Deep Learning Reconstruction Plus Single-Energy Metal Artifact Reduction for Supra Hyoid Neck CT in Patients With Dental Metals

Purpose: We investigated the effect of deep learning reconstruction (DLR) plus single-energy metal artifact reduction (SEMAR) on neck CT in patients with dental metals, comparing it with DLR and with hybrid iterative reconstruction (Hybrid IR)-SEMAR. Methods: In this retrospective study, 32 patients (25 men, 7 women; mean age: 63 ± 15 years) with dental metals underwent contrast-enhanced CT of the oral and oropharyngeal regions. Axial images were reconstructed using DLR, Hybrid IR-SEMAR, and DLR-SEMAR. In quantitative analyses, degrees of image noise and artifacts were evaluated. In one-by-one qualitative analyses, 2 radiologists evaluated metal artifacts, the depiction of structures, and noise on five-point scales. In side-by-side qualitative analyses, artifacts and overall image quality were evaluated by comparing Hybrid IR-SEMAR with DLR-SEMAR. Results: Artifacts were significantly less with DLR-SEMAR than with DLR in quantitative (P < .001) and one-by-one qualitative (P < .001) analyses, which resulted in significantly better depiction of most structures (P < .004). Artifacts in side-by-side analysis and image noise in quantitative and one-by-one qualitative analyses (P < .001) were significantly less with DLR-SEMAR than with Hybrid IR-SEMAR, resulting in significantly better overall quality of DLR-SEMAR. Conclusions: Compared with DLR and Hybrid IR-SEMAR, DLR-SEMAR provided significantly better supra hyoid neck CT images in patients with dental metals.

Ectopic pituitary neuroendocrine tumor arising in the sphenoid sinus with an avid 18F-fluorodeoxyglucose uptake masquerading as malignancy: A case report

Ectopic pituitary neuroendocrine tumors (PitNETs) are uncommon conditions that develop outside of the sella turcica. The sphenoid sinus is the most common site for ectopic PitNET, followed by the suprasellar region, clivus, and cavernous sinus. PitNETs, regardless of whether inside or outside sella, may display avid 18F-fluorodeoxyglucose (FDG) uptake and masquerade as malignant tumors. Herein, we report a case of ectopic PitNET arising in the sphenoid sinus, which was found as an FDG-avid mass during cancer screening. On magnetic resonance imaging, the tumor showed heterogeneous and intermediate signal intensity areas on T1- and T2-weighted images with cystic components, which was consistent with PitNET. The localization and the presence of empty sella were suggestive of ectopic PitNET, and the diagnosis of ectopic PitNET (prolactinoma) was confirmed by endoscopic biopsy. Ectopic PitNET should be considered in a mass similar in nature to an orthogonal PitNET in areas near the sella turcica especially in patients with empty sella.

Deep-learning reconstruction for the evaluation of lumbar spinal stenosis in computed tomography

To compare the quality and interobserver agreement in the evaluation of lumbar spinal stenosis (LSS) on computed tomography (CT) images between deep-learning reconstruction (DLR) and hybrid iterative reconstruction (hybrid IR). This retrospective study included 30 patients (age, 71.5 ± 12.5 years; 20 men) who underwent unenhanced lumbar CT. Axial and sagittal CT images were reconstructed using hybrid IR and DLR. In the quantitative analysis, a radiologist placed regions of interest within the aorta and recorded the standard deviation of the CT attenuation (i.e., quantitative image noise). In the qualitative analysis, 2 other blinded radiologists evaluated the subjective image noise, depictions of structures, overall image quality, and degree of LSS. The quantitative image noise in DLR (14.8 ± 1.9/14.2 ± 1.8 in axial/sagittal images) was significantly lower than that in hybrid IR (21.4 ± 4.4/20.6 ± 4.0) (P < .0001 for both, paired t test). Subjective image noise, depictions of structures, and overall image quality were significantly better with DLR than with hybrid IR (P < .006, Wilcoxon signed-rank test). Interobserver agreements in the evaluation of LSS (with 95% confidence interval) were 0.732 (0.712-0.751) and 0.794 (0.781-0.807) for hybrid IR and DLR, respectively. DLR provided images with improved quality and higher interobserver agreement in the evaluation of LSS in lumbar CT than hybrid IR.

Effect of rolipram on muscarinic acetylcholine receptor binding in the intact mouse brain

The effect of rolipram, a selective inhibitor of phosphodiesterase type 4 (PDE(4)) and elevating cyclic AMP (cAMP), on in vivo and in vitro (3)H-N-methylpiperidyl benzilate ((3)H-NMPB) binding to muscarinic acetylcholine receptors in the mouse brain was examined. Rolipram significantly decreased in vivo (3)H-NMPB binding in the cerebral cortex, hippocampus and striatum, whereas in vitro (3)H-NMPB binding in these regions was not altered. Saturation experiments on in vivo binding in conjunction with the kinetic analysis revealed that the apparent association rate constant (k(on)) of (3)H-NMPB binding in vivo was significantly decreased by rolipram. A similar decrease in the apparent association rate constant (k(on)) by rolipram was reported for dopamine D(1) and D(2) receptor binding in vivo. These results indicate that rolipram plays an important role in the global modulation of apparent rates of ligand-receptor interactions in the intact brain.

Effects of rolipram on in vivo dopamine receptor binding

In order to clarify whether changes in brain concentrations of the second messenger cyclic AMP (cAMP) affect in vivo receptor binding in the brain, the effects of rolipram, a selective inhibitor of phosphodiesterase type 4 (PDE(4)), on dopamine receptor binding in the mouse brain were studied. Rolipram significantly decreased in vivo (3)H-SCH 23390 (dopamine D(1) selective radioligand) binding in the mouse striatum in a dose-dependent manner. In vivo saturation experiments together with the kinetic analysis of (3)H-SCH 23390 binding revealed that the apparent association rate constant (k(on)) for (3)H-SCH 23390 binding rather than the maximum number of binding sites available (B(max)) was decreased by rolipram. (3)H-N-methylspiperone (NMSP, dopamine D(2) selective radioligand) binding in the mouse striatum was also decreased by rolipram whereas no significant changes in (3)H-raclopride (dopamine D(2) selective radioligand) binding were observed. As (3)H-raclopride binding has been reported to be much more sensitive than (3)H-NMSP binding to competition by endogenous dopamine, the decreases in (3)H-SCH 23390 and (3)H-NMSP binding cannot be attributed to competitive inhibition by endogenous dopamine. These results indicate that changes in second messenger cAMP concentrations may affect the apparent bimolecular association rate constant (k(on)) of dopamine receptor binding in intact brain. This may be mediated by changes in the receptor micro-environment and altered actual free ligand concentration surrounding the receptors.

The role of the cAMP-PKA system in the short-term regulation of striatal [(14)C]-2-deoxyglucose uptake in freely moving rats

The cyclic adenosine monophosphate (cAMP)-protein kinase (PK) A system has been shown to have stimulatory effects on glucose utilization in various tissues in vitro. However, little is known about the influence of cAMP on glucose utilization in vivo. In the present study, we examined how cAMP-related compounds affected [(14)C]-2-deoxyglucose (DG) uptake in the striatum of freely moving rats. An intrastriatal injection of dibutyryl-cyclic adenosine monophosphate (db-cAMP), although increasing local cerebral blood flow, was found to decrease the uptake of [(14)C]-2-DG in the striatum. This decrease of [(14)C]-2-DG uptake in the striatum was completely blocked by pretreatment with Rp-adenosine-3',5'-cyclic monophosphorothioate triethylamine (Rp-cAMPS). Moreover, intrastriatal infusion of Rp-cAMPS alone produced a striking increase of [(14)C]-2-DG uptake in the striatum. These results strongly suggest that transient activation of the cAMP-PKA system can depress the glucose phosphorylation process of the rat brain in vivo.

Different sensitivities to competitive inhibition of benzodiazepine receptor binding of 11C-iomazenil and 11C-flumazenil in rhesus monkey brain

The in vivo binding kinetics of 11C-iomazenil were compared with those of 11C-flumazenil binding in rhesus monkey brain. The monkey was anesthetized with ketamine and intravenously injected with either 11C-iomazenil or 11C-flumazenil in combination with the coadministration of different doses of non-radioactive flumazenil (0, 5 and 20 microg/kg). The regional distribution of 11C-iomazenil in the brain was similar to that of 11C-flumazenil, but the sensitivity of 11C-iomazenil binding to competitive inhibition by non-radioactive flumazenil was much less than that of 11C-flumazenil binding. A significant reduction in 11C-flumazenil binding in the cerebral cortex was observed with 20 microg/kg of flumazenil, whereas a relatively smaller inhibition of 11C-iomazenil binding in the same region was observed with the same dose of flumazenil. These results suggest that 11C-flumazenil may be a superior radiotracer for estimating benzodiazepine receptor occupancy in the intact brain.

Evaluation of in vivo binding properties of 3H-NMPB and 3H-QNB in mouse brain

Apparent muscarinic acetylcholine (mAch) receptor occupancy in mouse cerebral cortex, hippocampus, and striatum by scopolamine, an antagonist, and biperiden, a relatively selective M1 antagonist, was estimated with competitive binding studies using two different radioligands: 3H-N-methyl piperidyl benzilate (3H-NMPB) and 3H-quinuclidinyl benzilate (3H-QNB). Both radioligands labeled mAch receptors in these brain regions, and the relative regional distributions of the specific binding of 3H-NMPB in vivo paralleled the distribution of mAch receptors. 3H-NMPB binding in vivo was much more sensitive to direct competitive inhibition by scopolamine than was 3H-QNB. A similar discrepancy in sensitivity to competitors between 3H-NMPB and 3H-QNB was also observed when biperiden was used as a competitor, indicating that binding to different subtypes of the mAch receptor could not account for the observed differences in sensitivity to competition. An in vivo saturation study suggested that the apparent association rate constant (k on) of 3H-QNB binding might be changed by ligand concentration. The heterogeneity of the free ligand concentration in intact brain was assessed in relation to the ligand concentration dependency of the apparent association rate constant (k on) of 3H-QNB binding. This finding, together with the more favorable accumulation of 3H-NMPB in cerebral cortex, hippocampus, and striatum, leads us to conclude that 3H-NMPB, or its positron emitting counterpart, should be the more favorable radiotracer for the estimation of mAch receptor occupancy by cholinergic drugs in the brain.

KEYWORDS

mAch receptor, QNB, NMPB, in vivo, mouse.

Discrepancies in apparent dopamine D2 receptor occupancy between 3H-raclopride and 3H-N-methylspiperone

Competitive inhibition of 3H-raclopride (RAC) and 3H-N-methylspiperone (NMSP) binding against haloperidol, raclopride and NMSP was measured in the mouse striatum. 3H-RAC binding was more sensitive to competitive inhibition by all three compounds compared with 3H-NMSP. For example, 0.3 mg/kg of haloperidol resulted in 95% inhibition of 3H-RAC binding, however only 60% of inhibition of 3H-NMSP binding was found at the same dose of haloperidol. The cross-inhibition experiments using non-radioactive RAC or NMSP as competitors indicated different binding sites for 3H-RAC and 3H-NMSP in mouse striatum. Specifically, about 40% of 3H-NMSP binding was not displaced by treatment with a very high dose of raclopride (3 mg/kg). The time course of inhibition of the specific binding of 3H-RAC and 3H-NMSP were measured following i.p. injection of 0.5 mg/kg of haloperidol. No significant differences in the kinetics of haloperidol inhibition were observed between two radioligands.

Discrepancy of benzodiazepine receptor occupancy between 3H-flumazenil and 125I-iomazenil in intact mouse brain

The in vivo benzodiazepine (BZ) receptor occupancy in mouse brain was measured by employing 3H-flumazenil (FMZ) in comparison with 125I-iomazenil (IMZ), in order to obtain fundamental data for PET and SPECT studies, respectively. Mice were pretreated with various doses of flunitrazepam (FNP) 40 min prior to the tracer injection. At 20 min after the tracer injection, mice were killed by decapitation and receptor occupancy in cerebral cortex, hippocampus, cerebellum and pons-medulla were determined by the modified method reported by Goeders and Kuhar (1985). In all regions studied, BZ receptor occupancy by FNP measured with 3H-FMZ was significantly higher than that of 125I-IMZ. For instance, 0.1 mg/kg of FNP inhibited almost 50% of the specific binding of 3H-FMZ, on the other hand almost no inhibition of 125I-IMZ with the same dose of FNP was seen. This type of discrepancy was also observed in other types of benzodiazepine agonists, nimetazepam and triazolam, or inverse agonist ethyl-beta-carboline-3-carboxylate (CCE). It is of interest that in in vitro binding study using brain homogenate, almost the same competitive inhibition curve was observed between these two radioligands, which strongly suggested that discrepancy of receptor occupancy is likely observed in intact brain. The mechanism for such discrepancy is unknown, although the different kinetics properties of these two radioligand seems to be an important factor.

Changes in apparent in vivo binding of [3H]raclopride and [3H]N-methylspiperone induced by oxotremorine

The effects of muscarinic agonist, oxotremorine (0.3 mg/kg), and antagonist, scopolamine (0.5 mg/kg), on in vivo [3H]raclopride (RAC) and [3H]N-methylspiperone (NMSP) binding were investigated. Following tracer administration to control or pretreated mice, binding potentials, and the rate constants k3 and k4 were determined by kinetic analysis. Oxotremorine resulted in a 70% increase in striatal RAC binding potential compared with controls. RAC and NMSP showed almost identical decreases in k3 (40%), whereas k4 for RAC was unexpectedly decreased by 64%. Scopolamine resulted in no significant changes in RAC or NMSP binding. These results, in combination with previous data obtained in reserpinized mice, show that 1) competition by endogenous ligand may not be the only factor influencing the magnitude of apparent in vivo receptor binding, and 2) interneuronal communication may be partly mediated by changes in the rates of ligand-receptor binding.

Effects of the GABAergic system on in vivo binding of [3H]N-methylspiperone

The effects of flunitrazepam, a benzodiazepine receptor agonist and those of NNC-711, a GABA transporter blocker, on the in vivo binding of [3H]N-methylspiperone, a dopamine D2 receptor antagonist, were investigated in mouse brain. Treatment with either flunitrazepam or NNC-711 reduced the specific binding of [3H]N-methylspiperone in the striatum. Flumazenil, a central benzodiazepine receptor antagonist, blocked the effect of flunitrazepam, indicating that the reduction in specific binding in the striatum was mediated via the GABAergic system. The flunitrazepam significantly decreased the specific binding of [3H]N-methylspiperone in the striatum at all time points studied after tracer injection, whereas specific binding in the cerebellum and cerebral cortex was unaltered. This decrease in specific binding in the striatum was found to be due to a reduced input rate constant (k3) of [3H]N-methylspiperone. The maximum number of the binding sites available for dopamine D2 receptors in the striatum was not changed by the flunitrazepam treatment.

Isoform-specific up-regulation by ouabain of Na+,K+-ATPase in cultured rat astrocytes

There are two alpha-subunit isoforms (alpha1 and alpha2) and two beta-subunit isoforms (beta1 and beta2) of Na+,K+-ATPase in astrocytes, but the functional heterodimer composition is not known. Ouabain (0.5-1.0 mM) increased the levels of alpha1 and beta1 mRNAs, whereas it decreased those of alpha2 and beta2 mRNAs in cultured rat astrocytes. The increases in alpha1 and beta1 mRNAs were observed at 6-48 h after addition of the inhibitor. Immunochemical analyses showed that ouabain increased alpha1 and beta1, but not alpha2 and beta2, proteins, and that the isoforms in control and ouabain-treated cultures were of glial origin. Low extracellular K+ and monensin (20 microM) mimicked the effect of ouabain on alpha1 mRNA. The ouabain-induced increase in alpha1 mRNA was blocked by the protein synthesis inhibitor cycloheximide (10 microM), the intracellular Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetraacetoxymethyl ester (30 microM), and the calcineurin inhibitor FK506 (1 nM). These findings indicate that chronic inhibition of Na+,K+-ATPase up-regulates the alpha1 and beta1, but not alpha2 and beta2, isoforms in astrocytes, suggesting a functional coupling of alpha1beta1 complex. They also suggest that intracellular Na+, Ca2+, and calcineurin may be involved in ouabain-induced up-regulation of the enzyme in astrocytes.

Innovation in nursing education: development of computer-assisted thinking

In order to enhance students' active thinking, faculty members at International University of Health and Welfare developed the CAT (Computer Assisted Thinking) program. The CAT program is different from CAI (Computer Assisted Instruction), which mainly asks users to choose correct answers. Instead, the CAT program asks users to type in short sentences. There are two functions in the CAT program: one is to keep the students' action log each time they use the program and the other is to serve as medical dictionary. An analysis of the action log revealed that the students demonstrated little skill in inferential thinking. Their observations were very concrete. In order to help the students to develop their abstract thinking skills, we need to review our curriculum.

Ouabain-induced cell proliferation in cultured rat astrocytes

Ouabain markedly stimulated not only [3H]thymidine incorporation but also [3H]uridine incorporation into astrocytes. The effects were observed at 36-48 hr and 12-72 hr after addition of ouabain, respectively. The dose-response curves were both bell-shaped types with a peak at 10(-3) M for thymidine incorporation and 2 x 10(-3) M for uridine incorporation. Ouabain increased cell number as determined by an assay using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and by a method using a hemocytometer. Low concentration of external K+ mimicked the effect of ouabain in stimulating [3H]-thymidine incorporation, and high concentration of external K+ blocked the effect of ouabain. In contrast to astrocytes, ouabain did not stimulate [3H]thymidine incorporation into C6 glioma and fibroblast cells. The effect of ouabain on [3H]thymidine incorporation in astrocytes was dependent on external Ca2+, and it was blocked by cycloheximide. These findings indicate that prolonged Na+, K(+)-ATPase inhibition causes cell proliferation in cultured astrocytes in cell-specific and Ca(2+)-dependent manners.

Involvement of Na+,K(+)ATPase in the mitogenic effect of insulin-like growth factor-I on cultured rat astrocytes

We have previously reported that insulin/insulin-like growth factor (IGF)-I induced the alpha 1 isoform of Na+,K(+)-ATPase in cultured astrocytes. In this study the effects of insulin/IGF-I on Na+,K(+)-ATPase activity and cell proliferation were examined in astrocytes cultured under the various conditions, to test the possible involvement of the enzyme activity in the mitogenic action of IGF-I on astrocytes. Insulin increased Na+,K(+)-ATPase activity and stimulated cell proliferation in subconfluent astrocytes (cultured for 7-14 days in vitro). In contrast, these effects were not observed in confluent cells (cultured for 28 days). Furthermore, insulin stimulated neither the enzyme activity nor [3H]thymidine incorporation in astrocytes preincubated in fetal calf serum-free medium for 2 days (quiescent cells) and treated with dibutyryl cyclic AMP (differentiated cells). The increases in Na+,K(+)-ATPase activity and expression of the alpha 1 mRNA preceded the mitogenic effect. 125I-IGF-I binding experiment showed that all the cells used here had similar binding characteristics. The insulin-induced increase in enzyme activity was not affected by 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), and it was observed even in Ca(2+)-free medium. The stimulation by IGF-I of [3H]thymidine incorporation was attenuated by ouabain and a low external K+ level. These findings suggest that stimulation of Na+,K(+)-ATPase activity is involved in the mitogenic action of IGF-I on cultured astrocytes.

(S)-linalyl, 2-phenylethyl, and benzyl disaccharide glycosides isolated as aroma precursors from oolong tea leaves

Three glycosides, 6-O-beta-D-xylopyranosyl-beta-D-glucopyranosides (beta-primeverosides) of the aroma constituents, linalool, 2-phenylethanol, and benzyl alcohol, were isolated as aroma precursors from the tea leaves (Camellia sinensis var. sinensis cv. Shuixian and Maoxie, cultivars for oolong tea). The isolation was guided by acid or enzymatic hydrolysis, and subsequent GC and GC-MS analyses. The linalyl glycoside is the first example of naturally occurring (S)-linalyl beta-primeveroside.