Application of multi-planar reconstruction technique in endovascular repair of aortic dissection

BACKGROUND Endovascular repair of aortic dissection is an effective method commonly used in the treatment of Stanford type B aortic dissection.Stent placement during the operation was one-time and could not be repeatedly adjusted during the operation.Therefore,it is of great significance for cardiovascular physicians to fully understand the branch status,position,angle,and other information regarding aortic arch dissection before surgery.AIM To provide more references for clinical cardiovascular physicians to develop treatment plans.METHODS Data from 153 patients who underwent endovascular repair of aortic dissection at our hospital between January 2021 and December 2022 were retrospectively collected.All patients underwent multi-slice spiral computed tomography angiography.Based on distinct post-image processing techniques,the patients were categorized into three groups:Multiplanar reconstruction(MPR)(n=55),volume reconstruction(VR)(n=46),and maximum intensity projection(MIP)(n=52).The detection rate of aortic rupture,accuracy of the DeBakey classification,rotation,and tilt angles of the C-arm during the procedure,dispersion after stent release,and the incidence of late complications were recorded and compared.RESULTS The detection rates of interlayer rupture in the MPR and VR groups were significantly higher than that in the MIP group(P<0.05).The detection rates of De-Bakey subtypesⅠ,Ⅱ,andⅢin the MPR group were higher than those in the MIP group,and the detection rate of typeⅢin the MPR group was significantly higher than that in the VR group(P<0.05).There was no statistically significant difference in the detection rates of typesⅠandⅡcompared to the VR group(P>0.05).The scatter rate of markers and the incidence of complications in the MPR group were significantly lower than those in the VR and MIP groups(P<0.05).CONCLUSION The application of MPR in the endovascular repair of aortic dissection has improved the detection rate of dissection rupture,the accuracy of anatomical classification,and safety.

Properties of the Main Phases of the Super Geomagnetic Storms(ΔSYM-H≤-250 nT)with Different Heliolongitudes

We studied the properties of the main phases of 24 super geomagnetic storms(SGSs)(ΔSYM-H≤-250 nT)since 1981.We divided the SGSs into two subgroups:SGSs-Ⅰ(-400 nT<ΔSYM-H≤-250 nT)and SGSs-Ⅱ(ΔSYM-H≤-400 nT).Of the 24 SGSs,16 are SGSs-Ⅰand eight are SGSs-Ⅱ.The source locations of SGSs were distributed in the longitudinal scope of[E37,W66].95.8%of the SGSs were distributed in the longitudinal scope of[E37,W20].East and west hemispheres of the Sun had 14 and 10 SGSs,respectively.The durations of the main phases for six SGSs ranged from 2 to 4 hr.The durations of the main phases for the rest 18 SGSs were longer than 6.5 hr.The duration of the SGSs with source locations in the west hemisphere varied from 2.22 to 19.58 hr.The duration for the SGSs with the source locations in the east hemisphere ranged from 2.1 to31.88 hr.The averaged duration of the main phases of the SGSs in the west and east hemispheres are 8.3 hr and13.98 hr,respectively.|ΔSYM-H/Δt|for six SGSs with source locations distributed in the longitudinal area ranging from E15 to W20 was larger than 1.0 nT·minute^(-1),while|ΔSYM-H/Δt|for the rest 18 SGSs was lower than 1.0 nT·minute^(-1).|ΔSYM-H/Δt|for SGSs-Ⅰvaried from 0.18 to 3.0 nT·minute^(-1).|ΔSYM-H/Δt|for eight SGSs-Ⅱvaried from 0.37 to 2.2 nT·minute^(-1)with seven SGSs-Ⅱfalling in the scope from 0.37 to0.992 nT·minute^(-1).

A study on the dynamic spectral indices for SEP events on 2000 July 14 and 2005 January 20

We have studied the dynamic proton spectra for the two solar energetic particle(SEP)events on2000 July 14(hereafter GLE59)and 2005 January 20(hereafter GLE69).The source locations of GLE59 and GLE69 are N22 W07 and N12 W58 respectively.Proton fluxes>30 Me V have been used to compute the dynamic spectral indices of the two SEP events.Our results show that spectral indices of the two SEP events increased more swiftly at early times,suggesting that the proton fluxes>30 Me V might be accelerated particularly by the concurrent flares at early times for the two SEP events.For the GLE69 with source location at N12 W58,both flare site and shock nose are well connected with the Earth at the earliest time.However,only the particles accelerated by the shock driven by eastern flank of the CME can propagate along the interplanetary magnetic field line to the Earth after the flare.For the GLE59 with source location at N22 W07,only the particles accelerated by the shock driven by western flank of the associated CME can reach the Earth after the flare.Our results also show that there was slightly more than one hour during which the proton spectra for GLE69 are softer than that for GLE59 after the flares,suggesting that the shock driven by eastern flank of the CME associated with GLE69 is weaker than the shock driven by the western flank of the CME associated with GLE59.The results support that quasi-perpendicular shock has stronger potential in accelerating particles than the quasi-parallel shock.These results also suggest that only a small part of the shock driven by western flank of the CME associated with the GLE59 is quasi-perpendicular.

Sun-Earth connection event of super geomagnetic storm on 2001 March 31:the importance of solar wind density

An X1.7 flare at 10:15 UT and a halo CME with a projected speed of 942 km s-1 erupted from NOAA solar active region 9393 located at N20 W19,which were observed on 2001 March 29.When the CME reached the Earth,it triggered a super geomagnetic storm(hereafter super storm).We find that the CME always moved towards the Earth according to the intensity-time profiles of protons with different energies.The solar wind parameters responsible for the main phase of the super storm occurred on 2001 March 31 are analyzed while taking into account the delayed geomagnetic effect of solar wind at the L1 point and using the SYM-H index.According to the variation properties of SYM-H index during the main phase of the super storm,the main phase of the super storm is divided into two parts.A comparative study of solar wind parameters responsible for two parts shows the evidence that the solar wind density plays a significant role in transferring solar wind energy into the magnetosphere,besides the southward magnetic field and solar wind speed.

Investigation of the possible source for the solar energetic particle event on 2017 September 10

According to the solar proton data observed by Geostationary Operational Environmental Satellites （GOES）, ground-based neutron monitors on Earth and near-relativistic electron data measured by the ACE spacecraft, the onset times of protons with different energies and near-relativistic electrons have been estimated and compared with the time of solar soft and hard X-ray and radio burst data. The results show that first arriving relativistic and non-relativistic protons and electrons may have been accelerated by the concurrent flare. The results also suggest that release times of protons with different energies may be different, and the protons with lower energy may have been released earlier than those with higher energy. Some protons accelerated by concurrent flares may be further accelerated by the shock driven by the associated CME.

Extreme space weather events caused by super active regions during solar cycles 21-24

Extreme space weather events including≥X5.0 flares,ground level enhancement(GLE)events and super geomagnetic storms(Dst≥-250 nT)caused by super active regions(SARs)during solar cycles 21-24 were studied.The total number ofX5.0 solar flares was 62,among which 41 were X5.0-X9.9 flares and 21 were≥X10.0 flares.We found that 83.9%of the≥X5.0 flares were produced by SARs;78.05%of the X5.0-X9.9 and 95.24%of the≥X10.0 solar flares were produced by SARs;46 GLEs were registered during solar cycles 21-24,and 25 GLEs were caused by SARs,indicating that 54.3%of the GLEs were caused by SARs;24 super geomagnetic storms were recorded during solar cycles 21-24,and 12 of them were caused by SARs,namely 50%of the super geomagnetic storms were caused by SARs.We ascertained that only 29 SARs produced≥X5.0 flares,15 SARs generated GLEs and 10 SARs triggered super geomagnetic storms.Of the 51 SARs,only 33 SARs produced at least one extreme space weather event,while none of the other 18 SARs could trigger an extreme space weather event.There were only four SARs and each of them generated not only a≥X5.0 flare,but also a GLE event and a super geomagnetic storm.Most of the extreme space weather events caused by the SARs appeared during solar cycles 22 and 23,especially for GLE events and super geomagnetic storms.The longitudinal distributions of source locations for the extreme space weather events caused by SARs were also studied.

What Can We Learn from the Geoeffectiveness of the Magnetic Cloud on 2012 July 15–17?

An interplanetary shock and a magnetic cloud(MC) reached the Earth on 2012 July 14 and 15 one after another.The shock sheath and the MC triggered an intense geomagnetic storm.We find that only small part of the MC from06:45 UT to 10:05 UT on 2012 July 15 made contribution to the intense geomagnetic storm,while the rest part of the MC made no contribution to the intense geomagnetic storm.The averaged southward component of interplanetary magnetic field(Bs) and duskward-electric fields(Ey) within the MC from 10:05 UT,2012 July 15 to09:08 UT,2012 July 16(hereafter MC2),are 15.11 nT and 8.01 my m-1,respectively.According to the empirical formula established by Burton et al.(hereafter Burton equation),the geoeffectiveness of MC2 should be-655.42 nT,while the geoeffectiveness of MC2 is-324.68 nT according to the empirical formula established by O’Brien & McPherron(hereafter OM equation).However,the real geoeffectiveness of MC2 is 39.74 nT.The results indicate that the Burton equation and the OM equation cannot work effectively.The geoeffectiveness of MC2 shows that large and long duration of Bs or Ey cannot guarantee the occurrence of an intense geomagnetic storm if the solar wind dynamic pressure is very low.If we use 0.52 as γ,the geoeffectiveness of MC2 is 40.36 nT according to the empirical formula established by Wang et al.,which is very close to the observed value,indicating that the empirical formula established by Wang et al.is much better than the Burton equation and the OM equation.