Evaluation of postprocessing dual-energy methods in quantitative computed tomography. Part 2. Practical aspects.

Three facets of dual-energy quantitative computed tomography are studied: (1) the algorithm for postprocessing data (the methods of Cann, Laval-Jeantet et al, Goodsitt et al [two methods], and Nickoloff et al); (2) the influence of choice of tissue-equivalent materials for calibration; and (3) the difference between central and peripheral calibration. The different tissue-equivalent materials include bone mineral-equivalent (K2HPO4 solutions and calcium hydroxyapatite), fat-equivalent (liquid paraffin, polyethylene, and 70% ethanol solution), and red marrow-equivalent (plastic). Deviation from the manufacturer's quoted content is least with central positioning of the calibration materials.

Evaluation of postprocessing dual-energy methods in quantitative computed tomography. Part 1. Theoretical considerations.

Five postprocessing methods for dual-energy quantitative computed tomography of the vertebral body were evaluated theoretically. The methods were compared by transforming the original sets of equations to a standard set. Only two of these methods produced optimal results, namely the basic approach of Goodsitt et al and the method of Nickoloff et al.

Correlation of migration behavior in free-flow zone electrophoresis and electrophoretic titration curve.

The correlation of electrophoretic migration behavior in free-flow zone electrophoresis (FFZE) and electrophoretic titration curve (ETC) has been explored. It is shown that the ETC of a protein or a mixture of proteins can be used to predict the fraction numbers at which those proteins elute in a preparative scale FFZE experiment. The ETC is a quick and effective way to choose optimal buffer conditions in FFZE.

Relations between depressed mood and vocal parameters before, during and after sleep deprivation: a circadian rhythm study.

The mechanism underlying improvement after total sleep deprivation (TSD) was studied in 14 major depressed patients. The suggestions that (1) circadian processes and/or (2) dimensions of arousal may play a role in the response to TSD were investigated. Diurnal variation of depressed mood and of mood- and arousal-related vocal parameters was studied in relation to the effect of TSD on depressed mood and vocal parameters.

Pseudomalignant, nonneoplastic osseous soft-tissue tumors of the hand and foot.

Seventeen patients with nonneoplastic osseous tumors in the soft tissues of the hands and feet were retrospectively studied. Three of the patients had a reliable history of trauma. Ten patients showed periosteal reaction associated with gradual formation of an osseous soft-tissue tumor, sometimes with a peripheral zone of bone density.

Benign soft-tissue neoplasm simulating sarcoma of spermatic cord.

A large, painless, slow-growing mass arising in the scrotum of a twenty-three-year-old man, which proved to be benign myxoma, simulated a primary sarcoma of the spermatic cord. Only 1 case of myxoma involving the spermatic cord has been reported previously. It is extremely important that multiple microscopic sections of the specimen be examined carefully so that the proper tissue diagnosis can be made.

Auxiliary partial liver transplantation: imaging evaluation in 10 patients.

Auxiliary partial liver transplantation involves placement of a heterotopic graft in the subhepatic space, with the liver of the recipient left unaltered. We studied the values of three imaging procedures (Doppler sonography, diisopropyl iminodiacetic acid [DISIDA] scintigraphy, and cholangiography) to evaluate the transplant and the native liver after surgery in 10 patients. Special attention was paid to the Doppler waveform of the hepatic artery of the graft and to the resistive index.

[Early complications of caustic injuries of the digestive tract].

We retrospectively analyzed the gastrointestinal complications observed in 119 patients who had ingested corrosive agents. Hydrochloric acid and sodium hydroxide were the agents involved in 62% of patients. Women predominated over men (p less than 0.

Indications and results of choledochoduodenostomy in benign biliary tract diseases.

During a 12-year period ending December 1987, 17,200 operations for biliary tract disease were performed at the Dept. of Surgery of the University of Chile. Choledochoduodenostomy was performed in 140 of these patients operated upon for benign biliary tract and/or gallbladder diseases.

Indications and results of sphincteroplasty in benign biliary diseases.

A retrospective analysis of 143 patients submitted to sphincteroplasty at the Department of Surgery, University of Chile Clinical Hospital was performed. A significant percentage of these patients (90%) were admitted due to acute biliary tract disease with or without cholangitis. The standard operative procedure was anterior transduodenal sphincteroplasty with supraduodenal choledochal exploration leaving a choledochostomy.

Results of surgical treatment in patients with "western" intrahepatic lithiasis.

The results of the surgical treatment in 251 patients with intrahepatic stones are discussed. The mean age of the group was 48 years, with a predominance of females. Gallstones were observed in 72% of the cases, because 28% had had previous cholecystectomy.

Treatment of residual common bile duct stones after cholecystectomy.

This study was conducted to determine the occurrence of "open" residual common bile duct stones after cholecystectomy to establish predisposing factors and possible alternative treatments. Correct diagnosis of choledocholithiasis before or during surgery, adequate exploration of the common bile duct, and suitable selection of technical procedures are the most important points in preventing retained CBD stones. If these occur, an adequate alternative treatment may prove helpful.

[Results of the treatment of pyogenic hepatic abscess over a 10-year period].

The experience of the Hospital Clínico de la Universidad de Chile in the treatment of pyogenic liver abscess, during various periods of the last decade is presented. Fifty six cases treated by means of three therapeutic options are reviewed retrospectively. The overall mortality during period was of 27% and it decreased to 19% if only the last three years were taken into account.

New surgical techniques for voice improvement.

Laryngeal framework surgery for improving or changing the voice is a challenging development in phoniatric surgery. Basically two categories can be distinguished: (1) attempted medialization of the vocal fold, as for the treatment of paralytic dysphonias (arytenoid rotation technique and Isshiki's type I thyroplasty); (2) adjustment of the vocal fold's tension to produce changes in vocal pitch, as for the treatment of transsexuals or mutational dysphonia (cricothyroid approximation, Isshiki's type III thyroplasty and LeJeune's anterior commissure laryngoplasty). Both types of surgery are best performed with the patient under local anesthesia so that fine tuning of the voice is possible by monitoring the voice during the surgical procedure.

Value of proximal diversion and ureteral stenting in management of penetrating ureteral trauma.

Cases of penetrating ureteral trauma (17 gunshot wounds and 4 stab wounds) seen at two New York City hospitals over a nine-year period were reviewed. Early urologic complications (defined as urine drainage from the wound for greater than 2 weeks or need for a second operation) occurred in 50 percent of patients with a proximal ureteral injury but were less common when a nephrostomy and stent were used in the repair. A similar beneficial effect of stenting was seen in published cases, with a 91 percent complication rate for unstented repairs and a 15 percent rate when stenting and nephrostomy drainage were both used.

Comparison of induction and repair of adducts and of alkali-labile sites in human lymphocytes and granulocytes after exposure to ethylating agents.

A comparative study has been made of the induction and repair of adducts and alkali-labile sites in the DNA of human lymphocytes and granulocytes exposed to the ethylating agents N-ethyl-N-nitrosourea (ENU) and diethyl sulphate (DES). To evaluate these damages, the human blood cells were treated with highly 3H-labelled ENU and DES, and the resulting 3H-ethyl adducts were analysed via HPLC. Alkali-labile sites introduced in the DNA during treatment with non-radioactive ENU and DES were detected by alkaline elution with fluorometric quantitation of the DNA in the eluted fractions.

Common bile duct pressure in patients with common bile duct stones with or without acute suppurative cholangitis.

Resting common bile duct pressure was measured in three groups of patients: group 1, 53 patients with gallstones but without common duct stones; group 2, 35 patients with common bile duct stones unaccompanied by cholangitis; and group 3, 36 patients with common duct stones and acute suppurative cholangitis. A significantly higher pressure in the common bile duct was documented in patients with cholangitis when compared with the other two groups. Twenty-four patients with cholangitis had common duct pressure values above 20 cm H2O, the maximal values of normal.

Enzymatic determination of L-phenylalanine and phenylpyruvate with L-phenylalanine dehydrogenase.

An enzymatic method is described for the determination of L-phenylalanine or phenylpyruvate using L-phenylalanine dehydrogenase. The enzyme catalyzes the NAD-dependent oxidative deamination of L-phenylalanine or the reductive amination of the 2-oxoacid, respectively. The stoichiometric coupling of the coenzyme allows a direct spectrophotometric assay of the substrate concentration.

The inferiorly based pharyngoplasty: effects on chronic otitis media with effusion.

Conflicting reports in the literature on the relationship between the inferiorly based pharyngeal flap and otitis media with effusion (OME) motivated a prospective study on 51 children between 3 and 12 years of age suffering from velopharyngeal incompetence. The patient group consisted of 34 children with cleft palate and 17 children with congenitally short palate. The male-female ratio was 37 to 14, showing no differences regarding physical disability.

Bladder neck obstruction secondary to Brunn's cyst.

A large solitary Brunn's cyst caused a ball-valve type of obstruction of the bladder neck in a 29-year-old man without endoscopic or histological evidence of bladder inflammation. Unroofing and drainage restored normal voiding. The histopathological features of Brunn's nests are reviewed.