Design techniques and analysis of high-resolution neural recording systems targeting epilepsy focus localization

The design of a high-density neural recording system targeting epilepsy monitoring is presented. Circuit challenges and techniques are discussed to optimize the amplifier topology and the included OTA. A new platform supporting active recording devices targeting wireless and high-resolution focus localization in epilepsy diagnosis is also proposed. The post-layout simulation results of an amplifier dedicated to this application are presented. The amplifier is designed in a UMC 0.18µm CMOS technology, has an NEF of 2.19 and occupies a silicon area of 0.038 mm(2), while consuming 5.8 µW from a 1.8-V supply.

Evaluation of magnetic resonance colonography at 3.0 Tesla regarding diagnostic accuracy and image quality

OBJECTIVES: To assess magnetic resonance (MR)-colonography (MRC) for detection of colorectal lesions using two different T1w three-dimensional (3D)-gradient-recalled echo (GRE)-sequences and integrated parallel data acquisition (iPAT) at a 3.0 Tesla MR-unit. MATERIALS AND METHODS: In this prospective study, 34 symptomatic patients underwent dark lumen MRC at a 3.0 Tesla unit before conventional colonoscopy (CC). After colon distension with tap water, 2 high-resolution T1w 3D-GRE [3-dimensional fast low angle shot (3D-FLASH), iPAT factor 2 and 3D-volumetric interpolated breathhold examination (VIBE), iPAT 3] sequences were acquired without and after bolus injection of gadolinium. Prospective evaluation of MRC was performed. Image quality of the different sequences was assessed qualitatively and quantitatively. The findings of the same day CC served as standard of reference. RESULTS: MRC identified all polyps >5 mm (16 of 16) in size and all carcinomas (4 of 4) correctly. Fifty percent of the small polyps Diagnostic quality was excellent in 94% (384 of 408 colonic segments) using the 3D-FLASH and in 92% (376 of 408) for the VIBE. The 3D-FLASH sequence showed a 3-fold increase in signal-to-noise ratio (8 +/- 3.3 standard deviation (SD) in lesions without contrast enhancement (CE); 24.3 +/- 7.8 SD after CE). For the 3D-VIBE sequence, signal-to-noise ratio doubled in the detected lesions (147 +/- 54 SD without and 292 +/- 168 SD after CE). Although image quality was ranked lower in the VIBE, the image quality score of both sequences showed no statistical significant difference (chi > 0.6). CONCLUSIONS: MRC using 3D-GRE-sequences and iPAT is feasible at 3.0 T-systems. The high-resolution 3D-FLASH was slightly preferred over the 3D-VIBE because of better image quality, although both used sequences showed no statistical significant difference.

Heparin-induced thrombocytopenia: some working hypotheses on pathogenesis, diagnostic strategies and treatment

PURPOSE OF REVIEW: The present contribution will illustrate some evolving concepts on the pathogenesis and clinical management of heparin-induced thrombocytopenia (HIT) and describe how we approach patients with suspected HIT at our institution. RECENT FINDINGS: HIT is caused by an autoimmune reaction leading to the formation of antibodies directed against platelet factor 4. Conditions favoring the development of anti-platelet factor 4/heparin antibodies differ from those required for the formation of macromolecular ternary complexes (HIT antibody/platelet factor 4/heparin), which are able to activate platelets and induce clinical HIT. HIT can be diagnosed by combining its pretest probability with the quantitative result of rapid HIT-antibody assays. Treatment of acute HIT requires inhibition of in-vivo thrombin generation by means of alternative nonheparin anticoagulant drugs, whose effective dosage appears to be significantly lower than the official recommendations. As HIT antibodies are transient, HIT patients can be re-exposed to heparin, provided that previous heparin treatment is remote and that anti-platelet factor 4/heparin antibodies are undetectable. SUMMARY: In recent years, there has been a continuing elucidation of pathogenic and clinically relevant issues, which are intellectually rewarding to follow and should enable us to offer a steadily improving treatment to the HIT patients we are in charge of.

Carcinoma ex pleomorphic adenoma: diagnostic difficulty and outcome

OBJECTIVE: To analyze a series of carcinoma ex pleomorphic adenoma (CXPA) and to assess the diagnostic difficulties. STUDY DESIGN: The clinical presentation of 24 CXPAs was compared with 300 pleomorphic adenomas (PAs). Furthermore, pathohistological findings and follow-up results of CXPAs were evaluated. RESULTS: Eight of 24 (33%) CXPAs versus 41 of 300 (14%) PAs were localized in the deep lobe (P < 0.05). Forty-two percent of CXPAs versus 6 percent of PAs, respectively, were greater than 4 cm (P < 0.05). The sensitivity in detecting CXPA by fine-needle aspiration cytology (FNAC) was 47 percent. The tumor was known to be malignant preoperatively in 10 (42%) patients. Six of 24 (25%) patients with CXPA developed a tumor recurrence. The overall 5-year survival rate of CXPA was 76 percent. CONCLUSION: CXPAs are difficult to identify preoperatively. FNAC has a low accuracy and sensitivity. CXPAs versus PAs are significantly more frequently localized in the deep lobe and are significantly greater in size.

Pineal parenchymal tumor of intermediate differentiation: diagnostic pitfalls and discussion of treatment options of a rare tumor entity

Tumors of the pineal region are uncommon, comprising approximately 0.4-1% of all intracranial tumors in adults in European and American series. Histopathologically, they are a very heterogeneous group of tumors. Of genuine pineal tumors, pineal parenchymal tumors of intermediate differentiation (PPTIDs) are the least frequently found type. In this paper, we report on the case of a patient with an unexpected and difficult-to-diagnose PPTID. A 2.2 x 2.2-cm midline mass within the posterior part of the third ventricle with consecutive obstructive hydrocephalus was found in a 44-year-old man presenting with diplopia and gait disturbances. There was no clear connection of the tumor to the pineal gland. Differential diagnosis included all intraventricular and midline tumors, therefore a biopsy was taken. Preliminary histopathological diagnosis was germinoma or primitive neuroectodermal tumor, and the tissue sample was reexamined by a referential neuropathological institute. Final diagnosis was PPTID. The tumor was then resected through a transventricular/transchoroidal approach. Histopathological examination of tumor specimen confirmed the diagnosis of a PPTID. Postoperatively, the patient received gamma-knife radiosurgery. At 1-year follow-up, there are no signs of tumor regrowth. Diagnosis of pineal parenchymal tumors in general and PPTIDs in particular can be troublesome. Their histopathological features are still being defined, as is the biological behavior of the different tumor entities. Thus, treatment options including surgery, radiation therapy, and chemotherapy remain controversial. We recommend surgical removal of PPTID, preferably in toto whenever the size of the tumor permits that kind of excision.

Experimental characterization of cement–bentonite interaction using core infiltration techniques and 4D computed tomography

Deep geological storage of radioactive waste foresees cementitious materials as reinforcement of tunnels and as backfill. Bentonite is proposed to enclose spent fuel drums, and as drift seals. The emplacement of cementitious material next to clay material generates an enormous chemical gradient in pore water composition that drives diffusive solute transport. Laboratory studies and reactive transport modeling predict significant mineral alteration at and near interfaces, mainly resulting in a decrease of porosity in bentonite. The goal of this project is to characterize and quantify the cement/bentonite skin effects spatially and temporally in laboratory experiments. A newly developed mobile X-ray transparent core infiltration device was used, which allows performing X-ray computed tomography (CT) periodically without interrupting a running experiment. A pre-saturated cylindrical MX-80 bentonite sample (1920 kg/m3 average wet density) is subjected to a confining pressure as a constant total pressure boundary condition. The infiltration of a hyperalkaline (pH 13.4), artificial OPC (ordinary Portland cement) pore water into the bentonite plug alters the mineral assemblage over time as an advancing reaction front. The related changes in X-ray attenuation values are related to changes in phase densities, porosity and local bulk density and are tracked over time periodically by non-destructive CT scans.

Declining transition rates to psychosis: The role of diagnostic spectra and symptom overlaps in individuals with attenuated psychosis syndrome

Transition to psychosis in at-risk individuals has markedly declined in recent years. So far it has never been discussed in detail that with the growing awareness and increasing availability of early psychosis services, a much broader diagnostic spectrum is now being seen in these services. Subsequently, subjects present with symptoms that meet psychosis risk on a purely psychometric basis but may be the phenotypical expression of another underlying mental disorder. Here we critically review four groups of symptoms and clinical features that are frequently reported by individuals with suspected psychosis risk states, yet share strong commonalities with other mental disorders and conditions: isolated hallucinations; unusual bodily perceptions, hypochondriatic fears and cenesthetic psychotic symptoms; depersonalization; obsessive–compulsive, overvalued and delusional ideas. Of the 616 individuals so far assessed in the Bruderholz Early Psychosis Outpatient Service for Adolescents and Young Adults, 218 (30.5%) met ultra-high risk (UHR) criteria, 188 (86.2%) of whom suffered from one of the four above-mentioned symptom groups. The appraisal of the diagnostic spectra and their overlapping symptoms constitute a tremendous challenge in the clinical assessment of each referred individual. The final conclusion of a clinical assessment should not end with the mere assignment – or non-assignment – to a presumed psychosis risk group, but needs to take into account the ‘Gestalt’ of these particular symptoms and clinical features and thus be based on many more facets than solely a psychometric or nosological approach. Such an approach may break down the heterogeneous psychosis risk group and enable appropriate treatment regimes.

Quantification of nanoparticles at the single-cell level: an overview about state-of-the-art techniques and their limitations.

With the increasing production and use of engineered nanoparticles it is crucial that their interaction with biological systems is understood. Due to the small size of nanoparticles, their identification and localization within single cells is extremely challenging. Therefore, various cutting-edge techniques are required to detect and to quantify metals, metal oxides, magnetic, fluorescent, as well as electron-dense nanoparticles. Several techniques will be discussed in detail, such as inductively coupled plasma atomic emission spectroscopy, flow cytometry, laser scanning microscopy combined with digital image restoration, as well as quantitative analysis by means of stereology on transmission electron microscopy images. An overview will be given regarding the advantages of those visualization/quantification systems, including a thorough discussion about limitations and pitfalls.

Diagnostic Performance and Additional Value of Elastosonography in Focal Breast Lesions: Statistical Correlation between Size-Dependant Strain Index Measurements, Multimodality-BI-RADS Score, and Histopathology in a Clinical Routine Setting

Objective. To evaluate the diagnostic benefit of real-time elastography (RTE) in clinical routine. Strain indices (SI) for benign and malignant tumors were assessed. Methods. 100 patients with 110 focal breast lesions were retrieved. Patients had mammography (MG), ultrasound (US), and, if necessary, MRI. RTE was conducted after ultrasound. Lesions were assessed with BI-RADS for mammography and ultrasound. Diagnosis was established with histology or follow-up. Results. SI for BI-RADS 2 was 1.71 ± 0.86. Higher SI (2.21 ± 1.96) was observed for BI-RADS 3 lesions. SI of BI-RADS 4 and 5 lesions were significantly higher (16.92 ± 20.89) and (19.54 ± 10.41). 31 malignant tumors exhibited an average SI of 16.13 ± 14.67; SI of benign lesions was 5.29 ± 11.87 (P value <0.0001). ROC analysis threshold was >3.8 for malignant disease. Sensitivity of sonography was 90.3% (specificity 78.5%). RTE showed a sensitivity of 87.1% (specificity 79.7%). Accuracy of all modalities combined was 96.8%. In BI-RADS 3 lesions RTE was able to detect all malignant lesions (sensitivity 100%, specificity 92.9%, and accuracy 93.9%). Conclusions. RTE increased sensitivity and specificity for breast cancer detection when used in combination with ultrasound.

Diagnostic confidence and image quality of CT pulmonary angiography at 100 kVp in overweight and obese patients.

AIM To compare image quality and diagnostic confidence of 100 kVp CT pulmonary angiography (CTPA) in patients with body weights (BWs) below and above 100kg. MATERIALS AND METHODS The present retrospective study comprised 216 patients (BWs of 75-99kg, 114 patients; 100-125kg, 88 patients; >125kg, 14 patients), who received 100 kVp CTPA to exclude pulmonary embolism. The attenuation was measured and the contrast-to-noise ratio (CNR) was calculated in the pulmonary trunk. Size-specific dose estimates (SSDEs) were evaluated. Three blinded radiologists rated subjective image quality and diagnostic confidence. Results between the BW groups and between three body mass index (BMI) groups (BMI <25kg/m(2), BMI = 25-29.9kg/m(2), and BMI ≥30kg/m(2), i.e., normal weight, overweight, and obese patients) were compared using the Kruskal-Wallis test. RESULTS Vessel attenuation was higher and SDDE was lower in the 75-99kg group than at higher BWs (p-values between <0.001 and 0.03), with no difference between the 100-125 and >125kg groups (p = 0.892 and 1). Subjective image quality and diagnostic confidence were not different among the BW groups (p = 0.225 and 1). CNR was lower (p < 0.006) in obese patients than in normal weight or overweight subjects. Diagnostic confidence was not different in the BMI groups (p = 0.105). CONCLUSION CTPA at 100 kVp tube voltage can be used in patients weighing up to 125kg with no significant deterioration of subjective image quality and confidence. The applicability of 100 kVp in the 125-150kg BW range needs further testing in larger collectives.