303 research outputs found
Interventional MR imaging at 1.5 T: quantification of sound exposure
Sound pressure levels (SPLs) during interventional magnetic resonance (MR)
imaging may create an occupational hazard for the interventional
radiologist (ie, the potential risk of hearing impairment). Therefore,
A-weighted and linear continuous-equivalent SPLs were measured at the
entrance of a 1.5-T MR imager during cardiovascular and real-time pulse
sequences. The SPLs ranged from 81.5 to 99.3 dB (A-weighted scale), and
frequencies were from 1 to 3 kHz. SPLs for the interventional radiologist
exceeded a safe SPL of 80 dB (A-weighted scale) for all sequences;
therefore, hearing protection is recommended
Shrinkage of the distal renal artery 1 year after stent placement as evidenced with serial intravascular ultrasound
The objective of this study was to determine the quantitative
intravascular ultrasound (IVUS) and angiographic changes that occur during
1 year follow-up after renal artery stent placement, given that restenosis
continues to be a limitation of renal artery stent placement. 38
consecutive patients with symptomatic renal artery stenosis treated with
Palmaz stent placement were studied prospectively. IVUS and angiography
were performed at the time of stent placement and at 1 year follow-up. At
follow-up, angiographic restenosis was seen in 14% of patients. The lumen
area in the stent, seen with IVUS, was significantly decreased from
24+/-5.6 mm(2) to 17+/-5.6 mm(2) (p<0.001) solely due to plaque
accumulation. The distal main renal artery showed a significant decrease
in lumen area owing to a significant vessel area decrease from 39+/-14.0
mm(2) to 29+/-9.3 mm(2) (p<0.001) without plaque accumulation.
Angiographic analysis confirmed this reduction in luminal diameter and
showed that the distal renal artery diameter at follow-up was
significantly smaller than before stent placement (86+/-23.0% vs
104+/-23.9% of the contralateral renal artery diameter; p=0.003). Besides
plaque accumulation in the stent, unexplained shrinkage of the distal main
renal artery was evidenced with IVUS and angiography 1 year following
stent placement
A precious metal alloy for construction of MR imaging-compatible balloon-expandable vascular stents
The authors developed ABI alloy, which mechanically resembles stainless
steel 316. The main elements of ABI alloy are palladium and silver.
Magnetic resonance (MR) images and radiographs of ABI alloy and stainless
steel 316 stent models and of nitinol, tantalum, and Elgiloy stents were
compared. ABI alloy showed the least MR imaging artifacts and was more
radiopaque than stainless steel 316. ABI alloy has the potential to
replace stainless steel 316 for construction of balloon-expandable MR
imaging-compatible stents
Multi-detector row computed tomography angiography of peripheral arterial disease
With the introduction of multi-detector row computed tomography (MDCT), scan speed and image quality has improved considerably. Since the longitudinal coverage is no longer a limitation, multi-detector row computed tomography angiography (MDCTA) is increasingly used to depict the peripheral arterial runoff. Hence, it is important to know the advantages and limitations of this new non-invasive alternative for the reference test, digital subtraction angiography. Optimization of the acquisition parameters and the contrast delivery is important to achieve a reliable enhancement of the entire arterial runoff in patients with peripheral arterial disease (PAD) using fast CT scanners. The purpose of this review is to discuss the different scanning and injection protocols using 4-, 16-, and 64-detector row CT scanners, to propose effective methods to evaluate and to present large data sets, to discuss its clinical value and major limitations, and to review the literature on the validity, reliability, and cost-effectiveness of multi-detector row CT in the evaluation of PAD
Value of the duplex waveform at the common femoral artery for diagnosing obstructive aortoiliac disease
PurposeTo evaluate the accuracy, predictive value, and observer agreement of the duplex ultrasound waveform at the common femoral artery as a marker of significant aortoiliac disease in a large group of consecutive patients who underwent a diagnostic workup for peripheral arterial disease in a vascular unit.MethodsIn 191 consecutive patients (381 aortoiliac segments), we classified the duplex ultrasound waveform at the common femoral artery as triphasic, biphasic, sharp monophasic, or poor monophasic. The waveforms were then compared with the findings of magnetic resonance angiography of the aortoiliac segment and peripheral runoff vessels. We calculated the diagnostic accuracy of the duplex waveform for detecting >50% obstructive disease of the aortoiliac segment and determined the observer agreement for classifying the duplex waveforms done by two independent observers.ResultsMagnetic resonance angiography showed obstruction in 152 (39.9%) of 381 aortoiliac segments in 191 patients. The presence of a poor monophasic waveform, encountered in 91 (24.3%) of 375 segments, was a reliable sign of significant aortoiliac disease, with a positive predictive value of 92%. Other waveforms were nondiagnostic for aortoiliac obstructive disease. The sharp monophasic waveform reliably predicted occlusive disease of the superficial femoral artery that was seen in 17 of 23 instances. There was good observer agreement for classifying duplex waveforms (κw= 0.85; 95% confidence interval, 0.80 to 0.89).ConclusionThe poor monophasic duplex waveform at the common femoral artery is in itself an accurate marker of aortoiliac obstructive disease. Other waveforms are nondiagnostic for aortoiliac disease
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