Abstract— Halloysite clay Nanotubes (HNTs) are nanomaterials composed of double layered aluminosilicate minerals with a hollow tubular structure in the submicron range. They are characterized by a wide range of applications in anticancer therapy as agent delivery. In this work we aim to investigate the automatic detection features of HNTs through advanced quantitative ultrasound imaging employing different concentrations (3-5 mg/mL) at clinical conventional frequency, i.e. 7 MHz. Different tissue mimicking samples of HNT containing agarose gel were imaged through a commercially available echographic system, that was opportunely combined with ultrasound signal analysis research platform for extracting the raw ultrasound radiofrequency (RF) signals. Acquired data were stored and analyzed by means of an in-house developed algorithm based on wavelet decomposition, in order to identify the specific spectrum contribution of the HNTs and generate corresponding image mapping. Sensitivity and specificity of the HNT detection were quantified. Average specificity (94.36%) was very high with reduced dependency on HNT concentration, while sensitivity showed a proportional increase with concentration with an average of 46.78%. However, automatic detection performances are currently under investigation for further improvement taking into account image enhancement and biocompatibility issues. Index Terms — molecular imaging, cancer detection, nanoparticles, halloysite nanotubes, tissue typing, biomedical signal processing, theranostics, cell targeting, drug delivery. I. INTRODUCTION EW targeted ultrasound contrast agents (UCA) are playing a key role with the rapid development of contrast- enhanced ultrasound technology, showing good prospects for applications in molecular imaging and targeted therapy [1]. Overcoming all main limitations presented by traditional microbubble UCAs in relationship to their specific intra- vascular applications [2]-[4], novel nanoparticles allow cell This work was partially funded by the grant N° DM18604 – DD MIUR 14.5.2005 n.602 of MIUR, by FESR P.O. Apulia Region 2007-2013 – Action 1.2.4 (grant number 3Q5AX31) and by the Progetto Bandiera NANOMAX ENCODER. G. Soloperto, F. Conversano, A. Greco, and E. and S. Casciaro are with the National Research Council, Institute of Clinical Physiology 73100 Lecce, Italy. (E-mail: sergio.casciaro@cnr.it). S. Leporatti is with National Council of Research, Institute of Nanosciences, Lecce, Italy. G. Gigli and A. Lay-Ekuakille are with Department of Innovation Engineering, University of Salento, Lecce, Italy. targeting beyond capillary vasculature, such as cancer cells [5]-[8] without using expensive and health threatening ionizing techniques such as Positron Emission Tomography (PET), often used in association with MRI or CT [9], with additional radiation dose in this case, for obtaining suitable anatomical information. Echographic imaging is the most widely available medical imaging modality, owing to its inexpensiveness, safety and real-time features [10]. Nonetheless, healthy and pathologic tissues do not normally present sufficient discriminating scattering of ultrasound waves and UCA image enhancement is necessary to provide optimal contrast and enable tissue typing in ultrasonographic imaging. Additionally, novel cellular drug delivery experimental agents, including halloysite clays nanotubes (HNT), have been successfully tested on cellular and animal models. Specifically, halloysite clay is a two- layered aluminosilicate with a hollow tubular structure (50 to 70 nm in external diameter, 15 nm diameter lumen and 1 ± 0.5 μm length) and chemically similar to kaolin [11-13]. HNT is a natural product made of inexpensive materials [14] with a simple means of fabrication and selective labeling of the inner and outer surfaces. HNTs are therefore capable of entrapping and release active agents within the inner lumen, as successfully tested on various applications on both cellular and animal models [15-18]. In this article, we experimentally investigated and optimized the automatic detection features of HNTs through advanced quantitative ultrasound imaging employing different concentrations (3-5 mg/mL) and a conventional frequency (7 MHz) for future application of tissue typing through functionalized HNTs. II. MATERIALS AND METHODS A. HNT containing Tissue-mimicking Phantom Purified dehydrated HNTs were obtained from Applied Minerals, Inc. and coated with Methoxy(polyethyleneoxy) propyltrimethoxysilane. To conduct the experiments, HNTs were dispersed in tissue mimicking gel samples, whose employment in the study of signal enhancement produced by solid nanoparticles have been already reported in literature Sergio Casciaro, IEEE Member, Giulia Soloperto, Francesco Conversano, IEEE Member, Ernesto Casciaro, IEEE Member, Antonio Greco, Stefano Leporatti, Aimè Lay-Ekuakille, IEEE Senior Member, Giuseppe Gigli. Automatic Image Detection of Halloysite Clay Nanotubes as a Future Ultrasound Theranostic Agent for Tumoral Cell Targeting and Treatment N