[en] Myocardial necrosis plays an important role in the pathogenesis of various cardiovascular disorders and can result from different myocardial insults. Its non-invasive identification and localisation therefore may help in the diagnosis of these disorders, as well as in prognosis and assessment of treatment response. Apoptosis, or programmed cell death, is important in the spectrum of myocardial damage since it is gradually becoming more apparent that cell death may begin as apoptosis and not as necrosis. First attempts to directly visualise the area of myocardial necrosis were based on recognition of myocardial infarction with ''hot spot imaging agents'' in patients with chest pain. Since then, the study of myocardial necrosis with gamma imaging agents has gone beyond the detection of myocardial infarction, and attempts have been made to diagnose other cardiovascular disorders associated with cardiac cell death such as heart transplant rejection, myocarditis, cardiotoxicity and cardiomyopathies. Traditionally, two hot spot imaging agents have been used for the detection of myocardial necrosis, ^99mTc-pyrophosphate and ¹¹¹In-antimyosin. In addition, preliminary studies have demonstrated promising results with ^99mTc-glucarate. Recently, ^99mTc-annexin V has been successfully used for non-invasive gamma imaging of apoptosis after acute myocardial infarction, acute myocardial ischaemia, acute cardiac allograft rejection and malignant intracardiac tumours. This review article focusses on the characteristics of these different myocardial necrotic and apoptotic markers and compares their role in the assessment of myocardial damage. (orig.)

No abstract available

[en] Scintigraphy with ^99mTc-depreotide, a somatostatin analogue-technetium ligand, has been used for evaluation of various malignant neoplasms, including lung cancer. The diagnosis of bone metastases in patients with lung cancer is not always definitive with current imaging methods. Visualisation of somatostatin receptors (SSTRs) in bone lesions, when the primary tumour exhibits such receptors, could be helpful in characterising them as metastatic. The aim of this study was to assess the value of ^99mTc-depreotide in differentiating between benign and malignant bone lesions in patients with lung cancer. The study population comprised 20 patients (17 males and three females, mean age 63 years) with proven lung cancer in whom bone lesions had been detected by conventional imaging methods. All patients underwent ^99mTc-hydroxydiethylene diphosphonate and ^99mTc-depreotide scintigraphy within 2 weeks. Bone lesions were classified as benign or malignant on the basis of clinical, imaging and/or histological criteria. ^99m Tc-depreotide uptake in the primary tumour was seen in 19 of the 20 patients. Conventional imaging methods detected 55 bone lesions, 31 of which were classified as malignant. Twenty-eight (90%) of these lesions showed ^99mTc-depreotide uptake, suggesting bone metastases, while three did not. Twenty-four bone lesions were classified as benign by conventional imaging methods, and none of them showed ^99mTc-depreotide uptake. In addition, ^99mTc-depreotide demonstrated extra-osseous lesions in six patients. In patients with lung cancer and bone lesions, ^99mTc-depreotide scintigraphy uptake in the bone lesions supports the diagnosis of malignancy, in particular if the primary lung tumour also exhibits SSTRs. Furthermore, whole-body ^99mTc-depreotide scintigraphy may disclose extra-osseous disease. (orig.)

[en] Neurodegenerative diseases occur when neurons in the central and/or peripheral nervous systems lose function over time and ultimately die. They are characterized by common cellular and molecular mechanisms including protein aggregation and inclusion body formation, categorising each type of disease. Therefore, the definitive diagnosis is at post-mortem, based on pathology. However, the development of various molecular imaging techniques has enabled pathological changes to be inferred in vivo. Decreased myocardial ¹²³I-mIBG uptake has been reported in some patients with neurodegenerative diseases. This review is aimed to synthesise the basis, methodology and clinical role of myocardial ¹²³I-mIBG imaging in the diagnosis of certain neurodegenerative diseases, focusing on its utility to differentiate some neurodegenerative Parkinsonisms between them, and to differentiate dementia with Lewy bodies from Alzheimer’s disease and other dementias.

[en] The purpose of this study was to compare image quality and lesion detection capability between a digital and an analog PET/CT system in oncological patients. One hundred oncological patients (62 men, 38 women; mean age of 65 ± 12 years) were prospectively included from January–June 2018. All patients, who accepted to be scanned by two systems, consecutively underwent a single day, dual imaging protocol (digital and analog PET/CT). Three nuclear medicine physicians evaluated image quality using a 4-point scale (−1, poor; 0, fair; 1, good; 2, excellent) and detection capability by counting the number of lesions with increased radiotracer uptake. Differences were considered significant for a p value <0.05. Improved image quality in the digital over the analog system was observed in 54% of the patients (p = 0.05, 95% CI, 44.2–63.5). The percentage of interrater concordance in lesion detection capability between the digital and analog systems was 97%, with an interrater measure agreement of κ = 0.901 (p < 0.0001). Although there was no significant difference in the total number of lesions detected by the two systems (digital: 5.03 ± 10.6 vs. analog: 4.53 ± 10.29; p = 0.7), the digital system detected more lesions in 22 of 83 of PET+ patients (26.5%) (p = 0.05, 95% CI, 17.9–36.7). In these 22 patients, all lesions detected by the digital PET/CT (and not by the analog PET/CT) were < 10 mm. Digital PET/CT offers improved image quality and lesion detection capability over the analog PET/CT in oncological patients, and even better for sub-centimeter lesions.

[en] The purpose of this study was to assess whether digital photon counting technology in digital PET/CT influences the quantification of SUVmax in target lesions and regions of reference compared to analog PET/CT before an interchangeable use of either system in follow up studies. From January to June of 2018, 100 oncological patients underwent successive PET/CT imaging with digital and analog systems in the same day. Fifty-eight patients underwent analog imaging first and digital imaging thereafter, and 42 patients the other way round. SUVmax was measured in reference regions (liver and mediastinal blood pool) and in the most metabolically active target lesion in each patient. According to the sequence order of PET/CT acquisition, two groups of SUVmax values were obtained, i.e. group 1: analog PET/CT performed first; group 2: digital PET/CT performed first. Mean SUVmax in the total sample (regardless of the order of PET/CT acquisition) in the target lesions with the analog PET/CT was 8.14 ± 6.39 and the digital 9.97 ± 6.14 (P = 0.000). Total mean SUVmax in the liver with the analog was 4.39 ± 2.59 and the digital 4.46 ± 3.18 (P = 0.477). Total mean SUVmax in the mediastinal blood pool with the analog was 2.30 ± 0.67 and the digital 2.54 ± 0.74 (P = 0.000). Group 1: mean SUVmax in the target lesions with the analog system was 6.64 ± 4.71 and the digital 9.48 ± 5.60 (P = 0.000). Mean liver SUVmax with the analog was 4.70 ± 2.90 and the digital 4.80 ± 3.72 (P = 0.088). Mediastinal blood pool SUVmax with the analog was 2.33 ± 0.66 and the digital 2.45 ± 0.73 (P = 0.041). Group 2: mean SUVmax in target lesions with the digital system was 10.63 ± 6.88 and the analog 10.16 ± 7.76 (P = 0.046). Mean liver SUVmax with the digital was 3.99 ± 2.20 and the analog 3.96 ± 2.04 (P = 0.218). Mediastinal blood pool SUVmax with the digital was 2.66 ± 0.75 and the analog 2.27 ± 0.68 (P = 0.000). No significant differences between both time delays were found. Improved photon counting technology in the digital PET/CT, and the effect of delayed increased uptake and retention significantly increases SUVmax values. This has to be taken into account before interchangeable use of either system in follow up studies.

[en] Imaging with metaiodobenzylguanidine (MIBG) is used for the assessment of neuronal dysfunction in various cardiovascular disorders. Although valuable information is obtained by resting MIBG imaging, it is conceivable that competitive interference with the re-uptake mechanism would exaggerate MIBG defects and might unmask subclinical neuronal dysfunction. Tricyclic antidepressants, such as amitriptyline, have been reported to significantly increase cardiac MIBG washout and inhibit uptake into presynaptic neurons. This study was undertaken to assess whether a single oral dose of amitriptyline could influence cardiac MIBG distribution. Six patients (aged 62-81 years; four males, two females) who had demonstrated a normal cardiac MIBG scan during work-up for movement disorders were studied. The patients underwent a second ¹²³I-MIBG study after oral administration of 25 mg amitriptyline within 1 week. Single-photon emission computed tomography images were acquired at 4 h to assess the regional distribution of MIBG, after generation of polar maps and employing a 20-segment model. Mean percentage of peak activity was calculated for each segment at rest and after amitriptyline administration. After amitriptyline administration, there was a decrease in regional MIBG uptake in 10±4 segments per patient [62/120 segments (52%): 37 segments with a 5-10% decrease, 25 segments with a >10% decrease]. This change was statistically significant in lateral (P=0.003), apical (P<0.0001) and inferior (P=0.03) regions. A single oral dose of amitriptyline can induce changes in the uptake and retention of cardiac MIBG, indicating the feasibility of use of pharmacological intervention in cardiac neurotransmission imaging. (orig.)

[en] Differential diagnosis between dementia with Lewy bodies (DLB) and other neurodegenerative diseases with cognitive impairment represents a clinical challenge. Due to the overlapping of symptoms, the clinical diagnosis can be modified during the prolonged follow-up of these diseases. The purpose of this study was to assess the ability of cardiac metaiodobenzylguanidine (MIBG) imaging for early identification of DLB. Since January 2003, all patients with neurodegenerative diseases with cognitive impairment at their first visit at the Memory Unit and clinical criteria of DLB were consecutively recruited and underwent a cardiac ¹²³I-MIBG study. The heart-to-mediastinum ratio (HMR) and the washout rate (WR) of cardiac MIBG uptake were obtained. Sixty-five patients were included. After a clinical follow-up of 4 years, the progress of the disease procured a definite diagnosis in 44 (68%) patients: 19 DLB, 12 Alzheimer disease (AD), and 13 other neurodegenerative diseases with cognitive impairment. HMR was significantly decreased in DLB with respect to the other neurodegenerative diseases. WR was only significantly different between DLB and AD. The HMR cut off point of 1.36 differentiated DLB from the other dementias with a sensitivity of 94% and a specificity of 96% with an accuracy of 95%. Cardiac MIBG imaging performed at the time of the first clinical diagnosis of DLB can help early clinical identification or exclusion of this disease. (orig.)

[en] Physiological glucose uptake by the myocardium may hamper visualization of coronary atherosclerotic plaques in ¹⁸F-FDG PET studies. Intracellular myocardial calcium relates to glucose influx. We assessed whether administration of a calcium channel blocker such as verapamil could decrease myocardial ¹⁸F-FDG uptake in mice. Experiments were conducted on ten male C57BL/6JOlaHsd mice. The mice were studied by ¹⁸F-FDG PET/CT under basal conditions and after a single administration of verapamil injected 1 h prior to ¹⁸F-FDG administration at doses of 1 mg/kg (group A, n = 5) and 20 mg/kg (group B, n = 5). PET scanning was started 60 min after injection of ¹⁸F-FDG employing a dedicated small-animal PET/CT system (ARGUS-CT). In each mouse, post-verapamil PET images were coregistered with the basal PET images. Volumetric regions of interest (VOI) were drawn on the basal study containing the myocardium of the whole left ventricle and quantitatively compared with the same VOI applied to the post-verapamil scan. The SUV_mean was used to express the mean myocardial ¹⁸F-FDG uptake. The relative coefficient of variation (RV) between the basal and post-verapamil conditions was calculated. Verapamil administration decreased myocardial ¹⁸F-FDG uptake in all animals. The median (range) SUV_mean values in group A were 2.6 (1.6-4.1) under basal conditions and 1.7 (1.1-2.9) after verapamil administration (p = 0.043), and in group B were 1.6 (1.3-2.0) under basal conditions and 1.0 (0.9-1.4) after verapamil administration (p = 0.043). The median (range) RV values were -31% (-5%, -50%) in group A, and -37% (-10%, -51%) in group B (p = 0.6). In this animal model there was a significant reduction in ¹⁸F-FDG uptake in the myocardium following verapamil administration. This type of intervention could facilitate the definition of coronary atherosclerotic plaque inflammation on ¹⁸F-FDG PET scans. (orig.)

[en] The article Digital vs. analog PET/CT: intra-subject comparison of the SUVmax in target lesions and reference regions, written by Francisco Fuentes-Ocampo, Diego Alfonso López-Mora, Albert Flotats, Gabriela Paillahueque