BOLD indirect vs. ASL direct measurement of muscle perfusion

2005 ◽  
Vol 99 (1) ◽  
pp. 376-377 ◽  
Author(s):  
A. Leroy-Willig
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Maximal Voluntary Contraction ◽  
Venous Occlusion ◽  
Voluntary Contraction ◽  
Arterial Blood Flow ◽  
Muscle Perfusion ◽  
Arterial Blood ◽  
Planar Images

The following is the abstract of the article discussed in the subsequent letter: Although skeletal muscle perfusion is fundamental to proper muscle function, in vivo measurements are typically limited to those of limb or arterial blood flow, rather than flow within the muscle bed itself. We present a noninvasive functional MRI (fMRI) technique for measuring perfusion-related signal intensity (SI) changes in human skeletal muscle during and after contractions and demonstrate its application to the question of occlusion during a range of contraction intensities. Eight healthy men (aged 20–31 yr) performed a series of isometric ankle dorsiflexor contractions from 10 to 100% maximal voluntary contraction. Axial gradient-echo echo-planar images (repetition time = 500 ms, echo time = 18.6 ms) were acquired continuously before, during, and following each 10-s contraction, with 4.5-min rest between contractions. Average SI in the dorsiflexor muscles was calculated for all 240 images in each contraction series. Postcontraction hyperemia for each force level was determined as peak change in SI after contraction, which was then scaled to that obtained following a 5-min cuff occlusion of the thigh (i.e., maximal hyperemia). A subset of subjects ( n = 4) performed parallel studies using venous occlusion plethysmography to measure limb blood flow. Hyperemia measured by fMRI and plethysmography demonstrated good agreement. Postcontraction hyperemia measured by fMRI scaled with contraction intensity up to 60% maximal voluntary contraction. fMRI provides a noninvasive means of quantifying perfusion-related changes during and following skeletal muscle contractions in humans. Temporal changes in perfusion can be observed, as can the heterogeneity of perfusion across the muscle bed.

MRI measures of perfusion-related changes in human skeletal muscle during progressive contractions

2004 ◽  
Vol 97 (6) ◽  
pp. 2385-2394 ◽  
Author(s):  
D. M. Wigmore ◽  
B. M. Damon ◽  
D. M. Pober ◽  
J. A. Kent-Braun
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Maximal Voluntary Contraction ◽  
Human Skeletal Muscle ◽  
Venous Occlusion ◽  
Voluntary Contraction ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Planar Images

Although skeletal muscle perfusion is fundamental to proper muscle function, in vivo measurements are typically limited to those of limb or arterial blood flow, rather than flow within the muscle bed itself. We present a noninvasive functional MRI (fMRI) technique for measuring perfusion-related signal intensity (SI) changes in human skeletal muscle during and after contractions and demonstrate its application to the question of occlusion during a range of contraction intensities. Eight healthy men (aged 20–31 yr) performed a series of isometric ankle dorsiflexor contractions from 10 to 100% maximal voluntary contraction. Axial gradient-echo echo-planar images (repetition time = 500 ms, echo time = 18.6 ms) were acquired continuously before, during, and following each 10-s contraction, with 4.5-min rest between contractions. Average SI in the dorsiflexor muscles was calculated for all 240 images in each contraction series. Postcontraction hyperemia for each force level was determined as peak change in SI after contraction, which was then scaled to that obtained following a 5-min cuff occlusion of the thigh (i.e., maximal hyperemia). A subset of subjects ( n = 4) performed parallel studies using venous occlusion plethysmography to measure limb blood flow. Hyperemia measured by fMRI and plethysmography demonstrated good agreement. Postcontraction hyperemia measured by fMRI scaled with contraction intensity up to ∼60% maximal voluntary contraction. fMRI provides a noninvasive means of quantifying perfusion-related changes during and following skeletal muscle contractions in humans. Temporal changes in perfusion can be observed, as can the heterogeneity of perfusion across the muscle bed.

Evidence for a rapid vasodilatory contribution to immediate hyperemia in rest-to-mild and mild-to-moderate forearm exercise transitions in humans

2004 ◽  
Vol 97 (3) ◽  
pp. 1143-1151 ◽  
Author(s):  
Natasha R. Saunders ◽  
Michael E. Tschakovsky
Keyword(s):  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Arterial Blood Flow ◽  
Vascular Conductance ◽  
Muscle Pump ◽  
Arterial Blood ◽  
Exercise Hyperemia ◽  
Forearm Vascular Conductance ◽  
Condition B

Controversy exists regarding the contribution of a rapid vasodilatory mechanism(s) to immediate exercise hyperemia. Previous in vivo investigations have exclusively examined rest-to-exercise (R-E) transitions where both the muscle pump and early vasodilator mechanisms may be activated. To isolate vasodilatory onset, the present study investigated the onset of exercise hyperemia in an exercise-to-exercise (E-E) transition, where no further increase in muscle pump contribution would occur. Eleven subjects lay supine and performed a step increase from rest to 3 min of mild (10% maximal voluntary contraction), rhythmic, dynamic forearm handgrip exercise, followed by a further step to moderate exercise (20% maximal voluntary contraction) in each of arm above ( condition A) or below ( condition B) heart level. Beat-by-beat measures of brachial arterial blood flow (Doppler ultrasound) and blood pressure (arterial tonometry) were performed. We observed an immediate increase in forearm vascular conductance in E-E transitions, and the magnitude of this increase matched that of the R-E transitions within each of the arm positions ( condition A: E-E, 52.8 ± 10.7 vs. R-E, 60.3 ± 11.7 ml·min−1·100 mmHg−1, P = 0.66; condition B: E-E, 43.2 ± 12.8 vs. R-E, 33.9 ± 8.2 ml·min−1·100 mmHg−1, P = 0.52). Furthermore, changes in forearm vascular conductance were identical between R-E and E-E transitions over the first nine contraction-relaxation cycles in condition A. The immediate and identical increase in forearm vascular conductance in R-E and E-E transitions within arm positions provides strong evidence that rapid vasodilation contributes to immediate exercise hyperemia in humans. Specific vasodilatory mechanisms responsible remain to be determined.

Abstract 249: Delayed Gene Transfer Increases Transgene Expression in Vein Grafts

2013 ◽  
Vol 33 (suppl_1) ◽  
Author(s):  
Liang Du ◽  
Jingwan Zhang ◽  
Alexander Clowes ◽  
David Dichek
Keyword(s):  
Gene Expression ◽  
Blood Flow ◽  
Gene Transfer ◽  
Transgene Expression ◽  
Ex Vivo ◽  
Arterial Blood Flow ◽  
Vein Grafts ◽  
Arterial Blood ◽  
En Face

Background Autogenous vein grafts are effective therapies for obstructive arterial disease. However, their long-term utility is limited by stenosis and occlusion. Genetic engineering of veins that prevents intimal hyperplasia and atherosclerosis could significantly improve the clinical utility of vein grafts. We recently reported that a helper-dependent adenoviral vector (HDAd) reduces atherosclerosis 4 wks after gene transfer in fat-fed rabbits and can express a therapeutic transgene (apo AI) in normal rabbit carotids for at least 48 wks. Use of HDAd for vein graft gene therapy will depend on achievement of similarly high and persistent transgene expression in grafted veins. Hypothesis We tested the hypothesis that Ad-mediated transgene expression in grafted veins (at an early time point) can be increased by varying the timing of gene transfer. Methods Rabbit external jugular veins were transduced by exposure to a beta galactosidase (b-gal)-expressing Ad: in situ either without (a) or with (b) immediate arterial grafting; c) ex vivo with grafting after overnight incubation with Ad; d) in vivo immediately after grafting and e) in vivo 4 wks after grafting (n = 6 - 19 veins/group). Transgene expression was measured in veins removed 3 d after Ad exposure by PCR quantitation of b-gal mRNA and by en-face planimetry of blue-stained area. Results B-gal transgene expression was higher in ungrafted veins than in veins grafted immediately after gene transfer (84 ± 17 vs 9.4 ± 2.0 arbitrary units (AU); P < 0.0001). Overnight incubation of veins with Ad increased gene expression ex vivo by 10-fold but neither this nor performing vector infusion immediately after grafting improved gene expression (11 ± 4.7 and 9.1 ± 1.8 AU; P > 0.9 for both vs immediately grafted veins). Delaying gene transfer until 4 wks after grafting significantly increased gene expression, to a level equivalent to transgene expression in ungrafted veins (61 ± 11 AU; P = 0.3 vs ungrafted veins). En face planimetry yielded similar results. Conclusions Exposure of a transduced vein to arterial blood flow is associated with significant loss of transgene expression. Transgene expression in grafted veins is significantly higher when gene transfer is performed 4 wks after exposure of the vein to arterial blood flow.

Spiral Laminar Flow in Vivo

1996 ◽  
Vol 91 (1) ◽  
pp. 17-21 ◽  
Author(s):  
P. A. Stonebridge ◽  
P. R. Hoskins ◽  
P.L. Allan ◽  
J. F. F. Belch
Keyword(s):  
Blood Flow ◽  
Reverse Flow ◽  
Arterial Disease ◽  
Flow Patterns ◽  
Endothelial Damage ◽  
Arterial Blood Flow ◽  
Arterial Tree ◽  
Arterial Blood ◽  
Blood Flow Patterns

1. Blood flow patterns are poorly understood despite their impact on arterial disease. There have been few measurements in vivo of the three-dimensional blood flow patterns; we present the results of such studies using a new non-invasive in-vivo method of examining biplanar arterial blood flow patterns. 2. Multiple colour Doppler ultrasound directional velocity images were obtained at two different beam target angles from the artery in the plane perpendicular to its axis. Ensemble average images were constructed; the absolute velocity and direction were calculated by compounding the left and right averaged images. Simple directional, non-directional velocity and vector maps were constructed. 3. Flow patterns were sampled in 11 healthy male volunteers at four points of the pulse cycle; peak systole, systolic downswing, diastolic reverse flow and diastolic forward flow and at three sites; the right common and distal superficial femoral and the left common femoral arteries. 4. Stable rotational flow was observed in all subjects, the direction of rotation varying between sides and individuals. 5. There are theoretical advantages to spiral laminar blood flow; the forward-directed, rotationally induced stability and reduction of laterally directed forces may reduce turbulence in the tapering branching arterial tree and at stenoses and have a beneficial effect on mechanisms of endothelial damage and repair.

scholarly journals Validation of the mean systemic filling pressure assessment with preserved arterial blood flow by comparing two methods of calculation 

2021 ◽  
Author(s):  
Roberto Alberto De Blasi ◽  
Stefano Finazzi
Keyword(s):  
Near Infrared ◽  
Venous Occlusion ◽  
Calculation Model ◽  
Arterial Blood Flow ◽  
Venous Compliance ◽  
Model Method ◽  
Arterial Blood ◽  
Methods Of Calculation ◽  
Multi Phase

Abstract Significance: We developed a method for measuring in vivo venular volumes and pressures in the limbs using near-infrared spectroscopy (NIRS).Aim: 36 We aimed to validate the NIRS methodology by comparing two independent methods of calculation based on different physiological approaches.Approach: Pressure-volumes curves were recorded following graded venous occlusion on the forearm. Values from a multi-phase model (method 1) were compared with data derived from a resistor-capacitance calculation model (method 2) based on arterial pressure and venous compliance. We tested these methods on 10 healthy participants at rest and during exercise and on 6 severely ill patients.Results: Pressure-volume curves measured by method 1 were comparable with those calculated by method 2. Venular volumes calculated using method 1 correlated linearly with those calculated using method 2 both in participants (R2 = 0.98, p < 0.001) and in patients (R2 = 0.94, p < 0.001). The Bland-Altman test showed a good agreement between methods with few values out of the range of ± 1.96 SD.Conclusions: Our findings showed that the NIRS methodology may be valid for the assessment of venular bed with no flow interruption. Further research will be required to confirm the relevance of methodology in the clinical setting.

Comparison of plethysmographic methods with pulsed Doppler blood flowmetry

1979 ◽  
Vol 236 (6) ◽  
pp. H899-H903 ◽  
Author(s):  
B. I. Levy ◽  
W. R. Valladares ◽  
A. Ghaem ◽  
J. P. Martineaud
Keyword(s):  
Blood Flow ◽  
Strain Gauge ◽  
Venous Occlusion ◽  
Arterial Blood Flow ◽  
Pulsed Doppler ◽  
Local Cooling ◽  
Doppler Flowmetry ◽  
Strain Gauge Plethysmography ◽  
Arterial Blood ◽  
Local Warming

Hand blood flow was measured at rest, with local warming, and with local cooling. Three methods were simultaneously used: water plethysmography (WP), mercury-in-rubber strain gauge plethysmography (SG), and pulsed Doppler flowmetry (D). Of these, water plethysmography is the most sensitive and accurate; strain gauge plethysmography is simpler but less accurate; and pulsed Doppler flowmetry precisely measures instantaneous arterial blood flow without venous occlusion.

Skeletal muscle arteriolar constriction to ANG II: evaluation of a myogenic component

1992 ◽  
Vol 263 (6) ◽  
pp. H1847-H1854 ◽  
Author(s):  
J. T. Fleming ◽  
G. L. Anderson ◽  
J. Chen
Keyword(s):  
Blood Pressure ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Pressure Rise ◽  
Arterial Blood Flow ◽  
Ang Ii ◽  
Cremaster Muscle ◽  
Abrupt Decrease ◽  
Arterial Blood ◽  
Slow Infusion

This study addressed the hypothesis that an increase in blood pressure contributes to the overall constrictive response of skeletal muscle arterioles to angiotensin II (ANG II). Diameters of second-order arterioles (2A) and third-order arterioles (3A) in the rat cremaster muscle were quantitated after intravenous administration of ANG II. Hindquarter blood pressure was either allowed to increase or was maintained at normal levels. Constriction of 3A to bolus injection of ANG II was the same whether hindquarter pressure increased or not. However, the total vascular constrictive response of the cremaster muscle (based on 2A blood flow) and of the entire hindquarter (based on iliac arterial blood flow) to bolus ANG II was greater when hindquarter pressure was held constant. During slow infusion of ANG II, 3A constriction was unaffected by an abrupt decrease or increase in hindquarter pressure. However, an abrupt reduction of hindquarter pressure caused a significant decline in hindquarter vascular resistance. Thus an increase in blood pressure, whether rapid or gradual, does not influence 3A constriction to ANG II. However, in the entire hindquarter, a rapid rise in blood pressure opposes constriction to ANG II, whereas a gradual pressure rise evokes a mechanism that enhances constrictive response to the peptide

EFFECT OF VENOUS OCCLUSION ON PERIPHERAL ARTERIAL BLOOD-FLOW

The Lancet ◽  
1951 ◽  
Vol 257 (6651) ◽  
pp. 380-382 ◽  
Author(s):  
JesseE. Thompson ◽  
JohnR. Vane
Keyword(s):  
Blood Flow ◽  
Venous Occlusion ◽  
Arterial Blood Flow ◽  
Arterial Blood ◽  
Peripheral Arterial
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