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Radiologia 2012Dual-energy X-ray absorptiometry (DXA; DEXA) is the technique of choice to diagnose osteoporosis and to monitor the response to treatment. It is also useful for... (Review)
Review
Dual-energy X-ray absorptiometry (DXA; DEXA) is the technique of choice to diagnose osteoporosis and to monitor the response to treatment. It is also useful for measuring body composition. In recent years, new applications have been developed, including vertebral morphometry through the study of the lateral spine, prosthesis integration in orthopedics, and lipodystrophy in HIV+ patients, although its use in these cases is not well established. DXA densitometry is accurate and precise. It is essential to optimize each step of the diagnostic process, taking care to ensure the best acquisition, image analysis, and interpretation of the results. Thus, to obtain the greatest utility from DXA, radiologists need to know the technique, its indications, and its pitfalls. This article reviews the fundamentals, modalities, methods, and clinical applications of DXA.
Topics: Absorptiometry, Photon; Humans; Osteoporosis
PubMed: 22285678
DOI: 10.1016/j.rx.2011.09.023 -
Journal of AOAC International Aug 2021Paracetamol (PC) is one of the most widely used analgesic and antipyretic drugs and has recently been integrated into the supportive therapy of COVID-19. Pharmaceuticals...
BACKGROUND
Paracetamol (PC) is one of the most widely used analgesic and antipyretic drugs and has recently been integrated into the supportive therapy of COVID-19. Pharmaceuticals containing methionine (MT) with PC may contribute to avoid hepatotoxicity and eventual PC overdose-dependent death.
OBJECTIVE
The current work purposes to develop and validate two chromatographic methods for the simultaneous determination of MT and PC in the presence of two PC impurities (4-nitrophenol [NP] and 4-aminophenol [AP]).
METHOD
Two chromatographic methods were established and validated according to the International Conference on Harmonization guidelines. The first one was an RP-HPLC/UV method based on applying a "dual-mode" gradient elution. The separation was realized via varying both the composition of the ternary mobile phase (acetonitrile-methanol-water) and its flow rate. This strategy enabled a relatively rapid analysis with a satisfactory resolution, although the investigated compounds exhibit a significant difference in lipophilicity. The second one relied on TLC-densitometry, where the optimum separation was realized using a quaternary mobile phase system composed of butanol-dioxane-toluene-methanol (8:2.5:3.5:0.3, by volume). Both methods were monitored at 220 nm.
RESULTS
The developed methods were proven to be robust, accurate, specific, and appropriate for the routine analysis of PC in its pure form or in pharmaceutical formulations with MT in quality control laboratories.
CONCLUSIONS
The corresponding methods are suitable to determine MT and PC in the presence of PC impurities.
HIGHLIGHTS
The study achieves the analysis of MT and PC in the presence of PC impurities via the application of HPLC and TLC-densitometry methods.
Topics: Acetaminophen; COVID-19; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Densitometry; Humans; Methionine; Reproducibility of Results; SARS-CoV-2
PubMed: 33560299
DOI: 10.1093/jaoacint/qsab021 -
Journal of Optometry 2022To discriminate suspect glaucomatous from control eyes using corneal densitometry based on the statistical modeling of the pixel intensity distribution of Scheimpflug...
PURPOSE
To discriminate suspect glaucomatous from control eyes using corneal densitometry based on the statistical modeling of the pixel intensity distribution of Scheimpflug images.
METHODS
Twenty-four participants (10 suspect glaucomatous and 14 control eyes) were included in this retrospective study. Corneal biomechanics was assessed with the commercial Scheimpflug camera Corvis ST (Oculus). Sets of 140 images acquired per measurement were exported for further analysis. After corneal segmentation, pixel intensities corresponding to different corneal depths were statistically modeled for each image, from which corneal densitometry in the form of parameters α (brightness) and β (homogeneity) was derived. After data pre-processing, parameters α and β were input to six supervised machine learning algorithms that were trained, tested, and compared.
RESULTS
There exists a statistically significant difference in α and β parameters between suspect glaucomatous and control eyes (both, P < 0.05/N, Bonferroni). From the implemented supervised machine learning algorithms, the K-nearest neighbors (K-NN) algorithm reached 83.93% accuracy to discriminate between groups only using corneal densitometry parameters (α and β).
CONCLUSION
Densitometry of the anterior cornea including epithelium on its own has the potential to serve as a clinical tool for early glaucoma risk assessment.
Topics: Humans; Intraocular Pressure; Retrospective Studies; Cornea; Glaucoma; Machine Learning; Ocular Hypertension; Densitometry
PubMed: 36210294
DOI: 10.1016/j.optom.2022.09.002 -
Korean Journal of Ophthalmology : KJO Dec 2022To evaluate the long-term effects of uncomplicated traumatic hyphema on endothelial morphology, anterior segment structure, and corneal and lenticular densitometry.
PURPOSE
To evaluate the long-term effects of uncomplicated traumatic hyphema on endothelial morphology, anterior segment structure, and corneal and lenticular densitometry.
METHODS
In this retrospective comparative study, eyes with a history of uncomplicated traumatic hyphema were compared with the healthy contralateral unaffected eyes. The corneal endothelial cell properties were captured using specular microscopy. Anterior segment analysis, corneal densitometry (12-mm corneal diameter), and lens densitometry measurements were performed using the Pentacam imaging system.
RESULTS
Measurements were obtained at a mean follow-up of 49.5 ± 15.8 months after injury. The average endothelial cell density was significantly lower in the study group than in the control group (2,506.6 ± 294.0 cells/mm² vs. 2,665.7 ± 195.0 cells/mm², p = 0.020). There was no difference between the groups in respect of polymegathism and pleomorphism (p = 0.061 and p = 0.558, respectively). All the investigated corneal tomographic and angle parameters were similar in both groups (all p > 0.05). The corneal densitometry values in all concentric zones and layers showed no statistically significant difference between the groups (p > 0.05 for all). The lens zone 1 densitometry value was significantly higher in the study group than in the control group (9.6% ± 1.1% vs. 8.9% ± 1.2%, p = 0.031). No difference was observed in zone 2 and 3 (p = 0.170 and p = 0.322, respectively). The degree of hyphema was not correlated with endothelial cell and lenticular clarity loss (p = 0.087 and p = 0.294, respectively).
CONCLUSIONS
Even if traumatic hyphema is not complicated, long-term outcomes indicate endothelial cell loss and increased lenticular density.
Topics: Humans; Densitometry; Retrospective Studies; Cornea; Lens, Crystalline; Cross-Sectional Studies
PubMed: 36220635
DOI: 10.3341/kjo.2022.0098 -
BMC Ophthalmology Jun 2022To evaluate corneal densitometry after allogeneic corneal small-incision intrastromal lenticule implantation (SILI) for hyperopia.
PURPOSE
To evaluate corneal densitometry after allogeneic corneal small-incision intrastromal lenticule implantation (SILI) for hyperopia.
METHODS
A retrospective study. Thirty-one hyperopic eyes of 24 patients who underwent SILI were enrolled in this study. Examinations took place preoperatively and 1 week, 1 month, 3 months, and 6 months postoperatively. Corneal densitometry (CD) from different concentric radial zones (0-2, 2-6, and 6-10 mm annulus) and layers (anterior, central, and posterior) were obtained using Scheimpflug imaging. The association between CD changes and the uncorrected distance visual acuity (UDVA), spherical equivalent (SE), central corneal thickness (CCT) and K value were examined.
RESULTS
No serious intraoperative complications occurred during SILI. The mean total CD increased postoperatively compared to preoperatively (P < 0.01). However, no significant differences were found among the four subsequent follow-up time points (P > 0.05). At 6 months postoperatively, the CD values showed an increase of 2.71 ± 2.52, 2.23 ± 2.25, and 1.87 ± 2.46 at the 0-2, 2-6, and 6-10 mm annuli, respectively (all at P < 0.01). The anterior 120 μm displayed the highest densitometry before and after surgery (all at P < 0.01). No significant increase was found within the posterior 60 μm of the cornea (P > 0.05). No correlation was found between the CD and relevant parameters(all at P > 0.05).
CONCLUSIONS
SILI resulted in an increase in CD within the surgically altered area, however such change has no significant correlation with visual outcomes.
Topics: Cornea; Corneal Stroma; Corneal Topography; Densitometry; Hematopoietic Stem Cell Transplantation; Humans; Hyperopia; Retrospective Studies
PubMed: 35764952
DOI: 10.1186/s12886-022-02454-3 -
Photodiagnosis and Photodynamic Therapy Apr 2024Examination of corneal densitometry measurements using the Pentacam Scheimpflug imaging system in cases of pseudoexfoliative glaucoma (PEXG) and ocular hypertension...
BACKGROUND
Examination of corneal densitometry measurements using the Pentacam Scheimpflug imaging system in cases of pseudoexfoliative glaucoma (PEXG) and ocular hypertension (OHT).
METHODS
The study included 50 eyes of 29 PEXG patients, 25 eyes of 16 OHT patients, and 76 eyes of 38 healthy control subjects followed in the glaucoma clinic. Corneal densitometry values of all cases were measured using the Scheimpflug imaging system (Pentacam, Oculus, Germany). Corneal densitometry was assessed based on 4 concentric radial zones (0-2 mm, 2-6 mm, 6-10 mm, and 10-12 mm) and depths (anterior, central, posterior, and total) within the Scheimpflug imaging system. The results were statistically analyzed.
RESULTS
Corneal densitometry values examined between the OHT and control groups were higher in OHT and statistically significant (p < 0.05). Corneal densitometry values examined between the PEXG and control groups were higher in PEXG and statistically significant (p < 0.05). In comparison between the PEXG and OHT groups, corneal densitometry values in the central 0-2 mm, 2-6 mm, and 6-10 mm; posterior 0-2 mm and 2-6 mm radial zones were higher in PEXG and statistically significant (p < 0.05).
CONCLUSIONS
It was observed that elevated intraocular pressure levels in OHT cases could lead to changes in the cornea, consequently increasing corneal densitometry values. The higher corneal densitometry values in PEXG cases compared to OHT were attributed to the accumulation of pseudoexfoliative material in the cornea. Based on our study, corneal densitometry could serve as a potential biomarker for early glaucoma detection in OHT cases and could be employed to assess corneal transparency during the follow-up of PEXG cases.
Topics: Humans; Densitometry; Female; Cornea; Ocular Hypertension; Male; Aged; Exfoliation Syndrome; Middle Aged; Case-Control Studies
PubMed: 38368915
DOI: 10.1016/j.pdpdt.2024.103988 -
Indian Journal of Ophthalmology May 2022To evaluate corneal densitometry (CD) of patients with arcus senilis (AS) and its association with the serum lipid markers.
PURPOSE
To evaluate corneal densitometry (CD) of patients with arcus senilis (AS) and its association with the serum lipid markers.
METHODS
This is a cross-sectional, case-control study. The AS diagnosis was made clinically. Forty-five eyes of 45 patients with AS and 38 eyes of 38 age-matched control subjects with no noticeable AS were enrolled in the study. All participants underwent detailed ophthalmologic examination along with corneal Scheimpflug imaging with CD measurement. The evaluated serum lipid markers of the participants included total cholesterol, triglyceride, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and very-low-density lipoprotein (VLDL). The Spearman correlation analysis was used to correlate the serum lipid values and the CD. P < 0.05 was defined as statistically significant.
RESULTS
The male to female ratio was 26/19 and 14/24 in the study and control groups, respectively (P = 0.057). The mean age was 59.56 ± 8.7 and 56.47 ± 8.6 years in the study and control groups, respectively (P = 0.117). The mean total CD values in the zones extending from 2 to 12 mm were higher in the study group than in the control group (P < 0.001). The serum HDL level was found to be significantly decreased in the study group compared to the control group (P = 0.048 and Z = -1.976). There was a significant positive correlation between the serum triglyceride level and the CD value of the outermost zone (10-12 mm) (r = 0.334 and P = 0.025).
CONCLUSION
The CD of patients with AS was found to increase not only in the peripheral zone but also in the cornea's paracentral zone compared to the healthy controls. The serum triglyceride level should give an insight into the intensity of arcus senilis. The serum HDL levels were decreased in patients with AS.
Topics: Aged; Arcus Senilis; Case-Control Studies; Cornea; Cross-Sectional Studies; Densitometry; Female; Humans; Male; Middle Aged; Triglycerides
PubMed: 35502026
DOI: 10.4103/ijo.IJO_2696_21 -
Eye (London, England) Dec 2017PurposeThe aim of this study was to gain greater insight into the corneal densitometry changes occurring as a result of refractive surgery and to compare these changes...
PurposeThe aim of this study was to gain greater insight into the corneal densitometry changes occurring as a result of refractive surgery and to compare these changes across three widely used surgical techniques, namely, photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis with a femtosecond laser (LASIK-FS), or ReLEx small-incision lenticule extraction (ReLEx SMILE).Patients and methodsThree hundred and thirty-six patients (184 male and 152 female patients) participated in this study. They were split into three groups according to the refractive surgery technique they had undergone: LASIK-FS (74 patients), PRK (153 patients), and ReLEx SMILE (109 patients). All participants underwent an exhaustive eye examination both before and after surgery. Pre- and postoperative corneal densitometry was measured using an Oculus Pentacam system.ResultsThe mean postoperative total corneal densitometry values were 16.53±1.94 for the LASIK-FS group, 15.53±1.65 for PRK, and 16.10±1.54 for ReLEx SMILE. When corneal densitometry was analyzed for specific corneal areas, the values corresponding to the 0-2, 2-6, and 6-10 mm annuli were similar across the three surgical techniques. The only region in which differences were found was the peripheral area (P<0.05), but these variations across techniques were not statistically significant.ConclusionsCorneal densitometry can be used as an objective metric to assess corneal response to refractive surgery, and to monitor patients over time. Corneal densitometry was not negatively affected by any of the refractive surgical procedures under evaluation.
Topics: Adult; Cornea; Densitometry; Female; Follow-Up Studies; Humans; Keratomileusis, Laser In Situ; Lasers, Excimer; Male; Myopia; Photorefractive Keratectomy; Postoperative Period; Prospective Studies; Refraction, Ocular; Time Factors; Treatment Outcome
PubMed: 28622316
DOI: 10.1038/eye.2017.107 -
BMC Musculoskeletal Disorders Apr 2022Early detection and timely prophylaxis can retard the progression of osteoporosis. The purpose of this study was to determine the validity of peripheral Dual Energy...
BACKGROUND
Early detection and timely prophylaxis can retard the progression of osteoporosis. The purpose of this study was to determine the validity of peripheral Dual Energy X-ray Absorptiometry (DXA) test for osteoporosis screening. We examined peripheral bone mineral density (BMD) using AKDX-09 W-I DXA densitometer. Firstly, we acquired BMD data from manufacturer-supplied density-gradient phantoms and 30 volunteers to investigate its accuracy and precision, then we measured BMD for 150 volunteers using both AKDX (left forearm) and Hologic Discovery Wi (left forearm, left hip and L1 - L4 vertebrae) simultaneously. Correlation relationship of BMD results acquired from two instruments was assessed by simple linear regression analysis, the Receiver Operating Characteristic (ROC) curves and Areas Under the Curves (AUCs) were evaluated for the diagnostic value of left forearm BMD measured by AKDX in detecting osteoporosis.
RESULTS
In vitro precision errors of AKDX BMD were 0.40, 0.20, 0.19%, respectively, on low-, medium-, and high-density phantom; in vivo precision was 1.65%. Positive correlation was observed between BMD measured by AKDX and Hologic at the forearm (r = 0.670), L1-L4 (r = 0.430, femoral neck (r = 0.449), and total hip (r = 0.559). With Hologic measured T-score as the gold standard, the sensitivity of AKDX T-score < - 1 for identifying suboptimal bone health was 63.0 and 76.1%, respectively, at the distal one-third radius and at any site, and the specificity was 73.9 and 90.0%, respectively; the AUCs were 0.708 and 0.879. The sensitivity of AKDX T-score ≤ - 2.5 for identifying osteoporosis at the distal one-third radius and at any site was 76.9 and70.4%, respectively, and the specificity was 80.4 and 78.0%, respectively; the AUCs were 0.823 and 0.778.
CONCLUSIONS
Peripheral DXA appears to be a reliable tool for prescreening for osteoporosis.
Topics: Absorptiometry, Photon; Bone Density; Femur Neck; Forearm; Humans; Osteoporosis
PubMed: 35459140
DOI: 10.1186/s12891-022-05325-6 -
BMC Ophthalmology Mar 2023To quantitatively investigate corneal changes and the correlation between corneal densitometry (CD) and endothelial parameters after phacovitrectomy.
BACKGROUND
To quantitatively investigate corneal changes and the correlation between corneal densitometry (CD) and endothelial parameters after phacovitrectomy.
METHODS
Thirty-eight eyes with idiopathic full-thickness macular holes (iFTMHs) and cataracts underwent phacovitrectomy. Examinations were conducted at baseline and Day 1, Day 7, Month 1, and Month 3 postoperatively. CD and central corneal thickness (CCT) were measured using Pentacam. Corneal endothelial cell density (ECD), coefficient of variation (CV), and hexagonality (HEX) were measured using specular microscopy.
RESULTS
ECD and HEX significantly decreased after surgery and the change in HEX occurred prior to CV. CCT increased immediately after surgery and recovered 3 months postoperatively. CD values increased significantly 1 day after surgery and then gradually decreased. For CD in the 0-2 mm zone, it took 1 month to recover in the central and posterior layers and 3 months in the anterior and total layers. For CD in the 2-6 mm zone, the central layer recovered at Day 7, the anterior and total layers recovered at 1 month, and the posterior layer did not recover until 3 months postoperatively. The CD within all layers in the 0-2 mm zone was positively correlated with CCT. Posterior CD in the 0-2 mm zone was negatively correlated with ECD and HEX.
CONCLUSIONS
CD is not only correlated with CCT, ECD, and HEX but also reflects the state of the whole cornea and each layer. CD can be an objective, rapid, and noninvasive tool that reflects corneal health and undetectable edema and monitors the process of lesion repair.
TRIAL REGISTRATION
This study was registered with the Chinese Clinical Trial Registry (31/10/2021, ChiCTR2100052554).
Topics: Humans; Cataract; Cornea; Densitometry; Physical Examination
PubMed: 36879221
DOI: 10.1186/s12886-023-02818-3