Initial Experience with the Radiotracer 18F-Fluciclovine PET/CT in Ovarian Cancer.

OBJECTIVE: Early and accurate staging of ovarian cancer is paramount to disease survival. Conventional imaging including FDG PET/CT are limited in the evaluation of small metastatic lesions. 18F-Fluciclovine has minimal urine and bowel excretion allowing optimal visualization of the abdomen and pelvis. This study examines 18F-fluciclovine uptake in known primary and recurrent ovarian cancer. METHODS: Seven patients with a confirmed diagnosis of epithelial ovarian cancer underwent 18F-fluciclovine PET/CT imaging. Forty-one (41) lesions were identified with 18F-fluciclovine and confirmed to be true positive (n = 41). We aim to explore if 18F-fluciclovine uptake in ovarian lesions were greater than background uptake of bone marrow, blood pool, and bladder. Quantification analysis was performed to determine max and mean standard uptake values (SUVmax and SUVmean) of known and suspected lesions compared to SUVmean uptake of background structures. RESULTS: 18F-Fluciclovine demonstrated 100% sensitivity (41/41) for uptake in known ovarian lesions. The average SUVmax (±SD) uptake of known ovarian lesions was 5.9 (±2.6) and 5.1 (±2.0) on early and delayed images, respectively. The average tumor SUVmax to SUVmean of background (±SD) (T:B) ratios on early and delay were 1.9 (±0.8), 2.1 (±0.9) for marrow; 3.8 (±1.8), 3.4 (±1.5) for aorta; and 8.4 (±4.3), 1.5 (±1.7) for bladder, respectively. CONCLUSION: 18F-Fluciclovine uptake in malignant ovarian lesions was above background levels suggesting its feasibility in the imaging of ovarian cancer. Due to increasing tracer washout via the urinary bladder over time, early imaging at 4 min post injection is favorable.

Incidental Discovery of Hepatocellular Carcinoma on 18F-PSMA PET CT Performed for Prostate Cancer Reassessment.

Prostate-specific membrane antigen positron emission tomography (PSMA PET) has been approved by the Food and Drug Administration (FDA) to identify prostate cancer in the setting of biochemical recurrence but can also identify other malignancies. 18F-PSMA PET has not been studied as a potential tool for hepatocellular carcinoma (HCC). We describe the case of a 76-year-old male with a rising prostate-specific antigen (PSA) after definitive prostate cancer treatment and no prior liver pathology who was incidentally found to have HCC on 18F-PSMA PET.

Multi-institutional Development and Validation of Contouring Guidelines for Para-aortic Elective Nodal Irradiation in Prostate Cancer Based on Patterns of Involvement on Targeted Molecular Imaging Positron Emission Tomography/Computed Tomography.

PURPOSE: Molecular imaging better identifies anatomic regions of metastatic spread of prostate cancer compared with conventional imaging, resulting in para-aortic (PA) nodal metastases being increasingly identified. Consequently, some radiation oncologists electively treat the PA lymph node region in patients with gross or high risk of PA nodal involvement. The anatomic locations of at-risk PA lymph nodes for prostate cancer are unknown. Our objective was to use molecular imaging to develop guidelines for the optimal delineation of the PA clinical target volume (CTV) in patients with prostate cancer. METHODS AND MATERIALS: We conducted a multi-institutional retrospective cohort study of patients with prostate cancer undergoing 18F-fluciclovine or 18F-DCFPyL prostate-specific membrane antigen positron emission tomography (PET)/computed tomography (CT). Images of patients with PET-positive PA nodes were imported into the treatment planning system, avid nodes were contoured, and measurements were taken in relation to anatomic landmarks. A contouring guideline that encompassed the location of ≥95% of PET-positive PA nodes was created using descriptive statistics and then validated in an independent data set. RESULTS: Five hundred fifty-nine patients had molecular PET/CT imaging in the development data set (78% 18F-fluciclovine, 22% prostate-specific membrane antigen). Seventy-six patients (14%) had evidence of PA nodal metastasis. We determined that expanding the CTV to 1.8 cm left of the aorta, 1.4 cm right of the inferior vena cava (IVC), 7 mm posterior to the aorta/IVC or to the vertebral body, and superiorly to the T11/T12 vertebral interface, with the anterior border 4 mm anterior to the aorta/IVC and inferior border at the bifurcation of the aorta/IVC, resulted in coverage of ≥95% of PET-positive PA nodes. When the guideline was used in the independent validation data set (246 patients with molecular PET/CT imaging, of whom 31 had PA nodal metastasis), 97% of nodes were encompassed, thereby validating our guideline. CONCLUSIONS: We used molecular PET/CT imaging to determine the anatomic locations of PA metastases to develop contouring guidelines for creating a prostate cancer PA CTV. Although the optimal patient selection and clinical benefits of PA radiation therapy remain uncertain, our results will aid in delineating the optimal target when PA radiation therapy is pursued.

Effect of hormonal therapy on 18F-fluciclovine PET/CT in the detection of prostate cancer recurrence, localization of metastatic disease, and correlation with prostate-specific antigen.

INTRODUCTION: 18F-Fluciclovine, is a positron emission tomography (PET) radiotracer approved for the localization of sites of prostate cancer recurrence in men with a rising prostate-specific antigen (PSA) after definitive treatment. To explore the impact of androgen deprivation therapy (ADT) on the performance of 18F-fluciclovine, we conducted a retrospective analysis to compare the 18F-fluciclovine PET/CT positivity rate in patients receiving ADT at the time of the scan with the rate achieved in patients not receiving ADT. METHODS: A retrospective review of data from patients who underwent 18F-fluciclovine PET/CT for biochemical recurrence of prostate cancer between December 2016 to March 2020 was performed. The cohort was divided into an ADT group (patient reportedly on ADT) and a non-ADT group (not currently receiving ADT). Patients with unknown ADT status or undetectable/unknown PSA were excluded. For each group, the number of positive 18F-fluciclovine PET/CT scans (positivity rate) was evaluated for the whole body, prostate/bed, and extraprostatic regions and rates were correlated with PSA. The Fisher's Exact test was applied to establish the significance between the ADT and non-ADT positivity groups. Mantel-Haenszel trend test was performed to assess linearity between the positivity rate and PSA level. RESULTS: In 320 patients, the status of ADT was known. At the time of the 18F-fluciclovine scan, 68/320 (21%) patients were on ADT, while 252/320 (79%) were not. The median Gleason score was 8 (range of 6-10) in the ADT group vs. 7 (range of 6-10) in the non-ADT group (P < 0.001). Overall, positivity rates demonstrated no statistical significance between the ADT and non-ADT groups; Positivity rates (ADT vs. non-ADT) were 82% (56/68) vs. 82% (206/252) for the whole body, 57% (39/68) vs. 60% (152/252) for prostate/bed, and 60% (41/68) vs. 53% (133/252) for extraprostatic regions (P > 0.05). A positive linear correlation was noted between PSA and each group's positivity rate (P < 0.01). However, no significant difference was observed between ADT and non-ADT groups at different PSA levels (P > 0.05). CONCLUSIONS: Detection of prostate cancer recurrence with 18F-fluciclovine PET/CT is not significantly influenced by ADT, suggesting that localization of disease in patients with detectable PSA who are receiving ADT is feasible with 18F-fluciclovine.

Positivity Rate of [18F]Fluciclovine PET/CT in Patients with Suspected Prostate Cancer Recurrence at PSA Levels Below 1 ng/mL.

PURPOSE: Early and precise localization of recurrent prostate cancer lesions after local therapy facilitates optimal disease management. Here, we present results from a single-center study to evaluate the utility of [18F]fluciclovine PET/CT to localize prostate cancer recurrence in patients with PSA <1 ng/mL. PROCEDURES: Data from men who underwent [18F]fluciclovine PET/CT (August 2016-March 2020) for suspected recurrent prostate cancer and who had a PSA value <1ng/mL were retrospectively reviewed. The number of positive scans (positivity rates, PR) was calculated for the whole body, prostate/bed, and extraprostatic regions (pelvic or extrapelvic lymph nodes, bones, and soft tissue). PR were stratified by pre-scan PSA. RESULTS: Data from 113 patients were included. In total, 98 (87%) were post-prostatectomy and 15 (13%) had received non-surgical primary therapy. Twenty patients (18%) were receiving ADT at the time of the scan, 91 (81%) were not, and ADT status was not known for 2 (1.8%) patients. The overall PR at PSA <1ng/mL was 59% (67/113). For the prostate/bed, it was 35% (40/113), and for extraprostatic locations, it was 37% (42/113). At PSA >0-<0.2, 0.2-<0.5, and 0.5-<1 ng/mL, the overall PR was 43% (10/23), 70% (35/50), and 55% (22/40), respectively. In the prostate/bed, these were 13% (3/23), 50% (25/50), and 30% (12/40), respectively, and in extraprostatic lesions were 30% (7/23), 44% (22/50), and 33% (13/40), respectively. Pelvic lymph nodes were the most common site for extraprostatic lesions (29/113, 26%). PR in extrapelvic lymph nodes, bone, and soft tissue were 8.0%, 12%, and 3.5%, respectively. Soft tissue lesions comprised lung nodules (n=3) and a perirectal mass implant (n=1). CONCLUSIONS: Despite low PSA values, more than half of patients had positive [18F]fluciclovine PET/CT findings. Patients with low PSA levels may demonstrate suspicious findings outside of the pelvis, including abdominal lymph nodes and metastatic disease to bones and lungs.

Characterizing and Mitigating Bladder Radioactivity on 18F-Fluciclovine PET/CT.

18F-fluciclovine PET is approved for prostate cancer recurrence imaging. According to the radiopharmaceutical package insert, only 3% of the tracer is expected to be excreted in the urine over the first 4 h. Yet, in clinical practice we noticed a higher percentage of bladder excretion. We sought to evaluate and quantify early 18F-fluciclovine bladder radioactivity and determine whether refraining from voiding before 18F-fluciclovine injection would mitigate it. Methods: In total, 159 patients underwent 18F-fluciclovine PET/CT imaging as part of their clinical workup. The first 36 patients were instructed to void just before 18F-fluciclovine injection; the subsequent 123 patients were not asked to void. The SUVmax and SUVmean of the bladder, aorta, marrow, liver, and bladder volumes were determined. Comparing SUVmean of bladder to background, we characterized bladder radioactivity as insignificant (bladder < aorta), mild (bladder > aorta < marrow), moderate (bladder > marrow < liver), or intense (bladder > liver). Differences between the protocols were investigated. Results: Overall, 22% (35/159) of patients had moderate bladder activity and 8.8% (14/159) had intense bladder activity. A negative association was found between bladder volume and SUVmean A significant difference was found between the voiding and nonvoiding groups, with 38.9% (14/36) versus 17.1% (21/123) of patients, respectively, having moderate bladder activity and 22.2% (8/36) versus 4.9% (6/123) of patients, respectively, having intense bladder activity. Conclusion: Refraining from voiding before 18F-fluciclovine injection results in significantly lower urinary bladder radioactivity than does purposeful voiding before injection. We have modified our practice accordingly, particularly as moderate and intense bladder activity may mask or mimic local prostate cancer recurrence. Mechanisms underlying this phenomenon should be further investigated.

Best Practices for 18F-Fluciclovine PET/CT Imaging of Recurrent Prostate Cancer: A Guide for Technologists.

18F-fluciclovine is a Food and Drug Administration-approved PET tracer indicated for patients suspected to have recurrent prostate cancer based on a prostate-specific antigen rise after prior therapy. 18F-fluciclovine PET/CT is performed significantly differently from 18F-FDG PET/CT and requires special attention to patient preparation, injection technique, and imaging time. This article aims to provide nuclear medicine technologists with the best-practice guidelines for the 18F-fluciclovine PET/CT protocol.

Proof of Concept: Design and Initial Evaluation of a Device to Measure Gastrointestinal Transit Time.

Chronic constipation and gastrointestinal motility disorders constitute a large part of a gastroenterology practice and have a significant impact on a patient's quality of life and lifestyle. In most cases, medications are prescribed to alleviate symptoms without there being an objective measurement of response. Commonly used investigations of gastrointestinal transit times are currently limited to radiopaque markers or electronic capsules. Repeated use of these techniques is limited because of the radiation exposure and the significant cost of the devices. We present the proof of concept for a new device to measure gastrointestinal transit time using commonly available and inexpensive materials with only a small amount of radiotracer. Methods: We assembled gelatin capsules containing a 67Ga-citrate-radiolabeled grain of rice embedded in paraffin for use as a point-source transit device. It was tested for stability in vitro and subsequently was given orally to 4 healthy volunteers and 10 patients with constipation or diarrhea. Imaging was performed at regular intervals until the device was excreted. Results: The device remained intact and visible as a point source in all subjects until excretion. When used along with a diary of bowel movement times and dates, the device could determine the total transit time. The device could be visualized either alone or in combination with a barium small-bowel follow-through study or a gastric emptying study. Conclusion: The use of a point-source transit device for the determination of gastrointestinal transit time is a feasible alternative to other methods. The device is inexpensive and easy to assemble, requires only a small amount of radiotracer, and remains inert throughout the gastrointestinal tract, allowing for accurate determination of gastrointestinal transit time. Further investigation of the device is required to establish optimum imaging parameters and reference values. Measurements of gastrointestinal transit time may be useful in managing patients with dysmotility and in selecting the appropriate pharmaceutical treatment.

Managing Written Directives: A Software Solution to Streamline Workflow.

A written directive is required by the U.S. Nuclear Regulatory Commission for any use of 131I above 1.11 MBq (30 µCi) and for patients receiving radiopharmaceutical therapy. This requirement has also been adopted and must be enforced by the agreement states. As the introduction of new radiopharmaceuticals increases therapeutic options in nuclear medicine, time spent on regulatory paperwork also increases. The pressure of managing these time-consuming regulatory requirements may heighten the potential for inaccurate or incomplete directive data and subsequent regulatory violations. To improve on the paper-trail method of directive management, we created a software tool using a Health Insurance Portability and Accountability Act (HIPAA)-compliant database. This software allows for secure data-sharing among physicians, technologists, and managers while saving time, reducing errors, and eliminating the possibility of loss and duplication. Methods: The software tool was developed using Visual Basic, which is part of the Visual Studio development environment for the Windows platform. Patient data are deposited in an Access database on a local HIPAA-compliant secure server or hard disk. Once a working version had been developed, it was installed at our institution and used to manage directives. Updates and modifications of the software were released regularly until no more significant problems were found with its operation. Results: The software has been used at our institution for over 2 y and has reliably kept track of all directives. All physicians and technologists use the software daily and find it superior to paper directives. They can retrieve active directives at any stage of completion, as well as completed directives. Conclusion: We have developed a software solution for the management of written directives that streamlines and structures the departmental workflow. This solution saves time, centralizes the information for all staff to share, and decreases confusion about the creation, completion, filing, and retrieval of directives.

Single photon emission computed tomography myocardial perfusion imaging to detect cardiac allograft vasculopathy.

AIMS: Cardiac allograft vasculopathy (CAV) is a major cause of morbidity and mortality in cardiac transplant recipients. This study evaluates the usefulness of single photon emission computed tomography (SPECT) and various SPECT-derived diastolic variables to detect CAV in heart transplant patients. METHODS AND RESULTS: A retrospective review of 141 SPECT studies with corresponding coronary angiograms within 12 months was performed on 99 transplant recipients. Diastolic function was assessed using computer-derived measures of peak filling rate (PFR), time to peak filling rate (TPFR), and mean first one-third filling rate (MFR/3). Angiography identified CAV in 53 of the 141 studies (38%). Of the 53, SPECT identified 7 with reversible myocardial defects (sensitivity 13%) and stress-induced electrocardiographic evidence of ischaemia was seen in one patient (sensitivity 2%). SPECT imaging was negative in 86 of the 88 negative coronary angiograms (specificity 98%). The positive predictive value and negative predictive value were 78 and 65%, respectively. If a more stringent definition of CAV was used (≥70% stenosis), the sensitivity and specificity were unchanged (14 and 98%, respectively). There was no statistical difference in diastolic variables between patients with or without angiographic evidence of CAV in regard to PFR (3.57 ± 1.14 vs. 3.18 ± 1.21 EDV/s, P = 0.90), TPFR (149 ± 32 vs. 153 ± 43 ms, P = 0.33), or MFR/3 (1.37 ± 0.43 vs. 1.27 ± 0.42 EDV/s, P = 0.94). CONCLUSION: Adenosine stress/rest technetium-99m tetrofosmin-gated SPECT is not a sensitive test for detection of CAV in heart transplant recipients. Diastolic dysfunction, as assessed by SPECT, was not shown to be associated with development of CAV.

The influence of (18)flourodeoxyglucose positron emission tomography on the management of gastroesophageal junction carcinoma.

BACKGROUND: The influence of positron emission tomography (PET) scanning with flourodeoxyglucose (FDG) on decision making for the treatment of patients with esophagogastric junction (EGJ) carcinoma is unclear as is the utility of the maximum standardized uptake value (SUV) as a prognostic indicator. METHODS: This study was a retrospective review of EGJ carcinoma cases at a single institution during a 5-year period. RESULTS: FDG-PET altered treatment in 13 of 64 patients (20%). Of these, 21 patients had PET scans before and after undergoing neoadjuvant chemoradiation (CRT) as well as surgery. Patients who had a decrease in SUV >50% had a 12-month disease-free survival advantage over patients a decrease in SUV <50% (93% vs 43%, P = .025). CONCLUSIONS: FDG-PET alters treatment in a significant number of patients with EGJ carcinoma. A >50% decrease in SUV after CRT is associated with an improved prognosis.