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Modelling and Simulation of Nanosystems for Delivering Drugs to the Brain
Published in Carla Vitorino, Andreia Jorge, Alberto Pais, Nanoparticles for Brain Drug Delivery, 2021
Tânia F. G. G. Cova, Sandra C.C. Nunes
Woodworth [58] also resorted to magnetic resonance imaging (MRI)-guided focused ultrasounds to check the possibility of safely enlarge the interstitial spaces of the brain in order to increase the uptake of large therapeutic entities such as particulate drug carriers or modified viruses. Computer simulations were employed to assist treatment planning, evaluate magnetic resonance acoustic radiation force impulse imaging for target validation and examine treatment response by monitoring the electrophysiological and histopathological changes during the administration of a small molecule, Evans blue dye, and nanoparticle probes of different diameters in the living brain.
Breast cancer
Published in Anju Sahdev, Sarah J. Vinnicombe, Husband & Reznek's Imaging in Oncology, 2020
Sarah J Vinnicombe, Alexandra Athanasiou
US elastography has generated much interest recently. Techniques used include strain elastography, shear wave elastography (SWE), and acoustic radiation force impulse imaging. The various outputs all reflect tissue stiffness, which is increased in and around cancers. SWE has the advantage of being quantifiable and readily reproducible; it increases the specificity of greyscale US and could be used to decrease the number of benign biopsies of solid US BI-RADS category 3 lesions (73–75). Tumoural stiffness has also been shown to correlate with prognostic indicators, e.g. grade and nodal status (76).
History of Imaging for Prostate Cancer
Published in Ayman El-Baz, Gyan Pareek, Jasjit S. Suri, Prostate Cancer Imaging, 2018
Anatomic ultrasound imaging is the oldest and most widely used technique to image the prostate. Watanabe et al. were the first to describe the use of transrectal ultrasound (TRUS) imaging of the prostate with a 3.5 MHz transducer in 1974 (12,13). Prostate cancer lesions have been classically described as hypoechoic lesions on TRUS imaging (14,15). However, the low specificity and positive predictive value (PPV) of TRUS imaging was a clear limitation as other conditions such as prostatitis or focal infarcts could also show hypoechoic characteristics. Lee et al. showed that the positive predictive value of TRUS by itself was 41%, the PPV dropped to 24% if the DRE was normal, 12% if the PSA was normal, and only 5% if both the DRE and PSA levels were normal (16). In 1989, Hodge et al. explored the utility of adding lesion-directed biopsies to specific hypoechoic areas found on ultrasound compared to the standard non-targeted TRUS-guided systematic prostate biopsy. In 136 men with abnormal prostates on DRE, they found that directed biopsies toward hypoechoic areas within the prostate added very little yield since in 80/83 patients, prostate cancer was detected by the non-targeted systematic biopsies. The addition of TRUS-guided cores to hypoechoic lesions increased the yield by only 5% (17). Thus TRUS imaging by itself has been inadequate for the diagnosis, characterization, and targeting of prostate cancer due to poor resolution, low specificity, and its negative predictive value. The main concerns of the technique include failure to detect prostate cancer (due to poor spatial resolution of lesions), inaccurate risk stratification (from under sampling in cases of small volume disease, transition zone or anteriorly located tumors) and high detection rate of small clinically insignificant prostate cancer (18–20). Most prostate cancer tissue is known to be harder or stiffer than normal prostate tissue (the digital rectal exam is predicated on the physician detecting harder or abnormal lumps of cancer tissue). With real-time elastography imaging tissue, the physician induces a mechanical excitation in the prostate tissue and then images the response using real-time ultrasound (21). Techniques include strain elastography, acoustic radiation force impulse imaging, and shear wave elastography. Despite some promising results, an absolute quantitative threshold to distinguish benign from malignant tissue still remains to be determined. Thus transrectal ultrasound guidance continues to be used principally to guide systematic 12-core biopsies of the prostate.
The value of acoustic radiation force impulse imaging in preoperative prediction for efficacy of high-Intensity focused ultrasound uterine fibroids ablation
Published in International Journal of Hyperthermia, 2020
Dan-ling Zhang, Xin-xiu Liu, Jian-qing Tang, Song-song Wu, Ning Lin, Gui-sheng Ding, Xiao-li Pan, Sheng Chen
With the development of ultrasound technology, elastography has been gradually introduced into clinical practice, which uses the mechanical characteristics (strain and elasticity modulus) of human soft tissues for clinical imaging [6]. Acoustic Radiation Force pulse Imaging technology (ARFI) is a new elastography-based technology that includes the virtual touch tissue quantification (VTQ) and the virtual touch tissue imaging (VTI) .In this technique, tissue vibration is induced by acoustic radiation force, which causes deformation of tissue and shear wave propagation that are detected by ultrasonic methods, from which the viscoelastic coefficient of tissue is extracted [7]. Therefore, it can be effective to identify the elastic properties of tissues by detecting the data or images to reflect the tissue hardness [8,9]. While ARFI technology has been widely applied for the evaluation of tumor treatment efficacy [10–12], only few studies have shown its value in the preoperative prediction of HIFU ablation of uterine fibroids. In this study, we investigated the correlation between HIFU postoperative ablation rate and preoperative uterine fibroids’ SWV values and VTI grades. In addition, we evaluated the application value of acoustic radiation force impulse imaging in the preoperative prediction of the efficacy of HIFU ablation of uterine fibroids.
The galactose elimination capacity test to monitor liver disease course in patients with Wilson’s disease
Published in Scandinavian Journal of Gastroenterology, 2022
Ditte Emilie Munk, Jessica Björklund, Tea Lund Laursen, Hendrik Vilstrup, Peter Ott, Henning Grønbæk, Thomas Damgaard Sandahl
Measuring the degree of fibrosis with transient elastography (TE), acoustic radiation force impulse imaging (ARFI) and fibrosis scores has shown the ability to differentiate fibrosis stages in WD with TE measured by FibroScan being the most thoroughly investigated [26,27]. However, the validity of FibroScan results depends on the observer experience and, importantly, the degree of fibrosis measured with these methods have yet to be confirmed as associated with liver disease progression and treatment response in patients with WD [16,28]. The GEC test can be performed on all patients and does not rely on observer experience, and we do not expect the test result to be influenced by medical treatment of co-morbidity.
Noninvasive assessment of liver fibrosis in chronic hepatitis B carriers with sound touch elastography: study of surgical pathology specimens
Published in Expert Review of Medical Devices, 2020
Lulu Yang, Jiawu Li, Lin Ma, Hongjin Xiang, Du He, Changli Lu, Lin Tang, Yan Luo, Shigao Chen
Although all US shear wave elastography techniques are based on the same acoustic radiation force impulse imaging principle, each US system manufacturer has implemented its own elastography platforms to push or detect shear waves in individual commercial US systems. Importantly, the diagnostic performance and reference values for different elastography techniques in discriminating fibrosis stages vary among manufacturers, and the interchangeability of devices remains controversial [8,12–17]. Thus, for a new shear wave elastography technique, an assessment of its diagnostic criteria and accuracy in liver fibrosis staging is essential.