18F-Fluoride PET/CT Scan for Quantification of Bone Metabolism in the Inner Ear in Patients With Otosclerosis—A Pilot Study

Incidentally Discovered 99mTc-MDP Uptake on Bone Scan in Otosclerosis

Otosclerosis is a poorly understood clinical entity causing progressive conductive hearing loss. Here we present the first known evidence of otosclerosis demonstrating 99mTc-MDP uptake on bone scan. This presents an opportunity to explore the role of nuclear medicine imaging in early detection, staging, and even informing treatment and prognosis of this condition. Laryngoscope, 134:4763-4765, 2024.

Novel Musculoskeletal and Orthopedic Applications of 18F-Sodium Fluoride PET

PET imaging with ¹⁸F-sodium fluoride (NaF), combined with computed tomography or magnetic resonance, is a sensitive method of assessing bone turnover. Although NaF-PET is gaining popularity in detecting prostate cancer metastases to bone marrow, osseous changes represent secondary effects of cancer cell growth. PET tracers more appropriate for assessing prostate cancer metastases directly portray malignant activity and include ¹⁸F-fluciclovine and prostatic specific membrane antigen ligands. Recent studies investigating NaF-PET suggest utility in the assessment of benign musculoskeletal disorders. Emerging applications in assessing traumatic injuries, joint disease, back pain, orthopedic complications, and metabolic bone disease are discussed.

Comparison of the Variability of SUV Normalized by Skeletal Volume with the Variability of SUV Normalized by Body Weight in 18F-Fluoride PET/CT

Our objective was to test the hypothesis that variability in SUV normalized by skeletal volume (SV) in ¹⁸F-fluoride (¹⁸F-NaF) PET/CT studies is lower than variability in SUV normalized by body weight (BW). Methods: The mean SUV (SUV_mean) was obtained for whole skeletal volume of interest (wsVOI) in 163 selected ¹⁸F-NaF PET/CT studies. These studies were performed to investigate bone metastases and were considered to have normal results. SUV_mean was calculated with normalization by BW (BW SUV_mean), with normalization by SV (SV SUV_mean), and without normalization (WN SUV_mean). The total SV for each patient was also estimated on the basis of the wsVOI defined on the CT component of the PET/CT study. SUV_mean variability for each patient was estimated as the absolute value of the difference between the SUV_mean for the patient and the mean of the SUV_mean for the whole group of patients, divided by the mean of the SUV_mean for the whole group of patients. The variabilities of SUV_mean calculated by the 3 methods were compared using a paired 1-tailed Wilcoxon test. Results: The mean variability for the BW, SV, and WN SUV_mean was 0.16, 0.13, and 0.16, respectively. There were statistically significant differences between SV and BW SUV_mean variability (P = 0.03) and between SV and WN SUV_mean variability (P < 0.01). There was no statistically significant difference between BW and WN SUV_mean variability (P = 0.4). Conclusion: In patients with normal ¹⁸F-NaF PET/CT results, SV SUV_mean presents lower variability than BW SUV_mean.

Normal bone and soft tissue distribution of fluorine-18-sodium fluoride and artifacts on 18F-NaF PET/CT bone scan: a pictorial review

Fluorine-18-sodium fluoride (F-NaF) PET/CT is a relatively new and high-resolution bone imaging modality. Since the use of F-NaF PET/CT has been increasing, it is important to accurately assess the images and be aware of normal distribution and major artifacts. In this pictorial review article, we will describe the normal uptake patterns of F-NaF in the bone tissues, particularly in complex structures, as well as its physiologic soft tissue distribution and certain artifacts seen on F-NaF PET/CT images.

18F-NaF PET/CT for the evaluation of temporomandibular joint disorder

AIM

To investigate the usefulness of a quantitative parameter (maximum standardised uptake value [SUVmax]) of ¹⁸F-sodium fluoride (NaF) positron-emission tomography (PET)/computed tomography (CT) for the evaluation of temporomandibular joint (TMJ) disorder (TMD).

MATERIALS AND METHODS

Seventy-six TMD patients (male: female=14:62, age=40.3±17.1 years, bilateral: unilateral=40:36) with 152 TMJs were enrolled. The ¹⁸F-NaF PET/CT parameter (SUVmax) was compared with the presence of TMJ arthralgia (arthralgic=86, non-arthralgic=66) and clinical subtypes based on the Research Diagnostic Criteria for TMD Axis I (TMD osteoarthritis=49, non-TMD osteoarthritis=67, and asymptomatic TMJ=36). Splint therapy was applied to 48 patients for 6 months without considering ¹⁸F-NaF PET/CT findings. Post-splint therapy ¹⁸F-NaF PET/CT was performed in 32 patients and clinical responses to the therapy were classified into improvement (n=33), no change (n=10), or aggravation (n=7) for 50 TMJs excluding asymptomatic TMJs (n=14).

RESULTS

SUVmax was significantly greater in arthralgic TMJs than in non-arthralgic TMJs (6.62±3.56 versus 4.32±1.53, p<0.0001). SUVmax was also significantly greater in TMD osteoarthritis (6.75±3.85) than in non-TMD osteoarthritis (5.21±2.70) and asymptomatic TMJs (4.86±1.99; p=0.0386). After splint therapy, SUVmax was significantly increased in aggravated TMJs (from 7.80±3.72 to 11.00±5.74, p=0.0156), whereas no significant change in SUVmax was observed in improved (from 6.16±2.68 to 6.09±2.60, p=0.4915) and unchanged (from 6.46±4.19 to 6.77±4.32, p=0.3223) TMJs.

CONCLUSIONS

¹⁸F-NaF PET/CT is a useful imaging tool for TMD evaluation because SUVmax showed a fair diagnostic performance for arthralgic TMJ and TMD osteoarthritis, and a correlation with the therapeutic response.

SUV Normalized by Skeletal Volume on 18F-Fluoride PET/CT Studies

OBJECTIVE

To propose a technique for SUV normalization on F-fluoride PET/CT (F-NaF) studies based on skeletal volume and to compare the SUVs normalized by this technique with the ones normalized by body weight.

METHODS

SUVs were obtained in volumes of interest (VOIs) in proximal diaphyseal regions of the right humerus (HD) and right femur (FD) in 12 selected F-NaF studies. The 12 studies presented both regions considered normal by visual examination on PET and CT and were performed in patients presenting body weight below 50 kg (B50) or above 90 kg (A90) (6 patients in each group). The maximum SUVs were calculated in these 2 bone regions in both groups of patients using body weight (SUV BW) and skeletal volume (SUV SV) methodologies. The total skeletal volume for each patient was estimated based on whole skeletal VOIs automatically defined on the CT component of the PET/CT study. The maximum SUVs calculated using the 2 methodologies were compared.

RESULTS

The maximum SUVs BW were statistically higher in the group A90 in both regions, with a P < 0.001 and P < 0.008 for FD and HD, respectively. The maximum SUVs SV in the 2 regions were not statistically different between the groups B50 and A90, P values of 0.27 and 0.87 for FD and HD, respectively.

CONCLUSIONS

The SUVs normalized by skeletal volume present similar results in groups of patients with extremes of body weight. Therefore, this methodology could be more adequate than the one normalized by body weight to semiquantitatively analyze F-NaF studies.

Receiver operating characteristic (ROC) curve for classification of (18)F-NaF uptake on PET/CT

OBJECTIVE

To assess the cutoff values established by ROC curves to classify (18)F-NaF uptake as normal or malignant.

MATERIALS AND METHODS

PET/CT images were acquired 1 hour after administration of 185 MBq of (18)F-NaF. Volumes of interest (VOIs) were drawn on three regions of the skeleton as follows: proximal right humerus diaphysis (HD), proximal right femoral diaphysis (FD) and first vertebral body (VB1), in a total of 254 patients, totalling 762 VOIs. The uptake in the VOIs was classified as normal or malignant on the basis of the radiopharmaceutical distribution pattern and of the CT images. A total of 675 volumes were classified as normal and 52 were classified as malignant. Thirty-five VOIs classified as indeterminate or nonmalignant lesions were excluded from analysis. The standardized uptake value (SUV) measured on the VOIs were plotted on an ROC curve for each one of the three regions. The area under the ROC (AUC) as well as the best cutoff SUVs to classify the VOIs were calculated. The best cutoff values were established as the ones with higher result of the sum of sensitivity and specificity.

RESULTS

The AUCs were 0.933, 0.889 and 0.975 for UD, FD and VB1, respectively. The best SUV cutoffs were 9.0 (sensitivity: 73%; specificity: 99%), 8.4 (sensitivity: 79%; specificity: 94%) and 21.0 (sensitivity: 93%; specificity: 95%) for UD, FD and VB1, respectively.

CONCLUSION

The best cutoff value varies according to bone region of analysis and it is not possible to establish one value for the whole body.

Normal SUV values measured from NaF18- PET/CT bone scan studies

Objectives

Cancer and metabolic bone diseases can alter the SUV. SUV values have never been measured from healthy skeletons in NaF18-PET/CT bone scans. The primary aim of this study was to measure the SUV values from normal skeletons in NaF18-PET/CT bone scans.

Methods

A retrospective study was carried out involving NaF18- PET/CT bone scans that were done at our institution between January 2010 to May 2012. Our excluding criteria was patients with abnormal real function and patients with past history of cancer and metabolic bone diseases including but not limited to osteoporosis, osteopenia and Paget’s disease. Eleven studies met all the criteria.

Results

The average normal SUV_max values from 11 patients were: cervical vertebrae 6.84 (range 4.38–8.64), thoracic vertebrae 7.36 (range 6.99–7.66), lumbar vertebrae 7.27 (range 7.04–7.72), femoral head 2.22 (range 1.1–4.3), humeral head 1.82 (range 1.2–2.9), mid sternum 5.51 (range 2.6–8.1), parietal bone 1.71 (range 1.3–2.4).

Conclusion

According to our study, various skeletal sites have different normal SUV values. SUV values can be different between the normal bones and bones with tumor or metabolic bone disease. SUV can be used to quantify NaF-18 PET/CT studies. If the SUV values of the normal skeleton are known, they can be used in the characterization of bone lesions and in the assessment of treatment response to bone diseases.