Mechanistic and thermodynamic studies of oxyanion sorption by various synthetic Mg/Al layered double hydroxides.

In this study, Mg/Al layered double hydroxides (LDHs) were investigated for their potential in scavenging several harmful oxyanions from aqueous solution. LDHs could effectively remove oxyanions and the selectivity of LDHs was governed by both the valencies and the ionic radii of the oxyanions. LDHs prepared by the fast coprecipitation with hydrothermal treatment (FCHT) method and sol-gel with solvothermal treatment method (SGST) had higher oxyanion (i.e. arsenate) removal efficiency than those prepared by the conventional routes, owing to their lower carbonate content, higher surface area, larger pore volume, larger pore size, and nanocrystalline characteristic. The sorption of arsenate by FCHT-LDH was found primarily due to anion exchange mechanism and might involve a secondary sorption mechanism. The negative DeltaG degrees for arsenate sorption confirmed the spontaneity of the removal process. The positive values of DeltaH degrees and DeltaS degrees provided further evidence of the anion exchange process in the removal mechanism.

Detection of lung cancer on the chest radiograph: impact of previous films, clinical information, double reading, and dual reading.

To study the impact of clinical information, previous chest radiographs, double reading (one pair of observers read the films independently) and dual reading (one pair of observers read the films simultaneously) on the sensitivity, specificity and odds ratios of observers in the detection of early lung cancer on the chest radiograph. The study was performed in 3 sessions. In the first session, 14 observers reviewed the chest radiographs of 100 cases (30 with early lung cancer, 35 with no abnormalities, 35 with other cardiopulmonary diseases). Sensitivity, specificity, odds ratios and the effect of double reading were calculated. After 4 months, a second session was held in which 7 observers reviewed all cases with the provision of all information. The other 7 observers reviewed all cases without information again. To determine the effect of dual reading, in the third session, 4 pairs of observers reviewed all cases in which they disagreed in the first independent reading session. The effects of information, double reading and dual reading on sensitivity, specificity and odds ratio were calculated. The sensitivity of the observers in the first session ranged from 0.20 to 0.60 and the specificity from 0.87 to 0.95. In the second session, these parameters changed only slightly, independent from the availability of clinical information and previous films. With double reading the sensitivity increased and specificity decreased. With dual reading sensitivity increased and specificity remained unchanged. The odds ratios were improved with double reading by 4% and with the dual reading by 14%. Additional clinical information, previous chest radiographs, double reading and dual reading have little impact on the detection of early lung cancer on the chest radiograph.

Agenesis of the right upper lobe.

Bronchoscopy and bronchography revealed a very rare abnormality in the embryonal anatomy of the right bronchial tree in a 54-year-old woman with cough. There was a proximal migration of the apical branch of the right upper bronchus toward the trachea and a distal migration of the two other branches toward the middle lobe bronchus. The proximal migration was accompanied by a narrowing of the trachea. This case is considered an extremely rare embryonal variation in the development of the right bronchial tree.

Late complications of percutaneous dilatational tracheotomy.

STUDY OBJECTIVE: To assess the late complications of percutaneous dilatational tracheotomy, particularly the incidence of tracheal stenosis and voice changes. DESIGN: Prospective descriptive clinical study. SETTING: Teaching hospital, the Netherlands. PATIENTS: Eighty consecutive patients who were successfully decannulated after percutaneous tracheotomy. MEASUREMENTS AND RESULTS: Fourteen patients died after decannulation, of tracheotomy-unrelated causes. Sixty-six patients were followed up 3 to 39 months after decannulation (mean, 16 months). Fifty-four patients underwent tomography of the trachea. In 14 patients (26%), there was tracheal narrowing of more than 10%. Data analysis showed that these stenoses were operator dependent (p = 0.03). Voice changes, found in 13 (21%) of 61 patients, were major in 1 and minor in 12. Scars were generally cosmetically acceptable. Retraction of the scar, seen in 13 (19%) of 66 patients, was related to the duration of cannulation (p = 0.002). A persistent tracheocutaneous fistula was present in two patients. CONCLUSIONS: The incidence of tracheal stenosis after percutaneous dilatational tracheotomy is low compared with conventional tracheotomy. Experience with the technique is important to avoid late complications.

Miss rate of lung cancer on the chest radiograph in clinical practice.

STUDY OBJECTIVES: To investigate the miss rate of non-small cell lung cancer (NSCLC) on the chest radiograph. In addition, the characteristics, the delay in diagnosis, and the change in prognosis of the missed lesions were studied. DESIGN: A retrospective study on patients with histopathologically proven NSCLC during the years 1992 through 1995 in a large community hospital. SETTING: Department of Radiology, Atrium Medical Center, Heerlen, the Netherlands. PATIENTS: During the study period, 495 patients presented with NSCLC. Of these patients, the complete set of chest radiographs was available for analysis in 396; there were 300 men and 96 women, with a mean age of 68 years. MAIN OUTCOME MEASURES: The main outcome measures included the miss rate of NSCLC presenting as nodular lesions. Location, diameter, superposing structures, and delay of missed and detected lesions and the change of prognosis as a consequence of the delay in diagnosis were other measures. RESULTS: In 49 (19%) of 259 patients with NSCLC presenting as a nodular lesion on the chest radiographs, the lesions were missed. The miss rate was not dependent on location. Superposing structures were more often present in the group of missed lesions than in the group of detected lesions, respectively, 71% and 2%. The median diameter of the missed lesions was 16 mm and of the detected lesions it was 40 mm. The median delay of the missed lesions was 472 days and of the detected lesions it was 29 days. Twenty-two (45%) patients with missed lesions remained in stage T1, 6 (12%) remained in stage T2 and in 21 patients (43%), the tumor stage changed from stage T1 into T2. CONCLUSION: The miss rate of 19% in our study is low compared with the rate in the literature but it has a definitive impact on prognosis.

Primary large cell neuroendocrine carcinoma of the presacral region.

A 7 cm diameter presacral tumour, not related to the intrapelvic organs, was found in a 51 year old woman. The needle biopsy showed a poorly differentiated large cell carcinoma. The patient died of urosepsis after chemotherapy. Postmortem examination revealed no other primary or metastatic tumour. Histological examination of the presacral tumour showed a large cell carcinoma with a trabecular pattern and strong immunoreactivity for neuroendocrine markers. The tumour was finally classified as a primary large cell neuroendocrine carcinoma of the presacral region.

Interobserver variability and accuracy of computed tomographic assessment of nodal status in lung cancer.

To assess the interobserver variability of computed tomography in determining nodal status in non-small cell lung carcinoma, four experienced radiologists reviewed the computed tomographic scans of 147 patients. Interobserver variability was calculated using the kappa statistic. In addition, the accuracy of CT assessment of the nodal status by the four observers was measured by comparing their findings with thorough mediastinal exploration at both mediastinoscopy (n = 35) and thoracotomy (n = 112). Interobserver variability was large between the four radiologists regarding nodal status on a per-patient basis (kappa = 0.38). Sensitivity of computed tomography for the observers on a per-patient basis ranged from 40% to 69% with a 1.0-cm criterion and from 28% to 56% with a 1.5-cm criterion. From the large interobserver variability and the low sensitivities in this study it can be concluded that a negative result of computed tomography regarding mediastinal lymph nodes does not eliminate the need for mediastinoscopy or exploration of the mediastinum at the time of operation in patients with non-small cell lung cancer.

Computed tomographic staging of esophageal carcinoma: a study on interobserver variation and correlation with pathological findings.

Despite numerous reports on the efficacy of CT in the staging of esophageal carcinoma, no data are available on the reproducibility of the procedure. Three experienced radiologists independently reviewed the CT scans of 35 patients retrospectively. Calculation of interobserver variation was performed using the kappa statistic. The CT findings of each observer were subsequently correlated with the surgical and pathological findings of 17 patients. There was a large interobserver variation concerning involvement of the aorta, pulmonary vessels, vertebral column, stomach and lymph nodes, ranging from poor to excellent agreement. Agreement between observers on extension of the disease to the tracheobronchial tree, pericardium and liver was good or excellent. Agreement between the CT findings of all observers and the surgical findings for invasive growth was poor. CT pathological correlation of the three observers showed sensitivities ranging from 50 to 57%, specificities ranging from 50 to 60% and accuracies ranging from 46 to 71%. It can be concluded from this study that patients with positive CT findings for involvement of the tracheobronchial tree, the pericardium and the liver should be considered unresectable for cure. Negative findings, however, should be interpreted with caution, because involvement of other structures may still be present. Despite optimistic reports on the efficacy of CT in the pretherapy staging of esophageal neoplasms, this modality has its limitations.

Randomized clinical trial on the use of antispasmodic drugs in barium enema: impact on radiological practice.

PURPOSE: To assess the willingness of radiologists to change their practice when the results of a randomized clinical trial (RCT) on the use of antispasmodic drugs in barium enema are presented. MATERIALS AND METHODS: During the years 1994 and 1995 two postal questionnaires were sent to 481 practicing radiologists who were all members of the Netherlands Society of Radiology. In the first questionnaire the respondents were asked to give the characteristics of their practices in performing daily barium enema. The data from this questionnaire was used as a reference. The second questionnaire was sent to the respondents together with an abstract on the randomized clinical trial supporting the use of antispasmodic drugs in barium enema. We also indicated a preference for Buscopan over Glucagon as the antispasmodic drug. The willingness to change prescription habits was measured by comparing the data of the two questionnaires. RESULTS: Of 481 practicing radiologists, 312 responded to the first questionnaire and gave information of their prescription habits (response rate 64%). These 312 responders were sent an abstract of the RCT and were asked to fill out a second questionnaire to determine their willingness to change their practice. Two hundred and sixty-seven radiologists responded (response rate 86%). A significant number of 119 (51%) were willing to increase the use of antispasmodic drugs. A significant number of 128 (55%) chose to increase the use of Buscopan, while a significant number of 81 (32%) were willing to decrease the use of Glucagon. CONCLUSION: Direct exposure to the results of an RCT recommending the use of antispasmodic drugs in barium enema, especially Buscopan, is likely to increase its use by practicing radiologists.

Detection of lung cancer on the chest radiograph: a study on observer performance.

STUDY OBJECTIVES: to study the validity and observers consistency in the detection of lung cancer on the chest radiograph. MATERIALS AND METHODS: the chest radiographs of 100 clinical cases were interpreted by 14 observers. The radiographs were obtained from 30 patients with initially missed but histopathologically proven non-small cell lung cancer (NSCLC), 35 patients with other cardiopulmonary diseases and 35 patients with no abnormalities. The observers consisted of ten experienced radiologists, two-experienced chest physicians and two residents in radiology. All observers were unaware of the study design. The validity and observer consistency was determined for each observer. RESULTS: the mean sensitivity and specificity of the ten radiologists were 0.36 and 0.90. For the two chest physicians, the mean sensitivity and specificity were 0.29 and 0.96. For the two residents in radiology, mean sensitivity and specificity were 0.25 and 0.94. The mean interobserver kappa and mean intraobserver kappa for the radiologists were 0.38 and 0.54. For the two chest physicians, the mean interobserver kappa was 0.43, while the intraobserver kappa was 0.59. For the two residents in radiology, mean interobserver kappa was 0.35 and the intraobserver kappa was 0.42. There was no significant relation between the consistency parameters and validity parameters. The interobserver and intraobserver kappa values showed good correlation. CONCLUSION: the validity of the chest radiograph and observers consistency in the detection of nodular lung cancer varies widely. The level of experience is likely to influence the diagnostic performance.

Right heart failure: diagnosis via ultrasonography of the inferior vena cava and hepatic veins.

PURPOSE: To determine the efficiency of ultrasonographic measurements of the inferior vena cava (IVC) and hepatic vein (HV) in the detection of elevated systemic venous pressure due to right heart failure. MATERIAL AND METHODS: Measurements of the Collapsibility Index (CI) of the Inferior vena cava (IVC) and hepatic vein (HV) was obtained from 95 persons without right failure. The CI values of 32 patients with clinically documented right heart failure and the data of a subgroup of 24 patients who received therapy, were statistically compared to those of the group without right heart failure. RESULTS: There were statistical significant differences between the CI of the persons without and the patients with right heart failure and between the patients before and after therapy (two-sample T-test: p < 0.05). The position of the ROC curve indicates that measurements of the CI of the IVC and HV enables to distinguish very well patients with right heart failure from those without right heart failure. If the cut-off CI value between normal and abnormal of the IVC was set at 0.22, the sensitivity was 78% and the specificity 98%. When the cut-off value of the CI of the HV was set at 0.25 the sensitivity was 78% and the specificity 96%. There was good interobserver agreement with regard to the CI values of the IVC (correlation coefficient 0.65), but poor interobserver agreement with regard to the CI values of the HV (correlation coefficient 0.35). CONCLUSION: Ultrasonographic measurement of the CI of the inferior vena cava is particularly useful to exclude systemic venous congestion in right heart failure and to monitor the effect of therapy.

[The limited detection of lung cancer on chest X-rays]. / De beperkte detectie van longkanker op röntgenfoto's van de thorax.

In a study of everyday clinical practice, the diagnosis 'lung cancer' was not made on the chest X-ray initially in one-fifth of the cases, even though in retrospect the lesions had been visible on the chest X-ray. In nearly half of these cases, the diagnosis had been missed at least twice on succeeding X-rays of the patient in question. Most often, superimposed structures are responsible for having missed lesions on the chest X-ray; this was the case in 71% of the patients in whom a lesion was missed. The intra- and inter-observer variation in the detection of small tumours on the chest X-ray are quite large (kappa: 0.38 and 0.48, respectively). Providing clinical information or previous chest X-rays for purposes of comparison does not improve the observer performance. Separate evaluation by two assessors ('double reading') also does not improve the results significantly. Simultaneous evaluation ('dual reading') improves the sensitivity slightly (from 28 to 37%), but has hardly any effect on the specificity (from 93 to 92%), thus improving the results somewhat. The results with computed tomography are much better (high sensitivity but low specificity). A CT-scan of the chest seems indicated in case of a suspicion of lung cancer and/or when there is a (slight) suspicion of lung cancer on the basis of the chest X-ray.

Scimitar syndrome; an unusual congenital abnormality occasionally seen in adults.

Scimitar syndrome a very rare and variable congenital disorder characterized by an anomalous connection of the pulmonary vein with the IVC. The syndrome is mostly seen in very early infancy, but was now recognized in a 46-year-old woman, who was referred to the outpatient clinic of the department of cardiology with complaints of dizziness. Contrast enhanced computer tomography (CT) showed dextroposition of the heart and a large right pulmonary vein joined the inferior vena cava (IVC) just above the level of the diaphragm. The typical features of the syndrome are discussed.

Anorectal function in patients with defecation disorders and asymptomatic subjects: evaluation with defecography.

A controlled radiologic study of anorectal function was performed with the use of defecography in 19 patients with constipation and 13 with incontinence. All patients were age and sex matched to control subjects who were referred for barium enema study and who had no defecation disorder. There were no statistically significant differences between either patient group and the control group in anorectal angle and excursion of the anorectal junction. In the 32 patients and 155 consecutive patients referred for defecography because of a variety of defecation disturbances, approximately twice as many rectal wall abnormalities were seen compared with findings in the control group. These findings included intussusception, rectal prolapse, rectocele, mucosal prolapse, spastic pelvic floor, descending perineum syndrome, and solitary rectal ulcer syndrome. In conclusion, the main role of defecography is to document rectal wall changes during defecation straining as possible causes of evacuation difficulties. Clinical symptoms should also be taken into account when treatment is contemplated.

Defecography: principles of technique and interpretation.

After description of the performance, physiology and normal findings of defecography, the main pathology is discussed as intra-anal rectal intussusception, extra-anal rectal intussusception, mucosal prolapse, rectocele, descending perineum syndrome, spastic pelvic floor syndrome and the solitary rectal ulcer syndrome. Finally, the radiation dose and pitfalls are reported.

Rectal intussusception and rectal prolapse: detection and postoperative evaluation with defecography.

The authors studied pre- and post-operative defecograms in 20 patients with rectal intussusception and three with rectal prolapse to assess the value of defecography in detection of these conditions. Eleven patients also had solitary rectal ulcers. Two to 3 months after surgery, patients underwent defecography, and results were correlated with postoperative symptoms. In all three patients with rectal prolapse, and 13 of 20 with intussusception, findings on postoperative defecograms were normal and symptoms were gone. Abnormalities and symptoms persisted in two patients and recurred in another two. In five patients, symptoms persisted despite normal defecographic findings. In 11 patients with solitary rectal ulcers, rectal lesions were cured in nine; in two, intussusception and rectal lesions recurred. Thus, presence or absence of solitary rectal ulcer corresponded to postoperative symptoms in all cases. Symptoms and postoperative defecographic findings corresponded in 20. This study suggests that rectal intussusception and prolapse most likely lead to defecation disorders and that defecography is useful in detecting them.

Radiation dose in defecography.

The effective dose equivalent, as an expression of total patient risk for exposure to limited areas of the body, and gonadal doses associated with hereditary effects were estimated in 67 consecutive subjects (43 women and 24 men) who underwent defecography. With use of measured entrance exposure values and data from Monte Carlo simulations, the mean effective dose equivalent was estimated at 4.9 mSv +/- 1.6 (490 mrem +/- 160) for women and 0.6 mSv +/- 0.2 (60 mrem +/- 20) for men. The ovarian dose was 15 mSv +/- 5 (1.5 rem +/- 0.5). The testes are not within the primary beam and therefore are exposed to scattered radiation only, hence the low received dose of 0.14 mSv or less (14 mrem or less). These data indicate that defecography is among the radiologic procedures associated with a considerable, but not extreme, radiation dose.