Effects of Turbulence on Signal Intensity in Gradient Echo Images

Evans, Avery J.; Blinder, Russell A.; Herfkens, Robert J.; Spritzer, Charles E.; Kuethe, Dean O.; Fram, Evan K.; Hedlund, Laurence W.

doi:10.1097/00004424-198807000-00006

Cited by 99 publications

(32 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Occlusions were perfectly detected on MRA. An absence of signal intensity within the vessel at the level of stenosis and distally for a variable distance probably caused by loss of laminar flow in the poststenotic portion of the vessel with resultant intravoxel dephasing [12] and by increased residence times in the excited section [2] characteristically reflected the presence of severe stenosis. Eleven of 12 severe stenotic vessels were identified as the signal discontinuity of blood flow column on MRA.…”

Section: Discussionmentioning

confidence: 99%

Detection of Occlusive Lesions in Intracranial Arteries by Three-Dimensional Time-of-Flight Magnetic Resonance Angiography

et al. 1994

View full text Add to dashboard Cite

To evaluate the accuracy of 3-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA) for detecting intracranial arterial occlusive disease, this technique was compared with conventional angiography. The subjects were 54 patients with cerebrovascular ischemic disease. Using a semi-quantified grading scheme, stenotic lesions were assessed for each segment of the intracranial arteries to the level of the second segment. A high correlation in the degree of stenosis (Spearman rank correlation = 0.68, p = 0.0001, ĸstatistic = 0.846) and an extremely high sensitivity (100%) for detecting occlusive lesions were found. Specificity for each segment of the intracranial arteries varied from 94.8% (Ml portion of the middle cerebral artery) to 83.3% (Al portion of the anterior cerebral artery). However, mild stenosis tended to be slightly overestimated, and false-positive readings in specific parts of the vessels (the carotid siphon, the anterior cerebral artery orifice, and the middle cerebral artery bifurcation) were not insubstantial. We conclude that despite a relatively high false-positive rate in some regions, 3D TOF MRA is useful for evaluating intracranial major vessels in stroke patients.

show abstract

Section: Discussionmentioning

confidence: 99%

Detection of Occlusive Lesions in Intracranial Arteries by Three-Dimensional Time-of-Flight Magnetic Resonance Angiography

et al. 1994

View full text Add to dashboard Cite

show abstract

“…Phase-contrast measurements are optimized for laminar flow, whereas in turbulent flow patterns the precision of the CMR flow measurements declines [19,20]. In case of helical flow, motion in the non-velocity encoding directions may also lead to phase-shifts which are not related to through-plane flow.…”

Section: Discussionmentioning

confidence: 99%

Non-Invasive Stroke Volume Assessment in Patients with Pulmonary Arterial Hypertension: Left-Sided Data Mandatory.

Mauritz

Marcus

Boonstra

et al. 2009

B53. Acute Pulmonary Embolism: Diagnosis, Prevention, and Treatment

View full text Add to dashboard Cite

show abstract

“…The AR jet was associated with a signal void in the LV in diastole. Though the mechanism of signal loss is not completely elucidated, the work of Evans et al [13] indicates that this signal loss may be due to turbulence-induced phase cancellation.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Aortic Regurgitation by Cardiac Cine Magnetic Resonance Imaging: Planar Analysis and Comparison to Doppler Echocardiography

et al. 1991

View full text Add to dashboard Cite

Cine magnetic resonance imaging (MRI) displays cardiac flow in cine loop fashion on multiple tomographic sections. Since laminar flow is easily distinguished from turbulent flow, cine MRI may be uniquely suited to the study of valvular regurgitation: the entire cardiac volume can be sampled and the regurgitant jet at the valve plane can be depicted. We therefore assessed aortic regurgitation (AR) by cine MRI in 35 patients and 11 normal volunteers and compared results to pulsed (n = 32) or color flow Doppler (n = 14). The extent of the flow disturbance was estimated for both cine MRI and Doppler by indexing the size of the maximal, single plane regurgitant jet area (JA) to the left ventricular (LV) area. Cine MRI JA/LV ratio compared well with pulsed (r = 0.81) and color flow (r = 0.88) Doppler; classification as mild ( < 20%), moderate (20–40%), and severe ( > 40%) AR by both methods was identical in 43 of 46 cases with no differences of more than one grade. Overall sensitivity and specificity of cine MRI, compared to Doppler, were 94 and 95 %, respectively. Cine MRI also depicted the regurgitant jet at the valve plane in 11 patients. Thus planar analysis of cine MRI images in patients with AR provides a semiquantitative assessment of the AR flow disturbance which is similar to Doppler but, in addition, can image the entire cardiac volume and the regurgitant jet at the valve plane.

show abstract

Effects of Turbulence on Signal Intensity in Gradient Echo Images

Cited by 99 publications

References 0 publications

Detection of Occlusive Lesions in Intracranial Arteries by Three-Dimensional Time-of-Flight Magnetic Resonance Angiography

Detection of Occlusive Lesions in Intracranial Arteries by Three-Dimensional Time-of-Flight Magnetic Resonance Angiography

Non-Invasive Stroke Volume Assessment in Patients with Pulmonary Arterial Hypertension: Left-Sided Data Mandatory.

Evaluation of Aortic Regurgitation by Cardiac Cine Magnetic Resonance Imaging: Planar Analysis and Comparison to Doppler Echocardiography

Contact Info

Product

Resources

About