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The presence of heterotopic decidual tissue in the sinuses of a pelvic lymph node from a pregnant patient with cervical carcinoma is described. The diagnostic implications are discussed.
We present a completely automated 2D-3D registration technique that accurately maps a patient-specific heart model, created from preoperative images, to the patient's orientation in the operating room. This mapping is based on the registration of preoperatively acquired 3D vascular data with intraoperatively acquired angiograms. Registration using both single and dual-plane angiograms is explored using simulated but realistic datasets that were created from clinical images. Heart deformations and cardiac phase mismatches are taken into account in our validation using a digital 4D human heart model. In an ideal situation where the pre- and intraoperative images were acquired at identical time points within the cardiac cycle, the single-plane and the dual-plane registrations resulted in 3D root-mean-square (rms) errors of 1.60 +/- 0.21 and 0.53 +/- 0.08 mm, respectively. When a 10% timing offset was added between the pre- and the intraoperative acquisitions, the single-plane registration approach resulted in inaccurate registrations in the out-of-plane axis, whereas the dual-plane registration exhibited a 98% success rate with a 3D rms error of 1.33 +/- 0.28 mm. When all potential sources of error were included, namely, the anatomical background, timing offset, and typical errors in the vascular tree reconstruction, the dual-plane registration performed at 94% with an accuracy of 2.19 +/- 0.77 mm.
Detection and monitoring childhood growth disorders requires the correct use of growth charts. A check on the accuracy of every point plotted on Gairdner-Pearson growth charts of premature infants in a hospital paediatric department was carried out. Errors beyond set limits were recorded. Of 611 points plotted on the growth charts of 50 premature infants who were at least 1 year of age at the time of the study, there were 173 (28.5%) points plotted in error. Altogether 94.7% of the errors occurred when plotting the age along the horizontal (X) axis of the growth chart, irrespective of whether weight, length, or head circumference was being measured. There was no evidence that the errors caused appreciable changes in clinical management. Potential sources of error identified were failure to adjust for prematurity correctly, inaccuracy in calculating age, and the use of the logarithmic scale. These errors could be serious and it is important that there should be greater vigilance in using growth charts. The use of age calculators or improved chart design is recommended. Assessment of the use of other growth charts in different settings is also suggested.
Cardiac ischemia causes interstitial leakage of cellular enzymes followed by release of these enzymes into plasma. Quantitative interpretation of these data requires a specific circulatory model, and the performance of such models was investigated. Plasma activities of cardiac enzymes were measured for increasingly abrupt forms of ischemic heart injury in the dog: 1) permanent ligation of the left anterior descending coronary artery (LAD); 2) reperfusion after 2 h of ligation of the LAD; and 3) calcium-free perfusion of the LAD during 10 min (calcium-paradox injury). Release into plasma of a rapidly (41%/h) and a slowly (2.2%/h) catabolized enzyme was calculated from the plasma activities, using a detailed circulatory model with compartments for heart, plasma, muscle, skin, and viscera. The time course of cellular enzyme leakage into interstitial space in the heart was calculated from release into plasma and a range of reported values for transendothelial permeability. Simplification to one- and two-compartment models introduced, respectively, 10 and 2% error in calculated cumulative release. Considering the other sources of error, this implies adequate performance of the two-compartment model. Protein washout from the heart is strongly influenced by expansion of interstitial protein space with dead myocyte volume and depends on the microheterogeneity of necrotic tissue areas. Accelerated release of enzymes into plasma after reperfusion reflects accelerated cellular leakage rather than enhanced washout.
Whether CO2 partial pressure (PCO2) in expired gas may exceed that in arterial blood has been controversial. We measured arterial PCO2 (Paco2) and end-tidal PCO2 (PETco2) in four awake goats during air breathing and during hyperoxic CO2 rebreathing in various conditions of acid-base balance. During air breathing, Paco2 was slightly higher than PETco2; i.e., the mean (+/- SE) difference, Paco2 - PETco2, was positive by + 2.36 +/- 0.53 Torr (P less than 0.001). In contrast, during CO2 rebreathing with the same techniques of measurement, this difference was always negative (mean +/- SE = -11.63 +/- 0.22 Torr, P less than 0.001), and it widened as Paco2 increased with rebreathing. Magnitude of the negative difference during rebreathing was too great to be accounted for by incorrect assumptions or measurement error, even if reasonable contributions from all known sources of error were concurrently invoked. We conclude that during hyperoxic CO2 rebreathing in goats, PETco2 exceeds Paco2.
The dietary intake of population groups may be assessed using food consumption level estimates on a national basis and household food surveys. These may be useful for monitoring secular trends and geographical differences with stable and well-documented populations, but analytical studies of diet and health require data on individuals. Assessment techniques designed to assess the diet of individuals ranging from records with weights of food to questionnaires and biological markers have been critically reviewed in order to assess the accuracy of each. Quantitative estimates of the errors involved will be given. For example, the co-efficients of variation of differences incurred from asking subjects to estimate the weight of food portions, rather than weighing them, may regularly be in the 50% range for foods and 20% for nutrients. A variety of studies suggests that the co-efficients of differences in nutrient intake estimated over 1 day from the 24-hour recall method when compared with observed intakes ranged from 4 to 400%. These errors are believed to be random, and precision can be improved by increasing the numbers of observations on each individual or by increasing the numbers of individuals within each group. However, a substantial loss of power is incurred with errors of this magnitude. A more serious potential source of error is systematic bias due either to differences between different methods of dietary assessment or from deliberate over- or underreporting by the subjects themselves. Studies with the doubly labelled water technique have suggested that substantial underrecording of food intake can occur both in free-living individuals and in athletes. 24-hour urine nitrogen can be used to validate dietary assessments in individuals in nitrogen balance, and on-going studies in Cambridge show that within a group, underreporting occurs in specific individuals rather than in the group as a whole. Independent methods of validating dietary assessments, such as the doubly labelled water technique or the 24-hour urine nitrogen output, must be included in any study of free-living individuals.
Inadvertent administration of non-epidural medications into the epidural space has the potential for serious morbidity and mortality. The aim of this study was to collate reported incidents of this type, describe the potential mechanisms of occurrence and identify possible solutions. We searched medical databases and reviewed reference lists of papers retrieved, covering a period of 35 years, regarding this type of medication incident. The 31 reports of 37 cases found is likely to represent a gross underestimation of the actual number of incidents that occur. "Syringe swap", "ampoule error", and epidural/intravenous line confusion were the main sources of error in 36/37 cases (97%). Given that no effective treatment for such errors has been identified, prevention should be the main defence strategy. Despite all the precautions that are currently undertaken, accidents will inevitably occur. We have identified areas for systemwide change that may prevent these types of incidents from occurring in future.
The recently developed technique of high-speed phase-shifting speckle interferometry combined with temporal phase unwrapping allows dynamic displacement fields to be measured, even for objects containing global discontinuities such as cracks or boundaries. However, when local speckle averaging is included, small phase errors introduced at each time step are accumulated along the time axis, yielding total phase values that depend strongly on the speckle rereference rate. We present an analysis of the errors introduced in the phase evaluation by three sources: intensity errors, velocity errors, and speckle decorrelation. These errors are analyzed when they act both independently and together, for the most commonly used phase-shifting algorithms, with computer-generated speckle patterns. It is shown that, in a controlled out-of-plane geometry, errors in the unwrapped phase map that are due to speckle decorrelation rise as the time between rereferencing events is increased, whereas those due to intensity and velocity errors are reduced. It is also shown that speckle decorrelation errors are typically more important than the intensity and velocity errors. These results provide guidance as to the optimal speckle rereferencing rate in practical applications of the technique.
On a mechanical model of the lungs systematic (constant) and accidental (random) errors in measuring the volume by the device (see article)-1, were determined and these amounted to +2.7 and identical to 2.2, respectively. The latter was three times as low as the mean-square reproducibility error, i.e. the degree of error in the physiological measurement of FRC. Different sources of errors in the measurement of FRC, among which particular attention is called to errors in defining the helium concentration at the end of the mixing process in closed system, are considered.
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Corpora amylacea in the central and peripheral nervous system are round, amorphous intracellular bodies which are frequently found in large numbers around the ventricles of elderly individuals. These bodies were recently identified in a cytologic preparation of ventricular fluid. Although they have no known diagnostic significance, their possible confusion with yeast forms makes recognition of these structures important.
Parathyroid adenomas, the most common cause of hyperparathyroidism, display diverse histologic patterns. The majority of adenomas form solid masses or show nodular, trabecular, and acinar patterns. In a four-year review of data on 103 surgically resected parathyroid adenomas, we encountered only a single case that showed papillae formation. We report this case to illustrate occurrence of this unusual histologic pattern that might create a diagnostic problem.
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