Restaging of patients with lymphoma. Comparison of low dose CT (20 mAs) with contrast enhanced diagnostic CT in combined [18F]-FDG PET/CT.
OBJECTIVE
Assessment of the clinical benefit of i.v. contrast enhanced diagnostic CT (CE-CT) compared to low dose CT with 20 mAs (LD-CT) without contrast medium in combined [(18)F]-FDG PET/CT examinations in restaging of patients with lymphoma.


METHODS
45 patients with non-Hodgkin lymphoma (n=35) and Hodgkin's disease (n=10) were included into this study. PET, LD-CT and CE-CT were analyzed separately as well as side-by-side. Lymphoma involvement was evaluated separately for seven regions. Indeterminate diagnoses were accepted whenever there was a discrepancy between PET and CT findings. Results for combined reading were calculated by rating indeterminate diagnoses according the suggestions of either CT or PET. Each patient had a clinical follow-up evaluation for >6 months.


RESULTS
Region-based evaluation suggested a sensitivity/specificity of 66/93% for LD-CT, 87%/91% for CE-CT, 95%/96% for PET, 94%/99% for PET/LD-CT and 96%/99% for PET/CE-CT. The data for PET/CT were obtained by rating indeterminate results according to the suggestions of PET, which turned out to be superior to CT. Lymphoma staging was changed in two patients using PET/CE-CT as compared to PET/LD-CT.


CONCLUSIONS
Overall, there was no significant difference between PET/LD-CT and PET/CE-CT. However, PET/CE-CT yielded a more precise lesion delineation than PET/LD-CT. This was due to the improved image quality of CE-CT and might lead to a more accurate investigation of lymphoma.
la Fougère
C
C
Department of Nuclear Medicine, Ludwig-Maximilians-University, Munich, Germany. christian.lafougere@med.uni-muenchen.de
Pfluger
T
T
Schneider
V
V
Hacker
M
M
Bröckel
N
N
Morhard
D
D
Hundt
W
W
Bartenstein
P
P
Becker
C
C
Tiling
R
R
D001012:Aorta, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology; D004307:Dose-Response Relationship, Radiation; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008223:Lymphoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D008228:Lymphoma, Non-Hodgkin / Q000000981:diagnostic imaging / Q000473:pathology; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18