332 Paediatric Ultrasound Scan: Are We Providing a Quality Service?

Aim

Ultrasound scan is the preferred imaging modality in children as it carries no risk of radiation exposure. In this audit, the number of inpatient paediatric ultrasound referrals was assessed over a period of one year. The waiting time was also reviewed in addition to the impact of the results on the management plan.

Method

This was a retrospective audit which included patients who were below 16 and had inpatient ultrasound scan. Case notes were included from January 2020 to December 2020 in a busy district hospital in the UK. The time taken to perform the ultrasound scans and the impact on the management plan were only analysed for the scans requested for abdominal pain.

Results

A total of 914 paediatric ultrasounds scans were requested in 2020. A total number of 28 scans were requested for abdominal pain. The waiting time ranged from 3 to 135 hours with a mean of 23 hours. No scans were positive for appendicitis. Only 2 scans were positive for gynaecological pathologies, i.e., ovarian cysts. All the 28 patients were discharged without undergoing any procedure. Out of the 28 patients, 15 patients had a length of hospital stay of more than 24 hours before discharge.

Conclusions

A mean delay of 23 hours could potentially delay the management of paediatric patients with acute abdominal pathology. None of the patients in this audit underwent any procedure following performed scans. This may indicate that such scans did not alter the management of the studied patients in this audit.

Polymyalgia rheumatica-like presentation in a case of diffuse large B-cell lymphoma: a diagnostic pitfall

Diffuse large B-cell lymphoma (DLBCL) commonly presents with systemic manifestations including fever, weight loss, and night sweats. Uncommonly, patients with DLBCL can present with musculoskeletal manifestations mimicking polymyalgia rheumatica (PMR). Herein, the case of a 61-year-old woman who presented with pain in the bilateral shoulders, arms, hands, knees, pelvic girdle, and neck with bouts of fever, is presented. Laboratory workup for infectious and connective tissue diseases was non-revealing, except for elevated inflammatory markers. A positron emission tomography (PET)/computed tomography (CT) scan was suggestive of PMR, but also revealed enlarged lymph nodes initially thought to be reactive in nature. However, a lymph node biopsy showed findings consistent with DLBCL. This case highlights the importance of a thorough investigational workup when cases with features of PMR do not meet the proper criteria for this diagnosis to be made, in order not to miss a hematopoietic neoplasm with a PMR-like presentation.

Risk adapted therapeutic strategy in newly diagnosed acute myeloid leukemia: Refining the outcomes of ELN 2017 intermediate-risk patients

INTRODUCTION

Despite advances in the treatment of acute myeloid leukemia (AML), cytotoxic chemotherapy remains the standard induction regimen.

PATIENTS AND METHODS

In this single center retrospective study, we assessed outcomes of 99 consecutive adult AML patients treated with a risk-adapted strategy with a median follow-up of 35.5 months.

RESULTS

We identified 24 (24 %), 55 (56 %) and 20 (20 %) patients classified as favorable-, intermediate-, and adverse- risk group respectively, according to the European LeukemiaNet (ELN) 2017 classification. Patients either received idarubicin and cytarabine induction chemotherapy with or without FLT3 inhibitors or hypomethylating agents based on age and comorbidity. The complete response (CR) rate was 76 % (82 % and 61 % in patients aged < 60 and ≥ 60, respectively). For the whole cohort, the 3-year overall survival (OS) was 53 %, being 62 % and 30 % in patients aged < 60 and ≥ 60, respectively. The 3-year leukemia-free survival (LFS) was 54 %, with 56 % and 45 % in patients aged < 60 and ≥ 60, respectively. The 3-year LFS were 58 %, 62 % and 25 % for patients within ELN favorable-, intermediate-, and adverse-risk groups respectively. Twenty-seven (36 %) out of 75 patients with intermediate- and adverse-risk disease underwent allogeneic hematopoietic cell transplantation (allo-HCT) in first CR with 92 % of them receiving post-transplant maintenance consisting of azacitidine in 19 (76 %) patients or sorafenib in 6 (24 %) patients. Of these patients younger than 60 years, the 3-year OS and LFS were 85 % and 69 %, respectively.

CONCLUSION

These results indicate an improved OS for AML patients especially in intermediate-risk category who were treated with a total therapy consisting of induction chemotherapy followed by allo-HCT and post-transplant maintenance.

Diagnosing Lymphoproliferative Disorders Using Core Needle Biopsy Versus Surgical Excisional Biopsy: Three-Year Experience of a Reference Center in Lebanon

BACKGROUND

Despite current guidelines, a significant increase in the use of core needle biopsy (CNB) has been noted. Our aims were to determine the profile of patients referred for image-guided biopsies, to assess the diagnostic yield of these biopsies, and to learn whether CNB is an effective alternative to surgical excisional biopsy (SEB).

PATIENTS AND METHODS

All lymph node biopsy samples evaluated in the Department of Pathology and Laboratory Medicine from 2014 to 2017 were included. Patients' demographics, biopsy type, and final diagnosis were recorded and classified as diagnostic or nondiagnostic. The reasons for the latter were evaluated and follow-up was obtained, where available.

RESULTS

A total of 373 cases, 210 CNB and 163 SEB, were collected. The diagnostic yield was 79% for CNB compared to 97% for SEB. The choice of CNB versus SEB was not dependent on patient's age, gender, or clinical suspicion of malignancy. Failure to reach a diagnosis was due to insufficient or suboptimal tissue in most nondiagnostic CNBs. Lymphoma was equally diagnosed among CNB and SEB. CNB was at an advantage in diagnosing large B-cell lymphomas.

CONCLUSION

When performed adequately, CNB is a good substitute for SEB. Strict and specific guidelines need to be updated and adopted to indicate how and when it can be used, including the recommendation of concomitant complementary diagnostic laboratory testing such as flow cytometry. The latter should be readily available in order to not compromise the quality and accuracy of the diagnoses.

Diagnostic performance of Gallium-68 prostate-specific membrane antigen positron emission tomography-computed tomography in intermediate and high risk prostate cancer

Gallium-68 prostate-specific membrane antigen positron emission tomography-computed tomography (Ga-68 PSMA PET/CT) is an imaging modality that promises improved sensitivity and specificity of detection of prostate cancer lesions based on their increased uptake of PSMA-based radiotracers. It remains an emerging modality that has not yet been endorsed in the guidelines for the management of prostate cancer pending more established evidence to prove its efficacy. The objective of the study is to assess the value of Ga-68 PSMA PET/CT in the detection and localization of patients diagnosed with intermediate or high risk prostate cancer.Twenty three patients with intermediate or high risk prostate cancer had undergone Ga-68 PSMA PET/CT imaging prior to robotic assisted radical prostatectomy. Surgical specimens were then submitted for histological examinations. Lesions visualized on PET/CT and histology were independently mapped unto a 36-segment (Prostate Imaging Reporting and Data System version 2 [PI-RADS v.2]) map of the prostate. Concordance of visualization on PET/CT as compared to the histology as gold standard reference was then assessed. Lesions visualized on PET/CT and histology were independently mapped unto a 36-segment (PI-RADS v.2) map of the prostate. Concordance of visualization on PET/CT as compared to the histology as gold standard reference was then assessed.Sensitivity for all lesions identified on Ga-68 PSMA PET/CT was 42.37%; specificity was 88.61%. Both parameters were higher when considering only index lesions for which sensitivity was 68.42% and specificity was 98.23%. Sensitivity for the index lesions in intermediate risk group was 53.2% and was higher in the high risk group reaching 83.33%.Ga-68 PSMA PET/CT provides accurate localization of tumor lesions in patients with intermediate and high risk prostate cancer.

Lack of expression of ALK and CD30 in breast carcinoma by immunohistochemistry irrespective of tumor characteristics

CD30 is a member of the tumor necrosis factor family of cell surface receptors normally expressed in lymphocytes, as well as some lymphomas, but has been described in other malignancies. Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor that belongs to the insulin receptor superfamily, and is normally expressed in neural cells, but has been detected in several malignancies. There is conflicting data in the literature that describes the expression of these receptors in breast cancer, and the aim of this study is to test the expression of CD30 and ALK in a cohort of Middle Eastern patients with breast carcinoma.Cases of invasive breast cancer from the archives of AUBMC were reviewed over a period of 9 years, and the blocks that were used for immunohistochemical staining for ER, PR, Her-2/neu were selected. Immunohistochemical staining for CD30 (JCM182) and ALK (5A4 and D5F3) was performed.Two hundred eighty-four cases were identified (2 cases were male), with a mean age of 55 ± 12. CD30 and ALK expression was not seen in any of the cases.Our cohort showed complete negativity to both CD30 and ALK, adding to the conflicting data available in the literature, and more studies are needed to reliably identify a trend of expression of CD30 and ALK in breast carcinoma, especially in the Middle East.

EMT Markers in Locally-Advanced Prostate Cancer: Predicting Recurrence?

Background: Prostate cancer (PCa) is the second most frequent cause of cancer-related death in men worldwide. It is a heterogeneous disease at molecular and clinical levels which makes its prognosis and treatment outcome hard to predict. The epithelial-to-mesenchymal transition (EMT) marks a key step in the invasion and malignant progression of PCa. We sought to assess the co-expression of epithelial cytokeratin 8 (CK8) and mesenchymal vimentin (Vim) in locally-advanced PCa as indicators of EMT and consequently predictors of the progression status of the disease. Methods: Co-expression of CK8 and Vim was evaluated by immunofluorescence (IF) on paraffin-embedded tissue sections of 122 patients with PCa who underwent radical prostatectomies between 1998 and 2016 at the American University of Beirut Medical Center (AUBMC). EMT score was calculated accordingly and then correlated with the patients' clinicopathological parameters and PSA failure. Results: The co-expression of CK8/Vim (EMT score), was associated with increasing Gleason group. A highly significant linear association was detected wherein higher Gleason group was associated with higher mean EMT score. In addition, the median estimated biochemical recurrence-free survival for patients with < 25% EMT score was almost double that of patients with more than 25%. The validity of this score for prediction of prognosis was further demonstrated using cox regression model. Our data also confirmed that the EMT score can predict PSA failure irrespective of Gleason group, pathological stage, or surgical margins. Conclusion: This study suggests that assessment of molecular markers of EMT, particularly CK8 and Vim, in radical prostatectomy specimens, in addition to conventional clinicopathological prognostic parameters, can aid in the development of a novel system for predicting the prognosis of locally-advanced PCa.

Ki67 and P53 in Relation to Disease Progression in Metastatic Pancreatic Cancer: a Single Institution Analysis

We investigated the expression patterns of Ki67 and p53 in metastatic pancreatic adenocarcinomas and analyzed their relationship with disease progression-free survival (PFS) and overall survival (OS) in the overall study population and in patients treated with a gemcitabine-containing chemotherapy versus FOLFIRINOX chemotherapy. Patients with histologically confirmed stage IV adenocarcinoma of the pancreas treated at AUBMC were included after obtaining institutional review board approval (IRB ID: IM.ST.05). The ROC was plotted to identify the threshold Ki-67, p53 and CA19-9 value for disease progression, the identified value was further used in Kaplan Meier curves to compare PFS for both groups (gemcitabine versus FOLFIRINOX). A value of p < 0.05 was considered significant in all analyses. On univariate analysis, patients who had a Ki-67 > 12.5% or a p53 > 15% had significantly shorter PFS (p = 0.034 and p = 0.016, respectively). This effect was restricted to Gemcitabine or gemcitabine-combination treated patients. A decrease in CA19-9 levels 6-8 weeks after chemotherapy of >58% had significantly longer PFS (p = 0.027). On multivariate analysis after controlling for grade, age and P53, Ki-67 remained significant, for every one unit increase in Ki-67 the progression risk increases by 1.017 times. Our study highlights the negative impact of high P53 expression and Ki67 proliferation index on PFS in patients with metastatic pancreatic cancer.

Primary synovial sarcoma of the kidney: a case report of complete pathological response at a Lebanese tertiary care center

Background

Primary synovial sarcoma of the kidney is a rare type of soft tissue sarcoma. Its presenting features can resemble those of other renal tumors; rendering its early diagnosis, a dilemma. Several cases of renal synovial sarcoma have been reported in the literature with varying treatment options and outcomes. This article describes a rare case of primary renal synovial sarcoma and reviews all cases in the literature.

Case presentation

A 26-year-old male presented with flank pain and hematuria. Initially diagnosed with Wilm’s tumor, revision of pathology and histology, along with the immunohistochemical profile, confirmed, nevertheless, the diagnosis of primary monophasic synovial sarcoma of the kidney with the SYT-SSX2 fusion transcript. Follow-up, post nephrectomy, revealed recurrence within the lungs and at the surgical bed. Surgical resection followed by adjuvant chemotherapy regimen constituting of Doxorubicin and Ifosfamide, achieved complete pathological response.

Conclusion

In this case report, we emphasize the need for accurate diagnosis and prompt treatment. We propose multimodality treatment approach including surgery along with anthracycline-based chemotherapy to induce complete remission.

Undifferentiated Nasopharyngeal Carcinoma Mimicking Hodgkin Lymphoma With CD30 Expression

The presence of CD30-expressing Hodgkin-like cells with a background of inflammation and eosinophils in a young adolescent is usually diagnostic of classical Hodgkin lymphoma. Herein we present the case of a 12-year-old boy presenting with enlarged cervical lymph node characterized by the presence of Hodgkin-like cells expressing CD30 and EBV-LMP1 with a Hodgkin-like background. The Hodgkin-like cells were negative for CD15, CD20, CD45, and Pax-5. The tumor cells, however, expressed several cytokeratins, confirming the diagnosis of an undifferentiated carcinoma nasopharyngeal type. This case highlights the importance of possessing a high index of suspicion when encountering lymph nodes with Hodgkin-like cells and a Hodgkin-like background, even with CD30 expression, as the differential can include undifferentiated carcinoma nasopharyngeal type.

Acute promyelocytic leukemia with increased bone marrow reticulin fibrosis: Description of three cases and review of the literature

Pathologic increase in bone marrow reticulin fibrosis can be present in many malignant hematopoietic diseases. In acute leukemia, one-third of patients have some degree of marrow reticulin fibrosis at presentation, which is thought to be related to cytokine release from blasts. Marrow fibrosis is particularly common in acute megakaryoblastic leukemia, while this change is rarely seen in acute promyelocytic leukemia. Six case reports of acute promyelocytic leukemia with marrow reticulin fibrosis have been described so far in the literature. Herein, we present three cases of classical acute promyelocytic leukemia with increased marrow reticulin fibrosis encountered in our institution, summarizing their clinicopathologic features, treatment, and outcome to date. Awareness of the features of acute promyelocytic leukemia with marrow reticulin fibrosis is important as it may guide treatment options.

Activating BRAF Mutations Detected in Mixed Hürthle Cell Carcinoma and Multifocal Papillary Carcinoma of the Thyroid Gland

Despite the increase in the incidence of thyroid carcinomas, the occurrence of collision tumors in the thyroid remains a rare event. We present the case of a 69-year-old female who presented to the emergency department with a chief complaint of painful neck swelling. Imaging revealed a large right hemithyroid mass and a left hemithyroid nodule. Fine needle aspiration of the lesions and subsequent total thyroidectomy revealed a Hürthle cell carcinoma in the right lobe and bilateral multicentric papillary carcinoma foci, including 2 foci with a classical pattern and 1 encapsulated follicular variant in the isthmus. BRAF gene mutation analysis revealed V600E gene mutation in the classical variants of papillary carcinoma and in the Hürthle cell carcinoma. The focus of follicular variant of papillary carcinoma in the isthmus and a sample from normal thyroid tissue did not harbor BRAF mutations. This case is remarkable in being an unusual report of a follicular Hürthle cell carcinoma harboring the BRAF V600E mutation and occurring in collision with multifocal papillary carcinoma. Documentation of such cases is important as it helps better understand the pathogenesis, clinical behavior, and radiologic findings of such rare lesions and to determine the optimal treatment modalities.

(18) F-FDG PET-CT and trephine biopsy assessment of bone marrow involvement in lymphoma

The ability of positron emission tomography-computerized tomography (PET-CT) to accurately detect bone marrow involvement (BMI) has been suggested in Hodgkin lymphoma (HL) and diffuse large B-cell lymphoma (DLBCL), but its abilities in other histologies is less established. The aim of this retrospective study was to confirm the role of PET-CT in detecting BMI in DLBCL and HL, and to explore its usefulness in other subtypes. Of the 149 newly diagnosed patients, common subtypes included DLBCL, follicular lymphoma (FL) and HL. In DLBCL, the sensitivity and specificity of PET-CT at diagnosis were 75% and 92%. In FL, the sensitivity and specificity of PET-CT were 67% and 85% at diagnosis, and 73% and 89% at relapse. In HL, the sensitivity and specificity were 100% and 74%. PET-CT was able to detect BMI in patients with negative biopsies. Most of the patients in which PET-CT failed to identify BMI were already advanced stage by imaging. In this analysis, PET-CT was highly accurate for detecting BMI at diagnosis in DLBCL and HL and highly specific in FL at diagnosis and relapse. Results also suggested the diagnostic advantage of PET-CT over bone marrow biopsy in detecting BMI. Prospective evaluation is necessary and may eliminate biopsies in future patients.

Extranodal (dural) Rosai-Dorfman disease radiologically and histologically mimicking meningioma: a case report

BACKGROUND

Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) is an idiopathic nonneoplastic lymphohistiocytic proliferation with variable clinical presentations, sometimes mimicking other disorders including neoplasm. Particularly, intracranial Rosai-Dorfman disease is rare and without well-established optimal treatment modalities.

CASE

A 42-year-old man presented with gradually progressive unilateral hearing and vision loss over a two-year period. An MRI of the head showed findings consistent with meningiomatosis. He subsequently underwent a dural biopsy, and histologic examination of the lesion showed sheets of histiocytes positivefor CD68 and S-100 and negative for CD1a within a rich lymphoplasmacytic infiltrate. Some of the histiocytes showed emperipolesis of lymphocytes and plasma cells. These findings were consistent with Rosai-Dorfman disease. Interestingly, EMA-positive meningothelial whorls were seen scattered within the dominantly histiocytic-appearing process, mimicking the appearance of meningioma; these whorls were thought to be reactive in nature.

CONCLUSION

This case is important as it high-lights unusual clinical and histopathologic features of Rosai-Dorfman disease, thereby adding to the spectrum of manifestations of this entity. Awareness of such features is helpful in averting the misdiagnosis of intracranial Rosai-Dorfman disease with reactive meningothelial hyperplasia as meningiomas.

Simultaneous occurrence of a CD30 positive/ALK-negative high grade T-cell lymphoma and plasma cell myeloma: Report of a case

Simultaneous occurrences of T-cell and B-cell neoplasms are rare, and etiological relationships between these two malignancies are poorly understood. We report the case of a 76-year-old man who presented with hypercalcemia, multiple skin nodular lesions, fatigue, episodic fever, and night sweats. PET/CT scan showed diffuse skin and subcutaneous fat plane active lesions, supra- and infra- diaphragmatic active lymph nodes, liver and spleen involvement, bone marrow infiltration, and nonspecific bilateral lung nodules. A skin biopsy showed a high grade CD30-positive/ALK-negative T-cell lymphoma. A bone marrow biopsy showed involvement by the same neoplastic cells. Additionally, a monoclonal lambda restricted plasma cell population (15% of marrow elements) was identified, which, in view of an IgA lambda spike in the serum, was consistent with plasma cell myeloma. To the best of our knowledge, this case is the first reported case of a plasma cell neoplasm associated with an aggressive CD30-positive ALK-negative systemic T-cell lymphoma with skin involvement. Reporting such cases is important as it adds to the pool of rare cases of concomitant T-cell neoplasms and plasma cell myelomas, and might help in determining an etiological relationship, if any, between these two hematological malignancies.

Clinicopathologic features of post-transplant lymphoproliferative disorders arising after pediatric small bowel transplant

Few studies examined the clinicopathologic features of PTLD arising in pediatric SBT patients. Particularly, the association between ATG and PTLD in this population has not been described. Retrospective review of 81 pediatric patient charts with SBT--isolated or in combination with other organs--showed a PTLD incidence of 11%, occurring more frequently in females (median age of four yr) and with clinically advanced disease. Monomorphic PTLD was the most common histological subtype. There was a significant difference in the use of ATG between patients who developed PTLD and those who did not (p < 0.01); a similar difference was seen with the use of sirolimus (p < 0.001). These results suggested a link between the combination of ATG and sirolimus and development of more clinically and histologically advanced PTLD; however, the risk of ATG by itself was not clear. EBV viral loads were higher in patients with PTLD, and median time between detection of EBV to PTLD diagnosis was three months. However, viral loads at the time of PTLD diagnosis were most often lower than at EBV detection, thereby raising questions on the correlation between decreasing viral genomes and risk of PTLD.

EBV-positive low-grade marginal zone lymphoma in the breast with massive amyloid deposition arising in a heart transplant patient: A report of an unusual case

According to the 2008 World Health Organization classification, low-grade lymphomas arising in transplant recipients are not considered as specific types of PTLD. Most such cases are not associated with EBV infections, although rare reports of post-transplant marginal zone lymphoma have been described. We describe the case of an 18-yr-old female with history of heart transplant who developed a breast mass, but was otherwise completely asymptomatic. Surgical excision of the mass and histopathologic examination showed a low-grade B-cell lymphoma most consistent with marginal zone lymphoma with massive amyloid deposition; furthermore, numerous tumor cells were positive for EBV by in situ hybridization for EBV-encoded RNA. The patient was treated with reduction in immunosuppression, and no additional lesions developed. This case describes an atypical presentation of post-transplant low-grade B-cell lymphoma, unusual in its location, histopathologic features, and association with EBV, thereby adding to the rare previous accounts of such an entity, suggesting the need to include post-transplant marginal zone lymphomas in the current classification of PTLD, and helping in determining the optimal treatment modalities for such tumors.

Additive noise properties of active matrix flat-panel imagers

A detailed theoretical and empirical investigation of additive noise for indirect detection, active matrix flat-panel imagers (AMFPIs) has been performed. Such imagers comprise a pixelated array, incorporating photodiodes and thin-film transistors (TFTs), and an associated electronic acquisition system. A theoretical model of additive noise, defined as the noise of an imaging system in the absence of radiation, has been developed. This model is based upon an equivalent-noise-circuit representation of an AMFPI. The model contains a number of uncorrelated noise components which have been designated as pixel noise, data line thermal noise, externally coupled noise, preamplifier noise and digitization noise. Pixel noise is further divided into the following components: TFT thermal noise, shot and 1/f noise associated with the TFT and photodiode leakage currents, and TFT transient noise. Measurements of various additive noise components were carried out on a prototype imaging system based on a 508 microm pitch, 26 x 26 cm2 array. Other measurements were performed in the absence of the array, involving discrete components connected to the preamplifier input. Overall, model predictions of total additive noise as well as of pixel, preamplifier, and data line thermal noise components were in agreement with results of their measured counterparts. For the imaging system examined, the model predicts that pixel noise is dominated by shot and 1/f noise components of the photodiode and TFT at frame times above approximately 1 s. As frame time decreases, pixel noise is increasingly dominated by TFT thermal noise. Under these conditions, the reasonable degree of agreement observed between measurements and model predictions provides strong evidence that the role of TFT thermal noise has been properly incorporated into the model. Finally, the role of the resistance and capacitance of array data lines in the model was investigated using discrete component circuits at the preamplifier input. Measurements of preamplifier noise and data line thermal noise components as a function of input capacitance and resistance were found to be in reasonable agreement with model predictions.

A quantitative investigation of additive noise reduction for active matrix flat-panel imagers using compensation lines

A quantitative investigation of a technique for reducing correlated noise in indirect detection active matrix flat-panel imagers has been reported. Correlated noise in such systems arises from the coupling of electronic noise, originating from fluctuations in external sources such as power supplies and ambient electromagnetic sources, to the imaging array via its address lines. The noise reduction technique involves the use of signals from columns of compensation line pixels located in relatively close proximity to the columns of normal imaging pixels on the array. Compensation line pixels are designed to be as sensitive to externally-coupled noise as columns of normal imaging pixels but are insensitive to incident radiation. For each imaging pixel, correlated noise is removed by subtracting from the imaging pixel signal a signal derived from compensation line pixels located on the same row. The effectiveness of various implementations of this correction has been examined through measurements of signal and noise from individual pixels as well as of noise power spectra. These measurements were performed both in the absence of radiation as well as with x rays. The effectiveness of the correction was also demonstrated qualitatively by means of an image of a hand phantom. It was found that the use of a single compensation line dramatically reduces external noise through removal of the correlated noise component. While this form of the correction increases non-radiation-related uncorrelated noise, the effect can be largely reduced through the introduction of multiple compensation lines. Finally, a position-dependent correction based on compensation lines on both sides of the array was found to be effective when the magnitude of the correlated noise varied linearly across the array.

Strategies to improve the signal and noise performance of active matrix, flat-panel imagers for diagnostic x-ray applications

A theoretical investigation of factors limiting the detective quantum efficiency (DQE) of active matrix flat-panel imagers (AMFPIs), and of methods to overcome these limitations, is reported. At the higher exposure levels associated with radiography, the present generation of AMFPIs is capable of exhibiting DQE performance equivalent, or superior, to that of existing film-screen and computed radiography systems. However, at exposure levels commonly encountered in fluoroscopy, AMFPIs exhibit significantly reduced DQE and this problem is accentuated at higher spatial frequencies. The problem applies both to AMFPIs that rely on indirect detection as well as direct detection of the incident radiation. This reduced performance derives from the relatively large magnitude of the square of the total additive noise compared to the system gain for existing AMFPIs. In order to circumvent these restrictions, a variety of strategies to decrease additive noise and enhance system gain are proposed. Additive noise could be reduced through improved preamplifier, pixel and array design, including the incorporation of compensation lines to sample external line noise. System gain could be enhanced through the use of continuous photodiodes, pixel amplifiers, or higher gain x-ray converters such as lead iodide. The feasibility of these and other strategies is discussed and potential improvements to DQE performance are quantified through a theoretical investigation of a variety of hypothetical 200 microm pitch designs. At low exposures, such improvements could greatly increase the magnitude of the low spatial frequency component of the DQE, rendering it practically independent of exposure while simultaneously reducing the falloff in DQE at higher spatial frequencies. Furthermore, such noise reduction and gain enhancement could lead to the development of AMFPIs with high DQE performance which are capable of providing both high resolution radiographic images, at approximately 100 microm pixel resolution, as well as variable resolution fluoroscopic images at 30 fps.

A review of achievements of the national schistosomiasis control program in middle and upper Egypt areas

In Egypt the "national schistosomiasis control program" was formulated to control transmission by reduction of prevalence and intensity of current infections, and thereby achieve an acceptable level of schistosomiasis disease control. The program was implemented foremost in Middle Egypt (1977) and Upper Egypt (1980), collectively extending 800 km alongside of the River Nile and accommodate about 10.5 million people. Schistosoma haematobium has been essentially the prevailing species infection in both areas. The strategy of control entailed both area-wide mollusciciding with niclosamide, and selective population chemotherapy with metrifonate. Evaluation in 1986 showed that prevalence dropped from pre-control 29.4% in Middle Egypt and 26.3% in Upper Egypt to 6% and 7.8% respectively, together with a remarkable drop of infections among children. Also mean intensity attained low levels consistent of low grade infections. It is evident therefore that in these areas where an enhancement of schistosomiasis infections had been anticipated the employment of the twofold strategy effected a state of low-prevalence/low-intensity signifying a lowered reservoir of infection and a substantial interference with the potentials of transmission.

Comparison of deficits in electrical self-stimulation after ibotenic acid lesion of the lateral hypothalamus and the medial prefrontal cortex

The aim of the present study was to compare the self-stimulation deficit produced by a unilateral injection of the neurotoxin, ibotenic acid, in the lateral hypothalamus (LH) to the deficit produced by the same unilateral injection in the medial prefrontal cortex (MPC). Four groups of adult male Sprague-Dawley rats were used: in two control groups, electrodes were bilaterally implanted in the LH (5 rats) or in the MPC (6 rats) and self-stimulation (ICSS) was obtained separately with the right and left electrodes. In the two experimental groups the intrinsic neurons of the LH (8 rats) or of the MPC (10 rats) were destroyed unilaterally by local injection of ibotenic acid (4 micrograms in 0.5 microliter); the other side served as the sham-lesioned control. Ten days later ICSS electrodes were implanted bilaterally, one in the lesioned area, the other in the contralateral region. As in the case of the control rats, ICSS was determined separately for each electrode, first by a rate dependent test (nose-poke) then by a 'rate-free' test (shuttle-box). In the LH and MPC control rats, ICSS responses were the same with stimulation on either side. In the LH-lesioned rats, the ICSS rates measured with the nose-poke test were significantly decreased with stimulation on the lesioned side, whereas rates with stimulation of the non-lesioned LH were normal. Likewise, while shuttle responses with stimulation of the non-lesioned LH were normal, the OFF-time was increased and the ON-time was decreased with stimulation of the lesioned LH. In the MPC-lesioned rats, ICSS (nose-poke) was totally suppressed and the shuttle responses were disorganized since neither the ON- nor the OFF-times changed in response to increasing current intensities. Nose-poke responses with stimulation of the non-lesioned MPC were just about normal. These results show that in the two brain regions studied local neurons are involved in ICSS. The difference in the magnitude of the deficit observed suggests, that the neuronal circuits involved in MPC self-stimulation are poorly represented whereas in the LH many neuronal circuits involved in these mechanisms overlap.

Alterations of noradrenaline and serotonin uptake and metabolism in chronic cobalt-induced epilepsy in the rat

The high affinity uptake of noradrenaline and serotonin, and the concentrations of these monoamines and their metabolites, have been measured in the perifocal cortical area at various stages of the evolution of cobalt-induced epilepsy in the rat. Noradrenaline uptake was maximally reduced at days 8-10 after cortical cobalt application, a time corresponding to the onset of epileptic discharges; it remained diminished during the spiking activity period of the focus (days 14-20) and was back to normal values at day 40, at which time the epileptic syndrome had disappeared. Serotonin uptake was also diminished at days 8-10 but to a lesser extent than was noradrenaline uptake. In the homotopic cerebral cortex contralateral to cobalt application, noradrenaline uptake was reduced at day 10 only and to a lesser extent than in the perifocal area, whereas serotonin uptake was unaffected. Kinetic analysis of the cobalt-induced monoamine uptake alterations at day 10 revealed a diminution of the maximal velocity with no change in the Km. Noradrenaline and dihydroxyphenylethyleneglycol concentrations in the perifocal area were also maximally reduced at days 8-10 but were unaffected at day 2 and day 40 post cobalt application. A reduction of serotonin levels in the perifocal area was observed only at days 8-10 while 5-hydroxyindoleacetic acid remained unaffected throughout the time period studied. The levels of these monoamines and their metabolites were unchanged in the homotopic contralateral cortex 2-40 days after cobalt application. These results indicate that cortical cobalt application induces alterations of the biochemical indices of the density of noradrenaline-containing terminals that closely parallel the evolution of the epileptic syndrome. These data further emphasize the important role of the cortical noradrenergic system in cobalt-induced epilepsy.

Neurochemical lesion of the locus coeruleus of the rat does not suppress the sedative effect of clonidine

The locus coeruleus of male rats was destroyed bilaterally by injection of 6-hydroxydopamine. Rats injected with the vehicle and normal rats served as controls. Starting 20 days after the lesion, the locomotor activity of all rats was measured for 5 min every day. For the first 6 days, the lesioned rats were significantly less active than control rats; from the 7th to the 15th day, on the other hand, the locomotor activity of the two groups of rats was the same. From the 16th day onwards, the sedative effect of small doses of clonidine (2.5-100 micrograms/kg) was measured in lesioned and control animals. In spite of an almost total loss of noradrenaline in the cerebral cortex and hippocampus and a 33% loss of noradrenaline in the brain-stem of the lesioned rats, the sedative effect of clonidine was the same as in the control rats. This result suggests that the sedation produced by clonidine is not dependent on presynaptically located alpha 2-adrenoceptors.

Enhancement of learning four weeks after stimulation of the nucleus locus coeruleus in the rat: differential effects of dorsal noradrenergic bundle lesion and lesion of the locus coeruleus proper

In previous studies we showed that electrical stimulation of the nucleus locus coeruleus produced, four weeks later, a significant improvement in performance in acquisition of food-reinforced operant conditioning. In the two experiments reported here, we tested the role of the dorsal noradrenergic bundle and of the locus coeruleus proper in this long-term effect. Lesioning the dorsal noradrenergic bundle did not have a clear and consistent effect, whereas lesion of the nucleus coeruleus proper suppressed almost totally the beneficial effect of the stimulation. In the first experiment, the dorsal noradrenergic bundle was lesioned by local bilateral injection of 6-hydroxydopamine, 8 days before stimulation of the locus coeruleus. Four weeks after the stimulation, the rats were tested for acquisition of the operant task. Three control groups were used: not lesioned but stimulated, lesioned but not stimulated, and not lesioned/not stimulated. The locus coeruleus stimulation produced the same improvement of performance at the beginning of the acquisition, whether or not the dorsal noradrenergic bundle had been lesioned. However, a significant decrement of performance was observed in lesioned and stimulated rats during the last 40 min of the acquisition. In the second experiment, the locus coeruleus proper was destroyed by bilateral local injection of 6-hydroxydopamine and the locus coeruleus region was stimulated 15 days later. Three control groups were used, as in the first experiment. All the rats were tested 4 weeks later for acquisition of the operant task. The locus coeruleus lesion significantly attenuated the beneficial effect of the stimulation; however, the performance of the lesioned and stimulated rats was still significantly superior to that of the lesioned but not stimulated rats. These results suggest that the noradrenergic locus coeruleus system is involved in the long-term effect, but that the rostral projections passing through the dorsal bundle, in front of the lesion, are not critically involved in the observed effect.

[Is an alteration of noradrenergic afferents involved in focal epilepsies? (author's transl)]

Previous studies have indicated that noradrenergic system could be involved in various models of chemically, electrically or genetically induced epilepsy. The relationship between the development of a chronic cobalt focus in the rat and the alterations of the cortical noradrenergic system has been studied by means of biochemical analysis of the NA cortical content combined with the glyoxylic acid-induced fluorescence method and the micro-iontophoretic technique. It can be suggested that the noradrenergic system may influence the initiation, spread and disappearance of the epileptic syndrome: (1) The beginning of epileptic discharges coincides with a drop in the NA cortical content, with decrease in number of the NA-containing terminals and with a hypersensitivity of the cortical neurons to iontophoretically applied NA. (2) The termination of the epileptic syndrome coincides with an increase in density of the cortical noradrenergic innervation (sprouting) and consequently with an increase in NA cortical concentrations and a return to normal values of the NA threshold of the cortical neurons.