The usefulness of 111In-labeled platelet scintigraphy in the diagnosis of patients with febrile syndrome and a nonfunctioning renal graft.

111In-labeled platelet scintigraphy was used to confirm immunological intolerance as the cause of prolonged febrile syndrome in hemodialyzed patients with a nonfunctioning renal allograft. Thirty-six patients with febrile syndrome (> 38 degrees C) and a nonfunctioning renal graft were studied. Thirteen patients were under minimal steroids (5-10 mg/day) and 23 were free of immunosuppressive therapy. A control group of 6 patients without fever and with a nonfunctioning renal graft was also included. The labeling of autologous platelets with 111In-mercaptopyridine was performed following a modified technique of Thakur. Scans were obtained at 24 and 48 hr after injection of 100-200 microCi of 111In-labeled platelets. A platelet uptake index (PUI) was calculated to evaluate the results of the scintigraphy. A PUI > 1.5 at 24 or 48 hr was considered positive and suggestive of immunological activity in the nonfunctioning renal allograft. In the study group the PUI was considered positive in 26 patients and negative in 10. In 3 patients with positive PUI, fever disappeared after steroid treatment, and transplantectomy was performed in the remaining 23. In 8 of the 10 patients with a negative PUI, fever disappeared with antimicrobial therapy. In the control group, a negative PUI was obtained in all cases. The sensitivity of PUI in demonstrating immunological intolerance of the nonfunctioning renal allograft was 93% with a specificity of 100%. Our results suggest that this new approach with 111In-labeled platelet scintigraphy may constitute a good marker for discriminating the origin of the febrile syndrome in patients with a nonfunctioning renal allograft. A positive PUI (> 1.5) strongly suggested immunological intolerance of the nonfunctioning allograft.

Hyperperfusion and early technetium-99m-HMPAO SPECT appearance of central nervous system toxoplasmosis.

Three correlative 99mTc-HMPAO brain SPECT studies were performed on an AIDS patient from the early stage of a CNS toxoplasma lesion to its resolution after specific therapy. A hyperactive area in the right parieto-occipital lobe appeared in the first SPECT study, matching the heterogeneous T2-weighted image with Gd-DTPA enhancement reported on MRI. Both studies were performed 3 days after the onset of neurological symptoms when no abnormalities were found on a CT scan. This fact can be explained by the hyperemia that occurs in the acute stage of inflammation. Three months later, along with clinical improvement under specific treatment, both MRI and brain SPECT were normal. No hypoperfusion was seen in SPECT images, probably because the necrotic phase of the toxoplasma lesion was not reached in this case.

Regional cerebral blood flow-SPECT in chronic alcoholism: relation to neuropsychological testing.

To determine the prevalence of central nervous system damage due to ethanol, we evaluated 40 asymptomatic chronic alcoholics and 20 age-matched controls. Studies included neuropsychological testing, brain 99mTc-HMPAO SPECT, and morphometric analysis by CT scan. In the qualitative analysis, 30 of the 40 alcoholics showed hypoperfused areas on SPECT scan. In the semiquantitative analysis, alcoholics exhibited significant reduction in regional cerebral blood flow (rCBF) ratio of all brain lobes compared to controls (p < 0.001). The rCBF ratio was mainly reduced in frontal lobes (65%). Only 11 alcoholics showed significant frontal lobe atrophy in the morphometric analysis; most also had abnormalities on SPECT scan. Alcoholics exhibited significant impairment of frontal tasks and visuospatial skills. Frontal test impairment was independently related to both frontal atrophy and hypoperfusion. In a group of ten alcoholics in whom another SPECT scan was performed after 2 mo of ethanol abstinence, rCBF ratio of the frontal lobes normalized in eight, without frontal atrophy. In patients without frontal atrophy, reduced rCBF ratio of the anterior portion of the frontal lobes correlated negatively with frontal test results (r = -0.6535, p < 0.001). A significant negative correlation between cerebral perfusion and the amount of ethanol consumed in the month prior to study was observed (r = -0.6289, p < 0.001). In conclusion, asymptomatic chronic alcoholics frequently showed reversible frontal lobe hypoperfusion, which is related to recent ethanol intake, reflects brain function impairment and is independent of brain atrophy.

Prefrontal and temporal blood flow in schizophrenia: resting and activation technetium-99m-HMPAO SPECT patterns in young neuroleptic-naive patients with acute disease.

UNLABELLED: This study assesses prefrontal and temporal regional cerebral blood flow (rCBF) changes in young, neuroleptic-naive schizophrenic patients with acute disease. METHODS: A selected population of 10 young, never-treated schizophrenic women with acute disease was studied by two hexamethylpropyleneamine oxime (HMPAO) brain SPECT sessions, performed 48 hr apart, both at rest and during a prefrontal activation task using the Wisconsin Card Sort Test (WCST). All patients met Diagnostic and Statistical Manual of Mental Disorders, 3rd edition-revised criteria for schizophrenia or schizophreniform disorder, were neuroleptic-naive and had acute symptoms. RESULTS: Under resting conditions, the schizophrenic group had significantly higher rCBF in the prefrontal regions, mainly in the left side and including the anterior cingulate, than did the controls. In addition, schizophrenic patients showed significant interhemispheric differences in prefrontal and posterior temporal index values at rest (left hyperfrontality and left hypotemporality). During WCST activation, the control group showed significant increases in prefrontal blood flow, whereas the schizophrenic group did not. CONCLUSION: These results support a physiologic dysfunction of the prefrontal cortex in schizophrenia that is present at the onset of the illness prior to neuroleptic treatment. Furthermore, both left hyperfrontality and left hypotemporality may indicate a brain lateralization defect in schizophrenia.

Indium-111-labeled platelets in monitoring human pancreatic transplants.

We have performed 59 111In-labeled platelet scintigraphies in 12 patients with pancreas transplant, and we have compared retrospectively the 111In platelet uptake with the graft immunological situation. A diffuse uptake in the graft was seen in five of six patients with pancreatic rejection. The scans became positive before changes in biochemical tests were detected. No 111In platelet uptake was seen in five of seven normally functioning grafts. Two cases of venous thrombosis and two perigraft hematomas appeared like a focal 111In platelet accumulation. Indium-111-labeled platelet scintigraphy can be a useful method for monitoring pancreas transplants. It may be helpful in the early detection of pancreatic allograft rejection and in the differential diagnosis between this and other complications such as thrombosis or hematomas.

Evaluation of algorithms for the registration of 99Tcm-HMPAO brain SPET studies.

Five functions of merit were used for the registration of 99Tcm-HMPAO brain SPET studies. The correlation coefficient (COR), the stochastic sign change (SSC), the standard deviation of ratios (SDR), the sum of the absolute differences (SAD) and a new function based on a local correlation coefficient (LOC) were tested in the registration of photic neuroactivation (ACT), epilepsy (EPL) and Wada (WAD) SPET studies. The comparison included simulated and real studies. The translation error in registration was 0.1 +/- 0.1 pixels (mean +/- S.D.) for all functions of merit for the complete set of simulated studies (10 runs for each ACT, EPL and WAD). For rotation, LOC yielded the best results with a mean error of 0.3 +/- 0.2 degree and a maximum error of 0.6 degree. Slightly higher errors were found with SAD (0.4 +/- 0.2 degree, maximum 1.0 degree) and COR (0.5 +/- 1.0 degree, maximum 1.0 degree). The highest errors were found with SDR (0.8 +/- 1.0 degree, maximum 4.8 degrees) and SSC (0.8 +/- 1.1 degrees, maximum 4.7 degrees). The results obtained from five real studies of ACT, of EPL and of WAD were in agreement with the findings from the simulated studies, thus confirming the robustness of LOC, SAD and COR for the registration of 99Tcm-HMPAO brain SPET studies.

Three-dimensional realignment of activation brain single-photon emission tomographic studies.

Two methods for 3D realignment of activation brain single-photon emission tomographic (SPET) studies are analyzed. The first is based on principal axes transformation (PAT). The second uses the results of the first method as initial values to start a least-squares iterative process (LS) to search for the maximum value of the correlation function. Both methods were tested with simulated and real studies. The results of the PAT method showed a maximum translation error of 0.3 +/- 0.1 pixels and a rotational error of 1.2 +/- 0.7 degrees in a total of 100 runs. For the LS method these errors were 0.2 +/- 0.1 and 0.6 +/- 0.3. The realignment for 34 real studies was assessed by three expert observers. The alignment was found to be satisfactory in all cases for the LS method, and in 18 cases (53%) for the PAT method. From the results we conclude that a combination of both methods allows the accurate realignment of SPET neuroactivation studies.

Regional cerebral blood flow pattern in normal young and aged volunteers: a 99mTc-HMPAO SPET study.

The aim of this study was to investigate the normal pattern of regional cerebral blood flow (rCBF) distribution in normal young and aged volunteers using technetium-99m hexamethylpropylene amine oxime (99m-Tc-HMPAO) as a tracer. The region brain perfusion of young and aged subjects was compared, especially regarding rCBF differences due to age and gender, and interhemispheric rCBF asymmetries. Sixty-eight right-handed normal volunteers - 40 young (mean age 29. 5+/-6.3 years) and 28 aged (mean age 71.2+/-4.3 years) - were included in the study. rCBF was estimated on the basis of a semiquantitative approach by means of a left/right index and two region/reference ratios, using the cerebellum and the whole brain activity as references. A good correlation between these two region/reference ratios was found (P<0.005 in all cerebral regions). The highest rCBF ratios corresponded to the cerebellum, followed by the occipital lobe. The remaining cortical regions (temporal, parietal, frontal and basal ganglia) showed slightly lower values. The white matter showed rCBF ratios substantially lower than the grey matter. In neither young nor aged subjects were significant rCBF differences between the genders found in any of the two region/reference indices employed. Aged subjects showed significantly lower rCBF ratios than young subjects in the left frontal lobe and in the posterior region of the left temporal lobe. In both young and aged subjects, lower perfusion was found in the left hemisphere, except for the white matter region in both age groups and the frontal lobe in the young subjects. Aged subjects presented a slightly higher interhemispheric asymmetry in the frontal lobe. However, interhemispheric asymmetry was minimal (-1. 01% to 3.14%). Consequently, a symmetrical rCBF distribution can be assumed between homologous regions, independent of age.