Inter- and intra-observer agreement in dermatologists' diagnoses of hyperpigmented facial lesions and development of an algorithm for automated diagnosis.

BACKGROUND: Hyperpigmentation has varied aetio-pathologies. Hence, accurate and reproducible diagnosis of the type of hyperpigmentation is essential for effective management. It is typically made clinically by dermatologists but the rate of inter- and intra-observer agreement/variability is unknown. Hyperpigmented facial lesions are extremely common but access to dermatological services is difficult or costly in most countries. Thus, it is desired to evaluate dermatologists' inter- and intra-observer agreement in the diagnosis and to develop an algorithm for automated diagnosis. MATERIALS AND METHODS: Hyperpigmented lesions on 392 facial images were diagnosed by three experienced dermatologists either jointly or independently, and this process was subsequently repeated for 52 randomly selected images. When there was non-concordance amongst the dermatologists for the diagnosis, a majority decision was taken as correct diagnosis. Inter-observer and intra-observer agreement were analysed for the diagnosis of the hyperpigmented lesions. Thereafter, a multiclass classification method was developed to perform the task in an automatic manner. The developed algorithm was compared and validated against the ground truth derived from the dermatologists. RESULTS: Both inter- and intra-observer agreements are in the moderate range. The algorithm agreed well with the derived ground truth, with a Kappa value of 0.492, which is similar to the Kappa values of inter- and intra- observer agreements. CONCLUSION: The rates of inter- and intra-observer agreement in the diagnosis of hyperpigmented facial lesions amongst dermatologists were moderate in this study. Compared to visual assessment from the dermatologists, automated diagnosis using the developed algorithm achieved a high rate of concordance.

New image analysis tool for facial pore characterization and assessment.

BACKGROUND: Visible facial pores are an important cosmetic concern especially among young females. Number of different methodologies is used today to assess facial pores and efficacy of technologies. Main limitations of these methods are, however, (a) moderate correlation with visual perception, (b) characterization is mostly limited to size or number of pores, (c) measurement is limited to a smaller area of face, and (d) operational difficulties. In order to address these limitations, we developed a 2D image analysis tool to assess and characterize visible facial pores. MATERIALS AND METHODS: Two clinical studies were conducted with northeast Asian skin type females. In the first study, 40 subjects age between 20 and 40 with different degree of pore severity were recruited. In the second study, 15 subjects age between 20 and 40 with enlarged pores were recruited to evaluate pore product efficacy. In both studies, full face images were taken using Visia-CR and assessed by means of the newly developed tool and visual grading. RESULTS: A high correlation between visual grading and pore size was obtained (r = 0.86). New methodology was able to differentiate products similar to visual grading. CONCLUSION: Novel pore image analysis method using 2D skin surface imaging with standard photography has been developed and validated. In addition to pore size measurements, we propose this method to be used to measure pore shape, color, and orientation for a comprehensive characterization of facial pores.

Measurement of cytotoxic and interstitial components of cerebral edema in acute hepatic failure by diffusion tensor imaging.

PURPOSE: To use diffusion tensor imaging (DTI) metrics for measuring cytotoxic and interstitial components of cerebral edema (CE) in acute hepatic failure (AHF) patients. CE is a major complication in patients with AHF. MATERIALS AND METHODS: DTI was performed in 20 patients with AHF and 15 controls. Ten patients underwent repeat imaging after recovery from encephalopathy. Various regions of interest (ROIs) were drawn in the white and deep gray matter of the brain for the quantitation of fractional anisotropy (FA), mean diffusivity (MD), spherical isotropy (CS), linear anisotropy (CL), and planar anisotropy (CP) values. RESULTS: Significantly decreased MD values were observed in most brain ROIs in patients compared to controls. Significantly decreased FA, CL with increased CS values was also observed. In survivors with normal clinical profile after 3 weeks, a significant increase in MD and FA values were associated with decreased CS values in some regions compared to baseline study; however, it was still significantly changed compared to controls. CONCLUSION: Decreased MD and increased CS associated with decreased FA represent cytotoxic and interstitial components of CE, respectively. Incomplete normalization of these metrics in survivors after 3 weeks clinical recovery may be due to incomplete metabolic recovery.

Cerebral diffusion tensor imaging and in vivo proton magnetic resonance spectroscopy in patients with fulminant hepatic failure.

BACKGROUND AND AIM: Cerebral edema is a major complication in patients with fulminant hepatic failure (FHF). The aim of this study was to evaluate the metabolite alterations and cerebral edema in patients with FHF using in vivo proton magnetic resonance spectroscopy (MRS) and diffusion tensor imaging, and to look for its reversibility in survivors. METHODS: Ten FHF patients along with 10 controls were studied. Five of the 10 patients who recovered had a repeat imaging after three weeks. N-acetylaspartate, choline (Cho), glutamine (Gln), glutamine/glutamate (Glx), and myoinositol ratios were calculated with respect to creatine (Cr). Mean diffusivity (MD) and fractional anisotropy (FA) were calculated in different brain regions. RESULTS: Patients exhibited significantly increased Gln/Cr and Glx/Cr, and reduced Cho/Cr ratios, compared to controls. In the follow-up study, all metabolite ratios were normalized except Glx/Cr. Significantly decreased Cho/Cr were observed in deceased patients compared to controls. In patients, significantly decreased MD and FA values were observed in most topographical locations of the brain compared to controls. MD and FA values showed insignificant increase in the follow-up study compared to their first study. CONCLUSIONS: We conclude that the Cho/Cr ratio appears to be an in vivo marker of prognosis in FHF. Decreased MD values suggest predominant cytotoxic edema may be present. Persistence of imaging and MRS abnormalities at three weeks' clinical recovery suggests that metabolic recovery may take longer than clinical recovery in FHF patients.

Quantification of physiological and hemodynamic indices using T(1) dynamic contrast-enhanced MRI in intracranial mass lesions.

PURPOSE: To estimate precontrast tissue parameter (T(10)) using fast spin echo (FSE) and to quantify physiological and hemodynamic parameters with leakage correction using T(1)-weighted dynamic contrast-enhanced (DCE) perfusion imaging. MATERIALS AND METHODS: Voxel-wise T(10) computation was performed followed by the analysis of T(1)-weighted DCE perfusion data for the conversion of signal intensity time curve to concentration time curve, estimation of hemodynamic and physiological perfusion indices, and a method for leakage correction. Validations of accuracy of the computations have also been carried out. RESULTS: The computed T(10) and hemodynamic perfusion indices in normal white and gray matter were in good agreement with the literature values. Physiological perfusion indices in these regions were found negligible, validating computations. Cerebral blood volume (CBV) values change negligibly over the length of concentration time curve in white matter, gray matter, and lesion (CBV(corrected)), while CBV(uncorrected) (lesion) shows linear increase over time. CONCLUSION: T(1)-weighted DCE perfusion data along with FSE-based T(1) estimation can be used for an accurate estimation of hemodynamic and physiological perfusion indices.

Increased anisotropy in neonatal meningitis: an indicator of meningeal inflammation.

INTRODUCTION: Increased anisotropy in brain abscesses has been shown to be due to adhesion of inflammatory cells and is suggestive of an active inflammatory process. The objective of this study was to determine if similar changes occur in the pia-arachnoid on the surface of the cerebral cortex in patients with pyogenic meningitis, and if these changes regress following antibiotic therapy. METHODS: Diffusion tensor imaging (DTI) was performed on 14 term neonates (mean age 13 days) with bacterial meningitis and 10 healthy age- and sex-matched controls. Regions of interest (ROIs) were placed on areas including the leptomeninges, the cerebral cortex and adjoining subcortical white matter for quantitation of mean fractional anisotropy (FA) and diffusivity (MD) values. Follow-up MRI was performed in five of the neonates in the patient group after 2 weeks of antibiotic treatment. FA and MD values were compared in patients before and after antibiotic treatment as well as with those in the healthy controls. RESULTS: Significantly higher FA values but no difference in MD values were observed in the patient group as compared to the healthy controls at both time points (before and after antibiotic treatment). Significantly decreased FA values in the frontal, occipital and temporal cortical regions were observed in patients following antibiotic treatment. CONCLUSION: DTI-derived FA may be of value in the noninvasive assessment of meningeal inflammatory activity and treatment response in neonates.

Biological correlates of diffusivity in brain abscess.

Restricted diffusion in brain abscess is assumed to be due to a combination of inflammatory cells, necrotic debris, viscosity, and macromolecules present in the pus. We performed diffusion-weighted imaging (DWI) on 41 patients with proven brain abscesses (36 pyogenic and five tuberculous), and correlated the apparent diffusion coefficient (ADC) from the abscess cavity with viable cell density, viscosity, and extracellular-protein content quantified from the pus. On the basis of the correlation between cell density and ADC in animal tumor models and human tumors in the literature, we assumed that the restricted ADC represents the cellular portion in the abscess cavity. We calculated restricted and unrestricted lesion volumes, and modeled cell density over the restricted area with viable cell density per mm(3) obtained from the pus. The mean restricted ADC in the cavity (0.65 +/- 0.01 x 10(-3) mm(2)/s) correlated inversely with restricted cell density in both the pyogenic (r = -0.90, P = <0.05) and tuberculous (0.60 +/- 0.04 x 10(-3) mm(2)/s, r = -0.94, P = <0.05) abscesses. We conclude that viable cell density is the main biological parameter responsible for restricted diffusion in brain abscess, and it is not influenced by the etiological agents responsible for its causation.