The value of dynamic MRI studies in parotid tumors.
OBJECTIVE
To evaluate the ability of dynamic contrast-enhanced magnetic resonance imaging (MRI) to differentiate several tumor entities of the parotid gland in a prospective clinical trial.


METHODS
A total of 112 patients with parotid tumors were examined with dynamic contrast-enhanced 1.5 T MRI. Precontrast axial T1-weighted imaging was used to select five slices for the dynamic study. Subsequently, a T1-weighted FLASH sequence was used for the dynamic contrast study (0.2 ml Gd/kg x body weight). Contrast agent application and the FLASH sequence were started simultaneously. Ten acquisitions of 10 seconds' scan time each were performed (total acquisition time 1:40 minutes). Signal intensity versus time (SIvT) curves was obtained for all tumors. After correlation of the categorized SIvT curves, these were compared with histopathology. Finally, all MRIs together with the tumor specific SIvT curves were re-read and correlated with histopathologic diagnosis. All reading sessions were done by three experienced radiologists.


RESULTS
Four characteristic intensity-time curves were observed: pleomorphic adenoma showed a gradual increase in signal intensity, followed by a plateau phase on a low intensity level. Cysts showed a vacillating course at a low signal intensity level. Adenolymphomas as well as carcinomas showed a rapid increase in signal intensity followed by a plateau phase. Statistic significance was found for the time-to-peak values for adenolymphomas and pleomorphic adenomas and for the maximum peak signal intensity values for carcinomas. Together with other morphologic MRI criteria (contrast enhancement, border characteristics) and clinical features, a differentiation between adenolymphoma and carcinoma was possible.


CONCLUSIONS
With additional dynamic contrast-enhanced MRI, a more reliable differentiation between common parotid tumors is possible before surgery.
Alibek
Sedat
S
Institute of Radiology, University of Erlangen/Nuremberg, Maximiliansplatz 1 - 91054 Erlangen, Germany. sedat.alibek@idr.imed.uni-erlangen.de
Zenk
Johannes
J
Bozzato
Alessandro
A
Lell
Michael
M
Grunewald
Markus
M
Anders
Katharina
K
Rabe
Christina
C
Iro
Heinrich
H
Bautz
Werner
W
Greess
Holger
H
D000235:Adenolymphoma / Q000175:diagnosis* / Q000601:surgery; D008949:Adenoma, Pleomorphic / Q000175:diagnosis* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002277:Carcinoma / Q000175:diagnosis* / Q000601:surgery; D002648:Child; D003287:Contrast Media / Q000008:administration & dosage; D003937:Diagnosis, Differential; D005260:Female; D005682:Gadolinium; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010306:Parotid Gland / Q000473:pathology* / Q000601:surgery; D010307:Parotid Neoplasms / Q000175:diagnosis* / Q000601:surgery; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity
D003287:Contrast Media; D005682:Gadolinium