The U.S. molecular imaging market is expected to remain steady at around $1.5 billion through 2020, but the global market is projected to reach $2.2 billion, growing at a compound annual growth rate of 3.3 percent, according to a new RnRMarketResearch report. Part of the reason U.S. PET/CT sales have been stagnant for the past couple of years have to do with hospitals’ quest to cut costs. “Customers are more conscientious of pricing,” says Robert Brait, PET national product manager for Siemens Healthcare. “When evaluating to spend a couple of million dollars on a piece of equipment, health care organizations will also have to evaluate patient volumes and how they can best treat their patient community.”

As a result, many communities, especially the smaller ones, are sharing one PET/CT scanner in a cancer center. There has also been a resurgence in mobile PET/CT, mostly in rural communities, in an effort to service a large demographic area with one mobile system. But despite flat sales, PET/CT, as well as SPECT, SPECT/CT and PET/MRI have undergone a lot of technological advancement in recent years. Quantification is now the standard for PET/CT imaging and it’s starting to gain interest in SPECT/CT imaging. Meanwhile PET/MRI is beginning to be used for clinical applications.

The changing face of PET/CT
In the past, CT was the only modality used for radiation therapy planning (RTP) but there is now a growing interest in using PET/CT instead. “By adding PET to the CT scan you combine the anatomic detail of a premium CT with precise metabolic information of PET to detect, characterize and monitor even the smallest cancer lesion with reproducible quantification to support more cost-effective treatment,” says Brait.

He adds that CT will only show cancer activity once the tissue has been damaged, which could be two years after it had started to form, whereas PET shows activity at the cellular level before tissue damage even occurs. Dr. Mark Winkler of Steinberg Diagnostic Magnetic Imaging in Nevada is using his recently purchased Toshiba America Medical Systems Celesteion PET/CT for RTP. “For the first time we have a way to do treatment planning not only with the anatomic landmarks of CT but with the physiological information provided by the PET,” he says.

The system, which received FDA approval in November, utilizes an 88 centimeter PET bore that makes it ideal for the range of positions that RTP requires. Patients can be scanned with their arms over their head or with their breast down, hanging freely, if they have breast cancer.

The large bore is also patient-friendly, which is more important than ever in this new health care environment that places the patient at the center of care. “These people are sick — for the most part they either have cancer or are suffering from some form of dementia, so a more pleasant scanning environment with a very, very wide bore versus a conventional narrow bore PET/CT is very useful,” says Winkler.

It’s all about quantification now
“The major trend that we have seen over the last five years, and is going to be here for more years [to come], is that we are moving from typical, staging oncology examinations for PET/CT to treatment monitoring,” says Xavier Tarrade, global PET/CT product marketing manager at GE Healthcare.

The biggest advancement in PET/CT in the past couple of years is quantification. Whether it’s used for oncology, cardiology or neurology, it has now become the standard. “We are entering the phase where it’s not about just the image quality — it’s about getting quantitative information that is specific to each individual patient,” says Kirill Shalyaev, general manager of advanced molecular imaging at Philips Healthcare. “It’s a stepping stone toward personalized medicine.”

With quantification, physicians can now measure the standard uptake value (SUV) to determine if treatment is working. It’s particularly useful for oncology because if the SUV value goes down after the patient undergoes treatment, then the treatment is working. But if the value stays the same or increases, then the radiation oncologist or chemotherapist can switch to a more effective therapy.

For cardiology, quantification can determine which vessels are the most occluded so the physician knows which one to perform angioplasty on. For neurology, if the frontal or temporal lobes are not picking up the biomarker, then the patient may be developing Alzheimer’s disease.

“At this point you can’t treat Alzheimer’s disease but the SUV values in the brain show the beginning stages of Alzheimer’s disease or the amount of amyloid plaque, so the patient can be given medication to improve the quality of their life with the time they have remaining,” says Siemens’ Brait.

Quantification is also gaining a lot of interest in the SPECT and SPECT/CT fields as well. At last year’s Society of Nuclear Medicine and Molecular Imaging annual meeting, GE introduced its Discovery NM/CT 670 Pro SPECT/CT system, which features a set of new qualitative tools.

GE’s Q.Suite technology includes two analysis and reporting applications to simplify organ definition and activity calculations. The Q.Metrix application measures and reports SUV values and the Q.AC application is an image reconstruction algorithm that improves the accuracy of SPECT attenuation correction so that quantitative measurements can be obtained at very low doses. Siemens also brought quantification to SPECT/CT with the introduction of its Symbia Intevo SPECT/CT system in 2013. It features a technology called xSPECT that uses the CT as a frame of reference rather than conventional SPECT/CT imaging, which uses SPECT.

“In the past, it was very limited and challenging to be able to perform quantification on SPECT,” says Fritz Winderl, national product manager for SPECT/CT at Siemens. “With [other] SPECT/CT technology, accurate and routine use of quantifiable information is not possible since the inherent misalignment of SPECT and CT during reconstruction prevents the extraction and integration of critical CT information into the SPECT image data.”

But Siemens’ xSPECT technology solves that issue. It includes xSPECT Bone, which reconstructs the SPECT/CT images with high resolution bone detail, and xSPECT Quant, which utilizes a quantitative control method to produce accurate and reproducible quantitative measurements.

In with the new and out with the old
In November, Siemens introduced its Symbia Evo Excel SPECT system, a compact system which can fit into a room as small as 11 feet 8 inches by 15 feet. Many facilities today are looking to replace their 20-plus year-old systems and Siemens specifically targets the Evo Excel for that market.

“There are a lot of older SPECT cameras out there that are installed in small rooms due to the footprint of the system,” says Winderl. “In order to upgrade the system, oftentimes the newer systems require a larger room, but that is a barrier as often facilities do not have sufficient space or budget to expand the size of the room to install new equipment.”

The SPECT and SPECT/CT market is larger than the PET, PET/CT and PET/MRI markets since the systems have been around longer, are cheaper and are commonly used for many different indications, according to the RnRMarketResearch report. However, physicians believe that more and more SPECT procedures will be replaced by PET procedures. Philips’ Shalyaev believes that there might be some cannibalization in certain areas but that SPECT is here to stay. “SPECT has a solid role — if you look at molecular imaging, SPECT is relatively low-cost and the radiopharmaceuticals are ubiquitous and have much higher half lives,” he says.

From research tool to clinical modality
When PET/MRI was first introduced, it was solely a research modality, but recently it has been making its way into the clinical setting. The last five of Siemens’ Biograph mMR installations have been clinical installations.

“The interest in PET/MRI continues to grow,” says Abram Voorhees, product manager for the Biograph mMR at Siemens. “The early questions about the technology have now been answered by research published that shows equivalent diagnostic PET performance from PET/MRI as compared to PET/CT, and clinical workflows now demonstrate that one can image in such a way that brings the benefit of time savings to the patient.”

There is strong adoption in the large academic centers but Siemens has also installed systems at Zwanger-Pesiri Radiology in New York, the Golisano Children’s Hospital at the University of Rochester in New York and the Hoag Memorial Hospital Presbyterian in California.

“Even though we will see continued adoption in the academic medical centers, I think this signals that in the right market, it will have a place,” says Voorhees. In late November, GE received FDA clearance for its SIGNA PET/MR, which is now the second simultaneous PET/MRI on the market today. Previously, GE offered what it called its “trimodality solution,” in which the patient is transferred on a detachable table from the Discovery PET/CT 690 to the Discovery MR 750 in order to acquire the PET/MRI image.

But two separate systems occupy a lot of space, which is a critical element in a hospital, and the trimodality solution requires two or three separate exams. Because of those drawbacks, GE decided to develop the simultaneous solution. GE has currently sold 22 systems and 10 of them have already been delivered. The majority of the sites are academic institutions but it have also started deliveries in facilities that are not exclusively academic. Philips offers its Ingenuity TF PET/MR, which utilizes a separate PET scanner and MRI scanner on different ends of the patient table. Philips is not currently working on developing a simultaneous solution.

A few years ago, Philips anticipated that there would be significant growth in the PET/MRI sector but it is now noticing that no major developments are emerging and that the overall market is not showing much interest. “What the clinical community is struggling with is the cost of the equipment and the cost to maintain it,” says Shalyaev. “It’s relatively low throughput, not the same that you would get on an individual standalone machine.”

The doctor’s opinion
Dr. Winkler says that he is not interested in ever purchasing a PET/MRI. If he needs an MRI to complement a PET/CT then he would perform an MRI exam and then fuse the PET data later.

“The problem with a PET/MRI scanner is that it’s insanely expensive so it’s very hard to justify it in an environment where the dollars that you spend have to relate to outcomes in a positive way,” he says. He believes that you have to compromise the design of the MRI and the PET scanners in order to have a PET/MRI. “These are both technologies that are evolving — if you’re marrying a PET to an MRI, you’re acquiring a very expensive device and then you’re limiting the ability to improve or advance both the MRI and the PET devices over time.”
Stanford University in California has a GE SIGNA PET/MR for oncological research but the university will be installing another system in the fall for clinical applications. Initially it will be used for neurological cases such as studies for Alzheimer’s and dementia, radiation necrosis and evaluation of recurrent brain tumors.

Dr. Greg Zaharchuk, associate professor of radiology at the university, is particularly excited about the potential PET/MRI has to reduce radiation dose. “One of the nice things about the GE scanner is that we have been finding that in addition to having no radiation from the actual MRI portion of the exam, the detectors are more sensitive than any other detectors that have been available and so we can actually reduce the dose of radiotracer,” he says.

Zaharchuk doesn’t think it would make sense for a hospital that conducts mostly oncological exams to purchase a PET/MRI, but he thinks a hospital that conducts a lot of neurology exams would benefit from it. “Neurology, head and neck and pelvic imaging is where MRI really shines,” he says. “I think those places will be where PET/MRI is going to really show a competitive advantage over PET/CT.”

Personalizing medicine with PET/MRI
Siemens’ Voorhees believes that PET/MRI will gain a lot of interest in the next five to 10 years. “I see PET/MRI emerging and taking more of a mainstream place in the market, and sitting side by side with PET,” he says.

One area that he thinks PET/MRI will have significant value is in personalized medicine. The hope is that PET/MRI can be used to better visualize the disease, guide biopsies and identify the patient’s specific cancer phenotype as well as to select the most appropriate treatment and then measure the response to that personalized therapy.

“Cancer is often heterogeneous, whether it’s at the site of the primary tumor or in metastatic disease,” says Voorhees. “The key to personalized medicine is understanding the exact disease phenotype and then tailoring the treatment accordingly for the patient.”

Jason Lewis, president of the World Molecular Imaging Society, vice chair for research and chief of radiochemistry and imaging sciences service at Memorial Sloan Kettering Cancer Center, also believes that molecular imaging is going to play a big role in personalized medicine. “I truly believe that precision medicine is only going to be possible with molecular imaging because it’s going to give you the ability to diagnose diseases in early stages, interrogate heterogeneity of a disease and monitor therapy,” he says. “That can only be done on a patient-by-patient basis with non-invasive imaging. The biopsy is going to take a small sample of something very heterogeneous.”

Lewis is also excited about a few new technologies in development. He’s particularly interested in hyperpolarized MRI, a new technology that creates MRI contrast agents with increased signal intensity, and a technique called Raman spectroscopy that detects unique photons that interact with certain atomic bonds in molecules. “I think they are going to complement each other to give the diagnostic or therapeutic answer you want in a disease,” he says.