Diagnosis of Insufficiency Fracture After Radiotherapy in Patients With Cervical Cancer: Contribution of Technetium Tc99m -Labeled Methylene Diphosphonate Single-Photon Emission Computed Tomography/Computed Tomography

Background: Insufficiency fractures (IFs) are a type of stress fracture caused by the effects of normal or physiological stresses on abnormally weakened bone. Frequently, these fractures are occult, and a portion of these fractures is misdiagnosed as bone metastases on a whole-body bone scan (WBS). The aim of this study was to evaluate a potential benefit of single-photon emission computed tomography/computed tomography (SPECT/CT) with metabolic and morphological imaging to diagnose IF in patients with cervical cancer after radiotherapy. Methods: This article presents a retrospective review of 35 patients with cervical cancer after radiotherapy in patients (females; mean age, 55.94 +/- 8.75 years; range, 36-73 years) who were referred to have WBS to determine whether there was any bone metastasis. The criterion standard was based on radiological investigations, clinical information, and follow-up at a minimum of 12 months. Results: Insufficiency fractures were most frequently observed in the sacrum, accounting for 52.5% (21/40) of lesions. Fracture lines or sclerotic lines were noted in the IF lesion in 19 of 40 lesions on CT, and osteosclerosis was seen in 31 of 40 lesions. On WBS analysis, the sensitivity for detected lesions was 87.5% (42/48) for WBS. Nineteen lesions were interpreted as benign, 6 lesions were malignant, and 21 (43.8%) lesions were equivocal. Based on the criterion standard, WBS had an accuracy of only 47.9% (23/48). On SPECT/CT analysis, all of the lesions were observed on SPECT/CT; only 3 (6.25%) of 48 lesions were equivocal, and the accuracy was 89.6% (43/48). Conclusions: Single-photon emission computed tomography/computed tomography should be included in the differential diagnoses when lesions show elevated technetium Tc 99m-labeled methylene diphosphonate uptake on WBS. Compared with a WBS alone, a more accurate diagnosis of IF can be obtained using SPECT/CT, which resulted not only in fewer equivocal lesions but also in a higher diagnostic accuracy.