From Roentgen to magnetic resonance imaging: the history of medical imaging.

Medical imaging has advanced in remarkable ways since the discovery of x-rays 120 years ago. Today's radiologists can image the human body in intricate detail using computed tomography, magnetic resonance imaging, positron emission tomography, ultrasound, and various other modalities. Such technology allows for improved screening, diagnosis, and monitoring of disease, but it also comes with risks. Many imaging modalities expose patients to ionizing radiation, which potentially increases their risk of developing cancer in the future, and imaging may also be associated with possible allergic reactions or risks related to the use of intravenous contrast agents. In addition, the financial costs of imaging are taxing our health care system, and incidental findings can trigger anxiety and further testing. This issue of the NCMJ addresses the pros and cons of medical imaging and discusses in detail the following uses of medical imaging: screening for breast cancer with mammography, screening for osteoporosis and monitoring of bone mineral density with dual-energy x-ray absorptiometry, screening for congenital hip dysplasia in infants with ultrasound, and evaluation of various heart conditions with cardiac imaging. Together, these articles show the challenges that must be met as we seek to harness the power of today's imaging technologies, as well as the potential benefits that can be achieved when these hurdles are overcome.

Pre- and post-operative hydromyelia in spinal dysraphism.

BACKGROUND AND PURPOSE: There has been limited description of hydromyelia after surgery for spinal dysraphism. The opportunity to compare pre- and post-operative hydromyelia in patients with spinal dysraphism has been possible in two groups of patients using MRI. Post-operative assessment and possible relationship of hydromyelia to clinical findings has been made during a 7- to 14-year period. METHODS: A total of 38 patients with congenital lumbar or sacral lipomas and 20 with diastematomyelia were studied pre-operatively with a 1.5-T MRI. Most patients in each group were examined with surveillance MRI (1.5 T) post-operatively. Clinical correlations were carried out with each examination. RESULTS: Of the 38 dorsal or terminal lipoma post-operative patients, hydromyelia increased in 3 and was a new finding in 4. One symptomatic patient in the latter group had extensive septated lumbar hydromyelia. In 8 of 20 diastematomyelia patients, pre-operative hydromyelia was unchanged post-operatively. Hemicord hydromyelia developed in 1. CONCLUSION: Hydromyelia of varying degree was found in almost one-third of post-operative dorsal or terminal lipoma patients and nearly one-half of diastematomyelia patients. In five post-operative lipoma and two diastematomyelia patients, significant neurological findings remained. One of the six post-operative lipomas had new extensive lumbar hydromyelia that may have been responsible for the patient's symptoms. In the remaining symptomatic patients, hydromyelia was absent or modest.

Congenital lumbosacral lipomas: pitfalls in analysing the results of prophylactic surgery.

OBJECTIVES: Our objectives were to examine the assumption that the natural history of congenital lumbosacral lipomas in children presenting early and those presenting late is the same, and to determine whether there are factors that might predict the post-operative outcome of surgery among the presenting features of children with lumbosacral lipomas. METHODS: The authors present a clinical series of 50 consecutive cases of congenital lumbosacral lipoma that had been treated surgically. All patients underwent both pre- and post-operative urological assessment and pre-operative imaging with MRI. The case notes, urology assessments and MRI films were studied to provide data on the clinical presentation, follow-up history and urological outcome of the children, as well as on the anatomical features of their lipomas. RESULTS: Analysis of the data revealed a predominance in girls and a bimodal distribution of age at presentation with peaks at 0-2 and 7-8 years. Skin stigmata were more frequent in children below 6 years of age than in older children (P=0.035). The MRI scans demonstrated that the conus lay within the sacral canal more often in girls than boys (P=0.025). Severe bladder dysfunction was significantly more frequent in those presenting at =3 years of age (P=0.017) and there were more normal outcomes in patients operated upon before the age of 3 than in those operated upon at or after this age ( P<0.0001). Eight patients who had been operated upon had severe urological problems at the time of their last assessment (median age of 8 years and 2 months). They were predominantly girls with major pre-operative urological dysfunction. CONCLUSIONS: Formal pre-operative urological assessment proved to be the strongest determinant of final urological outcome. Other predictors of poor urological outcome were large lipoma size and sacral position for the lipoma. This series demonstrates how early and late presenting children may represent different patient groups, follow different natural histories and may therefore not be reliable for comparison purposes. Future studies of prophylactic untethering need to follow cohorts beyond the age of deterioration found in untreated cases (8 years) and must report the salient MRI features that we suggest are predictive of poor outcome.