Age-related changes in pre- and postmenopausal women investigated with 18F-fluoride PET--a preliminary study

Emerging Role of 18F-NaF PET/Computed Tomographic Imaging in Osteoporosis: A Potential Upgrade to the Osteoporosis Toolbox

Osteoporosis is a metabolic bone disorder that leads to a decline in bone microarchitecture, predisposing individuals to catastrophic fractures. The current standard of care relies on detecting bone structural change; however, these methods largely miss the complex biologic forces that drive these structural changes and response to treatment. This review introduces sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT) as a powerful tool to quantify bone metabolism. Here, we discuss the methods of 18F-NaF PET/CT, with a special focus on dynamic scans to quantify parameters relevant to bone health, and how these markers are relevant to osteoporosis.

18F-Sodium Fluoride PET as a Diagnostic Modality for Metabolic, Autoimmune, and Osteogenic Bone Disorders: Cellular Mechanisms and Clinical Applications

In a healthy body, homeostatic actions of osteoclasts and osteoblasts maintain the integrity of the skeletal system. When cellular activities of osteoclasts and osteoblasts become abnormal, pathological bone conditions, such as osteoporosis, can occur. Traditional imaging modalities, such as radiographs, are insensitive to the early cellular changes that precede gross pathological findings, often leading to delayed disease diagnoses and suboptimal therapeutic strategies. ¹⁸F-sodium fluoride (¹⁸F-NaF)-positron emission tomography (PET) is an emerging imaging modality with the potential for early diagnosis and monitoring of bone diseases through the detection of subtle metabolic changes. Specifically, the dissociated ¹⁸F^- is incorporated into hydroxyapatite, and its uptake reflects osteoblastic activity and bone perfusion, allowing for the quantification of bone turnover. While ¹⁸F-NaF-PET has traditionally been used to detect metastatic bone disease, recent literature corroborates the use of ¹⁸F-NaF-PET in benign osseous conditions as well. In this review, we discuss the cellular mechanisms of ¹⁸F-NaF-PET and examine recent findings on its clinical application in diverse metabolic, autoimmune, and osteogenic bone disorders.

Association of pretreatment SUVmax of cervix and SCC-antigen with FIGO2018 stage in Stage IIB-IVB squamous cervical cancer and relationship to prognosis

OBJECTIVE

To evaluate the association of pretreatment maximum standardized ¹⁸ F-fluorodeoxyglucose uptake value (SUV_max ) of cervix and serum squamous cell carcinoma antigen (SCC-ag) with FIGO2018 stage and prognosis among women with Stage IIB-IVB squamous cervical cancer.

METHODS

Retrospective study of 116 women with FIGO2018 Stage IIB-IVB cervical cancer treated in Hangzhou, China, 2013-2015. The relationship between pretreatment SUV_max or SCC-ag and prognostic factors was evaluated by univariate and multivariate analyses.

RESULTS

Women were stratified by mean SUV_max and mean SCC-ag. There was a significant difference between low (<12.9) and high (≥12.9) SUV_max groups in menopause (P = 0.004), FIGO2018 stage (P = 0.015), and survival rate (P < 0.001). The low group had better overall and progress-free survival by Kaplan-Meier evaluation (both P = 0.022). High SCC-ag (≥14.6 ng/mL) was associated with FIGO2018 stage (P = 0.038) and distant metastasis (P = 0.011). There was a significant correlation between SUV_max and serum SCC-ag (P = 0.026). In multivariate Cox regression analyses, FIGO2018 stage (P = 0.019) and SUV_max of cervix (P = 0.015) were independent predictors of poor outcome in squamous cervical cancer.

CONCLUSION

Both SUV_max of cervix and SCC-ag were associated with FIGO2018 stage in squamous cervical cancer. Pretreatment high SUV_max of cervix and advanced FIGO2018 stage might indicate a poor prognosis.

Advanced Quantitative Spine Imaging

Although advanced quantitative imaging may not be currently used to any degree in the routine reporting of spinal examinations, this situation will change in the not too distant future. Advanced quantitative imaging has already allowed us to understand a great deal more regarding spinal development, marrow physiology, and disease pathogenesis. Radiologists are ideally suited to drive this research forward. To speed up this process and optimize the impact of studies reporting spine quantitative data, we should work toward universal standards on the acquisition of spine data that will allow quantitative studies to be more easily compared, contrasted, and amalgamated.

Assessment of femoral neck bone metabolism using 18F-sodium fluoride PET/CT imaging

BACKGROUND

Standard of care metabolic bone disease assessment relies on changes to bone quantity, which can only be detected after structural changes occur.

PURPOSE

To investigate the usefulness of Bone Metabolism Score (BMS), derived from fluorine 18 labeled sodium fluoride (¹⁸F-NaF) PET/CT imaging as a biomarker of localized metabolic changes at the femoral neck.

METHODS

In this retrospective study, 139 participants (68 females and 71 males, ages 21-75 years) that had undergone ¹⁸F-NaF PET/CT were included. BMS was calculated as the ratio of standard uptake value (SUV) in the bone region to that of the total region. Correlations and linear regressions of BMS with age, CT-derived bone mineral density (BMD), body mass index (BMI), height, and weight were conducted. Differences in BMS between women younger and older than the age of 50 years were assessed. Inter- and intra-operator reproducibility was evaluated by coefficient of variation (CV) and intra-class correlation coefficient (ICC).

RESULTS

Among females, age was negatively correlated with left and right whole BMS (5.61% and 4.90% drop in BMS per decade of life) and left and right cortical BMS (10.50% and 10.09% drop in BMS per decade of life). BMS of women older than 50 years was lower than BMS of women younger than 50 years (P < .0001). Among males, age was negatively correlated with left and right whole BMS (4.29% and 4.25% drop in BMS per decade of life) and left and right cortical BMS (9.13% and 10.30% drop in BMS per decade of life). BMD was positively correlated with whole (r = 0.80, P < .0001) and cortical (r = 0.92, P < .0001) BMS.

CONCLUSIONS

BMS could provide functional insight regarding bone metabolism in the femoral neck to complement bone health status assessed through conventional structural imaging. The methodology described herein could be potentially useful for assessing hip fracture risk in individuals when BMD tests provide borderline determination of bone disease.

Applications of PET-MRI in musculoskeletal disease

New integrated PET-MRI systems potentially provide a complete imaging modality for diagnosis and evaluation of musculoskeletal disease. MRI is able to provide excellent high-resolution morphologic information with multiple contrast mechanisms that has made it the imaging modality of choice in evaluation of many musculoskeletal disorders. PET offers incomparable abilities to provide quantitative information about molecular and physiologic changes that often precede structural and biochemical changes. In combination, hybrid PET-MRI can enhance imaging of musculoskeletal disorders through early detection of disease as well as improved diagnostic sensitivity and specificity. The purpose of this article is to review emerging applications of PET-MRI in musculoskeletal disease. Both clinical applications of malignant musculoskeletal disease as well as new opportunities to incorporate the molecular capabilities of nuclear imaging into studies of nononcologic musculoskeletal disease are discussed. Lastly, we discuss some of the technical considerations and challenges of PET-MRI as they specifically relate to musculoskeletal disease.

LEVEL OF EVIDENCE

5 TECHNICAL EFFICACY: Stage 3 J. Magn. Reson. Imaging 2018;48:27-47.

In Vivo Molecular Imaging of Musculoskeletal Inflammation and Infection

In vivo molecular imaging detects biologic processes at molecular level and provides diagnostic information at an earlier time point during disease onset or repair. It offers definite advantage over anatomic imaging in terms of improved sensitivity and ability to quantify. Radionuclide molecular imaging has been widely used in clinical practice. This article discusses the role of radionuclide imaging in various infective and inflammatory diseases affecting musculoskeletal system with a focus on PET. It appears that, as more data become available, combined PET/MR imaging could emerge as a front runner in the imaging of musculoskeletal infection and inflammation.

Potential of PET-MRI for imaging of non-oncologic musculoskeletal disease

Early detection of musculoskeletal disease leads to improved therapies and patient outcomes, and would benefit greatly from imaging at the cellular and molecular level. As it becomes clear that assessment of multiple tissues and functional processes are often necessary to study the complex pathogenesis of musculoskeletal disorders, the role of multi-modality molecular imaging becomes increasingly important. New positron emission tomography-magnetic resonance imaging (PET-MRI) systems offer to combine high-resolution MRI with simultaneous molecular information from PET to study the multifaceted processes involved in numerous musculoskeletal disorders. In this article, we aim to outline the potential clinical utility of hybrid PET-MRI to these non-oncologic musculoskeletal diseases. We summarize current applications of PET molecular imaging in osteoarthritis (OA), rheumatoid arthritis (RA), metabolic bone diseases and neuropathic peripheral pain. Advanced MRI approaches that reveal biochemical and functional information offer complementary assessment in soft tissues. Additionally, we discuss technical considerations for hybrid PET-MR imaging including MR attenuation correction, workflow, radiation dose, and quantification.

Sodium 18F-fluoride PET/CT of bone, joint, and other disorders

The use of (18)F-sodium fluoride ((18)F-NaF) with PET/CT is increasing. This resurgence of an old tracer has been fueled by several factors including superior diagnostic performance over standard (99m)Tc-based bone scintigraphy, growth in the availability of PET/CT imaging systems, increase in the number of regional commercial distribution centers for PET radiotracers, the recent concerns about potential recurring shortages with (99m)Tc-based radiotracers, and the recent decision by the Centers for Medicare and Medicaid Services to reimburse for (18)F-NaF PET/CT for evaluation of patients with known or suspected bone metastases through the National Oncologic PET Registry. The major goal of this article is to review the current evidence on the diagnostic utility of (18)F-NaF in the imaging assessment of the bone and joint in a variety of clinical conditions.

Age-related differences in the activity of arterial mineral deposition and regional bone metabolism: a 18F-sodium fluoride positron emission tomography study

Functional (18)F-fluoride PET demonstrated an inverse relationship between the activity of arterial mineral deposition and regional bone metabolism. While bone metabolism decreases with age, the activity of arterial mineral deposition increases.

INTRODUCTION

The extent of arterial calcification increases with age, whereas bone mineral density decreases, evidencing a well-known inverse correlation on morphological basis. The aim of this study was to evaluate the functional relationship between the activity of arterial mineral deposition and regional bone metabolism as assessed by (18)F-sodium fluoride (NaF) PET/CT.

METHODS

Three hundred four subjects were examined by (18)F-NaF PET/CT. Tracer accumulation in the femoral arteries was analyzed both qualitatively and semiquantitatively by measuring the blood-pool-corrected standardized uptake value (target-to-background ratio). Uptake was compared with cardiovascular risk factors (RFs), calcified plaque burden, and regional bone metabolism as assessed by PET/CT.

RESULTS

The activity of arterial mineral deposition significantly increased with age (p < 0.001), whereas regional bone metabolism significantly decreased (p < 0.001). There was a significant inverse correlation between bone metabolism and arterial mineral deposition (unadjusted, p < 0.001); that association was not significant (p = 0.79) when controlled for age and other RFs. Both high activity of arterial mineral deposition and low bone metabolism were significantly associated with cardiovascular events and other RFs.

CONCLUSION

(18)F-NaF PET/CT provides a tool to visualize and quantify the activity of arterial mineral deposition and regional bone metabolism. In this study, we observed an inverse correlation between the activity of arterial mineral deposition and regional bone metabolism. While the activity of arterial mineral deposition significantly increases with age, regional bone metabolism decreases.