Diane S. Babcock

Optimal timing for diagnostic cranial ultrasound in low-birth-weight infants: Detection of intracranial hemorrhage and ventricular dilation

Intracranial hemorrhage and posthemorrhagic ventricular dilation are common problems in small preterm infants. To determine the optimal timing for ultrasound diagnosis of these abnormalities, we studied 64 preterm infants (less than 1,500 gm) by sequential cranial ultrasonography from birth until one year of age or until death. The optimal timing for ultrasound diagnosis of intracranial hemorrhage is days 4 to 7 with follow-up at day 14. The most efficient time for ultrasound examination to diagnose ventricular dilation was day 14 with follow-up at 3 months. Intracranial hemorrhage was diagnosed by ultrasound in 35 of the 64 patients (55%). In 18 of the 64 infants (28%) significant ventricular dilation was diagnosed by ultrasound during the first three months.

Power Doppler sonography: basic principles and clinical applications in children

Power Doppler sonography is a new technique that displays the strength of the Doppler signal in color, rather than the speed and direction information. It has three times the sensitivity of conventional color Doppler for detection of flow and is particularly useful for small vessels and those with low-velocity flow. Power Doppler sonography shows potential for detecting areas of ischemia in the kidney, brain, and prepubertal testis and for demonstrating hyperemia in areas of inflammation. Its increased sensitivity to motion and flash artifact, however, limits its application in children. Power Doppler is useful as an adjunct to conventional color and pulsed Doppler sonography.

Minimal vitamin D and high calcium and phosphorus needs of preterm infants receiving parenteral nutrition

Preterm infants (birth weight, 1,089 ± 91 g; gestational age, 28.9 ± 0.7 weeks; mean ± SEM) with mixed medical and surgical indications for parenteral nutrition (PN) were observed to determine the adequacy of infusates with fixed, low-dose vitamin D (25 IU/dl) and two combinations of calcium and phosphorus. The duration of low-dose vitamin D PN ranged from 5 to 52 days, with a median of 27 days. Twelve infants were randomly assigned to low (standard) Ca and P doses (5 mM each; 20 mg/dl of Ca and 15.5 mg/dl of P) and 13 high Ca and P doses (15 mM each; 60 mg/dl of Ca and 46.5 mg/dl of P). The maximum daily vitamin D intake was similar for both groups (31 ± 1.3 versus 33 ± 1.2 IU/kg). Vitamin D status in either group, as indicated by serum 25-hydroxyvitamin D (25-OHD) concentrations, was normal. There was no significant difference in observed changes of serial measurements of serum calcium, magnesium, phosphorus, alkaline phosphatase, creatinine (Cr), 25-OHD, and vitamin D-binding protein concentrations or urinary Ca:Cr and Mg:Cr ratios. In the low-dose Ca and P group, the serum P level was consistently <4 mg/dl in five infants, serum 1,25-dihydroxyvitamin D concentrations were higher, and tubular reabsorption of phosphorus was consistently <95% and significantly higher than in the high-dose Ca and P groups. Severe bone demineralization apparent on X-ray occurred in two infants, with a fractured distal left ulna in one of the two infants. Abdominal ultrasonograms showed gallbladder “sludge” in six infants (four in the low-dose and two in the high dose Ca, P group) that resolved with enteral feeding. We conclude that for preterm infants receiving PN, the vitamin D requirement is minimal. A high Ca- and P-level (15 mM each) infusate may be more appropriate than low Ca and P levels (5 mM each) to maintain Ca and P homeostasis.

Cerebrospinal fluid pseudocysts: sonographic appearance and clinical management

Eight patients with 10 intraperitoneal cerebrospinal fluid pseudocysts occurring as a complication of ventriculoperitoneal (VP) shunt procedure were reviewed to determine the sonographic characteristics as well as the etiologic basis for the pseudocysts. An additional 10 patients with VP shunts, being routinely evaluated for genitourinary tract abnormality, were reviewed to determine the sonographic characteristics and the amount of fluid present in the abdomen with a normally functioning VP shunt in place. We found that a small amount or no peritoneal fluid is found in the patient with a normally functioning VP shunt. Larger, localized, simple or loculated fluid collections are abnormal and compatible with pseudocyst formation. Debris was identified in the majority of the fluid collections. We believe that ultrasonography is the method of choice in evaluation of complications of the distal end of the VP shunt. Our series suggests that infection is the principle cause for pseudocyst development despite the frequent absence of systemic signs of infection. Appropriate treatment involves removal of the peritoneal catheter and treatment of the infection. The catheter may later be replaced intraperitoneally.

Parenteral nutrition for infants: effect of high versus low calcium and phosphorus content

Calcium (Ca) and phosphorus (P) homeostasis were determined in 18 infants (birth weight, 2,810 ± 135 g; gestational age, 37.4 ± 0.5 weeks; mean ± SEM) who received high or low Ca and P content (Ca, P) parenteral nutrition (PN) with a fixed, low dose of vitamin D (25 IU/dl). Nine infants were randomized into low (standard) Ca, P (20 mg Ca and 15.5 mg P/dl) and nine into high Ca, P (60–80 mg Ca and 46.5–62 mg P/dl) PN, and then were studied for up to 6 weeks. The high Ca, P group had stable serum 1,25 dihydroxyvitamin D [1,25(OH)2D], which consistently remained within the normal range (<116 pg/ml). Tubular reabsorption of phosphorus (TRP) also was stable and remained consistently <90%. The low Ca, P group had elevated and higher 1,25(OH)2D (p = 0.03) than the high Ca, P group. The mean serum 1,25(OH)2D concentration rose from 32 to 112, 115, and 133 pg/ml over a period of 6 weeks. TRP also was higher (p = 0.02) and remained consistently >90%. There were no significant differences between groups in serum parathyroid hormone, calcitonin, Ca, Mg, P, alkaline phosphatase, vitamin D binding protein, and 25 hydroxyvitamin D concentrations; urine Ca/creatinine and Mg/creatinine ratios, and fractional excretion of sodium (Na). Thus, a “high” Ca (60 mg/dl) and P (46.5 mg/dl) content in PN solutions can result in stable serum 1,25(OH)2D and TRP, presumably reflecting minimal stress to Ca and P homeostatic mechanisms without further increase in urinary Ca excretion.

Comparison of color Doppler sonography and radionuclide imaging in different degrees of torsion in rabbit testes.

RATIONALE AND OBJECTIVES We compared color Doppler sonography and radionuclide imaging in an animal model of variable torsion of the testes. METHODS The testes of 19 rabbits with unilateral 0 degree (nontorsion), 180 degrees, 360 degrees, or 540 degrees torsion and contralateral nontorsion were evaluated by sonography serially over 24 hr. Color Doppler sonography and radionuclide imaging at 24 hr were compared and correlated with pathology in a subset of testes. RESULTS Nontorsion (n = 16 testes) and 540 degrees torsion (n = 7 testes) were always correctly diagnosed at 24 hr by color Doppler sonography and radionuclide imaging. Torsion at 180 degrees (n = 2) was indistinguishable from nontorsion. With 360 degrees torsion (n = 6 testes), four testes had reduced or absent flow with color Doppler sonography, whereas only one testis was abnormal with radionuclide imaging. CONCLUSION Nontorsion and extreme torsion of rabbit testes are well documented by radionuclide imaging and color Doppler sonography. Torsion at 360 degrees can result in variable flow alterations that are better detected by color Doppler sonography than by radionuclide imaging.

Intraoperative uses of ultrasound in the pediatric neurosurgical patient

Ultrasound imaging has become a common method for intraoperative evaluation of the central nervous system. Real-time monitoring aids in guidance for aspiration of fluid collections and placement of catheters as well as the localization and evaluation of masses, and confirmation of their complete removal. Color Doppler is useful in the evaluation of blood flow in arteriovenous malformations, aneurysms, and neoplasms. Consultation among the ultrasound staff, neuroradiologists, and neurosurgeons before the operative procedure maximizes the usefulness of ultrasound, thus aiding in the success of surgery.

Quantification of intravenous contrast-enhanced Doppler power spectrum in the rabbit carotid artery

In vivo evaluation of Doppler contrast agent (DCA) enhancement has been principally qualitative. To quantitate the enhancement of the Doppler signal by perflubron emulsion, an investigational DCA, the audio-Doppler signal from the rabbit carotid artery was recorded during 0.5-ml/kg incremental doses to a total dose of 2.5 ml/kg. A representation of the recorded signal intensity, the Doppler power spectrum (DPS), was determined using a personal computer and commercially available software package. The dose related enhancement from perflubron emulsion was linear (r = 0.986, p = 0.0124) with a 710% (8.5 dB) overall enhancement at 2.5 ml/kg (p = 0.0001). Significant differences in enhancement could be detected with doses as low as 1.0 ml/kg and compared favorably with observer assessment of dose-related enhancement. This relatively simple method of computer analysis can quantify in vivo Doppler signal intensity and enhancement by perflubron emulsion and may enable quantitative comparisons between different DCAs.

Doppler contrast sonography for detecting reduced perfusion in experimental ischemia of prepubertal rabbit testes

RATIONALE AND OBJECTIVES We examined whether the intravenous (IV) Doppler ultrasound contrast agent SHU 508 would improve the detection of reduced perfusion of rabbit testes when normal flow was otherwise difficult to detect. METHODS Seventeen anesthetized prepubertal rabbits underwent random unilateral spermatic cord ligation and a contralateral sham operation. Immediate, blinded, and systematic color Doppler examination of each pair of testes was recorded before and after IV administration of 1 ml (300 mg) SHU 508, a gas-containing microparticle. Recorded examinations were reviewed by two pediatric radiologists who were unaware of experimental conditions and who graded intratesticular flow. RESULTS For 34 pairs of observations (17 animals x 2 observers), intratesticular flow was absent in the sham-operated testes in 18 precontrast and two postcontrast images. The false-positive rate in this group decreased from 53% to 6%. This improvement in the detection of normal blood flow was statistically significant. The absence of flow in the ischemic testis was not significantly different before or after contrast agent administration. CONCLUSION IV SHU 508 enhances color Doppler ultrasound detection of flow not otherwise evident in prepubertal rabbit testes. Doppler ultrasound contrast agents may be used in a setting of suspected torsion when routine Doppler sonography is indeterminate.

Very-low-birth-weight, Preterm Infants With or Without Intracranial Hemorrhage Neurologic, Cognitive and Cranial MRI Correlations at 4-8-year Follow-up

Fourteen very-low-birth-weight (VLBW) preterm infants with and without intracranial hemorrhage (ICH) were prospectively followed from birth to 4 to 8 years for the purpose of determining neurologic and cognitive sequelae associated with ICH severity and to correlate outcomes with brain morphology as determined by Magnetic Resonance Imaging (MRI). Intracranial hemorrhage was documented by cranial ultrasonography performed in early life. Follow-up assessments included neurologic and psychometric examinations and cranial MRI scans. Of six children with no ICH, five had normal results on all three follow-up measures. Three children with Grade I-II ICH had mild to moderate neurologic and cognitive sequelae with focal white matter MRI abnormalities. Five children with Grade III-IV ICH had severe neurologic, cognitive, and MRI deficits, including MRI regional and diffuse white matter abnormalities and/or cortical atrophy. Focal and diffuse neurologic deficits correlated with the extent of MRI morphologic abnormalities. Results of this study indicate that ICH severity correlated with outcomes in children at follow-up ; the more severe the ICH, the more adverse the neurologic, cognitive, and MRI results. MRI white matter abnormalities were present in all children with any degree ICH, while ventriculomegaly was seen only in severe ICH (Grade III-IV ICH). Neurologic deficits correlated with MRI structural abnormalities.