Comparative assessment of CT and sonographic techniques for appendiceal imaging.

OBJECTIVE: We performed a comparative assessment of CT and sonographic techniques used to assess appendicitis. MATERIALS AND METHODS: One hundred patients with clinically suspected acute appendicitis were examined with sonography, unenhanced focused appendiceal CT, complete abdominopelvic CT using IV contrast material, focused appendiceal CT with colonic contrast material, and repeated sonography with colonic contrast material. Each sonogram was videotaped for subsequent interpretation by three radiologists and two sonographers. The mean sensitivity, specificity, positive and negative predictive values, inter- and intraobserver variability, and diagnostic confidence scores of all observers were used for comparative performance assessments. The three CT examinations were filmed and interpreted separately by four radiologists. Patient discomfort was assessed on a 10-point scale for each radiologic study. Diagnoses were confirmed by pathologic evaluation of resected appendixes or clinical follow-up for a minimum of 3 months after presentation. RESULTS: Twenty-four of the 100 patients had positive findings for acute appendicitis. Both sonographic techniques had high specificity (85-89%) and comparable accuracy (73-75%) but low sensitivity (33-35%) and inter- and intraobserver variability (kappa = 0.15-0.20 and 0.39-0.42, respectively). Unenhanced focused appendiceal CT, abdominopelvic CT, and focused appendiceal CT with colonic contrast material all significantly outperformed sonography (p <0.0001), with sensitivities of 78%, 72%, and 80%; specificities of 86%, 91%, and 87%; and accuracies of 84%, 87%, and 85%, respectively. Abdominopelvic CT gave the greatest confidence in cases with negative findings (p = 0.001), and focused appendiceal CT with colonic contrast material gave the greatest confidence for cases with positive findings (p = 0.02). In terms of inter- and intraobserver variability, focused appendiceal CT with colonic contrast material yielded the highest, and unenhanced focused appendiceal CT the lowest, agreement (interobserver kappa = 0.45 vs. 0.36 and intraobserver kappa = 0.85 vs. 0.76, respectively) (p <0.05). Colonic contrast material was unsuccessfully advanced into the cecum in 18% of patients and leaked in another 24%. Patient discomfort was greatest with focused appendiceal CT using colonic contrast material and least with unenhanced focused appendiceal CT (p <0.05). CONCLUSION: A standard abdominopelvic CT scan is recommended as the initial examination for appendicitis in adult patients. However, focused appendiceal CT with colonic contrast material material should be used as a problem-solving technique in difficult cases.

The effects of intraocular lidocaine on the corneal endothelium.

OBJECTIVE: The study aimed to evaluate the direct effect of intraocular lidocaine hydrochloride (HCl) 1% on corneal endothelial cell function, ultrastructure, and viability using an in vitro perfusion specular microscope system. DESIGN: Paired rabbit and human corneas were isolated and mounted in an in vitro specular microscope for endothelial perfusion evaluation. Corneas were perfused with a control solution (BSS Plus for humans, glutathione bicarbonate Ringer's [GBR] for rabbits) for a 1-hour stabilization period. After the stabilization period, one cornea of each matched pair was perfused with preservative-free lidocaine HCl 1% for 15 minutes followed by control solution for an additional 2 to 3 hours. The control cornea continued to receive either GBR or BSS Plus. Corneal thickness measurements were taken every 15 minutes throughout the perfusion period. Corneal swelling and deswelling rates were calculated by linear regression analysis. At the end of the experiment, corneas were fixed for scanning and transmission electron microscopy. In another group of corneas, the endothelial viability was assayed after direct perfusion with lidocaine HCl 1%. RESULTS: Lidocaine HCl 1% caused endothelial cell edema, which reversed on removal of lidocaine from perfusion media. Corneal swelling and deswelling rates did not differ significantly between the lidocaine and control groups. Electron microscopy showed the effects of transient endothelial cell edema with an otherwise normal mosaic pattern and ultrastructure for both treatment groups. Endothelial cell viability was maintained after the direct lidocaine exposure and a 2-hour washout. CONCLUSIONS: Lidocaine HCl 1% causes a transient endothelial cell edema to the in vitro perfused endothelium of human and rabbit corneas. Proper attention should be given to the type of lidocaine injected intraocularly (i.e., concentration, vehicle, preservatives, pH, osmolarity). Although lidocaine HCl 1% appears to be safe to both human and rabbit endothelium during short-term in vitro exposure, further in vivo and in vitro studies are needed to determine long-term effects of intraocular lidocaine on the corneal endothelium.

Diagnosis and differentiation of congenital diaphragmatic hernia from other noncardiac thoracic fetal masses.

This retrospective study was designed to evaluate individual sonographic parameters that might help differentiate congenital diaphragmatic hernia (CDH) from other noncardiac thoracic masses such as cystic adenomatoid malformation of the lung (CAML) and congenital lobar emphysema (CLE) prenatally. Twenty-four cases of CDH, CAML, and CLE detected during prenatal ultrasound and documented postnatally (with surgical, autopsy, or radiological proof) were identified through extensive chart and record review. The hard copy gray-scale images were retrospectively reviewed for imaging characteristics that may differentiate the three entities. Additionally, the prospective diagnosis during prenatal ultrasound was also compared with the postnatal diagnosis. The most reliable indicators in our retrospective review included confident visualization of a diaphragmatic defect (92.3/100.0 PPV/NPV, p< or =0.002) and/or localization of the stomach within the chest as well as the presence of severe cardiac deviation (both 92.3/62.5 PPV/NPV, p< or =0.01). Other sonographic indicators (including the presence of cystic areas, side and size of the lesion and the presence of polyhydramnios) offered lower levels of sensitivity and specificity. Prospective diagnosis during real-time assessment was also integral, offering >80% sensitivity and specificity (p< or =0.001). Accurate prenatal diagnosis of CDH is difficult despite the relative frequency of this lesion. The classic triad of a thoracic mass accompanying a displaced heart, absence of a normally positioned fluid-filled stomach and polyhydramnios, although seen with CDH, may not adequately differentiate this entity from other noncardiac fetal thoracic masses. Realtime assessment remains integral to the appropriate diagnosis.

Corneal endothelial permeability of human tissue after storage in Optisol.

The purpose of this study was to compare Optisol to moist chamber storage for maintaining human corneal endothelial barrier function. Human corneas preserved in Optisol were stored for up to 35 days at 4 C. Endothelial carboxyfluorescein permeability (P(ac)) was measured and endothelial ultrastructure was evaluated by electron microscopy. Endothelial P(ac) (x 10(-4) cm/min) of Optisol-stored corneas was 1.7, 2.0, and 3.1 at five, seven, and 14 days, respectively. The P(ac) increased to 6.5 at 35 days of storage. Endothelial P(ac) in moist chamber stored-eyes was 2.6 at two days, and increased to 13.5 14 days of storage. Multiple regressional analysis showed that storage time and donor age affected P(ac); but time from death to enucleation, time from enucleation to storage, or endothelial cell number did not. Electron microscopy showed that endothelial junctions were maintained through two weeks by Optisol. Large areas of cellular destruction were seen after five days of moist chamber storage. These results show that Optisol can preserve endothelial barrier function through 14 days; barrier function is lost by three days of moist chamber storage.

Swelling in the isolated perfused cornea induced by 12(R)hydroxyeicosatetraenoic acid.

PURPOSE: To evaluate the effect of 12(R)hydroxyeicosatetraenoic acid (12(R)HETE) on corneal swelling when directly perfused to human and rabbit corneal endothelium. METHOD: Excised rabbit and human corneas were mounted in the in vitro specular microscope and the endothelium was perfused with 12(R)HETE at 10(-5), 10(-6), and 10(-7) mol/l. Both 12(R)HETE and 12(S)HETE were compared at equal molar (10(-6) mol/l) concentrations. The reversal of 12(R)HETE and ouabain corneal swelling was also compared. Endothelial permeability to carboxyfluorescein was measured after 12(R)HETE perfusion. High-performance liquid chromatographic analysis confirmed that 12(R)HETE remained in the perfusion media. RESULTS: 12(R)HETE caused a dose-dependent corneal swelling of 25 +/- 2, 24 +/- 1, and 14 +/- 0.5 microns/hr at 10(-5), 10(-6), and 10(-7) mol/l, respectively. Equal molar concentrations (10(-6) mol/l) of 12(S)HETE did not cause corneal swelling. Removal of the 12(R)HETE from the perfusion media resulted in reversal of corneal swelling whereas corneal swelling induced by ouabain did not reverse after ouabain removal. 12(R)HETE (10(-6) mol/l) perfused to the human corneal endothelium inhibited temperature reversal corneal thinning when compared to the paired corneal endothelium perfused with BSS Plus (Alcon Laboratories, Inc., Fort Worth, TX). Na/K adenosine triphosphatase activity was inhibited by 10(-6) mol/l ouabain by 35%, 10(-6) mol/l 12(R)HETE by 54%, and 10(-6) mol/l 12(S)HETE by 0.5%. Endothelial permeability to carboxyfluorescein was unaffected by 12(R)HETE. CONCLUSION: 12(R)HETE causes corneal swelling by inhibiting endothelial pump function. This inhibition of transport appears to be at least partly mediated by inhibition of endothelial Na/K adenosine triphosphatase.

Corneal endothelial cytoskeletal changes in F-actin with aging, diabetes, and after cytochalasin exposure.

We investigated the changes in endothelial cytoskeletal F-actin that occur with aging, diabetes, and exposure to cytochalasin D. Rabbit corneas, human donor corneas (with or without polymegethism), and corneas of diabetic individuals were studied. Endothelial F-actin was stained using nitrobenzoxadiazole-phallacidin. Results of these experiments demonstrated that F-actin of the rabbit and human corneal endothelium was arranged in linear circumferential strands that formed a hexagonal array. After in vitro perfusion of cytochalasin D to the corneal endothelium, the F-actin became randomly distributed throughout the cytoplasm, the hexagonal shape of the endothelial cell was disrupted, and endothelial permeability to carboxyfluorescein increased. Changes in F-actin were also observed in the endothelium of the human corneas with polymegethism, and in donor tissue having had previous posterior chamber intraocular lens implantation. The corneas of diabetic individuals also showed marked irregular F-actin fibers crossing the endothelial cell cytoplasm. These abnormal patterns of F-actin may contribute in part to the polymegethism observed in the corneal endothelial cells and may be the result of constant stress in cell volume regulation, particularly in the corneas of diabetic individuals.