Regional cerebral blood flow in weight-restored anorexia nervosa: a preliminary study.

Twenty-one individuals (19 females, two males) with teenage-onset anorexia nervosa (AN), 19 of whom were weight restored, were assessed using single-photon emission computed tomography (SPECT) 7 years after onset of AN, at a mean age of 22 years. For comparison we recruited a younger group without neuropsychiatric disorder (mean age 9:8 years; five females, four males) who underwent SPECT at follow-up after an operation for coarctation of the aorta or because of lymphatic leukaemia. Ethical considerations precluded the study of regional cerebral blood flow (rCBF) in participants with completely normal development. The group with AN showed marked hypoperfusion of temporal, parietal, occipital, and orbitofrontal lobes compared to the contrast group. rCBF was not correlated to body mass index in any of the groups. Results suggest that, even long after re-feeding has occurred, AN may be associated with moderate to severe cerebral blood flow hypoperfusion in the temporoparietal (or temporoparietooccipital) region and in the orbitofrontal region. A limitation of the study is that the young contrast group in this study could be expected to have a higher global rCBF than the group with AN. However, this should not significantly affect the relative values used in this study.

Administered activity of 99Tcm-MAG3 for gamma camera renography in children.

A method of calculating the activity of 99Tcm-MAG3 to be administered to children of different ages has been developed and evaluated. The suggested administered activity schedule is only valid for estimation of split renal function. The activity required to obtain the same count rate over the kidneys for all ages was calculated as a fraction of the activity administered to an adult by using a biokinetic model and taking attenuation effects into account. The activity schedule is based on the age of the child and was tested using renograms from patients of different ages. Statistical noise was added to the smoothed renograms simulating an injected activity corresponding to 45 MBq for an adult. The precision in the determination of split renal function calculated with four different methods was determined for 500 simulated renograms. The precision was approximately the same for all ages, but varied with the method used. The activity to be administered to a very small child is 90% of the adult activity, decreases to less than 50% between 2 and 5 years of age, and then slowly increases to 100% as the child grows to adulthood.

Administered activity of 99Tcm-DMSA for kidney scintigraphy in children.

Kidney scintigraphy using 99Tcm-dimercaptosuccinic acid (DMSA) is a common gamma camera investigation in paediatric patients. The present study deals with methods of calculating the activity to be administered to children. Our aim is to find a method of calculation which gives the same count density in the gamma camera images for all ages. Four different methods, based on body weight, height, body surface area and a theoretical model, are compared. The count density in the images of the kidneys was studied retrospectively in 85 patients aged between 3 weeks and 19.5 years. Fourteen young adults aged 22.0-31.9 years were also studied. Two of the calculation methods, based on body surface area and the theoretical model, showed no apparent age dependency (i.e. a constant count density was observed for all ages). The variation between individuals was similar with both methods, but only the body surface area method gave a count density comparable to that for the young adults. As the method based on body surface area is also easy to implement, this method is recommended.

Regional cerebral blood flow abnormalities in Rett syndrome.

Sixteen Rett syndrome (RS) girls and 1 24 year old RS woman were compared with 16 neurologically healthy children as to the regional cerebral blood flow (rCBF). Hypoperfusion of the frontal lobes and parts of the midbrain was found in RS, with significant differences to controls at latest by the age of three to four years. The findings were in accordance with previous reports of morphological, neuroradiological and functional abnormalities in these areas, compatible with a statement that structures in the midbrain and in the frontal lobes may have particular pathophysiological relevance in RS.

Radiopharmaceutical dosage of 99Tcm-HMPAO for cerebral blood flow SPET studies in children.

Four methods of calculating the activity of 99Tcm-hexamethylpropyleneamine oxime to be administered in cerebral blood flow investigations of children were evaluated in patient studies. Three of the methods were based on the size of the child. We also constructed a theoretical dosage model based on physiological data and attenuation effects. The aim of the study was to find a dosage calculation method that gave the same image quality for children of all ages as well as for adults. The results showed that the dosage method based on body weight is the only one of the four methods that does not exhibit an age-dependent variation in image quality and therefore this method is recommended.

SPECT (Single Photon Emission Computed Tomography) in 31 children and adolescents with autism and autistic-like conditions.

SPECT with Tc-99m-HM-PAO was used in examining 31 patients with autism and autistic-like conditions. Sixteen of these had autistic disorder/autistic-like conditions with associated epilepsy. The autistic disorder group without epilepsy was relatively high functioning. All 31 patients showed reduction of regional cerebral blood flow in the temporal lobes. There was no clear difference between the groups with and without epilepsy, suggesting that seizure disorder per se could not account for the findings.