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  • patients
  • 2 Because this is a new technique, and restenosis is a problem as yet unquantified in sufficient numbers of patients, all patients routinely undergo follow-up angiography with, I am sure, an undoubted morbidity. (ahajournals.org)
  • In 37 patients, successful MR coronary angiography could be performed. (ahajournals.org)
  • In 3 patients (all with an anomalous left main coronary artery originating from the right aortic sinus), there was disagreement about the proximal course between the results of MR and x-ray coronary angiography. (ahajournals.org)
  • Patients must have suspected atherosclerotic disease based on clinical findings or documented by angiography or doppler ultrasound performed within 3 months of the MRA. (clinicaltrials.gov)
  • In a randomized parallel feasibility study in 22 adult patients with PHT and a clinical indication for NSBB, we acquired haemodynamic data at baseline and after 4 weeks of NSBB (propranolol or carvedilol) using phase-contrast MR angiography (PC-MRA) in selected intra-abdominal vessels. (hindawi.com)
  • Recently, magnetic resonance imaging (MRI) based techniques have shown promise for investigating differential visceral blood flow in the hyperdynamic circulation of patients with cirrhosis [ 9 ] and in quantifying PHT. (hindawi.com)
  • Patients with some metal implants, cochlear implants, and cardiac pacemakers are prevented from having an MRI scan due to effects of the strong magnetic field and powerful radio frequency pulses unless the device they carry is labeled MR-Conditional. (wikipedia.org)
  • Like angiography, CTA exposes patients to high dosages of radiation. (wikipedia.org)
  • Even small changes may be measured, making MRA a useful tool for monitoring disease progression without exposing patients to the radiation of direct angiography or CTA. (wikipedia.org)
  • Prospective evaluation of high-resolution MRI using gadofosveset for stent-graft planning: comparison with CT angiography in 30 patients, AJR Am J Roentgenol, 2011;197:1251-7 Partovi S, Aschwanden M, Staub D, et al. (wikipedia.org)
  • scan
  • In this test, radio waves, a magnetic field, and a computer create a scan of your body parts to look for health problems. (ahealthyme.com)
  • If you've never experienced a magnetic resonance imaging (MRI) scan before, you might be anxious about what to expect. (osu.edu)
  • Background and Purpose - High-resolution turbo MR angiography with zero-filling interpolation (ZFI) technique is a new vascular imaging method with reduced scan time. (ahajournals.org)
  • Recently, turbo MR angiography with zero-filling interpolation (ZFI) technique has been proposed as a new technique to reduce scan time for the evaluation of cerebrovascular diseases. (ahajournals.org)
  • 7-10 Thus, the ZFI technique allows for high-resolution turbo MR angiography in less scan time. (ahajournals.org)
  • This can be described by: S N R v = π 2 v v e n c S N R {\displaystyle SNR_{v}={\frac {\pi }{\sqrt {2}}}{\frac {v}{v_{enc}}}SNR} where S N R {\displaystyle SNR} is the signal-to-noise ratio of the image (which depends on the magnetic field of the scanner, the voxel volume, and the acquisition time of the scan). (wikipedia.org)
  • This is based on MRI scan, magnetic resonance angiography and CT scan. (wikipedia.org)
  • radiation
  • Harms of overuse of CT angiography include radiation exposure and the possibility of finding then seeking treatment for a clinically insignificant pulmonary embolism which ought not be treated. (wikipedia.org)
  • gradients
  • To measure Δ Φ {\displaystyle \Delta \Phi } , of the MRI signal is manipulated by bipolar gradients (varying magnetic fields) that are preset to a maximum expected flow velocity. (wikipedia.org)
  • By applying additional magnetic fields (gradients) that vary linearly over space, specific slices to be imaged can be selected, and an image is obtained by taking the 2-D Fourier transform of the spatial frequencies of the signal (a.k.a., k-space). (wikipedia.org)
  • MRI scanners use strong magnetic fields, electric field gradients, and radio waves to generate images of the organs in the body. (wikipedia.org)
  • Pulses of radio waves excite the nuclear spin energy transition, and magnetic field gradients localize the signal in space. (wikipedia.org)
  • In magnetic resonance imaging (MRI), a sequence is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance. (wikipedia.org)
  • evaluate
  • CT angiography should not be used to evaluate for pulmonary embolism when other tests indicate that there is a low probability of a person having this condition. (wikipedia.org)
  • time-resolved
  • Bley TA, Duffek CC, Francois CJ, Schiebler ML, Acher CW, Mell M, Grist TM, Reeder SB (2010) Presurgical localization of the artery of Adamkiewicz with time-resolved 3.0-T MR angiography. (springer.com)
  • commonly
  • In the static magnetic fields commonly used in MRI, the energy difference between the nuclear spin states corresponds to a radio-frequency photon. (wikipedia.org)
  • main
  • The radio signal may be made to encode position information by varying the main magnetic field using gradient coils. (wikipedia.org)
  • The major components of an MRI scanner are: the main magnet, which polarizes the sample, the shim coils for correcting shifts in the homogeneity of the main magnetic field, the gradient system which is used to localize the MR signal and the RF system, which excites the sample and detects the resulting NMR signal. (wikipedia.org)
  • voltage
  • These changes in magnetization alignment cause a changing magnetic flux, which yields a changing voltage in receiver coils to give the signal. (wikipedia.org)