Bone Windows for Distinguishing Malignant from Benign Primary Bone Tumors on FDG PET/CT.
Bottom Line: Results.CT-BW demonstrated higher specificity than PET-only and PET/CT-BW (p=0.0005 and p=0.0103, respectively) and trended toward higher sensitivity than CT-STW (p=0.0759).Conclusion.
Affiliation: 1. Department of Diagnostic Radiology.
Objective. The default window setting on PET/CT workstations is soft tissue. This study investigates whether bone windowing and hybrid FDG PET/CT can help differentiate between malignant and benign primary bone tumors. Materials and methods. A database review included 98 patients with malignant (n=64) or benign primary bone (n=34) tumors. The reference standard was biopsy for malignancies and biopsy or >1 year imaging follow-up of benign tumors. Three radiologists and/or nuclear medicine physicians blinded to diagnosis and other imaging viewed the lesions on CT with bone windows (CT-BW) without and then with PET (PET/CT-BW), and separate PET-only images for malignancy or benignity. Three weeks later the tumors were viewed on CT with soft tissue windows (CT-STW) without and then with PET (PET/CT-STW). Results. Mean sensitivity and specificity for identifying malignancies included: CT-BW: 96%, 90%; CT-STW: 90%, 90%; PET/CT-BW: 95%, 85%, PET/CT-STW: 95%, 86% and PET-only: 96%, 75%, respectively. CT-BW demonstrated higher specificity than PET-only and PET/CT-BW (p=0.0005 and p=0.0103, respectively) and trended toward higher sensitivity than CT-STW (p=0.0759). Malignant primary bone tumors were more avid than benign lesions overall (p<0.0001) but the avidity of benign aggressive lesions (giant cell tumors and Langerhans Cell Histiocytosis) trended higher than the malignancies (p=0.08). Conclusion. Bone windows provided high specificity for distinguishing between malignant and benign primary bone tumors and are recommended when viewing FDG PET/CT.
No MeSH data available.
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Mentions: Specificity for the detection of primary bone tumors was significantly high with CT-BW when compared to PET/CT-BW (p=0.0103). This suggests that the fine bony detail that is visible with CT-BW is useful for distinguishing benign from malignant lesions, and that this bony detail may be obscured by FDG uptake. Specificity was also higher with CT-BW than with PET-only (p=0.0005), indicating that the anatomic data provided by the bone windows was more useful for identifying the lesions than FDG-uptake alone (Fig. 2). Sensitivity for detecting malignancy trended higher with CT-BW than CT-STW (p=0.0759, Fig 3 A and D). The margins of primary bone tumors are an important indicator of their biological potential 24-25. Malignancies are more likely to produce a greater degree of osteolysis than benign lesions 24-25. Soft tissue windows may over-emphasize tumor margins and spuriously make cortical or trabecular bone appear intact. Bone windows can reveal the osteolysis that is obscured by the soft tissue window setting (Fig. 4).
No MeSH data available.