The additional value of CT images interpretation in the differential diagnosis of benign vs. malignant primary bone lesions with 18F-FDG-PET/CT.
OBJECTIVE
To evaluate the value of a dedicated interpretation of the CT images in the differential diagnosis of benign vs. malignant primary bone lesions with 18 fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT).


METHODS
In 50 consecutive patients (21 women, 29 men, mean age 36.9, age range 11-72) with suspected primary bone neoplasm conventional radiographs and 18F-FDG-PET/CT were performed. Differentiation of benign and malignant lesions was separately performed on conventional radiographs, PET alone (PET), and PET/CT with specific evaluation of the CT part. Histology served as the standard of reference in 46 cases, clinical, and imaging follow-up in four cases.


RESULTS
According to the standard of reference, conventional 17 lesions were benign and 33 malignant. Sensitivity, specificity, and accuracy in assessment of malignancy was 85%, 65% and 78% for conventional radiographs, 85%, 35% and 68% for PET alone and 91%, 77% and 86% for combined PET/CT. Median SUV(max) was 3.5 for benign lesions (range 1.6-8.0) and 5.7 (range 0.8-41.7) for malignant lesions. In eight patients with bone lesions with high FDG-uptake (SUV(max) >or= 2.5) dedicated CT interpretation led to the correct diagnosis of a benign lesion (three fibrous dysplasias, two osteomyelitis, one aneurysmatic bone cyst, one fibrous cortical defect, 1 phosphaturic mesenchymal tumor). In four patients with lesions with low FDG-uptake (SUV(max) < 2.5) dedicated CT interpretation led to the correct diagnosis of a malignant lesion (three chondrosarcomas and one leiomyosarcoma). Combined PET/CT was significantly more accurate in the differentiation of benign and malignant lesions than PET alone (p = .039). There was no significant difference between PET/CT and conventional radiographs (p = .625).


CONCLUSIONS
Dedicated interpretation of the CT part significantly improved the performance of FDG-PET/CT in differentiation of benign and malignant primary bone lesions compared to PET alone. PET/CT more commonly differentiated benign from malignant primary bone lesions compared with conventional radiographs, but this difference was not significant.
Strobel
K
K
Division of Nuclear Medicine, Department of Medical Radiology, University Hospital Zurich, Raemistr. 100, 8091, Zurich, Switzerland. klaus.strobel@usz.ch
Exner
U E
UE
Stumpe
K D M
KD
Hany
T F
TF
Bode
B
B
Mende
K
K
Veit-Haibach
P
P
von Schulthess
G K
GK
Hodler
Juerg
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology*; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed / Q000379:methods*
D019788:Fluorodeoxyglucose F18