Basem Garada

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Volumetric index of Tl-201 uptake in symptomatic patients after high - dose radiation treatment for high-grade gliomas

J Nucl Med, Apr 30, 1995

To verify the utility of a volumetric estimation of Tl-201 uptake in the context of possible astr... more To verify the utility of a volumetric estimation of Tl-201 uptake in the context of possible astrocytoma recurrence after surgery, radiotherapy plus stereotactic boost (radiosurgery/brachitherapy), we analyzed sequential Tl-201/Tc99m-HMPAO brain SPECT studies of 28 patients (18 m/10 f). These were categorized as having tumor mass recurrence (TM), infiltrating tumor cells but no definite tumor mass (IT), or radiation changes and necrosis (RCN) after stereotactic biopsy and/or craniotomy. SPECT studies were obtained with a high-resolution dedicated gamma camera (CERASPECT, Digital Scinitgraphics, Inc.) and image acquisition was performed after intravenous Tl-201 (18.5 MBq) and Tc-99m HMPAO (740 MBq). In order to include relevant information about tumor burden, a volumetric index of Tl-201 uptake was expressed in cm{sup 3} related to voxel size (4.6 x 10{sup -3} cc) within an elliptical ROI that included the tumor area. Only voxels with a threshold {ge} 2 in relation to the average scalp Tl-201 uptake were included and this total number of voxels expressed in cc was compared to previously established maximal tumor/scalp Tl-201 uptake ratios (T/S) and histopathology. Results are presented as the median (min-max) and differences were considered significant for p<0.05. Differences were significant between all groups for both ratios and volume indices andmore » correlation between the two variables was 0.90. In conclusion, the volumetric index of Tl-201 is similar to the maximal Tl-201 T/S ratios in discriminating tumor recurrence and radiation necrosis, suggesting a future role for the volumetric index estimation in the evaluation of treatment efficacy and patient follow-up.« less

Quantitative brain SPECT in Alzheimer's disease and normal aging

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1993

To improve the diagnostic utility of brain single-photon emission computed tomography (SPECT) in ... more To improve the diagnostic utility of brain single-photon emission computed tomography (SPECT) in Alzheimer's disease (AD), we have developed and evaluated an objective method of differentiating patients and healthy elderly controls using a quantitative image analysis protocol. HMPAO-SPECT image datasets from 29 patients with probable AD and 78 age-matched controls were registered to a common anatomic frame of reference. Activity levels within 120 standardized cortical volumes were determined by an automated procedure. Subjects were classified into normal and AD groups by quadratic discriminant analysis using two features: global average activity level and average normalized activity levels within the two clusters of standardized volumes identified as most significantly different in AD by analysis of covariance. The classification used split-half replication to ensure valid results. Classification performance quantified by the area under a binormal ROC curve fitted to the data wa...

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A comparison of brain perfusion SPECT in cocaine abuse and AIDS dementia complex

Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1992

Intravenous drug use is a major risk factor for HIV-1 infection. Since both AIDS dementia complex... more Intravenous drug use is a major risk factor for HIV-1 infection. Since both AIDS dementia complex (ADC) and cocaine have been associated with abnormal brain perfusion imaging, we compared the scintigraphic patterns of ADC patients and cocaine polydrug users with normal control subjects using 99mTc-HMPAO SPECT. We found a high incidence of cortical defects in both ADC (100%) and cocaine-dependent (90%) subjects. In the cocaine and ADC patients, cortical defects were most frequent in the frontal, temporal and parietal lobes and occurred with similar frequency in the two populations. In both groups, the number of cortical defects per subject was higher than normal subjects (10.0 +/- 5.0 for ADC, 10.1 +/- 5.2 for cocaine and 0.7 +/- 1.5 for normal), background activity was high (a 65% and 60% incidence for ADC and cocaine, respectively), and basal ganglia involvement was frequent (40% and 65% for ADC and cocaine). We conclude that the brain perfusion pattern, while a sensitive indicator...

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Findings on CT, MR Imaging, and SPECT Imaging in 14 Cases

Hypertensive encephalopathy is a syndrome consisting of headache, seizures, visual changes, and o... more Hypertensive encephalopathy is a syndrome consisting of headache, seizures, visual changes, and other neurologic disturbances in patients with elevated systemic blood pressure. The purpose of this study was to analyze the imaging findings in 14 patients with hypertensive encephalopathy. CT (n = 13), MR (n = 12), and single-photonemission computed tomography (n = 2) examinations performed in these patients before and after resolution of symptoms were reviewed. Eight had the preeclampsia-eclampsia syndrome, and six had hypertensive encephalopathy due to other causes. CT and MR findings in all patients having these examinations were indicative of edema in the cortex and subcortical white matter in the occipital lobes. Two of the 14 patients also had similar findings in the cerebellum and frontal lobes. Single-photon emission computed tomography showed increased vascular perfusion adjacent to areas that appeared abnormal on CT and MR. The findings on the imaging studies resolved on foll...

Technepine: A high-affinity99mtechnetium probe to label the dopamine transporter in brain by SPECT imaging

Synapse, 1996

... Madras, BK, Jones, AG, Mahmood, A., Zimmerman, RE, Garada, B., Holman, BL, Davison, A., Blund... more

Focal cerebral perfusion defects demonstrated by 99mTc-hexamethylpropyleneamine oxime SPECT in elderly depressed patients

Psychiatry Research: Neuroimaging, 1996

High resolution single photon emission computed tomography (SPECT) was used to evaluate regional ... more High resolution single photon emission computed tomography (SPECT) was used to evaluate regional cerebral blood flow (rCBF) in 14 acutely depressed elderly patients and 29 normal subjects. SPECT images of the two groups were randomized and blindly read. Foci of decreased radionuclide uptake were assessed by number and location. The total number of rCBF defects per whole brain study was significantly greater in the depressed patients than in the normal subjects. A significantly greater number of rCBF defects was found most strikingly in the lateral frontal and less prominently in the lateral and medial temporal brain regions of the depressed patients.

SPECT-MR Image Fusion in the Intraoperative MR for Guidance of Neurosurgical Tumor Resection

Neurosurgery, 1997

Dual-isotope single-photon emission computerized tomography scanning in patients with glioblastoma multiforme: association with patient survival and histopathological characteristics of tumor after high-dose radiotherapy

Journal of Neurosurgery, 1998

Object. The study was conducted to determine the association between dual-isotope single-photon e... more Object. The study was conducted to determine the association between dual-isotope single-photon emission computerized tomography (SPECT) scanning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multiforme. Methods. Studies in which SPECT with 201Tl and 99mTc-hexamethypropyleneamine oxime (HMPAO) were used were performed 1 day before reoperation in 47 patients with glioblastoma multiforme who had previously been treated by surgery and high-dose radiotherapy. Maximum uptake of 201Tl in the lesion was expressed as a ratio to that in the contralateral scalp, and uptake of 99mTc-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups based on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological characteristics of tissue at reoperation, and SPECT uptake group with respect to 1-year survival was...

Detection of recurrent gliomas with quantitative thallium-201/technetium-99m HMPAO single-photon emission computerized tomography

Journal of Neurosurgery, 1992

✓ Deteriorating clinical status after high-dose radiation therapy for high-grade gliomas may be d... more ✓ Deteriorating clinical status after high-dose radiation therapy for high-grade gliomas may be due to radiation changes or may signal recurrent or residual tumor mass. The two conditions cannot be distinguished reliably by computerized tomography (CT) or magnetic resonance (MR) imaging. The authors assessed the ability of sequential thallium-201 chloride (201T1) and technetium-99m hexamethylpropylene amine oxime (99mTc HMPAO) single-photon emission CT (SPECT) to distinguish tumor recurrence from radiation changes after high-dose (≥ 600 cGy) radiation therapy for malignant gliomas. Preoperative tumor/nontumor uptake ratios were analyzed in 32 patients and correlated with the presence of gross tumor at the time of reoperation. In 12 of 13 patients with 201T1 tumor/scalp ratios of 3.5 or greater, recurrent tumor was present. The authors found 99mTc HMPAO SPECT to be useful for identifying the absence of solid tumor recurrence in patients with low to moderate 201T1 uptake (ratio 1.1 to...

A Technetium-99m SPECT Imaging Agent Which Targets the Dopamine Transporter in Primate Brain

Journal of Medicinal Chemistry, 1997

The dopamine transporter (DAT), located presynaptically on dopamine neurons, provides a marker fo... more The dopamine transporter (DAT), located presynaptically on dopamine neurons, provides a marker for certain neurological diseases. In particular, the DAT is depleted in Parkinson&amp;amp;#39;s disease, and the extent of depletion correlates with the loss of dopamine. Herein we describe the design, synthesis, and biological evaluation of technepine, the first 99mTc-labeled SPECT imaging agent which targets the dopamine transporter in striatum. We have demonstrated that the DAT can accommodate a chelating unit attached to the 8-amine function of a tropane skeleton. Further, we have demonstrated for the first time that a molecule can be designed to carry the radionuclide 99mTc across the blood-brain barrier in sufficient quantity to obtain in vivo images of the striatum in monkeys. This advance will undoubtedly lead to the design of new receptor and transporter-mediated 99mTc agents which can label specific transporter and receptor targets in the central nervous system.

Functional imaging in treatment planning of brain lesions

International Journal of Radiation Oncology*Biology*Physics, 1997

Explore the use of functional imaging data in radiation treatment planning of brain lesions. Comp... more Explore the use of functional imaging data in radiation treatment planning of brain lesions. Compare the treatment-planning process with and without the use of functional brain imaging for clinical cases where functional studies using either single photon emission computed tomography or magnetic resonance imaging are available. A method to register functional image data with planning image studies is needed for functional treatment planning. Functional volumes are not simply connected regions. One activation study may produce many isolated functional areas. After finding the functional volumes and registering the functional information with the planning imaging data, the tools used for conventional three-dimensional treatment planning are sufficient for functional treatment planning. However, the planning system must provide dose-volume histograms for volumes of interest that consist of isolated pieces. Treatment plans that spare functional brain while providing identical target coverage can be constructed for lesions situated near the functional volume. However, the dose to other areas of the brain may be increased. Functional imaging will make determination of dose response of eloquent areas of the brain possible when combined with volumetric dose information and neuropsychological evaluation prior to and after radiation therapy. Realizing the full potential of functional imaging studies will require improved delineation of activated volumes and determination of the uncertainties in functional volume delineation. Optimization of treatment plans by minimizing dose to volumes activated during functional imaging studies should be used cautiously, because the dose to &quot;silent,&quot; but possibly eloquent, brain may be increased.

Focal brain dysfunction in a 41-year old man with familial alternating hemiplegia

European Archives of Psychiatry and Clinical Neuroscience, 1997

The acute pathophysiologic changes during hemiplegic spells and the long-term outcome of alternat... more The acute pathophysiologic changes during hemiplegic spells and the long-term outcome of alternating hemiplegia remain obscure. In a 41-year-old male with familial alternating hemiplegia we found an increase in right frontal cerebral blood flow 3 h into a 5-h left hemiplegic episode. A repeat high-resolution brain SPECT study performed 26 h after the resolution of the left hemiplegia revealed normalization of the frontal blood flow accompanied by hyperperfusion in the right parietal lobe. An interictal SPECT scan several weeks later showed no asymmetries. Head CT and MRI scans were negative. Neuropsychologic assessment and neurologic examination revealed evidence of a diffuse disorder which predominantly involved the right hemisphere. To our knowledge, there are no previous correlative studies of serial high-resolution brain SPECT with MRI, or of detailed neuropsychologic assessment, in adult patients with such an advanced course of alternating hemiplegia of childhood.

Tc-99m HMPAO Brain Perfusion SPECT in Acute Aphasia Correlation With Clinical and Structural Findings

Clinical Nuclear Medicine, 1993

Tc-99m hexamethylpropylene amineoxime (HMPAO) brain perfusion SPECT was correlated with CT, MRI, ... more Tc-99m hexamethylpropylene amineoxime (HMPAO) brain perfusion SPECT was correlated with CT, MRI, and clinical findings in 17 patients with acute and subacute aphasia to determine its diagnostic potential in the early phases of stroke-associated language dysfunction. SPECT was performed using a dedicated brain imaging system after intravenous injection of 20 mCi (740 MBq) of Tc-99m HMPAO. Transaxial and three-dimensional surface rendered images were evaluated visually, and perfusion defects were correlated with CT, MRI, and a standard battery of clinical tests for aphasia. Clinical examination was insufficient for anatomic localization of aphasia in more than 40% of patients. CT exams were normal in 5 patients, although SPECT demonstrated perfusion defects in all 17. Nonfluent aphasia was present in only 6 of 10 patients with perfusion defects in Broca&#39;s area and fluent aphasia was present in only 5 of 10 patients with lesions in Wernicke&#39;s area. Auditory comprehension defect was associated with perfusion defects in the inferior parietal region in 9 of 12 patients (P = 0.05); reading and writing abnormalities were associated with perfusion defects in the posterior frontal, superior and inferior parietal cortex, and superior temporal gyri, and repetition deficit was associated with defects involving the inferior parietal cortex, the supramarginal and angular gyri, and the ipsilateral thalamus in 8 of 11 patients (P &lt; 0.05). Brain perfusion SPECT should be included in the initial evaluation of aphasic patients, because clinical tests of aphasia and morphological imaging have limited value for accurately determining the extent and location of functional deficits.

Thallium-201 Technetium-99m HMPAO single-photon emission computed tomography (SPECT) imaging for guiding stereotactic craniotomies in heavily irradiated malignant glioma patients

Acta Neurochirurgica, 1993

SPECT scanning with Tl-201 and Tc-99m offers a unique, inexpensive functional imaging modality to... more SPECT scanning with Tl-201 and Tc-99m offers a unique, inexpensive functional imaging modality to combine with CT stereotactic craniotomy for guiding resection of necrosis and/or tumour in patients treated with escalated doses of radiation (&gt; 6000 cGy) by either brachytherapy or radiosurgery. Thirty-two cases were analyzed, with a detailed description of the imaging and operative techniques.

SPECT imaging of the brain: comparison of findings in patients with chronic fatigue syndrome, AIDS dementia complex, and major unipolar depression

American Journal of Roentgenology, 1994

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