Min Scan Research Articles

18F]-Florbetaben PET/CT for Differential Diagnosis Among Cardiac Immunoglobulin Light Chain, Transthyretin Amyloidosis, and Mimicking Conditions

ObjectivesThis study aimed to test the diagnostic value of [18F]–florbetaben positron emission tomography (PET) in patients with suspicion of CA. BackgroundDiagnosis of cardiac involvement in immunoglobulin light-chain–derived amyloidosis (AL) and transthyretin-related amyloidosis (ATTR), which holds major importance in risk stratification and decision making, is frequently delayed. Furthermore, although diphosphonate radiotracers allow a noninvasive diagnosis of ATTR, demonstration of cardiac amyloidosis (CA) in AL may require endomyocardial biopsy. MethodsForty patients with biopsy-proven diagnoses of CA (20 ALs, 20 ATTRs) and 20 patients referred with the initial clinical suspicion and later diagnosed with non-CA pathology underwent a cardiac PET/computed tomography scan with a 60-min dynamic [18F]-florbetaben PET acquisition, and 4 10-min static scans at 5, 30, 50, and 110 min after radiotracer injection. ResultsVisual qualitative assessment showed intense early cardiac uptake in all subsets. Patients with AL displayed a high, persistent cardiac uptake in all the static scans, whereas patients with ATTR and those with non-CA showed an uptake decrease soon after the early scan. Semiquantitative assessment demonstrated higher mean standardized uptake value (SUVmean) in patients with AL, sustained over the whole acquisition period (early SUVmean: 5.55; interquartile range [IQR]: 4.00 to 7.43; vs. delayed SUVmean: 3.50; IQR: 2.32 to 6.10; p = NS) compared with in patients with ATTR (early SUVmean: 2.55; IQR: 1.80 to 2.97; vs. delayed SUVmean: 1.25; IQR: 0.90 to 1.60; p < 0.001) and in patients with non-CA (early SUVmean: 3.50; IQR: 1.60 to 3.37; vs. delayed SUVmean: 1.40; IQR: 1.20 to 1.60; p < 0.001). Similar results were found comparing heart-to-background ratio and molecular volume. ConclusionsDelayed [18F]-florbetaben cardiac uptake may discriminate CA due to AL from either ATTR or other mimicking conditions. [18F]-florbetaben PET/computed tomography may represent a promising noninvasive tool for the diagnosis of AL amyloidosis, which is still often challenging and delayed. (A Prospective Triple-Arm, Monocentric, Phase-II Explorative Study on Evaluation of Diagnostic Efficacy of the PET Tracer [18F]-Florbetaben [Neuraceq] in Patients With Cardiac Amyloidosis [FLORAMICAR2]; EudraCT number: 2017-001660-38)

Pushing the temporal resolution in absorption and Zernike phase contrast nanotomography: enabling fast in situ experiments.

Hard X-ray nanotomography enables 3D investigations of a wide range of samples with high resolution (<100 nm) with both synchrotron-based and laboratory-based setups. However, the advantage of synchrotron-based setups is the high flux, enabling time resolution, which cannot be achieved at laboratory sources. Here, the nanotomography setup at the imaging beamline P05 at PETRA III is presented, which offers high time resolution not only in absorption but for the first time also in Zernike phase contrast. Two test samples are used to evaluate the image quality in both contrast modalities based on the quantitative analysis of contrast-to-noise ratio (CNR) and spatial resolution. High-quality scans can be recorded in 15 min and fast scans down to 3 min are also possible without significant loss of image quality. At scan times well below 3 min, the CNR values decrease significantly and classical image-filtering techniques reach their limitation. A machine-learning approach shows promising results, enabling acquisition of a full tomography in only 6 s. Overall, the transmission X-ray microscopy instrument offers high temporal resolution inabsorption and Zernike phase contrast, enabling in situ experiments at thebeamline.

Provisioning of live black soldier fly larvae (Hermetia illucens) benefits broiler activity and leg health in a frequency- and dose-dependent manner

Fast-growing broilers spend most their time inactive and are therefore prone to experience leg problems. Environmental enrichment that facilitates intrinsically motivated behaviours can potentially promote activity and reduce leg problems, thereby improving broiler welfare. A promising environmental enrichment method is the scattering of desired feed items, such as insects, which are highly attractive to broilers. We studied the effect of providing live black soldier fly larvae (BSFL) scattered on the litter on broiler behaviour, leg health and performance. One-day-old male broilers were assigned to one of five treatments (eight pens/treatment, nine broilers/pen): a control without BSFL and four treatments with BSFL provided from day 1 onwards in different amounts (5 % or 10 % of estimated dietary dry matter intake; A5 and A10 respectively) and frequencies (two or four times a day; F2 and F4 respectively). All broilers were fed diets formulated to ensure a similar energy and nutrient intake. Broiler weight and leg health were determined on day 42. The behavioural time budget was determined weekly by observations for 7 h per day using 12-min scan sampling, and activity around larval provisioning was determined by 3-min scan sampling from 9 min before, until 27 min after larval provisioning on day 15/16, 29/30 and 40/41. Broilers in all larval provisioning treatments had a different behavioural time budget than controls, with significantly higher levels of foraging behaviour, walking, standing idle and general activity during at least three of the five observation days (p < 0.05 compared to controls). The increase in activity was numerically highest and most long-term in A10F4 broilers. Time spent active and in standing posture declined from week 4 onwards in A10F4, whereas for all other treatments this decline occurred already in week 2. Activity during 30 min after larval provisioning was higher for A10 than A5 treatments (p < 0.05 for all days) but overall not affected by frequency of larval provisioning. Hock burn occurred less in A10 birds than in controls (p < 0.05), and lameness occurred less in A10 and A5F4 birds than in controls (p < 0.01). Only A10F2 birds had a lower final weight than controls (p < 0.05). In conclusion, the largest amount combined with the highest frequency of larval provisioning applied in this study resulted in the most prominent increase in activity and better leg health, without significantly affecting broiler performance. Further investigation into BSFL provisioning methods is required to determine the optimal method for achieving improved broiler welfare.

Clinical validation of the novel HDAC6 radiotracer [18F]EKZ-001 in the human brain

PurposeHistone deacetylase 6 (HDAC6) is a cytoplasmic enzyme that modulates intracellular transport and protein quality control. Inhibition of HDAC6 deacetylase activity has shown beneficial effects in disease models, including Alzheimer’s disease and amyotrophic lateral sclerosis. This first-in-human positron emission tomography (PET) study evaluated the brain binding of [18F]EKZ-001 ([18F]Bavarostat), a radiotracer selective for HDAC6, in healthy adult subjects.MethodsBiodistribution and radiation dosimetry studies were performed in four healthy subjects (2M/2F, 23.5 ± 2.4 years) using sequential whole-body PET/CT. The most appropriate kinetic model to quantify brain uptake was determined in 12 healthy subjects (6M/6F, 57.6 ± 3.7 years) from 120-min dynamic PET/MR scans using a radiometabolite-corrected arterial plasma input function. Four subjects underwent retest scans (2M/2F, 57.3 ± 5.6 years) with a 1-day interscan interval to determine test-retest variability (TRV). Regional volume of distribution (VT) was calculated using one-tissue and two-tissue compartment models (1-2TCM) and Logan graphical analysis (LGA), with time-stability assessed. VT differences between males and females were evaluated using volume of interest and whole-brain voxel-wise approaches.ResultsThe effective dose was 39.1 ± 7.0 μSv/MBq. Based on the Akaike information criterion, 2TCM was the preferred model compared to 1TCM. Regional LGA VT were in agreement with 2TCM VT, however demonstrated a lower absolute TRV of 7.7 ± 4.9%. Regional VT values were relatively homogeneous with highest values in the hippocampus and entorhinal cortex. Reduction of acquisition time was achieved with a 0 to 60-min scan followed by a 90 to 120-min scan. Males demonstrated significantly higher VT than females in the majority of cortical and subcortical brain regions. No relevant radiotracer related adverse events were reported.Conclusion[18F]EKZ-001 is safe and appropriate for quantifying HDAC6 expression in the human brain with Logan graphical analysis as the preferred quantitative approach. Males showed higher HDAC6 expression across the brain compared to females.

3D whole-heart isotropic-resolution motion-compensated joint T1 /T2 mapping and water/fat imaging.

To develop a free-breathing isotropic-resolution whole-heart joint T1 and T2 mapping sequence with Dixon-encoding that provides coregistered 3D T1 and T2 maps and complementary 3D anatomical water and fat images in a single ~9 min scan. Four interleaved dual-echo Dixon gradient echo volumes are acquired with a variable density Cartesian trajectory and different preparation pulses: 1) inversion recovery-preparation, 2) and 3) no preparations, and 4) T2 preparation. Image navigators are acquired to correct each echo for 2D translational respiratory motion; the 8 echoes are jointly reconstructed with a low-rank patch-based reconstruction. A water/fat separation algorithm is used to obtain water and fat images for each acquired volume. T1 and T2 maps are generated by matching the signal evolution of the water images to a simulated dictionary. Complementary bright-blood and fat volumes for anatomical visualization are obtained from the T2 -prepared dataset. The proposed sequence was tested in phantom experiments and 10 healthy subjects and compared to standard 2D MOLLI T1 mapping, 2D balance steady-state free precession T2 mapping, and 3D T2 -prepared Dixon coronary MR angiography. High linear correlation was found between T1 and T2 quantification with the proposed approach and phantom spin echo measurements (y = 1.1 × -11.68, R2 = 0.98; and y = 0.85 × +5.7, R2 = 0.99). Mean myocardial values of T1 /T2 = 1116 ± 30.5 ms/45.1 ± 2.38 ms were measured in vivo. Biases of T1 /T2 = 101.8 ms/-0.77 ms were obtained compared to standard 2D techniques. The proposed joint T1 /T2 sequence permitted the acquisition of motion-compensated isotropic-resolution 3D T1 and T2 maps and complementary coronary MR angiography and fat volumes, showing promising results in terms of T1 and T2 quantification and visualization of cardiac anatomy and pericardial fat.

Narrow linewidth erbium-doped fiber laser incorporating with photonic crystal fiber based Fabry–Pérot interferometer for temperature sensing applications

We propose a narrow linewidth ring cavity erbium-doped fiber laser based on a photonic crystal fiber (PCF) based Fabry–Pérot interferometer (F–P). A 5.2-m-long erbium-doped fiber was used in the resonant cavity as gain medium. The F–P was fabricated by cascaded with single-mode fiber and 2 mm length PCF as the interferometer filter, and the interferometer period was 0.58 nm. The laser threshold was 57 mW in the experiment, and 1573.99 nm narrow linewidth lasing was realized and 3 dB linewidth was 0.2 nm. Single wavelength laser temperature sensing was implemented by heating and cooling the F–P filter. In the experiment, single-wavelength lasing could be tuned from 1573.25–1574.27 nm within 40–120 ℃, with 12.6 pm/℃ sensitivity, power fluctuation was lower than 1.78 dB, and linearity was more than 0.996. The single-wavelength laser temperature stability was tested, and power fluctuation was less than 0.819 dB within 25 min scan time. In addition, four different dual-wavelength lasers could be obtained with power shift less than 1.187 dB.

Evolution of a pyrocumulonimbus event associated with an extreme wildfire in Tasmania, Australia

Abstract. Extreme fires have substantial adverse effects on society and natural ecosystems. Such events can be associated with the intense coupling of fire behaviour with the atmosphere, resulting in extreme fire characteristics such as pyrocumulonimbus cloud (pyroCb) development. Concern that anthropogenic climate change is increasing the occurrence of pyroCbs globally is driving more focused research into these meteorological phenomena. Using 6 min scans from a nearby weather radar, we describe the development of a pyroCb during the afternoon of 4 January 2013 above the Forcett–Dunalley fire in south-eastern Tasmania. We relate storm development to (1) near-surface weather using the McArthur forest fire danger index (FFDI) and the C-Haines index, the latter of which is a measure of the vertical atmospheric stability and dryness, both derived from gridded weather reanalysis for Tasmania (BARRA-TA); and (2) a chronosequence of fire severity derived from remote sensing. We show that the pyroCb rapidly developed over a 24 min period on the afternoon of 4 January, with the cloud top reaching a height of 15 km. The pyroCb was associated with a highly unstable lower atmosphere (C-Haines value of 10–11) and severe–marginally extreme (FFDI 60–75) near-surface fire weather, and it formed over an area of forest that was severely burned (total crown defoliation). We use spatial patterns of elevated fire weather in Tasmania and fire weather during major runs of large wildfires in Tasmania for the period from 2007 to 2016 to geographically and historically contextualise this pyroCb event. Although the Forcett–Dunalley fire is the only known record of a pyroCb in Tasmania, our results show that eastern and south-eastern Tasmania are prone to the conjunction of high FFDI and C-Haines values that have been associated with pyroCb development. Our findings have implications for fire weather forecasting and wildfire management, and they highlight the vulnerability of south-east Tasmania to extreme fire events.

In situ characterization of foam morphology during melting of simulated waste glass using x-ray computed tomography

During batch-to-glass conversion, a glass-forming melt connects, creating a foam layer between the batch and the glass melt. Due to its transience and opacity, investigation of this foam layer presents a formidable challenge. In this work, we use in situ x-ray computed tomography to characterize the foam morphology that evolves during batch-to-glass conversion of a simulated nuclear waste glass. Rapid 1-min scans with 38 μm voxels were performed to capture the foam structure during heating. Geometric volume, total porosity, and bubble size distribution are reported. Using evolved gas analysis and combining the temperature-dependent melt viscosity with x-ray data, we describe the evolution of foam structure during the foam growth and subsequent collapse.

68Ga-PSMA-11 dose reduction for dedicated pelvic imaging with simultaneous PET/MR using TOF BSREM reconstructions.

When increasing the PET acquisition time to match the longer MRI protocol in simultaneous PET/MR, the injected PET tracer dose can possibly be lowered to reduce radiation exposure. Moreover, applying new commercially available time-of-flight (TOF) block sequential regularized expectation maximization (BSREM)-based reconstruction algorithms could allow for further dose reductions. The purpose of this study was to find the minimal dose of the tracer targeting the prostate specific membrane antigen (68Ga-PSMA-11) for a dedicated 15-min pelvic PET/MR scan that still matches the image quality of a reference 3-min scan at 100% (150MBq) dose. In this retrospective analysis, 25 patients were included. PET emission datasets were edited to simulate stepwise reductions of injected tracer dose. Reference TOF ordered subset expectation maximum (OSEM) and new TOF BSREM reconstructions were performed and differences in the resulting PET images were visually and quantitatively assessed. Visually, TOF BSREM reconstructions with relatively high regularization parameter (β) values are preferred. Quantitatively, however, high β-values result in lower lesion maximum standardized uptake values (SUVmax) compared to the reference. A β-value of 550 was considered the optimal compromise for the lowest possible 10% dose reconstructions, resulting in comparable visual assessment and lesion SUVmax. This study indicates that the injected 68Ga-PSMA-11 tracer dose for a standard 3-min PET scan can be reduced to approximately 10% (15MBq) when the PET acquisition time is matched to the 15-min pelvic MRI protocol, and when reconstructed with TOF BSREM using β = 550. This decreases the effective dose from 3.54 to 0.35mSv. • Low-dose dedicated pelvic68Ga-PSMA-11 PET/MR reduces radiation exposure for patients. • Retrospective study investigating the minimal dose needed for adequate image quality for 15-min PET frames over the pelvis showed using quantitative and qualitative analysis that a substantial dose reduction is possible without significant loss of image quality when using the TOF BSREM reconstruction algorithm. • With the introduction of low-dose pelvic68Ga-PSMA-11 PET/MR, new potential applications of68Ga-PSMA-11 PET for local staging or investigation of equivocal MRI findings could become applicable, even for patients without confirmed prostate cancer.

Reconstructed spatial resolution and contrast recovery with Bayesian penalized likelihood reconstruction (Q.Clear) for FDG-PET compared to time-of-flight (TOF) with point spread function (PSF)

BackgroundBayesian penalized likelihood reconstruction for PET (e.g., GE Q.Clear) aims at improving convergence of lesion activity while ensuring sufficient signal-to-noise ratio (SNR). This study evaluated reconstructed spatial resolution, maximum/peak contrast recovery (CRmax/CRpeak) and SNR of Q.Clear compared to time-of-flight (TOF) OSEM with and without point spread function (PSF) modeling.MethodsThe NEMA IEC Body phantom was scanned five times (3 min scan duration, 30 min between scans, background, 1.5–3.9 kBq/ml F18) with a GE Discovery MI PET/CT (3-ring detector) with spheres filled with 8-, 4-, or 2-fold the background activity concentration (SBR 8:1, 4:1, 2:1). Reconstruction included Q.Clear (beta, 150/300/450), “PSF+TOF4/16” (iterations, 4; subsets, 16; in-plane filter, 2.0 mm), “OSEM+TOF4/16” (identical parameters), “PSF+TOF2/17” (2 it, 17 ss, 2.0 mm filter), “OSEM+TOF2/17” (identical), “PSF+TOF4/8” (4 it, 8 ss, 6.4 mm), and “OSEM+TOF2/8” (2 it, 8 ss, 6.4 mm). Spatial resolution was derived from 3D sphere activity profiles. RC as (sphere activity concentration [AC]/true AC). SNR as (background mean AC/background AC standard deviation).ResultsSpatial resolution of Q.Clear150 was significantly better than all conventional algorithms at SBR 8:1 and 4:1 (Wilcoxon, each p < 0.05). At SBR 4:1 and 2:1, the spatial resolution of Q.Clear300/450 was similar or inferior to PSF+TOF4/16 and OSEM+TOF4/16. Small sphere CRpeak generally underestimated true AC, and it was similar for Q.Clear150/300/450 as with PSF+TOF4/16 or PSF+TOF2/17 (i.e., relative differences < 10%). Q.Clear provided similar or higher CRpeak as OSEM+TOF4/16 and OSEM+TOF2/17 resulting in a consistently better tradeoff between CRpeak and SNR with Q.Clear. Compared to PSF+TOF4/8/OSEM+TOF2/8, Q.Clear150/300/450 showed lower SNR but higher CRpeak.ConclusionsQ.Clear consistently improved reconstructed spatial resolution at high and medium SBR compared to PSF+TOF and OSEM+TOF, but only with beta = 150. However, this is at the cost of inferior SNR with Q.Clear150 compared to Q.Clear300/450 and PSF+TOF4/16/PSF+TOF2/17 while CRpeak for the small spheres did not improve considerably. This suggests that Q.Clear300/450 may be advantageous for the 3-ring detector configuration because the tradeoff between CR and SNR with Q.Clear300/450 was superior to PSF+TOF4/16, OSEM+TOF4/16, and OSEM+TOF2/17. However, it requires validation by systematic evaluation in patients at different activity and acquisition protocols.

An Evaluation of the GOES-16 Rapid Scan for Nowcasting in Southeastern Brazil: Analysis of a Severe Hailstorm Case

Abstract The GOES-16 mesoscale domain sector (MDS) scans with 1-min intervals are used in this study to analyze a severe thunderstorm case that occurred in southeastern Brazil. The main objective is to evaluate the GOES-16 MDS rapid scans against the operational full-disk scans with lower temporal resolution for nowcasting. Data from a C-band radar, observed sounding, and a ground-based lightning network are also used in the analysis. A group of thunderstorms formed in the afternoon of 29 November 2017 in an environment of moderate convective available potential energy (CAPE) and deep-layer shear. The storms presented supercell characteristics and intense lightning activity with peak rates in excess of 150 flashes per 5 min. The satellite-derived trends with 1-min interval were skillful in detecting thunderstorm intensification, mainly in the developing stage. The decrease in cloud-top 10.35-μm brightness temperature was accompanied by increases in ice mass flux, concentration of small ice particles at cloud top, and storm depth. In the mature stage, there is no evident trend in the satellite-derived parameters that could indicate storm intensification, but the cluster area expands suggesting cloud-top divergence. The 1-min rapid scans indicate greater lead time to severe weather relative to 10- and 15-min-resolution imagery, but also presented numerous false alarms (indication of severe weather but no occurrence) due to oscillations in the satellite-derived parameters. The parameters calculated every 5 min presented better skill than 10 and 15 min and fewer false alarms than 1 min.

Dipole modeling of multispectral signal for detecting metallic biopsy markers during MRI-guided breast biopsy: a pilot study.

During MRI-guided breast biopsy, a metallic biopsy marker is deployed at the biopsy site to guide future interventions. Conventional MRI during biopsy cannot distinguish such markers from biopsy site air, and a post-biopsy mammogram is therefore performed to localize marker placement. The purpose of this pilot study is to develop dipole modeling of multispectral signal (DIMMS) as an MRI alternative to eliminate the cost, inefficiency, inconvenience, and ionizing radiation of a mammogram for biopsy marker localization. DIMMS detects and localizes the biopsy marker by fitting the measured multispectral imaging (MSI) signal to the MRI signal model and marker properties. MSI was performed on phantoms containing titanium biopsy markers and air to illustrate the clinical challenge that DIMMS addresses and on 20 patients undergoing MRI-guided breast biopsy to assess DIMMS feasibility for marker detection. DIMMS was compared to conventional MSI field map thresholding, using the post-procedure mammogram as the reference standard. Biopsy markers were detected and localized in 20 of 20 cases using MSI with automated DIMMS post-processing (using a threshold of 0.7) and in 18 of 20 cases using MSI field mapping (using a threshold of 0.65 kHz). MSI with DIMMS post-processing is a feasible technique for biopsy marker detection and localization during MRI-guided breast biopsy. With a 2-min MSI scan, DIMMS is a promising MRI alternative to the standard-of-care post-biopsy mammogram.

Prototype detector for intraoperative PET-laparoscope system with a multi-layer movable detector

Intraoperative PET-laparoscope system has been proposed to locate lymph node metastasis during gastric cancer surgery. The proposed system consists of an external detector array connected to a patient’s surgical bed and a movable detector probe which is inserted into the patient’s stomach along with a laparoscope. In this study a prototype detector for the PET-laparoscope system is presented with a pixelated movable detector probe tracked by an optical tracking system. Detector prototype reconstructed images of a 22Na source with 3 mm spatial resolution in X (coronal) and Z (longitudinal) directions in a 2 min scan. The use of the pixelated multi-layer movable detector probe improved the spatial resolution of the system.

Multi-wavelength switchable erbium-doped fiber laser based on a hybrid filter incorporating a bi-tapered Mach–Zehnder interferometer and Sagnac loop

A multi-wavelength switchable C-band erbium-doped fiber laser based on a hybrid comb filter composed of a Sagnac loop and Mach–Zehnder interferometer (MZI) is designed and experimentally demonstrated. In the designed ring cavity fiber laser, the MZI is composed of bi-tapered single-mode fiber fabricated by etching with hydrofluoric acid. In the experiment, the wavelength intervals in the comb spectra of the Sagnac loop and MZI are 3.4 and 18.8 nm, respectively, and by combining the Sagnac loop and MZI, measurements of the hybrid comb spectrum are obtained. When the pump power is 91 mW, lasing occurs at 1529.2 nm. Adjustment of the variable attenuator (VA) can provide 1541.9 and 1558.6 nm single-wavelength switchable lasers, for which the maximum peak power difference is less than 3.59 dB, the signal-to-noise ratio (SNR) exceeds 19.25 dB, and the peak power fluctuation is less than 0.34 dB over a 30 min scan time at 26 °C. For dual-wavelength switchable laser emission, four different sets of wavelengths can be realized, and the SNR exceeds 15.57 dB with power fluctuations of less than 1.6 dB, under the same monitoring conditions. By further adjusting the VA, stable and tunable triple-wavelength lasing is also realizable; under these conditions, the SNR exceeds 15.02 dB and the power fluctuation is less than 0.91 dB. Furthermore, four- and five-wavelength lasing can also be achieved by adjusting the VA again, with SNRs exceeding 19.05 and 14.98 dB, respectively.

Reaction to allospecific death and to an unanimated gorilla infant in wild western gorillas: insights into death recognition and prolonged maternal carrying.

It is still unclear to what extent animals possess knowledge of death. Primates display a large variety and often contradictory behaviors toward conspecific corpses, particularly those of infants (e.g., prolonged carrying and care). This study reports on reactions in a wild, habituated western gorilla group (Gorilla gorilla, 11-13 individuals) in the Central African Republic to an unanimated conspecific infant, and to an allospecific corpse. Individuals' reactions were compared to their usual behavior using both continuous focal animal sampling and 10-min instantaneous scan sampling. In the first observation, an infant gorilla fell out of a tree and looked dead. The mother retrieved it and remained unusually close to another adult female, until the infant started to move again, almost 1 h later. Cases of infants regaining consciousness after almost-fatal accidents may act as positive reinforcement for continued carrying by mothers, which might be socially learned. In the second case, three immature gorillas reacted to a dead red river hog. For 20min they stared at the corpse from tree branches above, while chest beating, defecating, and urinating several times. They showed fear and did not approach the corpse. These observations show that non-predatory species, such as gorillas, may be able to acquire and develop some knowledge about death even though they do not kill other vertebrates.

107. Internal deformations in human intervertebral discs under axial compression: a 9.4T MRI study

BACKGROUND CONTEXT Back pain will be experienced by 70-85% of all people at some point in their lives, and is linked with intervertebral disc (IVD) degeneration. However, few studies have attempted to quantify changes in the internal deformations within IVDs as they degenerate without disrupting the disc continuity. Recent advances in MRI technology provide the opportunity to observe 3D deformations within intact IVDs in unprecedented detail. PURPOSE The aim of this study was to quantify human IVD deformations under axial compression. STUDY DESIGN/SETTING 9.4T MRI images were obtained of human cadaveric motion segments under pure axial loading. PATIENT SAMPLE Four human vertebral body–IVD–vertebral body specimens (L4-L5) were used for this study. Two were classed as degenerate (age = 55.5 ± 3.5 years (average ± SD), Pfirrmann rank = 3.5 ± 0.4) and two were classified as nondegenerate (age = 24.0 ± 2.8 years, Pfirrmann rank = 2.0 ± 0.3). OUTCOME MEASURES Digital volume correlation (DVC) was used to calculate the 3D strains within the IVDs. METHODS Specimens were aligned with the transverse plane of the disc parallel to the base of the mounting pots of a custom-made compression rig, and fixed in place using polymethylmethacrylate (PMMA). MR Images were acquired before, and after 2 mm of compression using a T2-weighted RARE sequence (coronal plane, resolution = (90 × 90) µm2, slice thickness = 800 µm, 17 min scan time). RESULTS High lateral strains were seen in the AF regions of the nondegenerate discs, while high lateral strains were seen in both the AF and the NP of the degenerate discs, particularly close to the end plates. The axial strain in both the NP and AF of the degenerate specimens was significantly higher (two tailed, unpaired t-test, p CONCLUSIONS This is the first study to use high field MRI to obtain images with in plane resolution as high as (90 × 90) µm2 to investigate internal deformations within degenerate and nondegenerate human discs. The 3D strain maps are useful for designers of partial or total disc replacement technologies who aim to restore the mechanical behavior of degenerate discs back to their nondegenerate state. Future investigations into 3D strains under different modes of loading will inform physical activities to mitigate high IVD strains, and the optimization of rigid instrumentation for fusion surgery by ensuring that modes of loading associated with the highest IVD strains are minimized. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Optimization of parathyroid 11C-choline PET protocol for localization of parathyroid adenomas in patients with primary hyperparathyroidism

PurposeTo evaluate the optimal tracer uptake time, the minimal amount of radioactivity and the inter-observer agreement for 11C-choline positron emission tomography/computed tomography (PET/CT) in patients with primary hyperparathyroidism (pHPT).MethodsTwenty-one patients with biochemically proven pHPT were retrospectively studied after injection of 6.3 ± 1.2 MBq/kg 11C-choline. PET data of the first nine patients, scanned for up to 60 min, were reconstructed in 10-min frames from 10- to 60-min postinjection (p.i.), mimicking varying 11C-choline uptake times. Parathyroid adenoma to background contrast ratios were calculated and compared, using standardized uptake values (SUVs). Data was reconstructed with varying scan durations (1, 2.5, 5, and 10 min) at 20–30-min p.i. (established optimal uptake time), mimicking less administered radioactivity. To establish the minimal required radioactivity, the SUVs in the shorter scan durations (1, 2.5, and 5 min) were compared to the 10-min scan duration to determine whether increased variability and/or statistical differences were observed. Four observers analyzed the 11C-choline PET/CT in four randomized rounds for all patients.ResultsSUVpeak of the adenoma decreased from 30 to 40 p.i. onwards. All adenoma/background contrast ratios did not differ from 20- to 30-min p.i. onwards. The SUVs of adenoma in the scan duration of 1, 2.5, and 5 min all differed significantly from the same SUV in the 10-min scan duration (all p = 0.012). However, the difference in absolute SUV adenoma values was well below 10% and therefore not considered clinically significant. The inter-observer analysis showed that the Fleiss’ kappa of the 1-min scan were classified as “moderate,” while these values were classified as “good” in the 2.5-, 5-, and 10-min scan duration. Observers scored lower certainty scores in the 1- and 2.5-min scans compared to the 5- and 10-min scan durations.ConclusionThe optimal time to start PET/CT scanning in patients with pHPT is 20 min after mean injection of 6.3 MBq/kg 11C-choline, with a recommended scan duration of at least 5 min. Alternatively, the radioactivity dose can be lowered by 50% while keeping a 10-min scan duration without losing the accuracy of 11C-choline PET/CT interpretation.

Cortical bone vessel identification and quantification on contrast-enhanced MR images

Cortical bone porosity is a major determinant of bone strength. Despite the biomechanical importance of cortical bone porosity, the biological drivers of cortical porosity are unknown. The content of cortical pore space can indicate pore expansion mechanisms; both of the primary components of pore space, vessels and adipocytes, have been implicated in pore expansion. Dynamic contrast-enhanced MRI (DCE-MRI) is widely used in vessel detection in cardiovascular studies, but has not been applied to visualize vessels within cortical bone. In this study, we have developed a multimodal DCE-MRI and high resolution peripheral QCT (HR-pQCT) acquisition and image processing pipeline to detect vessel-filled cortical bone pores. For this in vivo human study, 19 volunteers (10 males and 9 females; mean age =63±5) were recruited. Both distal and ultra-distal regions of the non-dominant tibia were imaged by HR-pQCT (82 µm nominal resolution) for bone structure segmentation and by 3T DCE-MRI (Gadavist; 9 min scan time; temporal resolution =30 sec; voxel size 230×230×500 µm3) for vessel visualization. The DCE-MRI was registered to the HR-pQCT volume and the voxels within the MRI cortical bone region were extracted. Features of the DCE data were calculated and voxels were categorized by a 2-stage hierarchical kmeans clustering algorithm to determine which voxels represent vessels. Vessel volume fraction (volume ratio of vessels to cortical bone), vessel density (average vessel count per cortical bone volume), and average vessel volume (mean volume of vessels) were calculated to quantify the status of vessel-filled pores in cortical bone. To examine spatial resolution and perform validation, a virtual phantom with 5 channel sizes and an applied pseudo enhancement curve was processed through the proposed image processing pipeline. Overlap volume ratio and Dice coefficient was calculated to measure the similarity between the detected vessel map and ground truth. In the human study, mean vessel volume fraction was 2.2%±1.0%, mean vessel density was 0.68±0.27 vessel/mm3, and mean average vessel volume was 0.032±0.012 mm3/vessel. Signal intensity for detected vessel voxels increased during the scan, while signal for non-vessel voxels within pores did not enhance. In the validation phantom, channels with diameter 250 µm or greater were detected successfully, with volume ratio equal to 1 and Dice coefficient above 0.6. Both statistics decreased dramatically for channel sizes less than 250 µm. We have a developed a multi-modal image acquisition and processing pipeline that successfully detects vessels within cortical bone pores. The performance of this technique degrades for vessel diameters below the in-plane spatial resolution of the DCE-MRI acquisition. This approach can be applied to investigate the biological systems associated with cortical pore expansion.

First clinical retrospective investigation of limited projection CBCT for lung tumor localization in patients receiving SBRT treatment

To clinically investigate the limited-projection CBCT (LP-CBCT) technology for daily positioning of patients receiving breath-hold lung SBRT radiation treatment and to investigate the feasibility of reconstructing fast 4D-CBCT from 1 min 3D-CBCT scan.Eleven patients who underwent breath-hold lung SBRT radiation treatment were scanned daily with on-board full-projection CBCT (CBCT) using half-fan scan. A subset of the CBCT projections and the prior planning CT were used to estimate the LP-CBCT images using the weighted free-form deformation method. The limited projections are clusteringly sampled within fifteen sub-angles in 360° in order to simulate the fast 1 min scan for 4D-CBCT. The estimated LP-CBCTs were rigidly registered to the planning CT to determine the clinical shifts needed for patient setup corrections, which were compared with shifts determined by the CBCT for evaluation. Both manual and automatic registrations were performed in order to compare the systematic registration errors. Fifty CBCT volumes were obtained from the eleven patients in fifty fractions for this pilot clinical study.For the CBCT images, the mean (±standard deviation) shifts between CBCT and planning CT from manual registration in left–right (LR), anterior–posterior (AP), and superior–inferior (SI) directions are 1.1 ± 1.2 mm, 2.1 ± 1.9 mm, 5.2 ± 3.6 mm, respectively. The mean deviation difference between shifts determined by CBCT and LP-CBCT images are 0.3 ± 0.5 mm, 0.5 ± 0.8 mm, 0.4 ± 0.3 mm, in LR, AP, and SI directions, respectively. The mean vector length of CBCT shift for all fractions is 6.1 ± 3.6 mm, and the mean vector length difference between CBCT and LP-CBCT for all fractions studied is 1.0 ± 0.9 mm. The automatic registrations yield similar results as manual registrations.The pilot clinical study shows that LP-CBCT localization offers comparable accuracy to CBCT localization for daily tumor positioning while reducing the projection number to 1/10 for patients receiving breath hold lung radiation treatment. The cluster projection sampling in this study also shows the feasibility of reconstructing fast 4D-CBCT from 1 min 3D-CBCT scan.

Dynamics of fluorine-18-fluorodeoxyglucose uptake in the liver and its correlation with hepatic fat content and BMI.

The aim of this study was to explore the rate of elimination of fluorine-18-fluorodeoxyglucose (F-FDG) from the liver and assess the impact of hepatic fat and obesity on F-FDG clearance in early and delayed PET scans. We hypothesized that an increase in liver fat may cause a decline in hepatic F-FDG elimination with potential consequences as measured by dual time-point F-FDG PET/CT imaging. A total of 32 patients from the Cardiovascular Molecular Calcification Assessed by F-NaF PET/CT (CAMONA) clinical trial (17 males, 15 females; mean age: 47.2 years, range: 23-69 years, mean BMI: 27.2 kg/m) were enrolled and underwent F-FDG PET/CT 90 and 180 min after tracer injection. Global mean standardized uptake value (SUVmean) (i.e. the average of SUVmean in segmented liver slices) and average maximum standardized uptake value (SUVmax) (i.e. the average of the SUVmax values recorded in same slices) were calculated for semiquantification of liver F-FDG uptake at both time-points. Percentage difference in global SUVmean and average SUVmax were also calculated to yield respective retention indices (RImean and RImax). Changes in global SUVmean, average SUVmax, RImean, and RImax from 90 to 180 min were correlated with BMI and liver fat content as measured by CT Hounsfield units. There was a 12.2±3.5 percent reduction in global liver SUVmean and a 4.1±5.8 percent reduction in average SUVmax at 180 min scan as compared with the 90 min time-point. RImean and RImax were inversely correlated with liver fat content and positively correlated with BMI. We observed a time-dependent decrease in global hepatic SUVmean and average SUVmax, which was affected by the amount of liver fat. Patients with higher BMI and hepatic fat content tended to retain F-FDG.