Very-high-frequency ultrasound corneal imaging as a new tool for early diagnosis of ocular surface toxicity in rabbits treated with a preserved glaucoma drug.

AIM: To evaluate very-high-frequency (VHF) ultrasound imaging as a new method to detect and quantify early corneal epithelium changes induced by chronic exposure to a benzalkonium-chloride-containing antiglaucoma drug. METHODS: Timolol preserved with 0.01% benzalkonium chloride solution was applied b.i.d. in 1 eye of 10 rabbits for 56 days. Unpreserved timolol solution was used as control. Ocular surface changes were assessed weekly combining clinical examinations, in vivo 60-MHz ultrasound imaging and ex vivo histological analysis. RESULTS: VHF ultrasound imaging allowed quantitative measurement of corneal epithelium thickness and qualitative imaging of toxic epithelial damage. It revealed significantly decreased epithelial thickness in vivo as early as the 21st day of treatment (40.75 +/- 1.72 microm at D0 vs. 39 +/- 2 at D21, vs. 31.9 +/- 2.98 at D56; p = 0.017 and p = 0.005, respectively). The first clinical changes appeared from the 42nd day of treatment (conjunctival redness, conjunctival staining and corneal staining; D56 compared to D0: p = 0.005, 0.01 and 0.004, respectively) and then correlated with VHF ultrasound data. Epithelial thickness measured with VHF ultrasound was correlated with histological epithelial pachymetry (p < 0.001) and with the corneal damage score assessed with scanning electron microscopy (p = 0.038). CONCLUSION: VHF ultrasound imaging provided an early in vivo diagnosis of corneal epithelium pathology induced by chronic exposure to a preserved glaucoma drug, before the first clinical evidence of ocular toxicity. It could be a new reproducible method to detect the toxicity of glaucoma medication so that therapy can then be adapted.

Constant delay in adapted cerebral response to light stimulation in premature neonates: a transcranial Doppler study.

Transcranial Doppler has been used previously to determine hemodynamic response to sensorial stimulation in adults but not in the neonatal period. Cerebral blood flow velocity (CBFV) was recorded in both middle cerebral arteries (MCA) and posterior cerebral arteries (PCA) in 100 premature neonates (male 56; female 44; 26 to 36 weeks gestation) from birth to 12 months. Brain development was evaluated on clinical examination. No difference in velocities was noted on prestimulation recordings from birth to 12 months. During light stimulation before six months, the CBFV was reduced (-11 +/- 6% in MCA and -13 +/- 5% in PCA compared with baseline values). After stimulation, the CBFV was increased (+6.7 +/- 3% in MCA and + 10.5 +/- 4% in PCA compared with baseline values). This study is in favor of cortex maturation in normal premature neonates at only six months. Consequently, functional transcranial Doppler technique will be helpful for the diagnosis of abnormal maturation timing in neonates with possible developmental retardation.

Differential diagnosis of focal nodular hyperplasia with quantitative parametric analysis in contrast-enhanced sonography.

OBJECTIVES: We investigated the potential of quantitative parametric analysis in the differential diagnosis of focal nodular hyperplasia (FNH) from other hypervascularized liver focal lesions. MATERIALS AND METHODS: Eighty-five focal liver lesions (in 83 patients) were explored using contrast-enhanced ultrasound (SonoVue and Cadence Contrast Pulse Sequencing) consisting of typical FNH (n=52), hepatocellular carcinoma (n=11), hemangioma with high flow (n=8), hypervascular metastases (n=10), and hepatocellular adenoma (n=4). QontraXt software (AMID, Italy) was used here to estimate the following parameters: maximum peak value, Tr (time corresponding to time for obtaining 63% of the plateau), beta parameter corresponding to the exponential factor, and slope corresponding to the tangent value of the first phase of enhancement. These parameters were obtained from the time-intensity curves derived from the enhancement observed in 2 regions of interest corresponding, respectively, to the whole lesion and the central region only. RESULTS: A significant statistical difference (P<0.05) was found in the values of Tr, beta, and slope between FNH and other hypervascularized lesions on both the whole lesion and central region. Among these parameters, slope appeared as the most valuable whatever the region of interest, ie, central or whole lesion (P<0.01). Central region was more accurate in the differentiation of FNH and concordant with visual characterization. CONCLUSION: Quantitative parametric curve analysis of the different hypervascularized lesions confirms the depiction of the central artery in FNH and thus could help in differentiating this specific focal liver lesion from the others.

Towards a quantitative in vivo evaluation of venous blood echogenicity: image processing versus subjective assessment.

PURPOSE: Spontaneous blood echogenicity in vein ultrasound images may be a marker for an increased erythrocyte aggregability, but a reliable quantitative evaluation method is a prerequisite for its use in clinical studies. We compared a simple scoring system of blood echogenicity intensity and pattern, with automatic image analysis. MATERIAL AND METHODS: 157 femoral and popliteal vein digitized ultrasound sequences were reviewed by two independent observers who chose an image, delimited an area of interest (ROI), and graded blood echogenicity intensity and pattern, using a four class score. Each observer reviewed the images selected by the other, without and with ROI. The computer calculated first and second order parameters describing echo intensity and spatial organization. RESULTS: Inter-observer reproducibility of subjective assessment was poor (Kappa<0.5), whereas the automatically calculated ROI average gray level intensity relatively to the whole image (tau(1)) effectively separated all grades of intensity. No parameter effectively separated patterns. CONCLUSION: Tau(1) is a simple parameter for the in vivo evaluation of blood echogenicity intensity. It should be evaluated in standardized conditions for clinical hemorheology studies in correlation with in vitro erythrocyte aggregation measurements.

Ultrasound-guided collection of amniotic fluid in pregnant rats.

Here we present an echographic method to withdraw amniotic fluid from pregnant rats. The method could be an alternative to the surgical amniotic fluid collection methods used currently. On day 18 of gestation, pregnant Sprague-Dawley rats underwent amniotic sac puncture by either surgical procedure or echographically guided method. This study evaluated the effect of the 2 collection procedures on parturition day, number of pups per litter, and weight of newborns compared with those of a control group without any fluid collection. These parameters did not differ statistically across groups. However, the echographically guided method did not require surgery or postsurgical recovery and was therefore advantageous from the perspective of animal use. Moreover ultrasound-guided collection allows experimental designs that require collection of multiple samples from the same animal during a single pregnancy.

Color Doppler imaging of orbital vessels: personal experience and literature review.

Many Doppler imaging studies have been performed in recent years in a large number of ocular disorders because of improvements in the Doppler equipment used for detecting and measuring the low blood-flow velocities that are a requisite for the quantitative evaluation of blood flow in the orbital vessels. The ophthalmic artery, central retinal artery and vein, posterior ciliary arteries, and the superior ophthalmic vein can be easily identified using color Doppler sonography. The changes in local blood flow in these vessels assessed by spectral analysis pulsed Doppler sonography have been used to characterize and to obtain new insights into different nontumoral vascular disorders including carotid artery stenosis, central retinal vein occlusion, giant cell arteritis, glaucoma, diabetes, fistulas, and tumoral processes of the eye and orbit. Our experience has confirmed the important role of Doppler sonography in the assessment of subclinical changes in the vascular bed, in the understanding of different processes, for following up after specific treatments, and for determining the long-term prognosis of these various conditions.