The Role of Hemodynamics in Intracranial Bifurcation Arteries after Aneurysm Treatment with Flow-Diverter Stents.

BACKGROUND AND PURPOSE: Treatment of intracranial bifurcation aneurysms with flow-diverter stents can lead to caliber changes of the distal vessels in a subacute phase. This study aims to evaluate whether local anatomy and flow disruption induced by flow-diverter stents are associated with vessel caliber changes in intracranial bifurcations. MATERIALS AND METHODS: Radiologic images and demographic data were acquired for 25 patients with bifurcation aneurysms treated with flow-diverter stents. Whisker plots and Mann-Whitney rank sum tests were used to evaluate if anatomic data and caliber changes could be linked. Symmetry/asymmetry were defined as diameter ratio 1 = symmetric and diameter ratio <1 = asymmetric. Computational fluid dynamics was performed on idealized and patient-specific anatomies to evaluate flow changes induced by flow-diverter stents in the jailed vessel. RESULTS: Statistical analysis identified a marked correspondence between asymmetric bifurcation and caliber change. Symmetry ratios were lower for cases showing narrowing or subacute occlusion (medium daughter vessel diameter ratio = 0.59) compared with cases with posttreatment caliber conservation (medium daughter vessel diameter ratio = 0.95). Computational fluid dynamics analysis in idealized and patient-specific anatomies showed that wall shear stress in the jailed vessel was more affected when flow-diverter stents were deployed in asymmetric bifurcations (diameter ratio <0.65) and less affected when deployed in symmetric anatomies (diameter ratio ∼1.00). CONCLUSIONS: Anatomic data analysis showed statistically significant correspondence between caliber changes and bifurcation asymmetry characterized by diameter ratio <0.7 (P < .001). Similarly, computational fluid dynamics results showed the highest impact on hemodynamics when flow-diverter stents are deployed in asymmetric bifurcations (diameter ratio <0.65) with noticeable changes on wall sheer stress fields. Further research and clinical validation are necessary to identify all elements involved in vessel caliber changes after flow-diverter stent procedures.

Evaluation of the clinical benefit of an electromagnetic navigation system for CT-guided interventional radiology procedures in the thoraco-abdominal region compared with conventional CT guidance (CTNAV II): study protocol for a randomised controlled trial.

BACKGROUND: Interventional radiology includes a range of minimally invasive image-guided diagnostic and therapeutic procedures that have become routine clinical practice. Each procedure involves a percutaneous needle insertion, often guided using computed tomography (CT) because of its availability and usability. However, procedures remain complicated, in particular when an obstacle must be avoided, meaning that an oblique trajectory is required. Navigation systems track the operator's instruments, meaning the position and progression of the instruments are visualised in real time on the patient's images. A novel electromagnetic navigation system for CT-guided interventional procedures (IMACTIS-CT®) has been developed, and a previous clinical trial demonstrated improved needle placement accuracy in navigation-assisted procedures. In the present trial, we are evaluating the clinical benefit of the navigation system during the needle insertion step of CT-guided procedures in the thoraco-abdominal region. METHODS/DESIGN: This study is designed as an open, multicentre, prospective, randomised, controlled interventional clinical trial and is structured as a standard two-arm, parallel-design, individually randomised trial. A maximum of 500 patients will be enrolled. In the experimental arm (navigation system), the procedures are carried out using navigation assistance, and in the active comparator arm (CT), the procedures are carried out with conventional CT guidance. The randomisation is stratified by centre and by the expected difficulty of the procedure. The primary outcome of the trial is a combined criterion to assess the safety (number of serious adverse events), efficacy (number of targets reached) and performance (number of control scans acquired) of navigation-assisted, CT-guided procedures as evaluated by a blinded radiologist and confirmed by an expert committee in case of discordance. The secondary outcomes are (1) the duration of the procedure, (2) the satisfaction of the operator and (3) the irradiation dose delivered, with (4) subgroup analysis according to the expected difficulty of the procedure, as well as an evaluation of (5) the usability of the device. DISCUSSION: This trial addresses the lack of published high-level evidence studies in which navigation-assisted CT-guided interventional procedures are evaluated. This trial is important because it addresses the problems associated with conventional CT guidance and is particularly relevant because the number of interventional radiology procedures carried out in routine clinical practice is increasing. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01896219 . Registered on 5 July 2013.

High-frequency ultrasound quantification of acute radiation dermatitis: pilot study of patients undergoing radiotherapy for breast cancer.

BACKGROUND: Acute radiation dermatitis (ARD) is a frequent complication after breast cancer radiotherapy and is usually assessed by semi-quantitative clinical scores, which may be subject to inter-observer variability. High-frequency ultrasound imaging of the skin can reliably quantify thickness and edema in diseased skin. We aimed to compare the relative increase in dermal thickness of the irradiated zone in breast-cancer patients undergoing radiotherapy, with clinical severity. METHODS: A consecutive series of patients undergoing treatment for breast cancer by lumpectomy and radiotherapy in a 6-month period also underwent clinical and ultrasound evaluation of ARD. RESULTS: We included 34 female patients 17 had grade 1 (group 1), 17 had grade 2 or grade 3 ARD (group 2). The mean relative increase in dermal thickness in irradiated skin (RIDTIS) was greater for group 2 than 1: 0.53 vs 0.29 mm (P=.023). On univariate analysis, ARD was associated with skin phototype, breast volume and RIDTIS, and on multivariable analysis, breast volume and age remained predictive of the disease. CONCLUSION: Patients with more severe dermatitis showed significantly increased dermal thickness. Dermal thickness is a quantitative variable that could help quantify the efficacy of drugs and improve the treatment of this disease in patients undergoing radiotherapy.

Comparison between Doppler ultrasonography and multiphase multidetector-row computed tomography in the detection of liver involvement in Rendu-Osler disease: An analysis of 62 patients.

PURPOSE: To evaluate the agreement between the Buscarini criteria on ultrasound (US) and multiphase contrast-enhanced multidetector-row computed tomography (MDCT) in the diagnosis and staging of liver involvement in hereditary hemorrhagic telangiectasia (HHT) (i.e., Rendu-Osler disease). To evaluate the role of variations in hepatic artery anatomy in the production of disagreement between these two imaging techniques. MATERIALS AND METHODS: This single center retrospective study included 62 patients with confirmed or suspected HHT. Each patient underwent Doppler US analyzed according to the Buscarini criteria and arterial and portal phase MDCT on the same day or one day apart. Liver involvement was classified as absent, slight, moderate or severe for each examination. Agreement was evaluated by the kappa and Bhapkar tests. Variations in hepatic arterial anatomy was analyzed by MDCT based on the Michel's classification and analysis of agreement and disagreement was performed using the Chi(2) test. RESULTS: Significant disagreement was identified between the two tests in 29 patients with κ=0.376 and a Bhapkar critical probability of P=0.0053. Staging of liver involvement was significantly more severe with MDCT in case of disagreement. A variant hepatic artery anatomy was identified in 12 patients with agreement and 7 patients with disagreement, but the difference was not significant (Chi(2)=0.297). CONCLUSION: The results of our study confirm the importance of associating contrast-enhanced MDCT with Doppler US in the evaluation of liver involvement in patients with HHT.

Computed tomographic study of anatomical relationship between pubic symphysis and ischial spines to improve interpretation of intrapartum translabial ultrasound.

OBJECTIVE: To analyze the anatomical relationship between the pubic symphysis and the ischial spines to determine reliable landmarks for the assessment of fetal head descent by intrapartum translabial ultrasound (ITU). METHODS: All computed tomography (CT) scans performed for breech presentation and for twin delivery between 2006 and 2014 in a tertiary university hospital were obtained for measurement and analysis by two operators. The symphysis-left ischial spine angle (SIA) and the symphysis-left ischial spine distance (SID) were measured on three-dimensional reconstructions from the CT volume dataset. We calculated intra- and interobserver agreements for SIA and SID with 95% prediction intervals, created Bland-Altman plots with 95% limits of agreement and estimated the intraclass correlation coefficient (ICC). A sagittal plane projection from the SIA enabled calculation of a sagittal angle, corresponding to the angle of progression (AoP) on ITU. RESULTS: SIA and SID were obtained from CT images from 458 women. Reproducibility was good for both SIA (intraobserver ICC, 0.94 (95% CI, 0.88-0.97) and interobserver ICC, 0.81 (95% CI, 0.66-0.92)) and SID (intraobserver ICC, 0.92 (95% CI, 0.82-0.97) and interobserver ICC, 0.83 (95% CI, 0.73-0.92)). The median SIA was 106° (interquartile range (IQR), 105-109°) and median SID was 26.1 (IQR, 23.4-29.5) mm. SIA and SID were not correlated with pelvic diameter or height. The 50th percentile of AoP was 110°. CONCLUSION: Knowledge of the anatomical relationship between the pubic symphysis and ischial spines makes it possible to establish a sonographic method for assesssing fetal head descent by taking into account the level of the ischial spines. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

[Predictive factors for visual outcome after corneal collagen crosslinking treatment in progressive keratoconus: One-year refractive and topographic results]. / Facteurs prédictifs de bonne réponse au crosslinking d'un kératocône évolutif : résultats réfractifs et topographiques à un an postopératoire.

PURPOSE: To assess the effects of preoperative patient characteristics on clinical outcomes of corneal collagen crosslinking (CXL) in patients with progressive keratoconus. PATIENTS AND METHODS: Fifty-four eyes of 41 patients underwent CXL for progressive keratoconus between June 2011 and December 2012. Corneal topography (Orbscan(®)) was assessed at 1, 3, and 6 months and 1 year after CXL treatment and compared with preoperative data. RESULTS: A significant improvement in 1-year postoperative best-corrected visual acuity (BCVA) (0.16±0.21 LogMar preoperatively versus 0.09±0.16 LogMar postoperatively, P=0.007) and in 3mm topographic central irregular astigmatism (P=0.04) was demonstrated with CXL. No significant change was noted for refractive astigmatism (P=0.69), or for 1-year postoperative Kmax (48.4 D±4.1 at baseline versus 48.5 D±4.1 postoperatively, P=0.46). Predictive factors for BVCA improvement were low preoperative BCVA, high refractive astigmatism and advanced keratoconus. Predictive factors for stability of postoperative Kmax values were early keratoconus, and central cone ("nipple" morphology of the cone mainly located in the central 3mm of the cornea). CONCLUSION: This retrospective study confirms the efficacy of CXL for progressive keratoconus, from a refractive as well as topographic standpoint. While cone localization or its eccentricity seems to explain the variability of CXL efficacy reported in the literature, cone severity appears to be the main predictive factor for a lack of topographic stability after CXL treatment but must be weighted by the preferential localization of the cone (3 or 5mm central corneal zone).

Measurement of skin thickness and skin elasticity to evaluate the effectiveness of intensive decongestive treatment in patients with lymphoedema: a prospective study.

BACKGROUND: Complex decongestive physiotherapy (CDP) is used to treat patients with severe lymphoedema. The efficacy of CDP is usually quantified by calculating limb volume from repeated measurements of circumference at least 10 points before and after treatment of an affected limb. Measurement is time-consuming and operator-dependent. OBJECTIVES: To determine whether decreased dermal thickness is correlated with decreased volume after intensive CDP. METHODS: A consecutive series of patients admitted for intensive CDP were studied over a 6-month period. Before and after CDP, we measured circumference, dermal thickness elasticity and finally improvement in quality of life using a visual analogue scale (VAS). RESULTS: Thirty patients were included in the study. Only three patients were previously untreated. The average relative reduction in limb volume was 4% and the reduction in the dermal thickness was 15% (correlation: r = 0.37, P = 0.05). Viscoelasticity was decreased by 13%. VAS quality of life score was improved by 30%. CONCLUSION: Changes in dermal thickness are slightly correlated with volume changes before and after 5-day intensive CDP in a selected series of patients previously treated at home.

Decrease of uteroplacental blood flow after feticide during second-trimester pregnancy termination with complete placenta previa: quantitative analysis using contrast-enhanced ultrasound imaging.

Contrast enhanced ultrasound (CEUS) was used to quantify the dynamic changes in uteroplacental blood flow before and after the interruption of fetal villus circulation resulting from feticide during a second trimester pregnancy termination in a patient with complete placenta previa. Quantitative analysis was performed on time-intensity curves acquired 24 h before and 48 h and 120 h after feticide and demonstrated the persistence of utero-placental blood flow with a progressive and two-step reduction in intervillous space and uteroplacental blood flow. Our results suggest that placental blood flow reduction after interruption of fetal circulation is a progressive and delayed mechanism.

Ultrasound analysis of the upper esophageal sphincter during swallowing in the healthy subject.

OBJECTIVES: The purpose of this study was to develop a methodology and standard settings for ultrasound study of the upper esophageal sphincter (UES) during swallowing. MATERIAL AND METHODS: This was a prospective study of 25 healthy volunteers (15 women and 10 men) aged 20 to 56 years. Neck ultrasonography was performed as each volunteer swallowed 10 mL of water three times. The parameters studied were: diameter of the closed UES; diameter of the open UES; anterior and lateral displacement (measured in cm) of the UES as the water bolus flowed through it; duration of UES opening; and average duration of UES displacement (measured in ms). Student's t tests for paired and unpaired samples were applied for the statistical analysis. RESULTS: The mean diameter of the closed UES was 0.78 ± 0.13 cm, while the mean duration of opening was 415 ± 57.66 ms and the mean duration of displacement was 937 ± 120.98 ms. Maximum anterior and lateral displacement of the UES was 0.42 ± 0.12 cm and 0.35 ± 0.18 cm, respectively. There was a significant difference between men and women for lateral displacement of the UES (P=0.04). CONCLUSION: This study established standards for ultrasound study of the UES during swallowing, using a non-invasive readily accessible method that may be useful for assessing swallowing disorders involving the UES (Zenker's diverticulum, fibrosis, stricture).

New insights into uteroplacental perfusion: quantitative analysis using Doppler and contrast-enhanced ultrasound imaging.

OBJECTIVE: To monitor and quantify uteroplacental perfusion in rat pregnancies by Doppler ultrasound (DUS) and contrast-enhanced ultrasound (CEUS). METHODS: Fourteen rats were randomized in two groups (the CEUS group and the control group). On days 8, 11, 14, 17, 19 and 20 of gestation, we used DUS to measure the resistance index (RI), pulsatility index and blood velocity in the uterine, arcuate and umbilical arteries in both groups. On days 14, 17 and 20, one group was also examined by CEUS. Quantitative perfusion parameters were calculated in 4 compartments (mesometrial triangle, placenta, umbilical cord and fetus) and compared. RESULTS: The DUS measurement showed that the RI of the uterine and arcuate arteries decreased (p < 0.01) from day 14 to day 17, while velocity increased each of these arteries (p < 0.01 and p < 0.05, respectively). Quantification of uteroplacental perfusion by CEUS in bolus mode revealed that blood volume and local blood flow increased from day 14 to day 20 in the mesometrial triangle (p < 0.01) and the placenta (p < 0.05). In the CEUS destruction-replenishment mode, the perfusion parameters showed trends similar to those observed in bolus mode. No microbubbles were detected in the umbilical vein or fetal compartments. The weights of pups in the two groups did not differ significantly. CONCLUSIONS: CEUS estimates of placental perfusion complement the data provided by DUS.

[Value of contrast-enhanced ultrasound in the evaluation of indeterminate renal cysts on CT]. / Évaluation de l'apport de l'échographie de contraste dans l'analyse des kystes rénaux de nature indéterminée au scanner.

PURPOSE: To demonstrate the value of contrast-enhanced ultrasound (CEUS) in the management of Bosniak type 2F and 3 renal cysts on CT. PATIENTS AND METHODS: Retrospective study of 14 patients with 15 Bosniak type 2F and 3 renal cysts on contrast enhanced CT. All patients underwent CEUS of the kidneys after injection of SonoVue(®). Using predetermined criteria, the lesions were classified as benign, malignant or indeterminate. Patients either underwent surgery or follow-up CT at one to three years. RESULTS: From the 15 indeterminate cysts on CT, 12 were either benign (n=8) or malignant (n=4) on CEUS. From the eight cysts considered benign on CEUS, seven remained stable on follow-up CT after a minimum of one year interval and one was surgically resected and confirmed to be benign. All four cysts considered malignant on CEUS were surgically resected and three were confirmed to be malignant and one was confirmed to be benign. Three cysts were indeterminate: two lesions were surgically resected and one was benign while the other was malignant and one lesion was stable at one year follow-up CT. CONCLUSION: CEUS was able to characterize indeterminate lesions as benign or malignant in 80% of cases with 92% reliability. Twenty percent of cysts remained indeterminate on CEUS. CEUS is reliable as a complement to CT in the evaluation of Bosniak type 2F and 3 renal cysts.

Circumstellar material in type Ia supernovae via sodium absorption features.

Type Ia supernovae are key tools for measuring distances on a cosmic scale. They are generally thought to be the thermonuclear explosion of an accreting white dwarf in a close binary system. The nature of the mass donor is still uncertain. In the single-degenerate model it is a main-sequence star or an evolved star, whereas in the double-degenerate model it is another white dwarf. We show that the velocity structure of absorbing material along the line of sight to 35 type Ia supernovae tends to be blueshifted. These structures are likely signatures of gas outflows from the supernova progenitor systems. Thus, many type Ia supernovae in nearby spiral galaxies may originate in single-degenerate systems.

[French first results using magnetic resonance-guided focused ultrasound for myoma treatment]. / Résultats préliminaires de la destruction des fibromes utérins par ultrasons focalisés contrôlée par résonance magnétique.

OBJECTIVE: Many women with myomas desire uterine conservation. Magnetic resonance-guided focused ultrasound surgery (MRgFUS) is a new non-invasive therapy. We describe our early results regarding efficacy and safety of MRgFUS for the treatment of uterine leiomyomas. PATIENTS AND METHODS: Fifty-two French women, over 18 years of age, who were candidates for surgical myomectomy, hysterectomy or uterine artery embolization due to symptomatic myomas were treated by MRgFUS (ExAblate 2000(®), InSightec) and followed up for at least 6 months. Intramural or subserous myomas with a size between 4-12 cm and a T2 low intensity MRI image were selected in women with no abdominal scar and no bowel interposition. The modified symptom severity score (SSS) was examined before and after the treatment at 6 months. Second treatment rate during the first follow-up year was reported. RESULTS: No serious complications were recorded during the treatments or follow-up period. Seven women had initial failure mostly because of bowel interposition, six of them had uterine artery embolisation. The mean modified SSS value for patients before MRgFUS was 41/100 and the values diminished significantly to a mean value of 22/100. A total of 65% of women had a reduction of at least 10 points (n=22) (initial score of 41 [29; 62] and 22 [16; 46] at 6 month follow-up). Good correlation was observed between myomas destruction and the symptoms score. During the follow-up period, ten patients (19%) required invasive interventions (six hysterectomies, two embolisations and two myomectomies). The average reduction in myoma volume determined by MR imaging at 6 months after treatment was 14%. This volume reduction is poorly correlated with the myoma's treated volume of 36.4% (6-74%). CONCLUSION: MRgFUS can safely be used for symptomatic treatment and avoid the need for surgical intervention in most patients. Additional follow-up is needed to determine the long-term durability of this promising non-invasive approach and to obtain reimbursement.

Evaluation of cardiac abnormalities by Doppler echocardiography in a large nationwide multicentric cohort of patients with systemic sclerosis.

OBJECTIVES: There is increasing concern about heart and pulmonary vascular involvement in systemic sclerosis (SSc). One of the most severe complications of SSc is pulmonary arterial hypertension (PAH). There has been an increased awareness of left ventricular (LV) diastolic abnormalities in SSc patients. However, previous studies have generally been conducted in small populations. The aims of this study were to prospectively screen for PAH and to describe echocardiographic parameters in a large group of SSc patients. METHODS: This prospective study was conducted in 21 centres for SSc in France. Patients without severe pulmonary function abnormalities, severe cardiac disease and known PAH underwent Doppler echocardiography performed by a reference cardiologist. RESULTS: Of the 570 patients evaluated, PAH was suspected in 33 patients and was confirmed in 18 by right heart catheterisation. LV systolic dysfunction was rare (1.4%). LV hypertrophy was found in 22.6%, with LV diastolic dysfunction in 17.7%. These LV abnormalities were influenced by age, gender and blood pressure. We identified a small group of 21 patients with a restrictive mitral flow pattern in the absence of any other cardiopulmonary diseases, suggesting a specific cardiac involvement in SSc. CONCLUSIONS: Left and right heart diseases, including PAH, LV hypertrophy and diastolic dysfunction, are common in SSc. However, a small subset of patients without any cardiac or pulmonary diseases have a restrictive mitral flow pattern that could be due to primary cardiac involvement of SSc. The prognostic implications of the LV abnormalities will be evaluated in the 3-year follow-up of this cohort.

A very faint core-collapse supernova in M85.

An anomalous transient in the early Hubble-type (S0) galaxy Messier 85 (M85) in the Virgo cluster was discovered by Kulkarni et al. on 7 January 2006 that had very low luminosity (peak absolute R-band magnitude M(R) of about -12) that was constant over more than 80 days, red colour and narrow spectral lines, which seem inconsistent with those observed in any known class of transient events. Kulkarni et al. suggest an exotic stellar merger as the possible origin. An alternative explanation is that the transient in M85 was a type II-plateau supernova of extremely low luminosity, exploding in a lenticular galaxy with residual star-forming activity. This intriguing transient might be the faintest supernova that has ever been discovered.

Detection of circumstellar material in a normal type Ia supernova.

Type Ia supernovae are important cosmological distance indicators. Each of these bright supernovae supposedly results from the thermonuclear explosion of a white dwarf star that, after accreting material from a companion star, exceeds some mass limit, but the true nature of the progenitor star system remains controversial. Here we report the spectroscopic detection of circumstellar material in a normal type Ia supernova explosion. The expansion velocities, densities, and dimensions of the circumstellar envelope indicate that this material was ejected from the progenitor system. In particular, the relatively low expansion velocities suggest that the white dwarf was accreting material from a companion star that was in the red-giant phase at the time of the explosion.

A giant outburst two years before the core-collapse of a massive star.

The death of massive stars produces a variety of supernovae, which are linked to the structure of the exploding stars. The detection of several precursor stars of type II supernovae has been reported (see, for example, ref. 3), but we do not yet have direct information on the progenitors of the hydrogen-deficient type Ib and Ic supernovae. Here we report that the peculiar type Ib supernova SN 2006jc is spatially coincident with a bright optical transient that occurred in 2004. Spectroscopic and photometric monitoring of the supernova leads us to suggest that the progenitor was a carbon-oxygen Wolf-Rayet star embedded within a helium-rich circumstellar medium. There are different possible explanations for this pre-explosion transient. It appears similar to the giant outbursts of luminous blue variable stars (LBVs) of 60-100 solar masses, but the progenitor of SN 2006jc was helium- and hydrogen-deficient (unlike LBVs). An LBV-like outburst of a Wolf-Rayet star could be invoked, but this would be the first observational evidence of such a phenomenon. Alternatively, a massive binary system composed of an LBV that erupted in 2004, and a Wolf-Rayet star exploding as SN 2006jc, could explain the observations.

An optical supernova associated with the X-ray flash XRF 060218.

Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae that are more luminous than average and that eject material at very high velocities. Less-luminous supernovae were not hitherto known to be associated with GRBs, and therefore GRB-supernovae were thought to be rare events. Whether X-ray flashes--analogues of GRBs, but with lower luminosities and fewer gamma-rays--can also be associated with supernovae, and whether they are intrinsically 'weak' events or typical GRBs viewed off the axis of the burst, is unclear. Here we report the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. Supernova 2006aj is intrinsically less luminous than the GRB-supernovae, but more luminous than many supernovae not accompanied by a GRB. The ejecta velocities derived from our spectra are intermediate between these two groups, which is consistent with the weakness of both the GRB output and the supernova radio flux. Our data, combined with radio and X-ray observations, suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis. This extends the GRB-supernova connection to X-ray flashes and fainter supernovae, implying a common origin. Events such as XRF 060218 are probably more numerous than GRB-supernovae.

[In vivo assessment of corneal epithelial toxicity of timolol with benzalkonium chloride using very-high-frequency ultrasound imaging]. / Evaluation in vivo par échographie à très haute fréquence des modifications épithéliales cornéennes induites par un bêta-bloquant avec 0,01% de chlorure de benzalkonium.

PURPOSE: To assess in vivo the corneal epithelial damage caused by a topical toxic medication using a 60-MHz ultrasound device. MATERIAL: and methods: A solution of timolol with 0.01% benzalkonium chloride (BAC) was applied twice a day in the test eyes of ten rabbits, and a BAC-free solution of timolol in the control eyes, for 56 days. We used a 60-MHz ultrasound device to evaluate the epithelial damage in BAC-exposed eyes, compared to control eyes. The clinical and ultrasound examinations were performed every week, and the histological analysis at the end of the experiment. RESULTS: The clinical findings were conjunctival redness, corneal staining and instability of the tear film. In vivo VHF ultrasound revealed a thinning of the epithelium of test eyes (from 40.9+/-1,6 microm at D0 to 31.8+/-3.4 microm at D56; p=0.0006 for D0 vs D56), while the epithelium of control eyes remained unchanged. Ultrasound epithelial thickness was correlated with corneal staining (at D34 and D56; p=0.0025 and 0.0377, respectively) and histological epithelial pachymetry (p=0.0176 for control and 0.0505 for tested epithelium). Moreover, we report qualitative VHF ultrasound imaging of early epithelial damage. CONCLUSION: This new device could be very useful in ocular toxicity evaluation as a reproducible and reliable tool for multicentric clinical research.