Role of positron emission tomography/computed tomography in bone malignancies

Vertebral MRI-based radiomics model to differentiate multiple myeloma from metastases: influence of features number on logistic regression model performance

OBJECTIVES

This study aimed to use the most frequent features to establish a vertebral MRI-based radiomics model that could differentiate multiple myeloma (MM) from metastases and compare the model performance with different features number.

METHODS

We retrospectively analyzed conventional MRI (T1WI and fat-suppression T2WI) of 103 MM patients and 138 patients with metastases. The feature selection process included four steps. The first three steps defined as conventional feature selection (CFS), carried out 50 times (ten times with 5-fold cross-validation), included variance threshold, SelectKBest, and least absolute shrinkage and selection operator. The most frequent fixed features were selected for modeling during the last step. The number of events per independent variable (EPV) is the number of patients in a smaller subgroup divided by the number of radiomics features considered in developing the prediction model. The EPV values considered were 5, 10, 15, and 20. Therefore, we constructed four models using the top 16, 8, 6, and 4 most frequent features, respectively. The models constructed with features selected by CFS were also compared.

RESULTS

The AUCs of 20EPV-Model, 15EPV-Model, and CSF-Model (AUC = 0.71, 0.81, and 0.78) were poor than 10EPV-Model (AUC = 0.84, p < 0.001). The AUC of 10EPV-Model was comparable with 5EPV-Model (AUC = 0.85, p = 0.480).

CONCLUSIONS

The radiomics model constructed with an appropriate small number of the most frequent features could well distinguish metastases from MM based on conventional vertebral MRI. Based on our results, we recommend following the 10 EPV as the rule of thumb for feature selection.

KEY POINTS

• The developed radiomics model could distinguish metastases from multiple myeloma based on conventional vertebral MRI. • An accurate model based on just a handful of the most frequent features could be constructed by utilizing multiple feature reduction techniques. • An event per independent variable value of 10 is recommended as a rule of thumb for modeling feature selection.

Temporal subtraction of low-dose and relatively thick-slice CT images with large deformation diffeomorphic metric mapping and adaptive voxel matching for detection of bone metastases: A STARD-compliant article

To evaluate the improvement of radiologist performance in detecting bone metastases at follow up low-dose computed tomography (CT) by using a temporal subtraction (TS) technique based on an advanced nonrigid image registration algorithm.Twelve patients with bone metastases (males, 5; females, 7; mean age, 64.8 ± 7.6 years; range 51-81 years) and 12 control patients without bone metastases (males, 5; females, 7; mean age, 64.8 ± 7.6 years; 51-81 years) were included, who underwent initial and follow-up CT examinations between December 2005 and July 2016. Initial CT images were registered to follow-up CT images by the algorithm, and TS images were created. Three radiologists independently assessed the bone metastases with and without the TS images. The reader averaged jackknife alternative free-response receiver operating characteristics figure of merit was used to compare the diagnostic accuracy.The reader-averaged values of the jackknife alternative free-response receiver operating characteristics figures of merit (θ) significantly improved from 0.687 for the readout without TS and 0.803 for the readout with TS (P value = .031. F statistic = 5.24). The changes in the absolute value of CT attenuations in true-positive lesions were significantly larger than those in false-negative lesions (P < .001). Using TS, segment-based sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of the readout with TS were 66.7%, 98.9%, 94.4%, 90.9%, and 94.8%, respectively.The TS images can significantly improve the radiologist's performance in the detection of bone metastases on low-dose and relatively thick-slice CT.

Advances in Contrast Agents for Contrast-Enhanced Magnetic Resonance Imaging

INTRODUCTION

Magnetic resonance imaging (MRI) is a well-established medical invention in modern medical technology diagnosis. It is a nondestructive, versatile, and sensitive technique with a high spatial resolution for medical diagnosis. However, MRI has some limitations in differentiating certain tissues, particularly tiny blood vessels, pathological to healthy tissues, specific tumors, and inflammatory conditions such as arthritis, atherosclerosis, and multiple sclerosis. The contrast agent (CA) assisted imaging is the best possible solution to resolve the limitations of MRI.

METHOD

The literature review was carried out using the keywords, "MRI, T1&T2 relaxation, MRI CAs, delivery and adverse effects, classification of CAs." The tools used for the literature search were PubMed, Scopus, and Google Scholar.

RESULT AND DISCUSSION

The literature findings focus on MRI technique, limitations, and possible solutions. Primarily, the review focuses on the mechanism of CAs in image formation with detailed explanations of T1 and T2 relaxations, the mechanism of the MRI-CA image formations. This review presents the adverse effects of CA as well as available marketed formulations and recent patents to extent complete information about the MRI-CA.

CONCLUSION

MRI generates detailed visual information of various tissues with high resolution and contrast. The proton present in the biological fluid plays a crucial role in MR image formation, and it is unable to distinguish pathological conditions in many cases. The CAs are the best solution to resolve the limitation by interacting with native protons. The present review discusses the mechanism of CAs in contrast enhancement and its broad classification with the latest literature. Furthermore, the article presents information about CA biodistribution and adverse effects. The review concludes with an appropriate solution for adverse effects and presents the future prospective for researchers to develop advanced formulations.

Effectiveness of 18F-FDG PET/CT in the diagnosis and staging of osteosarcoma: a meta-analysis of 26 studies

BACKGROUND

Multiple trials have attempted to assess the diagnostic value of ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) in osteosarcoma with results remaining inconclusive. This study aims to investigate the effectiveness of ¹⁸F-FDG PET and PET/CT in the diagnosis, staging, recurrence and metastasis formation observations of osteosarcoma through systematic review followed by meta-analysis.

METHODS

Three electronic databases, Medline/PubMed, Embase and the Cochrane Library were utilized in this study. Eligible studies that assessed the performance of ¹⁸F-FDG PET/CT for the diagnosis, staging, restaging and recurrence monitoring of osteosarcoma were retrieved utilizing specific search criteria. After screening and diluting out the non-conforming articles, all relevant articles and their data were identified and extracted to calculate the summary metrics involving sensitivity, specificity, diagnostic odd ratio (DOR), and area under the curve (AUC) to determine the effectiveness of ¹⁸F-FDG PET in diagnosing osteosarcoma clinically.

RESULTS

Out of 1976 articles searched, twenty-six studies were identified that were viable. All data from these articles, utilized in the quantitative analyses, showed after meta-analysis that when utilizing ¹⁸F-FDG PET or PET/CT it was better with a success rate of 90-100% for detecting primary lesions and distant metastases of patients with osteosarcoma. Similar results were also obtained for detecting lung and bone metastases in a subgroup analysis.

CONCLUSIONS

As such the investigation demonstrated that ¹⁸F-FDG PET and PET/CT are very accurate for the diagnosis, staging and recurrence monitoring of osteosarcoma. ¹⁸F-FDG-avid lesions should be further examined in osteosarcoma, especially for suspicious lung lesions.

Effectiveness of 18F-FDG PET/CT in the diagnosis, staging and recurrence monitoring of Ewing sarcoma family of tumors: A meta-analysis of 23 studies

BACKGROUND

To investigate the value of positron emission tomography (PET) and PET/computed tomography (CT) using fluorine-18-fluorodeoxyglucose (F-FDG) in the diagnosis, staging, restaging and recurrence monitoring of Ewing sarcoma family of tumors (ESFTs), a meta-analysis was performed through systematically searching PubMed, Embase, and Cochrane Central library to retrieve articles.

METHODS

After screening and diluting out the articles that met inclusion criteria to be used for statistical analysis the pooled evaluation indexes including sensitivity, specificity, and diagnostic odd ratio (DOR) as well as the summary receiver operating characteristic curve (SROC) were calculated involving diagnostic data (true positive, false positive, false negative, and true negative) extracted from original studies.

RESULTS

Screening determined that out of 2007, 23 studies involving a total of 524 patients were deemed viable for inclusion in the meta-analysis. The results of the analysis showed that the sensitivity and specificity were at 86% and 80%, respectively. Additionally, a satisfactory accuracy of F-FDG PET and PET/CT was observed in detecting ESFT recurrence, lung metastasis, and osseous metastasis.

CONCLUSION

This meta-analysis suggests that F-FDG PET and PET/CT with an extremely high accuracy could be considered a valuable method for detecting distant metastasis and post-operational recurrence of ESFT, which might have a profound impact on the development of treatment protocols for ESFT.

Pictorial review of 18F-FDG PET/CT findings in musculoskeletal lesions

We herein reviewed ¹⁸F-fluoro-2-deoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) findings in a number of musculoskeletal lesions including malignant tumors, benign tumors, and tumor-like lesions with correlations to other radiographic imaging modalities, and described the diversity of the ¹⁸F-FDG PET/CT findings of this entity. Malignant primary musculoskeletal tumors are typically ¹⁸F-FDG avid, whereas low-grade malignant tumors show mild uptake. Benign musculoskeletal tumors generally show a faint uptake of ¹⁸F-FDG, and tumor-like conditions also display various uptake patterns of ¹⁸F-FDG. Although musculoskeletal tumors show various uptakes of ¹⁸F-FDG on PET/CT, its addition to morphological imaging modalities such as CT and MRI is useful for the characterization and differentiation of musculoskeletal lesions.

Use of PET/CT and Stereotactic Radiation Therapy for the Diagnosis and Treatment of Osteosarcoma Metastases

This case report describes the use of two new concepts in the diagnosis and treatment of metastatic osteosarcoma (OSA) in one dog. The dog was initially presented for positron emission tomography and computed tomography (PET/CT) as full-body staging following amputation and adjuvant chemotherapy for treatment of OSA of the proximal tibia. The initial PET/CT did not show evidence of metastatic disease. Six mo after OSA, diagnosis pulmonary metastatic nodules were identified and oral toceranib phosphate was initiated. Twelve mo postdiagnosis the dog developed neck pain and non-ambulatory tetraparesis and was diagnosed with a C7 vertebral metastatic lesion based on magnetic resonance imaging. A second PET/CT was performed to screen for further metastatic lesions, and a nodule within the right ischium was identified. The C7 and ischial lesions were treated with stereotactic radiation therapy (SRT). Sixteen mo postdiagnosis, a third PET/CT was performed due to increasing size of the pulmonary nodules and a right-sided liver metastasis was detected. The liver mass was treated with SRT. The PET/CT scans facilitated identification of gross metastatic lesions that were subsequently treated with SRT, which resulted in clinical improvement of the dog's neurological signs.

Two cases of gastrointestinal stromal tumor of the small intestine with liver and bone metastasis

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. These tumors most commonly occur in the stomach (60%), jejunum and ileum (30%). Metastasis is characteristically the malignant behavior of the GISTs. GISTs most frequently metastasize to the liver and peritoneum, whereas bone and lung metastases are uncommon sites. Here, we described two cases of bone and liver metastases in patients with advanced GISTs. Both of them showed liver metastasis at disease presentation and bone metastasis in early time after the diagnosis. Bone metastases involved the lumber spine and right femur in first patient and L2 vertebral body in the second case. All of the lesions presented a lytic pattern. These cases are presented because of the rare incidence of bone metastasis to femur and vertebral bodies. More attention should be paid to the diagnosis of bone metastases from GISTs in clinical practice despite the shortage of available data on the sensitivity and specificity of bone scintigraphy and PET-CT.

Performance of Positron Emission Tomography and Positron Emission Tomography/Computed Tomography Using Fluorine-18-Fluorodeoxyglucose for the Diagnosis, Staging, and Recurrence Assessment of Bone Sarcoma: A Systematic Review and Meta-Analysis

To investigate the performance of fluorine-18-fluorodeoxyglucose (F-FDG) positron emission tomography (PET) and PET/computed tomography (CT) in the diagnosis, staging, restaging, and recurrence surveillance of bone sarcoma by systematically reviewing and meta-analyzing the published literature.To retrieve eligible studies, we searched the MEDLINE, Embase, and the Cochrane Central library databases using combinations of following Keywords: "positron emission tomography" or "PET," and "bone tumor" or "bone sarcoma" or "sarcoma." Bibliographies from relevant articles were also screened manually. Data were extracted and the pooled sensitivity, specificity, and diagnostic odds ratio (DOR), on an examination-based or lesion-based level, were calculated to appraise the diagnostic accuracy of F-FDG PET and PET/CT. All statistical analyses were performed using Meta-Disc 1.4.Forty-two trials were eligible. The pooled sensitivity and specificity of PET/CT to differentiate primary bone sarcomas from benign lesions were 96% (95% confidence interval [CI], 93-98) and 79% (95% CI, 63-90), respectively. For detecting recurrence, the pooled results on an examination-based level were sensitivity 92% (95% CI, 85-97), specificity 93% (95% CI, 88-96), positive likelihood ratio (PLR) 10.26 (95% CI, 5.99-17.60), and negative likelihood ratio (NLR) 0.11 (95% CI, 0.05-0.22). For detecting distant metastasis, the pooled results on a lesion-based level were sensitivity 90% (95% CI, 86-93), specificity 85% (95% CI, 81-87), PLR 5.16 (95% CI, 2.37-11.25), and NLR 0.15 (95% CI, 0.11-0.20). The accuracies of PET/CT for detecting local recurrence, lung metastasis, and bone metastasis were satisfactory. Pooled outcome estimates of F-FDG PET were less complete compared with those of PET/CT.F-FDG PET and PET/CT showed a high sensitivity for diagnosing primary bone sarcoma. Moreover, PET/CT demonstrated excellent accuracy for the staging, restaging, and recurrence surveillance of bone sarcoma. However, to avoid misdiagnosis, pathological examination or long-term follow-up should be carried out for F-FDG-avid lesions in patients with suspected bone sarcoma.

Establishing a rabbit spinal tumor model for nonvascular interventional therapy through CT-guided percutaneous puncture inoculation

BACKGROUND AND PURPOSE

An animal spinal tumor model is needed to better simulate the clinical situation and to allow percutaneous puncture, which may provide an experimental platform for the new nonvascular interventional therapies. We established a rabbit spinal tumor model through a CT-guided percutaneous puncture inoculation technique for nonvascular interventional therapy.

MATERIALS AND METHODS

VX2 tumor cells were inoculated into the lumbar vertebrae of 32 rabbits through a CT-guided percutaneous puncture technique; then, the development of hind limb paraparesis was observed in the rabbits twice a day. MR imaging and CT were performed on days 14, 21, and 28 postinoculation and at the development of hind limb paraparesis. On days 21 and 28 postinoculation, 2 rabbits, whose imaging suggested successful modeling without hind limb paraparesis, were chosen on each day. The lumbar vertebrae were sampled from 1 rabbit for histopathologic examination, and the other rabbit underwent PET-CT examination before percutaneous vertebroplasty. Finally the lesion vertebrae were sampled for histopathologic examination.

RESULTS

The success rate of modeling was 90.6% (29/32) in our study. On day 21 postinoculation, successful modeling was achieved in 21 rabbits, with 19 having no hind limb paraparesis. On day 28 postinoculation, another 7 achieved successful modeling, and only 1 developed hind limb paraparesis. Percutaneous vertebroplasty treatment was successful for the 2 rabbit models.

CONCLUSIONS

Establishment of a rabbit spinal tumor model through a CT-guided percutaneous puncture technique and inoculation of VX2 tumor is easy and has a high success rate. The established model can be used to study nonvascular interventional therapies for spinal tumor, including percutaneous vertebroplasty.