PERFUSION IMAGING Regional Heterogeneity of Myocardial Perfusion in Healthy Human Myocardium: Assessment with Magnetic Resonance Perfusion Imaging #

The knowledge of myocardial perfusion in healthy volunteers is fundamental for evaluation of patients with ischemic heart disease. The study was conducted to determine range, regional variability, and transmural gradient of myocardial perfusion in normal volunteers with Magnetic Resonance Perfusion Imaging (MRPI). Perfusion was assessed in 17 healthy volunteers (age: 20–47 yr, 11 males) at rest and adenosineinduced hyperemia using a 1.5 T MR scanner. Perfusion was quantified (mL/g/min) for the transmural myocardium and separately for the endo- and epimyocardium in the anterior, lateral, posterior, and septal left ventricular wall using the Fermi model for constrained deconvolution. Regional variabilities for resting, hyperemic perfusion, and perfusion reserve were 22 ± 8%, 21±10%, and 35±18%. Mean resting, hyperemic perfusion, and perfusion reserve were 1.1±0.4 mL/g/min, 4.2±1.1 mL/g/min, and 4.1±1.4. Perfusion in the septum was higher at rest (1.3±0.3 mL/g/min vs. 1.0± 0.3 mL/g/min, p<0.05) and lower during hyperemia (3.6±0.8 mL/g/min vs. 4.5± 1.1 mL/g/min, p<0.03), resulting in a reduced perfusion reserve (PR) (3.2±0.9 vs

Immediate and 12 months follow up of function and lead integrity after cranial MRI in 356 patients with conventional cardiac pacemakers

Background: Conventional cardiac pacemakers are still often regarded as a contraindication to magnetic resonance imaging (MRI). We conducted this study to support the hypothesis that it is safe to scan patients with cardiac pacemakers in a 1.5 Tesla MRI, if close supervision and monitoring as well as adequate pre- and postscan programming is provided. Methods: We followed up 356 patients (age 61.3 +/- 9.1 yrs., 229 men) with single (n = 132) or dual chamber (n = 224) cardiac pacemakers and urgent indication for a cranial MRI for 12 months. The scans were performed at 1.5T. During the scan patients were monitored with a 3-lead ECG and pulse oximetry. Prior to the scan pacemakers were programmed according to our own protocol. Results: All 356 scans were completed without complications. No arrhythmias were induced, programmed parameters remained unchanged. No pacemaker dysfunction was identified. Follow-up examinations were performed immediately, 2 weeks, 2, 6, and 12 months after the scan. There was no significant change of pacing capture threshold (ventricular 0.9 +/- 0.4 [email protected] ms, atrial 0.9 +/- 0.3 [email protected] ms) immediately (ventricular 1.0 +/- 0.3 [email protected] ms, atrial 0.9 +/- 0.4 [email protected] ms) or at 12 months follow-up examinations (ventricular 0.9 +/- 0.2 [email protected] ms, atrial 0.9 +/- 0.3 [email protected] ms). There was no significant change in sensing threshold (8.0 +/- 4.0 mV vs. 8.1 +/- 4.2 mV ventricular lead, 2.0 +/- 0.9 mV vs. 2.1 +/- 1.0 mV atrial lead) or lead impedance (ventricular 584 +/- 179 O vs. 578 +/- 188 O, atrial 534 +/- 176 O vs. 532 +/- 169 O) after 12 months. Conclusions: This supports the evidence that patients with conventional pacemakers can safely undergo cranial MRI in a 1.5T system with suitable preparation, supervision and precautions. Long term follow-up did not reveal significant changes in pacing capture nor sensing threshold