Christine Jaskowiak

Pilot study using PET/CT as a novel, noninvasive assessment of disease activity in inflammatory bowel disease.

Background: A pilot study was performed investigating the possibility that positron emission tomography (PET) activity using 18‐fluorodeoxyglucose (FDG) with nearly simultaneous computerized tomography (CT) for anatomic accuracy would identify regions of active inflammation in both ulcerative colitis (UC) and Crohns disease (CD). Methods: Prospective clinical data was collected in 12 patients experiencing an exacerbation of their inflammatory bowel disease; 7 with CD and 5 with UC. A PET/CT scan (GE Discovery LS PET/CT scanner) was performed in all patients. Twenty patients undergoing PET/CT because of solitary pulmonary nodules served as controls. We graded the small bowel and 4 colon regions (ascending, transverse, descending, and rectosigmoid) with PET activity scores assigned to each region based on the amount of FDG uptake using the liver as the reference organ. Results: In UC patients, PET activity was seen in 13 of 24 (52%) regions. There was high (23 of 24; 95.8%) correlation between PET activity and disease activity as determined by colonoscopy, disease activity indices, and radiology. In patients with CD, PET activity was seen in 19 of 32 (59.4%) regions. Again, there was a high (26 of 32; 81.3%) correlation between PET activity and clinical disease activity. Of the 20 controls, significant PET activity (Grades 2 and 3) was seen in only 2 of 100 regions (2%). Conclusions: We found that PET activity correlated well with active inflammation in both UC and CD, suggesting that this may be a noninvasive method of identifying disease activity in patients with inflammatory bowel disease.

Does the Use of IV Contrast Enhanced CT for Attenuation Correction Affect Clinical Interpretation of Head and Neck PET/CT?

Purpose of Report: Evaluate the effect of IV contrast use with FDG PET/CT on clinical interpretation of PET images for head and neck cancer. Procedures: 20 consecutive patients referred for PET/CT and contrast enhanced CT of the head and neck had two sets of PET images obtained. One set used standard low dose CT for attenuation correction, and the other used IV contrast enhanced diagnostic quality CT for attenuation correction. Two blinded nuclear medicine physicians interpreted the results. Results: No statistically significant difference in clinical interpretation of the PET images was found. It was noted that PET scans attenuation corrected with IV contrast CTs had greater incidence of abnormal appearing lesions (P<0.01). Conclusion: It is reasonable to use contrast enhanced CT for attenuation correction in PET/CT of head and neck cancer. This would allow for a reduction in radiation dose delivered to patient.

Implementing Hybrid CT/PET: The University of Wisconsin Experience

Oncology Issues November/December 2006 In Brief In late 2001, the University of Wisconsin’s Radiation Oncology Department installed one of the first radiotherapy-dedicated hybrid CT/PET scanners in the country. This scanner is shared between Radiation Oncology and Nuclear Medicine. In the last five years, the technology has proven valuable for diagnostic purposes and radiotherapy treatment planning. While the CT/PET acquisition benefited our hospital and patients, implementation of the new technology was not a seamless process. The adoption of the hybrid CT/PET posed challenges to our institution and, in particular, to the Radiation Oncology and Nuclear Medicine Departments that jointly share the equipment (see box, page 27). Now, a few years after its acquisition, the CT/PET scanner plays a vital role in the functioning of both departments. This new technology has significantly altered the way we design radiation treatment plans for our cancer patients.