The value of 99mTc-methylene diphosphonate single photon emission computed tomography/computed tomography in diagnosis of fibrous dysplasia

Craniofacial fibrous dysplasia: A review of current literature

INTRODUCTION

Fibrous dysplasia (FD) is a rare genetic disease, in which normal bone is replaced by fibro-osseus tissue. Disease severity varies greatly from single monostotic lesions to widespread polyostotic disease. Craniofacial lesions are common and, due to the complex anatomy, can cause several disabling symptoms and local extra-skeletal complications. Since relatively rare, reported cases of craniofacial FD (CFD), specifically, are few and the appropriate management remains incompletely defined.

METHODOLOGY

We performed a systematic literature review following the PRISMA guidelines for articles considering CFD in the years 2010-2023. The search was conducted in the PubMed and OVID Medline libraries. Altogether 193 articles were retrieved and reviewed.

RESULTS

Overall, the clinical presentation of CFD is highly variable depending on site and extent of lesion, with pain, deformity or impairment of function being most common. Diagnoses are often incidental and primarily based on CT imaging, while more extensive imaging, genetic studies and lesion biopsies are reserved for unclear cases. Asymptomatic patients are suitable for observation, while symptomatic or widespread disease may require more active approach with medical or surgical treatment. Follow-up is encouraged in all patients to observe possible lesion reactivation, late-stage complications and, though rarely, malignant transformation. Management should be individually tailored with a multidisciplinary team and wholesome consideration of individual needs.

CONCLUSIONS

This review provides an updated discussion on craniofacial FD with focus on improved understanding of disease pathophysiology, appropriate line of surgical management, and new potential means of medical treatment.

Machine learning based on SPECT/CT to differentiate bone metastasis and benign bone lesions in lung malignancy patients

BACKGROUND

Bone metastasis is a common event in lung cancer progression. Early diagnosis of lung malignant tumor with bone metastasis is crucial for selecting effective treatment strategies. However, 14.3% of patients are still difficult to diagnose after SPECT/CT examination.

PURPOSE

Machine learning analysis of [99mTc]-methylene diphosphate (99mTc-MDP) SPECT/CT scans to distinguish bone metastases from benign bone lesions in patients with lung cancer.

METHODS

One hundred forty-one patients (69 with bone metastases and 72 with benign bone lesions) were randomly assigned to the training group or testing group in a 7:3 ratio. Lesions were manually delineated using ITK-SNAP, and 944 radiomics features were extracted from SPECT and CT images. The least absolute shrinkage and selection operator (LASSO) regression was used to select the radiomics features in the training set, and the single/bimodal radiomics models were established based on support vector machine (SVM). To further optimize the model, the best bimodal radiomics features were combined with clinical features to establish an integrated Radiomics-clinical model. The diagnostic performance of models was evaluated using receiver operating characteristic (ROC) curve and confusion matrix, and performance differences between models were evaluated using the Delong test.

RESULTS

The optimal radiomics model comprised of structural modality (CT) and metabolic modality (SPECT), with an area under curve (AUC) of 0.919 and 0.907 for the training and testing set, respectively. The integrated model, which combined SPECT, CT, and two clinical features, exhibited satisfactory differentiation in the training and testing set, with AUC of 0.939 and 0.925, respectively.

CONCLUSIONS

The machine learning can effectively differentiate between bone metastases and benign bone lesions. The Radiomics-clinical integrated model demonstrated the best performance.

Multimodal imaging diagnosis for bone fibrous dysplasia malignant transformation: A case report

Fibrous dysplasia of bone (FDB) is a rare benign condition in which fibrous tissue replaces normal bone architecture. FDB rarely undergoes malignant transformation, but there are reports of locally aggressive fibrous dysplasia with cortical destruction and soft tissue extension. Diagnosis of FDB malignant transformation is not easy, especially in monostotic form, because of the overlap in imaging features of locally aggressive fibrous dysplasia and fibrous dysplasia with malignant transformation. The present case study reports a rare case of FDB in a 23-year-old man with polyostotic fibrous dysplasia arising in the left side of the pelvis and lower limb bones with partial transformation to fibrosarcoma. This study explored the multimodal imaging features of FDB malignant transformation, to achieve early detection and improve diagnostic accuracy of local FDB aggressiveness and its malignant transformation.

Single-Photon Emission Computed Tomography/Computed Tomography Image-Based Radiomics for Discriminating Vertebral Bone Metastases From Benign Bone Lesions in Patients With Tumors

Purpose: The purpose of this study was to investigate the feasibility of Single-Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) image-based radiomics in differentiating bone metastases from benign bone lesions in patients with tumors. Methods: A total of 192 lesions from 132 patients (134 in the training group, 58 in the validation group) diagnosed with vertebral bone metastases or benign bone lesions were enrolled. All images were evaluated and diagnosed independently by two physicians with more than 20 years of diagnostic experience for qualitative classification, the images were imported into MaZda software in Bitmap (BMP) format for feature extraction. All radiomics features were selected by least absolute shrinkage and selection operator (LASSO) regression and 10-fold cross-validation algorithms after the process of normalization and correlation analysis. Based on these selected features, two models were established: The CT model and SPECT model (radiomics features were derived from CT and SPECT images, respectively). In addition, a combination model (ComModel) combined CT and SPECT features was developed in order to better evaluate the predictive performance of radiomics models. Subsequently, the diagnostic performance between each model was separately evaluated by a confusion matrix. Results: There were 12, 13, and 18 features contained within the CT, SPECT, and ComModel, respectively. The constructed radiomics models based on SPECT/CT images to discriminate between bone metastases and benign bone lesions not only had high diagnostic efficacy in the training group (AUC of 0.894, 0.914, 0.951 for CT model, SPECT model, and ComModel, respectively), but also performed well in the validation group (AUC; 0.844, 0.871, 0.926). The AUC value of the human experts was 0.849 and 0.839 in the training and validation groups, respectively. Furthermore, both SPECT model and ComModel show higher classification performance than human experts in the training group (P = 0.021 and P = 0.001, respectively) and the validation group (P = 0.037 and P = 0.007, respectively). All models showed better diagnostic accuracy than human experts in the training group and the validation group. Conclusion: Radiomics derived from SPECT/CT images could effectively discriminate between bone metastases and benign bone lesions. This technique may be a new non-invasive way to help prevent unnecessary delays in diagnosis and a potential contribution in disease staging and treatment planning.

Characterization of Solitary Lesions in the Extremities on Whole-Body Bone Scan in Patients With Known Cancer: Contribution of Single-Photon Emission Computed Tomography/Computed Tomography

Background: Solitary lesions in the extremities showing ^99mTc-methylene diphosphate (MDP) uptake are often encountered on whole-body bone scan (WBS), and proper interpretation of this diagnostic method is important for patients with known cancer. The purpose of this study was to summarize the characteristics of solitary lesions in the extremities of patients with known cancer and to evaluate the diagnostic accuracy of single-photon emission computed tomography/computed tomography (SPECT/CT) in differentiating bone metastases from benign bone lesions.

Methods: This study was a retrospective review of 86 patients (54 males and 32 females; mean age, 57.88 ± 10.97 years; range, 31–81 years) with known cancer who underwent WBS and showed solitary lesions with ^99mTc-MDP uptake in the extremities and then underwent SPECT/CT for further diagnosis. SPECT/CT images were independently interpreted by two experienced nuclear medicine physicians. The diagnostic accuracy of SPECT/CT in differentiating malignant from benign solitary lesions in the extremities was evaluated. Inter-reviewer agreement was assessed by using weighted k statistics. The standard diagnostic criterion was based on biopsy or radiologic follow-up over at least 12 months.

Results: In total, 23 bone metastases and 63 (73.26%) benign lesions were diagnosed. The majority (16/23, 69.57%) of bone metastases were found in the diaphyses. The most common benign bone disease was a benign bone tumor (31.75%, 20/63). The majority (13/20, 65%) of benign bone tumors were enchondromas. In the proximal and distal extremities, the most common disease was degeneration (27.11%, 16/59), followed by benign bone tumors and osteonecrosis of the femoral head (ONFH) (22.03%, 13/59). In the diaphyses of the extremities, bone metastasis was the most common disease, accounting for 64% (16/25) of the findings. For the SPECT/CT analysis, the accuracy was 94.19% (81/86) for reviewer 1 and 95.34% (82/86) for reviewer 2. The weighted kappa score for inter-reviewer agreement was 0.813.

Conclusion: When solitary disease of the extremities is detected by WBS in patients with known cancer, benign lesions may be more common than malignant lesions. SPECT/CT resulted in not only fewer equivocal lesions but also in higher diagnostic accuracy.

Accurate characterization of 99mTc-MDP uptake in extraosseous neoplasm mimicking bone metastasis on whole-body bone scan: contribution of SPECT/CT

Background

^99mTc-labelled methylene diphosphonate (^99mTc-MDP) uptake can occasionally be identified in extraosseous neoplasms on whole-body scans (WBSs) and may be misinterpreted as bone metastasis. The purpose of our study was to investigate the frequency of ^99mTc-MDP uptake in extraosseous neoplasms and to assess the additional value of SPECT/CT for the localization and characterization of this unusual uptake.

Methods

Data from 7308 patients (SPECT/CT was performed in 2147 patients) with known cancer who underwent WBSs for metastatic work-up between May 2015 and July 2018 were retrospectively reviewed. The locations, numbers, and intensities of extraosseous ^99mTc-MDP uptake were evaluated by WBS, and the intratumoural calcification was evaluated by SPECT/CT. The diagnostic accuracy of SPECT/CT in locating ^99mTc-MDP uptake in extraosseous neoplasms was compared to that of WBS.

Results

A total of 41 patients showed ^99mTc-MDP uptake in extraosseous neoplasms. Of these patients, 23 patients had uncertain lesions by WBS, and further SPECT/CT was performed. The incidence of ^99mTc-MDP uptake in extraosseous neoplasms was observed to be 0.6% by WBS and 1.1% (by) SPECT/CT. During imaging analysis, WBS had an accuracy of only 35% (14/40), whereas SPECT/CT correctly located and diagnosed all 40 lesion sites in the 23 patients. Twenty-three lesion sites (57.5%, 23/40) showed moderate or high intensity of extraosseous ^99mTc-MDP uptake. Of the 23 patients, 17 patients (73.9%, 18/23) with 31 lesion sites (77.5%, 31/40) presented with intratumoural calcification.

Conclusions

^99mTc-MDP uptake in extraosseous neoplasms can be observed as 0.6% on WBS and is usually localized to the breast, liver, and lung. Nuclear physicians should be familiar with such extraosseous uptake when interpreting WBSs. SPECT/CT offers better accuracy than WBS alone for locating the majority of lesions present with intratumoural calcification.

Diagnosis of Insufficiency Fracture After Radiotherapy in Patients With Cervical Cancer: Contribution of Technetium Tc 99m-Labeled Methylene Diphosphonate Single-Photon Emission Computed Tomography/Computed Tomography

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.