Eczema and Urticaria in the Adult Population in Portugal: A Prevalence Study

BACKGROUND AND AIMS

Eczema and urticaria are both inflammatory skin diseases. The prevalence of both diseases varies worldwide and the reasons are unknown. We aimed to investigate the eczema and urticaria prevalence in the Portuguese adult (≥16 years-old) population.

MATERIALS AND METHODS

A telephone interview survey was performed in the last quarter of 2017. To calculate the prevalences, subjects should have been previously diagnosed with eczema/urticaria by a health professional, be aged ≥16 years-old, and reside in Portugal. The sample had a proportion that was approximately representative by population, region, gender, and age group. Odds ratios were performed to measure associations with prevalences. SPSS statistics and values of p<0.05 with 95% confidence intervals were considered statistically significant.

RESULTS

5,000 phone calls were analysed. The prevalence of eczema and urticaria in Portugal is 4.4% and 3.4%, respectively. Algarve is the region with the highest prevalence for both diseases. Being a female is the factor that most influenced these diseases with an OR=1.99 (p<0.001; CI 1.49-2.66) for eczema and 1.73 (p=0.001; CI 1.25 - 2.40) for urticaria, with also higher prevalences (5.7% and 4.2%, respectively).

CONCLUSIONS

The prevalences found are higher than in previous studies in Portugal and comparable to results from other countries. Comparisons among prevalence of eczema are affected by several obstacles. Regarding urticaria, our results seem to be in the same line as others. Being female with eczema and urticaria is more common and represents a higher risk factor than male subjects. According to Harrop et al., 2007, in Europe, atopic eczema is 0.14-0.60% of general eczema. In this way, we can estimate that prevalence of atopic eczema in Portugal is around 0.61-2.64%.

Porphyromonas gingivalis lipopolysaccharide-induced periodontitis and serum amyloid-beta peptides

OBJECTIVE

The aim of this investigation was to determine the circulating levels of amyloid beta (Aβ) peptides using the Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) model to induce periodontitis.

METHODS

Experimental periodontitis was induced in 6 male Sprague-Dawley rats. Alveolar bone loss was measure by micro computed tomography. Serum concentrations of Aβ_1-40 and Aβ_1-42 prior to periodontal induction, at 24 h, 7, 14, and 21 days the last injection of Pg-LPS.

RESULTS

The distance between the cemento-enamel junction and the bone crest (i.e., alveolar bone loss) was significantly higher at the end of periodontal induction compared to baseline (2.92 ± 0.29 mm vs. 3.8 ± 0.28 mm, P < 0.001). Periodontitis evoked a slight acute elevation of Aβ_1-40 serum levels that were maintained during the whole experiment. Aβ_1-42 peptide levels peak at the end of the study. A positive strong correlation was observed between alveolar bone loss and Aβ_1-40 serum levels at 7 days (r = 0.695, P = 0.012) and as well as with serum Aβ_1-42 concentrations at 21 days (r = 0.968, P = 0.002).

CONCLUSIONS

Periodontitis induced Pg-LPS produced increased serum levels of Aβ peptides. Further studies are needed to confirm our results and to investigate the mechanisms by which periodontitis could be associated with an overexpression of Aβ.

Vaginal residence and pharmacokinetic preclinical study of topical vaginal mucoadhesive W/S emulsions containing ciprofloxacin

The aim of this work is to test the in vivo behavior of a mucoadhesive vaginal emulsion resistant to the clearance of vaginal fluids using ciprofloxacin (CPX) as an anti-infective model of drug. CPX is a broad-spectrum antibiotic used in the treatment of sexual tissues infections, as intravenous injection in a dose of 20 mg every 12 h. In this study, CPX was incorporated in water in silicone (W/S) mucoadhesive emulsions and the in vivo residence time and the CPX in vivo absorption and distribution to the sexual organs was studied using the rat as animal model. W/S emulsion shows excellent in vitro bioadhesion having high resistance to the vaginal fluids clearance. The drug release profiles show a constant release of CPX during at least 6 h according to a zero-order kinetics. In vivo computerized PET/CT Image Analysis after intravaginal administration to rats indicates that W/S emulsions remain in the vaginal area for a long time and shows a good absorption of the radiotracers used as markers through the vaginal mucosa. Ciprofloxacin pharmacokinetic studies developed after the single intravaginal administration of W/S emulsion shows a good absorption and distribution of CPX on the uterus and ovarian tissue. A significant concentration of CPX in the sexual tissues was observed after 24 h of administration of W/S emulsion. Therefore, W/S emulsions have a good in vivo residence and drug release in the vaginal mucosae showing a great potential for the treatment of sexual tissues infections, as vaginal bioadhesive delivery systems of antinfectious drugs.

Preclinical characterization and clinical evaluation of tacrolimus eye drops

Severe allergic ocular diseases as atopic keratoconjunctivitis can induce corneal damage due to inflammatory substances released from giant papillae. Tacrolimus eye drops are one of the current therapeutic alternatives for its treatment. This work is aimed at developing and characterizing a 0.03% tacrolimus ophthalmic formulation, which was introduced in three types of vehicles (BBS, PVA and Hyaluronic Acid). For this, we have performed in vitro (stability studies) and in vivo assays (corneal permanence time measured directly by Positron Emission Tomography) of three potential formulations. Next, the best formulation was selected, and its toxicological profile and clinical effectiveness have been evaluated. The biopermanence studies (direct measurements and PET/CT) showed that the formulations with PVA and Hyaluronic Acid present more retention time on the ocular surface of rats than PBS. From the stability study, we have determined that tacrolimus with PVA in cold storage is the best option. Tacrolimus with PVA has shown lower cytotoxicity than cyclosporine at early times. On the other hand, the pilot study performed has shown significant improvements in patients, with no noticeable adverse reactions. Based on stability, biopermanence, safety and clinical effectiveness studies, we concluded that tacrolimus-PVA eye drops are a suitable candidate for its clinical application in inflammatory ophthalmology diseases.

Optimization of the reconstruction parameters in [123I]FP-CIT SPECT

The aim of this work was to obtain a set of parameters to be applied in [¹²³I]FP-CIT SPECT reconstruction in order to minimize the error between standardized and true values of the specific uptake ratio (SUR) in dopaminergic neurotransmission SPECT studies. To this end, Monte Carlo simulation was used to generate a database of 1380 projection data-sets from 23 subjects, including normal cases and a variety of pathologies. Studies were reconstructed using filtered back projection (FBP) with attenuation correction and ordered subset expectation maximization (OSEM) with correction for different degradations (attenuation, scatter and PSF). Reconstruction parameters to be optimized were the cut-off frequency of a 2D Butterworth pre-filter in FBP, and the number of iterations and the full width at Half maximum of a 3D Gaussian post-filter in OSEM. Reconstructed images were quantified using regions of interest (ROIs) derived from Magnetic Resonance scans and from the Automated Anatomical Labeling map. Results were standardized by applying a simple linear regression line obtained from the entire patient dataset. Our findings show that we can obtain a set of optimal parameters for each reconstruction strategy. The accuracy of the standardized SUR increases when the reconstruction method includes more corrections. The use of generic ROIs instead of subject-specific ROIs adds significant inaccuracies. Thus, after reconstruction with OSEM and correction for all degradations, subject-specific ROIs led to errors between standardized and true SUR values in the range [-0.5, +0.5] in 87% and 92% of the cases for caudate and putamen, respectively. These percentages dropped to 75% and 88% when the generic ROIs were used.

Association of metreleptin treatment and dietary intervention with neurological outcomes in Celia's encephalopathy

Celia's encephalopathy (progressive encephalopathy with/without lipodystrophy, PELD) is a recessive neurodegenerative disease that is fatal in childhood. It is caused by a c.985C>T variant in the BSCL2/seipin gene that results in an aberrant seipin protein. We evaluated neurological development before and during treatment with human recombinant leptin (metreleptin) plus a dietary intervention rich in polyunsaturated fatty acids (PUFA) in the only living patient. A 7 years and 10 months old girl affected by PELD was treated at age 3 years with metreleptin, adding at age 6 omega-3 fatty acid supplementation. Her mental age was evaluated using the Battelle Developmental Inventory Screening Test (BDI), and brain PET/MRI was performed before treatment and at age 5, 6.5, and 7.5 years. At age 7.5 years, the girl remains alive and leads a normal life for her mental age of 30 months, which increased by 4 months over the last 18 months according to BDI. PET images showed improved glucose uptake in the thalami, cerebellum, and brainstem. This patient showed a clear slowdown in neurological regression during leptin replacement plus a high PUFA diet. The aberrant BSCL2 transcript was overexpressed in SH-SY5Y cells and was treated with docosahexaenoic acid (200 µM) plus leptin (0.001 mg/ml) for 24 h. The relative expression of aberrant BSCL2 transcript was measured by qPCR. In vitro studies showed significant reduction (32%) in aberrant transcript expression. This therapeutic approach should be further studied in this devastating disease.

Preclinical PET Study of Intravitreal Injections

Purpose

This work aimed at describing the time course of vitreous clearance through the use of positron emission tomography (PET) as a noninvasive tool for pharmacokinetic studies of intravitreal injection.

Methods

The pharmacokinetic profile of intravitreal injections of molecules labeled with 18Fluorine (18F) was evaluated in adult Sprague Dawley rats by using a dedicated small-animal PET/computed tomography scanner. Different conditions were studied: three molecules radiolabeled with 18F (18F-FDG, 18F-NaF, and 18F-Choline), three volumes of intravitreal injections (7, 4, and 2 μL), and absence or presence of eye inflammation (uveitis).

Results

Our results showed that there are significant pharmacokinetic differences among the radiolabeled molecules studied but not among the injected volumes. The presence or absence of uveitis was an important factor in vitreous clearance, since the elimination of the drug was clearly increased when this condition is present.

Conclusions

Intravitreal pharmacokinetic studies based on the use of dedicated PET imaging can be of potential interest as noninvasive tools in ophthalmic drug development in small animals.

Positron Emission Tomography for the Development and Characterization of Corneal Permanence of Ophthalmic Pharmaceutical Formulations

Purpose

This work is aimed at describing the utility of positron emission tomography/computed tomography (PET/CT) as a noninvasive tool for pharmacokinetic studies of biopermanence of topical ocular formulations.

Methods

The corneal biopermanence of a topical ophthalmic formulation containing gellan gum and kappa carragenan (0.82% wt/vol) labeled with 18Fluorine (18F) radiotracers (18F-FDG and 18F-NaF) was evaluated by using a dedicated small-animal PET/CT, and compared with the biopermanence of an aqueous solution labeled with the same compounds. Regions of interest (ROIs) were manually drawn on the reconstructed PET images for quantifying the radioactivity concentration in the eye. The biopermanence of the formulations was determined by measuring the radioactivity concentration at different times after topical application. Additionally, cellular and ex vivo safety assays were performed to assess the safety of the performed procedures.

Results

Differences were observed in the ocular pharmacokinetics of the two formulations. After 1.5 hours of contact, 90% of the hydrogel remained in the ocular surface, while only 69% of the control solution remained. Furthermore, it was observed that flickering had a very important role in the approach of the trial. The application of 18F-FDG in the eye was neither irritating nor cytotoxic for human corneal epithelial cells.

Conclusions

The use of small-animal PET and 18F radiotracers in ocular pharmacokinetics of ophthalmic formulations is feasible and could be a safe method for future ocular pharmacokinetic studies in humans.

Recombination in liquid-filled ionization chambers beyond the Boag limit

PURPOSE

The high mass density and low mobilities of charge carriers can cause important recombination in liquid-filled ionization chambers (LICs). Saturation correction methods have been proposed for LICs. Correction methods for pulsed irradiation are based on Boag equation. However, Boag equation assumes that the charge ionized by one pulse is fully collected before the arrival of the next pulse. This condition does not hold in many clinical beams where the pulse repetition period may be shorter than the charge collection time, causing overlapping between charge carriers ionized by different pulses, and Boag equation is not applicable there. In this work, the authors present an experimental and numerical characterization of collection efficiencies in LICs beyond the Boag limit, with overlapping between charge carriers ionized by different pulses.

METHODS

The authors have studied recombination in a LIC array for different dose-per-pulse, pulse repetition frequency, and polarization voltage values. Measurements were performed in a Truebeam Linac using FF and FFF modalities. Dose-per-pulse and pulse repetition frequency have been obtained by monitoring the target current with an oscilloscope. Experimental collection efficiencies have been obtained by using a combination of the two-dose-rate method and ratios to the readout of a reference chamber (CC13, IBA). The authors have also used numerical simulation to complement the experimental data.

RESULTS

The authors have found that overlap significantly increases recombination in LICs, as expected. However, the functional dependence of collection efficiencies on the dose-per-pulse does not change (a linear dependence has been observed in the near-saturation region for different degrees of overlapping, the same dependence observed in the nonoverlapping scenario). On the other hand, the dependence of collection efficiencies on the polarization voltage changes in the overlapping scenario and does not follow that of Boag equation, the reason being that changing the polarization voltage also affects the charge collection time, thus changing the amount of overlapping.

CONCLUSIONS

These results have important consequences for saturation correction methods for LICs. On one hand, the two-dose-rate method, which relies on the functional dependence of the collection efficiencies on dose-per-pulse, can also be used in the overlapping situation, provided that the two measurements needed to feed the method are performed at the same pulse repetition frequency (monitor unit rate). This result opens the door to computing collection efficiencies in LICs in many clinical setups where charge overlap in the LIC exists. On the other hand, correction methods based on the voltage-dependence of Boag equation like the three-voltage method or the modified two-voltage method will not work in the overlapping scenario due to the different functional dependence of collection efficiencies on the polarization voltage.

Evaluation and optimization of occupational eye lens dosimetry during positron emission tomography (PET) procedures

The last recommendations of the International Commission on Radiological Protection for eye lens dose suggest an important reduction on the radiation limits associated with early and late tissue reactions. The aim of this work is to quantify and optimize the eye lens dose associated to nurse staff during positron emission tomography (PET) procedures. PET is one of the most important diagnostic methods of oncological and neurological cancer disease involving an important number of workers exposed to the high energy isotope F-18. We characterize the relevant stages as preparation and administration of monodose syringes in terms of occupational dose. A direct reading silicon dosimeter was used to measure the lens dose to staff. The highest dose of radiation was observed during preparation of the fluorodesoxyglucose (FDG) syringes. By optimizing a suitable vials' distribution of FDG we find an important reduction in occupational doses. Extrapolation of our data to other clinical scenarios indicates that, depending on the work load and/or syringes activity, safety limits of the dose might be exceeded.

A method for estimating DMSA SPECT renal function for assessing the effect of percutaneous nephrolithotripsy on the treated pole

BACKGROUND

The aim of this study was to develop a method for estimating DMSA SPECT renal function on each renal pole in order to evaluate the effect of percutaneous nephrolithotripsy by focusing the measurements on the region through which the percutaneous approach is performed.

METHODS

Twenty patients undergoing percutaneous nephrolithotripsy between November 2010 and June 2012 were included in this study. Both Planar and SPECT-DMSA studies were carried out before and after nephrolithotripsy. The effect of percutaneous nephrolithotripsy was evaluated by estimating the total renal function and the regional renal function of each renal pole. Despite PCNL has been previously reported as a minimally invasive technique, our results showed regional renal function decreases in the treated pole in most patients, affecting the total renal function in a few of them.

RESULTS

A quantification method was used for estimating the SPECT DMSA renal function of the upper, interpolar and lower renal poles. Our results confirmed that total renal function was preserved after nephrolithotripsy. Nevertheless, the proposed method showed that the regional renal function of the treated pole decreased in most patients (15 of 20 patients), allowing us to find differences in patients who had not shown changes in the total renal function obtained from conventional quantification methods.

CONCLUSION

A method for estimating the SPECT DMSA renal function focused on the treated pole enabled us to show for the first time that nephrolithotripsy can lead to a renal parenchymal damage restricted to the treated pole.

The blood-tendon barrier: identification and characterisation of a novel tissue barrier in tendon blood vessels

In the last decade, nanobiotechnology research has emerged as a revolutionising new approach to the 21st century pharmaceutical challenges, offering valuable gains in a vast set of biomedical applications. In the field of bone tissue engineering, a broad range of nanotechnology-based delivery systems have been researched and the most recent developments in high-throughput technology and in silico approaches are creating very high expectations. This review presents a comprehensive overview of the emergent nanotechnology-based materials, processing techniques and research strategies for the delivery of pharmaceutics to bone including the materials general characteristics and the available drug delivery systems to distribute agents systemically or locally. Complementary to what was stated above, it also reviews the latest high-throughput processing techniques and the existent in silico tools (mathematical and computational models) used to help on the design of delivery systems.

Assessing Medication Beliefs of Mental Health Professionals: The Portuguese Version of the Medication Alliance Beliefs Questionnaire

Introduction

Clinician's attitudes are an important consideration in implementing adherence strategies and that these attitudes can be successfully improved as a result of training. The 22-item Medication Alliance Beliefs Questionnaire (MABQ; Byrne et al.2008) was used to assess clinician attitudes towards non-adherence. The MABQ contains five subscales reflecting the clinician's self-efficacy (adequacy), the satisfaction (work satisfaction); their appraisal of their self-worth (self-esteem), their outcome expectancies (pessimism) in relation to non-adherent patients, and the extent to which they understand the difficulties patients might experience in trying to adhere to treatment (empathy).

Aims/objectives

To develop the Portuguese version of the MABQ.

Methods

The MABQ was translated and adapted for Portuguese language. The translation was done by the first author (AC). The accuracy of this translation was discussed in a two focus group of experts, providing opinion on face and content validity. After pre-testing, the final version of the Portuguese translation was produced.

Results

A convenience sample of 65 mental health professionals working in a variety of settings is being collected. The average score in MABQ was 80.06 (SD 9.5). The value of internal reliability coefficient α was 0.80. The intraclass correlation coefficient of total MABQ score was 0.35. The t-test showed that there were no statistically significant differences between the mean values of the measurement scale at two different times (80.4 vs.76.2; P = 0.02).

Conclusion

The attitudes of mental health professionals may have a predictive relationship with treatment outcomes of patients with mental health disorders. The validation of the Portuguese version of MABQ will provide professionals with a new tool to evaluate crucial issues related to medication beliefs.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

How we can enhance treatment adherence? Perspective of patients and clinicians

Introduction

Non-adherence to antipsychotic medication is commonly found in mental health disorders (MHD), thus forming a major obstacle to long-term maintenance treatment and contributing to high relapse rates and also can influence the attitudes and beliefs of mental health professionals (MHP).

Objectives

–assess the beliefs of MHP;

–assess perception of illness in patients with MHD.

Aims

Contribute to treatment adherence of patients with MHD, through developing adequate strategies to their needs.

Methods

In this cross-sectional study, we use a convenience sample of patients with MHD attending in the mental health departments of three general hospitals in Lisbon great area. Data is being collected through individual interviews. We have applied clinical and socio-demographic questionnaire and additional measures to assess symptom severity, treatment adherence and attitudes towards medication. For MHP, we used a optimism scale (ETOS), Difficulty Implementing Adherence Strategies (DIAS); Medication Alliance Beliefs Questionnaire (MABQ).

Results

Two convenience samples were composed by 150 patients with MHD (mean age: 39.7; SD ± 9.8) and 65 MHP (mean age: 37.0; sd 8.3) working in a variety of settings is being collected. From the perspective of patients, the most important reason for adherence is to accept the illness (54,7%, n = 82). 50.8% (n = 33) of MHP believes that if patients are unmotivated for treatment, adherence strategies are unlikely to be effective. 43.1 (n = 28) of MHP agrees that if patients do not accept their illness, any adherence strategies that result.

Conclusion

With this study, we expect to gain further knowledge on the factors related patients and MHP that might influence compliance and, therefore, contribute to the development of effective strategies to promote treatment adherence in MHD.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Assessing Strategies to Improve Antipsychotic Adherence: The Portuguese Version of the Difficulty Implementing Adherence Strategies

Introduction

Non-adherence is a problem throughout medicine and there are many strategies that are used to improve antipsychotic adherence. A review of the literature identified 33 commonly cited strategies for enhancing consumer adherence. Three core themes were identified: Information/Education; Behavioural strategies; and Cognitive/Motivational strategies.

Aims/objectives

To develop the Portuguese version of the DIAS.

Methods

The DIAS was translated and adapted for Portuguese language. The translation was done by the first author (AC). The accuracy of this translation was discussed in a two focus group of experts, providing opinion on face and content validity. The participants were asked to rate how often they had difficulties using each of the 33 strategies with consumers who were non-adherent. A four point Likert scale was used (1 = never; 4 = always) such that higher scores indicated more frequent difficulty using the strategy.

Results

A convenience sample of 65 mental health professionals working in a variety of settings is being collected. The average score in DIAS was 85.0 (SD14.6). The value of internal reliability coefficient α was 0.93. The intraclass correlation coefficient of total MABQ score was 0.45. The t-test showed that there were no statistically significant differences between the mean values of the measurement scale at two different times (84.5 vs.90.5; P = 0.04).

Conclusion

Interventions to improve antipsychotic adherence would benefit from further research. However, it is important always to bear in mind that none of these strategies can be a substitute a positive therapeutic alliance. The Portuguese version of DIAS will provide professionals with a new tool to evaluate the frequency how strategies are implemented and the impact of each strategy in treatment adherence.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Association between suicide attempts and insight among patients with bipolar disorders

Introduction

Insight is an important factor associated with non-compliance and poor outcome. Poor level of insight has been described as a characteristic in patients with acute bipolar disorder with more unawareness in social consequences. In contrast, awareness of having a mental disorder, of its symptoms, of its consequences, and/or of the need for treatment is associated with a number of positive prognostic indicators. Insight is also linked, however, to depression and suicidal ideation in bipolar disorder.

Objectives

(1) Assess the illness perception. (2) Assess the impact of insight in suicidal tendencies.

Aims

Contribute to development measures to improve the insight in bipolar disorders.

Methods

In this cross sectional study we use a convenience sample of patients with bipolar disorder attending in the mental health departments of three general hospitals in Lisbon great area. We have applied clinical and socio-demographic questionnaire and additional measures to assess symptom severity, treatment adherence and illness perception.

Results

A samples was composed by 64 patients with bipolar disorder (mean age = 38.7; SD ± 10.1). A total of 48.4% patients (n = 31) had made a suicide attempted and 23.4% (n = 15) of this patient done 5 or more attempted suicide. We found a significant correlation with symptoms and insight (rs = 0.56; P < 0.01).

Conclusion

Mental health professionals often utilize insight as an indicator of prognosis, because of its association with treatment adherence. The findings of the current study suggest that having intact or good insight may be an indicator for suicidal ideation among patients with bipolar disorders. A brief psychoeducational approach could potentially be effective. We recommend a combined approach to Improve clinical insight in bipolar disorder.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Clinicopathological characteristics of infiltrating lobular breast carcinoma in elderly women: Preliminary results

This study was conducted to investigate the clinicopathological parameters in elderly women (aged >70 years) with infiltrating lobular carcinoma (ILC) of the breast and compare the results with those obtained from younger patients (aged 55-70 years). The study sample included a total of 46 women with ILCs, 10 aged >70 and 36 aged 55-70 years. The parameters analysed were tumor size, histological grade (HG), axillary lymph node involvement, distant metastasis and immunohistochemical expression of estrogen, progesterone and androgen receptors, Ki67, p53 and B cell lymphoma 2. Compared to women aged 55-70 years, ILCs in women aged >70 years were commonly of larger size (P=0.068) and were more frequently HG3 (P=0.024). There were no statistically significant differences in the other parameters analysed. Furthermore, we were unable to determine differences in cancer recurrence and mortality in the two patient subgroups during our follow-up. In conclusion, our preliminary results, based on the limited number of cases included in this study, indicate that i) ILCs in women aged >70 years tended to be larger compared to those in women aged 55-70 years and were more frequently of grade 3; and ii) there were no significant differences in terms of recurrence and mortality between the two patient subgroups during our follow-up.

Impact and correction of the bladder uptake on 18 F-FCH PET quantification: a simulation study using the XCAT2 phantom

The spill-in counts from neighbouring regions can significantly bias the quantification over small regions close to high activity extended sources. This effect can be a drawback for (18)F-based radiotracers positron emission tomography (PET) when quantitatively evaluating the bladder area for diseases such as prostate cancer. In this work, we use Monte Carlo simulations to investigate the impact of the spill-in counts from the bladder on the quantitative evaluation of prostate cancer when using (18)F-Fluorcholine (FCH) PET and we propose a novel reconstruction-based correction method. Monte Carlo simulations of a modified version of the XCAT2 anthropomorphic phantom with (18)F-FCH biological distribution, variable bladder uptake and inserted prostatic tumours were used in order to obtain simulated realistic (18)F-FCH data. We evaluated possible variations of the measured tumour Standardized Uptake Value (SUV) for different values of bladder uptake and propose a novel correction by appropriately adapting image reconstruction methodology. The correction is based on the introduction of physiological background terms on the reconstruction, removing the contribution of the bladder to the final image. The bladder is segmented from the reconstructed image and then forward-projected to the sinogram space. The resulting sinograms are used as background terms for the reconstruction. SUV max and SUV mean could be overestimated by 41% and 22% respectively due to the accumulation of radiotracer in the bladder, with strong dependence on bladder-to-lesion ratio. While the SUVs measured under these conditions are not reliable, images corrected using the proposed methodology provide better repeatability of SUVs, with biases below 6%. Results also showed remarkable improvements on visual detectability. The spill-in counts from the bladder can affect prostatic SUV measurements of (18)F-FCH images, which can be corrected to less than 6% using the proposed methodology, providing reliable SUV values even in the presence of high radioactivity accumulation in the bladder.

Validation of semi-quantitative methods for DAT SPECT: influence of anatomical variability and partial volume effect

The aim of this work was to evaluate the influence of anatomical variability between subjects and of the partial volume effect (PVE) on the standardized Specific Uptake Ratio (SUR) in [(123)I]FP-bib SPECT studies. To this end, magnetic resonance (MR) images of 23 subjects with differences in the striatal volume of up to 44% were segmented and used to generate a database of 138 Monte Carlo simulated SPECT studies. Data included normal uptakes and pathological cases. Studies were reconstructed by filtered back projection (FBP) and the ordered-subset expectation-maximization algorithm. Quantification was carried out by applying a reference method based on regions of interest (ROIs) derived from the MR images and ROIs derived from the Automated Anatomical Labelling map. Our results showed that, regardless of anatomical variability, the relationship between calculated and true SUR values for caudate and putamen could be described by a multiple linear model which took into account the spill-over phenomenon caused by PVE (R² ≥ 0.963 for caudate and ≥0.980 for putamen) and also by a simple linear model (R(2) ≥ 0.952 for caudate and ≥0.973 for putamen). Calculated values were standardized by inverting both linear systems. Differences between standardized and true values showed that, although the multiple linear model was the best approach in terms of variability (X² ≥ 11.79 for caudate and ≤7.36 for putamen), standardization based on a simple linear model was also suitable (X² ≥ 12.44 for caudate and ≤12.57 for putamen).

In vivo quantification of renal function in mice using clinical gamma cameras

INTRODUCTION

In preclinical research, the growing number of transgenic models has led to the need for renal-function studies in mice. Many efforts have been made to develop dedicated SPECT systems for rodents, but their availability is limited due to high capital costs. The aim of this work is to demonstrate the feasibility of mouse renal imaging by using an inexpensive alternative based on clinical gamma-cameras.

METHODS

A healthy mouse was scanned 3 h after injection of 6 mCi of Dimercaptosuccinic acid (DMSA) labeled with 99mTc by using a single-head gamma-camera in conjunction with a dedicated pinhole collimator. List-mode data were binned to emulate multiple injections of 1 mCi, 0.1 mCi and 0.01 mCi of 99mTc-DMSA and 6-min ventral and dorsal planar images were acquired and SPECT imaging (60 projection images acquired over 60 min) was performed. An optimization of the protocols in terms of injected activity, time scan, renal cortex uniformity and cortex-to-pelvis contrast was carried out.

RESULTS

The appropriate protocols were an injected activity of 0.6 mCi, combined with duration of scanning of 1 min for planar and 60 min for SPECT imaging. Our results were validated through the relative quantification of renal function, which showed that both kidneys contributed equally to the total function. They showed that functional structures of the mouse kidneys can be visually distinguished as easily as in human studies.

CONCLUSIONS

Our findings showed the feasibility of conducting quantitative DMSA SPECT studies of anesthetized mice on clinical gamma cameras.

Cell membrane CD44v6 levels in squamous cell carcinoma of the lung: association with high cellular proliferation and high concentrations of EGFR and CD44v5

Membranous CD44v6 levels in tumors and surrounding samples obtained from 94 patients with squamous cell lung carcinomas were studied and compared to clinical stage, cellular proliferation, membranous CD44v5 levels, epidermal growth factor receptor EGFR and cytoplasmatic concentrations of CYFRA 21.1. CD44v6 positive values were observed in 33/38 non-tumor samples and in 76/94 tumor samples, but there were not statistically significant differences between both subgroups. In CD44v6 positive tumor samples, CD44v6 was not associated with clinical stage, histological grade, ploidy and lymph node involvement, but significant association was found with high cellular proliferation. Likewise, CD44v6 positive tumors had significantly higher levels of EGFR and CD44v5. In patients with squamous cell lung carcinomas and clinical stage I, positive CD44v6 cases were associated with the same parameters. Furthermore, positive CD44v5 squamous tumors were associated significantly with histological grade III and lower levels of CYFRA21.1. Our findings support the value of CD44v6 as a possible indicator of poor outcome in patients with squamous lung carcinomas.

Improved image quality in pinhole SPECT by accurate modeling of the point spread function in low magnification systems

PURPOSE

Single photon emission computed tomography (SPECT) has become an important noninvasive imaging technique in small-animal research. Due to the high resolution required in small-animal SPECT systems, the spatially variant system response needs to be included in the reconstruction algorithm. Accurate modeling of the system response should result in a major improvement in the quality of reconstructed images. The aim of this study was to quantitatively assess the impact that an accurate modeling of spatially variant collimator/detector response has on image-quality parameters, using a low magnification SPECT system equipped with a pinhole collimator and a small gamma camera.

METHODS

Three methods were used to model the point spread function (PSF). For the first, only the geometrical pinhole aperture was included in the PSF. For the second, the septal penetration through the pinhole collimator was added. In the third method, the measured intrinsic detector response was incorporated. Tomographic spatial resolution was evaluated and contrast, recovery coefficients, contrast-to-noise ratio, and noise were quantified using a custom-built NEMA NU 4-2008 image-quality phantom.

RESULTS

A high correlation was found between the experimental data corresponding to intrinsic detector response and the fitted values obtained by means of an asymmetric Gaussian distribution. For all PSF models, resolution improved as the distance from the point source to the center of the field of view increased and when the acquisition radius diminished. An improvement of resolution was observed after a minimum of five iterations when the PSF modeling included more corrections. Contrast, recovery coefficients, and contrast-to-noise ratio were better for the same level of noise in the image when more accurate models were included. Ring-type artifacts were observed when the number of iterations exceeded 12.

CONCLUSIONS

Accurate modeling of the PSF improves resolution, contrast, and recovery coefficients in the reconstructed images. To avoid the appearance of ring-type artifacts, the number of iterations should be limited. In low magnification systems, the intrinsic detector PSF plays a major role in improvement of the image-quality parameters.

Monte Carlo simulations versus experimental measurements in a small animal PET system. A comparison in the NEMA NU 4-2008 framework

In this work a comparison between experimental and simulated data using GATE and PeneloPET Monte Carlo simulation packages is presented. All simulated setups, as well as the experimental measurements, followed exactly the guidelines of the NEMA NU 4-2008 standards using the microPET R4 scanner. The comparison was focused on spatial resolution, sensitivity, scatter fraction and counting rates performance. Both GATE and PeneloPET showed reasonable agreement for the spatial resolution when compared to experimental measurements, although they lead to slight underestimations for the points close to the edge. High accuracy was obtained between experiments and simulations of the system's sensitivity and scatter fraction for an energy window of 350-650 keV, as well as for the counting rate simulations. The latter was the most complicated test to perform since each code demands different specifications for the characterization of the system's dead time. Although simulated and experimental results were in excellent agreement for both simulation codes, PeneloPET demanded more information about the behavior of the real data acquisition system. To our knowledge, this constitutes the first validation of these Monte Carlo codes for the full NEMA NU 4-2008 standards for small animal PET imaging systems.

Histological grade (HG) in invasive ductal carcinomas of the breast of less than 1 cm: clinical and biological associations during progression from HG1 to HG3

AIM

To study the clinical and biological (cellular proliferation and hormone-dependence) associations during the progression of histological grade (HG), from HG1 to HG3, in invasive ductal carcinomas of the breast (IDC) <1 cm.

PATIENTS AND METHODS

The study group included 119 women with IDCs ≤1 cm, aged between 27 and 88 years (median=61 years). The parameters analyzed were: histological grade (HG1: 52; HG2: 45; HG3: 22); axillary lymph node involvement (N); distant metastasis (M); and immunohistochemical expression of estrogen (ER), progesterone (PR) and androgen (AR) receptors, and Ki67, p53 and B-cell lymphoma 2 (BCL2).

RESULTS

Compared to HG3 tumors, HG1s exhibited an increased expression of ER, AR and BCL2, as well as lower expression of p53 and Ki67. In HG1 tumors, significant (p<0.05) associations were found between ER and PR (positive), ER and p53 (negative), ER and Ki67 (negative), PR and AR (positive), PR and p53 (negative), AR and p53 (negative), p53 and BCL2 (negative), and between BCL2 and Ki67 (negative). HG3s only showed significant (p<0.05) associations between ER and Ki-67 (negative) and between BCL2 or Ki-67 (negative). Only two significant relationships (ER-Ki67 and BCL2-Ki67) persisted in all three grades.

CONCLUSION

Our results lead us to the following conclusions: i) compared HG1, HG3 ductal carcinomas exhibited decreased expression of ER, AR and BCL2 and increased expression of p53 and Ki67; and ii) only two significant and negative relations (ER-Ki67 and BCL2-Ki67) persisted in all three grades.

Correction for FDG PET dose extravasations: Monte Carlo validation and quantitative evaluation of patient studies

PURPOSE

Current procedure guidelines for whole body [18F]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) state that studies with visible dose extravasations should be rejected for quantification protocols. Our work is focused on the development and validation of methods for estimating extravasated doses in order to correct standard uptake value (SUV) values for this effect in clinical routine.

METHODS

One thousand three hundred sixty-seven consecutive whole body FDG-PET studies were visually inspected looking for extravasation cases. Two methods for estimating the extravasated dose were proposed and validated in different scenarios using Monte Carlo simulations. All visible extravasations were retrospectively evaluated using a manual ROI based method. In addition, the 50 patients with higher extravasated doses were also evaluated using a threshold-based method.

RESULTS

Simulation studies showed that the proposed methods for estimating extravasated doses allow us to compensate the impact of extravasations on SUV values with an error below 5%. The quantitative evaluation of patient studies revealed that paravenous injection is a relatively frequent effect (18%) with a small fraction of patients presenting considerable extravasations ranging from 1% to a maximum of 22% of the injected dose. A criterion based on the extravasated volume and maximum concentration was established in order to identify this fraction of patients that might be corrected for paravenous injection effect.

CONCLUSIONS

The authors propose the use of a manual ROI based method for estimating the effectively administered FDG dose and then correct SUV quantification in those patients fulfilling the proposed criterion.

Simulated FDG-PET studies for the assessment of SUV quantification methods

AIM

To study in detail the accuracy and repeatability of three commonly used methods for SUV estimation in solitary pulmonary nodules.

MATERIAL AND METHODS

We have designed a realistic framework based on simulated FDG-PET acquisitions from an anthropomorphic activity model that included solitary pulmonary nodules (different sizes) of well-known SUV. This framework enables us to compare the SUV values obtained from the reconstructed PET images with the real SUV values. Three commonly used methods (SUVmax, SUVmean and SUV50) were used to estimate the tumor activity.

RESULTS

Our results showed the tumor activity was overestimated using SUVmax and clearly subestimated using SUVmean. Instead, the quantification of SUV50 showed great agreement with the simulated tumor activity and only slight subestimation was found for very small lesions. On the other hand, SUVmean showed better performance than SUV50 in terms of repeatability, providing variabilities below 5% for all tumor sizes and for injected doses as low as 111 MBq.

CONCLUSIONS

Our findings showed that SUV50 provided better performance for estimating accurately tumor SUV values in pulmonary nodules, but SUVmean showed better results in terms of repeatability.