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Renal T * 2 perfusion using an iron oxide nanoparticle contrast agent—influence of T 1 relaxation on the first‐pass response
Author(s) -
Bjørnerud Atle,
Johansson Lars O.,
Ahlström Håkan K.
Publication year - 2002
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.10058
Subject(s) - perfusion , echo (communications protocol) , nuclear magnetic resonance , bolus (digestion) , chemistry , tracer , materials science , physics , computer science , medicine , surgery , radiology , computer network , nuclear physics
Abstract Quantitative perfusion measurements require accurate knowledge of the correlation between first‐pass signal changes and the corresponding tracer concentration in tissue. In the present study, a detailed analysis of first‐pass renal cortical changes in T 1 and T * 2following bolus injection of the iron oxide nanoparticle NC100150 Injection was investigated in a pig model using a double‐echo gradient‐echo sequence. The estimated change in 1/ T * 2during first pass calculated from single‐echo sequences was compared to the true double‐echo‐derived 1/ T * 2curves. Using a single‐echo (TE = 6 ms) spoiled gradient‐echo sequence, the first‐pass 1/ T * 2response following a bolus injection of 1 mg Fe/kg of NC100150 Injection was significantly underestimated due to counteracting T 1 effects. Signal response simulations showed that the relative error in the first‐pass response decreased with increasing TE and contrast agent dose. However, both the maximum TE and the maximum dose are limited by excessive cortical signal loss, and the maximum TE is further limited by high temporal resolution requirements. The problem of T 1 contamination can effectively be overcome by using a double‐echo gradient‐echo sequence. This yields a first‐pass response that truly reflects the tissue tracer concentration, which is a critical requirement for quantitative renal perfusion assessment. Magn Reson Med 47:298–304, 2002. © 2002 Wiley‐Liss, Inc.