How has the field of molecular imaging developed so far?
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KN Sudhir
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The availability of cutting-edge innovations has led to phenomenal growth and widespread acceptance of molecular imaging over the last few years. For instance, in oncology in nearly four out of ten cases, physicians changed their intended patient management due to molecular imaging. (Source: Hillner BE, Siegel BA, Shields AF, Liu D, Gareen IF, Hanna L, Hartson Stine S, Coleman RE. The Impact of Positron Emission Tomography (PET) on Expected Management during cancer treatment. Findings of the National Oncologic PET Registry. Cancer 2009; 115:410-418. PMID: 19016303). This additional diagnostic information has made molecular imaging integral to diagnosis (find disease), staging (characterise disease) and treatment monitoring (follow disease) of cancer. Moreover, molecular imaging has taken on a similar essential role in cardiology and neurology. The field of molecular imaging has come a long way since its inception—making it, in the last years, one of the fastest growing imaging procedures worldwide.
What are the major operational issues being faced by research organisations in this field?
In researching how to diagnose and treat the most challenging diseases, such as cancer, coronary artery disease and dementia, molecular imaging is one of the most important quantitative imaging tests. With conventional PET/CT technology, quantification of imaging biomarker uptake is already possible, but there can be inaccuracies and significant, unknown variances in image measurements that create an operational issue for longitudinal studies and correspondingly research organisations. With today’s SPECT/CT, inherent limitations in conventional technology have even prevented SPECT from producing quantitative measurements of a tracer’s uptake at all. To help researchers make sound decisions, imaging, therefore, must not only be quantifiable—it must also be accurate, reproducible and consistent.
Two additional challenging operational issues facing research organisations today are the dual requirements to improve patient safety, especially for repeating studies and the increase in productivity when, for instance, the instrumentation is shared with daily clinical use. Unfortunately, conventional PET/CT or SPECT/CT systems often require researchers to choose between protecting patients through lower dose and enhancing productivity through faster scans.
How does molecular imaging improve the performance of research organisations?
A primary goal of research organisations is to deliver solutions that will produce definitive and timely answers to clinical questions. And, in today’s increasingly competitive and rapidly changing healthcare environment, these answers must also be provided in the safest and most efficient way possible. The ability to find these answers sooner than traditional anatomical modalities has made nuclear medicine a cornerstone of diagnostic imaging. Additionally, the ability of both PET and now SPECT to provide quantitative results can provide researchers more confidence in their evaluation of patients.
Which are the areas in healthcare research that can benefit from molecular imaging?
The future of molecular imaging will be strongly linked with, for instance, oncology and therapy planning. As population ages, the frequency of cancers will increase and our ability to image the biology and physiology of a patient is critical to being able to understand, diagnose and stage the disease, but even more critically, to plan and monitor patient therapy. For neurology, new tracers that allow the visualisation and quantification of amyloid plaque deposition in the brain will support physicians in diagnosing and monitoring neurodegenerative diseases. And for cardiology, the development of new tracers labelled with 18F will make PET more accessible to assess myocardial perfusion.
How do you see innovation in molecular imaging impacting radiology worldwide and in India?
Innovations in molecular imaging help radiologists see the functional part of the organ rather than the physiology. For example, any change in the tumour that can be seen by a CT or MRI after six months can be seen by the PET/CT much earlier. This enables the physician to detect and diagnose certain diseases earlier. Due to this, we find many radiologists planning to acquire nuclear medicine equipment, especially PET/CT. With the advent of newer imaging biomarkers, the utility of PET/CT is no longer limited to detection and staging of cancer alone; there are newer applications in neurology and cardiology as well. All these developments are seen with a keen interest in India.
Which area of radiology do you see increased scope for molecular imaging?
Since the first system was released, PET/CT has played an important role in oncology, and this role will continue to expand in not only detecting the disease, but also in monitoring therapies and treatment. PET imaging is already considered the gold standard for staging and monitoring several cancer types, and the increasing availability of new radio-pharmaceuticals will help increase its footprint. Neurology has also been an area of focus for PET, especially in light of the new PET tracers available to measure amyloid plaque build-up in the brain, providing additional information to physicians evaluating patients for Alzheimer’s disease and other causes of cognitive decline. In cardiology, PET is already used to evaluate myocardial tissue viability with FDG, and is a very powerful tool to assess myocardial perfusion, although not very common due to the very short half-life of specific isotopes for this application. However, developments on new tracers labelled with 18F- will make the distribution easier and may increase the utilisation of PET in cardiology.
SPECT has long been noted for its high sensitivity, and is regarded as one of the key systems to allow early response assessment, which is of vital importance to radiologists.
Tell us about Siemens’ Biograph mCT Flow & Symbia Intevo?
With the new Biograph mCT Flow, Siemens found a way to overcome the limitations of conventional PET/CT. So far, PET exams were done in sequential segments, called bed positions. With Biograph mCT Flow’s FlowMotion technology, the patient bed moves continuously inside the gantry and allows anatomy-based planning. That means each exam is planned based on that specific patient’s anatomy, so physicians can plan their exams to get more information where it is really important for that patient, for example, scanning for more time on the head, utilising motion correction in the chest and acquiring the legs at a higher speed, in one single exam protocol.
Now, with Symbia Intevo, the world’s first xSPECT system, physicians have the potential to not only image disease, but also leverage the high resolution to see the unseen and more confidently interpret images. Moreover, Symbia Intevo’s unique quantitative capabilities may provide the ability to monitor and adjust treatments earlier by accurately measuring even small differences. XSPECT hardware and software technology enables higher image contrast, and more precise lesion characterisation provides physicians additional support in distinguishing between degenerative disease and cancer. This facilitates physician decision making and potentially minimises the need for costly CT, MR or biopsy follow-ups. To supplement this outstanding improvement in image quality, xSPECT reconstruction is also the world’s first quantitative technology.
By offering accurate and reproducible quantification, it may support physicians’ ability to more confidently interpret clinical images, enabling early modification of patient treatment to reduce costs associated with ineffective therapies.