Lacrimal scintigraphy BNMS Guidelines.

PURPOSE: The purpose of this guideline is to assist specialists in Nuclear Medicine and Radionuclide Radiology in recommending, performing, interpreting and reporting the results of lacrimal scintigraphy (also known as Dacroscintigraphy). This guideline will assist individual departments to formulate their own local protocols. This does not aim to be prescriptive regarding technical aspects of individual camera acquisitions, which need to be developed in conjunction with the local experts in medical physics. There are numerous radiological techniques to assess the physiology of the lacrimal system. This guideline will describe the application of a drop of radiotracer into each eye and consecutive imaging to demonstrate the level of impaired drainage, with the possibility of quantifying such impairment. This guideline is a recent and updated version of a previously published guideline on the British Nuclear Medicine Society website in 2018 [1].

The assessment of time-of-flight on image quality and quantification with reduced administered activity and scan times in 18F-FDG PET.

OBJECTIVES: The last decade has seen considerable technological innovations in PET detectors with the availability, among other advances, of time-of-flight (TOF). TOF has been shown to increase the signal-to-noise ratio (SNR), which should allow for a reduction in acquired counts while maintaining image quality. METHODS: Fifty-eight patients referred for routine F-flurodeoxyglucose ((18)F-FDG) oncology PET studies were included in this study. Patients with weight below or above 100 kg were prescribed 350 or 400 MBq of (18)F-FDG, respectively. Listmode data were acquired for 2.5 min per bed position and reconstructed with ordered-subset expectation maximization (OSEM) reconstruction. TOF reconstruction was performed on reduced-count data, with two levels of reduction (-20 and -40% for patients <100 kg and -16 and -30% for patients >100 kg) achieved by clipping the listmode data. Liver SNR, mediastinum mean standardized uptake value (SUV(mean)), and lesion maximum standardized uptake value (SUV(max)) were measured in all images. All images were visually assessed as adequate or suboptimal. RESULTS: No significant difference was seen in mediastinum SUV(mean) or lesion SUV(max) when comparing reduced-count TOF with full-count OSEM images. Compared with the original OSEM images, liver SNR was higher for TOF images using the more conservative -20% reduction of counts (P < 0.001, Wilcoxon's signed-rank test), whereas no significant statistical difference was seen with -40% reductions. CONCLUSION: Incorporation of TOF allows for a reduction in acquired counts; this method has been implemented at our institution, with administered activity reduced for all patients to 280 MBq and a reduction in scan times for all but the largest patients. This has significantly reduced the patient radiation dose and improved scanner flexibility and throughput.

Reduced-count myocardial perfusion SPECT with resolution recovery.

AIM: The aim of this study was to determine whether resolution recovery (RR) iterative reconstruction algorithms can consistently produce diagnostic quality myocardial perfusion SPECT images for the patient population routinely scanned in this department. Reduced-count data were compared with full-count data without RR according to our established protocol. The desired outcome would be to implement the software to allow a reduction in the administered activity for routine myocardial SPECT. METHODS: Half-count SPECT data were derived from full-count datasets for 53 stress and rest routine myocardial SPECT scans on a GE Infinia camera. Full-count data were reconstructed using standard non-RR ordered subset expectation maximization reconstruction, whereas half-count data were reconstructed using Evolution RR software. Myocardial functional values, image quality and report outcomes of the full-count and half-count reports were compared. Sequential full-time and half-time myocardial SPECT acquisitions were performed for 15 stress and rest studies on a Siemens c.cam dedicated cardiac camera. Half-count data were reconstructed using Siemens Flash 3D RR. RESULTS: No degradation in image quality was found when comparing full-count and half-count studies from the Infinia. Ten percent of the half-count studies from the c.cam were considered slightly worse than full-count data. Statistically significant differences in some full-count versus half-count functional values were found but the actual mean differences were not considered clinically significant. No difference was found for 44 out of 53 full-count versus half-count reports, a minor difference for seven out of 53 and a significant difference in two cases. CONCLUSION: RR was found to produce diagnostic image quality for nearly all scans, but it was felt that a reduction of 50% from our standard protocol was too great. A proposed reduction of 33% administered activity was considered acceptable to produce consistently adequate diagnostic images for both manufacturers.