Investigative radiology
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Investigative radiology · Mar 2015
Clinical TrialImproved detection of hypervascular liver lesions with CAIPIRINHA-Dixon-TWIST-volume-interpolated breath-hold examination.
The aim of this study was to assess the diagnostic performance of a dynamic, multiphasic contrast-enhanced volume-interpolated sequence with advanced parallel imaging techniques, Dixon fat saturation, and view sharing with 5 hepatic arterial subphases for the detection of focal liver lesions. ⋯ Compared with a standard hepatic arterial phase, MA-CDT-VIBE with 5 hepatic arterial subphases demonstrated greater diagnostic accuracy for the detection of hypervascular focal liver lesions and provided a robust and optimized hepatic arterial acquisition phase.
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Investigative radiology · Mar 2015
Subtype differentiation of renal tumors using voxel-based histogram analysis of intravoxel incoherent motion parameters.
The aim of this study was to determine if voxel-based histogram analysis of intravoxel incoherent motion imaging (IVIM) parameters can differentiate various subtypes of renal tumors, including benign and malignant lesions. ⋯ Intravoxel incoherent motion imaging parameters with inclusion of histogram measures of heterogeneity can help differentiate malignant from benign lesions as well as various subtypes of renal cancers.
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Investigative radiology · Mar 2015
Optimizing contrast media injection protocols in state-of-the art computed tomographic angiography.
Very short acquisition times and the increasing use of low-kilovolt protocols in standard computed tomographic (CT) angiography (CTA) examinations demand modifications in the contrast media (CM) injection regimen. The aim of this study was to optimize the use of tube voltage-adjusted CM delivery parameters, especially injection duration and iodine delivery rate (IDR), in thoracoabdominal CTA in a porcine model. ⋯ The optimization of CM injection protocols is mandatory to achieve state-of the art CTA at low kilovolt and can reduce CM doses to patients.
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Investigative radiology · Jan 2015
Impact of measurement parameters on apparent diffusion coefficient quantification in diffusion-weighted-magnetic resonance imaging.
The scope of this work was to systematically evaluate the reproducibility of diffusion-weighted imaging and the impact of b values used for apparent diffusion coefficient (ADC) calculation as well as the echo time (TE) on the resulting ADC in phantom studies. We attempted to find a minimum upper b value needed for reliable ADC measurements. In addition, we were able to investigate these impacts not only for different diffusivities but also for different T2 relaxation times. The influence of different b values on ADC calculations for different organs was also assessed in a volunteer study. ⋯ Apparent diffusion coefficient can be measured with high reproducibility but strongly depends on b values used and TE, which should be kept constant in each examination protocol. Whereas upper b values as low as 400 s/mm can be used for examinations of tissues with low diffusivities, very high b values (>1000 s/mm) are needed to reach an optimal SNR for high diffusive tissues. An upper b value of 600 s/mm is a good compromise regarding ADC stability, SNR, and measurement time for all tissue types.
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Investigative radiology · Jan 2015
A clinically feasible treatment protocol for magnetic resonance-guided high-intensity focused ultrasound ablation in the liver.
Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) allows for noninvasive thermal ablation under real-time temperature imaging guidance. The purpose of this study was to assess the feasibility and safety of MR-HIFU ablation of liver tissue in a clinically acceptable setting. The experimental protocol was designed with a clinical ablation procedure of a small malignant tumor in mind; the procedures were performed within a clinically feasible time frame and care was taken to avoid adverse events. The main outcome was the size and quality of the ablated liver tissue volume on imaging and histology. Secondary outcomes were safety and treatment time. ⋯ Our results demonstrate the feasibility and safety of MR-HIFU ablation of liver tissue volumes. The imaging data and cell viability histology show, for the first time, that confluent ablation volumes can be achieved with motion-gated ablation and MR guidance. These results were obtained using a readily available MR-HIFU system with only minor modifications, within a clinically acceptable time frame, and with only minor adverse events. This shows that this technique is sufficiently reliable and safe to initiate a clinical trial.