First clinical experience of a ring-configured cadmium zinc telluride camera: A comparative study versus conventional gamma camera systems.

Background: A novel semiconductor cadmium zinc telluride (CZT) gamma camera system using a block sequential regularized expectation maximization (BSREM) reconstruction algorithm is now clinically available. Here we investigate how a multi-purpose ring-configurated CZT system can be safely applied in clinics and describe the initial optimization process.

Method: Seventy-six patients (bone-, cardiac- and lung scan) were scanned on a conventional gamma camera (planar and/or single-photon emission computed tomography [SPECT]/SPECT-CT) used in clinical routine and on the ring-configurated CZT camera Starguide (GE Healthcare).

PET/CT imaging 2 h after injection of [F]PSMA-1007 can lead to higher staging of prostate cancer than imaging after 1 h.

Background: [F]PSMA-1007 is a prostate specific membrane antigen (PSMA) ligand for positron emission tomography (PET) imaging of prostate cancer. Current guidelines recommend imaging 90-120 min after injection but strong data about optimal timing is lacking. Our aim was to study whether imaging after 1 h and 2 h leads to a different number of detected lesions, with a specific focus on lesions that might lead to a change in treatment.

Diagnostic accuracy for CZT gamma camera compared to conventional gamma camera technique with myocardial perfusion single-photon emission computed tomography: Assessment of myocardial infarction and function.

Background: The solid-state cadmium-zinc-telluride (CZT) gamma camera for myocardial perfusion single-photon emission computed tomography (MPS) has theoretical advantages compared to the conventional gamma camera technique. This includes more sensitive detectors and better energy resolution. We aimed to explore the diagnostic performance of gated MPS with a CZT gamma camera compared to a conventional gamma camera for detection of myocardial infarct (MI) and assessment of left ventricular (LV) volumes and ejection fraction (LVEF), using cardiac magnetic resonance (CMR) as the reference method.

Biokinetics and dosimetry of F-PSMA-1007 in patients with prostate cancer.

Purpose: Positron emission tomography-computed tomography (PET-CT) using prostate-specific membrane antigen (PSMA) ligands is a method for imaging prostate cancer. A recent tracer, F-PSMA-1007, offers advantages concerning production and biokinetics compared to the standard tracer ( Ga-PSMA-11). Until now, radiation dosimetry data for this ligand was limited to the material of three healthy volunteers.

Detection of lymph node metastases in patients with prostate cancer: Comparing conventional and digital [ F]-fluorocholine PET-CT using histopathology as a reference.

Background: Positron emission tomography-computed tomography (PET-CT) with [ F]-fluorocholine (FCH) is used to detect and stage metastatic lymph nodes in patients with prostate cancer. Improvements to hardware and software have recently been made. We compared the capability of detecting regional lymph node metastases using conventional and digital silicon photomultiplier (SiPM)-based PET-CT technology for FCH.

Head-to-head comparison of a Si-photomultiplier-based and a conventional photomultiplier-based PET-CT system.

Background: A novel generation of PET scanners based on silicon (Si)-photomultiplier (PM) technology has recently been introduced. Concurrently, there has been development of new reconstruction methods aimed at increasing the detectability of small lesions without increasing image noise. The combination of new detector technologies and new reconstruction algorithms has been found to increase image quality.

Image reconstruction methods affect software-aided assessment of pathologies of [F]flutemetamol and [F]FDG brain-PET examinations in patients with neurodegenerative diseases.

Purpose: To assess how some of the new developments in brain positron emission tomography (PET) image reconstruction affect quantitative measures and software-aided assessment of pathology in patients with neurodegenerative diseases.

Methods: PET data were grouped into four cohorts: prodromal Alzheimer's disease patients and controls receiving [F]flutemetamol, and neurodegenerative disease patients and controls receiving [F]FDG PET scans. Reconstructed images were obtained by ordered-subsets expectation maximization (OSEM; 3 iterations (i), 16/34 subsets (s), 3/5-mm filter, ±time-of-flight (TOF), ±point-spread function (PSF)) and block-sequential regularized expectation maximization (BSREM; TOF, PSF, β-value 75-300).

Optimization of [F]PSMA-1007 PET-CT using regularized reconstruction in patients with prostate cancer.

Background: Prostate-specific membrane antigen (PSMA) radiotracers such as [F]PSMA-1007 used with positron emission tomography-computed tomography (PET-CT) is promising for initial staging and detection of recurrent disease in prostate cancer patients. The block-sequential regularization expectation maximization algorithm (BSREM) is a new PET reconstruction algorithm, which provides higher image contrast while also reducing noise. The aim of the present study was to evaluate the influence of different acquisition times and different noise-suppressing factors in BSREM (β values) in [F]PSMA-1007 PET-CT regarding quantitative data as well as a visual image quality assessment.

Appropriate coronary revascularization can be accomplished if myocardial perfusion is quantified by positron emission tomography prior to treatment decision.

Background: Many patients undergo percutaneous coronary intervention (PCI) without the use of non-invasive stress testing prior to treatment. The aim of this study was to determine the potential added value of guiding revascularization by quantitative assessment of myocardial perfusion prior to intervention.

Methods And Results: Thirty-three patients (10 females) with suspected or established CAD who had been referred for a clinical coronary angiography (CA) with possibility for PCI were included.

Comparison of conventional and Si-photomultiplier-based PET systems for image quality and diagnostic performance.

Background: A new generation of positron emission tomography with computed tomography (PET-CT) was recently introduced using silicon (Si) photomultiplier (PM)-based technology. Our aim was to compare the image quality and diagnostic performance of a SiPM-based PET-CT (Discovery MI; GE Healthcare, Milwaukee, WI, USA) with a time-of-flight PET-CT scanner with a conventional PM detector (Gemini TF; Philips Healthcare, Cleveland, OH, USA), including reconstruction algorithms per vendor's recommendations.

Methods: Imaging of the National Electrical Manufacturers Association IEC body phantom and 16 patients was carried out using 1.

Comparison between silicon photomultiplier-based and conventional PET/CT in patients with suspected lung cancer-a pilot study.

Background: Lung cancer is one of the most common cancers in the world. Early detection and correct staging are fundamental for treatment and prognosis. Positron emission tomography with computed tomography (PET/CT) is recommended clinically.

Impact of acquisition time and penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm on a Si-photomultiplier-based PET-CT system for F-FDG.

Background: Block-sequential regularized expectation maximization (BSREM), commercially Q. Clear (GE Healthcare, Milwaukee, WI, USA), is a reconstruction algorithm that allows for a fully convergent iterative reconstruction leading to higher image contrast compared to conventional reconstruction algorithms, while also limiting noise. The noise penalization factor β controls the trade-off between noise level and resolution and can be adjusted by the user.

Impact of penalizing factor in a block-sequential regularized expectation maximization reconstruction algorithm for F-fluorocholine PET-CT regarding image quality and interpretation.

Background: Recently, the block-sequential regularized expectation maximization (BSREM) reconstruction algorithm was commercially introduced (Q.Clear, GE Healthcare, Milwaukee, WI, USA). However, the combination of noise-penalizing factor (β), acquisition time, and administered activity for optimal image quality has not been established for F-fluorocholine (FCH).

Qualitative assessments of myocardial ischemia by cardiac MRI and coronary stenosis by invasive coronary angiography in relation to quantitative perfusion by positron emission tomography in patients with known or suspected stable coronary artery disease.

Background: To relate findings of qualitative evaluation of first-pass perfusion-CMR and anatomical evaluation on coronary angiography (CA) to the reference standard of quantitative perfusion, cardiac PET, in patients with suspected or known stable coronary artery disease (CAD).

Methods And Results: Forty-one patients referred for CA due to suspected stable CAD, prospectively performed adenosine stress/rest first-pass perfusion-CMR as well as N-NH PET on the same day, 4 ± 3 weeks before CA. Angiographers were blinded to PET and CMR results.

Differences in attenuation pattern in myocardial SPECT between CZT and conventional gamma cameras.

Background: In myocardial perfusion imaging (MPI), single-photon emission tomography (SPECT) soft-tissue attenuation by the abdomen, breasts, and lateral chest wall may create artifacts that mimic true perfusion defects. This may cause misdiagnosis of myocardial perfusion. The aim of the present study was to compare the localization, extent, and depth of attenuation artifacts in MPI SPECT for a multi-pinhole cadmium zinc telluride (CZT) camera vs a conventional gamma camera.

Fully quantitative cardiovascular magnetic resonance myocardial perfusion ready for clinical use: a comparison between cardiovascular magnetic resonance imaging and positron emission tomography.

Background: Recent studies have shown that quantification of myocardial perfusion (MP) at stress and myocardial perfusion reserve (MPR) offer additional diagnostic and prognostic information compared to qualitative and semi-quantitative assessment of myocardial perfusion distribution in patients with coronary artery disease (CAD). Technical advancements have enabled fully automatic quantification of MP using cardiovascular magnetic resonance (CMR) to be performed in-line in a clinical workflow. The aim of this study was to validate the use of the automated CMR perfusion mapping technique for quantification of MP using 13N-NH3 cardiac positron emission tomography (PET) as the reference method.

The radiation dose to overweighted patients undergoing myocardial perfusion SPECT can be significantly reduced: validation of a linear weight-adjusted activity administration protocol.

Background: Large body size can cause a higher proportion of emitted photons being attenuated within the patient. Therefore, clinical myocardial perfusion SPECT (MPS) protocols often include unproportionally higher radioisotope activity to obese patients. The aim was to evaluate if a linear weight-adjusted low-dose protocol can be applied to obese patients and thereby decrease radiation exposure.

Importance of correct patient positioning in myocardial perfusion SPECT when using a CZT camera.

Introduction: Myocardial perfusion single photon emission computed tomography (MPS) is one of the most widely used diagnostic methods in patients with suspected ischemic heart disease (IHD). Recently, a novel technique based on cadmium-zinc-telluride (CZT) detectors, pinhole collimators, and a stationary gantry was introduced for MPS. The aim of this work was to investigate how patient positioning affects the reconstructed MPS images using this novel technique.

Reduced administered activity, reduced acquisition time, and preserved image quality for the new CZT camera.

Background: For a 1-day myocardial perfusion SPECT (MPS) the recommendations for administered activity stated in the EANM guidelines results in an effective dose of up to 16 mSv per patient. Recently, a gamma camera system, based on cadmium zinc telluride (CZT) technology, was introduced. This technique has the potential to reduce the effective dose and scan time compared to the conventional NaI gamma camera.

Evaluation of image reconstruction methods for (123)I-MIBG-SPECT: a rank-order study.

Background: There is an opportunity to improve the image quality and lesion detectability in single photon emission computed tomography (SPECT) by choosing an appropriate reconstruction method and optimal parameters for the reconstruction.

Purpose: To optimize the use of the Flash 3D reconstruction algorithm in terms of equivalent iteration (EI) number (number of subsets times the number of iterations) and to compare with two recently developed reconstruction algorithms ReSPECT and orthogonal polynomial expansion on disc (OPED) for application on (123)I-metaiodobenzylguanidine (MIBG)-SPECT.

Material And Methods: Eleven adult patients underwent SPECT 4 h and 14 patients 24 h after injection of approximately 200 MBq (123)I-MIBG using a Siemens Symbia T6 SPECT/CT.

Inhomogeneous activity distribution of 177Lu-DOTA0-Tyr3-octreotate and effects on somatostatin receptor expression in human carcinoid GOT1 tumors in nude mice.

The aim of this study was to investigate the activity distribution in neouroendocrine tumors after diagnostic, or therapeutic, amounts of [(177)Lu-DOTA(0)-Tyr(3)]-octreotate and to investigate how the activity distribution influences the absorbed dose. Furthermore, the activity distribution of a second administration of radiolabeled octreotate was studied. Nude mice with subcutaneously grown human midgut carcinoid (GOT1) were injected intravenously with different amounts of (177)Lu-octreotate.

Radiation induces up-regulation of somatostatin receptors 1, 2, and 5 in small cell lung cancer in vitro also at low absorbed doses.

Background: Radiation can be used to up-regulate the expression of the somatostatin receptor (sstr) subtype 2 in small cell lung cancer (SCLC) cells at absorbed doses of 2-8 Gy. Increased sstr expression results in increased binding of radiolabeled somatostatin analogs to the tumor cell, which enhances the efficacy of systemic radionuclide therapy. The aim of this study was to determine if lower absorbed doses could up-regulate sstr2 expression, and possibly influence other sstr subtypes.

Effects of treatment with (177)Lu-DOTA-Tyr(3)-octreotate on uptake of subsequent injection in carcinoid-bearing nude mice.

Purpose: The aim of this study was to analyze the effect therapeutic injections of (177)Lu-DOTA(0)-Tyr(3)]-octreotate (DOTATATE) had on the tumor uptake of a subsequent injection with (111)In-DOTATATE in GOT1-bearing nude mice.

Methods And Materials: Nude mice, xenografted with the human midgut carcinoid, GOT1, were first intravenously injected with a curative (30 MBq) or a suboptimal (7.5 MBq) amount of (177)Lu-DOTATATE.

Radiation-induced up-regulation of somatostatin receptor expression in small cell lung cancer in vitro.

Background: The internalization of radiolabeled somatostatin analogs into tumor cells is of great importance for radionuclide therapy. It has previously been shown that some radiolabeled somatostatin analogs are internalized through receptor-mediated endocytosis. The development of methods that increase the number of receptors on tumor cells is important to further improve the internalization of radionuclides.