Performance evaluation of a preclinical SPECT/CT system for multi-animal and multi-isotope quantitative experiments.

The aim was to study the performance of the U-SPECT/CT E-class system for preclinical imaging, to later demonstrate the viability of simultaneous multi-animal and multi-isotope imaging with reliable quantitative accuracy. The performance of the SPECT was evaluated for two collimators dedicated for mouse (UHS-M) and rat imaging (UHR-RM) in terms of sensitivity, energy resolution, uniformity and spatial resolution. Point sources, hot‑rod and uniform phantoms were scanned, and additional tests were carried out to evaluate singular settings such as simultaneous multi-isotope acquisition and imaging with a multi-bed system.

Early Imaging and Molecular Changes with Neoadjuvant Bevacizumab in Stage II/III Breast Cancer.

This prospective, phase II study evaluated novel biomarkers as predictors of response to bevacizumab in patients with breast cancer (BC), using serial imaging methods and gene expression analysis. Patients with primary stage II/III BC received bevacizumab 15 mg/kg (cycle 1; C1), then four cycles of neoadjuvant docetaxel doxorubicin, and bevacizumab every 3 weeks (C2-C5). Tumour proliferation and hypoxic status were evaluated using F-fluoro-3'-deoxy-3'-L-fluorothymidine (FLT)- and F-fluoromisonidazole (FMISO)-positron emission tomography (PET) at baseline, and during C1 and C5.

Ultra-low dose whole-body CT for attenuation correction in a dual tracer PET/CT protocol for multiple myeloma.

Purpose: To investigate within phantoms the minimum CT dose allowed for accurate attenuation correction of PET data and to quantify the effective dose reduction when a CT for this purpose is incorporated in the clinical setting.

Methods: The NEMA image quality phantom was scanned within a large parallelepiped container. Twenty-one different CT images were acquired to correct attenuation of PET raw data.

Impact of the dosimetry approach on the resulting Y radioembolization planned absorbed doses based on Tc-MAA SPECT-CT: is there agreement between dosimetry methods?

Background: Prior radioembolization, a simulation using Tc-macroaggregated albumin as Y-microspheres surrogate is performed. Gamma scintigraphy images (planar, SPECT, or SPECT-CT) are acquired to evaluate intrahepatic Y-microspheres distribution and detect possible extrahepatic and lung shunting. These images may be used for pre-treatment dosimetry evaluation to calculate the Y activity that would get an optimal tumor response while sparing healthy tissues.

Image quality evaluation in a modern PET system: impact of new reconstructions methods and a radiomics approach.

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.

Phantom, clinical, and texture indices evaluation and optimization of a penalized-likelihood image reconstruction method (Q.Clear) on a BGO PET/CT scanner.

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.

Significant dose reduction is feasible in FDG PET/CT protocols without compromising diagnostic quality.

Purpose: To reduce the radiation dose to patients by optimizing oncological FDG PET/CT protocols.

Methods: The baseline PET/CT protocol in our institution for oncological PET/CT examinations consisted of the administration of 5.18 MBq/kg of FDG and a CT acquisition with a reference current-time product of 120 mAs.

[Ionizing radiation received by patients with osteosarcoma during intra-arterial chemotherapy treatment].

Background: Osteosarcoma paediatric patients are usually treated with intra-arterial chemotherapy (QTia) which is admi-nistered directly to the tumour. This procedure exposes patients to ionizing radiation. Paediatric patients are especially sensitive to this exposure.

Effective dose estimation for oncological and neurological PET/CT procedures.

Background: The aim of this study was to retrospectively evaluate the patient effective dose (ED) for different PET/CT procedures performed with a variety of PET radiopharmaceutical compounds. PET/CT studies of 210 patients were reviewed including Torso (n = 123), Whole body (WB) (n = 36), Head and Neck Tumor (HNT) (n = 10), and Brain (n = 41) protocols with FDG (n = 170), C-CHOL (n = 10), FDOPA (n = 10), C-MET (n = 10), and F-florbetapir (n = 10). ED was calculated using conversion factors applied to the radiotracer activity and to the CT dose-length product.

Performance Characteristics of the Whole-Body Discovery IQ PET/CT System.

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. 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.

Radiation dose produced by patients during radiopharmaceutical incorporation in nuclear medicine diagnostic procedures.

Objectives: The aim of this study was to assess the dose received by members of the public due to close contact with patients undergoing nuclear medicine procedures during radiopharmaceutical incorporation, and comparing it with the emitted radiation dose when the test was complete, in order to establish recommendations.

Material And Methods: A prospective study was conducted on 194 patients. H*(10) dose rates were measured at 0.

Radiation dosimetry and biodistribution in non-human primates of the sodium/iodide PET ligand [(18)F]-tetrafluoroborate.

Background: [(18)F]-tetrafluoroborate is a PET radiotracer taken up by the sodium/iodide symporter (NIS). Albeit the in vivo behavior in rodents is similar to the (99m)Tc-pertechnetate, no studies exist in primates or in humans. The aims of this study were to evaluate the biodistribution of [(18)F]-tetrafluoroborate in non-human primates with PET and to estimate the absorbed dose in organs.

Brain PET imaging optimization with time of flight and point spread function modelling.

Purpose: To assess the influence of reconstruction algorithms and parameters on the PET image quality of brain phantoms in order to optimize reconstruction for clinical PET brain studies in a new generation PET/CT.

Methods: The 3D Hoffman phantom that simulates (18)F-fluorodeoxyglucose (FDG) distribution was imaged in a Siemens Biograph mCT TrueV PET/CT with Time of Flight (TOF) and Point Spread Function (PSF) modelling. Contrast-to-Noise Ratio (CNR), contrast and noise were studied for different reconstruction models: OSEM, OSEM + TOF, OSEM + PSF and OSEM + PSF + TOF.

Lessons from 11C-dihydrotetrabenazine imaging in a xenograft mouse model of rat insulinoma: is PET imaging of pancreatic beta cell mass feasible?

Background: The feasibility of beta cell mass (BCM) imaging and quantification with positron emission tomography (PET) in the pancreas is controversial. In an effort to shed some light on this topic, we have used a xenograft model of rat insulinoma (RIN) in mice, mimicking an intramuscular islet transplantation situation.

Methods: A total of 105 RIN cells were subcutaneously implanted in nude mice (N.

PET optimization for improved assessment and accurate quantification of 90Y-microsphere biodistribution after radioembolization.

Purpose: 90Y-microspheres are widely used for the radioembolization of metastatic liver cancer or hepatocellular carcinoma and there is a growing interest for imaging 90Y-microspheres with PET. The aim of this study is to evaluate the performance of a current generation PET/CT scanner for 90Y imaging and to optimize the PET protocol to improve the assessment and the quantification of 90Y-microsphere biodistribution after radioembolization.

Methods: Data were acquired on a Biograph mCT-TrueV scanner with time of flight (TOF) and point spread function (PSF) modeling.

[¹⁸F]fluorothymidine-positron emission tomography in patients with locally advanced breast cancer under bevacizumab treatment: usefulness of different quantitative methods of tumor proliferation.

Objectives: To investigate quantitative methods of tumor proliferation using 3'-[(18)F]fluoro-3'-deoxythymidine ([(18)F]FLT) PET in patients with breast cancer (BC), studied before and after one bevacizumab administration, and to correlate the [(18)F]FLT-PET uptake with the Ki67 index.

Material And Methods: Thirty patients with newly diagnosed, untreated BC underwent a [(18)F]FLT-PET before and 14 days after bevacizumab treatment. A dynamic scan centered over the tumor began simultaneously with the injection of [(18)F]FLT (385 ± 56 MBq).

A method for multichannel dosimetry with EBT3 radiochromic films.

Purpose: An improved method for multichannel dosimetry is presented. This method explicitly takes into account the information provided by the unexposed image of the film.

Methods: The method calculates the dose by applying a couple of perturbations to the scanned dose, one dependent and the other independent on the color channel.

Application of spherical diodes for megavoltage photon beams dosimetry.

Purpose: External beam radiation therapy (EBRT) usually uses heterogeneous dose distributions in a given volume. Designing detectors for quality control of these treatments is still a developing subject. The size of the detectors should be small to enhance spatial resolution and ensure low perturbation of the beam.

[Validation of segmentation techniques for positron emission tomography using ex-vivo images of oncological surgical specimens].

Objective: To design a novel ex-vivo acquisition technique to establish a common framework to validate different segmentation techniques for oncological PET images. To evaluate several automatic segmentation algorithms on this set of images.

Material And Methods: In 15 patients with cancer, ex-vivo PET studies of surgical specimens removed during surgery were performed after injection of (18)F-FDG.

Automated analysis of FDG PET as a tool for single-subject probabilistic prediction and detection of Alzheimer's disease dementia.

Purpose: To introduce, evaluate and validate a voxel-based analysis method of ¹⁸F-FDG PET imaging for determining the probability of Alzheimer's disease (AD) in a particular individual.

Methods: The subject groups for model derivation comprised 80 healthy subjects (HS), 36 patients with mild cognitive impairment (MCI) who converted to AD dementia within 18 months, 85 non-converter MCI patients who did not convert within 24 months, and 67 AD dementia patients with baseline FDG PET scan were recruited from the AD Neuroimaging Initiative (ADNI) database. Additionally, baseline FDG PET scans from 20 HS, 27 MCI and 21 AD dementia patients from our institutional cohort were included for model validation.

Impact of time-of-flight and point-spread-function in SUV quantification for oncological PET.

Background: Accuracy in the quantification of the SUV is a critical point in PET because proper quantification of tumor uptake is essential for therapy monitoring and prognosis evaluation. Recent advances such as time-of-flight (TOF) and point-spread-function (PSF) reconstructions have dramatically improved detectability. However, first experiences with these techniques have shown a consistent tendency to measure markedly high SUV values, bewildering nuclear medicine physicians and referring clinicians.

[Contribution of time of flight and point spread function modeling to the performance characteristics of the PET/CT Biograph mCT scanner].

Objective: To characterize the performance of the Biograph mCT PET/CT TrueV scanner with time of flight (TOF) and point spread function (PSF) modeling.

Material And Methods: The PET/CT scanner combines a 64-slice CT and PET scanner that incorporates in the reconstruction the TOF and PSF information. PET operating characteristics were evaluated according to the standard NEMA NU 2-2007, expanding some tests.

PET Tracers for Clinical Imaging of Breast Cancer.

Molecular imaging of breast cancer has undoubtedly permitted a substantial development of the overall diagnostic accuracy of this malignancy in the last years. Accurate tumour staging, design of individually suited therapies, response evaluation, early detection of recurrence and distant lesions have also evolved in parallel with the development of novel molecular imaging approaches. In this context, positron emission tomography (PET) can be probably seen as the most interesting molecular imaging technology with straightforward clinical application for such purposes.