PET-CT & Oncology: Hitting Stride

Applications of PET-CT are expanding as is the technology's ability to improve patient care (and often at less overall cost). Educating other specialties about the impact and appropriate role of PET-CT is a priority today as is surmounting somewhat complicated reimbursement. IT is the missing link that is proving to be a challenge with many PET-CT scanners not yet talking to PACS.

PET-CT is proving its might in oncology. Approved indications have expanded from the original cache - lung, colon, esophageal and metastatic breast cancer and lymphoma - to include others such as locally advanced breast cancer, cervical, endometrial and ovarian cancer. The hybrid technology is improving patient care, facilitating more accurate staging to allow clinicians to more appropriately treat cancer. At the same time, studies show that PET-CT does save money in the long run by avoiding futile surgeries and determining whether or not a patient is responding to chemotherapy.

Later this year, the Centers for Medicare and Medicaid Services (CMS) will launch the PET Registry. Participating institutions can scan any patient with a biopsy-proven cancer. The national data collection effort will hopefully demonstrate the utility of PET and lead to an open approval for PET, similar to CT, says Medhat Osman, MD, PhD, director of PET at St. Louis University (St. Louis, Mo.).

Despite all of the positives, PET-CT faces some challenges. Reimbursement remains sticky; CMS and private payors have not yet adopted standard processes. Training of radiologists and nuclear medicine physicians also is a work-in-progress. Although oncologists have made great strides in understanding PET technology, educating referring physicians about functional imaging remains a priority, says Peter Conti, MD, PhD, president of Society for Nuclear Medicine. IT is another hurdle. Communication and integration between PET-CT scanners and other imaging and IT equipment can be problematic, and DICOM for nuclear medicine is undeveloped.

Flexing its muscles

"PET-CT offers the best of both worlds by acquiring both anatomical and functional information nearly simultaneously," poses Osman, who uses Philips Medical Systems 16-slice Gemini PET-CT for oncology imaging. PET and CT images complement each other, providing a more comprehensive picture of the extent of disease in many types of cancer. As PET-CT demonstrates its utility, PET centers have added multiple new indications such as locally advanced breast, ovarian, endometrial and cervical cancer.

"PET-CT with FDG can really help improve diagnostic and staging capabilities [for Medicaid-approved indications]. In about 30 to 40 percent of cases, PET-CT with FDG adds information that really alters patient treatment," explains Ronald Korn, MD, director of nuclear medicine and PET-CT imaging for Scottsdale Medical Imaging (Scottsdale, Ariz.). Korn has relied on GE Healthcare's Discovery LS PET-CT scanner as a functional go-to modality for three years.

A classic example of a treatment plan altered by a PET-CT scan is the advanced lung cancer patient. The current data suggest that the best treatment for advanced lung cancer (Stage III disease) is chemotherapy and radiation therapy followed by surgery. Conventional anatomic imaging has limited utility for staging lung cancer patients, but PET-CT has great sensitivity in deciding who should be a surgical candidate and who would be better served with chemotherapy and radiation first. Indeed PET-CT can alter staging in up to 30 percent of the patients and provide additional information in about 40 percent of patients compared to conventional imaging. If after therapy, a follow up PET-CT shows response to treatment then a patient can proceed to surgery. If the follow-up PET-CT scan shows little improvement then the oncologist can resort to second line drugs or palliative care.

Similarly, PET-CT can provide information to help clinicians determine the best treatment regimen for patients with locally advanced breast cancer. The nuclear medicine division at New York University School of Medicine in New York City, which relies on a Siemens Medical Solutions biograph 6 PET-CT scanner, now sees breast cancer patients earlier in the disease process, says Elissa Kramer, MD, director of the division of nuclear medicine. Kramer explains, "When a patient presents with locally advanced breast cancer, it's important to know the extent of disease, and when a patient is treated with adjunctive chemotherapy, oncologists need to know if it's working or if they are losing ground." PET-CT answers these questions. It also can determine when the malignancy is treated so that the patient can proceed to surgery for completion of therapy. Consequently, earlier referrals of breast cancer patients are on the upswing.

Oncologists are turning to PET-CT for more extensive use in other types of cancer, too. "There is a parallel with lymphoma. Initially, PET-CT was used for initial staging and follow-up after chemotherapy. Now, patients are referred earlier if there is a suspected recurrence and three to six months after chemotherapy," says Kramer.

Another shift in the clinical landscape is using PET-CT to assess a patient's response to chemotherapy. "A newer, very promising aspect of PET is using a scan to determine whether or not a patient is responding to chemotherapy. Some experts advocate a PET-CT scan after one cycle of chemotherapy, especially with lymphoma," notes Osman.

Reimbursement: The ongoing issue

Despite the clinical and economic promise of hybrid scans, reimbursement is not yet a given. "Until now, patients with certain types of cancer have been denied access to PET-CT because PET does not have blanket approval from CMS," says Osman. The PET Registry could improve the situation and lead to open coverage for all oncology indications; however, CMS' plans for the data gathered through the registry are unclear.

The other reimbursement quandary centers around payment, coding and billing on both the Medicare and private front, says Conti. Currently, CMS recommends an initial CT scan, which can be followed by a PET scan if results are inconclusive. "That's not realistic or how we practice medicine with hybrid scanners," says Conti. Nevertheless, centers may not be paid for the CT portion of a PET-CT scan because the practice doesn't adhere to the CMS fine print. The solution is education, sums Conti. Educating CMS and private payors about the clinical and efficiency benefits of hybrid scanning should yield positive results.

Education & training

"One of the biggest challenges is educating other specialties about the impact and appropriate role of PET-CT," says Korn. PET-CT can be overutilized by clinicians who don't understand its role. For example, a clinician may believe PET-CT can play a screening role and refer a patient with mildly enlarged lymph nodes for a PET scan. PET can not tell if the nodes are malignant; it is better used as a diagnostic tool, says Korn.

Overutilization is not the only clinical education concern. Kramer of NYU points out clinicians may not understand how powerful PET is and need to understand what it can do. Kramer employs a multi-faceted approach to educating her colleagues, relying on literature, lectures and one-on-one discussions to educate her peers about the utility of PET-CT. "One-on-one conversations in context with a physician are definitely the most convincing form of education," she states.

Training radiologists and nuclear medicine physicians is another challenge. "With [fairly] favorable reimbursement many entrepreneurs have oversaturated the market," explains Korn. PET is an expensive technology, and facilities need a certain number of cases to support the investment. Eighteen PET centers operate in Arizona, but many are low volume. Furthermore, some are operated by physicians with minimal formal training who may not grasp the limitations and nuances of the technology.
The training issue is on the national radar. The Journal of Nuclear Medicine and American College of Radiology recently published a white paper outlining an approach to reading and training. "These are recommendations, not guidelines, but it's a good starting point," notes Conti. The Society of Nuclear Medicine aims to take the process to the next level and prepare guidelines for hybrid technology imaging later this year.

IT hurdles at a glance

IT presents another challenge. "Initially, PET-CT was a storage challenge as far as archiving and transferring the scans to PACS. This has become less of a challenge with the arrival of multislice CT scanners. PET-CT storage requirements pale in comparison to multislice CT storage requirements," says Korn. Still storage can be a dilemma with head to toe PET-CT studies ranging up to 0.5 gigabytes in size. "That takes a lot of space on an optical disk. We can store only a few PET-CT studies on one optical disk," Osman relates.

PET-CT image distribution and transfer is far from seamless. Most centers rely on a variety of means to share images: hard copies, CDs and emailed images. Kramer states, "Eventually we hope to put snapshots on PACS, but right now we can't do it because the PET-CT workstation doesn't talk to PACS." Similarly, at St. Louis University, the nuclear medicine department cannot transfer PET-CT images to its cyber knife. Instead, each modality must be transferred separately with software fusing images at the knife. "This defeats the whole point of PET-CT," states Osman. DICOM can help these types of integration challenges, admits Osman. DICOM also will facilitate multi-center trials and clinical care as well, adds Conti. "Current DICOM tags may be sufficient to allow appropriate display of PET-CT images," notes Jerold W. Wallis, MD, associate professor of radiology at Mallinckrodt Institute of Radiology at Washington University School of Medicine (St. Louis) and past chair of the Society of Nuclear Medicine DICOM working group. The real hitch, users claim, is convincing vendors to recognize DICOM's clinical value and incorporate it into their solutions.

PET moves into the future

"PET is a great technology for probing the molecular biology of tumors," relates Korn. As drug companies develop agents designed to target specific molecules of cancer, PET could provide the means to determine if the agent is working and the tumor has stopped growing. New tracers like fluoro-18 fluorocholine and C11-methionine could have a tremendous impact if they are approved by the FDA, says Korn. New tracers could detect metabolism and protein proliferation and synthesis, enabling clinicians to determine if a therapy is working earlier than currently possible. "We won't have to wait an entire chemotherapy cycle to see if it is working," predicts Korn.

Conclusion

PET-CT has demonstrated its merit in oncology imaging. Its clinical utility is increasing across the spectrum; hybrid scans are useful in more types of cancers, earlier in the disease process and as an integral component of follow up care.
The combination scanner is not yet a mature modality. Reimbursement, education and training are still works in progress. And IT remains challenging with the absence of a DICOM nuclear medicine standard, which is needed to quell integration and communications woes. Despite the growing pains, PET-CT promises to be a positive force in the oncology arena.

Sidebar

Choosing the Right PET-CT Scanner
Since hybrid PET-CT scanners first burst onto the market four years ago, vendors have launched multiple new devices. All are variations on the same theme. PET-CT scanners are available in CT slice counts ranging from two to 64 and with bismuth germanium oxide (BGO) and lutetium oxyorthosilicate (LSO) PET crystal configurations.

"The right PET-CT scanner for any given site is not a one-size-fits-all decision. It depends on the technology currently in place, applications and budget. A center can purchase a device to fit its immediate needs or one that it can grow into over time," explains Peter Conti, MD, president of the Society for Nuclear Medicine. Conti says two-, four- and six-slice CT scanners are more than adequate for routine staging of cancer. But if site protocols are highly sophisticated and include coronary artery or vascular imaging, a 16- or 64-slice CT element may be warranted. Another reason for purchasing a higher slice CT scanner is the multifunctional PET-CT option. That is, a facility that needs an additional CT scanner may turn to a PET-CT scanner for hybrid imaging in the mornings and devote the afternoon schedule to standalone CT work - thus maximizing the utility of the scanner.

LSO is a relatively new PET crystal configuration that provides slightly faster image acquisition than BGO configurations, which may have advantages if the facility uses shorter-life isotopes like rubidium-82. Faster PET acquisition can aid throughput, but throughput has not yet reached a critical point at most PET centers.

As a facility makes its purchase decision, it's important to weigh price, features, clinical needs and the current imaging inventory. A thorough analysis will help put PET-CT buyers on the path to a successful implementation.