PTR thickness measurement increases the sensitivity of detection of mild PO compared with conventional RNFL measurement. This new way of using OCT may be useful for clinicians to detect mild PO.

Intravoxel incoherent motion (IVIM) MRI is a method to extract microvascular blood flow information out of diffusion-weighted images acquired at multiple b-values. We hypothesized that IVIM can identify the muscles selectively involved in a specific task, by measuring changes in activity-induced local muscular perfusion after exercise. We tested this hypothesis using a widely used clinical maneuver, the lift-off test, which is known to assess specifically the subscapularis muscle functional integrity. Twelve shoulders from six healthy male volunteers were imaged at 3 T, at rest, as well as after a lift-off test hold against resistance for 30 s, 1 and 2 min respectively, in three independent sessions. IVIM parameters, consisting of perfusion fraction (f), diffusion coefficient (D), pseudo-diffusion coefficient D* and blood flow-related fD*, were estimated within outlined muscles of the rotator cuff and the deltoid bundles. The mean values at rest and after the lift-off tests were compared in each muscle using a one-way ANOVA. A statistically significant increase in fD* was measured in the subscapularis, after a lift-off test of any duration, as well as in D. A fD* increase was the most marked (30 s, +103%; 1 min, +130%; 2 min, +156%) and was gradual with the duration of the test (in 10(-3) mm(2) /s: rest, 1.41 ± 0.50; 30 s, 2.86 ± 1.17; 1 min, 3.23 ± 1.22; 2 min, 3.60 ± 1.21). A significant increase in fD* and D was also visible in the posterior bundle of the deltoid. No significant change was consistently visible in the other investigated muscles of the rotator cuff and the other bundles of the deltoid. In conclusion, IVIM fD* allows the demonstration of a task-related microvascular perfusion increase after a specific task and suggests a direct relationship between microvascular perfusion and the duration of the effort. It is a promising method to investigate non-invasively skeletal muscle physiology and clinical perfusion-related muscular disorders.

Statistically significant differences exist among commercially available OCT instruments in measuring mean CMT and mean average RNFL thickness in patients with optic neuritis and/or MS. These findings likely result from the differences in data acquisition and segmentation algorithm software among OCT instruments. Awareness of these variations among OCT instruments will be important in using these instruments for clinical trials and management of patients with optic neuritis and/or MS.

The evaluation of local muscle recruitment during a specific movement can be done indirectly by measuring changes in local blood flow. Intravoxel incoherent motion perfusion imaging exploits some properties of the magnetic resonance to measure locally microvascular perfusion, and seems ideally suited for this task. We studied the selectivity of the increase in intravoxel incoherent motion blood flow related parameter fD* in the muscles of 24 shoulders after two physical exam maneuvers, Jobe and Lift-off test (test order reversed in half of the volunteers) each held 2min against resistance. After a lift-off, IVIM blood flow-related fD* was increased in the subscapularis (in 10mms, 3.24±0.86 vs. rest 1.37±0.58, p<0.001) and the posterior bundle of deltoid (2.62±1.34 vs. rest 0.77±0.32, p<0.001). Those increases were selective when compared with other rotator cuff muscles and deltoid bundles respectively. After a Jobe test, increase in fD* was scattered within the rotator cuff muscles, but was selective for the lateral deltoid compared to the other deltoid bundles (anterior, p<0.001; posterior, p<0.05). Those results were similar when the testing order was reversed. In conclusion, this study demonstrated a selective increase in local microvascular perfusion after specific muscle testing of the shoulder muscles with IVIM. This technique has the potential to non-invasively characterize perfusion-related musculoskeletal physiological as well as pathological processes.

Background: The assessment of brain death can be challenging in critically ill patients, and cerebral perfusion quantification might give information on the brain tissue viability. Intravoxel incoherent motion perfusion imaging is a magnetic resonance imaging technique, which extracts perfusion information from a diffusion-weighted sequence, and provides local, microvascular perfusion assessment without contrast media injection. Methods: Diffusion weighted images were acquired with 16 b-values (0-900 s/mm 2 ) in the brain in two patients with cerebral death, confirmed by clinical assessment and evolution, as well as in two age-matched healthy subjects. The intravoxel incoherent motion perfusion fraction maps were obtained by fitting the bi-exponential signal equation model. 8 regions of interest were drawn blindly in the brain neocortex (in the frontal, temporal, parietal, and occipital lobes on both sides) and perfusion fractions were compared between patients with cerebral death and healthy control. Statistical significance was assessed using two-sided Wilcoxon signed rank test, and set to α < 0.05. Results: Intravoxel incoherent motion (IVIM) perfusion fraction was vanishing in the brain of the two patients with cerebral brain death compared to the healthy controls. Mean (± standard deviation) cortex perfusion fraction was 0.016 ± 0.005 respectively 0.005 ± 0.008 in the cerebral death patients, compared to respectively 0.052 ± 0.021 (p = 0.02) and 0.071 ± 0.042 (p = 0.008) in the age-matched controls. Conclusion: Intravoxel incoherent motion perfusion imaging is a promising tool to assess local brain tissue viability in critically ill patients.