Molecular imaging is one of the key aspects in the twenty-first century medical diagnose. A combination of biomedical engineering, biomedicine, chemistry, pharmacology and many other sciences led the way towards molecular imaging. There is no clear-cut definition for molecular imaging, but it can be considered as a non- invasive imaging method in cellular and molecular level. A cell is the primary building block of the body. As a result, there is a direct relationship between cell biology (anatomy) and molecular imaging. If the clinicians can make a clear picture at that level, they can identify the pathogenesis behind a disease of a patient. Hence, they can give the most appropriate treatment to the patient at the right time.
Purpose of Molecular Imaging
The granted purpose of molecular imaging is to observe the human body and treat the abnormalities, but with the development and the advancement of the field it spreads over many areas related to medicine. The research laboratories where animal tests take place use molecular imaging methods to come up with their final results accurately and quickly. They are used to diagnose and scope the treatment of heart diseases, cancers, brain disorders such as Alzheimer’s and Parkinson’s disease and many other diseases.
Molecular Imaging Techniques
From the beginning of 1990’s, we can identify many researches and works done related to the field of molecular imaging. In today’s world, there are many technigues used for generating molecular images. They are MRI (Magnetic Resonance Imaging), PET (Positron Emission Tomography), SPECT (Single Photon Emission Computed Tomography), CT (X-ray Computed Tomography), Ultrasound and optical methods such as ‘Optical Fluorescence Imaging’ and ‘Optical Bioluminescence Imaging’.
PET and SPECT are two methods related to nuclear medicine. CT is an advanced method developed with the same X- ray machine technique, but with the ability of making 3-D images. Ultrasound is a very cheap and non-radiographic method where the sound resonance is used to generate images. MRI uses magnetic resonance for its imaging procedure.
The optical methods can be considered as the most unheard imaging methods. There are two technologies used in optical methods. The first one is reporter technology and the other one is imaging technology. Reporter technology identifies molecular processes of the interested area. Usually these reporters are enzymes or some other proteins, which give fluorescence to the targeted area. The imaging technology is used to develop the sensitive and accurate methods for fluorescent visualization. This technology can be divided into two, i) in vivo fluorescence imaging and ii) concentrate on the emerging field of fluorescence tomography.
Advances in Molecular Imaging
Molecular imaging technology has a positively increasing slope when it is compared to other medical fields, as such new techniques and methods are introduced to the field day by day. Most of the advancements in the field deal with machineries. Activatable or smart probes are newly added to optical and MRI imaging. The contrast agents (a small molecule which can make a bond with the targeted cell area and emits rays) provide the advantage of reducing the noise that derives from signal producing. The scientists have recently introduced few other radio pharmaceuticals that have a lesser half-life which will not be affected your body in vivo imaging. They also identified some radio pharmaceuticals that will be lasting a longer period giving you the room to generate 3D images or to conduct longer period image processing. A sub-field called MBI (Molecular Breast Imaging) is being developed as a separate aspect and helpful in treating breast cancers. The optical imaging methods’ enhancement is also taking place rapidly. The fluorescence molecular tomography (FMT) was developed rapidly around in 2007 as an alternative to PET with a higher throughput. (More images in less time)
Nuclear Medicine and Molecular Imaging
When reading this article you may have come up with the question ‘What is the connection between molecular imaging and nuclear medicine?’ as there is a mentioning about nuclear medicine. PET and SPECT are the first and the most optimistic method of molecular imaging. In the other imaging methods such as MRI and ultrasound, there are always complex and high power consumption methods to generate the deepest level images. In nuclear medicine, a radio pharmaceutical (e.g., 11 C, 18 F and 64 Cu for PET; 99m Tc, 123 I and 111 In for SPECT) is inserted into the body and it spreads all over the body and emit rays that can be detected by an image receiver. These radio pharmaceuticals make contact with the primary level of the body structure (molecular level) and ease the image processing method.