Association Between Time Since Administration of Pegylated G-CSF (Pegfilgrastim) and Bone Marrow Uptake on FDG PET/CT: Determination of a Minimum Interval.

BACKGROUND. Pegfilgrastim administration after chemotherapy increases bone marrow and spleen FDG uptake. Consensus is lacking regarding the optimal interval between pegfilgrastim administration and FDG PET/CT. OBJECTIVE. The purpose of this study was to assess the association between bone marrow and spleen uptake and the interval between pegfilgrastim administration and FDG PET/CT. METHODS. This retrospective study included 70 oncology patients (mean age, 64 ± 12 [SD] years; 48 men, 22 women) receiving chemotherapy who underwent FDG PET/CT (study scan) within 35 days after pegfilgrastim administration and who underwent additional FDG PET/CT at least 4 months before pegfilgrastim initiation or at least 3 months after last pegfilgrastim administration (reference scan). A nuclear medicine physician recorded the SUVmean for normal osseous structures and spleen and assessed bone marrow uptake using a 4-point visual scale (1, no abnormal uptake; 2, clinically insignificant uptake; 3, clinically significant uptake possibly interfering with interpretation; 4, clinically significant uptake expected to interfere with interpretation). RESULTS. Percentage change in SUVmean between reference and study scans significantly increased (p < .05) as the interval increased for five sites (i.e., for patients with interval of 7-13 vs 29-35 days, mean percentage change was 32.3% ± 18.2% vs 11.5% ± 17.3% for cervical vertebra, 42.2% ± 18.3% vs 21.3% ± 14.2% for thoracic vertebra, 47.2% ± 19.8% vs 19.1% ± 13.9% for lumbar vertebra, 51.1% ± 25.8% vs 12.7% ± 11.3% for pelvis, and 53.0% ± 25.6% vs 4.4% ± 14.1% for lower extremity); percentage change was not associated with the interval for upper extremity or spleen (p > .05). Visual uptake scores of 4, 3, 2, and 1 were observed in days 7-21, 12-22, 12-28, and 14-35, respectively. Percentage of patients with a score of 3 or 4 was 94.4% for days 7-13, 58.1% for days 14-21, 6.7% for days 22-28, and 0% for days 29-35. A total of 71.4% of patients had a score of 3 or 4 on day 7-21, whereas 4.8% had a score of 3 and 0% had a score of 4 on days 22-35. CONCLUSION. A visual uptake score of 3 or 4 was consistently observed throughout an approximately 3-week interval following pegfilgrastim administration, without any such case beyond 22 days. CLINICAL IMPACT. We recommend a preferred interval of at least 3 weeks after pegfilgrastim administration before PET/CT.

Clinical evaluation of TOF versus non-TOF on PET artifacts in simultaneous PET/MR: a dual centre experience.

PURPOSE: Our objective was to determine clinically the value of time-of-flight (TOF) information in reducing PET artifacts and improving PET image quality and accuracy in simultaneous TOF PET/MR scanning. METHODS: A total 65 patients who underwent a comparative scan in a simultaneous TOF PET/MR scanner were included. TOF and non-TOF PET images were reconstructed, clinically examined, compared and scored. PET imaging artifacts were categorized as large or small implant-related artifacts, as dental implant-related artifacts, and as implant-unrelated artifacts. Differences in image quality, especially those related to (implant) artifacts, were assessed using a scale ranging from 0 (no artifact) to 4 (severe artifact). RESULTS: A total of 87 image artifacts were found and evaluated. Four patients had large and eight patients small implant-related artifacts, 27 patients had dental implants/fillings, and 48 patients had implant-unrelated artifacts. The average score was 1.14 ± 0.82 for non-TOF PET images and 0.53 ± 0.66 for TOF images (p < 0.01) indicating that artifacts were less noticeable when TOF information was included. CONCLUSION: Our study indicates that PET image artifacts are significantly mitigated with integration of TOF information in simultaneous PET/MR. The impact is predominantly seen in patients with significant artifacts due to metal implants.

Prospective comparison of combined 18F-FDG and 18F-NaF PET/CT vs. 18F-FDG PET/CT imaging for detection of malignancy.

PURPOSE: Typically, (18)F-FDG PET/CT and (18)F-NaF PET/CT scans are done as two separate studies on different days to allow sufficient time for the radiopharmaceutical from the first study to decay. This is inconvenient for the patients and exposes them to two doses of radiation from the CT component of the examinations. In the current study, we compared the clinical usefulness of a combined (18)F-FDG/(18)F-NaF PET/CT scan with that of a separate (18)F-FDG-only PET/CT scan. METHODS: There were 62 patients enrolled in this prospective trial. All had both an (18)F-FDG-alone PET/CT scan and a combined (18)F-FDG/(18)F-NaF PET/CT scan. Of the 62 patients, 53 (85%) received simultaneous tracer injections, while 9 (15%) received (18)F-NaF subsequent to the initial (18)F-FDG dose (average delay 2.2 h). Images were independently reviewed for PET findings by two Board-Certified nuclear medicine physicians, with discrepancies resolved by a third reader. Interpreters were instructed to only report findings that were concerning for malignancy. Reading the (18)F-FDG-only scan first for half of the patients controlled for order bias. RESULTS: In 15 of the 62 patients (24%) neither the (18)F-FDG-only PET/CT scan nor the combined (18)F-FDG/(18)F-NaF PET/CT scan identified malignancy. In the remaining 47 patients who had PET findings of malignancy, a greater number of lesions were detected in 16 of 47 patients (34%) using the combined (18)F-FDG/(18)F-NaF PET/CT scan compared to the (18)F-FDG-only PET/CT scan. In 2 of these 47 patients (4%), the (18)F-FDG-only scan demonstrated soft tissue lesions that were not prospectively identified on the combined study. In 29 of these 47 patients (62%), the combined scan detected an equal number of lesions compared to the (18)F-FDG-only scan. Overall, 60 of all the 62 patients (97%) showed an equal or greater number of lesions on the combined scan than on the (18)F-FDG-only scan. CONCLUSION: The current study demonstrated that (18)F-FDG and (18)F-NaF can be combined in a single PET/CT scan by administering the two radiopharmaceuticals simultaneously or in sequence on the same day. In addition to patient convenience and reduced radiation exposure from the CT component, the combined (18)F-FDG/(18)F-NaF PET/CT scan appeared to increase the sensitivity for detection of osseous lesions compared to the (18)F-FDG-only PET/CT scan in the studied population.

Initial investigation of ¹8F-NaF PET/CT for identification of vertebral sites amenable to surgical revision after spinal fusion surgery.

PURPOSE: A pilot study was performed in patients with recurrent back pain after spinal fusion surgery to evaluate the ability of (18)F-NaF PET/CT imaging to correctly identify those requiring surgical intervention and to locate a site amenable to surgical intervention. METHODS: In this prospective study 22 patients with recurrent back pain after spinal surgery and with equivocal findings on physical examination and CT were enrolled for evaluation with (18)F-NaF PET/CT. All PET/CT images were prospectively reviewed with the primary objective of identifying or ruling out the presence of lesions amenable to surgical intervention. The PET/CT results were then validated during surgical exploration or clinical follow-up of at least 15 months. RESULTS: Abnormal (18)F-NaF foci were found in 16 of the 22 patients, and surgical intervention was recommended. These foci were located at various sites: screws, cages, rods, fixation hardware, and bone grafts. In 6 of the 22 patients no foci requiring surgical intervention were found. Validation of the results by surgery (15 patients) or on clinical follow-up (7 patients) showed that (18)F-NaF PET/CT correctly predicted the presence of an abnormality requiring surgical intervention in 15 of 16 patients and was falsely positive in 1 of 16. CONCLUSION: In this initial investigation, (18)F-NaF PET/CT imaging showed potential utility for evaluation of recurrent symptoms after spinal fusion surgery by identifying those patients requiring surgical management.

Simultaneous PET/MRI in the Evaluation of Breast and Prostate Cancer Using Combined Na[18F] F and [18F]FDG: a Focus on Skeletal Lesions.

PURPOSE: The purpose of this study is to prospectively evaluate the performance of sodium 18F]fluoride (Na[18F]F)/2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) simultaneous time-of-flight enabled positron emission tomography (PET)/magnetic resonance imaging (MRI) for the detection of skeletal metastases in selected patients with advanced breast and prostate cancers. PROCEDURE: The institutional review board approved this HIPAA-compliant protocol. Written informed consent was obtained from each patient. A total of 74 patients (23 women and 51 men with breast and prostate cancer, respectively) referred for standard-of-care whole-body bone scintigraphy (WBBS) were enrolled in this prospective study. All patients underwent a [99mTc]methyldiphosphonate ([99mTc]MDP) WBBS followed by Na[18F]F/[18F]FDG PET/MRI. Lesions detected by each imaging modality were tabulated and a lesion-based and patient-based analysis was conducted. RESULTS: On a patient-based analysis, [99mTc]MDP WBBS identified skeletal lesions in 37 patients and PET/MRI in 45 patients. On a lesion-based analysis, WBBS identified a total of 81 skeletal lesions, whereas PET/MRI identified 140 lesions. Additionally, PET/MRI showed extra-skeletal lesions in 19 patients, including lymph nodes (16), prostate (4) lung (3), and liver (2) lesions. CONCLUSIONS: The ability of Na[18F]F/[18F]FDG PET/MRI to identify more skeletal lesions than 99mTc-MDP WBBS and to additionally identify extra-skeletal disease may be beneficial for patient care and represent an alternative to the single modalities performed separately. Na[18F]F/[18F]FDG PET/MRI is a promising approach for evaluation of skeletal and extra-skeletal lesions in a selected population of breast and prostate cancer patients.

Assessment of skeletal tumour burden on 18F-NaF PET/CT using a new quantitative method.

PURPOSE: The purpose of this study was to test a method of quantifying skeletal tumour burden with F-NaF PET/CT. PATIENTS AND METHODS: We retrospectively reviewed the charts of 117 patients who underwent F-NaF PET/CT for the detection of bone metastases, 68 women and 49 men, 16-82 years old (mean±SD: 62.9±10.7 years). Mean standardized uptake values (SUVmean) were measured in five anatomic sites to evaluate normal skeleton activity. The influence of sex and age was investigated. Skeletal tumour burden was calculated in 69 exams positive for bone metastases using volumetric data and SUVmean values. Intraobserver and interobserver reproducibility was tested. In 10 patients with breast cancer, skeletal tumour burden in pretreatment and post-treatment F-NaF PET/CT was compared with tumour marker and clinical evolution. RESULTS: The range of normal skeleton SUVmean for the 410 volume of interests analysed was 2.2-5.9 (mean±SD: 4.4±1.5). A threshold of 10 was chosen to exclude F-NaF normal skeleton uptake. An inverse relationship was found between normal skeleton SUVmean and age (r=-0.237; P=0.032). Our results show excellent intraobserver and interobserver reproducibility, with intraclass correlation values of 0.995 and 0.997, respectively. The percentage change in the skeletal tumour burden in response to therapy shows a moderate direct correlation with the percentage variation of the tumour marker (r=0.668; P=0.035). CONCLUSION: The methodology that we used to quantify skeletal tumour burden is easy to perform, highly reproducible and allows for the evaluation of bone tumour response to therapy in a subgroup of breast cancer patients. The possibility of skeletal tumour burden quantification is another advantage of F-NaF PET/CT over the visual and subjective interpretation of bone scintigraphy.

Clinical significance of extraskeletal computed tomography findings on 18F-NaF PET/CT performed for osseous metastatic disease evaluation.

PURPOSE: Extraskeletal findings detected on whole-body low-dose unenhanced computed tomography (CT) as a part of F-NaF PET/CT scans can be numerous and present challenges for further management. Here, we investigate the frequency and clinical significance of extraskeletal findings among 130 consecutive patients undergoing F-NaF PET/CT for osseous metastatic disease. METHODS: F-NaF PET/CT performed on 130 patients (101 men and 29 women; mean age: 61.4 years) with biopsy-proven malignancies were reviewed independently. Incidental soft tissue findings detected on unenhanced low-dose CT portions of the scans were compiled and categorized by clinical significance. RESULTS: A total of 275 incidental extraskeletal CT findings were observed in 114 out of 130 patients (87.7%). Seven patients (5.4%) showed clinically significant findings. One patient developed new lung nodules that were resected and proven to be metastases. Two patients showed new hypodense hepatic lesions that were highly suspicious for liver metastases. One patient with prostate cancer was found to have previously unknown retroperitoneal lymphadenopathy. Three patients showed indeterminate renal and adrenal lesions that necessitated further correlative imaging. CONCLUSION: Although CT indicated a large number of incidental extraskeletal lesions in the majority of patients undergoing F-NaF PET/CT, clinically significant incidental findings requiring further evaluation were relatively infrequently observed in 5.4% of patients. Thus, the low-dose unenhanced CT in F-NaF PET/CT performed for oncologic evaluation may indicate unexpected soft tissue lesions that can impact patient management and therefore should be interpreted by physicians skilled in CT reading, with correlation to available imaging, and familiar with established guidelines for work-up of incidental findings.

Improvements in PET Image Quality in Time of Flight (TOF) Simultaneous PET/MRI.

PURPOSE: An integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) scanner with time of flight (TOF) technology is now available for clinical use. The aim of this study is to evaluate the potential of TOF PET in PET/MRI to reduce artifacts in PET images when compared to non-TOF PET/MRI, TOF PET/X-ray computed tomography (CT), and non-TOF PET/CT. PROCEDURES: All patients underwent a single 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) injection, followed first by PET/CT, and subsequently by PET/MRI. PET/CT exams were requested as standard-of-care for oncological indications. Using the PET acquisitions datasets, 4 series of images (TOF PET/CT, non-TOF PET/CT, TOF PET/MRI, and non-TOF PET/MRI) were reconstructed. These image series were visually evaluated for: (1) dental metal artifacts, (2) breathing artifacts, and (3) pelvic artifacts due to scatter correction errors from high bladder [(18)F]FDG concentration. PET image quality was assessed by a 3-point scale (1-clinically significant artifact, 2-non clinically significant artifact, and 3-no artifact). RESULTS: Twenty-five patients (mean ± SD age: 56 ± 13 years old; female: 10, male: 15) were enrolled. TOF PET/MRI, non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT scores 2.8, 2.5, 2.4, and 2.3, respectively for the presence of dental artifacts, 2.8, 2.5, 2.2, and 1.9, respectively, for the presence of breathing artifacts, and 2.7, 1.7, 2.0, and 1.3, respectively, for the presence of pelvic artifacts TOF PET/MRI images showed the highest image quality scores among the 4 datasets of PET images. CONCLUSION: The superior timing resolution and resulting TOF capability of the new PET/MRI scanner improved PET image quality in this cohort by reducing artifacts compared to non-TOF PET/MRI, TOF PET/CT, and non-TOF PET/CT.

Prospective Comparison of 99mTc-MDP Scintigraphy, Combined 18F-NaF and 18F-FDG PET/CT, and Whole-Body MRI in Patients with Breast and Prostate Cancer.

UNLABELLED: We prospectively evaluated the use of combined (18)F-NaF/(18)F-FDG PET/CT in patients with breast and prostate cancer and compared the results with those for (99m)Tc-MDP bone scintigraphy and whole-body MRI. METHODS: Thirty patients (15 women with breast cancer and 15 men with prostate cancer) referred for standard-of-care bone scintigraphy were prospectively enrolled in this study. (18)F-NaF/(18)F-FDG PET/CT and whole-body MRI were performed after bone scintigraphy. The whole-body MRI protocol consisted of both unenhanced and contrast-enhanced sequences. Lesions detected with each test were tabulated, and the results were compared. RESULTS: For extraskeletal lesions, (18)F-NaF/(18)F-FDG PET/CT and whole-body MRI had no statistically significant differences in sensitivity (92.9% vs. 92.9%, P = 1.00), positive predictive value (81.3% vs. 86.7%, P = 0.68), or accuracy (76.5% vs. 82.4%, P = 0.56). However, (18)F-NaF/(18)F-FDG PET/CT showed significantly higher sensitivity and accuracy than whole-body MRI (96.2% vs. 81.4%, P < 0.001, 89.8% vs. 74.7%, P = 0.01) and bone scintigraphy (96.2% vs. 64.6%, P < 0.001, 89.8% vs. 65.9%, P < 0.001) for the detection of skeletal lesions. Overall, (18)F-NaF/(18)F-FDG PET/CT showed higher sensitivity and accuracy than whole-body MRI (95.7% vs. 83.3%, P < 0.002, 87.6% vs. 76.0%, P < 0.02) but not statistically significantly so when compared with a combination of whole-body MRI and bone scintigraphy (95.7% vs. 91.6%, P = 0.17, 87.6% vs. 83.0%, P = 0.53). (18)F-NaF/(18)F-FDG PET/CT showed no significant difference from a combination of (18)F-NaF/(18)F-FDG PET/CT and whole-body MRI. No statistically significant differences in positive predictive value were noted among the 3 examinations. CONCLUSION: (18)F-NaF/(18)F-FDG PET/CT is superior to whole-body MRI and (99m)Tc-MDP scintigraphy for evaluation of skeletal disease extent. Further, (18)F-NaF/(18)F-FDG PET/CT and whole-body MRI detected extraskeletal disease that may change the management of these patients. (18)F-NaF/(18)F-FDG PET/CT provides diagnostic ability similar to that of a combination of whole-body MRI and bone scintigraphy in patients with breast and prostate cancer. Larger cohorts are needed to confirm these preliminary findings, ideally using the newly introduced simultaneous PET/MRI scanners.

Detection of osseous metastasis by 18F-NaF/18F-FDG PET/CT versus CT alone.

PURPOSE: Sodium fluoride PET (18F-NaF) has recently reemerged as a valuable method for detection of osseous metastasis, with recent work highlighting the potential of coadministered 18F-NaF and 18F-FDG PET/CT in a single combined imaging examination. We further examined the potential of such combined examinations by comparing dual tracer 18F-NaF18/F-FDG PET/CT with CT alone for detection of osseous metastasis. PATIENTS AND METHODS: Seventy-five participants with biopsy-proven malignancy were consecutively enrolled from a single center and underwent combined 18F-NaF/18F-FDG PET/CT and diagnostic CT scans. PET/CT as well as CT only images were reviewed in blinded fashion and compared with the results of clinical, imaging, or histological follow-up as a truth standard. RESULTS: Sensitivity of the combined 18F-NaF/18F-FDG PET/CT was higher than that of CT alone (97.4% vs 66.7%). CT and 18F-NaF/18F-FDG PET/CT were concordant in 73% of studies. Of 20 discordant cases, 18F-NaF/18F-FDG PET/CT was correct in 19 (95%). Three cases were interpreted concordantly but incorrectly, and all 3 were false positives. A single case of osseous metastasis was detected by CT alone, but not by 18F-NaF/18F-FDG PET/CT. CONCLUSIONS: Combined 18F-NaF/18F-FDG PET/CT outperforms CT alone and is highly sensitive and specific for detection of osseous metastases. The concordantly interpreted false-positive cases demonstrate the difficulty of distinguishing degenerative from malignant disease, whereas the single case of metastasis seen on CT but not PET highlights the need for careful review of CT images in multimodality studies.

Semiquantitative Analysis of the Biodistribution of the Combined ¹8F-NaF and ¹8F-FDG Administration for PET/CT Imaging.

UNLABELLED: In this study, we evaluated the biodistribution of the (18)F(-)/(18)F-FDG administration, compared with separate (18)F-NaF and (18)F-FDG administrations. We also estimated the interaction of (18)F-NaF and (18)F-FDG in the (18)F(-)/(18)F-FDG administration by semiquantitative analysis. METHODS: We retrospectively analyzed the data of 49 patients (39 men, 10 women; mean age ± SD, 59.3 ± 15.2 y) who underwent separate (18)F-FDG PET/CT and (18)F-NaF PET/CT scans as well as (18)F(-)/(18)F-FDG PET/CT sequentially. The most common primary diagnosis was prostate cancer (n = 28), followed by sarcoma (n = 9) and breast cancer (n = 6). The mean standardized uptake values (SUVs) were recorded for 18 organs in all patients, and maximum SUV and mean SUV were recorded for all the identified malignant lesions. We also estimated the (18)F(-)/(18)F-FDG uptake as the sum of (18)F-FDG uptake and adjusted (18)F-NaF uptake based on the ratio of (18)F-NaF injected dose in (18)F(-)/(18)F-FDG PET/CT. Lastly, we compared the results to explore the interaction of (18)F-FDG and (18)F-NaF uptake in the (18)F(-)/(18)F-FDG scan. RESULTS: The (18)F(-)/(18)F-FDG uptake in the cerebral cortex, cerebellum, parotid grand, myocardium, and bowel mostly reflected the (18)F-FDG uptake, whereas the uptake in the other analyzed structures was influenced by both the (18)F-FDG and the (18)F-NaF uptake. The (18)F(-)/(18)F-FDG uptake in extraskeletal lesions showed no significant difference when compared with the uptake from the separate (18)F-FDG scan. The (18)F(-)/(18)F-FDG uptake in skeletal lesions reflected mostly the (18)F-NaF uptake. The tumor-to-background ratio of (18)F(-)/(18)F-FDG in extraskeletal lesions showed no significant difference when compared with that from (18)F-FDG alone (P = 0.73). For skeletal lesions, the tumor-to-background ratio of (18)F(-)/(18)F-FDG was lower than that from (18)F-NaF alone (P < 0.001); however, this difference did not result in missed skeletal lesions on the (18)F(-)/(18)F-FDG scan. CONCLUSION: The understanding of the biodistribution of radiopharmaceuticals and the lesion uptake of the (18)F(-)/(18)F-FDG scan as well as the variations compared with the uptake on the separate (18)F-FDG PET/CT and (18)F-NaF PET/CT are valuable for more in-depth evaluation of the combined scanning technique.

Combined 18F-NaF and 18F-FDG PET/CT in the Evaluation of Sarcoma Patients.

PURPOSE: The combined administration of F-NaF and F-FDG in a single PET/CT scan has the potential to improve patient convenience and cancer detection. Here we report the use of this approach for patients with sarcomas. PATIENTS AND METHODS: This is a retrospective review of 21 patients (12 men, 9 women; age, 19-66 years) with biopsy-proven sarcomas who had separate F-NaF PET/CT, F-FDG PET/CT, and combined F-NaF/F-FDG PET/CT scans for evaluation of malignancy. Two board-certified nuclear medicine physicians and 1 board-certified musculoskeletal radiologist were randomly assigned to review the scans. Results were analyzed for sensitivity and specificity, using linear regression and receiver operating characteristics. RESULTS: A total of 13 patients had metastatic disease on F-NaF PET/CT, F-FDG PET/CT, and combined F-NaF/F-FDG PET/CT. Skeletal disease was more extensive on the F-NaF PET/CT scan than on the F-FDG PET/CT in 3 patients, whereas in 1 patient, F-FDG PET/CT showed skeletal disease and the F-NaF PET/CT was negative. Extraskeletal lesions were detected on both F-FDG and combined F-NaF/F-FDG PET/CT in 20 patients, with 1 discordant finding in the lung. CONCLUSIONS: The combined F-NaF/F-FDG PET/CT scan allows for accurate evaluation of sarcoma patients. Further evaluation of this proposed imaging modality is warranted to identify the most suitable clinical scenarios, including initial treatment strategy and evaluation of response to therapy.

18F-sodium fluoride PET/CT in oncology: an atlas of SUVs.

PURPOSE: The purpose of this study was to analyze the distribution of 18F Sodium Fluoride (18F-NaF) uptake in the normal skeleton, benign and malignant bone lesions, and extraskeletal tissues, using semiquantitative SUV measurements. PATIENTS AND METHODS: We retrospectively analyzed data from 129 patients who had 18F-NaF PET/CT at our institution for an oncological diagnosis between 2007 and 2014. There were 99 men and 30 women, 19 to 90 years old (mean [SD], 61.5 [15.5]). The range, average, and SD of SUV were measured for normal bone and extraskeletal tissues uptake for the entire patient population. A separate statistical analysis was performed to compare group A, which corresponds to the population of patient with no 18F-NaF-avid metastatic lesions, and group B, which corresponds to the population of patient with 18F-NaF-avid metastatic lesions. We also measured SUV max and SUV mean for bony metastases and degenerative changes RESULTS: The PET/CT images were acquired at 30 to 169 minutes (mean [SD], 76.5 [22.8]) after injection of 3.9 to 13.6 mCi (mean [SD], 7.3 [2.4]) of 18F-NaF. The range and mean (SD) of SUV max for 18F-NaF-avid metastasis were 4.5 to 103.3 and 25.9 (16.6) and for 18F-NaF-avid degenerative changes were 3.3 to 52.1 and 16.5 (7.9), respectively. CONCLUSIONS: Various skeletal sites have different normal SUVs. Skeletal metastases have different SUVs when compared with benign findings such as degenerative changes.

18F NaF brain metastasis uptake in a patient with melanoma.

A 57-year-old man with a history of metastatic melanoma and sclerotic bone lesions seen on CT was referred for F NaF PET/CT evaluation of active skeletal metastases. While the bone lesions had no uptake and were therefore thought to represent sequela of previously treated disease, an unexpected area of F NaF uptake was identified in the left temporal lobe. Concurrent contrast-enhanced brain MRI re-demonstrated a large metastasis, also seen on previous MRI scans done at another institution.

Pilot prospective evaluation of 99mTc-MDP scintigraphy, 18F NaF PET/CT, 18F FDG PET/CT and whole-body MRI for detection of skeletal metastases.

OBJECTIVE: The aim of this study was to compare 99mTc-MDP bone scanning, 18F NaF PET/CT, 18F FDG PET/CT, and whole-body MRI (WBMRI) for detection of known osseous metastases. PATIENTS AND METHODS: This prospective pilot trial (September 2007-April 2009) enrolled 10 participants (5 men, 5 women, 47-81 years old) diagnosed with cancer and known osseous metastases. 18F NaF PET/CT, 18F FDG PET/CT, and WBMRI were performed within 1 month for each participant. RESULTS: The image quality and evaluation of extent of disease were superior by 18F NaF PET/CT compared to 99mTc-MDP scintigraphy in all patients with skeletal lesions and compared to 18F FDG PET/CT in 3 of the patients with skeletal metastases. 18F NaF PET/CT showed osseous metastases where 18F FDG PET/CT was negative in another 3 participants. Extraskeletal metastases were identified by 18F FDG PET/CT in 6 participants. WBMRI with the combination of iterative decomposition of water and fat with echo asymmetry and least-squares estimation, short tau inversion recovery, and diffusion-weighted imaging pulse sequences showed fewer lesions than 18F NaF PET/CT in 5 patients, same number of lesions in 2 patients, and more lesions in 1 patient. WBMRI showed fewer lesions than 18F FDG in 3 patients and same lesions in 6 patients. CONCLUSIONS: Our pilot phase prospective trial demonstrated superior image quality and evaluation of skeletal disease extent with 18F NaF PET/CT compared to 99mTc-MDP scintigraphy and 18F FDG PET/CT, as well as the feasibility of multisequence WBMRI. In addition, 18F FDG PET/CT provided valuable soft-tissue information that can change disease management. Further evaluation of these findings using the recently introduced PET/MRI scanners is warranted.

Prospective evaluation of (99m)Tc MDP scintigraphy, (18)F NaF PET/CT, and (18)F FDG PET/CT for detection of skeletal metastases.

INTRODUCTION: Technetium (Tc) methylene diphosphonate (MDP) has been the standard method for bone scintigraphy for three decades. (18)F sodium fluoride ((18)F NaF) positron emission tomography (PET)/computed tomography (CT) has better resolution and is considered superior. The role of 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F FDG) PET/CT is proven in a variety of cancers, for which it has changed the practice of oncology. There are few prospective studies comparing these three methods of detection of skeletal metastases. Thus, we were prompted to initiate this prospective pilot trial. METHODS: This is a prospective study (Sep 2007-Dec 2010) of 52 patients with proven malignancy referred for evaluation of skeletal metastases. There were 37 men and 15 women, 19-84 years old (average, 55.6 ± 15.9). Technetium-99m ((99m)Tc) MDP bone scintigraphy, (18)F NaF PET/CT, and (18)F FDG PET/CT were subsequently performed within 1 month. RESULTS: Skeletal lesions were detected by (99m)Tc MDP bone scintigraphy in 22 of 52 patients, by (18)F NaF PET/CT in 24 of 52 patients, and by (18)F FDG PET/CT in 16 of 52 patients. The image quality and evaluation of extent of disease were superior by (18)F NaF PET/CT over (99m)Tc MDP scintigraphy in all 22 patients with skeletal lesions on both scans and over (18)F FDG PET/CT in 11 of 16 patients with skeletal metastases on (18)F FDG PET/CT. In two patients, (18)F NaF PET/CT showed skeletal metastases not seen on either of the other two scans. Extraskeletal lesions were identified by (18)F FDG PET/CT in 28 of 52 subjects. CONCLUSION: Our prospective pilot-phase trial demonstrates superior image quality and evaluation of skeletal disease extent with (18)F NaF PET/CT over (99m)Tc MDP scintigraphy and (18)F FDG PET/CT. At the same time, (18)F FDG PET detects extraskeletal disease that can significantly change disease management. As such, a combination of (18)F FDG PET/CT and (18)F NaF PET/CT may be necessary for cancer detection. Additional evaluation with larger cohorts is required to confirm these preliminary findings.