The risk of endoleak following stent covering of the internal iliac artery during endovascular aneurysm repair.

AIM: To investigate the risk of endoleak during endovascular aneurysm repair (EVAR) involving the distal common iliac artery (CIA) when the internal iliac artery (IIA) is covered without prior coil embolization. MATERIALS AND METHODS: Retrospective analysis of 145 (125 men, 20 women) consecutive EVAR cases. Clinical notes and radiological images were reviewed, and data collected on patient demographics, aneurysm morphology, covering of the IIA with or without embolization, presence of endoleaks, and patient symptoms relating to IIA ischaemia. RESULTS: A total of 29 IIAs (10%) were covered in a total of 25 patients. Seven IIAs (24%) were embolized before stent covering (Embolization group), and 22 IIAs (76%) were covered only without embolization (Cover group). There was no statistically significant difference in the mean size of the abdominal aortic aneurysm diameter or CIA diameter between each group. No endoleaks from IIA retrograde filling were found in either group. CONCLUSION: The results of the present study do not support the traditional view that coverage of the IIA without prior embolization carries a high risk of endoleak, with no endoleaks seen in all 22 cases. Large-scale trials are required. However, the advent of branched-stenting techniques and the emergence of their success in long-term follow-up may preclude the former.

Observer accuracy in the detection of pulmonary nodules on CT: effect of cine frame rate.

AIM: To assess the effect of cine frame rate on the accuracy of the detection of pulmonary nodules at computed tomography (CT). MATERIALS AND METHODS: CT images of 15 consecutive patients with (n = 13) or without (n = 2) pulmonary metastases were identified. Initial assessment by two thoracic radiologists provided the "actual" or reference reading. Subsequently, 10 radiologists [board certified radiologists (n = 4) or radiology residents (n = 6)] used different fixed cine frame rates for nodule detection. Within-subjects analysis of variance (ANOVA) was used to evaluate the data. RESULTS: Eighty-nine nodules were identified by the thoracic radiologists (median 8, range 0-29 per patient; median diameter 9 mm, range 4-40 mm). There was a non-statistically significant trend to reduced accuracy at higher frame rates (p=0.113) with no statistically significant difference between experienced observers and residents (p = 0.79). CONCLUSION: The accuracy of pulmonary nodule detection at higher cine frame rates is reduced, unrelated to observer experience.

Posterior reversible encephalopathy syndrome: a possible late interaction between cytotoxic agents and general anaesthesia.

A 49-year-old woman who had previously received treatment with cytotoxic drugs for metastatic gestational trophoblastic disease (GTD) presented with a witnessed tonic-clonic seizure, headache, confusion and blindness, 6 days after the uneventful administration of a general anaesthetic and 2 months after cessation of chemotherapy. Magnetic resonance imaging showed relatively symmetrical, subcortical, white matter abnormalities, predominantly affecting the occipital, posterior temporal and parietal lobes and the cerebellum. T2-dependent abnormalities and elevated regional apparent diffusion coefficient were present in a pattern typical for posterior reversible encephalopathy syndrome (PRES). The clinical and radiological manifestations were resolved completely with supportive therapy. This case of PRES may be a late complication of gemcitabine or cisplatin therapy precipitated by a general anaesthetic, or associated electrolyte or blood pressure disturbance.

Simultaneous two-photon activation of type-I photodynamic therapy agents.

The excitation and emission properties of several psoralen derivatives are compared using conventional single-photon excitation and simultaneous two-photon excitation (TPE). Two-photon excitation is effected using the output of a mode-locked titanium: sapphire laser, the near infrared output of which is used to promote nonresonant TPE directly. Specifically, the excitation spectra and excited-state properties of 8-methoxypsoralen and 4'-aminomethyl-4,5,8-trimethylpsoralen are shown to be equivalent using both modes of excitation. Further, in vitro feasibility of two-photon photodynamic therapy (PDT) is demonstrated using Salmonella typhimurium. Two-photon excitation may be beneficial in the practice of PDT because it would allow replacement of visible or UV excitation light with highly penetrating, nondamaging near infrared light and could provide a means for improving localization of therapy. Comparison of possible laser excitation sources for PDT reveals the titanium: sapphire laser to be exceptionally well suited for nonlinear excitation of PDT agents in biological systems due to its extremely short pulse width and high repetition rate that together provide efficient PDT activation and greatly reduced potential for biological damage.

Experimental assessment of O(2) interferences on laser-induced fluorescence measurements of NO in high-pressure, lean premixed flames by use of narrow-band and broadband detection.

We experimentally investigate the influence of O(2) interferences on laser-induced fluorescence measurements of NO in lean methane-fueled flames at a range of pressures for both narrow-band and broadband fluorescence detection. We identify NO excitation schemes that minimize O(2) interferences. From detection scans we obtain interference spectra for the different NO excitation schemes. We then identify optimum excitation-detection schemes for narrow-band detection measurements of NO. To simulate broadband detection experiments, we numerically apply five different filter combinations to the experimentally obtained detection scans. We develop filter-assessment parameters to judge the effectiveness of the different filtering schemes, and we establish a methodology for evaluating broadband excitation-detection strategies. From this research we identify optimum excitation-detection schemes for broadband detection measurements of NO.

Formulation of a dimensionless overlap fraction to account for spectrally distributed interactions in fluorescence studies.

An overlap term is used in fluorescence theory to account for the spectrally distributed interaction between laser radiation and molecular transitions. We present a dimensionless overlap fraction formulation. Compared with the more common dimensional overlap term [in units of inverse wave number (1/cm(-1))], this form of expression of the interaction between a laser and an absorption transition has a much more practical interpretation and simplifies the equations that describe fluorescence measurements.

Performance of Pyrromethene 580 and 597 in a commercial Nd:YAG-pumped dye-laser system.

We report the performance of two new laser dyes, Pyrromethene 580 and 597, in a 10-Hz, Nd:YAG-pumped dye-laser system. These dyes demonstrate broader and more efficient tuning curves compared with those of Rhodamine 590 and 610. Pyrromethene 580 and 597 provide peak conversion efficiencies of 38% at 552 nm and 32% at 571 nm, respectively. Moreover, these new dyes provide conversion efficiencies of 31% near 572.5 nm, a wavelength used for fluorescence studies of NO. This enhanced efficiency should improve the signal-to-noise ratio in linear fluorescence [NO] measurements.