Non-oncologic Applications of PET/CT and PET/MR in Musculoskeletal, Orthopedic, and Rheumatologic Imaging: General Considerations, Techniques, and Radiopharmaceuticals

An evaluation of the physiological uptake range of 18F-fluoro-2-deoxy-D-glucose in normal ovaries of seven dogs using positron emission tomography/computed tomography

Introduction

This study evaluated the physiological uptake range of 18F-fluoro-2-deoxy-D-glucose (18F-FDG) in the normal ovaries of seven dogs using positron emission tomography/computed tomography (PET/CT).

Materials and methods

The dogs were subjected to general anesthesia and were positioned in ventral recumbency for PET/CT scans. The dosage of 18F-FDG ranged from 0.14 to 0.17 mCi/kg and was administered intravenously followed by 0.9% NaCl flushing; PET/CT images of each dog were obtained precisely 60 min after the injection of 18F-FDG. The regions of interest were drawn manually, and standardized uptake values (SUV) were calculated to evaluate the 18F-FDG uptake in each ovary. The maximum and mean SUVs (SUV max and SUV mean) for all the ovaries of the dogs were then computed.

Results

The range of SUV max and SUV mean of the normal ovaries of the dogs were 1.28-1.62 and 1.07-1.31 (mean ± standard deviation), respectively.

Conclusion

This is the first study to investigate the normal 18F-FDG uptake baseline data of normal canine ovaries using PET/CT scans. These data will help clinicians in identifying malignant tumors before anatomical changes in the ovary through PET/CT scans.

Rheumatology experience with FDG PET / CT in inflammation of unknown origin: a single - centre report for determining factors associated with diagnostic precision

BACKGROUND / AIM: The use of PET / CT is becoming more common in the elucidation of inflammatory processes in which the underlying cause cannot be determined by conventional examinations. Although PET / CT is an effective method for detecting inflammatory foci, the precise diagnosis may not be obtained in all cases. In addition, considering factors such as radiation exposure and cost, it becomes important to identify patients who can get results with PET / CT. In this study, it was aimed to examine the factors that can predict the differential diagnostic value of PET / CT by retrospectively scanning patients who underwent PET / CT for inflammation of unknown origin (IUO) in rheumatology practice.

METHODS

Demographic, clinical and laboratory information of the patients followed up in our clinic and who underwent PET / CT for differential diagnosis were enrolled. Whether they were diagnosed after PET / CT and during the follow - up period, and their diagnoses were examined.

RESULTS

A total of 132 patients were included in the study. A previous diagnosis of rheumatic disease was present in 28.8 % of the patients, and a history of malignancy was present in 2.3 % . The patients were divided into three groups: group 1 patients with increased FDG uptake in PET / CT and diagnosis confirmed by PET / CT, group 2 patients with increased FDG uptake in PET / CT but diagnosis was not confirmed, and group 3 patients without increased FDG uptake in PET / CT. Increased FDG uptake in PET / CT was detected in 73 % of the patients. While PET / CT helped the diagnosis in 47 (35.6 %) patients (group 1), it did not help the diagnosis in 85 (64.4 %) (groups 2 and 3). Thirty - one (65.9 %) of the diagnosed patients were diagnosed with a rheumatologic disease. When the 3 groups were compared, male gender, advanced age, CRP levels, presence of constitutional symptoms, SUVmax values and number of different organs with increased FDG uptake were higher in Group 1. Sixty - six percent and 74 % of the patients in groups 2 and 3 were not diagnosed during the follow - up period. No patient in group 3 was diagnosed with malignancy during follow - up.

CONCLUSION

PET / CT has high diagnostic value when combined with clinical and laboratory data in the diagnosis of IUO. Our study revealed that various factors can affect the diagnostic value of PET / CT. Similar to the literature, the statistically significant difference in CRP levels shows that patients with high CRP levels are more likely to be diagnosed with an aetiology in PET / CT. Although detection of involvement in PET / CT is not always diagnostic, there was an important finding that no malignancy was detected in the follow - up in any patient without PET / CT involvement. Key points • PET / CT is an effective method for detecting inflammatory foci. • PET / CT has proven to be effective in the diagnosis of rheumatological diseases, the extent of disease and the evaluation of response to treatment. • Indications for the use of PET / CT in the field of rheumatology and the associated factors and clinical features supporting the diagnosis with PET / CT are still to be fully clarified. • In routine practice, with PET / CT, both delays in diagnosis and examinations performed during diagnosis and the cost can be reduced.

Positron emission tomography/magnetic resonance imaging in musculoskeletal benign conditions

A wide spectrum of benign musculoskeletal (orthopedic and rheumatological) conditions affect the general population. Collectively, these are common, and they can inflict significant morbidity with resultant negative impact on the quality of life of patients. For many of these conditions, there is established evidence for research and clinical use of PETCT and MRI for assessment of disease. Introduction of integrated PET/MRI around a decade ago brought optimism that combining the strength of PET and MRI techniques on a single platform could have synergistic effect to benefit imaging assessment of patients, including in the context of benign musculoskeletal conditions. This review specifically focuses on the progress that has been made. This aims to showcase clinical studies derived primarily from the integrated PET/MRI platforms for the evaluation of common orthopedic and rheumatological conditions. Despite enthusiasm and progress by early adopters of the PET/MRI technology, significant barriers are present for its wider adoption, validation, and translation to routine clinical practice. Attenuation correction is a particular challenge which affects regions close to the skeleton and impacts PET/MRI assessment of musculoskeletal disorders. Continued effort on research and validation, as well as promotion of its multimodal multiparametric capability to clinical and pharmaceutical stakeholders, and increased availability through increased adoption of PET/MRI scanners internationally, may accelerate its translation into routine clinical practice in this domain.

Diagnosis and staging of hepatobiliary malignancies: Potential incremental value of (18)F-FDG-PET/MRI compared to MRI of the liver

OBJECTIVE

 The purpose of the study was to investigate the potential added value of ¹⁸F-FDG-PET/MRI (functional information derived from PET) over standard diagnostic liver MRI (excellent soft tissue characterization) in diagnosing and staging suspected primary hepatobiliary malignancies including extrahepatic cholangiocarcinoma (ECC), intrahepatic cholangiocellular carcinoma (ICC) and gallbladder cancer (GBCA).

METHODS

 Twenty consecutive patients with suspected hepatobiliary malignancy were included in this retrospective study. All patients underwent combined whole-body (WB) ¹⁸F-FDG-PET/MRI including contrast-enhanced MRI of the liver, contrast-enhanced WB-MRI and WB ¹⁸F-FDG-PET. Two experienced readers staged hepatobiliary disease using TNM criteria: first based on MRI alone and then based on combined ¹⁸F-FDG-PET/MRI. Subsequently, the impact of FDG-PET/MRI on clinical management compared to MRI alone was recorded. Histopathologic proof served as the reference standard.

RESULTS

 Hepatobiliary neoplasms were present in 16/20 patients (ECC n = 3, ICC n = 8, GBCA n = 5), two patients revealed benign disease, two were excluded. TNM staging with ¹⁸F-FDG-PET/MRI was identical to MRI alone in 11/18 (61.1 %) patients and correctly changed the stage in 4/18 (22.2 %), resulting in a change in management for 2/4 patients (11.1 %). ¹⁸F-FDG-PET/MRI was false-positive in 3/18 cases (16.7 %). Both MRI and ¹⁸F-FDG-PET/MRI were falsely positive in 1 case without malignancy.

CONCLUSIONS

 A small incremental benefit of ¹⁸F-FDG-PET/MRI over standard MRI of the liver was observed. However, in some cases ¹⁸F-FDG-PET/MRI may lead to false-positive findings. Overall there is seemingly limited role of ¹⁸F-FDG-PET/MRI in patients with suspected hepatobiliary malignancy.

Total-Body PET Imaging of Musculoskeletal Disorders

Imaging of musculoskeletal disorders, including arthritis, infection, osteoporosis, sarcopenia, and malignancies, is often limited when using conventional modalities such as radiography, computed tomography (CT), and MR imaging. As a result of recent advances in Positron Emission Tomography (PET) instrumentation, total-body PET/CT offers a longer axial field-of-view, higher geometric sensitivity, and higher spatial resolution compared with standard PET systems. This article discusses the potential applications of total-body PET/CT imaging in the assessment of musculoskeletal disorders.

Musculoskeletal trauma imaging in the era of novel molecular methods and artificial intelligence

Over the past decade rapid advancements in molecular imaging (MI) and artificial intelligence (AI) have revolutionized traditional musculoskeletal radiology. Molecular imaging refers to the ability of various methods to in vivo characterize and quantify biological processes, at a molecular level. The extracted information provides the tools to understand the pathophysiology of diseases and thus to early detect, to accurately evaluate the extend and to apply and evaluate targeted treatments. At present, molecular imaging mainly involves CT, MRI, radionuclide, US, and optical imaging and has been reported in many clinical and preclinical studies. Although originally MI techniques targeted at central nervous system disorders, later on their value on musculoskeletal disorders was also studied in depth. Meaningful exploitation of the large volume of imaging data generated by molecular and conventional imaging techniques, requires state-of-the-art computational methods that enable rapid handling of large volumes of information. AI allows end-to-end training of computer algorithms to perform tasks encountered in everyday clinical practice including diagnosis, disease severity classification and image optimization. Notably, the development of deep learning algorithms has offered novel methods that enable intelligent processing of large imaging datasets in an attempt to automate decision-making in a wide variety of settings related to musculoskeletal trauma. Current applications of AI include the diagnosis of bone and soft tissue injuries, monitoring of the healing process and prediction of injuries in the professional sports setting. This review presents the current applications of novel MI techniques and methods and the emerging role of AI regarding the diagnosis and evaluation of musculoskeletal trauma.

Potential Applications of PET/CT/MR Imaging in Inflammatory Diseases: Part I: Musculoskeletal and Gastrointestinal Systems

During the past decades, the role of fludeoxyglucose (FDG)-PET and hybrid PET/computed tomography (CT) has been established clinically in the diagnostic workup of a multitude of infectious and inflammatory disorders. In recent years, the fusion of MR imaging to PET has also been increasingly explored, and this may be especially useful in musculoskeletal and gastrointestinal inflammatory diseases due to exceptional soft tissue contrast and reduced radiation dose. This article outlines the current potential for hybrid molecular imaging in the musculoskeletal system and the gastrointestinal tract with special focus on the potential for fused PET/CT/MR imaging.

What Is the Best Method to Differentiate Acute Charcot Foot From Acute Infection?

RECOMMENDATION

Differentiation between acute Charcot neuroarthropathy (CN) and acute infection/osteomyelitis is complex and requires multiple (>1) diagnostic criteria. These criteria include an emphasis on the presence of neuropathy, history, and physical examination. The absence of skin wounds and resolution of swelling/erythema with elevation makes the likelihood of infection very low. In unclear cases, laboratory testing, histologic examination and culturing of bone specimens, scintigraphy, and imaging, especially magnetic resonance imaging (MRI), may be of benefit.

LEVEL OF EVIDENCE

Moderate.

DELEGATE VOTE

Agree: 100%, Disagree: 0%, Abstain: 0% (Unanimous, Strongest Consensus).

Clinical Nononcologic Applications of PET/CT and PET/MRI in Musculoskeletal, Orthopedic, and Rheumatologic Imaging

OBJECTIVE

With improvements in PET/CT and PET/MRI over the last decade, as well as increased understanding of the pathophysiology of musculoskeletal diseases, there is an emerging potential for PET as a primary or complementary modality in the management of rheumatologic and orthopedic conditions.

CONCLUSION

We discuss the role of PET/CT and PET/MRI in nononcologic musculoskeletal disorders, including inflammatory and infectious conditions and postoperative complications. There is great potential for an increased role for PET to serve as a primary or complementary modality in the management of orthopedic and rheumatologic disorders.