A multicentre simulation study of planar whole-body bone scintigraphy in Sweden

Background

Whole-body bone scintigraphy is a clinically useful non-invasive and highly sensitive imaging method enabling detection of metabolic changes at an early stage of disease, often earlier than with conventional radiologic procedures. Bone scintigraphy is one of the most common nuclear medicine methods used worldwide. Therefore, it is important that the examination is implemented and performed in an optimal manner giving the patient added value in the subsequent care process. The aim of this national multicentre survey was to investigate Swedish nuclear medicine departments compliance with European practice guidelines for bone scintigraphy. In addition, the effect of image acquisition parameters on the ability to detect metabolic lesions was investigated.

Methods

Twenty-five hospital sites participated in the study. The SIMIND Monte Carlo (MC) simulation and the XCAT phantom were used to simulate ten fictive patient cases with increased metabolic activity distributed at ten different locations in the skeleton. The intensity of the metabolic activity was set into six different levels. Individual simulations were performed for each site, corresponding to their specific camera system and acquisition parameters. Simulated image data sets were then sent to each site and were visually evaluated in terms of if there was one or several locations with increased metabolic activity relative to normal activity.

Result

There is a high compliance in Sweden with the EANM guidelines regarding image acquisition parameters for whole-body bone scintigraphy. However, up to 40% of the participating sites acquire lower count density in the images than recommended. Despite this, the image quality was adequate to maintain a stable detection level. None of the hospital sites or individual responders deviated according to the statistical analysis. There is a need for at least 2.5 times metabolic activity compared to normal for a lesion to be detected.

Conclusion

The imaging process is well harmonized throughout the country and there is a high compliance with the EANM guidelines. There is a need for at least 2.5 times the normal metabolic activity for a lesion to be detected as abnormal.

Health care costs for residents diagnosed with diabetes type 2 in Malmö, Sweden between 2011 and 2018

Background

During the last decade, type 2 diabetes (T2D) prevalence has increased worldwide, especially among children and young adults. Diabetes is a chronic disease that if not diagnosed in time can lead to serious health complications and put pressure on the societal resources. The aim of this study was to evaluate the economic impact of the increased T2D prevalence in Malmö over time on the regional health care organization.

Methods

A longitudinal population-based study in Malmö, within the Cities Changing Diabetes project. Data was collected from the Patient Administrative System in Region Skåne, classifying T2D by the ICD E11 code. The health care cost (HCC) has been adjusted by the Consumer Price Index (CPI) to 2020 prices.

Results

The prevalence of T2D increased from 2,5% in 2011 to 4,3% in 2018. The increase in T2D prevalence was most noticeable for residents 18 - 64 years. The overall HCC for treating residents with T2D was approximately €47,2 million in 2011 and €90,7 million in 2018. The HCC in 2018 was higher for males than for females (€54,6 million vs €36,2 million). In 2018, the cost was €49,9 million for those 18 - 64 years and €40,5 million for those being 65 years or older. The overall HCC increased during the study period (3,3 times for those 18 - 64 years and 1,4 times for those being 65 years or older). For the age group 18 - 64 the HCC per resident was €5 000 in 2011 and €5 300 in 2018. The HCC per resident for all age groups, has not changed markedly, from €6 200 in 2011 to €6 100 in 2018 as well as the number of health care visits (23 in 2011 and 29 in 2018).

Conclusions

The HCC for T2D has increased markedly since 2011. This increase is most noticeable for people under 65 years. The overall HCC for these patients and its change over time puts an increased strain on the health care provider Region Skåne, mainly due to increased prevalence.

Key messages

The overall HCC during 2011 – 2018 has increased 2 times for residents with T2D and 1.5 times for residents without T2D. This increase is likely to continue if the current trend remains. The main driving force behind the increase in HCC over time is the increase in T2D prevalence and not in HCC per resident.

OP0186 CHANGES IN CIRCULATING B CELL LEVELS AND IMMUNOPHENOTYPE ARE ASSOCIATED WITH DEVELOPMENT OF ARTHRITIS FOLLOWING TREATMENT WITH CHECKPOINT INHIBITORS

Background:

Inflammatory arthritis (IA) is frequent among rheumatic side effects induced by checkpoint inhibitor (CPI) therapy for metastatic malignancies1. While T cells are likely to sustain the inflammatory process2, fewer data are available concerning the role of B cells3.

Objectives:

To investigate the phenotype of circulating B cells in patients who develop CPI-induced IA (CPI-IA) and to compare it with features of B cells in patients not developing immune-related adverse events (irAE) upon CPI treatment.

Methods:

B cell subsets at baseline (before CPI initiation) and during CPI treatment were analyzed in CPI-IA patients and in patients receiving CPI but who did not develop irAE (non-irAE). Peripheral blood mononuclear cells (PBMC) were analyzed by flow cytometry and B cells were identified as CD19+ and divided into naïve (CD27-IgD+), memory (CD27+IgD+/-), double negative (CD27-IgD-) and transitional (CD10+CD24+CD38+/hi) B cells. Levels of CD21, an activation marker on transitional B cells, were also analyzed. Non-parametric tests were used for analysis of differences between groups.

Results:

Six CPI-IA and 7 non-irAE patients matched for age, gender and CPI treatment were included, who had received CPI treatment due to metastatic melanoma. Flow cytometry revealed a significant increase of circulating B cells (p=0.002) (Figure 1A) and especially of transitional B cells in CPI-IA patients vs. non-irAE (median %, range: 7.8 (4.5-11.4) vs. 3.2 (1.6-4.3),p=0.007) (Figure 1B), while no remarkable changes were seen across other subsets. Transitional B cell levels significantly decreased from active to quiescent CPI-IA in all patients (p=0.008). In two CPI-IA patients for whom baseline sampling was available, the increase of transitional levels occurred early after CPI treatment and before CPI-IA onset. Levels of expression of CD21 on transitional B cells were increased in CPI-IA vs. non-irAE (p=0.01).

Conclusion:

Transitional B cells are expanded in CPI-IA patients and seem to increase early after start of CPI therapy. Monitoring this B cell subset might lead to closer follow-up and earlier diagnosis of CPI-IA.

References:

[1]Ramos-Casals M, Brahmer JR, Callahan MK, et al. Immune-related adverse events of checkpoint inhibitors. Nat Rev Dis Primers 2020;6:38

[2]Murray-Brown W, Wilsdon TD, Weedon H, et al. Nivolumab-induced synovitis is characterized by florid T cell infiltration and rapid resolution with synovial biopsy-guided therapy. J Immunother Cancer 2020;8:e000281

[3]Das R, Bar N, Ferreira M, et al. Early B cell changes predict autoimmunity following combination immune checkpoint blockade. J Clin Invest. 2018;128:715-2

Disclosure of Interests:

None declared

POS1064 SERUM BIOMARKERS BEFORE AND AFTER A SIX MONTHS STRUCTURED WEIGHT LOSS INTERVENTION IN PATIENTS WITH PSORIATIC ARTHRITIS AND OBESITY COMPARED WITH CONTROLS

Background:

Obesity is highly overrepresented in psoriatic arthritis (PsA) and associated with increased disease activity. We have previously shown in 41 patients with PsA (Caspar criteria) and obesity (here body mass index BMI ≥33 kg/m2) that weight loss treatment including Very Low Energy Liquid Diet (VLED) resulted in a median weight loss of 18.6% and concomitantly a significant improvement in CRP and disease activity in joints, entheses and skin at six months (M6) follow up.

Objectives:

To analyze serum biomarkers associated with inflammation, cartilage and bone metabolism before and after weight loss treatment in PsA patients compared with controls, without PsA or psoriasis, matched for age, sex and weight.

Methods:

The weight loss treatment included VLED (640 kcal/day) during 12 or 16 weeks (depending on baseline (BL) BMI <40 or ≥40 kg/m2), followed by a structured reintroduction of an energy restricted diet. cs/bDMARDs were held unchanged from 3 months before BL until M6. The patients were assessed with 66/68 joints counts.

Serum levels of vascular endothelial growth factor (VEGF), S100A8, S100A9, matrix metalloproteinases (MMP-3, 8 and 13), hepatocyte growth factor (HGF), B-cell activating factor (BAFF), Dickkopf (DKK)-1, sclerostin (SOST), soluble receptor activator of nuclear factor-kB ligand (RANKL), osteprotegerin (OPG) and aggrecan were measured at BL and M6 in PsA patients and controls with Magnetic Luminex Assays (R&D-systems) following the manufacturer’s instructions using a Bio-Plex 200 system (BioRad). Serum cartilage oligomeric matrix protein (COMP) (R&D-systems), carboxyterminal telopeptide of type-1 collagen (CTX-1) (Immunodiagnostics systems: IDS) and osteocalcin (IDS) were measured with enzyme-linked immunosorbent assay (ELISA).

Results:

Totally 41 PsA patients [age median 54 (IQR 48-62) yrs; 63 % women] and 39 controls [age 55 (46-60) yrs, 72 % women] were included. At M6 the weight-loss since BL was 18.7 (14.6-26.5) kg in the PsA patients and 22.6 (14.7-28.4) kg in the controls (p=0.546). Significant reductions in DAS28CRP [2.9 (2.1–3.7) vs. 2.4 (1.7–3.0)] and DAPSA [15.3(6.6-29.1) vs. 11.0 (2.8–17.6)] (p<0.001) were seen in the PsA patients.

At BL serum levels of the biomarkers were not significantly different in patients vs. controls.

After weight-loss significant reductions were seen in serum VEGF, S100A8, MMP-8, HGF, BAFF, COMP and DKK-1, whereas serum SOST and CTX-1 were significantly increased in both patients and controls (Table 1). The other biomarkers were not significantly changed.

Conclusion:

Weight loss in patients with PsA and controls was associated with lowered serum levels of several biomarkers related to inflammation and cartilage degradation, along with increased levels of biomarkers for bone turnover.

Table 1.PsA (N=41)BL median (IQR)PsA (N=41)M6 median (IQR)PsAp-valueCtrl (N=39)BL median (IQR)Ctrl (N=39)M6 median (IQR)Ctrlp-valueBMI (kg/m2)35.2 (34.1-38.1)29.8 (26.6-31.5)<0.00137.7 (36.7–41.5)30.4 (27.9–33.2)<0.001CRP (mg/L)4 (2–8.5)2 (1–6.5)0.0414 (2–6)2 (1–4)<0.001VEGF (pg/mL)79.6 (55.9–113.5)69.6 (53.1–105.3)0.01082.3 (48.0–125.9)65.0 (42.2-85.5)<0.001S100A8 (pg/mL)75.5 (48.0–99.5)63.3 (42.8–93.6)0.02171.8 (40.5–101.0)63.3 (40.3-85.7)0.006MMP-8 (pg/mL)9975.4(6811.8–14154.8)9202.6(5767.1–12049.6)0.0177494.7(4805.2-12616.9)7218.3(3466.0-9785.3)0.112HGF (pg/mL)327.9 (250.3–413.6)271.3 (206.9–331.0)<0.001307.9 (239.1–348.3)239.8 (200.3-276.0)<0.001BAFF (pg/mL)794.4 (716.4–868.2)674.6 (613.2–790.5)<0.001760.8 (664.1–827.3)678.1 (603.7–719.8)<0.001COMP (pg/mL)266.1 (209.8–366.0)217.0 (156.0–272.0)0.008293.6 (185.2–340.5)221.6 (163.5-300.0)0.018Dkk-1 (pg/mL)3608.4(3055.0–4401.3)3382.6(2802.5–4218.2)0.0023635.8(3212.8-4380.6)3480.4(2948.9–4087.3)0.007SOST (pg/mL)52.9 (32.5–65.4)60.3 (37.2–85.6)0.01450.0 (30.8–79.3)61.3(35.7–81.4)0.019CTX-1 (ng/mL)0.27 (0.20–0.39)0.51 (0.35–0.64)<0.0010.23 (0.16–0.34)0.50(0.30–0.61)<0.001

Disclosure of Interests:

None declared.

Head-to-Head Comparison among Semi-Quantification Tools of Brain FDG-PET to Aid the Diagnosis of Prodromal Alzheimer's Disease

BACKGROUND

Several automatic tools have been implemented for semi-quantitative assessment of brain [18]F-FDG-PET.

OBJECTIVE

We aimed to head-to-head compare the diagnostic performance among three statistical parametric mapping (SPM)-based approaches, another voxel-based tool (i.e., PALZ), and a volumetric region of interest (VROI-SVM)-based approach, in distinguishing patients with prodromal Alzheimer's disease (pAD) from controls.

METHODS

Sixty-two pAD patients (MMSE score = 27.0±1.6) and one hundred-nine healthy subjects (CTR) (MMSE score = 29.2±1.2) were enrolled in five centers of the European Alzheimer's Disease Consortium. The three SPM-based methods, based on different rationales, included 1) a cluster identified through the correlation analysis between [18]F-FDG-PET and a verbal memory test (VROI-1), 2) a VROI derived from the comparison between pAD and CTR (VROI-2), and 3) visual analysis of individual maps obtained by the comparison between each subject and CTR (SPM-Maps). The VROI-SVM approach was based on 6 VROI plus 6 VROI asymmetry values derived from the pAD versus CTR comparison thanks to support vector machine (SVM).

RESULTS

The areas under the ROC curves between pAD and CTR were 0.84 for VROI-1, 0.83 for VROI-2, 0.79 for SPM maps, 0.87 for PALZ, and 0.95 for VROI-SVM. Pairwise comparisons of Youden index did not show statistically significant differences in diagnostic performance between VROI-1, VROI-2, SPM-Maps, and PALZ score whereas VROI-SVM performed significantly (p < 0.005) better than any of the other methods.

CONCLUSION

The study confirms the good accuracy of [18]F-FDG-PET in discriminating healthy subjects from pAD and highlights that a non-linear, automatic VROI classifier based on SVM performs better than the voxel-based methods.

Brain Glucose Metabolism Heterogeneity in Idiopathic REM Sleep Behavior Disorder and in Parkinson's Disease

BACKGROUND/OBJECTIVE

Idiopathic REM sleep behavior disorder (iRBD) often precedes Parkinson's disease (PD) and other alpha-synucleinopathies. The aim of the study is to investigate brain glucose metabolism of patients with RBD and PD by means of a multidimensional scaling approach, using18F-FDG-PET as a biomarker of synaptic function.

METHODS

Thirty-six iRBD patients (64.1±6.5 y, 32 M), 72 PD patients, and 79 controls (65.6±9.4 y, 53 M) underwent brain 18F-FDG-PET. PD patients were divided according to the absence (PD, 32 subjects; 68.4±8.5 y, 15 M) or presence (PDRBD, 40 subjects; 71.8±6.6 y, 29 M) of RBD. 18F-FDG-PET scans were used to independently discriminate subjects belonging to four categories: controls (RBD no, PD no), iRBD (RBD yes, PD no), PD (RBD no, PD yes) and PDRBD (RBD yes, PD yes).

RESULTS

The discriminant analysis was moderately accurate in identifying the correct category. This is because the model mostly confounds iRBD and PD, thus the intermediate classes. Indeed, iRBD, PD and PDRBD were progressively located at increasing distance from controls and are ordered along a single dimension (principal coordinate analysis) indicating the presence of a single flux of variation encompassing both RBD and PD conditions.

CONCLUSION

Data-driven approach to brain 18F-FDG-PET showed only moderate discrimination between iRBD and PD patients, highlighting brain glucose metabolism heterogeneity among such patients. iRBD should be considered as a marker of an ongoing condition that may be picked-up in different stages across patients and thus express different brain imaging features and likely different clinical trajectories.

Corrosion threshold data of metallic materials in various operating environment of offshore wind turbine parts (tower, foundation, and nacelle/gearbox)

This paper outlines corrosion thresholds for different environmental conditions of metallic materials commonly used in the tower, foundation, and nacelle/gearbox of an offshore wind turbine. These threshold values were derived from laboratory corrosion testing employing electrochemical analysis techniques, using the media/solvents that are representative to the operating environment of those wind turbine parts, such as seawater, grease, oils/lubricants, or their combination, at room temperature and at 328K. These values can provide an indication when general/local corrosion or protective film/surface damages have occurred. They can thus be utilised for detecting and monitoring corrosion at certain locations in the wind turbine structure. The presented data have been verified and validated to ensure their repeatability and reliability by means of numerous laboratory tests in accordance to the relevant engineering test standards and an extensive literature/published data review.

Diagnostic performance of the specific uptake size index for semi-quantitative analysis of I-123-FP-CIT SPECT: harmonized multi-center research setting versus typical clinical single-camera setting

Introduction

The specific uptake size index (SUSI) of striatal FP-CIT uptake is independent of spatial resolution in the SPECT image, in contrast to the specific binding ratio (SBR). This suggests that the SUSI is particularly appropriate for multi-site/multi-camera settings in which camera-specific effects increase inter-subject variability of spatial resolution. However, the SUSI is sensitive to inter-subject variability of striatum size. Furthermore, it might be more sensitive to errors of the estimate of non-displaceable FP-CIT binding. This study compared SUSI and SBR in the multi-site/multi-camera (MULTI) setting of a prospective multi-center study and in a mono-site/mono-camera (MONO) setting representative of clinical routine.

Methods

The MULTI setting included patients with Parkinson’s disease (PD, n = 438) and healthy controls (n = 207) from the Parkinson Progression Marker Initiative. The MONO setting included 122 patients from routine clinical patient care in whom FP-CIT SPECT had been performed with the same double-head SPECT system according to the same acquisition and reconstruction protocol. Patients were categorized as “neurodegenerative” (n = 84) or “non-neurodegenerative” (n = 38) based on follow-up data. FP-CIT SPECTs were stereotactically normalized to MNI space. SUSI and SBR were computed for caudate, putamen, and whole striatum using unilateral ROIs predefined in MNI space. SUSI analysis was repeated in native patient space in the MONO setting. The area (AUC) under the ROC curve for identification of PD/“neurodegenerative” cases was used as performance measure.

Results

In both settings, the highest AUC was achieved by the putamen (minimum over both hemispheres), independent of the semi-quantitative method (SUSI or SBR). The putaminal SUSI provided slightly better performance with ROI analysis in MNI space compared to patient space (AUC = 0.969 vs. 0.961, p = 0.129). The SUSI (computed in MNI space) performed slightly better than the SBR in the MULTI setting (AUC = 0.993 vs. 0.991, p = 0.207) and slightly worse in the MONO setting (AUC = 0.969 vs. AUC = 0.976, p = 0.259). There was a trend toward larger AUC difference between SUSI and SBR in the MULTI setting compared to the MONO setting (p = 0.073). Variability of voxel intensity in the reference region was larger in misclassified cases compared to correctly classified cases for both SUSI and SBR (MULTI setting: p = 0.007 and p = 0.012, respectively).

Conclusions

The SUSI is particularly useful in MULTI settings. SPECT images should be stereotactically normalized prior to SUSI analysis. The putaminal SUSI provides better diagnostic performance than the SUSI of the whole striatum. Errors of the estimate of non-displaceable count density in the reference region can cause misclassification by both SUSI and SBR, particularly in borderline cases. These cases might be identified by visual checking FP-CIT uptake in the reference region for particularly high variability.

The Alzheimer's disease metabolic brain pattern in mild cognitive impairment

We investigated the expression of the Alzheimer's disease-related metabolic brain pattern (ADRP) in 18F-FDG-PET scans of 44 controls, 27 patients with mild cognitive impairment (MCI) who did not convert to Alzheimer's disease (AD) after five or more years of clinical follow-up, 95 MCI patients who did develop AD dementia on clinical follow-up, and 55 patients with mild-to-moderate AD. The ADRP showed good sensitivity (84%) and specificity (86%) for MCI-converters when compared to controls, but limited specificity when compared to MCI non-converters (66%). Assessment of 18F-FDG-PET scans on a case-by-case basis using the ADRP may be useful for quantifying disease progression.

Emerging clinical issues and multivariate analyses in PET investigations

PET using 18F-2-fluoro-2-deoxy-D-glucose (FDG-PET) has been gradually introduced in the diagnostic clinical criteria of the most prevalent neurodegenerative diseases. Moreover, an increasing amount of literature has shown that the information provided by FDG-PET enhances the sensitivity of standard imaging biomarkers in less frequent disorders in which an early differential diagnosis can be of paramount relevance for patient management and outcome. Therefore emerging uses of FDG-PET may be important in prion diseases, autoimmune encephalitis (AE) and amyotrophic lateral sclerosis. Interestingly, FDG-PET findings can also be observed in the early phases of these conditions, even in the presence of normal magnetic resonance imaging scans. Thalamic hypometabolism is a common finding in sporadic Creutzfeldt-Jacob disease and fatal familiar insomnia patients, with further cortical synaptic dysfunction in the former. Limbic and extra-limbic metabolic abnormalities (more often hypermetabolism) can be observed in AE, although specific patterns may be seen within different syndromes associated with antibodies that target neuronal surface or synaptic antigens. FDG-PET shows its usefulness by discriminating patients with amyotrophic lateral sclerosis associated to upper motor neuron onset that evolve to frontotemporal dementia. Besides visual and voxel based image analysis, multivariate analysis as interregional correlation analysis and independent/principal component analysis have been successfully implemented to PET images increasing the accuracy of the discrimination of neurodegenerative diseases. The clinical presentation and current diagnostic criteria of these neurologic disorders as well as the emerging usefulness of FDG-PET in the diagnostic workup are presented and discussed in this review.

Early identification of MCI converting to AD: a FDG PET study

PURPOSE

Mild cognitive impairment (MCI) is a transitional pathological stage between normal ageing (NA) and Alzheimer's disease (AD). Although subjects with MCI show a decline at different rates, some individuals remain stable or even show an improvement in their cognitive level after some years. We assessed the accuracy of FDG PET in discriminating MCI patients who converted to AD from those who did not.

METHODS

FDG PET was performed in 42 NA subjects, 27 MCI patients who had not converted to AD at 5 years (nc-MCI; mean follow-up time 7.5 ± 1.5 years), and 95 MCI patients who converted to AD within 5 years (MCI-AD; mean conversion time 1.8 ± 1.1 years). Relative FDG uptake values in 26 meta-volumes of interest were submitted to ANCOVA and support vector machine analyses to evaluate regional differences and discrimination accuracy.

RESULTS

The MCI-AD group showed significantly lower FDG uptake values in the temporoparietal cortex than the other two groups. FDG uptake values in the nc-MCI group were similar to those in the NA group. Support vector machine analysis discriminated nc-MCI from MCI-AD patients with an accuracy of 89% (AUC 0.91), correctly detecting 93% of the nc-MCI patients.

CONCLUSION

In MCI patients not converting to AD within a minimum follow-up time of 5 years and MCI patients converting within 5 years, baseline FDG PET and volume-based analysis identified those who converted with an accuracy of 89%. However, further analysis is needed in patients with amnestic MCI who convert to a dementia other than AD.

Can Spatiotemporal Fluoride (18F-) Uptake be Used to Assess Bone Formation in the Tibia? A Longitudinal Study Using PET/CT

BACKGROUND

When a bone is broken for any reason, it is important for the orthopaedic surgeon to know how bone healing is progressing. There has been resurgence in the use of the fluoride (¹⁸F^-) ion to evaluate various bone conditions. This has been made possible by availability of positron emission tomography (PET)/CT hybrid scanners together with cyclotrons. Absorbed on the bone surface from blood flow, ¹⁸F^- attaches to the osteoblasts in cancellous bone and acts as a pharmacokinetic agent, which reflects the local physiologic activity of bone. This is important because it shows bone formation indicating that the bone is healing or no bone formation indicating no healing. As ¹⁸F^- is extracted from blood in proportion to blood flow and bone formation, it thus enables determination of bone healing progress.

QUESTIONS/PURPOSES

The primary objective of this study was to determine whether videos showing the spatiotemporal uptake of ¹⁸F^- via PET bone scans could show problematic bone healing in patients with complex tibia conditions. A secondary objective was to determine if semiquantification of radionuclide uptake was consistent with bone healing.

METHODS

This study investigated measurements of tibia bone formation in patients with complex fractures, osteomyelitis, and osteotomies treated with a Taylor Spatial Frame^TM (TSF) by comparing clinical healing progress with spatiotemporal fluoride (¹⁸F^-) uptake and the semiquantitative standardized uptake value (SUV). This procedure included static and dynamic image acquisition. For intrapatient volumes acquired at different times, the CT and PET data were spatially registered to bring the ends of the bones that were supposed to heal into alignment. To qualitatively observe how and where bone formation was occurring, time-sequenced volumes were reconstructed and viewed as a video. To semiquantify the uptake, the mean and maximum SUVs (SUVmean, SUVmax) were calculated for the ends of the bones that were supposed to heal and for normal bone, using a spherical volume of interest drawn on the registered volumes. To make the semiquantitative data comparable for all patients with multiple examinations, the SUVmean and SUVmax difference per day (SUVmeanDPD and SUVmaxDPD) between the first PET/CT scan and each subsequent one was calculated. Indicators of poor healing progress were (1) uneven distribution of the radionuclide uptake between ends of the bones that were supposed to heal as seen in the video or, (2) low absolute magnitude of the SUV difference data. Twenty-four patients treated between October 2013 and April 2015 with a TSF gave informed consent to be examined with ¹⁸F^- PET/CT bone scans. Twenty-two patients successfully completed treatment, one of whom had only one PET/CT scan.

RESULTS

Observation of ¹⁸F^- uptake was able to identify three patients whose healing progress was poor, indicated by uneven distribution of radionuclide uptake across the ends of the bones that were supposed to heal. An absolute magnitude of the SUVmaxDPD of 0.18 or greater indicated good bone formation progress. This was verified in 10 patients by the days between the operation to attach and to remove the TSF being less than 250 days, whereas other SUVmaxDPD values were ambiguous, with 11 patients achieving successful completion.

CONCLUSIONS

Observation of the spatiotemporal uptake of ¹⁸F^- appears to be a promising method to enable the clinician to assess the progress of bone formation in different parts of the bone. Bone uptake which is uneven across the ends of bone that were supposed to heal or very low bone uptake might indicate impaired bone healing where early intervention may then be needed. However, semiquantification of ¹⁸F^- uptake (SUVmaxDPD), SUVmeanDPD) was ambiguous in showing consistency with the bone-healing progress.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Progressive Disintegration of Brain Networking from Normal Aging to Alzheimer Disease: Analysis of Independent Components of 18F-FDG PET Data

Brain connectivity has been assessed in several neurodegenerative disorders investigating the mutual correlations between predetermined regions or nodes. Selective breakdown of brain networks during progression from normal aging to Alzheimer disease dementia (AD) has also been observed. Methods: We implemented independent-component analysis of ¹⁸F-FDG PET data in 5 groups of subjects with cognitive states ranging from normal aging to AD-including mild cognitive impairment (MCI) not converting or converting to AD-to disclose the spatial distribution of the independent components in each cognitive state and their accuracy in discriminating the groups. Results: We could identify spatially distinct independent components in each group, with generation of local circuits increasing proportionally to the severity of the disease. AD-specific independent components first appeared in the late-MCI stage and could discriminate converting MCI and AD from nonconverting MCI with an accuracy of 83.5%. Progressive disintegration of the intrinsic networks from normal aging to MCI to AD was inversely proportional to the conversion time. Conclusion: Independent-component analysis of ¹⁸F-FDG PET data showed a gradual disruption of functional brain connectivity with progression of cognitive decline in AD. This information might be useful as a prognostic aid for individual patients and as a surrogate biomarker in intervention trials.

[123I]FP-CIT ENC-DAT normal database: the impact of the reconstruction and quantification methods

Background

[¹²³I]FP-CIT is a well-established radiotracer for the diagnosis of dopaminergic degenerative disorders. The European Normal Control Database of DaTSCAN (ENC-DAT) of healthy controls has provided age and gender-specific reference values for the [¹²³I]FP-CIT specific binding ratio (SBR) under optimised protocols for image acquisition and processing. Simpler reconstruction methods, however, are in use in many hospitals, often without implementation of attenuation and scatter corrections. This study investigates the impact on the reference values of simpler approaches using two quantifications methods, BRASS and Southampton, and explores the performance of the striatal phantom calibration in their harmonisation.

Results

BRASS and Southampton databases comprising 123 ENC-DAT subjects, from gamma cameras with parallel collimators, were reconstructed using filtered back projection (FBP) and iterative reconstruction OSEM without corrections (IRNC) and compared against the recommended OSEM with corrections for attenuation and scatter and septal penetration (ACSC), before and after applying phantom calibration. Differences between databases were quantified using the percentage difference of their SBR in the dopamine transporter-rich striatum, with their significance determined by the paired t test with Bonferroni correction.

Attenuation and scatter losses, measured from the percentage difference between IRNC and ACSC databases, were of the order of 47% for both BRASS and Southampton quantifications. Phantom corrections were able to recover most of these losses, but the SBRs remained significantly lower than the “true” values (p < 0.001). Calibration provided, in fact, “first order” camera-dependent corrections, but could not include “second order” subject-dependent effects, such as septal penetration from extra-cranial activity. As for the ACSC databases, phantom calibration was instrumental in compensating for partial volume losses in BRASS (~67%, p < 0.001), while for the Southampton method, inherently free from them, it brought no significant changes and solely corrected for residual inter-camera variability (−0.2%, p = 0.44).

Conclusions

The ENC-DAT reference values are significantly dependent on the reconstruction and quantification methods and phantom calibration, while reducing the major part of their differences, is unable to fully harmonize them. Clinical use of any normal database, therefore, requires consistency with the processing methodology. Caution must be exercised when comparing data from different centres, recognising that the SBR may represent an “index” rather than a “true” value.

Evaluation of inter-departmental variability of ejection fraction and cardiac volumes in myocardial perfusion scintigraphy using simulated data

BACKGROUND

Myocardial perfusion scintigraphy (MPS) is a clinically useful noninvasive imaging modality for diagnosing patients with suspected coronary artery disease. By utilizing gated MPS, the end diastolic volume (EDV) and end systolic volume (ESV) can be measured and the ejection fraction (EF) calculated, which gives incremental prognostic value compared with assessment of perfusion only. The aim of this study was to evaluate the inter-departmental variability of EF, ESV, and EDV during gated MPS in Sweden.

METHODS

Seventeen departments were included in the study. The SIMIND Monte Carlo (MC) program together with the XCAT phantom was used to simulate three patient cases with different EDV, ESV, and EF. Individual simulations were performed for each department, corresponding to their specific method of performing MPS. Images were then sent to each department and were evaluated according to clinical routine. EDV, ESV, and EF were reported back.

RESULTS

There was a large underestimation of EDV and ESV for all three cases. Mean underestimation for EDV varied between 26% and 52% and for ESV between 15% and 60%. EF was more accurately measured, but mean bias still varied between an underestimation of 24% to an overestimation of 14%. In general, the intra-departmental variability for EDV, ESV, and EF was small, whereas inter-departmental variability was larger.

CONCLUSIONS

Left ventricular volumes were generally underestimated, whereas EF was more accurately estimated. There was, however, large inter-departmental variability.

Neurobiology of Sleep Disturbances in PTSD Patients and Traumatized Controls: MRI and SPECT Findings

OBJECTIVE

Sleep disturbances such as insomnia and nightmares are core components of post-traumatic stress disorder (PTSD), yet their neurobiological relationship is still largely unknown. We investigated brain alterations related to sleep disturbances in PTSD patients and controls by using both structural and functional neuroimaging techniques.

METHOD

Thirty-nine subjects either developing (n = 21) or not developing (n = 18) PTSD underwent magnetic resonance imaging and a symptom-provocation protocol followed by the injection of 99mTc-hexamethylpropyleneamineoxime. Subjects were also tested with diagnostic and self-rating scales on the basis of which a Sleep Disturbances Score (SDS; i.e., amount of insomnia/nightmares) was computed.

RESULTS

Correlations between SDS and gray matter volume (GMV)/regional cerebral blood flow (rCBF) were computed in the whole sample and separately in the PTSD and control groups. In the whole sample, higher sleep disturbances were associated with significantly reduced GMV in amygdala, hippocampus, anterior cingulate, and insula; increased rCBF in midbrain, precuneus, and insula; and decreased rCBF in anterior cingulate. This pattern was substantially confirmed in the PTSD group, but not in controls.

CONCLUSION

Sleep disturbances are associated with GMV loss in anterior limbic/paralimbic, PTSD-sensitive structures and with functional alterations in regions implicated in rapid eye movement-sleep control, supporting the existence of a link between PTSD and sleep disturbance.

Effects on the FDG distribution by a high uptake of brown adipose tissue at PET examination

Background

At fluorodeoxyglucose/positron emission tomography (FDG/PET) examinations, a generally increased uptake of the skeletal muscles is sometimes encountered. As the tracer distribution constitutes a ‘zero-sum-game’, the uptake of lesions as well as of normal tissues is reduced in these patients. This has to be considered at calculation of standardised uptake values (SUVs), especially at longitudinal examinations in the same patient. In the current study, a possible similar influence on the FDG distribution by a high uptake of brown adipose tissue (BAT) was studied.

Methods

Twelve patients with strongly increased BAT uptake were examined twice with a mean of 5 days (study group). In six of these patients, there was at least one pathological lesion with increased uptake. The BAT uptake was normalised at the second examination after pretreatment with propranolol. SUVs of the pathological lesions and of the liver, spleen, lung, blood, skeletal muscles, bone marrow, gluteal fat, abdomen and heart were assessed. In order to control the effects of propranolol on normal organs/tissues, which could interfere with the findings, 25 age and gender matched normal controls were also studied (control subjects).

Results

In the study group, there was only a lower bone marrow uptake after propranolol administration. Comparing the study group with the control subjects, the bone marrow activity was higher at examination before propranolol treatment compared to the control subjects. There was also a higher uptake of the spleen in the study group before propranolol treatment compared to the control subjects. There were no differences between the study group after propranolol administration and the control subjects.

Conclusions

The differences found are small and cannot be explained, why they could be random phenomena. Together with, there were no differences between the study group after propranolol administration and the control subjects; it is concluded that an effect on the FDG distribution in patients with a strong BAT uptake by can be disregarded in clinical praxis. This is important at longitudinal examinations of patients undergoing tailored tumour therapy and in contrast to examinations in patients with a generally increased uptake of the skeletal muscles which significantly affects the distribution of the radiopharmaceutical.

Positron emission tomography neuroimaging in amyotrophic lateral sclerosis: what is new?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease involving upper and lower motor neurons, extra-motor neurons, microglia and astrocytes. The neurodegenerative process results in progressive muscle paralysis and even in cognitive impairment. Within the complex diagnostic work-up, positron emission tomography (PET) represents a valuable imaging tool in the assessment of patients with ALS. PET, by means of different radiotracers (i.e. 18F-fluorodeoxyglucose, 6-[18F]fluoro-L-dopa, [11C]flumazenil) can assess the status of the wide range of brain regions and neural circuits, which can be affected by ALS. Furthermore, experimental radiocompounds have been developed for the evaluation of white matter, which plays a role in the progression of the disease. Here we present a comprehensive review including in different sections the most relevant PET studies: studies investigating ALS and ALS-mimicking conditions (especially primary lateral sclerosis and other neurodegenerative diseases), articles selecting specific subsets of patients (with bulbar or spinal onset), studies investigating patients with familial type of ALS, studies evaluating the role of the white matter in ALS and papers evaluating the diagnostic sensitivity of PET in ALS patients.

Towards mapping the brain connectome in depression: functional connectivity by perfusion SPECT

Several studies have demonstrated altered brain functional connectivity in the resting state in depression. However, no study has investigated interregional networking in patients with persistent depressive disorder (PDD). The aim of this study was to assess differences in brain perfusion distribution and connectivity between large groups of patients and healthy controls. Participants comprised 91 patients with PDD and 65 age- and sex-matched healthy controls. Resting state perfusion was investigated by single photon emission computed tomography, and group differences were assessed by Statistical Parametric Mapping. Brain connectivity was explored through a voxel-wise interregional correlation analysis using as covariate of interest the normalized values of clusters of voxels in which perfusion differences were found in group analysis. Significantly increased regional brain perfusion distribution covering a large part of the cerebellum was observed in patients as compared with controls. Patients showed a significant negative functional connectivity between the cerebellar cluster and caudate, bilaterally. This study demonstrated inverse relative perfusion between the cerebellum and the caudate in PDD. Functional uncoupling may be associated with a dysregulation between the role of the cerebellum in action control and of the caudate in action selection, initiation and decision making in the patients. The potential impact of the resting state condition and the possibility of mitochondrial impairment are discussed.

(18)F-MCL-524, an (18)F-Labeled Dopamine D2 and D3 Receptor Agonist Sensitive to Dopamine: A Preliminary PET Study

PET has been used to examine changes in neurotransmitter concentrations in the living brain. Pioneering PET studies on the dopamine system have used D2 and D3 receptor (D2/D3) antagonists such as (11)C-raclopride. However, more recently developed agonist radioligands have shown enhanced sensitivity to endogenous dopamine. A limitation of available agonist radioligands is that they incorporate the short-lived radioisotope (11)C. In the current study, we developed the (18)F-labeled D2/D3 receptor agonist (R)-(-)-2-(18)F-fluoroethoxy-N-n-propylnorapomorphine ((18)F-MCL-524).

METHODS

In total, 10 PET measurements were conducted on 5 cynomolgus monkeys. Initially, the binding of (18)F-MCL-524 was compared with that of (11)C-MNPA in 3 monkeys. Second, the specificity of (18)F-MCL-524 binding was examined in pretreatment studies using raclopride (1.0 mg/kg) and d-amphetamine (1.0 mg/kg). Third, a preliminary kinetic analysis was performed using the radiometabolite-corrected arterial input function of the baseline studies. Finally, 2 whole-body PET measurements were conducted to evaluate biodistribution and radiation dosimetry after intravenous injection of (18)F-MCL-524.

RESULTS

(18)F-MCL-524 entered the brain and provided striatum-to-cerebellum ratios suitable for reliable quantification of receptor binding using the multilinear reference tissue model. Mean striatal nondisplaceable binding potential (BPND) values were 2.0 after injection of (18)F-MCL-524 and 1.4 after (11)C-MNPA. The ratio of the BPND values of (18)F-MCL-524 and (11)C-MNPA was 1.5 across striatal subregions. After administration of raclopride and d-amphetamine, the (18)F-MCL-524 BPND values were reduced by 89% and 56%, respectively. Preliminary kinetic analysis demonstrated that BPND values obtained with the 1-tissue- and 2-tissue-compartment models were similar to values obtained with the multilinear reference tissue model. Estimated radiation doses were highest for gallbladder (0.27 mSv/MBq), upper large intestine (0.19 mSv/MBq), and small intestine (0.17 mSv/MBq). The estimated effective dose was 0.035 mSv/MBq.

CONCLUSION

The (18)F-labeled agonist (18)F-MCL-524 appears suitable for quantification of D2/D3 receptor binding in vivo, and the results encourage extension to human studies. The longer half-life of (18)F makes (18)F-MCL-524 attractive for studies on modulation of the dopamine concentration-for example, in combination with simultaneous measurement of changes in blood-oxygen-level-dependent signal using bimodal PET/functional MRI.

Technical requirements for Na¹⁸F PET bone imaging of patients being treated using a Taylor spatial frame

Diagnosis of new bone growth in patients with compound tibia fractures or deformities treated using a Taylor spatial frame is difficult with conventional radiography because the frame obstructs the images and creates artifacts. The use of Na(18)F PET studies may help to eliminate this difficulty.

METHODS

Patients were positioned on the pallet of a clinical PET/CT scanner and made as comfortable as possible with their legs immobilized. One bed position covering the site of the fracture, including the Taylor spatial frame, was chosen for the study. A topogram was performed, as well as diagnostic and attenuation correction CT. The patients were given 2 MBq of Na(18)F per kilogram of body weight. A 45-min list-mode acquisition was performed starting at the time of injection, followed by a 5-min static acquisition 60 min after injection. The patients were examined 6 wk after the Taylor spatial frame had been applied and again at 3 mo to assess new bone growth.

RESULTS

A list-mode reconstruction sequence of 1 × 1,800 and 1 × 2,700 s, as well as the 5-min static scan, allowed visualization of regional bone turnover.

CONCLUSION

With Na(18)F PET/CT, it was possible to confirm regional bone turnover as a means of visualizing bone remodeling without the interference of artifacts from the Taylor spatial frame. Furthermore, dynamic list-mode acquisition allowed different sequences to be performed, enabling, for example, visualization of tracer transport from blood to the fracture site.

Neurobiological insight into hyperbaric hyperoxia

AIM

Hyperbaric hyperoxia (HBO) is known to modulate aerobic metabolism, vasoreactivity and blood flow in the brain. Nevertheless, mechanisms underlying its therapeutic effects, especially in traumatic brain injury (TBI) and stroke patients, are debated. The present study aimed at investigating regional cerebral blood flow (rCBF) distribution during acute HBO exposure.

METHODS

Regional cerebral blood flow response was investigated in seven healthy subjects exposed to either normobaric normoxia or HBO with ambient pressure/inspired oxygen pressure of 101/21 and 250/250 kPa respectively. After 40 min at the desired pressure, they were injected a perfusion tracer and subsequently underwent brain single photon emission computed tomography. rCBF distribution changes in the whole brain were assessed by Statistical Parametric Mapping.

RESULTS

During HBO, an increased relative rCBF distribution was found in sensory-motor, premotor, visual and posterior cingulate cortices as well as in superior frontal gyrus, middle/inferior temporal and angular gyrus and cerebellum, mainly in the dominant hemisphere. During normobaric normoxia, a higher (99m) Tc-HMPAO distribution in the right insula and subcortical structures as well as in bilateral hippocampi and anterior cingulated cortex was found.

CONCLUSIONS

The present study firstly confirmed the rCBF distribution increase during HBO in sensory-motor and visual cortices, and it showed for the first time a higher perfusion tracer distribution in areas encompassed in dorsal attention system and in default mode network. These findings unfold both the externally directed cognition performance improvement related to the HBO and the internally directed cognition states during resting-state conditions, suggesting possible beneficial effects in TBI and stroke patients.

Gray matter volume alterations related to trait dissociation in PTSD and traumatized controls

OBJECTIVE

This study used voxel-based morphometry (VBM) to investigate brain structural alterations related to trait dissociation and its relationship with post-traumatic stress disorder (PTSD).

METHOD

Thirty-two subjects either developing (N = 15) or non-developing (N = 17) PTSD underwent MRI scanning and were assessed with the Dissociative Experience Scale (DES), subscales for pathological (DES-T) and non-pathological trait (DES-A) dissociation, and other clinical measures. Gray matter volume (GMV) was analyzed using VBM as implemented in SPM. PTSD and non-PTSD subjects were compared to assess brain alterations related to PTSD pathology, whereas correlation analyses between dissociation measures and GMV were performed on the whole sample (N = 32), irrespective of PTSD diagnosis, to identify alterations related to trait dissociation.

RESULTS

As compared to traumatized controls, PTSD subjects showed reduced GMV in the prefrontal cortex, hippocampus and lingual gyrus. Correlations with dissociation measures (DES, DES-T, and DES-A) consistently showed increased GMV in the medial and lateral prefrontal, orbitofrontal, parahippocampal, temporal polar, and inferior parietal cortices.

CONCLUSION

PTSD and dissociation seem to be associated with opposite volumetric patterns in the prefrontal cortex. Trait dissociation appears to involve increased GMV in prefrontal, paralimbic, and parietal cortices, with negligible differences between pathological and non-pathological dissociation.

The relation between the blood glucose level and the FDG uptake of tissues at normal PET examinations

Background

The influence of the blood glucose level on the tracer uptake of normal tissues at [¹⁸F]-2-fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) was retrospectively studied in examinations in clinical patients.

Methods

Five hundred examinations were evaluated in retrospect. The inclusion criteria were studies with a normal or near-normal FDG distribution. Patients who had been subjected to chemotherapy (including GSF treatment) or radiotherapy <4 weeks prior to the examination were excluded; we cannot exclude, however, that in a very few patients the available information might have been incomplete. Otherwise, patients were included regardless of concurrent diseases and/or therapy. In one evaluation, the mean standardized uptake value of the liver, spleen, lungs, peripheral blood, selected muscles and bone marrow of all 500 individuals was correlated to the blood glucose level. In another evaluation, a subgroup of 62 patients with increased blood glucose levels (≥7.0 mmol/l) was compared with another subgroup of 62 patients paired with regard to age and gender with blood glucose levels within normal range (≤6.0 mmol/l).

Results

There was a weak positive correlation between the blood glucose level and the muscular uptake of FDG, while there was no correlation with the tracer uptake of the liver, spleen, lungs, peripheral blood or bone marrow. The patient group with increased blood glucose levels showed a slightly, but significantly, higher muscular FDG uptake compared with the matched subgroup of patients with normal blood glucose levels. When comparing the other assessed tissues/organs, there were no differences between these two patient groups.

Conclusions

The effect of hyperglycaemia at FDG PET on the studied normal tissues is restricted to a slightly increased muscular uptake. The effect of the blood glucose level on the blood activity at the time of examination is negligible.

Dynamic PET/CT measurements of induced positron activity in a prostate cancer patient after 50-MV photon radiation therapy

Background

The purpose of this work was to reveal the research interest value of positron emission tomography (PET) imaging in visualizing the induced tissue activity post high-energy photon radiation treatment. More specifically, the focus was on the possibility of retrieving data such as tissue composition and physical half-lives from dynamic PET acquisitions, as positron-emitting radionuclides such as ¹⁵O, ¹¹C, and ¹³N are produced in vivo during radiation treatment with high-energy photons (>15 MeV). The type, amount, and distribution of induced positron-emitting radionuclides depend on the irradiated tissue cross section, the photon spectrum, and the possible perfusion-driven washout.

Methods

A 62-year-old man diagnosed with prostate cancer was referred for palliative radiation treatment of the pelvis minor. A total dose of 8 Gy was given using high-energy photon beams (50 MV) with a racetrack microtron, and 7 min after the end of irradiation, the patient was positioned in a PET/computed tomography (CT) camera, and a list-mode acquisition was performed for 30 min. Two volumes of interests (VOIs) were positioned on the dynamic PET/CT images, one in the urinary bladder and the other in the subcutaneous fat. Analysis of the measured relative count rate was performed in order to compute the tissue compositions and physical half-lives in the two regions.

Results

Dynamic analysis from the two VOIs showed that the decay constants of activated oxygen and carbon could be deduced. Calculation of tissue composition from analyzing the VOI containing subcutaneous fat only moderately agreed with that of the tabulated International Commission on Radiation Units & Measurements (ICRU) data of the adipose tissue. However, the same analysis for the bladder showed a good agreement with that of the tabulated ICRU data.

Conclusions

PET can be used in visualizing the induced activity post high-energy photon radiation treatment. Despite the very low count rate in this specific application, wherein 7 min after treatment was about 5% of that of a standard ¹⁸F-FDG PET scan, the distribution of activated tissue elements (¹⁵O and ¹¹C) could be calculated from the dynamic PET data. One possible future application of this method could possibly be to measure and determine the tumor tissue composition in order to identify any hypoxic or necrotic region, which is information that can be used in the ongoing therapy planning process.

Trial registration

The official name of the trial committee of this study is ‘Regionala etikprövningsnämnden i Stockholm’ (FE 289, Stockholm, SE-17177, Sweden). The unique identifying number is 2011/1789-31/2.

Incidence of respiratory viruses in patients with community-acquired pneumonia admitted to the intensive care unit: results from the Severe Influenza Pneumonia Surveillance (SIPS) project

Few patients with community-acquired pneumonia (CAP) require admission to the intensive care unit (ICU-CAP). However, they represent the most severe form of the disease. An understanding of the etiologic agents of ICU-CAP may lead to better treatment decisions and patient outcomes. The objective of this study was to determine the incidence of respiratory viruses in patients with ICU-CAP. This was an observational study conducted in six Kentucky hospitals from December 2008 through October 2011. A case of ICU-CAP was defined as a patient admitted to an ICU with the diagnosis of CAP. The Luminex xTAG multiplex polymerase chain reaction (PCR) assay was used for viral identification. A total of 468 adult and pediatric patients with ICU-CAP were enrolled in the study. A total of 92 adult patients (23 %) and 14 pediatric patients (19 %) had a respiratory virus identified. Influenza was the most common virus identified in adults and the second most common in pediatric patients. This study suggests that respiratory viruses may be common etiologic agents of pneumonia in patients with ICU-CAP. The Centers for Disease Control and Prevention (CDC) recommend empiric anti-influenza therapy during the winter for hospitalized patients with CAP. This study supports this recommendation in patients with ICU-CAP.

Simplified quantification and whole-body distribution of [18F]FE-PE2I in nonhuman primates: prediction for human studies

INTRODUCTION

[(18)F]FE-PE2I is a promising dopamine transporter (DAT) radioligand. In nonhuman primates, we examined the accuracy of simplified quantification methods and the estimates of radiation dose of [(18)F]FE-PE2I.

METHODS

In the quantification study, binding potential (BP(ND)) values previously reported in three rhesus monkeys using kinetic and graphical analyses of [(18)F]FE-PE2I were used for comparison. BP(ND) using the cerebellum as reference region was obtained with four reference tissue methods applied to the [(18)F]FE-PE2I data that were compared with the kinetic and graphical analyses. In the whole-body study, estimates of adsorbed radiation were obtained in two cynomolgus monkeys.

RESULTS

All reference tissue methods provided BP(ND) values within 5% of the values obtained with the kinetic and graphical analyses. The shortest imaging time for stable BP(ND) estimation was 54 min. The average effective dose of [(18)F]FE-PE2I was 0.021 mSv/MBq, similar to 2-deoxy-2-[(18)F]fluoro-d-glucose.

CONCLUSIONS

The results in nonhuman primates suggest that [(18)F]FE-PE2I is suitable for accurate and stable DAT quantification, and its radiation dose estimates would allow for a maximal administered radioactivity of 476 MBq in human subjects.

Impact of acute hypobaric hypoxia on blood flow distribution in brain

AIM

Acute hypobaric hypoxia is well known to alter brain circulation and to cause neuropsychological impairment. However, very few studies have examined the regional changes occurring in the brain during acute exposure to extreme hypoxic conditions.

METHODS

Regional cerebral blood flow (rCBF) response to hypoxia was investigated in six healthy subjects exposed to either normobaric normoxia or hypobaric hypoxia with ambient pressure/inspired oxygen pressure of 101/21 kPa and 50/11 kPa respectively. After 40 min at the desired pressure they were injected (99m)Tc-HMPAO and subsequently underwent single photon emission computed tomography. Regional cerebral blood flow distribution changes in the whole brain were assessed by Statistical Parametric Mapping, a well established voxel-based analysis method.

RESULTS

Hypobaric hypoxia increased rCBF distribution in sensorymotor and prefrontal cortices and in central structures. PCO(2) correlated positively and SatO(2) negatively with rCBF in several temporal, parahippocampal, parietal and central structures.

CONCLUSIONS

These findings underscore the specific sensitivity of the frontal lobe to acute hypobaric hypoxia and of limbic and central structures to blood gas changes emphasizing the involvement of these brain areas in acute hypoxia.

Evaluation of preoperative lymphoscintigraphy and sentinel node procedure in vulvar cancer

OBJECTIVE

To assess the value of preoperative lymphoscintigraphy, and to evaluate the validity and feasibility of the sentinel node (SN) procedure in vulvar carcinoma.

STUDY DESIGN

Retrospective clinical and histopathological review of 77 patients with invasive squamous cell carcinoma in vulva who were treated at Karolinska University Hospital Stockholm, Sweden, from 2000 to 2007. The patients underwent SN mapping preoperatively with radioactive tracer and blue dye (n=60) or only blue dye (n=17). The SN was removed separately followed by complete inguinofemoral lymphadenectomy.

RESULTS

The relation between SNs detected on the scintigram and those found during surgery showed good agreement using weighted kappa. The detection rate of SN was 98% for radioisotope plus blue dye, and 94% for blue dye alone. Two cases of false negative SN (false negative rate 2.7%) were found, both with large midline tumors.

CONCLUSION

Preoperative scintigram is a valuable help to identify and localize the SNs and gives the best estimate of the accurate number but cannot determine if unilateral or bilateral groins should be explored in cases of midline tumors. Our results are in favor of using radioisotope and blue dye to identify the SNs. This study support previous reports that the method is not recommended for tumors larger than 40 mm to optimize detection of SN and minimize the false negative detection rate.

Effects of EMDR psychotherapy on 99mTc-HMPAO distribution in occupation-related post-traumatic stress disorder

BACKGROUND

Post-traumatic stress disorder (PTSD) is a derangement of mood control with involuntary, emotionally fraught recollections that may follow deep psychological trauma in susceptible individuals. This condition is treated with pharmacological and/or cognitive therapies as well as psychotherapy with eye movement desensitization and reprocessing (EMDR). However, only a very limited number of studies have been published dealing with work-related PTSD, and investigations on the effect of treatment on cerebral blood flow represent an even smaller number.

AIM

To investigate the short-term outcome of occupation-related PTSD after EMDR therapy by 99mTc-HMPAO SPECT.

METHOD

Fifteen patients, either train drivers suffering from PTSD after having been unintentionally responsible for a person-under-train accident or employees assaulted in the course of duty, were recruited for the study. 99mTc-HMPAO SPECT was performed on these patients both before and after EMDR therapy while they listened to a script portraying the traumatic event. Tracer distribution analysis was then carried out at volume of interest (VOI) level using a three-dimensional standardized brain atlas, and at voxel level by SPM. The CBF data of the 15 patients were compared before and after treatment as well as with those of a group of 27 controls who had been exposed to the same psychological traumas without developing PTSD.

RESULTS

At VOI analysis significant CBF distribution differences were found between controls and patients before and after treatment (P=0.023 and P=0.0039, respectively). Eleven of the 15 patients responded to treatment, i.e., following EMDR they no longer fulfilled the DSM-IV criteria for PTSD. When comparing only the eleven responders with the controls, the significant group difference found before EMDR (P=0.019) disappeared after treatment. Responders and non-responders showed after therapy significant regional differences in frontal, parieto-occipital and visual cortex and in hippocampus. SPM analysis showed significant uptake differences between patients and controls in the orbitofrontal cortex (Brodmann 11) and the temporal pole (Brodmann 38) both before and after treatment. A significant tracer distribution difference present before treatment in the uncus (Brodmann 36) disappeared after treatment, while a significant difference appeared in the lateral temporal lobe (Brodmann 21).

CONCLUSION

Significant 99mTc-HMPAO uptake regional differences were found, mainly in the peri-limbic cortex, between PTSD patients and controls exposed to trauma but not developing PTSD. Tracer uptake differences between responders and patients not responding to EMDR were found after treatment suggesting a trend towards normalization of tracer distribution after successful therapy. These findings in occupational related PTSD are consistent with previously described effects of psychotherapy on anxiety disorders.

Release of sequestered malaria parasites upon injection of a glycosaminoglycan

Severe human malaria is attributable to an excessive sequestration of Plasmodium falciparum–infected and uninfected erythrocytes in vital organs. Strains of P. falciparum that form rosettes and employ heparan sulfate as a host receptor are associated with development of severe forms of malaria. Heparin, which is similar to heparan sulfate in that it is composed of the same building blocks, was previously used in the treatment of severe malaria, but it was discontinued due to the occurrence of serious side effects such as intracranial bleedings. Here we report to have depolymerized heparin by periodate treatment to generate novel glycans (dGAG) that lack anticoagulant-activity. The dGAGs disrupt rosettes, inhibit merozoite invasion of erythrocytes and endothelial binding of P. falciparum–infected erythrocytes in vitro, and reduce sequestration in in vivo models of severe malaria. An intravenous injection of dGAGs blocks up to 80% of infected erythrocytes from binding in the micro-vasculature of the rat and releases already sequestered parasites into circulation. P. falciparum–infected human erythrocytes that sequester in the non-human primate Macaca fascicularis were similarly found to be released in to the circulation upon a single injection of 500 μg of dGAG. We suggest dGAGs to be promising candidates for adjunct therapy in severe malaria.

Severe Plasmodium falciparum malaria is common and in part the result of an excessive binding of infected erythrocytes in the microvasculature. The parasite employs heparan sulfate during the adherence to the vascular endothelium and to erythrocytes. Heparin, which is related to heparan sulfate in that it is composed of the same building blocks, was here periodate-treated to generate depolymerized glycosaminoglycans (dGAGs) that possess no anticoagulant activity. The dGAGs disrupt erythrocyte and endothelial binding of P. falciparum–infected erythrocytes in vitro. An intravenous injection of dGAGs blocks infected erythrocytes from binding in the micro-vasculature of the rat and releases already sequestrated parasites into circulation both in the rat and in a non-human primate. If this approach is successfully translated to the clinical setting, it may offer help to patients whereby the injection of a dGAG releases already sequestered parasite-infected erythrocytes and re-establishes the micro-vascular blood flow. The authors suggest dGAGs to be promising candidates of adjunct therapy that may have an important impact on malaria mortality.

Generation of cross-protective antibodies against Plasmodium falciparum sequestration by immunization with an erythrocyte membrane protein 1-duffy binding-like 1 alpha domain

The Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) is an important virulence factor on the surface of infected erythrocytes. Naturally acquired antibodies to PfEMP1 expressed by parasites causing severe malaria are suggested to be protective and of major interest for the development of a vaccine against severe disease. In this study, the PfEMP1 expressed by a parasite clone displaying a multiadhesive phenotype associated with severe malaria was well recognized by sera of malaria semi-immune children. The efficiency of the Duffy binding-like 1 alpha (DBL1 alpha) domain of this PfEMP1 was therefore, alone or in combination with two additional DBL1 alpha domains, evaluated as a potential vaccine candidate using both a rodent model and a primate model. Antibodies against the DBL1 alpha domain were generated by immunization with recombinant DBL1 alpha-Semliki Forest virus particles and recombinant protein and analyzed in vitro. The immunized animals were challenged in vivo with various parasite strains or clones. Immunization with the PfEMP1-DBL1 alpha domain abolished the PfEMP1-dependent sequestration of the homologous strain in immunized rats and substantially inhibited parasite adhesion in immunized monkeys. Protection against sequestration of heterologous parasite strains was also confirmed by direct or indirect challenge in the rat model. These results strongly support the use of the DBL1 alpha domain in the development of a vaccine targeting severe malaria.

Development of dose delivery verification by PET imaging of photonuclear reactions following high energy photon therapy

A method for dose delivery monitoring after high energy photon therapy has been investigated based on positron emission tomography (PET). The technique is based on the activation of body tissues by high energy bremsstrahlung beams, preferably with energies well above 20 MeV, resulting primarily in 11C and 15O but also 13N, all positron-emitting radionuclides produced by photoneutron reactions in the nuclei of 12C, 16O and 14N. A PMMA phantom and animal tissue, a frozen hind leg of a pig, were irradiated to 10 Gy and the induced positron activity distributions were measured off-line in a PET camera a couple of minutes after irradiation. The accelerator used was a Racetrack Microtron at the Karolinska University Hospital using 50 MV scanned photon beams. From photonuclear cross-section data integrated over the 50 MV photon fluence spectrum the predicted PET signal was calculated and compared with experimental measurements. Since measured PET images change with time post irradiation, as a result of the different decay times of the radionuclides, the signals from activated 12C, 16O and 14N within the irradiated volume could be separated from each other. Most information is obtained from the carbon and oxygen radionuclides which are the most abundant elements in soft tissue. The predicted and measured overall positron activities are almost equal (-3%) while the predicted activity originating from nitrogen is overestimated by almost a factor of two, possibly due to experimental noise. Based on the results obtained in this first feasibility study the great value of a combined radiotherapy-PET-CT unit is indicated in order to fully exploit the high activity signal from oxygen immediately after treatment and to avoid patient repositioning. With an RT-PET-CT unit a high signal could be collected even at a dose level of 2 Gy and the acquisition time for the PET could be reduced considerably. Real patient dose delivery verification by means of PET imaging seems to be applicable provided that biological transport processes such as capillary blood flow containing mobile 15O and 11C in the activated tissue volume can be accounted for.

Imaging the neurobiological substrate of atypical depression by SPECT

PURPOSE

Neurobiological abnormalities underlying atypical depression have previously been suggested. The purpose of this study was to explore differences at functional brain imaging between depressed patients with and without atypical features and healthy controls.

METHODS

Twenty-three out-patients with chronic depressive disorder recruited from a service for patients with audiological symptoms were investigated. Eleven fulfilled the DSM-IV criteria for atypical depression (mood reactivity and at least two of the following: weight gain, hypersomnia, leaden paralysis and interpersonal rejection sensitivity). Twenty-three healthy subjects served as controls. Voxel-based analysis was applied to explore differences in (99m)Tc-HMPAO uptake between groups.

RESULTS

Patients in the atypical group had a higher prevalence of bilateral hearing impairment and higher depression and somatic distress ratings at the time of SPECT. Significantly higher tracer uptake was found bilaterally in the atypical group as compared with the non-atypicals in the sensorimotor (Brodmann areas, BA1-3) and premotor cortex in the superior frontal gyri (BA6), in the middle frontal cortex (BA8), in the parietal associative cortex (BA5, BA7) and in the inferior parietal lobule (BA40). Significantly lower tracer distribution was found in the right hemisphere in the non-atypicals compared with the controls in BA6, BA8, BA44, BA45 and BA46 in the frontal cortex, in the orbito-frontal cortex (BA11, BA47), in the postcentral parietal cortex (BA2) and in the multimodal association parietal cortex (BA40).

CONCLUSION

The differences found between atypical and non-atypical depressed patients suggest different neurobiological substrates in these patient groups. The putative links with the clinical features of atypical depression are discussed. These findings encourage the use of functional neuroimaging in psychiatric disorders.

Induction of cross-reactive immune responses to NTS-DBL-1alpha/x of PfEMP1 and in vivo protection on challenge with Plasmodium falciparum

The interactions of Plasmodium falciparum infected erythrocytes parasitized red blood cells (pRBC) with endothelial receptors and erythrocytes are mediated by multiple Duffy-binding like (DBL) and cysteine-rich interdomain region (CIDR) domains harboured in the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). The success of a subunit vaccine based on PfEMP1 depends on its ability to elicit cross-reactive responses to a substantial number of PfEMP1 variants. We have here evaluated serological PfEMP1 cross-reactivity by immunizing rats with phylogenetically diverse recombinant NTS-DBL-1alpha/x fusion domains from the 3D7 genome parasite emulsified in Montanide ISA 720. Cross-reactivity was elicited to these diverse DBL-1alpha/x domains as measured by ELISA and by immunoblotting. Employing a novel in vivo model of human infected erythrocyte sequestration, immunized animals were challenged with the FCR3S1.2 clone and cross-protection in terms of reduction in lung sequestration amounting to approximately 50% was demonstrated. Our results suggest that immunization with phylogenetically distant DBL-1alpha/x variants, can elicit partial cross-protection to challenge with the parasites harbouring a distant variant. These observations have implications for the design of multi-component vaccines against P. falciparum malaria.

Whole-body imaging of sequestration of Plasmodium falciparum in the rat

The occlusion of vessels by packed Plasmodium falciparum-infected (iRBC) and uninfected erythrocytes is a characteristic postmortem finding in the microvasculature of patients with severe malaria. Here we have employed immunocompetent Sprague-Dawley rats to establish sequestration in vivo. Human iRBC cultivated in vitro and purified in a single step over a magnet were labeled with 99mtechnetium, injected into the tail vein of the rat, and monitored dynamically for adhesion in the microvasculature using whole-body imaging or imaging of the lungs subsequent to surgical removal. iRBC of different lines and clones sequester avidly in vivo while uninfected erythrocytes did not. Histological examination revealed that a multiadhesive parasite adhered in the larger microvasculature, inducing extensive intravascular changes while CD36- and chondroitin sulfate A-specific parasites predominantly sequester in capillaries, inducing no or minor pathology. Removal of the adhesive ligand Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1), preincubation of the iRBC with sera to PfEMP1 or preincubation with soluble PfEMP1-receptors prior to injection significantly reduced the sequestration. The specificity of iRBC binding to the heterologous murine receptors was confirmed in vitro, using primary rat lung endothelial cells and rat lung cryosections. In offering flow dynamics, nonmanipulated endothelial cells, and an intact immune system, we believe this syngeneic animal model to be an important complement to existing in vitro systems for the screening of vaccines and adjunct therapies aiming at the prevention and treatment of severe malaria.

Principal component and volume of interest analyses in depressed patients imaged by 99mTc-HMPAO SPET: a methodological comparison

Previous regional cerebral blood flow (rCBF) studies on patients with unipolar major depressive disorder (MDD) have analysed clusters of voxels or single regions and yielded conflicting results, showing either higher or lower rCBF in MDD as compared to normal controls (CTR). The aim of this study was to assess rCBF distribution changes in 68 MDD patients, investigating the data set with both volume of interest (VOI) analysis and principal component analysis (PCA). The rCBF distribution in 68 MDD and 66 CTR, at rest, was compared. Technetium-99m d, l-hexamethylpropylene amine oxime single-photon emission tomography was performed and the uptake in 27 VOIs, bilaterally, was assessed using a standardising brain atlas. Data were then grouped into factors by means of PCA performed on rCBF of all 134 subjects and based on all 54 VOIs. VOI analysis showed a significant group x VOI x hemisphere interaction ( P<0.001). rCBF in eight VOIs (in the prefrontal, temporal, occipital and central structures) differed significantly between groups at the P<0.05 level. PCA identified 11 anatomo-functional regions that interacted with groups ( P<0.001). As compared to CTR, MDD rCBF was relatively higher in right associative temporo-parietal-occipital cortex ( P<0.01) and bilaterally in prefrontal ( P<0.005) and frontal cortex ( P<0.025), anterior temporal cortex and central structures ( P<0.05 and P<0.001 respectively). Higher rCBF in a selected group of MDD as compared to CTR at rest was found using PCA in five clusters of regions sharing close anatomical and functional relationships. At the single VOI level, all eight regions showing group differences were included in such clusters. PCA is a data-driven method for recasting VOIs to be used for group evaluation and comparison. The appearance of significant differences absent at the VOI level emphasises the value of analysing the relationships among brain regions for the investigation of psychiatric disease.

C-peptide improves adenosine-induced myocardial vasodilation in type 1 diabetes patients

Patients with type 1 (insulin-dependent) diabetes show reduced skeletal muscle blood flow and coronary vasodilatory function despite intensive insulin therapy and good metabolic control. Administration of proinsulin C-peptide increases skeletal muscle blood flow in these patients, but a possible influence of C-peptide on myocardial vasodilatory function in type 1 diabetes has not been investigated. Ten otherwise healthy young male type 1 diabetic patients (Hb A1c 6.6%, range 5.7-7.9%) were studied on two consecutive days during normoinsulinemia and euglycemia in a double-blind, randomized, crossover design, receiving intravenous infusion of C-peptide (5 pmol.kg-1.min-1) for 120 min on one day and saline infusion on the other day. Myocardial blood flow (MBF) was measured at rest and during adenosine administration (140 microg.kg-1.min-1) both before and during the C-peptide or saline infusions by use of positron emission tomography and [15O]H2O administration. Basal MBF was not significantly different in the patients compared with an age-matched control group, but adenosine-induced myocardial vasodilation was 30% lower (P < 0.05) in the patients. During C-peptide administration, adenosine-stimulated MBF increased on average 35% more than during saline infusion (P < 0.02) and reached values similar to those for the healthy controls. Moreover, as evaluated from transthoracal echocardiographic measurements, C-peptide infusion resulted in significant increases in both left ventricular ejection fraction (+5%, P < 0.05) and stroke volume (+7%, P < 0.05). It is concluded that short-term C-peptide infusion in physiological amounts increases the hyperemic MBF and left-ventricular function in type 1 diabetic patients.

Hantavirus infection in people inhabiting a highly endemic region of the Gran Chaco territory, Paraguay: association with Trypanosoma cruzi infection, epidemiological features and haematological characteristics

The seroprevalences of anti-hantavirus antibodies were determined in 712 individuals (551 Indians, 140 Mennonites of German ancestry, and 21 Paraguayans of Spanish ancestry) inhabiting a region of western Paraguay in the Gran Chaco territory of South America. The overall seroprevalence of hantavirus infection among the 712 subjects, who were aged 2-80 years, was 42.7% (45.2% in the Indians and 34.2% in the non-Indians). Of the 672 subjects also checked for antibodies against Trypanosoma cruzi, 226 (33.6%) were seropositive for this protozoan parasite. The results of a multivariate regression analysis indicated that, after adjusting for age, sex, setting of residence (rural/urban) and infection with the human T-cell leukaemia/lymphoma virus type II (HTLV-II), a T. cruzi-seropositive individual was 1.73 times more likely to be hantavirus seropositive than a T. cruzi-seronegative individual. Living in a rural setting increased the risk of being hantavirus seropositive 2.17-fold. In both the Indians and non-Indian subpopulations, hantavirus seroprevalence increased with age in both sexes, but only in the non-Indian supopulation was this increase significantly greater in males than in females. Hantavirus seropositivity was significantly associated with thrombocytosis, even after adjusting for the relevant confounders.

Regional cerebral blood flow as assessed by principal component analysis and (99m)Tc-HMPAO SPET in healthy subjects at rest: normal distribution and effect of age and gender

The increasing implementation of standardisation techniques in brain research and clinical diagnosis has highlighted the importance of reliable baseline data from normal control subjects for inter-subject analysis. In this context, knowledge of the regional cerebral blood flow (rCBF) distribution in normal ageing is a factor of the utmost importance. In the present study, rCBF was investigated in 50 healthy volunteers (25 men, 25 women), aged 31-78 years, who were examined at rest by means of single-photon emission tomography (SPET) using technetium-99m d, l-hexamethylpropylene amine oxime (HMPAO). After normalising the CBF data, 27 left and 27 right volumes of interest (VOIs) were selected and automatically outlined by standardisation software (computerised brain atlas). The heavy load of flow data thus obtained was reduced in number and grouped in factors by means of principal component analysis (PCA). PCA extracted 12 components explaining 81% of the variance and including the vast majority of cortical and subcortical regions. Analysis of variance and regression analyses were performed for rCBF, age and gender before PCA was applied and subsequently for each single extracted factor. There was a significantly higher CBF on the right side than on the left side ( P<0.001). In the overall analysis, a significant decrease was found in CBF ( P=0.05) with increasing age, and this decrease was particularly evident in the left hemisphere ( P=0.006). When gender was specifically analysed, CBF was found to decrease significantly with increasing age in females ( P=0.037) but not in males. Furthermore, a significant decrease in rCBF with increasing age was found in the brain vertex ( P=0.05), left frontotemporal cortex ( P=0.012) and temporocingulate cortex ( P=0.003). By contrast, relative rCBF in central structures increased with age ( P=0.001). The ability of standardisation software and PCA to identify functionally connected brain regions might contribute to a better understanding of the relationships between rCBF at rest, anatomically defined brain structures, ageing and gender.