AimTo investigate liver biochemistry in infants screened for biliary atresia (BA) at the time of hepatobiliary scintigraphy (HS) and to evaluate the effect of change in threshold for HS. MethodsInfants born from 2010 to 2021, who underwent HS <6 months postpartum for BA, were included and data sourced from electronic medical records. The change in threshold in 2018 from >= 20 (and/or if conjugated bilirubin exceeds 20% of total bilirubin) to >= 17 mu M (regardless of total bilirubin) was evaluated. ResultsIn the cohort of 635 infants, 48 had BA, 247 had AATD, and the remaining 343 were categorised as 'other'. After the threshold adjustment, HS timing was unaffected (p = 0.27), but the annual HS rate rose from 39 to 87, yet evaluations following the new guideline only accounted for 12%. All liver parameters were elevated in the BA group compared with the additional groups (p < 0.001). Amongst the 104 patients with non-excretory HS, gamma-glutamyl transferase (p < 0.001) and alanine aminotransferase (p = 0.002) remained elevated for BA. The lowest conjugated bilirubin measured in BA children was 36 mu M. ConclusionAfter threshold change, HS use increased without earlier BA diagnostics, but most were not due to the new guideline. Alanine aminotransferase and gamma-glutamyl transferase should be considered in BA diagnostics.

We investigated the feasibility of using a dopamine transporter (DaT) tracer ligand ([123I]FP-CIT) along with novel multi-pinhole brain collimators for dynamic brain single photon emission computed tomography (SPECT) in suspected Parkinson's disease patients. Thirteen patients underwent dynamic tracer acquisitions before standard imaging. Uptake values were corrected for partial volume effects. Specific binding ratio (SBRcalc) was calculated, reflecting binding potential relative to non-displaceable binding (BPND) in the cortex. Additional pharmacokinetic parameters (BPND, R1, k2) were estimated using the simplified reference tissue model, revealing differences between Kahraman low-score (LS) and high-score (HS) groups. Results showed increasing striatal tracer uptake until 100 min post-injection, with consistent values afterward. Uptake and SBRcalc ratios matched visual assessment. LS patients had lower putamen than caudate nucleus tracer uptake, decreased BPND values, while R1 and k2 values were comparable to HS patients. In conclusion, dynamic multi-pinhole SPECT using DaT tracer with the extraction of pharmacokinetic parameters is feasible and could help enable early differentiation of reduced and normal DaT values.

BACKGROUND:It is essential to have an accurate assessment of the renal function of patients with chronic kidney disease to monitor, treat, and predict further development of the condition. Measurement of renal function in terms of glomerular filtration rate (GFR) requires either urine or blood sampling, but especially in children, more simple methods of measurement are preferable. The main objective of this study was to examine if the estimated GFR (eGFR) calculated with different cystatin-C-based equations was comparable to the GFR measured by a radiotracer (mGFR) in pediatric patients. METHODS:In this retrospective study, 28 pediatric patients contributed with 73 pairs of measurements collected within 5 years. Bland-Altman Limits of Agreement were used to evaluate the performance and accuracy of two different cystatin-C-based estimates, the CKiDCrea-CysC and the CKiDU25 respectively, compared to an mGFR based on plasma clearance of technetium-99m-diethylenetriaminepentaacetic acid or chromium-51-ethylenediaminetetraacetic acid. RESULTS:Using the CKiDCrea-CysC equation, 58.9% of the datasets were within P10 and 87.7% were within P30. The mean difference was 4.8 mL/min/1.73m2 (standard deviation: 8.5 mL/min/1.73m2) and tended to overestimate GFR and thereby overrate the kidney function within the entire GFR range. Using the CKiDU25 equation, 53.4% were within P10 and 93.2% within P30. The mean difference was -2.9 mL/min/1.73m2 (standard deviation: 8.4 mL/min/1.73m2), but the difference varied with the GFR value. CONCLUSIONS:A cystatin-C-based eGFR provides a viable substitute for monitoring renal function in pediatric patients with chronic kidney disease. However, it has a lower accuracy than mGFR and can therefore not replace mGFR in clinical use.

Background Imaging of idiopathic inflammatory myopathies (IIMs) is challenging, and no pathognomonic signs exist. Different tracers have been tested for this purpose, mainly inflammation markers including technetium-99m-pyrophosphate (PYP). We aimed to examine the utility of fluorine-18-fluorodeoxyglucose (FDG) relative to PYP in idiopathic inflammatory myopathy (IIM). Methods Using visual grading and CT-guided muscular segmentation and standardized uptake values (SUVs), we assessed muscular tracer uptake qualitatively and quantitatively, comparing FDG uptake in eight patients with recent-onset IIM and 24 healthy control persons and FDG and PYP uptake in seven patients. Results Muscular FDG and PYP uptake was increased in all patients. However, uptake distribution and signal intensity differed considerably. FDG scans revealed clear involvement of certain muscle groups including core and swallowing muscles and, in addition, abnormality in diseased extra-muscular organs. PYP was mainly visible in bones, whereas muscular PYP uptake was generally discrete and primarily located in the extremities. Quantitatively, FDG uptake was significantly higher in patients than in controls; the volume-weighted SUVmean for all right-side muscles was 0.84 versus 0.60 g/ml (95% confidence interval (CI) for mean difference 0.14–0.34, p = 0.0001). FDG SUVmean values were up to four times higher than PYP mean values in upper limb muscles (95% CI for the mean ratio 2.37–3.77, p = 0.0004) and two–three times higher in lower limb muscles (95% CI for the mean ratio 2.28–2.71, p < 0.0001). Conclusions Muscular FDG uptake was higher in treatment-naïve IIM patients than in healthy controls and more distinct than PYP uptake in patients with a potential to reveal extra-muscular IIM involvement and malignancy. Thus, FDG appears to be superior to PYP in the diagnostic evaluation of IIM.

Objective Artificial intelligence (AI) offers new opportunities for objective quantitative measurements of imaging biomarkers from positron-emission tomography/computed tomography (PET/CT). Clinical image reporting relies predominantly on observer-dependent visual assessment and easily accessible measures like SUVmax, representing lesion uptake in a relatively small amount of tissue. Our hypothesis is that measurements of total volume and lesion uptake of the entire tumour would better reflect the disease`s activity with prognostic significance, compared with conventional measurements. Methods An AI-based algorithm was trained to automatically measure the prostate and its tumour content in PET/CT of 145 patients. The algorithm was then tested retrospectively on 285 high-risk patients, who were examined using F-18-choline PET/CT for primary staging between April 2008 and July 2015. Prostate tumour volume, tumour fraction of the prostate gland, lesion uptake of the entire tumour, and SUVmax were obtained automatically. Associations between these measurements, age, PSA, Gleason score and prostate cancer-specific survival were studied, using a Cox proportional-hazards regression model. Results Twenty-three patients died of prostate cancer during follow-up (median survival 3.8 years). Total tumour volume of the prostate (p = 0.008), tumour fraction of the gland (p = 0.005), total lesion uptake of the prostate (p = 0.02), and age (p = 0.01) were significantly associated with disease-specific survival, whereas SUVmax (p = 0.2), PSA (p = 0.2), and Gleason score (p = 0.8) were not. Conclusion AI-based assessments of total tumour volume and lesion uptake were significantly associated with disease-specific survival in this patient cohort, whereas SUVmax and Gleason scores were not. The AI-based approach appears well-suited for clinically relevant patient stratification and monitoring of individual therapy.

1124 Objectives: To evaluate the performance of a novel clinical multi-pinhole (MPH) brain SPECT system based on a hypothesis of superior image quality compared to traditional parallel hole low energy high resolution (LEHR) collimators. Methods: We conducted the study using a triple-head SPECT scanner from Mediso Medical Imaging Systems equipped with novel MPH collimators designed for high resolution and high sensitivity brain imaging. Each collimator plate made of 18 mm tungsten had 30 pinhole apertures creating overlapping and non-overlapping projections. We first measured spatial sensitivity using a Tc-99m point source. By moving the point source within the entire scanner field of view one position at a time, we established a complete sensitivity curve in both axial- and transaxial- direction. Second, using a mini Derenzo phantom with rod diameters of 2 to 7 mm, we assessed the spatial resolution visually. Third, we evaluated the quality of scatter correction with an I-123 line source placed in a 15 cm diameter water cylinder. From the reconstructed images, we calculated the scatter fraction as the fraction of counts within the water volume divided by counts within the central part containing the line source. All measurements were repeated on a dual-head Siemens Symbia SPECT scanner mounted with parallel hole LEHR collimators for comparison. Finally, a patient suspected of having Parkinson’s disease underwent a DaTSCAN. A 15 min SPECT-CT MPH acquisition was performed 2.5 h after injection of 150 MBq I-123-FP-CIT, followed immediately by a 32 min LEHR dual-headed SPECT-CT acquisition 3 h p.i. All MPH acquisitions used a 20% energy window on the Tc-99m or I-123 primary energy peak, respectively. Reconstruction of the MPH scans was performed with both attenuation and scatter correction using a Monte Carlo-based algorithm simulating both aperture and scatter medium. Dual-headed LEHR acquisitions collected data from a 15% energy window; reconstructions applied attenuation correction, scatter correction and resolution recovery. Scatter correction of the LEHR acquisitions was based on window subtraction of adjacent windows; for Tc-99m we applied a dual energy window procedure and for I-123 a triple window procedure. Results: Peak spatial sensitivity of the MPH system was 700 cps/MBq compared to 180 cps/MBq for the dual-headed LEHR. The MPH spatial resolution images revealed visible rods with 5 mm diameter whereas the on LEHR images rods of 7 mm were only partially visible. The scatter fraction from the MPH acquisition was 0.3% compared to 33.2% from the LEHR acquisition. The MPH patient scan visually revealed a higher image quality in terms of better delineation of the striatum and higher image contrast between cerebral cortical regions and the brain ventricles compared to LEHR scan. Conclusions: The image quality in terms of sensitivity, resolution and scatter fraction was evaluated. In the central field of view, the MPH sensitivity was 3.9 times higher than conventional LEHR imaging. Spatial resolution was significantly improved. Elimination of scatter from the higher energy peaks of I-123 yields images of high quantitative value. Patient scan suggested that the dedicated MPH system visually improves image quality with reduced imaging duration. The novel MPH system has great potential to improve image quality of brain SPECT examinations.

The issue of whether 99mTc-DTPA can replace 51Cr-EDTA for measurement of plasma clearance as a surrogate for glomerular filtration rate (GFR) is of great relevance to daily clinical practice. Prompted by the shortage of 51Cr-EDTA we conducted a head-to-head comparison in patients attending our department for GFR determination. The two tracers (3.7 MBq of 51Cr-EDTA and 8 MBq of 99mTc-DTPA) were administered intravenously immediately after each other, and the standard number of blood samples were drawn. Fifty-four patients were enrolled. In 51 of these, single-sample measurement was performed with the following results: GFREDTA was 84.6 ± 23.3 mL/min, GFRDTPA was 84.2 ± 24.7 mL/min. The mean difference was 0.4 ± 2.8 mL/min, p = 0.32, and results based on the two tracers were highly correlated (r = 0.995). GFRDTPA exceeded GFREDTA at high GFR values (difference < 0 at GFREDTA >91.4 mL/min) and vice versa (difference > 0 at GFREDTA < 91.4 mL/min). However, differences fell within few GFR units that most often will have no clinical consequence. We therefore conclude that 99mTc-DTPA can replace 51Cr-EDTA for single-sample determination of GFR in a clinical setting.

Citation for pulished version (APA): Polymeri, E., Sadik, M., Kaboteh, R., Borrelli, P., Enqvist, O., Ulén, J., Ohlsson, M., Trägårdh, E., Poulsen, M. H., Simonsen, J. A., Hoilund-Carlsen, P. F., Johnsson, Å. A., & Edenbrandt, L. (2020). Deep learning-based quantification of PET/CT prostate gland uptake: association with overall survival. Clinical Physiology and Functional Imaging, 40(2), 106-113. https://doi.org/10.1111/cpf.12611

To validate a deep‐learning (DL) algorithm for automated quantification of prostate cancer on positron emission tomography/computed tomography (PET/CT) and explore the potential of PET/CT measurements as prognostic biomarkers.

BACKGROUND:Breast cancer-related lymphedema (BCRL) is a feared late complication. Treatment options are lacking at present. Recent studies have suggested that mesenchymal stromal cells can alleviate lymphedema. Herein, we report the results from the first human pilot study with adipose-derived regenerative cells (ADRCs) for treating BCRL with 1 year of follow-up.MATERIAL AND METHODS:We included 10 patients with BCRL. ADRCs were injected directly into the axillary region together with a scar-releasing fat grafting procedure. Primary endpoint was change in arm volume. Secondary endpoints were change in patient-reported outcomes, changes in lymph flow, and safety.RESULTS:During follow-up, no significant change in volume was noted. Patient-reported outcomes improved significantly with time. Five patients reduced their use of conservative management. Quantitative lymphoscintigraphy did not improve on the lymphedema-affected arms. ADRCs were well tolerated, and only minor transient adverse events related to liposuction were noted.CONCLUSIONS:In this pilot study, a single injection of ADRCs improved lymphedema based on patient-reported outcome measures, and there were no serious adverse events during the follow-up period. Lymphoscintigraphic evaluation showed no improvement after ADRC treatment. There was no change in excess arm volume. Results of this trial need to be confirmed in randomized clinical trials.

Poster: EANM 19 / TEPS-72 / Glomerular filtration rate: Comparison of two tracers by: Janus, T. L. Andersen, K. Thilsing-Hansen, D. Roholdt, C. H. Led, P. T. Andersen, H. Thomsen, O. Gerke, P. F. Hoilund-Carlsen, J. A. Simonsen; Odense University Hospital, Odense C, DENMARK

PURPOSE:The aim of this study was to develop a deep learning-based method for segmentation of bones in CT scans and test its accuracy compared to manual delineation, as a first step in the creation of an automated PET/CT-based method for quantifying skeletal tumour burden. METHODS:Convolutional neural networks (CNNs) were trained to segment 49 bones using manual segmentations from 100 CT scans. After training, the CNN-based segmentation method was tested on 46 patients with prostate cancer, who had undergone 18F-choline-PET/CT and 18F-NaF PET/CT less than three weeks apart. Bone volumes were calculated from the segmentations. The network's performance was compared with manual segmentations of five bones made by an experienced physician. Accuracy of the spatial overlap between automated CNN-based and manual segmentations of these five bones was assessed using the Sørensen-Dice index (SDI). Reproducibility was evaluated applying the Bland-Altman method. RESULTS:The median (SD) volumes of the five selected bones were by CNN and manual segmentation: Th7 41 (3.8) and 36 (5.1), L3 76 (13) and 75 (9.2), sacrum 284 (40) and 283 (26), 7th rib 33 (3.9) and 31 (4.8), sternum 80 (11) and 72 (9.2), respectively. Median SDIs were 0.86 (Th7), 0.85 (L3), 0.88 (sacrum), 0.84 (7th rib) and 0.83 (sternum). The intraobserver volume difference was less with CNN-based than manual approach: Th7 2% and 14%, L3 7% and 8%, sacrum 1% and 3%, 7th rib 1% and 6%, sternum 3% and 5%, respectively. The average volume difference measured as ratio volume difference/mean volume between the two CNN-based segmentations was 5-6% for the vertebral column and ribs and ≤3% for other bones. CONCLUSION:The new deep learning-based method for automated segmentation of bones in CT scans provided highly accurate bone volumes in a fast and automated way and, thus, appears to be a valuable first step in the development of a clinical useful processing procedure providing reliable skeletal segmentation as a key part of quantification of skeletal metastases.

BACKGROUND:Lymphoscintigraphy is commonly used to assess breast cancer-related lymphedema. However, a reliable quantitative method that clearly distinguishes normal lymphatic function from lymphedema is desired. We propose a quantitative method based upon the physiological mean transit time (MTT) measure of lymph fluid passing through the arm.METHODS AND RESULTS:Eleven patients, aged 34-68 years, with unilateral arm lymphedema following breast cancer treatment underwent simultaneous bilateral lymphoscintigraphy using intradermal injection of 99mTc-labeled human serum albumin (HSA). Imaging was performed at 30-45 minute intervals for 5 hours. Time activity curves from each injection site and each arm region were recorded. The input into the arm region was obtained as the (minus) time derivative of the injection site activity curve. In the proposed model the arm activity curve was considered to arise from the convolution of the retention function and the input function. The retention function was obtained by fitting the calculated arm activity curve to the measured arm activity curve. The MTT of activity passing through the arm was calculated as the time integral of the resulting retention function. All measured time activity curves were well described by the model. The MTT of the lymphedema arm (mean 60.1 minutes, range 22-105 minutes) was markedly different from that of the contralateral normal arm (mean 5.4 minutes, range 1.2-8.7 minutes), p < 0.0001.CONCLUSION:The proposed model showed great similarity with measured time activity curves and was capable of quantitatively distinguishing lymphatic function of the lymphedema arm from that of the normal arm in terms of calculated MTT.

• You may download this work for personal use only. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying this open access version If you believe that this document breaches copyright please contact us providing details and we will investigate your claim. Please direct all enquiries to puresupport@bib.sdu.dk

OBJECTIVES:In stable coronary artery disease (CAD), coronary revascularisation may reduce mortality of patients with a certain amount of left ventricular myocardial ischaemia. However, revascularisation does not always follow the guidance suggested by ischaemia testing. We compared outcomes in patients without ischaemia who had either revascularisation or medical treatment.DESIGN AND POPULATION:Based on registries, 1327 consecutive patients with normal myocardial perfusion scintigraphy (MPS) and 278 with fixed perfusion defects were followed for a median of 6.1 years. Most patients received medical therapy alone (Med), but 26 (2%) with a normal MPS and 15 (5%) with fixed perfusion defects underwent revascularisation (Revasc).OUTCOME MEASURES:Incidence rates of all-cause death (ACD) and rates of cardiac death/myocardial infarction (CD/MI).RESULTS:With a normal MPS, the ACD rate was 6.2%/year in the Revasc group versus 1.9%/year in the Med group (p=0.01); the CD/MI rates were 6.9%/year and 0.6%/year, respectively (p<0.00001). Results persisted after adjustment for predictors of revascularisation, in particular angina score, and in comparisons of matched Revasc and Med patients. With fixed defects, the ACD rate was 9.1%/year in the Revasc group and 6.7%/year in the Med group (p=0.44); the CD/MI rate was 5.0%/year versus 4.2%/year, respectively (p=0.69). If adjusted for angiographic variables or analysed in matched subsets, differences remained insignificant.CONCLUSIONS:With normal MPS, revascularisation conferred a higher risk, even after adjustment for predictors of revascularisation. With fixed defects, the Revascversus Med difference was close to equipoise. Hence, in patients with stable CAD without ischaemia, we could not find evidence to justify exceptional revascularisation.