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Researchers Add Functional Information to Virtual Colonography and Bronchoscopy with PET/CT
Cardinal Health Acquires Five PET Radiopharmaceutical Production Facilities

Researchers Add Functional Information to Virtual Colonography and Bronchoscopy with PET/CT

A pilot study performed at Stanford University (Stanford, Calif) demonstrated the potential diagnostic capabilities of clinicians armed with 3D reconstructions of combined PET/CT imaging, as reported by researchers in the July issue of the Journal of Nuclear Medicine.¹

Combining functional data with accurate anatomical information on potentially cancerous tumors allows visual navigation that “may be used to detect and characterize cancer, spare someone from more invasive medical procedures, lead to better disease-detection rates of colon cancer, provide surgical guidance, and detect which tumors may be easier to biopsy,” said Andrew Quon, co-author of the study and assistant professor of radiology at Stanford.

When PET’s power to detect the metabolic indications of growing cancer cells is combined with CT’s detailed anatomical information and the data is rendered in 3D, the weaknesses of both methods of imaging are curtailed, allowing radiologists to “peel away the organs, highlight tumors, and detect cancerous ‘hot spots’—providing an omnipotent perspective of the body,” according to Quon.

CT virtual bronchoscopy compared with PET/CT virtual bronchoscopy. (A, C, and E) Standard 2D PET/CT tomographs illustrating patient with highly 18F-FDG?avid malignant subcarinal/paratracheal mass that extends along right tracheal sidewall and right bronchus. (B) CT virtual bronchoscopy illustrating that tracheal sidewall and carina appear normal, without indication of large tumors that abut central airways. (D) PET/CT virtual bronchoscopy showing abnormal 18F-FDG uptake along right paratracheal wall, carina, and proximal right bronchus consistent with regions of malignant tissue that were not evident on CT virtual bronchoscopy. Images and video fly-through provided excellent preview of region before surgical bronchoscopy. t = tumor.

The study notes that 24 patients with various malignancies were studied; combined PET/CT 3D imaging was helpful in either diagnosis or preprocedural planning for eight of these participants. “We demonstrated both the feasibility of rendering PET/CT images into 3D volumes and the potential clinical utility of this technique for diagnostic lesion characterization and preprocedural planning,” the study abstract concluded.

The diagnostic value of the technique was empirically demonstrated in one case, in which a cancer lesion was revealed that had not been previously detected by PET, CT, or PET/CT imaging. According to Quon, it showed “the potential synergistic enhancement of both PET and CT when rendered into three dimensions.”

One particular condition for which combined PET/CT 3D imaging could prove especially valuable is colorectal cancer, the second-leading cause of cancer-related deaths in the United States. Invasive colon-oscopy is the current method for evaluation of colorectal cancer; PET/CT 3D imaging has the potential to replace this diagnostic standard.

The combined 3D imaging method also could prove indispensable for lung-cancer evaluation and cardiac diagnosis: “It could have exciting applications in cardiovascular imaging, providing 3D views of blood vessels and possibly identifying individuals at risk for heart disease,” Quon said.

Researchers noted that the concept had merely been proven, not validated, by the study, and that software tools would need additional development. But Quon noted that the technique showed potential for expansion to include other tracers and anatomic regions beyond the chest and colon.

—C. Vasko

Reference

1. Quon A, Napel S, Beaulieu CF, Gambhir SS. “Flying through” and “flying around” a PET/CT scan: pilot study and development of 3D integrated 18F-FDG PET/CT for virtual bronchoscopy and colonoscopy. J Nucl Med. 2006;47:1081?1087. Available at: jnm.snmjournals.org/cgi/content/abstract/47/7/1081. Accessed August 4, 2006.