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Biomedical subjects

M Ivanovic

Publications and source records attributed to M Ivanovic.

At least 19 recordsLinked to original sources
PubMed2001

Functional, dynamic, and anatomic MR urography: feasibility and preliminary findings.

RATIONALE AND OBJECTIVES: The authors assessed the feasibility of using magnetic resonance (MR) urography to acquire functional, dynamic, and anatomic information in human subjects with normal and hydronephrotic kidneys. MATERIALS AND METHODS: In subjects known to have or suspected of having hydronephrosis, split renal filtration fractions were measured with a customized magnetization-prepared, inversion-prepared gradient-recalled echo sequence to determine the T1 of flowing blood in the inferior vena cava and aorta before and after contrast medium administration and in the renal veins and arteries after contrast medium administration. Multiple timed sets of coronal fast spoiled gradient-echo 70 degrees flip-angle images were acquired before and after contrast medium administration to derive MR renograms from changes in the signal intensity of the cortex and medulla. Precontrast T2-weighted images were obtained with a three-dimensional fast spoiled gradient-echo maximum intensity projection pulse sequence, and postcontrast T1 maximum intensity projection images were also obtained to depict the renal anatomy. RESULTS: Split filtration fraction differentiated normal from hydronephrotic kidneys. MR renograms depicted vascular, tubular, and ductal phases and differentiated between normal and hydronephrotic kidneys (P < .05, n = 20). Contrast medium dose correlated with the peak of the cortical signal intensity curves on the renogram (r = 0.7, P < .0005; n = 20). The sensitivities for the visual determination of hydronephrosis and unilateral delayed excretion of contrast material were both 100%, and the specificities were 64% and 85%, respectively. CONCLUSION: The preliminary findings show promise for the use of MR urography in the comprehensive assessment of renal function, dynamics, and anatomy.

Adult↗
PubMed2001

Detection of motion in hybrid PET/SPECT imaging based on the correlation of partial sinograms.

This paper describes a motion detection method specific to hybrid positron emission tomography/single photon emission computed tomography systems. The method relies on temporal fractionation of the acquisition into three data sets followed by an algorithm based on the cross correlation (CC) of partial sinograms from successive sets at different rotations of the camera. Spatial inconsistencies due to motion are detected by decreases in the CC between two sets. This permits to separate data into premotion and postmotion sets of consistent data that are reconstructed independently then registered and summed. Rigid motions greater than 1-cm translation or 10 degrees rotation were detected with this method from experimental data obtained by manually moving phantoms made of radioactive spheres as well as from a patient lung study corrupted by artificial motion. The different motion studies showed that the image contrast does not seem to be a limiting factor and that the motion is best detected when the gantry is parallel to the direction of motion. The registration and fusion of the reconstructed premotion and postmotion sets lead in all cases to a reduction of the motion artifacts and an increase in signal-to-noise ratio.

Algorithms↗
PubMed1999

Acute cervical spine injuries: prospective MR imaging assessment at a level 1 trauma center.

PURPOSE: To determine the weighted average sensitivity of magnetic resonance (MR) imaging in the prospective detection of acute neck injury and to compare these findings with those of a comprehensive conventional radiographic assessment. MATERIALS AND METHODS: Conventional radiography and MR imaging were performed in 199 patients presenting to a level 1 trauma center with suspected cervical spine injury. Weighted sensitivities and specificities were calculated, and a weighted average across eight vertebral levels from C1 to T1 was formed. Fourteen parameters indicative of acute injury were tabulated. RESULTS: Fifty-eight patients had 172 acute cervical injuries. MR imaging depicted 136 (79%) acute abnormalities and conventional radiography depicted 39 (23%). For assessment of acute fractures, MR images (weighted average sensitivity, 43%; CI: 21%, 66%) were comparable to conventional radiographs (weighted average sensitivity, 48%; CI: 30%, 65%). MR imaging was superior to conventional radiography in the evaluation of pre- or paravertebral hemorrhage or edema, anterior or posterior longitudinal ligament injury, traumatic disk herniation, cord edema, and cord compression. Cord injuries were associated with cervical spine spondylosis (P < .05), acute fracture (P < .001), and canal stenosis (P < .001). CONCLUSION: MR imaging is more accurate than radiography in the detection of a wide spectrum of neck injuries, and further study is warranted of its potential effect on medical decision making, clinical outcome, and cost-effectiveness.

Acute Disease↗
PubMed1999

Spinal sonography and magnetic resonance imaging in patients with repaired myelomeningocele: comparison of modalities.

The goals of this study were to evaluate the feasibility of using ultrasonography of the spine in the follow-up evaluation of patients with repaired myelomeningocele at birth and to compare sonography with the accepted modality of magnetic resonance imaging. Over a period of 4 years we performed 165 sonographic studies in 101 patients; 107 sonographic studies had MR imaging results for comparison. We collected our data prospectively. The quality of the sonograms was good in 110 of 129 studies, acceptable in 17 of 129, and poor in two of 129. The sonographic examinations failed in 33 of 165 studies (20%). Concordant information was obtained between ultrasonography and magnetic resonance imaging in the following percentage of studies: level of the distal end of the cord in 82%, position of the cord in the canal in 59%, presence of hydromyelia in 63%, cord duplication in 96%, adhesions in 16%, intradural mass in 37%, cord measurements in 85%, and dural sac measurements in 83%. At the lumbosacral level, we saw no cord pulsation in 57% of the studies in patients with cord adhesions and in 20% of those without adhesions. At the lower thoracic level, we saw no pulsation in 35% of the studies in patients with cord adhesions and in 7% of those without adhesions. Postoperative studies of cord release surgery in eight patients showed varied findings. We conclude that in those patients who have a spinal defect or interlaminar space allowing proper visualization of the lumbosacral spinal canal, ultrasound can provide fairly similar information to that obtained with magnetic resonance imaging of that area with no need for sedation and at a reduced cost. Ultrasonography seems more sensitive than magnetic resonance imaging in the detection of cord adhesions, which is particularly relevant in the diagnosis of tethering.

Adolescent↗
PubMed1997

Impaired permeability in radiation-induced lung injury detected by technetium-99m-DTPA lung clearance.

UNLABELLED: This study evaluates the use of the 99mTc-DTPA aerosol lung clearance method to investigate radiation-induced lung changes in eight patients undergoing radiotherapy for lung or breast carcinoma. The sensitivity of the method was compared with chest radiography for detecting radiation-induced changes in the lung, regional alterations within (irradiated region) and outside (shielded region) the treatment ports, effect of irradiated lung volume, and dependence on time after radiotherapy. METHODS: Serial DTPA lung clearance studies were performed before the first radiation treatment (baseline), then weekly during a 5- to 7-wk course, and up to 12 times post-therapy over periods of 56-574 days. The total activity deposited in the lungs for each study was approximately 150 microCi (approximately 5.6 MBq). DTPA clearance, expressed in terms of the biological half-time, t 1/2, was computed from the slopes of the least-squares fit regression lines of the time-activity curves for the first 10 min for irradiated and shielded lung regions. RESULTS: Major findings include: (a) significant and early DTPA t 1/2 changes were observed in all patients during and after radiotherapy; (b) changes in DTPA t 1/2 values were observed in both irradiated and shielded lung regions in all patients suggesting a radiation-induced systemic reaction; (c) changes in DTPA t 1/2 values were correlated (p < 0.05) with the irradiated lung volumes; (d) significantly reduced DTPA t 1/2 values were observed in three patients who subsequently presented with clinical symptoms and/or radiographic changes consistent with radiation pneumonitis (t1/2 felt to 19% +/- 6% of baseline values, compared with 64% +/- 17% in the remaining patients [p < 0.01]); (e) the onset of decreased DTPA t 1/2 values in these three patients occurred 35-84 days before clinical symptoms and/or radiographic changes; and (f) DTPA t 1/2 tended to approach baseline values with time after radiotherapy, suggesting a long-term recovery in lung injury. CONCLUSION: These observations show significant and early alterations in DTPA lung clearance during and after radiotherapy that may provide a sensitive assay to monitor changes in radiation-induced lung injury and may facilitate early therapeutic intervention.

Aerosols↗
PubMed1996

Quantitative 123I IMP and 99mTc HMPAO imaging in the dog following cocaine administration.

SPECT and associated imaging procedures were used in beagle dogs to (1) evaluate the uptake, distribution, and clearance properties of i.v.-injected 123I IMP (IMP) and 99mTc HMPAO (HMPAO) in the brain, lungs, liver, and kidneys; (2) quantify the acute effects (after 15 sec) of very low doses (0.5 or 1.0 mg/kg) cocaine on the kinetics and localization properties of IMP and HMPAO; and (3) evaluate comparative imaging properties of IMP and HMPAO for measuring regional cerebral blood flow (rCBF). Regional and global uptake and localization of IMP or HMPAO were evaluated in control studies using dynamic planar (0-30 min) and SPECT imaging (at 35 min). The regional distribution properties of IMP and HMPAO in the brain were estimated from regions of interest (ROIs) drawn around anatomic structures on MR slices and manually registered with corresponding SPECT slices. Cocaine significantly reduced the 30-min IMP uptake in the brain and lungs by approximately 15%, but only slightly changed HMPAO uptake in the brain and other organs. In the control studies, the respective uptakes of IMP in the brain and lungs were 9 and 39% greater (p < 0.01) than those of HMPAO. In control SPECT studies, the highest uptake of IMP was observed in the thalamus and progressively less activity was observed in the parietal lobe, frontal lobe, cerebellum, occipital lobe, and entire brain; activity in the olfactory bulb was lower than in all other regions. Cocaine reduced IMP uptake in the cerebellum (p < 0.01), occipital lobe (p < 0.01), and entire brain (p < 0.05). IMP uptake (cpm/pixel-mCi) in the different brain regions was 1.3 to 2.1 times greater than that of HMPAO (p < 0.001). HMPAO uptake was more homogeneous throughout the gray matter of the brain; no significant uptake differences were observed among flagged regions. Results indicate that single, acute doses of cocaine, 0.5 and 1.0 mg/kg, significantly altered the uptake and localization properties of IMP in the dog's brain, lungs, liver, and kidneys. Variations in regional uptake of IMP in the parietal, frontal, and occipital lobes, cerebellum, and thalamus were greater than with HMPAO.

Amphetamines↗
PubMed1996

Transient effect of a short-term educational programme without prophylaxis on control of plaque and gingival inflammation in school children.

The development of chronic inflammatory periodontal diseases is strongly correlated with the growth and maturation of subgingival bacterial colonies. Consequently a major preventive goal should be the control of plaque formation. We conducted a randomized, controlled trial to examine the short-term effect of an intensive instructional program without professional prophylaxis on the gingival health of 240, 11-14 year old school children. Plaque index (PlI), gingival index (GI), bleeding index (BI) and probing pocket depth (PD) were examined 4 x by 1 examiner blinded to the instruction. During the period of instruction, subjects in the experimental groups were involved in a plaque and gingivitis prevention program provided in separate educational sessions. One of the experimental groups (E-1; n = 80) was provided with a new toothbrush, toothpaste and instruction while the second experimental group (E-2; n = 80) was provided with toothbrush, toothpaste, dental floss and instruction. In the control group (C; n = 80) only dental examinations were provided: no preventive program or oral health measures were conducted. Examinations were conducted every 3 months during the instructional period and at 6 months following the completion of the active preventive programme. During the experimental period there was a significant decrease (p < 0.001) in the mean PlI, GI and BI of the experimental groups following the program while in controls there was a slight but not significant increase of mean values (p > 0.05). During the preventive program experimental groups exhibited small but not significant (p > 0.05) reductions of PD. Experimental group 1 showed similar PlI, GI, BI and PD scores as experimental group 2 during the study. After the instructional program was completed and a period of 6 months had passed, there was a large and significant (p < 0.001) increase of mean PlI, GI and BI scores in both experimental groups back to the baseline levels. We conclude that a short-term preventative program without professional instrumentation induces a transient improvement of gingival health of schoolchildren but only during the instructional period. The maintenance of improved gingival health over longer time periods requires prolonged, repeated instruction by professionals. These measures may be difficult to institute and are of questionable cost-effectiveness.

Adolescent↗
PubMed1996

Bone age in children of diverse ethnicity.

OBJECTIVE: Determination of skeletal or bone age is often used in pediatrics and orthopedics. The most commonly used bone age standards in the United States, those published by Greulich and Pyle, were derived from white children of the upper socioeconomic class in 1931-1942. We examined whether these standards apply to the current assessment of bone age in children of diverse ethnicity. MATERIALS AND METHODS: Hand radiographs of children less than 19 years old at our institution were evaluated for bone age using the standards of Greulich and Pyle. Differences between bone age and chronologic age were calculated, and the mean differences were compared among subgroups of children on the basis of sex, age, and ethnicity. RESULTS: In Asian and white girls, bone age approximated chronologic age throughout childhood, with the only significant discrepancy being in adolescent white girls, in whom bone age exceeded chronologic age by an average of 4 months. In black girls, bone age exceeded chronologic age except during middle childhood. In late childhood and adolescence, bone age exceeded chronologic age by approximately 10 months. In Hispanic adolescent girls, bone age exceeded chronologic age by nearly 9 months. In black adolescent boys, bone age exceeded chronologic age by 5 months, with no significant discrepancies between bone age and chronologic age at other ages. In white preadolescent boys, bone age lagged behind chronologic age to a statistically significant degree, ranging from approximately 4 to 8 months. Preadolescent Asian boys also showed significant delays in bone age, particularly in middle childhood, when bone age lagged behind chronologic age by nearly 15 months. In adolescent Asian boys, bone age exceeded chronologic age by 9 months 15 days. In adolescent Hispanic boys, bone age exceeded chronologic age by 11 months 15 days. In younger Hispanic boys, delays in bone age occurred but were significant only in early childhood (4-month delay). CONCLUSION: Using the standards of Greulich and Pyle to determine bone age must be done with reservations, particularly in black and Hispanic girls and in Asian and Hispanic boys in late childhood and adolescence, when bone age may exceed chronologic age by 9 months to 11 months 15 days.

Adolescent↗
PubMed1995

Variation in antisperm antibody results using different assays.

PROBLEM: The detection of various types of antisperm antibodies (ASA) in the serum varies among different assays. This variation may influence the diagnosis and management of infertile couples who are tested for such immunologic factors. This prospective study was conducted to determine the variation in the results of ASA as measured by the sperm immobilization (SI), sperm agglutination (SA), and the indirect immunobead (IB) assays. METHOD: The sera of 79 patients that tested positive for ASA by at least one of the assays listed above were concurrently tested with all three assays. RESULTS: Using an individual ASA assay, 66 (84%), 26 (33%) or 36 (46%) of sera tested positive by the SA, SI, or IB assays, respectively. However, using a combination of assays, 67 (85%), 78 (99%) or 40 (51%) of sera tested positive using either the SA+SI, SA+IB or SI+IB assays, respectively. CONCLUSION: These findings suggest that the utilization of different assays to detect ASA may detect sera that are positive for ASA with more reliability than single assay testing.

Agglutination Tests↗
PubMed1994

Small animal imaging with pinhole single-photon emission computed tomography.

BACKGROUND: High resolution spatial details of the distribution of activity in three dimensions is required to evaluate the localization and dosimetric properties of radiolabelled monoclonal antibodies in tumors and normal tissues. Planar imaging of small animals with a resolution of 5-10 mm is usually the imaging modality of choice. The authors investigated high resolution single-photon emission computed tomographic (SPECT) imaging, based on a rotating pinhole scintillation camera. Although the sensitivity of the pinhole collimator is low, several radionuclides offer suitable decay properties to perform pinhole SPECT, especially in conjunction with high activity levels used in radioimmunotherapy. METHODS: Transverse, sagittal, and coronal sections were reconstructed using a three-dimensional cone-beam algorithm, which is a generalization of the two-dimensional fan-beam filtered backprojection algorithm. Before reconstruction, the pinhole projections were corrected for the decay of the radionuclide, geometric and intrinsic efficiency variations of the camera system, and center of rotation shift. RESULTS: The spatial resolution at 50 mm from the pinhole collimator with 3.3 mm aperture was 3.4 mm, and the sensitivity 7.2 c/s microCi for technetium-99m. With the 2 mm collimator the resolution was 2.2 mm, and the sensitivity was 2.6 c/s/microCi. To show the spatial resolution in vivo, a rat was injected with 185 MBq of technetium-99m-methylene diphosphonate or with 5 mCi technetium-99m-hexamethylpropylene amine oxime. The bone structures were well delineated in the methylene diphosphonate image, and in the hexamethylpropylene amine oxime image, the brain was nicely shown. For comparison a magnetic resonance image for the same section was done. CONCLUSIONS: High resolution SPECT imaging with the pinhole collimator provides mapping of the activity in three-dimensions, needed for more detailed biodistribution data and to perform more accurate dosimetry.

Algorithms↗
PubMed1994

Correlative image registration.

Image registration in nuclear medicine and radiology refers to the spatial matching or merging of two or more images from the same or different imaging modalities. The coordinates of the corresponding picture elements (pixels) from different images are transformed to align and equate their positions and spatial coordinates. Correlative image registration is a more restrictive term that applies to the matching of spatial coordinates of images coming from different imaging modalities. The registration of correlative images provides a useful approach to combine the best sensitivities and specificities of complementary procedures to detect, locate, monitor, and measure pathological and other physical changes. Here we review the registration of images from nuclear medicine (single-photon emission computed tomography, positron emission tomography and planar imaging) with those from other imaging modalities (magnetic resonance imaging, computed tomography, digital subtraction angiography and ultrasound) to closely correlate changes in metabolism, blood flow, receptor density, and other functional measurements with regional anatomy and morphological changes. The types of image registration applications, techniques, and terminology associated with image registration and examples of application are presented.

Angiography, Digital Subtraction↗
PubMed1994

Feasibility of dual radionuclide brain imaging with I-123 and Tc-99m.

A study was conducted to evaluate the feasibility of simultaneous dual radionuclide brain imaging with 123I and 99mTc using photopeak image subtraction techniques or offset photopeak image acquisition. The contribution of the photons from one radionuclide to a second radionuclide's photopeak energy window (crosstalk) was evaluated for SPECT and planar imaging of a brain phantom containing 123I and 99mTc for a range of activity levels and distribution properties approximating those in rCBF images of the adult human brain. Crosstalk was evaluated for 10% symmetrical energy windows centered on the 123I and 99mTc photopeaks and for 10% energy windows asymmetrically placed to the left and right of the center of the respective photopeaks. Major observations include: (1) in the centered photopeak windows, 99mTc crosstalk in the 123I window is 8.9% of the 99mTc seen in the 99mTc window and ranges from 37.5% to 75.0% of the 123I in the 123I window. 123I crosstalk is 37.8% of the 123I seen in the 123I window and ranges from 4.4% to 8.9% of the 99mTc seen in the 99mTc window; (2) the spatial distribution of a radionuclide's crosstalk photons differs from that observed in the radionuclide's photopeak window; (3) a 99mTc photopeak window offset to the left does not decrease 123I crosstalk, and the percentage of 99mTc scattered photons is significantly increased in the window.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Pinhole SPECT: an approach to in vivo high resolution SPECT imaging in small laboratory animals.

UNLABELLED: The performance of pinhole SPECT and the application of this technology to investigate the localization properties of radiopharmaceuticals in vivo in small laboratory animals are presented. METHODS: System sensitivity and spatial resolution measurements of a rotating scintillation camera system are made for a low-energy pinhole collimator equipped with 1.0-, 2.0- and 3.3-mm aperture pinhole inserts. The spatial detail offered by pinhole SPECT for in vivo imaging was investigated in studies of the brain and heart in Fisher 344 rats by administering 201TICI, 99mTc-HMPAO, 99mTc-DTPA and 99mTc-MIBI. Image acquisition is performed using a rotating scintillation camera equipped with a pinhole collimator; projection data are acquired in conventional step-and-shoot mode as the camera is rotated 360 degrees around the subject. Pinhole SPECT images are reconstructed using a modified cone-beam algorithm developed from a two-dimensional fanbeam filtered backprojection algorithm. RESULTS: The reconstructed transaxial resolution of 2.8 mm FWHM and system sensitivity of 0.086 c/s/kBq with the 2.0-mm pinhole collimator aperture provide excellent spatial detail and adequate sensitivity for imaging the regional uptake of the radiopharmaceuticals in tumor, organs and other tissues in small laboratory animals. CONCLUSION: The resolution properties of pinhole SPECT are superior to those which have been achieved thus far with conventional SPECT or PET imaging technologies. Pinhole SPECT provides an important approach for investigating localization properties of radiopharmaceuticals in vivo.

Animals↗
PubMed1993

High resolution pinhole SPECT for tumor imaging.

High-resolution, non-invasive, 3D-imaging techniques would greatly benefit the investigation of the localization properties of tumor-specific radiopharmaceuticals in laboratory animals. The present study reports how pinhole SPECT can be applied to tumor localization studies in small laboratory animals to provide high resolution SPECT images in vivo. Pinhole SPECT was performed using a rotating scintillation camera, equipped with a pinhole collimator. The sensitivity of a 2 mm diameter collimator at 45 mm from the source is 90 cps/MBq for 99mTc. The planar spatial resolution at a 45 mm distance is 2.2 mm. The transaxial spatial resolution, with a distance of 45 mm between the collimator aperture and the axis of rotation, is 3.1 mm. For SPECT imaging, spatial linearity is preserved across the usable field-of-view. The major advantage of the high resolution properties of pinhole tomography is demonstrated by the enhanced lesion-to-normal-brain uptake ratio achieved on tomographic slices as compared to planar images. For example, 201Tl tumor-to-normal-brain uptake ratios of 1.1 to 1.3 observed on planar images, corresponded to ratios ranging from 3.2 to 3.7 on the SPECT slices. Examples of the activity distributions of two radiopharmaceuticals in tumor and in normal brain for sagittal and coronal images are given. In all cases, tumors are clearly delineated on the pinhole SPECT slices. The present study shows that pinhole SPECT performed with standard SPECT instrumentation can give high spatial resolution images, with a FWHM approximately 3 mm and a sensitivity approximately 100 cps/MBq for 99mTc.

Animals↗
PubMed1993

SPECT and planar brain imaging in crack abuse: iodine-123-iodoamphetamine uptake and localization.

The uptake, distribution, and clearance properties of 123I-IMP in the brain were evaluated in controls and asymptomatic crack users to investigate cerebral blood flow alterations in crack abuse. Serial dynamic planar images of the brain (0-25 min), SPECT of the brain (0.5 hr and 4 hr) and whole-body scans (75 min) were obtained in 21 crack abusers and 21 control subjects. Major observations include: (a) foci of abnormally reduced 123I-IMP activity mainly in the frontal and parieto-occipital cortex or marked irregularities in the uptake of 123I-IMP throughout the cerebral cortex consistent with moderate to severe disruption in regional cerebral blood flow were observed on the 0.5 hr SPECT images of 16/21 asymptomatic crack users; (b) no correlation could be demonstrated between the incidence or severity of SPECT perfusion abnormality with the frequency, amount or length of time of crack use; (c) focal perfusion defects observed in 6/21 crack users on the 0.5-hr SPECT images partially or completely filled-in on delayed SPECT at 4 hr in four of six subjects; (d) the rate of cerebral uptake of 123I-IMP in crack users averaged 23% less than observed in control subjects over the first 25 min after tracer administration; and (e) 123I-IMP activity reaching the brain of cigarette smoking control subjects (n = 14) at 25 min after injection averaged 42.5% less than in nonsmoking controls (n = 7). Quantitative measurements of the uptake and distribution properties of 123I-IMP in the brain proved to be an objective, sensitive and useful measure of regional cerebral blood flow in crack abuse.

Adult↗
PubMed1991

Cerebellar metabolic activation by delta-9-tetrahydro-cannabinol in human brain: a study with positron emission tomography and 18F-2-fluoro-2-deoxyglucose.

We investigated the effects of acute i.v. administration of 2 mg of delta 9-tetrahydrocannabinol (THC) on regional brain glucose metabolism using 18F-2-fluoro-2-deoxyglucose and positron emission tomography (PET) in eight normal subjects. Subjects were tested twice: during baseline conditions and 30-40 min after THC administration. Changes in global cerebral glucose metabolism in response to THC were variable: three subjects showed an increase, three showed a decrease, and two showed no change. In contrast, all subjects showed an increase in normalized metabolism in the cerebellum following THC administration. Cerebellar changes were the only significant regional metabolic changes due to THC administration. The increase in metabolic activity in the cerebellum was correlated with the subjective sense of THC intoxication and with plasma THC concentration. Cerebellar localization of metabolic effects due to THC administration corresponds well with the high density of cannabinoid receptors known to be in this area.

Adult↗
PubMed1991

Effects of visual stimulation on the redistribution of iodine-123-IMP in the brain using SPECT imaging.

A study was performed to validate the assumption that redistribution and clearance of [123I]IMP localization in the brain are unaffected by changes in ambient light levels and visual stimulation occurring after radiopharmaceutical is administered and deposited in the brain. Serial SPECT and planar imaging studies were performed on six healthy, volunteer, adult male subjects under resting, nonactivation conditions. Studies were repeated 7 days later with each subject exposed to strobe light stimulation prior to delayed SPECT procedures at 3 hr. Redistribution and clearance of 123I-IMP in the brain were examined in cortical, subcortical, and cerebellar regions on transaxial slices for the two sets of serial procedures in each subject. Visual stimulation following the initial uptake of [123I]IMP did not affect the distribution or clearance of [123I]IMP in the brain, including the visual cortex, and therefore should not influence the interpretation of delayed SPECT images.

Adult↗