Changes in myocardial oxygenation and perfusion under pharmacological stress with dipyridamole: Assessment usingT*2 andT1 measurements

Abstract

The aim of this pilot‐study was to evaluate changes in myocardial oxygenation and perfusion under pharmacological stress with dipyridamole (DIP) by means of MRI. Twenty healthy volunteers were examined using a multi‐echo gradient‐echo sequence. The differential myocardial signal response due to the blood oxygen level dependent (BOLD) effect was studied under variable conditions of myocardial oxygen supply caused by the vasodilator DIP. Unlike contrast agents (CA) methods, which require at least two injections of CA and DIP, the presented methods require only a single infusion of DIP. To assess changes in myocardial perfusion, a saturation recovery TurboFLASH (SRTFL) sequence with centric reordering for T1 measurements was used with global and slice‐selective spin‐preparation (five volunteers). The signal response was measured at baseline conditions and when myocardial blood flow was increased during pharmacological stress with DIP. Administration of DIP induced a 17 ± 9% increase in T*2. Enhanced perfusion resulted in a 15 ± 5% decrease of T1 after slice‐selective spin preparation and a calculated increase in absolute perfusion of about 5.1 ml/(g × min), which reflects coronary reserve. The study shows that DIP‐induced alterations in the relationship between myocardial oxygen supply and demand are detectable in healthy volunteers using T*2 and T1 measurements. A combination of T*2 and T1 examinations could become a useful diagnostic tool for the non‐invasive assessment of myocardial oxygenation and perfusion in patients with coronary artery disease (CAD). Magn Reson Med 41:686–695, 1999. © 1999 Wiley‐Liss, Inc.

Oxygenation-sensitive CMR for assessing vasodilator-induced changes of myocardial oxygenation

“…T 2 * mapping was more sensitive to oxygenation changes but showed more variability. The fact that BOLD CMR shows a linear correlation to coronary sinus oxygen saturation is in agreement with the expected proportionality between the BOLD effect and the absolute tissue content of deoxygenated hemoglobin[13,19,20]. Importantly, a previous theoretical study by Dharmakumar et al demonstrated that the BOLD signal is blood volume-independent[21].…”

Anthracycline-Associated T1 Mapping Characteristics Are Elevated Independent of the Presence of Cardiovascular Comorbidities in Cancer Survivors

“…23,24 Previously, both skeletal and cardiac muscle have demonstrated increased intracellular edema related to inflammatory cytokines associated with cancer before treatment. 25 Thus, our observation of T1-related changes in newly diagnosed cancer patients may be related to the presence of comorbidities, cancer-related processes, or a mixture of both.…”

Calibration of myocardial T2 and T1 against iron concentration

“…For T2*, susceptibility artefacts are often seen at the myocardial-lung interface, in the inferior wall due to heavy iron loading in the liver, as a result of cardiac motion, and from veins in the atrioventricular groove containing deoxygenated blood. Although blood oxygenation level affects T2* in vivo, T1 and T2 are less affected and in any case, this is unlikely to affect post-mortem T1 or T2 values [36]. …”