Search PubMed⌕ Search

Biomedical subjects

S A Larsson

Publications and source records attributed to S A Larsson.

At least 19 recordsLinked to original sources
PubMed2003

Early assessment of neoadjuvant chemotherapy by FEC-courses of locally advanced breast cancer using 99mTc-MIBI.

PURPOSE: Response assessment at neoadjuvant (preoperative) chemotherapy of locally advanced breast cancer using clinical examination and mammography is insensitive. Mammoscintigraphy with 99mTc-MIBI was studied for the prediction of response at such therapy before finishing the chemotherapy cycles. MATERIAL AND METHODS: Chemotherapy was given as repeated courses of 5-fluorouracil, epirubicin and cyclophosphamide (FEC). In 1 patient group (n = 23), the tumor uptake relative to surrounding breast tissue and lung tissue at SPECT examination after finishing neoadjuvant chemotherapy was compared with the examination made before chemotherapy. In another group (n = 30), a similar comparison after the first therapy cycle (mean 19 days) with a baseline examination was made. Histologic examination of the resected tumors was made. RESULTS: After finishing chemotherapy, there was a strong reduction of the relative tumor activity, while there was no correlation with therapy effect as assessed by histology. After one therapy course, there was no significant reduction of the relative tumor uptake. CONCLUSION: Scintigraphy with 99mTc-MIBI demonstrated the response after finished neoadjuvant chemotherapy of breast cancer using FEC-courses. It cannot be used to predict a therapy response after one therapy course.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2002

Differences in resting state regional cerebral blood flow assessed with 99mTc-HMPAO SPECT and brain atlas matching between depressed patients with and without tinnitus.

An increased occurrence of major depressive disorder has been reported in tinnitus patients, and of tinnitus in depressive patients. Involvement of several Brodmann areas (BAs) has been reported in tinnitus perception. The aim of this study was to assess the regional cerebral blood flow (rCBF) changes in depressed patients with and without tinnitus. The rCBF distribution at rest was compared among 45 patients with a lifetime prevalence of major depressive disorder, of whom 27 had severe tinnitus, and 26 normal healthy subjects. 99mTc-hexamethylenepropylene amine oxime (99mTc-HMPAO) single photon emission computed tomography (SPECT), using a three-headed gamma camera, was performed and the uptake in 34 functional sub-volumes of the brain bilaterally was assessed by a computerized brain atlas. Decreased rCBF in right frontal lobe BA 45 (P<0.05), the left parietal lobe BA 39 (P<0.00) and the left visual association cortex BA 18 (P<0.05) was found in tinnitus patients compared with non-tinnitus patients. The proportion of tinnitus patients with pronounced rCBF alterations in one or more of the temporal lobe BAs 41+21+22 was increased compared to gender matched controls (P<0.00) and patients without tinnitus (P<0.05). Positive correlations were found between trait anxiety scales from the Karolinska Scales of Personality and rCBF in tinnitus patients only in three limbic BAs (P<0.01), and inverse correlations in non-tinnitus patients only in five BAs subserving auditory perception and processing (P<0.05). rCBF differences between healthy controls and depressed patients with and without tinnitus were found in this study. The rCBF alterations were distributed in the cortex and were particularly specific in the auditory cortex. These findings suggest that taking audiological symptoms into account may yield more consistent results between rCBF studies of depression.

Age Factors↗
PubMed2001

SPET imaging of central muscarinic acetylcholine receptors with iodine-123 labelled E-IQNP and Z-IQNP.

1-Azabicyclo[2.2.2]oct-3-yl alpha-hydroxy-alpha-(1-iodo-1-propen-3-yl)-alpha-phenylacetate (IQNP) is a muscarinic acetylcholine receptor (mAChR) antagonist and the racemic ligand contains eight stereoisomers. In a single-photon emission tomography (SPET) study in monkeys we recently confirmed that [123I]E-(R,R)-IQNP ([123I]E-IQNP) is a radioligand with modest selectivity for the M1 and M4 subtypes, whereas [123I]Z-(R,R)-IQNP ([123I]Z-IQNP) is non-subtype selective. In the present SPET study, E- and Z-IQNP were examined in human subjects. SPET examination was performed on three male subjects after i.v. injection of [123I]E-IQNP and in another three after i.v. injection of [123I]Z-IQNP. The binding potential (BP) for [123I]E-IQNP was calculated using several quantitative approaches with the cerebellum as a reference region. High-performance liquid chromatography was used to measure radioligand metabolism in plasma. Following [123I]E-IQNP, the radioactivity was high in the neocortex and striatum, intermediate in the thalamus and low in the pons and cerebellum, which is consistent with the rank order for the regional density of M1 and M4 subtypes in vitro. For all regions, peak equilibrium was identified within the 48-h data acquisition. The simplified reference tissue approach using SPET data from 0 to 48 h was the most reliable in this limited series of subjects. Following injection of [123I]Z-IQNP, radioactivity was high in the neocortex and striatum, intermediate in the thalamus and pons and low in the cerebellum, which is in agreement with the density of M1, M2 and M4 subtypes as measured in vitro. Quantitative analyses provided indirect support for specific M2 binding of Z-IQNP in the cerebellum. The high selectivity of [123I]E-IQNP for M1 and M4 receptors allowed the use of cerebellum as a reference region devoid of specific binding, and may be advantageous for applied clinical studies of M1 and M4 receptors binding in man. [123I]Z-IQNP has potential for exploration of M2 receptor binding in the cerebellum.

Adult↗
PubMed2001

A spatially varying compton scatter correction for SPECT utilizing the integral Klein-Nishina cross section.

An algorithm correcting for the fraction of scattered events in SPECT and planar imaging is proposed. The algorithm utilizes a pixel-based multi-channel analyser for data acquisition. The method was designed to operate on a local level by three subtraction steps: (a) Subtracting a modified Klein-Nishina single scatter distribution, pixel by pixel, from the events obtained experimentally in the upper half of the photo-peak window. (b) Subtracting a mirrored distribution of the unscattered events hence obtained from that of total events in the lower half of the window, thus giving the scatter distribution in this part of the window. (c) Subtracting the sum of the scatter distributions in both window halves from the corresponding sum of total events in order to obtain the unscattered photons within the photo-peak window. The accuracy of the method was validated experimentally, using a new rCBF phantom allowing for imaging in matter corresponding to soft tissue and approximately in air, respectively. After correction for photon scattering and attenuation, the regional difference in SPECT values in soft tissue equivalent matter and in low-density matter (simulating air) was only 1.5 +/- 7.2% (mean +/- 1 SD), thus indicating a high accuracy of the correction method. Provided that an accurate and stable pixel peak-alignment routine is available, the method can be applied using a minimum of three windows.

Algorithms↗
PubMed2001

High continuous positive airway pressure level induces ventilation/perfusion mismatch in the prone position.

OBJECTIVE: Gas exchange in patients with adult respiratory distress syndrome is influenced by posture. The combined effect of continuous positive airway pressure and posture has not been investigated. We studied the effect of normal spontaneous breathing, and that of continuous positive airway pressure, on ventilation/perfusion distributions in healthy volunteers while they were in supine and prone positions. SETTING: Nuclear medicine department in a university hospital. DESIGN: Experimental study. SUBJECTS: Sixteen healthy volunteers. INTERVENTIONS: In the supine or prone position, the subjects inhaled a technetium-labeled aerosol (technetium-99m diethylenetriamine pentaacetic acid) through a tight-fitting mask. Single photon emission computed tomography images of the lungs were obtained. The subjects then received an intravenous injection of technetium-99m-labeled macroaggregates of albumin, and an identical single photon emission computed tomography imaging was performed. In the group that received continuous positive airway pressure, an end-expiratory pressure of 10 cm H2O was applied during both inhalation and injection. MEASUREMENTS AND MAIN RESULTS: During spontaneous breathing, ventilation/perfusion distribution assessed by regression analysis was uniform (i.e., not significantly different from zero) both in supine and prone positions, with a slope of -1.5 +/- 3.5%/cm supine and 1.5 +/- 3.5%/cm prone. During continuous positive airway pressure breathing in the supine position, ventilation/perfusion had a slope of -3.4 +/- 2.4 compared with 8.3 +/- 1.1%/cm in the prone position according to analysis of spatial resolution. CONCLUSION: There was a less favorable ventilation/perfusion ratio in the prone position when the subjects were exposed to continuous positive airway pressure of 10 cm H2O.

Adult↗
PubMed2001

Localization of sentinel nodes in head and neck tumours by combined lymphoscintigraphy and bone scintigraphy.

Sentinel node scintigraphy in tumours of the head and neck region was combined with bone scintigraphy to provide anatomical landmarks in order to better locate the lymph node uptake. 99Tc(m)-nanocolloid (40 MBq) was injected in the peritumour region 1 h after the administration of bone-seeking 99Tc(m)-methylene diphosphonate (200 MBq). After 5 min, A-P and lateral projections of the head and neck region were acquired. In all the 26 patients examined, the surrounding anatomy was clearly depicted. In 23 patients, the lymphatic drainage was identified within 30 min. In these patients, all hot spots appearing outside the deposited activity could be located according to the neck region classification system of the Memorial Sloan-Kettering Hospital. No lymphatic drainage was visualized in the remaining three patients. The injection of bone-seeking activity 1 h before deposition of the radiocolloid provided images visualizing soft tissues as well as skeletal structures, thus improving the topical diagnosis. Correlation with the results of surgery was not performed. The administration of a small amount of bone-seeking activity prior to sentinel node scintigraphy of head and neck tumours improves the anatomical localization of the lymph node activity.

Adult↗
PubMed2000

Z-IQNP: a potential radioligand for SPECT imaging of muscarinic acetylcholine receptors in Alzheimer's disease.

RATIONALE: The density of the M2 subtype of muscarinic acetylcholine receptors (mAChR) has been shown to be reduced in the brain of patients with Alzheimer's disease (AD). It is therefore of interest to develop a brain imaging method for diagnostic purposes. Z-(R,R)-1-azabicyclo[2.2.2]oct-3-yl alpha-hydroxy-alpha-(1-iodo1-propen-3-yl)-alpha-phenylacetat e (Z-IQNP) is a muscarinic antagonist with high affinity for the M2 subtype. OBJECTIVE: The pharmacological characteristics and topographic distribution of radiolabelled Z-IQNP as a radioligand for the M2 mAChR subtype were examined in vitro and in vivo. METHODS: Z-IQNP was labelled with 1251 and 123I. Autoradiography was performed on whole-hemisphere cryosections from human post mortem brains. SPECT was performed in a cynomolgus monkey. RESULTS: Autoradiography showed binding of [125I]Z-IQNP in all brain regions, which was inhibited by the non-selective muscarinic antagonist scopolamine. The addition of BIBN 99, a compound with high affinity for the M2 subtype, inhibited [125I]Z-IQNP binding particularly in the cerebellum, which has a high density of the M2 subtype. SPECT demonstrated high uptake of [123I]Z-IQNP in all brain regions. The binding was markedly reduced in all brain regions after pretreatment with the non-selective muscarinic antagonist dexetimide and also the M1 antagonist biperiden. Dexetimide markedly inhibited [123I]Z-IQNP binding in the cerebellum, which is consistent with a high density of M2-receptors in this region. The sigma receptor binding compound DuP 734 had no effect on Z-IQNP binding either in vitro or in vivo. CONCLUSIONS: This study indicates that radiolabelled Z-IQNP has high specificity for mAChR with higher affinity for the M2 than the M1 subtype and negligible affinity for sigma recognition sites both in vitro and in vivo. [123I]Z-IQNP should be useful for future SPECT studies in AD for examination of the density of M2 receptors particularly in the cerebellum.

Alzheimer Disease↗
PubMed2000

A novel phantom design for emission tomography enabling scatter- and attenuation-"free" single-photon emission tomography imaging.

A newly designed technique for experimental single-photon emission tomography (SPET) and positron emission tomography (PET) data acquisition with minor disturbing effects from scatter and attenuation has been developed. In principle, the method is based on discrete sampling of the radioactivity distribution in 3D objects by means of equidistant 2D planes. The starting point is a set of digitised 2D sections representing the radioactivity distribution of the 3D object. Having a radioactivity-related grey scale, the 2D images are printed on paper sheets using radioactive ink. The radioactive sheets can be shaped to the outline of the object and stacked into a 3D structure with air or some arbitrary dense material in between. For this work, equidistantly spaced transverse images of a uniform cylindrical phantom and of the digitised Hoffman rCBF phantom were selected and printed out on paper sheets. The uniform radioactivity sheets were imaged on the surface of a low-energy ultra-high-resolution collimator (4 mm full-width at half-maximum) of a three-headed SPET camera. The reproducibility was 0.7% and the uniformity was 1.2%. Each rCBF sheet, containing between 8.3 and 80 MBq of 99mTcO4- depending on size, was first imaged on the collimator and then stacked into a 3D structure with constant 12 mm air spacing between the slices. SPET was performed with the sheets perpendicular to the central axis of the camera. The total weight of the stacked rCBF phantom in air was 63 g, giving a scatter contribution comparable to that of a point source in air. The overall attenuation losses were <20%. A second SPET study was performed with 12-mm polystyrene plates in between the radioactive sheets. With polystyrene plates, the total phantom weight was 2300 g, giving a scatter and attenuation magnitude similar to that of a patient study. With the proposed technique, it is possible to obtain "ideal" experimental images (essentially built up by primary photons) for comparison with "real" images degraded by photon scattering and attenuation losses. The method can serve as a tool for experimental validation and intercomparison of attenuation and scatter correction methods. Moreover, the large flexibility of this phantom design will allow investigations of arbitrary activity distributions and autoradiography or other imaging techniques such as PET, x-ray computed tomography or magnetic resonance imaging.

Brain↗
PubMed2000

What is the message of a meeting? Analysis and comparison of the 2458 abstracts of the EANM/WCNMB congress in Berlin and the SNM meeting in Toronto in 1998. European Association of Nuclear Medicine/World Federation of Nuclear Medicine and Biology, and the Society of Nuclear Medicine.

The abstracts of the joint congress of EANM/WCNMB in Berlin 1998 and of the 45th Annual Meeting of the Society of Nuclear Medicine in Toronto 1998 have been analysed and compared in terms of comprehensibility, composition, questions at issue, methods, patient/subject number, type of conclusion and duplication of information between the meetings. All 1362 and 1096 abstracts, respectively, were analysed from the abstract books with regard to ten "hard" and four "soft" variables. The dominant topics were new radiopharmaceuticals, methods of synthesis, examination methods, evaluation of examinations, investigation algorithms, technical devices and novel use of radiopharmaceuticals. In addition to these topics, there were numerous reports about established radiopharmaceuticals and techniques, often without a specific merit mentioned. There were also many abstracts with questions outside nuclear medicine, but using such techniques. Few papers reported negative findings or dealt with quality assurance, dosimetry, and cost-effectiveness. Many of the conclusions contained hyperbole. Some abstracts were very extensive and detailed. Sixty-seven contributions conveyed identical information at both meetings. Structured and/or paragraphed abstracts promote clarity and reduce the number of lines that need to be read in order to comprehend the background and aim of the abstract. Such contributions were more frequent at the EANM/WCNMB congress while the SNM meeting covered a wider field with a greater representation of radiophysics, instrumentation, and computer evaluations.

Abstracting and Indexing↗
PubMed2000

Effects of acute hypobaric hypoxia on regional cerebral blood flow distribution: a single photon emission computed tomography study in humans.

Single Photon Emission Computed Tomography (SPECT) and radiopharmaceutical stabilizing agents allowed us to investigate regional cerebral blood flow (CBF) distribution in six resting healthy subjects during acute laboratory hypobaric hypoxic conditions. In the hypobaric experiment stabilized 99mTc-D, L-hexamethyl-propylene amine oxime was injected 40 min after reaching hypoxic conditions corresponding to an altitude of 5500 m above sea level. Arterial blood sample was taken after five additional minutes. Mean arterial oxygen pressure and haemoglobin saturation were 28 mmHg and 56%, respectively. The control experiment was performed similarly, apart from barometric pressure and blood gas analysis. We analysed CBF distribution in 12 regions of functional interest bilaterally in frontal, parietal, temporal, occipital cortex, in the hippocampus, in the basal ganglia and other central structures of brain. No overall effect of hypoxia on normalized regional CBF distribution in the considered regions was found. Motor cortex (Brodmann 4) and basal ganglia were the only regions in which hypobaric hypoxia significantly increased relative distribution of the radiopharmaceutical [F(1,5)=18.30; P < 0.008 and F(1,5)=10.85; P < 0.022, respectively]. Despite severe hypoxia, we did not observe any major regional CBF redistribution. We found a small relative increase in blood flow to the motor cortex and the basal ganglia, at rest after 40 min of hypobaric hypoxia, suggesting a preferential compensatory mechanism of these functional regions of brain.

Acute Disease↗
PubMed2000

Reproducibility and repeatability of 99Tcm-HMPAO rCBF SPET in normal subjects at rest using brain atlas matching.

The aim of this study was to assess regional cerebral blood flow (rCBF) in normal subjects at rest using 99Tcm-HMPAO single photon emission tomography (SPET). Analysis of reproducibility and repeatability was performed both before and after normalization of flow data. Six healthy volunteers were examined, three times each, according to a routine rCBF protocol. A computerized brain atlas was used to evaluate flow data in eight selected regions. The overall reproducibility of rCBF was evaluated from two scans performed at an average interval of 3 months. Repeatability was evaluated from two scans, 3 h apart and without re-injection of 99Tcm-HMPAO. For the normalized (relative) flow data, the reproducibility was +/- 1.3% and the repeatability +/- 2.2% (i.e. methodological errors dominate). For the non-normalized flow data, the corresponding values were +/- 14.8% and +/- 5.9%. rCBF SPET with 99Tcm-HMPAO is highly reproducible provided that the flow data are normalized. The variation in flow between individuals at one point in time and 3 months later was less than +/- 5% for all brain regions.

Adult↗
PubMed2000

A comparison of 99Tcm-MDP and 99Tcm-MIBI in the detection of breast cancer.

In this study, we made an intra-individual comparison of the uptake of 99Tcm-MDP and 99Tcm-MIBI in breast cancer. Twenty women with large breast masses (one dimension > or = 3 cm on mammography) underwent SPET in the supine position with both agents. All transverse sections demonstrating tumour activity were added together and the net (total) tumour uptake in a region of interest was compared to that of surrounding tissue activity (background). We also evaluated maximum tumour uptake versus background activity. Tumour uptake was observed in all examinations. In contrast to MIBI, eight MDP examinations showed increased uptake in normal breast parenchyma in addition to tumour uptake. There was no significant difference in net tumour uptake between the two tracers and non-parenchymal (indifferent) background activity, but the maximum tumour activity of MIBI was significantly higher than that of MDP. In the eight MDP examinations with parenchymal activity, mammograms were required to identify tumour uptake correctly. In conclusion, MDP may provide similar images to MIBI in postmenopausal women not receiving hormone replacement therapy. For other patients, MIBI gives better tumour depiction.

Adult↗
PubMed2000

Diclofenac treatment prolongs renal transit time in acute ureteral obstruction: a renographic study.

OBJECTIVE: Prostaglandin inhibitors, mostly diclofenac, are currently first-choice therapy for ureteral colic, their main action being reduction of intrapelvic pressure and diuresis. We hypothesized that diclofenac, by increasing tubular reabsorption, can delay excretion of contrast medium and give a false impression of severe obstruction. METHODS: Gamma camera renography was performed with 50 MBq (99)Tc(m)-MAG3 before and with 150 MBq 30 min after intramuscular injection of 75 mg diclofenac in 10 patients with acute ureteral colic. The time to maximum isotope activity in each kidney, T(max), was compared with T(max) in 10 control patients, who did not receive diclofenac but underwent two identical renographies. RESULTS: T(max) was significantly delayed after diclofenac, from 353 s at baseline to >1,200 s on the stone side, and from 225 to 465 s on the healthy side. Without diclofenac there was no T(max) retardation between the two renographies. CONCLUSION: Diclofenac treatment can lead to overestimation in ureteral stone disease, by delaying renal excretion bilaterally, but predominantly on the side of calculus.

Acute Disease↗
PubMed1999

Pulmonary perfusion is more uniform in the prone than in the supine position: scintigraphy in healthy humans.

The main purpose of this study was to find out whether the dominant dorsal lung perfusion while supine changes to a dominant ventral lung perfusion while prone. Regional distribution of pulmonary blood flow was determined in 10 healthy volunteers. The subjects were studied in both prone and supine positions with and without lung distension caused by 10 cmH2O of continuous positive airway pressure (CPAP). Radiolabeled macroaggregates of albumin, rapidly trapped by pulmonary capillaries in proportion to blood flow, were injected intravenously. Tomographic gamma camera examinations (single-photon-emission computed tomography) were performed after injections in the different positions. All data acquisitions were made with the subject in the supine position. CPAP enhanced perfusion differences along the gravitational axis, which was more pronounced in the supine than prone position. Diaphragmatic sections of the lung had a more uniform pulmonary blood flow distribution in the prone than supine position during both normal and CPAP breathing. It was concluded that the dominant dorsal lung perfusion observed when the subjects were supine was not changed into a dominant ventral lung perfusion when the subjects were prone. Lung perfusion was more uniformly distributed in the prone compared with in the supine position, a difference that was more marked during total lung distension (CPAP) than during normal breathing.

Adult↗
PubMed1999

The somatostatin analogue octreotide inhibits neuroblastoma growth in vivo.

Neuroblastoma, a neural crest-derived childhood tumor of the sympathetic nervous system, may in some cases differentiate to a benign ganglioneuroma or regress due to apoptosis. However, the majority of neuroblastomas are diagnosed as metastatic tumors with a poor prognosis despite intensive multimodal therapy. The neuropeptide somatostatin (SOM) has been shown to inhibit neuroblastoma growth and induce apoptosis in vitro. Therapeutic effects of SOM analogues are dependent on tumor expression of high-affinity receptors. In the present study, human neuroblastoma SH-SY5Y cells were grown as xenografts in nude rats. In vivo SOM receptor expression in the xenografts was identified using scintigraphy with 111In-pentetreotide. Rats were randomized to treatment with the long-acting SOM analogue octreotide (10 microg s.c. every 12 h), 13-cis-retinoic acid (4 mg orally every 24 h), or vasoactive intestinal peptide (40 microg s.c. every 24 h) and compared with controls. Tumor volume was assessed every second day and tumor weight after 10-12 d. Octreotide treatment inhibited neuroblastoma growth significantly with reduced tumor volumes at 10 and 12 d compared with untreated controls (mean 3.56 and 4.24 versus 6.48 and 8.01 mL, respectively; p < 0.01). Also, tumor weights after 10-12 d were reduced in octreotide-treated animals (n = 8, median weight 2.90 g, range 1.67-5.57 g) compared with untreated rats (n = 14, 7.54 g, 1.65-10.82 g, p = 0.005). Serum IGF-I decreased significantly over time both in rats treated with octreotide and in untreated controls. It is concluded that treatment with the SOM analogue octreotide may significantly decrease neuroblastoma tumor growth in vivo. Further studies are warranted to establish the role of SOM analogues in the treatment of children with unfavorable neuroblastoma.

Animals↗
PubMed1999

Concentration of 123I-metaiodobenzylguanidine in left and right liver lobes. Findings indicate regional differences in function in the normal liver.

PURPOSE: Normal radioactivity in the liver is often shown to be higher in the left lobe than in the right lobe at clinical examination by single photon emission computed tomography (SPECT) with 123I-metaiodobenzylguanidine (123I-MIBG). Our objective was to determine whether this represents a pathological condition. MATERIAL AND METHODS: The distribution of 123I-MIBG in the liver was retrospectively studied in clinical patients who had normal CT examinations of the liver and spleen. In the SPECT sections of 27 123I-MIBG examinations, we determined the activity ratios between the left and right lobes. The control group comprised 33 examinations with (111)In-pentetreotide (OctreoScan) and 23 examinations with 99mTc-antigranulocyte antibody. RESULTS: The mean activity ratio between left and right lobes for 123I-MIBG was 1.24, and for (111)In-pentetreotide 0.87. These figures differed significantly both from each other and from 1.00. The mean ratio for 99mTc-antibody at the early examinations was 0.99, and at the late examinations 0.95. These figures differed significantly from the values for 123I-MIBG and (111)In-pentetreotide. CONCLUSION: The increased concentration of 123I-MIBG in the left lobe of the liver compared to the right lobe is a normal finding. The reason for this cannot be explained. The difference in the way in which the left and right lobes deal with the three radiopharmaceuticals is a new finding and indicates a regional difference in liver function that has not been reported previously.

3-Iodobenzylguanidine↗
PubMed1998

Resting state rCBF mapping with single-photon emission tomography and positron emission tomography: magnitude and origin of differences.

Single-photon emission tomography (SPET), using technetium-99m hexamethylpropylene amine oxime, and positron emission tomography (PET), using oxygen-15 butanol were compared in six healthy male volunteers with regard to the mapping of resting state regional cerebral blood flow (rCBF). A computerized brain atlas was utilized for 3D regional analyses and comparison of 64 selected and normalized volumes of interest (VOIs). The normalized mean rCBF values in SPET, as compared to PET, were higher in most of the Brodmann areas in the frontal and parietal lobes (4.8% and 8.7% respectively). The average differences were small in the temporal (2. 3%) and occipital (1.1%) lobes. PET values were clearly higher in small VOIs like the thalamus (12.3%), hippocampus (12.3%) and basal ganglia (9.9%). A resolution phantom study showed that the in-plane SPET/PET system resolution was 11.0/7.5 mm. In conclusion, SPET and PET data demonstrated a fairly good agreement despite the superior spatial resolution of PET. The differences between SPET and PET rCBF are mainly due to physiological and physical factors, the data processing, normalization and co-registration methods. In order to further improve mapping of rCBF with SPET it is imperative not only to improve the spatial resolution but also to apply accurate correction techniques for scatter, attenuation and non-linear extraction.

Adult↗