期刊
MAGNETIC RESONANCE IMAGING
卷 24, 期 5, 页码 563-568出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.mri.2005.12.008
关键词
prostate; diffusion; biexponential decay
资金
- AHRQ HHS [R03HS13234-01, R03 HS013234] Funding Source: Medline
- NCI NIH HHS [1 R33 CA99015, R25 CA089017, P01 CA067165, R01 CA109246, 1R01CA109246-01A] Funding Source: Medline
- NCRR NIH HHS [U41 RR019703] Funding Source: Medline
- NIA NIH HHS [R01 AG019513, R01 AG19513-01, AG P01CA67165-03] Funding Source: Medline
- NINDS NIH HHS [R01 NS039335, 1 R01 NS39335-01A1] Funding Source: Medline
Detailed measurements of water diffusion within the prostate over an extended b-factor range were performed to assess whether the standard assumption of monoexponential signal decay is appropriate in this organ. From nine men undergoing prostate MR staging examinations at 1.5 T, a single 10-mm-thick axial slice was scanned with a line scan diffusion imaging sequence in which 14 equally spaced b factors from 5 to 3500 s/mm(2) were sampled along three orthogonal diffusion sensitization directions in 6 min. Due to the combination of long scan time and limited volume coverage associated with the multi-b-factor, multidirectional sampling, the slice was chosen online from the available T2-weighted axial images with the specific goal of enabling the sampling of presumed noncancerous regions of interest (ROIs) within the central gland (CG) and peripheral zone (PZ). Histology from prescan biopsy (n=9) and postsurgical resection (n=4) was subsequently employed to help confirm that the ROIs sampled were noncancerous. The CG ROIs were characterized from the T2-weighted images as primarily mixtures of glandular and stromal benign prostatic hyperplasia, which is prevalent in this population. The water signal 2 decays with b factor from all Rots were clearly non-monoexponential and better served with bi- vs. monoexponential fits, as tested using X based F test analyses. Fits to biexponential decay functions yielded intersubject fast diffusion component fractions in the order of 0.73 +/- 0.08 for both CG and PZ ROIs, fast diffusion coefficients of 2.68 +/- 0.39 and 2.52 +/- 0.38 mu m(2)/ms and slow diffusion coefficients of 0.44 +/- 0.16 and 0.23 +/- 0.16 um(2)/ms for CG and PZ ROIs, respectively. The difference between the slow diffusion coefficients within CG and PZ was statistically significant as assessed with a Mann-Whitney nonparametric test (P<.05). We conclude that a monoexponential model for water diffusion decay in prostate tissue is inadequate when a large range of b factors is sampled and that biexponential analyses are better suited for characterizing prostate diffusion decay curves. (C) 2006 Elsevier Inc. All rights reserved.
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