Clinical Spectrum of Congenital Anomalies of Kidney and Urinary Tract in Children.

OBJECTIVES: To evaluate the clinical spectrum and patterns of clinical presentation in congenital anomalies of kidney and urinary tract. METHODS: We enrolled 307 consecutively presenting children with congenital anomalies of kidney and urinary tract at the pediatric nephrology clinic. Patients were evaluated clinically, with serum biochemistry, appropriate imaging and radionuclide scans. RESULTS: The most common anomaly was primary vesicoureteric reflux (VUR) (87, 27.3%), followed by pelviureteral junction obstruction (PUJO) (62,20.1%), multicystic dysplastic kidney (51 16.6%), non-obstructive hydronephrosis (32, 10.4%) and posterior urethral valves (PUV) (23, 7.4%). 247 (80.4%) anomalies had been identified during the antenatal period. Another 33 (10.7%) were diagnosed during evaluation of urinary tract infection, and 21 (6.8%) during evaluation for hypertension at presentation. Obstructive anomalies presented earlier than non-obstructive (7 (3, 22.5) vs 10 (4, 24) mo: (P=0.01)). The median (IQR) ages of presentation for children with PUV (n=23), VUR (n=87) and PUJO (n=62) were 4 (2, 14) mo, 10 (5, 27) mo, and 7 (3, 22.5) mo, respectively. Nine (2.9%) children had extrarenal manifestations. CONCLUSIONS: The median age at clinical presentation for various subgroups of anomalies indicates delayed referral. We emphasize the need for prompt referral in order to initiate appropriate therapeutic strategies in children with congenital anomalies of kidney and urinary tract.

Impact of the Publication of Appropriate Use Criteria on Utilization Rates of Myocardial Perfusion Imaging Studies in Ontario, Canada: A Population-Based Study.

BACKGROUND: Concern regarding overutilization of cardiac imaging has led to the development of appropriate use criteria (AUC). Myocardial perfusion imaging (MPI) is one of the most commonly used cardiac imaging modalities worldwide. Despite multiple iterations of AUC, there is currently no evidence regarding their real-world impact on population-based utilization rates of MPI. Our goal was to assess the impact of the AUC on rates of MPI in Ontario, Canada. We hypothesized that publication of the AUC would be associated with a significant reduction in MPI rates. METHODS AND RESULTS: We conducted a retrospective cohort study of the adult population of Ontario from January 1, 2000, to December 31, 2015. Age- and sex-standardized rates were compared from 4 different periods intersected by 3 published iterations of the AUC. Overall, 3 072 611 MPI scans were performed in Ontario during our study period. The mean monthly rate increased from 14.1/10 000 in the period from January 2000 to October 2005 to 18.2/10 000 between November 2005 and June 2009. After this point in time, there was a reduction in rates, falling to a mean monthly rate of 17.1/10 000 between March 2014 and December 2015. Time series analysis revealed that publication of the 2009 AUC was associated with a significant reduction in MPI rates (P<0.001). This translated into ≈88 849 fewer MPI scans at a cost savings of ≈72 million Canadian dollars. CONCLUSIONS: Our results reflect a potential real-world impact of the 2009 MPI AUC by demonstrating evidence of a significant effect on population-based rates of MPI.

[Nuclear Medicine in Germany. Updated key data and trends from official statistics]. / Nuklearmedizin in Deutschland. Aktualisierte Kennzahlen und Trends aus offiziellen Statistiken.

AIM: Updated presentation of the spectrum of nuclear medicine in-vivo examinations and therapies from officially available statistics on out-patient and in-patient care as well as trends of structural data on nuclear medicine in Germany. METHODS: Data from the German Federal Health Monitoring, from the frequency statistics of the statutory health insurance for out-patients and from the German Medical Association were used and supplemented by data from selective literature searches. RESULTS: In descending order, thyroid, bone and cardiac scans continue to be the most frequent nuclear medicine procedures. With a marked increase of PET/CT and SPECT/CT, the number of basic scintigraphies is declining. Cardiac, lung and brain scans as well as lymph scintigraphies are increasingly requested, bone and thyroid scan decrease. The consultation of nuclear medicine physicians in private practices is increasing by 4 % per year (2009: 2 164 664; 2015: 2 687 359). The number of nuclear medicine physicians in the out-patient sector rose significantly (2009: 756, 2015: 939, growth 24 %) and has remained constant due to restrictions since 2013. The specialist recognitions of women in nuclear medicine increased (proportion currently 46 %). In hospitals, more PET(/CT) scanners (2009: 97; 2015: 125) and fewer gamma cameras (2009: 594; 2015: 550) are operated. The number of non-thyroid (and also out-patient) radionuclide therapies continued to increase. CONCLUSION: With increased use of hybrid technologies, the nuclear medicine spectrum shows positive trends especially in nuclear cardiology and extra-thyroid therapy. These developments must be taken into account when amending regulations of specialist training and medical student teaching.

Opportunities for improvement on current nuclear cardiology practices and radiation exposure in Latin America: Findings from the 65-country IAEA Nuclear Cardiology Protocols cross-sectional Study (INCAPS).

BACKGROUND: Comparison of Latin American (LA) nuclear cardiology (NC) practice with that in the rest of the world (RoW) will identify areas for improvement and lead to educational activities to reduce radiation exposure from NC. METHODS AND RESULTS: INCAPS collected data on all SPECT and PET procedures performed during a single week in March-April 2013 in 36 laboratories in 10 LA countries (n = 1139), and 272 laboratories in 55 countries in RoW (n = 6772). Eight "best practices" were identified a priori and a radiation-related Quality Index (QI) was devised indicating the number used. Mean radiation effective dose (ED) in LA was higher than in RoW (11.8 vs 9.1 mSv, p < 0.001). Within a populous country like Brazil, a wide variation in laboratory mean ED was found, ranging from 8.4 to 17.8 mSv. Only 11% of LA laboratories achieved median ED <9 mSv, compared to 32% in RoW (p < 0.001). QIs ranged from 2 in a laboratory in Mexico to 7 in a laboratory in Cuba. Three major opportunities to reduce ED for LA patients were identified: (1) more laboratories could implement stress-only imaging, (2) camera-based methods of ED reduction, including prone imaging, could be more frequently used, and (3) injected activity of 99mTc could be adjusted reflecting patient weight/habitus. CONCLUSIONS: On average, radiation dose from NC is higher in LA compared to RoW, with median laboratory ED <9 mSv achieved only one third as frequently as in RoW. Opportunities to reduce radiation exposure in LA have been identified and guideline-based recommendations made to optimize protocols and adhere to the "as low as reasonably achievable" (ALARA) principle.

Comparisons and contrasts in the practice of nuclear cardiology in the United States and Japan.

There are interesting differences between the practice of Nuclear Cardiology in Japan and that in the United States and associated unique challenges. Differences in patient body habitus and the perceived importance of limiting patient radiation dose have resulted in different radiopharmaceutical and imaging protocol preferences. Governmental approval and reimbursement policies for various radiopharmaceuticals have promulgated adoption of different clinical applications. Both countries have experienced a significant decline in the number of nuclear cardiology studies performed, in part due to decreased governmental funding and reimbursement and to the emergence of competing modalities. Whereas precertification and test substitution have impacted negatively on the sustainability and growth of nuclear cardiology in the United States, in Japan those deterrents have not yet been encountered. Instead, communication barriers between nuclear medicine physicians and referring cardiologists are cited as a more significant barrier.

The role of nuclear cardiac imaging in risk stratification of sudden cardiac death.

Sudden cardiac death (SCD) represents a significant portion of all cardiac deaths. Current guidelines focus mainly on left ventricular ejection fraction (LVEF) as the main criterion for SCD risk stratification and management. However, LVEF alone lacks both sensitivity and specificity in stratifying patients. Recent research has provided interesting data which supports a greater role for advanced cardiac imaging in risk stratification and patient management. In this article, we will focus on nuclear cardiac imaging, including left ventricular function assessment, myocardial perfusion imaging, myocardial blood flow quantification, metabolic imaging, and neurohormonal imaging. We will discuss how these can be used to better understand SCD and better stratify patient with both ischemic and non-ischemic cardiomyopathy.

Administered Activities in Pediatric Nuclear Medicine and the Impact of the 2010 North American Consensus Guidelines on General Hospitals in the United States.

UNLABELLED: We sought to describe the practice of pediatric nuclear medicine at general hospitals in the United States and to assess the impact of dose awareness campaigns such as Image Gently. METHODS: A web-based survey was developed that requested information regarding hospital type, whether the hospital practices pediatric nuclear medicine, and the hospital's method for determining the administered activity for children. The survey invitation was emailed to a sample of general hospitals with more than 300 beds, excluding dedicated pediatric, veterans, psychiatric, and rehabilitation hospitals. Data were collected for 5 procedures performed on children: (99m)Tc-methylene diphosphate (MDP) bone scans, (99m)Tc-mercaptoacetyltriglycine (MAG3) renograms, (99m)Tc-dimercaptosuccinic acid (DMSA) renal cortical scans, (99m)Tc-based hepatobiliary scans, and (18)F-FDG PET scans. The sites reported dosage by weight (MBq/kg), minimum and maximum dosages, and the activities that they would administer to 2 hypothetical patients: a 5-y-old boy (20 kg, 110 cm tall) and a 10-y-old girl (30 kg, 140 cm tall). RESULTS: The invitation was delivered to 196 sites, with 121 (61.7%) responding. Eighty-two hospitals (67.8%) performed nuclear medicine on children. All sites scaled administered activity for children, mostly by body weight. Also, 82.4% of sites indicated they were familiar with Image Gently, 57.1% were familiar with the 2010 North American consensus guidelines for children, and 54.9% altered their protocols because of the guidelines. The median value for parameters defined by the guidelines was equal to the guideline-recommended value for all procedures. More than 50% of the sites-particularly those familiar with the guidelines-were compliant with the guidelines regarding both the acquisition parameters and the administered activities for the 2 hypothetical patients. However, there remained a wide variation in practice, sometimes by more than a factor of 10, for sites not familiar with the guidelines. CONCLUSION: Image Gently and the North American guidelines have had a substantial impact on pediatric nuclear medicine practice in the United States. However, a wide variation in practice still exists, particularly for sites not familiar with the guidelines. Further promotion and dissemination of the guidelines and best practice are still necessary.

Improving the Spatial Alignment in PET/CT Using Amplitude-Based Respiration-Gated PET and Respiration-Triggered CT.

UNLABELLED: Respiratory motion during PET can cause inaccuracies in the quantification of radiotracer uptake, which negatively affects PET-guided radiotherapy planning. Quantitative accuracy can be improved by respiratory gating. However, additional miscalculation of standardized uptake value (SUV) in PET images can be caused by inappropriate attenuation correction due to a spatial mismatch between gated PET and CT. In this study, the effect of respiration-triggered CT on the spatial match between CT and amplitude-based respiration-gated PET images is investigated. METHODS: (18)F-FDG PET/CT was performed in 38 patients. Images were acquired on 2 PET/CT scanners, one without and one with continuous bed motion during PET acquisition. The amplitude limits of the amplitude-based respiration-gated PET were used for the respiration-triggered sequential low-dose CT. Both standard (spiral) and triggered CT scans were used to reconstruct the PET data. Spatial mismatch was quantified using the position difference between the lung-liver boundary in PET and CT images, the distance between PET and CT lung lesions' centroids, and the amount of overlap of lesions indicated by the Jaccard similarity coefficient. Furthermore, the effect of attenuation correction was quantified by measuring SUVs in lung lesions. RESULTS: For triggered CT, the average distance between the lung-liver boundary in PET and CT was significantly reduced (4.5 ± 6.7 mm) when compared with standard CT (9.2 ± 8.1 mm) (P < 0.001). The mean distance between the lesions' centroids in PET and CT images was 6.3 ± 4.0 and 5.6 ± 4.2 mm (P = 0.424), for the standard and triggered CT, respectively. Similarly, the Jaccard similarity coefficient was 0.30 ± 0.21 and 0.32 ± 0.20 (P = 0.609) for standard and triggered CT, respectively. For 6 lesions, there was no overlap of PET and CT when the standard CT was used; compared with the triggered CT, these lesions showed (partial) overlap. The maximum and mean SUV increase of the PET/CT compared with the PET/triggered CT was 5.7% ± 11.2% (P < 0.001) and 6.1% ± 10.2% (P = 0.001), respectively. CONCLUSION: Amplitude-based respiration-gated PET in combination with respiration-triggered CT resulted in a significantly improved match in the area of the liver dome and a significantly higher SUV for lung lesions. However, lesions in the lungs did not show a consistent improvement in spatial match.

Justification of the hybrid nuclear medicine examinations.

The annual frequency of nuclear medicine examinations is increasing worldwide. This is partly a consequence of the recently introduced single photon emission tomography, combined with computed tomography, and positron emission tomography, combined with computed tomography, techniques, which combine functional, metabolic and morphological information important for the diagnosis of many diseases. However, since the effective radiation dose is the sum of the dose of two components, the hybrid examinations result in increased patient exposure. Accordingly, their justification becomes mandatory. It starts with their clinical importance-the opportunity to resolve a clinical problem decisive for patients' management. Knowledge of the indications, contraindications and the examinations' limitations is the responsibility of the nuclear medicine physician, as well as the choice of the most adequate examination and protocol. In conclusion, the cost and the accessibility of the examinations should not be the principal consideration as opposed to the diagnostic value and the exposure. Flexible protocols and algorithms should be used for hybrid nuclear medicine examinations.

Focus on GABA(A) receptor function. A comparative analysis of in vivo imaging studies in neuropsychiatric disorders.

UNLABELLED: Impairment of GABA(A) receptor function is increasingly recognized to play a major role in the pathophysiology of neuropsychiatric diseases including anxiety disorder (AD), major depressive disorder (MDD) and schizophrenia (SZ). PATIENTS, METHOD: We conducted a PUBMED search, which provided a total of 23 in vivo investigations with PET and SPECT, in which GABA(A) receptor binding in patients with the primary diagnosis of AD (n = 14, 160 patients, 172 controls), MDD (n = 2, 24 patients, 28 controls) or SZ (n = 6, 77 patients, 90 controls) was compared to healthy individuals. RESULTS: A retrospective analysis revealed that AD, MDD and SZ differed as to both site(s) and extent(s) of GABAergic impairment. Additionally, it may be stated that, while the decline of GABA(A) receptor binding AD involved the whole mesolimbocortical system, in SZ it was confined to the frontal and temporal cortex. CONCLUSION: As GABA is known to inhibit dopamine and serotonin, GABAergic dysfunction may be associated with the disturbances of dopaminergic and serotonergic neurotransmission in neuropsychiatric disorders.

When the value of gold is zero.

This manuscript presents the concerns around the increasingly common problem of not having readily available or useful "gold standard" measurements. This issue is particularly important in critical care where many measurements used in decision making are surrogates of what we would truly wish to use. However, the question is broad, important and applicable in many other areas.In particular, a gold standard measurement often exists, but is not clinically (or ethically in some cases) feasible. The question is how does one even begin to develop new measurements or surrogates if one has no gold standard to compare with?We raise this issue concisely with a specific example from mechanical ventilation, a core bread and butter therapy in critical care that is also a leading cause of length of stay and cost of care. Our proposed solution centers around a hierarchical validation approach that we believe would ameliorate ethics issues around radiation exposure that make current gold standard measures clinically infeasible, and thus provide a pathway to create a (new) gold standard.

Computed tomography utilization rates after the placement of a scanner in an emergency department: a single-center experience.

The convenience of a computed tomography (CT) scanner in the emergency department (ED) may impact utilization rates. Our primary aim was to determine the rate of utilization before and after the placement of an ED CT scanner. Secondary aims were to determine the rate of utilization by anatomic region and during a 5-month period when the ED scanner was unavailable. We performed an electronic chart review of our ED with an annual census of 70,000 patients. We identified all patients over the age of 21 who had a CT scan performed from January 2008 to October 2010. Predetermined data elements were extracted by trained, hypothesis-blinded abstractors. Comparisons overall and within scan subtype were performed using seasonal matching. We found a CT utilization rate of 114 per 1,000 patient visits before and 139 per 1,000 patient visits after the placement of a CT scanner in the ED (p<0.0001). Linear regression analysis found a line with a slope of ß=0.114 (95 % CI=0.107-0.121) and an R2 of 0.508. CT rates increased in the following regions: head CTs by 14 per 1,000 visits (p<0.0001); neck CTs by 3 per 1,000 visits (p<0.0001); abdomen/pelvis CTs by 4 per 1,000 visits (p=0.0015); "other" CTs by 2 per 1,000 visits (p<0.0001). Increased rates of chest and facial CTs approached significance with p values of 0.05. During the 5-month downtime, utilization remained unchanged at 141 per 1,000 visits (p=0.38). Overall CT utilization increased after the placement of a scanner in the ED. Most subtypes of scan increased. Utilization was unchanged during a period of ED scanner unavailability, suggesting that increased utilization may be difficult to reverse.

Primary hyperparathyreosis: is concordant sonography and scintigraphy really so important?

BACKGROUND: In primary hyperparathyreosis, US and scintigraphy are the most usual preoperative localization methods for detection of parathyroid adenomas or hyperplasia. RESULTS: 88 (80 female) patients were detected. Unilateral neck exploration was performed in 43 patients (48.9 %) and bilateral exploration in 45 patients (51.1 %). The cure rate was 97.6 %. None case of parathyroid hyperplasia was detected, there were 2 cases of duplex adenoma. For left/right and quadrant localization, sensitivity of US was 71.05 % and 55.07 %, of scintigraphy 95.77 % and 88.71 %, and in concordant imaging 97.67 % and 96.77 %. Analogically, PPV was: US 91.53 % and 76.00 %, scintigraphy 87.18 % and 74.32 %, concordant imaging 93.33 %and 81.08 %. Only US sensitivity was significantly lower, all other differences showed no statistical significance. CONCLUSION: Our data showed low sensitivity but a high positive predictive value of ultrasonography and a high diagnostic value of scintigraphy. Sensitivity and the positive predictive value of concordant localization showed no significant difference, compared to scintigraphy. The routine need for concordance for parathyroid adenoma localization appears dubious, however, its value for prediction of multiglandular disease remains important for protocols that do not apply peroperative localization (Tab. 2, Ref. 35).

Iodine-131 SPET/CT and 18F-FDG PET/CT for the identification and localization of mediastinal lymph node metastases from differentiated thyroid carcinoma.

Mediastinal lymph node metastases (MLNM) from differentiated thyroid carcinoma (DTC) are considered difficult to diagnose. The aim of this study was to assess the value of iodine-131 (131I) single photon emission tomography/computed tomography (SPET/CT) and of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for the diagnosis of MLNM from DTC. Five hundred and eleven consecutive patients operated for DTC and treated with 131I for ablation of the remnant thyroid and/or for treatment of metastases were enrolled in the study and underwent an 131I whole body scan (131I-WBS). Thirty seven sites of increased 131I uptake, on the 131I-WBS that could be an indication for MLNM were re-evaluated by a 131I-SPET/CT scan. Thirty four other patients with negative 131I-WBS but having elevated serum thyroglobulin (Tg), were examined by 18F-FDG PET/CT to possibly diagnose MLNM. A total of 44 DTC patients with MLNM were identified, among the above 37 and 34 cases: 25/37 (67.6%) cases were examined and identified by 131I-SPET/CT and 19/34 (55.9%) cases by 18F-FDG PET/CT. A total of 25 and 19 cases were identified. The male-to-female ratio and the average age in patients with 18F-FDG-avid MLNM were significantly higher than in patients with 131I-avid MLNM. Among the above 44 patients, 40 patients had superior mediastinal nodal metastases, 9 had aortic nodal metastases and only 1 inferior mediastinal nodal metastases. A patient could have metastases in more than one site. In conclusion, our study suggests that in 511 operated DTC patients, treated for remnant ablation and/or for metastases and examined by 131I-WBS, there were 37 cases doubtful of having MLNM in the 131I-WBS and 34 cases doubtful, because of negative 131I-WBS and elevated Tg. The 131I-SPET/CT scan was sensitive for detecting MLNM in 25 of the 37 cases and the 18F-FDG PET/CT in 19 of the 34 cases. These hybrid imaging modalities, when applied as above, were suitable for detecting more MLNM and thus, better supporting treatment planning in these DTC patients.

Preoperative imaging for early-stage cutaneous melanoma: predictors, usage, and utility at a single institution.

BACKGROUND: Preoperative imaging for early-stage cutaneous melanoma is not recommended by current guidelines. Our goal was to investigate our institutional usage and utility. METHODS: Patients with clinically node-negative cutaneous melanoma undergoing surgery with sentinel lymph node biopsy were identified retrospectively. Any melanoma-related imaging after diagnosis and before surgery was considered a staging study. RESULTS: Five hundred fifteen studies were performed in 409 of 546 (75%) patients. Chest x-rays was performed in 70% and advanced imaging in 14% (computed tomography imaging, magnetic resonance imaging, ultrasound, and positron-emission computed tomography imaging). No metastatic lesions were identified. A Breslow thickness greater than 4 mm (odds ratio = 6.46 vs <1 mm; 95% confidence interval, 2.07 to 20.15) and male sex (odds ratio = 2.62 vs female; 95% confidence interval, 1.26 to 5.46) were associated with an increased likelihood of advanced imaging. CONCLUSIONS: Preoperative imaging was performed in the majority of patients with node-negative melanoma, with 14% undergoing advanced studies. No metastatic lesions were identified, confirming the limited utility in this setting.

Hemorragia masiva después de anticoagulación con bivalirudina en 2 casos de pacientes con trasplante cardiaco / Massive haemorrhage after bivalirudin anticoagulation in two heart transplant patients

La trombopenia inducida por heparina es una complicación autoinmunitaria frecuente. Se trata de un estado protrombótico debido a la formación de anticuerpos contra los complejos heparina/factor plaquetario 4. Ante esta situación es necesario el empleo de fármacos alternativos a la heparina para la anticoagulación durante la circulación extracorpórea. Se exponen 2 casos de trasplante cardiaco en los que se empleó bivalirudina como anticoagulante durante la circulación extracorpórea. En ambos pacientes se observó la aparición de complicaciones hemorrágicas severas. Es necesario mejorar el diagnóstico de la trombopenia inducida por heparina y desarrollar protocolos de empleo de nuevos fármacos alternativos a la heparina. Por ello revisamos los protocolos de actuación y las alternativas terapéuticas a la heparina(AU)

Heparin-induced thrombopenia is a common autoimmune complication. It is a prothrombotic state due to the formation of antibodies against heparin/platelet factor 4 complexes. In this situation drugs other than heparin must be used for anticoagulation during extracorporeal circulation (bypass) surgery. Two cases of heart transplantation are presented in whom bivalirudin was used as an anticoagulant during the cardiopulmonary bypass. Severe bleeding complications were observed in both patients. The diagnosis of heparin-induced thrombopenia needs to be improved, as well as the development of protocols for using new drugs other than heparin. For this reason, we have reviewed current protocols and alternative therapies to heparin(AU)

Paediatric urological investigations--dose comparison between urology-related and CT irradiation.

BACKGROUND: Urological investigation in children frequently involves high radiation doses; however, the issue of radiation for these investigations receives little attention compared with CT. OBJECTIVE: To compare the radiation dose from paediatric urological investigations with CT, which is commonly regarded as the more major source of radiation exposure. MATERIALS AND METHODS: We conducted a retrospective audit in a tertiary paediatric centre of the number and radiation dose of CT scans, micturating cystourethrography exams and urological nuclear medicine scans from 2006 to 2011. This was compared with radiation doses in the literature and an audit of the frequency of these studies in Australia. RESULTS: The tertiary centre audit demonstrated that the ratio of the frequency of urological to CT examinations was 0.8:1 in children younger than 17 years. The ratio of the radiation dose of urological to CT examinations was 0.7:1. The ratio in children younger than 5 years was 1.9:1. In Australia the frequency of urological procedures compared with CT was 0.4:1 in children younger than 17 years and 3.1:1 in those younger than 5 years. The ratio of radiation-related publications was 1:9 favouring CT. CONCLUSION: The incidence and radiation dose of paediatric urological studies is comparable to those of CT. Nevertheless the radiation dose of urological procedures receives considerably less attention in the literature.

Development of a new, fast, user friendly, ray tracing program "CSIM" for the simulation of parallelhole collimators.

We have developed a fast, user friendly, ray-tracing program, "CSIM" for low-energy gamma rays (up to ∼200keV) to simulate the performance characteristics of parallelhole collimators. We have used a ray-tracing approach to find the sensitivity and resolution of the parallelhole collimator by including the penetration of photons through the collimator due to the finite attenuation of the collimator material. "CSIM" can calculate the sensitivity of the collimator, the geometric and penetrating photon ratios, and the 1D and 2D point source response functions (PSF) with the statistical uncertainty for different hole shapes (e.g. square, hexagonal, and cylindrical). We have used "CSIM" to simulate the collimator of the YAP-(S)PETII small animal scanner. We present the analysis of the YAP-(S)PETII scanner round-hole parallel collimator designed for nuclear medicine imaging at 140keV. For this aim, different designs have been considered for a variety of source-collimator distances (b=5, 10, 15, 20cm). Resolution and sensitivity characteristics have been plotted as a function of the collimator thickness and the diameter of the hole. For each value of the source-collimator distance, and for each collimator thickness investigated, the trade-off between sensitivity and spatial resolution has been given as a series of characteristic curves. Then, we compare our simulated resolution and sensitivity results to the analytically calculated ones and found that the analytically calculated results for the YAP-(S)PETII scanner collimator are not far away the results predicted by CSIM and also with the experimentally measured resolution values.

Trends in advanced imaging use for women undergoing breast cancer surgery.

BACKGROUND: Evidence-based guidelines recommend limited perioperative diagnostic imaging for new breast cancer diagnoses. For patients aged >65 years, conventional imaging use (mammography, plain radiographs, and ultrasound) has remained stable, whereas advanced imaging (computed tomography [CT], nuclear medicine scans [positron emission tomography/bone scans], and magnetic resonance imaging [MRI]) use has increased. In this study, the authors evaluated traditional and advanced imaging use among younger patients (aged ≤ 65 years) undergoing breast cancer surgery. METHODS: The MarketScan Commercial Claims and Encounters Research Database from 2005 through 2008 was analyzed to evaluate the use of conventional and advanced diagnostic imaging associated with surgery for ductal carcinoma in situ (DCIS) or stage I through III invasive breast cancer. RESULTS: The study cohort included 52,202 women (13% with DCIS and 87% with stage I-III breast cancer). The proportion of patients undergoing conventional imaging remained stable, whereas the average number of conventional imaging tests per patient increased from 4.21 tests in 2005 to 4.79 tests per patient in 2008 (P < .0001). For advanced imaging, the proportion of women who underwent imaging increased from 48.8% in 2005 to 68.8% in 2008 (P < .0001), as did the number of tests per patient (from 1.53 tests in 2005 to 1.98 tests in 2008; P < .0001). MRI examinations accounted for nearly all of the increase in advanced imaging. Patients who underwent MRI examinations received significantly more traditional imaging tests compared with to those who did not, indicating that these tests are additive and are not replacing traditional imaging. CONCLUSIONS: The current results demonstrate that the use of perioperative breast MRI has increased among women aged <65 years. Further study is indicated to determine whether the benefits of this procedure justify increased use.