Development of a Hybrid-Imaging-Based Prognostic Index for Metastasized-Melanoma Patients in Whole-Body 18F-FDG PET/CT and PET/MRI Data.

Besides tremendous treatment success in advanced melanoma patients, the rapid development of oncologic treatment options comes with increasingly high costs and can cause severe life-threatening side effects. For this purpose, predictive baseline biomarkers are becoming increasingly important for risk stratification and personalized treatment planning. Thus, the aim of this pilot study was the development of a prognostic tool for the risk stratification of the treatment response and mortality based on PET/MRI and PET/CT, including a convolutional neural network (CNN) for metastasized-melanoma patients before systemic-treatment initiation.

Spatial-temporal perfusion patterns of the human liver assessed by pseudo-continuous arterial spin labeling MRI.

Purpose: To investigate the capabilities of a modern pseudo-continuous arterial spin labeling (PCASL) technique for non-invasive assessment of the temporal and spatial distribution of the liver perfusion in healthy volunteers on a clinical MR system at 3T.

Materials And Methods: A 2D-PCASL multi-slice echo planar imaging sequence was adapted to the specific conditions in liver: a) labeling by PCASL was optimized to the flow characteristics in the portal vein, b) background suppression was applied for reduction of motion related artifacts, c) post labeling delays (PLDs) were varied over a large range (0.7-3.

Assessment of image quality of a radiotherapy-specific hardware solution for PET/MRI in head and neck cancer patients.

Background And Purpose: Functional PET/MRI has great potential to improve radiotherapy planning (RTP). However, data integration requires imaging with radiotherapy-specific patient positioning. Here, we investigated the feasibility and image quality of radiotherapy-customized PET/MRI in head-and-neck cancer (HNC) patients using a dedicated hardware setup.

Voxel-wise correlation of functional imaging parameters in HNSCC patients receiving PET/MRI in an irradiation setup.

Purpose: The purpose of this study was to demonstrate the feasibility of voxel-wise multiparametric characterization of head and neck squamous cell carcinomas (HNSCC) using hybrid multiparametric magnetic resonance imaging and positron emission tomography with [F]-fluorodesoxyglucose (FDG-PET/MRI) in a radiation treatment planning setup.

Methods: Ten patients with locally advanced HNSCC were examined with a combined FDG-PET/MRI in an irradiation planning setup. The multiparametric imaging protocol consisted of FDG-PET, T2-weighted transverse short tau inversion recovery sequence (STIR) and diffusion-weighted MRI (DWI).

Scan time reduction in diffusion-weighted imaging of the pancreas using a simultaneous multislice technique with different acceleration factors: How fast can we go?

Objectives: To investigate the feasibility of simultaneous multislice-accelerated diffusion-weighted imaging (sms-DWI) of the pancreas with different acceleration factors and its influence on image quality, acquisition time and apparent diffusion coefficients (ADCs) in comparison to conventional sequences.

Methods: DWI of the pancreas was performed at 1.5T in ten healthy volunteers and 20 patients with sms-accelerated echo-planar DWI using two different sms-acceleration factors of 2 and 3 (sms2/3-DWI).

Comprehensive metabolic and morphologic disease characterization in systemic sclerosis: initial results using combined positron emission tomography and magnetic resonance imaging.

Background: The aim of this study was to evaluate the role of metabolic and morphologic parameters derived from simultaneous hybrid PET/MRI in correlation to clinical criteria for an image-based characterization of musculoskeletal, esophagus and lymph node involvement in systemic sclerosis (SSc).

Methods: Between November 2013 and May 2015, simultaneous whole-body hybrid PET/MRI was performed in 13 prospectively recruited patients with SSc. A mean dose of 241.

Defining optimal tracer activities in pediatric oncologic whole-body F-FDG-PET/MRI.

Purpose: To explore the feasibility of reducing administered tracer activities and to assess optimal activities for combined F-FDG-PET/MRI in pediatric oncology.

Methods: 30 F-FDG-PET/MRI examinations were performed on 24 patients with known or suspected solid tumors (10 girls, 14 boys, age 12 ± 5.6 [1-18] years; PET scan duration: 4 min per bed position).

Self-navigated 4D cartesian imaging of periodic motion in the body trunk using partial k-space compressed sensing.

Purpose: To enable fast and flexible high-resolution four-dimensional (4D) MRI of periodic thoracic/abdominal motion for motion visualization or motion-corrected imaging.

Methods: We proposed a Cartesian three-dimensional k-space sampling scheme that acquires a random combination of k-space lines in the ky/kz plane. A partial Fourier-like constraint compacts the sampling space to one half of k-space.

Diagnosing Lung Nodules on Oncologic MR/PET Imaging: Comparison of Fast T1-Weighted Sequences and Influence of Image Acquisition in Inspiration and Expiration Breath-Hold.

Objective: First, to investigate the diagnostic performance of fast T1-weighted sequences for lung nodule evaluation in oncologic magnetic resonance (MR)/positron emission tomography (PET). Second, to evaluate the influence of image acquisition in inspiration and expiration breath-hold on diagnostic performance.

Materials And Methods: The study was approved by the local Institutional Review Board.

Systematic Evaluation of Amide Proton Chemical Exchange Saturation Transfer at 3 T: Effects of Protein Concentration, pH, and Acquisition Parameters.

Objective: The goal of this work was to systematically evaluate the reproducibility of amide proton transfer chemical exchange saturation transfer (APT-CEST) at 3 T and its signal dependence on pH, protein concentration, and acquisition parameters. An in vitro system based on bovine serum albumin (BSA) was used, and its limitations were tested by comparing it to in vivo measurements. The contribution of small endogenous metabolites on the APT-CEST signal at 3 T was also investigated.

Diffusion-weighted imaging in the assessment of prostate cancer: Comparison of zoomed imaging and conventional technique.

Purpose: To compare reduced field-of-view (zoomed) diffusion-weighted imaging (DWI) and conventional DWI in the evaluation of prostate cancer with respect to lesion detection, image quality and alignment accuracy.

Material And Methods: The study was carried out in accordance with the Declaration of Helsinki and was approved by the institutional review board. Image data of 29 histology-proven prostate cancer lesions in 15 patients were evaluated.

Scan time minimization in hepatic diffusion-weighted imaging: evaluation of the simultaneous multislice acceleration technique with different acceleration factors and gradient preparation schemes.

Objective: To evaluate simultaneous multislice (sms) accelerated diffusion-weighted imaging (DWI) of the liver in comparison to conventional sequences.

Materials And Methods: Ten volunteers underwent DWI of the liver at 1.5 T.

Is It Possible to Detect Activated Brown Adipose Tissue in Humans Using Single-Time-Point Infrared Thermography under Thermoneutral Conditions? Impact of BMI and Subcutaneous Adipose Tissue Thickness.

Purpose: To evaluate the feasibility to detect activated brown adipose tissue (BAT) using single-time-point infrared thermography of the supraclavicular skin region under thermoneutral conditions. To this end, infrared thermography was compared with 18-F-FDG PET, the current reference standard for the detection of activated BAT.

Methods: 120 patients were enrolled in this study.

Towards tracer dose reduction in PET studies: Simulation of dose reduction by retrospective randomized undersampling of list-mode data.

Objective: Optimization of tracer dose regimes in positron emission tomography (PET) imaging is a trade-off between diagnostic image quality and radiation exposure. The challenge lies in defining minimal tracer doses that still result in sufficient diagnostic image quality. In order to find such minimal doses, it would be useful to simulate tracer dose reduction as this would enable to study the effects of tracer dose reduction on image quality in single patients without repeated injections of different amounts of tracer.

Simultaneous multislice diffusion-weighted MRI of the liver: Analysis of different breathing schemes in comparison to standard sequences.

Purpose: To systematically evaluate image characteristics of simultaneous-multislice (SMS)-accelerated diffusion-weighted imaging (DWI) of the liver using different breathing schemes in comparison to standard sequences.

Materials And Methods: DWI of the liver was performed in 10 healthy volunteers and 12 patients at 1.5T using an SMS-accelerated echo planar imaging sequence performed with respiratory-triggering and free breathing (SMS-RT, SMS-FB).

Apparent diffusion coefficient-dependent voxelwise computed diffusion-weighted imaging: An approach for improving SNR and reducing T2 shine-through effects.

Purpose: To introduce and evaluate a method for signal-to-noise ratio (SNR) improvement and T2 shine-through effect reduction in diffusion-weighted magnetic resonance imaging (DWI).

Materials And Methods: The proposed method uses quantitative information given by the voxel apparent diffusion coefficient (ADC) to derive voxelwise-computed DWI (vcDWI). Behavior of signal intensity variations was simulated and correlated with measurements using a dedicated phantom for DWI allowing for independent adjustment of T2 -relaxivity and diffusivity.

Comprehensive Oncologic Imaging in Infants and Preschool Children With Substantially Reduced Radiation Exposure Using Combined Simultaneous ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Imaging: A Direct Comparison to ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography.

Objective: The aim of this study was to evaluate the clinical applicability and technical feasibility of fluorodeoxyglucose (FDG) positron emission tomography (PET)/magnetic resonance imaging (MRI) compared with FDG PET/computed tomography (CT) in young children focusing on lesion detection, PET quantification, and potential savings in radiation exposure.

Methods: Twenty examinations (10 PET/CT and 10 PET/MRI examinations) were performed prospectively in 9 patients with solid tumors (3 female, 6 male; mean age, 4.8 [1-6] years).

PET/CT, MR, and PET/MR in Lymphoma and Melanoma.

With the introduction of hybrid imaging technologies such as PET/CT and recently PET/MRI, staging and therapy-response monitoring have evolved. PET/CT has been shown to be of value for routine staging of FDG-avid lymphomas before as well as at the end of treatment. For interim staging, trials are ongoing to evaluate the use of PET/CT.

Combined unsupervised-supervised classification of multiparametric PET/MRI data: application to prostate cancer.

Multiparametric medical imaging data can be large and are often complex. Machine learning algorithms can assist in image interpretation when reliable training data exist. In most cases, however, knowledge about ground truth (e.

Multiparametric analysis of bone marrow in cancer patients using simultaneous PET/MR imaging: Correlation of fat fraction, diffusivity, metabolic activity, and anthropometric data.

Background: To analyze the regional composition of bone marrow (BM) in correlation with metabolic activity and diffusivity using simultaneous positron emission tomography (PET)/MRI.

Methods: Retrospective analysis of 18F-FDG-PET/MR scans of 110 patients was performed. A three-dimensional gradient-echo sequence with Dixon-based fat-water separation was used for fat quantification.

Impact of measurement parameters on apparent diffusion coefficient quantification in diffusion-weighted-magnetic resonance imaging.

Objective: The scope of this work was to systematically evaluate the reproducibility of diffusion-weighted imaging and the impact of b values used for apparent diffusion coefficient (ADC) calculation as well as the echo time (TE) on the resulting ADC in phantom studies. We attempted to find a minimum upper b value needed for reliable ADC measurements. In addition, we were able to investigate these impacts not only for different diffusivities but also for different T2 relaxation times.

Measurement of apparent diffusion coefficient with simultaneous MR/positron emission tomography in patients with peritoneal carcinomatosis: comparison with 18F-FDG-PET.

Purpose: To characterize peritoneal carcinomatosis (PC) of different histologically proven primary tumors based on diffusion-weighted imaging (DWI) and (18) F-FDG positron emission tomography (PET).

Materials And Methods: Forty-one patients underwent simultaneous MR/PET after clinically indicated (18) F-FDG-PET/CT. For all patients, histology of the primary tumor was obtained.

Simultaneous whole-body PET/MR imaging in comparison to PET/CT in pediatric oncology: initial results.

Purpose: To compare positron emission tomography (PET)/magnetic resonance (MR) imaging and PET/computed tomography (CT) for lesion detection and interpretation, quantification of fluorine 18 ((18)F) fluorodeoxyglucose (FDG) uptake, and accuracy of MR-based PET attenuation correction in pediatric patients with solid tumors. Materials and Methods This prospective study had local ethics committee and German Federal Institute for Drugs and Medical Devices approval. Written informed consent was obtained from all patients and legal guardians.

Combined PET/MR: Where are we now? Summary report of the second international workshop on PET/MR imaging April 8-12, 2013, Tubingen, Germany.

This workshop was held a year after the initial positron emission tomography/magnetic resonance (PET/MR) workshop in Tübingen, which was recently reported in this journal. The discussions at the 2013 workshop, however, differed substantially from those of the initial workshop, attesting to the progress of combined PET/MR as an innovative imaging modality. Discussions were focused on the search for truly novel, unique clinical and research applications as well as technical issues such as reliable and accurate approaches for attenuation and scatter correction of PET emission data.