Manson et al. Egyptian Journal of Radiology and Nuclear Medicine (2020) 51:208 Egyptian Journal of Radiology https://doi.org/10.1186/s43055-020-00315-x and Nuclear Medicine REVIEW Open Access Integrating image fusion with nanoparticle contrast agents for diagnosis: a review Eric Naab Manson1* , Francis Hasford1,2, Stephen Inkoom1,3 and Ahmed Mohammed Gedel1,4 Abstract Background: As newer technologies in the field of medical imaging continue to expand, development of unique techniques for optimizing image quality and minimizing radiation dose becomes very necessary for improve diagnosis of pathologies and patient safety. Different types of medical imaging devices have been developed for specific diagnostic purposes. Main text: This article provides a brief overview on the need for co-registration of some medical images into a single image (image fusion), advantages of some nanoparticle contrast agents in medical imaging, and a discussion of present and future role of integrating image fusion with nanoparticle contrast agents in diagnosis. Conclusion: The use of nanoparticle contrast agents together with image fusion is a promising technique in future medical imaging as is likely to reveal pathologies of ≤ 1 nm sizes. Keywords: Medical imaging, Nanoparticles, Image fusion Background Also, each of these individual imaging modalities have Today, medical imaging plays an important role in diagno- unique strength and limitations in regards to spatial sis and prognosis of pathologies. The first modern tech- resolution, image contrast, signal-to-noise ratio, and sen- nology to have evolved from medical imaging was X-ray sitivity. The various imaging modalities do complement imaging. However, the rapid advancement of the technol- each other. For instance, in nuclear medicine imaging, ogy led to the development of modern clinical technolo- PET often shows abnormalities with high contrast and gies that are employed worldwide in hospitals/clinics for insufficient anatomic detail which limits the identifica- diagnosis and therapy. These include ultrasound (US), tion of organ or tissue with the lesion. In addition to nu- magnetic resonance imaging (MRI), computed tomog- clear medicine imaging, the attenuation by patient of the raphy (CT), single-photon emission computed tomog- emitted radiation in SPECT reduces the anatomic detail raphy (SPECT), and positron emission tomography (PET) required in the image. These abnormalities could be cor- [1]. These imaging modalities use different approaches for rected by combining the nuclear medicine imaging sys- important analysis and provide different information on tem (SPECT or PET) with other imaging systems such the human body for diagnosis. For example, CT scans as CT, MRI, or ultrasound. provide information on the body structure, MRI scans One major technique that has been employed to over- provide detailed information on the tissue types and PET come these limitations and improve image quality is provides functional information on the anatomy being image fusion. Image fusion is to combine two or more examined. images from different imaging modalities of the same scene into a single image without distracting (changing) the required and relevant features from each of the ori- * Correspondence: [email protected] ginal images [2]. Recent advances in medical imaging 1Department of Medical Physics, School of Nuclear and Allied Sciences, from fusion of images from different imaging modalities University of Ghana, Accra, Ghana have proven to significantly improve diagnostics and Full list of author information is available at the end of the article © The Author(s). 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. Manson et al. Egyptian Journal of Radiology and Nuclear Medicine (2020) 51:208 Page 2 of 11 monitoring disease progression. Image fusion is very reducing their accumulation in potential endangered useful for evaluating patients receiving cancer care in healthy tissues. Today, the most widely and frequently the areas of diagnosis, staging, treatment planning, mon- used nanoparticle therapeutic agents are Doxil, Ambi- itoring the response to therapy in addition to disease some, and Abraxane. Efforts are being made toward the progression [3]. Image fusion from diagnostic imaging development of newer nanoparticle contrast agents for modalities such as CT or MRI provides a good definition diagnosis purpose to be incorporated fully into the clin- of anatomy which removes the anatomic localization of ical environment [5]. Figure 1 illustrates specification of the abnormalities and correction of the emission images some new nanoparticles that are frequently used for for attenuation. diagnostic and therapeutic applications. Another technique that has also been employed to im- The aim of this review is to provide a brief overview prove image quality is through the use of nanoparticle on the need for co-registration of some medical images, contrast agents. Nanoparticle contrast agents are able to followed by the use of nanoparticle contrast agents and enhance images produced from these imaging modalities image fusion for diagnosis. Finally, the review provides a by highlighting specific diseases or features between two discussion on possible future benefits in medical imaging tissues within the anatomy under consideration. Current world through the integration of image fusion and nano- research in molecular imaging is working toward provid- particle contrast agents as a unique imaging technique ing new opportunities for biomedical imaging with great for diagnosis of diseases. promise for the development of unique imaging agents at the nano scale. These nano agents have unique op- Medical imaging modalities tical, magnetic, and chemical properties which permit Basically, there are four common groups of medical im- their use in the creation of imaging probes with better aging technologies. These are magnetic resonance (for contrast enhancement, increased sensitivity, controlled MRI systems), X-ray transmissions (for CT and planar biodistribution, better spatial resolution, and temporal X-ray systems), radiation emissions (for SPECT and PET information, multifunctional and multimodal imaging systems), and acoustic or light reflections (for US sys- across imaging techniques such as MRI, SPECT, PET, tems) [6]. Figure 2a-g below shows image acquisition and ultrasound. Recently, nanoparticle contrast agents processes of these imaging equipments. The MRI uses a based on polymers, proteins, lipids, metals and silica, strong magnet and radiofrequency signals which polar- carbon nanotubes, selenium-cadmium nanocrystals, and izes and excite hydrogen nuclei within the abundant microbubbles are the most recommended nanoparticles water molecules and fat in human tissue to produce a for diagnostic and theranostic purpose [4]. detectable signal which are reconstructed with the aid of Many different nanoparticles have been developed and a computer program to produce an image of the soft tis- evaluated over the years. Soon after the development of sues. Magnetic resonance technology is considered safe nanoparticles, systems such as polymers, liposomes, pro- and non-invasive because it uses non-ionizing radiation teins, dendrimers, and micelles were basically used to [12]. On the other hand, CT is mostly used in bone im- deliver chemotherapy drugs to pathologic sites while aging without contrast agents. For lung, vascular and Fig. 1 Specification of some nanoparticles frequently used for diagnostic and therapeutic purposes [5] Manson et al. Egyptian Journal of Radiology and Nuclear Medicine (2020) 51:208 Page 3 of 11 Fig. 2 a MRI imaging system. b Alignment of protons without magnetic field. c Alignment of protons with magnetic field [7, 8]. d Shows the image acquisition of the SPECT system, where the gamma camera rotates about the patient to acquire a projection image at each angle. e With the PET imaging system, the patient is located within a ring of detectors and the positron annihilation emits two gamma photons in opposite direction which are picked up by two detectors [9]. f CT imaging system [10]. g Ultrasound imaging system [11] Manson et al. Egyptian Journal of Radiology and Nuclear Medicine (2020) 51:208 Page 4 of 11 Lately, image registration and fusion procedures have been made easier through the use of software tool kits. Examples of these tool kits include Insight segmentation and registration toolkit (ITK), Elastix, Advanced Normalization Tools (ANTs), NiftyReg, Medical Image Processing, Analysis, and Visualization (MIPAV), Med- ical Image Processing, Analysis, and Visualization (MIPAV), and OsiriX [16]. Image registration The purpose of image registration is to compare or inte- grate data sets between