Integrated PET/CT in differentiated thyroid cancer: diagnostic accuracy and impact on patient management.
The aim of this study was to investigate the diagnostic accuracy and impact on patient management of the new integrated PET/CT modality in patients with suspected iodine-negative, differentiated thyroid carcinoma (DTC).


METHODS
Forty patients with DTC and a suggestion of iodine-negative tumor tissue underwent PET/CT examination (370 MBq (18)F-FDG, coregistered PET/CT whole-body images). As the first step of analysis, PET and CT images were scored blindly and independently by 2 nuclear medicine physicians and 2 radiologists. A 5-point scale was used. The second step consisted of a consensus reading, during which a virtual side-by-side fusion of PET and CT images was initially evaluated and afterward the "real" fusion (i.e., coregistered) PET/CT images were also scored with the same 5-point scale. The imaging results were compared with histopathologic findings and the course of disease during further follow-up examinations.


RESULTS
One hundred twenty-seven lesions in 40 patients were evaluated. Diagnostic accuracy was 93% and 78% for PET/CT and PET, respectively (P = 0.049, per-patient analysis). In 17 (74%) of 23 patients with suspicious (18)F-FDG foci, integrated PET/CT added relevant information to the side-by-side interpretation of PET and CT images by precisely localizing the lesion(s). In tumor-positive PET patients, PET/CT fusion by coregistration led to a change of therapy in 10 (48%) patients. Futile surgery was prevented in an additional 3 patients.


CONCLUSIONS
Integrated PET/CT is able to improve diagnostic accuracy in a therapeutically relevant way in patients with iodine-negative DTC. By precisely localizing tumor tissue, image fusion by integrated PET/CT is clearly superior to side-by-side interpretation of PET and CT images.
Palmedo
Holger
H
Department of Nuclear Medicine, University Hospital of Bonn, 53127 Bonn, Germany. holger.palmedo@ukb.uni-bonn.de
Bucerius
Jan
J
Joe
Alexius
A
Strunk
Holger
H
Hortling
Niclas
N
Meyka
Susanne
S
Roedel
Roland
R
Wolff
Martin
M
Wardelmann
Eva
E
Biersack
Hans-Juergen
HJ
Jaeger
Ursula
U
D018263:Adenocarcinoma, Follicular / Q000000981:diagnostic imaging / Q000473:pathology; D000231:Adenocarcinoma, Papillary / Q000000981:diagnostic imaging / Q000473:pathology; D018249:Adenoma, Oxyphilic / Q000000981:diagnostic imaging / Q000473:pathology; D000328:Adult; D000368:Aged; D019468:Disease Management; D004351:Drug Resistance; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D049268:Positron-Emission Tomography / Q000379:methods; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D013954:Thyroglobulin / Q000097:blood; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging
D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D013954:Thyroglobulin