Advanced quantitative evaluation of PET systems using the ACR phantom and NiftyPET software.

PURPOSE: A novel phantom-imaging platform, a set of software tools, for automated and high-precision imaging of the American College of Radiology (ACR) positron emission tomography (PET) phantom for PET/magnetic resonance (PET/MR) and PET/computed tomography (PET/CT) systems is proposed. METHODS: The key feature of this platform is the vector graphics design that facilitates the automated measurement of the knife-edge response function and hence image resolution, using composite volume of interest templates in a 0.5 mm resolution grid applied to all inserts of the phantom. Furthermore, the proposed platform enables the generation of an accurate µ $\mu$ -map for PET/MR systems with a robust alignment based on two-stage image registration using specifically designed PET templates. The proposed platform is based on the open-source NiftyPET software package used to generate multiple list-mode data bootstrap realizations and image reconstructions to determine the precision of the two-stage registration and any image-derived statistics. For all the analyses, iterative image reconstruction was employed with and without modeled shift-invariant point spread function and with varying iterations of the ordered subsets expectation maximization (OSEM) algorithm. The impact of the activity outside the field of view (FOV) was assessed using two acquisitions of 30 min each, with and without the activity outside the FOV. RESULTS: The utility of the platform has been demonstrated by providing a standard and an advanced phantom analysis including the estimation of spatial resolution using all cylindrical inserts. In the imaging planes close to the edge of the axial FOV, we observed deterioration in the quantitative accuracy, reduced resolution (FWHM increased by 1-2 mm), reduced contrast, and background uniformity due to the activity outside the FOV. Although it slows convergence, the PSF reconstruction had a positive impact on resolution and contrast recovery, but the degree of improvement depended on the regions. The uncertainty analysis based on bootstrap resampling of raw PET data indicated high precision of the two-stage registration. CONCLUSIONS: We demonstrated that phantom imaging using the proposed methodology with the metric of spatial resolution and multiple bootstrap realizations may be helpful in more accurate evaluation of PET systems as well as in facilitating fine tuning for optimal imaging parameters in PET/MR and PET/CT clinical research studies.

Lysine analogue use during cancer surgery: a survey from a Canadian tertiary care centre.

Background: When used during surgery, antifibrinolytic hemostatic agents such as lysine analogues are effective at reducing blood loss and the need for transfusions. Despite proven efficacy, use of hemostatic agents remains low during some surgeries. Our objective was to explore surgeon opinions about, and use of lysine analogues in, oncologic surgeries at a large tertiary care academic institution. Methods: We administered a survey to surgeons who perform high-transfusion-risk oncologic surgeries at a large academic hospital in Ottawa, Ontario. Design and distribution of the survey followed a modified Dillman method. To ensure that the survey questionnaire was relevant, clear, and concise, we performed informant interviews, cognitive interviews, and pilot-testing. The final survey consisted of 19 questions divided into 3 sections: respondent demographics, use of hemostatic agents, and potential clinical trial opinions. Results: Of 28 surgeons, 24 (86%) participated. When asked to indicate the frequency of lysine analogue use, "never" accounted for 46% of the responses, and "rarely" (<10% of the time) accounted for 23% of the responses. Reasons for never using included "unfamiliar with benefits" and "prefer alternatives." Fifteen surgeons (63%) felt that a trial was needed to demonstrate the efficacy and safety of lysine analogues in their cancer field. Conclusions: Our survey found that lysine analogues are infrequently used during oncologic surgeries at our institution. Many surgeons are unfamiliar with the benefits and side effects of lysine analogues and, alternatively, use topical hemostatic agents. Our results demonstrate that future trials exploring the efficacy and safety of lysine analogues in oncologic surgery are needed.

A randomized trial of individualized versus standard of care antiemetic therapy for breast cancer patients at high risk for chemotherapy-induced nausea and vomiting.

PURPOSE: Despite triple antiemetic therapy use for breast cancer patients receiving emetogenic chemotherapy, nausea remains a clinical challenge. We evaluated adding olanzapine (5 mg) to triple therapy on nausea control in patients at high personal risk of chemotherapy-induced nausea and vomiting (CINV). METHODS: This multi-centre, placebo-controlled, double-blind trial randomized breast cancer patients scheduled to receive neo/adjuvant chemotherapy with anthracycline-cyclophosphamide or platinum-based chemotherapy to olanzapine (5 mg, days 1-4) or placebo. Primary endpoint was frequency of self-reported significant nausea, repeated for all cycles of chemotherapy. Secondary endpoints included: duration of nausea, overall total control of CINV, Health Related Quality of Life (HRQoL) using FLIE questionnaire, use of rescue mediation and treatment-related adverse events. RESULTS: 218 eligible patients were randomised to placebo (105) or olanzapine (113). From days 0-5 following each cycle of chemotherapy, 41.3% (95%CI: 36.1-46.7%) of patients in the placebo group reported significant nausea compared to 27.7% (95%CI: 23.2-32.4%) in the olanzapine group (p = 0.001). Across all cycles of chemotherapy, patients receiving olanzapine experienced a statistically significant improvement in HRQoL (p < 0.001). Grade 1/2 sedation was the most commonly side effect reported at 40.8% in the placebo group vs. 54.1% with olanzapine (p < 0.001). CONCLUSION: In patients at high personal risk of CINV, the addition of olanzapine 5 mg daily to standard antiemetic therapy significantly improves the control of nausea, HRQoL, with no unexpected toxicities.

An evaluation of DistillerSR's machine learning-based prioritization tool for title/abstract screening - impact on reviewer-relevant outcomes.

BACKGROUND: Systematic reviews often require substantial resources, partially due to the large number of records identified during searching. Although artificial intelligence may not be ready to fully replace human reviewers, it may accelerate and reduce the screening burden. Using DistillerSR (May 2020 release), we evaluated the performance of the prioritization simulation tool to determine the reduction in screening burden and time savings. METHODS: Using a true recall @ 95%, response sets from 10 completed systematic reviews were used to evaluate: (i) the reduction of screening burden; (ii) the accuracy of the prioritization algorithm; and (iii) the hours saved when a modified screening approach was implemented. To account for variation in the simulations, and to introduce randomness (through shuffling the references), 10 simulations were run for each review. Means, standard deviations, medians and interquartile ranges (IQR) are presented. RESULTS: Among the 10 systematic reviews, using true recall @ 95% there was a median reduction in screening burden of 47.1% (IQR: 37.5 to 58.0%). A median of 41.2% (IQR: 33.4 to 46.9%) of the excluded records needed to be screened to achieve true recall @ 95%. The median title/abstract screening hours saved using a modified screening approach at a true recall @ 95% was 29.8 h (IQR: 28.1 to 74.7 h). This was increased to a median of 36 h (IQR: 32.2 to 79.7 h) when considering the time saved not retrieving and screening full texts of the remaining 5% of records not yet identified as included at title/abstract. Among the 100 simulations (10 simulations per review), none of these 5% of records were a final included study in the systematic review. The reduction in screening burden to achieve true recall @ 95% compared to @ 100% resulted in a reduced screening burden median of 40.6% (IQR: 38.3 to 54.2%). CONCLUSIONS: The prioritization tool in DistillerSR can reduce screening burden. A modified or stop screening approach once a true recall @ 95% is achieved appears to be a valid method for rapid reviews, and perhaps systematic reviews. This needs to be further evaluated in prospective reviews using the estimated recall.

Psychosocial and pharmacologic interventions for methamphetamine addiction: protocol for a scoping review of the literature.

BACKGROUND: Methamphetamine use and harms are rising rapidly. Management of patients with methamphetamine use disorder (MUD) and problematic methamphetamine use (PMU) is challenging, with no clearly established best approach; both psychosocial and pharmacologic interventions have been described. Furthermore, given the diversity of individuals that use methamphetamines, there is a need to assess evidence for treatments for subgroups including youths; gay, bisexual, and other men who have sex with men; individuals with mental health comorbidities; and individuals in correction services. Establishing awareness of the messages regarding treatment from recent clinical practice guidelines (CPG) in the field is also of value. The first study objective will be to establish a greater understanding of the methods, populations, and findings of controlled studies for psychosocial and pharmacologic treatments for MUD and PMU. Investigation of this information can help establish the potential for advanced syntheses of the evidence (such as network meta-analysis) to compare therapies for this condition and to identify gaps related to key populations where more primary research is needed. Summarizing the recommendations regarding treatment of MUD/PMU from recent CPGs and systematic reviews will be an important secondary objective. METHODS: A scoping review will be performed. Using the OVID platform, MEDLINE, Embase, PsycINFO, and relevant Cochrane databases from EBM Reviews will be searched (from databases' inception onwards). Eligibility criteria will include individuals described as having MUD or PMU, with designs of interest including randomized trials, non-randomized trials, and controlled cohort studies with three or more months of follow-up; systematic reviews and CPGs will also be sought. Two reviewers (with support from automation tools) will independently screen all citations, full-text articles, and chart data. Different approaches to handling and summarizing the data will be implemented for each type of study design. Tables and graphics will be used to map evidence sources and identify evidence gaps. DISCUSSION: This research will enhance awareness of evidence addressing the effects of psychosocial and pharmacologic interventions for MUD/PMU overall and in sub-populations, both in terms of recent CPGs/reviews and primary studies; inspection of the latter will also help establish the feasibility of future syntheses to compare treatments, such as network meta-analysis. SYSTEMATIC REVIEW PROTOCOL REGISTRATION: Open Science Framework ( https://osf.io/9wy8p ).

A multicentre, randomised trial comparing schedules of G-CSF (filgrastim) administration for primary prophylaxis of chemotherapy-induced febrile neutropenia in early stage breast cancer.

BACKGROUND: The optimal duration of filgrastim as primary febrile neutropenia (FN) prophylaxis in early breast cancer patients is unknown, with 5, 7 or 10 days being commonly prescribed. This trial evaluates whether 5 days of filgrastim was non-inferior to 7/10 days. PATIENTS AND METHODS: In this randomised, open-label trial, early breast cancer patients who were to receive filgrastim as primary FN prophylaxis were randomly allocated to 5 versus 7 versus 10 days of filgrastim for all chemotherapy cycles. A protocol amendment in November 2017 allowed subsequent patients (N = 324) to be randomised to either 5 or 7/10 days. The primary outcome was a composite of either FN or treatment-related hospitalisations. Secondary outcomes included chemotherapy dose reductions, delays and discontinuations. Analyses were carried out by per protocol (primary) and intention-to-treat, and the non-inferiority margin was set at 3% for the risk of having FN and/or hospitalisation per cycle of chemotherapy. RESULTS: Patients (N = 466) were randomised to receive 5 (184, 39.5%), or 7/10 (282, 60.5%) days of filgrastim. In our primary analysis, the difference in risk of either FN or treatment-related hospitalisation per cycle was -1.52% [95% confidence interval (CI): -3.22% to 0.19%] suggesting non-inferiority of a 5-day filgrastim schedule compared with 7/10-days. The difference in events per cycle for FN was 0.11% (95% CI: -1.05 to 1.27) while for treatment-related hospitalisations it was -1.68% (95% CI: -2.73% to -0.63%). The overall proportions of patients having at least one occurrence of either FN or treatment-related hospitalisation were 11.8% and 14.96% for the 5- and 7/10-day groups, respectively (risk difference: -3.17%, 95% CI: -9.51% to 3.18%). CONCLUSION: Five days of filgrastim was non-inferior to 7/10 days. Given the cost and toxicity of this agent, 5 days should be considered standard of care. CLINICALTRIALS. GOV REGISTRATION: NCT02428114 and NCT02816164.

Knowledge Synthesis in Evidence-Based Medicine.

Systematic reviews are the most common form of knowledge synthesis and remain a cornerstone of the practice of evidence-based medicine. They offer enhanced rigor and validity relative to traditional narrative review articles by reducing bias and increasing objectivity. In answering focused research questions, systematic reviews are directly applicable to clinical practice as well as the development of clinical guidelines and the identification of knowledge gaps, which may drive future primary research directions. Typically, such a rigorous process necessarily requires substantive time to carefully and systematically identify, screen, and synthesize all relevant available primary research on a topic. Further, other knowledge synthesis methods have emerged to address the varying needs of decision makers with respect to condensed timelines and more diverse research questions, as well as to allow incorporation of already synthesized evidence into reviews. These alternative methods include rapid reviews, scoping reviews, and overviews of systematic reviews, which are being used with increasing frequency by clinicians, decision-makers, and researchers. We encourage clinicians and researchers in nuclear medicine and other imaging sciences to acquire a greater familiarity with these methods and to consider them in clinical decision making, the development of clinical guidelines, and the planning of future research activities.

Optimizing vascular access for patients receiving intravenous systemic therapy for early-stage breast cancer-a survey of oncology nurses and physicians.

Background: Despite advances in systemic therapy choices for patients with early-stage breast cancer, optimal practices for intravenous (IV) access remain unknown. That lack of knowledge holds particularly true for the use of central venous access devices (cvads) such as peripherally inserted central catheters (piccs) and implanted vascular access devices (ports). Methods: Using a survey of Canadian oncologists and oncology nurses responsible for the care of breast cancer patients, we evaluated current access practices, perceptions of complications, and perceptions of risk, and we estimated complication rates and evaluated perceived risk factors for lymphedema. Results: Survey responses were received from 25 physicians and 57 oncology nurses. Administration of trastuzumab or an anthracycline was associated with a higher likelihood of a cvad being recommended. Other factors associated with recommendation of a cvad included prior difficult IV access and a recommendation from the chemotherapy nurse. Although the complication rates perceived to be associated with the use of piccs and ports remained high, respondents felt that cvads might improve patient quality of life. Risk factors perceived to be associated with the risk of lymphedema were axillary lymph node dissection, radiation to the axilla, and line-associated infection. Factors known to be unrelated to lymphedema risk (specifically, blood draws and blood pressure measurement) continue to be perceived as posing a higher risk. Conclusions: Despite widespread use of chemotherapy for patients with breast cancer, the type of venous access used for treatment varies significantly, as do perceptions about the risks of cvad use and the risk for lymphedema development. Further prospective studies are needed to identify best-practice strategies.

Perceptions of vascular access for intravenous systemic therapy and risk factors for lymphedema in early-stage breast cancer-a patient survey.

Background: The choice of vascular access for systemic therapy administration in breast cancer remains an area of clinical equipoise, and patient preference is not consistently acknowledged. Using a patient survey, we evaluated the patient experience with vascular access during treatment for early-stage breast cancer and explored perceived risk factors for lymphedema. Methods: Patients who had received systemic therapy for early-stage breast cancer were surveyed at 2 Canadian cancer centres. Results: Responses were received from 187 patients (94%). The route of vascular access was peripheral intravenous line (IV) in 24%, a peripherally inserted central catheter (picc) in 42%, and a surgically inserted central catheter (port) in 34%. Anthracycline-based regimens were associated with a greater use of central vascular access devices (cvads- that is, a picc or port; 86/97, 89%). Trastuzumab use was associated with greater use of ports (49/64, 77%). Although few patients (7%) reported being involved in the decisions about vascular access, most were satisfied or very satisfied (88%) with their access type. Patient preference centred mainly on avoiding delays in the initiation of chemotherapy. Self-reported rates of complications (183 evaluable responses) were infiltration with peripheral IVs (9/44, 20%), local skin infections with piccs (7/77, 9%), and thrombosis with ports (4/62, 6%). Perceived risk factors for lymphedema included use of the surgical arm for blood draws (117/156, 75%) and blood pressure measurement (115/156, 74%). Conclusions: Most patients reported being satisfied with the vascular access used for their treatment. Improved education and understanding about the evidence-based requirements for vascular access are needed. Perceived risk factors for lymphedema remain variable and are not evidence-based.

Optimal sequence of adjuvant endocrine and radiation therapy in early-stage breast cancer - A systematic review.

IMPORTANCE: Clinical equipoise exists around the optimal time to start adjuvant endocrine therapy in patients who will receive post-operative radiotherapy for breast cancer. Concerns continue to exist regarding potential reduced efficacy, or increased toxicity, when radiation, and endocrine therapy are administered concurrently. OBJECTIVE: To perform a systematic review of studies comparing outcomes between sequential and concurrent adjuvant radiation and endocrine therapy in early-stage breast cancer. All modalities of radiation therapy were considered, and endocrine therapy could be either tamoxifen or an aromatase inhibitor. Outcomes of interest included; local, regional or distant recurrence, overall survival and treatment-related toxicities. EVIDENCE REVIEWED: PubMed, Ovid Medline, EMBASE, and the Cochrane Central Register of Controlled Trials were searched from 1946 to December 2017. Two reviewers independently assessed each citation using the criteria outlined above. Study quality was assessed using the Cochrane Collaboration's tool for prospective studies, and the Newcastle-Ottawa scale for retrospective studies. FINDINGS: Of 2137 unique citations identified, 13 met eligibility criteria. Eleven were unique studies (7569 patients), while 2 of the studies were updated analyses of previous studies. Studies evaluated the timing of adjuvant radiation, and tamoxifen (5 studies, 1550 patients), or aromatase inhibitors (6 studies, 6019 patients). We identified 1 complete randomized clinical trial (150 patients), and 5 retrospective studies (1580 patients), in addition to conference abstracts (5 studies, 5839 patients). Overall, none of the studies showed a significant difference in efficacy, or toxicity, with concurrent versus sequential treatment. However, given the significant heterogeneity of the study populations, it was not possible to conduct a meta-analysis. CONCLUSIONS AND RELEVANCE: In the absence of high quality data, adequately powered randomized trials are required to answer this important clinical question.

Taxane acute pain syndrome (TAPS) in patients receiving chemotherapy for breast or prostate cancer: a prospective multi-center study.

BACKGROUND: Taxane acute pain syndrome (TAPS) is characterized by myalgias and arthralgias starting 2-3 days after taxane-based chemotherapy and lasting up to 7 days. In the absence of validated tools, many studies use the presence of both the myalgia and arthralgia components of the Common Terminology Criteria for Adverse Events (CTCAE) to define TAPS. The present study prospectively evaluated the frequency, severity, and impact of TAPS in patients with breast or prostate cancer. PATIENTS AND METHODS: In this prospective, non-randomized study, patients with breast or prostate cancer commencing taxane-based chemotherapy completed the CTCAE (version 4.03), the Functional Assessment of Cancer Therapy-Taxane (FACT-T), and Brief Pain Inventory (BPI) questionnaires at baseline and once between days 5 and 7 of each chemotherapy cycle. RESULTS: From March 2015 to April 1, 2016, 75 patients (breast n = 66, prostate n = 9) were enrolled; 83% received docetaxel and 16% paclitaxel and 1% withdrew. After the first cycle of taxane, TAPS was reported by 25/69 (36.2%) patients; a further 8/69 (18.2%) reporting TAPS after a subsequent chemotherapy treatment. Overall incidence of TAPS was 33/75 (44%). While associated with detrimental scores on FACT-T and BPI as well as increased use of analgesics in 63% (21/33) of patients with TAPS, TAPS did not lead to alterations in chemotherapy dosing. CONCLUSIONS: TAPS is common after taxane-based chemotherapy, and its presence is associated with reduced quality of life and increased analgesic requirements. Prospective patient-reported outcome assessments are crucial to help individualize treatment strategies and improve management of TAPS.

Network geometry of evidence from randomised controlled trials addressing donor selection and source of haematopoietic progenitor cells used in allogeneic transplantation: a systematic scoping review.

BACKGROUND AND METHODS: A scoping review of randomised controlled trials (RCTs) addressing source of cells and choice of donor for allogeneic haematopoietic cell transplantation (HCT) was performed to create a network of best evidence that allows us to identify new potential indirect comparisons for the strategic development of future studies that connect to the existing evidence network. RESULTS: A total of 19 eligible RCTs (2589 total patients) were identified. Nine studies (1566 patients) compared clinical outcomes following the use of peripheral blood progenitor cells (PBPCs) with bone marrow (BM) from matched related donors (eight studies) or matched unrelated donors (one study). The remaining studies compared BM or PBPCs with various methods of BM stimulation or manipulation (six studies), compared different methods of surface molecule-based selection and/or depletion of grafts (two studies) or compared the optimal number of units for paediatric cord blood transplantation (two studies). No published RCTs compared different types of donors. The geometry of the evidence network was analysed to identify opportunities for potential novel indirect comparisons and to identify opportunities to expand the network. Few indirect comparisons are currently feasible due to small sample size and heterogeneity in patient diagnoses and demographics between treatment nodes in the network. CONCLUSION: More RCTs that enrol greater numbers of similar patients are needed to leverage the current evidence network concerning donor choice and source of cells used in allogeneic HCT.

Comparison of pharmacological and non-pharmacological interventions to prevent delirium in critically ill patients: a protocol for a systematic review incorporating network meta-analyses.

BACKGROUND: Delirium is characterized by acute changes in mental status including inattention, disorganized thinking, and altered level of consciousness, and is highly prevalent in critically ill adults. Delirium has adverse consequences for both patients and the healthcare system; however, at this time, no effective treatment exists. The identification of effective prevention strategies is therefore a clinical and research imperative. An important limitation of previous reviews of delirium prevention is that interventions were considered in isolation and only direct evidence was used. Our systematic review will synthesize all existing data using network meta-analysis, a powerful statistical approach that enables synthesis of both direct and indirect evidence. METHODS: We will search Ovid MEDLINE, CINAHL, Embase, PsycINFO, and Web of Science from 1980 to March 2016. We will search the PROSPERO registry for protocols and the Cochrane Library for published systematic reviews. We will examine reference lists of pertinent reviews and search grey literature and the International Clinical Trials Registry Platform for unpublished studies and ongoing trials. We will include randomized and quasi-randomized trials of critically ill adults evaluating any pharmacological, non-pharmacological, or multi-component intervention for delirium prevention, administered in or prior to (i.e., peri-operatively) transfer to the ICU. Two authors will independently screen search results and extract data from eligible studies. Risk of bias assessments will be completed on all included studies. To inform our network meta-analysis, we will first conduct conventional pair-wise meta-analyses for primary and secondary outcomes using random-effects models. We will generate our network meta-analysis using a Bayesian framework, assuming a common heterogeneity parameter across all comparisons, and accounting for correlations in multi-arm studies. We will perform analyses using WinBUGS software. DISCUSSION: This systematic review will address the existing knowledge gap regarding best practices for delirium prevention in critically ill adults by synthesizing evidence from trials of pharmacological, non-pharmacological, and multi-component interventions administered in or prior to transfer to the ICU. Use of network meta-analysis will clarify which delirium prevention strategies are most effective in improving clinical outcomes while causing least harm. The network meta-analysis is a novel approach and will provide knowledge users and decision makers with comparisons of multiple interventions of delirium prevention strategies. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42016036313.

Estrogen, progesterone, and HER2/neu receptor discordance between primary and metastatic breast tumours-a review.

Discordance in estrogen (ER), progesterone (PR), and HER2/neu status between primary breast tumours and metastatic disease is well recognized. In this review, we highlight how receptor discordance between primary tumours and paired metastasis can help elucidate the mechanism of metastasis but can also effect patient management and the design of future trials. Discordance rates and ranges were available from 47 studies (3384 matched primary and metastatic pairs) reporting ER, PR, and HER2/neu expression for both primary and metastatic sites. Median discordance rates for ER, PR, and HER2/neu were 14 % (range 0-67 %, IQR 9-25 %), 21 % (range 0-62 %, IQR 15-41 %), and 10 % (range 0-44 %, IQR 4-17 %), respectively. Loss of receptor expression was more common (9.17 %) than gain (4.51 %). Discordance rates varied amongst site of metastasis with ER discordance being highest in bone metastases suggesting that discordance is a true biological phenomenon. Discordance rates vary for both the biomarker and the metastatic site. Loss of expression is more common than gain. This can affect patient management as it can lead to a reduction in both the efficacy and availability of potential therapeutic agents. Future studies are recommended to explore both the mechanisms of discordance as well as its impact on patient outcome and management.

Rapid processing of PET list-mode data for efficient uncertainty estimation and data analysis.

In this technical note we propose a rapid and scalable software solution for the processing of PET list-mode data, which allows the efficient integration of list mode data processing into the workflow of image reconstruction and analysis. All processing is performed on the graphics processing unit (GPU), making use of streamed and concurrent kernel execution together with data transfers between disk and CPU memory as well as CPU and GPU memory. This approach leads to fast generation of multiple bootstrap realisations, and when combined with fast image reconstruction and analysis, it enables assessment of uncertainties of any image statistic and of any component of the image generation process (e.g. random correction, image processing) within reasonable time frames (e.g. within five minutes per realisation). This is of particular value when handling complex chains of image generation and processing. The software outputs the following: (1) estimate of expected random event data for noise reduction; (2) dynamic prompt and random sinograms of span-1 and span-11 and (3) variance estimates based on multiple bootstrap realisations of (1) and (2) assuming reasonable count levels for acceptable accuracy. In addition, the software produces statistics and visualisations for immediate quality control and crude motion detection, such as: (1) count rate curves; (2) centre of mass plots of the radiodistribution for motion detection; (3) video of dynamic projection views for fast visual list-mode skimming and inspection; (4) full normalisation factor sinograms. To demonstrate the software, we present an example of the above processing for fast uncertainty estimation of regional SUVR (standard uptake value ratio) calculation for a single PET scan of (18)F-florbetapir using the Siemens Biograph mMR scanner.

A new virtual ring-based system matrix generator for iterative image reconstruction in high resolution small volume PET systems.

A common approach to improving the spatial resolution of small animal PET scanners is to reduce the size of scintillation crystals and/or employ high resolution pixellated semiconductor detectors. The large number of detector elements results in the system matrix--an essential part of statistical iterative reconstruction algorithms--becoming impractically large. In this paper, we propose a methodology for system matrix modelling which utilises a virtual single-layer detector ring to greatly reduce the size of the system matrix without sacrificing precision. Two methods for populating the system matrix are compared; the first utilises a geometrically-derived system matrix based on Siddon's ray tracer method with the addition of an accurate detector response function, while the second uses Monte Carlo simulation to populate the system matrix. The effectiveness of both variations of the proposed technique is demonstrated via simulations of PETiPIX, an ultra high spatial resolution small animal PET scanner featuring high-resolution DoI capabilities, which has previously been simulated and characterised using classical image reconstruction methods. Compression factors of 5 x 10(7) and 2.5 x 10(7)are achieved using this methodology for the system matrices produced using the geometric and Monte Carlo-based approaches, respectively, requiring a total of 0.5-1.2 GB of memory-resident storage. Images reconstructed from Monte Carlo simulations of various point source and phantom models, produced using system matrices generated via both geometric and simulation methods, are used to evaluate the quality of the resulting system matrix in terms of achievable spatial resolution and the CRC, CoV and CW-SSIM index image quality metrics. The Monte Carlo-based system matrix is shown to provide the best image quality at the cost of substantial one-off computational effort and a lower (but still practical) compression factor. Finally, a straightforward extension of the virtual ring method to a three dimensional virtual cylinder is demonstrated using a 3D DoI PET scanner.

Should de-escalation of bone-targeting agents be standard of care for patients with bone metastases from breast cancer? A systematic review and meta-analysis.

BACKGROUND: De-escalation of bone-targeted agents, such as bisphosphonates and denosumab, from 4- to 12-weekly dosing is an increasingly used strategy in patients with bone metastases from breast cancer. It is unclear whether there is sufficient evidence to support de-escalation as a standard of care. METHODS: A systematic review of randomized trials comparing standard 4-weekly administration of bone-targeted agents with de-escalated (Q12-weekly) dosing in breast cancer patients was carried out. Medline, PubMed and the Cochrane Register of Controlled Trials were searched from inception until November 2014 for relevant studies. Outcomes of interest included skeletal-related event (SRE) rates, bone pain, adverse events (AEs) and bone turnover biomarkers. Random-effects meta-analyses were carried out. RESULTS: A total of nine citations representing seven unique studies were eligible. One study is ongoing with no reported data. Six studies reported data for at least one outcome of interest. Data were available comparing standard versus de-escalated therapy for pamidronate (1 study, 38 patients), zoledronate (3 studies, 1117 patients) and denosumab (2 studies, 284 patients). Meta-analysis of five trials reporting data for on-study SRE rates between standard (61/443 patients) and de-escalated (49/392 patients) arms produced a summary risk ratio of 0.90 (95% confidence interval 0.63-1.29). Meta-analyses of data for AEs and bone turnover biomarkers also showed no statistically significant differences between standard and de-escalated arms, though only limited numbers of patients and events were present for most analyses. CONCLUSION: In this systematic review of studies of bisphosphonates and denosumab, there appears to be no difference in SREs or pain with de-escalated therapy. While a large, hopefully definitive study is ongoing, the data presented so far are consistent with de-escalation of bone-targeting agents becoming a standard of care for patients with bone metastases from breast cancer.

Model-based correction for scatter and tailing effects in simultaneous 99mTc and 123I imaging for a CdZnTe cardiac SPECT camera.

An advantage of semiconductor-based dedicated cardiac single photon emission computed tomography (SPECT) cameras when compared to conventional Anger cameras is superior energy resolution. This provides the potential for improved separation of the photopeaks in dual radionuclide imaging, such as combined use of (99m)Tc and (123)I . There is, however, the added complexity of tailing effects in the detectors that must be accounted for. In this paper we present a model-based correction algorithm which extracts the useful primary counts of (99m)Tc and (123)I from projection data. Equations describing the in-patient scatter and tailing effects in the detectors are iteratively solved for both radionuclides simultaneously using a maximum a posteriori probability algorithm with one-step-late evaluation. Energy window-dependent parameters for the equations describing in-patient scatter are estimated using Monte Carlo simulations. Parameters for the equations describing tailing effects are estimated using virtually scatter-free experimental measurements on a dedicated cardiac SPECT camera with CdZnTe-detectors. When applied to a phantom study with both (99m)Tc and (123)I, results show that the estimated spatial distribution of events from (99m)Tc in the (99m)Tc photopeak energy window is very similar to that measured in a single (99m)Tc phantom study. The extracted images of primary events display increased cold lesion contrasts for both (99m)Tc and (123)I.