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Purpose: The purpose of this study is to determine the value of Tc-99m HMPAO SPECT in the diagnosis of the dementias, with particular reference to Alzheimer disease., Materials and Methods: Tc-99m HMPAO was used with a 3-camera scanner to produce 5 sets of sectional images of the brain. Diagnosis was made by a physician blinded to the clinical diagnosis. Results in 49 subjects were ultimately compared with neuropathologic study of the brain at autopsy., Results: Sensitivity = 86.7% (68.4-95.6%, 95% confidence interval [CI]), specificity = 89.5% (65.5-98.2% CI), positive predictive value = 92.9% (75.0-98.8% CI), negative predictive value = 81% (57.4-93.7% CI), accuracy = 87.8% (74.5-94.9% CI), likelihood ratio = 8.23% (7.09-9.57% CI)., Conclusions: Comparison is made with several other SPECT and PET series with histopathologic correlation. Brain blood flow SPECT is useful in the diagnosis and differential diagnosis of the dementias.

The characterization of frontotemporal lobar degeneration (FTLD) is complicated and not widely recognized. Connected language measures (ie, discourse) and functional neuroimaging may advance knowledge specifying early distinctions among frontal dementias. The present study examined the correspondence of discourse measures with (1) clinical diagnosis and (2) single photon emission computed tomography (SPECT) imaging. Nineteen subjects were selected from Alzheimer's Disease Center (ADC) participants if they were diagnosed with early-stage frontotemporal lobar degeneration and also underwent single photon emission computed tomography and discourse evaluation. First, clinical diagnoses given by specialists at an Alzheimer's Disease Center were compared with the discourse-based diagnostic profiles. Secondly, compromised brain regions that were predicted from discourse profiles were compared with SPECT findings. Results revealed a significant correspondence between the ADC diagnosis and the discourse-based diagnoses. Also, the discourse profiles across frontotemporal lobar degeneration subtypes were consistently associated with distinctive patterns of SPECT hypometabolism in the right frontal, left frontal, or left temporal lobes. These findings suggest that discourse methods may be systematized to provide an efficient adjunct measure beyond the traditional word and sentential level measures. Objectifying complex language performance may contribute to early detection and differentiation among frontotemporal lobar degeneration variants because consensus in the literature states that language is a core disturbance of frontotemporal lobar degeneration.

Unlabelled: Occipital lobe perfusion defects have been identified on regional cerebral blood flow (rCBF) SPECT scans of adolescent children and young adults with major depressive disorder (MDD). We reinvestigated a series of rCBF SPECT scans obtained several years ago on drug-naive children with a clinical diagnosis of MDD and on healthy children., Methods: To test whether visually apparent abnormalities in rCBF constitute statistically significant differences between patients, given the relatively small sample sizes, we applied the technique of statistical parametric mapping (SPM)., Results: Two groups of patients were identified: 8 with significant posterior flow deficits in the occipital cortex (Brodmann's areas 18 and 19), usually symmetric, and best visualized on paramedian sagittal sections, and 13 without obvious occipital perfusion deficits but with anterior rCBF deficits in a pattern often described in the literature, attaining statistical significance in the right frontal region. Other localizations in the left frontal and bilateral prefrontal regions did not attain significance, but each localization contained statistically significant maxima (z scores). The scan findings of all 18 healthy children were normal., Conclusion: With the aid of SPM, 2 groups of children with significantly different rCBF behavior were identified. The reason for this difference is not known but should be investigated to determine its possible significance to patients with MDD.

Purpose: To evaluate single photon emission computed tomographic (SPECT) imaging of regional cerebral blood flow in the diagnosis of Alzheimer disease (AD) and the differential diagnosis of the dementias., Materials and Methods: Regional cerebral blood flow SPECT was performed with inhaled xenon-133 in 261 patients and with injected technetium-99m hexamethyl-propyleneamine oxime (HMPAO) in 162 patients with possible dementia. In 16 patients, both agents were used in 1 day. SPECT images obtained in elderly healthy control subjects (with Xe-133 in 15, with Tc-99m HMPAO in 14) were available. In each patient without AD, further classification of disease was attempted. Histopathologic correlation was available in 54 patients (with autopsy in 51, with biopsy in three)., Results: SPECT diagnoses were true-positive in 37, true-negative in eight, false-positive in three, and false-negative in six patients. Sensitivity was 86% (37 of 43; 95% confidence limits = .72, .95); specificity, 73% (eight of 11; confidence limits = .39, .94); positive predictive value, 92% (37 of 40; confidence limits = .80, .98); and negative predictive value, 57% (eight of 14; confidence limits = .29, .82)., Conclusion: Regional cerebral blood flow SPECT may assist in the early and late diagnoses of AD and in the differential-diagnosis of the dementias when there is a complicated or confusing clinical picture.

A study of 76 consecutive xenon-133 SPECT studies of regional cerebral blood flow was undertaken to determine the frequency of various patterns of blood flow in cases of clinically diagnosed probable and possible Alzheimer's disease. The reference tomographic section was a slice 6 cm above and parallel to the canthomeatal line. With the use of this technique, the "classic" finding of bilateral temporoparietal (TP) flow reductions as the sole abnormality occurred in only 28% of cases. Bilateral TP reductions accompanied by bilateral or unilateral frontal flow reductions were nearly as common (24%), and other patterns accounted for the other 48% of cases.

It is important to determine preoperatively which patients can tolerate permanent occlusion of a cervical internal carotid or cerebral artery when such a procedure may be necessary to treat cerebrovascular or neoplastic lesions. Here we report our experience in combining temporary intra-arterial balloon occlusion with concomitant cerebral blood flow imaging in preoperative evaluation of such patients. Forty-two patients with a variety of cerebrovascular and neoplastic lesions underwent trial balloon occlusion of an internal carotid or intracerebral artery. Eight patients developed both neurologic symptoms as well as brain perfusion defects during trial occlusion. Nine others developed only perfusion defects. The remainder were asymptomatic and had negative scans. Brain blood flow imaging during intra-arterial balloon occlusion identified 17 patients potentially at risk for developing postsurgical ischemic deficits. Treatment alternatives to acute arterial sacrifice were developed for these patients.

Purpose: To describe the technique of using SPECT brain blood flow imaging to identify patients at risk for having strokes after balloon or surgical ligation of an internal carotid artery., Patients and Methods: 29 patients underwent temporary balloon occlusion of the internal carotid artery and blood flow imaging studies were obtained prior to sacrifice of the vessel; 11 internal carotid arteries were indeed sacrificed and form the basis of our study. Follow-up of these patients ranged from 3 to 65 days., Results: Three groups emerged: group I, patients with symptoms during occlusion and an abnormal blood flow study (one patient); group II, patients with no symptoms during the occlusion but with an unequivocally abnormal blood flow study (two patients); group III, patients without symptoms during occlusion and a normal or slightly abnormal blood flow study (eight patients)., Conclusion: Carotid sacrifice without initial and temporary balloon occlusion is unnecessarily risky. Imaging of blood flow in the brains of these patients can further improve the safety of occlusion procedures in the internal carotid artery.

Regional CBF (rCBF) was measured quantitatively using the inert-gas washout technique with xenon-133 and single-photon emission computed tomography. Tomographic data were reconstructed by filtered back projection, and flow was calculated according to the double-integral method. Ninety-seven subjects ranging in age from 20 to 59 years received a single examination; eight of these received a second examination within 1 h of the first; seven others received a second examination separated from the first by 1-10 days. Transverse-section images were obtained at 2, 6, and 10 cm above and parallel to the canthomeatal line (CML). Cortical gray matter flows were obtained from 12 brain regions in the slice 6 cm above the CML, and cerebellar and inferior cerebral gray matter flows were obtained from 4 regions in the slice 2 cm above the CML. Mean gray matter flow was 72 +/- 12 ml/min/100 g, with highest flows in the parietal lobes and visual cortex. No significant differences in rCBF occurred when a second study followed the first by 30 min to 10 days. Right-sided rCBF was slightly higher than left in all regions except frontal and parietal lobes where there was no difference. Flow was higher in women than in men and declined mildly with age for both sexes (slope = -0.33 ml/min/100 g/year; p less than 0.05).

Antihypertensive therapy significantly reduces cardiovascular morbidity and mortality in the rapidly growing population of elderly patients. However, the desire to treat more of these patients is dampened by the concern that a reduction in blood pressure may compromise cerebral blood flow, causing untoward consequences. This study evaluated the therapeutic effect of titrated doses of prazosin, an alpha-adrenergic blocking agent, on systemic blood pressure and cerebral blood flow in elderly patients with chronic stable hypertension. Prazosin alone or co-administered with hydrochlorothiazide significantly lowered mean systolic and diastolic blood pressures in 31 elderly hypertensive patients. At the same time, however, there was no significant change in cerebral blood flow, which was measured in eight patients. Neither harmful biochemical changes nor treatment-related adverse effects were observed in any patients. Prazosin therapy alone or in combination with low-dose diuretic therapy was effective in the treatment of hypertension in this elderly population. Furthermore, blood pressure reduction with prazosin therapy was accomplished without compromising cerebral blood flow and without unfavorably altering lipid profiles.

A single-photon dynamic computer-assisted tomograph (DSPECT) has been built and is currently being used to evaluate regional cerebral blood perfusion in patients and volunteers. A computer simulation of the system was created to analyze the effects of data collection, Poisson noise, attenuation compensation, and the reconstruction technique now employed in the DSPECT. Several methods of attenuation compensation were used to generate perfusion images from both ideal and noisy data. The results indicate that the mean perfusion is calculated to within 10.4% accuracy for all perfusion rates in a region of interest if attenuation correction is used. Without attenuation correction, perfusions are underestimated by as much as 27%. The three correctors tested have different effects on the calculated perfusion value, depending on the location of the region of interest in the picture. The algorithm introduces random noise that is proportional to both the random error in the input data and the perfusion rate. Air-curve delay errors result in inaccuracies in the final perfusion picture that are proportional to perfusion rate. Physiological values (0.8-1.5) of the partition coefficient cause overestimation of both gray (0-34%) and white (7-67%) matter perfusion values. Compton scatter and collimator effects were not addressed in this study.

A 65-year-old man with well-defined crossed aphasia secondary to right cerebral infarction 10 years previously was studied for current language and cognitive abilities and regional cerebral blood flow (rCBF) during cognitive activation measured by single-photon emission tomography (SPECT). Reversed hemispheric lateralization was demonstrated by qualitative aspects of the patient's constructional deficits, dominant parietal lobe signs, and absence of the neglect syndrome. Language activation procedures during SPECT produced focal increases in rCBF to both frontal lobes with a phoneme detection task and to right temporal and parietal lobes with a math task. The authors stress the complexities of assessing brain/language mechanisms in vivo and demonstrate variabilities in rCBF during language activation dependent on task selection.

Using a single-photon emission computed tomographic scanner (SPECT) the authors determined regional cerebral blood flow (rCBF) with inhaled xenon-133, a noninvasive procedure. Studies were performed in 40 normal individuals, and these were compared with rCBF determinations in 51 patients with seizure disorders. Although positive results were obtained in 15 of 16 patients with mass lesions, the group of principal interest comprised 25 patients suffering from "temporal lobe" epilepsy. Only one of these had a positive x-ray computed tomogram, but 16 had positive findings on rCBF study. These findings included increased local blood flow in the ictal state and reduced flow interictally.

A common cause of dementia in late midlife and old age is Alzheimer disease (AD), which affects more than one in 20 individuals over the age of 65. Past studies of regional cerebral blood flow (rCBF) in patients with AD here suggested blood flow abnormalities, but findings have differed. We have studied 37 patients diagnosed as having AD with inhalation and washout of 133Xe and single-photon emission computed tomography (SPECT), obtaining evidence of abnormal rCBF patterns in 19. Flow reductions were most common in the temporoparietal regions and were occasionally found in the frontal areas. Investigators using positron-emission tomography (PET) have identified similar findings with respect to rCBF and regional oxygen, glucose, and protein metabolism. The SPECT determination of rCBF, which gives information similar to that provided by PET, may assume importance in the diagnosis of AD and in the differential diagnosis of the dementias.

Regional cerebral blood flow (rCBF) was evaluated in 15 normal, healthy volunteer control subjects before and after the administration of 1 g acetazolamide (ACZ) using a rotating four-detector single-photon emission computed tomograph (SPECT). ACZ, a carbonic anhydrase inhibitor, is a cerebral vasodilator. RCBF values in mL/minute/100 g were derived within eight cortical regions of interest (ROI), and from the whole slice as an expression of whole brain blood flow (WBF). ROI/WBF ratios were established for each ROI in each of the 15 subjects for both pre-ACZ and post-ACZ studies. ACZ produced a 30% +/- 17% increase in WBF. Studies were done in random order, with nine subjects undergoing the post-ACZ study first, and six the pre-ACZ, or baseline, study first. Statistical analysis showed no significant difference in any ROI that might be caused by sequence of test procedures. Ratios were then examined to determine whether rCBF elevation was proportionate in all ROI in all subjects. No significant difference was found in any ROI except for the left parietal, for which marginally significant change was identified. Subjects also were examined for possible age and sex differences in ACZ response, and no differences were found.

Sixty-two patients with radiographically proven intracranial arteriovenous malformations underwent preoperative regional cerebral blood flow measurement with 133Xe single-photon emission computed tomography. Contralateral regions of hypoperfusion were detected in all cases. Steal severity was assessed according to the contralateral steal index [ISteal(c)]. ISteal(c) was greater than 0.7 (severe) in 22 (35%), 0.7-0.8 (intermediate) in 18 (29%), and greater than 0.8 (mild) in 22 (35%). ISteal(c) was more frequently severe or mild in females and more often intermediate in males (p less than 0.05). Hyperemic complications were encountered more frequently in patients with intermediate ISteal(c) (p = 0.086). An unfavorable outcome was associated with less severe contralateral steal (p = 0.12). A detailed clinical, radiographic, and hemodynamic profile may help to preoperatively identify patients at high risk for a poor surgical outcome.

Intracranial arteriovenous malformations (AVMs) are high flow shunts that may jeopardize the perfusion of adjacent tissue. Clinical and radiographic data from 62 patients were analyzed to determine their relationship to the severity of steal measured by single photon emission computed tomography (SPECT). The ipsilateral steal index [ISteal(i)] was determined by dividing regional cerebral blood flow (rCBF) values within hand-drawn regions of hypoperfusion in the ipsilateral hemisphere by total brain flow, which was calculated as the average rCBF of each hemisphere. Of the patients, 40% were less than 30 years of age, 45% were 30 to 50 years old, and 15% were over 50. Forty-eight per cent presented with hemorrhage and 34% presented with progressive deficits. There was angiographic steal in 37%, and postoperative hyperemic complications developed in 21%. All patients had ipsilateral regions of hypoperfusion. The ISteal(i) was less than 0.7 in 23 (37%), 0.7 to 0.8 in 20 (32%), and greater than 0.8 in 19 (31%). The ISteal(i) was significantly less severe in the patients over 50; 78% of these patients had an ISteal(i) of greater than 0.8 (P less than 0.01). A history of hemorrhage was associated with less severe steal than that in patients who had not bled (P = 0.088). Patients presenting with a history of progressive deficits had increased severity of steal compared with those without progressive deficits (P less than 0.05). A trend toward decreased severity of steal was noted in patients with unfavorable outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional cerebral function and blood flow can be imaged using isopropyl[123I]iodoamphetamine (IMP), or 133Xe (DSPECT), respectively. Both of these essentially non-invasive, quantitative, methods are suitable for many nuclear medicine laboratories. This study assessed the in vivo information about intracerebral disease provided by IMP and DSPECT techniques to determine the optimal diagnostic use of these modalities. Single photon emission computed tomograms of 53 subjects were acquired using similar displays for IMP and DSPECT data. Lobar tracer distributions were graded by three experienced observers and analyzed using a kappa statistic to eliminate chance agreements. Overall, both IMP and DSPECT had similar patterns. However, while similar, one or the other technique often displayed abnormalities not present on both. Although technical factors may account for some differences between the modalities, a case of arteriovenous malformation proves that discordant findings can result directly from tracer localization properties. Thus at least some discordances provide truly complementary diagnostic information lacking in either single study taken alone.

Regional cerebral blood flow (rCBF) may be measured with a single-photon-emission computed tomograph (SPECT) after inhalation of xenon 133. Our SPECT studies of rCBF in a group of 18 patients with seizure disorders, when compared with studies in 32 normal control subjects, have shown enhanced flow to an active seizure focus and ischemia of brain areas in certain subjects between seizures. Thus, SPECT determination of rCBF has demonstrated a number of findings recently observed with positron-emission tomography and may become a useful modality in the study of patients who have epilepsy.

Eleven patients with angiographically and/or pathologically proved arteriovenous malformations (AVMs) were studied using dynamic, single-photon-emission computed tomography (DSPECT). Quantification of regional cerebral blood flow in structurally normal areas remote from the AVM disclosed areas of decreased flow compared with normal controls in eight of 11 patients examined. Areas of hypoperfusion correlated with altered function as manifested by epileptogenic foci and impaired cognitive function. Dynamic, single-photon-emission computed tomography provides a noninvasive technique to monitor quantitatively hemodynamic changes associated with AVMs. Our findings suggest that such changes are present in the majority of patients with AVMs and that they may be clinically significant. The potential application of regional cerebral blood flow imaging by DSPECT in the management of patients with AVMs is discussed.

Regional cerebral blood flow (rCBF) was assessed in 35 patients with possible or probable Alzheimer's disease (AD) and in 16 patients known to have had at least one stroke. Patients were evaluated before and after the administration of 1 g acetazolamide (ACZ) by means of a rotating four-detector single-photon emission computed tomograph (SPECT) and inhaled Xe-133. RCBF values in mL/minute/100 g were derived from eight cortical regions of interest (ROI), and from the whole transverse section as a measure of whole brain flow (WBF). ROI/WBF ratios were calculated for each ROI in paired determinations done before and 15 minutes after the administration of ACZ. Results were compared with those previously obtained in a study of 15 normal, healthy volunteer subjects. ROI/WBF ratios greater than 2 standard deviations (SD) below the mean for a given ROI in the normal group were regarded as probably abnormal, whereas ratios greater than 4 SD below the mean were considered definitely abnormal. After ACZ administration, the number of ROI greater than 2 SD below the normal mean decreased significantly in the AD group and was unchanged in the stroke patients. However, the number of ROI/WBF ratios greater than 4 SD below the normal mean fell in the AD group and rose in the stroke group, with the difference in behavior highly statistically significant. Thus, the response of low-flow areas to ACZ differs in AD and in stroke, which could be of ultimate diagnostic significance.

Regional cerebral blood flow was measured with xenon-133 inhalation single photon emission computed tomography in a patient who developed a neurological deficit after carotid ligation. Hemispheric hypoperfusion was noted in resting studies and impaired vasoreactivity was suggested by lack of symmetrical flow augmentation after acetazolamide administration. Because of progressive neurological deterioration, an extracranial-intracranial bypass was performed. After prompt neurological improvement, repeat cerebral blood flow measurements at 1 and 9 weeks postoperatively confirmed improvement in resting flow and vasoreactivity. It is possible that decreased cerebrovascular reserve implied by measurements of vasoreactivity can identify patients who will benefit from surgical revascularization.

Arteriovenous malformations (AVMs) dramatically alter normal cerebral circulatory dynamics. Clinical and radiographic data from 62 patients were analyzed to determine their impact on total brain blood flow (TBF) measured by single-photon emission computed tomography. 48% of patients presented with hemorrhage and 34% with progressive deficits. 37% had angiographic steal and 21% developed postoperative hyperemic complications. 40% were under 30 years old, 45% were between 30 and 50 years of age, and 15% were over 50. TBF was less than 70 ml/100 gm/min in 32% of patients, between 70 and 84 ml/100 gm/min in 40%, and greater than 84 ml/100 gm/min in 27%. Female patients had higher TBF than males; 42% of females but only 17% of males had values greater than 84 ml/100 gm/min (p less than 0.05). A trend toward decreased TBF with advancing age was noted. Intracranial hemorrhage was associated with lower TBF; 47% of patients with hemorrhage and 19% of those without had TBF of less than 70 ml/100 gm/min (p less than 0.05). 89% of patients with AVMs less than 5 cm in diameter had TBF of less than or equal to 84 ml/100 gm/min, and 65% of those with larger AVMs had similarly low flows (p less than 0.05). A trend toward lower TBF was observed in patients with unfavorable outcomes.