Department of Experimental Diagnostic Imaging, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
PLoS One. 2013;8(3):e55746. doi: 10.1371/journal.pone.0055746. Epub 2013 Mar 1.
Prostate imaging requires optimization in young and old mouse models. We tested which MR sequences and field strengths best depict the prostate gland in young and old mice; and, whether prostate MR signal, size, and architecture change with age.
Magnetic resonance imaging (MRI) of the prostate of young (2 months) and old (18 months) male nude mice (n = 6) was performed at 4.7 and 7 T and SCID mice (n = 6) at 7 T field strengths, using T1, fat suppressed T1, DWI, T2, fat suppressed T2, as well as T2-based- and proton density-based Dixon "water only" sequences. Images were ranked for best overall sequence for prostate visualization, prostate delineation, and quality of fat suppression. Prostate volume and signal characteristics were compared and histology was performed.
T2-based-Dixon "water only" images ranked best overall for prostate visualization and delineation as well as fat suppression (n = 6, P<0.001) at both 4.7 T and 7 T in nude and 7T in SCID mice. Evaluated in nude mice, T2-based Dixon "water only" had greater prostate CNR and lower fat SNR at 7 T than 4.7 T (P<0.001). Prostate volume was less in older than younger mice (n = 6, P<0.02 nude mice; n = 6, P<0.002 SCID mice). Prostate T2 FSE as well as proton density-based and T2-based-Dixon "water only" signal intensity was higher in younger than older mice (P<0.001 nude mice; P<0.01 SCID mice) both at 4.7 and 7 T. This corresponded to an increase in glandular hyperplasia in older mice by histology (P<0.01, n = 6).
T2-based Dixon "water only" images best depict the mouse prostate in young and old nude mice at 4.7 and 7 T. The mouse prostate decreases in size with age. The decrease in T2 and T2-based Dixon "water only" signal with age corresponds with glandular hyperplasia. Findings suggest age should be an important determinant when choosing models of prostate biology and disease.
前列腺成像需要在年轻和老年小鼠模型中进行优化。我们测试了哪些磁共振序列和场强最能描绘年轻和老年小鼠的前列腺；以及前列腺磁共振信号、大小和结构是否随年龄而变化。
对年轻（2 个月）和老年（18 个月）雄性裸鼠（n = 6）和 SCID 鼠（n = 6）的前列腺进行磁共振成像（MRI），分别在 4.7T 和 7T 场强下使用 T1、脂肪抑制 T1、DWI、T2、脂肪抑制 T2 以及 T2 加权和质子密度加权 Dixon“仅水”序列进行扫描。根据前列腺显示、勾画和脂肪抑制质量对图像进行整体最佳序列评分。比较前列腺体积和信号特征，并进行组织学检查。
在 4.7T 和 7T 的裸鼠以及 7T 的 SCID 鼠中，T2 加权 Dixon“仅水”图像在前列腺显示和勾画以及脂肪抑制方面的总体评分最高（n = 6，P<0.001）。在裸鼠中，7T 下的 T2 加权 Dixon“仅水”图像的前列腺对比度噪声比（CNR）更高，脂肪信噪比（SNR）更低（n = 6，P<0.001）。与年轻小鼠相比，老年小鼠的前列腺体积较小（n = 6，P<0.02 裸鼠；n = 6，P<0.002 SCID 鼠）。与年轻小鼠相比，老年小鼠的前列腺 T2 FSE 以及质子密度加权和 T2 加权 Dixon“仅水”信号强度更高（n = 6，P<0.001 裸鼠；P<0.01 SCID 鼠），无论是在 4.7T 还是 7T 下都是如此。这与组织学检查显示的老年小鼠腺泡增生增加相对应（n = 6，P<0.01）。
在 4.7T 和 7T 下，T2 加权 Dixon“仅水”图像最能描绘年轻和老年裸鼠的前列腺。随着年龄的增长，小鼠的前列腺会变小。随着年龄的增长，T2 和 T2 加权 Dixon“仅水”信号的降低与腺泡增生相对应。这些发现表明，在选择前列腺生物学和疾病模型时，年龄应该是一个重要的决定因素。
