Digital beam attenuator technique for compensated chest radiography

The feasibility of producing patient-specific beam attenuators for chest radiography has been investigated using an anthropomorphic phantom and a human volunteer. A low-dose test exposure is digitized, processed, and used to print a small cerium filter, which is placed in the x-ray beam near the collimator. The final radiograph is recorded on film. The technique results in relatively uniform film exposure, so that structures in all regions of the chest are simultaneously displayed with optimal film contrast. The equalized exposure improves image quality in the normally underpenetrated regions and reduces the role of cross-scatter from the lungs. The image is analogous to optical or computer-processed unsharp masking techniques, but the processing is accomplished in the x-ray beam and results in an improved exposure distribution, giving advantages that cannot be achieved with image processing techniques alone.     

Results of cystectomy with and without preoperative radiotherapy in carcinoma of the urinary bladder

During a period of 13 years, 84 patients underwent total cystectomy for transitional cell carcinoma of the bladder. The corrected 5-year survival rate was 58%. The operative mortality was 5 patients (6%). The 5-year survival rate of 42 patients who were treated by surgery alone was 53%, whereas that of 42 patients who received preoperative radiation of 30-40 Gy was 65%. The prognoses of the patients were dependent on the histological differentiation and the extent of the primary tumour within each treatment group.     

Liver metastases: detection by phase-contrast MR imaging

Forty patients with biopsy-proved metastatic liver cancers were studied by magnetic resonance (MR) imaging using one or more conventional (in-phase) pulse sequences and a corresponding phase-contrast (opposed-phase) pulse sequence. Pulse-sequence performance was quantitated by measuring signal-difference-to-noise (SD/N) ratios between cancerous tissue and liver. The SD/N performance of T2-weighted spin-echo (SE) pulse sequences improved when used with the phase-contrast technique. SE 2,000/30 opposed-phase images showed improved (P less than .001) SD/N in 72% of patients over in-phase images. The SD/N of T1-weighted SE or inversion recovery pulse sequences deteriorated when used with the phase-contrast technique. Changes in measured SD/N correlated well with image appearance and actual lesion detectability in individual cases. Phase-contrast imaging should be employed routinely when T2-weighted SE pulse sequences are relied on to detect liver cancer.     

Osteosarcoma: use of MR imaging and MR spectroscopy in clinical decision making

Magnetic resonance (MR) imaging was performed on 14 patients with histologically proved osteosarcoma (mean age, 14.4 years). There was excellent correlation of intramedullary tumor extent as determined with MR imaging and pathologic examination (r = 99%). This was facilitated by the presence of a chemical shift artifact at the tumor-marrow interface on the T1-weighted images. The correlation between CT and pathologic findings was not as good (r = 84%). In a single patient, however, a 10-cm length of sclerotic bone was incorrectly interpreted as being tumor. If this case is excluded, the correlation between CT and pathologic findings improves significantly (r = 96%). T2-weighted images were optimal in demonstrating soft-tissue bulk and breach of the epiphysis or cortex. Vascular involvement was also readily defined. The T2 value of the tumor soft-tissue component decreased in patients who were deemed to have responded well to therapy. Two patients with very high T2 values after chemotherapy developed wide-spread metastatic disease and died. Phosphorus-31 MR spectroscopy of five patients with osteosarcoma showed elevated levels of phosphomonoesters (PMEs), inorganic phosphate (Pi), and phosphodiesters (PDEs). PME and PDE peak areas decreased in three patients after chemotherapy, while Pi peak areas increased.     

A modification of the Hammett equation for predicting ionisation constants of p-vinyl phenols

Currently there are several compounds used as drugs or studied as new chemical entities, which have an electron withdrawing group connected to a vinylic double bond in a phenolic or catecholic core structure. These compounds share a common feature – current computational methods utilizing the Hammett type equation for the prediction of ionisation constants fail to give accurate prediction of pK_a's for compounds containing the vinylic moiety. The hypothesis was that the effect of electron-withdrawing substituents on the pK_a of p-vinyl phenols is due to the delocalized electronic structure of these compounds. Thus, this effect should be additive for multiple substituents attached to the vinylic double bond and quantifiable by LFER-based methods. The aim of this study was to produce an improved equation with a reduced tendency to underestimate the effect of the double bond on the ionisation of the phenolic hydroxyl. To this end a set of 19 para-substituted vinyl phenols was used. The ionisation constants were measured potentiometrically, and a training set of 10 compounds was selected to build a regression model (r² = 0.987 and S.E. = 0.09). The average error with an external test set of six compounds was 0.19 for our model and 1.27 for the ACD-labs 7.0. Thus, we have been able to significantly improve the existing model for prediction of the ionisation constants of substituted p-vinyl phenols.     

Intravesical epirubicin with and without verapamil for the prophylaxis of superficial bladder tumours

Seventy-five patients with recurrent bladder carcinoma were randomized after electroresection to receive either epirubicin (E) or epirubicin + verapamil (E + V) instillation of the bladder at regular intervals for 2 years. Samples of the bladder wall, tumour tissue and peripheral blood were taken from 20 patients. The average follow-up period was 21 months. Fifty per cent of the patients in the E group and 37% in the E + V group developed recurrent tumours. Recurrence rates (RR) were 6.3 and 4.7, respectively. Before the instillation therapy the RR was 16.0. There was a highly significant reduction of RR during the instillation therapies; in group E p less than 0.005 and in group E + V p less than 0.001. The difference between the treatment groups was not statistically significant. Verapamil increased epirubicin concentrations in both the bladder wall and the tumour tissue, but did not affect concentrations in the peripheral blood. Side effects were few and did not lead to discontinuation of treatment.     

Comparison of an immortalized human corneal epithelial cell line and rabbit corneal epithelial cell culture in cytotoxicity testing.

The cytotoxicity of benzalkonium chloride (BAC) and disodium edetate (EDTA) was evaluated in vitro in rabbit corneal epithelial primary cells and in the immortalized human corneal epithelial cell line SV40. Cell injury was assessed by lactate dehydrogenase (LDH) leakage and by reduction of the tetrazolium salt WST-1 to formazan by mitochondrial metabolic activity. Cell cultures were exposed to test compounds both in serum-free and in serum-containing medium. Although WST-1 and LDH tests measured different physiological endpoints, they yielded comparable results. However, the LDH test seemed less reliable due to great variation. The use of serum was found to result in lower toxicity of the compounds in both tests. The rabbit primary cell culture and the human corneal cell line were quite similar in their responses to BAC and EDTA. The human cell line is a promising in vitro alternative in oculotoxicity testing.     

Superparamagnetic iron oxide-enhanced MR imaging: pulse sequence optimization for detection of liver cancer

The effects of magnetic resonance (MR) pulse sequences and timing parameters on tumor-liver contrast were studied in an animal model of metastatic liver cancer. Six spin-echo (SE), three inversion-recovery (IR), and four gradient-echo (GRE) sequences were evaluated at 0.6 T before and after injection of super-paramagnetic iron oxide. GRE techniques, irrespective of echo time and flip angle, showed the greatest change in signal intensity (enhancement) of the liver after administration of iron oxide. Single-acquisition GRE sequences (16 seconds) matched the contrast-to-noise ratio (C/N) performance of the most effective 6.4-minute SE sequences. Multiexcitation GRE sequences showed tumor-liver C/Ns per unit time that were significantly (P less than .05) higher than those achieved with SE and IR sequences. GRE sequences, which recruit intravoxel dephasing as an additional source of transverse relaxation enhancement (T2*), show a higher C/N per unit time and in this respect seem superior to SE and IR sequences for MR imaging with superparamagnetic iron oxide.     

Strict versus moderate glucose control after resuscitation from ventricular fibrillation

OBJECTIVE: Elevated blood glucose is associated with poor outcome in patients resuscitated from out-of-hospital cardiac arrest (OHCA). Our aim was to determine whether strict glucose control with intensive insulin treatment improves outcome of OHCA patients. DESIGN: A randomized, controlled trial. SETTING: Two university hospital intensive care units. PATIENTS: Ninety patients resuscitated from OHCA with ventricular fibrillation detected as the initial rhythm were treated with therapeutic hypothermia. INTERVENTIONS: Patients were randomized into two treatment groups: a strict glucose control group (SGC group), with a blood glucose target of 4-6 mmol/l, or a moderate glucose control group (MGC group), with a blood glucose target of 6-8 mmol/l. Both groups were treated with insulin infusion for 48 h, because a control group with no treatment was considered unethical. MEASUREMENTS AND RESULTS: Baseline data were similar in both groups. In the SGC group 71% of the glucose measurements were within the target range compared with 41% in the MGC group. Median glucose was 5.0 mmol/l in the SGC group and 6.4 mmol/l in the MGC group. The occurrence of moderate hypoglycemic episodes was 18% in the SGC group and 2% in the MGC group (p = 0.008). No episodes of severe hypoglycemia occurred. Mortality by day 30 was 33% in the SGC group and 35% in the MGC group (p = 0.846); the difference was 2% (95% CI -18% to +22%). CONCLUSIONS: We found no additional survival benefit from strict glucose control compared with moderate glucose control with a target between 6 and 8 mmol/l in OHCA patients.