Perspectives of brain imaging with PET systems

Abstract In this partial review and partial attempt at vision of what may be the future of dedicated brain PET scanners, the key implementations of the PET technique, we postulate that we are still on a development path and there is still a lot to be done in order to develop optimal brain imagers. Optimized for particular imaging tasks and protocols, and also mobile, that can be used outside the PET center, in addition to the expected improvements in sensitivity and resolution. For this multi-application concept to be more practical, flexible, adaptable designs are preferred. This task is greatly facilitated by the improved TOF performance that allows for more open, adjustable, limited angular coverage geometries without creating image artifacts. As achieving uniform very high resolution in the whole body is not practical due to technological limits and high costs, hybrid systems using a moderate-resolution total body scanner (such as J-PET) combined with a very high performing brain imager could be a very attractive approach. As well, as using magnification inserts in the total body or long-axial length imagers to visualize selected targets with higher resolution. In addition, multigamma imagers combining PET with Compton imaging should be developed to enable multitracer imaging.

Download Full-text

Prediction and validation of total and regional fat mass by B-mode ultrasound in Japanese pre-pubertal children

British Journal Of Nutrition ◽

10.1017/s0007114511001103 ◽

2011 ◽

Vol 106 (6) ◽

pp. 944-950 ◽

Cited By ~ 5

Author(s):

Taishi Midorikawa ◽

Megumi Ohta ◽

Yuki Hikihara ◽

Suguru Torii ◽

Michael G. Bemben ◽

...

Keyword(s):

Fat Mass ◽

Model Development ◽

Whole Body ◽

Validation Group ◽

Prediction Equations ◽

Fat Thickness ◽

Total Body ◽

Scanning Head ◽

Body Scanner ◽

Development Group

The present study was performed to develop regression-based prediction equations for fat mass by ultrasound in Japanese children and to investigate the validity of these equations. A total of 127 healthy Japanese pre-pubertal children aged 6–12 years were randomly separated into two groups: the model development group (fifty-four boys and forty-four girls) and the validation group (eighteen boys and eleven girls). Total body, trunk, arm and leg fat masses were initially determined by dual-energy X-ray absorptiometry (DXA, Delphi A-QDR whole-body scanner; Hologic, Inc., Bedford, MA, USA). Then, fat thickness was measured by B-mode ultrasound (5 MHz scanning head) at nine sites (arm: lateral forearm, anterior and posterior upper arm; trunk: abdomen and subscapular; leg: anterior and posterior thigh, anterior and posterior lower leg). Regression analyses were used to describe the relationships between the site-matched fat masses (total body, arm, trunk and leg) obtained by DXA and ultrasound in the development group. When these fat mass prediction equations were applied to the validation group, the measured total and regional fat mass was very similar to the predicted fat mass (mean difference calculated as predicted − measured fat mass ± 2 sd; total body 0·1 (sd 0·5) kg, arm 0·1 (sd 0·3) kg, trunk − 0·1 (sd 0·3) kg, leg 0·1 (sd 0·5) kg for boys; total body 0·5 (sd 1·3) kg, arm 0·0 (sd 0·3) kg, trunk 0·1 (sd 0·8) kg, leg 0·3 (sd 0·6) kg for girls), and the Bland–Altman analysis did not indicate a bias. These results suggest that ultrasound-derived prediction equations for boys and girls are useful for estimating total and regional fat mass.

Download Full-text

New probe for the improvement of the Spatial Resolution in total-body PET (PROScRiPT)

EPJ Web of Conferences ◽

10.1051/epjconf/202125309004 ◽

2021 ◽

Vol 253 ◽

pp. 09004

Author(s):

A. Ros ◽

L. Barrientos ◽

M. Borja-Lloret ◽

J.V. Casaña ◽

E. Muñoz ◽

...

Keyword(s):

Spatial Resolution ◽

Whole Body ◽

Ct Scanner ◽

Scintillation Crystal ◽

Pet Ct ◽

Energy Peak ◽

Extended Field ◽

Total Body ◽

Bed Position ◽

Pet Scanners

In recent decades, PET scanners have been widely used for diagnosis and treatment monitoring in nuclear medicine. The continuous effort of the scientific community has led to improvements in scanner performance. Total-body PET is one of the latest upgrades in PET scanners. These kinds of scanners are able to scan the whole body of the patient with a single bed position, since the scanner tube is long enough for the patient to fit inside. While these scanners show unprecedented efficiency and extended field-of-view, a drawback is their low spatial resolution compared to dedicated scanners. In order to improve the spatial resolution of specific areas when measuring with a total-body PET scanner, the IRIS group at IFIC-Valencia is developing a probe. The proposed setup of the probe contains a monolithic scintillation crystal and a SiPM. The signal of the probe is read out by a TOFPET2 ASIC from PETsys, which has shown good performance for PET in terms of spatial and time resolutions. Furthermore, the PETsys technology generates a trigger signal that will be used to time synchronise the probe and the scanner. The proof-of-concept of the probe will be tested in a Preclinical Super Argus PET/CT scanner for small animals located at IFIC. Preliminary simulations of the scanner and the probe under ideal conditions show a slight improvement in the position reconstruction compared to the data obtained with the scanner, therefore we expect a considerable improvement when using the probe in a total-body PET scanner. Characterisation tests of the probe have been performed with a 22Na point-like source, obtaining an energy resolution of 9.09% for the 511 keV energy peak and a temporal resolution of 619 ps after time walk correction. The next step of the project is to test the probe measuring in temporal coincidence with the scanner.

Download Full-text

Significant artefactual noise in 90Y TOF-PET imaging of low specific activity phantoms arises despite increased acquisition time

EJNMMI Physics ◽

10.1186/s40658-019-0259-6 ◽

2019 ◽

Vol 6 (1) ◽

Author(s):

Michel Hesse ◽

Stephan Walrand

Keyword(s):

Pet Imaging ◽

Specific Activity ◽

Whole Body ◽

Acquisition Time ◽

Random Coincidence ◽

Natural Crystal ◽

Phantom Studies ◽

Pet Reconstruction ◽

Very High ◽

Tof Pet

AbstractVolumes of usual PET phantoms are about four to sixfold that of a human liver. In order to avoid count rate saturation and handling of very high 90Y activity, reported TOF-PET phantom studies are performed using specific activities lower than those observed in liver radioembolization.However, due to the constant random coincidence rate induced by the natural crystal radioactivity, reduction of 90Y specific activity in TOF-PET imaging cannot be counterbalanced by increasing the acquisition time. As a result, most 90Y phantom studies reported images noisier than those obtained in whole-body 18F-FDG, and thus advised to use dedicated noise control in TOF-PET imaging post 90Y liver radioembolization.We performed acquisitions of the Jaszczak Deluxe phantom in which the hot rod insert was only partially filled with 2.6 GBq of 90Y. Standard reconstruction parameters recommended by the manufacturer for whole-body 18F-FDG PET were used.Low specific activity setups, although exactly compensated by increasing the acquisition time in order to get the same number of detected true coincidences per millilitre, were impacted by significant noise. On the other hand, specific activity and acquisition time setup similar to that used in post 90Y liver radioembolization provided image quality very close to that of whole-body 18F-FDG.This result clearly discards the use of low specific activity phantoms intended to TOF-PET reconstruction parameter optimization. Volume reduction of large phantoms can be achieved by vertically setting the phantoms or by adding Styrofoam inserts.

Download Full-text

Use of Continuous Blood Volume Monitoring to Detect Inadequately High Dry Weight

The International Journal of Artificial Organs ◽

10.1177/039139889601900706 ◽

1996 ◽

Vol 19 (7) ◽

pp. 411-414 ◽

Cited By ~ 48

Author(s):

F. Lopot ◽

P. Kotyk ◽

J. Bláha ◽

J. Forejt

Keyword(s):

Blood Volume ◽

Vena Cava ◽

Extracellular Fluid ◽

Dry Weight ◽

Whole Body ◽

The Status ◽

Varying Length ◽

Group 3 ◽

Group 2 ◽

Total Body

A continuous blood volume monitoring (CBVM) device (Inline Diagnostics, Riverdale, USA) was used to study response to prescribed ultrafiltration during haemodialysis (HD) in 66 stabilised HD patients. Fifty percent of patients showed the expected linear decrease in BV right from the beginning of HD (group 1), 32% exhibited no decrease at all (group 2), while eighteen percent formed the transient group 3 which showed a plateau of varying length after which a decrease occurred. The correct setting of dry weight was verified through evaluation of the ratio of extracellular fluid volume to total body water (VEC/TBW) in 26 patients by means of whole body multifrequency impedometry MFI (Xitron Tech., San Diego, USA) and through measurement of the Vena Cava Inferior diameter (VCID) pre and post HD (in 6 and 5 patients from groups 1 and 3 and from group 2, respectively). The mean VEC/TBW in groups 1 and 3 was 0.56 pre and 0.51 post HD as compared to 0.583 and 0.551 in group 2. VCID decreased on average by 14.1% in groups 1 and 3 but remained stable in group 2. Both findings thus confirmed inadequately high estimation of dry weight. Since CBVM is extremely easy to perform it can be used as a method of choice in detecting inadequately high prescribed dry weight. The status of the cardiovascular system must always be considered before final judgement is made.

Download Full-text

Combined17O/1H MRI study in a whole-body scanner

Applied Magnetic Resonance ◽

10.1007/bf03166943 ◽

2003 ◽

Vol 24 (3-4) ◽

pp. 409-415 ◽

Cited By ~ 1

Author(s):

M. Kempka ◽

J. Hankiewicz ◽

D. Fiat

Keyword(s):

Whole Body ◽

Mri Study ◽

Body Scanner

Download Full-text

Using Moderate Resolution Imaging Spectrometer (MODIS) to calibrate advanced very high resolution radiometer reflectance channels

Journal of Geophysical Research Atmospheres ◽

10.1029/2001jd002035 ◽

2002 ◽

Vol 107 (D23) ◽

pp. AAC 11-1-AAC 11-10 ◽

Cited By ~ 105

Author(s):

Andrew K. Heidinger ◽

Changyong Cao ◽

Jerry T. Sullivan

Keyword(s):

High Resolution ◽

Imaging Spectrometer ◽

Moderate Resolution ◽

Resolution Imaging ◽

Very High

Download Full-text

Arc-PET: Cost-Effective Whole-Body Scanner with High Sensitivity and High Spatial Resolution

2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) ◽

10.1109/nss/mic42677.2020.9507815 ◽

2020 ◽

Author(s):

Eric W. Petersen ◽

Wei Zhao ◽

Amir Goldan

Keyword(s):

Spatial Resolution ◽

High Spatial Resolution ◽

High Sensitivity ◽

Cost Effective ◽

Whole Body ◽

Body Scanner

Download Full-text

Smaller organ mass with greater age, except for heart

Journal of Applied Physiology ◽

10.1152/japplphysiol.90454.2008 ◽

2009 ◽

Vol 106 (6) ◽

pp. 1780-1784 ◽

Cited By ~ 35

Author(s):

Qing He ◽

Stanley Heshka ◽

Jeanine Albu ◽

Lawrence Boxt ◽

Norman Krasnow ◽

...

Keyword(s):

African Americans ◽

The Elderly ◽

Left Ventricular ◽

Fat Free Mass ◽

Whole Body ◽

Organ Mass ◽

Total Body ◽

Age Range ◽

Negative Relationships

Autopsy/cadaver data indicate that many organs and tissues are smaller in the elderly compared with young adults; however, in vivo data are lacking. The aim of this study was to determine whether the mass of specific high-metabolic-rate organs is different with increasing age, using MRI. Seventy-five healthy women (41 African-Americans and 34 Caucasians, age range 19–88 yr) and 36 men (8 African-Americans and 28 Caucasians, age range 19–84 yr) were studied. MRI-derived in vivo measures of brain, heart, kidneys, liver, and spleen were acquired. Left ventricular mass (LVM) was measured by either echocardiography or cardiac gated MRI. Total body fat mass and fat-free mass (FFM) were measured with a whole body dual-energy X-ray absorptiometry (DXA) scanner. Multiple regression analysis was used to investigate the association between the organ mass and age after adjustment for weight and height (or DXA measures of FFM), race, sex, and interactions among these variable. No statistically significant interaction was found among age, sex, and race in any regression model. Significant negative relationships between organ mass and age were found for brain ( P < 0.0001), kidneys ( P = 0.01), liver ( P = 0.001), and spleen ( P < 0.0001). A positive relationship between LVM and age was found after adjustment for FFM ( P = 0.037). These findings demonstrate that age has a significant effect on brain, kidneys, liver, spleen, and heart mass. The age effect was independent of race and sex.

Download Full-text

Vegetative growth of grasslands based on hyper-temporal NDVI data from the Modis sensor

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2016000700009 ◽

2016 ◽

Vol 51 (7) ◽

pp. 858-868

Author(s):

Marcos Cicarini Hott ◽

Luis Marcelo Tavares de Carvalho ◽

Mauro Antonio Homem Antunes ◽

Polyanne Aguiar dos Santos ◽

Tássia Borges Arantes ◽

...

Keyword(s):

Vegetative Growth ◽

Vegetation Index ◽

Normalized Difference Vegetation Index ◽

High Growth ◽

Growth Index ◽

Data Series ◽

Moderate Resolution ◽

Resolution Imaging ◽

Moderate Resolution Imaging Spectroradiometer ◽

Very High

Abstract: The objective of this work was to analyze the development of grasslands in Zona da Mata, in the state of Minas Gerais, Brazil, between 2000 and 2013, using a parameter based on the growth index of the normalized difference vegetation index (NDVI) from the moderate resolution imaging spectroradiometer (Modis) data series. Based on temporal NDVI profiles, which were used as indicators of edaphoclimatic conditions, the growth index (GI) was estimated for 16-day periods throughout the spring season of 2012 to early 2013, being compared with the average GI from 2000 to 2011, used as the reference period. Currently, the grassland areas in Zona da Mata occupy approximately 1.2 million hectares. According to the used methods, 177,322 ha (14.61%) of these grassland areas have very low vegetative growth; 577,698 ha (45.96%) have low growth; 433,475 ha (35.72%) have balanced growth; 39,980 ha (3.29%) have high growth; and 5,032 ha (0.41%) have very high vegetative growth. The grasslands had predominantly low vegetative growth during the studied period, and the NDVI/Modis series is a useful source of data for regional assessments.

Download Full-text