Riccardo Navarra

Optical coherence tomography and 3-dimensional confocal structured imaging system–guided femtosecond laser capsulotomy versus manual continuous curvilinear capsulorhexis

Purpose To compare the features of capsulotomy obtained during femtosecond laser–assisted cataract surgery with those of continuous curvilinear capsulorhexis (CCC) obtained using a standard manual technique. Setting Ophthalmology Clinic, Department of Medicine and Science of Ageing, University G. D’Annunzio Chieti‐Pescara, Chieti, Italy. Design Prospective randomized clinical study. Methods Candidates for cataract extraction were randomized into 1 of 3 groups as follows: Lensx femtosecond laser–assisted cataract surgery capsulotomy (laser group 1), Lensar femtosecond laser–assisted cataract surgery capsulotomy (laser group 2), and manual CCC (manual group). Results Each group comprised 30 eyes (30 patients). The capsulotomies in laser group 1 and laser group 2 showed significantly better circularity than the manual CCCs at 7 days (P<.001). There was a significant correlation between the intended versus achieved capsulotomy size in the 2 laser groups. Both laser groups had better intraocular lens (IOL) centration than the manual group at all timepoints (P<.001). Between‐group differences in uncorrected and corrected distance visual acuities were not statistically significant. The residual spherical equivalent and mean absolute error were statistically significantly smaller in the 2 laser groups than in the manual group (P=.038) and increased significantly over time in all the groups (P<.001). Conclusions Femtosecond laser capsulotomies showed better circularity with more predictable size than manual CCCs. In addition, IOL centration was better immediately after surgery and over time with better refractive results in the 2 laser groups. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Advanced Morphological and Functional Magnetic Resonance Techniques in Glaucoma

Glaucoma is a multifactorial disease that is the leading cause of irreversible blindness. Recent data documented that glaucoma is not limited to the retinal ganglion cells but that it also extends to the posterior visual pathway. The diagnosis is based on the presence of signs of glaucomatous optic neuropathy and consistent functional visual field alterations. Unfortunately these functional alterations often become evident when a significant amount of the nerve fibers that compose the optic nerve has been irreversibly lost. Advanced morphological and functional magnetic resonance (MR) techniques (morphometry, diffusion tensor imaging, arterial spin labeling, and functional connectivity) may provide a means for observing modifications induced by this fiber loss, within the optic nerve and the visual cortex, in an earlier stage. The aim of this systematic review was to determine if the use of these advanced MR techniques could offer the possibility of diagnosing glaucoma at an earlier stage than that currently possible.

Prematurity and brain perfusion: Arterial spin labeling MRI

Purpose Abnormal brain perfusion is a critical mechanism in neonatal brain injury. The aim of the present study was to compare Cerebral Blood Flow (CBF) evaluated with ASL MRI in three groups of neonates: preterms without brain lesions on MRI (PN), preterms with periventricular white matter lesions (PNp) and term neonates with normal MRI (TN). The correlation between CBF and clinical outcome was explored. Materials and methods The institutional review board approved this prospective study and waived informed consent. The perfusion ASL data from 49 consecutive preterm neonates (PN) studied at term-equivalent age and 15 TN were evaluated. Statistically significant differences in gray matter CBF were evaluated by using a linear mixed-model analysis and Mann-Whitney U test. Logistic regression analysis was used to assess the relation between CBF and neuromotor outcome at 12 months. Results Comparison of means indicated that the CBF of the whole brain were significantly higher in PN compared to TN (P = 0.011). This difference remained significant when considering the frontal (P = 0.038), parietal (P = 0.002), temporal (P = 0.030), occipital (P = 0.041) and cerebellar (P = 0.010) gray matter. In the PN group, lower CBF in basal ganglia was associated with a worse neuromotor outcome (P = 0.012). Conclusions ASL MRI demonstrated differences in brain perfusion of the basal ganglia between PN and TN. In PN, a positive correlation between CBF and neuromotor outcome was demonstrated in this area.

Diagnostic accuracy of biparametric vs multiparametric MRI in clinically significant prostate cancer: Comparison between readers with different experience

BACKGROUND MRI plays a crucial role to identify men with a high likelihood of clinically significant prostate cancer who require immediate biopsy. The added value of DCE MRI in combination with T2-weighted imaging and DWI is controversial (risks related to gadolinium administration, duration of MR exam, financial burden, effects on diagnostic performance). A comparison of a biparametric and a standard multiparametric MR imaging protocol, taking into account the different experience of the readers, may help to choose the best MR approach regarding diagnostic performance. PURPOSE To determine the added value of dynamic contrasted-enhanced imaging (DCE) over T2-weighted imaging (T2-WI) and diffusion weighted imaging (DWI) for the detection of clinically significant prostate cancer, and to evaluate how it affects the diagnostic performance of three readers with different grade of experience in prostate imaging. MATERIALS AND METHODS Eighty-five patients underwent prostate MR examination at 1.5 T MR scanner performed because of elevated prostate-specific antigen level and/or suspicion of prostate cancer at digital rectal examination. Two MR images sets (Set 1 = biparametric, Set 2 = multiparametric) were retrospectively and independently scored by three radiologists with 7, 3 and 1 years of experience in prostate MR imaging respectively, according to PI-RADS v2. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated by dichotomizing reader scores. Receiver operating characteristic (ROC) analysis was performed and areas under the curve (AUCs) were calculated for each reader and image set. A comparison of ROC curves was performed to test the difference between the areas under the ROC curves among the three readers. RESULTS There was no significant difference regarding the detection of clinically significant tumor among the three readers between the two image sets. The AUC for the bi-parametric and multi-parametric MR imaging protocol was respectively 0.68-0.72 (Reader 1), 0.72-0.70 (Reader 2) and 0.60-0.54 (Reader 3). ROC curve comparison revealed no statistically significant differences for each protocol among the most experienced (Reader 1) and the other readers (Readers 2-3). CONCLUSION The diagnostic accuracy of a bi-parametric MR imaging protocol consisting of T2-weighted imaging and DWI is comparable with that of a standard multi-parametric imaging protocol for the detection of clinically significant prostate cancer. The experience of the reader does not significantly modify the diagnostic performance of both MR protocols.

Perinatal MRI diffusivity is related to early assessment of motor performance in preterm neonates

Preterm neonates represent a high-risk population for abnormal neuropsychological development. But presently, an accurate method for identifying those at risk is not available. This study evaluated the association between the microstructural organization measured with Diffusion Tensor Imaging (DTI) in term-corrected preterm neonates and subsequent motor performance. Fractional anisotropy (FA), axial diffusion (AD), mean diffusivity (MD) and radial diffusivity (RD) were determined in two regions of interest (ROIs) corresponding to the posterior limb of the internal capsule (PLIC) and cortico-spinal tract (CST). The Griffiths Mental Developmental Scales (GMDS) were longitudinally administered at 3, 6 and 15 months; and correlations between the metrics of diffusivity and the motor subscale of the GMDS were assessed using the Spearman correlation. A statistically significant negative correlation was observed between the AD of PLIC of the left hemisphere and the 3-month GMDS Locomotor Subscale. These results suggested that AD is a valid indicator of the stage of maturation of the motor pathway in preterm neonates, but not of later motor outcome.

Spinal cord microstructure integrating phase-sensitive inversion recovery and diffusional kurtosis imaging

PurposeThe aim of this prospective study was to determine the feasibility in terms of repeatability and reproducibility of diffusional kurtosis imaging (DKI) for microstructural assessment of the normal cervical spinal cord (cSC) using a phase-sensitive inversion recovery (PSIR) sequence as the anatomical reference for accurately defining white-matter (WM) and gray-matter (GM) regions of interests (ROIs).MethodsThirteen young healthy subjects were enrolled to undergo DKI and PSIR sequences in the cSC. The repeatability and reproducibility of kurtosis metrics and fractional anisotropy (FA) were calculated in GM, WM, and cerebral-spinal-fluid (CSF) ROIs drawn by two independent readers on PSIR images of three different levels (C1–C4). The presence of statistically significant differences in DKI metrics for levels, ROIs (GM, WM, and CSF) repeatability, reproducibility, and inter-reader agreement was evaluated.ResultsIntra-class correlation coefficients between the two readers ranged from good to excellent (0.75 to 0.90). The inferior level consistently had the highest concordance. The lower values of scan–rescan variability for all DKI parameters were found for the inferior level. Statistically significant differences in kurtosis values were not found in the lateral white-matter bundles of the spinal cord.ConclusionThe integration of DKI and PSIR sequences in a clinical MR acquisition to explore the regional microstructure of the cSC in healthy subjects is feasible, and the results obtainable are reproducible. Further investigation will be required to verify the possibility to translate this method to a clinical setting to study patients with SC involvement especially in the absence of MRI abnormalities on standard sequences.

Safety and effects on motor cortex excitability of five cathodal transcranial direct current stimulation sessions in 25 hours

OBJECTIVE To assess the safety and effects on motor cortex excitability of five cathodal-tDCS sessions (charge density 342.9C/m2) delivered over the dominant motor cortex with a return electrode over the ipsilateral shoulder at increasing time intervals in 25hours. METHODS Safety was operatively defined as absence of serious adverse events related to tDCS including brain tissue alterations documentable by magnetic resonance imaging and spectroscopy. Effects on motor cortex excitability were evaluated by motor evoked potential (MEP) amplitude. RESULTS Thirty-two healthy subjects were enrolled. No serious adverse events occurred. Magnetic resonance imaging and spectroscopy did not show alterations. Inter-individual MEP variability was assessed by the standard error of mean at baseline and subjects were classified on the basis of the ratio between normalized MEPs after the first stimulation compared to baseline. Fifty-six percent of subjects responded with reduction of MEP amplitude, 25% were non-responders and 19% were inverse responders. In responders, MEP suppression was 32% one hour after the end of first cathodal-tDCS, 21% three hours after the second, no longer present with increasing stimulation intervals and 38% two and half hours after the fifth stimulation. Intra-individual inter-sessional reliability in response was high (88-92%). CONCLUSIONS Five cathodal-tDCS sessions in 25hours are safe. Inter-individual variability in MEP suppression is considerable but response to one cathodal-tDCS highly predicts the response to other sessions. Duration of MEP suppression is limited to three hours. These findings should be considered in trials utilizing repeated cathodal-tDCS.