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Background: Our study aims to explore the current utilisation of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) in the diagnostic pathway of pyrexia of unknown origin (PUO) and associated cost of illness in a large tertiary teaching hospital in Australia., Method: 1257 febrile patients between June 2016 and September 2022 were retrospectively reviewed. There were 57 patients who met the inclusion criteria of "classical PUO", of which FDG-PET/CT was performed in 31 inpatients, 15 outpatients and 11 inpatients did not have an FDG-PET/CT scan. The patient demographics, clinical characteristics and inpatient cost were analysed, together with the diagnostic performance of FDG-PET/CT and impact on clinical management., Result: The mean age, length of stay and total cost of admission were higher for inpatients who received FDG-PET/CT versus those who did not. The median cost per patient-bed-day did not differ between the two groups. Inpatients who received earlier FDG-PET/CTs (≤ 7 days from admission) had shorter length of stays and lower total cost compared to those who received a later scan. A negative FDG-PET/CT scan, demonstrating no serious or life-threatening abnormalities resulted in subsequent discharge from hospital or outpatient clinic in 7/10 (70%) patients. There were 11/40 (28%) scans where ancillary abnormalities were identified, requiring further evaluation., Conclusion: FDG-PET/CT showed high diagnostic accuracy and significant impact on patient management in patients with PUO. FDG-PET/CT performed earlier in admission for PUO was associated with shorter length of stay and lower total cost., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The impact of modern imaging in uncovering the underlying pathology of PMR cannot be understated. Long dismissed as an inflammatory syndrome with links to the large vessel vasculitis giant cell arteritis (GCA), a pathognomonic pattern of musculotendinous inflammation is now attributed to PMR and may be used to confirm its diagnosis. Among the available modalities, 18 F-fluorodeoxyglucose ( 18 F-FDG) PET/CT is increasingly recognized for its high sensitivity and specificity, as well as added ability to detect concomitant large vessel GCA and exclude other relevant differentials like infection and malignancy. This atlas provides a contemporary depiction of PMR's pathology and outlines how this knowledge translates into a pattern of findings on whole body 18 F-FDG PET/CT that can reliably confirm its diagnosis., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Imaging is increasingly being used to guide clinical decision-making in patients with giant cell arteritis (GCA). While ultrasound has been rapidly adopted in fast-track clinics worldwide as an alternative to temporal artery biopsy for the diagnosis of cranial disease, whole-body PET/CT is emerging as a potential gold standard test for establishing large vessel involvement. However, many unanswered questions remain about the optimal approach to imaging in GCA. For example, it is uncertain how best to monitor disease activity, given there is frequent discordance between imaging findings and conventional disease activity measures, and imaging changes typically fail to resolve completely with treatment. This chapter addresses the current body of evidence for the use of imaging modalities in GCA across the spectrum of diagnosis, monitoring disease activity, and long-term surveillance for structural changes of aortic dilatation and aneurysm formation and provides suggestions for future research directions., Competing Interests: Declaration of competing interest Author CEO declares advisory board for AbbVie; speaking honoraria from AbbVie, Novartis, and Janssen and Roche; co-investigator on STERLING-PMR trial, funded by NIHR-NHMRC; investigator on AbbVie and Novartis clinical trials. Author MY declares advisory board for BioGen; co-investigator on STERLING-PMR trial, funded by NIHR-NHMRC; financial support from AbbVie, and UCB to attend international conferences, including the BSR and EULAR. Author DFL co-investigator on STERLING-PMR trial, funded by NIHR-NHMRC. Author AMP declares no conflict of interest. Author HIK declares speaking honoraria from AbbVie, and Roche and Jansen; co-investigator on STERLING-PMR trial, funded by NIHR-NHMRC; investigator on AbbVie, Sanofi, and Novartis clinical trials; educational support from Pfizer. Author CLH declares co-investigator on STERLING-PMR trial, funded by NIHR-NHMRC; grant support from Vifor. Author SLM declares consultancy on behalf of her institution for Roche/Chugai, Sanofi, AbbVie and AstraZeneca; investigator on clinical trials for Sanofi, GSK, and Sparrow; speaking/lecturing on behalf of her institution for Roche/Chugai, Vifor, Pfizer, UCB, and Novartis; chief investigator on STERLING-PMR trial, funded by NIHR-NHMRC; patron of the charity PMRGCAuk. No personal remuneration was received for any of the above activities. Support from Roche/Chugai to attend EULAR2019 in person and from Pfizer to attend ACR Convergence 2021 virtually. SLM is supported in part by the NIHR Leeds Biomedical Research Centre. The views expressed in this article are those of the authors and not necessarily those of the NIHR, the NIHR Leeds Biomedical Research Centre, the National Health Service, or the UK Department of Health and Social Care., (Crown Copyright © 2023. Published by Elsevier Ltd. All rights reserved.)

Background: Clinical diagnosis of Alzheimer disease (AD) is only 70% accurate. Reduced cerebral blood flow (CBF) and metabolism in parieto-temporal and posterior cingulate cortex may assist diagnosis. While widely accepted that 18 F-fluoro-2-deoxyglucose positron emission tomography ( 18 F-FDG PET) has superior accuracy to CBF-SPECT for AD, there are very limited head-to-head data from clinically relevant populations and these studies relied on clinical diagnosis as the reference standard., Aims: To compare directly the accuracy of CBF-SPECT and 18 F-FDG PET in patients referred for diagnostic studies in detecting β-amyloid PET confirmed AD., Methods: A total of 126 patients, 56% with mild cognitive impairment and 44% with dementia, completed both CBF-SPECT and 18 F-FDG PET as part of their diagnostic assessment, and subsequently underwent β-amyloid PET for research purposes. Transaxial slices and Neurostat 3D-SSP analyses of 18 F-FDG PET and CBF-SPECT scans were independently reviewed by five nuclear medicine clinicians blinded to all other data. Operators selected the most likely diagnosis and their diagnostic confidence. Accuracy analysis used final diagnosis incorporating β-amyloid PET as the reference standard., Results: Clinicians reported high diagnostic confidence in 83% of 18 F-FDG PET compared to 67% for CBF-SPECT (P = 0.001). All reviewers showed individually higher accuracy using 18 F-FDG PET. Based on majority read, the combined area under the receiver operating characteristic curve in diagnosing AD was 0.71 for 18 F-FDG PET and 0.61 for CBF-SPECT (P = 0.02). The sensitivity of 18 F-FDG PET and CBF-SPECT was 76% versus 43% (P < 0.001), while specificity was 74% versus 83% (P = 0.45)., Conclusions: 18 F-FDG PET is superior to CBF-SPECT in detecting AD among patients referred for the assessment of cognitive impairment., (© 2020 The Authors. Internal Medicine Journal by Wiley Publishing Asia Pty Ltd on behalf of Royal Australasian College of Physicians.)

Purpose: To evaluate the sensitivity and specificity of PET/CT findings in PMR and generate a diagnostic algorithm utilizing a minimum number of musculoskeletal sites., Methods: Steroid-naïve patients with newly diagnosed PMR (2012 EULAR/ACR classification criteria) were prospectively recruited to undergo whole-body 18 F - FDG PET/CT. Each PMR case was age- and sex-matched to four PET/CT controls. Control scan indication, diagnosis and medical history were extracted from the clinical record. Qualitative and semi-quantitative scoring (maximum standardized uptake value [SUV max ]) of abnormal 18 F-FDG uptake at 21 musculoskeletal sites was undertaken for cases and controls. Results informed the development of a novel PET/CT diagnostic algorithm using a classification and regression trees (CART) method., Results: Thirty-three cases met the inclusion criteria and were matched to 132 controls. Mean age was 68.6 ± 7.4 years for cases compared with 68.2 ± 7.3 for controls, and 54.5% were male. Median CRP was 49 mg/L (32-65) and ESR 41.5 mm/h (24.6-64.4) in the PMR group. The predominant control indication for PET/CT was malignancy (63.6%). Individual musculoskeletal sites proved insufficient for diagnostic purposes. A novel algorithm comprising 18 F-FDG uptake ≥ 2 adjacent to the ischial tuberosities in combination with either abnormalities at the peri-articular shoulder or interspinous bursa achieved a sensitivity of 90.9% and specificity of 92.4% for diagnosing PMR., Conclusions: The presence of abnormal 18 F-FDG uptake adjacent to the ischial tuberosities together with findings at the peri-articular shoulder or interspinous bursa on whole-body PET/CT is highly sensitive and specific for a diagnosis of PMR., Trial Registration: Clinical Trial Registration: Australian New Zealand Clinical Trials Registry, http://www.anzctr.org.au , ACTRN1261400696695.

Objectives: To characterize 18F-fluorodeoxyglucose (18F-FDG) uptake on whole-body PET/CT in PMR, and identify its precise anatomic correlate using MRI., Methods: Patients with newly diagnosed PMR according to the 2012 EULAR/ACR classification criteria were prospectively recruited. Participants with GCA were excluded. A whole-body 18F-FDG PET/CT scan was performed in all untreated patients. Qualitative and semiquantitative [standardized uptake value maximum (SUVmax)] scoring of abnormal 18F-FDG uptake was undertaken. MRI of the pelvis, knee and wrist and hand was performed in three representative patients with anatomical correlation of FDG-avid sites carried out using Medview fusion software., Results: Twenty-two patients with PMR were recruited. Their mean age was 68.3 years (s.d. 6.3) and 13/22 were male. On whole-body PET/CT, 18F-FDG uptake adjacent to the ischial tuberosities was observed in 21 participants (95.4%) and recorded the highest mean SUVmax value [3.6 (s.d. 1.7)]. A high frequency of posteromedial knee (61.9%) and wrist and/or hand involvement (66.7%) was also appreciated. MRI of the pelvis revealed high T2 signal surrounding the proximal hamstring tendon origins of both semimembranosus and the conjoint tendon of the semitendinosus and biceps femoris. At the knee, peritendonitis at the distal insertion of the semimembranosus was observed. PET/MRI fusion at the pelvis and knee confirmed semimembranosus peritendonitis as the anatomical correlate of 18F-FDG uptake adjacent to the ischial tuberosities and of posteromedial knee structures., Conclusion: Hamstring peritendonitis is a common and distinctive manifestation of PMR on whole-body PET/CT., Trial Registration: Australian New Zealand Clinical Trials Registry, http://www.anzctr.org.au, ACTRN1261400696695., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com)