Search PubMed⌕ Search

Biomedical subjects

O Sabri

Publications and source records attributed to O Sabri.

At least 55 records · Page 3Linked to original sources
PubMed1999

Active and remitted schizophrenia: psychopathological and regional cerebral blood flow findings.

Single photon emission computed tomography with technetium-99m-d,l-hexamethylpropyleneamine oxime (99mTc-HMPAO) was used to assess regional cerebral blood flow (rCBF) during both florid and remitted stages of schizophrenia. Forty schizophrenic patients in an active phase of illness (diagnosis by DSM-III-R) were examined in two clinical states (ill vs. improved). At study entry, 24 patients were drug-naive, five were currently drug-free, and 11 were being treated with antipsychotic medication. Twenty medical patients who suffered from non-specific headaches but were free of neurological and psychiatric symptoms served as control subjects. At initial examination during the active phase of illness, cerebral perfusion patterns in the schizophrenic patients were characterized by both hypofrontality and hypotemporality. After remission, hypofrontality was no longer apparent in two of four frontal regions, and hypotemporality disappeared completely. As assessed with the Positive and Negative Syndrome Scale (PANSS), formal thought disorders, hallucinations, and ideas of grandiosity correlated with rCBF in the active phase of illness, but not after remission. In the remitted but not in the florid state, blunted affect, difficulties in abstract thinking, lack of spontaneity, and stereotyped thoughts correlated with rCBF. Correlations of five symptoms with rCBF changed significantly from first to second examination. The present study suggests that correlations between single psychotic symptoms and rCBF differ significantly in florid vs. remitted phases of schizophrenia.

Adult↗
PubMed1999

Dual-head gamma camera 2-[fluorine-18]-fluoro-2-deoxy-D-glucose positron emission tomography in oncological patients: effects of non-uniform attenuation correction on lesion detection.

The purpose of this study was to evaluate a dual head coincidence gamma camera (DH-PET) equipped with single-photon transmission for 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients. Forty-five patients with known or suspected malignancies, scheduled for a positron emission tomography (PET) scan, were first studied with a dedicated ring PET and subsequently with DH-PET. All patients underwent measured attenuation correction using germanium-68 rod sources for ring PET and caesium-137 sources for DH-PET. Ring PET emission scan was started 64+/-17 min after intravenous administration of 235+/-42 MBq FDG. DH-PET emission followed 160+/-32 min after i.v. FDG. Attenuation-corrected and non-attenuation-corrected images were reconstructed for ring PET and DH-PET. The image sets were evaluated independently by three observers blinded to clinical data and to results of conventional imaging. Attenuation-corrected ring PET as the standard of reference depicted 118 lesions, non-attenuation-corrected ring PET 113 (96%) lesions, and attenuation-corrected DH-PET and non-attenuation-corrected DH-PET, 101 (86%) and 84 (71%) lesions, respectively (P<0.05). The lesion detection rate of attenuation-corrected and non-attenuation-corrected DH-PET was almost similar for lesions >20 mm, whereas attenuation correction increased the detection rate from 60% to 80% for lesions </=20 mm (P<0.01). A patient-based analysis revealed concordant results relative to attenuation-corrected ring PET for non-attenuation-corrected ring PET, attenuation-corrected DH-PET and non-attenuation-corrected DH-PET in 42 (93%), 36 (80%) and 31 (69%) patients, respectively. Differences might have influenced patient management in two (4%), six (13%) and ten (22%) patients, respectively. In conclusion, measured attenuation correction markedly improves the lesion detection capability of DH-PET. With measured attenuation correction the diagnostic performance of DH-PET is closer to that of dedicated ring PET.

Evaluation Studies as Topic↗
PubMed1999

"Ecstasy"-induced changes of cerebral glucose metabolism and their correlation to acute psychopathology. An 18-FDG PET study.

The aim of this study was to determine the acute effects of the "Ecstasy" analogue MDE (3,4-methylene dioxyethamphetamine) on cerebral glucose metabolism (rMRGlu) of healthy volunteers and to correlate neurometabolism with acute psychopathology. In a randomized double-blind trial, 15 healthy volunteers without a history of drug abuse were examined with fluorine-18-deoxyglucose (18FDG) positron emission tomography (PET) 110-120 min after oral administration of 2 mg/kg MDE (n = 7) or placebo (n = 8). Two minutes prior to radiotracer injection, constant cognitive stimulation was started and maintained for 32 min using a word repetition paradigm to ensure constant and comparable mental conditions during cerebral glucose uptake. Individual brain anatomy was represented using Tl-weighted 3D flash magnetic resonance imaging (MRI), followed by manual regionalization into 108 regions of interest and PET/MRI overlay. After absolute quantification of rMRGlu and normalization to global metabolism, normalized rMRGlu under MDE was compared to placebo using the Mann-Whitney U-test. Acute psychopathology was assessed using the Positive and Negative Syndrome Scale (PANSS) and rMRGlu was correlated to PANSS scores according to Spearman. MDE subjects showed significantly decreased rMRGlu in the bilateral frontal cortex: left frontal posterior (-7.1%, P < 0.05) and right prefrontal superior (-4.6%, P < 0.05). On the other hand, rMRGlu was significantly increased in the bilateral cerebellum (right: +10.1%, P < 0.05; left: +7.6%, P < 0.05) and in the right putamen (+6.2%, P < 0.05). There were positive correlations between rMRGlu in the middle right cingulate and grandiosity (r = 0.87, P < 0.05), both the right amygdala (r = 0.90, P < 0.01) and the left posterior cingulate (r = 0.90, P < 0.01) to difficulties in abstract thinking, and the right frontal inferior (r = 0.85, P < 0.05), right anterior cingulate (r = 0.93, P < 0.01), and left anterior cingulate (r = 0.85, P < 0.05) to attentional deficits. A negative correlation was found between the left frontal operculum (Broca's area) and attentional deficits (r = -0.85, P < 0.05). The present study revealed acute neurometabolic changes under the "Ecstasy" analogue MDE, indicating a frontostriatocerebellar imbalance paralleling other psychotropic substances or various psychiatric disorders.

3,4-Methylenedioxyamphetamine↗
PubMed1999

Preoperative PET activation for assessment of motor cortex area in precentral chondroma.

BACKGROUND: A main problem in the preoperative planning for precentral tumors is the exact assessment of the spatial relationship between the tumor and the functionally relevant brain areas, which may be difficult using only morphologically oriented imaging (CT, MRI). Therefore, we applied motor activation PET and PET/MRI overlay in a patient with a precentral tumor. DESCRIPTION: We report the case of a 21-year-old woman suffering from progressive right-sided headache and intermittent dysesthesia of the left leg. MRI showed a hypointense tumor with inhomogenous contrast enhancement in the right precentral area. For preoperative assessment of the spatial relationship between the tumor and the motor cortex area, the patient underwent two F-18-fluorodeoxyglucose positron emission tomography (PET) scans (1. resting condition and 2. motor activation of the left leg) and subsequent calculation of subtraction images of activation minus rest. Fusion of PET and MRI data (PET/MRI overlay) was performed for bimodal function and morphology presentation. PET revealed an activation pattern behind and below the tumor, indicating that the motor cortex area was shifted to the back. PET findings were confirmed by intraoperative electrophysiology. Cortical stimulation combined with intraoperative neuronavigation localized the motor area of the left foot and leg exactly at the dorsal border, below and lateral to the lesion. After complete resection of the solid tumor, histopathological examination revealed a chondroma. The postoperative course was uneventful, and the patient was discharged without neurological deficits. CONCLUSIONS: This case shows that biomodal imaging (PET/MRI) provides a noninvasive exact assessment of functionally important cortex areas for preoperative planning in patients with cerebral lesions.

Adult↗
PubMed1999

Neurometabolic effects of psilocybin, 3,4-methylenedioxyethylamphetamine (MDE) and d-methamphetamine in healthy volunteers. A double-blind, placebo-controlled PET study with [18F]FDG.

The neurometabolic effects of the hallucinogen psilocybin (PSI; 0.2 mg/kg), the entactogen 3,4-methylenedioxyethylamphetamine (MDE; 2 mg/kg) and the stimulant d-methamphetamine (METH; 0.2-0.4 mg/kg) and the drugs' interactions with a prefrontal activation task were investigated in a double-blind, placebo-controlled human [F-18]fluorodeoxyglucoseFDG-positron emission tomographicPET study (each group: n = 8). Subjects underwent two scans (control: word repetition; activation word association) within 2-4 weeks. Psilocybin increased rMRGlu in distinct right hemispheric frontotemporal cortical regions, particularly in the anterior cingulate and decreased rMRGlu in the thalamus. Both MDE and METH induced cortical hypometabolism and cerebellar hypermetabolism. In the MDE group, cortical hypometabolism was more pronounced in frontal regions, with the exception of the right anterior cingulate, which tended to be hyperactive. Cognitive activation-related increases in left frontocortical regions were attenuated under all three psychoactive substances, but less so under MDE. Taking into account performance data and subjective reports on task difficulty, these effects may result from different mechanisms across the three groups. Our PSI data are in line with studies on acute schizophrenic patients suggesting frontal overactivity at rest, but diminished capacity to activate prefrontal regions upon cognitive demand. The MDE data support the hypothesis that entactogens constitute a distinct psychoactive substance class, which takes an intermediate position between stimulants and hallucinogens.

3,4-Methylenedioxyamphetamine↗
PubMed1999

[Aspects of cerebral connnectivity in schizophrenia. A comparative CBF study on treated schizophrenics before and after medication].

INTRODUCTION: The hypothesis of prefrontal-temporolimbic disconnectivity, considered to be relevant to the pathogenesis of schizophrenia, has been tested in 29 drug-naive schizophrenic patients, comparing the active with the remitted state. METHOD: A pre-post-treatment design was applied to 29 drug-naive schizophrenic inpatients, 18 male, mean age 32 years, 11 female, mean age 32 years, mean duration of illness 29 months. Psychopathological symptoms were assessed using PANSS, regional cerebral blood (rCBF) was measured by HMPAO-SPECT. RCBF values were calculated for 21 regions of interest after normalization to cerebellum, and plotted by Euklidean diagrams using the ordinal, nonmetric, multidimensional scaling method. These diagrams represent similarity correlations visualized as spatial distances. High correlation levels as indicated by small Euklidean distances have been interpreted as functional connectivity. RESULTS: In active schizophrenia, functional disconnectivity was observed between prefrontal and temporal cortex. After remission, connectivity was improved between temporolimbic and frontal cortex. CONCLUSION: Comparing active with remitted schizophrenia, a frontotemporal disconnectivity appears. Temporolimbic as well as frontolimbic connections restitute parallel to psychopathological improvement.

Adolescent↗
PubMed1999

Radioiodine therapy in Graves' disease patients with large diffuse goiters treated with or without carbimazole at the time of radioiodine therapy.

We sought to ascertain how high the success rates of radioiodine therapy are for Graves' disease patients with large diffuse goiters when aiming for a constant absorbed dose of 250 Gy. Thirty-six patients with a thyroid volume of 50-110 mL were evaluated for changes in thyroid function and appearance 3, 6, and 12 months after radioiodine therapy. Success was defined as definitive elimination of hyperthyroidism following therapy (hypothyroidism corrected with thyroxine on diagnosis); failure as persistent/recurrent hyperthyroidism after 12 months. Overall success rate was 50%. However, a subgroup of 20 patients without simultaneous carbimazole (carbimazole-off) showed a highly significantly larger success rate (85%) than the 16 patients with simultaneous carbimazole (carbimazole-on) at the time of radioiodine therapy (6.3%, p < 0.000005). Successful cases showed a significantly higher volume reduction after radioiodine than failures (75.5% vs. 35.4%, p < 0.00005). Stepwise logistic regression showed that therapy failure was related to administration of carbimazole during radioiodine therapy (p < 0.0250 and absorbed dose (p < 0.05), but not thyroid function (free triiodothyronine [FT3] and free thyroxine [FT4]), initial thyroid volume or thyrotropin-receptor antibody (TRAb) value. However, a significant correlation of therapy success to absorbed dose (r = 0.69, p < 0.005) could be shown only for carbimazole-off patients, but not for the others. Finally, multivariate factor analysis consistently showed that therapy success was correlated only to absorbed dose and antithyroid drugs, not to initial thyroid volume, TRAb value, or thyroid function. Thyroid volume per se is not responsible for the lower success rate in Graves' disease patients with large goiters because even a comparable group of 32 Graves' disease patients with small thyroid glands (< or =20 mL) and without simultaneous carbimazole showed a success rate of 87.5%. The high failure rate in the carbimazole-on patients (absorbed dose comparable to carbimazole-off) is due to the simultaneous administration of carbimazole. Therefore, if clinically feasible, we recommend discontinuing carbimazole at least one day before beginning radioiodine therapy.

Adult↗
PubMed1999

Neuropsychological impairment correlates with hypoperfusion and hypometabolism but not with severity of white matter lesions on MRI in patients with cerebral microangiopathy.

BACKGROUND AND PURPOSE: Cerebral microangiopathy, indicated on MRI by lacunar infarctions (LI) and deep white matter lesions (DWML), is said to lead to vascular dementia. METHODS: Fifty-seven patients with proven cerebral microangiopathy were assessed for changes in regional cerebral blood flow (rCBF) and glucose metabolism (rMRGlu) and compared with 19 age-matched controls. The findings were correlated with results of extensive neuropsychological testing, as well as with MRI findings. A special head holder ensured reproducibility of positioning during rCBF (single-photon emission CT [SPECT]), rMRGlu (positron emission tomography [PET]), and MR imaging. White matter and cortex were quantified with regions of interest defined on MRI and superimposed to corresponding PET/SPECT slices. LI and DWML were graded by number and extent. RESULTS: Even with severe DWML and multiple LI, rCBF and rMRGlu values were not reduced. ANOVAs identified brain atrophy and neuropsychological deficits as the main determinants for reduced rCBF and rMRGlu values in both cortex and white matter. Neuropsychological deficits correlated well with decreased rCBF and rMRGlu, whereas MRI patterns such as LI and DWML did not. Factor analysis revealed no correlation of LI and DWML with rCBF, rMRGlu, atrophy, and neuropsychological deficits, showing instead positive correlations between rCBF, rMRGlu, and neuropsychological performance and negative correlations of the latter 3 with brain atrophy. CONCLUSIONS: From these data, we conclude that LI and DWML are epiphenomena that may morphologically characterize cerebral microangiopathy but do not in themselves indicate cognitive impairment. Dementia or neuropsychological deficits, by contrast, are reflected exclusively by functional imaging parameters (rCBF, rMRGlu) and cerebral atrophy.

Adult↗
PubMed1999

Success rate of radioiodine therapy in Graves' disease: the influence of thyrostatic medication.

There is controversy whether simultaneous thyrostatic medication influences the outcome of radioiodine (131I) therapy in Graves' disease by reducing the absorbed energy dose of 131I when delivering a standard dose. We therefore sought to ascertain whether the outcome of ablative 131I therapy is in any way affected by simultaneous thyrostasis (carbimazole) by aiming for a constant absorbed dose of 200-250 Gy. We prospectively studied 207 patients with Graves' disease (106 with and 101 without simultaneous carbimazole at the time of 131I therapy). All patients were reexamined 3, 6, and 12 months after 131I therapy. The 101 nonthyrostatic patients showed a highly significantly greater success rate (93%) than the 106 thyrostatic patients (49%). Stepwise logistic regression demonstrated that failure was related to the administration of carbimazole during 131I therapy (P < 0.00005) and the absorbed dose (P < 0.025), but was not related to free T3, free T4, TSH receptor antibodies, or thyroid volume. The success rate was 100% in 93 nonthyrostatic patients with absorbed doses of 200 Gy or more, but was only 12.5% (1 of 8) for absorbed doses less than 200 Gy. Correlation between success and absorbed dose was significantly higher for nonthyrostatic than for thyrostatic patients (r = 0.93 vs. r = 0.24). Sixteen patients who discontinued thyrostasis 1-3 days before 131I therapy showed 94% successes. Simultaneous thyrostasis is the decisive factor against a successful 131I therapy even if the significantly reduced 131I uptake/half-life values under thyrostasis are compensated with a higher delivered dose to ensure a comparable absorbed dose, possibly due to the additionally effective radioprotective properties of carbimazole. Therefore, if clinically feasible, we recommend discontinuing thyrostasis at least 1 day before beginning 131I therapy, because even in hyperthyroid nonthyrostatic patients the success rate was 100%.

Adult↗
PubMed1999

F-18-FDG positron imaging in oncological patients: gamma camera coincidence detection versus dedicated PET.

AIM: Of the present study was to investigate the feasibility of 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG) imaging in oncological patients with a dual head gamma camera modified for coincidence detection (MCD). METHODS: Phantom studies were done to determine lesion detection at various lesion-to-background ratios, system sensitivity and spatial resolution. Thirty-two patients with suspected or known malignant disease were first studied with a dedicated full-ring PET system (DPET) applying measured attenuation correction and subsequently with an MCD system without attenuation correction. MCD images were first interpreted without knowledge of the DPET findings. In a second reading, MCD and DPET were evaluated simultaneously. RESULTS: The phantom studies revealed a comparable spatial resolution for DPET and MCD (5.9 x 6.3 x 4.2 mm vs. 5.9 x 6.5 x 6.0 mm). System sensitivity of MCD was less compared to DPET (91 cps/Bq/ml/cmFOV vs. 231 cps/Bq/ml/cmFOV). At a lesion-to-background ratio of 4:1, DPET depicted a minimal phantom lesion of 1.0 cm in diameter, MCD a minimal lesion of 1.6 cm. With DPET, a total of 91 lesions in 27 patients were classified as malignant. MCD without knowledge of DPET results revealed increased FDG uptake in all patients with positive DPET findings. MCD detected 72 out of 91 DPET lesions (79.1%). With knowledge of the DPET findings, 11 additional lesions were detected (+12%). MCD missed lesions in six patients with relevance for staging in two patients. All lesions with a diameter above 18 mm were detected. CONCLUSION: MCD FDG imaging yielded results comparable to dedicated PET in most patients. However, a considerable number of small lesions clearly detectable with DPET were not detected by MCD alone. Therefore, MCD cannot yet replace dedicated PET in all oncological FDG studies. Further technical refinement of this new method is needed to improve image quality (e.g. attenuation correction).

Adult↗
PubMed1999

[Various dynamics of Tc-99m-tetrofosmin and Tc-99m-MIBI in a parathyroid adenoma].

Case report of a patient with hypercalcemia and suspected parathyroid adenoma. Because of a previous strumectomy a precise preoperative localization of the suspected parathyroid adenoma was demanded. Tc-99m-tetrofosmin scintigraphy in double phase technique failed to detect a parathyroid adenoma by failing to show a region of increased focal uptake with delayed washout in relation to the thyroid gland. Only comparison of the Tc-99m-tetrofosmin images with a Tc-99m-pertechnetate scan revealed a right caudal parathyroid adenoma. A double phase Tc-99m-MIBI study of the same patient was able to localize this parathyroid adenoma without the need of a corresponding Tc-99m-pertechnetate scintigraphy due to a differential washout with persistent focal uptake in the parathyroid adenoma and a progressively decreasing uptake in the thyroid tissue. This case indicates that Tc-99m-tetrofosmin is a suitable agent for parathyroid imaging only if used together with Tc-99m-pertechnetate but it seems to lack the differential washout characteritics of Tc-99m-MIBI according parathyroid gland and thyroid gland.

Adenoma↗
PubMed1999

[Quantification of repositioning errors in PET studies through superimposition of emission and transmission scans. Comparison between acquisition with and without repositioning].

AIM: The purpose of this study was to quantify positioning discrepancies between emission (E) and transmission (T) scan using image fusion. A direct comparison of one-step and two-step acquisitions was performed where all studies were analyzed in respect to artifacts caused by inaccurate positioning. In addition, phantom measurements were conducted to estimate the consequences of repositioning errors on standardized uptake value calculations (SUV). METHODS: 40 patients were examined by two-step whole-body scans using PET and 15 patients were subject to one-step examinations in the head/neck area. Repositioning between the scans was achieved by a laser matrix positioning system in combination with external body markings. After reconstruction and image fusion of the scans, the positioning discrepancies were measured as the distances between the outer boundaries of E and T in four different body regions. Additional evaluations of the SUV by increasing E-T dislocation were performed using a Jaszczak phantom containing hollow spheres. RESULTS: For the two-step acquisitions, the mean spatial deviations along the three orthogonal axes x, y, and z were between 8.9 mm and 13.8 mm, whereas for the one-step examinations mean values between 3.5 mm and 4.3 mm were determined (level of significance in each direction p < 0.0001). Artifacts were found in 47.5% of the whole body scans, but in none of the head/neck studies. The development of image artifacts was simulated by phantom studies. In contrast, the deviations of the computed SUV caused by increasing positioning discrepancies were minimal because of the minimal differences between the attenuation coefficients of the media involved. CONCLUSION: The presented data show that an artifactfree reconstruction of attenuation-corrected studies requires a precise positioning of the patient. One-step examination protocols without repositioning are advantageous due to the significantly lower positioning discrepancies. The additional reconstruction of nonattenuation-corrected studies has proven to be useful in discovering image artifacts and is therefore recommended.

Artifacts↗
PubMed1999

[Role of positron emission tomography (PET) and single photon emission tomography (SPECT) in so-called "multiple chemical sensitivity"].

Functional imaging with SPECT and PET is increasingly used to prove evidence for the existence of a syndrome "Multiple Chemical Sensitivity" (MCS) and plays a major role in legal trials to justify compensation for the exposure to solvents. This paper critically reviews the literature on the use of SPECT and PET for the determination of MCS. The authors come to the conclusion that the current data are not sufficient to justify the claim of the existence of such a syndrome. The low specificity of the observed PET and especially SPECT-findings makes it very difficult to establish a cause-result relationship and therefore makes the use of these methods in legal trials on this issue doubtful.

Humans↗
PubMed1999

[Bone scintigraphy and rhenium radioisotope management in the course of metastatic prostatic cancer].

A 78-year-old patient with prostate cancer and osseous metastases had a pain symptomatic. In the Urology he was treated with antiandrogenes. The outcome of the bone scintigraphy showed a super bone scan with normalization after antiandrogene-therapy which seemed to be a sign of remission, before he showed a progressive form with multiple osseous metastases. Pain could not be treated with non steroidal antiphlogistics and opiates, so the indication for treatment with Rhenium-186-HEDP was given in this case.

Aged↗
PubMed1999

[Radioiodine therapy in veterinary medicine: treatment of hyperthyroidism in a cat].

A nine-year-old cat with symptoms of a distinct hyperthyroidism was presented at the University Hospital of the RWTH Aachen. The clinical symptoms as well as the diagnostic procedures performed at the hospital confirmed the diagnosis. After five weeks of thyreostatic medication a regular metabolism of the thyroid gland was established, followed by a radioiodine therapy with 70.3 MBq 131-iodine. Subsequently, the cat was hospitalized for two days before it could be released in good condition. Six weeks after treatment the former drastically reduced weight of the cat recovered to near normal. Even though the chemical analysis detected a discrete hyperthyroidism, clinical symptoms were no longer prominent. Three months after treatment, the final examination showed a regular metabolism of the thyroid gland without a specific thyroidal medication. The presented case illustrates that radioiodine therapy is a safe and efficient treatment of thyroidal dysfunctions in veterinary medicine.

Animals↗
PubMed1998

[Clinical value of positron emission tomography in neuromedicine. Position paper on results of an interdisciplinary consensus conference].

To date, positron emission tomography (PET) is the most powerful method for the in-vivo investigation of human brain metabolism. Besides extensive application of this technology in the neurosciences, PET is also being increasingly used as a clinical tool. However, despite its acceptance in clinical practice a major obstacle is its high costs. The present article reviews the literature on the clinical use of PET in neurology, neurosurgery, and psychiatry in order to substantiate the clinical indications for PET in these specialties as established by an interdisciplinary conference.

Brain Diseases↗
PubMed1998

Cerebral interregional correlations of associative language processing: a positron emission tomography activation study using fluorine-18 fluorodeoxyglucose.

Even though there have been numerous positron emission tomography (PET) activation studies on the perfusional and metabolic bases of language processing, little is known about the intracerebral functional network of language and cognitive processes. It was the aim of this study to investigate the cerebral interregional correlations during voluntary word association versus word repetition in healthy subjects to gain insight into the functional connectivity of associative speech processing. Due to individual variability in functional anatomy, the study protocol was designed as an averaged single-subject study. Eight healthy volunteers performed a verbal association task during fluorine-18 fluorodeoxyglucose (18F-FDG) PET scanning. Two different tasks were performed in randomized order: (a) word repetition (after auditory presentation of nouns) as a control condition, and (b) word association (after auditory presentation of nouns) as a specific semantic activation. The regional metabolic rate of glucose (rMRGlu) was calculated after brain regionalization [112 regions of interest on individual 3D flash magnetic resonance imaging (MRI)] and PET/MRI realignment. Statistical analysis was performed for comparison of association and repetition and for calculation of interregional correlation coefficients during both tasks. Compared with word repetition, word association was associated with significant increases in rMRGlu in the left prefrontal cortex, the left frontal operculum (Broca's area) and the left insula, indicating involvement of these areas in associative language processing. Decreased rMRGlu was found in the left posterior cingulum during word association. During word repetition, highly significant negative correlations were found between the left prefrontal cortex, the contralateral cortex areas and the ipsilateral posterior cingulum. These negative correlations were almost completely eliminated during the association task, suggesting a functional decoupling of the strict intercorrelation pattern.

Adult↗