Diagnostic performance of hepatic CT and chemical-shift MRI to discriminate lipid-poor adrenal adenomas from hepatocellular carcinoma metastases

PURPOSE

To evaluate the diagnostic performance of multiphase hepatic CT parameters (non-contrast attenuation, absolute and relative washout ratios [APW and RPW, respectively], and relative enhancement ratio [RER]) and chemical-shift MRI (CS-MRI) for discriminating lipid-poor adrenal adenomas (with non-contrast CT attenuation > 10 HU) from metastases in patients with hepatocellular carcinoma (HCC).

METHODS

This retrospective study included HCC patients with lipid-poor adrenal lesions who underwent multiphase hepatic CT between January 2010 and December 2021. For each adrenal lesion, non-contrast attenuation, APW, RPW, RER, and signal-intensity index (SI-index) were measured. Each parameter was compared between adenomas and metastases. The area under the receiver operating characteristic curves (AUCs) and sensitivities to achieve 100% specificity for adenoma diagnoses were determined.

RESULTS

104 HCC patients (78 men; mean age, 71.8 ± 9.6 years) with 63 adenomas and 48 metastases were identified; CS-MRI was performed in 66 patients with 49 adenomas and 21 metastases within one year of CT. Lipid-poor adenomas showed lower non-contrast attenuation (22.9 ± 7.1 vs. 37.9 ± 9.4 HU) and higher APW (40.5% ± 12.8% vs. 23.7% ± 17.4%), RPW (30.0% ± 10.2% vs. 12.4% ± 9.6%), RER (329% ± 152% vs. 111% ± 43.0%), and SI-index (43.3 ± 20.7 vs. 10.8 ± 13.4) than HCC metastases (all p < .001). AUC for non-contrast attenuation, APW, RPW, RER, and SI-index were 0.894, 0.786, 0.904, 0.969, and 0.902, respectively. The sensitivities to achieve 100% specificity were 7.9%, 25.4%, 30.2%, 63.5%, and 24.5%, respectively. Combined RER and APW achieved the highest sensitivity of 73.0%.

CONCLUSION

Multiphase hepatic CT allows for better discrimination between lipid-poor adrenal adenomas and metastases relative to CS-MRI, especially when combined with RER and washout parameters.

Lung-Optimized Deep-Learning-Based Reconstruction for Ultralow-Dose CT

RATIONALE AND OBJECTIVES

To evaluate the image properties of lung-specialized deep-learning-based reconstruction (DLR) and its applicability in ultralow-dose CT (ULDCT) relative to hybrid- (HIR) and model-based iterative-reconstructions (MBIR).

MATERIALS AND METHODS

An anthropomorphic chest phantom was scanned on a 320-row scanner at 50-mA (low-dose-CT 1 [LDCT-1]), 25-mA (LDCT-2), and 10-mA (ULDCT). LDCT were reconstructed with HIR; ULDCT images were reconstructed with HIR (ULDCT-HIR), MBIR (ULDCT-MBIR), and DLR (ULDCT-DLR). Image noise and contrast-to-noise ratio (CNR) were quantified. With the LDCT images as reference standards, ULDCT image qualities were subjectively scored on a 5-point scale (1 = substantially inferior to LDCT-2, 3 = comparable to LDCT-2, 5 = comparable to LDCT-1). For task-based image quality analyses, a physical evaluation phantom was scanned at seven doses to achieve the noise levels equivalent to chest phantom; noise power spectrum (NPS) and task-based transfer function (TTF) were evaluated. Clinical ULDCT (10-mA) images obtained in 14 nonobese patients were reconstructed with HIR, MBIR, and DLR; the subjective acceptability was ranked.

RESULTS

Image noise was lower and CNR was higher in ULDCT-DLR and ULDCT-MBIR than in LDCT-1, LDCT-2, and ULDCT-HIR (p < 0.01). The overall quality of ULDCT-DLR was higher than of ULDCT-HIR and ULDCT-MBIR (p < 0.01), and almost comparable with that of LDCT-2 (mean score: 3.4 ± 0.5). DLR yielded the highest NPS peak frequency and TTF_50% for high-contrast object. In clinical ULDCT images, the subjective acceptability of DLR was higher than of HIR and MBIR (p < 0.01).

CONCLUSION

DLR optimized for lung CT improves image quality and provides possible greater dose optimization opportunity than HIR and MBIR.

Practical Preventive Strategies for Extravasation of Contrast Media During CT: What the Radiology Team Should Do

RATIONALE AND OBJECTIVES

This study aimed to assess the effectiveness of practical preventive strategies (i.e., venous vulnerability assessment and prevention scan protocol rules) taken by our radiology team (radiology nurses, radiology technicians, radiologists) on reducing extravasation of contrast media (ECM) during CT.

MATERIALS AND METHODS

A total of 73,931 patients who underwent contrast-enhanced CT scans between January 2013 and December 2019 were retrospectively included. Venous vulnerability assessment by the radiology team began in 2015, and prevention scan protocol rules for the prevention of ECM were added in 2017. We defined each period as follows: 2013-2014, no prevention (Period A); 2015-2016, early prevention (Period B, venous vulnerability assessment only); and 2017-2019: late prevention (Period C, venous vulnerability assessment with prevention scan protocol rules). The incident reports, radiology reports, and medical records of patients in whom ECM occurred were reviewed. We compared the frequency of ECM during each period.

RESULTS

ECM occurred in 0.39% (292/73,931) of the patients. The frequencies of ECM for Periods A, B, and C were 0.62% (121/19,505), 0.43% (89/20,847), and 0.24% (82/33,579), respectively. There were significant differences in the frequencies of ECM among the three periods (Chi-squared test, p < 0.01).

CONCLUSION

Implementation of venous vulnerability assessment and prevention scan protocol rules by a radiology team can be a practical and simple solution to reduce the risk of ECM during CT.

Radiation dose optimization potential of deep learning-based reconstruction for multiphase hepatic CT: A clinical and phantom study

PURPOSE

This clinical and phantom study aimed to evaluate the impact of deep learning-based reconstruction (DLR) on image quality and its radiation dose optimization capability for multiphase hepatic CT relative to hybrid iterative reconstruction (HIR).

METHODS

Task-based image quality was assessed with a physical evaluation phantom; the high- and low-contrast detectability of HIR and DLR images were computed from the noise power spectrum and task-based transfer function at five different size-specific dose estimate (SSDE) values in the range 5.3 to 18.0-mGy. For the clinical study, images of 73 patients who had undergone multiphase hepatic CT under both standard-dose (STD) and lower-dose (LD) examination protocols within a time interval of about four-months on average, were retrospectively examined. STD images were reconstructed with HIR, while LD with HIR (LD-HIR) and DLR (LD-DLR). SSDE, quantitative image noise, and contrast-to-noise ratio (CNR) were compared between protocols. The noise magnitude, noise texture, streak artifact, image sharpness, interface smoothness, and overall image quality were subjectively rated by two independent radiologists.

RESULTS

In phantom study, the high- and low-contrast detectability of DLR images obtained at 5.3-mGy and 7.3-mGy, respectively, were slightly higher than those obtained with HIR at the STD protocol dose (18.0-mGy). In clinical study, LD-DLR yielded lower image noise, higher CNR, and higher subjective scores for all evaluation criteria than STD (all, p ≤ 0.05), despite having 52.8% lower SSDE (8.0 ± 2.5 vs. 16.8 ± 3.4-mGy).

CONCLUSIONS

DLR improved the subjective and objective image quality of multiphase hepatic CT compared with HIR techniques, even at approximately half the radiation dose.

Eriodictyon angustifolium extract, but not Eriodictyon californicum extract, reduces human hair greying

OBJECTIVE

Yerba Santa (Eriodictyon angustifolium and Eriodictyon californicum) has been used for many years in traditional medicine. However, the effect of Yerba Santa on melanogenesis has not yet been investigated. We aimed to assess the biological effects of Yerba Santa on hair pigmentation.

METHODS

Yerba Santa extracts were assessed for their cytological effects following X-ray irradiation treatment and then tested directly for the prevention of human hair greying. Ultra-performance liquid chromatography (UPLC) was utilized to identify the individual extract components.

RESULTS

Eriodictyon angustifolium extract significantly increased melanin synthesis in the melanoma cell line through activation of the WNT/MITF/tyrosinase-signalling pathway. In contrast, E. californicum had no effect on melanin synthesis. E. angustifolium extract also demonstrated a protective effect against the damage induced by X-ray irradiation in human keratinocytes. Application of the extracts to subjects who had grey beards demonstrated a reduced number of grey beard hair per year specifically with the E. angustifolium extract. A significant decrease in grey head hair was also observed after application of E. angustifolium extract. Upregulation of gene expression related to melanin production and WNT signalling was observed after the application of E. angustifolium extract. Sterubin was the most abundant flavonoid detected by UPLC in E. angustifolium extract. In addition, sterubin showed the highest difference in terms of quantity, between E. angustifolium and E. californicum extract.

CONCLUSION

Eriodictyon angustifolium extract, which is abundant in sterubin, may be suitable as a potential cosmetic and medical agent for the prevention and improvement of hair greying.

Low contrast material dose coronary computed tomographic angiography using a dual-layer spectral detector system in patients at risk for contrast-induced nephropathy

OBJECTIVE:

To evaluate the effects of virtual monochromatic imaging (VMI) using dual-layer spectral detector CT on the image quality of coronary CT angiography (CCTA) acquired by using a low contrast material (CM) dose.

METHODS:

We used a VMI 50keV protocol with a 50%  CM dose (140  mgI kg^-1) to scan 30 patients with renal insufficiency and a 120 kVp with the standard CM dose (280  mgI kg^-1) to scan 30 controls without renal insufficiency. Quantitative parameters, including CT attenuation, image noise, and contrast-to-noise ratio (CNR), were measured. The visual image quality factors of contrast enhancement, image noise, beam-hardening artefact, vessel sharpness, and overall image quality were scored on a 4-point scale.

RESULTS:

The mean CT attenuation of the ascending aorta was significantly higher for 50 keV VMI than for 120 kVp. Image noise was significantly lower under the 50 keV VMI. CNR and the mean visual score for contrast enhancement were significantly higher for 50 keV VMI. There were no significant differences in the other visual image quality parameters between the two protocols.

CONCLUSION:

Dual-layer spectral detector CT using 50 keV VMI enabled reducing the CM dose by 50 % without CCAT image quality degradation in patients with renal insufficiency.

ADVANCES IN KNOWLEDGE:

The VMI 50 keV protocol using dual-layer spectral detector CT and a CM dose reduced by 50 % (140 mgI kg^-1) can improve the diagnostic image quality of CCTA.

Dual-energy computed tomography colonography using dual-layer spectral detector computed tomography: Utility of virtual monochromatic imaging for electronic cleansing

OBJECTIVE

To assess the utility of virtual monochromatic imaging (VMI) using a dual-layer spectral detector CT for electronic cleansing in fecal-tagging CT colonography (CTC).

METHODS

This study included 35 patients who underwent fecal-tagging CTC with a dual-layer detector spectral CT scanner. Conventional images at 120 kVp and VMI at 40, 50, and 60 keV were reconstructed. Quantitative image quality parameters, i.e., tagging density and image noise, were compared and the visual image quality was scored on a four-point scale. We recorded the number of the colon segments with appropriate tagging density (≥300 HU) for each patient and used these data to compare the reconstructions. In addition, electronic cleansing performance was semi-quantitatively assessed using a four-point scale.

RESULTS

The mean tagging density on VMI was significantly higher than that on conventional 120 kVp images. The number of colon segments with appropriate tagging density on VMI were significantly higher than that on conventional 120 kVp images. There was no significant difference among the reconstructed images with respect to image noise. Scores for subjective image quality and electronic cleansing performance on VMI were significantly higher than those on conventional 120 kVp images.

CONCLUSION

With dual-layer spectral detector CT, VMI can yield significantly better fecal-tagged CTC image quality and improve electronic cleansing performance.

Dual-layer dual-energy computed tomography for the assessment of hypovascular hepatic metastases: impact of closing k-edge on image quality and lesion detectability

OBJECTIVES

To evaluate the image quality of virtual-monoenergetic-imaging (VMI) from dual-layer dual-energy CT (DLCT) for the assessment of hypovascular liver metastases and its effect on lesion detectability.

METHODS

Eighty-one patients with hypovascular-liver-metastases undergoing portal-venous-phase abdominal DLCT were included. Polyenergetic-images (PEI) and VMI at 40-200 keV (VMI_40-200, 10-keV interval) were reconstructed. Image noise, tumor-to-liver contrast, and contrast-to-noise ratio (CNR) of hepatic parenchyma and metastatic nodules (n = 288) were measured to determine the optimal monoenergetic levels. Two radiologists independently and subjectively assessed the image quality (image contrast, image noise, and diagnostic confidence) of PEI and optimal VMI on 5-point scales to determine the best energy. For 38 patients having up to 10 metastases each with diameters < 25 mm (153 lesions), we compared blindly assessed lesion detectability and conspicuity between PEI and VMI at the best energy.

RESULTS

Image noise of VMI_40-200 was consistently lower than that of PEI (p < 0.01). Tumor-to-liver contrast and CNR increased as the energy decreased with CNR at VMI_40-70 being higher than that observed on PEI (p < 0.01). The highest subjective score for diagnostic confidence was assigned at VMI₄₀ followed by VMI_50-70, all of which were significantly better than that of PEI (p < 0.01, kappa = 0.75). Lesion detectability at VMI₄₀ was significantly superior to PEI, especially for lesions with diameters of < 10 mm (p < 0.01, kappa ≥ 0.6).

CONCLUSIONS

VMI_40-70 provided a better subjective and objective image quality for the evaluation of hypovascular liver metastases, and the lesion detectability was improved with use of VMI₄₀ compared with conventional PEI.

KEY POINTS

• DLCT-VMI at 40-70 keV provides a superior subjective and objective image quality compared with conventional PEI for the assessment of hypovascular hepatic metastases during portal venous phase. • Tumor-to-liver contrast and CNR of hypovascular hepatic metastases was maximized at 40 keV without a relevant increase in the image noise. • VMI at 40 keV yields a superior lesion detectability, especially for small (< 1 cm) metastatic nodules compared with conventional PEI.

Model-based Iterative Reconstruction in Low-radiation-dose Computed Tomography Colonography: Preoperative Assessment in Patients with Colorectal Cancer

RATIONALE AND OBJECTIVES

To assess the effect of model-based iterative reconstruction (MBIR) on image quality and diagnostic performance of low-radiation-dose computed tomography colonography (CTC) in the preoperative assessment of colorectal cancer.

MATERIALS AND METHODS

This study included 30 patients with colorectal cancer referred for surgical treatment. All patients underwent CTC with a standard dose (SD) protocol in the supine position and a low-dose (LD; radiation dose reduction of approximately 85%) protocol in the prone position. The SD protocol images were post-processed using filtered back projection (FBP), whereas the LD protocol images were post-processed using FBP and MBIR. Objective and subjective image quality parameters were compared among the three different methods. Preoperative evaluations, including site, length, and tumor and node staging were performed, and the findings were compared to the postsurgical findings.

RESULTS

The mean image noise of SD-FBP, LD-FBP, and LD-MBIR images was 17.3 ± 3.2, 40.5 ± 10.9, and 11.2 ± 2.0 Hounsfield units, respectively. There were significant differences for all comparison combinations among the three methods (P < .01). For image noise, the mean visual scores were significantly higher for SD-FBP and LD-MBIR than for LD-FBP, and the scores for SD-FBP and LD-MBIR were equivalent (3.9 ± 0.3 [SD-FBP], 2.0 ± 0.5 [LD-FBP], and 3.7 ± 0.3 [LD-MBIR]). Preoperative information was more accurate under SD-FBP and LD-MBIR than under LD-FBP, and the information was comparable between SD-FBP and LD-MBIR.

CONCLUSION

MBIR can yield significantly improved image quality on low-radiation-dose CTC and provide preoperative information equivalent to that of standard-radiation-dose protocol.

Contrast enhancement in abdominal computed tomography: influence of photon energy of different scanners

OBJECTIVE

Different CT scanners have different X-ray spectra and photon energies indicating that contrast enhancement vary among scanners. However, this issue has not been fully validated; therefore, we performed phantom and clinical studies to assess this difference.

METHODS

Two scanners were used: scanner-A and scanner-B. In the phantom study, we compared the contrast enhancement between the scanners at tube voltage peaks of 80, 100 and 120 kVp. Then, we calculated the effective energies of the two CT scanners. In the clinical study, 40 patients underwent abdominal scanning with scanner-A and another 40 patients with scanner-B, with each group using the same scanning protocol. The contrast enhancement of abdominal organs was assessed quantitatively (based on the absolute difference between the attenuation of unenhanced scans and contrast-enhanced scans) and qualitatively. A two-tailed independent Student's t-test and or the Mann-Whitney U test were used to compare the discrepancies.

RESULTS

In the phantom study, contrast enhancement for scanner-B was 36.9, 32.6 and 30.8% higher than that for scanner-A at 80, 100 and 120 kVp, respectively. The effective energies were higher for scanner-A than for scanner-B. In the quantitative analysis for the clinical study, scanner-B yielded significantly better contrast enhancement of the hepatic parenchyma, pancreas, kidney, portal vein and inferior vena cava compared with that of scanner-A. The mean visual scores for contrast enhancement were also significantly higher on images obtained by scanner-B than those by scanner-A.

CONCLUSION

There were significant differences in contrast enhancement of the abdominal organs between the compared CT scanners from two different vendors even at the same scanning and contrast parameters. Advances in knowledge: Awareness of the impact of different X-ray energies on the resultant attenuation of contrast material is important when interpreting clinical CT images.

Dual-region-of-interest bolus-tracking technique for coronary computed tomographic angiography on a 320-row scanner: reduction in the interpatient variability of arterial contrast enhancement

OBJECTIVE

We compared the effect of a dual-region-of-interest (ROI) bolus-tracking technique on interpatient variability of arterial contrast enhancement with that of the conventional bolus-tracking technique in coronary computed tomographic angiography (CTA) on a 320-row scanner.

METHODS

This study included 100 patients who underwent coronary CTA using one of two protocols: (1) 50 patients underwent scanning using a conventional single-ROI bolus-tracking technique (P-single) with an ROI placed in the ascending aorta, and (2) 50 patients underwent scanning using a dual-ROI technique (P-dual) with two ROIs placed in the pulmonary trunk and the ascending aorta. CT attenuation in the ascending aorta and coronary arteries, and the interpatient variability were compared between the two scanning protocols.

RESULTS

The mean CT attenuation of the ascending aorta and coronary arteries tended to be higher for P-dual than for P-single, but the difference was not significant (p = 0.08-0.30). The interpatient variability of contrast enhancement (SD of the CT attenuation) was significantly smaller for P-dual than for P-single (p < 0.01).

CONCLUSION

The dual-ROI bolus-tracking technique can reduce interpatient variability of arterial contrast enhancement in coronary CTA on a 320-row scanner. Advances in knowledge: The use of a dual-ROI bolus-tracking technique can provide sufficient and consistent arterial enhancement of coronary CTA.

Dual-layer DECT for multiphasic hepatic CT with 50 percent iodine load: a matched-pair comparison with a 120 kVp protocol

OBJECTIVES

To evaluate the image quality and lesion conspicuity of virtual-monochromatic-imaging (VMI) with dual-layer DECT (DL-DECT) for reduced-iodine-load multiphasic-hepatic CT.

METHODS

Forty-five adults with renal dysfunction who had undergone hepatic DL-DECT with 300-mgI/kg were included. VMI (40-70-keV, DL-DECT-VMI) was generated at each enhancement phase. As controls, 45 matched patients undergoing standard 120-kVp protocol (120-kVp, 600-mgI/kg, and iterative reconstruction) were included. We compared the size-specific dose estimate (SSDE), image noise, CT attenuation, and contrast-to-noise ratio (CNR) between protocols. Two radiologists scored the image quality and lesion conspicuity.

RESULTS

SSDE was significantly lower in DL-DECT group (p < 0.01). Image noise of DL-DECT-VMI was almost constant at each keV (differences of ≤15%) and equivalent to or lower than of 120-kVp. As the energy decreased, CT attenuation and CNR gradually increased; the values of 55-60 keV images were almost equivalent to those of standard 120-kVp. The highest scores for overall quality and lesion conspicuity were assigned at 40-keV followed by 45 to 55-keV, all of which were similar to or better than of 120-kVp.

CONCLUSIONS

For multiphasic-hepatic CT with 50% iodine-load, DL-DECT-VMI at 40- to 55-keV provides equivalent or better image quality and lesion conspicuity without increasing radiation dose compared with standard 120-kVp protocol.

KEY POINTS

• 40-55-keV yields optimal image quality for half-iodine-load multiphasic-hepatic CT with DL-DECT. • DL-DECT protocol decreases radiation exposure compared with 120-kVp scans with iterative reconstruction. • 40-keV images maximise conspicuity of hepatocellular carcinoma especially at hepatic-arterial phase.

Saturation Recovery Myocardial T1 Mapping with a Composite Radiofrequency Pulse on a 3T MR Imaging System

PURPOSE

To evaluate the effect of a composite radiofrequency (RF) pulse on saturation recovery (SR) myocardial T₁ mapping using a 3T MR system.

MATERIALS AND METHODS

Phantom and in vivo studies were performed with a clinical 3T MR scanner. Accuracy and reproducibility of the SR T₁ mapping using conventional and composite RF pulses were first compared in phantom experiments. An in vivo study was performed of 10 healthy volunteers who were imaged with conventional and composite RF pulse methods twice each. In vivo reproducibility of myocardial T₁ value and the inter-segment variability were assessed.

RESULTS

The phantom study revealed significant differences in the mean T₁ values between the two methods, and the reproducibility for the composite RF pulse was significantly smaller than that for the conventional RF pulse. For both methods, the correlations of the reference and measured T₁ values were excellent (r² = 0.97 and 0.98 for conventional and composite RF pulses, respectively). The in vivo study showed that the mean T₁ value for composite RF pulse was slightly lower than that for conventional RF pulse, but this difference was not significant (P = 0.06). The inter-segment variability for the composite RF pulse was significantly smaller than that for conventional RF pulse (P < 0.01). Inter-scan correlations of T₁ measurements of the first and second scans were highly and weakly correlated to composite RF pulses (r = 0.83 and 0.29, respectively).

CONCLUSION

SR T₁ mapping using composite RF pulse provides accurate quantification of T₁ values and can lessen measurement variability and enable reproducible T₁ measurements.

Cardiovascular magnetic resonance myocardial T1 mapping to detect and quantify cardiac involvement in familial amyloid polyneuropathy

OBJECTIVES

This study sought to explore the potential role of non-contrast T1 mapping for the detection and quantification of cardiac involvement in familial amyloid polyneuropathy (FAP).

METHODS

Japanese patients with FAP [n = 41, age 53.2 ± 13.9 years, genotype Val30Met (n = 25), non-Val30Met (n = 16)] underwent cardiac magnetic resonance imaging that included T1 mapping (saturation-recovery method) and late gadolinium-enhanced (LGE) imaging on a 3.0-T MR scanner. Their native T1 was measured on mid-ventricular short-axis images and compared with 30 controls.

RESULTS

Of the 41 FAP patients 29 were LGE positive. The native T1 was significantly higher in FAP patients than in the controls (1,634.1 ± 126.3 ms vs. 1,432.4 ± 69.0 ms, p < 0.01), significantly higher in LGE-positive- than LGE-negative FAP patients (1,687.1 ± 104.4 ms vs. 1,505.4 ± 68.5 ms, p < 0.01), and significantly higher in LGE-negative FAP patients than the controls (p < 0.01). A native T1 cutoff value of 1,610 ms yielded 85.4% accuracy for identifying LGE-positive FAP. The native T1 significantly correlated with the interventricular septum wall thickness, the left ventricular mass, the LGE volume, the plasma B-type natriuretic peptide level, and the E/e' ratio (all p < 0.01).

CONCLUSION

T1 mapping is of high diagnostic accuracy for the detection of LGE-positive FAP. The native myocardial T1 may be correlated with the severity of cardiac amyloid deposition.

KEY POINTS

• The native T1 was higher in FAP patients than the controls. • The native T1 was higher in LGE-positive- than LGE-negative FAP patients. • The native T1 was higher in LGE-negative FAP patients than the controls. • The native T1 correlated with clinical markers of systolic and diastolic dysfunction. • Myocardial T1 mapping is of high diagnostic accuracy for detecting LGE-positive FAP.

Dynamic Viscoelasticity of Soft Liners and Masticatory Function

Soft denture liners are used for edentulous patients to cushion functional forces. We hypothesized that the application of soft liners having viscoelastic properties would lead to the most marked improvement in masticatory function. The shear storage modulus ( G′), shear loss modulus ( G′′), and loss tangent (tan δ) were determined for 6 materials by means of a dynamic viscoelastometer. Masticatory function of ten subjects was evaluated by measurements of maximum bite forces and chewing times and frequencies for 2 food samples, and by the use of visual analogue scales. The acrylic materials exhibited viscoelastic behavior, while the silicones exhibited elastic behavior. The improvement in masticatory function compared with hard resin was found to be in the order: acrylic permanent materials > silicone > acrylic temporary materials. The results suggest that the use of materials with higher tan δ and G′ provides the most optimum masticatory function for patients requiring the provision of soft liners on their dentures.

The Influence of Iterative Reconstruction on Coronary Artery Calcium Scoring-Phantom and Clinical Studies

RATIONALE AND OBJECTIVES

We compared the effect of iterative model reconstruction (IMR), filtered back projection (FBP), and hybrid iterative reconstruction (HIR) on coronary artery calcium (CAC) scoring.

MATERIALS AND METHODS

CAC scans of 30 consecutive patients (18 men and 12 women, age 70.1 ± 12.2 years) were reconstructed with FBP, HIR, and IMR, and the image noise was measured on all images. Two radiologists independently measured the CAC scores using semiautomated software, and interobserver agreement was evaluated. Statistical analysis included the Spearman correlation coefficient and Bland-Altman analysis.

RESULTS

The mean image noise on FBP, HIR, and IMR images was 48.0 ± 7.9, 29.6 ± 4.8, and 9.3 ± 1.3 Hounsfield units, respectively. The difference among all reconstruction combinations was significant (P < .01). The CAC score on HIR and IMR scans was 4.2% and 8.9% lower, respectively, than the CAC score on FBP images. There was no significant difference in the mean CAC score among the three reconstructions. The interobserver correlation was excellent for all three reconstructions (r² = 0.96 FBP, 0.99 HIR, 0.99 IMR); the best Bland-Altman measure of agreement was with IMR, followed by HIR and FBP.

CONCLUSION

For CAC scoring, IMR can reduce the image noise and blooming artifacts, and consequently lowers the measured CAC score. IMR can lessen measurement variability and yield stable, reproducible measurements.

Study of factors related to the reflection abilities of dental trainees

INTRODUCTION

This study analysed the internal and external factors related to the reflection abilities of dental trainees.

PARTICIPANTS AND METHODS

We created transcripts from oral presentations by the dental trainees of Hiroshima University Hospital (n = 35, 2012-2013) at a significant event analysis conference. The reflection depths were compared between the trainees of the university hospital and external clinical combination groups. We determined and statistically analysed the reflection depths.

RESULTS

At the end of training, a Mann-Whitney U-test revealed a significant difference in the median reflection depths of the groups (U = 66, W = 342 and P = 0.007). The results of multiple regression analysis indicated a significant relation between the reflection depth and external training completion (P = 0.024). There were no relations with other factors, including gender and academic background.

CONCLUSION

Experiences in external clinics create a close connection between the staff and trainees because communities of practice can cause deeper reflections. We need to create small groups in large-scale organisations such as university hospitals. This construct can be adapted not only for Japanese dental trainees but also for global dental and other medical trainees.

CT Angiography in Patients with Peripheral Arterial Disease: Effect of Small Focal Spot Imaging and Iterative Model Reconstruction on the Image Quality

RATIONALE AND OBJECTIVES

We investigated the effects of small focal spot (SFS) imaging and iterative model reconstruction (IMR) on the image quality of computed tomography angiographs (CTA) in patients with peripheral arterial disease.

MATERIALS AND METHODS

We divided 60 consecutive patients with suspected or confirmed peripheral artery disease into two equal groups. One group underwent large focal spot scanning under our standard CTA protocol with hybrid iterative reconstruction (iDose(4)) (protocol 1), and the other underwent scanning with the SFS protocol and IMR (protocol 2). Quantitative image quality parameters, ie, arterial computed tomography attenuation, image noise, and the contrast-to-noise ratio, were compared and the visual image quality (depiction of each vessel) was scored on a 5-point scale.

RESULTS

There was no significant difference in the arterial attenuation among all evaluated slice levels. The mean image noise was significantly lower under protocol 2 and the contrast-to-noise ratio was significantly higher at all slice levels. The visual scores assigned to the two protocols for the depiction of large vessels, such as the abdominal aorta and iliac artery, were comparable. However, the mean visual scores for small vessels in the lower extremities were significantly higher under protocol 2.

CONCLUSION

CTA with SFS and IMR yielded significantly better qualitative and quantitative image quality especially for small vessels.

Effectiveness of a simulated patient training programme based on trainee response accuracy and appropriateness of feedback

INTRODUCTION

Simulated patients (SPs) need education and training in required skills to be effective resources in education. This study was conducted to examine the effectiveness of an SP training programme based on the accuracy of trainee responses and the appropriateness of their feedback.

METHODS

Thirty-two applicants to the training programme and 35 experienced SPs were included in this study. The experienced SPs served as a reference group. The rate of accurate responses and the rate of appropriate feedback were assessed with pre- and post-training tests, and these two outcome measures were compared with those of the experienced SPs.

RESULTS

No significant differences were found in trainee response accuracy or appropriateness of feedback between pre- and post-training tests. The response accuracy rate of the trainees on the pre-training test was significantly lower than that of SPs with 1-2 years of experience, whilst there was no significant difference between these SPs and the trainees on the post-training test.

CONCLUSIONS

Although our study suggests that more training is needed to improve the skills of SPs, the training programme may contribute to helping trainees reach a novice level in the skill of providing accurate responses. SP training should be encouraged to contribute to the effectiveness of such teaching and to establish the validity of the assessment.

OSCEs in Japanese postgraduate clinical training Hiroshima experience 2000-2009

BACKGROUND

Hiroshima University Hospital used the Objective Structured Clinical Examination (OSCE) as a formative and summative assessment tool to evaluate trainees' competence.

AIM

To reflect on Hiroshima University Hospital experience of OSCEs in postgraduate training in terms of OSCE structure and trainees' perception of the OSCE they attended.

METHODS

A total 27 OSCEs implemented in Hiroshima University Hospital from 2000 to 2009 were examined. The OSCE in postgraduate training, Hiroshima University Hospital, was influenced by many factors from organisational and pedagogical perspectives, and changed to meet social and curriculum needs. At each OSCE, all examinees were required to answer an anonymous questionnaire, which consisted of ten checklists, just after their experience of OSCE.

RESULTS

Five hundred and forty trainees who attended each OSCE were required to answer a questionnaire and 510 were returned (94.4%). In the comparison between formative and summative OSCEs, the number of trainees who answered "the OSCE is meaningful" in formative OSCE was significantly higher than that in summative OSCE (P < 0.001). In the comparison between before and after the 2006/2007 academic year, trainees who indicated that OSCEs were meaningful increased after 2006/2007 (P < 0.05), and trainees who felt they were evaluated appropriately by these OSCEs increased after 2006/2007 (P < 0.01).

CONCLUSION

Trainees viewed OSCEs positively and appreciated their effectiveness from a pedagogical perspective, and OSCE positively affected the trainees' approach to learning. A ten-year process of OSCE change has helped with educational reforms because of its adaptability. Flexible attitudes to change are necessary for stakeholders to achieve the desired reforms.

Influence of socio-economic background and antenatal care programmes on maternal mortality in Surabaya, Indonesia

OBJECTIVE

To determine the risk factors, such as socio-economic background, quality of antenatal care and availability of family planning, responsible for high maternal mortality in Surabaya, Indonesia.

METHODS

The study used a case-control design. Descriptive, bivariate and multivariate analyses were carried out, comparing 59 maternal deaths and 177 women survivors in the referral hospital, from 1996 to 1999.

RESULTS

The risk factors for maternal mortality were: living outside of Surabaya [odds ratio (OR) = 11.7, 95% confidence interval (CI) = 5.0-29.2], unemployment (OR = 4.4, 95% CI = 1.7-13.8), unavailability of toilet facilities (OR = 2.9, 95% CI = 1.0-7.7), <4 antenatal visits (OR = 2.5, 95% CI = 1.1-5.5) and initial visit to antenatal care facilities after the fourth month of pregnancy (OR = 3.0, 95% CI = 1.3-7.0). There was no significant association between maternal mortality and the availability of family planning.

CONCLUSION

Low socio-economic background and the availability of antenatal care have a significant influence on maternal mortality in Surabaya, Indonesia.

Hemodynamic responses among three tracheal intubation devices in normotensive and hypertensive patients

We compare hemodynamic responses in normotensive and hypertensive anesthetized paralyzed patients among three intubation devices: the Macintosh laryngoscope (LS), the Trachlight lightwand (LW), and the intubating laryngeal mask airway Fastrach (ILM). Seventy-five normotensive and 75 hypertensive patients were randomly assigned to each intubation device (n = 25). Noninvasive systolic blood pressure (SBP) and diastolic blood pressure (DBP) and heart rate (HR) were recorded immediately preinduction, immediately preintubation, and every minute for the first 5 min after the successful intubation. The number of intubation attempts, the time to successful intubation, and any airway injuries were recorded. Pharyngolaryngeal morbidity was assessed 18-24 h after surgery by a blinded investigator. In all groups, there was a reduction in SBP and DBP but no change in HR immediately preintubation compared with baseline values. In all groups, HR increased, but there were no increases in SBP and DBP other than in DBP in the LS/hypertensive group after intubation compared with baseline values. In normotensive patients, there were no differences in any hemodynamic variables among the three devices. In hypertensive patients, SBP and DBP in the LS group were significantly higher than the ILM and LW groups for 2 min after intubation, but there were no differences in HR among the devices. The number of intubation attempts was similar among groups, but intubation time was longer for the ILM group. The incidence of airway injury was more frequent for the ILM than the LS and LW groups (16% versus 0% versus 0%). There were no differences in pharyngolaryngeal morbidity among groups. We conclude that both the ILM and the LW attenuated the hemodynamic stress response to tracheal intubation compared with the LS in hypertensive, but not in normotensive, anesthetized paralyzed patients.

IMPLICATIONS

Both the intubating laryngeal mask airway Fastrach and the Trachlight lightwand attenuate the hemodynamic stress response to tracheal intubation compared with the Macintosh laryngoscope in hypertensive, but not in normotensive, anesthetized paralyzed patients.

Human GLUT5 immunolabeling is useful for evaluating microglial status in neuropathological study using paraffin sections

In neuropathological studies it is important to detect both resting and reactive microglia in paraffin sections. We examined the usefulness of human (h) GLUT5, a glucose transporter, as a microglial marker. We produced an hGLUT5 antibody against its C-terminal sequence and stained human brain tissue sections. The hGLUT5 antibody consistently stained microglia in cryostat sections. In paraffin sections fixed with formalin, paraformaldehyde or ethanol, both resting and reactive microglia were stained; the latter were stained more intensely than the former. The hGLUT5 and glial fibrillary acidic protein labeling did not overlap each other in double immunofluorescence analyses. Oligodendrocytes, perivascular cells, choroid plexus epithelium and ependymal cell were negative for hGLUT5. Even after 1-month fixation in formalin, the hGLUT5 antibody stained microglia well. Microwave pretreatment enhanced the immunoreactivity of hGLUT5. As compared with other microglial markers, KP-1, KiM1p, CR3.43 and RCA-1, the hGLUT5 antibody could be considered good morphological marker. hGLUT5 immunolabeling clearly showed the detailed microglial processes, whereas immunolabeling with Ki-M1P and KP-1 showed cytoplasmic granules, and it was difficult to trace the microglial processes. The hGLUT5 antibody stained both resting and reactive microglia, whereas CR3.43 stained only reactive microglia, and RCA-1 labeled microvessels more intensely than microglia. Thus, hGLUT5 is a marker that is suitable for routine histopathological staining procedures.

Intubating laryngeal mask airway size selection: a randomized triple crossover study in paralyzed, anesthetized male and female adult patients

We determined the optimal size of intubating laryngeal mask airway (ILM) for ventilation and blind tracheal intubation in men and women. We also determined the distance the tracheal tube needs to protrude beyond the distal aperture to ensure that the cuff is through the vocal cords. Fifty male and 50 female anesthetized, paralyzed patients (ASA physical status I or II, aged 18-80 yr) were studied. Three operators (A, B, and C) were involved for the purposes of blinding. The size 3, 4, or 5 ILM was inserted into each patient in random order by Operator A, and the quality of ventilation was scored (adequate, suboptimal, or failed) by Operator B. The fiberoptic position (correct, too shallow, or too deep) and the distance between the distal aperture and the vocal cords was determined by Operator B. A single attempt at blind intubation was made by Operator C. Operators B and C were blinded to the size of the ILM. Operator C was also blinded to the information recorded by Operator B. All ILMs were inserted into the laryngopharynx at the first attempt. For men and women, the ventilation score was smaller for the Size 3 than the Size 4 or 5 (all: P < 0.002). For men, correct positioning was less common with the Size 3 than the Size 4 or 5 (both: P < 0.02). For women, correct positioning was similar among sizes. For men, tracheal intubation was successful less frequently with the Size 3 (84%) than the Size 4 (100%) or 5 (98%) (both: P < or = 0.01). For women, tracheal intubation success was similar among sizes (Size 3, 4, and 5: 86%, 96%, and 92%, respectively). Intubation was always successful if the ILM was correctly positioned and always failed if it was too shallow or deep. In both male and female patients, the distance between the distal aperture and the vocal cords increased with increasing ILM size (all: P < 0.04) and patient height (P < 0.0001) and was always longer for men (all: P < 0.0001). The overall mean distance (95% confidence interval) that the tracheal tube needed to protrude was 10-12 cm (8-13 cm) in men and 8-11 cm (8-12 cm) in women. We conclude that for men, the Size 4 and 5 ILMs are better than the Size 3 for ventilation and blind intubation. For women, the Size 4 and 5 ILMs are better than the Size 3 for ventilation, but there is no difference among sizes for blind intubation. The length the tracheal tube must protrude from the distal aperture to ensure that the cuff is completely through the vocal cords is 8-13 cm, depending on ILM size, the tracheal tube size, and the sex and height of the patient.

IMPLICATIONS

For men, the Size 4 and 5 intubating laryngeal mask airways are better than the Size 3 for ventilation and blind tracheal intubation. For women, the Size 4 and 5 are better than the Size 3 for ventilation, but there is no difference among sizes for blind intubation. The length the tracheal tube must protrude from the distal aperture of the intubating laryngeal mask airway to ensure that the cuff is completely through the vocal cords is 8-13 cm, depending on the size of the mask and tracheal tube and on the sex and height of the patient.

Dynamic viscoelasticity of soft liners and masticatory function

Soft denture liners are used for edentulous patients to cushion functional forces. We hypothesized that the application of soft liners having viscoelastic properties would lead to the most marked improvement in masticatory function. The shear storage modulus (G'), shear loss modulus (G''), and loss tangent (tan delta) were determined for 6 materials by means of a dynamic viscoelastometer. Masticatory function of ten subjects was evaluated by measurements of maximum bite forces and chewing times and frequencies for 2 food samples, and by the use of visual analogue scales. The acrylic materials exhibited viscoelastic behavior, while the silicones exhibited elastic behavior. The improvement in masticatory function compared with hard resin was found to be in the order: acrylic permanent materials > silicone > acrylic temporary materials. The results suggest that the use of materials with higher tan delta and G' provides the most optimum masticatory function for patients requiring the provision of soft liners on their dentures.

Effect of viscoelastic properties of resilient denture liners on pressures under dentures

In order to evaluate the influence of viscoelastic properties of resilient denture liners on the pressures under dentures, a series of creep and stress relaxation tests were carried out using a simplified mandibular edentulous model and denture model. Two diaphragm pressure sensors were attached to the edentulous model so that they contacted the residual ridge and the buccal slope. The results may be summarized as follows: (i) The use of resilient denture liners is effective for stress relief under dentures. (ii) The thickness increase of each denture liners causes the effect of stress relaxation. (iii) The material exhibited viscoelastic behaviour after applying the stress and has the ability to distribute stress or stress relaxation. It is important to understand the viscoelastic behaviours of each resilient denture liner and choose the material according to the clinical situation. The information obtained should be useful to clinicians when they select materials for their patients.

Effect of triacylglycerols containing medium- and long-chain fatty acids on body fat accumulation in rats

Effect of triacylglycerols containing medium- and long-chain fatty acids (TML) on body fat accumulation was studied in rats. Male Wistar rats were fed an experimental diet containing 25% soybean oil or TML for 6 weeks. The food intake for 6 weeks did not significantly differ between the two diet groups. However, the perirenal and mesenteric adipose tissue weight and carcass fat content were significantly lower in the TML diet group than in the soybean oil diet group. The epididymal adipose tissue weight and liver triacylglycerol content did not significantly differ between the two diet groups. The digestibility of dietary fat did not significantly differ between the two diet groups. These results suggest that an intake of TML decreases body fat accumulation compared to an intake of soybean oil in rats.

Routine use of the intubating laryngeal mask airway results in increased upper airway morbidity

PURPOSE

The classic laryngeal mask airway (LMA) has a soft, silicone tube and the intubating laryngeal mask airway (ILM) has a rigid, silicone-coated steel tube. We compare postoperative pharyngolaryngeal morbidity in patients randomised to receive either device.

METHODS

Sixty-five female patients (ASA physical status class I or II, aged 18-80 yr) undergoing balanced regional anesthesia for gynecological laparotomy expected to last one to two hours were randomly assigned for airway management with the LMA or ILM. Intracuff pressure was maintained at 60 cm H20. Postoperative pharyngolaryngeal morbidity (sore throat, difficulty swallowing, sore mouth, sore neck/jaw, hoarseness) was assessed at two, 24 and 48 hr by blinded investigators.

RESULTS

The number of insertion attempts and duration of anesthesia was similar between groups. Sore throat was more common for the ILM at two hours (44 vs 15%, P=0.01), 24 hr (59 vs 21%, P=0.008) and 48 hr (34 vs 3%, P=0.005). Sore mouth was more common for the ILM at two hours (16 vs 0%, P=0.02) and 24 hr (12 vs 0%, P=0.04), but not at 48 hr (6 vs 3%). Difficulty swallowing was more common for the ILM at two hours (25 vs 0%, P=0.04), but not at 24 hr (31 vs 3%) and 48 hr (12 vs 9%). There were no differences in the incidence of sore jaw/neck (ILM, 3-12%; LMA, 0-3%) and hoarseness (ILM, 12-31%; LMA, 16-18%). There was no correlation between postoperative pharyngolaryngeal morbidity and duration of anesthesia.

CONCLUSION

Pharyngolaryngeal morbidity is more common with the ILM than the LMA following anesthesia lasting one to two hours.

Increased expression of mXBP-1 (TREB-5) in thymic B cells in New Zealand mice

New Zealand Black mice as well as several other murine models of murine lupus are well known for premature degeneration of thymus and development of autoimmunity. To focus on molecular events unique to murine lupus, we performed differential display using arbitrary primer pairs to distinguish NZB versus BALB/c thymus at 5 weeks of age. Following an extensive analysis of DNA bands that were either consistently up or downregulated and from studies of expression pattern of thymic genes by in situ nucleic acid hybridization, we focused on one clone that was consistently differentially expressed between NZB and BALB/c thymus. This clone was isolated, sequenced, and identified as the murine homologue of the human X box binding protein (hXBP-1), also known as TREB 5. mXBP-1 was found to be consistently upregulated in B cells in the thymic cortex of NZB and (NZBxNZW)F1, but not BALB/c, C3H/HeJ or C57BL/6 mice. In addition, it was dramatically elevated in MRL/ lpr but not MRL/++ mice; similarly, it was increased in BXSB/ Yaa male but not BXSB female thymic cortex. Of particular interest was an absence of mXBP-1 expression in the thymus of NZB/ Bln- Igh6(null)homozygotes. mXBP-1 has several putative functions, including the regulation of MHC class II expression and by virtue of its ability to recognize CRE-like elements shown to be involved in HTLV-1 transcription.

B cells are selectively associated with thymic cortical but not medullary pathology in NZB mice

Abnormal expansion of autoantibody-synthesizing B cells and self-reactive T cells, which most likely escape negative selection within the thymus, have both been characterized and reasoned to play a role in the pathogenesis of autoimmunity in NZB mice. Support for this thesis has been our observation that NZB mice have severe cortical and medullary thymic microarchitectural defects. As a means to dissect the roles of T and B cells in the induction of such abnormalities, B cell-deficient NZB mice were bred by backcrossing the Igh6(null)allele on to the NZB background (NZB-muMT mice). Such mice showed undetectable levels of autoantibodies. NZB-muMT mice, as compared to wild-type NZB mice, had lower absolute numbers of CD4(+)T cells. Furthermore, thymic abnormalities in NZB-muMT mice were restricted to the medulla. These data suggest that, while B cells may play a role in thymic cortical abnormalities, the medullary abnormalities are induced by other mechanisms.

The thermic effect is greater for structured medium- and long-chain triacylglycerols versus long-chain triacylglycerols in healthy young women

The purpose of this study was to investigate the hypothesis that a single dose of structured medium- and long-chain triacylglycerols (SMLCTs) composed of medium-chain (20%) and long-chain (80%) fatty acids would increase the metabolic rate more than a dose of long-chain triacylglycerols (LCTs) in 15 healthy young women aged 18 to 28 years. The effects on postingestive energy expenditure were compared for SMLCTs versus LCTs. On the experimental days, the subjects fasted overnight and then ingested 1,680 kJ SMLCTs or LCTs each day. Energy expenditure and the respiratory quotient (RQ) were measured before and after SMLCT and LCT ingestion by indirect calorimetry. Blood samples were collected before and after ingestion to obtain plasma and serum. Postingestive total energy expenditure (PTEE) was significantly higher after SMLCT ingestion versus LCT ingestion (26.9 +/- 1.0 v 25.5 +/- 1.1 kJ/kg/6 h, P < .05). The thermic effects of the test oil were also significantly greater after SMLCT ingestion compared with LCT ingestion (3.02 +/- 0.49 v 1.47 +/- 0.82 kJ/kg/6 h, P < .01). Plasma glucose and serum triacylglycerol concentrations were not significantly different. Serum free fatty acid and 3-hydroxybutyric acid concentrations were higher after SMLCT ingestion versus LCT ingestion. These results suggest that long-term substitution of SMLCTs for LCTs will produce body fat loss if energy intake remains constant.

Airway rescue with the intubating laryngeal mask in a patient with an unexpectedly large epiglottic cyst

We report the successful use of the intubating laryngeal mask airway for rescue and intubation in an anaesthetised patient with an unexpectedly large epiglottic cyst. This case illustrates that airway rescue and intubation with the intubating laryngeal mask is possible and preoperative airway assessment does not always provide reliable information about airway management.

Haemodynamic responses to the intubating laryngeal mask and timing of removal

We determined (a) the haemodynamic responses to intubating laryngeal mask (ILM) airway insertion/intubation and removal in anaesthetized patients, and (b) whether the timing of ILM removal influences these responses. One-hundred and twenty patients without cardiovascular disease were studied. ILM airway insertion/intubation was 5 min after induction with propofol 2 mg kg(-1) and maintenance of anaesthesia with sevoflurane 2% in oxygen 33% and nitrous oxide. Patients were randomly assigned for removal of the intubating laryngeal mask airway at 1, 3 and 5 min after successful intubation. Systolic and diastolic arterial pressures and heart rate were recorded preinduction (baseline), before ILM airway insertion/intubation, at 1-min intervals after insertion/intubation, and at 1-min intervals for 5 min after ILM removal. ILM insertion was successful at the first attempt in all patients, but 46 patients required more than one intubation attempt. Compared with baseline values, there were no increases in systolic or diastolic arterial pressure, but there was an increase in heart rate 1 min after ILM insertion/intubation (9%, P<0.001) and 1 min after ILM removal (8%, P<0.01). There was a significant increase in systolic and diastolic pressures and heart rate 1 min after ILM insertion/intubation (30%, 31% and 15%; all: P<0.002) compared with before ILM insertion/intubation values and 1 min after ILM removal (9%, 8% and 7%; all P<0.05) compared with 1 min after ILM insertion/intubation values. Removal of the ILM 1 min after successful intubation resulted in higher arterial pressure compared with removal at 3 min (systolic arterial pressure 10% higher for 1 min, P = 0.01) and 5 min (systolic arterial pressure 10-23% higher for 3 min, P<0.01; diastolic arterial pressure 10-20% higher for 4 min, P>0.02), but there were no differences in heart rate between groups. Systolic and diastolic arterial pressures were greater if more than one intubation attempt was required. Early removal or multiple intubation attempts did not exceed baseline haemodynamic values. We conclude that ILM insertion/intubation and removal in anaesthetized patients produces little or no haemodynamic response, even if multiple intubation attempts are required. The timing of removal exerts a small, but clinically unimportant influence on these responses.

Tissue inhibitor of metalloproteinases-1, matrix metalloproteinases-1 and -8, and collagenase activity levels in peri-implant crevicular fluid after implantation

The integrity of connective tissues surrounding dental implants may be influenced by a balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). The purpose of this study was to provide an overall assessment of TIMP-1, MMP-1 and -8 levels as well as collagenase activities during the wound healing process after implantation and in peri-implantitis lesions. Peri-implant crevicular fluid (PICF) was sampled with sterile paper strips from 10 osseointegrated implants of 6 subjects. Ten implants from 6 patients affected with peri-implantitis were also assessed. Gingival crevicular fluid (GCF) from 11 periodontitis-affected patients and 10 healthy volunteers served as controls. TIMP-1 and MMP-1 and -8 protein levels in the PICF were measured by ELISA, and active and APMA-activatable collagenase activities were determined by functional assays using image-analysis after SDS-PAGE. The experiment showed a significant increase in the TIMP-1 level at 1 week after implantation as compared with that in GCF from healthy periodontium. Four weeks after implantation it had reached the same level as that in the GCF of healthy subjects. The data has also disclosed a higher post-implantation collagenase activity level at 1 week than at weeks 2, 4, and 12. This may be due to the increase in MMP-1 and -8. Furthermore, peri-implantitis and periodontitis were shown to be similar inflammatory lesions in respect to MMP-1 and -8 and collagenase activities, even though the TIMP-1/MMP-1 + MMP-8 ratio was significantly lower in peri-implantitis than in periodontitis. In conclusion, the overproduction of TIMP-1 in the wound area after implantation could, to some extent, inhibit excessive tissue destruction and degradation of the neo-matrix in wound repair due to MMPs.

Determination of sugar alcohols in confectioneries by high-performance liquid chromatography after nitrobenzoylation

A method was developed for the determination of sugar alcohols, meso-erythritol, xylitol, D-glucitol, D-mannitol, maltitol and parachinit by high-performance liquid chromatography (HPLC). The sugar alcohols were converted into strong ultraviolet (UV)-absorbing derivatives with p-nitrobenzoyl chloride. HPLC was performed on a phenyl column, using acetonitrile-water (67:33) as mobile phase and UV detection (260 nm). The calibration curves for all sugar alcohols tested were linear in the 10-250 microg/ml range. The average recoveries of the sugar alcohols from four sugarless confectioneries spiked at 5 and 10% levels of six sugar alcohol standards ranged from 73.2 to 109.0% with relative standard deviations ranging from 0.7 to 9.0%. The detection limit of the developed method was 0.1% for the above sugar alcohols contained in the samples.

Long-term changes of hydroxyapatite-coated dental implants

There are many controversies about the long-term prognosis of hydroxyapatite (HA)-coated implants. Failure may be related to compositional and structural changes of the coating occurring during implantation. Two retrieved and two unused HA-coated blade-type implants were examined by stereomicroscopy, secondary electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electron probe microanalysis. The objective was to investigate the HA morphology, composition, and structure, and to characterize the changes that occurred in the retrieved implant coatings. Retrieved implants presented partial loss of the coating, especially at the apical and mesiodistal edges. Remaining HA was thick and flattened in the cervical and central areas and gradually thinner and rougher towards the apical and mesiodistal edges. Increase of Cl and Mg, decrease of OH, and X-ray diffraction peak broadening were found in the retrieved implant coatings, in comparison with the unused implants. Morphological changes of the retrieved implants seem to depend on stress values in the surrounding bone and on implant mobility. Compositional changes and increased amount of lattice imperfections appeared in the retrieved implant coatings, as a result of ion substitutions in the apatite lattice. However, the present study could not confirm the influence of these changes on implant failure.

Dynamic viscoelastic properties and the age changes of long-term soft denture liners

The dynamic viscoelastic properties of long-term soft denture liners were measured over a wide range of frequencies using a dynamic viscoelastometer based on a non-resonance-forced vibration principle. Changes in properties over a 3 yr period have also been monitored. One acrylic material, one fluoroelastomer, one heat cured silicone and one self-curing addition silicone were used. Complex dynamic tensile modulus (E*), tensile storage modulus (E'), tensile loss modulus (E") and loss tangent (tan delta) were determined over the frequency range from 0.01 to 100 Hz on administration of a 0.27% strain at 37 degrees C. The dynamic viscoelasticity of the acrylic and fluoroelastomer products was more sensitive to changes in frequency than that of silicone products. The acrylic material and fluoroelastomer exhibited viscoelastic behaviour whilst silicones exhibited elastic behaviour. The silicone products remained unchanged after soaking for 3 yr whilst the acrylic and fluoroelastomer products underwent significant change.

Segmental cervical spine movement with the intubating laryngeal mask during manual in-line stabilization in patients with cervical pathology undergoing cervical spine surgery

We quantified the extent and distribution of segmental cervical movement produced by the intubating laryngeal mask (ILM) during manual in-line stabilization in 20 anesthetized patients with cervical pathology undergoing cervical spine surgery. All patients had neurological symptoms preoperatively. The ILM was inserted with the head and neck in the neutral position. Intubation was facilitated by transillumination of the neck with a lightwand. Cervical movement was recorded with single-frame lateral radiographic images taken 1) immediately before induction (baseline); 2) during ILM insertion (insertion); 3) when transillumination was first seen at the cricothyroid membrane (intubation A); 4) when the tube was being advanced into the trachea (intubation B); and 5) during ILM removal (removal). Radiographic images were digitized and the degree of flexion/extension and posterior movement measured for the occiput (C0) through to C5. During ILM insertion, C0-5 were flexed by an average of 1-1.6 degrees (all P < 0.05). During intubation A/B, C0-4 were flexed by an average of 1.4-3.0 degrees (all P < 0.01), but C5 was unchanged. During ILM removal, C0-3 were flexed by an average of 1 degree (all: P < 0.05), but C3-5 were unchanged. During insertion and intubation A/B, C2-5 were displaced posteriorly by an average of 0.5-1.0 mm (all: P < 0.05). During removal, there was no change at C1-5. Neurological symptoms improved in all patients. We conclude that the ILM produces segmental movement of the cervical spine despite manual in-line stabilization in patients with cervical spine pathology undergoing cervical spine surgery. This motion is in the opposite direction to direct laryngoscopy, suggesting that different approaches to airway management may be more appropriate depending on the nature of the cervical instability.

IMPLICATIONS

The intubating laryngeal mask produces segmental movement of the cervical spine, despite manual in-line stabilization in patients with cervical spine pathology undergoing cervical spine surgery. This motion is in the opposite direction to direct laryngoscopy, suggesting that different approaches to airway management may be more appropriate depending on the nature of the cervical instability.