A. M. Watson1, C. M. Jones1, E. G. Davis1, M. Eng1, R. M. Cannon1, P. Philips1 1University Of Louisville,Department Of Surgery,Louisville, KY, USA
Introduction:
Acute cellular rejection (ACR) following organ transplantation continues to be a major problem in solid organ transplantation. ACR following organ transplantation is associated with activation of T-cells, which have increased glucose uptake and utilization. This physiologic activity could be utilized for detection of ACR. This study was designed to evaluate the effectiveness of 18[F] Fluoro-2- Deoxyglucose Positron Emission Tomography (FDG PET) in detecting acute rejection in the clinical setting.
Methods:
FDG-PET studies were performed on 88 orthotopic liver transplant patients (41 men, 47 women; mean age 51 +/- 6 years) at 7 and 17 days post-operatively (1st PET and 2nd PET respectively). Additional studies was performed if patients had suspicion of rejection and at resolution of rejection (3rd PET and 4th PET respectively). The FDG-PET images were matched to 107 non-transplant patients (52 +/- 20 years), which served as controls. The controls underwent 2 FDG-PET studies during the same time intervals (1st PET and 2nd PET). A circular region of interest (ROI) was placed over the liver for semi-quantitative evaluation of FDG-PET images by means of standard uptake values (SUVs).
Results:
There was no significant difference between the SUV of the baseline FDG-PET studies (1st & 2nd PET) post-transplant versus the SUV obtained in non-transplanted patients. The mean SUVs normalized for body weight in post-orthotopic liver transplant patients measured 1.93 +/- 0.5 (p = 0.122); the mean SUVs for non-transplant patients were 2.10 +/- 0.6 (p = 0.210). Eighteen of 88 patients in our study (20.5%) had histologically proven ACR during a 30 +/- 11 day follow-up. There was no significant difference between the SUV values of 1st PET among non-rejecters vs. rejecters (mean 2.05; SD 0.46, median 2.19; IQR 1.75, 2.34 vs. mean 1.82, SD 0.40; median 1.77, IQR 1.76, 2.13. p value=0.127). Within the rejection cohort, the SUVs from the 3rd PET (rejection) were higher compared to the 1st PET (baseline). The mean SUVs of the 3rd PET measured 2.41 (SD 0.48; median 2.5, IQR 2.14, 2.74) compared to the baseline 1st PET mean SUV of 1.82 (SD 0.41; median 1.77, IQR 1.76, 2.13) and this difference was statistically significant (p<0.001).
Conclusion:
To date the role of FDG-PET in the diagnosis of ACR has not been evaluated. Semi-quantitative analysis using SUV showed a statistically significant increase between baseline and rejection FDG-PET studies. Additional prospective validation studies are essential to define the role of FDG-PET scan as an early marker for acute cellular rejection.
