FDG-PET/CT for diagnosis of cyst infection in autosomal dominant polycystic kidney disease

Purpose: Cyst infections are a common complication in autosomal dominant polycystic kidney disease (ADPKD). Diagnosing these infections often remains challenging. Conventional imaging techniques such as ultrasonography, computed tomography (CT), and standard magnetic resonance imaging have several drawbacks and disadvantages. The purpose of this pictorial essay was to illustrate and discuss the potential value of18F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET)/CT in diagnosing cyst infection in ADPKD. Methods: Exemplary (ADPKD) patients who underwent FDG-PET/CT as part of their routine clinical work-up in our institution are presented to show the potential value and drawbacks of this imaging technique in diagnosing cyst infection. In addition, the current literature and guidelines on this topic were reviewed. Results: FDG-PET/CT appears to be a sensitive method for the detection of cyst infection, but it is not infallible. Furthermore, FDG uptake in cysts and cyst-like lesions is not specific and clinical and radiological correlations are essential to improve specificity and minimize the risk of falsely discarding other diseases, in particular malignancy. Conclusion: FDG-PET/CT seems to be a useful imaging modality to diagnose cyst infections in ADPKD. However, its exact diagnostic value has not been established yet due to the lack of a reliable reference standard in previous studies on this topic

F-18-FDG PET/CT in Infective Endocarditis:Indications and Approaches for Standardization

Purpose of Review: Additional imaging modalities, such as FDG-PET/CT, have been included into the workup for patients with suspected infective endocarditis, according to major international guidelines published in 2015. The purpose of this review is to give an overview of FDG-PET/CT indications and standardized approaches in the setting of suspected infective endocarditis. Recent Findings: There are two main indications for performing FDG-PET/CT in patients with suspected infective endocarditis: (i) detecting intracardiac infections and (ii) detection of (clinically silent) disseminated infectious disease. The diagnostic performance of FDG-PET/CT for intracardiac lesions depends on the presence of na

Diagnostic accuracy of dynamic CZT-SPECT in coronary artery disease. A systematic review and meta-analysis

Background: With the appearance of cadmium-zinc-telluride (CZT) cameras, dynamic myocardial perfusion imaging (MPI) has been introduced, but comparable data to other MPI modalities, such as quantitative coronary angiography (CAG) with fractional flow reserve (FFR) and positron emission tomography (PET), are lacking. This study aimed to evaluate the diagnostic accuracy of dynamic CZT single-photon emission tomography (SPECT) in coronary artery disease compared to quantitative CAG, FFR, and PET as reference. Materials and Methods: Different databases were screened for eligible citations performing dynamic CZT-SPECT against CAG, FFR, or PET. PubMed, OvidSP (Medline), Web of Science, the Cochrane Library, and EMBASE were searched on the 5th of July 2020. Studies had to meet the following pre-established inclusion criteria: randomized controlled trials, retrospective trails or observational studies relevant for the diagnosis of coronary artery disease, and performing CZT-SPECT and within half a year the methodological references. Studies which considered coronary stenosis between 50% and 70% as significant based only on CAG were excluded. Data extracted were sensitivity, specificity, likelihood ratios, and diagnostic odds ratios. Quality was assessed with QUADAS-2 and statistical analysis was performed using a bivariate model. Results: Based on our criteria, a total of 9 studies containing 421 patients were included. For the assessment of CZT-SPECT, the diagnostic value pooled analysis with a bivariate model was calculated and yielded a sensitivity of 0.79 (% CI 0.73 to 0.85) and a specificity of 0.85 (95% CI 0.74 to 0.92). Diagnostic odds ratio (DOR) was 17.82 (95% CI 8.80 to 36.08, P < 0.001). Positive likelihood ratio (PLR) and negative likelihood ratio (NLR) were 3.86 (95% CI 2.76 to 5.38, P < 0.001) and 0.21 (95% CI 0.13 to 0.33, P < 0.001), respectively. Conclusion: Based on the results of the current systematic review and meta-analysis, dynamic CZT-SPECT MPI demonstrated a good sensitivity and specificity to diagnose CAD as compared to the gold standards. However, due to the heterogeneity of the methodologies between the CZT-SPECT MPI studies and the relatively small number of included studies, it warrants further well-defined study protocols

Improved [¹⁸F]FDG PET/CT Diagnostic Accuracy for Infective Endocarditis Using Conventional Cardiac Gating or Combined Cardiac and Respiratory Motion Correction (CardioFreeze^TM)

Infective endocarditis (IE) is a serious and diagnostically challenging condition. [18F]FDG PET/CT is valuable for evaluating suspected IE, but it is susceptible to motion-related artefacts. This study investigated the potential benefits of cardiac motion correction for [18F]FDG PET/CT. In this prospective study, patients underwent [18F]FDG PET/CT for suspected IE, combined with a conventional cardiac gating sequence, a data-driven cardiac and respiratory gating sequence (CardioFreezeTM), or both. Scans were performed in adherence to EANM guidelines and assessors were blinded to patients’ clinical contexts. Final diagnosis of IE was established based on multidisciplinary consensus after a minimum of 4 months follow-up and surgical findings, whenever performed. Seven patients participated in the study, undergoing both an ungated [18F] FDG-PET/CT and a scan with either conventional cardiac gating, CardioFreezeTM, or both. Cardiac motion correction improved the interpretability of [18F]FDG PET/CT in four out of five patients with valvular IE lesions, regardless of the method of motion correction used, which was statistically significant by Wilcoxon’s signed rank test: p = 0.046. In one patient the motion-corrected sequence confirmed the diagnosis of endocarditis, which had been missed on non-gated PET. The performance of the two gating sequences was comparable. In conclusion, in this exploratory study, cardiac motion correction of [18F]FDG PET/CT improved the interpretability of [18F]FDG PET/CT. This may improve the sensitivity of PET/CT for suspected IE. Further larger comparative studies are necessary to confirm the additive value of these cardiac motion correction methods.</p

Perivascular adipose tissue-derived nitric oxide compensates endothelial dysfunction in aged pre-atherosclerotic apolipoprotein E-deficient rats

BACKGROUND AND AIMS: Atherosclerosis is a major contributor to global mortality and is accompanied by vascular inflammation and endothelial dysfunction. Perivascular adipose tissue (PVAT) is an established regulator of vascular function with emerging implications in atherosclerosis. We investigated the modulation of aortic relaxation by PVAT in aged rats with apolipoprotein E deficiency (ApoE-/-) fed a high-fat diet as a model of early atherosclerosis. METHODS AND RESULTS: ApoE-/- rats (N = 7) and wild-type Sprague-Dawley controls (ApoE+/+, N = 8) received high-fat diet for 51 weeks. Hyperlipidemia was confirmed in ApoE-/- rats by elevated plasma cholesterol (p < 0.001) and triglyceride (p = 0.025) levels. Early atherosclerosis was supported by increased intima/media thickness ratio (p < 0.01) and ED1-positive macrophage influx in ApoE-/- aortic intima (p < 0.001). Inflammation in ApoE-/- PVAT was characteristic by an increased [18F]FDG uptake (p < 0.01), ED1-positive macrophage influx (p = 0.0003), mRNA expression levels of CD68 (p < 0.001) and IL-1β (p < 0.01), and upregulated iNOS protein (p = 0.011). The mRNAs of MCP-1, IL-6 and adiponectin remained unchanged in PVAT. Aortic PVAT volume measured with micro-PET/CT was increased in ApoE-/- rats (p < 0.01). Maximal endothelium-dependent relaxation (EDR) to acetylcholine in ApoE-/- aortic rings without PVAT was severely impaired (p = 0.012) compared with controls, while ApoE-/- aortic rings with PVAT showed higher EDR than controls. All EDR responses were blocked by L-NMMA and the expression of eNOS mRNA was increased in ApoE-/- PVAT (p = 0.035). CONCLUSION: Using a rat ApoE-/- model of early atherosclerosis, we capture a novel mechanism by which inflammatory PVAT compensates severe endothelial dysfunction by contributing NO upon cholinergic stimulation

Long-term prognostic value of quantitative myocardial perfusion in patients with chest pain and normal coronary arteries

BACKGROUND: Patients with chest pain and no obstructive coronary artery disease have shown a high incidence of major adverse cardiovascular events (MACE). We evaluated the role of absolute myocardial perfusion quantification in predicting all-cause mortality and MACE during long-term follow-up in this group of patients. METHODS: We studied 79 patients who underwent Nitrogen-13 ammonia PET for quantification of global myocardial blood flow (MBF) and myocardial flow reserve (MFR) due to suspected impaired myocardial perfusion. Patients with coronary artery disease (i.e., > 30% stenosis in one or more coronary arteries) were excluded. We assessed all-cause mortality and MACE. MACE was defined as the composite incidence of death, myocardial infarction (MI), or hospitalization due to heart failure. RESULTS: Median follow-up was 8 (IQR: 3-14) years. Univariate Cox regression showed that only MFR (P = 0.01) was a predictor of all-cause mortality. Univariate Cox regression analysis showed that both MFR and Stress MBF were predictors of the composite endpoint of MACE (P < 0.001 and P = 0.01, respectively). CONCLUSION: Quantitative assessment of myocardial perfusion may predict all-cause mortality and MACE in patients with chest pain and normal coronary arteries in the long-term follow-up

Patient-Tailored Approach for Diagnostics and Treatment of Mycotic Abdominal Aortic Aneurysm

Background: The existing literature on mycotic aortic aneurysm is scarce and focuses on treatment. This study evaluates the clinical characteristics, diagnostics, treatment and outcome of patients with a mycotic abdominal aortic aneurysm treated in a tertiary referral center. Methods: A retrospective cohort study was conducted including all patients with a proven mycotic abdominal aortic aneurysm admitted between May 2010 and July 2020. Primary outcome was mortality and secondary outcome included complications such as vascular graft/endograft infection. Results: Twenty-four patients with a mycotic abdominal aortic aneurysm were included. Patients had a mean age of 68 +/- 9 years and 20 (83%) were male. Thirteen patients (57%) had positive preoperative blood cultures. Streptococcus pneumoniae was most frequently isolated by blood culturing, pus, and vascular, or perivascular tissue cultures (17%). In 19 (83%) patients the mycotic abdominal aortic aneurysm was located infrarenally, in three (13%) patients suprarenally, and in one (4%) patient juxtarenally. Median follow-up was 20 (7-42) months. In 8 patients (33%) vascular graft and or endograft infection was diagnosed after surgical repair. Ten (42%) patients died during the follow-up period. The main causes of death were vascular graft/endograft infection-related (n = 4) and rupture of the mycotic abdominal aortic aneurysm (n = 3). No patient characteristics could be identified as predictive for mortality. Conclusions: This study shows a large variation in presentation, diagnostic approaches, and surgical and antibiotic treatment of mycotic abdominal aortic aneurysm. The detailed information about the diagnostic approaches to this rare disease and its antibiotic and/or other treatment contributes to existing knowledge of mycotic abdominal aortic aneurysm. Because of the individual variation patients should be discussed in a multidisciplinary team with a vascular surgeon, infectious disease specialist, and clinical microbiologist

Repeatability of 18 F-FDG PET radiomic features:A phantom study to explore sensitivity to image reconstruction settings, noise, and delineation method

BACKGROUND: 18 F-fluoro-2-deoxy-D-Glucose positron emission tomography (18 F-FDG PET) radiomics has the potential to guide the clinical decision making in cancer patients, but validation is required before radiomics can be implemented in the clinical setting. The aim of this study was to explore how feature space reduction and repeatability of 18 F-FDG PET radiomic features are affected by various sources of variation such as underlying data (e.g., object size and uptake), image reconstruction methods and settings, noise, discretization method, and delineation method.METHODS: The NEMA image quality phantom was scanned with various sphere-to-background ratios (SBR), simulating different activity uptakes, including spheres with low uptake, that is, SBR smaller than 1. Furthermore, images of a phantom containing 3D printed inserts reflecting realistic heterogeneity uptake patterns were acquired. Data were reconstructed using various matrix sizes, reconstruction algorithms, and scan durations (noise). For every specific reconstruction and noise level, ten statistically equal replicates were generated. The phantom inserts were delineated using CT and PET-based segmentation methods. A total of 246 radiomic features was extracted from each image dataset. Images were discretized with a fixed number of 64 bins (FBN) and a fixed bin width (FBW) of 0.25 for the high and a FBW of 0.05 for the low uptake data. In terms of feature reduction, we determined the impact of these factors on the composition of feature clusters, which were defined on the basis of Spearman's correlation matrices. To assess feature repeatability, the intraclass correlation coefficient was calculated over the ten replicates.RESULTS: In general, larger spheres with high uptake resulted in better repeatability compared to smaller low uptake spheres. In terms of repeatability, features extracted from heterogeneous phantom inserts were comparable to features extracted from bigger high uptake spheres. For example, for an EARL-compliant reconstruction, larger and smaller high uptake spheres yielded good repeatability for 32% and 30% of the features, while the heterogeneous inserts resulted in 34% repeatable features. For the low uptake spheres, this was the case for 22% and 20% of the features for bigger and smaller spheres, respectively. Images reconstructed with point-spread-function (PSF) resulted in the highest repeatability when compared with OSEM or time-of-flight, for example, 53%, 30%, and 32% of repeatable features, respectively (for unsmoothed data, discretized with FBN, 300 s scan duration). Reducing image noise (increasing scan duration and smoothing) and using CT-based segmentation for the low uptake spheres yielded improved repeatability. FBW discretization resulted in higher repeatability than FBN discretization, for example, 89% and 35% of the features, respectively (for the EARL-compliant reconstruction and larger high uptake spheres).CONCLUSION: Feature space reduction and repeatability of 18 F-FDG PET radiomic features depended on all studied factors. The high sensitivity of PET radiomic features to image quality suggests that a high level of image acquisition and preprocessing standardization is required to be used as clinical imaging biomarker.</p

Diagnostic accuracy of myocardial perfusion imaging in patients evaluated for kidney transplantation:A systematic review and meta-analysis

BACKGROUND: Cardiovascular disease is the most common cause of death after kidney transplantation. Coronary artery disease (CAD) assessment is therefore mandatory in patients evaluated for transplantation. We aimed to assess the diagnostic accuracy for CAD of single-photon emission computed tomography (SPECT) compared to the standards invasive coronary angiography (ICA) and coronary computed tomography angiography (CCTA) in patients evaluated for kidney transplantation. METHODS: We performed a systematic literature search in PubMed, EMBASE, Web of Science, OvidSP (Medline), The Cochrane Library and Google Scholar. Studies investigating the diagnostic accuracy of myocardial perfusion imaging (MPI) SPECT in patients evaluated for kidney transplantation were retrieved. After a risk of bias assessment using QUADAS-2, a meta-analysis was conducted. RESULTS: Out of 1459 records, 13 MPI SPECT studies were included in the meta-analysis with a total of 1245 MPI SPECT scans. There were no studies available with CCTA as reference. Pooled sensitivity of MPI SPECT for CAD was 0.66 (95% CI 0.53 to 0.77), pooled specificity was 0.75 (95% CI 0.63 to 0.84) and the area under the curve (AUC) was 0.76. Positive likelihood ratio was 2.50 (95% CI 1.78 to 3.51) and negative likelihood ratio was 0.41 (95% CI 0.28 to 0.61). Pooled positive predictive value was 64.9% and pooled negative predictive value was 74.1%. Significant heterogeneity existed across the included studies. CONCLUSIONS: MPI SPECT had a moderate diagnostic accuracy in patients evaluated for kidney transplantation, with a high rate of false-negative findings. The use of an anatomical gold standard against a functional imaging test in the included studies is however suboptimal. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12350-021-02621-x

Targeted optical fluorescence imaging:a meta-narrative review and future perspectives

Purpose: The aim of this review is to give an overview of the current status of targeted optical fluorescence imaging in the field of oncology, cardiovascular, infectious and inflammatory diseases to further promote clinical translation. Methods: A meta-narrative approach was taken to systematically describe the relevant literature. Consecutively, each field was assigned a developmental stage regarding the clinical implementation of optical fluorescence imaging. Results: Optical fluorescence imaging is leaning towards clinical implementation in gastrointestinal and head and neck cancers, closely followed by pulmonary, neuro, breast and gynaecological oncology. In cardiovascular and infectious disease, optical imaging is in a less advanced/proof of concept stage. Conclusion: Targeted optical fluorescence imaging is rapidly evolving and expanding into the clinic, especially in the field of oncology. However, the imaging modality still has to overcome some major challenges before it can be part of the standard of care in the clinic, such as the provision of pivotal trial data. Intensive multidisciplinary (pre-)clinical joined forces are essential to overcome the delivery of such compelling phase III registration trial data and subsequent regulatory approval and reimbursement hurdles to advance clinical implementation of targeted optical fluorescence imaging as part of standard practice