Characterization of Insufficiency Fracture and Bone Metastasis After Radiotherapy in Patients With Cervical Cancer Detected by Bone Scan: Role of Magnetic Resonance Imaging

Abstract

Background: Insufficiency fracture (IF) can show increased uptake on a bone scan (BS). IFs are often misinterpreted as bone metastases if the characteristic “Honda sign” (H-sign) is invisible. The purpose of the present study was to evaluate the utility of magnetic resonance imaging (MRI) alone for the characterization of IF and bone metastasis after radiotherapy in patients with cervical cancer detected by BS. Materials and Methods: Our study included 40 patients with cervical cancer after radiotherapy that showed pelvic emerging increased uptake on a BS during follow-up. Then further MRI examination was performed in all patients. Two radiologists independently reviewed the MR images, and the sensitivity, specificity and accuracy were calculated based on the mean scores. Diagnostic validity of the inter-observer was calculated by using kappa statistics. The gold standard was based on radiologic findings, clinical data and follow-up at least 12 months. Results: A total of 57 emerging bone lesions detected at BS were identified in the reference standard, including 43 IFs and 14 bone metastases. Only 20 patients showed a “H-sign” on the BS images. Using MRI analysis, all lesions detected by BS were found in MRI by both radiologists. On average, the sensitivity, specificity, and accuracy for distinguishing IFs from bone metastases were 95.3% (41/43), 92.8% (13/14), and 94.7% (54/57), respectively. The inter-observer variability was determined to be very good (kappa value = 0.962). Conclusions: MRI is a reliable diagnostic technique for the further characterization of emerging lesions detected by BS, MRI shows great diagnostic efficiency in the differentiation of IF and bone metastasis.

Differentiation of Cervical Spine Osteoradionecrosis and Bone Metastasis After Radiotherapy Detected by Bone Scan in Patients With Nasopharyngeal Carcinoma: Role of Magnetic Resonance Imaging

“…Meanwhile, 38.6% of ORNs and 19.4% of metastases that were not detected on BS were found on MRI, and the frequency of equivocal lesions was also reduced. These results were similar to those of several previous studies that assessed the added value of MRI or SPECT/CT to BS alone in the discrimination of RT-induced pelvic insufficiency fracture and pelvic metastasis in cervical cancer patients (13)(14)(15)22). Therefore, the results of our study indicated that MRI could be a noninvasive technique for further discrimination of new cervical spine lesions detected by BS.…”

“…BS shows enough sensitivity for detecting metastasis, but it shows several limitations in specificity because many benign bone tumors, infections, and degenerative disease may also show abnormal radiotracer uptake (13,15,16,22). Recently, BS has been applied for detecting RT-induced bone complications and has shown variable sensitivity in the detection of insufficiency fractures after RT for pelvic malignancy, with a detection rate ranging from 40 to 87.5% (14,15,23). In this study, BS showed a detection sensitivity of 61.4% for detecting ORN.…”

“…Bone scan (BS) is considered as a sensitive enough technique for the detection of bone marrow diseases and has been widely applied for monitoring bone metastasis in patients with a malignancy (13). However, BS has a limitation in terms of specificity, because RT-induced bone complications, acute osteoporotic fractures, and the metastases may all result in increased uptake (14)(15)(16). MRI is quite sensitive for the detection of reactive marrow edema and fatty changes, and very helpful for the detection of soft-tissue masses.…”

“…MRI is quite sensitive for the detection of reactive marrow edema and fatty changes, and very helpful for the detection of soft-tissue masses. MRI has been proven to be valuable for distinguishing benign and malignant compression spinal fractures (17,18), and differentiating RT-induced insufficiency fractures from metastases (14). However, few studies have assessed the MRI findings of ORN (10)(11)(12), and the role of MRI in the distinction of cervical spine ORN and metastasis remains unknown.…”

Sacral insufficiency fracture following rectal cancer treatment – case report

“…Plain radiographs are not recommended as they can delay diagnosis due to difficulties caused by image interpretation [7]. Radiotherapy-induced IF and bone metastasis show an increased uptake on a bone scintigraphy after radiotherapy' but the typical 'H' sign of IF does not always appear, which can be misinterpreted as bone metastasis [8]; therefore, bone scintigraphy should not be the first choice.…”