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Purpose: To maximize acquisition bandwidth in zero echo time (ZTE) sequences, readout gradients are already switched on during the RF pulse, creating unwanted slice selectivity. The resulting image distortions are amplified especially when the anatomy of interest is not located at the isocenter. We aim to characterize off-center ZTE MRI of extremities such as the shoulder, knee, and hip, adjusting the carrier frequency of the RF pulse excitation for each TR. Methods: In ZTE MRI, radial encoding schemes are used, where the distorted slice profile due to the finite RF pulse length rotates with the k-space trajectory. To overcome these modulations for objects far away from the magnet isocenter, the frequency of the RF pulse is shifted for each gradient setting so that artifacts do not occur at a given off-center target position. The sharpness of the edges in the images were calculated and the ZTE acquisition with off-center excitation was compared to an acquisition with isocenter excitation both in phantom and in vivo off-center MRI of the shoulder, knee, and hip at 1.5 and 3T MRI systems. Results: Distortion and blurriness artifacts on the off-center MRI images of the phantom, in vivo shoulder, knee, and hip images were mitigated with off-center excitation without time or noise penalty, at no additional computational cost. Conclusion: The off-center excitation allows ZTE MRI of the shoulder, knee, and hip for high-bandwidth image acquisitions for clinical settings, where positioning at the isocenter is not possible.

Abstract Background In this work, we compare input level, feature level and decision level data fusion techniques for automatic detection of clinically significant prostate lesions (csPCa). Methods Multiple deep learning CNN architectures were developed using the Unet as the baseline. The CNNs use both multiparametric MRI images (T2W, ADC, and High b-value) and quantitative clinical data (prostate specific antigen (PSA), PSA density (PSAD), prostate gland volume & gross tumor volume (GTV)), and only mp-MRI images (n = 118), as input. In addition, co-registered ground truth data from whole mount histopathology images (n = 22) were used as a test set for evaluation. Results The CNNs achieved for early/intermediate / late level fusion a precision of 0.41/0.51/0.61, recall value of 0.18/0.22/0.25, an average precision of 0.13 / 0.19 / 0.27, and F scores of 0.55/0.67/ 0.76. Dice Sorensen Coefficient (DSC) was used to evaluate the influence of combining mpMRI with parametric clinical data for the detection of csPCa. We compared the DSC between the predictions of CNN’s trained with mpMRI and parametric clinical and the CNN’s trained with only mpMRI images as input with the ground truth. We obtained a DSC of data 0.30/0.34/0.36 and 0.26/0.33/0.34 respectively. Additionally, we evaluated the influence of each mpMRI input channel for the task of csPCa detection and obtained a DSC of 0.14 / 0.25 / 0.28. Conclusion The results show that the decision level fusion network performs better for the task of prostate lesion detection. Combining mpMRI data with quantitative clinical data does not show significant differences between these networks (p = 0.26/0.62/0.85). The results show that CNNs trained with all mpMRI data outperform CNNs with less input channels which is consistent with current clinical protocols where the same input is used for PI-RADS lesion scoring. Trial registration The trial was registered retrospectively at the German Register for Clinical Studies (DRKS) under proposal number Nr. 476/14 & 476/19.

Abstract Magnetic resonance imaging (MRI) provides a multitude of techniques to detect and characterize myocardial infarction. To correlate MRI findings with histology, in most cases terminal animal studies are performed; however, precise extraction and spatial correlation of myocardial tissue samples to MRI image data is difficult. In this proof of concept study, we present a 3D-printing technique to facilitate the extraction of tissue samples from myocardial regions. Initially, seven pig hearts embedded in formaldehyde were imaged on a clinical 3 T system to define biopsy targets on high resolution ex vivo images. Magnitude images and R2*-maps acquired with a 3D multi-echo gradient echo sequence and 0.58 mm isotropic resolution were used to create digital models of the cardiac anatomy. Biopsy guides were 3D-printed to steer the extraction of myocardial samples. In total, 61 tissue samples were extracted with an average offset of the tissue sample location from the target location of 0.59 ± 0.36 mm. This offset was not dependent on the distance of the target point to the epicardial surface. Myocardial tissue could be extracted from all samples. The presented method enables extraction of myocardial tissue samples that are selected by ex vivo MRI with submillimeter precision.

In closed-bore MRI units, assistance systems play a crucial role in overcoming patient access limitations during percutaneous interventions. In this work, we present eGantryMate, a piezo-motor-driven assistance system specifically designed for MR-guided needle interventions in high-field MRI systems. eGantryMate consists of an instrument positioning unit and a control unit equipped with piezo motors, radiofrequency filters, and shielding. Paired with a real-time tracking sequence for automatic marker detection and projection of the instrument trajectory onto the MR image, eGantryMate enables precise and efficient needle interventions. Targeting experiments were performed by inserting a biopsy needle into a series of fiducial targets in a phantom, and usability experiments were conducted in vivo without needle insertion. The results show artifact-free MR imaging, minimal temperature rise on the instrument positioning unit, and precise targeting capabilities. These findings demonstrate eGantryMate’s ability to perform real-time needle alignments and insertions within the magnet bore, highlighting its potential to enhance the acceptability and efficacy of MR-guided interventions.

Abstract Pigs are frequently applied as animal models in cardiovascular research due to their anatomical and physiological similarity to humans. For study planning and refinement, precise knowledge of the cardioaortic dimensions is essential. In a retrospective single-center study, the cardioaortic dimensions and left ventricular function of German Landrace pigs were assessed using cardiac MRI. All parameters were compared between male and female pigs and analyzed for correlation with body weight. In total, 15 pigs were included (7 male and 8 female, weight 60.9 ± 7.0 kg). The left ventricle revealed an end-diastolic diameter of 50.5 ± 4.4 mm and an ejection fraction of 51.2 ± 9.8%. The diameters of the ascending and descending aorta were 21.3 ± 2.3 and 16.2 ± 1.4 mm, respectively. There were no significant differences between male and female pigs, except that males had a smaller end-diastolic left ventricular volume (p = 0.041). A moderate correlation was found between body weight and the aortic annulus diameter (R = 0.57, p = 0.027). In conclusion, cardiac MRI allows precise quantification of porcine cardioaortic dimensions. For medical device testing, size differences between pigs and humans should be considered.

Abstract Automatic prostate tumor segmentation is often unable to identify the lesion even if multi-parametric MRI data is used as input, and the segmentation output is difficult to verify due to the lack of clinically established ground truth images. In this work we use an explainable deep learning model to interpret the predictions of a convolutional neural network (CNN) for prostate tumor segmentation. The CNN uses a U-Net architecture which was trained on multi-parametric MRI data from 122 patients to automatically segment the prostate gland and prostate tumor lesions. In addition, co-registered ground truth data from whole mount histopathology images were available in 15 patients that were used as a test set during CNN testing. To be able to interpret the segmentation results of the CNN, heat maps were generated using the Gradient Weighted Class Activation Map (Grad-CAM) method. The CNN achieved a mean Dice Sorensen Coefficient 0.62 and 0.31 for the prostate gland and the tumor lesions -with the radiologist drawn ground truth and 0.32 with whole-mount histology ground truth for tumor lesions. Dice Sorensen Coefficient between CNN predictions and manual segmentations from MRI and histology data were not significantly different. In the prostate the Grad-CAM heat maps could differentiate between tumor and healthy prostate tissue, which indicates that the image information in the tumor was essential for the CNN segmentation.

In MR-guided interventional procedures, RF coils can be attached to the instruments to provide a positive MR signal for device tracking. The signal from these coils can vary strongly over the procedure and mask the surrounding anatomy. The purpose of this study is to introduce and demonstrate a low-cost, vendor- and device-independent interface circuit that allows the interventionalist to adjust the active device signal intensity. In this work a variable attenuator circuit was constructed to control the tip signal of an active coronary artery catheter in real-time from within the MR scanner room. Performance of the attenuator circuit and the active catheter was characterized on the test bench, in a phantom model, and in vivo. The system was used in a pig model at 3T during the introduction of the catheter into the left coronary artery. The circuit could attenuate the amplitude of the tracking coil signal by up to 20 dB. Without attenuation, the tracking coil signal intensity was masking anatomical details of the coronary ostium making it impossible to reliably introduce the catheter into the artery. After interactive adjustment, which was performed in a few seconds by the interventionalist, the improved visualization of the vascular anatomy enabled a rapid insertion of the catheter into the coronary ostium. The vendor-independent variable attenuator provides real-time control of the catheter signal without interrupting the image acquisition. Even though most MRI systems can control the individual signal levels from coils by software, the attenuator hardware is advantageous as it can be integrated into any MR-system, and it provides a direct interface for the interventionalist at the magnet.

Purpose: Concerning voice efficiency considerations of different singing styles, from western classical singing to contemporary commercial music, only limited data is available to date. This single-subject study attempts to quantify the acoustic sound intensity within the human glottis depending on different vocal tract configurations and vocal fold vibration.Methods: Combining Finite-Element-Models derived from 3D-MRI data, audio recordings, and electroglottography (EGG) we analyzed vocal tract transfer functions, particle velocity and acoustic pressure at the glottis, and EGG-related quantities to evaluate voice efficiency at the glottal level and resonance characteristics of different voice qualities according to Estill Voice Training®.Results: Voice qualities Opera and Belting represent highly efficient strategies but apply different vowel strategies and should thus be capable of predominate orchestral sounds. Twang and Belting use similar vowels, but the twang vocal tract configuration enabled the occurrence of anti-resonances and was associated with reduced vocal fold contact but still partially comparable energy transfer from the glottis to the vocal tract. Speech was associated with highly efficient glottal to vocal tract energy transfer, but with the absence of psychoactive strategies makes it more susceptible to noise interference. Falsetto and Sobbing apply less efficiently. Falsetto mainly due to its voice source characteristics, Sobbing due to energy loss in the vocal tract. Thus technical amplification might be appropriate here.Conclusion: Differences exist between voice qualities regarding the sound intensity, caused by different vocal tract morphologies and oscillation characteristics of the vocal folds. The combination of numerical analysis of geometries inside the human body and experimentally determined data outside sheds light on acoustical quantities at the glottal level.

Breath control is an important factor for singing voice production, but pedagogic descriptions of how a beneficial movement pattern should be performed vary widely and the underlying physiological processes are not understood in detail. Differences in respiratory movements during singing might be related to the sex of the singer. To study sex-related differences in respiratory kinematics during phonation, 12 singers (six male and six female) trained in the Western classical singing tradition were imaged with dynamic magnetic resonance imaging. Singers were asked to sustain phonation at five different pitches and loudness conditions, and cross-sectional images of the lung were acquired. In each dynamic image frame the distances between anatomical landmarks were measured to quantify the movements of the respiratory apparatus. No major difference between male and female singers was found for the general respiratory kinematics of the thorax and the diaphragm during sustained phonation. However when compared to sole breathing, male singers significantly increased their thoracic movements for singing. This behavior could not be observed in female singers. The presented data support the hypothesis that professional singers follow sex-specific breathing strategies. This finding may be important in a pedagogical context where the biological sex of singer and student differ and should be further investigated in a larger cohort.

Many neurological disorders are analyzed and treated with implantable electrodes. Many patients with such electrodes have to undergo MRI examinations – often unrelated to their implant - at the risk of radio-frequency induced heating. The number of electrode contact sites of these implants keeps increasing due to improvements in manufacturing and computational algorithms. Electrode grids with multiple receive channels couple to the RF fields present in MRI, but, due to their proximity, a combination of leads has a coupling response which is not a superposition of the individual leads’ response. To investigate the problem of RF-induced heating of coupled multi-lead implants, temperature mapping was performed on a set of intra-cranial electroencephalogram (icEEG) electrode grid prototypes with increasing number of contact sites (1-16). Additionally, electric field measurements were used to investigate the radio-frequency heating characteristics of the implants in different media combinations, simulating the device being partially immersed inside the patient.MR measurements show RF-induced heating up to 19.6 K for the single electrode, reducing monotonically with larger number of contact sites to a minimum of 0.9 K for the largest grid. The SAR calculated from temperature measurements agrees well with electric field mapping: The same trend is visible for different insertion lengths, however, the energy dissipated by the whole implant varies with the grid size and insertion length. Thus, in the tested circumstances, a larger electrode number either reduced or had a similar risk of RF induced heating, indicating, that the size of electrode grids is a design parameter, which can be used to change an implants RF response and in turn to reduce the risk of RF induced heating and improve the safety of patient with neuro-implants undergoing MRI examinations.

Abstract Respiratory kinematics are important for the regulation of voice production. Dynamic MRI is an excellent tool to study respiratory motion providing high-resolution cross-sectional images. Unfortunately, in clinical MRI systems images can only be acquired in a horizontal subject position, which does not take into account gravitational effects on the respiratory apparatus. To study the effect of body posture on respiratory kinematics during phonation, 8 singers were examined both in an open-configuration MRI with a rotatable gantry and a conventional horizontal MRI system. During dynamic MRI the subjects sang sustained tones at different pitches in both supine and upright body positions. Sagittal images of the respiratory system were obtained at 1–3 images per second, from which 6 anatomically defined distances were extracted to characterize its movements in the anterior, medium and posterior section of the diaphragm as well as the rip cage (diameter at the height of the 3rd and 5th rip) and the anterior–posterior position of the diaphragm cupola. Regardless of body position, singers maintained their general principles of respiratory kinematics with combined diaphragm and thorax muscle activation for breath support. This was achieved by expanding their chest an additional 20% during inspiration when singing in the supine position but not for sole breathing. The diaphragm was cranially displaced in supine position for both singing and breathing and its motion range increased. These results facilitate a more realistic extrapolation of research data obtained in a supine position.

Abstract Background Automatic tumor segmentation based on Convolutional Neural Networks (CNNs) has shown to be a valuable tool in treatment planning and clinical decision making. We investigate the influence of 7 MRI input channels of a CNN with respect to the segmentation performance of head&neck cancer. Methods Head&neck cancer patients underwent multi-parametric MRI including T2w, pre- and post-contrast T1w, T2*, perfusion (ktrans, ve) and diffusion (ADC) measurements at 3 time points before and during radiochemotherapy. The 7 different MRI contrasts (input channels) and manually defined gross tumor volumes (primary tumor and lymph node metastases) were used to train CNNs for lesion segmentation. A reference CNN with all input channels was compared to individually trained CNNs where one of the input channels was left out to identify which MRI contrast contributes the most to the tumor segmentation task. A statistical analysis was employed to account for random fluctuations in the segmentation performance. Results The CNN segmentation performance scored up to a Dice similarity coefficient (DSC) of 0.65. The network trained without T2* data generally yielded the worst results, with ΔDSCGTV-T = 5.7% for primary tumor and ΔDSCGTV-Ln = 5.8% for lymph node metastases compared to the network containing all input channels. Overall, the ADC input channel showed the least impact on segmentation performance, with ΔDSCGTV-T = 2.4% for primary tumor and ΔDSCGTV-Ln = 2.2% respectively. Conclusions We developed a method to reduce overall scan times in MRI protocols by prioritizing those sequences that add most unique information for the task of automatic tumor segmentation. The optimized CNNs could be used to aid in the definition of the GTVs in radiotherapy planning, and the faster imaging protocols will reduce patient scan times which can increase patient compliance. Trial registration The trial was registered retrospectively at the German Register for Clinical Studies (DRKS) under register number DRKS00003830 on August 20th, 2015.

Abstract Background Whole brain radiation therapy (WBRT) is the standard therapy for multiple brain metastases. However, WBRT has a poor local tumor control and is associated with a decline in neurocognitive function (NCF). Aim of this trial is to assess the efficacy and safety of a new treatment method, the WBRT with hippocampus avoidance (HA) combined with the simultaneous integrated boost (SIB) on metastases/resection cavities (HA-WBRT+SIB). Methods This is a prospective, randomized, two-arm phase II multicenter trial comparing the impact of HA on NCF after HA-WBRT+SIB versus WBRT+SIB in patients with multiple brain metastases. The study design is double-blinded. One hundred thirty two patients are to be randomized with a 1:1 allocation ratio. Patients between 18 and 80 years old are recruited, with at least 4 brain metastases of solid tumors and at least one, but not exceeding 10 metastases ≥5 mm. Patients must be in good physical condition and have no metastases/resection cavities in or within 7 mm of the hippocampus. Patients with dementia, meningeal disease, cerebral lymphomas, germ cell tumors, or small cell carcinomas are excluded. Previous irradiation and resection of metastases, as well as the number and size of metastases to be boosted have to comply with certain restrictions. Patients are randomized between the two treatment arms: HA-WBRT+SIB and WBRT+SIB. WBRT is to be performed with 30 Gy in 12 daily fractions and the SIB with 51 Gy/42 Gy in 12 daily fractions on 95% of volume for metastases/resection cavities. In the experimental arm, the dose to the hippocampi is restricted to 9 Gy in 98% of the volume and 17Gy in 2% of the volume. NCF testing is scheduled before WBRT, after 3 (primary endpoint), 9, 18 months and yearly thereafter. Clinical and imaging follow-ups are performed 6 and 12 weeks after WBRT, after 3, 9, 18 months and yearly thereafter. Discussion This is a protocol of a randomized phase II trial designed to test a new strategy of WBRT for preventing cognitive decline and increasing tumor control in patients with multiple brain metastases. Trial registration The HIPPORAD trial is registered with the German Clinical Trials Registry ( DRKS00004598 , registered 2 June 2016).

Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn–Zn ferrite (Mn0.6Zn0.4EuxFe2−xO4, x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for x = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high r2 relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to x = 0.15, r1 relaxivity increased significantly. On the contrary, europium substitution decreased r2 relaxivity due to a reduction in saturation magnetization. The ratio of r2/r1 decreased from 152 for the europium-free sample to 11.2 for x = 0.15, which indicates that Mn0.6Zn0.4Eu0.15Fe1.85O4 is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher r1 and lower r2 relaxivities than those of pluronic F127-coated samples.

IntroductionAn accurate delineation of the intraprostatic gross tumor volume (GTV) is of importance for focal treatment in patients with primary prostate cancer (PCa). Multiparametric MRI (mpMRI) is the standard of care for lesion detection but has been shown to underestimate GTV. This study investigated how far the GTV has to be expanded in MRI in order to reach concordance with the histopathological reference and whether this strategy is practicable in clinical routine.Patients and MethodsTwenty-two patients with planned prostatectomy and preceded 3 Tesla mpMRI were prospectively examined. After surgery, PCa contours delineated on histopathological slides (GTV-Histo) were superimposed on MRI using ex-vivo imaging as support for co-registration. According to the PI-RADSv2 classification, GTV was manually delineated in MRI (GTV-MRI) by two experts in consensus. For volumetric analysis, we compared GTV-MRI and GTV-Histo. Subsequently, we isotropically enlarged GTV-MRI in 1 mm increments within the prostate and also compared those with GTV-Histo regarding the absolute volumes. For evaluating the spatial accuracy, we considered the coverage ratio of GTV-Histo, the Sørensen–Dice coefficient (DSC), as well as the contact with the urethra.ResultsIn 19 of 22 patients MRI underestimated the intraprostatic tumor volume compared to histopathological reference: median GTV-Histo (4.7 cm3, IQR: 2.5–18.8) was significantly (p

The respiratory system is a central part of voice production as it contributes to the generation of subglottic pressure, which has an impact on voice parameters including fundamental frequency and sound pressure level. Both parameters need to be adjusted precisely during complex phonation tasks such as singing. In particular, the underlying functions of the diaphragm and rib cage in relation to the phonation of pitch jumps are not yet understood in detail. This study aims to analyse respiratory movements during phonation of pitch jumps using dynamic MRI of the lungs. Dynamic images of the breathing apparatus of 7 professional singers were acquired in the supine position during phonation of upwards and downwards pitch jumps in a high, medium, and low range of the singer's tessitura. Distances between characteristic anatomical landmarks in the lung were measured from the series of images obtained. During sustained phonation, the diaphragm elevates, and the rib cage is lowered in a monotonic manner. During downward pitch jumps the diaphragm suddenly changed its movement direction and presented with a short inspiratory activation which was predominant in the posterior part and was associated with a shift of the cupola in an anterior direction. The magnitude of this inspiratory movement was greater for jumps that started at higher compared to lower fundamental frequency. In contrast, expiratory movement of the rib cage and anterior diaphragm were simultaneous and continued constantly during the jump. The data underline the theory of a regulation of subglottic pressure via a sudden diaphragm contraction during phonation of pitch jumps downwards, while the rib cage is not involved in short term adaptations. This strengthens the idea of a differentiated control of rib cage and diaphragm as different functional units during singing phonation.

Implementation of advanced imaging techniques like multiparametric magnetic resonance imaging (mpMRI) or Positron Emission Tomography (PET) in radiation therapy (RT) planning of patients with primary prostate cancer demands several preconditions: accurate staging of the extraprostatic and intraprostatic tumor mass, robust delineation of the intraprostatic gross tumor volume (GTV) and a reproducible characterization of the prostate cancer’s biological properties. In the current review we searched for the currently available imaging techniques and we discussed their ability to fulfill these preconditions.We found that current pretreatment imaging was mainly performed with mpMRI and/or Prostate-specific membrane antigen PET imaging. Both techniques offered an accurate detection of the extraprostatic and intraprostatic tumor burden and had a major impact on RT concepts. However, some studies postulated that mpMRI and PSMA PET had complementary information for intraprostatic GTV detection. Moreover, interobserver differences for intraprostatic tumor delineation based on mpMRI were observed. It is currently unclear whether PET based GTV delineation underlies also interobserver heterogeneity. Further research is warranted to answer whether multimodal imaging is able to visualize biological processes related to prostate cancer pathophysiology and radiation resistance.

Following the publication of this article [1], the authors noticed that figures 2, 3, 4 and 5 were in the incorrect order and thus had incorrect captions.

Abstract Background To assess the effect of radiochemotherapy (RCT) on proposed tumour hypoxia marker transverse relaxation time (T2*) and to analyse the relation between T2* and 18F-misonidazole PET/CT (FMISO-PET) and 18F-fluorodeoxyglucose PET/CT (FDG-PET). Methods Ten patients undergoing definitive RCT for squamous cell head-and-neck cancer (HNSCC) received repeat FMISO- and 3 Tesla T2*-weighted MRI at weeks 0, 2 and 5 during treatment and FDG-PET at baseline. Gross tumour volumes (GTV) of tumour (T), lymph nodes (LN) and hypoxic subvolumes (HSV, based on FMISO-PET) and complementary non-hypoxic subvolumes (nonHSV) were generated. Mean values for T2* and SUVmean FDG were determined. Results During RCT, marked reduction of tumour hypoxia on FMISO-PET was observed (T, LN), while mean T2* did not change significantly. At baseline, mean T2* values within HSV-T (15 ± 5 ms) were smaller compared to nonHSV-T (18 ± 3 ms; p = 0.051), whereas FDG SUVmean (12 ± 6) was significantly higher for HSV-T (12 ± 6) than for nonHSV-T (6 ± 3; p = 0.026) and higher for HSV-LN (10 ± 4) than for nonHSV-LN (5 ± 2; p ≤ 0.011). Correlation between FMISO PET and FDG PET was higher than between FMSIO PET and T2* (R2 for GTV-T (FMISO/FDG) = 0.81, R2 for GTV-T (FMISO/T2*) = 0.32). Conclusions Marked reduction of tumour hypoxia between week 0, 2 and 5 found on FMISO PET was not accompanied by a significant T2*change within GTVs over time. These results suggest a relation between tumour oxygenation status and T2* at baseline, but no simple correlation over time. Therefore, caution is warranted when using T2* as a substitute for FMISO-PET to monitor tumour hypoxia during RCT in HNSCC patients. Trial registration DRKS, DRKS00003830 . Registered 23.04.2012.

Abstract Magnetic resonance imaging (MRI) provides excellent cross-sectional images of the soft tissues in patients. Unfortunately, MRI is intrinsically slow, it exposes patients to severe acoustic noise levels, and is limited in the visualization of certain tissues such as bone. These limitations are partly caused by the timing structure of the MRI exam which first generates the MR signal by a strong radio-frequency excitation and later acquires the weak MRI signal. Concurrent excitation and acquisition (CEA) can overcome these limitations, but is extremely challenging due to the huge intensity difference between transmit and receive signal (up to 100 dB). To suppress the strong transmit signals during signal reception, a fully automated analog cancellation unit was designed. On a 3 Tesla clinical MRI system we achieved an on-resonance analog isolation of 90 dB between the transmit and receive path, so that CEA images of the head and the extremities could be acquired with an acquisition efficiency of higher than 90% at sound pressure levels close to background noise. CEA with analog cancellation might provide new opportunities for MRI in tissues with very short T2 relaxation times, and it offers a silent and time-efficient MRI acquisition.

Abstract Background Focal radiation therapy has gained of interest in treatment of patients with primary prostate cancer (PCa). The question of how to define the intraprostatic boost volume is still open. Previous studies showed that multiparametric MRI (mpMRI) or PSMA PET alone could be used for boost volume definition. However, other studies proposed that the combined usage of both has the highest sensitivity in detection of intraprostatic lesions. The aim of this study was to demonstrate the feasibility and to evaluate the tumour control probability (TCP) and normal tissue complication probability (NTCP) of radiation therapy dose painting using 68Ga-HBED-CC PSMA PET/CT, mpMRI or the combination of both in primary PCa. Methods Ten patients underwent PSMA PET/CT and mpMRI followed by prostatectomy. Three gross tumour volumes (GTVs) were created based on PET (GTV-PET), mpMRI (GTV-MRI) and the union of both (GTV-union). Two plans were generated for each GTV. Plan95 consisted of whole-prostate IMRT to 77 Gy in 35 fractions and a simultaneous boost to 95 Gy (Plan95PET/Plan95MRI/Plan95union). Plan80 consisted of whole-prostate IMRT to 76 Gy in 38 fractions and a simultaneous boost to 80 Gy (Plan80PET/Plan80MRI/Plan80union). TCPs were calculated for GTV-histo (TCP-histo), which was delineated based on PCa distribution in co-registered histology slices. NTCPs were assessed for bladder and rectum. Results Dose constraints of published protocols were reached in every treatment plan. Mean TCP-histo were 99.7% (range: 97%–100%) and 75.5% (range: 33%–95%) for Plan95union and Plan80union, respectively. Plan95union had significantly higher TCP-histo values than Plan95MRI (p = 0.008) and Plan95PET (p = 0.008). Plan80union had significantly higher TCP-histo values than Plan80MRI (p = 0.012), but not than Plan80PET (p = 0.472). Plan95MRI had significantly lower NTCP-rectum than Plan95union (p = 0.012). No significant differences in NTCP-rectum and NTCP-bladder were observed for all other plans (p > 0.05). Conclusions IMRT dose escalation on GTVs based on mpMRI, PSMA PET/CT and the combination of both was feasible. Boosting GTV-union resulted in significantly higher TCP-histo with no or minimal increase of NTCPs compared to the other plans.

Abstract Background We hypothesized that dominant intraprostatic lesions (DILs) could be depictured by multimodal imaging techniques (MRI and/or PSMA PET/CT) in patients with primary prostate cancer (PCa) and investigated possible effects of radiotherapy (RT) dose distribution within the DILs on the patients’ outcome. Methods One hundred thirty-eight patients with localized prostate cancer (PCa) and visible DIL underwent primary external beam RT between 2008 and 2016 with an aimed prescription dose of 76 Gy to the whole prostate. Seventy-five patients (54%) additionally received androgen deprivation therapy. Three volumes were retrospectively generated: DIL using pretreatment MRI and/or PSMA PET/CT, prostatic gland (PG) and the subtraction between PG and DIL (SPG). The minimum dose (Dmin), maximum dose (Dmax) and mean dose (Dmean) in the three respective volumes were calculated. Biochemical recurrence free survival (BRFS) was considered in uni- and multivariate Cox regression analyses. An explorative analysis was performed to determine cut-off values for the three dose parameters in the three respective volumes. Results With a median follow-up of 45 months (14–116 months) 15.9% of patients experienced BR. Dmin (cut-off: 70.6 Gy, HR = 0.39, p = 0.036) applied to the DIL had an impact on BRFS in multivariate analysis, in contrast to the Dmin delivered to PG and SPG which had no significant impact (p > 0.05). Dmin was significantly (p 0.05). Conclusions The dose distribution within DILs defined by PSMA PET/CT and/or MRI is an independent risk factor for BR after primary RT in patients with PCa. These findings support the implementation of imaging based DIL interpretation for RT treatment planning, although further validation in larger patient cohorts with longer follow-up is needed.

The Land Suitability Rating System (LSRS) is a rule-based set of algorithms that integrate soil, climate and landscape factors to calculate a classed suitability rating for a given landscape to support commercial field crop production. The attributes used to define each of the factors are based on their proven ability to affect crop growth, their ability to be measured (or estimated by proxy) and their availability in accessible databases. The LSRS was first published in 1995 by Agriculture and Agri-Food Canada as a site-specific, manual calculator for spring-seeded small grains that incorporated sets of attribute point deduction curves based on expert knowledge. Since that time the system has been expanded to include additional crop modules and all data handling and calculations are automated through a set of web-based applications. The current version of LSRS (version 5) is implemented in Ruby on Rails® software as a suite of web services. The system runs against any soil map with standardized Canadian Soil Information Service soil data tables to process soil attributes and calculate limitations to crop growth. A climate factor rating is based on crop-specific agro-climatic indices and thresholds. Climatic indices have historically been calculated from 30-year climate normal periods using monthly data but LSRS can now also utilize daily data records which facilitate trend analyses within annual historic records. The use of available gridded climate datasets enables direct overlay and extraction of climate attributes to the spatial extent of soil map polygons. Lastly, the system incorporates a landscape factor related to land erodibility and constraints to management. Each of the three suitability factors is assigned a class rating between 1 (no limitations) and 7 (unsuitable) with the final overall rating being the most limiting of the three factors. Recent improvements in the ability of the system to process multiple climate datasets mean outputs from Global Circulation Models may also be useful for the LSRS model in assessing possible impacts of climate change on crop suitability. LSRS is used increasingly as a spatial research tool in assessing potential changes in crop distributions at both national and regional scales.

Evaluation of recurrent angina after percutaneous coronary interventions is challenging. Since bioresorbable vascular scaffolds (BVS) cause no artefacts in magnetic resonance imaging (MRI) due to their polylactate-based backbone, evaluation of vascular patency by MRI might allow for non-invasive assessment and triage of patients with suspected BVS failure.Patients with polylactate-based ABSORB-BVS in proximal coronary segments were examined with 3 Tesla MRI directly (baseline) and one year after implantation. For assessment of coronary patency, a high-resolution 3D spoiled gradient echo pulse sequence with fat-saturation, T2-preparation (TE: 40 ms), respiratory and end-diastolic cardiac gating, and a spatial resolution of (1.08 mm)3 was positioned parallel to the course of the vessel for bright blood imaging. In addition, a 3D navigator-gated T2-weighted variable flip angle turbo spin echo (TSE) sequence with dual-inversion recovery black-blood preparation and elliptical k-space coverage was applied with a voxel size of (1.14 mm)3. For quantitative evaluation lumen diameters of the scaffolded areas were measured in reformatted bright and black blood MR angiography data.11 patients with implantation of 16 BVS in the proximal coronary segments were included, of which none suffered from major adverse cardiac events during the one year follow up. Vascular patency in all segments implanted with BVS could be reliably assessed by MRI at baseline and after one year, whereas segments with metal stents could not be evaluated due to artefacts. Luminal diameter within the BVS remained constant during the one year period. One patient with atypical angina after BVS implantation was noninvasively evaluated showing a patent vessel, also confirmed by coronary angiography.Coronary MRI allows contrast-agent free and non-invasive assessment of vascular patency after ABSORB-BVS implantation. This approach might be supportive in the triage and improvement of diagnostic workflows in patients with postinterventional angina and scaffold implantation.German Register of Clinical Studies DRKS00007456.

Reference genes (RG) as sample internal controls for gene transcript level analyses by quantitative RT-PCR (RT-qPCR) must be stably expressed within the experimental range. A variety of in vitro cell culture settings with primary human hepatocytes, and Huh-7 and HepG2 cell lines, were used to determine candidate RG expression stability in RT-qPCR analyses. Employing GeNorm, BestKeeper and Normfinder algorithms, this study identifies PSMB6, MDH1 and some more RG as sufficiently unregulated, thus expressed at stable levels, in hepatocyte-like cells in vitro. Inclusion of multiple RG, quenching occasional regulations of single RG, greatly stabilises gene expression level calculations from RT-qPCR data. To further enhance validity and reproducibility of relative RT-qPCR quantifications, the ΔCT calculation can be extended (e-ΔCT) by replacing the CT of a single RG in ΔCT with an averaged CT-value from multiple RG. The use of two or three RG--here identified suited for human hepatocyte-like cells--for normalisation with the straightforward e-ΔCT calculation, should improve reproducibility and robustness of comparative RT-qPCR-based gene expression analyses.