SIEMENS

There’s one cardinal rule for cancer treatment: The battle must begin at the earliest possible moment. Unfortunately, however, the disease often goes unnoticed for far too long. At that point, the search for metastases of a malignant tumor becomes paramount in treatment planning. Indispensable here are procedures that not only generate and display cross-sectional views of organs but that also make biochemical processes visible. That’s because diseased cells reveal themselves through their altered metabolism. Tissue cells that consume an unusual amount of sugar, for example, indicate uncontrolled cell growth.

This combination of imaging capabilities (anatomical and physiological) is what make Siemens’ Biograph Molecular CT (mCT) ideal for cancer diagnostics. A whole-body scanner, Biograph combines positron emission tomography (PET) with three-dimensional computer tomography (CT) X-ray images. PET scanning measures the concentration of a slightly radioactive tracer—usually the glucose compound F-18-FDG (18F Fludeoxyglucose)—which is injected into the patient beforehand.

The radioactive tracer concentrates in those areas that metabolize it fastest—in other words, tumors. During the process of glucose metabolism F-18 decays by emitting a positron, which in turn is transformed into photons that are detected by the PET unit and converted into images. At the same time, the ring-shaped CT unit produces high-resolution 3D X-ray images of the part of the body being examined. The result is a fused image that displays the location and dimensions of tumors. “Hybrid imaging provides us with significantly better information more quickly than either method would on its own,” says radiologist Dr. Martin Freesmeyer, Chief Physician at the Clinic for Nuclear Medicine at University Hospital Jena, Germany, where a Siemens PET/CT unit entered service in mid-2009.

The Biograph not only takes measurements faster than any other system, it also sets new standards for image sharpness. Whereas conventional systems achieve PET image resolution of four to five millimeters, the Biograph mCT generates images with nearly two millimeter resolution throughout almost all of the recorded region. It achieves this thanks to four detector rings containing a total of 32,448 individual detectors that can capture changes in glucose metabolism that were previously impossible to resolve.

Patients benefit from the new system because it is fast. A routine scan takes no longer than five to ten minutes. Instead of having to undergo several X-ray examinations and a correspondingly high exposure to radiation, patients need only complete a single combined PET/CT scan in order for doctors to obtain precise, high-contrast diagnostic images.

Norbert Franke, who is responsible for Biograph sales at Siemens Healthcare in Erlangen, believes the reduction in required examinations offers a big benefit. “The combination of a better chance of recovery and fewer examinations reduces treatment costs,” he says. A total of 50 Biograph units are now in operation in Germany. “We are now also seeing a significant increase in demand for them in Asia and other European countries,” Franke reports.

Procurement costs for the devices are the main factor hindering their widespread use. A Biograph mCT can cost as much as €3 million depending on its equipment features. At the same time, however, the hybrid device lowers treatment costs by eliminating the need for multiple examinations. American and European radiologists and oncologists also believe that the use of radioactive tracers ensures efficient cancer detection.

This technology is urgently needed because 436,000 new cases of cancer are discovered in Germany each year and 211,500 people die from the disease annually, according to the German Cancer Aid Society. The World Health Organization (WHO) believes the number of cancer victims worldwide will increase by 50 percent between now and 2030 due to a rising proportion of elderly people in the global population. The most recent World Cancer Report issued by WHO predicts cancer will soon replace cardiovascular disease as the number one cause of death worldwide.

Unmasking Cancer Cells. The economy offered by a combined PET/CT procedure takes on a new dimension when viewed against the background of such alarming figures. For one thing, the success of expensive chemotherapy treatments can be monitored more effectively through molecular diagnostic techniques, and treatment measures themselves can be better planned if the cancer is detected earlier.

“Particularly in the post-treatment phase, combined PET/CT examinations are superior to all other procedures,” says Prof. Jürgen Ruhlmann from Medizin Center Bonn. That’s because radioactive tracers can immediately zero in on tumor cells. “Experimental data shows that combined PET/CT devices can detect nests of tumor cells measuring just under a millimeter,” says Ruhlmann.

This capability enables doctors to implement countermeasures early. Many studies have shown that the combination of molecular imaging and computer tomography improves the chance of survival for cancer patients. PET/CT examinations are increasingly being used to search for lung, colon, skin, lymph node, breast, and thyroid tumors, and more and more nuclear medical specialists and radiologists are beginning to utilize high-resolution images to detect other types of cancers - including prostate, bronchial and head/throat carcinomas.