The measurement of lymphocyte volume: importance of reference particle deformability and counting solution tonicity

We have determined the influence of reference particle deformability and suspending buffer tonicity on the measurement of lymphocyte volume by an electronic particle volume analyzer. When the volume analyzer was standardized with latex spherules having a shape factor (fe) of 1.5, red cell volume was 96 cu micron and lymphocyte volume was 289 cu micron. The red cell volume corresponded closely to the true red cell volume; the true lymphocyte volume, however, was 218 cu micron when measured by the lymphocytocrit/lymphocyte count and 203 cu micron by wet lymphocyte weight and density (mean approximately 210 cu micron). The difference between the electronic volume (Ve) of 289 cu micron and true lymphocyte volume of 210 cu micron was due to the influence of lymphocyte deformability (shape factor) as it traverses the sizing aperture. Since the true volume equals the Ve/fe, the red cells with a shape factor near 1.0 were sized appropriately by this method. In contrast, the lymphocyte shape factor was 1.38; thus, the true lymphocyte volume was 289 cu micron/1.38 or 210 cu micron. The tonicity of the suspending solution also influenced the measurement of particle volume when osmotically inactive standard particles (e.g., latex spherules) were used as a reference. Whereas the true lymphocyte volume was 210 cu micron at 286 mosmole/liter, it was 194 cu micron at 330 and 229 cu micron at 250 mosmole/liter. The standard counting solution, Isoton, is hyperosmolar (330 mosmole/liter) and causes an 8% shrinkage of osmotically active cells.     

Transoesophageal echocardiography in congenital heart disease

The development of paediatric transoesophageal ultrasound imaging represents an important advance in the diagnosis and management of the patient with congenital heart disease. Although primary diagnostic transoesophageal studies are seldom indicated in infants and unoperated children, they have an important role in the older child, especially where there has been prior cardiac surgery. Diagnostic studies are most appropriate for abnormalities of venous return, the atria, atrioventricular valves and the left ventricular outflow tract. Two other important areas in which transoesophageal imaging is playing an increasing role in the management of the paediatric patient is in monitoring interventional catheterization and in the intraoperative and immediate postoperative monitoring of surgical repair.     

Electron-beam CT scanning for detection of coronary calcification and prediction of coronary heart disease

Electron-beam or ultrafast computerized tomographic (CT) scanning provides a convenient and sensitive means of detecting coronary calcification, which is an early index of atherosclerosis. The procedure has strong negative predictive power for presence of coronary artery disease, but a limited ability to predict disease severity. However, preliminary indications are that it is as good or better than conventional risk factors in this respect. Although further validation is needed before electron-beam CT can be regarded as an established method of detecting presymptomatic coronary atherosclerosis, the procedure has potential in this context.      

Percutaneous diagnostic and therapeutic interventional radiologic procedures in children: experience in 100 patients

Diagnostic and therapeutic interventional radiologic procedures that provide many treatment options in adults are gaining acceptance in pediatric medicine. Diagnostic (69 patients) and therapeutic (31 patients) interventional experiences in 100 children are summarized, and the procedures of choice for various clinical problems are outlined. Procedures include percutaneous biopsy for benign and malignant diseases, transhepatic cholangiography and biliary drainage, genitourinary procedures (nephrostomy, stent placement, balloon dilation), aspiration of fluid for laboratory analysis, therapeutic drainage of abscesses and noninfected fluid collections, and percutaneous gastrostomy and gastroenterostomy. Diagnoses were accurate in 96% of cases, and therapeutic procedures were successful in 84% of patients, usually obviating operation. Complications occurred in six patients (6%); the most severe was hemoptysis causing respiratory distress. There was no procedure-related mortality. Interventional procedures have wide applications in pediatric patients.     

Periappendiceal abscesses: percutaneous drainage

Percutaneous abscess drainage was performed in 21 patients who had periappendiceal abscesses. Fifteen patients had de novo abscesses, while six patients had persistent postsurgical abscesses. Nineteen of the 21 percutaneous drainages were successful. After percutaneous abscess drainage, interval appendectomy was simple and uneventful in all 14 patients in whom it was performed; four patients had appendices removed prior to percutaneous abscess drainage, and three elderly patients have not required appendectomy (follow-up 1 1/2-3 1/2 years). Percutaneous catheter drainage of periappendiceal abscess performed with computed tomographic guidance is effective and safe. Its benefits include imaging demonstration of the abscess; avoidance of an operation for abscess drainage; temporization of extremely ill patients; simplification of appendectomy, which is made elective; obviation of all operations in selected patients (e.g., elderly or with cardiopulmonary disease); and reduction of hospital stay and cost.     

Liver volume measurements and three-dimensional display from MR images

A method was investigated for measuring the volumes of human livers in vivo from magnetic resonance images and subsequently displaying these livers in three dimensions. Volumetric image sets of phantoms, healthy volunteers, and patients with cirrhotic livers were processed. Two image-processing approaches were compared for accuracy of liver measurements, intrasubject and interobserver variation, and speed of processing. Results indicated that both processing methods had a high degree of volume-measuring accuracy (within 8%), the interobserver measurements had a high coefficient of correlation (r = .9994), the intrasubject measurements had a low coefficient of variation (1.8%), and one method was four to five times faster than the other. The faster and easier of the two image-processing approaches provided satisfactory results for measuring liver volumes, but the slower approach provided more realistic-looking three-dimensional images of the liver.     

Benign postoperative biliary strictures: dilation with fluoroscopic guidance

Benign postoperative biliary strictures in 74 patients were dilated percutaneously with balloon catheters. In all cases, dilation was performed with fluoroscopic guidance in a radiology suite. Lasting patency following removal of biliary stents occurred in 73% of 49 patients with biliary-enteric anastomotic strictures and in 88% of 25 patients with primary ductal strictures, for an overall success rate of 78%. A successful outcome was more likely if the interval between the last biliary tract surgery and balloon dilation exceeded 2 years. Stricture patency was more easily achieved in patients with primary ductal strictures than in those with biliary-enteric anastomotic strictures. Serious, procedure-related complications were encountered when strictures were dilated transhepatically; these included sepsis in 18 of 65 patients and bleeding due to arteriobiliary communications in seven. No serious complications occurred when strictures were dilated via a T tube track, making this the preferred route if available. Surgeons should be encouraged to leave T tubes in place if postoperative biliary stricture is suspected. Balloon dilation should be strongly considered in patients with benign postoperative strictures in whom surgical repair is difficult.     

Focal nodular hyperplasia and hepatic adenoma: comparison of angiography, CT, US, and scintigraphy

The authors reviewed 23 cases of focal nodular hyperplasia and 13 cases of hepatic adenoma, all of which were confirmed pathologically. All solitary masses that exhibited normal or increased uptake of technetium 99m-sulfur colloid were shown to be hyperplasia; while previous criteria such as a central blood supply on angiograms or a central scar on computed tomography (CT) or ultrasound (US) scans were helpful, they were relatively infrequent. A mass that was slightly hypodense and homogeneous on a CT or US scan and highly vascular with an intense capillary stain on an angiogram was almost always hyperplasia. Acute hemorrhage within a focal hepatic tumor was common in adenoma but did not occur in hyperplasia.