[Show abstract][Hide abstract] ABSTRACT: Quantification of mechanical properties of human prostate tissue is important for developing sonoelastography for prostate cancer detection. In this study, we characterized the frequency-dependent complex Young's modulus of normal and cancerous prostate tissues in vitro by using stress relaxation testing and viscoelastic tissue modeling methods. After radical prostatectomy, small cylindrical tissue samples were acquired in the posterior region of each prostate. A total of 17 samples from eight human prostates were obtained and tested. Stress relaxation tests on prostate samples produced repeatable results that fit a viscoelastic Kelvin-Voigt fractional derivative (KVFD) model (r2>0.97). For normal (n = 8) and cancerous (n = 9) prostate samples, the average magnitudes of the complex Young's moduli (|E*|) were 15.9 ± 5.9 kPa and 40.4 ± 15.7 kPa at 150 Hz, respectively, giving an elastic contrast of 2.6:1. Nine two-sample t-tests indicated that there are significant differences between stiffness of normal and cancerous prostate tissues in the same gland (p < 0.01). This study contributes to the current limited knowledge on the viscoelastic properties of the human prostate, and the inherent elastic contrast produced by cancer. (E-mail: [email protected]
Full-text · Article · Jul 2008 · Ultrasound in Medicine & Biology
[Show abstract][Hide abstract] ABSTRACT: In this paper, we evaluate the performance of sonoelastography for prostate cancer detection. Ultrasound (US) B-mode and sonoelastographic volumes were acquired from five prostate glands ex vivo. Additionally, one more gland was imaged in vivo using a transrectal US probe. Semi-automatic algorithms were used to segment the surface of the gland from the B-mode volume and the tumors from sonoelastographic data. To assess the detection performance, three dimensional (3D) sonoelastographic findings were compared in size and position to 3D histological data. Sonoelastography detected seven out of nine cancers in the ex vivo prostate glands and two out of three malignant masses in the in vivo experiment. Overall, 3D sonoelastography has shown potential for prostate cancer detection albeit based on limited data.
[Show abstract][Hide abstract] ABSTRACT: Epidemiologic studies suggested that vitamin E has a protective effect against prostate cancer. We showed here that tocopherol-associated protein (TAP), a vitamin E-binding protein, promoted vitamin E uptake and facilitated vitamin E antiproliferation effect in prostate cancer cells. Interestingly, without vitamin E treatment, overexpression of TAP in prostate cancer cells significantly suppressed cell growth; knockdown of endogenous TAP by TAP small interfering RNA (siRNA) in nonmalignant prostate HPr-1 cells increased cell growth. Further mechanism dissection studies suggested that the tumor suppressor function of TAP was via down-regulation of phosphoinositide 3-kinase (PI3K)/Akt signaling, but not by modulating cell cycle arrest or androgen receptor signaling. Immunoprecipitation results indicated that TAP inhibited the interaction of PI3K subunits, p110 with p85, and subsequently reduced Akt activity. Constitutively active Akt could negate the TAP-suppressive activity on prostate cancer cell growth. Moreover, stable transfection of TAP in LNCaP cells suppressed LNCaP tumor incidence and growth rate in nude mice. Furthermore, TAP mRNA and protein expression levels were significantly down-regulated in human prostate cancer tissue samples compared with benign prostate tissues as measured by reverse transcription-PCR, in situ hybridization, and immunohistochemistry. Together, our data suggest that TAP not only mediates vitamin E absorption to facilitate vitamin E antiproliferation effect in prostate cancer cells, but also functions like a tumor suppressor gene to control cancer cell viability through a non-vitamin E manner. Therefore, TAP may represent a new prognostic marker for prostate cancer progression.
[Show abstract][Hide abstract] ABSTRACT: We present a method for combining histological data with 3D
ultrasound of excised prostate tissue using surface registration. With
this technique, 3D prostate cancer lesions can be properly located and
visualized within a B-scan volume for tissue characterization
comparisons. Three prostate specimens were scanned with a GE Logiq 700
(Expert series) to obtain 2D B-scan sequences. The prostate boundaries
were manually segmented from each sequence and reconstructed into 3D
volumes. Specimens were fixed, sectioned into slabs, then mounted whole
onto slides. Cancerous lesions were outlined by a pathologist. The
slides were photographed with an Optronics Spot digital camera using
Image-Pro Plus software on a PC. The gland surface was manually
segmented from 2D histology images and reconstructed into a volume.
Various reconstruction problems were addressed, such as specimen
shrinkage due to the fixing and staining processes. The fusion algorithm
translates and rotates one surface volume in 3D to find the best surface
overlap. The resulting geometric transform is used to reorient the
original image volume. The displacement error was determined by
measuring the urethra offsets in final volume cross-sections. The offset
distance ranged from 1.25 mm to 3.45 mm with an average of 2.36 mm.
Another measure to gauge volume alignment is to calculate the ratio of
overlapping voxels to total combined voxels(intersection/union). For a
perfect case, this ratio will be 1. The ratios for the three cases
ranged in value from 0.774 to 0.845