Tc-99m HMPAO Research Articles

Bio-distribution study of Tc-99m HMPAO labeled platelet in healthy volunteer.

The bio-distribution of Tc-99m HMPAO labeled platelets (LP), which could be used to image subtle thrombosis, is not reported in a human yet, which is the subject of the current study. The platelets were extracted from 49 ml whole blood and labeled with Tc-99m HMPAO, then re-injected to the healthy volunteer. Anterior and posterior whole body imaging was done by a dual-head gamma camera 3, 18, 33, 46, 81, 124, 190 min and 15 hours after injection. Also a whole-body SPECT was done at 137 min post-injection. The area under the curves of the spleen, liver, left kidney, bladder, right lung, brain, and abdominal aorta ROIs was calculated to estimate the accumulation of labeled platelets within the organs. The spleen was the target organ. The kidneys, liver, and heart were also remarkably visualized. The thyroid, stomach, bladder, or gastrointestinal (GI) uptake/activity was not significant. The stomach visualization was enhanced after ingestion at 60 min. The sagittal and lateral sinuses were delineated, and the background of the brain was very low. During the study, the area under the curve of activity was 738, 308, 302, 196, 230, 121, 79, 216, 529, 369, 162, and 54 counts. min/pixel for spleen, liver, heart, right lung, left kidney, right iliac artery, sagittal sinus, thyroid, bladder, stomach, GI, and background, respectively. The quality of the scan with low dose Tc-99m HMPAO LPs is optimal. We documented the bio-distribution of LPs. The optimal imaging time was 80-120 min post-injection when the free Tc-99m and GI transit were negligible. The sagittal and lateral sinuses were visualized enabling detection of possible clots in the vessels.

Ictal and interictal SPECT with 99m Tc-HMPAO in presurgical epilepsy. II: Methodological considerations onhyper- and hypoperfusion.

Single-photon emission computed tomography (SPECT) with the tracer 99m Tc-HMPAO is a method to visualize the cerebral hyperperfusion during an epileptic seizure and thus localize the epileptogenic zone and seizure propagation. Subtraction of interictal from Ictal SPECT Co-registered to MRI (SISCOM) visualizes areas with relative increases in cerebral blood flow. The purpose of this retrospective study is to explore the added value of visualizing areas of hypoperfusion as well as hyperperfusion, so-called reversed SISCOM. Fifty-six patients operated for epilepsy who had been investigated with SISCOM were included in the analysis. The patients were divided into two groups based on seizure duration after tracer injection, above or below 30 s. The preoperative SISCOM description was compared to the area of resection and given a concordance score. The 56 SISCOM were recalculated visualizing also areas of hypoperfusion and again compared to the site of resection using the same scale of concordance. The reversed SISCOM were categorized into three subgroups: "Altered Conclusion," "Confirmed Conclusion," and "Adds Nothing." If an area of hyperperfusion had an area of hypoperfusion in close proximity, it was re-interpreted as noise, thus possibly altering the conclusion. If the areas of hypoperfusion were in the opposite hemisphere it was interpreted as confirming factor. Further the concordance scores from conventional SISCOM and reversed SISCOM was compared to surgical outcome to explore the difference in sensitivity, positive predictive value (PPV), and odds ratio. In approximately half of the cases reversed SISCOM added additional value, meaning either altered the conclusion or confirmed the conclusion. The sensitivity, PPV, and odds ratio was also better in the subgroup of long, >30 s seizure duration after injection, and got worse in the group with short, <30 s seizure duration after injection. Adding reversed SISCOM performed better than conventional SISCOM at predicting good surgical outcome.

Ictal and interictal SPECT with 99m Tc-HMPAO in presurgical epilepsy. I: Predictive value and methodologicalconsiderations.

This retrospective study investigates the predictive value of ictal subtraction single-photon emission computed tomography (SPECT) co-registered to magnetic resonance imaging (MRI) (SISCOM) for successful epilepsy surgery. 57 patients examined with SISCOM as a part of epilepsy surgery evaluation were divided into two groups based on seizure duration after tracer injection (group 1: Seizure duration above or equal to 30 s, group 2: Seizure duration under 30 s). SISCOM was compared to the surgical site and categorized as good or poor concordance. Subsequently, Odds ratios (ORs) and positive predictive values (PPVs) were calculated for each group for good surgical outcome, freedom from disabling seizures. The PPVs and ORs for good surgical outcome was 74.1% and 5.71 for group 1 and 40% and 0.22 for group 2. SISCOM had a similar positive predictive value regardless of whether the focus was in the same or neighboring lobe, but same hemisphere as the resection. In conclusion, the implementation of a precise definition for a well-executed ictal SPECT scan with respect to seizure duration after injection enhances the positive predictive value (PPV) and odds ratio (OR) for successful surgical outcome, surpassing previous findings, whether the focus in resected lobe or the neighboring.

Effects of cranioplasty in cerebral blood perfusion using quantification with 99m-Tc HMPAO SPECT-CT.

Syndrome of the trephined or sinking skin flap syndrome is an underdiagnosed condition of craniectomized patients that usually improves after cranioplasty. Among the pathophysiological theories proposed, the changes of cerebral blood perfusion (CBP) caused by cranial defects might have a role in the neurological deficiencies observed. We aim to assess the regional cortex changes in CBP after cranioplasty with Technetium 99m hexamethylpropylene-amine oxime (99mTc-HMPAO) SPECT-CT. Twenty-eight craniectomized patients subject to cranioplasty were studied with 99mTc-HMPAO SPECT-CT in three different times, before cranioplasty, a week, and 3months after. The images were processed with quantification software comparing CBP of 24 cortical areas with a reference area, and with a database of controls. A mixed effects model and T-Student were used. CBP increased significantly in both hemispheres after cranioplasty, either using ratio (β=.019, p-value=.030 first postsurgical SPECT-CT and β=.021, p-value=.015 in the second study, vs. presurgical) or Z-score (β=.220, p-value=.026 and β=.279, p-value=.005, respectively). Nine areas of the damaged side had a significant lower CBP ratio and Z-score than the undamaged. Posterior cingulate showed an increased CBP ratio (p-value=.034) and Z-score (p-value=.028) in the first postsurgical SPECT-CT. These posterior cingulate changes represent a 4.83% increase in ratio and 91.04% in Z-Score (p-value=.035 and .040, respectively). CBP changes significantly in specific cortical areas after cranioplasty. Posterior cingulate changes might explain some improvements in attention impairments. SPECT-CT could be a useful tool to assess CBP changes in these patients and might be helpful in their clinical management.

In vivo Molecular Imaging Stratifies Rats with Different Susceptibilities to Hyperoxic Acute Lung Injury

ObjectivesAcute Respiratory Distress Syndrome (ARDS) is one of the most frequent causes of admission to medical intensive care units. It carries a mortality rate &gt;30%, due to lack of early detection tools, inability to identify patients at risk for progression, and limited therapies. Previously, we demonstrated the utility of 99mTc‐hexamethylpropyleneamine oxime (HMPAO) and 99mTc‐duramycin in vivo imaging to detect oxidative stress and endothelial cell death in rats exposed to 100% O2 (hyperoxia) as a model of human ARDS. Pre‐exposure to hyperoxia for 48 hrs followed by 24 hr in room air (H‐T) protects against ARDS in that, when subsequently re‐exposed to hyperoxia, rats are tolerant of and survive the otherwise lethal effects of hyperoxia. Thus, the objective of this study was to evaluate the ability of 99mTc ‐HMPAO and ‐duramycin to track the protection of hyperoxia pre‐exposure and to identify mechanisms involved as potential therapeutic targets.MethodsSprague‐Dawley rats were exposed to either room air, hyperoxia (100% O2) for 60 hr, hyperoxia for 48 hr followed by 24 hr of room air (H‐T), or H‐T followed by 60 hr of hyperoxia (H‐T+60). Rats were anesthetized and imaged using either 99mTc‐HMPAO or 99mTc‐duramycin (37‐74 MBq) (n=4‐6 per group). In vivo scintigraphy images were acquired 20 min post i.v. injection and lung uptake was determined from the images as mean lung activity normalized to mean forelimb blood activity. Rat lung endpoints including wet‐to‐dry weight ratio, volume of pleural effusion in the chest cavity, expression of 3‐nitrotyrosine (3NT), and histological H&amp;E and cleaved caspase 3 positive‐cells (apoptosis marker) were also measured as indices of injury/protection.ResultsLung 99mTc‐HMPAO uptake increased by 200% in hyperoxia‐exposed rats, whereas uptake in H‐T+60 rats was 24% less than in H‐T rats. Lung uptake of 99mTc‐duramycin increased by 167% in hyperoxia‐exposed rats, but uptake in H‐T+60 rats was only 17% greater than H‐T rats. Lung wet/dry weight ratio increased by 21% in hyperoxia‐exposed rats, but by only 15% in H‐T+60 versus HT rats. Similarly, pleural effusion was reduced significantly (66%) in the H‐T+60 rats compared to the hyperoxia rats. 3NT expression, as a measure of oxidative stress, was increased ~300% with hyperoxia, but no significant increase was detected in H‐T+60 rats compared to H‐T. Histological analysis indicates that neutrophilic influx, edema, and apoptotic cells were increased with hyperoxia, but this increase was small or not observed with H‐T+60.ConclusionsLung uptake of 99mTc‐HMPAO and 99mTc‐duramycin, reflecting oxidative stress and cell death, respectively, is reduced significantly in rats preconditioned to tolerate hyperoxia compared to those without the preconditioning. This tolerance is also reflected in lung functional and histological endpoints measured independently. Overall these results suggest the potential utility of 99mTc‐HMPAO and 99mTc‐ duramycin imaging as a tool for identifying those hosts that are more or less susceptible to progressing to severe ARDS following mild symptoms of lung injury.

Longitudinal changes in regional cerebral blood flow in late middle-aged and older adults with treated and untreated obstructive sleep apnea.

Obstructive sleep apnea (OSA) is associated with abnormal cerebral perfusion at wakefulness, but whether these anomalies evolve over time is unknown. Here, we examined longitudinal changes in regional cerebral blood flow (rCBF) distribution in late middle‐aged and older adults with treated or untreated OSA. Twelve controls (64.8 ± 8.0 years) and 23 participants with newly diagnosed OSA (67.8 ± 6.2 years) were evaluated with polysomnography and cerebral 99mTc‐HMPAO single‐photon emission computed tomography during wakeful rest. OSA participants were referred to a sleep apnea clinic and 13 of them decided to start continuous positive airway pressure (CPAP). Participants were tested again after 18 months. Voxel‐based analysis and extracted relative rCBF values were used to assess longitudinal changes. Untreated OSA participants showed decreased relative rCBF in the left hippocampus and the right parahippocampal gyrus over time, while treated participants showed trends for increased relative rCBF in the left hippocampus and the right parahippocampal gyrus. No changes were found over time in controls. Untreated OSA is associated with worsening relative rCBF in specific brain areas over time, while treated OSA shows the opposite. Considering that OSA possibly accelerates cognitive decline in older adults, CPAP treatment could help reduce risk for cognitive impairment.

Basal and Acetazolamide Brain Perfusion SPECT in Internal Carotid Artery Stenosis.

Internal carotid artery (ICA) stenosis including Moyamoya disease needs revascularization when hemodynamic insufficiency is validated. Vascular reserve impairment was the key to find the indication for endarterectomy/bypass surgery in the atherosclerotic ICA stenosis and to determine the indication, treatment effect, and prognosis in Moyamoya diseases. Vascular reserve was quantitatively assessed by 1-day split-dose I-123 IMP basal/acetazolamide SPECT in Japan or by Tc-99m HMPAO SPECT in other countries using qualitative or semi-quantitative method. We summarized the development of 1-day basal/ acetazolamide brain perfusion SPECT for ICA stenosis, both quantitative and qualitative methods, and their methodological issues regarding (1) acquisition protocol; (2) qualitative assessment, either visual or deep learning-based; (3) clinical use for atherosclerotic ICA steno-occlusive diseases and mostly Moyamoya diseases; and (4) their impact on the choice of treatment options. Trials to use CT perfusion or perfusion MRI using contrast materials or arterial spin labeling were briefly discussed in their endeavor to use basal studies alone to replace acetazolamide-challenge SPECT. Theoretical and practical issues imply that basal perfusion evaluation, no matter how much sophisticated, will not disclose vascular reserve. Acetazolamide rarely causes serious adverse reactions but included fatality, and now, we need to monitor patients closely in acetazolamide-challenge studies.

307.2: Successful liver and kidney transplantations from a donor with left ventricular assist device.

Background: Organ transplantation from donors with ventricular assist devices are not common. Here, we report organ retrieval from a donor with a left ventricular assist device (LVAD) who was on the heart transplant waiting list before brain death diagnosis. Presentation of Case: The organ donor was diagnosed with dilated cardiomyopathy and underwent LVAD surgery for bridging to heart transplantation in 2016. Brain death occurred 22 months after LVAD implantation at the age of 39 due to widespread intraparenchymal and subarachnoid hemorrhage. Brain death diagnosis was confirmed with brain perfusion SPECT (Tc-99m HMPAO). In accordance with the donor’s will, the relatives approved organ donation. The donor’s organ reserve was assessed to be suitable for liver and kidney transplants and proper donor care was given. During organ harvesting, cardiovascular surgeons accompanied the organ transplant team to control LVAD flow and ensure optimum organ perfusion. After a successful operation, the liver was transplanted to a patient awaiting liver transplantation for 13 years with a diagnosis of primary sclerosing cholangitis, the kidneys were transplanted to patients awaiting kidney transplantation for 31 and 14 years with diagnoses of nephrolithiasis and polycystic kidney disease, respectively. No complications occurred among the liver and kidney transplant recipients. Conclusions: There are very few reported donors with assist device. This is the first case of an organ donor with an assist device waiting for an organ transplantation who became an actual donor in our country.

Single Photon Emission Computed Tomographic (SPECT) Study in Writer’s Cramp Patients

Background: Writer’s cramp is probably related to abnormal functioning of basal ganglia. But the actual mechanism is not known.Objective: The purpose of the present study was to evaluate the functional association of writer’s cramp with basal ganglia through SPECT study.Methodology: This prospective case control study was carried out in the Department of Neurology, Bangabandhu Sheikh Mujib Medical University, Dhaka and institute of nuclear medicine (INM), Dhaka from July 2001 to June 2003 to understand the basic pathophysiology of writer’s cramp by SPECT study and to compare the perfusion difference of basal ganglia between writer’s cramp and non-writer’s cramp group. A total of 20 respondents consisting of 10 in each group of writer’s cramp and non-writer’s cramp group as cases and controls respectively were enlisted by simple random method. Both the group of respondents underwent Tc99m HMPAO SPECT study during rest and writing period.Result: Out of 10 cases male patients were nine (90%) and female patient was one (10%) with male female ratio 9:1. Majority of patients presented third to fifth decades of which maximum (30%) were from 30-34 age group. Total six (60%) patients had simple writer’s cramp next three (30%) progressive writer’s cramp and one with dystonic variety. Maximum writer’s cramp patients were associated with great deal of writing (teacher, student, clerk, banker) and or performed repetitive hand movement (computer operator) from the point of occupational distribution. The perfusion difference of basal ganglia of both writer’s cramp and non-writer’s cramp group was seen by Tc99m HMPAO SPECT study during rest and writing period. First visual analysis of the scans by an expert nuclear medicine specialist showed no difference and then quantification of perfusion difference of basal ganglia by using SIEMENS macro programming environment (MPE) software showed no significant perfusion difference of basal ganglia between case and control group both during rest and writing period. In addition it was found highly significant perfusion difference (P=0.000321) separately in controls between left side and right side comparison during rest and significant difference (P=0.03) in writing and also significant in right side (P=0.022) during comparison of rest and writing period. The study also showed a significant perfusion difference (P=0.01) in cases between left and right comparison during writing and also significant perfusion difference (P=0.018) was found in rest and writing comparison of left side in writer’s cramp patients.Conclusion: There is no abnormality in basal ganglia perfusion pattern among the writer’s cramp patient.Journal of National Institute of Neurosciences Bangladesh, 2018;4(2): 92-96

PP.15.27] USE OF 99 M TC-HMPAO BRAIN SPECT ON PATIENTS WITH RESISTANT HYPERTENSION TO ASSESS THE SAFETY OF RENAL DENERVATION

Objective: To determine the speed change of cerebral blood flow after radiofrequency ablation of the renal arteries in patients with arterial hypertension resistant to drug therapyDesign and method: The study included 13 patients (average age 54,2 ± 11.4 years) with arterial hypertension resistant to drug therapy. All patients underwent office blood pressure measurement, brain SPECT with 99m Tc-HMPAO at baseline and after 6 months after renal denervation Results: According to office measurements, baseline blood pressure amounted to 166,9/101,1 mmHg with the decline -24,6/-14,8 mmHg 6 months after denervation (p < 0.05). When comparing indices of regional cerebral blood flow obtained when brain SPECT showed no signs of deterioration of cerebral perfusion and reduce the speed of cerebral circulation. On the contrary, in some regions of the brain marked by a significant increase in the speed of cerebral blood flow: in the right rear parietal, occipital right and left frontal and right-lower areas (p < 0.05). These results allow us to speak not only about security but also the positive impact of renal denervation on cerebral blood flow, probably due to the persistent decline in systemic arterial pressure. No patient included in the study were recorded adverse side effects related to the denervation. Dynamics of the level of blood creatinine or signs of stenosis of the renal arteries after ablation have not been identified Conclusions: In patients with resistant hypertension conducting renal denervation contributes to a significant reduction of office blood pressure. When evaluating the effect of renal denervation on the brain as one of the main target organs of hypertension, revealed no reduction in the level of cerebral blood flow and cerebral perfusion, suggesting the safety of this procedure.

Quantitative Evaluation of the Absolute Value of the Cerebral Blood Flow According to the Scintigraphic Studies with 99MTC-HMPAO

Background. Represented by physical and mathematical model of cerebral hemodynamics, considered as a flow system. Objective. Development of cerebral blood flow quantification procedure according to scintigraphy data with 99m Tc-HMPAO. Methods. Analytical, numerical and experimental study of the kinetics 99mTc-HMPAO in brain. Results. For the purpose of quantitative assessment of volumetric cerebral blood flow according to the data of scintigraphy with 99m Tc-HMPAO, it was suggested to view the brain as a flow system. This allows calculating volumetric cerebral blood flow after numerical determination of the model parameters according to the results of indirect angiography and establishment of effective blood dilution volume in brain using single-photon emission-computed tomography. In this case, the suggested blood flow calculation procedure does not require any a priori knowledge of hemodynamics in a certain reference area. Conclusions. Preliminary clinical studies allow characterizing the suggested approach to calculation of volumetric cerebral blood flow absolute values as appropriate.

Resting functional connectivity in social anxiety disorder and the effect of pharmacotherapy

Neuroimaging research has reported differences in resting-state functional connectivity (RFC) between social anxiety disorder (SAD) patients and healthy controls (HCs). Limited research has examined the effect of treatment on RFC in SAD. We performed a study to identify differences in RFC between SAD and HC groups, and to investigate the effect of pharmacotherapy on RFC in SAD. Seed-based RFC analysis was performed on technetium-99m hexamethylpropylene amine oxime (Tc-99m HMPAO) SPECT scans using a cross-subject approach in SPM-12. Seeds were chosen to represent regions in a recently published network model of SAD. A second-level regression analysis was performed to further characterize the underlying relationships identified in the group contrasts. Twenty-three SAD participants were included, of which 18 underwent follow-up measures after an 8-week course of citalopram or moclobemide. Fifteen healthy control (HC) scans were included. SAD participants at baseline demonstrated several significant connectivity disturbances consistent with the existing network model as well as one previously unreported finding (increased connectivity between cerebellum and posterior cingulate cortex). After therapy, the SAD group demonstrated significant increases in connectivity with dorsal anterior cingulate cortex which may explain therapy-induced modifications in how SAD sufferers interpret emotions in others and improvements in self-related and emotional processing.

Optimal HMPAO α value for Lassen's correction algorithm obscured by statistical noise.

Objective[99mTc] d,l-hexamethyl-propyeneamine oxime (99mTc-HMPAO), a brain perfusion tracer, suffers significant underestimation of regional cerebral blood flow (rCBF). Lassen et al. developed their linearization algorithm to correct the influence of back-diffusion of the tracer, and proposed their parameter α as 1.5. Based on mathematical modeling and literature review, recently, a new α value of 0.5 has been proposed for Lassen’s correction algorithm for 99mTc-HMPAO, although correction using the old α value of 1.5 was confirmed to be sufficient. Inugami et al. reported that linearization correction gives a stable correlation coefficient over a wide range of α. Our hypotheses are that statistical noise is the source of the stable correlation coefficient presented by them and that the robustness of the correlation coefficient is the reason why many studies confirmed the value of α as 1.5.MethodsStatistical noise was added in silico to the count, whose relationship with flow was α = 0.5. Then, the count was corrected by Lassen’s linearization algorithm with a variety of α.ResultsThis study confirmed the hypothesis that smaller α values (strong correction) increase the noise at high flow values, leading to nominal increases in correlation coefficient as α decreases.ConclusionDespite this, adoption of the new, smaller α value of 0.5 would be more useful clinically in regaining the contrast between low-flow and high-flow areas of the brain.Electronic supplementary materialThe online version of this article (doi:10.1007/s12149-016-1073-z) contains supplementary material, which is available to authorized users.

Simultaneous acquisition of (99m)Tc- and (123)I-labeled radiotracers using a preclinical SPECT scanner with CZT detectors.

Simultaneous acquisition of (99m)Tc and (123)I was evaluated using a preclinical SPECT scanner with cadmium zinc telluride (CZT)-based detectors. 10-ml cylindrical syringes contained about 37MBq (99m)Tc-tetrofosmin ((99m)Tc-TF) or 37MBq (123)I-15-(p-iodophenyl)-3R,S-methyl pentadecanoic acid ((123)I-BMIPP) were used to assess the relationship between these SPECT radioactive counts and radioactivity. Two 10-ml syringes contained 100 or 300MBq (99m)Tc-TF and 100MBq (123)I-BMIPP to assess the influence of (99m)Tc upscatter and (123)I downscatter, respectively. A rat-sized cylindrical phantom also contained both 100 or 300MBq (99m)Tc-TF and 100MBq (123)I-BMIPP. The two 10-ml syringes and phantom were scanned using a pinhole collimator for rats. Myocardial infarction model rats were examined using 300MBq (99m)Tc-TF and 100MBq (123)I-BMIPP. Two 1-ml syringes contained 105MBq (99m)Tc-labeled hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) and 35MBq (123)I-labeled N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane ((123)I-FP-CIT). The two 1-ml syringes were scanned using a pinhole collimator for mice. Normal mice were examined using 105MBq (99m)Tc-HMPAO and 35MBq (123)I-FP-CIT. The relationship between SPECT radioactive counts and radioactivity was excellent. Downscatter contamination of (123)I-BMIPP exhibited fewer radioactive counts for 300MBq (99m)Tc-TF without scatter correction (SC) in 125-150keV. There was no upscatter contamination of (99m)Tc-TF in 150-175keV. In the rat-sized phantom, the radioactive count ratio decreased to 4.0% for 300MBq (99m)Tc-TF without SC in 125-150keV. In the rats, myocardial images and radioactive counts of (99m)Tc-TF with the dual tracer were identical to those of the (99m)Tc-TF single injection. Downscatter contamination of (123)I-FP-CIT was 4.2% without SC in 125-150keV. In the first injection of (99m)Tc-HMPAO and second injection of (123)I-FP-CIT, brain images and radioactive counts of (99m)Tc-HMPAO with the dual tracer in normal mice also were the similar to those of the (99m)Tc-HMPAO single injection. In the first injection of (123)I-FP-CIT and second injection of (99m)Tc-HMPAO, the brain images and radioactive counts with the dual tracer were not much different from those of the (123)I-FP-CIT single injection. Dual-tracer imaging of (99m)Tc- and (123)I-labeled radiotracers is feasible in a preclinical SPECT scanner with CZT detector. When higher radioactivity of (99m)Tc-labeled radiotracers relative to (123)I-labeled radiotracers is applied, correction methods are not necessarily required for the quantification of (99m)Tc- and (123)I-labeled radiotracers when using a preclinical SPECT scanner with CZT detector.

Nano Liposomes Labeled with (99m)Tc-HMPAO, a Novel Agent for Blood Pool Imaging.

In-vitro labeling of RBC with (99m)Tc is an intricate procedure and there is always a need for an alternate blood pool imaging agent. The aim of this study was to prepare an effective nano sized liposome (NLs) similar to human RBC for blood pool scintigraphy. This study formulates PEG-NLs and non-PEG-NLs using film method plus high pressure homogenization technique. Biodistribution studies were performed on BALB/C mice 1, 4 and 24 h after tail vein injection of labeled NLs with (99m)Tc hexamethylpropylene-amine-oxime ((99m)Tc-HMPAO). Planar images were acquired using a 256 × 256 matrix following(99m) Tc-HMPAO-NLs injection into ear vein of rabbits 1, 2 and 24 h later. SPECT images were obtained 15 minutes after the injection (64 slices, 30 second/projection). The mean diameter, zeta potential and polydispersity index (PDI) of the PEG-NLs and the NLs were (80.88 ± 0.594 nm, -12.5 ± 0.56 mv, 0.158 ± 0.025) and (94.14 ± 0.114 nm, -35.5 ± 0.67 mv and 0.198 ± 0.007), respectively. (99m)Tc-HMPAO-PEG-NLs showed a significant circulation tracer activity (7.74 ± 1.63%ID/g at 1 h and 4.9 ± 0.77 %ID/g at 4 h), with low liver accumulation (12.07 ± 3.66 %ID/g at 1 h and 14.85 ± 1.3 %ID/g at 4 h). Heart to liver, spleen and background ROIs (region of interests) for (99m) Tc-HMPAO-PEG-NLs were 1.25, 4 and 4.28 respectively at 2 h which changed to 1.06, 1.75 and 2.51 respectively at 24 h. The (99m)Tc-HMPAO-PEG-NLs with a prolonged blood circulation time could be an excellent RBC alternative for scintigraphy and gastrointestinal bleeding.

CT-based attenuation and scatter correction compared with uniform attenuation correction in brain perfusion SPECT imaging for dementia

This study investigated if the appearance and diagnostic accuracy of HMPAO brain perfusion SPECT images could be improved by using CT-based attenuation and scatter correction compared with the uniform attenuation correction method.A cohort of subjects who were clinically categorized as Alzheimer’s Disease (), Dementia with Lewy Bodies () or healthy normal controls (), underwent SPECT imaging with Tc-99m HMPAO and a separate CT scan. The SPECT images were processed using: (a) correction map derived from the subject’s CT scan or (b) the Chang uniform approximation for correction or (c) no attenuation correction. Images were visually inspected. The ratios between key regions of interest known to be affected or spared in each condition were calculated for each correction method, and the differences between these ratios were evaluated.The images produced using the different corrections were noted to be visually different. However, ROI analysis found similar statistically significant differences between control and dementia groups and between AD and DLB groups regardless of the correction map used.We did not identify an improvement in diagnostic accuracy in images which were corrected using CT-based attenuation and scatter correction, compared with those corrected using a uniform correction map.

Screening with angiographic images prior to (99m)Tc-HMPAO labelled leukocyte scintigraphy in the diagnosis of periprosthetic infection

To evaluate the impact of the angioscintigrapy of the three phase bone scan as screening method to rule out infection of the hip and knee prosthesis prior to performing the (99m)Tc-HMPAO leukocyte scintigraphy. A total of 120 (70 women, 50 men; mean age 71±11years) with clinical suspicion of hip (n=63) or knee (n=57) infection of the prosthesis and clinical suspicion of infection were evaluated prospectively. All patients underwent three-phase bone scan (angioscintigraphy, vascular and bone phase) and (99m)Tc-HMPAO-labelled white blood cell scintigraphy. Final diagnosis of infection was made by microbiological documentation or clinical follow-up for at least 12months. Eighteen out of 120 patients were diagnosed of infection of hip prosthesis (n=10) or knee prosthesis (n=8). The angioscintigraphy was positive in 15/18 infected cases and in 21/102 of the non-infected cases with a sensitivity of 83%, specificity of 79% and negative predictive value of 97%. Sensitivity and specificity of (99m)Tc-HMPAO leukocyte scintigraphy were 72% and 95%, respectively. If the leukocyte labeled scintigraphies had been used exclusively for patients with positive angioscintigraphy, this would have saved up to 70% of the (99m)Tc-HMPAO leukocyte scintigraphies performed. There were no cases of infection with positive labeled leukocyte scintigraphy and negative angioscintigraphy. Angioscintigraphy (blood flow phase of bone scan) is a useful technique for screening for hip and knee joint prosthesis infection, significantly reducing the need for (99m)Tc-HMPAO leukocyte scintigraphy without affecting the sensitivity of the technique.

Improvement in cerebral hemodynamic parameters and outcomes after superficial temporal artery-middle cerebral artery bypass in patients with severe stenoocclusive disease of the intracranial internal carotid or middle cerebral arteries.

Both the older and the recent extracranial-intracranial (EC-IC) bypass trials for symptomatic carotid occlusion failed to demonstrate a reduction in stroke recurrence. However, the role of superficial temporal artery (STA)-middle cerebral artery (MCA) bypass in patients with symptomatic intracranial stenoocclusive disease has been rarely evaluated. The authors evaluated serial changes in various cerebral hemodynamic parameters in patients with severe stenoocclusive disease of the intracranial internal carotid artery (ICA) or middle cerebral artery (MCA) and impaired cerebral vasodilatory reserve (CVR), treated by STA-MCA bypass surgery or medical treatment. Patients with severe stenoocclusive disease of the intracranial ICA or MCA underwent transcranial Doppler (TCD) ultrasonography and CVR assessment using the breath-holding index (BHI). Patients with impaired BHI (< 0.69) were further evaluated with acetazolamide-challenge technitium-99m hexamethylpropyleneamine oxime ((99m)Tc HMPAO) SPECT. STA-MCA bypass surgery was offered to patients with impaired CVR on SPECT. All patients underwent TCD and SPECT at 4 ± 1 months and were followed up for cerebral ischemic events. A total of 112 patients were included. This total included 73 men, and the mean age of the entire study population was 56 years (range 23-78 years). (99m)Tc HMPAO SPECT demonstrated impaired CVR in 77 patients (69%). Of these 77 patients, 46 underwent STA-MCA bypass while 31 received best medical treatment. TCD and acetazolamide-challenge (99m)Tc HMPAO SPECT repeated at 4 ± 1 months showed significant improvement in the STA-MCA bypass group. During a mean follow-up of 34 months (range 18-39 months), only 6 (13%) of 46 patients in the bypass group developed cerebral ischemic events, as compared with 14 (45%) of 31 patients receiving medical therapy (absolute risk reduction 32%, p = 0.008). STA-MCA bypass surgery in carefully selected patients with symptomatic severe intracranial stenoocclusive disease of the intracranial ICA or MCA results in significant improvement in hemodynamic parameters and reduction in stroke recurrence.

The Effects of (99mTc) Hm-Pao Labeling on Lymphocyte Functions

Objective: (99mTc) HM-PAO labeled leucocytes have been used as a standard diagnostic procedure for the detection of infection and inflammation. Although, some investigators have already pointed out that labeling of leucocytes with (99mTc) HM-PAO has detrimental effects on the cells, still very little is known regarding the effects of ionizing radiation on lymphocyte functions. Methods: In this study, we evaluated the effects of (99mTc) HM-PAO labeling on lymphocyte adhesion, proliferation, migration and apoptosis. We used NC-NC lymphoblastoid cell line as the lymphocyte population. (99mTc) HM-PAO labeling decreased cell adhesion, proliferation and motility whereas induced apoptosis, and cell cycle arrest. Proliferation assays were performed both using MTT and ELISA tests with 24 hours intervals following labeling. Results: It was recorded that the rate of decrease in proliferation was up to 70% by the 4th day after labeling. (99mTc) HMPAO labeling led a 35% decrease on adhesion ability of the cells on fibronectin. By using Boyden chamber motility assay, we showed that both spontaneous and MCP-1 induced lymphocyte motility were potently blocked by (99mTc) HM-PAO labeling. The rate of decrease in motility was approximately five times. In addition, we observed a 12 times increase in the apoptosis rate within the (99mTc) HM-PAO treated cells compared to the control cells. Besides it was observed that cell cycle arrest was induced starting from 3rd day after (99mTc) HM-PAO treatment. Conclusion: Based on our data (99mTc) HM-PAO labeling has damaging effects on lymphocyte functions including cell adhesion, proliferation, motility and viability in in vitro.

Evaluation of Bone or Soft Tissue Infection with Tc-99m Hmpao White Blood Cell Scintigraphy: Semiquantitative Method

Objective: Aim the aim of this study was to investigate semiquantitatively the diagnostic performance of Tc-99m hexamethypropylene amine oxime labeled white blood cell (Tc-99m HMPAO-WBC) scintigraphy in patients with suspected bone or soft tissue infections. Methods: Material and Method twenty one patients who applied to Nuclear Medicine Departmant (for suspected prosthesis infection, diabetic foot, bone infection, graft infection) were evaluated retrospectively. Tc-99m HMPAO WBC scintigraphy imaging were performed to all patients. Planar images were taken 1., 2., and 4. hours after injecting the labeled leukocytes. Evaluation of infection with Tc-99m HMPAO WBC scintigraphy was done semiquantitatively. Relative uptake was determined by setting the region of interest (ROI) of lesion area on the anterior view. Rectangular ROI was set on the against limb (nonlesion). The ratio of the average pixel count in the lesion (L) to that in the non-lesion (NL) (L/NL ratio) was calculated at 1., 2., and 4. hours images. Final diagnosis was based on histopathology, microbiologic assays, or clinical and imaging follow-up. Results: 0.55 and 1.55±0.74, 1.42±0.55, 1.40±0.55 in positive and control groups, respectively. Positive group revealed a statistically significant increase L/NL values in the data 3 hours images (p=0.002). However, no statistically significant was found between L/NL values in 3 hours imaging data in control group (p=0.223). All the data in the positive group found Zehra Pinar Koc1, Yasemin Bulut2, Sinan Canpolat3, Ayhan Uysal4, Mehmet Sarac5 1Firat University Faculty of Medicine, Department of Nuclear Medicine, Elazig, Turkey 2Firat University Faculty of Medicine, Department of Clinic Microbiology, Elazig, Turkey 3Firat University Faculty of Medicine, Department of Phsiology, Elazig, Turkey 4Firat University Faculty of Medicine, Department of Cardiovascular Surgery, Elazig, Turkey 5Firat University Faculty of Medicine, Department of Pediatric Surgery, Elazig, Turkey Evaluation of Pulmonary Infection in Rabbits by Tc-99m Hmpao Labeled Leukocyte Scintigraphy