Early warning

Engineeering expertise has improved medical imaging for the delivery of more effective treatments even before symptoms become apparent, says Jean-Luc Vanderheyden

Medical imaging, perhaps more than any other facet of diagnostic technology, has made huge strides in offering physicians a window on the structural and functional pathology associated with a variety of diseases.

The leap from X-rays to computed tomography (CT), magnetic resonance imaging (MRI) then to more recent generations of imaging technology, including positron emission technology (PET) and single-photon emission computed tomography (SPECT), has provided non-invasive methods for diagnosing disease and assessing the effectiveness of treatment. These methods enable real-time visualisation of tissue composition and function and yield greatly improved imaging specificity for diagnostic applications.

The next generation of imaging technology is emerging from advanced engineering and software applications that are enhancing the sensitivity of medical imaging and helping physicians detect and define the scope of disease even before symptoms appear, when the disease is most treatable.

Using these new techniques, often in tandem with new molecular imaging agents that ‘light up’ diseased cells, physicians can harness the advances in sensitivity to pinpoint the delivery of targeted treatments, maximising their therapeutic and curative potential and minimising their effects on surrounding, healthy tissue.

Newer imaging techniques such as CT, PET, and SPECT provide exceptional resolution and high-definition views of body tissues. They can detect very small tumours, for example, or small defects in cardiac tissue that could, if left untreated, precipitate a heart attack. Yet these early-stage lesions will often go undetected because normal body motion associated with breathing and the beating of the heart can obscure such small anomalies.

GE Healthcare’s Motion Free technology applies engineering expertise to address this problem. Motion Free PET/CT and SPECT imaging incorporates cardiac and respiratory tracking techniques and advanced algorithms that enable visualisation, quantification, and reconstruction of the effects of normal heart and lung or diaphragm motion on the movement of surrounding tissues.

In oncology, where the aim is to detect tumours when they are small, eliminating blurring effects can improve the sensitivity of the scan. This has important implications for improving the treatment of cancer as well.

Radiation therapy aims to deliver the highest possible dose of radiation to the lesion without damaging nearby healthy cells. Targeting the radiation beam to the tumour and keeping it focused on the lesion is critical. In a patient with a 1-2 cm diameter tumour who breathes normally during radiation therapy, the tumour mass may move as much as 2-3 cm in all directions.

A conventional approach might aim the radiation beam at an area larger than the lesion to take into account tumour movement. Motion Free technology can be used during therapy to guide the radiation therapy, helping it track the movement of the lesion and stay focused on the target tissue. This technique can spare vital organs such as the bowel or the spinal cord, for example, and allow the delivery of higher, more effective doses.

In cardiology, conventional technology for imaging the heart to assess the adequacy of blood flow often cannot detect small myocardial defects due to artifacts caused by the movement of the beating heart. The ability to pinpoint these small defects, even before they cause symptoms, could enable physicians to identify patients at risk of a heart attack.

Another problem in imaging the heart is the creation of ‘false positives’ associated with the motion, leading to the physician ‘seeing’ a defect which in reality does not exist. As in respiratory tracking, Motion Free technology used in concert with PET/CT or SPECT imaging is contributing to the management of this disease, and in some cases avoiding unnecessary treatment.

Whether in oncology, cardiology, or many other areas of medicine, cutting-edge imaging techniques to pinpoint diseased cells in the body, combined with state-of-the-art engineering, are contributing to important advances in healthcare delivery. As minimally invasive approaches to diagnosis and treatment become increasingly popular, tools able to pinpoint target tissues and account for changes in their size and location are adding value across medical disciplines.

The development of these new techniques requires strong interdisciplinary teams drawn from specialisms such as engineering, software, biology and chemistry. Ultimately, these engineered solutions to medical imaging challenges will promote earlier disease detection and more powerful, safer treatments.

Jean-Luc Vanderheyden is leader of molecular imaging at GE Healthcare