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Functional neuroimaging studies in humans are common worldwide. In order to determine with more accuracy both morphometric parameters and volume of the primary auditory cortex (PAC), we studied both right and left hemispheres in human control brains. Twelve hemispheres were systematically sectioned orthogonal to the anterior-posterior commissures (ac-pc line). Serial sections of the complete temporal lobe at 50 microm were obtained and stained with thionin (12 hemispheres) for cytoarchitectonic analysis. Four hemispheres were stained with the neuronal marker parvalbumin, a marker of primary sensory cortices. Morphometric analysis of the thionin-stained sections included size and shape factors as well as volume estimation using the Cavalieri method. Primary auditory areas extended for an average of 24 mm (twelve 2 mm apart sections); volume estimates determined by the Cavalieri method was 857+/-213 mm3 with a range of 658 mm3. The left primary auditory cortex was 7% greater than the right auditory cortex, without significant differences between hemispheres. The size and form of morphometric parameters obtained from each sampled section also revealed scarce differences between hemispheres, and the tendency to irregularity and ellipsoidity was more marked in the left hemisphere. No differences in size and form between right and left hemispheres were determined in our study. Morphometric analysis are of value in functional studies, specially those using non-invasive and lower resolution techniques such as Single Photon Emission Computed Tomography (SPECT).

Flicker stimuli of variable frequency (2-90 Hz) elicit a steady-state visual-evoked response (SSVER) in the electroencephalogram (EEG) with the same frequency as the stimulus. In humans, the amplitude of this response peaks at approximately 15 Hz, decreasing at higher stimulation frequencies. It was not known whether this peak response corresponds to increased synaptic activity in the visual cortex or to other mechanisms [for instance, the temporal coherence (phase summation) of evoked responses]. We studied the SSVER in 16 normal volunteers by means of visual stimulation at 14 different frequencies (from 5 to 60 Hz) while recording the EEG. In nine subjects of the group, we measured regional cerebral blood flow (rCBF) with positron emission tomography (PET)-H2(15)O at rest and during visual stimulation at five different frequencies: 5, 10, 15, 25, and 40 Hz. We confirmed that the amplitude of the SSVER in occipital regions peaks at 15 Hz stimulation. Applying to the PET rCBF data a contrast weighted by the amplitude of the SSVER, we determined that the primary visual cortex rCBF follows an activation pattern similar to the SSVER. This finding suggests that the amplitude of the SSVER corresponds to increased synaptic activity, specifically in Brodmann's area 17. Additionally, this study showed that visual stimulation at 40 Hz causes selective activation of the macular region of the visual cortex, and that a region in the dorsal aspect of the Crus I lobule of the left cerebellar hemisphere is activated during repetitive visual stimulation.

We used functional brain imaging with positron emission tomography (PET)-H2 15O to study a remarkable neurophysiological finding in the normal brain. Auditory stimulation at various frequencies in the gamma range elicits a steady-state scalp electroencephalographic (EEG) response that peaks in amplitude at 40 Hz, with smaller amplitudes at lower and higher stimulation frequencies. We confirmed this finding in 28 healthy subjects, each studied with monaural trains of stimuli at 12 different stimulation rates (12, 20, 30, 32, 35, 37.5, 40, 42.5, 45, 47.5, 50, and 60 Hz). There is disagreement as to whether the peak in the amplitude of the EEG response at 40 Hz corresponds simply to a superimposition of middle latency auditory evoked potentials, neuronal synchronization, or increased cortical synaptic activity at this stimulation frequency. To clarify this issue, we measured regional cerebral blood flow (rCBF) with PET-H2 15O in nine normal subjects at rest and during auditory stimulation at four different frequencies (12, 32, 40, and 47 Hz) and analyzed the results with statistical parametric mapping. The behavior of the rCBF response was similar to the steady-state EEG response, reaching a peak at 40 Hz. This finding suggests that the steady-state amplitude peak is related to increased cortical synaptic activity. Additionally, we found that, compared with other stimulation frequencies, 40 Hz selectively activated the auditory region of the pontocerebellum, a brain structure with important roles in cortical inhibition and timing.

Deficits in sustained attention have been frequently described in schizophrenia. The neuroanatomical basis reported previously have included altered levels of activation in cingulate and prefrontal cortex, but the contribution of further regions remains unclear. We explored the full neuroanatomy underlying the sustained attentional deficits observed in naïve schizophrenics compared with controls. Participants included 10 controls and 11 patients. The experimental design included rest, auditory stimulation using clicks, and two counting tasks. Subjects were instructed to mentally count the clicks, and then to count forward at the same frequency they heard previously when listening to the clicks. Relative cerebral blood flow (relCBF) was measured by means of PET (15)O-water. Differences were observed between both groups at superior temporal cortex, superior parietal gyrus, and cerebellum during tasks requiring listening. During all counting conditions, additionally to supplementary motor area (SMA), dorsolateral prefrontal cortex (DLPCF), precentral gyrus, cingulate, cerebellum, and inferior parietal (IP) gyrus, patients engaged other frontal structures including inferior, medial, and superior frontal areas. When counting with no auditory stimulation (C; requires components of working memory and time estimation), significant differences were observed in the level of activation of frontal and IP regions. Our naïve patients presented abnormal activation of auditory associative pathways. They failed to activate prefrontal and parietal regions at a similar level during tasks requiring increased cognitive effort, and they required a higher activation of inferior frontal regions to properly respond to cognitive demands., (Copyright 2002 Wiley-Liss, Inc.)

The basal ganglia are part of a neuronal network organized in parallel circuits. The "motor circuit" is most relevant to the pathophysiology of movement. Abnormal increment or reduction in the inhibitory output activity of basal ganglia give rise, respectively, to poverty and slowness of movement (i.e., Parkinson's disease) or dyskinesias.

Periodic limb movements in sleep (PLM) have been associated with several degenerative disorders and other focal or diffuse diseases. We present a patient with clinical diagnosis of corticobasal degeneration and sleep complaints, in whom video recording and polygraphic study confirmed the presence of right PLM. The unilaterality of the movements and the positron emission tomography findings (hypometabolism in the left frontoparietal, basal ganglia, and thalamic areas) suggest that the loss of inhibitory descending central pathways, with origin in the cortex or basal ganglia, may be involved in the pathogenesis of PLM., (Copyright 2001 Movement Disorder Society.)

To evaluate the differences in the functional activity of the auditory cortex between normal hearing and profound deafness, a perfusion single photon emission tomography (SPECT) study was designed. SPECT stereotaxic localisation of the auditory cortex was previously validated in 2 brains by means of an anatomical study of the macroscopic localisation and cytoarchitecture of the auditory cortex. Additionally, 15 controls with normal hearing and 30 patients with profound bilateral deafness were scanned using external anatomical point sources (glabela, ineon) for stereotaxic location of the auditory cortex. The normal controls were scanned in auditive deprivation and, in 10 cases, during a monoaural tonal stimulation. Cerebral blood flow relative to cerebellum (relCBF) was assessed in the auditory cortex. The anatomical study showed that mean differences between the true auditory cortex size and the measured SPECT value were less than 2.5 mm. Nevertheless, only the caudal aspect of this area corresponded to the primary auditory cortex in the cytoarchitectonic study. During tonal stimulation, control subjects presented a significant increase of relCBF in the auditory cortex bilaterally, with significant differences in the asymmetry index (contralateral to the side of stimulation). The relCBF in the auditory cortex of controls in deprivation conditions was significantly higher than in deaf patients. There were no significant differences between groups of deaf patients, however the highest values were seen after cochlear implant. SPECT is a suitable method for studying changes in auditory cortex activity relative to different functional conditions, with a possible role in cochlear implant candidates in predicting the future benefit of the implantation.

Unlabelled: Thirty-four patients with a probable Alzheimer's Disease (AD) (mild AD = 16; moderate AD = 18) and 12 matched controls were evaluated using semiquantitative SPECT-99mTc-HMPAO and neuropsychological tests (CERAD)., Results: Both temporal hypoperfusion (p < 0.01) and memory tests (p < 0.001) made it possible to differentiate the controls from mild AD patients. In these patients, significant correlations (p < 0.05) were also found between: 1) delayed recall test/temporal hypoperfusion, 2) learning memory test/temporoparietal and frontal hypoperfusion and 3) visual constructive praxis/posterior temporal hypoperfusion. In contrast to mild AD, moderate AD patients showed higher temporal (p < 0.01) parietal and frontal (p < 0.05) hypoperfusion along with worsening of praxis (p < 0.001) and memory tests (p < 0.05)., Conclusions: SPECT imaging and neuropsychology evaluation can distinguish controls from AD patients with mild an moderate grades of dementia, showing a strong correlation from the early stages of AD.

In order to evaluate the relationship between perfusion brain SPECT and specific cognitive functions as well as the possible influence of the illness severity on them, 34 patients clinically diagnosed as probable Alzheimer disease (AD) and 12 elderly controls were studied. AD patients were subdivided according to severity as 16 mild AD and 18 moderate AD. Neuropsychological battery of CERAD protocol and a semiquantitative analysis of 99mTc-HMPAO-SPECT images was carried out in all groups. With regard to the regions affected in SPECT, involvement of temporo-parietal cortex were of most use in discriminating between AD patients and controls, but only temporal hipoperfusion distinguished mild disease from controls. Memory and praxis impairment correlated with temporo-parietal perfusion. Frontal involvement seemed to be a discriminator of disease progression, nevertheless, a significant correlation was present between memory and frontal hipoperfusion indicating the diffuse and sometimes heterogeneous distribution of AD pathology.

Objective: The aim of this study is to evaluate the contribution of the Cedars-Sinai quantification tomographic method (CS) in the diagnosis and localization of ischemic areas in coronary artery disease (CAD) and to optimize the threshold values proposed by CS., Patients and Methods: Fifty patients with clinical suspicion of CAD performed a maximal stress test by cycloergometer; thallium myocardial tomographic images were obtained; applying the CS program afterwards. The sensitivity and specificity variations obtained by changing the criteria for extent of myocardial hypoperfusion (range 1% to 100%) were used to calculate the new thresholds (CS-I), using the results of coronariographic studies as a reference. The data determined by qualitative analysis were compared with that obtained by quantitative analysis by means of CS and CS-I using coronary angiography as the standard of reference., Results: The coronary angiography showed coronary disease in 37 patients. The sensitivity for the diagnosis of CAD was superior using CS (97%) at the expense of low specificity (15%) which nevertheless improved with CS-I (54%). For the location of CAD, the visual analysis was statistically significant (p < 0.05) in the left anterior descending and right coronary arteries, CS being superior in the diagnosis of 3 vessel disease., Conclusions: The quantification of tomographic studies with thallium by means of CS needs a readjustment of the thresholds. The tested values (CS-I) improved the CS results, although they require prospective validation. Quantitative study permits the confirmation of visual findings, being a complementary method that can be rapidly and easily interpreted, although it is not recommended as a single technique for the diagnosis of coronary disease.

Introduction and Objectives: The purpose of this study is to show our experience in clinical dynamic cardiomyoplasty., Patients, Materials and Methods: Six patients with end-stage heart failure and 2 patients with left ventricular aneurysm underwent dynamic cardiomyoplasty using the latissimus dorsi muscle. The latissimus dorsi was electrically conditioned before the procedure through a lead placed under local anesthesia and connected to an external cardiac pace-maker. Surgical technique--including dissection of the latissimus dorsi and encircling of the ventricles with the muscle flap--was performed in general terms as described at the Broussais Hospital. In the first 3 patients a bipolar lead connected to a single impulse generator was used. In the other 5 patients a train of impulses cardiomyostimulator was used. Changes in systolic function were studied through Doppler-echocardiography and radionuclide studies. Changes in diastolic function were evaluated through E wave velocity and deceleration time., Results: Mean follow up was 9 +/- 5.7 months. No early deaths were recorded. One patient underwent emergency surgery, one week after the procedure, because of a tear of the patch used to close the wall defect after left ventricular aneurysm resection. In 2 patients a subcutaneous serous collection secondary to muscle dissection was evacuated. One patient died due to a stroke 4 months after the procedure. Another patient died after an unsuccessful coronary transluminal percutaneous angioplasty 11 months after the procedure. An improved functional class was observed in all patients. No changes in systolic function were observed after surgery when the cardiomyoestimulator was turned-off either with echocardiography (26.7 +/- 8.6 vs 24.8 +/- 5.8% [NS]) or radionuclides (24.5 +/- 9.5 vs 20.2 +/- 8.3% [NS]). When the cardiomyostimulator was turned-on a statistically significant increase of the left ventricular ejection fraction was observed either with echocardiography (24.8 +/- 5.8 vs 37 +/- 10.3%; p < 0.05) or radionuclides (20.2 +/- 8.3 vs 33.3 +/- 12.2%; p < 0.05). This significant increase of the ejection fraction has been observed in subsequent studies. Nevertheless the differences when the cardiomyostimulator is turned-on and turned-off have decreased several months after the procedure. A significant increase of the left ventricular outflow velocity (cm/seg) was observed when the generator was turned-on (57.7 +/- 20.4 vs 75.1 +/- 17.8%; p < 0.01). A significant increase of the dP/dt (mmHg/seg) was observed when the generator was turned-on (706.3 +/- 291.5 vs 592.6 +/- 181.6%; [NS]). No significant changes were observed on E wave velocity. A significant decrease of the deceleration time was observed several months after the procedure (p < 0.05)., Conclusions: We believe that dynamic cardiomyoplasty is a safe and valid surgical procedure for some patients with end stage cardiomyopathies as well as in association with Jatene's technique for the management of left ventricular aneurysms. An improvement in functional class is present and a significant increase of the left ventricular systolic function. Nevertheless it is necessary to find new systolic parameters, independent of volumetric calculations, to evaluate the mechanical support of the muscle as well as to determine the long-term pattern of electrical stimulation.

An esophagobronchial fistula developed in a patient who had well-differentiated squamous carcinoma of the lung that was treated with chemotherapy. Because the esophagobronchial fistula could not be surgically repaired, it was isolated with a mechanical stitch above and below it. Forty-eight hours after initiation of enteral nutrition, a perfusion lung scan was performed because of clinical suspicion of pulmonary embolism. Because the scan showed reduced pulmonary radioactivity and accumulation of activity in the kidneys and spine, an arteriovenous shunt was suspected. However, subsequent digital subtraction angiography ruled out this possibility and a recurrence of the esophagobronchial fistula was confirmed with an esophagogram. The unusual extrapulmonary activity could be related to a reversible capillary shunt in the pulmonary vasculature, secondary to acute respiratory distress syndrome.

By means of ultrasonography it is possible to detect hepatic lesions of few millimeters, however, it doesn't give a precise diagnosis. The role of planar scintigraphy in the diagnosis of hepatic hemangioma has already been established, although it has limitations which are partially solved by means of SPECT. 46 patients with different pathologies and 9 healthy volunteers have been studied. In the 19 confirmed hemangiomas, planar scintigraphy showed a sensitivity of 73.6% versus 84.2% for SPECT, mostly due to lesions less than 2.5 cm. Besides that, SPECT allowed a correct visualization of abdominal and intrahepatic major vessels, although lesions less than 1.5 cm are difficult to evaluate.

Brain single photon emission computed tomography (SPECT) with 99mTc-HMPAO is a diagnostic tool for evaluating regional cerebral blood flow. Recently, the diagnostic possibilities of the method are being investigated in some neurologic disorders, such as cerebrovascular accidents, seizures and dementia. This work has been carried out with 54 subjects, 9 healthy volunteers and 45 patients (31 dementia and 14 epileptics), in order to evaluate gammagraphic patterns and the utility of cortico/cerebellar activity indexes. An interesting diagnostic finding is a significant decrease (p less than 0.001) in perfusion of temporoparietal regions in the patients with Alzheimer's disease in relation with the healthy volunteers' group. We have not found significant changes in perfusion in the group of epileptic patients during the interictal phase. We conclude emphasizing the interest of the SPECT in the differential diagnosis of dementia.