Baseline perfusion defects were seen on (99m)Tc-dimercapto-succinic acid scan at presentation in 115 of our 151 patients (76%) independent of presentation mode. New permanent defects developed in abnormal and previously normal kidneys, and were associated with urinary tract infection. Being circumcised was associated with fewer urinary tract infections and a lower incidence of observed new permanent defects (5.2% vs 10.2%).
Purpose To investigate the possibility of reducing the injected activity for whole-body [18F]FDG-PET/CT studies of paediatric oncology patients and to assess the usefulness of time-of-flight (TOF) acquisition on PET image quality at reduced count levels. Procedures Twenty-nine paediatric oncology patients (12F/17M, 3–18 years old (median age 13y), weight 45±20 kg, BMI 19±4 kg/m2), who underwent routine whole-body PET/CT examinations on a Siemens Biograph mCT TrueV system with TOF capability (555ps) were included in this study. The mean injected activity was 156 ± 45 MBq (3.8 ± 0.8 kg/MBq) and scaled to patient weight. The raw data was collected in listmode (LM) format and pre-processed to simulate reduced levels of [18F]FDG activity (75, 50, 35, 20 and 10% of the original counts) by randomly removing events from the original LM data. All data were reconstructed using the vendor-specific e7-tools with standard OSEM only, with OSEM plus resolution recovery (PSF). The reconstructions were repeated with added TOF (TOF) and PSF+TOF. The benefit of TOF together with the reduced count levels was evaluated by calculating the gains in signal-to-noise ratio (SNR) in the liver and contrast-to-noise ratio (CNR) in all PET-positive lesions before and after TOF employed at every simulated reduced count level. Finally, the PSF+TOF images at 50, 75 and 100% of counts were evaluated clinically on a 5-point scale by three nuclear medicine physicians. Results The visual inspection of the reconstructed images did not reveal significant differences in image quality between 75 and 100% count levels for PSF+TOF. The improvements in SNR and CNR were the greatest for TOF reconstruction and PSF combined. Both SNR and CNR gains did increase linearly with the patients BMI for both OSEM only and PSF reconstruction. These benefits were observed until reducing the counts to 50 and 35% for SNR and CNR, respectively. Conclusions The benefit of using TOF was noticeable when using 50% or greater of the counts when evaluating the CNR and SNR. For [18F]FDG-PET/CT, whole-body paediatric imaging the injected activity can be reduced to 75% of the original dose without compromising PET image quality.
The addition of SPECT 4 to 6 hours postinjection of tracer significantly improves the diagnostic accuracy of hepatobiliary scintigraphy compared with planar imaging alone. This accuracy is as good as HBS performed after phenobarbitone stimulation. The combined technique of HBS with SPECT and phenobarbitone has the highest accuracy. Delayed imaging at 24 hours is usually not necessary.
The nephrotoxic potential of anti-inflammatory drugs alone and in compound preparations has been known for over fifty years. Nephrotoxicity associated with selective cyclooxygenase 2 (COX-2) inhibitor use is reported in adult patients but not in children. We present here the first report of reversible acute renal failure associated with the COX-2 inhibitor rofecoxib (Vioxx) in three children. Patient 1, an 18 month old girl with neonatal Bartter syndrome, developed acute renal failure with a peak creatinine of 1.9 mg/dl (164 micromol/l) and severe hyperkalemic metabolic acidosis. Patient 2, a 14 year old boy with a history of rheumatic fever, developed acute renal failure with a peak creatinine of 2.7 mg/dl (240 micromol/l). While patient 3, a healthy 14 year old girl, developed acute renal failure and tubulointerstitial nephritis confirmed on renal biopsy with a peak creatinine of 3.3 mg/dl (287 micromol/L). All children had been taking non-selective non-steroidal anti-inflammatory drugs (NSAID's) immediately prior to rofecoxib use. Renal function returned to normal within one week in all three patients and has remained normal at follow-up. This paper highlights the nephrotoxic risk of COX-2 inhibitor use in the pediatric population.
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