Anatomic abnormalities of the pharynx are thought to play a role in the pathogenesis of obstructive sleep apnea (OSA), but their contribution has never been conclusively proven. The present study tested this anatomic hypothesis by comparing the mechanics of the paralyzed pharynx in OSA patients and in normal subjects. According to evaluation of sleep-disordered breathing (SDB) by nocturnal oximetry, subjects were divided into three groups: normal group (n = 17), SDB-1 (n = 18), and SDB-2 (n = 22). The static pressure-area relationship of the passive pharynx was quantified under general anesthesia with complete paralysis. Age and body mass index were matched among the three groups. The site of the primary closure was the velopharynx in 49 subjects and the oropharynx in only 8 subjects. Distribution of the location of the primary closure did not differ among the groups. Closing pressure (PC) of the velopharynx for SDB-1 and SDB-2 groups (0.90 +/- 1.34 and 2.78 +/- 2.78 cmH2O, respectively) was significantly higher than that for the normal group (-3.77 +/- 3.44 cmH2O; P < 0.01). Maximal velopharyngeal area for the normal group (2.10 +/- 0.85 cm2) was significantly greater than for SDB-1 and SDB-2 groups (1.15 +/- 0.46 and 1.06 +/- 0.75 cm2, respectively). The shape of the pressure-area curve for the velopharynx differed between normal subjects and patients with SDB, being steeper in slope near Pc in patients with SDB. Multivariate analysis of mechanical parameters and oxygen desaturation index (ODI) revealed that velopharyngeal Pc was the only variable highly correlated with ODI. Velopharyngeal Pc was associated with oropharyngeal Pc, suggesting mechanical interdependence of these segments. We conclude that the passive pharynx is more narrow and collapsible in sleep-apneic patients than in matched controls and that velopharyngeal Pc is the principal correlate of the frequency of nocturnal desaturations.

Artifacts caused by metallic implants appear as dark and bright streaks at computed tomography (CT), which severely degrade the image quality and decrease the diagnostic value of the examination. When x-rays pass through a metal object, depending on its size and composition, different physical effects negatively affect the measurements in the detector, most notably the effects of photon starvation and beam hardening. To improve image quality and recover information about underlying structures, several artifact reduction methods have been introduced in modern CT systems. Projection-based metal artifact reduction (MAR) algorithms act in projection space and replace corrupted projections caused by metal with interpolation from neighboring uncorrupted projections. MAR algorithms primarily suppress artifacts that are due to photon starvation. The dual-energy CT technique is characterized by data acquisition at two different energy spectra. Dual-energy CT provides synthesized virtual monochromatic images at different photon energy (kiloelectron volt) levels, and virtual monochromatic images obtained at high kiloelectron volt levels are known to reduce the effects of beam hardening. In clinical practice, although MAR algorithms can be applied after image acquisition, the decision whether to apply dual-energy CT for the patient usually needs to be made before image acquisition. Radiologists should be more familiar with the clinical and technical features of each method and should be able to choose the optimal method according to the clinical situation. RSNA, 2018.

• Model-based iterative reconstruction (MBIR) creates high-quality low-dose CT images. • MBIR significantly improves image noise and artefacts over adaptive statistical iterative techniques. • MBIR shows greater potential than ASIR for diagnostically acceptable low-dose CT. • The prolonged processing time of MBIR may currently limit its routine use in clinical practice.

A human cholangiocellular carcinoma cell line, HuCC-T1, was established in vitro from the malignant cells of ascites of a 56-yr-old patient. Histologic findings of the primary liver tumor revealed a moderately differentiated adenocarcinoma. Tumor cells from the ascites have been cultured with RPMI 1640 medium containing 0.2% lactalbumin hydrolysate and the cultured cells grew as monolayers with a population doubling time of 74 h during exponential growth at Passage 25. They had an epithelial-like morphology and were positive for mucine staining. Ultrastructural studies revealed the presence of microvilli on the cell surface and poorly developed organelles in the cytoplasm. The HuCC-T1 cell was tumorigenic in nude mice. The number of chromosomes in HuCC-T1 ranged from 61 to 80. These human cholangiocellular carcinoma cells in serum-free medium secreted several tumor markers, including carbohydrate antigen 19/9, carbohydrate antigen 125, carcinoembryonic antigen, and tissue polypeptide antigen. The carbohydrate antigen 19/9 secretion level of HuCC-T1 cells cultured in RPMI 1640 medium with 1% fetal bovine serum was sixfold higher than that with 0.2% lactalbumin hydrolysate. These findings suggest that HuCC-T1 will provide useful information to clarify the mechanism of tumor marker secretion and tumor cell growth in the human cholangiocellular carcinoma.