Individual and peer factors associated with ketamine use among adolescents in Taiwan

The aim of this cross-sectional study was to examine the individual (demographic characteristics, substance-using behaviors, emotional status, and negative outcome expectancy) and peer factors associated with ketamine use in Taiwanese adolescents. A total of 9,860 adolescents completed the self-report questionnaires without omission. Demographic characteristics, substance-using behaviors, emotional status, negative outcome expectancy, and peer factors were compared between the ketamine users and non-users using the Mann-Whitney U test and the Chi-square test, and then significant factors were further selected for stepwise logistic regression analysis to examine the associated factors of ketamine use. Sixty-nine (0.7%) participants reported having used ketamine in the past year. The results of logistic regression analysis indicated that ketamine users were more likely to use marijuana, smoke cigarettes, have peers using illicit drugs, and have a lower level of negative outcome expectancy regarding using ketamine than ketamine non-users. The associated factors found in this study should be taken into consideration when developing prevention and intervention programs for ketamine use in adolescents.     

Use of the CogState Brief Battery in the assessment of Alzheimer's disease related cognitive impairment in the Australian Imaging, Biomarkers and Lifestyle (AIBL) study

Abstract

The primary aim of neuropsychology is the understanding of brain-behavior relationships. This necessitates confronting the mind-body problem, and the neuropsychologist must frequently cross between physical and psychological conceptual systems. The localizationist-antilocalizationist controversy can be understood, in part, as a result of different attitudes toward this conceptual difficulty. The tendency to reify the name of complex psychological constructs demonstrated by some of the localizationists continues to muddle both the thinking and research of neuropsychologists. Our increased ability to localize brain lesions through neuroradiographic tests must be paralleled by increased sophistication in analyzing psychological functions. The methods from cognitive psychology offer great promise in the study of ability and disability in neuropsychology.     

Promising application of dynamic nuclear polarization for in vivo (13)C MR imaging

Use of hyperpolarized (13)C in magnetic resonance (MR) imaging is a new technique that enhances signal tens of thousands-fold. Recent in vivo animal studies of metabolic imaging that used hyperpolarized (13)C demonstrated its potential in many applications for disease indication, metabolic profiling, and treatment monitoring. We review the basic physics for dynamic nuclear polarization (DNP) and in vivo studies reported in prostate cancer research, hepatocellular carcinoma research, diabetes and cardiac applications, brain metabolism, and treatment response as well as investigations of various DNP (13)C substrates.     

In vivo MR quantification of superparamagnetic iron oxide nanoparticle leakage during low-frequency-ultrasound-induced blood-brain barrier opening in swine

Purpose:

To verify that low‐frequency planar ultrasound can be used to disrupt the BBB in large animals, and the usefulness of MRI to quantitatively monitor the delivery of superparamagnetic iron oxide (SPIO) nanoparticles into the disrupted regions.

Materials and Methods:

Two groups of swine subjected to craniotomy were sonicated with burst lengths of 30 or 100 ms, and one group of experiment was also performed to confirm the ability of 28‐kHz sonication to open the BBB transcranially. SPIO nanoparticles were administered to the animals after BBB disruption. Procedures were monitored by MRI; SPIO concentrations were estimated by relaxivity mapping.

Results:

Sonication for 30 ms created shallow disruptions near the probe tip; 100‐ms sonications after craniotomy can create larger and more penetrating openings, increasing SPIO leakage ～3.6‐fold than 30‐ms sonications. However, this was accompanied by off‐target effects possibly caused by ultrasonic wave reflection. SPIO concentrations estimated from transverse relaxation rate maps correlated well with direct measurements of SPIO concentration by optical emission spectrometry. We have also shown that transcranial low‐frequency 28‐kHz sonication can induce secure BBB opening from longitudinal MR image follow up to 7 days.

Conclusion:

This study provides valuable information regarding the use low‐frequency ultrasound for BBB disruption and suggest that SPIO nanoparticles has the potential to serve as a thernostic agent in MRI‐guided ultrasound‐enhanced brain drug delivery. J. Magn. Reson. Imaging 2011;. © 2011 Wiley Periodicals, Inc.     

Optimal scanning time window for 18F-FP-(+)-DTBZ (18F-AV-133) summed uptake measurements

¹⁸F-9-fluoropropyl-(+)-dihydrotetrabenazine (¹⁸F-AV-133) is a novel positron emission tomography tracer for imaging the vesicular monoamine transporter II in dopaminergic neuron degeneration, which might be indicative for Parkinson's disease (PD) and other parkinsonism. Studies were performed to optimize the imaging time window for calculating standardized uptake value ratio (SUVR) with correlation to distribution volume ratio (DVR) and in differentiating PD from normal controls (NCs).

Methods

Thirteen ¹⁸F-AV-133 positron emission tomography studies were conducted on four NCs (age, 62.3±4.9 years) and nine PD patients (age, 60.8±6.0 years) with Hoehn and Yahr stages 2 to 3. Dynamic images were acquired within 180 min (0–30, 50–140 and 160–180 min) and were rearranged into 14 of 10-min scans. The contralateral striatum was defined as the opposite striatum to the predominantly affected limbs. Volumes of interest (VOIs) of bilateral putamen, caudate nuclei and occipital cortex (OC; as the reference region) were delineated from individual magnetic resonance imaging. SUVRs of striatum to OC were computed from 14 dynamic image sets. The DVRs were computed from Logan graphic analysis by using OC as the input. The performance of SUVR was evaluated based on the correlation of SUVR at each time window to DVR, as well as the Cohen effect size (group mean SUVR difference between PD and NC/standard deviation).

Results

¹⁸F-AV-133 uptake decreased in PD subjects at bilateral striatum especially at contralateral side with posterior putamen predominant as compared with NC. Consistent higher correlations of SUVRs to DVR for all VOIs were observed at later time window and reached to its maximal value of 0.9917 at 90–100 min. The group mean SUVR differences between NC and PD subjects increased and reached relatively stable values after 90 min. The effect sizes for all VOIs were stable across different time window and with the largest value around 90~120 min.

Conclusion

The scanning time of 90–100 min for ¹⁸F-AV-133 is considered as the optimal time window for summed uptake measurements in terms of SUVRs' correlation to DVRs, differential power, stability and clinical feasibility across and between NC and PD patients.     

Effect of increased MRI and CT scan utilization on clinical decision-making in patients referred to a surgical clinic for back pain

Background

We sought to determine the association between radiologic and clinical diagnoses and to measure the impact of more magnetic resonance imaging (MRI) and computed tomography (CT) scans on clinical decision-making in patients referred to a surgical clinic for back pain.

Methods

We conducted a 7-week prospective study of patients referred for back pain to spine surgeons in 1 health care centre. Patients were included if they had not previously been seen by a surgeon for their back problems and if their back pain was related to the thoracic or lumbar spine. We collected demographic data, imaging findings, clinical diagnoses as determined by the surgeons and visit outcomes and compared our results with those of a similar study conducted in 1996.

Results

Of 160 patients, 8 (5%) were no-shows and excluded from further analysis owing to incomplete data. There were more MRI scans and fewer plain radiographs ordered in 2009 compared with 1996 (73% v. 11% and 39% v. 68%, respectively). Degenerative disc disease was a more common radiologic diagnosis (n = 78, 63%) than clinical diagnosis (n = 41, 27%). Disc herniation was a more common radiologic diagnosis (n = 69, 56%) than clinical diagnosis (n = 25, 16%). With regards to visit outcomes, there were fewer second opinions sought in 2009 compared with 1996 (3% v. 11%). Although not statistically significant, the number of surgical candidates remained relatively stable (19% in 1996 v. 16% in 2009, p = 0.44).

Conclusion

The clinical diagnosis had a poor association with radiologic abnormalities. Despite an increase in the number of MRI and CT scans, the number of patients deemed surgical candidates has not changed.