• fibromuscular dysplasia
• secondary Raynaud's phenomenon
• vascular ultrasound
• very high frequencies ultrasound

The aim of this thesis is to evaluate vascular applications of very high frequencies ultrasound (VHFUS) through the analysis of preliminary results obtained from two different scientific studies.
VHFUS allows visualization of the vessel wall ultrastructure of several arterial districts with a correlation between the different ultrasound interfaces and the layers that histologically compose the vessel wall.
Compared to what previously seen with conventional ultrasound, arterial wall showed an additional echogenic interface, possibly corresponding to the external elastic lamina (media-adventitia interface), allowing the measure of many wall parameters: most important being intima-media thickness (IMT), adventitia thickness (AT) and global thickness (IMAT).
These new diagnostic possibilities have been applied in two different clinical scenarios, analyzing the preliminary results of two different scientific studies:
• The first work evaluates patency, caliber and ultrastructure of the vessel wall of the interdigital arteries of hands in patients with secondary Raynaud's phenomenon, comparing the results with those obtained in healthy subjects population. Preliminary data shows significant differences in intimal thickness and "Media to lumen ratio" between the two study groups. Furthermore, considering only the cryoglobulinemic patients compared to the control group, significant differences were identified for the above-mentioned parameters as well as for the intima-media thickness and lumen diameter.
• The second work shows preliminary results obtained from the FUCHSIA study (Very high-Frequency Ultrasonography for arterial phenotyping in patients with Cervico-Cerebral Artery Dissection (CCeAD), Hypertension, Spontaneous Coronary Artery Dissection (SCAD) and FibroMuscular DysplasIA (FMD). This study is based on the identification of radial vascular wall abnormalities by very high frequency ultrasound in patients with fibromuscular dysplasia. This case-control study aim is to indentify radial vascular wall abnormalities analyzing this disease with VHFUS and automated image analysis. Furthermore, the disarray level of the vessels echogenic interfaces was assessed calculating the root mean square error (RMSE) between 20 profiles crossing the two interfaces and the profile obtained averaging them. For each echogenic interface, the RMSE was normalized for the maximum value of the corresponding mean profile (RMSE/mean). Results show a similar radial internal diameter in the two group, the maximum values of the mean profiles corresponding to the two interfaces tended to be lower in FMD patients. RMSE/mean was significantly higher in FMD than in C both for 1st and 2nd echogenic interface. IMT, AT and IMAT were significantly higher in FMD: the difference in IMT and IMAT remained significant even when considering age and mean BP as covariates. Wall/lumen ratio was similar and wall cross sectional area (WCSA) increased in FMD, calculated with either IMT or IMAT. In conclusion wall ultrastructure of radial arteries of hypertensive FMD patients was extensively altered: a peculiar “blurred” pattern, characterized of loss of echogenicity and inhomogeneity of the two echogenic layers, independent of age and mean BP. Increased wall thickness and WCSA were also found, indicating a eutrophic remodeling.