Narrow-band imaging: potential and limitations

The purpose of introducing optical electronics into video endoscopes is to improve the accuracy of diagnosis through image processing and digital technology. Narrow-band imaging (NBI), one of the most recent techniques, involves the use of interference filters to illuminate the target in narrowed red, green and blue (R/G/B) bands of the spectrum. This results in different images at distinct levels of the mucosa and increases the contrast between the epithelial surface and the subjacent vascular network. NBI can be combined with magnifying endoscopy with an optical zoom. The aim of this new technique is to characterize the surface of the distinct types of gastrointestinal epithelia - e. g., intestinal metaplasia in Barrett's esophagus. The technique may also make it possible to demonstrate disorganization of the vascular pattern in inflammatory disorders of the gastrointestinal mucosa and in superficial neoplastic lesions in the esophagus, stomach, and large bowel.

Premalignant lesions of the esophagogastric mucosa

Premalignant esophagogastric (EG) lesions develop against a background of chronic inflammation, called a premalignant condition. For esophageal squamous cell cancer, causal factors include alcohol, tobacco, hot beverages, oral consumption of opioids, and probably infectious agents. For adenocarcinoma in the Barrett's esophagus (BE), gastroesophageal reflux disease (GERD) is the principal causal factor. At the EG junction, adenocarcinoma arises either from the esophagus or from the proximal stomach (cardia). In the distal stomach, chronic gastritis with atrophy is the premalignant condition related to Helicobacter pylori infection. A high intake of salt and low intake of antioxidants also play a role. The histopathology of EG premalignant lesions is now included in the groups low-grade and high-grade intraepithelial neoplasia (IEN) of the revised Vienna classification. Endoscopy is the gold standard for detection of the lesions at the preclinical stage and their appearance is described in subtypes of the type 0 of the Japanese classification, with a distinction between protruding and nonprotruding lesions. There is a priority for primary prevention of causal factors rather than for mass screening, which is justified only in Japan for the prevention of stomach cancer. The trend to early detection of premalignant lesions justifies the development of mini-invasive endoscopic procedures of treatment.

Using magnetic resonance imaging to characterize pedicle asymmetry in both normal patients and patients with adolescent idiopathic scoliosis

STUDY DESIGN

Morphometric analysis of vertebrae from normal patients and patients with adolescent idiopathic scoliosis.

OBJECTIVES

To use magnetic resonance imaging to assess pedicle asymmetry in normal patients and patients with adolescent idiopathic scoliosis in the early stages of scoliosis development and to determine if patients with adolescent idiopathic scoliosis exhibited a consistent vertebral morphology.

SUMMARY OF BACKGROUND DATA

To date, most studies of vertebral morphology in adolescent idiopathic scoliosis have produced conflicting data, especially on pedicle length, and have been conducted on patients in the late stages of scoliosis development, which may affect the patterns of vertebral morphology detected. Magnetic resonance imaging enables in vivo assessment of curves during development and permits improved acquisition of transverse images.

METHODS

Magnetic resonance images of 76 pedicles from 8 normal patients and 80 pedicles from 10 patients with adolescent idiopathic scoliosis were examined retrospectively. Recorded parameters included pedicle lengths, pedicle widths, pedicle areas, pedicle perimeters, and lamina lengths. The extent and direction of asymmetry in vertebrae from normal patients and patients with adolescent idiopathic scoliosis were determined and compared.

RESULTS

Normal patients displayed significant neural arch asymmetry, with the left sided measurements being greater. Patients with adolescent idiopathic scoliosis also displayed significant neural arch asymmetry; however, the longer pedicle was not consistently on the convexity or the concavity.

CONCLUSIONS

The baseline used to assess adolescent idiopathic scoliosis vertebral morphology must take into consideration the extent and direction of normal vertebral asymmetry. The pattern of vertebral asymmetry seen inadolescent idiopathic scoliosis may depend on the specific cause of the disorder, with no consistent pattern evident when data from different causes are pooled together.

Diagnosis of esophagogastric tumors

Esophagogastric tumors occur in three sectors: the esophagus, the EG junction and the non-cardia stomach. Neoplasia develops in the squamous stratified epithelium of the esophagus and in the columnar epithelium of the Barrett's esophagus or in the stomach. At the junction, tumors arise either in a very short Barrett's esophagus or in the gastric epithelium of the cardia. The prognosis of tumors detected at the advanced stage is poor. Secondary prevention requires detection at the early stage. Most superficial neoplastic lesions in the esophagus and in the stomach have a non-protruding appearance, which is similar for premalignant and malignant lesions. Improved accuracy in endoscopic diagnosis and prediction of histology prior to biopsy and treatment decision is based upon magnification with a optical zoom and electronic processing of the captured image with structure enhancement, enhancement of the color of hemoglobin and narrow band imaging. This applies particularly to the exploration of the Barrett's esophagus for identification of the areas with intestinal metaplasia and of flat neoplastic areas. In spite of the predictive value of endoscopy for histology, biopsy samples are still required for pathology and eventually studies with biological markers. Spectroscopic techniques provide a new perspective, up to the level of molecular endoscopy, but they are unlikely to be cost/effective. The classification in the sub-types 0 of neoplastic lesions has some relevance to prediction of depth of invasion. In the esophagus, EUS staging with high frequency miniprobes is a useful complement.

A model for the efficacy of combined inhibitors

AIMS

The method of the sum of the fractional inhibitory concentrations (SigmaFIC) is used ubiquitously in the investigation of antimicrobial combinations. The inherent assumption of this simple equation is that in a mixture all antimicrobials have identical dose responses. The aim of this work was to analyse the outcome of removing this assumption.

METHODS AND RESULTS

A model to describe the efficacy of combined inhibitors was produced which removed the assumption of identical dose responses. The results of several checkerboard experiments showed that the new model, termed the facomb was a more general form of the SigmaFIC method, but the features described by the SigmaFIC as either synergy or antagonism could be attributed to differences in the dose responses of antimicrobials in combination. Where the model failed to adequately describe experimental data it was suggested that these might be cases of true antagonism or synergy.

CONCLUSIONS

The SigmaFIC methodology used to describe the effect of antimicrobial combinations (preservatives and antibiotics) is valid only when it is demonstrated that individual components of the mixture have identical dose responses. Otherwise the SigmaFIC method is invalid. Descriptions of antimicrobial synergy may simply be due to the mixing of antimicrobials with differing dose responses.

SIGNIFICANCE AND IMPACT OF THE STUDY

Studies aimed at producing synergistic mixtures of antimicrobials, which ignore the dose response of the individual antimicrobials, may waste valuable research effort looking for a physiological explanation for an apparent synergy, where none, in-fact, exists. Conversely, mixing antimicrobials with very different dose responses might lead to mixtures with an 'apparent' synergy which may themselves be very useful therapeutically.

Treatment of esophagogastric tumors

Esophageal and gastric tumors are often considered as a single group: they share similar symptoms - upper GI endoscopy with a flexible video-endoscope is the gold standard procedure of detection - similar techniques of endotherapy for cure or palliation are offered for both types of tumors. When the endoscopic procedure is performed for a superficial cancer or its precursors, with a curative intent, endoscopic mucosal resection (EMR) is generally preferred to mucosal ablation with a thermal (Nd:YAG) or non-thermal (photodynamic therapy) procedure. In addition to esophageal squamous cell cancer and gastric cancer, new indications of EMR arise in the Barrett esophagus. Guidelines for safe indications concern diameter, polypoid or non polypoid morphology with the subtypes elevated, flat and depressed, and depth of invasion. A superficial invasion in the sub-mucosa is a relative contra-indication in the esophagus, but not in the stomach. The technique of EMR is now codified with an injection into the submucosa for lifting the lesion and either suction with a cap, grasping with a forceps if a 2 channel instrument is used, or tissue incision with a needle knife. En bloc, gives better results than piecemeal resection. The most frequent complication is bleeding. When legitimate indications are respected, the results of EMR are equivalent to those of surgical resection and have reached the consensus level. The major indication in palliation is the relief of dysphagia from malignant esophageal obstruction. Increased indications are proposed for malignant pyloric obstruction. Multiple models of metal expandable and coated stents with appropriate balance between rigidity and flexibility (nitinol alloy) and enough expansive radial force are now offered. After stenting the survival period is short and there is a toll of complications.

Diagnosis of esophagogastric tumors

There is increasing concern regarding the need to establish guidelines for upper gastrointestinal endoscopy. This applies to the reliability of the diagnosis of early cancer, tolerance, and the need to reduce the use of conscious sedation in order to contain costs--one reason why nasogastroscopy with a thin fiberscope is being applied with increasing success. Recent advances that have been made in the early diagnosis of esophageal and gastric tumors now require high-resolution video gastroscopes and the routine use of chromoscopy. For a long time, the helpful contribution made by the zoom video endoscope to the identification of the pit pattern in neoplastic lesions was limited to the colon. However, the most recent zoom endoscopes, with improved mechanical characteristics and a standard diameter, have now opened up relevant applications in the analysis of early esophageal or gastric malignancies. The best example of this is the identification of the pit pattern in intestinal metaplasia in Barrett's esophagus, although the classification of the pit pattern in upper gastrointestinal neoplasia is still being investigated. Spectroscopic analysis of the response of neoplastic tissue to an applied photon beam has been hampered by the complex origins of the efferent photons. Recent technology, available only through a physical laboratory allows simultaneous analysis of fluorescence, reflectance, and light scattering. In this situation, the method has obtained sensitivity and specificity rates of nearly 100% in classifying low-grade dysplasia, high-grade dysplasia, and cancer in Barrett's esophagus. With regard to depth exploration in the wall of the digestive tract, endosonographic examination using a high-frequency probe (20-30 MHz) may be challenged in the future by the technique of optical coherence tomography, a method that does not require acoustic transmission through water and provides a much higher resolution, of up to 10 microm. Optical coherence tomography could be used in the staging of intramucosal esophageal cancer and for detecting intestinal metaplasia in the esophagus. In conclusion, the increasing progress being made in the accuracy of endoscopic diagnosis emphasizes the need for cost-benefit analyses of screening and surveillance protocols.

The components of the magnetic resonance image of the neurocentral junction

The neurocentral junction (NCJ) is a cartilaginous growth plate located between the vertebral centrurn and the neural arch. In characterizing the age of closure of this growth plate, anatomic studies have suggested that the NCJ closes before age 10, whereas MRI studies have suggested that the NCJ does not fuse until adolescence In this study, gross anatomic and histologic sections were correlated with MR images to determine the components of the NCJ image. The NCJ image appeared as a thick white line that was shown to encompass the cartilage of the growth plate, the surrounding woven bone and a portion of the trabecular bone of the vertebra. Although the MR pixels were too large to completely resolve the tissues that surround the growth plate, MRI was shown to be a valuable technique of visualizing the NCJ cartilage and further MRI studies of the human NCJ are needed.

Development of the neurocentral junction as seen on magnetic resonance images

The neurocentral junction (NCJ) is a cartilaginous growth plate in the vertebra that has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS) since the early 1900s. Studies to date have focused on the age of closure without characterizing normal NCJ development. Using MRI, the normal development of the NCJ image can be determined and the stages preceding the disappearance of the NCJ image can be characterized. 405 NCJs from 11 pediatric patients were examined using MRI and the various images were categorized. NCJ development encompassed five stages, with a specific pattern of absence of the NCJ image noted in each vertebra and in the vertebral column as a whole. The image of the NCJ first became absent in the cervical region (age 6), then in the lumbar region (age 12) and finally in the thoracic region (age 14). These patterns of development serve as a baseline to evaluate NCJ pathology in conditions such as adolescent idiopathic scoliosis (AIS).

[An orbital exostosis, the history of its removal and didactic presentation in the XIXth century and today ...]

During a meeting on Paleopathology an anatomic piece dating back to 1853 was presented by Dr Thillaud. It consisted of a right hemiskull, the orbital cavity of which was entirely filled by a bone tumour, which was considered as benignant according to all macroscopic paleopathological and radiological criteria. The situation of the tumour in the skeleton was surprising, considering the report in the Dupuytren Museum catalogue which mentioned its removal and a long survival of the patient after the operation. After some research, it was possible to find out all details of the case history, of the removal of the tumour and of its aberrant presentation in the skull which was solely done in a didactic purpose, as far back as 1853. This observation is a further proof of the interest of written documents in Paleopathology and of the evident connexion of this discipline with the History of Medicine.

Radiofrequency facet joint denervation in the treatment of low back pain: a placebo-controlled clinical trial to assess efficacy

STUDY DESIGN

A prospective double-blind randomized controlled trial was performed.

OBJECTIVE

To assess the efficacy of percutaneous radiofrequency articular facet denervation for low back pain.

SUMMARY OF BACKGROUND DATA

Uncontrolled observational studies in patients with low back pain have reported some benefits from the use of facet joint radiofrequency denervation. Because the efficacy of percutaneous radiofrequency had not been clearly shown in previous studies, a randomized controlled trial was conducted to assess the efficacy of the technique for improving functional disabilities and reduce pain.

METHODS

For this study, 70 patients with low back pain lasting of more than 3 months duration and a good response after intraarticular facet injections under fluoroscopy were assigned randomly to receive percutaneous radiofrequency articular facet denervation under fluoroscopic guidance or the same procedure without effective denervation (sham therapy). The primary outcomes were functional disabilities, as assessed by the Oswestry and Roland-Morris scales, and pain indicated on a visual analog scale. Secondary outcomes included spinal mobility and strength.

RESULTS

At 4 weeks, the Roland-Morris score had improved by a mean of 8.4% in the neurotomy group and 2.2% in the placebo group, showing a treatment effect of 6.2% (P = 0.05). At 4 weeks, no significant treatment effect was reflected in the Oswestry score (0.6% change) or the visual analog pain score (4.2% change). At 12 weeks, neither functional disability, as assessed by the Roland-Morris scale (2.6% change) and Oswestry scale (1.9% change), nor the pain level, as assessed by the visual analog scale (-7.6% change), showed any treatment effect.

CONCLUSIONS

Although radiofrequency facet joint denervation may provide some short-term improvement in functional disability among patients with chronic low back pain, the efficacy of this treatment has not been established.