTIVE
To evaluate the most informative pair of sequences in magnetic resonance (MR) for T-staging of nasopharyngeal carcinoma (NPC).


METHODS
The MR images of 134 patients with newly diagnosed NPC, from 1996 to 2002, were retrospectively reviewed. All the patients were scanned using 1.5 Tesla MR systems. The images of the nasopharynx were reviewed by two qualified radiologists to determine the positive findings and the T-stage by UICC (6th edition) System, using each sequence separately. The T-stage derived from a single MR sequence was then compared with the T-stage based on the five selected sequences to assess the number and percentage of patients who were being understaged. Therefore, the overall percentage accuracy of each single sequence could be determined. A pair of sequences providing information to achieve almost 100% diagnostic accuracy was then derived.


RESULTS
The overall percentage accuracy of five individual sequences of the nasopharynx is as follows: contrast-enhanced (CE) fat suppression (FS) axial T1 (94.8%), CE FS coronal T1 (88.1%), FS axial T2 (85.8%), non-contrast enhanced (NE) axial T1 (78.4%) and non-contrast enhanced (NE) coronal T1 (77.6%). CE FS axial T1 has the best accuracy. All the structures that are missed in CE FS axial T1, which lead to apparent understaging, are appreciated in NE axial T1-weighted images.


CONCLUSIONS
Individual sequences supplement each other in the NPC staging. CE FS axial T1 is the most informative individual sequence. Combination of CE FS axial T1 and NE axial T1 of the nasopharynx provides sufficient information to achieve almost 100% diagnostic accuracy in T-staging; therefore, both should be included in the MR-staging protocol.
Lau
Kam Y
KY
Department of Radiology, Pamela Youde Nethersole Eastern Hospital, 3 Lok Man Road, Chai Wan, Hong Kong, ROC.
Kan
Wai K
WK
Sze
Wai M
WM
Lee
Anne W M
AW
Chan
John K W
JK
Yau
Tsz K
TK
Yeung
Rebecca M
RM
Tan
Lawrence
L
Chan
Ping O
PO
Lee
Alex S L
AS
D006801:Humans; D008279:Magnetic Resonance Imaging; D009303:Nasopharyngeal Neoplasms / Q000473:pathology*; D009305:Nasopharynx / Q000473:pathology*; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging / Q000379:methods*; D012189:Retrospective Studies