Warthin tumor of the parotid gland: diagnostic value of MR imaging with histopathologic correlation.
OBJECTIVE
The purpose of our study was to describe the MR imaging appearance of Warthin tumors multiple MR imaging techniques and to interpret the difference in appearance from that of malignant parotid tumors.


METHODS
T1-weighted, T2-weighted, short inversion time inversion recovery, diffusion-weighted, and contrast-enhanced dynamic MR images of 19 Warthin tumors and 17 malignant parotid tumors were reviewed. MR imaging results were compared with those of pathologic analysis.


RESULTS
Epithelial stromata and lymphoid tissue with slitlike small cysts in Warthin tumors showed early enhancement and a high washout rate (> or =30%) on dynamic contrast-enhanced images, and accumulations of complicated cysts showed early enhancement and a low washout ratio (< 30%). The areas containing complicated cysts showed high signal intensity on T1-weighted images, whereas some foci in those areas showed low signal intensity on short tau inversion recovery images. The mean minimum signal intensity ratios (SIRmin) of Warthin tumor on short tau inversion recovery (0.29 +/- 0.22 SD) (P < .01) and T2-weighted images (0.28 +/- 0.09) (P < .05) were significantly lower than those of malignant parotid tumors (0.53 +/- 0.19, 0.48 +/- 0.19). The average washout ratio of Warthin tumors (44.0 +/- 20.4%) was higher than that of malignant parotid tumors (11.9 +/- 11.6%). The mean apparent diffusion coefficient of Warthin tumors (0.96 +/- 0.13 x 10(-3)mm2/s) was significantly lower (P < .01) than that of malignant tumors (1.19 +/- 0.19 x 10(-3)mm2/s).


CONCLUSIONS
Detecting hypointense areas of short tau inversion recovery and T2-weighted images or low apparent diffusion coefficient values on diffusion-weighted images was useful for predicting whether salivary gland tumors were Warthin tumors. The findings of the dynamic contrast-enhanced study also were useful.
Ikeda
Mitsuaki
M
Department of Radiology, Chiba University Hospital, Chiba, Japan.
Motoori
Ken
K
Hanazawa
Toyoyuki
T
Nagai
Yuichiro
Y
Yamamoto
Seiji
S
Ueda
Takuya
T
Funatsu
Hiroyuki
H
Ito
Hisao
H
D000235:Adenolymphoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000473:pathology / Q000601:surgery; D010307:Parotid Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D012680:Sensitivity and Specificity
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA