Rationale and Objectives To compare prostate morphology, image quality, and diagnostic performance of 1.5 T endorectal coil MRI and 3.0 T non-endorectal coil MRI in patients with prostate cancer. Materials and Methods MR images obtained of 83 patients with prostate cancer using 1.5 T MRI systems with an endorectal coil were compared to images collected from 83 patients with a 3.0 T MRI system. Prostate diameters were measured and image quality was evaluated by one ABR-certified radiologist (Reader 1) and one ABR-certified diagnostic medical physicist (Reader 2). The likelihood of the peripheral zone cancer presence in each sextant and local extent were rated and compared with histopathologic findings. Results Prostate anterior-posterior diameter measured by both readers was significantly shorter with 1.5 T endorectal MRI than with 3.0 T MRI. The overall image quality score difference was significant only for Reader 1. Both readers found that the two MRI systems provided similar diagnostic accuracy in cancer localization, extraprostatic extension, and seminal vesicle involvement. Conclusion Non-endorectal coil 3.0 T MRI provides prostate images that are natural in shape and that have comparable image quality to those obtained at 1.5 T with an endorectal coil, but not superior diagnostic performance. These findings suggest an opportunity exists for improving technical aspects of 3.0 T prostate MRI.
Knowledge regarding complex radiation responses in biological systems can be enhanced using genetically amenable model organisms. In this manuscript, we reviewed the use of the nematode, Caenorhabditis elegans (C. elegans), as a model organism to investigate radiation’s biological effects. Diverse types of experiments were conducted on C. elegans, using acute and chronic exposure to different ionizing radiation types, and to assess various biological responses. These responses differed based on the type and dose of radiation and the chemical substances in which the worms were grown or maintained. A few studies compared responses to various radiation types and doses as well as other environmental exposures. Therefore, this paper focused on the effect of irradiation on C. elegans, based on the intensity of the radiation dose and the length of exposure and ways to decrease the effects of ionizing radiation. Moreover, we discussed several studies showing that dietary components such as vitamin A, polyunsaturated fatty acids, and polyphenol-rich food source may promote the resistance of C. elegans to ionizing radiation and increase their life span after irradiation.
Background: In the United States, prostate cancer has a relatively large impact on men's health. Magnetic resonance imaging (MRI) is useful for the diagnosis and treatment of prostate cancer. Introduction: The purpose of this study was to develop a quantitative marker for use in prostate cancer magnetization transfer (MT) magnetic resonance imaging (MRI) studies that is independent of radiofrequency (RF) saturation amplitude. Methods: Eighteen patients with biopsy-proven prostate cancer were enrolled in this study. MTMRI images were acquired using four RF saturation amplitudes at 33 frequency offsets. ROIs were delineated for the peripheral zone (PZ), central gland (CG), and tumor. Z-spectral data were collected in each region and fit to a three-parameter equation. The three parameters are: the magnitude of the bulk water pool (Aw), the full width at half maximum of the water pool (Gw), and the magnitude of the bound pool (Ab), while, the slopes from the linear regressions of Gw and Ab on RF saturation amplitude (called kAb and kGw) were used as quantitative markers. Results: A pairwise statistically significant difference was found between the PZ and tumor regions for the two saturation amplitude-independent quantitative markers. No pairwise statistically significant differences were found between the CG and tumor regions for any quantitative markers. Conclusion: The significant differences between the values of the two RF saturation amplitudeindependent quantitative markers in the PZ and tumor regions reveal that these markers may be capable of distinguishing healthy PZ tissue from prostate cancer.
Following radiotherapy, PSA nadir is correlated with disease-free survival-lower nadir predicting higher long-term biochemical disease-free rates; however, temporary PSA rise ("bounce") may confound this prediction. We present mature results from a prospective Phase II SBRT trial correlating PSA response kinetics with relapse, with detailed analysis of patients with any post-SBRT PSA rise. Materials/Methods: 17 institutions treated 259 low-and intermediate-risk patients with SBRT (38Gy/4 fx) with median and maximum post-SBRT follow-up of 5 and 8 years. "Heterogeneous" dosimetry was required: Dmax >150% of prescribed (Rx isodose 50-67%), with strict "HDR-like" urethra, bladder and rectal dose limitation. Androgen deprivation therapy was not used. Patients were considered biochemically relapsed if either Phoenix or ASTRO criteria were met. Results: Median PSA levels measured 5.12 ng/mL pre-SBRT and 0.9, 0.2, 0.1 and 0.055 ng/mL at 1, 3, 5 and 7 years post-SBRT, respectively. Although 93.2% of patients remained disease-free at 5-and 7-years (100% low risk, 88.5% int. risk; nadir + 2), only 35% (90/259) had continuously decreasing PSA values post-SBRT, while 65% (169/259) had at least one rise (median 0.2 ng/mL; range 0.1-4.2 ng/mL). Of patients with any post-SBRT PSA rise, only 15/169 (8.9%) developed confirmed biochemical relapse (CBR), while 154/169 (91.1%) remained disease-free. Among patients with any PSA rise, those with CBR had a higher median PSA nadir (2.2 vs 1.2 ng/mL for non-relapsers, pZ0.046), and shorter median time to 1 st rise (16 vs 23 months for non-relapsers, pZ0.03). Median magnitude of first PSA rise was similar: 0.2 ng/mL for both. Among patients with any PSA rise, additional factors associated with relapse are in the Table. Conclusion: After heterogeneous SBRT, median PSA decreases through 7 years of follow-up, reaching <0.1 ng/mL after year 6. Nearly 2/3rds of patients experienced at least one post-SBRT PSA rise, with over 90% remaining disease-free thereafter. PSA rise associated with biochemical relapse tended to occur sooner and have a higher pre-bounce nadir level and was also more commonly seen in older patients and those with nonlow-risk disease. These results may help physicians to better sort patients whose post-SBRT PSA rise is unlikely to portend relapse versus those who may require more intensive monitoring.
specifically focused on patients with low risk prostate cancer with limited data available in intermediate (IRPC) or high risk prostate cancer. We describe toxicity and biochemical progression free survival outcomes of linear accelerator based SBRT boost for IRPC. Materials/Methods: This is a multi-center (9) retrospective review of prospectively collected data for a total of 60 patients; thirty-eight patients (63%) were treated on an IRB approved prospective trial. IRPC patients that included clinical stage T2b (7%) or PSA > 10 ng/ml and < 20 ng/ml (25%) or Gleason score of 7 (82%), received 45 Gy of IMRT in 25 fractions followed by a SBRT boost of 5.5 Gy per fraction for 4 fractions. Cone beam CT image guidance was used prior to each fraction for correction of target setup error. Twenty-three percent of patients received concomitant androgen deprivation therapy (ADT); forty-six patients (77%) deferred concomitant ADT. NCI CTCAE v3.0 was used to assess urinary and rectal toxicity at baseline, during treatment, and then at 1, 3, 6, 9, 12, 18, 24, 30, and 36 months after treatment. Biochemical determinations were made at concurrent follow up time points. IPSS and IEFF scores were also obtained at baseline and at follow up. Results: Median follow up was 21.5 months (range 2.9-87.2). No patient (0%) had a biochemical failure, using the combined ASTRO Phoenix definition. Mean PSA (ng/ml
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