Differentiation of Hemorrhage from Iodine Using Spectral Detector CT: A Phantom Study

BACKGROUND AND PURPOSE

Conventional CT often cannot distinguish hemorrhage from iodine extravasation following reperfusion therapy for acute ischemic stroke. We investigated the potential of spectral detector CT in differentiating these lesions.

MATERIALS AND METHODS

Centrifuged blood with increasing hematocrit (5%-85%) was used to model hemorrhage. Pure blood, blood-iodine mixtures (75/25, 50/50, and 25/75 ratios), and iodine solutions (0-14 mg I/mL) were scanned in a phantom with attenuation ranging from 12 to 75 HU on conventional imaging. Conventional and virtual noncontrast attenuation was compared and investigated for correlation with calculation of relative virtual noncontrast attenuation. Values for all investigated categories were compared using the Mann-Whitney U test. Sensitivity and specificity of virtual noncontrast, relative virtual noncontrast, conventional CT attenuation, and iodine quantification for hemorrhage detection were determined with receiver operating characteristic analysis.

RESULTS

Conventional image attenuation was not significantly different among all samples containing blood (P > .05), while virtual noncontrast attenuation showed a significant decrease with a decreasing blood component (P < .01) in all blood-iodine mixtures. Relative virtual noncontrast values were significantly different among all investigated categories (P < .01), with correct hemorrhagic component size estimation for all categories within a 95% confidence interval. Areas under the curve for hemorrhage detection were 0.97, 0.87, 0.29, and 0.16 for virtual noncontrast, relative virtual noncontrast, conventional CT attenuation, and iodine quantification, respectively. A ≥10-HU virtual noncontrast, ≥20-HU virtual noncontrast, ≥40% relative virtual noncontrast, and combined ≥10-HU virtual noncontrast and ≥40% relative virtual noncontrast attenuation threshold had a sensitivity/specificity for detecting hemorrhage of 100%/23%, 89%/95%, 100%/82%, and 100%/100%, respectively.

CONCLUSIONS

Spectral detector CT can accurately differentiate blood from iodinated contrast in a phantom setting.

Intraspecific divergence and convergence of floral tube length in specialized pollination interactions

Floral tubes are often thought to be a consequence of adaptive specialization towards pollinator morphology. We explore floral tube length evolution within Tritoniopsis revoluta (Iridaceae), a species with considerable geographical tube length variation. We ask whether tube lengths of T. revoluta populations are associated with pollinator proboscis lengths, whether floral divergence occurs in the presence of different pollinators and whether floral convergence occurs between distantly related populations pollinated by the same pollinator. Finally, we ask whether tube length evolution is directional. Shifts between morphologically different pollinators were always associated with shifts in floral morphology, even when populations were very closely related. Distantly related populations had similar tube lengths when they were pollinated by the same pollinator. Shifts in tube length tended to be from short to long, although reversals were not infrequent. After correcting for the population-level phylogeny, there was a strong positive, linear relationship between floral tube length and pollinator proboscis length, suggesting that plants are functionally specialized on different pollinators at different sites. However, because tube length evolution in this system can be a bidirectional process, specialization to the local pollinator fauna is unlikely to result in evolutionary or ecological dead-ends such as canalization or range limitation.

Tratamientos complementarios: óxido nítrico, posición en prono y surfactante

The management of hypoxic respiratory failure is based on oxygen delivery and ventilatory support with lung-protective ventilation strategies. Better understanding of acute lung injury have led to new therapeutic approaches that can modify the outcome of these patients. These adjunctive oxygenation strategies include inhaled nitric oxide and surfactant delivery, and the use of prone positioning. Nitric oxide is a selective pulmonary vasodilator that when inhaled, improves oxygenation in clinical situations such as persistent pulmonary hypertension of the newborn, pulmonary hypertension associated with congenital heart disease, and acute respiratory distress syndrome (ARDS). When applied early in ARDS, prone positioning improves distribution of ventilation and reduces the intrapulmonary shunt. The surfactant has dramatically decreased mortality caused by hyaline membrane disease in premature newborns, although the results have been less successful in ARDS. Greater experience is required to determine whether the combination of these treatments will improve the prognosis of these patients.

Radiology quality and performance metrics on the Web: a management information and communications tool

RATIONALE AND OBJECTIVES

The purpose of this study was to demonstrate the feasibility of using the World Wide Web to communicate critical radiology quality and performance metrics to departmental and hospital management staff.

MATERIALS AND METHODS

Data on report turnaround, appointment access, patient and physician satisfaction, and financial performance were harvested from a variety of sources. These were then standardized and condensed so they could be displayed electronically in a concise, information-dense fashion.

RESULTS

The final product was a series of graphic materials on a single Web site. The most informative was a summary "spiderweb chart" that indicated the percentage of specified performance goals achieved for 12 operational parameters. These graphic materials were distributed to management staff monthly by means of e-mail.

CONCLUSION

The use of simple Web-based technology facilitates the collection of key departmental performance data and the dissemination of these data to a wide audience.

Outbreak of a multiresistant Klebsiella pneumoniae strain in an intensive care unit: antibiotic use as risk factor for colonization and infection

An observational study was undertaken to describe a nosocomial outbreak caused by multiresistant Klebsiella pneumoniae (MRKP). Ten patients in the pediatric intensive care unit (ICU) at a hospital in Madrid were colonized by or infected with MRKP from October 1997 to April 1998. Thirty-two patients with MRKP-negative surveillance cultures who were admitted to the ICU during the outbreak period were selected as control patients. Random amplified polymorphic DNA analysis of MRKP isolates revealed patterns that were indistinguishable from each other. After identification of colonized patients by surveillance cultures and implementation of standard and contact precautions, the outbreak was controlled. An age <12 weeks (odds ratio [OR], 13.1) and previous treatment with third-generation cephalosporins and aminoglycosides (OR, 31.2) were independently associated with MRKP colonization and/or infection. Individual exposure to antibiotics, irrespective of other clinical determinants, is a risk factor for MRKP acquisition. Screening high-risk patients during outbreaks and reducing the use of third-generation cephalosporins and aminoglycosides contribute to the control of these epidemics.

Thyroid-specific gene expression in the multi-step process of thyroid carcinogenesis

Thyroid-specific transcription factors TTF-1 and Pax-8 play a decisive role in the determination and maintenance of cellular phenotype activating thyroglobulin (Tg), thyroperoxidase (TPO), thyrotropin receptor (TSH-R) and the sodium/iodide symporter (NIS) gene transcription. In the present work, we have studied the expression of TTF-1 and Pax-8 and their target genes in samples derived from thyroid neoplasms of follicular origin, as well as in medullary carcinoma (MTC), obtained from surgery or from fine needle aspiration (FNA) biopsies. The results show that TTF-1 and Pax-8 are expressed in well differentiated adenomas and that their expression decreases in less differentiated papillary and follicular carcinomas and is lost in undifferentiated anaplastic carcinomas. Parallel levels of Tg, TPO and TSH-R expression were found in the same neoplasm samples. Interestingly TSH-R and TTF-1 gene expression was found in MTC samples. Furthermore, the expression of the thyroid-specific genes and their transcription factors is lost in thyroid cells derived from follicular, papillary and anaplastic human carcinomas. In these cells, Tg, TPO and TSH-R promoter activities were absent. Cotransfection with expression vectors for TTF-1 and Pax-8 resulted in the stimulation of transcription to a different extent for each promoter. These results may be clinically relevant for the evaluation and prognosis of thyroid cancer since the loss of specific markers correlates with the degree of tumor differentiation.

[Postoperative management following single-stage laryngotracheoplasty in acquired subglottic stenosis in children]

Acquired laryngotracheal stenosis (ALTS) in children is a more and more common disease, following the widespread adoption of prolonged endotracheal intubation for respiratory support, specially among newborn and premature infants with respiratory distress syndrome. Several treatment procedures have been described in order to solve this problem; some authors have recently reported encouraging results with single-stage laryngotracheoplasty, making open reconstruction with airway division, cartilage grafts when appropriate, and closure of the tracheotomy tract at the same operation, followed by a short period of endotracheal intubation, avoiding the need for prolonged laryngeal stenting with its associated risks of granulation tissue formation, restenosis and airway obstruction, and with no need of new surgical procedures. Two patients of 9 and 16 months of age underwent successfully the surgical technique described above, with no need of laryngeal stent; postoperative management required several issues in order to prevent an accidental extubation during the time of scarring of the laryngotracheoplasty. No complications occurred. Follow-up at 6 and 12 months after operation was normal, both ventilation and voice quality.

Pituitary-thyroid function in patients with septic shock and its relation with outcome

OBJECTIVE

To study the time course of thyroid function abnormalities and their relation to outcome in patients with septic shock.

DESIGN

Prospective study in a cohort of consecutive patients.

SETTING

Intensive Care Unit in a University Hospital.

PATIENTS AND METHODS

We studied 27 patients (mean age 50 +/- 19 years, Apache II score 18.4 +/- 5.2, 15 survivors) diagnosed of septic shock. Total T4 (T4) and total T3 (T3) (RIA) were determined on days 1 and 5 after admission. We also measured TSH (ultrasensitive RIA) at 08.00, 20.00 and 01.00 hours (on days 1 and 5), and the TSH response to TRH (400 microg intravenous) on days 2 and 6. Data are mean +/- SD.

RESULTS

Whereas low thyroid hormones concentrations were present on day 1 in all patients, only survivors presented a significant increase in T3 and T4 on day 5. Basal TSH levels and the area under the curve of the TSH response to TRH on day 2 were significantly higher in survivors than in non survivors (0.89 +/- 0.63 vs. 0.34 +/- 0.42 microIU/ml, and 229 + 157 vs. 101 + 101). The normal nocturnal (01.00 hr) surge of TSH (the difference between TSH concentrations at 8 am and at 1 am) was abolished in both survivors and non survivors on day 1 but it was recovered on day 5 only in survivors.

CONCLUSIONS

Our data indicate that patients with septic shock present an altered hypothalamic-pituitary-thyroid axis, and that survivors thyroid function differs from that of non survivors shortly after diagnosis. Survivors are characterised by a greater TSH response to TRH, indicating a less deranged hypothalamic-pituitary-thyroid axis. Thyroid function improves in survivors, but not in non survivors, during the course of their illness.

Male gonadal function after chemotherapy in survivors of childhood malignancy

Investigations of adult patients have shown that chemotherapy causes gonadal damage, but much less information is available about the impact of chemotherapy on gonadal function in children with malignant disease. At one time, being prepubertal during therapy was thought to confer some protection against chemotherapy induced gonadal damage. However, recent studies have indicated otherwise. We designed this study to assess gonadal function in 15 postpubertal males who had received polychemotherapy for a malignant disease during childhood and we compared them with 13 control adults males. The mean age of the patients at the time of the study was 18.2 +/- 3.6 years (range 13.8-29.0), and when given chemotherapy treatment was 10.2 +/- 3.0 years (range 6-16). At that time 12 were prepubertal and at the time of the study all were Tanner V. The mean interval from the completion of treatment until the study was 6.42 years (range 2.0-16.5). All patients had received polychemotherapy. We evaluated testicular size, sperm counts, LH and FSH after GnRH test, and testosterone levels. Puberty had progressed normally in all patients. We found no significant differences in testosterone and basal LH levels between patients and controls. However, we detected an appreciable difference in peak LH levels (P < 0.05) and in basal and peak FSH levels (P < 0.001). Seven patients had exaggerated LH response to GnRH, indicating dysfunction of the Leydig cells. The results of semen analyses were: 8 patients had azoospermia, 3 oligospermia, and 1 patient had a normal semen analysis. All patients with semen abnormalities presented a basal and peak FSH higher than the mean +2 SD of the control group. In summary, we found no evidence of gonadal protection in prepubertal patients. We found a high incidence of germinal cell damage, whereas Leydig cell abnormalities were found less often. An endocrine study of patients that have received chemotherapy is warranted.

CT findings of retroperitoneal malignant mesenchymoma

Malignant mesenchymoma (MM) is a rare mesenchymal neoplasm which, by definition, demonstrates at least two distinct types of malignant mesenchymal differentiation. We present the computed tomographic (CT) findings of a 42-year-old female with a pathologically proven retroperitoneal MM consisting of osteoid production combined with foci of liposarcoma and Kaposi sarcoma. MM should be considered along with extraosseous osteosarcoma and teratoma in the differential diagnosis for unusual large heterogeneous retroperitoneal masses with massive calcification.

Effect of thiopentone, etomidate and propofol on systemic vascular resistance during cardiopulmonary bypass

We have studied the effect of thiopentone, etomidate and propofol on systemic vascular resistance (SVR) during cardiopulmonary bypass with constant pump flow in 30 patients undergoing elective coronary artery bypass surgery. SVR decreased to 78% of control values after thiopentone 4 mg kg-1, to 72% of control after etomidate 0.3 mg kg-1, and to 68% of control after propofol 2 mg kg-1; it returned to control values 10 min after administration of thiopentone and propofol and 7 min after administration of etomidate. Analysis of variance showed that there were no significant differences in the changes in SVR between the groups.

Effect of propofol on peripheral vascular resistance during cardiopulmonary bypass

Twenty-eight patients undergoing elective coronary artery bypass surgery were allocated randomly to receive either propofol 2 mg kg-1 or an equivalent volume of its vehicle during cardiopulmonary bypass with constant pump flow. Peripheral vascular resistance (PVR) was calculated from perfusion pressure and pump flow. After propofol, PVR decreased from 1767 (SD 415) dyn s cm-5 to a minimum of 1263 (283) dyn s cm-5 at 2 min, and remained significantly less than the control value until 12.5 min after administration of propofol. In the group given the vehicle, PVR did not change significantly. In a second study in 10 patients, venous blood samples were withdrawn before and 2, 4, 6, 8, 10, 20 and 30 min after injection of propofol 2 mg kg-1 during cardiopulmonary bypass, for measurement of blood concentrations of propofol. Concentrations were greater than predicted by a computer simulation based on published pharmacokinetic data. The decrease in PVR may be an important factor in the hypotension caused by propofol during induction of anaesthesia.

Sensitivity of MRI in metastatic neoplasia: a case report

Serial magnetic resonance imaging (MRI) and computed tomography (CT) were performed on a patient with metastatic lung cancer to brain. Magnetic resonance (MR) visualized two foci of intracerebral metastasis six weeks prior to CT.