Projection-based respiratory-resolved left ventricular volume measurements in patients using free-breathing double golden-angle 3D radial acquisition

Objective

To refine a new technique to measure respiratory-resolved left ventricular end-diastolic volume (LVEDV) in mid-inspiration and mid-expiration using a respiratory self-gating technique and demonstrate clinical feasibility in patients.

Materials and methods

Ten consecutive patients were imaged at 1.5 T during 10 min of free breathing using a 3D golden-angle radial trajectory. Two respiratory self-gating signals were extracted and compared: from the k-space center of all acquired spokes, and from a superior–inferior projection spoke repeated every 64 ms. Data were binned into end-diastole and two respiratory phases of 15% respiratory cycle duration in mid-inspiration and mid-expiration. LVED volume and septal–lateral diameter were measured from manual segmentation of the endocardial border.

Results

Respiratory-induced variation in LVED size expressed as mid-inspiration relative to mid-expiration was, for volume, 1 ± 8% with k-space-based self-gating and 8 ± 2% with projection-based self-gating (P = 0.04), and for septal–lateral diameter, 2 ± 2% with k-space-based self-gating and 10 ± 1% with projection-based self-gating (P = 0.002).

Discussion

Measuring respiratory variation in LVED size was possible in clinical patients with projection-based respiratory self-gating, and the measured respiratory variation was consistent with previous studies on healthy volunteers. Projection-based self-gating detected a higher variation in LVED volume and diameter during respiration, compared to k-space-based self-gating.

     

Glucose administration and heme catabolism after caloric restriction

Heme catabolism was monitored through the determination of total serum bilirubin and endogenous production of carbon monoxide in 6 healthy males before and after administration of 100 g of glucose orally and intravenously, respectively. To facilitate comparison, hyperbilirubinemia was induced through a 36-hr period of subtotal caloric restriction before the study. A decrease in production of carbon monoxide was seen after glucose given orally as well as intravenously, whereas total serum bilirubin decreased significantly only after glucose orally. It is suggested that oral as well as intravenous glucose administration temporarily inhibits heme catabolism, at least when given after a period of caloric restriction. In addition, oral glucose might have--probably via a gut-related factor--a facilitating effect on liver uptake of bilirubin.