Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) combined with conventional MRI for the detection of skull-base invasion in nasopharyngeal carcinoma: comparison with 18F-sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT).

Background: The extent of skull base invasion (SBI) in nasopharyngeal carcinoma (NPC) directly impacts tumor staging, treatment strategies, and prognosis assessment for NPC patients, emphasizing the critical need for prompt diagnosis and precise assessment of invasion. Thus, we aimed to integrate the advantages of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) and conventional magnetic resonance imaging (cMRI), and assess their combined diagnostic efficacy versus that of 18F-sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT) for detecting SBI in NPC patients. Methods: The study prospectively and randomly recruited 62 patients newly diagnosed with NPC by pathological biopsy at the Cancer Center of Affiliated Hospital of Guangdong Medical University from January 2021 to September 2022. All patients underwent baseline cMRI, IVIM-DWI, and PET/CT scans. The IVIM-DWI analysis included 3 primary parameters: true diffusion coefficient (D), pseudodiffusion coefficient (D*), and pseudodiffusion fraction (f). SBI was defined as the involvement of any substructure confirmed by follow-up MRI and clinical symptoms. Inter-observer agreement was evaluated utilizing the intraclass correlation coefficients (ICC) and kappa coefficients. Receiver operating characteristic (ROC) curve was used to evaluate the diagnostic performance of cMRI, IVIM-DWI plus cMRI, and PET/CT. DeLong test was used to compare the areas under the curve (AUC) of the 3 modalities. Results: Excellent inter-observer reliability was observed (range, 0.841-0.946). Among the IVIM-DWI parameters, D* + f demonstrated comparable accuracy to D + D* + f (AUC 0.906 vs. 0.904; sensitivity 88.9% vs. 89.8%; specificity 92.3% vs. 91.0%). IVIM-DWI plus cMRI yielded an overall AUC of 0.947, sensitivity of 92.6%, and specificity of 96.8%, surpassing cMRI alone with an AUC of 0.914 (P=0.025), sensitivity of 91.2%, and specificity of 91.7%, as well as 18F-NaF PET/CT with an AUC of 0.852 (P<0.001), sensitivity of 80.1%, and specificity of 90.4%. In detecting substructures of SBI, IVIM-DWI plus cMRI showed superior performance compared to 18F-NaF PET/CT within the petrous part of the temporal bone (AUC 0.968 vs. 0.871, P=0.011; sensitivity 93.5% vs. 87.1%, specificity 100% vs. 87.1%), pterygopalatine fossa (AUC 0.935 vs. 0.831, P=0.032; sensitivity 93.9% vs. 69.7%, specificity 93.1% vs. 96.6%), and foramen ovale (AUC 0.885 vs. 0.710, P=0.019; sensitivity 76.9% vs. 61.5%, specificity 100% vs. 80.6%). Conclusions: IVIM-DWI plus cMRI can accurately detect SBI and the substructures in NPC, providing a valuable reference for personalized treatment strategies and precise prognosis assessment.

Pamidronate for pain in adult chronic nonbacterial osteitis: protocol of a randomized, double-blind, placebo-controlled trial.

Chronic nonbacterial osteitis (CNO) is a rare auto-inflammatory bone disease affecting children and adults. Adult CNO is characterized by painful bone lesions, primarily of the anterior chest wall. There is no approved therapy for adult CNO. Current off-label treatments include intravenous bisphosphonates, which have been shown to alleviate pain through decreasing bone turnover. However, no adequately powered randomized controlled trials (RCTs) have been conducted. This double-blind, placebo-controlled RCT investigates the efficacy of intravenous pamidronate to decrease bone pain in adult CNO patients. Recruiting at the Dutch national referral center for CNO, adult patients with persistent bone pain despite non-steroidal anti-inflammatory drugs, or optionally other standard-of-care treatments are randomized to receive two courses of intravenous pamidronate (at 0 and 3 mo, 30 mg daily, on 3 consecutive d) or placebo. From 6 mo onwards, all patients receive open-label pamidronate for another two courses. The primary outcome is change in score for maximum pain from 0 to 6 mo. Secondary outcomes include change in quantitative intralesional bone turnover as measured on sodium-fluoride positron emission computed tomography ([18F]NaF-PET/CT), inflammation markers, shoulder function, general health, quality of life, fatigue, physical, and work activity. The pamidronate for pain in adult chronic nonbacterial osteitis trial addresses the need for evidence-based treatments in adult CNO. Results will directly impact daily clinical practice, either validating the use of intravenous pamidronate in CNO at the dose used in this trial or prompting the search for alternative regimens or agents. This trial was registered in EudraCT (reference 2020-001068-27) and the Dutch Trial Register (reference NL68020.058.20).

Complimentary Role of [18F]FDG and [18F]NaF-PET/CT in Evaluating Synchronous Thyroid Carcinoma and Parathyroid Adenoma with Brown Tumors.

We herein present a patient initially suspected of multiple lytic skeletal metastasis of unknown primary on anatomical imaging. Metabolic imaging by [18F]-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) detected focal [18F]FDG uptake in the right thyroid nodule, mild [18F]FDG uptake in soft tissue lesion in the left inferior parathyroid region, and multiple nonavid osteolytic skeletal lesions. Fine-needle aspiration cytology of the right thyroid nodule showed papillary thyroid carcinoma (PTC). The patient had raised serum parathyroid hormone and serum calcium levels, suggesting parathyroid disease. [18F]-sodium fluoride (NaF)-PET/CT showed a metabolic superscan pattern of hyperparathyroidism with brown tumors rather than metastatic lytic skeletal lesions. Patient underwent total thyroidectomy and bilateral central compartment clearance, along with soft tissue lesion resection in the left inferior parathyroid region. Finally, histopathology confirmed PTC classical variant with no aggressive histology features (pT1N0) for thyroid nodule and parathyroid adenoma for soft tissue lesion in the left inferior parathyroid region. The findings of the [18F]FDG and [18F]NaF-PET/CT imaging were helpful for making a final diagnosis of synchronous thyroid cancer and parathyroid adenoma, which in turn guided the appropriate treatment strategy.

The potential advantages of 18F sodium fluoride positron emission tomography-computed tomography for clinical staging and management planning in patients with nasopharyngeal carcinoma.

Background: The staging and treatment planning of nasopharyngeal carcinoma (NPC) face challenges due to limited sensitivity of conventional imaging. 18F-sodium fluoride (18F-NaF) positron emission tomography-computed tomography (PET/CT) offers potential advantages in detecting early bone involvement. This retrospective cohort study aimed to assess the potential advantage of 18F-NaF PET/CT for clinical staging and management planning in patients with NPC and to compare 18F-NaF PET/CT findings with those of conventional imaging modalities. Methods: We enrolled a cohort of patients with NPC who underwent 18F-NaF PET/CT at our PET/CT center between July 1, 2017, and June 30, 2021, and analyzed the findings of 18F-NaF PET/CT and conventional imaging modalities. Data from multidisciplinary team discussions on clinical staging and management planning both before and after 18F-NaF PET/CT were recorded. Additionally, any changes in clinical staging and management planning following 18F-NaF PET/CT were documented. Results: A total of 58 patients were included in this study. After 18F-NaF PET/CT imaging, clinical tumor-node-metastasis (TNM) staging was observed to have changed in seven cases (12.1%). Among these, four cases had changes in T stage and three cases in the M stage. Additionally, changes in clinical management plans were observed in eight patients (13.8%). Changes due the results of 18F-NaF PET/CT included three cases with major modification (two cases switched from curative treatment to palliative treatment, and one case switched from palliative treatment to curative treatment) and five cases with minor changes. The minor changes involved alteration to the radiotherapy target volume (three cases with an increased target volume and one case with a reduced target area). Furthermore, one case required an alteration to the radiotherapy strategy for local bone involvement. Conclusions: The use of 18F-NaF PET/CT in patients newly diagnosed with NPC may offer potential advantages for clinical staging and treatment planning, enabling physicians to select a more individualized treatment approach.

Assessment of regional and total skeletal metabolism using 18F-NaF PET/CT in patients with chronic kidney disease.

OBJECTIVE: The study aims to assess regional and total bone metabolic activity in patients with chronic kidney disease using Na[18F]F PET and correlation between semi-quantitative indices and blood parameters. METHODS: Seventy-two subjects (mean age 61.8 ± 13.8 years) were included. Of these 24/72 patients had end-stage renal disease (ESRD) (GFR < 15 mL/min/1.73 m2), 38/72 had chronic kidney disease (CKD) (GFR between 60 and 15 mL/min/1.73 m2), and 10/72 were controls with normal renal function. All subjects underwent Na[18F]F PET-CT with a dose activity of 0.06 mCi/Kg. Regional and total skeletal metabolism were assessed with mean SUVs in a skeletal volume of interest (VOI), bone to soft tissue index (B/S), global SUV mean (GSUV mean) of the whole bone, and uptake in the femoral neck. RESULTS: Statistically significant differences were observed in a number of 18F-NaF metrics like femoral neck metabolism in CKD and ERSD groups in comparison to control in right (P = 0.003) and left femur (P = 0.006), bone to soft tissue index in the femur (P = 0.016) and GSUV5 (P = 0.006). There is also a significant difference in SUV mean in lumbar vertebrae (L1-L4) among CKD, ESRD, and controls. There was a moderate correlation between 18F-NaF PET scan uptake and blood parameters such as ALP and PTH. Na[18F]F uptake parameters were significantly different in low versus high bone turnover state. CONCLUSIONS: The assessment of total skeleton and regional metabolism and bone turnover in CKD patients is feasible with Na[18F]F PET. Na[18F]F can help to detect early changes in bone metabolism and assess the progression of bone disease in this complex condition. Quantification with Na[18F]F PET might provide better assessment of the bone turnover. The difference in Na[18F]F uptake in CKD compared to controls is likely related to a change in bone turnover which, however, requires further validation.

Bilateral Carotid Artery Molecular Calcification Assessed by [18F] Fluoride PET/CT: Correlation with Cardiovascular and Thromboembolic Risk Factors.

Atherosclerosis, a leading cause of mortality and morbidity worldwide, involves inflammatory processes that result in plaque formation and calcification. The early detection of the molecular changes underlying these processes is crucial for effective disease management. This study utilized positron emission tomography/computed tomography (PET/CT) with [18F] sodium fluoride (NaF) as a tracer to visualize active calcification and inflammation at the molecular level. Our aim was to investigate the association between cardiovascular risk factors and [18F] NaF uptake in the left and right common carotid arteries (LCC and RCC). A cohort of 102 subjects, comprising both at-risk individuals and healthy controls, underwent [18F] NaF PET/CT imaging. The results revealed significant correlations between [18F] NaF uptake and cardiovascular risk factors such as age (ß = 0.005, 95% CI 0.003-0.008, p < 0.01 in LCC and ß = 0.006, 95% CI 0.004-0.009, p < 0.01 in RCC), male gender (ß = -0.08, 95% CI -0.173--0.002, p = 0.04 in LCC and ß = -0.13, 95% CI -0.21--0.06, p < 0.01 in RCC), BMI (ß = 0.02, 95% CI 0.01-0.03, p < 0.01 in LCC and ß = 0.02, 95% CI 0.01-0.03, p < 0.01 in RCC), fibrinogen (ß = 0.006, 95% CI 0.0009-0.01, p = 0.02 in LCC and ß = 0.005, 95% CI 0.001-0.01, p = 0.01), HDL cholesterol (ß = 0.13, 95% CI 0.04-0.21, p < 0.01 in RCC only), and CRP (ß = -0.01, 95% CI -0.02-0.001, p = 0.03 in RCC only). Subjects at risk showed a higher [18F] NaF uptake compared to healthy controls (one-way ANOVA; p = 0.02 in LCC and p = 0.04 in RCC), and uptake increased with estimated cardiovascular risk (one-way ANOVA, p < 0.01 in LCC only). These findings underscore the potential of [18F] NaF PET/CT as a sensitive tool for the early detection of atherosclerotic plaque, assessment of cardiovascular risk, and monitoring of disease progression. Further research is needed to validate the technique's predictive value and its potential impact on clinical outcomes.

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.

Prospective study of Na[18F]F PET/CT for cancer staging in morbidly obese patients compared with [99mTc]Tc-MDP whole-body planar, SPECT and SPECT/CT.

PURPOSE: This prospective study aims to assess the diagnostic test characteristics of Na[18F]F PET/CT for the skeletal staging of cancer in morbidly obese patients compared with 99mTc-methylene diphosphonate (MDP), whole-body planar (WBS), SPECT, and SPECT/CT acquisitions. MATERIAL AND METHODS: One hundred seventeen obese patients (BMI 46.5 ± 6.1 kg/m2 and mean age, 59.0 years; range 32-89 years) with BMI > 40 kg/m2 were prospectively enrolled and underwent [99mTc]Tc-MDP WBS, SPECT, SPECT/CT, and Na[18F]F PET/CT within two weeks for the osseous staging of a malignancy. Images were assessed qualitatively using a 3-point scale. Patient and lesion-based diagnostic test characteristics were estimated using an optimistic and pessimistic dichotomization method. RESULTS: Bone metastases were confirmed in 44 patients. Patient-based optimistic diagnostic test characteristics were (sensitivity, specificity, overall accuracy): Na[18F]F PET/CT (95.5%, 95.9%, 95.7%), [99mTc]Tc-MDP WBS (52.3%, 71.2%, 64.1%), SPECT (61.4%, 80.8%, 73.5%) and SPECT/CT (65.9%, 91.8%, 82.1%). Lesion-based optimistic diagnostic test characteristics were: Na[18F]F PET/CT (97.7%, 97.9%, 97.7%), [99mTc]Tc-MDP WBS (39%, 67%, 48.9%), SPECT (52.9%, 93.6%, 67.3%) and SPECT/CT (65.9%, 91.8%, 82.1%). There was no significant difference in the specificity of Na[18F]F and SPECT/CT. All other pairwise comparisons were significant (p<.001). ROC curve analysis showed a high overall accuracy of Na[18F]F with significantly higher AUCs for Na[18F]F PET/CT compared to [99mTc]Tc-MDP WBS, SPECT, and SPECT/CT on both patient and lesion-based analysis (p<.001). Moreover, Na[18F]F PET/CT changed patient management in 38% of patients. CONCLUSIONS: Na[18F]F PET/CT may be the preferred imaging modality for skeletal staging in morbidly obese patients. The technique provides excellent diagnostic test characteristics superior to [99mTc]Tc-MDP bone scan (including SPECT/CT), impacts patient management, has an acceptable radiation exposure profile, and is well-tolerated. Further cost-effectiveness evaluations are warranted.

Therapy-induced bone changes in oncology imaging with 18F-sodium fluoride (NaF) PET-CT.

18F-Sodium fluoride (18F-NaF) is a PET tracer that is mostly used in the evaluation of bone metastasis in oncology cases. Recently, 18F-NaF PET/CT is gaining wide popularity owing to its higher sensitivity over the other conventional bone tracer with higher and rapid single-pass extraction, negligible plasma protein binding, rapid blood, and renal clearance. In the era of constant evolution of cancer therapy regimens, considerable bone health impact is seen in the form of avascular necrosis, insufficiency fractures, among others. A significant number of these therapy-induced changes show high bone turnover and thereby 18F-NaF accumulation, mimicking metastatic lesions. This article summarizes and illustrates the pattern and morphological features of 18F-NaF PET/CT findings in these changes in the context of clinical and therapeutic history.

Update on imaging in chronic kidney disease-mineral and bone disorder: promising role of functional imaging.

Disorders of mineral metabolism and bone disease are common complications in chronic kidney disease (CKD) patients and are associated with increased morbidity and mortality. Bone biopsies, bone scintigraphy, biochemical markers, and plain films have been used to assess bone disorders and bone turnover. Of these, functional imaging is less invasive than bone/marrow sampling, more specific than serum markers and is therefore ideally placed to assess total skeletal metabolism. 18F-sodium fluoride (NaF) PET/CT is an excellent bone-seeking agent superior to conventional bone scan in CKD patients due to its high bone uptake, rapid single-pass extraction, and minimal binding to serum proteins. Due to these properties, 18F-NaF can better assess the skeletal metabolism on primary diagnosis and following treatment in CKD patients. With the increased accessibility of PET scanners, it is likely that PET scanning with bone-specific tracers such as 18F-NaF will be used more regularly for clinical assessment and quantitation of bone kinetics. This article describes the pattern of scintigraphic/functional appearances secondary to musculoskeletal alterations that might occur in patients with CKD.

Longitudinal analysis of atherosclerotic plaques evolution: an 18F-NaF PET/CT study.

PURPOSE: 18F-NaF-PET/CT can detect mineral metabolism within atherosclerotic plaques. To ascertain whether their 18F-NaF uptake purports progression, this index was compared with subsequent morphologic evolution. METHODS: 71 patients underwent two consecutive 18F-NaF-PET/CTs (PET1/PET2). In PET1, non-calcified 18F-NaF hot spots were identified in the abdominal aorta. Their mean/max HU was compared with those of a non-calcified control region (CR) and with corresponding areas in PET2. A target-to-background ratio (TBR), mean density (HU), and calcium score (CS) were calculated on calcified atherosclerotic plaques in PET1 and compared with those in PET2. A VOI including the entire abdominal aorta was drawn; mean TBR and total CS were calculated on PET1 and compared with those PET2. RESULTS: Hot spots in PET1 (N = 179) had a greater HU than CR (48 ± 8 vs 37 ± 9, P < .01). Mean hot spots HU increased to 59 ± 12 in PET2 (P < .001). New calcifications appeared at the hot spots site in 73 cases (41%). Baseline atherosclerotic plaque's (N = 375) TBR was proportional to percent HU and CS increase (P < .01 for both). Aortic CS increased (P < .001); the whole-aorta TBR in PET1 correlated with the CS increase between the baseline and the second PET/CT (R = .63, P < .01). CONCLUSIONS: 18F-NaF-PET/CT depicts the early stages of plaques development and tracks their evolution over time.

18F-Sodium Fluoride (NaF) Uptake in Calcified Bladder Carcinoma: Double Density Sign

18F-Sodium fluoride (NaF) is primarily a skeletal imaging agent which can be localized in extraosseous calcified foci. Here, we describe a case of a 48-year-old man with bladder carcinoma referred for staging using 18F-NaF positron emission tomography/computed tomography (PET/CT). 18F-NaF PET/CT detected a calcified soft tissue mass in the urinary bladder. Extraosseous 18F-NaF uptake is often encountered and these non-osseous findings could possibly provide important diagnostic information. Thus, recognition of extraosseous 18F-NaF activity has implications for accurate staging and management.

A longitudinal 18F-fluorodeoxyglucose (18F-FDG) and 18F-sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT) study in apolipoprotein E (ApoE) knockout rats fed with a Western diet.

BACKGROUND: Inflammation and vascular calcification are risk factors for cardiovascular disease, but their relationship is still under investigation. This longitudinal in vivo study aimed to monitor inflammation and calcification during the formation of atherosclerotic plaques in apolipoprotein E knockout (ApoE-/-) rats by 18F-fluorodeoxyglucose (18F-FDG) and 18F-sodium fluoride (18F-NaF) positron emission tomography/computed tomography (PET/CT). METHODS: In the ApoE group, male ApoE-/- rats were fed a high-fat Western diet from 13 weeks of age, and in the normal group, male SD rats of the same age were fed a normal diet. A longitudinal PET/CT study using 18F-FDG and 18F-NaF was performed at 12, 27, and 46 weeks of age. T1-weighted magnetic resonance imaging (MRI) was used as an atlas template, and the uptake of the tracers in the cardiovascular system was analyzed based on atlas 3D geometry volumes-of-interest (VOIs). After the PET/CT study, pathological and immunohistochemical examinations were performed on the corresponding lesions. RESULTS: The body weight and plasma cholesterol levels of the ApoE-/- rats increased with time, and at each time point, significantly higher body weight and plasma cholesterol levels were observed in the ApoE-/- rats than in the normal rats. PET/CT showed that in ApoE-/- rats, the uptake of 18F-FDG was found in the aortic arch, while the uptake of 18F-NaF was found in pulmonary arteries. The uptake of the two tracers in the ApoE group increased with time. Extensive early stage of atherosclerotic plaques, with high expression of CD68 and alizarin red, were observed in pulmonary arteries. However, only a thickened intima with very high expression of hypoxia-inducible factor-1 alpha (HIF-1α) was seen in the aortic arch. CONCLUSIONS: In ApoE-/- rats fed a high-fat Western diet, early atherosclerotic lesions developed in the pulmonary arteries; however, 18F-FDG failed to accumulate in these lesions but to accumulate in the aortic arch with only neointimal hyperplasia and significantly high expression of hypoxia.

Changes in microarchitecture of atherosclerotic calcification assessed by 18F-NaF PET and CT after a progressive exercise regimen in hyperlipidemic mice.

BACKGROUND: Despite the association of physical activity with improved cardiovascular outcomes and the association of high coronary artery calcification (CAC) scores with poor prognosis, elite endurance athletes have increased CAC. Yet, they nevertheless have better cardiovascular survival. We hypothesized that exercise may transform vascular calcium deposits to a more stable morphology. METHODS: To test this, hyperlipidemic mice (Apoe-/-) with baseline aortic calcification were separated into 2 groups (n = 9/group) with control mice allowed to move ad-lib while the exercise group underwent a progressive treadmill regimen for 9 weeks. All mice underwent blood collections and in vivo 18F-NaF µPET/µCT imaging both at the start and end of the exercise regimen. At euthanasia, aortic root specimens were obtained for histomorphometry. RESULTS: Results showed that, while aortic calcification progressed similarly in both groups based on µCT, the fold change in 18F-NaF density was significantly less in the exercise group. Histomorphometric analysis of the aortic root calcium deposits showed that the exercised mice had a lower mineral surface area index than the control group. The exercise regimen also raised serum PTH levels twofold. CONCLUSION: These findings suggest that weeks-long progressive exercise alters the microarchitecture of atherosclerotic calcium deposits by reducing mineral surface growth, potentially favoring plaque stability.

18F-NaF PET/CT of Obese Patients on a Lutetium-Yttrium Oxyorthosilicate PET/CT System: Patient Dosimetry, Optimization of Injected Activity, and Acquisition Time.

18F-NaF PET/CT has a rapid single-pass extraction and fast clearance from soft tissues, resulting in a good target-to-background ratio. This study aimed to establish the optimum acquisition time and dosimetry for 18F-NaF PET/CT to evaluate bone metastases in obese patients. A secondary objective was to evaluate the impact of acquisition time on image quality, lesion detection rate, noise level, and radiation burden in this patient group. Methods: In total, 60 patients were included in the study (20 patients with a body mass index (BMI) of 30.0-34.9 kg/m2, 20 with a BMI of 35-39.9 kg/m2, and 20 with a BMI of >40 kg/m2). Images were acquired after intravenous injection of a 2.2 MBq/kg (0.06 mCi/kg) dose of 18F-NaF. Data were acquired in list mode using ordered-subset expectation maximization reconstruction. The raw data were rebinned to simulate scans with acquisition times of 2, 2.5, and 3 min per bed position. The scans were visually analyzed by 2 observers and scored by rank against a panel of parameters (overall image quality, noise level, background soft tissue, and lesion detectability), and the contrast-to-noise ratio (CNR) was calculated. Results: The mean CNR was 20.19 ± 8.39 for a 2-min acquisition, 21.03 ± 8.35 for 2.5 min, and 22.16 ± 8.37 for 3 min. There were no statistically significant differences in CNR among the 3 different acquisition durations (P > 0.05). Lesion delineation was excellent and independent of the acquisition time. All relevant lesions could be identified with all 3 acquisition times. A mean activity of 215.4 ± 31.3 MBq was injected, with estimated mean effective absorbed doses of 4.09 ± 0.59 mSv for 18F-NaF PET and 7.88 ± 1.66 mSv for CT alone. Conclusion: 18F-NaF PET/CT can be beneficial in obese patients because of its good pharmacokinetics. Optimal osseous staging can be achieved with relatively low doses and radiation burden. Lesion delineation was excellent regardless of acquisition time. However, it is recommended that an acquisition of 3 min per bed position be used in patients with a BMI of more than 40.

Incidental brain metastasis of breast cancer detected on 18F-Sodium Fluoride (NaF) PET-CT.

18F- Sodium Fluoride (NaF) is an excellent bone imaging agent used for skeletal staging but can also be localized in extra osseous calcifying lesions. We report a case of a 38-year-old woman with breast carcinoma referred for 18F-NaF PET-CT to evaluate possible metastatic lesions. 18F-NaF PET-CT detected incidental focal soft tissue tracer uptake in the right cerebellum with no sign of calcification seen on CT images. Subsequent MRI show high intensity signal lesion confirming brain metastasis. Extra osseous 18F-NaF uptake may provide important diagnostic information that might alter patient management.

When Limb Surgery Has Become the Only Life-Saving Therapy in FOP: A Case Report and Systematic Review of the Literature.

Fibrodysplasia ossificans progressiva (FOP) is a rare disease in which heterotopic ossification (HO) is formed in muscles, tendons and ligaments. Traumatic events, including surgery, are discouraged as this is known to trigger a flare-up with risk of subsequent HO. Anesthetic management for patients with FOP is challenging. Cervical spine fusion, ankylosis of the temporomandibular joints, thoracic insufficiency syndrome, restrictive chest wall disease, and sensitivity to oral trauma complicate airway management and anesthesia and pose life-threatening risks. We report a patient with FOP suffering from life-threatening antibiotic resistant bacterial infected ulcers of the right lower leg and foot. The anesthetic, surgical and postoperative challenges and considerations are discussed. In addition, the literature on limb surgeries of FOP patients is systemically reviewed. The 44 year-old female patient was scheduled for a through-knee amputation. Airway and pulmonary evaluation elicited severe abnormalities, rendering standard general anesthesia a rather complication-prone approach in this patient. Thus, regional anesthesia, supplemented with intravenous analgosedation and N2O-inhalation were performed in this case. The surgery itself was securely planned to avoid any unnecessary tissue damage. Postoperatively the patient was closely monitored for FOP activity by ultrasound and [18F]PET/CT-scan. One year after surgery, a non-significant amount of HO had formed at the operated site. The systematic review revealed seventeen articles in which thirty-two limb surgeries in FOP patients were described. HO reoccurrence was described in 90% of the cases. Clinical improvement due to improved mobility of the operated joint was noted in 16% of the cases. It should be noted, though, that follow-up time was limited and no or inadequate imaging modalities were used to follow-up in the majority of these cases. To conclude, if medically urgent, limb surgery in FOP is possible even when general anesthesia is not preferred. The procedure should be well-planned, alternative techniques or procedures should be tested prior to surgery and special attention should be paid to the correct positioning of the patient. According to the literature recurrent HO should be expected after surgery of a limb, even though it was limited in the case described.

Skin and Arterial Wall Deposits of 18F-NaF and Severity of Disease in Patients with Pseudoxanthoma Elasticum.

Pseudoxanthoma elasticum (PXE) is a genetic disease characterized by the calcification of elastin fibers. Our aim was to quantify vascular calcification in the arteries and the deposition of 18F-sodium-fluoride (18F-NaF) in the skin and vessel walls with positron emission tomography/computed tomography. This was an observational study including 18 patients with PXE. Vascular calcification was measured in Agatston units, and deposition in the skin and vessel walls was shown using target-to-background ratio (TBR). Severity of the disease was scored by Phenodex. We found higher vascular calcification in the popliteal, femoral, and aortic arch vessels compared to other vascular regions; however, the uptake of radiotracer was the highest in the aorta and femoral arteries. In the skin, the highest uptake was observed in the neck and the axillae. There was no significant association between 18F-NaF deposition in the arteries or skin and the global Phenodex score. In contrast, the Phenodex score was significantly associated in univariate analyses with the averaged vascular calcium score (p < 0.01). In the neck, patients with higher skin Phenodex scores exhibited higher radiotracer uptake. As a conclusion, because vascular calcification is physiological, our data suggested that the detection of cutaneous (neck) 18F-NaF deposits might serve to monitor the calcification process in the short-term for patients with PXE.

Can 18F-NaF PET/CT before Autologous Stem Cell Transplantation Predict Survival in Multiple Myeloma?

There is an unmet need for positron emission tomography (PET) radiotracers that can image bone disease in multiple myeloma (MM) in a more sensitive and specific way than the widely used 18F-fluorodeoxyglucose (18F-FDG). Sodium fluoride (18F-NaF) is a highly sensitive tracer of bone reconstruction, evolving as an important imaging agent for the assessment of malignant bone diseases. We attempted to investigate for the first time the prognostic significance of 18F-NaF PET/CT in newly diagnosed, symptomatic MM patients planned for autologous stem cell transplantation (ASCT). Forty-seven patients underwent dynamic and static PET/CT with 18F-NaF before treatment. After correlation with the respective findings on CT and 18F-FDG PET/CT that served as reference, the 18F-NaF PET findings were compared with established factors of high-risk disease, like cytogenetic abnormalities as well as bone marrow plasma cell infiltration rate. Furthermore, the impact of 18F-NaF PET/CT on progression-free survival (PFS) was analyzed. Correlation analysis revealed a moderate, significant correlation of the 18F-NaF parameters SUVaverage and K1 in reference tissue with bone marrow plasma cell infiltration rate. However, no significant correlation was observed regarding all other 18F-NaF PET parameters. Survival analysis revealed that patients with a pathologic 18F-NaF PET/CT have a shorter PFS (median = 36.2 months) than those with a physiologic scan (median = 55.6 months) (p = 0.02). Nevertheless, no quantitative 18F-NaF parameter could be shown to adversely affect PFS. In contrast, the respective analysis for quantitative dynamic 18F-FDG PET/CT revealed that the parameters SUVmax, fractional blood volume (VB), k3 and influx from reference tissue as well as SUVaverage from MM lesions had a significant negative impact on patient survival. The herein presented findings highlight the rather limited role of 18F-NaF PET/CT as a single PET approach in MM.