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Use of the mean transit time of an intravascular contrast agent as an exchange‐insensitive index of myocardial perfusion
Author(s) -
Lombardi Massimo,
Jones Richard A.,
Westby Jørgen,
Torheim Geir,
Southon Timothy E.,
Haraldseth Olav,
Michelassi Claudio,
Kvaerness Jørn,
Rinck Peter A.,
L'Abbate Antonio
Publication year - 1999
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/(sici)1522-2586(199903)9:3<402::aid-jmri7>3.0.co;2-n
Subject(s) - mean transit time , perfusion , blood flow , chemistry , nuclear medicine , biomedical engineering , medicine , cardiology , perfusion scanning
A simple two‐compartment model was used to study the effects of water exchange on the signal produced by an inversion recovery prepared rapid gradient‐echo sequence during the first passage of a low dose of an intravascular contrast agent. Water exchange at intermediate rates of exchange (1–10 Hz) between the vascular and extravascular spaces caused the form of the signal changes during the first pass to be dependent on both the fractional sizes of the vascular and extravascular compartments and on the exchange rate. Unless the effects of exchange are minimized by using a very short inversion time, parameters such as the peak height and area under the curve will be affected by regional and/or pathological variations in the exchange rate and the size of the vascular fraction. The mean transit time (MTT) is, however, less affected by water exchange. Experimental first‐pass data produced by intravascular low‐dose injections of iron oxide particles were studied in five pigs at 0.5 T. The MTT as derived from the first‐pass curves, without deconvolution with the arterial input function, was well correlated with the myocardial blood flow (MBF) as measured using radioactive microspheres (r = 0.70, n = 52, P < 0.01). Other first‐pass parameters such as the peak height or area under the curve exhibited either a poorer, or no, correlation with the MBF. The data suggest that the MTT of the first pass of an intravascular contrast agent may be a robust, quantitative method for assessing myocardial blood flow in patients. J. Magn. Reson. Imaging 1999;9:402–408. © 1999 Wiley‐Liss, Inc.