Comprehensive literature review of oral and intravenous contrast-enhanced PET/CT: a step forward?

The integration of diagnostic CT scans into PET/CT facilitates a comprehensive single examination, presenting potential advantages for patients seeking a thorough one-shot check-up. The introduction of iodinated contrast media during PET scanning raises theoretical concerns about potential interference with uptake quantification, due to the modification of tissue density on CT. Nevertheless, this impact appears generally insignificant for clinical use, compared to the intrinsic variability of standardized uptake values. On the other hand, with the growing indications of PET, especially 18F-FDG PET, contrast enhancement increases the diagnostic performances of the exam, and provides additional information. This improvement in performance achieved through contrast-enhanced PET/CT must be carefully evaluated considering the associated risks and side-effects stemming from the administration of iodinated contrast media. Within this article, we present a comprehensive literature review of contrast enhanced PET/CT, examining the potential impact of iodinated contrast media on quantification, additional side-effects and the pivotal clinically demonstrated benefits of an all-encompassing examination for patients. In conclusion, the clinical benefits of iodinated contrast media are mainly validated by the large diffusion in PET protocols. Contrary to positive oral contrast, which does not appear to offer any major advantage in patient management, intravenous iodine contrast media provides clinical benefits without significant artifact on images or quantification. However, studies on the benefit-risk balance for patients are still lacking.

Potential utility of myocardial blood flow quantification with single photon emission computed tomography in a patient undergoing treatment for breast cancer.

Diagnosis and management of cardiac complications of cancer treatment can be challenging. Few PET data suggest a potential role of dynamic perfusion imaging with measurements of absolute myocardial blood flow and flow reserve (MFR). We report the case of a 72-year-old woman with a history of bilateral breast cancer who underwent dynamic cardiac scintigraphy. Relative perfusion analysis was normal, whereas MFR was impaired in all territories suggesting diffuse microvascular dysfunction. Flow parameters derived from dynamic cardiac scintigraphy could thus be an interesting tool in cardio-oncology.

Osteonecrosis of the Femoral Head as a Potential Pitfall in 18 F-PSMA-1007 PET.

ABSTRACT: PSMA-targeted PET agents are mainly involved for prostate cancer; however, unspecific bone uptakes can be challenging for the clinician. We report the case of a 71-year-old man with history of recurrent prostate cancer initially treated by surgery and radiation therapy. 18 F-PSMA 1007 PET/CT was performed. Beside hyperfixing lymph nodes, focal uptake was found in right femoral head with shell subchondral hypofixation and no morphologic correlate on CT. MRI found bilateral osteonecrosis of the femoral head. This case emphasizes that osteonecrosis of the femoral head can mimic a metastasis uptake, even with normal CT, without however the fixation being constant.

From modern-day parasitology to paleoparasitology: the elusive past record and evolution of Cryptosporidium.

Recent efforts have been made to review the state of the art on a variety of questions and targets in paleoparasitology, including protozoan taxa. Meanwhile, these efforts seemed to let aside Cryptosporidium, and we then intended to review its paleoparasitological record to assess its past distribution and favored detection methods, and eventually highlight needed research trajectories. This review shows that contrary to other parasites, most of the positive results came from South-American sites and coprolites rather than sediment samples, highlighting the need to test this kind of material, notably in Europe where many negative results were reported in the published literature from sediment samples. Moreover, aDNA-based detections are nearly absent from the paleoparasitological record of this parasite, though punctually shown successful. With their potential to address the evolutionary history of Cryptosporidium species, notably through their 18S rRNA tree, aDNA-based approaches should be encouraged in the future. In sum, and though the limits of currently used methods and materials remain unclear, this review highlights the potential role of coprolites and aDNA for the study of Cryptosporidium species in the past and how this history shaped their current diversity and distribution, notably among human populations but also farm animals.

Implications of the prevalence of Ascaris sp. in the funerary context of a Late Antique population (5th-7th c.) in Granada (Spain).

OBJECTIVE: To evaluate the prevalence of gastro-intestinal parasites in human remains from Late Antiquity (5th - 7th c.) Granada (Spain). MATERIALS: The study included pelvic and cranial control samples from 17 skeletons from the archaeological sites of Los Mondragones (n = 13) and Rafael Guillén (n = 4). METHODS: In the paleoparasitological study, soil samples from pelvic area and cranium were analyzed using the rehydration, homogenization, and micro-sieving method and visualization under brightfield microscopy. RESULTS: Ascaris sp. eggs were detected in pelvic samples from seven individuals. CONCLUSIONS: These findings may indicate that this parasite was endemic. Its detection frequency is one of the highest reported at group level in an osteological series from Late Antiquity. SIGNIFICANCE: The prevalence of Ascaris sp. associated with skeletal remains has implications for assessing the lifestyle and health of populations in southern Spain during the Late Antique period. LIMITATIONS: The number of individuals is small and taphonomic processes could have limited paleoparasitological findings SUGGESTIONS FOR FURTHER RESEARCH: Future interdisciplinary studies of this type are warranted in larger osteological series to improve knowledge of parasitosis in the past.

Dynamic CZT-SPECT: Characterizing the Lower Values of Myocardial Blood Flow and Reserve.

ABSTRACT: CZT-SPECT myocardial perfusion enables quantification of myocardial blood flow (MBF). Normal values and thresholds have been accurately defined in PET but remain unclear in SPECT. The aim of this study was to report normal MBF and myocardial flow reserve values in very low-risk patients referred for coronary artery disease screening with dynamic SPECT, in comparison with patients experiencing coronary artery disease. Eighty-four patients (31 male) were analyzed. The mean 10 years risk of fatal cardiovascular events score was 2.7% ± 1.4%. The mean global stress MBF and myocardial flow reserve were 1.6 ± 0.6 mL/min/g and 2.7 ± 0.7.

3D-Ring CZT System With New Low- and Medium-Energy Range: Ultrafast Dual-Isotope Lung SPECT/CT Improvement.

ABSTRACT: New 3D-ring CZT systems with low- and medium-energy-range detectors allow for simultaneous dual-isotope lung scintigraphy. We compared 10-, 7-, 5-, and 3-minute acquisitions for 99m Tc and 81m Kr performed simultaneously on StarGuide CZT-SPECT/CT and reframed in 50 patients. Ventilation/perfusion mismatches were calculated (mean, 15.6% ± 28%), and Spearman correlation coefficients of mismatches were 0.994, 0.994, and 0.984 between 10- and 7-, 5-, and 3-minute acquisitions, respectively. No visual difference in image quality or final diagnosis was found. 3D-ring CZT-SPECT with low and medium energy range detectors allows ultrafast dual-isotope lung scintigraphy up to 3 minutes.

Extinction of Lipomatous Hypertrophy of the Interatrial Septum FDG Uptake With Propranolol Premedication.

ABSTRACT: Lipomatous hypertrophy of the interatrial septum is a rare lesion of the heart. CT and cardiac MR are often sufficient to determine the benign lipomatous nature of the tumor and can avoid the need for histological confirmation. Lipomatous hypertrophy of the interatrial septum contains variable amounts of brown adipose tissue, resulting in different degrees of 18 F-FDG uptake in PET. We report the case of a patient with an interatrial lesion suspected of malignancy, discovered on CT and failing cardiac MR, with initial 18 F-FDG uptake. Final characterization was made thanks to 18 F-FDG PET with ß-blocker premedication, avoiding an invasive procedure.

Precision of Myocardial Blood Flow and Flow Reserve Measurement During CZT SPECT Perfusion Imaging Processing: Intra- and Interobserver Variability.

The aim of this study was to evaluate the reproducibility of myocardial blood flow (MBF) and myocardial flow reserve (MFR) measurement in patients referred for dynamic SPECT. Methods: We retrospectively analyzed patients referred for myocardial perfusion imaging. SPECT data were acquired on a cadmium zinc telluride-based pinhole cardiac camera in list mode using a stress (251 ± 15 MBq)/rest (512 ± 26 MBq) 1-d 99mTc-tetrofosmin protocol. Kinetic analyses were done with software using a 1-tissue-compartment model and converted to MBF using a previously determined extraction fraction correction. MFR was analyzed and compared globally and regionally. Motion detection was applied, but not attenuation correction. Results: In total, 124 patients (64 male, 60 female) were included, and SPECT acquisitions were twice reconstructed by the same nuclear medicine board-certified physician for 50 patients and by 2 different physicians for 74. Both intra- and interobserver measurements of global MFR had no significant bias (-0.01 [P = 0.94] and 0.01 [P = 0.67], respectively). However, rest MBF and stress MBF were significantly different in global left ventricular evaluation (P = 0.001 and P = 0.002, respectively) and in the anterior territory (P < 0.0001) on interuser analysis. The average coefficient of variation was 15%-30% of the mean stress MBF if the analysis was performed by the same physician or 2 different physicians and was around 20% of the mean MFR independently of the processing physician. Using the MFR threshold of 2, we noticed good intrauser agreement, whereas it was moderate when the users were different (κ = 0.75 [95% CI, 0.56-0.94] vs. 0.56 [95% CI, 0.36-0.75], respectively). Conclusion: Repeated measurements of global MFR by the same physician or 2 different physicians were similar, with an average coefficient of variation of 20%. Better reproducibility was achieved for intrauser MBF evaluation. Automation of processing is needed to improve reproducibility.

A study protocol for an observational cohort investigating cardiac transthyretin amyloidosis flow reserve before and after Tafamidis treatment: The AMYTRE study.

Introduction: Anginal symptoms and signs of ischemia have been reported in some patients with cardiac transthyretin amyloidosis (ATTR) without obstructive epicardial coronary artery disease (CAD). Few studies found that coronary microvascular dysfunction was highly prevalent in subjects with cardiac amyloidosis, even in the absence of epicardial CAD. The purpose of this study is to confirm the coronary microvascular dysfunction, and to go further with evaluation of the effect of Tafamidis on microvascular dysfunction after 24 months of treatment. Methods and analysis: This study is a multicentric, prospective, observational cohort study. Adult patients with confirmed ATTR cardiomyopathy seen in the nuclear medicine departments of three large referral centers and treated with Tafamidis will be included. At baseline, patients will have a clinical and echocardiography evaluation. They will undergo a dynamic rest/stress cardiac scintigraphy with flow and reserve measurements before and 24 months after Tafamidis introduction. The primary outcome of this study will be the variation of stress and rest myocardial blood flow and flow reserve between baseline and 24 months after treatment. The effect of Tafamidis will be assessed by an intention to treat analysis. Ethics and dissemination: The study has received the following approvals: Orleans Hospital Research Committee (CHRO-2021-05) and Sud-Mediterranée IV Regional Ethics Committee (21 06 02). Results will be made available to physicians, the funders, and other researchers. Clinical trial registration: [https://clinicaltrials.gov/ct2/show/NCT05103943], identifier [NCT05103943].

18 F-FDG Muscular Uptake in Statin-Associated Symptoms Without Myositis : How Long to Stop Treatment for Image Quality Improvement?

ABSTRACT: Statin-associated muscle symptoms are a frequent adverse effect of statin treatment and can lead to a statin-associated myopathy characterized by a significant serum creatine kinase increase. We report the case of an 80-year-old man who presented an increased muscular 18 F-FDG uptake in a statin-associated muscle symptom without creatine kinase abnormality or inflammation. Statin treatment was discontinued for 6 hours, 3 days, and 7 days on consecutive follow-up examinations. The 1-week window clearly enhanced image quality. This case illustrates the possibility of diffuse muscular 18 F-FDG uptake without myositis and the need for a minimal 1-week statin discontinuation to reduce muscular uptake.

Case Report: Potential Applications of Using a 3D-Ring CZT SPECT for Lymphoscintigraphic Exploration of Lower Limb Edema.

Lymphoscintigraphy is still considered the gold standard imaging modality for diagnosing lymphedema, due to ineffective lymphatic transport resulting in edema and skin damage. However, protocol variability and poor image resolution can make the interpretation challenging. Up to now, 99 mTc-labeled colloid lymphatic travel is monitored with dual-head cameras, but single-photon emission CT (SPECT) has proved its interest. Here, we present the case of a 59-year-old-man with bilateral asymmetric lower limb edema which was explored using dual-head and new 3D-ring cadmium -zinc-telluride (CZT) SPECT cameras, confirming bilateral lower limb lymphatic dysfunction. In line with other recently published reports, this case report promotes the use of SPECT/CT in the lymphoscintigraphic exploration of lower limb edema. The recognition of the clinicopathologic features of lower limb edema is required to prevent missed diagnoses, such as compressive disease, tumors, etc., as well as to better influence the management of patients.

Gated Tomographic Radionuclide Angiography Using 3D-Ring CZT StarGuide SPECT/CT Head-To-Head Comparison With a Cardiac-Dedicated CZT Camera: First Clinical Use and Validation.

ABSTRACT: Gated tomographic radionuclide angiography can assess and monitor left cardiac function. Dedicated cardiac CZT cameras have enabled dose reduction and quicker acquisitions. New 3D-ring CZT general purpose systems are now available. We report 50 patients who underwent a 7-minute acquisition on a cardiac-dedicated CZT camera and 9 minutes on a new 3D-ring CZT system after mean injection of 321.4 ± 55.9 MBq 99mTc-labelled human serum albumin. There was no significant difference in left ventricular volumes, and left and right ventricular ejection fractions. These preliminary results seem to validate the use of 3D-ring CZT system for LEVF and cardiac function evaluation.

Regadenoson versus dipyridamole: Evaluation of stress myocardial blood flow response on a CZT-SPECT camera.

BACKGROUND: Regadenoson is a selective adenosine receptor agonist. It is currently unclear if the level of hyperemia differs between stress agents. We compared Myocardial Blood Flow (MBF) and Myocardial Flow Reserve (MFR) response on CZT-SPECT Myocardial Perfusion Imaging (MPI) to evaluate if dipyridamole and regadenoson could induce the same level of hyperemia. METHODS: 228 patients with dynamic CZT-SPECT MPI were retrospectively analyzed (66 patients stressed with regadenoson and 162 with dipyridamole) in terms of MBF and MFR. To rule out confounding factors, two groups of 41 patients were matched for clinical characteristics in a sub-analysis, excluding high cardiovascular risk patients. RESULTS: Overall stress MBF was higher in regadenoson patients (1.71 ± 0.73 vs. 1.44 ± 0.55 mL·min-1·g-1 for regadenoson and dipyridamole, respectively, p < .05). However, when confounding factors were ruled out, stress MBF (1.57 ± 0.56 vs. 1.61 ± 0.62 mL·min-1·g-1 for dipyridamole and regadenoson, respectively, p = .88) and MFR (2.62 ± 0.77 vs. 2.46 ± 0.76 for dipyridamole and regadenoson, respectively, p = .40) were not different between regadenoson and dipyridamole. CONCLUSIONS: Our results suggest that dipyridamole and regadenoson induce equivalent hyperemia in dynamic SPECT with similar stress MBF and MFR in comparable patients.

Combining flow and reserve measurement during myocardial perfusion imaging: A new era for myocardial perfusion scintigraphy?

Myocardial flow reserve represents the ratio of myocardial blood flow between stress and rest, giving functional information about both macrocirculation and microcirculation; it has been reported extensively in positron emission tomography, with an increase in diagnostic performance, providing important prognostic information and being a powerful tool to guide therapy. Advances in single photon emission computed tomography, with the widespread availability of "cadmium zinc telluride" single photon emission computed tomography cameras, raise the question of myocardial flow reserve use in daily clinical practice. In this article, we review the pathophysiology of myocardial blood flow and myocardial flow reserve, and the initial data available from single photon emission computed tomography myocardial blood flow and myocardial flow reserve evaluation; we also discuss potential limitations to the wider implementation of flow evaluation in single photon emission computed tomography.

Myocardial Flow Reserve Measurement During CZT-SPECT Perfusion Imaging for Coronary Artery Disease Screening: Correlation With Clinical Findings and Invasive Coronary Angiography-The CFR-OR Study.

Purpose: The aim of this study was to assess the results of cadmium zinc telluride (CZT)- single-photon emission computed tomography (SPECT) myocardial flow reserve (MFR) in coronary artery disease (CAD) screening regarding clinical risk and its correlation to invasive coronary angiography (ICA). Methods: A total of 137 patients (61 male and 76 female) referred for CAD screening myocardial perfusion imaging (MPI) between November 2018 and April 2020 were included in the CFR-OR prospective trial. The 10-year risk of cardiovascular death according to the European Society of Cardiology (SCORE) was calculated. SPECT 1-day 99mTc-tetrofosmin protocol was acquired on CZT cardiac-dedicated pinhole cameras. Low-dose thoracic CT was used for coronary calcium score (CCS) evaluation. ICA, when performed within 3 months, was also analyzed. Results: Mean SCORE and mean global MFR were, respectively, 4 ± 3.1% and 2.50 ± 0.74; 34 patients had impaired CFR (using a threshold of 2). There was a significant inverse correlation between MFR and SCORE (p = 0.006), gender (p = 0.019), and number of cardiovascular risk factors (p = 0.01). MFR was significantly reduced in patients with CCS above 1 (p = 0.01). No significant correlation was found between MFR and individual cardiovascular risk factors (dyslipidemia, hypertension, diabetes, or family history of CAD). A total of 23 patients underwent ICA. Global MFR SPECT sensitivity and specificity were 83.3 and 100 %, respectively, with an area under the curve of 0.94. Conclusion: Adding MFR to SPECT MPI for CAD screening on CZT camera may contribute to high-risk patient identification and enhance diagnostic performances. MFR could help physician decision to perform ICA.

Impact of attenuation correction for CZT-SPECT measurement of myocardial blood flow.

OBJECTIVES: Most of cardiac dedicated CZT-SPECT systems are not equipped with CT, whereas PET systems are. We evaluated the impact of AC correction on CZT-SPECT myocardial blood flow (MBF) and myocardial flow reserve (MFR) measurements. METHODS: 104 patients were included. SPECT data were acquired on cadmium zinc telluride (CZT)-based pinhole cardiac camera in listmode using a stress (250 ± 17 MBq)/rest (511 ± 23 MBq) 1-day Tc-99m-tetrofosmin protocol. Low-dose CT was acquired on another SPECT/CT camera in the same position. All analysis was performed using Corridor4DM. RESULTS: Stress and rest MBF were significantly lower when AC was applied (P < 0.001). For regional and global MFR, there was no significant difference between AC and NAC measurements (P > 0.25 at least). Mean global LV MFR was 2.43 ± 0.87 and 2.33 ± 0.89, respectively, for NAC and AC measurements. Using a threshold of 2, 86 patients (83%) remained classified as normal and abnormal regarding global LV MFR whether AC was applied or not. Mean difference between NAC and AC values for the 18 other patients was 0.3. CONCLUSION: AC correction does not significantly affect MFR measurement both in regional and global LV analyses.