Noninvasive quantification of myocardial blood flow in humans : A direct comparison of the [13N]ammonia and the [15O]water techniques

• Published in: Circulation (New York, N.Y.) N.Y.), 1996-06, Vol.93 (11), p.2000-2006
• Main Authors: NITZSCHE, E. U, CHOI, Y, CZERNIN, J, HOH, C. K, HUANG, S.-C, SCHELBERT, H. R
• Format: Article
• Language: English
• Subjects: Adenosine - pharmacology; Adult; Ammonia; Animals; Biological and medical sciences; Cardiovascular system; Coronary Circulation - drug effects; Coronary Vessels - diagnostic imaging; Dogs; Female; Half-Life; Heart - diagnostic imaging; Humans; Hyperemia - chemically induced; Hyperemia - physiopathology; Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Isotopes; Male; Medical sciences; Nitrogen Isotopes; Oxygen - pharmacokinetics; Radionuclide investigations; Rest; Species Specificity; Stress, Physiological - physiopathology; Tomography, Emission-Computed; Vasodilator Agents - pharmacology; Water
• ISSN: 0009-7322; 1524-4539
• DOI: 10.1161/01.CIR.93.11.2000

[13N]Ammonia has been validated in dog studies as a myocardial blood flow tracer. Estimates of myocardial blood flow by [13N]ammonia were highly linearly correlated to those by the microsphere and blood sample techniques. However, estimates of myocardial blood flow with [13N]ammonia in humans have not yet been compared with those by an independent technique. This study therefore tested the hypothesis that the [13N]ammonia positron emission tomographic technique in humans gives estimates of myocardial blood flow comparable to those obtained with the [15O]water technique. A total of 30 pairs of positron emission tomographic flow measurements were performed in 30 healthy volunteers; 15 volunteers were studied at rest and 15 during adenosine-induced hypermia. Estimates of average and of regional myocardial blood flow by the [13N]ammonia and the [15O]water approaches correlated well (y = 0.02 + 1.02x, r = .99, P < .001 SEE = 0.023 for average and y = 0.06 + 1.00x, r = .97, P < .001, SEE = 0.025 for regional values) over a flow range of 0.45 to 4.74 mL.min-1.g-1. At rest, mean myocardial blood flow was 0.64 +/- 0.09 mL.min-1.g-1 for [13N]ammonia and 0.66 +/- 0.12 mL.min-1.g-1 for [15O]water (P = NS). For adenosine-induced hyperemia, mean myocardial blood flow was 2.63 +/- 0.75 mL.min-1.g-1 for [13N]ammonia and 2.73 +/- 0.77 mL.min-1.g-1 for [15O]water (P = NS). The coefficient of variation as an index of the observed heterogeneity of myocardial blood flow averaged, for [13N]ammonia, 9 +/- 4% at rest and 12 +/- 7% during stress and, for [15O]water, 14 +/- 11% at rest and 16 +/- 9% during stress. The coefficients of variation for [15O]water were significantly higher than those for [13N]ammonia (P = .004 at rest and P = .03 during stress). The two approaches yield comparable estimates of myocardial blood flow in humans, which supports the validity of the [13N]ammonia method in human myocardium previously shown only in animals. However, the [15O]water approach reveals a greater heterogeneity (presumably method-related), which might limit the accuracy of sectorial myocardial blood flow estimates in humans.