Medical imaging (MI) is a step forward in modern medicine that encompasses different imaging techniques and processes to image the human body for diagnosis and treatment. It plays an important role in initiatives to improve public health through various radiological imaging techniques such as:
Magnetic resonance imaging (MRI)
Medical ultrasonography or ultrasound (US)
Medical photography and nuclear medicine imaging
Diagnostic Medical Imaging
Diagnosis helps in identifying a specific disease or illness by examining the patient thoroughly. Most diseases affect the body where it can’t be seen with the naked eye. Thus, Diagnostic medical imaging assists in diagnosis by aiding us through visual representation of any abnormalities that exist within the body. E.g., MI captures the bones of a body and helps the physicians to determine if they are broken or dislocated.
How does Medical Imaging work?
Medical Imaging plays a vital role in the healthcare industry allowing physicians to make accurate diagnoses and treatment decisions. A world without medical imaging is hard to imagine where every diagnosis and treatment becomes slower and is difficult to achieve. It works as invisible waves that typically originates from one side of the body, travels through the region of interest and hits a detector on the other side of the body. These waves can be electromagnetic radiation, magnetic fields, or sound waves that are absorbed by the body’s tissues at varying degrees. The detector then develops an image composed of their shadows that are directly captured through a detecting camera.
Apart from the medical diagnosis and treatment, they are used in various applications such as
Spot Diagnosis – The image diagnoses the specific regions of our body. E.g.: Radiographs and CT scans help detect fractures, tumours, cysts, and anomalies of the bone.
Treatment Planning – Determines the size of a lesion and decide on the surgery. Virtual surgeries can be performed through medical imaging technology, either directly in the software, or after importing and creating stereolithographic models.
Disease Progression – Determines the disease stage and progression by using CT or MRI scans and PET scans to detect metastases, SPECT for scanning bones. Monitoring disease progression plays a crucial role in Parkinson’s disease.
Efficacy of Treatment – The PET Scans of cancer patients under treatment aids the physicians to check how effective the treatment is in reducing the size of the tumour. Further, surgeons use MI to align bones and implants during a surgical procedure.
Technologies and Applications
Every imaging technology comprises unique attributes with specific limitations. Based on the limitations, radiologists conclude on a required imaging technique.
Ultrasound uses sound waves to create medical images. It is considered to be one of the safest methods of diagnostic medical imaging. The sound waves travel through an ultrasound probe with a conducting gel into the body. The waves then hit the anatomical structures of the body which are captured and transformed into images that can be viewed on a monitor.
Radiographs are the earliest form of medical imaging. They are used to visualize bones and determine the root cause of an illness. Mammography is a screening tool to detect breast cancer. Fluoroscopy is a combination of radiographs and a contrast agent that can either be injected or swallowed. The contrast agent is followed by the radiographs and determines the obstructions, ulcers and other disorders.
The patient lies in the CT chamber containing both the detector and the source in the opposite directions. It travels in an arc around the patient and obtains images sequentially with millimetres apart. The three different axes – coronal, axial and sagittal creates a three-dimensional image. Though CT scans are better than traditional radiographs, it delivers a higher dose of radiation to the body.
Magnetic Resonance Imaging
MRI Scans uses radio waves within a magnetic field. Since the human body consists of a huge amount of water, the hydrogen ions within the water molecules align themselves based on the field. Once the radiofrequency is applied, the ions return to their original positions which are recorded and generated into an image. An MRI scan can visualize soft tissues such as muscles, joint spaces and tendons. MRIs can be a risk factor for people having metal implants such as artificial joints and pacemakers due to their strong magnetic field.
Nuclear Medicine Imaging
Nuclear Medicine Imaging uses radioactive molecules known as “tracers”. They are either injected or swallowed into the bloodstream that is absorbed by specific tissues. The tracers emit gamma rays that are captured and converted into digitized images. Based on the region of interest the tracers are absorbed, eg: Thyroid cells absorb radioactive iodine to scan the thyroid gland, technetium, gallium or indium for bone scanning, etc… The positron emission tomography (PET) uses a radioactive form of glucose absorbed by cancer cells that are high in metabolism. It helps in determining the distant metastases in cancer patients
Future of AI in Medical Imaging
As medical imaging advances in healthcare, diagnosis and treatment planning will see a parallel trend on the rise. The recent muse will be the implementation of AI in medical imaging. They can identify slices of interest from hundreds of images, detect finer abnormalities, retrieve old records, and conduct a large-scale medical screening that can be integrated and interfaced with other digital health applications.