Technological advance in radiology

Dr Anant S Mashankar

The science of medicine has grown by leaps and bounds in the last couple of decades. Newer medicines, antibiotics and vaccines have brought in a new era of health care. Similarly, equipment oriented branches of medicine have undergone a radical change due to introduction of computers, microprocessors and solid state devices. Amongst the various branches of medicine, radiology stands out as one to have radically revolutionised and advanced in the last few decades.

From the discovery of X-rays in 1895, radiology remained confined to the use of X-rays for diagnosis till the 60s when ultrasound was first introduced in medical diagnosis. From then on, it has been a wonderful journey of advancement, refinement of technology and invention of newer methods and it continues.

Let us have a closer look at some of the amazing modalities in radiology today.

CT scan

Touted as the invention of the century, it was invented by Sir Godfrey Hounsfield in 1973, who was awarded the Nobel prize for his invention. He introduced, for the first time, the concept of cross sectional scanning with the help of computers. His first scanner was termed as the first generation scanner and took as many as seven minutes to perform a single scan!

His invention then went through a complete metamorphosis covering as many as five generations and even more.

Today, an ultrafast spiral CT scanner is capable of performing as many as sixteen scans in half a second. CT scan has applications in almost every branch of medicine. Evaluation of paralytic stroke, head injury and cancer disease were some of the standard applications of CT scan for generations. Today, CT scan has its utility in virtually every field of medicine including coronary angiography. 3D CT, CT angiography, virtual colonoscopy, virtual bronchoscopy and brain perfusion studies are some of the latest applications of CT scan.

MRI

Unlike CT scan, MRI is based on the application of a strong magnetic field for obtaining cross sectional scans of the body. Besides having the advantage of not using ionising radiation, it also is exclusive in its ability to diagnose diseases in some areas like the white matter of the brain, spinal cord, joints and muscles. Although the principles of MRI were established as early as in the 50s, it was only in the 70s and 80s that the medical applications were developed and popularised.

The initial scanners were slow and had limited applications. The technology has developed rapidly over a period of time with the scan times reducing to about half and the applications increasing to more than double. Now MRI is capable of performing sub second scans in areas like gall bladder disease and cardiology. MR spectroscopy is highly sensitive for cancer detection.

Ultrasonography

Ultrasonography has come a long way in terms of technology. Commonly known as sonography, it works on the principle of ultrasonic waves passing through the body. The reflections or echoes are picked up by the machine to help us get cross sectional image of the body part under examination. Today’s ultrasound scanners are capable of providing such high tech facilities as 3D and 4D scans and tissue harmonic scanning.

Doppler sonography, for study of blood vessels and vascularity, is an excellent noninvasive tool for assessment of disease. More and more applications of Doppler sonography are being explored and tried in the evaluation of vascular disease, hypertension, cerebrovascular stroke, tumor disease and pregnancy.

Digital and computed radiography

Digital and Computed radiography (DR & CR) is a revolutionary development in the field of radiography. Apart from better quality radiographs, it also provides computerised archival of data. These images are flexible and can be adjusted to the best settings before being printed. These can also be stored and transported over long distances digitally for remote viewing.

Many of the hospitals in the western world have become filmless departments where all the storage and viewing of X-rays is on computers only! This is also ecofriendly as it avoids the chemistry of films and film processing. It is also beneficial to the patients as it completely avoids repetition of exposures. Teleradiology

Teleradiology is digital transportation and remote viewing of images. This has immense importance from the points of view of remote reporting, expert opinion, conferencing and academic interaction. A common platform for data storage and interaction facilitates and interaction between different modalities and equipments.

DICOM is now accepted and used as a standard platform for processing, transportation and networking of images. The new concept of teleradiology is centered on the consideration that it involves management of medical information rather than simple transmission of diagnostic images from one place to another.

Teleradiology must therefore be able to contribute to the seamless integration of the digital environment in which medical data are managed throughout the hospital and beyond, generating value added services to the patients as well as economic benefits to the institution.

Imaging material suffers from the problem of very large size. Therefore, a balance has to be struck between the degree of compression of images and transmission time. Department of Information and Technology (DOT), government of India, has laid down guidelines for maintenance of minimal standards in teleradiology.

Isotope scanning and PET

Isotope scanning stands out as the imaging modality with evaluation of the physiological function. Relatively safe and non-invasive, it has a special place in the evaluation of metastatic cancer, thyroid function, kidney and myocardial functioning.

Positron Emission Tomography (PET) is fast developing as the most promising and sensitive tool for physiological evaluation. PET scanning involves the use of pharmaceutical agents, mainly FDG (18 fluoro deoxy glucose). These are generated from a cyclotron. The method is based on increased glycolytic activity of the diseased cells, especially the cancer cells.

Glucose uptake by the cancer cells is very high as compared to that of the normal cells. A variety of PET scanners are available. However, gamma cameras are very popular as they are already in use for isotope scanning. Various clinical trials are going on all over the world to explore the usefulness of PET in various disease processes.

The writer is honorary assistant professor of radiology, K J Somaiya Medical college, Mumbai and consultant radiologist at Mandakini Imaging Centre. Email:anant_mashankar@hotmail.com