Clinical Applications of Diffusion-Weighted-MRI in
Prostate Cancer
Pornphan Wibulpolprasert MD*,
Sith Phongkitkarun MD*, Panas Chalermsanyakorn MD**
Affiliation :
* Department of Diagnostic and Therapeutic Radiology, Faculty of Medicine, Ramathibodi Hospital,
Mahidol University, Bangkok, Thailand
** Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
Objective : To determine the relationship between the apparent diffusion coefficient (ADC) values calculated from diffusion-
weighted (DW) MR imaging in different b values and tumor grading by Gleason scores of the peripheral zone prostate
cancer.
Material and Method: Thirty-nine patients with prostate cancer who underwent pre-operative endorectal Diffusion-Weighted
(DW) magnetic resonance (MR) imaging between March 2006 and March 2010 were included. Regions of interest (ROIs)
were drawn on ADC maps at sites of visible tumor on DW images and ADC maps comparison to histopathology. Differentiation
between ADC values of tumor and non-tumor areas were analyzed by using paired t-test and sign-test and between tumors
grading were analyzed by using Wilcoxon rank-sum (Mann-Whitney) test and Kruskal-Wallis equality-of population rank
test.
Results : The mean ADC of tumor is lower than non-tumor areas at all b-values. There is negative correlation between ADC
value and tumor grading with statistical significance at b = 1,000 sec/mm2, between tumor grade I (1.95x10-3 mm2/sec, SD
= 0.33) and tumor grade II (1.16x10-3 mm2/sec, SD = 0.27) (p = 0.03) and between tumor grade I and tumor grade III
(1.10x10-3 mm2/sec, SD = 0.36) (p = 0.002) and at b = 2,000 sec/mm2, between tumor grade I (2.21x10-3 mm2/sec, SD = 0.08)
and tumor grade II (1.22x10-3 mm2/sec, SD = 0.38) (p = 0.01), and between tumor grade I and tumor grade III
(1.32x10-3 mm2/sec, SD = 0.49) (p = 0.04). There is no statistical significance difference between tumor grade II and
grade III.
Conclusion : Tumor shows restricted diffusion with ADC value lower than non-tumor areas. There is a significant negative
correlation between ADCs and tumor grading between low and intermediate grades and between low and high grades
tumor at the b = 1,000 and 2,000 sec/mm2. ADC maps may be a useful tool for non-invasive assessment of the aggressiveness
of prostate cancers that are visible on MR images.
Keywords : Endorectal diffusion-weighted-MRI, ADC values, Prostate cancer, Gleason score
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