Three-dimensionally printed facial prosthesis with a silicone veneer technique: A clinical report.

Digital technology has revolutionized the acquisition of patient data and the fabrication of prosthetic replacements for extraoral defects. This clinical report illustrates the use of a new technique which allows the digital creation of an acrylic resin framework which is then veneered with silicone to create an esthetic prosthesis in less time and with less patient discomfort.

Comparison of Histogram-Based Gaussian Analysis With and Without Noise Correction for the Characterization of Indeterminate Adrenal Nodules.

OBJECTIVE. The purpose of this study is to determine whether gaussian-based histogram analysis without and with noise correction can characterize indeterminate adrenal nodules (those with attenuation greater than 10 HU on unenhanced CT) as lipid-poor adenomas. MATERIALS AND METHODS. This retrospective study evaluated adrenal nodules larger than 1 cm on unenhanced CT using gaussian analysis without and with noise correction on intralesional ROIs. Two independent readers who were blinded to the final diagnoses evaluated the nodules. The final diagnosis for each nodule was determined on the basis of pathologic findings or accepted imaging criteria. Interreader agreement was assessed using the intraclass correlation coefficient. Algorithm performance was summarized using sensitivity, specificity, and the AUC. RESULTS. Ninety-four adrenal nodules in 85 patients were analyzed; 36 of these were metastases (34 of which were pathologically confirmed), and 58 were presumed adenomas. Interreader agreement was excellent for nodule size, mean attenuation, SD of attenuation, and the gaussian index. Noise-corrected gaussian analysis had significantly higher specificity (81.9% vs 55.6%; p < 0.001) and lower sensitivity (36.2% vs 56.9%; p < 0.001) for identifying adenomas than did the uncorrected gaussian analysis. The AUC of corrected gaussian analysis was 0.72, which is significantly greater than that of uncorrected gaussian analysis (0.51; p ≤ 0.001) and similar to that of mean attenuation (0.77). CONCLUSION. Noise correction is necessary when using a gaussian analysis characterization of indeterminate adrenal nodules on modern unenhanced CT examinations. This method may be able to discriminate between adenomas and nonadenomas.

Evaluation of diagnostic accuracy: multidetector CT image noise correction improves specificity of a Gaussian model-based algorithm used for characterization of incidental adrenal nodules.

OBJECTIVES: To investigate whether the histogram analysis method of characterizing adrenal nodules as adenomas is affected by increased noise with modern CT technique, and if an extension that allows for noise correction will improve diagnostic performance. MATERIALS AND METHODS: This is a HIPAA-compliant, IRB-approved retrospective study performed on 58 total patients. The first group of 29 patients had 33 adrenal lesions that were pathology-proven non-adenomas. The second group had 29 patients with 33 pathology-proven or presumed adenomas based on established imaging criteria. The nodules were evaluated using the histogram method, mean attenuation method, and a Gaussian model-based algorithm without (uncorrected Gaussian algorithm) and with correction (corrected Gaussian algorithm) for image noise. Sensitivity, specificity, and accuracy for identifying adenoma were derived. RESULTS: There were no significant differences in identifying adenoma from non-adenoma when using the histogram analysis method and the uncorrected Gaussian algorithm, both of which had low specificities of 42.4% and 47.0%, respectively (p = 0.30). Adding noise correction to the Gaussian algorithm resulted in a statistically significant increase in specificity relative to the histogram method (86.4% vs. 42.4%, p < 0.001). The corrected Gaussian algorithm improved sensitivity compared to the mean attenuation method (71.2% vs. 54.5%, p < 0.001), but had lower specificity (86.4% vs. 100%, p < 0.001), and similar overall accuracy (78.8% vs. 77.3%, p = 0.74). CONCLUSION: With modern low-dose CT technique, the specificity scores of the histogram method for discrimination of adrenal adenomas and non-adenomas are lower than with previous higher dose scans. The specificity and accuracy of a histogram-equivalent method can be increased mathematically through image noise correction, and the corrected Gaussian algorithm has improved sensitivity to the mean attenuation with similar accuracy albeit with lower specificity. Although this suggests limited utility for histogram analysis in adrenal nodule characterization, our study demonstrates the potential mathematical application for other noise-dependent CT characterization methods.

Characterization of Adrenal Adenoma by Gaussian Model-Based Algorithm.

We confirmed that computed tomography (CT) attenuation values of pixels in an adrenal nodule approximate a Gaussian distribution. Building on this and the previously described histogram analysis method, we created an algorithm that uses mean and standard deviation to estimate the percentage of negative attenuation pixels in an adrenal nodule, thereby allowing differentiation of adenomas and nonadenomas. The institutional review board approved both components of this study in which we developed and then validated our criteria. In the first, we retrospectively assessed CT attenuation values of adrenal nodules for normality using a 2-sample Kolmogorov-Smirnov test. In the second, we evaluated a separate cohort of patients with adrenal nodules using both the conventional 10HU unit mean attenuation method and our Gaussian model-based algorithm. We compared the sensitivities of the 2 methods using McNemar's test. A total of 183 of 185 observations (98.9%) demonstrated a Gaussian distribution in adrenal nodule pixel attenuation values. The sensitivity and specificity of our Gaussian model-based algorithm for identifying adrenal adenoma were 86.1% and 83.3%, respectively. The sensitivity and specificity of the mean attenuation method were 53.2% and 94.4%, respectively. The sensitivities of the 2 methods were significantly different (P value < 0.001). In conclusion, the CT attenuation values within an adrenal nodule follow a Gaussian distribution. Our Gaussian model-based algorithm can characterize adrenal adenomas with higher sensitivity than the conventional mean attenuation method. The use of our algorithm, which does not require additional postprocessing, may increase workflow efficiency and reduce unnecessary workup of benign nodules.

Retinol-binding site in interphotoreceptor retinoid-binding protein (IRBP): a novel hydrophobic cavity.

PURPOSE: Interphotoreceptor retinoid-binding protein (IRBP) appears to target and protect retinoids during the visual cycle. X-ray crystallographic studies had noted a betabetaalpha-spiral fold shared with crotonases and C-terminal protein transferases. The shallow cleft formed by the fold was assumed to represent the retinol-binding site. However, a second hydrophobic site consisting of a highly restricted cavity was more recently appreciated during in silico ligand-docking studies. In this study, the ligand-binding environment within the second module of Xenopus IRBP (X2IRBP) is defined. METHODS: Pristine recombinant polypeptide corresponding to X2IRBP was expressed in a soluble form and purified to homogeneity without its fusion tag. Phenylalanine was substituted for tryptophan at each of the putative retinol-binding domains (W450F, hydrophobic cavity; W587F, shallow cleft). Binding of 11-cis and all-trans retinol were observed in titrations monitoring retinol fluorescence enhancement, quenching of tryptophan fluorescence, and energy transfer. The effect of oleic acid on retinol binding was also examined. RESULTS: A ligand-binding stoichiometry of approximately 1:1 was observed for 11-cis and all-trans with K(d) in the tens of nanomolar range. The substitution mutants showed little effect on retinol binding in titrations after fluorescence enhancement. However, the W450F and not the W587F mutant showed a markedly reduced capacity for fluorescence quenching for both 11-cis and all-trans retinol. Oleic acid inhibited the binding of 11-cis and all-trans retinol in an apparent noncompetitive manner. CONCLUSIONS: The binding site for 11-cis and all-trans retinol is a novel hydrophobic cavity that is highly restrictive and probably distinct from the long chain fatty acid-binding site.