Evaluation of a low-dose neonatal chest radiographic system

A new low-dose chest radiographic system for use in the neonatal nursery was evaluated. This test system, composed of a Du Pont Kevlar fiber-front cassette, Quanta fast-detail screen, Cronex 4L film (wide latitude), and additional yttrium filtration (0.1 mm), reduced the radiation dose in neonatal chest radiography by 69% (0.9 vs 2.9 mrad [0.009 vs 0.029 mGy]) as compared with a conventional system without added yttrium filtration; the thyroid dose was reduced by 76% (0.9 vs 3.7 mrad [0.009 vs 0.037 mGy]). The cumulative dose reduction was achieved through a combination of factors, including (1) beam hardening by the added yttrium filter, (2) increased X-ray transmission through the Kevlar cassette, and (3) a fast film-screen combination. Scatter radiation at distances of 1 and 6 ft. (0.3 and 1.8 m) was negligible for both systems. Image sharpness was compared for the conventional system with and without added yttrium filtration and for the Kevlar system with yttrium. Although sharpness of bony detail was unchanged by adding yttrium filtration to the conventional system, a decrease in sharpness was noted with the Kevlar system. Because image sharpness was affected in the test system, we are not using the Kevlar-Cronex 4L system for mobile chest radiography in the neonatal intensive care unit, despite dose reductions. However, further study is recommended to determine if there is a slower film-screen combination with yttrium filtration that will not degrade image sharpness.     

Low grade pelviureteric junction obstruction with normal diuretic renography

We report five patients with normal diuretic renograms who underwent Whitaker pressure perfusion testing. They were found to have normal pressure at low flow rates (2-4 ml/min) and an abnormally elevated pressure at high flow rates (8-10 ml/min). Because of persistent symptoms, two patients underwent surgery, while the other three have been followed up. Our findings indicate that a negative diuretic renogram in a well hydrated patient with good renal function may not rule out low grade obstruction. Renal pelvic perfusion at low flow rates as well as high flow rates is recommended to determine better the function of the pelviureteric junction.     

Computed Tomography Angiography with Three‐dimensional Reconstruction for Pulmony Venous Definition in High‐risk Infants with Congenital Heart Disease

Background. Pulmonary venous anomalies may be difficult to define in small, critically ill infants using standard echocardiography. In many centers, invasive cardiac catheterization is used if the diagnosis remains inconclusive. We evaluated computed tomography angiography (CTA) as a low‐risk alternative to cardiac catheterization in these infants. Methods. All infants <7 kg with congenital heart disease who had undergone CTA in a tertiary care pediatric institution during a 30‐month period were included. All had undergone preceding echocardiography, with pulmonary veins defined as normal (group A, n = 40), or abnormal (group B, n = 16). In 6 group B patients, a conclusive diagnosis could not be made by echocardiogram alone. CTAs were analyzed only if contrast density in the left atrium exceeded 200 Houndsfield units. CTA diagnoses (using axial and reformatted 3‐dimensional still frame images, and audio video interleaved loops) were compared with preceding echocardiograms (group A), or echocardiography, catheterization angiography, or surgical findings (group B). Results. Fifty‐six patients (mean age 12.4 weeks; range 0–64; mean weight 4.19 kg; range 1.4–7) were included. There were no scan complications. Mean scan duration was 4.6 seconds (range 1.84–11). Scan indications in group A were related mainly to arch (57.5%) and airway issues (17.5%). In group B, most patients had variations of anomalous pulmonary venous return (43.75%), with postsurgical stenosis the second largest group (31.25%). CTA diagnoses were confirmed in all patients. Additional diagnostic confirmation in group B was made at catheterization (1/16) or during surgical intervention (15/16). Conclusion. Normal and abnormal pulmonary veins could be defined accurately, safely, and rapidly by CTA in all cases. Three‐dimensional reformatting provided additional assistance with surgical planning. Echocardiography remains the first‐line choice for diagnostic imaging in all patients with pulmonary venous anomalies. However, when echo diagnosis is inconclusive, CTA and not catheterization should be considered the next imaging modality of choice.     

Elimination of myeloma cells from bone marrow by using monoclonal antibodies and magnetic immunobeads

The efficacy of immunomagnetic beads to purge human myeloma cells from bone marrow ex vivo was evaluated. The optimal conditions for purging were studied first by using three myeloma cell lines: RPMI-8226, SKO- 007, and SKMM-2. Myeloma cells labeled with the vital fluorescent dye Hoechst 33342 were admixed with normal bone marrow cells, and two monoclonal antibodies reactive with the myeloma cells (PCA-1 and BL-3) were added alone or in combination with the cells. Magnetic beads coated with goat antimouse immunoglobulin G were then added, and the tumor cells to which beads were attached were separated from the mixture with a magnet. The efficacy of tumor cell removal was dependent on the bead-to-tumor ratio; a ratio of more than 500 was optimal in the presence of excess normal marrow cells. The combination of monoclonal antibodies PCA-1 and BL-3 increased the tumor cell removal as compared with either antibody alone. Two cycles of treatment were more effective than one cycle was. Under optimal conditions, 2.3 to 4 logs of tumor cells could be removed from the mixture containing 10% myeloma cells without a significant loss of normal hematopoietic progenitors as measured by CFU-GM, CFU-GEM, and BFU-E. When the efficacy of this procedure was tested on fresh bone marrow from patients with multiple myeloma (MM) by using the combination of PCA-1, BL-3, and J-5, 1.6 to 2.5 logs of tumor cells could be removed by one cycle of treatment, even from marrows containing less than 10% myeloma cells. These observations support the use of monoclonal antibody combinations and immunobeads as a reliable and nontoxic method to eliminate contaminating myeloma cells ex vivo in preparation for autologous bone marrow transplantation in patients with MM.     

Regulation of human peripheral blood erythroid burst-forming unit growth by T lymphocytes and T lymphocyte subpopulations defined by OKT4 and OKT8 monoclonal antibodies

To reexamine the influence that T lymphocytes have on the regulation of human peripheral blood burst-forming unit (BFU-E) proliferation in the absence of a statistically significant number of monocytes, very low numbers (3 to 10 X 10(3)/mL) of a null cell fraction highly enriched for BFU-E were cultured alone and in the presence of 5 X 10(5) sheep erythrocyte-purified, autologous T lymphocytes in a methylcellulose culture system containing erythropoietin. T lymphocytes consistently enhanced the growth of BFU-E from the null cell fraction, as reflected in both their number and size. Irradiation of T lymphocytes prior to coculture with null cells markedly reduced this enhancement, strongly suggesting that T lymphocytes synthesize erythroid burst-promoting factors (BPA). To determine whether there were functional differences between the two major T lymphocyte populations as defined by OKT4 (T helper/inducer) and OKT8 (T suppressor/cytotoxic) murine monoclonal antibodies to stimulate the growth of BFU-E, both T cell subpopulations were isolated by negative (panning) or positive (fluorescence-activated cell sorting) selection and cocultured with null cells. No statistically significant differences emerged between unseparated, OKT4+ and OKT8+ T lymphocytes in their ability to stimulate the growth of BFU-E. Thus, these studies provide further evidence that T lymphocytes are a major population of BPA-producing cells and further that OKT4+ and OKT8+ T lymphocytes equally elaborate these factors.     

Rapid improvement in the renal tubular dysfunction associated with tyrosinemia following hepatic replacement.

The postoperative management of patients with hereditary tyrosinemia type I (McKusick 27670) following liver transplantation is often complicated by the renal tubular dysfunction associated with this disease. To characterize better the temporal course of the improvement in renal excretory activity following hepatic replacement, renal tubular function and metabolite excretion were studied in a 4-year-old girl with hereditary tyrosinemia during the immediate post-transplantation course. Tubular reabsorption of bicarbonate and phosphate were normal 5 days following transplantation, in contrast to glucosuria, hyperaminoaciduria, and tyrosyluria, which persisted for approximately 3 weeks. After hepatic replacement, serum amino acid concentrations returned to normal and succinylacetone was no longer detected in the urine. This is the third tyrosinemia patient reported to achieve complete resolution of urinary abnormalities following transplantation, and the only patient in whom renal tubular function was formally assessed within the first postoperative week.     

Minoxidil for control of acute blood pressure elevation in chronically hypertensive children

Twenty-three episodes of acute elevation of BP related to renal disease in 13 chronically hypertensive children 2 to 18 years of age were treated with a single oral dose of minoxidil. All except one patient were receiving a diuretic and all but one a beta-blocking agent at the time of minoxidil treatment. The goal of lowering BP to or below the 95th percentile for age within four hours of minoxidil administration was achieved in 14 of 23 treatment episodes. The goal was achieved in nine of 11 (82%) when the dose of minoxidil was greater than or equal to 0.2 mg/kg and in five of 12 (42%) when the dose was less than 0.2 mg/kg (P less than .05). In patients treated with greater than or equal to 0.2 mg/kg of minoxidil, mean systolic and diastolic BP decreased significantly from pretreatment values within one hour. In patients receiving less than 0.2 mg/kg, mean systolic BP was never significantly reduced and mean diastolic BP did not change significantly for two hours. Adverse effects were minimal. The results indicate that minoxidil in a dose of 0.2 mg/kg in combination with a diuretic and beta-blocking agent will lower BP to safe levels in most patients with severe hypertension related to renal disease within four hours with minimal side effects.     

Effect of calcitonin replacement therapy in idiopathic juvenile osteoporosis

An 8-year-old boy with idiopathic juvenile osteoporosis and multiple fractures had three abnormalities of bone mineral metabolism: calcitonin deficiency, elevated serum calcitriol concentrations, and hypercalciuria. Calcitonin deficiency was documented by two attempts to stimulate calcitonin secretion with intravenous calcium and pentagastrin. Treatment for 11 months with daily subcutaneous injections of human calcitonin and oral administration of calcitriol failed to reduce the excessive bone resorption observed on bone biopsy, and the fracture rate did not decrease. Treatment was discontinued for two months, then resumed with calcitonin injections and oral calcium supplementation. The fracture rate decreased but bone biopsy continued to show excessive resorption. Therapy was discontinued. After the onset of puberty, endogenous calcitonin was detectable. Exogenous calcitonin therapy may have failed to control bone resorption for several reasons: insufficient dose, reduction of bone receptors from long-term calcitonin exposure, secondary hyperparathyroidism, or lack of association between calcitonin deficiency and the bone disease.     

Congenital diaphragmatic hernia in neonates: variations in umbilical catheter and enteric tube position

PURPOSE: To evaluate anatomic variations of support apparatus position on radiographs obtained in neonates with congenital diaphragmatic hernia (CDH). MATERIALS AND METHODS: The authors evaluated radiographs obtained in 71 neonates with CDH to determine whether nasogastric tubes, umbilical venous catheters, and umbilical arterial catheters deviated from their expected anatomic course. The relationship between deviation patterns and hernia contents was evaluated. RESULTS: Sixty-eight neonates-54 with left-sided CDH and 14 with right-sided CDH-had a nasogastric tube. The tubes in 21 patients with left-sided CDH had a normal anatomic course at radiography. Nineteen of these patients did not have stomach in the hernia. In 13 patients, the tip of the nasogastric tube was lodged at the esophagogastric junction. In 17 patients, the tube was in the left hemithorax. In all 30 of these patients, the stomach was within the CDH. All nasogastric tubes in the 14 patients with right-sided CDH had leftward deviation. Thirty-seven patients-27 with left-sided CDH and 10 with right-sided CDH-had umbilical venous catheters. The catheters in 12 patients with left-sided CDH had apex leftward convexity. The umbilical venous catheter in eight patients with right-sided CDH had rightward shift; all eight patients had liver herniation. CONCLUSION: The positions of nasogastric tubes and umbilical venous catheters vary in several predictable patterns in neonates with CDH. Knowledge of these variations may be helpful for supporting the diagnosis of CDH in unclear cases and thus avoiding unnecessary apparatus adjustments, and for predicting hernia contents.