The evolution of cerebral blood flow in the developing brain: evaluation with iodine-123 iodoamphetamine SPECT and correlation with MR imaging. (73/4352)

BACKGROUND AND PURPOSE: Although it is well established that brain maturation correlates temporally with the functions the newborn or infant performs at various stages of development, the precise relationship between function and anatomic brain maturation remains unclear. The purpose of this study was to investigate the developmental changes of regional cerebral blood flow (rCBF) in infants and children using iodine-123 iodoamphetamine (123I-IMP) and single-photon emission computed tomography (SPECT). These findings were correlated with the MR imaging appearance of the brain and with known developmental changes. METHODS: Twenty-one 123I-IMP SPECT examinations of 17 patients, ranging in age from neonates to 2 years, were reviewed retrospectively. All children had had transient neurologic events in the neonatal period that did not significantly affect subsequent neuropsychological development. MR studies were performed in 12 of these patients and the MR findings were correlated with the SPECT results. RESULTS: SPECT studies showed a consistent pattern of evolving changes in 123I-IMP uptake, most likely reflecting evolution of rCBF. From the 34th postconceptional week until the end of the second month after term delivery, there was predominant uptake in the thalami, brain stem, and paleocerebellum, with relatively less cortical activity. Radionuclide uptake in both the perirolandic and occipital cortices was well seen around the 40th postconceptional week and increased rapidly thereafter, with a predominance of parietal activity. By 3 months, radionuclide uptake in the cerebellar hemispheres and parietofrontal cortices increased. Frontal and temporal activity increased by age 6 to 8 months. Uptake in the basal ganglia increased by 8 months. By the beginning of the second year, rCBF showed a similar topographic pattern to that in adults. CONCLUSION: The time course of the changes in 123I-IMP uptake in the developing brain as detected by SPECT is similar to that of myelination and most likely reflects an overall topologic maturational pattern of the brain.  (+info)

Brain perfusion imaging in asymptomatic patients receiving cyclosporin. (74/4352)

BACKGROUND AND PURPOSE: Cyclosporin has neurotoxic effects in a significant number of transplant patients that are associated with characteristic findings on MR images. Focal abnormalities in cerebral perfusion have been implicated in the pathophysiology of cyclosporin neurotoxicity. In the clinically asymptomatic patient, however, it is not known whether any imaging evidence of cyclosporin's effect on the brain is demonstrable. Our hypothesis was that conventional MR imaging, perfusion MR imaging, and single-photon emission CT (SPECT) could enable detection of subclinical lesions in asymptomatic patients. The ability to detect such lesions might aid in the identification of persons most at risk for clinical neurotoxicity. METHODS: Ten posttransplant patients being treated with cyclosporin were recruited prospectively. Imaging studies were performed within 3 weeks of transplantation. Patients were examined with MR imaging, using standard spin-echo and dynamic contrast-enhanced perfusion techniques, and SPECT scanning. Postprocessing of MR perfusion data was performed to obtain pixel-by-pixel maps of regional cerebral blood volume, peak height, and time-to-peak parameters. RESULTS: The mean age of the patients was 45 +/- 11 years. At the time of imaging, three patients had minor neurologic manifestations commonly associated with cyclosporin (ie, mild tremor, headache), but no patient had clinical neurotoxicity. Findings on conventional MR images, MR perfusion maps, and SPECT perfusion scans were normal in all patients. CONCLUSION: Conventional MR imaging, dynamic perfusion MR imaging, and SPECT do not depict any lesions in asymptomatic patients on cyclosporin. Therefore, it may not be possible for imaging methods to aid in the identification of patients at risk for neurotoxicity. Our findings support previously published conclusions that the lesions visible in patients with clinical neurotoxicity are due to cyclosporin effects and not to preexisting coincidental abnormalities.  (+info)

Decreased cerebellar blood flow in postinfectious acute cerebellar ataxia. (75/4352)

OBJECTIVE: The aim of the present study was to evaluate the regional cerebral blood flow (rCBF) in patients with postinfectious acute cerebellar ataxia using single photon emission computed tomography (SPECT). METHODS: Five children with postinfectious acute cerebellar ataxia and five control subjects were examined. The distribution of rCBF was measured by SPECT imaging after intravenous administration of 123I-IMP (111 MBq). The rCBF ratio-defined as the ratio of rCBF in the region of interest (ROI) to that in the occipital cortex-was calculated for each cortical and subcortical ROI. The mean rCBF ratio of each region was then compared between the ataxic and control subjects. These patients and all control subjects were also evaluated using MRI. RESULTS: The rCBF ratio was significantly lower in the cerebellum of the ataxic patients than in the cerebellum of the control subjects (p<0.05). No abnormal cerebellar morphology and no abnormal signal intensities were found on MRI. CONCLUSION: 123I-IMP SPECT clearly demonstrated the decreased rCBF in the cerebellum of all patients with postinfectious acute cerebellar ataxia.  (+info)

Experimental study of lymph node auto-transplantation in rats. (76/4352)

OBJECTIVE: To observe the restoration of structure and function of auto-transplanted lymph nodes. METHODS: Inguinal lymph nodes in Spregue-Dawley (SD) rats were auto-transplanted by free implantation, or with an intact vascular pedicle, or by free transplantation with microvascular anastomosis, to the popliteal fossa where lymph nodes were removed. The observation methods included emission computerized tomographic (ECT) scanning, staining of China ink and methylthionine chloride to observe the histological changes. RESULTS: After four weeks, these vascularized nodes showed normal histological appearances and spontaneously reestablished afferent and efferent lymphatic reconnection with the surrounding lymphatic vessels. ECT lymphoscintigraphy with 99mTc-Dx showed that vascularized lymph nodes had restored their normal function. CONCLUSION: Vascularized lymph node transplantation is a useful method for draining extremity lymph edema.  (+info)

Nimodipine and perfusion changes after stroke. (77/4352)

BACKGROUND AND PURPOSE: Meta-analysis of previous trials of oral nimodipine in acute stroke has suggested a benefit when commenced within 12 hours of onset. We sought to study the effect of oral nimodipine on reperfusion after acute stroke and the relation between reperfusion and outcome. METHODS: Fifty patients with acute middle cerebral artery territory cortical infarction were blindly randomized within 12 hours of onset to either oral nimodipine (30 mg every 6 hours) or placebo. Treatment was continued for 2 weeks. Cerebral blood flow was assessed with the use of 99mTc-hexamethylpropyleneamine oxime single-photon emission CT before therapy, 24 hours later, and at 3 months. Hypoperfusion was measured by a validated volumetric technique. Neurological impairment and functional outcome were assessed with the Canadian Neurological Scale and Barthel Index, respectively. Tissue loss was measured with CT at 3 months. Four patients were excluded from analysis for technical reasons. RESULTS: Twenty-three patients received nimodipine, and 23 received placebo. In the nimodipine group, there was early reperfusion that was not maintained at outcome (P=0.01). In the placebo group, mean infarct hypoperfusion volumes showed no overall change. Nonnutritional reperfusion in nimodipine-treated patients was associated with adverse neurological (P=0.05) and functional outcome (P=0.06). There was, however, no difference in clinical outcome between the 2 groups. CONCLUSIONS: Oral nimodipine administered within 12 hours enhanced acute reperfusion, but this was largely nonnutritional. Larger studies using a shorter treatment delay are required to evaluate the clinical efficacy of nimodipine in acute ischemic stroke.  (+info)

Effects of medical therapy on outcome assessment using exercise thallium-201 single photon emission computed tomography imaging: evidence of a protective effect of beta-blocking antianginal medications. (78/4352)

OBJECTIVES: The purpose of this study was to determine whether antianginal medications modify the prognostic significance of exercise single photon emission computed tomography (SPECT) ischemia. BACKGROUND: Antianginal medications (especially beta-adrenergic blocking agents) limit exercise SPECT ischemia, but it is not known whether such medications also modify the prognostic effect of exercise SPECT ischemia. METHODS: We included 352 patients with coronary heart disease, who had exercise Tl-201 SPECT and coronary angiography, and who were initially treated medically. Survival Cox models were applied in patients for whom classes of antianginal medications taken at exercise SPECT were the same as those prescribed for follow-up (GI; n = 136), and in patients for whom new classes of antianginal medications, including beta-blockers (GII; n = 79) or not including beta-blockers (GIII; n = 113), were added for follow-up. RESULTS: During a mean 5.3+/-1.6 years of follow-up, 45 patients had cardiac death or myocardial infarction. Variables reflecting necrosis (irreversible defect extent, left ventricular ejection fraction) and those from coronary angiography provided equivalent prognostic information in the three groups. In contrast, the SPECT variable reflecting ischemia (reversible defect extent), which provided comparable prognostic information in GI (p = 0.005) and GIII (p = 0.004), lost its prognostic significance (p = 0.54) in GII, and was associated with a lower relative risk in GII than in GI or GIII (both p < 0.05). CONCLUSIONS: In patients with coronary heart disease, the introduction of antianginal medications, when including beta-blockers, appears to have a favorable effect on the deleterious prognostic effect of exercise ischemia.  (+info)

Effects of subcortical cerebral infarction on cortical glucose metabolism and cognitive function. (79/4352)

BACKGROUND: The mechanism of dementia in subcortical cerebral infarction is incompletely understood. OBJECTIVE: To determine how cognitive function is related to cortical metabolism in patients with subcortical infarction and a continuum of cognitive impairment. METHODS: We used positron emission tomography (PET) and the glucose metabolic tracer fludeoxyglucose F 18 to study 8 patients with subcortical stroke and normal cognitive function (S-CN), 5 patients with subcortical stroke and cognitive impairment (S-CI) who did not have dementia, 8 patients with subcortical stroke and dementia (S-D), and 11 controls with no cognitive impairment or stroke. A subset of patients had absolute regional cerebral metabolic rate of glucose (CMRglc) determined, while in all subjects regional tracer uptake normalized to whole brain tracer uptake was calculated. PET data were analyzed by constructing volumes of interest using coregistered magnetic resonance imaging data and correcting the PET data for atrophy. RESULTS: Global CMRglc was significantly lower in the patients with S-D than in the control and S-CN groups, with S-CI rates intermediate to those of the S-D and S-CN groups. Absolute regional CMRs of glucose were similar in the S-D and S-CI groups and in the control and S-CN groups. The regional pattern, however, showed lower right frontal regional CMRglc ratios in all stroke groups compared with the controls. There were modest correlations between performance on the Mini-Mental State Examination and whole brain CMRglc when all 4 groups were included. CONCLUSIONS: These results demonstrate that subcortical infarction produces global cerebral hypometabolism, which is related to the clinical status of the patients. In addition, specific frontal lobe hypometabolism also appears to be a feature of subcortical infarction. Taken together, both global and regional effects on cortical function mediate the production of clinical symptoms in patients with subcortical strokes.  (+info)

Quantification and visualization of defects of the functional dopaminergic system using an automatic algorithm. (80/4352)

In SPECT, the binding of radiotracers in brain areas is usually assessed by manual positioning of regions of interest (ROIs). The disadvantages of this method are that it is an observer-dependent procedure and that it may not be sensitive for assessing defects significantly smaller than the ROI. To circumvent these limitations, we developed a fully automatic three-dimensional technique that quantifies neuronal radiotracer binding on a voxel-by-voxel basis. METHODS: To build a model of normal 123I-labeled N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodophenyl) nortropane (FPCIT) binding, 17 studies of healthy volunteers were registered to the same orientation. After registration, the specific-to-nonspecific binding ratio was calculated for each voxel of the striatal volumes of interest (VOIs). The mean and SD of that binding ratio were then calculated on a voxel-by-voxel basis. For the analysis of 10 healthy volunteer studies (control group) and 21 studies of drug-naive patients with Parkinson's disease, the registration and calculation of the specific-to-nonspecific [123I]FPCIT binding ratio were performed by the same method. Subsequently, a voxel of the striata was classified as a diminished [123I]FPCIT binding ratio if its value was lower than the mean -2 x SD. For each subject, the defect size, the relative number of voxels with a diminished binding ratio and the binding ratio of the whole striatal VOIs were calculated and compared with the binding ratio as assessed by the traditional ROI method. RESULTS: The results of the automatic method correlated significantly with the results of the traditional ROI method. Furthermore, for the ipsilateral side, the automatically calculated defect size had less overlap between the patient and the control group than the traditionally calculated binding ratio. CONCLUSION: The method presented quantifies [123I]FPCIT binding ratio automatically on a voxel-by-voxel basis, by comparison with a model of healthy volunteers. We have shown that it is appropriate to use the automatic method as a replacement for the traditional manual method, which enables us to study the localized dopaminergic degeneration process in Parkinson's disease more precisely and without any inter- or intraobserver variability.  (+info)