DiŠusion-weighted imaging (DWI) has recently been attempted in the abdominal region. We review diŠusion-weighted images of the liver, especially from the technical point of view. We discuss selection of pulse sequence parameters, eŠects of anti-breathing motion technique, tips for measuring apparent diŠusion coe‹cient (ADC), and utility of superparamagnetic iron oxide (SPIO), showing clinical cases, including those at 3T. Our current trial of new pulse sequencing, such as SPIO-mediated breath-holding black-blood ‰uid-attenuated inversion recovery (BH-BB-FLAIR), imaging is shown. Some prospects for the future in DWI of the liver are also stated.
We evaluated the newly developed whole-brain, isotropic, 3-dimensional turbo spin-echo imaging with variable flip angle echo train (SPACE) for contrast-enhanced T(1)-weighted imaging in detecting brain metastases at 3 tesla (T). Twenty-two patients with suspected brain metastases underwent postcontrast study with SPACE, magnetization-prepared rapid gradient-echo (MP-RAGE), and 2-dimensional T(1)-weighted spin echo (2D-SE) imaging at 3T. We quantitatively compared SPACE, MP-RAGE, and 2D-SE images by using signal-to-noise ratios (SNRs) for gray matter (GM) and white matter (WM) and contrast-to-noise ratios (CNRs) for GM-to-WM, lesion-to-GM, and lesion-to-WM. Two blinded radiologists evaluated the detection of brain metastases by segment-by-segment analysis and continuously-distributed test. The CNR between GM and WM was significantly higher on MP-RAGE images than on SPACE images (P<0.01). The CNRs for lesion-to-GM and lesion-to-WM were significantly higher on SPACE images than on MP-RAGE images (P<0.01). There was no significant difference in each sequence in detection of brain metastases by segment-by-segment analysis and the continuously-distributed test. However, in some cases, the lesions were easier to detect in SPACE images than in other sequences, and also the vascular signals, which sometimes mimic lesions in MP-RAGE and 2D-SE images, were suppressed in SPACE images. In detection of brain metastases at 3T magnetic resonance (MR) imaging, SPACE imaging may provide an effective, alternative approach to MP-RAGE imaging for 3D T(1)-weighted imaging.
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