Effects of age and weight on the metabolic activities of the cervical, thoracic and lumbar spines as measured by fluorine-18 fluorodeoxyglucose-positron emission tomography in healthy males.

OBJECTIVE: This study aimed to explore the age and weight-related metabolic trends in the spines of healthy male subjects using fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) imaging. SUBJECTS AND METHODS: Forty three healthy male subjects (age 23-75 years, weight 50-145kg) were selected from the CAMONA study. A global assessment methodology was applied to the subjects' 18F-FDG 180 minute scans, where each region of the spine (cervical, thoracic and lumbar) was individually encapsulated in a single region of interest, and standardized uptake value (SUVmean) was calculated per respective region. RESULTS: SUVmean increased significantly with weight in both the thoracic spine (Slope=0.0066, P=0.001) and lumbar spine (Slope=0.0087, P<0.0001), but not the cervical spine. There were no significant correlations between age and SUVmean in all three regions. The cervical spine (average SUVmean=1.84±0.31) illustrated elevated activity when compared to the thoracic (average SUVmean=1.46±0.27, P<0.0001) and lumbar (average SUVmean=1.41±0.28, P<0.0001) spines. CONCLUSION: This study illustrated the ability of 18F-FDG PET to assess metabolic processes in the spine. The data provided evidence of weight dependent metabolic activity, likely related to inflammation. This study offers a methodological precedent that can be applied to studies in populations with back pain.

Prognostic significance of 18F-sodium fluoride in newly diagnosed multiple myeloma patients.

Focal bone lesions and fractures due to weakened bone are associated with higher morbidity and mortality of multiple myeloma (MM) patients. 18F-sodium fluoride (18F-NaF) is a sensitive PET radiotracer for detection of abnormal bone metabolism and, therefore, is particularly suited to assess the degree of bone involvement in MM patients. We aimed to investigate the prognostic significance of metabolic active volume (MAV) of 18F-NaF-avid lesions in MM patients. In addition to MAV, conventional methods of PET quantification, namely SUVmean and SUVmax, were measured in each patient for the purpose of comparison. Thirty-seven newly diagnosed MM patients were included. PET imaging was performed after intravenous administration of 200 MBq NaF. Active bone lesions and fractures on whole-body 18F-NaF-PET/CT scans were identified. An adaptive thresholding algorithm automatically calculated the total MAV, SUVmean and SUVmax for each patient (ROVER, ABX, Radeberg, Germany). The patients were followed for a median of 39.8 months after treatment (range: 17.8-55.4). The overall survival (OS) of patients with 18F-NaF-MAV value > 38.65 (36.36% [N of Events/Total N: 4/11]) was significantly shorter than that of patients with 18F-NaF-MAV value < 38.65 (3.85% [1/26]; P = 0.002). In multivariate forward stepwise (conditional LR) Cox regression analysis of prognostic factors of OS (including 18F-NaF-MAV (> 38.65 or < 38.65), age, gender, beta-2 microglobulin, and revised international staging system), 18F-NaF-MAV remained the only significant factor (HR: 14.39, P = 0.02). The results for PFS were not significant. Moreover, Kaplan-Meier analyses of conventional methods of PET quantification did not reveal any statistically significant log-rank p-values. MM patients with high 18F-NaF-MAV had shorter overall survival, compared to those with low 18F-NaF-MAV levels (NCT02187731).

Assessing the feasibility of NaF-PET/CT versus FDG-PET/CT to detect abdominal aortic calcification or inflammation in rheumatoid arthritis patients.

OBJECTIVE: We aimed to determine whether NaF-PET/CT or FDG-PET/CT can detect abdominal aortic molecular calcification and inflammation in patients with rheumatoid arthritis (RA). METHODS: In this study, 18 RA patients (4 women, 14 men; mean age 56.0 ± 11.7) and 18 healthy controls (4 women, 14 men; mean age 55.8 ± 11.9) were included. The controls were matched to patients by sex and age (± 4 years). All subjects of this study underwent NaF-PET/CT scanning 90 min following the administration of NaF. FDG-PET/CT imaging was performed 180 min following intravenous FDG injection. Using OsiriX software, the global mean standardized uptake value (global SUVmean) in abdominal aorta was calculated for both FDG and NaF. The NaF SUVmean and FDG SUVmean were divided by the blood pool activity providing target-to-background ratios (TBR) namely, NaF-TBRmean and FDG-TBRmean. The CT calcium volume score was obtained using a growing region algorithm based on Hounsfield units. RESULTS: The average NaF-TBRmean score among RA patients was significantly greater than that of healthy controls (median 1.61; IQR 1.49-1.88 and median 1.40; IQR 1.23-1.52, P = 0.002). The average CT calcium volume score among RA patients was also significantly greater than that of healthy controls (median 1.96 cm3; IQR 0.57-5.48 and median 0.004 cm3; IQR 0.04-0.05, P < 0.001). There was no significant difference between the average FDG-TBRmean scores in the RA patients when compared to healthy controls (median 1.29; IQR 1.13-1.52 and median 1.29; IQR 1.13-1.52, respectively, P = 0.98). CONCLUSION: Quantitative assessment with NaF-PET/CT identifies increased molecular calcification in the wall of the abdominal aorta among patients with RA as compared with healthy controls, while quantitative assessment with FDG-PET/CT did not identify a difference in aortic vessel wall FDG uptake between the RA and healthy control groups.

An Isolated Osseous Rosai-Dorfman Disease Shown on FDG PET/CT.

Rosai-Dorfman disease is typically presented as lymphadenopathy, especially in the neck. Extranodal diseases also frequently occur but are generally concurrent with nodal disease. We report FDG PET/CT findings of solitary femoral Rosai-Dorfman disease without any lymphadenopathy in a pediatric patient.

The Evolving Role of PET-Based Novel Quantitative Techniques in the Interventional Radiology Procedures of the Liver.

Interventional radiology procedures have revolutionized the treatment of cancer and interventional oncology is now the fourth pillar of cancer care. The article discusses the importance of fluorodeoxyglucose (FDG)-PET imaging, and dual time-point imaging in the context of PET/computed tomography as applied to treatments of liver malignancy. The necessary paradigm shift in the adoption of novel segmentation methodologies to express global disease burden is explored.

Evolving Role of PET-Based Novel Quantitative Techniques in the Management of Hematological Malignancies.

"The role of 18F-fluorodeoxyglucose PET/computed tomography in hematological malignancies continues to expand in disease diagnosis, staging, and management. A key advantage of PET over other imaging modalities is its ability to quantify tracer uptake, which can be used to determine degree of disease activity. Although tracer uptake with PET is conventionally measured in focal lesions, novel quantitative techniques are being investigated that set objective protocols and produce robust parameters that represent total disease activity portrayed by PET. This article discusses recent advances in PET quantification that can improve reliability and accuracy of characterizing hematological malignancies."

Metastatic Seeding Attacks Bone Marrow, Not Bone: Rectifying Ongoing Misconceptions.

Conventional modalities, such as bone scintigraphy, are commonly used to assess osseous abnormalities in skeletal metastasis. Fluorine-18 (18F)-sodium fluoride (NaF) PET similarly portrays osteoblastic activity but with improved spatial and contrast resolution and more accurate anatomic localization. However, these modalities rely on indirect evidence for tumor activity. PET imaging with 18F-fluorodeoxyglucose (FDG) and tumor-specific tracers may have an increased role by directly portraying the metabolic activity of cancer cells, which are often seeded in bone marrow and cause osseous disease after initial latency. This article describes the utility and limitations of these modalities in assessing skeletal metastases.

Pretreatment volumetric parameters of FDG-PET predict the survival after Yttrium-90 radio-embolization in metastatic liver disease.

This study aimed to determine the prognostic value of pretreatment FDG-PET in patients with metastatic liver disease undergoing Yttrium 90 (90Y) radio-embolization using global disease assessment measures. Data from 16 patients with metastatic liver disease (8 males, 8 females) aged 55-97 years (mean: 67±12) were retrospectively collected. On PET, active malignant lesions in the liver were segmented with an adaptive thresholding system (ROVER software, ABX GmbH, Radeberg, Germany). Conventional measures of PET quantification such as SUVmean, SUVmax, and partial volume-corrected SUVmean (pvcSUVmean) and volumetric parameters including metabolic tumor volume (MTV), total lesion glycolysis (TLG) and pvcTLG were measured. Receiver operating characteristic (ROC) was used to determine the optimal cutoffs for Kaplan-Meier analyses. Kaplan-Meier analysis was performed to estimate progression-free survival (PFS) and overall survival (OS). In addition, Cox regression analysis was used to determine predictors of PFS and OS. There was no correlation between pretreatment conventional parameters of FDG-PET and PFS or OS. In contrast, in the univariate Cox regression analyses, pretreatment volumetric parameters were significant predictors for PFS [TLG (HR: 6.1, P=0.02), pvcTLG (HR: 3.9, P=0.03) and MTV (HR: 5.8, P=0.02)]. Moreover, TLG (HR: 6.1, P=0.03), pvcTLG (HR: 5.2, P<0.01) and MTV (HR: 10.7, P<0.01) were significant prognostic factors for OS. Pretreatment volumetric FDG-PET parameters are prognostic factors for PFS and OS in patients with liver metastasis receiving radio-embolization with 90Y.

The Evolving Role of FDG-PET/CT in the Diagnosis, Staging, and Treatment of Breast Cancer.

The applications of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/X-ray computed tomography (PET/CT) in the management of patients with breast cancer have been extensively studied. According to these studies, PET/CT is not routinely performed for the diagnosis of primary breast cancer, although PET/CT in specific subtypes of breast cancer correlates with histopathologic features of the primary tumor. PET/CT can detect metastases to mediastinal, axial, and internal mammary nodes, but it cannot replace the sentinel node biopsy. In detection of distant metastases, this imaging tool may have a better accuracy in detecting lytic bone metastases compared to bone scintigraphy. Thus, PET/CT is recommended when advanced-stage disease is suspected, and conventional modalities are inconclusive. Also, PET/CT has a high sensitivity and specificity to detect loco-regional recurrence and is recommended in asymptomatic patients with rising tumor markers. Numerous studies support the future role of PET/CT in prediction of response to neoadjuvant chemotherapy (NAC). PET/CT has a higher diagnostic value for prognostic risk stratification in comparison with conventional modalities. With the continuing research on the treatment planning and evaluation of patients with breast cancer, the role of PET/CT can be further extended.

Evolving Roles of Fluorodeoxyglucose and Sodium Fluoride in Assessment of Multiple Myeloma Patients: Introducing a Novel Method of PET Quantification to Overcome Shortcomings of the Existing Approaches.

PET with fluorodeoxyglucose and sodium fluoride (NaF) radiotracers has shown a great promise in assessing patients with multiple myeloma (MM). However, the standardization of PET/computed tomography scans interpretation in patients with myeloma in clinical practice is still debatable. This article reviews available data regarding the use of fluorodeoxyglucose and NaF PET in patients with MM. Introduced is a novel method of PET quantification as applied to patients with MM. A new concept for PET-based evaluation of patients with MM is also discussed: dual time point imaging. Finally, the role of NaF in assessment of cardiovascular complications of MM is described.

Evolving Role of MR Imaging and PET in Assessing Osteoporosis.

An imbalance in bone remodeling results in many metabolic bone diseases, such as osteoporosis. fluorine-18 sodium fluoride PET imaging allows the assessment of bone remodeling process in a anatomy specific manner. On the other hand structural imaging modalities such as MRI can now generate high resolution images of bone including the trabecular and cortical microstructure. Molecular (functional) imaging with PET in conjunction with structural imaging has the potential to improve the way metabolic bone diseases are managed in the clinic.

An update on the role of 18F-FDG-PET/CT in major infectious and inflammatory diseases.

For decades, conventional nuclear medicine techniques have been utilized for the assessment of many infectious and inflammatory diseases. Most of these techniques have limitations such as the relatively low spatial resolution, being time consuming and low sensitivity or specificity. In recent years, FDG-PET/CT has shown promising role in the management of such diseases. An expanding set of studies illustrate the multifarious roles of FDG-PET/CT in the assessment of these conditions, both systemic diseases and more regional. Specifically, PET can provide vital information at a molecular level and consequently detect the disease activity at their earliest manifestation. With the continuing research on the diagnosis and treatment monitoring of patients with infectious and inflammatory diseases, the role of PET/CT can be further extended.

Pre-treatment partial-volume-corrected TLG is the best predictor of overall survival in patients with relapsing/refractory non-hodgkin lymphoma following radioimmunotherapy.

The role of fluorodeoxyglucose-positron emission tomography (FDG-PET) has been well established in assessment of lymphoma, including non-Hodgkin lymphoma (NHL). The aim of this study was to compare changes and survival predictive values of various quantification parameters of FDG-PET/CT in patients with relapsing/refractory lymphoma before and after radioimmunotherapy (RIT). Data from 17 patients with relapsing/refractory NHL, treated with targeted RIT after chemotherapy/radiotherapy, were retrospectively collected. FDG-PET/CT scans were performed approximately three months before and six months after RIT. An adaptive contrast-oriented thresholding algorithm was used to segment lesions on the FDG-PET images. Wilcoxon signed-rank tests were used to assess changes in SUVmax, SUVmean, partial volume-corrected SUVmean (pvcSUVmean), total lesion glycolysis (TLG), and pvcTLG before and after treatment. The patients were followed up after completing RIT for up to 10 years. Kaplan-Meier and Cox regression analyses evaluated the association between the quantification parameters and survival data. In the survived group, the decrease in mean percentage of change for TLG and pvcTLG was greater than SUVmax, SUVmean and pvcSUVmean [TLG: 253.9 to 106.9, -81.4%; P = 0.052 and pvcTLG: 368.9 to 153.3, -58.4%; P = 0.04]. In addition, overall survival (OS) was shorter in patients with pre-RIT pvcTLG more than 644 compared to those below this value (log-rank P < 0.01). In univariate Cox regression for OS, a higher baseline pvcTLG was a significant prognostic factor (HR: 6.8, P = 0.02). Our results showed that pre-treatment pvcTLG was the best predictor of OS in patients with relapsing/refractory NHL following RIT.