Terms Of Cross-sectional Area Research Articles

Multimodal ultrasound evaluation of asymptomatic ulnar nerve dislocation at the cubital tunnel.

Ultrasonography has received broad acceptance as an effective peripheral nervous imaging examination. Shear wave elastography (SWE) can quantitatively assess the stiffness of nerves; however, little research has been conducted on elastography for ulnar nerve dislocation. The purpose of this study was thus to investigate the characteristics of multimodal ultrasound, including high-resolution ultrasonography and SWE, for asymptomatic ulnar nerve dislocation at cubital tunnel. In this prospective cross-sectional study, 41 participants were recruited in Shandong Provincial Hospital Affiliated to Shandong First Medical University in July 2022. The inclusion criteria for participants were being in good health and being 18-60 years of age. Meanwhile, the exclusion criterion was a history of upper limb pain or fractures, peripheral neuropathy, or systemic or immunological diseases. Finally, 38 participants were enrolled. Two ultrasound doctors measured the maximum diameter, the maximum cross-sectional area (CSA), and the shear modulus of the ulnar nerve at the cubital tunnel independently. Another two ultrasound doctors determined whether dislocation was present during dynamic elbow flexion and extension and divided the elbows into a dislocation group and a control group. The descriptive statistics and independent sample t-test were used for data analysis, and intragroup correlation coefficient (ICC) was used to determine the consistency of evaluation between observers. Ulnar nerve dislocation was observed in 15.8% (12/76) of the ulnar nerves. There was no significant difference in the maximum diameter between the dislocation group (0.194±0.022 cm) and the control group (0.181±0.023 cm) (t=1.888; P=0.063). The CSA and SWE of the ulnar nerve were 0.064±0.009 cm2 and 43.629±6.737 kPa in the dislocation group, respectively, and were 0.050±0.008 cm2 and 31.293±7.858 kPa in the control group, respectively. There were significant differences between the two groups in terms of CSA (P<0.001) and SWE (P<0.001). The ICCs of the maximum diameter, CSA, and SWE values between observers were 0.970, 0.900, and 0.915, respectively. Multimodal ultrasound consisting of high-resolution ultrasonography combined with elastography can comprehensively and quantitatively evaluate the morphological changes and mechanical properties of the dislocated ulnar nerve and monitor disease progress.

Importance of paravertebral muscle quality in the etiology of degenerative lumbar spinal stenosis

Objectives: Degenerative lumbar spinal stenosis (DLSS) is the leading cause of pain, disability, and loss of independence in older adults. In this study, the relationship between DLSS and paravertebral muscle thickness and density was investigated using computed tomography (CT) and magnetic resonance imaging (MRI) methods. Thus, the importance of muscles has been examined to take precautions in the name of preventive medicine. Methods: This study was planned as a cross-sectional study. The patient group (n = 77) who had surgery for DLSS and the control group (n = 77) were examined. A total of 154 participants (55 females and 22 males in each group) were evaluated retrospectively in terms of cross-sectional area (CSA) and density in the psoas, erector spina and multifidus muscles. In both groups age, gender and body mass index values equalized. Measurements was averaged from the mid-lumbar 3 level from both sides and multi-points. Results: There was no significant difference between muscle thicknesses (p &amp;gt; 0.05). When evaluated in terms of muscle densities, a significant difference was found between the patient and the control group in terms of psoas muscle (p &amp;lt; 0.05). Likewise, there is the same relationship between erector spinae muscle density and multifidus muscle density (p &amp;lt; 0.05). Conclusions: Roughly no difference was found between the patient and control groups in terms of CSA of the psoas, erector spinae and multifidus muscles, but it was observed that the muscle density, especially in the multifidus, decreased significantly in the patients. Our results suggest that paravertebral muscle density assessment is an important criterion in disease prediction and can inform preventive treatment.

Comparison of Ultrasound-Guided Steroid and Platelet-Rich Plasma (PRP) Injection in Patients with Carpal Tunnel Syndrome

Objective: Imaging-guided injection treatments can yield effective results in patients with mild-to-moderate carpal tunnel syndrome (CTS) resistant to conservative methods. Methods: Patients who presented with typical median nerve entrapment findings for at least 3 months, were diagnosed with mild-moderate CTS electrophysiologically, and underwent ultrasound-guided steroid and PRP injection were included in the study. Visual analog scale (VAS) scores, Boston Carpal Tunnel Questionnaire (Functional status scale (FSS) and Symptom severity scale (SSS) parameters) scores were recorded in the pre-procedure, 1st month and 6th month controls of the patients. Sonographically, median nerve cross-sectional area (CSA) measurements were recorded at pre-procedure and post-procedure 1st and 6th month controls. Results: In 27 patients (21 women, 6 men), 40 median nerve injections (9 patients right, 5 patients left, 13 patients bilateral) were evaluated. In all patients, CSA, VAS, FSS, and SSS scores were significantly lower at 1 month and 6 months after the procedure than before the procedure. (p=0.000, p=0.000, p=0.000, P=0.000, respectively). While the VAS scores were found to be significantly lower in the steroid group than in the PRP group at 1 month (p=0.04), there was no significant difference between the two groups in terms of CSA, FSS, and SSS scores (p=0.1, p=0.5, p=0.8, respectively). At 6 months, CSA, VAS, FSS, and SSS scores were significantly lower in the PRP group compared to the steroid group (p=0.000, p=0.000, p=0.000, p=0.000 respectively). Conclusion: In mild-to-moderate carpal tunnel syndrome, steroid injections applied under ultrasonography guidance of the median nerve are effective for a short time, and PRP injections are a superior and safe option to steroids for long-term efficacy.

ZnO nanoparticles coated with oleic acid as additives for a polyalphaolefin lubricant

In this work, ZnO nanoparticles (NPs) were successfully synthesized and coated with oleic acid (OA). The mean diameter of these NPs (ZnO-OA) was around 11.5 nm, their core was characterized by XRD and their coating by FTIR and Raman. Homogeneous dispersions at different concentrations (0.10, 0.25, 0.50, 0.75 and 1.00 wt%) of ZnO-OA in polyalphaolefin 40 (PAO40) oil were thermophysically and tribologically characterized. Both density and viscosity values increased with the concentration of NPs, reaching relative increments of 0.5% and 4.0%, respectively, for the 1 wt% nanodispersion. Tribological tests were performed at 353.15 K using an Anton Paar MCR 302 rheometer equipped with a tribological ball-on three-pins configuration testing module. Regarding the tribological behavior, the optimal concentration was 0.25 wt% of ZnO-OA (25% of reduction in the friction coefficient and 82% wear reduction in terms of cross sectional area, respect to those obtained with the neat base oil). The rolling mechanism owing to the spherical shape of the nanoadditives, transforming sliding friction into rolling friction, and the mending effect could explain the better tribological performance of nanolubricants with respect to that of neat PAO40. In addition, the presence of PAO40, ZnO-OA NPs and iron oxides was evidenced from confocal Raman microscopy on the worn surfaces obtained from tribological test with PAO40 + 0.25 wt% ZnO-OA dispersion.

Use of NRCS-curve number method for peak discharge estimation in Sharqu ElNeil locality, Khartoum, Sudan

Predicting the amount of surface runoff reaching crossing point of a watershed stream with a highway is critical for accurate design of safe hydraulic structures and flood protection. Sharqu ElNeil locality of Khartoum, Sudan, has been subject to repeated flash floods amplified by the presence of Alilafon Street, which runs in the NW-SE direction forming a terrace obstructing the natural flow of seasonal streams towards the Blue Nile River plain. Existing structures (culverts) are unable to pass stream water. They were either insufficient in terms of cross sectional area, ill-designed, or were displaced due to unplanned urbanization. Therefore, the (SCS)-curve number (CN) method developed by US Soil Conservation Service was used combined with geographical information systems (GIS) in order to estimate peak discharge reaching stream crossing points and to re-evaluate existing hydraulic structures. From hydrological modeling and field survey, eight catchments and crossing points were identified. Catchment area ranged between 13.4 and 42.1 km2 while the CN value ranged between 80 and 90. Rainfall intensity was obtained from frequency analysis of 100-year rainfall data. It has ranged between 5.5 and 65 mm/h for the 10-year return period. Computed peak discharge values ranged between 15.6 and 47.2 m3/s. Hydraulic structures were designed for each crossing point based on Manning formula. One new culvert and amendments for five existing structures were proposed.

Multifidus muscle size in adolescents with and without back pain using ultrasonography

ObjectiveThe purposes of this study were; a) to compare multifidus muscle cross sectional area (CSA) in male adolescents suffering from low back pain (LBP) with healthy male adolescents using ultrasonography (US), and b) to assess the correlation between multifidus muscle size and demographic variables. MethodsA random sample of 40 healthy boys (as a control group) and 40 boys with LBP (as an experimental group) at the age range of 15–18 years was recruited in the present cohort study. Multifidus muscle dimensions including CSA, antero-posterior and medio-lateral dimensions were measured at level of L5 in both groups using US. ResultsThe results of an independent t-test to compare multifidus muscle size between the experimental and control groups showed a significant difference between the two groups in terms of CSA, antro-posterior and medio-lateral dimensions so that the experimental group had smaller muscle size than the control group. A significant correlation was found between height, weight and body mass index (BMI) and multifidus muscle size, but no significant correlation was observed between age and muscle size. Pain intensity and functional disability index was significantly correlated with muscle size in the experimental group. ConclusionsAccording to the results, multifidus muscle size was decreased in 15–18 years old male adolescents suffering from LBP compared with their healthy counterparts. Further studies are needed to support the findings of the present study.

Morphological classification and comparison of suboccipital muscle fiber characteristics.

In an attempt to clarify the function of the suboccipital muscles, we performed morphological observation of the suboccipital muscles for variations in the muscle belly and compared the morphology of their muscle fibers in terms of cross-sectional area by immunostaining with anti-myosin heavy chain antibodies. The cadavers of 25 Japanese individuals were used: 22 for morphological examinations and three for histological examinations. Among samples of the rectus capitis posterior major muscle (RCPma) and rectus capitis posterior minor muscle (RCPmi), 86.4% had a typical muscle appearance with a single belly, and 13.6% had an anomalous morphology. None of the samples of the obliquus capitis superior (OCS) or obliquus capitis inferior (OCI) muscles had an anomalous appearance. Measurement of cross-sectional area revealed that fast-twitch muscle fibers in the RCPma and OCI had a significantly greater cross-sectional area than those of the RCPmi and OCS. The cross-sectional area of intermediate muscle fibers was also significantly greater in the OCS than in the RCPma, RCPmi, and OCI. The cross-sectional area of slow-twitch muscle fibers was significantly greater in the OCS than in the RCPma, RCPmi, and OCI, and the RCPmi showed a significantly greater cross-sectional area for slow-twitch muscle fibers than did the RCPma, and OCI. Our findings indicate that the RCPmi and OCS exert a greater force than the RCPma and OCI, and act as anti-gravity agonist muscles of the head. Prolonged head extension in individuals with anomalous suboccipital muscle groups could result in dysfunction due to undue stress.

Mitochondrial Ultrastructure and Glucose Signaling Pathways Attributed to the Kv1.3 Ion Channel.

Gene-targeted deletion of the potassium channel Kv1.3 (Kv1.3−∕−) results in “Super-smeller” mice with a sensory phenotype that includes an increased olfactory ability linked to changes in olfactory circuitry, increased abundance of olfactory cilia, and increased expression of odorant receptors and the G-protein, Golf. Kv1.3−∕− mice also have a metabolic phenotype including lower body weight and decreased adiposity, increased total energy expenditure (TEE), increased locomotor activity, and resistance to both diet- and genetic-induced obesity. We explored two cellular aspects to elucidate the mechanism by which loss of Kv1.3 channel in the olfactory bulb (OB) may enhance glucose utilization and metabolic rate. First, using in situ hybridization we find that Kv1.3 and the insulin-dependent glucose transporter type 4 (GLUT4) are co-localized to the mitral cell layer of the OB. Disruption of Kv1.3 conduction via construction of a pore mutation (W386F Kv1.3) was sufficient to independently translocate GLUT4 to the plasma membrane in HEK 293 cells. Because olfactory sensory perception and the maintenance of action potential (AP) firing frequency by mitral cells of the OB is highly energy demanding and Kv1.3 is also expressed in mitochondria, we next explored the structure of this organelle in mitral cells. We challenged wildtype (WT) and Kv1.3−∕− male mice with a moderately high-fat diet (MHF, 31.8 % kcal fat) for 4 months and then examined OB ultrastructure using transmission electron microscopy. In WT mice, mitochondria were significantly enlarged following diet-induced obesity (DIO) and there were fewer mitochondria, likely due to mitophagy. Interestingly, mitochondria were significantly smaller in Kv1.3−∕− mice compared with that of WT mice. Similar to their metabolic resistance to DIO, the Kv1.3−∕− mice had unchanged mitochondria in terms of cross sectional area and abundance following a challenge with modified diet. We are very interested to understand how targeted disruption of the Kv1.3 channel in the OB can modify TEE. Our study demonstrates that Kv1.3 regulates mitochondrial structure and alters glucose utilization; two important metabolic changes that could drive whole system changes in metabolism initiated at the OB.

Weight optimal design of lateral wing upper covers made of composite materials

The present investigation is devoted to the development of a new optimal design of lateral wing upper covers made of advanced composite materials, with special emphasis on closer conformity of the developed finite element analysis and operational requirements for aircraft wing panels. In the first stage, 24 weight optimization problems based on linear buckling analysis were solved for the laminated composite panels with three types of stiffener, two stiffener pitches and four load levels, taking into account manufacturing, reparability and damage tolerance requirements. In the second stage, a composite panel with the best weight/design performance from the previous study was verified by nonlinear buckling analysis and optimization to investigate the effect of shear and fuel pressure on the performance of stiffened panels, and their behaviour under skin post-buckling. Three rib-bay laminated composite panels with T-, I- and HAT-stiffeners were modelled with ANSYS, NASTRAN and ABAQUS finite element codes to study their buckling behaviour as a function of skin and stiffener lay-ups, stiffener height, stiffener top and root width. Owing to the large dimension of numerical problems to be solved, an optimization methodology was developed employing the method of experimental design and response surface technique. Optimal results obtained in terms of cross-sectional areas were verified successfully using ANSYS and ABAQUS shared-node models and a NASTRAN rigid-linked model, and were used later to estimate the weight of the Advanced Low Cost Aircraft Structures (ALCAS) lateral wing upper cover.

Residents' journal review

Residents' journal review

A New Class of Damage Variables in Continuum Damage Mechanics

In this work various new proposed damage variables are introduced, examined and compared. Only the scalar case pertaining to isotropic damage is investigated here. Several types of new damage variables are proposed as follows: (1) damage variables that are defined in terms of cross-sectional area, (2) damage variables that are defined in terms of the elastic modulus or stiffness, and (3) composite damage variables that are defined in terms of two parameters relating to both cross-sectional area and stiffness. However, the generalization to tensors and general states of deformation and damage may be a straightforward process but is beyond the scope of this work. The damage variables introduced in this work can be applied to elastic materials including homogeneous materials like metals and heterogeneous materials like composite laminates. In the second part of this work, higher-order strain energy forms are proposed. It is seen that a specific nonlinear stress-strain relationship is associated with each higher-order strain energy form. These higher order strain energy forms along with some of the proposed damage variables are used in trying to lay the theoretical groundwork for the design of undamageable materials, i.e., materials that cannot be damaged where the value of the damage variable remains zero throughout the deformation process.

Effect of Connector Design on Fracture Resistance of Zirconia All-ceramic Fixed Partial Dentures

The purpose of the present study was to determine the relationship between cross-sectional design and fracture load using a static load bearing test in yttria-stabilized tetragonal zirconia polycrystal ceramic frameworks on a molar fixed partial denture. The test framework was designed as a 3-unit bridge with two abutment teeth at the second premolar and second molar of the mandible. The cross-sectional area of the connector was 9.0, 7.0, or 5.0mm(2). In terms of shape, the cross-section was either circular or oval, with a height/width ratio of 1:1, 3:4, or 2:3. For each of the 9 combinations of cross-sectional area and shape, 5 frameworks were prepared (45 in total). Frameworks were cemented to a metallic test model with adhesive resin cement. After fracture load was measured, the percentage of fracture sites was determined and the fracture surfaces observed. In terms of cross-sectional area, there was a statistically significant difference in fracture load between 9.0, 7.0, and 5.0mm(2). No significant difference in fracture load was observed between any two shapes of connector (p>0.05). The fracture load of all frameworks with a cross-sectional area of 9.0 or 7.0mm(2) was over 880 N, which was recognized as parafunctional occlusal force. Fracture occurred at the distal connector in 82.2% of all frameworks on average. Fracture load decreased as cross-sectional area of the connector became smaller. The cross-sectional shape used in the present study was less influential on fracture load. It appears to be clinical possible to apply a connector with a cross-sectional area of 7.0mm(2). Fracture often occurred at the distal connector between the pontic and the abutment, corresponding to the second molar.

Comparison of two approaches to internal jugular vein cannulation in young children: ultrasonographic evaluation.

Percutaneous cannulation of internal jugular vein is difficult in pediatric patients because of its small size and anatomic variation. The aim of this study is to investigate cross-sectional area and relative anatomy of right internal jugular vein with respect to the carotid artery in two approaches and thereby to find ideal cannulation site in young children. The cross-sectional area of right internal jugular vein and the degree of the carotid artery overlap was evaluated in 47 children using ultrasound at two levels; 1) at the cricoid cartilage (high approach) and 2) at the junction of the two heads of the sternocleidomastoid muscle (low approach). The cross-sectional area was significantly larger by about 28.8% in the low approach than that of the high approach (P < 0.01). The internal jugular vein was partially overlapping the carotid artery in 48.9% and completely overlapping in 42.6% in the low approach and in 44.7% and 34.0% in the high approach respectively. The carotid artery overlap was significantly higher in the low approach when compared with the high approach (P < 0.02). In terms of cross-sectional area, the low approach with larger size is optimal for internal jugular vein cannulation. Although the degree of the carotid artery overlap was higher at the low approach, the internal jugular vein was partially or completely covering the carotid artery in most patients in both approaches. When attempting to cannulate the internal jugular vein, clinicians should be aware of the large anatomic variations.

Diagnostic Precision of Ultrasonography in Patients with Carpal Tunnel Syndrome

To evaluate the diagnostic value of ultrasonography in patients with electrophysiologically confirmed carpal tunnel syndrome. A prospective ultrasonographic study of 35 wrists with electrophysiologically confirmed carpal tunnel syndrome and of 40 normal wrists. Receiver-operating-characteristics curves for the ultrasonographic measurements of median nerve were plotted to identify the most optimal cutoff values. The ultrasonographic measurements of median nerves were found to be increased significantly in patients with carpal tunnel syndrome when compared with controls, particularly in terms of cross-sectional area (P<0.001) and the bowing of the flexor retinaculum (P<0.01) but not in the flattening ratio (P>0.05). According to receiver-operating-characteristics curve results, the most optimal cutoff value for the cross-sectional area of the median nerve was obtained at the level of middle carpal tunnel, which was 9.3 mm, with a sensitivity of 80% and specificity of 77.5%. The optimal cutoff value for the bowing of the flexor retinaculum was 3.7 mm, with a sensitivity of 71.4% and specificity of 55%. No optimum cutoff value could be identified from the receiver-operating-characteristics curves for the flattening ratio of median nerve. Ultrasonographic examination of the median nerve seems to be a promising method in the diagnosis of carpal tunnel syndrome, evaluating the morphologic changes of the median nerve in patients with clinical signs and symptoms. Further studies with wider series are needed to confirm our preliminary results.

Extensible elastica solutions on the large deflection of fiber cantilever with circular wavy crimp (I)

Extensible elastica solutions of two-dimensional deflection of crimped fiber cantilever of circular wavy crimp were obtained for one end clamped boundary under concentrated, inclined and dead tip load Fiber was also regarded as a linear elastic material. Crimp was described as a combination of semicircular arcs smoothly connected with each other having constant curvature of all the same magnitude and alternative sign. Also the inclined load direction was taken into account. The solutions were expressed as the recursive forms of integrals in two different cases, which can also be transformed to elliptic integrals respectively. Comparing the data with inextensible ones was carried out. Consequently in the solution, the normal strain of neutral axis is expressed in terms of cross-sectional area, second moment of area and normalized load parameter. Examples of the circular cross-sectioned fiber are presented. As a result, the differences of normalized load between inextensible and extensible elastica solutions when the radius ratio becomes 0.1 were maximum Λ=0.1.

Histomorphometric bone modifications induced by growth hormone treatment in a rabbit model of short bowel syndrome

The effects of recombinant human growth hormone (rhGH) on cancellous and cortical bone were investigated in an experimental rabbit model of short bowel syndrome (SBS). Eighteen young male New Zealand rabbits, 2.0 ± 0.2 kg b.w., were divided into three groups: an SBS Group submitted to a 70% midjejunoileal enterectomy and reanastomosis; an SBS-GH Group undergoing the same surgery and receiving 0.4 mg/kg/day rhGH for 28 days; a Control Group which was sham-operated. Thirty-five days after surgery, all the animals were pharmacologically euthanised and their femurs and L5 vertebrae were used for densitometric and histomorphometric studies. Vertebral and femoral densitometric results showed that the SBS Group presented significantly ( P < 0.01) lower values (10–25%) than the Control and SBS-GH Groups. Significant differences in the cancellous histomorphometric parameters, namely the trabecular bone area (–7% to 46%), trabecular thickness (–21% to 34%) and trabecular separation (17–32%), were observed between the SBS Group and the other groups. Both the SBS and SBS-GH Groups showed significantly ( P < 0.05) higher values than the Control Group in terms of cross-sectional area (~24%), cortical area (~20%), and periosteal perimeter (~9%), while medullary area (41%) and endocortical perimeter (18%) were significantly higher ( P < 0.05) in SBS Group than those of Control Group. The current findings are encouraging and suggest that GH administration in SBS animal model used may improve skeletal tissue remodelling.

The relationship between muscle cross-sectional area and strength in various isokinetic movements among soccer players

The aim of the present study was to examine the relationships between muscle cross-sectional area (CSA) and muscular strength in terms of knee extension and flexion, hip extension and flexion, and hip abduction and adduction among well-trained soccer players. Fourteen university soccer players participated in the study, who had previously been divided into two groups based on ability (Group A: above-average ability; Group B: average ability). Maximal isokinetic and concentric muscular strength was measured in knee extension/flexion, hip extension/flexion and hip abduction/adduction using an isokinetic dynamometer at 1.57 and 4.19 rad·s−1 (3.14 rad·s−1) in both the dominant and non-dominant leg. The CSAs of the thigh, gluteus muscles and iliopsoas muscles were calculated based on magnetic resonance imaging. There was no significant difference between the two groups in muscle CSA and isokinetic strength. Although there were some statistically significant differences between the dominant and non-dominant leg in terms of CSA and strength (P<0.05–0.01), these were small and negligible. Apart from a non-significant relationship between the CSAs of the adductor muscles and hip adductor strength (r<0.26, n.s.), the CSA of the other muscle groups correlated with maximal isokinetic strength (r=0.38–0.64, P<0.05). These results suggest that no difference in muscle characteristics (in terms of muscle CSA and strength) was apparent among well-trained soccer players, even between the dominant and non-dominant leg. There is also a case that the anatomical function of a single (or group of) muscle(s) may not be reflected by the strength—CSA relationship depending on the movements (such as hip adduction-adductor muscle CSA). Thus, further studies are required to develop methods to assess neuromuscular function in relation to muscle morphology among soccer players.

Focusing of an intense neutralized proton beam

An intense low-energy (15–20 keV) proton beam is focused in two stages: ballistic focusing is followed by magnetic compression. The beam is formed by an MAIS wide-aperture source, in which a plasma is generated by many discharge elements via a discharge over the polyethylene surface. In the presence of an external magnetic field, the beam turns out to be overneutralized by electrons coming from the cathode grids of the source and from the target. The maximal focusing efficiency (>70%) is observed within 10 µs after the pulse has been applied if the target is negatively biased. The degree of beam compression in terms of cross-sectional area is 1.6×103. The numerical simulation of the focusing agrees well with the results of measurement.

Accuracy of measurement of acoustic rhinometry applied to small experimental animals.

Nasal obstruction is one of the major symptoms of allergic rhinitis. In the study of the mechanism of nasal obstruction, experiments on animal are useful. In adult humans, acoustic rhinometry has been used to evaluate nasal obstruction by determining nasal cavity dimensions in terms of cross-sectional areas as a function of the distance from the nostril. We modified the equipment used on humans to assess dimensions of nasal airway geometry of small experimental animals. The purpose of this study was to investigate the accuracy of measurement of the modified acoustic rhinometry applied to small experimental animals using nasal cavity models and guinea pigs. Measurement of the nasal cavity models (made of cylindrical silicone tubes) showed that the acoustic rhinometry estimated 85.5% of actual area and 79.0% of actual volume. In guinea pigs, nasal cavity volume determined by the acoustic rhinometry was 73.7 +/- 20.0% of actual volume. The actual volume was estimated by impression material instilled into the nasal cavity of the animals (IM volume), and volume determined by acoustic rhinometry significantly correlated with IM volume. Furthermore, there was a significant negative correlation between the volume and nasal airway resistance in guinea pigs. Measurement of the nasal airway resistance is the method frequently used in the evaluation of the nasal obstruction in guinea pigs. These results suggest that acoustic rhinometry is useful in evaluating nasal obstruction in small experimental animals.

Evaluation of nasal passage patency after antigen and histamine challenge in guinea pigs by acoustic rhinometry.

We investigated the effects of antigen and histamine on the nasal passage patency in guinea pigs with or without nasal allergy. The change of nasal patency was measured by acoustic rhinometry and nasal airway resistance. Acoustic reflections have been used in adult humans to determine nasal cavity dimensions in terms of cross-sectional areas as a function of the distance from the nostril. In order to measure nasal cavity dimensions in guinea pigs, we modified equipment for use in humans by decreasing sound tube dimensions, increasing sampling frequency, and applying a special nosepiece. The percent change of volume, minimum cross-sectional area, and nasal airway resistance showed the largest changes at 10 minutes after antigen challenge in sensitized guinea pigs. There was a significant correlation between the individual percent change of nasal airway resistance and volume or minimum cross-sectional area. Histamine, 10(2) to 10(5) micrograms/mL, caused a dose-dependent reduction in percent change of volume in the challenged side of nonsensitized guinea pigs, but not in the opposite side. These results indicate that the noninvasive acoustic reflections technique is useful in small experimental animals, especially to assess the effect of nasal cavity dimensions after the challenge of antigen or nonspecific stimuli.