Enhancement effects of test injection with a small amount of MR contrast medium in the oral and maxillofacial region.
OBJECTIVE
To examine whether the signal intensity of dynamic contrast-enhanced MRI (DCE-MRI) is altered by test injection of 1 ml of contrast medium, and if so, whether this change affects the DCE-MRI analysis.


METHODS
Six healthy volunteers were examined by DCE-MRI using a Magnevist syringe and/or an Omniscan syringe for the injection of contrast medium. Each scan was performed 10 times using steady-state free precession (3D-FISP), a sequence for DCE-MRI, before and after intravenous injection of 1 ml of the contrast medium. The internal pterygoid muscle, masseter muscle, tongue, parotid gland, submandibular gland, bone marrow of the mandible, subcutaneous adipose tissue, and common carotid artery were determined to be regions of interest (ROI), and the ROI internal average signal intensity was measured. The 10 data sets obtained before or after contrast medium administration for each ROI were evaluated using the paired t-test.


RESULTS
The test injection increased the signal intensities of six of eight ROIs, with all 20 experiments in the submandibular gland showing significant differences. There was no significant difference in the two ROIs corresponding to the carotid artery and subcutaneous adipose tissue of the cheek.


CONCLUSIONS
The enhanced signal intensity in the tissue might have been caused by the small amount of contrast medium in the test injection. To eliminate this discrepancy caused by the test injection, a pre-contrast scan should be performed when the average signal intensity of an ROI is measured. We therefore believe that the data obtained before a test injection may be important in the analysis of DCE-MRI.
Yanagi
Yoshinobu
Y
Department of Oral Diagnosis and Dentomaxillofacial Radiology, Okayama University Hospital of Medicine and Dentistry, 5-1 Shikata-cho, 2-chome, Okayama 700-8525, Japan.
Asaumi
Jun-ichi
J
Konouchi
Hironobu
H
Hisatomi
Miki
M
Matsuzaki
Hidenobu
H
Murakami
Jun
J
Maki
Yuu
Y
Unetsubo
Teruhisa
T
Kishi
Kanji
K
D000328:Adult; D017536:Carotid Artery, Common; D002610:Cheek; D003287:Contrast Media / Q000008:administration & dosage*; D004333:Drug Administration Routes; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007267:Injections; D008279:Magnetic Resonance Imaging; D008297:Male; D008334:Mandible; D008406:Masseter Muscle; D010306:Parotid Gland; D011626:Pterygoid Muscles; D013363:Submandibular Gland; D014059:Tongue
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA