Low-flow low-gradient aortic stenosis (LFLG AS) with reduced left ventricle ejection fraction (LVEF) is still a diagnostic and therapeutic challenge. The aim of this paper is to review the latest ...evidences about the assessment of the valvular disease, usually difficult because of the low-flow status, and the therapeutic options. Special emphasis is given to the available diagnostic tools for the characterization of LFLG AS without functional reserve at stress echocardiography and to the factors that clinicians should evaluate to choose between surgical aortic valve repair, transcatheter aortic valve implantation, or medical therapy.
A dual-loop architecture employs eight distributed microregulators (UREGs) to achieve load response times below 500 ps in 45-nm SOI CMOS. The trip point of an asynchronous comparator inside each UREG ...is tuned for high DC accuracy with a local charge pump, which receives UP/DOWN currents from a slow outer feedback loop. The feedback through the charge pumps also ensures balanced load sharing among the UREGs. Two techniques are introduced to reduce the output ripple generated by switching the pMOS passgate on and off: hybrid fast/slow passgate control (in which the DC portion of the load current is supplied by a parallel output device with slew-rate-limited gate drive) and pMOS strength calibration (which adjusts the active width of the passgate to compensate for PVT variations). The distributed regulator system is integrated into a DDR3 I/O core and supplies power to CMOS delay lines used for clock-to-data deskewing. Each of the eight UREGs is sized to provide up to 5.3 mA of load current and occupies an area of 55 × 60 μm 2 . The measured DC load regulation is better than 10 mV down to an 85-mV dropout voltage. Jitter readings of the CMOS delay lines indicate output noise close to 28 mVpp.
Sr isotope records from marginal marine basins track the mixing between seawater and local continental runoff, potentially recording the effects of sea level, tectonic, and climate forcing in marine ...fossils and sediments. Our 110 new 87Sr/86Sr analyses on oyster and foraminifera samples from six late Miocene stratigraphic sections in southern Turkey, Crete, and Sicily show that 87Sr/86Sr fell below global seawater values in the basins several million years before the Messinian Salinity Crisis, coinciding with tectonic uplift and basin shallowing. 87Sr/86Sr from more centrally located basins (away from the Mediterranean coast) drop below global seawater values only during the Messinian Salinity Crisis. In addition to this general trend, 55 new 87Sr/86Sr analyses from the astronomically tuned Lower Evaporites in the central Apennines (Italy) allow us to explore the effect of glacio‐eustatic sea level and precipitation changes on 87Sr/86Sr. Most variation in our data can be explained by changes in sea level, with greatest negative excursions from global seawater values occurring during relative sea level lowstands, which generally coincided with arid conditions in the Mediterranean realm. We suggest that this greater sensitivity to lowered sea level compared with higher runoff could relate to the inverse relationship between Sr concentration and river discharge. Variations in the residence time of groundwater within the karst terrain of the circum‐Mediterranean region during arid and wet phases may help to explain the single (robust) occurrence of a negative excursion during a sea level highstand, but this explanation remains speculative without more detailed paleoclimatic data for the region.
Key Points
Negative Sr isotope excursions in Miocene Mediterranean marine sediments
Sr isotope excursions primarily correspond to sea level fall or basin uplift
Groundwater effects on river and basin water geochemistry are likely important
Our aim was to compare contrast-enhanced MR angiography (CE-MRA) and 3D time-of-flight (TOF) MRA at 3T for follow-up of coiled cerebral aneurysms.
Fifty-two patients treated with Guglielmi detachable ...coils for 54 cerebral aneurysms were evaluated at 3T MRA. 3D TOF MRA (TR/TE = 23/3.5; SENSE factor = 2.5) and CE-MRA by using a 3D ultrafast gradient-echo sequence (TR/TE = 5.9/1.8; SENSE factor = 3) enhanced with 0.1-mmol/kg gadobenate dimeglumine were performed in the same session. Source images, 3D maximum intensity projection, 3D shaded surface display, and/or 3D volume-rendered reconstructions were evaluated in terms of aneurysm occlusion/patency and artifact presence.
In terms of clinical classification, the 2 MRA sequences were equivalent for 53 of the 54 treated aneurysms: 21 were considered fully occluded, whereas 16 were considered to have a residual neck and 16 were considered residually patent at follow-up MRA. The remaining aneurysm appeared fully occluded at TOF MRA but had a residual patent neck at CE-MRA. Visualization of residual aneurysm patency was significantly (P = .001) better with CE-MRA compared with TOF MRA for 10 (31.3%) of the 32 treated aneurysms considered residually patent with both sequences. Coil artifacts were present in 5 cases at TOF MRA but in none at CE-MRA. No relationship was apparent between the visualization of patency and either the size of the aneurysm or the interval between embolization and follow-up.
At follow-up MRA at 3T, unenhanced TOF and CE-MRA sequences are similarly effective at classifying coiled aneurysms as occluded or residually patent. However, CE-MRA is superior to TOF MRA for visualization of residual patency and is associated with fewer artifacts.
We report a case of a patient with right type I proatlantal intersegmental artery associated with right fetal posterior cerebral artery and absence of both vertebral arteries and of the left ...posterior communicating artery. We also describe the clinical relevance of these findings for this patient. A 56-year-old woman with vertigo and tinnitus underwent contrast enhanced Magnetic Resonance Angiography (MRA) of the supra-aortic arteries using a 1.5 Tesla scanner. Maximum intensity projection and volume rendering reconstructions were obtained. MRA demonstrated the persistence of an anastomotic artery between the right internal carotid artery and basilar artery, passing through the foramen magnum, suggesting a type I proatlantal intersegmental artery. The examination also showed the absence of both vertebral arteries and the presence of a right fetal-type posterior cerebral artery. To our knowledge, this is the first report of a type I proatlantal intersegmental artery associated with an omolateral fetal-type posterior cerebral artery and the absence of both vertebral arteries and of the left posterior communicating artery. This condition requires a watchful monitoring of the patient and has to be considered in case of surgical procedures of the carotid arteries.
A preclinical insert for small animal simultaneous SPECT and MR imaging, in particular for imaging mouse brains, is presented. It consists of ten static magnetic resonance imaging (MRI)-compatible ...gamma cameras based on tiles of silicon photomultipliers readout by a multichannel ASIC and coupled to 5 cm × 5 cm CsI(Tl) scintillators and to an MRI-compatible multipinhole collimator. Calibration and image reconstruction algorithm are illustrated. Mutual compatibility is demonstrated along with imaging performance that is comparable with other non-MR micro-SPECT systems: 0.9 mm tomographic spatial resolution across a transverse field of view of 15.6 mm, 12% energy resolution (at 140 keV), and 1105 cps/MBq sensitivity. Experimental results with phantoms (glass capillaries of 290 μm diameter and a mini Derenzo) are presented.
Diffusion tensor imaging (DTI) tractography enables the in vivo visualization of the course of white matter tracts inside or around a tumor, and it provides the surgeon with important information in ...resection planning. This study is aimed at assessing the ability of preoperative DTI tractography in predicting the extent of the resection achievable in surgical removal of gliomas. Patients with low-grade gliomas (LGGs; 46) and high-grade gliomas (HGGs; 27) were studied using a 3T scanner according to a protocol including a morphological study (T2, fluid-attenuated inversion-recovery, T1 sequences) and DTI acquisitions (b = 1000 s/mm(2), 32 gradient directions). Preoperative tractography was performed off-line on the basis of a streamline algorithm, by reconstructing the inferior fronto-occipital (IFO), the superior longitudinal fascicle (SLF), and the corticospinal tract (CST). For each patient, the relationship between each bundle reconstructed and the lesion was analyzed. Initial and residual tumor volumes were measured on preoperative and postoperative 3D fluid-attenuated inversion-recovery images for LGGs and postcontrast T1-weighted scans for HGGs. The presence of intact fascicles was predictive of a better surgical outcome, because these cases showed a higher probability of total resection than did subtotal and partial resection. The presence of infiltrated or displaced CST or infiltrated IFO was predictive of a lower probability of total resection, especially for tumors with preoperative volume <100 cm(3). DTI tractography can thus be considered to be a promising tool for estimating preoperatively the degree of radicality to be reached by surgical resection. This information will aid clinicians in identifying patients who will mostly benefit from surgery.
Mediterranean marginal basins recorded the Messinian salinity crisis (MSC) in various structural settings, including syn-rift, thrust-top, foredeep, and foreland basins. During the MSC, the Apennines ...were one of the mobile belts of the peri-Mediterranean chain. Starting from more hinterland areas, allochthonous units of both the northern and southern Apennines migrated toward the Adriatic foreland, developing allochthonous-top sedimentary basins. One of these basins, on top of the Molise allochthonous units (southern Apennines), recorded almost all of the main steps of the MSC. In a gypsum quarry district, the occurrence of conduits yielding flow-mobilized sediments, which cross-cut the Lower Evaporites, testifies to a fluid-migration event responsible for the formation of a brecciated mudgrade limestone buildup. This event can be connected with the Mediterranean drawdown responsible for the Messinian erosional surface (MES). The post-evaporitic marly succession that unconformably overlies the Lower Evaporites and the “Brecciated limestones” is characterized by the presence of Paratethyan molluscs and ostracods (Loxoconcha muelleri and Loxocorniculina djafarovi zones), and small mammals, among which is recorded the occurrence of Stephanomys debruijni. A disconformity within the post-evaporitic succession divides it into lower (p-ev1) and upper (p-ev2) Lago-Mare deposits. A further erosional surface separates the Messinian Lago-Mare sediments from fully marine lower Zanclean (MPl2 Zone) deposits. Whilst the unconformity separating the Lower Evaporites and the Lago-Mare deposits (although enhanced by a tectonic event) could be related to a late Messinian base level drop (MES1), as well as the disconformity between p-ev1 and p-ev2 (MES2), the younger angular unconformities affecting both the Lago-Mare deposits (p-ev2) and the fully marine Pliocene sediments might be related to two different phases of orogenic transport. Those events affected the Molise allochthonous units during their Late Miocene-Early Pliocene forelandward migration.
•The Stingeti gypsum quarry is a good example of how the MSC impacted mobile belt.•Flow-mobilized sediments and limestone buildup indicate a great escape of fluids.•The post-evaporitic succession is dominated by brackish Paratethyan taxa.•Small mammals of the MN13 Zone are within the Loxocorniculina djafarovi Zone.•Sedimentation occurred on top of a mobile belt affected by three tectonic phases.
In order to avoid distal embolisation from mural thrombus within the ectatic segment, we opted to use a distal protection device (Filter Wire EX, Boston Scientific). ...distal protection systems have ...been mainly used in the setting of acute coronary syndromes, and to treat thrombotic or degenerated saphenous vein graft stenosis.
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