Prediction of the progression of chronic renal failure in children: are current models accurate?

Mathematical models have been used since 1976 in an attempt to predict the progression of chronic renal failure. These models have used the serum creatinine level as either a reciprocal or logarithmic plot against time. The accuracy of such predictions are characterized by either a correlation coefficient (r value) or prediction error (time at which dialysis was predicted minus time at which dialysis actually occurred). Retrospectively, we analyzed 37 children who progressed to end-stage renal disease, grouped them by their respective primary diseases, and calculated both r values and prediction error for each individual and group. Although r values for each group (with the exception of patients less than 1 year of age) were comparable, prediction errors were widely disparate among the various groupings. Individuals within each of the groups had disparate values even though identical r values were present. These observations indicate that predictive models using serum creatinine levels are of limited clinical use and are least useful for patients younger than 1 year of age.

The radiologic study of the normal spine: cervical, thoracic, lumbar, and sacral.

The goal of this discussion is to provide the radiologist with a complete and systematic method of evaluating each area of the spine, and to provide him with anatomically correlated information to assist in the identification of the individual portions of the neural arch on each projection. Photographs of anatomic specimens, wired spine specimens, and appropriate radiographs of each view of the spine are presented.

Ultrasonic evaluation of intracranial pathology in infants: a new technique.

A prospective study had demonstrated the clinical usefulness of water-delay ultrasound as a means of routinely imaging the intracranial contents in infants younger than one year of age. Correlation between ultrasound and CT images was excellent, showing both normal and pathological anatomy. This technique is most helpful in the detection of hydrocephalus and other "fluid lesions" (subdural hygroma or hematoma, Dandy-Walker cyst, porencephalic cyst) and in evaluation of response to therapy. Because small amounts of intraventricular and subependymal hemorrhage cannot be detected by ultrasound, CT remains the procedure of choice when these conditions are suspected. The water-delay method is accurate and inexpensive, rarely requires patient sedation, and avoids exposure to ionizing radiations.

Intravenous angiography using digital video subtraction: x-ray imaging system.

An x-ray imaging system, using digital subtraction techniques, has been developed. The system requires: (1) high output generation equipment; (2) an image intensifier capable of receiving high output exposures, 1 mR (2.58 X 10(-7) C/kg) at the face of the intensifier, without loss of either contrast or resolution; (3) a precision digital video camera; (4) processing computer with sufficient storage capacity; and (5) digital image storage. With this system it is possible to visualize the major arteries after intravenous contrast injection. The system, angiography technique, and early results are described.

Intravenous angiography using digital video subtraction: intravenous cervicocerebrovascular angiography.

The clinical application of intravenous angiography to study the cervicocerebrovascular system using the digital video subtraction system described in a companion article is reported. About 0.75 ml/kg of a standard 76% iodine contrast solution is injected into an antecubital vein using a power injector. Then 15-20 exposures of the head and neck region at a 1/sec rate are made on the image intensifier. The images are recorded by a high performance video system and the output signal is digitized for subsequent computer manipulation. The subtraction images of these vessels produced by the computer show the vessels clearly, even though they contain very low concentrations of contrast media. Standard exposure factors of 75-80 kVp, 9-10 msec at 800-1,000 mA are used. Clinically pertinent features of the data alteration and flow through the system and the step-by-step computer procedures used to achieve and analyze the various forms of subtracted images are described. Five experimental and clinical cases demonstrate appropriate applications to cervicocerebrovascular disease: (1) evaluating the effects of surgical and medical therapy on atherosclerosis; (2) providing a screening angiographic test for patients with asymptomatic bruits and/or positive noninvasive studies; (3) evaluating patients who have significant generalized vascular disease either precluding or presenting hazardous contraindications to transarterial catheterization; (4) evaluating significantly aged patients in whom standard angiography has higher risk; and (5) evaluating currently asymptomatic patients who are medically at higher risk for developing atherosclerotic lesions. Numerous examples of the various types of image manipulations are presented: (1) linear subtraction; (2) logarithmic subtraction; (3) alterations of electronic contrast enhancement (map slope); (4) the usefulness of a series of angiographic images; and (5) the importance of multiple projections with this technique.