Metallic artifacts caused by dental metal prostheses on PET images: a PET/CT phantom study using different PET/CT scanners

Objective  The objective of this study was to investigate the effects of computed tomography (CT) artifacts caused by dental metal prostheses on positron emission tomography (PET) images. Methods  A dental arch cast was fixed in a cylindrical water-bath phantom. A spherical phantom positioned in the vicinity of the dental arch cast was used to simulate a tumor. To simulate the tumor imaging, the ratio of the ¹⁸F-fluoro-deoxy-glucose radioactivity concentration of the spherical phantom to that of the water-bath phantom was set at 2.5. A dental bridge composed of a gold–silver–palladium alloy on the right mandibular side was prepared. A spherical phantom was set in the white artifact area on the CT images (site A), in a slightly remote area from the white artifact (site B), and in a black artifact area (site C). A PET/CT scan was performed with and without the metal bridge at each simulated tumor site, and the artifactual influence was evaluated on the axial attenuation-corrected (AC) PET images, in which the simulated tumor produced the strongest accumulation. Measurements were performed using three types of PET/CT scanners (scanners 1 and 2 with CT-based attenuation correction, and 3 with Cesium-137 (¹³⁷Cs)-based attenuation correction). The influence of the metal bridge was evaluated using the change rate of the SUVmean with and without the metal bridge. Results  At site A, an overestimation was shown (scanner 1: +5.0% and scanner 2: +2.5%), while scanner 3 showed an underestimation of −31.8%. At site B, an overestimation was shown (scanner 1: +2.1% and scanner 2: +2.0%), while scanner 3 showed an underestimation of −2.6%. However, at site C, an underestimation was shown (scanner 1: −25.0%, scanner 2: −32.4%, and scanner 3: −8.4%). Conclusions  When CT is used for attenuation correction in patients with dental metal prostheses, an underestimation of radioactivity of accumulated tracer is anticipated in the dark streak artifact area on the CT images. In this study, the dark streak artifacts of the CT caused by metallic dental prostheses may cause false negative finding of PET/CT in detecting small and/or low uptake tumor in the oral cavity.     

Roles of alcohol drinking pattern in fatty liver in Japanese women

Purpose

Several studies have reported an inverse association between moderate alcohol consumption and prevalence of fatty liver (FL) in men. We aimed to clarify this association in women.

Methods

We collected health checkup data from 4,921 Japanese women without concurrent liver disease (mean age 46.4 years) and performed a cross-sectional study to evaluate the influence of alcohol drinking patterns (frequency and amount) on the prevalence of FL as assessed by ultrasonography.

Results

Alcohol consumption was reported in 30.8 % of participants, and FL was observed in 13.8 % (15.5 % nondrinkers, 10.1 % drinkers). Alcohol consumption was inversely associated with FL prevalence [adjusted odds ratio (AOR) 0.79, 95 % confidence interval (CI) 0.63–0.98]. In analyses stratified by drinking frequency and/or amount of alcohol consumed, the risk of FL decreased for the following categories: 0.1–19.9 g/drinking day (AOR 0.61, 95 % CI 0.44–0.83) and 0.1–69.9 g/week (AOR 0.74, 95 % CI 0.55–0.98). The amount of alcohol consumed directly correlated with the prevalence of FL in daily drinkers (p < 0.05), whereas there was no correlation between the frequency of alcohol consumption and FL prevalence. Alanine aminotransferase levels were significantly lower for the following categories: 0.1–19.9 g/drinking day for 1–3 days a week (p = 0.016) and 0.1–69.9 g within 1–3 drinking days a week (p = 0.004).

Conclusions

Minimal alcohol consumption appears to have protective effects against nonalcoholic FL disease in women, although an increase in the amount of alcohol consumed appears to nullify the protective effect.     

Radiographic features of a patient with both cemento-ossifying fibroma and keratocystic odontogenic tumor in the mandible: a case report and review of literature

We herein describe a rare case of a 48-year-old woman with both ossifying fibroma (OF) and keratocystic odontogenic tumor (KCOT) in the mandible. CT images showed a 15 × 15 × 20-mm radiolucent-radiopaque lesion with bucco-lingual bony expansion in the left first premolar equivalent area of the mandible, and a 15 × 40 × 35-mm well-defined unilocular radiolucent lesion in the left side of the mandible, extending from the distal side of the distal root of the left second molar to the left mandibular ramus. A biopsy of the radiolucent-radiopaque lesion and fenestration surgery of the radiolucent lesion were performed. Histopathologic examination revealed a fibro-osseous lesion (FOL) and a KCOT, respectively. CT was useful in diagnosing the radiolucent-radiopaque lesion as OF and for detecting the 3-dimensional bone expansion and the contents in the lumen of the KCOT.     

Dose reduction trial from 60 Gy in 10 fractions to 54 Gy in 9 fractions schedule in high-dose-rate interstitial brachytherapy for early oral tongue cancer

To compare the effects of 60 Gy/10 fractions (twice a day) with those of 54 Gy/9 fractions in high-dose-rate interstitial brachytherapy (HDR-ISBT) for early tongue cancer, we performed a matched-pair analysis of patients with early tongue cancer (T1-2N0M0), who were treated with 60 or 54 Gy of radiation between 1996 and 2004. Seventeen patients treated with 54 Gy and 34 matched-pair patients treated with 60 Gy were extracted and analyzed. Local recurrence occurred in two patients in the 54-Gy arm and five patients in the 60-Gy arm. The 2-year local control rates were 88% for both the 54-Gy arm and 60-Gy arm (not significant). The 2-year overall survival rates were 88% in the 60-Gy arm and 82% in the 54-Gy arm. Two-year actuarial complication-free rates were 91% in the 60-Gy arm and 83% in the 54-Gy arm (not significant), respectively. There was no significant association between the total dose and local control rate and late complications. The outcome of 54 Gy/ 9 fractions was similar to that of 60 Gy/ 10 fractions in patients with early tongue cancer.     

Clockwise and Counter-Clockwise Circulation of Wavefronts around an Anatomical Obstacle as One Mechanism of Two Morphologies of Sustained Ventricular Tachycardia in Patients after a Corrective Operation of Tetralogy of Fallot

Two different monomorphic VTs were observed in two patients after a corrective operation for tetralogy of Fallot. The activation pattern of the wavefronts of the two VTs were different: in a counter-clockwise direction around the anatomical obstacle due to a ventriculotomy of the right ventricle in one VT; and in a clockwise direction around the same obstacle in the other VT. The different revolutions of the wavefronts could be the mechanism for the different morphologies of VT.     

Further studies on the resolution of human mercapt- and nonmercaptalbumin and on human serum albumin in the elderly by high-performance liquid chromatography

High-performance liquid chromatographic (HPLC) analysis of human serum albumin (HSA) on Asahipak GS-520 showed at least two peaks, the principal component corresponding to human mercaptalbumin (HMA) and the secondary one to nonmercaptalbumin (HNA). HPLC analysis of HSA on Asahipak ES-520 N showed three peaks, the principal component corresponding to HMA, the secondary one to HNA having mixed disulfide with cysteine or glutathione and the tertiary one to HNA oxidized higher than mixed disulfide. Two kinds of rapid HPLC for the resolution of HSA into HMA and HNA were developed by the present authors. Using these HPLC, the present authors found a significant decrease in the fraction of HMA in the elderly.     

Interpretation of dissolution rate data from in vitro testing of compressed tablets

To find if theoretically and experimentally a relation existed between the dissolution rate theory of Kitazawa, Johno & others (1975) and that of Wagner (1969), a study was undertaken with uncoated caffeine, aspirin and proxyphylline tablets using two dissolution methods. Although the original treatment for surface area of drug available for dissolution was quite different between the two dissolution theories, the dissolution rate constants obtained were in fair agreement. Hence it might not be always necessary to take into consideration changes in the surface area as a function of dissolution rate, and the 1n W^∞/ (W^∞ - W) versus time plot devised by Kitazawa & others might be a useful and simple means of obtaining the dissolution rate constant of an active ingredient from a dosage form such as compressed tablet.     

Development of a new mouse palate organ culture system and effect of X-irradiation on palatogenesis

On the basis of an already established suspension system of organ culture for mouse palate explants, we developed a new culture system, which has several advantages over the previous methods. We used a 48-well culture plate in which the explants can be cultured indivisually, and only 300 μ 1 of medium is needed for each well. In order to optimize the culture results, we systematically studied the influence of main “culture conditions” such as tilt degree of the culturing palate, rotation speed, and addition of ascorbic acid to the medium. This system allows culturing of palates from day 13.5 of gestation to day 16.5 under serum-free conditions using a chemically defined medium, which resulted in 78% of the palates growing fused. Utilizing this culture system, the direct effect of X-irradiation on palataogesis was analyzed. A 4 Gy dose of X-irradiation was administrated at the beginning of culture period. The incidence of palatal fusion was not significantly different from that of the non-irradiated group.