0
selected
-
1.
Micro-relief analysis with skin capacitive imaging.
Bontozoglou, C, Zhang, X, Xiao, P
Skin research and technology : official journal of International Society for Bioengineering and the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society for Skin Imaging (ISSI). 2019;(2):165-170
Abstract
BACKGROUND In this study, the performance of capacitive imagining in skin micro-relief analysis was investigated. This measurement principle has been used for skin hydration measurements over the last decade and it is commercially available by various manufacturers. Strengthening its potential for new applications could offer an affordable and portable multi-purpose device for in vivo skin research. Previous studies in the literature have used a wide range of optical devices to determine how the skin surface topographic features are affected by chronological age, environmental influences and living habits. MATERIAL AND METHODS A capacitive system was used in order to capture hydration images from the middle volar forearm of twelve volunteers. The visual output of the system was studied and image processing algorithms were adapted to automatically extract skin micro-relief features. The change in the skin network of lines during arm extension, the lines' anisotropy index and the number of closed polygons per skin surface area were plotted against the subjects' chronological age. The results were compared with optical measurements from the literature to validate our algorithms and evaluate the capacitive imaging in skin micro-relief analysis. RESULTS The change in the intensity of primary and secondary lines during arm extension and the number of closed polygons per surface area were in agreement with the literature. The anisotropy index output gave inconclusive results. CONCLUSIONS The experimental results show that the capacitive systems could only extract two-dimensional skin topographic features.
-
2.
Comparison of quantitative regional ventilation-weighted fourier decomposition MRI with dynamic fluorinated gas washout MRI and lung function testing in COPD patients.
Kaireit, TF, Gutberlet, M, Voskrebenzev, A, Freise, J, Welte, T, Hohlfeld, JM, Wacker, F, Vogel-Claussen, J
Journal of magnetic resonance imaging : JMRI. 2018;(6):1534-1541
Abstract
BACKGROUND Ventilation-weighted Fourier decomposition-MRI (FD-MRI) has matured as a reliable technique for quantitative measures of regional lung ventilation in recent years, but has yet not been validated in COPD patients. PURPOSE/HYPOTHESIS To compare regional fractional lung ventilation obtained by ventilation-weighted FD-MRI with dynamic fluorinated gas washout MRI (19 F-MRI) and lung function test parameters. STUDY TYPE Prospective study. POPULATION Twenty-seven patients with chronic obstructive pulmonary disease (COPD, median age 61 [54-67] years) were included. FIELD STRENGTH/SEQUENCE For FD-MRI and for 19 F-MRI a spoiled gradient echo sequence was used at 1.5T. ASSESSMENT FD-MRI coronal slices were acquired in free breathing. Dynamic 19 F-MRI was performed after inhalation of 25-30 L of a mixture of 79% fluorinated gas (C3 F8 ) and 21% oxygen via a closed face mask tubing using a dedicated coil tuned to 59.9 MHz. 19 F washout times in numbers of breaths (19 F-nbreaths ) as well as fractional ventilation maps for both methods (FD-FV, 19 F-FV) were calculated. Slices were matched using a landmark driven algorithm, and only corresponding slices with an overlap of >90% were coregistered for evaluation. STATISTICAL TESTS The obtained parameters were correlated with each other using Spearman's correlation coefficient (r). RESULTS FD-FV strongly correlated with 19 F-nbreaths on a global (r = -0.72, P < 0.0001) as well as on a lobar level and with lung function test parameters (FD-FV vs. FEV1, r = 0.76, P < 0.0001). There was a small systematic overestimation of FD-FV compared to 19 F-FV (mean difference -0.03 (95% confidence interval [CI]: -0.097; -0.045). DATA CONCLUSION Regional ventilation-weighted Fourier decomposition-MRI is a promising noninvasive, radiation-free tool for quantification of regional ventilation in COPD patients. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1534-1541.
-
3.
Comparative quantification of dietary supplemented neural creatine concentrations with (1)H-MRS peak fitting and basis spectrum methods.
Turner, CE, Russell, BR, Gant, N
Magnetic resonance imaging. 2015;(9):1163-1167
Abstract
Magnetic resonance spectroscopy (MRS) is an analytical procedure that can be used to non-invasively measure the concentration of a range of neural metabolites. Creatine is an important neurometabolite with dietary supplementation offering therapeutic potential for neurological disorders with dysfunctional energetic processes. Neural creatine concentrations can be probed using proton MRS and quantified using a range of software packages based on different analytical methods. This experiment examines the differences in quantification performance of two commonly used analysis packages following a creatine supplementation strategy with potential therapeutic application. Human participants followed a seven day dietary supplementation regime in a placebo-controlled, cross-over design interspersed with a five week wash-out period. Spectroscopy data were acquired the day immediately following supplementation and analyzed with two commonly-used software packages which employ vastly different quantification methods. Results demonstrate that neural creatine concentration was augmented following creatine supplementation when analyzed using the peak fitting method of quantification (105.9%±10.1). In contrast, no change in neural creatine levels were detected with supplementation when analysis was conducted using the basis spectrum method of quantification (102.6%±8.6). Results suggest that software packages that employ the peak fitting procedure for spectral quantification are possibly more sensitive to subtle changes in neural creatine concentrations. The relative simplicity of the spectroscopy sequence and the data analysis procedure suggest that peak fitting procedures may be the most effective means of metabolite quantification when detection of subtle alterations in neural metabolites is necessary. The straightforward technique can be used on a clinical magnetic resonance imaging system.
-
4.
Comparison of digital and film grading of diabetic retinopathy severity in the diabetes control and complications trial/epidemiology of diabetes interventions and complications study.
Hubbard, LD, Sun, W, Cleary, PA, Danis, RP, Hainsworth, DP, Peng, Q, Susman, RA, Aiello, LP, Davis, MD, ,
Archives of ophthalmology (Chicago, Ill. : 1960). 2011;(6):718-26
Abstract
OBJECTIVE To compare diabetic retinopathy (DR) severity as evaluated by digital and film images in a long-term multicenter study, as the obsolescence of film forced the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study (DCCT/EDIC) to transition to digital after 25 years. METHODS At 20 clinics from 2007 through 2009, 310 participants with type 1 diabetes with a broad range of DR were imaged, per the Early Treatment Diabetic Retinopathy Study (ETDRS) protocol, with both film and digital cameras. Severity of DR was assessed centrally from film and tonally standardized digital cameras. For retinopathy outcomes with greater than 10% prevalence, we had 85% or greater power to detect an agreement κ of 0.7 or lower from our target of 0.9. RESULTS Comparing DR severity, digital vs film yielded a weighted κ of 0.74 for eye level and 0.73 for patient level ("substantial"). Overall, digital grading did not systematically underestimate or overestimate severity (McNemar bias test, P = .14). For major DR outcomes (≥3-step progression on the ETDRS scale and disease presence at ascending thresholds), digital vs film κ values ranged from 0.69 to 0.96 ("substantial" to "nearly perfect"). Agreement was 86% to 99%; sensitivity, 75% to 98%; and specificity, 72% to 99%. Major conclusions were similar with digital vs film gradings (odds reductions with intensive diabetes therapy for proliferative DR at EDIC years 14 to 16: 65.5% digital vs 64.3% film). CONCLUSION Digital and film evaluations of DR were comparable for ETDRS severity levels, DCCT/EDIC design outcomes, and major study conclusions, indicating that switching media should not adversely affect ongoing studies.
-
5.
Digitization of simulated clinical dental impressions: virtual three-dimensional analysis of exactness.
Persson, AS, Odén, A, Andersson, M, Sandborgh-Englund, G
Dental materials : official publication of the Academy of Dental Materials. 2009;(7):929-36
Abstract
OBJECTIVES To compare the exactness of simulated clinical impressions and stone replicas of crown preparations, using digitization and virtual three-dimensional analysis. METHODS Three master dies (mandibular incisor, canine and molar) were prepared for full crowns, mounted in full dental arches in a plane line articulator. Eight impressions were taken using an experimental monophase vinyl polysiloxane-based material. Stone replicas were poured in type IV stone (Vel-Mix Stone; Kerr). The master dies and the stone replicas were digitized in a touch-probe scanner (Procera) Forte; Nobel Biocare AB) and the impressions in a laser scanner (D250, 3Shape A/S), to create virtual models. The resulting point-clouds from the digitization of the master dies were used as CAD-Reference-Models (CRM). Discrepancies between the points in the pointclouds and the corresponding CRM were measured by a matching-software (CopyCAD 6.504 SP2; Delcam Plc). The distribution of the discrepancies was analyzed and depicted on color-difference maps. RESULTS The discrepancies of the digitized impressions and the stone replicas compared to the CRM were of similar size with a mean+/-SD within 40microm, with the exception of two of the digitized molar impressions. The precision of the digitized impressions and stone replicas did not differ significantly (F=4.2; p=0.053). However, the shape affected the digitization (F=5.4; p=0.013) and the interaction effect of shape and digitization source (impression or stone replica) was pronounced (F=28; p<0.0001). The reliability was high for both digitization methods, evaluated by repeated digitizations. SIGNIFICANCE The exactness of the digitized impressions varied with shape. Both impressions and stone replicas can be digitized repeatedly with a high reliability.
-
6.
The reliability of computed tomography (CT) values and dimensional measurements of the oropharyngeal region using cone beam CT: comparison with multidetector CT.
Yamashina, A, Tanimoto, K, Sutthiprapaporn, P, Hayakawa, Y
Dento maxillo facial radiology. 2008;(5):245-51
Abstract
OBJECTIVES To evaluate the reliability of cone beam CT (CBCT) values and dimensional measurements of oropharyngeal air spaces as compared with those of multidetector row CT (MDCT). METHODS A soft tissue equivalent phantom with different sized holes was used. The phantom was scanned using CBCT and MDCT. In addition, a volunteer was examined using both methods for clinical comparison. The CT data were retrieved to a personal computer and treated using image processing software for three-dimensional rendering and dimensional measurements. The CT values of air, water and soft tissues were measured experimentally and the CT values of air, fat and muscle were measured in a clinical case. The diameter of each hole drilled in the phantom was measured on CBCT and MDCT images using the software tool and digimatic callipers. RESULTS The CBCT values were quite different from the Hounsfield units obtained with a typical MDCT system. The standard deviations were almost ten times larger with CBCT. In vivo assessment showed that the CBCT values for fat had a wide range that partially overlapped the values for muscle. The measurement of distances greater than 4 mm was consistent for all methods. The difference for holes was less than 0.2 mm. CONCLUSIONS The phantom study showed that CBCT provides limited quantitative CT values for each pixel on sliced images for differentiating air, water and soft tissues. However, the measurement of air spaces with CBCT was quite accurate.