Computed high b-value diffusion-weighted imaging improves lesion contrast and conspicuity in prostate cancer.

BACKGROUND: To evaluate whether very high b-value computed diffusion-weighted imaging (cDWI) is able to provide better contrast between the foci of prostate cancer and background tissue than the standard apparent diffusion coefficient (ADC) map, and whether this improved contrast could be used to improve the tumor detection. METHODS: Very high b-value cDWI series up to b4000 were created for 14 patients with high-grade prostate cancer. Contrast-to-noise ratios (CNRs) and CNR-to-ADC ratios were calculated. Three blinded readers also assessed the tumor conspicuity on a standard five-point scale. RESULTS: The tumor CNR increased with increasing b-values in all the patients up to a maximum average CNR of 75.1 for a b-value of 4000 (average CNR for the ADC maps: 10.0). CNR/ADC ratios were higher than 1 (indicating higher CNR than respective ADC) for cDWI of 1500 and higher, with a maximum of 6.5 for cDWI4000. The average subjective tumor conspicuity scores for cDWI2000, 3000 and 4000 were significantly higher than that of the ADC (4.0): 4.5 (P=0.018), 4.5 (P=0.017) and 4.6 (P=0.012). CONCLUSIONS: cDWI is able to provide better contrast between the foci of prostate cancer and background tissue compared with a standard ADC map. This resulted in improved subjective tumor conspicuity.

Mass-like peripheral zone enhancement on CT is predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer.

PURPOSE: To determine whether focal peripheral zone enhancement on routine venous-phase CT is predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer. MATERIALS AND METHODS: IRB approval was obtained and informed consent waived for this HIPAA-compliant retrospective study. Forty-three patients with higher-grade prostate cancer (≥Gleason 4 + 3) and 96 with histology-confirmed lower-grade (≤Gleason 3 + 4 [n = 47]) or absent (n = 49) prostate cancer imaged with venous-phase CT comprised the study population. CT images were reviewed by ten blinded radiologists (5 attendings, 5 residents) who scored peripheral zone enhancement on a scale of 1 (benign) to 5 (malignant). Mass-like peripheral zone enhancement was considered malignant. Likelihood ratios (LR) and specificities were calculated. Multivariate conditional logistic regression analyses were conducted. RESULTS: Scores of "5" were strongly predictive of higher-grade prostate cancer (pooled LR+ 9.6 [95% CI 5.8-15.8]) with rare false positives (pooled specificity: 0.98 [942/960, 95% CI 0.98-0.99]; all 10 readers had specificity ≥95%). Attending scores of "5" were more predictive than resident scores of "5" (LR+: 14.7 [95% CI 5.8-37.2] vs. 7.6 [95% CI 4.2-13.7]) with similar specificity (0.99 [475/480, 95% CI 0.98-1.00] vs. 0.97 [467/480, 95% CI 0.96-0.99]). Significant predictors of an assigned score of "5" included presence of a peripheral zone mass (p < 0.0001), larger size (p < 0.0001), and less reader experience (p = 0.0008). Significant predictors of higher-grade prostate cancer included presence of a peripheral zone mass (p = 0.0002) and larger size (p < 0.0001). CONCLUSION: Focal mass-like peripheral zone enhancement on routine venous-phase CT is specific and predictive of higher-grade (Gleason 4 + 3 and higher) prostate cancer.

Maneuvering in an arboreal habitat: the effects of turning angle on the locomotion of three sympatric ecomorphs of Anolis lizards.

Although the maximal speeds of straight-ahead running are well-documented for many species of Anolis and other lizards, no previous study has experimentally determined the effects of turning on the locomotor performance of a lizard. Anolis lizards are a diverse group of arboreal species, and the discrete paths created by networks of perches in arboreal environments often force animals to turn in their natural habitats. For three species of Anolis with similar overall body size but different shape, we quantified the escape locomotor performance for arboreal locomotion on 4.8 cm diameter perches that were straight (0 degrees ) or had turning angles of 30 degrees and 90 degrees. The turning angle had widespread significant effects that were often species-dependent. This was shown by measuring the average gross velocity (including the times while the lizards paused) of the three species covering the middle 30 cm of a racetrack with either 30 degrees or 90 degrees turns. The results were expressed as a percentage of the gross velocity over the same distance on a straight racetrack. The values obtained for A. grahami (99 % for 30 degrees turns and 79 % for 90 degrees turns) showed a smaller effect of turning angle than for A. lineatopus (79 % for 30 degrees turns and 50 % for 90 degrees turns) and A. valencienni (74 % for 30 degrees turns and 48 % for 90 degrees turns). Consequently, the rank order of species based on speed depended on the angle of the turn. Some of the magnitudes of decreased locomotor speed associated with turning exceeded those reported previously for the effects of decreasing perch diameter for these species. For all species, more pausing occurred with increased turning angle, with the twig ecomorph (A. valencienni) pausing the most. Approximately half the individuals of each species jumped to traverse the 90 degrees turn, but some of the potential benefits of jumping for increasing speed were offset by pauses associated with preparing to jump or recovering balance immediately after a jump. The tail of Anolis lizards may facilitate the substantial rotation (>60 degrees ) of the body that often occurred in the airborne phase of the jumps.

Efficacy of prophylactic antibiotics in reduction mammoplasty.

The use of prophylactic antibiotics in reduction mammoplasty has been random and its efficacy unproven. This study reviewed 106 consecutive inferior pedicle technique reduction mammoplasties. Two groups were identified; 47 patients received prophylactic antibiotics and 59 patients did not. The decision of who received prophylactic antibiotics was random based on resident rotation and resident preoperative orders. The demographics were equal between the antibiotic group and the control group. The wound infection rate and the rate of delayed healing were examined in both groups. There were no statistically significant differences in the infection rate or the rate of delayed wound healing in either the antibiotic group or the control group. Individual risk factors were also studied in each group. These risk factors included obesity, older age, smoking history, and large reductions. The use of prophylactic antibiotics did not reduce the infection rate in any of these high-risk groups. Comparing the individual risk factors for the remainder of the patient population showed that the infection rate was higher in obese patients but was unaffected by prophylactic antibiotics. Delayed healing was also higher in larger reductions but also was unaffected by the use of prophylactic antibiotics. We conclude that the use of prophylactic antibiotics in reduction mammoplasty is not efficacious in reducing the rate of wound infection or delayed healing.