Towards standardization of absolute SPECT/CT quantification: a multi-center and multi-vendor phantom study.

Unlabelled: Absolute quantification of radiotracer distribution using SPECT/CT imaging is of great importance for dosimetry aimed at personalized radionuclide precision treatment. However, its accuracy depends on many factors. Using phantom measurements, this multi-vendor and multi-center study evaluates the quantitative accuracy and inter-system variability of various SPECT/CT systems as well as the effect of patient size, processing software and reconstruction algorithms on recovery coefficients (RC).

PET-Based Human Dosimetry of Ga-NODAGA-Exendin-4, a Tracer for β-Cell Imaging.

Ga-NODAGA-exendin-4 is a promising tracer for β-cell imaging using PET/CT. Possible applications include preoperative visualization of insulinomas and discrimination between focal and diffuse forms of congenital hyperinsulinism. There is also a significant role for this tracer in extending our knowledge on the role of β-cell mass in the pathophysiology of type 1 and type 2 diabetes by enabling noninvasive quantification of tracer uptake as a measure for β-cell mass.

Metabolic Subtyping of Pheochromocytoma and Paraganglioma by F-FDG Pharmacokinetics Using Dynamic PET/CT Scanning.

Static single-time-frame F-FDG PET/CT is useful for the localization and functional characterization of pheochromocytomas and paragangliomas (PPGLs). F-FDG uptake varies between PPGLs with different genotypes, and the highest SUVs are observed in cases of succinate dehydrogenase () mutations, possibly related to enhanced aerobic glycolysis in tumor cells. The exact determinants of F-FDG accumulation in PPGLs are unknown.

Improving the Spatial Alignment in PET/CT Using Amplitude-Based Respiration-Gated PET and Patient-Specific Breathing-Instructed CT.

Appropriate attenuation correction is important for accurate quantification of SUVs in PET. Patient respiratory motion can introduce a spatial mismatch between respiration-gated PET and CT, reducing quantitative accuracy. In this study, the effect of a patient-specific breathing-instructed CT protocol on the spatial alignment between CT and amplitude-based optimal respiration-gated PET images was investigated.

Quantification, improvement, and harmonization of small lesion detection with state-of-the-art PET.

In recent years, there have been multiple advances in positron emission tomography/computed tomography (PET/CT) that improve cancer imaging. The present generation of PET/CT scanners introduces new hardware, software, and acquisition methods. This review describes these new developments, which include time-of-flight (TOF), point-spread-function (PSF), maximum-a-posteriori (MAP) based reconstruction, smaller voxels, respiratory gating, metal artefact reduction, and administration of quadratic weight-dependent F-fluorodeoxyglucose (FDG) activity.

Metal Artifact Reduction of CT Scans to Improve PET/CT.

In recent years, different metal artifact reduction methods have been developed for CT. These methods have only recently been introduced for PET/CT even though they could be beneficial for interpretation, segmentation, and quantification of the PET/CT images. In this study, phantom and patient scans were analyzed visually and quantitatively to measure the effect on PET images of iterative metal artifact reduction (iMAR) of CT data.

Whole organ and islet of Langerhans dosimetry for calculation of absorbed doses resulting from imaging with radiolabeled exendin.

Radiolabeled exendin is used for non-invasive quantification of beta cells in the islets of Langerhans in vivo. High accumulation of radiolabeled exendin in the islets raised concerns about possible radiation-induced damage to these islets in man. In this work, islet absorbed doses resulting from exendin-imaging were calculated by combining whole organ dosimetry with small scale dosimetry for the islets.

A 3D-printed anatomical pancreas and kidney phantom for optimizing SPECT/CT reconstruction settings in beta cell imaging using In-exendin.

Background: Quantitative single photon emission computed tomography (SPECT) is challenging, especially for pancreatic beta cell imaging with In-exendin due to high uptake in the kidneys versus much lower uptake in the nearby pancreas. Therefore, we designed a three-dimensionally (3D) printed phantom representing the pancreas and kidneys to mimic the human situation in beta cell imaging. The phantom was used to assess the effect of different reconstruction settings on the quantification of the pancreas uptake for two different, commercially available software packages.

Tumor Delineation and Quantitative Assessment of Glucose Metabolic Rate within Histologic Subtypes of Non-Small Cell Lung Cancer by Using Dynamic F Fluorodeoxyglucose PET.

Purpose To assess whether dynamic fluorine 18 (F) fluorodeoxyglucose (FDG) positron emission tomography (PET) has added value over static F-FDG PET for tumor delineation in non-small cell lung cancer (NSCLC) radiation therapy planning by using pathology volumes as the reference standard and to compare pharmacokinetic rate constants of F-FDG metabolism, including regional variation, between NSCLC histologic subtypes. Materials and Methods The study was approved by the institutional review board. Patients gave written informed consent.

The Impact of Optimal Respiratory Gating and Image Noise on Evaluation of Intratumor Heterogeneity on 18F-FDG PET Imaging of Lung Cancer.

Unlabelled: Accurate measurement of intratumor heterogeneity using parameters of texture on PET images is essential for precise characterization of cancer lesions. In this study, we investigated the influence of respiratory motion and varying noise levels on quantification of textural parameters in patients with lung cancer.

Methods: We used an optimal-respiratory-gating algorithm on the list-mode data of 60 lung cancer patients who underwent F-FDG PET.

Performance of automatic image segmentation algorithms for calculating total lesion glycolysis for early response monitoring in non-small cell lung cancer patients during concomitant chemoradiotherapy.

Background And Purpose: This study evaluated the use of total lesion glycolysis (TLG) determined by different automatic segmentation algorithms, for early response monitoring in non-small cell lung cancer (NSCLC) patients during concomitant chemoradiotherapy.

Materials And Methods: Twenty-seven patients with locally advanced NSCLC treated with concomitant chemoradiotherapy underwent (18)F-fluorodeoxyglucose (FDG) PET/CT imaging before and in the second week of treatment. Segmentation of the primary tumours and lymph nodes was performed using fixed threshold segmentation at (i) 40% SUVmax (T40), (ii) 50% SUVmax (T50), (iii) relative-threshold-level (RTL), (iv) signal-to-background ratio (SBR), and (v) fuzzy locally adaptive Bayesian (FLAB) segmentation.

Comparison of Tumor Uptake Heterogeneity Characterization Between Static and Parametric 18F-FDG PET Images in Non-Small Cell Lung Cancer.

Unlabelled: (18)F-FDG PET is well established in the field of oncology for diagnosis and staging purposes and is increasingly being used to assess therapeutic response and prognosis. Many quantitative indices can be used to characterize tumors on (18)F-FDG PET images, such as SUVmax, metabolically active tumor volume (MATV), total lesion glycolysis, and, more recently, the proposed intratumor uptake heterogeneity features. Although most PET data considered within this context concern the analysis of activity distribution using images obtained from a single static acquisition, parametric images generated from dynamic acquisitions and reflecting radiotracer kinetics may provide additional information.

Performance of 3DOSEM and MAP algorithms for reconstructing low count SPECT acquisitions.

Purpose: Low count single photon emission computed tomography (SPECT) is becoming more important in view of whole body SPECT and reduction of radiation dose. In this study, we investigated the performance of several 3D ordered subset expectation maximization (3DOSEM) and maximum a posteriori (MAP) algorithms for reconstructing low count SPECT images.

Materials And Methods: Phantom experiments were conducted using the National Electrical Manufacturers Association (NEMA) NU2 image quality (IQ) phantom.

Tumor and red bone marrow dosimetry: comparison of methods for prospective treatment planning in pretargeted radioimmunotherapy.

Background: Red bone marrow (RBM) toxicity is dose-limiting in (pretargeted) radioimmunotherapy (RIT). Previous blood-based and two-dimensional (2D) image-based methods have failed to show a clear dose-response relationship. We developed a three-dimensional (3D) image-based RBM dosimetry approach using the Monte Carlo-based 3D radiobiological dosimetry (3D-RD) software and determined its additional value for predicting RBM toxicity.

The impact of respiratory gated positron emission tomography on clinical staging and management of patients with lung cancer.

Objectives: Respiratory motion artefacts during positron emission tomography (PET) deteriorate image quality, potentially introducing diagnostic uncertainties. The objective of this study was to determine the impact of optimal respiratory gating on clinical staging and management of patients with primary lung cancer.

Materials And Methods: From our fast-track outpatient diagnostic program, 55 patients with primary lung cancer, who underwent whole body [(18)F]-fluorodeoxyglucose (FDG) PET, were included.

Improving the Spatial Alignment in PET/CT Using Amplitude-Based Respiration-Gated PET and Respiration-Triggered CT.

Unlabelled: Respiratory motion during PET can cause inaccuracies in the quantification of radiotracer uptake, which negatively affects PET-guided radiotherapy planning. Quantitative accuracy can be improved by respiratory gating. However, additional miscalculation of standardized uptake value (SUV) in PET images can be caused by inappropriate attenuation correction due to a spatial mismatch between gated PET and CT.

PET in the management of locally advanced and metastatic NSCLC.

Despite considerable improvements in the treatment options for advanced-stage non-small-cell lung cancer (NSCLC), disease-specific survival remains poor. With the aim of improving patient outcome, the treatment paradigm of locally advanced NSCLC has shifted from solely radiotherapy towards combined and intensified treatment approaches. Also, treatment for patients with stage IV (oligo)metastatic NSCLC has evolved rapidly, with therapeutic options that include a number of targeted agents, surgery, and stereotactic ablative radiotherapy.

Muscle Activity during Walking Measured Using 3D MRI Segmentations and [18F]-Fluorodeoxyglucose in Combination with Positron Emission Tomography.

Purpose: This study aimed to determine the contribution of each muscle of the lower limb to walking using positron emission tomography (PET) with [F]-fluorodeoxyglucose (FDG). Furthermore, we compared our results obtained using volumetric analysis of entire muscles with those obtained using a more traditional approach considering the uptake in only one slice in each segment.

Methods: Ten healthy subjects walked on a treadmill at self-selected comfortable walking speed for 90 min, 60 min before and 30 min after intravenous injection of 50-MBq FDG.

Comparison of a free-breathing CT and an expiratory breath-hold CT with regard to spatial alignment of amplitude-based respiratory-gated PET and CT images.

Unlabelled: Respiratory motion during PET has a significant effect on the quantification of radiotracer uptake in PET images. Even when respiratory motion is considered using PET gating techniques, inaccuracies in standardized uptake values can be caused by inappropriate attenuation correction due to a spatial mismatch between PET and CT. In this study, the effect of breath-hold CT imaging on the spatial match between CT and amplitude-based respiratory-gated PET images is investigated.

Amplitude-based optimal respiratory gating in positron emission tomography in patients with primary lung cancer.

Objectives: Respiratory motion during PET imaging introduces quantitative and diagnostic inaccuracies, which may result in non-optimal patient management. This study investigated the effects of respiratory gating on image quantification using an amplitude-based optimal respiratory gating (ORG) algorithm.

Methods: Whole body FDG-PET/CT was performed in 66 lung cancer patients.

Predictive patient-specific dosimetry and individualized dosing of pretargeted radioimmunotherapy in patients with advanced colorectal cancer.

Purpose: Pretargeted radioimmunotherapy (PRIT) with bispecific antibodies (bsMAb) and a radiolabeled peptide reduces the radiation dose to normal tissues. Here we report the accuracy of an (111)In-labeled pretherapy test dose for personalized dosing of (177)Lu-labeled IMP288 following pretargeting with the anti-CEA × anti-hapten bsMAb, TF2, in patients with metastatic colorectal cancer (CRC).

Methods: In 20 patients bone marrow absorbed doses (BMD) and doses to the kidneys were predicted based on blood samples and scintigrams acquired after (111)In-IMP288 injection for individualized dosing of PRIT with (177)Lu-IMP288.

Comparison of liver SUV using unenhanced CT versus contrast-enhanced CT for attenuation correction in (18)F-FDG PET/CT.

Aim: The aim of the study was to compare standardized uptake values (SUVs) in liver tissue obtained using whole-body unenhanced low-dose computed tomography (CT) with those obtained using contrast-enhanced high-dose CT for PET attenuation correction in PET/CT scanning.

Materials And Methods: Ten patients scheduled for (18)F-FDG PET and contrast-enhanced CT of the abdomen were included in this study. PET data were corrected for attenuation using both unenhanced low-dose CT images and contrast-enhanced high-dose CT images.

Multicenter harmonization of 89Zr PET/CT performance.

Unlabelled: This study investigated the feasibility of quantitative accuracy and harmonized image quality in (89)Zr-PET/CT multicenter studies.

Methods: Five PET/CT scanners from 3 vendors were included. (89)Zr activity was measured in a central dose calibrator before delivery.