The Prognostic Value of 99mTc-HMPAO-Labeled Leucocyte SPECT/CT in Cardiac Device-Related Infective Endocarditis.

OBJECTIVES: This was a prospective, single-center study designed to assess the prognostic value of the hybrid technique of single photon emission tomography and computed tomography with the application of technetium99m-hexamethylpropyleneamine oxime-labelled autologous leukocytes (99mTc-HMPAO-SPECT/CT) in patients with cardiac device-related infective endocarditis (CDRIE). BACKGROUND: CDRIE entails the risk of complications and an increase in mortality rates, both in-hospital and long-term. The prognostic value of 99mTc-HMPAO-SPECT/CT in the course of CDRIE has not been evaluated so far. METHODS: The project enrolled 103 consecutive patients with suspected CDRIE, all of whom underwent 99mTc-HMPAO-SPECT/CT. The resulting scans were then classified as positive if the presence of abnormal tracer uptake involving cardiac and intravascular sections of the device electrodes was found. Patients were prospectively observed for a mean time of 17.48 ± 11.9 months. All-cause mortality, in-hospital mortality, and complete hardware removal were assessed, followed by a composite endpoint including complications, namely embolic events, new onset heart failure, uncontrolled infection, renal replacement therapy, reoperation, new heart rhythm, and conduction disturbances. RESULTS: In the analysis, despite a noticeable trend, all-cause mortality rates were not found to be statistically significantly higher among the 35 patients who registered positive results using 99mTc-HMPAO-SPECT/CT for CDRIE (group 1) than among the 68 patients from group 2 whose 99mTc-HMPAO-SPECT/CT results were negative (20% vs. 10.3%, respectively; p = 0.14). However, group 1 did present higher in-hospital mortality (11.4% vs. 0%, respectively; odds ratio: 19.6; 95% confidence interval [CI]: 1.02 to 374.70), an increased rate of complications (43% vs. 9%, respectively; hazard ratio [HR]: 5.9; 95% CI: 2.27 to 15.20), and underwent hardware removal more frequently (57% vs. 16%, respectively; HR: 4.3; 95% CI: 2.07 to 19.08). CONCLUSIONS: In patients with suspected CDRIE, positive 99mTc-HMPAO-SPECT/CT results were associated with increased rates of in-hospital mortality and complications.

The clinical contribution of SPECT/CT with 99mTc-HMPAO-labeled leukocyte scintigraphy in hip and knee prosthetic infections. / Aportación clínica de la SPECT/TC en la gammagrafía con leucocitos marcados con 99mTc-HMPAO en infección de prótesis de cadera y rodilla.

OBJECTIVES: White blood cell scanning with 99mTc-hexamethylpropylene amine oxime (HMPAO) has proven a sensitive and specific imaging method in the diagnosis of suspected prosthesis infection. The aim of this retrospective study was to evaluate the usefulness of SPECT/CT performed simultaneously using a hybrid imaging device of prosthesis infections. MATERIALS AND METHODS: 99mTc-HMPAO scintigraphy was performed on 37 patients (11 men and 26 women; age range 38-84 years; mean age±SD, 65.7±5.6 years). Planar scans were acquired 2.4 and 24hour after injection. SPECT/CT was obtained 4 h after injection, using a dual-head hybrid gama camera coupled with a low-power x-ray tube. In all patients, scintigraphic results were matched with the results of surgery, cultures and clinical follow-up. RESULTS: Seventeen (45,9%) out of 37 patients had prosthesis infection and 20 (54,1%) out of 37 patients had non-infectious prosthesis pathologies with 99mTc-HMPAO scintigraphy and SPECT/CT. The 99mTc-HMPAO scintigraphy was true-positive for infection in 16 of 37 patients and true-negative in 20 of 37 patients. SPECT/CT provided an accurate anatomic localization of all positive foci. With regard to the final diagnosis, SPECT/CT added a significant clinical contribution in 22 of 37 patients (59,4%). Sensitivity, specificity, negative predictive value and positive predictive values were 100%,59.1%,100%,62.5% in planar images with 99mTc-HMPAO scintigraphy and 100%,90.1%,100%,88.2% in the planar+SPECT/CT imaging, respectively. DISCUSSION: Our results indicate that SPECT/CT performed using a hybrid device can improve imaging with 99mTc-HMPAO scintigraphy in patients with suspected osteomyelitis by providing accurate anatomic localization and precise definition of the extent of infection.

Predicting progression of amnesic MCI: The integration of episodic memory impairment with perfusion SPECT.

The present study aimed at assessing if the ability to predict progression from amnesic Mild Cognitive Impairment (aMCI) to dementia is improved by considering the presence at the baseline of Single Photon Emission Computed Tomography (SPECT) perfusion abnormalities in addition to a defect of long term memory. The Episodic Memory Score (EMS), a global index which integrates results obtained in subtests of the Rey's Verbal Learning Test and the Rey-Osterrieth Figure recall, were taken into account to evaluate defects of long term memory. The study sample consisted of 42 subjects affected by aMCI, who were followed-up during a two-year period. At the final follow-up 15 subjects progressed to AD. The EMS predicted progression from aMCI to dementia with a high level of sensitivity and a lower level of specificity, but the association of neuropsychological (EMS) and SPECT data (hypoperfusion in the Posterior Cingulate Cortex) increased the accuracy in predicting conversion from aMCI to AD. The association of results obtained by aMCI patients on memory tests and perfusion SPECT may improve the accuracy in detecting subjects who will progress to dementia. The use of currently available and low-cost investigations could be advantageous in terms of public health policies.

Quantitation of rat cerebral blood flow using 99mTc-HMPAO.

INTRODUCTION: Technetium-99m-hexamethylpropyleneamine oxime (99mTc-HMPAO) is potentially useful for the assessment of cerebral blood flow (CBF) in small animals. In this paper, a procedure for quantitation of rat CBF using 99mTc-HMPAO was determined. METHODS: Biodistribution of 99mTc-radioactivity in normal rats was determined after intravenous administration of 99mTc-HMPAO. Acetazolamide treated rats were intravenously administered with the mixture of 99mTc-HMPAO and N-isopropyl-[125I]iodoamphetamine ([125I]IMP), and arterial blood was then collected for 5min. After blood sampling, the brain radioactivity concentration was measured with the auto-well γ counter. RESULTS: The brain radioactivity concentration after intravenous administration of 99mTc-HMPAO was steady from 14s to 60min post-injection. A double tracer experiment using 99mTc-HMPAO and [125I]IMP showed that 19s was the average of the optimal integration interval of arterial blood 99mTc-radioactivity concentration to obtain CBF values measured by 99mTc-HMPAO identical to those determined by [125I]IMP. The CBF value determined by 99mTc-HMPAO, calculated by dividing the brain radioactivity concentration at 5min post-injection by the integrated arterial blood radioactivity concentration until 19s post-injection, was well correlated with CBF as determined by [125I]IMP. CONCLUSION: These results suggest that the CBF quantitation procedure described in this paper could be useful for rat CBF assessment.

Comparative Analysis of (99m)Tc-MDP Three-Phase Bone Scan with SPECT/CT and (99m)Tc-HMPAO-Labeled WBC SPECT/CT in the Differential Diagnosis of Clinically Suspicious Post-traumatic Osteomyelitis / 대한핵의학회잡지

PURPOSE: To identify differences between three-phase bone scan and SPECT/CT (TBS) and WBC SPECT/CT (WS) and compare diagnostic accuracies of each modality in patients with suspicious post-traumatic osteomyelitis (OM).METHODS: Twenty-one patients with suspicious post-traumatic OM were enrolled. All patients performed TBS and WS within 1 week. Foci ofMDP andWBC accumulation were divided into three categories: bone (OM), soft tissue (soft tissue inflammation; STI), negative for inflammation (NI). Confirmative diagnosis was made upon operative pathology or long-term clinical follow-up.RESULTS: Of 21 patients, four OM, eight STI, nine NI were finally diagnosed. TBS diagnosis was correct in three of four positive cases and nine of 17 negative cases. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) of TBS were 75 %, 52.9 %, 57.1 %, 27.3 %, 90 %. WS diagnosis was correct in two of four positive cases and 17 of 17 negative cases. Sensitivity, specificity, accuracy, PPV, NPV were 50 %, 100 %, 81.0 %, 100 %, 89.5 %. Twelve of 21 cases showed agreement between TBS and WS. TBS misdiagnosed nine cases (six STI and two NI as eight OM; one OM as one STI), while WS misdiagnosed four cases (two OM as two STI; two STI as two NI). Combining results from TBS and WS led to better diagnostic accuracy (91.7 %) than either TBS or WS alone.CONCLUSION: TBS and WS showed moderate agreement in assessment of clinically suspected post-traumatic OM. WS better evaluated inflammation than TBS. WS tended to underestimate inflammation whereas TBS tended to overestimate inflammation. Combining TBS and WS enhanced diagnostic accuracy.

[Screening with angiographic images prior to (99m)Tc-HMPAO labelled leukocyte scintigraphy in the diagnosis of periprosthetic infection]. / Cribado mediante angiogammagrafía previo a la realización de gammagrafía con leucocitos (99m)Tc-HMPAO en el diagnóstico de infección de prótesis articulares.

AIM: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.

In vitro assessment of cytotoxicity and labeling efficiency of 99mTc-HMPAO with stromal vascular fraction of adipose tissue.

INTRODUCTION: Noninvasive radionuclide imaging of cells using technetium99m-hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) is a potential diagnostic tool for several applications. Herein we aimed to evaluate the labeling efficiency and cellular toxicity of (99m)Tc-HMPAO with Stromal Vascular Fraction (SVF) of adipose tissue to develop a process tool for theranostic purposes, in particular imaging cardiac stem cell therapy. METHODS: Ten million cells of SVF were labeled with (99m)Tc-HMPAO complex and excess radiolabel was cleared off through washing in PBS. The labeling efficiency of (99m)Tc-HMPAO was detected in labeled cells and their subsequent supernatant wash using isotope dose calibrator and gamma camera. The cytotoxicity was assessed for the comparative reactive oxygen species (ROS) by H2DCFDDA, apoptotic events by annexin-V and TUNEL assay and mitochondrial potential by JC-1. RESULTS: An encouraging labeling efficiency of 33% was observed with (99m)Tc-HMPAO complex. The radionuclide labeling of SVF demonstrated significant safety profile as evaluated by apoptotic assays. CONCLUSION: (99m)Tc-HMPAO labeling efficiency of 33% of total SV fraction would produce sufficient radioactive signals that would enable for in vivo tracking of cells by SPECT-CT. The radionuclide did not demonstrate any significant impact on the structural or functional organization of the labeled cells. Our study indicates that SVF can be safely labeled with (99m)Tc-HMPAO without adverse cytotoxic events and for its potential role in imaging cardiac stem cell therapy.

Real-time differential tracking of human neutrophil and eosinophil migration in vivo.

BACKGROUND: Hitherto, in vivo studies of human granulocyte migration have been based on indiscriminate labeling of total granulocyte populations. We hypothesized that the kinetics of isolated human neutrophil and eosinophil migration through major organs in vivo are fundamentally different, with the corollary that studying unseparated populations distorts measurement of both. METHODS: Blood neutrophils and eosinophils were isolated on 2 separate occasions from human volunteers by using Current Good Manufacturing Practice CD16 CliniMACS isolation, labeled with technetium 99m-hexamethylpropyleneamine oxime, and then reinfused intravenously. The kinetics of cellular efflux were imaged over 4 hours. RESULTS: Neutrophils and eosinophils were isolated to a mean purity of greater than 97% and greater than 95%, respectively. Activation of neutrophils measured as an increase in their CD11b mean fluorescence intensity in whole blood and after isolation and radiolabeling was 25.98 ± 7.59 and 51.82 ± 17.44, respectively, and was not significant (P = .052), but the mean fluorescence intensity of CD69 increased significantly on eosinophils. Analysis of the scintigraphic profile of lung efflux revealed exponential clearance of eosinophils, with a mean half-life of 4.16 ± 0.11 minutes. Neutrophil efflux was at a significantly slower half-life of 13.72 ± 4.14 minutes (P = .009). The migration of neutrophils and eosinophils was significantly different in the spleen at all time points (P = .014), in the liver at 15 minutes (P = .001), and in the bone marrow at 4 hours (P = .003). CONCLUSIONS: The kinetics of migration of neutrophils and eosinophils through the lung, spleen, and bone marrow of human volunteers are significantly different. Study of mixed populations might be misleading.

Radiolabeled WBC scintigraphy in the diagnostic workup of patients with suspected device-related infections.

OBJECTIVES: The aim of this study was to investigate the diagnostic performance of (99m)Tc-hexamethypropylene amine oxime labeled autologous white blood cell ((99m)Tc-HMPAO-WBC) scintigraphy in patients with suspected infections associated with cardiovascular implantable electronic devices (CIEDs). BACKGROUND: Early, definite recognition of CIED-related infections combined with accurate localization and quantification of disease burden is a prerequisite for optimal treatment strategies. METHODS: All 63 consecutive patients underwent clinical examination, blood chemistry, microbiology, and echography of the cardiac region/venous pathway of the device. Final diagnosis of infection was established in 32 of 63 patients and in 23 of 32 by microbiology. RESULTS: Sensitivity of (99m)Tc-HMPAO-WBC single-photon emission computed tomography/computed tomography (SPECT/CT) was 94% for both detection and localization of CIED-associated infection. SPECT/CT imaging had a definite added diagnostic value over both planar and stand-alone SPECT. Pocket infection was often associated with lead(s) involvement; the intracardiac portion of the lead(s) more frequently exhibited (99m)Tc-HMPAO-WBC accumulation and presented the highest rate of complications, infectious endocarditis, and septic embolism. Two false negative cases and no false positive results were observed. None of the patients with negative (99m)Tc-HMPAO-WBC scintigraphy developed CIED-related infection during follow-up of 12 months. Echography of the cardiac region/venous pathway of the device had 90% specificity, but low sensitivity (81% when intracardiac lead[s] infection only was considered). The Duke criteria had 31% sensitivity for the definite category (100% specificity) and 81% for the definite and possible categories (77% specificity). CONCLUSIONS: (99m)Tc-HMPAO-WBC scintigraphy enabled the confirmation of the presence of CIED-associated infection, definition of the extent of device involvement, and detection of associated complications. Moreover, (99m)Tc-HMPAO-WBC scintigraphy reliably excluded device-associated infection during a febrile episode and sepsis, with 95% negative predictive value.

Brain perfusion SPECT in patients with Behçet's disease.

The aim of this study was to detect brain functional deficits in patients with Behçet's disease (BD) and signs or symptoms of central nervous system (CNS) involvement at different times in their clinical history. A total of 24 patients aged 20 to 53years (median age 39years; 20 women, four men) with Behçet's syndrome fulfilling the diagnosis as defined by the syndrome classification were enrolled in this study. Single-photon emission computed tomography (SPECT) with (99m)Technetium (Tc)-hexamethylpropyleneamine oxime (HMPAO) as the perfusion tracer was performed to detect brain lesions. The results of (99m)Tc-HMPAO brain SPECT scans showed impaired perfusion in all cases with neurological complaints (24 out of 24, 100%). Temporal lobes and basal ganglia were the most common areas with such lesions. In contrast, brain MRI and CT images were normal or non-specific in all cases. In conclusion, (99m)Tc-HMPAO brain SPECT imaging is a powerful and sensitive tool for disclosing brain involvement in numerous clinical situations, even including patients with subtle neurological symptoms/signs such as headaches and dizziness. It is also a useful modality for evaluating the effects of treatment and disease monitoring to prevent CNS damage.

Quantifying the effect of repetitive transcranial magnetic stimulation in the rat brain by µSPECT CBF scans.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is used to treat neurological and psychiatric disorders such as depression and addiction amongst others. Neuro-imaging by means of SPECT is a non-invasive manner of evaluating regional cerebral blood flow (rCBF) changes, which are assumed to reflect changes in neural activity. OBJECTIVE: rCBF changes induced by rTMS are evaluated by comparing stimulation on/off in different stimulation paradigms using microSPECT of the rat brain. METHODS: Rats (n = 6) were injected with 10 mCi of (99m)Tc-HMPAO during application of two rTMS paradigms (1 Hz and 10 Hz, 1430 A at each wing of a 20 mm figure-of-eight coil) and sham. SPM- and VOI-based analysis was performed. RESULTS: rTMS caused widespread significant hypoperfusion throughout the entire rat brain. Differences in spatial extent and intensity of hypoperfusion were observed between both stimulation paradigms: 1 Hz caused significant hypoperfusion (P < 0.05) in 11.9% of rat brain volume while 10 Hz caused this in 23.5%; the minimal t-value induced by 1 Hz was -24.77 while this was -17.98 due to 10 Hz. Maximal percentage of hypoperfused volume due to 1 Hz and 10 Hz was reached at tissue experiencing 0.03-0.15 V/m. CONCLUSION: High-frequency (10 Hz) stimulation causes more widespread hypoperfusion, while 1 Hz induces more pronounced hypoperfusion. The effect of rTMS is highly dependent on the electric field strength in the brain tissue induced by the TMS coil. This innovative imaging approach can be used as a fast screening tool in quantifying and evaluating the effect of various stimulation paradigms and coil designs for TMS and offers a means for research and development.

Changes in Cerebral Vascular Reserve Capacity after Carotid Artery Stenting: A 6-Month Follow-up Study

BACKGROUND: Assessment of cerebral vascular reserve capacity prior to carotid artery stenting is used for predicting hyperperfusion syndrome. However, the changes in vascular reserve capacity after carotid stenting are not fully understood. In this study we investigated the effects of carotid artery stenting on the restoration of vascular reserve capacity using (99m)TC-hexamethylpropylene amine oxime (HMPAO) single-photon-emission computed tomography (SPECT). METHODS: The study population comprised 29 patients who underwent carotid artery stenting. Patients were divided into groups according to occlusion of the contralateral internal carotid artery (unilateral group vs bilateral group) and according to the presence or absence of symptoms related to carotid stenosis (symptomatic group vs asymptomatic group). Pre- and postacetazolamide-activated (99m)TC-HMPAO SPECT were performed prior to stent insertion and at 1 and 6 months postoperatively. Vascular reserve capacity was assessed based on pre-, and 1- and 6-month postacetazolamide gamma count ratio (Post0, Post1, and Post6, respectively) and cerebrovascular reactivity (CVR0, CRV1, and CRV6, respectively). RESULTS: The postacetazolamide gamma count ratio and cerebrovascular reactivity tended to improve at 1 month after stenting, but tended to deteriorate at 6 months after stenting in the unilateral group compared with the bilateral group [Post0-Post1=0.045+/-0.078 (mean+/-SD), p=0.014; Post0-Post6=0.025+/-0.063, p=0.042; Post1-Post6=-0.020+/-0.047, p=0.102; CVR0-CVR1=0.043+/-0.071, p=0.008, CVR0-CVR6=0.019+/-0.063, p=0.097; CVR1-CVR6=-0.024+/-0.047, p=0.008] and in the symptomatic group compared with the asymptomatic group (Post0-Post1=0.058+/-0.106, p=0.038; Post0-Post6=0.048+/-0.103, p=0.061; Post1-Post6=-0.010+/-0.048, p=0.700; CVR0-CVR1=0.037+/-0.083, p=0.074; CVR0-CVR6=0.014+/-0.073, p=0.344; CVR1-CVR6=-0.023+/-0.054, p=0.055). CONCLUSIONS: The observed increases in postacetazolamide gamma count ratio and cerebrovascular reactivity at 1 month followed by decreases at 6 months may reflect the restoration of vascular reserve capacity. Carotid artery stenting can improve vascular reserve capacity, especially in patients with unilateral stenosis and with symptomatic stenosis.

Characteristics of Brain Perfusion in Patients of Parkinson's Disease / 핵의학분자영상

PURPOSE: It was well known that cerebral blood perfusion is normal or diffusely decreased in the majority of patients with Parkinson's disease (PD). Actually we interpreted brain perfusion SPECT images of PD patients in the clinical situation, we observed various cerebral perfusion patterns in patients with PD. So we performed brain perfusion SPECT to know the brain perfusion patterns of PD patients and the difference of perfusion patterns according to the sex and the age. Also we classified PD patients into small groups based on the brain perfusion pattern. METHODS AND MATERIALS: Two hundred nineteen patients (M: 70, F: 149, mean age: 62.9+/-6.9 y/o) who were diagnosed as PD without dementia clinically and 55 patients (M: 15, F: 40, mean age: 61.4+/-9.2 y/o) as normal controls who had no past illness history were performed (99m)Tc-HMPAO brain perfusion SPECT and neuropsychological test. RESULTS: At first, we compared all patients with PD and normal controls. Brain perfusion in left inferior frontal gyrus, left insula, left transverse temporal gyrus, left inferior parietal lobule, left superior parietal lobule, right precuneus, right caudate tail were lower in patients with PD than normal controls. Secondly, we compared male and female patients with PD and normal controls, respectively. Brain perfusion SPECT showed more decreased cerebral perfusion in left hemisphere than right side in both male and female patients compared to normal controls. And there was larger hypoperfusion area in female patients compared with male. Thirdly, we classified patients with PD and normal controls into 4 groups according to the age and compared brain perfusion respectively. In patient below fifties, brain perfusion in both occipitoparietal and left temporal lobe were lower in PD group. As the patients with PD grew older, hypoperfusion area were shown in both frontal, temporal and limbic lobes. Fourthly, We were able to divide patients into small groups based on cerebral perfusion pattern. There was normal cerebral blood perfusion in 32 (14.7%) of 219 patients with PD, decreased perfusion on the frontal lobe in 45 patients (20.6%), the temporal lobe in 38 patients (17.4%), the parietal lobe in 39 patients (17.9%), the occipital lobe in 40 patients (18.3%), diffuse area in 14 patients (6.4%) and unclassified in 10 patients (4.6%). Fifthly, we compared the results of the neuropsychological test and cerebral perfusion pattern. There was no correlation between two tests except visuospatial function. CONCLUSION: Various perfusion state were found in patients with PD according to the age and sex. Also we were able to classify perfusion state into several groups and compare the neuropsychological test with cerebral perfusion.

The Value of (99m)Tc-HMPAO-WBC Scan in the Diagnosis of Infection after Total Knee Arthroplasty

PURPOSE: The early diagnosis and detection of prosthetic infection after TKA is very important and difficult for deter- mination of the plan in management and reduction of complications. In these reasons, this study was performed to evaluate the usefulness and limitation of (99m)Tc-HMPAO(Technetium (99m)-hexamethyl- propylene amine oxime)-labeled WBC scan in the patients with clinically suspicious prosthetic infection. MATERIALS AND METHODS: The study subjects were 25 patients(3 men and 19 women, mean age: 66.5 years) performed (99m)Tc-HMPAO WBC scan in the patients with clinically suspicious prosthesis infection after TKA from January, 2005 to May, 2007. And in 6 patients who had undergone bilateral arthroplasty, we regarded one patient as two cases. Thus, total 31 prostheses were included in this study. Final diagnosis of infection was based on bacteriological result by intrao- perative cultures, surgical findings, and histological evidence intraoperatively obtained in the suspicious site and clinical follow-up. RESULTS: In the final diagnosis, we confirmed that total 16 prosthetic joints were infected. Of these infected prostheses, increased (99m)Tc-HMPAO WBC scan uptake waspositive in 15, negative in 1. Finally, 15 cases were confirmed as nonin- fected prosthesis, 6 showed positive by (99m)Tc-HMPAO WBC scan uptake, 9 showed negative. Over all sensitivity, speci- ficity, and positive predictive value for diagnosisof infected TKA were 93.75, 60%, and 71.43%. CONCLUSION: (99m)Tc-HMPAO WBC scan was a highly sensitive method for the diagnosis of prosthetic infection after TKA. But low specificity and high false positive of (99m)Tc-HMPAO WBC scan demand more clinical follow-up for confirmed diagnosis. To increase specificity, additionally scan will be needed.

Neurological Improvement after Cranioplasty in Patients with Surgical Bony Defects : The Usefulness of Acetazolamide Activated (99m)Tc-HMPAO SPECT

OBJECTIVE: The purpose of this study is to examine the influence of cranioplasty on dynamics of cerebral blood flow(CBF) and cerebrovascular reserve capacity(CVRC), and to investigate the usefulness of single photon emission computed tomography (SPECT) as a prognostic factor for neurological improvement after cranioplasty. METHODS: Between March 2003 and December 2005, a prospective study was performed on 24 patients who had undergone total 25 cranioplasty operations. Cerebral blood flow velocities in the middle cerebral artery(MCA) and internal carotid artery (ICA) were obtained by transcranial Doppler ultrasonography(TCD). The CVRC was assessed by SPECT in the natural state and after stimulation with 1g of acetazolamide. Neurological improvement after cranioplasty was compared between patients who showed hyperactivity to acetazolamide-activated SPECT (Group 1, n=7) and hypoactivity to acetazolamide-activated SPECT (Group 2, n=17). These measurements were obtained two weeks prior to and two weeks after cranioplasty. RESULTS: The blood flow velocities at the opposite site to the cranioplasty as well as at the cranioplasty site were significantly increased (P<0.05). Compared with Group 2, there was significant increase in CBF and neurological imrovement after cranioplasty in Group 1. CONCLUSION: Among patients with surgical bony defects, the patients who had normal reactivity of the CVRC showed a significant increase in CBF and neurological improvement after cranioplasty. The authors suggest that CVRC measurement prior to surgery may be an important prognostic factor for neurological improvement after cranioplasty.

The Clinical Significance of SPECT in Head Trauma

SPECT(single photon emission computed tomography) using 99m-Tc-HMPAO is a current method of identifying the relative condition of cerebral blood perfusion in pathologic conditions of the brain such as TIA, complete cerebral infarction, dementia, and psychologically ill states. The purpose of this article is to evaluate the significance of SPECT in head injuries. According to the other previous reports, there are several drawbacks in SPECT to evaluate the victims of head injury such as uncooperability of the patient, long scanning time. poor patient monitoring during the scanning time. poor availability, ete. The authors analyzed 54 cases of head injury patients, studying SPECT and CT in regard to the comparison of CT and SPECT, the relation of SPECT and the severity of the head injury, the duration of admission and the SPECT findings. The results were as follows: 1) In focal lesion, CT was more available for the quick evaluation of the location, size, and rapid decision making, and SPECT was available for the adjuvant method of postoperative follow-up. 2) In diffuse brain lesion, CT showed only the diffuse brain swelling and SPECT was available for more fine localization of the lesion. 3) In mild head injury, CT could not identify the location of the lesion and SPECT showed focal perfusion defects(55%).