Near‐isotropic noncontrast MRA of the renal and peripheral arteries using a thin‐slab stack‐of‐stars quiescent interval slice‐selective acquisition

Abstract Background Computed tomography angiography (CTA) or contrast-enhanced (CE) cardiovascular magnetic resonance angiography (CMRA) is often obtained in patients with atrial fibrillation undergoing evaluation prior to pulmonary vein (PV) isolation. Drawbacks of CTA include radiation exposure and potential risks from iodinated contrast agent administration. Free-breathing 3D balanced steady-state free precession (bSSFP) Non-contrast CMRA is a potential imaging option, but vascular detail can be suboptimal due to ghost artifacts and blurring that tend to occur with a Cartesian k-space trajectory or, in some cases, inconsistent respiratory gating. We therefore explored the potential utility of both breath-holding and free-breathing non-contrast CMRA, using radial k-space trajectories that are known to be less sensitive to flow and motion artifacts than Cartesian. Main body Free-breathing 3D Cartesian and radial stack-of-stars acquisitions were compared in 6 healthy subjects. In addition, 27 patients underwent CTA and non-contrast CMRA for PV mapping. Three radial CMR acquisition strategies were tested: (1) breath-hold (BH) 2D radial bSSFP (BH-2D); (2) breath-hold, multiple thin-slab 3D stack-of-stars bSSFP (BH-SOS); and (3) navigator-gated free-breathing (FB) 3D stack-of-star bSSFP using a spatially non-selective RF excitation (FB-NS-SOS). A non-rigid registration algorithm was used to compensate for variations in breath-hold depth. In healthy subjects, image quality and vessel sharpness using a free-breathing 3D SOS acquisition was significantly better than free-breathing (FB) Cartesian 3D. In patients, diagnostic image quality was obtained using all three radial CMRA techniques, with BH-SOS and FB-NS-SOS outperforming BH-2D. There was overall good correlation for PV maximal diameter between BH-2D and CTA (ICC = 0.87/0.83 for the two readers), excellent correlation between BH-SOS and CTA (ICC = 0.90/0.91), and good to excellent correlation between FB-NS-SOS and CTA (ICC = 0.87/0.94). For PV area, there was overall good correlation between BH-2D and CTA (ICC = 0.79/0.83), good to excellent correlation between BH-SOS and CTA (ICC = 0.88/0.91) and excellent correlation between FB-NS-SOS and CTA (ICC = 0.90/0.95). CNR was significantly higher with BH-SOS (mean = 11.04) by comparison to BH-2D (mean = 6.02; P = 0.007) and FB-NS-SOS (mean = 5.29; P = 0.002). Conclusion Our results suggest that a free-breathing stack-of-stars bSSFP technique is advantageous in providing accurate depiction of PV anatomy and ostial measurements without significant degradation from off-resonance artifacts, and with better image quality than Cartesian 3D. For patients in whom respiratory gating is unsuccessful, a breath-hold thin-slab stack-of-stars technique with retrospective motion correction may be a useful alternative.

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Percutaneous mechanical thrombectomy in the treatment of acute and subacute occlusions of the peripheral arteries and bypasses

VASA ◽

10.1024/0301-1526/a000495 ◽

2016 ◽

Vol 45 (1) ◽

pp. 49-56 ◽

Cited By ~ 10

Author(s):

Frantisek Stanek ◽

Radoslava Ouhrabkova ◽

David Prochazka

Keyword(s):

Mechanical Thrombectomy ◽

Clinical Success ◽

Major Amputation ◽

Peripheral Arteries ◽

Duration Of Symptoms ◽

Efficient Treatment ◽

Percutaneous Mechanical Thrombectomy ◽

Single Centre Study ◽

Crural Arteries

Abstract. Background: The aim of this prospective single-centre study was to analyse the immediate results, failures and complications of percutaneous mechanical thrombectomy using the Rotarex catheter in the treatment of acute and subacute occlusions of peripheral arteries and bypasses, as well as to evaluate long-term outcomes of this method. Patients and methods: Patients with acute (duration of symptoms < 14 days) or subacute (duration of symptoms > 14 days and < 3 months) occlusions of peripheral arteries and bypasses were selected consecutively for treatment. The cohort consisted of 113 patients, aged 18 - 92 years (median 72 years). In all, 128 procedures were performed. Results: Angiographic success was obtained in 120 interventions (93.8 %). Reasons for failures were rethrombosis of a partially recanalised segment in six procedures, and embolism into crural arteries in one intervention - percutaneous aspiration thromboembolectomy (PAT) and/or thrombolysis were ineffective in all these cases. Breakage of the Rotarex catheter happened in one procedure. Embolisation into crural arteries as a transitory complication solvable with PAT and/or thrombolysis occurred in four cases. Rethrombosis was more frequent in bypasses than in native arteries (p = 0.0069), in patients with longer occlusions (p = 0.026) and those with poorer distal runoff (p = 0.048). Embolisation happened more often in patients with a shorter duration of symptoms (p = 0.0001). Clinical success was achieved in 82.5 %. Major amputation was performed in 10 % of cases. Cumulative patency rates were 75 % after one month, 71 % after six months, 38 % after 12 months, 33 % after 18 months and 30 % after 24, 30, 36 and 42 months. Conclusions: Rotarex thrombectomy has excellent immediate results with a low rate of failures and complications. In comparison to thrombolysis, it enables the fast and efficient treatment of acute and subacute occlusions of peripheral arteries in one session.

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Numerical analysis of local heat flux and thin-slab solidification in a CSP funnel-type mold with electromagnetic braking

Metallurgical Research & Technology ◽

10.1051/metal/2020044 ◽

2020 ◽

Vol 117 (6) ◽

pp. 602

Author(s):

Heping Liu ◽

Jianjun Zhang ◽

Hongbiao Tao ◽

Hui Zhang

Keyword(s):

Heat Flux ◽

Casting Speed ◽

Shell Growth ◽

Local Heat ◽

Operating Conditions ◽

Thin Slab ◽

Wide Face ◽

Slab Width ◽

Steel Grades ◽

Local Heat Flux

In this article, based on the actual monitored temperature data from mold copper plate with a dense thermocouple layout and the measured magnetic flux density values in a CSP thin-slab mold, the local heat flux and thin-slab solidification features in the funnel-type mold with electromagnetic braking are analyzed. The differences of local heat flux, fluid flow and solidified shell growth features between two steel grades of Q235B with carbon content of 0.19%C and DC01 of 0.03%C under varying operation conditions are discussed. The results show the maximum transverse local heat flux is near the meniscus region of over 0.3 m away from the center of the wide face, which corresponds to the upper flow circulation and the large turbulent kinetic energy in a CSP funnel-type mold. The increased slab width and low casting speed can reduce the fluctuation of the transverse local heat flux near the meniscus. There is a decreased transverse local heat flux in the center of the wide face after the solidified shell is pulled through the transition zone from the funnel-curve to the parallel-cure zone. In order to achieve similar metallurgical effects, the braking strength should increase with the increase of casting speed and slab width. Using the strong EMBr field in a lower casting speed might reverse the desired effects. There exist some differences of solidified shell thinning features for different steel grades in the range of the funnel opening region under the measured operating conditions, which may affect the optimization of the casting process in a CSP caster.

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Evaluation of Color Coded Ultrasound (CCU) for Quantitative Morphometry of Peripheral Arteries as Compared to Angiography: Results of the PeriQuant Registry Study

Ultraschall in der Medizin - European Journal of Ultrasound ◽

10.1055/s-0029-1239742 ◽

2009 ◽

Vol 30 (S 01) ◽

Author(s):

RR Macharzina ◽

N Fan ◽

W Charlotte ◽

U Schwarzwälder ◽

A Grabs ◽

...

Keyword(s):

Peripheral Arteries ◽

Registry Study ◽

Quantitative Morphometry ◽

Coded Ultrasound

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Association of Variables of Coagulation, Fibrinolysis and Acute-phase with Atherosclerosis in Coronary and Peripheral Arteries and those Arteries Supplying the Brain

Thrombosis and Haemostasis ◽

10.1055/s-0038-1653783 ◽

1995 ◽

Vol 73 (03) ◽

pp. 374-379 ◽

Cited By ~ 140

Author(s):

Jürgen Heinrich ◽

Helmut Schulte ◽

Rainer Schönfeld ◽

Ekkehart Köhler ◽

Gerd Assmann

Keyword(s):

Acute Phase ◽

Coronary Atherosclerosis ◽

Plasminogen Activator Inhibitor ◽

Arterial Disease ◽

Plasma Fibrinogen ◽

Base Line ◽

Peripheral Arteries ◽

Brain Vessels ◽

The Brain ◽

D Dimer

SummaryWe investigated the vessel status of coronary and peripheral arteries and those arteries supplying the brain in 929 consecutive male patients admitted to a coronary rehabilitation unit. The severity of coronary atherosclerosis was scored using coronary angiography. Changes in extracranial brain vessels and manifest cerebrovascular disease (CVD) were determined by B-mode ultrasound and Doppler examination. Peripheral arterial disease (PAD) was diagnosed using base-line and stress oscillography. We assessed variables of coagulation, fibrinolysis, and the acute phase response.There was a significant increase in plasma fibrinogen, plasminogen, d-dimer and C-reactive protein (CRP) with increasing severity of coronary heart disease. Compared to men with unaffected arteries, men with 3 diseased coronary arteries had 58% greater d-dimer concentrations. Patients with CVD and PAD, respectively, also had significantly higher fibrinogen, d-dimer and CRP concentrations. We did not find an association between plasminogen activator inhibitor activity and the severity of coronary atherosclerosis.In conclusion, plasma fibrinogen, d-dimer and CRP concentrations were significantly related to atherosclerosis in the coronary, peripheral and extracranial brain arteries.

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