PET/CT Spreads Its Wings to Monitor Cancer Therapy

Twitter icon
Facebook icon
LinkedIn icon
e-mail icon
Google icon
These PET/CT images of a patient’s chest with esophageal cancer, taken on the Philips Medical Systems Time of Flight system, demonstrate areas of increased uptake along the esophagus.

PET/CT is flexing its muscle in oncology imaging. Evidence of the hybrid scanner’s power is evident to anyone in the market for a standalone PET system—major vendors no longer market dedicated PET scanners. Combining CT’s anatomic imaging capabilities with PET’s metabolic detection provides a formidable resource for detecting, staging and restaging cancer as well as following up to manage patients effectively.

Hybrid PET/CT systems are making strides on several fronts. For starters, some sites are improving and accelerating patient care and trimming costs with sequential imaging. Others are taking advantage of the National Oncology PET Registry; the registry broadens oncology applications beyond those initially approved by the Centers for Medicare & Medicaid Services (CMS) and reimburses registered sites for such exams.

While PET/CT is a known powerhorse for diagnosing, staging and restaging cancer, the systems also show promise for monitoring a tumor’s response to therapy, which could lead to better patient care as its provides physicians with data needed to refine treatment based on each patient’s particular response to treatment.

Despite the clinical advances, IT continues to vex PET/CT. Image management is not quite geared to the specific needs of the hybrid modality. Upcoming PACS could better handle PET/CT images. Training is another can of worms as both interpreting physicians and technologists require a solid grounding in CT and PET. Finally, the three-to-five-year outlook remains very bright as researchers explore new radiotracers and radio-labeled antibodies.

The carefully honed enterprise

Diagnostic PET/CT Center of Chattanooga in Chattanooga, Tenn., is a sequential imaging PET/CT pioneer. Senior Staff Radiologist Joe Busch, MD, has used sequential imaging since 2004. The technique is simple and yields significant gains in efficiency and patient care. Instead of performing an attenuation CT scan followed by a PET scan, sequential imaging acquires a diagnostic CT followed by a PET study in one shot. It optimizes the CT component by using the CT to its potential rather than limiting its role to attenuation correction. The approach is more cost-effective and efficient than fusing separately acquired scans, says Busch, as it requires only a single room and one tech. Plus, the sequential technique produces more data and is easier on patients. “The patient undergoes one visit, one venipuncture and one radiation exposure. The scan is complete in 15 minutes,” says Busch, who uses Siemens Medical Solutions biograph 6 and biograph 16 PET/CT systems to complete about eight PET/CT scans daily. The approach benefits radiologists and nuclear medicine physicians as well as the interpreter who reviews both scans simultaneously—a workflow improvement over fusing separate images. What’s more, PET/CT can accelerate patient care. For example, a newly diagnosed colorectal cancer patient can be completely staged within one day of a PET/CT study with the exception of rectal staging via transrectal ultrasound.

PET/CT is a clinical boon in other cases as well. “It can be extremely helpful in staging lymph node pathology, enhancing pleural plaques and carcinomas of the head and neck or breast,” Busch says. In fact, local oncologists refer all head and neck cases to Diagnostic PET/CT Center of Chattanooga because they realize the capabilities of its equipment. “We use Siemens’ high-resolution techniques and IV contrast media to discern positive lymph nodes smaller than eight millimeters, which is critical in head and neck cancers,” explains Busch.

The integrated approach

Tacoma Radiology Associates in Tacoma, Wash., is a relative newcomer to the PET/CT arena. For the last several years, the practice focused on hybrid fusion via software to produce integrated imaging reports that incorporated not only PET and CT, but also MR and lab results. “We wanted to wait for a true advance in PET design before investing in PET/CT,” says Anthony Larhs, MD, director of nuclear medicine and clinical PET. Late last year, the practice invested in Philips Medical Systems Time of Flight PET/CT scanner. The hybrid system improves localization of information of interest, particularly as the patient’s girth increases; Time of Flight compensates for increased girth to produce