Respiratory gated PET/CT of the liver: A novel method and its impact on the detection of colorectal liver metastases.

PURPOSE: To evaluate the diagnostic performance of a new method for respiratory gated positron emission tomography (rgPET/CT) for colorectal liver metastases (CRLM), secondly, to assess its additional value to standard PET/CT (PET/CT).

MATERIALS AND

METHODS

Forty-three patients scheduled for resection of suspected CRLM were prospectively included from September 2011 to January 2013. None of the patients had previously undergone treatment for their CRLM. All patients underwent PET/CT and rgPET/CT in the same session. For rgPET/CT an in-house developed electronic circuit was used which displayed a color-coded countdown for the patient. The patients held their breath according to the countdown and only the data from the inspiration breath-hold period was used for image reconstruction. Two independent and blinded readers evaluated both PET/CT and rgPET/CT separately. The reference standard was histopathological confirmation for 73 out of 131 CRLM and follow-up otherwise.

RESULTS

Reference standard identified 131 CRLM in 39/43 patients. Nine patients accounted for 25 mucinous CRLM. The overall per-lesion sensitivity for detection of CRLM was for PET/CT 60.0%, for rgPET/CT 63.1%, and for standard+rgPET/CT 67.7%, respectively. Standard+rgPET/CT was overall significantly more sensitive for CRLM compared to PET/CT (p=0.002) and rgPET/CT (p=0.031). The overall positive predictive value (PPV) for detection of CRLM was for PET/CT 97.5%, for rgPET/CT 95.3%, and for standard+rgPET/CT 93.6%, respectively.

CONCLUSION

Combination of PET/CT and rgPET/CT improved the sensitivity significantly for CRLM. However, high patient compliance is mandatory to achieve optimal performance and further improvements are needed to overcome these limitations. The diagnostic performance of the evaluated new method for rgPET/CT was comparable to earlier reported technically more complex and expensive methods.