Perfusion quantification in breast using T1-weighted DCE MRI: contrast agent concentration determination at 3T

Yves Fierens, Robert Luypaert, Smitha Makkat, Johan De Mey

Onderzoeksoutput: Conference paper

Samenvatting

Introduction:
Perfusion estimates based on T1 weighted dynamic contrastenhanced (DCE) MRI have been shown to be promising for non-invasive breast tumor characterisation and assessment of anti-angiogenic treatment [1]. The exam is usually performed in the context of a comprehensive MR protocol that also comprises standard morphologic imaging as well as low temporal resolution bolus tracking, both at high spatial resolution. The protocol routinely uses a dedicated breast coil, characterised by a non-uniform spatial response [2]. Quantitative analysis of the DCE data requires translation of the acquired signals to contrast agent concentrations, typically on the basis of a signal-concentration calibration curve and scanning of a reference
fluid of known concentration with the patient [3]. The aim of this study was to determine the influence of the presence of the breast coil on this procedure on a 3T system.
Materials and Methods:
The measurements were performed on a Philips 3T Achieva MR system. The T1-weighted turbo field echo (TFE) sequence
was acquired with the same parameters as those selected for breast perfusion studies (TR/TE:4.9msec/2.4msec, non- selective 180° prepulse, inversion time 196ms, 128x90 matrix, FOV43 cm, slice thickness 6mm, temporal resolution
of 0.3s). MR images of multiple 20mm-diameter syringes filled with different concentrations of contrast agent (0-4 mmole/l Gd-DTPA solution in saline) were obtained with the quadrature head coil and the corresponding signal vs concentration curve was fitted to provide a calibration curve. In order to mimic the in vivo concentration determinations and assess the effect of rf inhomogeneity, 4 syringes were placed inside the 7 channel breast coil (Figure 1) and imaged for each of four cyclical permutations of these syringes, with either the breast coil or the built-in body coil (breast coil present but not used).
The syringe of highest concentration was subsequently used as reference for the concentration determinations. The root mean square (rms) procentual deviation between measurement and known concentration was used as a figure of merit.
Results:
The resulting concentrations (Figure 2) depend strongly on the position of the syringes inside the breast coil.
In spite of the lower SNR obtained, detecting the signals with the body coil instead of the breast coil leads to a significant improvement of the results, with mean rms percentages dropping from 27% to 10%.
References:
[1] Makkat et al. [2008] Radiology, accepted
[2] Makkat et al [2007] J Magn Reson Imaging;25(6):1159-67.
[3] Makkat et al. [2008] Proc ISMRM;16;3563
Originele taal-2English
TitelProceedings ESMRMB 2008
Pagina's198-198
Aantal pagina's1
StatusPublished - 3 okt 2008
EvenementUnknown - Stockholm, Sweden
Duur: 21 sep 200925 sep 2009

Conference

ConferenceUnknown
LandSweden
StadStockholm
Periode21/09/0925/09/09

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