Salivary glands: echo-planar versus PROPELLER Diffusion-weighted MR imaging for assessment of ADCs.
OBJECTIVE
To compare the image distortion and the quantification variation in parotid gland apparent diffusion coefficients (ADCs) on periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) versus echo-planar diffusion-weighted (DW) magnetic resonance (MR) images and to investigate the relationship between parotid gland ADC and parotid gland fat content.


METHODS
This prospective study was approved by a local institutional review board. Written informed consent was obtained from all 33 enrolled healthy volunteers (15 men, 18 women; mean age, 36.4 years +/- 11.8 [standard deviation]). All participants underwent 1.5-T non-fat-saturated and fat-saturated PROPELLER DW MR imaging as well as 1.5-T nonaccelerated and twofold-accelerated echo-planar DW MR imaging. Image distortion on the DW images was qualitatively scored, and parotid ADC was quantitatively analyzed. The correlation between parotid ADC and parotid fat content was evaluated by using linear regression analysis. Wilcoxon signed rank and t tests were used for statistical analysis, with Bonferroni correction applied for multiple comparisons.


RESULTS
Echo-planar DW images showed distortion, which was completely eliminated on the PROPELLER DW images. The mean parotid ADCs measured with non-fat-saturated PROPELLER (0.670 x 10(-3) mm(2) +/- 0.149), nonaccelerated echo-planar (0.892 x 10(-3) mm(2) +/- 0.128), twofold-accelerated echo-planar (1.088 x 10(-3) mm(2) +/- 0.124), and fat-saturated PROPELLER (1.307 x 10(-3) mm(2) +/- 0.217) DW imaging differed significantly from one another (P < .001 for all comparisons). Parotid ADC had a significant negative correlation with parotid fat content (x) measured at non-fat-saturated PROPELLER DW imaging: ADC = -0.0087x + 1.1173 (r = 0.80, P < .001).


CONCLUSIONS
PROPELLER DW imaging pulse sequences can yield distortion-free images for parotid ADC measurements and enable quantitative evaluation of the relationship between parotid ADC and parotid fat content.


BACKGROUND
http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.2531082228/-/DC1.
Juan
Chun-Jung
CJ
Department of Radiology, National Defense Medical Center, Taipei, Taiwan, Republic of China.
Chang
Hing-Chiu
HC
Hsueh
Chun-Jen
CJ
Liu
Hua-Shan
HS
Huang
Yin-Cheng
YC
Chung
Hsiao-Wen
HW
Chen
Cheng-Yu
CY
Kao
Hung-Wen
HW
Huang
Guo-Shu
GS
D000273:Adipose Tissue / Q000033:anatomy & histology*; D000328:Adult; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008297:Male; D010306:Parotid Gland / Q000033:anatomy & histology*; D019047:Phantoms, Imaging; D011446:Prospective Studies; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric