Pulsatility and resistance indices in intrarenal arteries of normal adults

In order to establish the normal range of values of Pulsatility (PI) and Resistance (RI) Indices in the intrarenal vasculature, a study of 50 healthy volunteers (23 males, 27 females), divided into five groups of 10 according to age, was performed with Duplex Doppler ultrasound. Both kidneys were examined in all individuals and, in 12, indices were also compared between upper and lower poles of both kidneys. In addition, repeat examinations were performed in nine subjects on three different days, in order to assess the reproducibility of the method. No differences were found in the mean values of both indices between males and females, upper and lower poles, right and left kidneys. A statistically significant increase (p < 0.01, unpaired t-test) was demonstrated when the oldest age group (7th decade) was compared to the youngest age group (3rd decade). The method appeared remarkably reproducible for RI (4.2–7%), with wider variation in the PI (9.5–22.7%).     

The effect of central corneal thickness on estimates of the anterior chamber depth

Background: The slitlamp can be used to estimate the anterior chamber depth (ACD). The length of a slit object is increased until the corneal and iris/lens images appear to just touch. Multiplying the just‐touching‐slit‐length (JTSL) by a conversion factor gives an estimate of the ACD as measured by ultrasonography. The purpose of this study was to determine if central corneal thickness (CCT) affects the accuracy of this technique. Methods: The ACD of 50 subjects was measured by A‐scan ultrasonography and estimated by the slitlamp technique. CCT was measured by ultrasonic pachometry. The refractive error was determined subjectively. Results: The average ultrasonographic ACD for all subjects was 3.32 ± 0.65 mm. The average JTSL was 2.46 ± 0.38 mm. The conversion ratio between the ultrasonographic ACD and the average JTSL was 1.35. The predicted ACD using the regression equation of JTSL on the ultrasound anterior chamber depth (USACD) was 3.32 ± 0.54 mm. The corresponding value using the regression equation of JTSL and CCT on USACD was exactly the same, that is, 3.32 ± 0.54 mm. Conclusion: Incorporation of CCT into a regression equation does not improve the accuracy of the Smith technique.     

STANDARD IMAGING TECHNIQUES OF ENDOSCOPIC ULTRASOUND‐GUIDED FINE‐NEEDLE ASPIRATION USING A CURVED LINEAR ARRAY ECHOENDOSCOPE

Standard imaging techniques using a curved linear array echoendocope are summarized to facilitate the attainment of expertise in endoscopic ultrasonography and endoscopic ultrasound‐guided fine needle aspiration, and to promote the widespread use of this diagnostic and therapeutic tool. Typical images of the mediastinal organs, the bilio‐pancreatic systems and neighboring organs by scanning from the esophagus, stomach, duodenal bulb, and descending portion of the duodenum, are shown in a sequential manner. The basic techniques of endoscopic ultrasound‐guided fine needle aspiration are also presented.     

NEWLY DEVELOPED ULTRASOUND ENDOSCOPE WITH AN ELECTRONIC RADIAL ARRAY TRANSDUCER

A prototype electronic radial scan ultrasound endoscope has been developed by Olympus (Tokyo, Japan) for endoscopic ultrasound (EUS) study. The ultrasound view‐angle of this model is 360° vertical to the scope. Though the diameter of the scanner and the shaft of the scope is bigger than those of the present mechanical radial scan model, clinical manipulation of the new scope is the same as that of the present model. Image quality of the ultrasound picture demonstrated by the electronic radial model was as clear as those provided by the mechanical radial scan model. Ultrasound penetration was better and satisfactory because of less echoic reduction compared to the mechanical radial model. The newly developed electronic radial model can be evaluated as an ultrasound endoscope for the next generation. The advantage of this system is to facilitate the clinical use of color Doppler function and tissue harmonic imaging, and this system can be operated by the same monitor unit as a convex model of ultrasound endoscope.     

Ultrasound for the assessment of the embolic risk of carotid plaques

In a prospective study we compared duplex-ultrasound characteristics of symptomatic internal carotid artery (ICA) stenoses with cranial computerized tomographic (CCT) findings in 82 patients suffering from completed or transient middle cerebral artery symptoms. The aim was to assess the pathogenic role of ICA plaque morphology and the potential embolic risk of ICA plaques. The degree of carotid stenosis was estimated by spectral analysis of the pulsed Doppler signal. The CCT findings were classified as being either normal, lacunar lesions, hemodynamically induced low-perfusion infarctions, or territorial embolic infarctions. According to their ultrasonic features we characterized the ICA plaque surface as smooth or irregular and their structure as homogeneous or heterogeneous. Plaques with an irregular surface and heterogeneous echogenicity dominated significantly in CCT-territorial infarctions (p < 0.01), whereas hemodynamically induced low-perfusion infarctions showed no relationship with any plaque characteristic. High degree ICA stenoses (> 50>%) dominated in both territorial infarctions and low-perfusion infarctions, as compared to ipsilateral normal CCT or lacunes (p < 0.05). Normal CCT and lacunar infarctions were associated with homogeneous and smooth plaques (both p < 0.05). We conclude that > 50% ICA stenoses can cause both hemodynamically induced low-perfusion infarctions as well as thromboembolic territorial infarctions, whereas ulcerated and heterogeneous plaques constitute a high risk factor for arterio-arterial embolic stroke. Furthermore, carotid ultrasound may help to estimate the clinical significance of carotid lesions.     

Mediastinal lymphadenopathy: a variant of incomplete Kawasaki disease

A 14-month-old girl presented with a 4-d history of fever and generalized exanthema. Four characteristic symptoms of incomplete Kawasaki disease (KD) were present on admission (fever, rash, non-purulent conjunctival injection, oropharyngeal changes) and then followed by oedema of the hands and feet and mild plantar desquamation. The typical laboratory features of KD, such as elevated erythrocyte sedimentation rate, leukocytosis, thrombocytosis, and positive C-reactive protein were also seen. Ultrasound examination of the mediastinum revealed the presence of a lymph node, 30 mm in diameter, below the tracheal carina. Thoracic CT scan confirmed the mediastinal lymph node. The patient was treated with aspirin and intravenous γ -globulin. Ultrasound study of the mediastinum, which was carried out 6 weeks after hospital discharge, showed that the lymph node had disappeared. This case illustrates that lymph nodes other than cervical lymphadenopathy should be sought when the diagnosis of classical or atypical KD is suspected.     

Bilateral fracture dislocation of the sacroiliac joint

 We present a rare case of a 27-year-old man sustaining a bilateral fracture dislocation of the sacroiliac joints without disruption of the anterior pelvis, following a fall from a height. Reconstructed images in the coronal plane and three-dimensional CT images were invaluable in the diagnosis and assessment of this injury.     

Morphologic analysis of rat retinocollicular neuron terminals containing monoamine oxidase

The retino-collicular neuron terminals containing type A monoamine oxidase (MAO-A) in the stratum griseum superficiale of the rat superior colliculus were analyzed to provide a morphologic basis for the physiologic role of these neurons in the visual pathway. A computer-assisted, three-dimensional re-construction of the terminal complex associated with the MAO-A-positive terminals was performed. MAO-A-positive terminals originated in the retina and terminated in the stratum griseum superficiale. This was confirmed by tract tracing and enucleation experiments. The terminals were densely grouped in clusters of irregularly shaped swellings. Electron microscopy revealed that the MAO-A-positive terminals were located in a glomerulus-like structure. In this terminal complex, a significant proportion of the axonal profiles (42.96%) synapsed with the MAO-A-positive terminals. Most of the profiles (24.16%) resembled presynaptic dendrites, which represent intermediate elements between the retinal terminals and conventional dendrites. Unlike the glomerulus in the dorsal lateral geniculate body, the MAO-A-positive terminal swellings were not located in the central part of the terminal complex. The terminals had an irregular shape and were located in the complex. The terminal complex was partially ensheathed by glial processes. Furthermore, the membrane surfaces exhibiting synaptic specializations were very small compared with the total surface of the terminal swellings. The membrane length of the synaptic specialization was 5.38% of the total perimeter of the MAO-A-positive terminals.     

Diagnostic imaging of orofacial malformations

Summary Two-dimensional conventional X-rays and computer tomographic imaging systems contribute to the diagnosis and surgical planning of patients with orofacial malformations. The ability to reformat CT scans into three-dimensional osseous and soft tissue surface images has a significant impact on the diagnosis and management of orofacial malformations. Cephalometric evaluation with teleradiography provides precise insight into both the skeletal structures and the soft parts, enabling the radiologist to assess the relationship among the different parts in a given subject, at any given time and in relation to the normal.      

Acute effects of acetazolamide on cerbral blood flow in man

We have followed the time course of the effect of the carbonic anhydrase inhibitor acetazolamide injected i. v. in unanesthetized healthy human beings. The dose administered was 500 mg as a bolus. Cerebral blood flow (CBF) was measured continuously before, during and after the injection, using a pulsed ultrasound doppler system, which measured the instantaneous mean velocity across the lumen of the internal carotid artery, just below its entrance into the skull. Ventilation, heart-rate, end-expiratory PCO₂- arterial PCO₂, pH and systemic blood pressure was also measured. We found that acetazolamide caused a rise in CBF which could be detected as early as 2 min after the injection. A maximal average response of 75% increase in CBF was seen after 25 min. The half-time of the declining phase of the response was 95 min. There were no systematic differences in the CO₂ reactivities, given as ACBF/ΔPACO₂ in % of CBF at normocapnia, before and after acetazolamide injection, regardless of the absolute PACO₂ level. The present dose of the drug caused no change in ventilation, alveolar and arterial PCO₂ or in arterial blood pH indicating that the carbonic anhydrase was not fully inhibited. Our observations show that acetazolamide nevertheless caused a rapid vasodilation in the brain and over a wide range of PCO₂′s. We suggest that this agent has a local vasodilator effect on the cerebral arterioles, unrelated to its specific effects as a carbonic anhydrase inhibitor.