Management of patient dose and image noise in routine pediatric CT abdominal examinations.

The aim was to propose a strategy for finding reasonable compromises between image noise and dose as a function of patient weight. Weighted CT dose index (CTDI(w)) was measured on a multidetector-row CT unit using CTDI test objects of 16, 24 and 32 cm in diameter at 80, 100, 120 and 140 kV. These test objects were then scanned in helical mode using a wide range of tube currents and voltages with a reconstructed slice thickness of 5 mm. For each set of acquisition parameter image noise was measured and the Rose model observer was used to test two strategies for proposing a reasonable compromise between dose and low-contrast detection performance: (1) the use of a unique noise level for all test object diameters, and (2) the use of a unique dose efficacy level defined as the noise reduction per unit dose. Published data were used to define four weight classes and an acquisition protocol was proposed for each class. The protocols have been applied in clinical routine for more than one year. CTDI(vol) values of 6.7, 9.4, 15.9 and 24.5 mGy were proposed for the following weight classes: 2.5-5, 5-15, 15-30 and 30-50 kg with image noise levels in the range of 10-15 HU. The proposed method allows patient dose and image noise to be controlled in such a way that dose reduction does not impair the detection of low-contrast lesions. The proposed values correspond to high- quality images and can be reduced if only high-contrast organs are assessed.

Micro-patterning of biomolecules on polymer substrates.

UV−excimer laser photoablation was used, in combination with surface blocking techniques, to pattern proteins on the surfaces of polyimide and poly(ethylene terephthalate). This technique involves physical adsorption of avidin through laser-defined openings in low-temperature laminates or adsorbed protein blocking layers. Visualization of biomolecular patterns were monitored using avidin and fluorescein-labeled biotin as a model receptor−ligand couple. Adsorbed proteins could be shown to bind to UV-laser-treated polymer surfaces up to three times higher than on commercially available polymers. UV-laser photoablation was also used for the generation of three-dimensional structure, which leads to the possibility of biomolecule patterning within polymer-based microanalytical systems. The simplicity and easy handling of the described technique facilitate its application in microdiagnostic devices.

Multi-phase postmortem CT angiography: recognizing technique-related artefacts and pitfalls.

BACKGROUND AND PURPOSE: Multi-phase postmortem CT angiography (MPMCTA) is increasingly being recognized as a valuable adjunct medicolegal tool to explore the vascular system. Adequate interpretation, however, requires knowledge about the most common technique-related artefacts. The purpose of this study was to identify and index the possible artefacts related to MPMCTA. MATERIAL AND METHODS: An experienced radiologist blinded to all clinical and forensic data retrospectively reviewed 49 MPMCTAs. Each angiographic phase, i.e. arterial, venous and dynamic, was analysed separately to identify phase-specific artefacts based on location and aspect. RESULTS: Incomplete contrast filling of the cerebral venous system was the most commonly encountered artefact, followed by contrast agent layering in the lumen of the thoracic aorta. Enhancement or so-called oedematization of the digestive system mucosa was also frequently observed. CONCLUSION: All MPMCTA artefacts observed and described here are reproducible and easily identifiable. Knowledge about these artefacts is important to avoid misinterpreting them as pathological findings.

Dual-energy CT behavior of heroin, cocaine, and typical adulterants.

PURPOSE: To investigate the dual-energy CT behavior of cocaine and heroin and of typical adulterants, and to evaluate the elemental composition of pure cocaine and heroin compared with cocaine and heroin in bodypacks. METHODS: Pure heroin and pure synthetic cocaine samples, eight different adulterants, and in each case ten different bodypacks containing cocaine or heroin, were imaged at 80, 100, 120, and 140 kVp in a dual source CT system at two different degrees of compression. Two radiologists, blinded to the samples, measured the attenuation. The dual-energy index (DEI) was calculated. We performed atomic mass spectrometry for the elemental analysis of pure cocaine, pure heroin, and heroin and cocaine in bodypacks, and 140 kVp in a dual-source CT system. RESULTS: Inter- and intra-observer agreement for attenuation measurements was good (r = 0.61-0.72; p < 0.01). The cocaine bodypacks had a positive DEI of 0.029, while the pure drugs and the heroin bodypacks had a negative DEI (-0.051 to -0.027). Levamisole was the only substance which expressed a positive DEI of 0.011, while the remaining adulterants had negative DEIs ranging between -0.015 and -0.215. Atomic mass spectrometry revealed a concentration of tin in the cocaine bodypack that was 67 times higher than in the pure synthetic cocaine sample. CONCLUSIONS: The different DEIs of bodypacks containing cocaine and heroin allow them to be distinguished with dual-energy CT. Although the material properties of pure cocaine, pure heroin, or common drug extenders do not explain the differences in DEI, tin contamination during illicit natural cocaine production may be a possible explanation.

Postmortale Darstellung der Koronararteriendurchmultiphasische Ganzkörper-CT-Angiographie : Vergleich mit Ante-mortem-Koronarangiographien

Die Diagnostik des plötzlichen Herztods durch bildgebende Techniken ist bislang unzureichend evaluiert. Als Validierungsoption für postmortale koronarangiographische Methoden steht der Sektionsbefund zur Verfügung. Sequenziell postmortal durchgeführte alternative angiographische Methoden sind denkbar. Schließlich bietet die ante mortem durchgeführte Koronarangiographie (CA) - ggf. In Verbindung mit der perkutanen transluminalen Koronarangioplastie (PTCA) - weitere Vergleichsmöglichkeiten. Neben deskriptiven sind hier auch potenziell funktionelle Aussagen zum Stenosegrad möglich.

Comparison of organ doses and image quality between CT and flat panel XperCT scans in wrist and inner ear examinations.

The aim of this study was to evaluate and compare organ doses delivered to patients in wrist and petrous bone examinations using a multislice spiral computed tomography (CT) and a C-arm cone-beam CT equipped with a flat-panel detector (XperCT). For this purpose, doses to the target organ, i.e. wrist or petrous bone, together with those to the most radiosensitive nearby organs, i.e. thyroid and eye lens, were measured and compared. Furthermore, image quality was compared for both imaging systems and different acquisition modes using a Catphan phantom. Results show that both systems guarantee adequate accuracy for diagnostic purposes for wrist and petrous bone examinations. Compared with the CT scanner, the XperCT system slightly reduces the dose to target organs and shortens the overall duration of the wrist examination. In addition, using the XperCT enables a reduction of the dose to the eye lens during head scans (skull base and ear examinations).

Micro-insurance through corporate-NGO partnerships in West Bengal : opportunities and constraints

This Practical Note examines the nascent micro-insurance sector in West Bengal, paying particular attention to the corporate- NGO partnership model for micro-insurance distribution,which has been enabled by India's unique regulatory framework. We challenge the popularconstruction of this model as a 'win - win' for all parties by analysing conflicting understandings of micro-insurance schemes and their purposes by insurance companies, NGOs, and poorvillagers. The article also considers the role of the specific political context of West Bengal inconstricting corporate- NGO micro-insurance

Clinical usefulness of FDG-PET/CT scan imaging in the management of posttransplant lymphoproliferative disease.

BACKGROUND: Posttransplant lymphoproliferative disease (PTLD) is, aside skin cancer, the most common malignancy occurring after solid organ transplant in adults. Fluorodeoxyglucose (FDG) positron emission tomography (PET) has proved useful in the management of lymphomas. METHODS: We report our experience with the use of FDG-PET inline with computed tomography (CT) scanning in the management of four transplant recipients with histologically confirmed PTLD, including three monomorphic PTLDs and one polymorphic PTLD. RESULTS: FDG-PET/CT scan at diagnosis showed increased FDG uptake in all examined PTLD lesions, and the disease was upstaged on the basis of FDG-PET/CT scan results over conventional CT scanning in one patient. At the end of treatment, PET/CT scans no longer demonstrated FDG uptake in the original PTLD lesions in all patients. Complete remission of disease persisted for at least 1 year after diagnosis in all. CONCLUSIONS: Our results strongly support that FDG-PET scanning is highly specific for diagnosis and follow-up of PTLD. The clinical relevance of including FDG-PET/CT scanning in the management of PTLD should be evaluated in a larger prospective cohort study.