Influence of fat suppression to evaluate T1 values in breast cancer: assessing the reliability of pharmacokinetic parameters
Kayu Takezawa1, Mariko Goto1, Koji Sakai1, Hiroyasu Ikeno1, Katsuhiko Nakatsukasa2, Hiroshi Imai3, and Kei Yamada1

1Radiology, Kyoto Prefectural University of Medicine, Kyoto, Japan, 2Breast Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan, 3Siemens Japan K.K, Tokyo, Japan


The influence of fat suppression on T1 values and pharmacokinetic parameters in breast cancer were evaluated using a prototype Dixon-TWIST-VIBE technique. We measured T1 values of breast cancers on both fat suppression and not-fat suppression data sets and we calculated Ktrans values using same ROI that employed on T1 value measurements. Our result suggests that the fat suppression might influence T1 values in breast cancer, and reliability of Ktrans seemed inappropriate as an absolute value. On the other hand, the assessment of intra-patient Ktrans change might be feasible.

Introduction and Purpose

Pharmacokinetic analysis using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) directly reflects the physiological properties; including vessel permeability, perfusion and the volume of the extravascular/extracellular spaces. In breast lesions, it has been shown that pharmacokinetic analysis can potentially improve the differentiation of malignant from benign lesion, and is valuable in monitoring the responses to neoadjuvant chemotherapy1-3.

Pharmacokinetic parameters are calculated using the tissue T1 values. In the breast DCE MRI, fat-suppression techniques are routinely applied to improve the delineation of tumors. Two flip angles (FA) images with fat-suppression are commonly used to create T1 mapping. However, the breast fibroglandular tissue contains various amount of fat tissue, and T1 values of both the breast tissue and tumor are expected to change from with and without fat-suppression. The difference of T1 values may influence the calculated permeability parameters.

Prototype Dixon-TWIST-VIBE (DT-VIBE) technique provides high temporal and spatial resolution and makes it possible to obtain both fat suppression (water image) and non-fat suppression (in-phase) images from the same data set. In this study, we evaluated the influence of fat-suppression on T1 values and pharmacokinetic parameters in DCE-MRI of breast lesions using the prototype DT-VIBE technique.

Material and Methods

MRI was performed using a 3.0-T MRI system (MAGNETOM Skyra; Siemens Healthcare, Erlangen, Germany) with a 16-channel phased-array bilateral breast coil. A 2-point variable FAs (5°, 15°) with Dixon images were applied for T1 mapping. Prototype DT-VIBE (temporal resolution: 5 s, spatial resolution: 1 mm x 1mm x 3 mm) was performed in both early (25 flames within 2 min 22 s, started from 22 s before contrast material injection) and delayed phases (9 flames within 30 s, started from 5 min after injection). The total number of scan frames was 34 with a scan time of 5 min 30 s.

T1 values and pharmacokinetic parameters (Ktrans) were calculated for five female patients (mean age, 59.8 years; range, 49-75 years) with locally advanced breast cancers who were scheduled for neoadjuvant chemotherapy (NAC) including bevacizumab. Four of the five patients underwent MRI before and after a cycle of NAC. We obtained total of nine MR examinations (before treatment, n=5; after NAC, n=4). On DT-VIBE, regions of interest (ROIs) were delineated by an experienced radiologist, who free-handedly traced the whole tumor as carefully as possible (Fig. 1). These ROIs were copied on both T1 and Ktrans maps generated from the DT-VIBE datasets.

Pharmacokinetic evaluation was performed based on the two-compartment Tofts model using Tissue 4D® software (Siemens Healthcare). T1 and Ktrans values were compared between in-phase and Dixon-water images on each examination using the Wilcoxon rank-sum test (Matlab®; MathWorks, Natick, MA). Values of p<0.05 were treated as significant.


T1 values for breast tumors showed no significant difference between in-phase and Dixon-water images (Fig. 2; p = 1.00), but some cases showed large differences of more than 50% (Fig. 3a, P4). In terms of Ktrans values, some cases also showed large differences of more than 30% (Fig. 4). The change in intra-patient Ktrans values between before and after NAC showed the same decreasing tendency for both in-phase and Dixon-water images, with no significant difference in decreasing ratio (Fig. 4; p=0.875).


In our study, we have shown that some of the cases may exhibit large differences in T1 values between in-phase and Dixon-water images, although there was no statistical significant differences. One of the causes of this variety in T1values might be attributed to the fat fraction within the placed ROI. In long T1 value tissues, such as breast tumors on pre-contrast images, slight measured signal difference can yield large difference in the calculated T1 value using 2-point valuable flip angle method. Thus, the reliability of Ktrans measurement using different image data sets seemed inappropriate. Assessment of the intra-patient Ktrans change ratio using the same dataset might be feasible.Our results suggest that Ktrans can be used as a relative value, but not an absolute value that allows comparison between patients.

There were several limitations in our study. First, the sample size was small. Second, we evaluated only one ROI in each lesion. Third, influence of fat suppression only using Dixon method was evaluated. Phantom study was needed to evaluate the influence of other fat suppression method.


In breast cancers, measured T1 values and Ktrans may change according to with or without fat-suppression. Assessments of intra-patient Ktrans changes would be feasible as relative values, but not feasible as an absolute value to compare among patients, owing to the variability in T1 values observed in fat-suppressed images.


No acknowledgement found.


1. Huang W, Tudorica LA, Li X, et al. Discrimination of benign and malignant breast lesions by using shutter-speed dynamic contrast-enhanced MR imaging. Radiology. 2011;261:394–403

2. Schabel MC, Morrell GR, Oh KY, et al. Pharmacokinetic mapping for lesion classification in dynamic breast MRI. J Magn Reson Imaging. 2010;31:1371– 1378

3. Yu Y, Jiang Q, Miao Y, et al. Quantitative analysis of clinical dynamic contrast-enhanced MR imaging for evaluating treatment response in human breast cancer. Radiology. 2010;257:47–55


ROIs for breast cancers in five patients. ROIs were free-handedly traced for the whole tumor. Non-enhanced lesions, such as necrotic, cystic and fibrotic components, were excluded.

Comparison between T1 values of breast cancers for Dixon in-phase and water images. T1 values show no significant difference between in-phase and Dixon-water images (p = 1.00).

T1 values for breast tumors in Dixon in-phase and water images in each patient. a) Before NAC; b) after NAC. Some cases, such as Patient 4 before NAC, show large differences in values of more than 50% between Dixon in-phase and water images (arrow).

Ktrans values show a large difference of more than 30% between in-phase and Dixon water images in Patient 2 (arrow). Intra-patient Ktrans values change from before treatment to after NAC, showing the same decreasing tendency with no significant difference in decreasing ratio (P = 0.8750).

Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)