Michael J. Gelfand

Low-grade vesicoureteral reflux. Variability in grade on sequential radiographic and nuclear cystograms.

Paired voiding cystourethrogram (VCU) and nuclear cystogram (NC) studies in 68 children with vesicoureteral reflux (VUR) were analyzed to determine the variability of VUR on sequential studies. Sequential paired examinations included 82 studies where a VCU was followed by a repeat VCU study and 128 studies where a VCU was followed by a NC study. Grade I VUR on the initial VCU was difficult to duplicate on repeat cystography, regardless of the follow-up modality. When the initial VCU showed no VUR, 20% of follow-up studies demonstrated VUR. Follow-up VCU and NC studies showed similar results in detecting increases and decreases in the grade of VUR. Low-grade VUR may be intermittent, and clinical therapeutic decisions should take this varability into account.

The effects of rate and route of nutrient intake on protein metabolism

Isotopic measurements of protein kinetics are useful for the investigation of metabolic protein disorders during surgical illness. The effects of rate and route (oral vs parenteral) of nutritional substrate intake have not been well defined. Fischer 344 rats were infused with a total parenteral nutrition (TPN) solution at either 25, 100, or 175% of their normal substrate intake or were fed an oral diet ad libitum. After 4 days, [15N]glycine was infused at 0.138 mg 15N/hr for 24 hr. Whole-body protein turnover (WPT), synthesis, and catabolism were determined by 15N urea enrichment. Fractional synthesis rates (FSR) of liver and muscle protein were calculated by analyzing 15N tissue enrichment. WPT (r = 0.93, P less than 0.001) and liver FSR (r = 0.57, P less than 0.01) increased linearly with TPN infusion rates. All rats had protein synthesis rates greater than catabolism rates except for the rats infused with 25% TPN. Although caloric intake was the same in rats fed orally and those infused with 100% TPN, the orally fed rats had faster WPT (P less than 0.001), synthesis (P less than 0.05), catabolism (P less than 0.001), and liver FSR (P less than 0.05) than the TPN rats. Muscle FSR was not significantly affected by either the route of feeding or the TPN infusion rate. In this study, rate and route of substrate intake affected protein kinetics in the whole animal and liver, but not in muscle. Rate and route of nutrient intake need to be carefully specified and controlled during isotopic studies of protein kinetics.

Hepatobiliary scintigraphy in pediatric liver transplant recipients.

The clinical usefulness of hepatobiliary scintigraphy was evaluated in pediatric liver transplant recipients. One hundred fifteen hepatobiliary scintigraphic studies were performed in 30 patients who received 22 whole liver and 16 segmental grafts. Parameters that were useful in predicting an adverse outcome were failure to visualize excreted radiopharmaceutical at or beyond the biliary anastomosis on a study performed within 24 hours after transplant, and persistent or increasing delay in the time of visualization of excreted radiopharmaceutical. Abnormalities of liver uptake and excretion were seen in rejection, but they were also seen in patients who remained well without rejection or parenchymal disease. Significant biliary leaks were identified in the three cases in which they were known to be present. In liver transplant recipients, hepatobiliary imaging is useful in predicting graft survival and identifying biliary leaks.

I-123 iofetamine single photon emission tomography in school-age children with difficult-to-control seizures

Interictal 1–123 iofetamine (IMP) single photon emission tomography (SPECT) was performed in 15 children with difficult-to-control partial or generalized seizures. SPECT studies were compared with magnetic resonance imaging and CT in seven patients, with magnetic resonance imaging only in five, and with CT only in three. Electroencephalography was performed on all subjects, including invasive studies in nine. SPECT was abnormal in six patients. Magnetic resonance and/or CT studies were abnormal in two of the six patients. The other four patients with abnormal SPECT imaging studies had four magnetic resonance and two CT studies that were normal. The SPECT abnormality corresponded to EEG localization in each of the six cases. Lesions localized on SPECT were in or near the temporal lobes. Five other patients with normal SPECT had welllocalized abnormalities on EEG. Four magnetic resonance and five CT studies were also negative in these five cases. Four patients whose EEGs did not show adequate lateralization had four normal SPECT, two normal CT, and three normal magnetic resonance studies. In children as in adults, IMP SPECT imaging shows promise in the localization of seizure foci in or near the temporal lobes.

Radionuclide imaging of Meckel's diverticulum in children.

Fifty-eight children were studied for the presence of Meckels diverticulum by scintigraphy with 99m Tc-pertechnetate. Meckels diverticulum was found at surgery in 6 of 6 patients with positive radionuclide studies and in 2 of 48 patients with negative studies. Four studies could not be interpreted because of widespread intestinal activity. Using the criteria described in this paper, false-positive readings did not occur.

Postoperative evaluation of the Fontan procedure by radionuclide angiography

Seven patients were evaluated by radionuclide angiography (RNA) following Fontan-like procedures for complex cyanotic congenital defects. Both first-pass and ECG gated equilibrium angiography were performed in each. Residual right-to-left shunts, right atrial (RA) outflow and pulmonary arterial obstruction, and left ventricular dysfunction were demonstrated by these techniques. In addition, RA ejection fraction (RAEF) by gated equilibrium scan was measured in each patient. Relatively low RAEF was seen in conjunction with residual obstruction to pulmonary flow. RNA is useful in the postoperative evaluation of patients after Fontan procedures.

Imaging of irradiated liver with Tc-99m-sulfur colloid and Tc-99m-IDA

In three cases, irradiated regions of liver failed to concentrate Tc-99m-sulfur colloid. In two of these three, imaging with Tc-99m-acetanilide iminodiacetic acid (IDA) agents within five days showed near normal hepatic uptake of this henatobiliary imaging agent. The hepatic parenchymal cells may be imaged with Tc-99m-IDA in some irradiated regions of liver, despite loss of reticuloendothelial cell function.

PET/CT in the Evaluation of Neuroblastoma.

I-123-metaiodobenzylguanidine (MIBG) is the most commonly used functional imaging agent in patients with neuroblastoma, but use of [F-18]- FDG PET is increasing. MIBG is useful for defining the extent of disease at diagnosis, following response to treatment, and localizing residual and recurrent disease. In early-stage disease, FDG is often better concentrated in tumor sites than MIBG. In all stages, disease extent in the chest, abdomen, and pelvis and local metastases may be better delineated by FDG. In advanced-stage disease, MIBG is superior for following the treatment response of metastatic tumor in the marrow and bone. Several C-11- and F-18-labeled tracers may be equal to or superior to I-123-MIBG if supply problems can be resolved.

Pinhold imaging: utility in testicular imaging in children.

Pinhole imaging of the testis was done in ten boys with suspected testicular torsion. In three of the ten cases, pinhole images were easier to interpret than images obtained with a converging collimator. In six of the ten cases, pinhole images were required for interpretation of the study, because converging images could not be interpreted.

Production and Application of 123I-Labeled M-Iodobenzylguanidine (123I-MIBG)

131I-Labeled m-iodobenzylguanidine (131I-mIBG) was first synthesized by Wieland and co-workers1 and soon became widely used for diagnosis of neural crest tumors, such as pheochromocytoma2 and neuroblastoma.3 Because of I-123’s superior physical properties for scintigraphic imaging compared to I-131,4 123I-mIBG has become the preferred agent for diagnosis, staging, and clinical follow-up of patients with these tumors. In addition, 123I-mIBG has shown potential for cardiac applications, such as determination of regional myocardial adrenergic activity following myocardial infarctions5 and prioritization of candidates for heart transplantation.6