Calf Muscles Imaged at BOLD MR: Correlation with TcPo₂and Flowmetry Measurements during Ischemia and Reactive Hyperemia—Initial Experience

Abstract

BOLD MR imaging of calf muscles-depending on underlying key parameters-has moderate to good correlation with LDF and TcPo2 measurements during ischemia and reactive hyperemia.

Blood oxygenation level‐dependent (BOLD) MRI of human skeletal muscle at 1.5 and 3 T

“…It was more pronounced in slowtwitch soleus muscle when compared with fast-twitch gastrocnemius muscle, a finding that is well known and may be explained by the larger capillary density and thus higher degree of oxygen diffusion into muscle tissue of that muscle (19). After cuff deflation the larger T2* increase in the soleus muscle compared with the gastrocnemius muscle has also been previously described and may be explained by the better vascularity or perfusion reserve of the mostly oxidative fiber containing soleus muscle (3,4,6,14). As the muscle BOLD effect has a complex origin that is still not completely understood, other mechanisms may also contribute to the observed intermuscular differences.…”

“…This paradigm has been extensively applied and is well established in skeletal muscle BOLD studies due to its easy feasibility and almost complete independence on patient compliance. For muscle BOLD MRI, we used a previously described multiecho gradient-echo EPI sequence that only had to be minimally adapted between the two MRI systems of 1.5 T and 3.0 T (4,6,7,16). This sequence allows the differentiation of tissue oxygen related contrast (''true'' BOLD signal) from changes in T1, baseline drifts, and inflow effects which frequently interfere in conventional single-echo EPI imaging (17,18).…”

“…T2* changes in gradient-echo (GE) echo-planar-imaging (EPI) sequences can mainly be attributed to changes in the intravascular ratio of oxy-to deoxyhemoglobin of the muscle microvasculature (1)(2)(3)(4)(5). Muscle BOLD imaging has been shown to be capable of detecting disturbances of muscle microperfusion in diseases such as peripheral arterial occlusive disease, chronic compartment syndrome, and ischemic heart disease (6)(7)(8)(9).…”

Standards of Practice for Superficial Femoral and Popliteal Artery Angioplasty and Stenting

“…In case of noncompressible vessels, the ToeBrachial Index (TBI) may be used instead (critical level \50 mmHg) [4]. Measurements of TcPO 2 (critical level \30 mmHg) are suggested in case of diabetic patients with ulcers both for baseline evaluation and for assessment of response to revascularization [21,22]. Examination for carotid bruits, cardiac murmurs, gallops, or arrhythmias and palpation for the presence of an abdominal aortic aneurysm also is recommended [3].…”

Dynamic Blood Oxygen Level-dependent MR Imaging of Muscle: Comparison of Postocclusive Reactive Hyperemia in Young Smokers and Nonsmokers

“…[7][8][9] Blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging, an established functional imaging technique, 10,11 is widely used in neuroradiology to assess the function of organs such as the heart 12 and skeletal muscle. [13][14][15][16][17][18][19] According to Ogawa's group, 10 the signal intensity (SI) of BOLD primarily reflects the concentrations of deoxyhemoglobin and oxyhemoglobin in the local microcir-culation. Inhomogeneity of the local magnetic field caused by paramagnetic deoxyhemoglobin in the microvasculature results in decreased apparent transverse relaxation time (T 2 *).…”