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Background and purpose: Cholangiocarcinoma is an infrequent neoplasm barely studied with 18F-FDG-PET/CT. We evaluated the metabolic behavior of cholangiocarcinoma in PET/CT according to its location (intra or extrahepatic) and analyzed the relationship between metabolic parameters of the primary tumor and tumor markers (CA19-9 and CEA), determining their prognostic significance.Methods: Retrospective study of PET/CT of 60 patients with untreated cholangiocarcinoma, divided into two groups according to tumor location. FDG uptake was evaluated visually and semiquantitatively [SUVmax and tumor-to-liver ratio (TLR)], and differences between intra and extrahepatic cholangiocarcinomas were tested, both for FDG uptake in the primary tumor and for the presence of regional or distant disease (per-patient), as well as regarding tumor marker levels. A correlation between metabolic parameters and tumor markers was performed, and prognostic value of these factors was determined (univariate and multivariate analyses).Results: Intrahepatic cholangiocarcinomas were significantly more FDG-avid than extrahepatic ones (p = 0.006 for SUVmax; p = 0.002 for TLR). There were differences neither between both groups considering the capacity of PET/CT to detect regional (p = 0.261) and distant involvement (p = 0.876), nor regarding the levels of tumor markers (p = 0.160 for CA19-9; p = 0.708 for CEA). Metabolic parameters and tumor markers showed a weak positive correlation (R2 0.22-0.27). At the multivariate analysis, advanced stage (p = 0.024), increased CEA (p = 0.022), and higher TLR (p = 0.003) were significantly related with shorter overall survival.Conclusions: Intra and extrahepatic cholangiocarcinomas behave differently on PET/CT, though no differences between both groups exist in its capacity to detect regional or distant disease. Metabolic parameters and levels of tumor markers seem to relate with tumor burden, impacting in prognosis. [ABSTRACT FROM AUTHOR]

Objective: as scarce literature on the topic is available, we aimed to compare diagnostic utility of semi-quantitative versus visual analysis in labelled white blood cell scintigraphy (WBCS) for osteoarticular infection. One-day and two-day protocols were assessed, particularly in orthopaedic devices., Material and Methods: prospective study of 79 consecutive patients with suspected osteoarticular infection. In all patients, WBCS were performed at 30min, 4h, 8h and 24h. Images were analysed by grouping in two protocols: one-day-protocol (experts evaluated 30min, 4h and 8h planar images) and two-day-protocol (experts evaluated 30min, 4h and 24h planar images). Planar images were interpreted qualitative and semiquantitatively and also were compared grouping patients with and without orthopaedic devices. To find which cut-off value of the percentage variation could predict of osteoarticular infection, multiple cut-off values were calculated in both protocols from the Youden index. Three blinded readers analysed the images., Results: Comparing final diagnosis visual analysis of the one-day-protocol provided better results with sensitivity of 95.5%, specificity of 93% and diagnostic accuracy of 93.7% (p<001) than the two-day-protocol with values of 86.4%, 94.7% and 92.4%, respectively (p<001). For semi-quantitative analysis, the one-day-protocol also obtained better results with sensitivity of 72.7%, specificity of 78.9% and accuracy of 77.2% (p<001) than two-day-protocol (no significant results; p=0.14), especially in the group of patients with orthopaedic devices (sensitivity of 100%, specificity of 79.5% and accuracy of 82.7%; p<001)., Conclusions: most accurate approach in the diagnosis of osteoarticular infection corresponded to visual analysis in one-day-protocol that showed greater sensitivity and specificity than semi-quantitative analysis. Semi-quantitative analysis only could be useful when visual analysis is doubtful. In patients with joint prostheses, an increase in percentage variation above 9% obtained maximum sensitivity and negative predictive value., (Copyright © 2020 Sociedad Española de Medicina Nuclear e Imagen Molecular. Published by Elsevier España, S.L.U. All rights reserved.)

The present work investigates the influence of different biological and physical parameters on image quality (IQ) perception of the abdominal area in a modern PET scanner, using new reconstruction algorithms and testing the utility of a radiomics approach. Scans of 112 patients were retrospectively included. Images were reconstructed using both OSEM + PSF and BSRM methods, and IQ of the abdominal region was subjectively evaluated. First, 22 IQ related parameters were obtained (including count rate and biological or mixed parameters) and compared to the subjective IQ scores by means of correlations and logistic regression. Second, an additional set of radiomics features was extracted, and a model was constructed by means of an elastic-net regression. For the OSEM + PSF and especially for the BSRM reconstructions, IQ parameters presented only at best moderated correlations with the subjective IQ. None of the studied parameters presented a good predictive power for IQ, while a simple radiomics model increased the performance of the IQ prediction. These results suggest the necessity of changing the standard parameters to evaluate IQ, particularly when a BSRM algorithm is involved. Furthermore, it seems that a simple radiomics model can outperform the use of any single parameter to assess IQ.

Primary cardiac or pericardial tumors are infrequent, metastatic involvement being more common. Cardiac angiosarcoma is a rare primary malignant tumor of mesenchymal origin. It entails a poor prognosis mostly due to frequent metastases at the time of diagnosis, as well as low response to onco-specific treatments. We describe a case of a 74-year-old patient with a primary cardiac angiosarcoma with an infrequent location at pericardium level. We review the literature and the utility of 18 F-FDG PET/CT in the initial staging., (Copyright © 2018 Sociedad Española de Medicina Nuclear e Imagen Molecular. Publicado por Elsevier España, S.L.U. All rights reserved.)

Objective: Medullary thyroid carcinoma (MTC) is a rare malignancy. Location of residual, recurrent, or metastatic disease is crucial to treatment management and outcome. We aimed to evaluate the use of F-FDG PET/CT in localizing MTC foci in patients with biochemical relapse., Methods: This is a retrospective cohort study. Review of 51 FDG PET/CT studies of 45 patients referred to restage MTC due to increased calcitonin (Ctn) and carcinoembryonic antigen (CEA) values at follow-up. FDG PET/CT diagnostic accuracy was determined through a patient-based analysis, using histology as criterion standard when available, or other imaging studies and clinical follow-up otherwise (mean, 4 years)., Results: There were 25 positive scans. Sensitivity, specificity, positive and negative predictive values, diagnostic accuracy, and positive likelihood ratio were 66.7%, 83.3%, 88.0%, 57.7%, 72.5%, and 4.0, respectively. Using a Ctn cutoff of 1000 pg/mL, sensitivity increased to 76.9%. There were significant differences of Ctn and CEA values between positive and negative FDG PET/CT (P < 0.05). Regarding true-positive studies, average SUVmax comparing locoregional and metastatic disease was at the limit of significance (P = 0.046)., Conclusions: PET/CT can be useful to restage patients with biochemical relapse of MTC, with a better performance in higher Ctn levels. Its high positive predictive value (88%) may impact in the therapeutic management, although its low negative predictive value (57.7%) makes strict follow-up mandatory in examinations without pathologic findings.

Introduction: The aim of this study was to evaluate the behavior of a penalized-likelihood image reconstruction method (Q.Clear) under different count statistics and lesion-to-background ratios (LBR) on a BGO scanner, in order to obtain an optimum penalization factor (β value) to study and optimize for different acquisition protocols and clinical goals., Methods: Both phantom and patient images were evaluated. Data from an image quality phantom were acquired using different Lesion-to-Background ratios and acquisition times. Then, each series of the phantom was reconstructed using β values between 50 and 500, at intervals of 50. Hot and cold contrasts were obtained, as well as background variability and contrast-to-noise ratio (CNR). Fifteen 18 F-FDG patients (five brain scans and 10 torso acquisitions) were acquired and reconstructed using the same β values as in the phantom reconstructions. From each lesion in the torso acquisition, noise, contrast, and signal-to-noise ratio (SNR) were computed. Image quality was assessed by two different nuclear medicine physicians. Additionally, the behaviors of 12 different textural indices were studied over 20 different lesions., Results: Q.Clear quantification and optimization in patient studies depends on the activity concentration as well as on the lesion size. In the studied range, an increase on β is translated in a decrease in lesion contrast and noise. The net product is an overall increase in the SNR, presenting a tendency to a steady value similar to the CNR in phantom data. As the activity concentration or the sphere size increase the optimal β increases, similar results are obtained from clinical data. From the subjective quality assessment, the optimal β value for torso scans is in a range between 300 and 400, and from 100 to 200 for brain scans. For the recommended torso β values, texture indices present coefficients of variation below 10%., Conclusions: Our phantom and patients demonstrate that improvement of CNR and SNR of Q.Clear algorithm which depends on the studied conditions and the penalization factor. Using the Q.Clear reconstruction algorithm in a BGO scanner, a β value of 350 and 200 appears to be the optimal value for 18F-FDG oncology and brain PET/CT, respectively., (© 2018 American Association of Physicists in Medicine.)

The aim of this study was to assess the physical performance of a new PET/CT system, the Discovery IQ with 5-ring detector blocks. Methods: Performance was measured using the National Electrical Manufacturers Association NU2-2012 methodology. Image quality was extended by accounting for different acquisition parameters (lesion-to-background ratios [8:1, 4:1, and 2:1] and acquisition times) and reconstruction algorithms (VUE-point HD [VPHD], VPHD with point-spread-function modeling [VPHD-S], and Q.Clear). Tomographic reconstruction was also assessed using a Jaszczak phantom. Additionally, 30 patient lesions were analyzed to account for differences in lesion volume and SUV quantification between reconstruction algorithms. Results: Spatial resolution ranged from 4.2 mm at 1 cm to 8.5 mm at 20 cm. Sensitivity measured at the center and at 10 cm was 22.8 and 20.4 kps/kBq, respectively. The noise-equivalent counting rate peak was 124 kcps at 9.1 kBq/cm 3 The scatter fraction was 36.2%. The accuracy of correction for count losses and randoms was 3.9%. In the image quality test, contrast recovery for VPHD, VPHD-S, and Q.Clear ranged from 18%, 18%, and 13%, respectively (hot contrast; 10-mm sphere diameter; ratio, 2:1), to 68%, 67%, and 81%, respectively (cold contrast; 37-mm sphere diameter; ratio, 8:1). Background variability ranged from 3.4%, 3.0%, and 2.1%, respectively (ratio, 2:1), to 5.5%, 4.8%, and 3.7%, respectively (ratio, 8:1). On Q.Clear reconstruction, the decrease in the penalty term (β) increased the contrast recovery coefficients and background variability. With the Jaszczak phantom, image quality increased overall when a reconstruction algorithm modeling the point-spread function was used, and use of Q.Clear increased the signal-to-noise ratio. Lesions analyzed using VPHD-S and Q.Clear had an SUV mean of 6.5 ± 3 and 7 ± 3, respectively ( P < 0.01), and an SUV max of 11 ± 4.8 and 12 ± 4, respectively ( P < 0.01). No significant difference in mean lesion volume was found between algorithms. Conclusion: Among the various Discovery bismuth germanium oxide-based PET/CT scanners, the IQ with 5-ring detector blocks has the highest overall performance, with improved sensitivity and counting rate performance. Q.Clear reconstruction improves the PET image quality, with higher recovery coefficients and lower background variability., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

Computed tomography (CT) has been used as the reference imaging technique for the initial staging of diffuse large B-cell lymphoma until recent days, when the introduction of positron emission tomography (PET)/CT imaging as a hybrid technique has become of routine use. However, the performance of both examinations is still common. The aim of this work was to compare the findings between low-dose 2-deoxy-2-((18)F)fluoro-d-glucose ((18)F-FDG) PET/CT and full-dose contrast-enhanced CT (ceCT) in 28 patients with localized diffuse large B-cell lymphoma according to PET/CT findings, in order to avoid the performance of ceCT. For each technique, a comparison in the number of nodal and extranodal involved regions was performed. PET/CT showed more lesions than ceCT in both nodal (41 vs. 36) and extranodal localizations (16 vs. 15). Disease staging according to both techniques was concordant in 22 patients (79%) and discordant in 6 patients (21%), changing treatment management in 3 patients (11%). PET/CT determined a better staging and therapeutic approach, making the performance of an additional ceCT unnecessary.

The development of molecular and functional imaging with new imaging techniques such as computed tomography, magnetic resonance imaging, and positron emission tomography (PET) among others, has greatly improved the detection of tumors, tumor staging, and the detection of possible recurrences. Furthermore, the combination of these different imaging modalities and the continual development of radiotracers for PET have advanced our understanding and knowledge of the different pathophysiological processes in cancer, thereby helping to make treatment more efficacious, improving patients' quality of life, and increasing survival. PET is one of the imaging techniques that has attracted the most interest in recent years for its diagnostic capabilities. Its ability to anatomically locate pathologic foci of metabolic activity has revolutionized the detection and staging of many tumors, exponentially broadening its potential indications not only in oncology but also in other fields such as cardiology, neurology, and inflammatory and infectious diseases., (Copyright © 2016 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.)

There is a growing interest in using quantification in FDG-PET/CT in oncology, especially for evaluating response to therapy. Complex full quantitative procedures with blood sampling and dynamic scanning have been clinically replaced by the use of standardized uptake value measurements that provide an index of regional tracer uptake normalized to the administered dose of FDG. Some approaches have been proposed for assessing quantitative metabolic response, such as EORTC and PERCIST criteria in solid tumors. When using standardized uptake value in clinical routine and multicenter trials, standardization of protocols and quality control procedures of instrumentation is required., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: The evaluation of bone marrow infiltration (BMI) is of crucial importance in the staging of lymphoma. Although bone marrow biopsy (BMB) is the reference standard for the evaluation of BMI, it has limitations. PET/CT has become an excellent tool in staging of lymphoma, and bone marrow uptake is correlated with the involvement of lymphoma. The aim of this study was to assess the utility of PET/CT and its concordance with BMB in the detection of BMI in patients with diffuse large B-cell lymphoma (DLBCL) and Hodgkin lymphoma (HL)., Patients and Methods: One hundred forty-seven patients with DLBCL (84) and HL (63) were referred for a PET/CT and a BMB (unilateral) at the initial staging. The reference standard was BMB., Results: Bone marrow infiltration was detected by PET/CT in 39 (26%) and by BMB in 21 (14%) cases. There was concordance between PET/CT and BMB in 128 patients (87%) (74 DLBCL, 54 HL), 21 with positive PET/CT and BMB results and 107 with negative PET/CT and BMB results. Discordant results were observed in 19 patients (14%); 18 of them with positive PET/CT and negative standard BMB results (not performed in active sites). The sensitivity, specificity, accuracy, as well as positive and negative predictive values of FDG-PET/CT for the detection of BMI were 95%, 86%, 87%, 54%, and 99%, respectively., Conclusions: PET/CT detects more bone marrow involvement in DLBCL and HL compared with BMB. Its good concordance with BMB makes it a complementary technique, as it helps select the biopsy site in cases with negative results.

Positron emission tomography/computed tomography (PET/CT) is a hybrid imaging technique that combines the anatomic information from CT with the metabolic information acquired from PET after the administration of specific radiotracers, the most commonly used of which is F18-fluorodeoxyglucose (FDG). In oncology, this technique is based on the increased uptake of FDG by malignant lesions. In the locomotor apparatus, some uptake by bones and soft tissues is physiological or benign and this uptake must be differentiated from uptake by malignancies, whether primary or secondary. The most important limitations are active inflammatory or infectious processes, which are positive on PET images, and malignant lesions that are smaller than 1cm, cystic, necrotic, or low-grade, which are negative on PET images. PET/CT in the locomotor apparatus is especially useful for the detection of metastases from the most common tumors. It is also used for staging and monitoring the response to treatment of some hematological tumors like lymphoma, where it is fundamental to determine whether the bone marrow has been infiltrated, or myeloma. Lastly, although it is not yet an established indication, PET/CT is being increasingly used to study sarcomas, because it can provide additional information that can be useful for the characterization and grading of tumors, for guiding biopsies, for staging and re-staging, and for evaluating the response to neoadjuvant therapy as well as for evaluating new drugs in clinical trials., (Copyright © 2012 SERAM. Published by Elsevier Espana. All rights reserved.)

Objective: To determine the value of whole-body [(18)F] fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for diagnosing occult malignant disease in patients with myositis compared with broad conventional cancer screening., Methods: We prospectively studied 55 consecutive patients with a recent diagnosis of myositis in 3 teaching hospitals over a 3-year period by whole-body FDG-PET/CT and compared the results with those of conventional cancer screening, which included thoracoabdominal CT, mammography, gynecologic examination, ultrasonography, and tumor marker analysis. Comparisons were made using predictive values and their 95% confidence intervals., Results: A total of 9 of 55 patients were diagnosed with paraneoplastic myositis. FDG uptake was positive in 7 patients (1 false-positive), negative in 44 patients (3 false-negative), and inconclusive in 4 patients. Positive and negative predictive values of FDG-PET/CT for the diagnosis of cancer were 85.7% and 93.8%, respectively. Conventional screening was cancer-positive in 9 patients (2 false-positive) and negative in the remaining 46 patients (2 false-negative). Positive and negative predictive values were 77.8% and 95.7%, respectively. The overall predictive value of broad conventional screening was the same as that of FDG-PET/CT (92.7 vs 92.7)., Conclusion: The performance of FDG-PET/CT, a single imaging study, for diagnosing occult malignant disease in patients with myositis was comparable to that of broad conventional screening, which includes multiple tests., (Copyright 2010 Elsevier Inc. All rights reserved.)

Objective: The incidence of esophageal cancer has increased considerably over recent years, it now being the 6th most frequent cause of cancer-related death. Our study has aimed to compare the clinical value of PET/CT and CT scan in the initial staging of patients with esophageal cancer., Material and Methods: Fifty nine patients (6 women) diagnosed of esophageal cancer were assessed retrospectively. All patients underwent diagnostic CT scan and PET/CT for initial staging within 3 to 15 days following clinical diagnosis., Results: PET/CT showed intracellular (18)F-FDG entrapment having pathological significance in all the tumors (100%), signs of locoregional lymph node infiltration (N1) in 34 and a total of 19 lesions consistent with metastasis (M1) in 14 patients (23.72%). The CT scan detected malignancy in 57 patients (96.6%), abnormal lymph node in 32 patients and 17 N1 in 12 patients (20.33%). In three cases, CT- PET detected synchronous esophageal lesion in staging studies for other neoplastic processes (lung and ear-nose-throat)., Conclusion: PET/CT showed a higher detection rate of primary malignant lesions, abnormal lymph nodes and distant metastases. A change in stage was only observed in two patients.

Objective: The present study was designed to determine whether 24-hour imaging after thallium reinjection or imaging obtained shortly after reinjection provides better results regarding reversibility of fixed perfusion defects observed in conventional stress-redistribution imaging., Patients and Methods: We studied 24 patients undergoing stress-redistribution thallium tomography with fixed defects (15 exercise, 6 adenosine, 3 dobutamine). All patients had coronary angiography and 17 a history of myocardial infarction. After obtaining the redistribution images, 1 mCi thallium was injected at rest, and images were acquired at 30 minutes and 24 hours after reinjection. The tomograms obtained were divided into 12 segments and analyzed quantitatively., Results: Of the 190 abnormal segments on the stress images, 53 (28%) demonstrated improved thallium uptake on redistribution images and 137 had persistent defects. Shortly after reinjection, 33 (24%) segments had improved thallium uptake and 104 had persistent defects, 29 (28%) of which showed further improvement in the 24-hour study. In patients with myocardial infarction, of the 36 fixed severe defects, 9 (25%) had improved thallium uptake shortly after reinjection, increasing activity from 36 +/- 10% to 53 +/- 8%, and 22 (61%) defects improved at 24 hours, increasing activity from 37 +/- 8% to 56 +/- 6%. Therefore, 13 irreversible segments in the short-term study after reinjection were reversible on 24-hour images., Conclusion: These data indicate that 24-hour imaging after thallium reinjection provides better results regarding reversibility of fixed perfusion defects observed in conventional stress-redistribution imaging than imaging obtained shortly after reinjection.