[en] The aim of this study was to determine and validate a set of Hounsfield unit (HU) ranges to segment computed tomography (CT) images into tissue types and to test the validity of dual-energy X-ray absorptiometry (DXA) tissue segmentation on pure, unmixed porcine tissues. This preclinical prospective study was approved by the local ethical committee. Different quantities of porcine bone tissue (BT), lean tissue (LT) and adipose tissue (AT) were scanned using DXA and CT. Tissue type segmentation in DXA was performed via the standard clinical protocol and in CT through different sets of HU ranges. Percent coefficients of variation (%CV) were used to assess precision while % differences of observed masses were tested against zero using the Wilcoxon signed-rank Test. Total mass DXA measurements differ little but significantly (P=0.016) from true mass, while total mass CT measurements based on literature values show non-significant (P=0.69) differences of 1.7% and 2.0%. BT mass estimates with DXA differed more from true mass (median -78.2 to -75.8%) than other tissue types (median -11.3 to -8.1%). Tissue mass estimates with CT and literature HU ranges showed small differences from true mass for every tissue type (median -10.4 to 8.8%). The most suited method for automated tissue segmentation is CT and can become a valuable tool in quantitative nuclear medicine.

[en] With the routine use of 2-deoxy-2-["1"8F]-fluoro-D-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scans, metabolic activity of tumors can be quantitatively assessed through calculation of SUVs. One possible normalization parameter for the standardized uptake value (SUV) is lean body mass (LBM), which is generally calculated through predictive equations based on height and body weight. (Semi-)direct measurements of LBM could provide more accurate results in cancer populations than predictive equations based on healthy populations. In this context, four methods to determine LBM are reviewed: bioelectrical impedance analysis, dual-energy X-ray absorptiometry. CT, and magnetic resonance imaging. These methods were selected based on clinical accessibility and are compared in terms of methodology, precision and accuracy. By assessing each method’s specific advantages and limitations, a well-considered choice of method can hopefully lead to more accurate SUVLBM values, hence more accurate quantitative assessment of 18F-FDG PET images.

[en] The majority of individuals with cardiac amyloidosis have myocardial amyloid deposits formed from misfolded light chain (AL) or transthyretin (TTR) proteins. Diagnosis of amyloidosis and differentiation between the types is important for prognosis, therapy, and genetic counseling. Cardiac ATTR amyloidosis, the focus of this practice points document, is an under diagnosed cause of heart failure. Amyloid derived from wild-type TTR results in a restrictive cardiomyopathy, most commonly presenting in men in their early 70's onwards, but occasionally seen as young as age 60. Although almost 1 in 4 males > 80 years have some TTR-derived amyloid deposits at autopsy, the clinical significance of a mild degree of deposition is unknown - generally clinical manifestations of heart failure occur once enough amyloid has been deposited to cause LV wall thickening. Approximately 3-4% among US African Americans have a common inherited mutation of the TTR gene (Val122Ile), which produces a restrictive cardiomyopathy in a minority, but may contribute to heart failure in a higher proportion. Cardiac amyloidosis should be suspected in individuals with heart failure and thickened ventricles with grade 2 or greater diastolic dysfunction on echocardiography or typical findings on cardiac magnetic resonance imaging (CMR; diffuse late gadolinium enhancement, ECV expansion or characteristic T-1 relaxation times); diagnosis is confirmed by endomyocardial biopsy and typing of amyloid fibrils as needed. Several studies confirm the high sensitivity and specificity of ^99mTc-bone compound scintigraphy [^99mTc-3,3-diphosphono-1,2- propanedicarboxylic acid (DPD) or PYP for cardiac ATTR amyloidosis; recent studies highlight the value of DPD and/or PYP in differentiating cardiac ATTR from AL amyloidosis. A distinct advantage of ^99mTc-PYP imaging, even when echocardiography and CMR are diagnostic for cardiac amyloidosis, is its ability to specifically identify ATTR cardiac amyloidosis non-invasively and thereby guide patient management. The purpose of this document is to identify the critical components involved in performing ^99mTechnetium-pyrophosphate (^99mTc-PYP) imaging for the evaluation of cardiac transthyretin amyloidosis (ATTR)

[en] Regional contribution to left ventricular (LV) ejection is of much clinical importance but its assessment is notably challenging. While deformation imaging is often used, this does not take into account loading conditions. Recently, a method for intraventricular pressure estimation was proposed, thus allowing for loading conditions to be taken into account in a non-invasive way. In this work, a method for 3D automatic myocardial performance mapping in echocardiography is proposed by performing 3D myocardial segmentation and tracking, thus giving access to local geometry and strain. This is then used to assess local LV stress–strain relationships which can be seen as a measure of local myocardial work. The proposed method was validated against ¹⁸F-fluorodeoxyglucose positron emission tomography, the reference method to clinically assess local metabolism. Averaged over all patients, the mean correlation between FDG-PET and the proposed method was . In conclusion, stress–strain loops were, for the first time, estimated from 3D echocardiography and correlated to the clinical gold standard for local metabolism, showing the future potential of real-time 3D echocardiography (RT3DE) for the assessment of local metabolic activity of the heart. (paper)

[en] In the acute setting of endocarditis it is very important to assess both the vegetation itself, as well as potential life-threatening complications, in order to decide whether antibiotic therapy will be sufficient or urgent surgery is indicated. A single whole-body scan investigating inflammatory changes could be very helpful to achieve a swift and efficient assessment. In this study we assessed whether ¹⁸F-FDG can be used to detect and localize peripheral embolism or distant infection. Twenty-four patients with 25 episodes of endocarditis, enrolled between March 2006 and February 2008, underwent ¹⁸F-FDG PET/CT imaging on a dedicated PET/CT scanner. PET/CT imaging revealed a focus of peripheral embolization and/or metastatic infection in 11 episodes (44%). One episode had a positive PET/CT scan result for both embolism and metastatic infection. PET/CT detected seven positive cases (28%) in which there was no clinical suspicion. Valve involvement of endocarditis was seen only in three patients (12%). PET/CT may be an important diagnostic tool for tracing peripheral embolism and metastatic infection in the acute setting of infective endocarditis, since a PET/CT scan detected a clinically occult focus in nearly one third of episodes. (orig.)

[en] FDG-PET/CT is part of the standard diagnostic management of a patients with a large variety of common and less common malignant tumors, based on the increased glucose metabolism within tumors. A hybrid fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) was performed in a neurofibromatosis patient to rule out relapse of malignant peripheral nerve sheet tumor. The scan revealed non-malignant neurofibromas, a testis seminoma and hypermetabolic syphilitic granulomata. This case stresses the need to rule out infectious diseases when atypical hypermetabolic lesions are present

No abstract available

[en] As prognosis in sarcoidosis is determined by cardiac involvement, the objective was to study the added value of cardiovascular magnetic resonance (CMR) in risk stratification. In 114 patients (48 ± 12 years/52% male) with biopsy-proven sarcoidosis, we studied the value of clinical and CMR-derived parameters to predict future events, using sustained ventricular tachycardia, ventricular fibrillation, aborted cardiac death, implantable cardioverter-defibrillator (ICD) placement with appropriate shocks, hospitalization for heart failure, and death as composite endpoint. Median follow-up after CMR was 3.1 years (1.1–5.7 years). The ejection fraction (EF) was 58.2 ± 9.1% and 54.7 ± 10.8% for left ventricle (LV) and right ventricle (RV), respectively. LV late gadolinium enhancement (LGE) was present in 40 patients (35%) involving 5.1% of the LV mass (IQR, 3.0–12.0%), with concomitant RV involvement in 12 patients (11%). T2-weighting imaging and/or T2 mapping showed active disease in 14 patients. The composite endpoint was reached in 34 patients, with 7 deaths in the LGE-positive group (17.5%), versus two deaths in the LGE-negative group (2.7%) (p = 0.015). At univariate analysis, RVEF (p = 0.009), pulmonary arterial pressure (p = 0.002), and presence of LGE (p < 0.001) and LGE (% of LV) (p < 0.001) were significant. At multivariate analysis, only presence of LGE and LGE (% of LV) was significant (both p = 0.03). At Kaplan-Meier, presence of LGE and an LGE of 3% predicted event-free survival and patient survival. We found no difference in active versus inactive disease with regard to patient survival. Myocardial enhancement at LGE-CMR adds independent prognostic value in risk stratification sarcoidosis patients. In contrast, clinical as well as functional cardiac parameters lack discriminative power.

[en] With this document, we provide a standard for PET/(diagnostic) CT imaging procedures in cardiovascular diseases that are inflammatory, infective, infiltrative, or associated with dysfunctional innervation (4Is). This standard should be applied in clinical practice and integrated in clinical (multicenter) trials for optimal procedural standardization. A major focus is put on procedures using [${}^{18}$F]FDG, but 4Is PET radiopharmaceuticals beyond [${}^{18}$F]FDG are also described in this document. Whilst these novel tracers are currently mainly applied in early clinical trials, some multicenter trials are underway and we foresee in the near future their use in clinical care and inclusion in the clinical guidelines. Finally, PET/MR applications in 4Is cardiovascular diseases are also briefly described. Diagnosis and management of 4Is-related cardiovascular diseases are generally complex and often require a multidisciplinary approach by a team of experts. The new standards described herein should be applied when using PET/CT and PET/MR, within a multimodality imaging framework both in clinical practice and in clinical trials for 4Is cardiovascular indications.

[en] Sarcoidosis is a multisystem chronic inflammatory disease of unknown etiology characterized by widespread growth of non-caseating granulomas. The diagnosis of sarcoidosis is based on clinical and imaging presentation, histologic confirmation and the absence of alternative diseases. Radiology and Nuclear Medicine play an essential role in the diagnostic work-up of patients with sarcoidosis to assess disease extent and activity. In addition, imaging modalities have shown their potential in managing these patients in terms of treatment response and prognostic assessment. Sarcoidosis has a predilection for chest involvement, showing typical and atypical manifestations in the lungs, airways and hilar/mediastinal lymph nodes. Chest radiography (X-ray) still plays an important role in suggesting diagnosis for cases with typical presentation of sarcoidosis, while computed tomography (CT) has higher accuracy in detecting early stage disease and in narrowing differential diagnosis, particularly in atypical manifestations. For extrathoracic involvement, both CT and MR (magnetic resonance) have comparable performance even though MR is the modality of choice for assessing neurosarcoidosis and cardiac sarcoidosis. In the last decades positron emission tomography/CT (PET/CT) has demonstrated an increasing and relevant value in assessing disease extent and activity, treatment planning and therapy response, with a crucial role in the management of cardiac sarcoidosis. In this article, an overview of the possible imaging manifestations of thoracic and extrathoracic sarcoidosis and current concepts on staging, response assessment and prognosis is provided. Finally, the potential applications of non-FDG radiotracers is briefly discussed.