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Background: Although CT urography (CTU) is widely used for the evaluation of the entire urinary tract, the most important drawback is the radiation exposure., Purpose: To evaluate the effect of a noise reduction filter (NRF) using a phantom and to quantitatively and qualitatively compare excretory phase (EP) images using a low noise index (NI) with those using a high NI and postprocessing NRF (pNRF)., Material and Methods: Each NI value was defined for a slice thickness of 5 mm, and reconstructed images with a slice thickness of 1.25 mm were assessed. Sixty patients who were at high risk of developing bladder tumors (BT) were divided into two groups according to whether their EP images were obtained using an NI of 9.88 (29 patients; group A) or an NI of 20 and pNRF (31 patients; group B). The CT dose index volume (CTDI(vol)) and the contrast-to-noise ratio (CNR) of the bladder with respect to the anterior pelvic fat were compared in both groups. Qualitative assessment of the urinary bladder for image noise, sharpness, streak artifacts, homogeneity, and the conspicuity of polypoid or sessile-shaped BTs with a short-axis diameter greater than 10 mm was performed using a 3-point scale., Results: The phantom study showed noise reduction of approximately 40% and 76% dose reduction between group A and group B. CTDI(vol) demonstrated a 73% reduction in group B (4.6 ± 1.1 mGy) compared with group A (16.9 ± 3.4 mGy). The CNR value was not significantly different (P = 0.60) between group A (16.1 ± 5.1) and group B (16.6 ± 7.6). Although group A was superior (P < 0.01) to group B with regard to image noise, other qualitative analyses did not show significant differences., Conclusion: EP images using a high NI and pNRF were quantitatively and qualitatively comparable to those using a low NI, except with regard to image noise.

Objectives: The aim of this study was to examine attenuation values in the central vein and perivenous artefacts at the subclavian vein in cervical CT angiography (CTA) when using 40 ml contrast material (CM) followed by different volumes (25 ml vs 40 ml) of saline flush (SF)., Methods: 61 patients underwent CTA between the aortic arch (AA) and distal to the circle of Willis (cW). After calculating test-bolus time to peak enhancement at the cW (Tc), scanning delay was represented as [(Tc + 4) - scan duration between AA and cW] s. 28 patients (Group A) received 40 ml of 370 mg iodine (I) ml(-1) CM followed by 25 ml of SF, and 33 patients (Group B) received the same CM followed by 40 ml of SF, both administered through the right antecubital vein. Arterial attenuation was measured at seven points in the aorto-carotid artery and at three points in the vertebrobasilar artery. Venous attenuation in the central vein was measured at four points. Mean attenuation values were analysed quantitatively. Axial and post-processing three-dimensional images were assessed qualitatively., Results: When Groups A and B were compared, there were no differences in the mean attenuation values in either the aorto-carotid artery (p=0.78) or the vertebrobasilar artery (p=0.82). Mean venous attenuation values were lower (p=0.002) in Group B than in Group A. Although the qualitative assessment of arterial images showed no differences between the two groups overall, perivenous artefacts at the subclavian vein were assessed as less prominent (p<0.01) in Group B., Conclusions: When compared with CTA followed by 25 ml of SF, CTA followed by 40 ml of SF can reduce venous attenuation values and perivenous artefacts at the subclavian vein.

An interventional-radiology computed-tomography (IVR-CT)/angio system is a combination of an angiographic unit and a CT scanner. This system allows patient's movement in and out of the two imaging units, on the same table. Since June 2003, we have applied our conventional protocol for evaluation of cerebral blood perfusion during interventional radiology (IVR) procedures. We reviewed our experience using the IVR-CT/angio system and investigated the efficacy and limitations of this technique. No complications relating to radiation exposure, contrast medium use, or IVR procedures were observed. CT perfusion was useful for detecting cerebral perfusion impairment during IVR procedures. This was helpful in deciding the postoperative management. Because patients do not need to be transported to another radiographic suite to evaluate cerebral blood perfusion, the IVR-CT/angio system is ideal for safely and simply detecting cerebral perfusion defects during IVR procedures. However, it is important to consider whether there is sufficient indication for the procedure, because radiation exposure and the amount of contrast medium use are increased if the IVR procedures become difficult.

Photodynamic therapy (PDT) is a promising therapeutic modality for treatment of solid tumors. In this study, third-generation aryl ether dendrimer porphyrins (DPs) with either 32 quaternary ammonium groups (32(+)DPZn) or 32 carboxylic groups (32(-)DPZn) were evaluated as a novel, supramolecular class of photosensitizers for PDT. DPs showed a different cell-association profile depending on the positive or negative charge on the periphery, and both DPs eventually localized in membrane-limited organelles. In contrast, protoporphyrin IX (PIX), which is a hydrophobic and relatively low molecular weight photosensitizer used as a control in this study, diffused through the cytoplasm except the nucleus. Confocal fluorescent imaging using organelle-specific dyes indicated that PIX induced severe photodamage to disrupt membranes and intracellular organelles, including the plasma membrane, mitochondrion, and lysosome. On the other hand, cells treated with DPs kept the characteristic fluorescent pattern of such organelles even after photoirradiation. However, notably 32(+)DPZn achieved remarkably higher (1)O(2)-induced cytotoxicity against LLC cells than PIX. Furthermore, both dendrimer porphyrins had far lower dark toxicity as compared with PIX, demonstrating their highly selective photosensitizing effect in combination with a reduced systemic toxicity.

Carboxylate and ammonium functionalities-32 of each-facilitate electrostatic interaction between oppositely charged dendrimer electrolytes and porphyrin cores, which leads in protic media to a supramolecular, fluorescence-active aggregate of two chromophores that communicate and have a predictable topology (see drawing on the right; A=acceptor, D=donor). In contrast to the complexation of linear polyelectrolytes, the contact area for the two dendrimer molecules is very limited, just as one would expect for an assembly of spherical molecules., (© 1998 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.)