Sedation and general anaesthesia in children undergoing MRI and CT: adverse events and outcomes.

Quality assurance data were collected prospectively for children who were sedated (n = 922) or given general anaesthesia (n = 140) for magnetic resonance imaging (MRI) or computerized tomography (CT). The data included patient characteristics, concurrent medication, adequacy of sedation, adverse events and requirement for escalated care. The quality of scans was evaluated. Reasons for preselection of general anaesthesia included previously failed sedation (28%), potential for failed sedation (32%) and perceived medical risk (14%). Hypoxaemia occurred in 2.9% of sedated children, and was more common in children classified as ASA III or IV. Sedation was inadequate for 16% of children and failed in 7%. Failed sedation was associated with greater age (P = 0.009), higher ASA status (P = 0.04) and use of benzodiazepines as sole sedatives (P < 0.03). More of the children who underwent general anaesthesia were ASA III or IV than sedated children, yet the procedure was successful in all the children who underwent general anaesthesia, with one incident of laryngospasm. Excessive motion was noted in 12% of scans of sedated children and 0.7% of those completed with general anaesthesia. We conclude that sedation of children for MRI and CT is associated with risks of hypoxaemia and of inadequate or failed sedation. These adverse events were more likely to occur in older children, those with a higher ASA status and those in whom benzodiazepines had been used as sole sedatives. For a preselected high-risk group of children, general anaesthesia may make MRI and CT scans more successful with minimal adverse events.

MR imaging of hemorrhagic brain lesions: a comparison of dual-echo gradient- and spin-echo and fast spin-echo techniques.

OBJECTIVE: Our objective was to assess the usefulness of the dual-echo gradient- and spin-echo (GRASE) technique in revealing acute hemorrhagic brain lesions and compare GRASE and fast spin-echo techniques for revealing acute hemorrhagic lesions and image artifacts. MATERIALS AND METHODS: Thirty-two consecutive patients with acute intracranial hemorrhage underwent dual-echo GRASE (TEeff1/TEeff2, 35/85) and fast spin-echo (25/110) imaging. The techniques were matched for TR (3032 msec), spatial resolution, and acquisition time. Two neuroradiologists reviewed the images independently, documenting the number, size (<1, >1, or 1 cm in diameter), location, and signal characteristics (hypointense versus hyperintense compared with brain) of detectable lesions. These observers also compared matched T2- and proton density-weighted GRASE and fast spin-echo images for paramagnetic lesion conspicuity, diamagnetic susceptibility artifacts, chemical shift artifacts along the phase- and frequency-encoding directions, and artifactual CSF hyperintensity in the thin curvilinear cortical sulci and the Virchow-Robin spaces on only the proton density-weighted images. RESULTS: The average number and conspicuity of dark (paramagnetic) lesions were significantly greater on GRASE than on fast spin-echo images (p < .05 and p < .001, respectively). We found no significant difference in the average number of bright lesions revealed by either technique (p > .1). Chemical shift artifacts along the phase-encoding directions were more prominent on GRASE than on fast spin-echo imaging. Chemical shift artifacts along the frequency-encoding directions and artifactual CSF hyperintensity were more prominent on fast spin-echo than on GRASE imaging. No visually apparent difference was found in the degree of diamagnetic susceptibility artifacts seen with the two techniques. CONCLUSION: Dual-echo GRASE imaging can be helpful in the examination of patients with suspected acute brain hemorrhage.

GRASE (gradient- and spin-echo) MR of the brain.

PURPOSE: To assess the clinical utility of GRASE (gradient- and spin-echo) MR imaging of the brain by comparing it with the T2-weighted turbo spin-echo technique. METHODS: Fifty-three consecutive patients referred for MR imaging of the brain were studied with T2-weighted turbo spin-echo and GRASE techniques, matched for effective echo time (110 milliseconds), echo train length (eight), and spatial resolution. The examinations were evaluated independently by two neuroradiologists for lesion detection (high- and low-signal-intensity lesions) and lesion conspicuity, and for susceptibility, motion, and chemical-shift artifacts. RESULTS: The GRASE technique provided greater detection of both high- and low-signal-intensity lesions and of low-signal-intensity lesions with paramagnetic susceptibility characteristics (ie, calcium and hemorrhage). Chemical-shift artifacts in the frequency-encoding direction were more prominent with the turbo spin-echo technique, whereas chemical-shift artifacts in the phase-encoding direction were more prominent with the GRASE technique. There was no significant difference in the degree of diamagnetic susceptibility artifacts at the base of the skull, or in motion artifacts. CONCLUSION: T2-weighted GRASE is a fast imaging technique with a potential for replacing turbo spin-echo in routine MR imaging of the brain. GRASE maintains the contrast resolution of turbo spin-echo imaging and is better at depicting lesions with paramagnetic susceptibility characteristics.

Carpo-metacarpal growth disturbance and the assessment of carpal narrowing in children with juvenile rheumatoid arthritis.

Second metacarpal length (M2), radio-metacarpal length (RM), and intermetacarpal width (W) were measured on 96 radiographs in 52 children with polyarticular juvenile rheumatoid arthritis (JRA), and compared with body height and skeletal maturation in order to: (1) differentiate between processes resulting in retardation of bone growth and those producing delay in skeletal maturation; (2) assess the severity and progression over time of such retardation; and (3) assess the impact of retardation of the second metacarpal on the assessment of carpal narrowing in children with JRA. All measurements were converted into z scores (the units of standard deviation above or below the normal mean for each measurement) based on published norms. Retardation of M2 (mean z scores -0.91) began earlier and was more severe compared with retardation of height (mean z score -0.25). This disproportion widened with increasing duration of disease. That this primarily represents a disturbance in M2 growth rather than a secondary effect due to altered maturation is suggested by the bone ages being normal (mean z score 0.14) and the absence of premature closure of the metacarpal physes. Z scores for RM/W (mean -3.53) were at least 1 Z more negative than for corresponding measurements of RM/M2 (mean -2.41) in 47 (90.4%) children and the mean difference between the z scores for RM/W was -1.12. This discrepancy between RM/W and RM/M2 was eliminated by correcting for the reduction in M2.