Ivo Florian Rausch

• Priv. Doz. Dipl.-Ing., PhD
• Medical University of Vienna

Purpose Multidrug resistance-associated proteins (MRPs) have a widespread tissue distribution. They play an important role in drug disposition and drug-drug interactions (DDIs) and have been associated with various diseases. PET with 6-bromo-7-[¹¹C]methylpurine ([¹¹C]BMP) has been used to assess MRP1 function in the brain and lungs of mice. [¹¹C]BM...

Aim The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) provides an innovation leap in the use of fertilized chicken eggs (in ovo model) in preclinical imaging as PET/MRI enables the investigation of the chick embryonal organ-specific distribution of PET-tracers. However, hybrid PET/MRI inheres technical chall...

The design, fabrication, assembly and testing of a modular dynamic torso phantom for magnetic resonance imaging (MRI) is presented. The phantom is composed of fully MRI-compatible materials and consists of a saline-filled acrylic shell, with dimensions comparable to a human torso, and three distinct interior motion modules. Two linear piezo stages...

Background Accurate pharmacokinetic modelling in PET necessitates measurements of an input function, which ideally is acquired non-invasively from image data. For hepatic pharmacokinetic modelling two input functions need to be considered, to account for the blood supply from the hepatic artery and portal vein. Image-derived measurements at the por...

Background P-glycoprotein (P-gp) is an efflux transporter which is abundantly expressed at the blood-brain barrier (BBB) and which has been implicated in the pathophysiology of various brain diseases. The radiolabelled antiemetic drug [¹¹C]metoclopramide is a P-gp substrate for positron emission tomography (PET) imaging of P-gp function at the BBB....

Purpose Multidrug resistance-associated protein 1 (MRP1) is a transport protein with a widespread tissue distribution, which has been implicated in the pathophysiology of Alzheimer’s and chronic respiratory disease. PET with 6-bromo-7-[¹¹C]methylpurine ([¹¹C]BMP) has been used to measure MRP1 function in rodents. In this study, [¹¹C]BMP was for the...

Background Approaches targeting the sodium-glucose cotransporter (SGLT) could represent a promising future therapeutic strategy for numerous oncological and metabolic diseases. In this study, we evaluated the safety, biodistribution and radiation dosimetry of the glucose analogue positron emission tomography (PET) agent [¹⁸F] labeled alpha-methyl-4...

St. John's wort (SJW) extract, a herbal medicine with antidepressant effects, is a potent inducer of intestinal and/or hepatic cytochrome P450 (CYP) enzymes and P‐glycoprotein (P‐gp), which can cause clinically relevant drug interactions. It is currently not known whether SJW can also induce P‐gp activity at the human blood–brain barrier (BBB), whi...

To investigate the use of kinetic parameters derived from direct Patlak reconstructions of [68Ga]Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) to predict the histological grade of malignancy of the primary tumor of patients with prostate cancer (PCa). Thirteen patients (mean age 66 ± 10 years) with a primary, therapy-naïve PC...

Background Total-body PET scanners with axial field of views (FOVs) longer than 1 m enable new applications to study multiple organs (e.g., the brain-gut-axis) simultaneously. As the spatial resolution and the associated partial volume effect (PVE) can vary significantly along the FOV, detailed knowledge of the contrast recovery coefficients (CRCs)...

Objectives: Advanced MR imaging of brain tumors is still mainly based on qualitative imaging. PET imaging offers additive metabolic information, and MR fingerprinting (MRF) offers a novel approach to quantitative data acquisition. The purpose of this study was to evaluate the ability of MRF to predict tumor regions and grading in combination with...

Introduction: Dynamic positron emission tomography (PET) and the application of kinetic models can provide important quantitative information based on its temporal information. This however requires arterial blood sampling, which can be challenging to acquire. Nowadays, state-of-the-art PET/CT systems offer fully automated, whole-body (WB) kinetic...

The nervous and circulatory system interconnects the various organs of the human body, building hierarchically organized subsystems, enabling fine-tuned, metabolically expensive brain-body and inter-organ crosstalk to appropriately adapt to internal and external demands. A deviation or failure in the function of a single organ or subsystem could tr...

The aim of the study was to evaluate the effect of reduced injected [18F]FDG activity levels on the quantitative and diagnostic accuracy of PET images of patients with non-lesional epilepsy (NLE). Nine healthy volunteers and nine patients with NLE underwent 60-min dynamic list-mode (LM) scans on a fully-integrated PET/MRI system. Injected FDG activ...

Introduction Amino-acid positron emission tomography (PET) is a validated metabolic imaging approach for the diagnostic work-up of gliomas. This study aimed to evaluate sex-specific radiomic characteristics of L-[S-methyl- ¹¹ Cmethionine (MET)-PET images of glioma patients in consideration of the prognostically relevant biomarker isocitrate dehydro...

This article presents the protocol on Quality Controls in PET/CT and PET/MRI published online in May 2022 by the European Federation of Organisations for Medical Physics (EFOMP), which was developed by the Working group for PET/CT and PET/MRI Quality Control (QC) protocol. The main objective of this protocol was to comprehensively provide simple an...

Aim Recently, total-body PET/CT systems with an extended axial field-of-view (aFOV) became commercially available which allow acquiring physiologic information of multiple organs simultaneously. However, the nominal aFOV may clinically not be used effectively due to the inherently reduced sensitivity at the distal ends of the aFOV. The aim of this...

Aim/Introduction: Patient head motion poses a significant challenge when performing dynamic PET brain studies. In response, we developed a fast, robust, easily implementable and tracer-independent brain motion correction technique that facilitates accurate alignment of dynamic PET images. Materials and methods: Correction of head motion was perform...

Aim: The aim of this study was to assess the effects of including somatostatin receptor agonist (SSTR) PET imaging in meningioma radiotherapy planning by means of changes in inter-observer variability (IOV). Further, the possibility of using threshold-based delineation approaches for semiautomatic tumor volume definition was assessed. Patients and...

Background New approaches for 7 Tesla magnetic resonance spectroscopic imaging (MRSI) allow the simultaneous imaging of multiple neuro-oncological biomarkers with 3-4 mm resolution in clinically feasible measurement times. Specifically, the amino acids glutamine (Gln) and Glycine (Gly), were previously limited to single voxel detection at lower fie...

Background The NMDA receptor (NMDAR) plays a key role in the central nervous system, e.g., for synaptic transmission. While synaptic NMDARs are thought to have protective characteristics, activation of extrasynaptic NMDARs might trigger excitotoxic processes linked to neuropsychiatric disorders. Since extrasynaptic NMDARs are typically GluN2B-enric...

Aim To evaluate the effect of combining positron range correction (PRC) with point-spread-function (PSF) correction and to compare different methods of implementation into iterative image reconstruction for ¹²⁴I-PET imaging. Materials and methods Uniform PR blurring kernels of ¹²⁴I were generated using the GATE (GEANT4) framework in various materi...

Background Hybrid imaging (e.g., positron emission tomography [PET]/computed tomography [CT], PET/magnetic resonance imaging [MRI]) helps one to visualize and quantify morphological and physiological tumor characteristics in a single study. The noninvasive characterization of tumor heterogeneity is essential for grading, treatment planning, and fol...

The choice of materials challenges the development of Magnetic Resonance Imaging (MRI) phantoms and, to date, is mainly limited to water-filled compartments or gel-based components. Recently, solid materials have been introduced through additive manufacturing (AM) to mimic complex geometrical structures. Nonetheless, no such manufactured solid mate...

(1) Background: Recent developments in 7T magnetic resonance spectroscopic imaging (MRSI) made the acquisition of high-resolution metabolic images in clinically feasible measurement times possible. The amino acids glutamine (Gln) and glycine (Gly) were identified as potential neuro-oncological markers of importance. For the first time, we compared...

Aim To develop and evaluate a new approach for spatially variant and tissue-dependent positron range (PR) correction (PRC) during the iterative PET image reconstruction. Materials and Methods The PR distributions of three radionuclides (¹⁸F, ⁶⁸Ga, and ¹²⁴I) were simulated using the GATE (GEANT4) framework in different material compositions (lung,...

Rationale: To determine whether ComBat harmonization improves 18F-FDG-PET radiomics-based tissue classification in pooled PET/MR and PET/CT datasets. Methods: Two-hundred patients who had undergone 18F-FDG-PET/MR (two scanners/vendors; 50 patients each) or -PET/CT (two scanners/vendors; 50 patients each) were retrospectively included. Grey-level hi...

Background: MR-based methods for attenuation correction (AC) in PET/MRI either neglect attenuation of bone, or use MR-signal derived information about bone, which leads to a bias in quantification of tracer uptake in PET. In a previous study, we presented a PET/MRI specific MR coil with an integrated transmission source (TX) system allowing for di...

Purpose To assess dose levels in routine nuclear medicine (NUC) procedures in Austria as a prior to a legislative update of the National Diagnostic Reference Levels (NDRL). Method As part of a nationwide survey of common NUC-examinations between June 2019 and November 2019, data sets were collected from 33 Austrian hospitals with NUC equipment. Al...

An EFOMP Working Group (WG) was created in 2020 with the aim of establishing recommendations for performing PET/CT and PET/MRI Quality Control (QC). The WG would like to create a document with a set of measurements suitable for practical use, taking into account possible variations in practices based on the size and type of hospital or availability...

PurposeRisk classification of primary prostate cancer in clinical routine is mainly based on prostate-specific antigen (PSA) levels, Gleason scores from biopsy samples, and tumor-nodes-metastasis (TNM) staging. This study aimed to investigate the diagnostic performance of positron emission tomography/magnetic resonance imaging (PET/MRI) in vivo mod...

Purpose To investigate the possibility of reducing the injected activity for whole-body [18F]FDG-PET/CT studies of paediatric oncology patients and to assess the usefulness of time-of-flight (TOF) acquisition on PET image quality at reduced count levels. Procedures Twenty-nine paediatric oncology patients (12F/17M, 3–18 years old (median age 13y),...

Background PET/MRI phantom studies are challenged by the need of phantom-specific attenuation templates to account for attenuation properties of the phantom material. We present a PET/MRI phantom built from MRI-visible material for which attenuation correction (AC) can be performed using the standard MRI-based AC. Methods A water-fillable phantom...

Purpose of the report: F-FDG PET is limited for assessment of central nervous system lymphoma (CNSL) due to physiologic tracer accumulation in the brain. We prospectively evaluated the novel PET tracer Ga-pentixafor, which targets the C-X-C chemokine receptor 4 (CXCR4), for lesion visualization and response assessment of CNSL. Materials and metho...

Background Cardiac positron emission tomography/magnetic resonance imaging (PET/MRI) can assess various cardiovascular diseases. In this study, we intra-individually compared right (RV) and left ventricular (LV) parameters obtained from dual-tracer PET/MRI scan. Methods In 22 patients with coronary heart disease (69 ± 9 years) dynamic [ ¹³ N]NH 3...

AimThe aim of this study was to evaluate and correct for partial-volume-effects (PVE) on [68Ga]Ga-Pentixafor uptake in atherosclerotic plaques of the carotid arteries, and the impact of ignoring bone in MR-based attenuation correction (MR-AC).Methods Twenty [68Ga]Ga-pentixafor PET/MR examinations including a high-resolution T2-TSE MR of the neck we...

In the past, determination of absolute values of cerebral metabolic rate of glucose (CMRGlc) in clinical routine was rarely carried out due to the invasive nature of arterial sampling. With the advent of combined PET/MR imaging technology, CMRGlc values can be obtained non-invasively, thereby providing the opportunity to take advantage of fully qua...

Background In oncology, lesion characterization is essential for tumor grading, treatment planning, and follow‐up of cancer patients. Hybrid imaging systems, such as Single Photon Emission Computed Tomography (SPECT)/CT, Positron Emission Tomography (PET)/CT, or PET/magnetic resonance imaging (MRI), play an essential role for the noninvasive quanti...

The purpose of this study was to establish a non-invasive clinical PET/MR protocol using [¹⁸F]-labeled deoxyglucose (FDG) that provides physicians with regional metabolic rate of glucose (MRGlc) values and to clarify the contribution of absolute quantification to clinical management of patients with non-lesional extratemporal lobe epilepsy (ETLE)....

Purpose PET/MRI has recently been introduced into clinical practice. We prospectively investigated the clinical impact of PET/MRI compared with PET/CT, in a mixed population of cancer patients, and performed an economic evaluation of PET/MRI. Methods Cancer patients referred for routine staging or follow-up by PET/CT underwent consecutive PET/CT a...

Background Several MR-based attenuation correction (AC) approaches were developed to conquer the challenging AC in hybrid PET/MR imaging. These AC methods are commonly evaluated on standardized uptake values or tissue concentration. However, in neurotransmitter system studies absolute quantification is more favorable due to its accuracy. Therefore,...

Hybrid PET/MR offers new opportunities in radiation oncology for tissue/tumour characterisation and response assessment. Attenuation correction (AC) is an important issue especially in the presence of immobilization devices and flat table tops (FTT). The goal of this study was to compare two methods of AC using CT- and 68Ge/68Ga transmission scan-b...

Quality control (QC) of medical imaging devices is essential to ensure their proper function and to gain accurate and quantitative results. Therefore, several international bodies have published QC guidelines and recommendations for a wide range of imaging modalities to ensure adequate performance of the systems. Hybrid imaging systems such as posi...

A fully-automated processing pipeline is presented to support non-invasive absolute quantification of cerebral metabolic rate of glucose (CMRGlc) in a clinical setting. Our method takes full advantage of 'anato-metabolic' information associated with fully-integrated PET/MR imaging. Methods: Ten healthy volunteers (27 ± 7 years, 70 ± 10 kg, 5M/5F) u...

Several radionuclides of the transition metal manganese are known and accessible. Three of them, ⁵¹Mn, 52mMn, and 52gMn, are positron emitters which are potentially interesting for PET applications, and thus, have caught the interest of the radiochemical/‐pharmaceutical and nuclear medicine communities. This mini‐review provides an overview of the...

Background [¹⁸F]‐2‐fluoro‐2‐deoxy‐D‐glucose (18F‐FDG) positron emission tomography/computed tomography (FDG‐PET/CT) imaging provides important information about the size and metabolic activity of lesions caused by Echinococcus multilocularis and is therefore recommended for the initial assessment and follow‐up of human alveolar echinococcosis (AE)....

Combined PET/MR imaging (PET/MRI) was proposed for patient management in 2006 with first commercial versions of integrated whole-body systems becoming available as of 2010. PET/MRI followed the prior evolution of hybrid imaging as attested by the successful adoption of combined PET/CT and SPECT/CT since the early 2000 s. Today, around 150 whole-bod...

Combined PET/MR imaging (PET/MRI) was proposed for patient management in 2006 with first commercial versions of integrated whole-body systems becoming available as of 2010. PET/MRI followed the prior evolution of hybrid imaging as attested by the successful adoption of combined PET/CT and SPECT/CT since the early 2000 s. Today, around 150 whole-bod...

Aim To assess if tumour grading based on dynamic [18F]FET positron emission tomography/magnetic resonance imaging (PET/MRI) studies is affected by different MRI-based attenuation correction (AC) methods. Methods Twenty-four patients with suspected brain tumours underwent dynamic [18F]FET-PET/MRI examinations and subsequent low-dose computed tomogr...

The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) provides a benefit for diagnostic imaging. Still, attenuation correction (AC) is a challenge in PET/MRI compared to stand-alone PET and PET-computed tomography (PET/CT). In the absence of photonic transmission sources, AC in PET/MRI is usually based on retros...

Purpose: The aim of the study was to assess the reliability of self-reported weight and size of nuclear medicine patients in view of recommendation for the weight-dependent tracer application for imaging and therapy. Methods: A total of 824 patients (334m, 490f) were asked to report their weight and size prior imaging or therapy and their level of...

Radiomics analysis of 18F-FDG-PET/CT images promises for an improved in-vivo disease characterization. To date, several studies reported significant variations in textural features due to differences in patient preparation, imaging protocols, lesion delineation and feature extraction. Our objective was to study variations of features prior to a rad...

Aim: The aim of this study is to evaluate the physical performance of the Philips Vereos whole-body PET/CT system according to the NEMA NU2-2012 standard and to compare it to other state-of-the-art PET/CT systems. Methods: Spatial resolution, sensitivity, count-rate performance, count rate accuracy and image quality were assessed. Specifically, spa...

Medical imaging has evolved from a pure visualization tool to representing a primary source of analytic approaches toward in vivo disease characterization. Hybrid imaging is an integral part of this approach, as it provides complementary visual and quantitative information in the form of morphological and functional insights into the living body. A...

Absolute quantification of PET brain imaging requires the measurement of an arterial input function (AIF), typically obtained invasively via an arterial cannulation. We present an approach to automatically calculate an image-derived input function (IDIF) and cerebral metabolic rates of glucose (CMRGlc) from the [18F]FDG PET data using an integrated...

State-of-the-art patient management frequently requires the use of non-invasive imaging methods to assess the anatomy, function or molecular-biological conditions of patients or study subjects. Such imaging methods can be singular, providing either anatomical or molecular information, or they can be combined, thus, providing “anato-metabolic” infor...

A novel breathing phantom was designed for being used in conventional and ion-beam radiotherapy as well as for medical imaging. Accurate dose delivery and patient safety are aimed to be verified for four-dimensional (4D) treatment techniques compensating for breathing-induced tumor motion. The phantom includes anthropomorphic components representin...

Background: Few data exist regarding the prognostic value of L-[S-methyl- 11C]methionine (MET) PET for treatment-naive gliomas. Methods: A total of 160 glioma patients (89 men, 71 women, mean age: 45, range 18 - 84 yrs) underwent a MET PET prior to any therapy. The PET scans were evaluated visually and semiquantitatively by tumor to background (...

Purpose: About 10% of patients with neurofibromatosis type 1 (NF-1) develop malignant peripheral nerve sheath tumours (MPNST) mostly arising in plexiform neurofibroma (PN); 15% of MPNST arise in children and adolescents. 2-[(18) F]fluoro-2-deoxy-d-glucose ([(18) F]FDG)-PET (where PET is positron emission tomography) is a sensitive method in differ...

Objectives To evaluate and compare the effect of reduced acquisition time, as a surrogate of injected activity, on the PET quantification accuracy in PET/CT and PET/MR imaging. Methods Twenty min ¹⁸F-FDG phantom measurements and 10 min ¹⁸F-FET brain scans were acquired in a Biograph-True-Point-True-View PET/CT (n = 8) and a Biograph mMR PET/MR (n...

The purpose of this study was to test the feasibility of migrating a quantitative brain imaging protocol from a positron emission tomography (PET)-only system to an integrated PET/MR system. Potential differences in both absolute radiotracer concentration as well as in the derived kinetic parameters as a function of PET system choice have been inve...

Purpose To evaluate the influence of point spread function (PSF)-based reconstruction and matrix size for PET on (1) lung lesion detection and (2) standardized uptake values (SUV). Methods This prospective study included oncological patients who underwent [18F]-FDG-PET/CT for staging. PET data were reconstructed with a 2D ordered subset expectatio...

This paper highlights the origins of combined positron emission tomography (PET) and magnetic resonance imaging (MRI) whole-body systems that were first introduced for applications in humans in 2010. This text first covers basic aspects of each imaging modality before describing the technical and methodological challenges of combining PET and MRI w...

Aim: To compare attenuation correction (AC) approaches for positron emission tomography/magnetic resonance imaging (PET/MRI) in clinical neuro-oncology. Methods: Forty-nine PET/MRI brain scans were included: brain tumor studies using (18)F-FET (n = 31) and 68-Ga-DOTANOC (n = 7) and studies of healthy subjects using (18)F-FDG (n = 11). For each sub...

Background Accurate quantification of plaque imaging using 18F-NaF PET requires partial volume correction (PVC). MethodsPVC of PET data was implemented by the use of a local projection (LP) method. LP-based PVC was evaluated with an image quality (NEMA) and with a thorax phantom with “plaque-type” lesions of 18-36 mL. The validated PVC method was t...

Purpose: To determine whether interim F-FDG PET or interim diffusion-weighted magnetic resonance imaging (DWI) can predict the end-of-treatment (EOT) outcome after immunotherapy in patients with FDG-avid extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT). Materials and methods: Patients with untreated MALT l...

Purpose PET with 18F-FDG has the potential to assess vascular macrophage metabolism. 18F-FDG is most often used in combination with contrast-enhanced CT to localize increased metabolism to specific arterial lesions. Novel 18F-FDG PET/MRI hybrid imaging shows high potential for the combined evaluation of atherosclerotic plaques, due to the superior...

Aims: To assess incremental and total patient exposure from clinical SPECT/CT imaging by means of effective dose estimations with regards to different protocols and SPECT/CT systems. Materials and methods: Consecutive patient exposure levels were documented prospectively from SPECT/CT operations at three European imaging centers. Documentation i...