Obstructive uropathy

Recent study has increased the understanding of the physiological processes occurring in obstructive uropathy, in particular the role played by vasoactive mediators and cellular mechanisms. There is an emphasis on developing effective and less invasive means of detection and treatment of ureteric obstruction, although it remains to be determined how the techniques currently being assessed will impact on clinical practice.

Sublabial, transseptal, transsphenoidal approach to the pituitary region guided by the ACUSTAR I system

OBJECTIVE

Advances in imaging resolution have resulted in superior visualization of intracranial anatomy. Because of the inherent complexity of the surgical exposure of these lesions, intraoperative localizing techniques are required. Currently, C-arm fluoroscopy provides only two-dimensional localization for these anatomic structures. The recently described ACUSTAR I system, developed in conjunction with Codman and Shurtleff, Inc. (Randolph, Mass.), is an interactive, image-guided device that allows three-dimensional localization with a degree of accuracy previously unattainable. We assessed the clinical utility of the ACUSTAR I system for intraoperative spatial confirmation during transsphenoidal approaches to pituitary lesions.

METHODS

Eight patients underwent transsphenoidal approaches to pituitary lesions with the assistance of the ACUSTAR I system. The spatial relationships were clinically judged intraoperatively by the surgeon and by use of traditional C-arm fluoroscopy and then were compared with the ACUSTAR I system results.

RESULTS

In all eight patients, the ACUSTAR I system correctly displayed the surgical orientation and provided localization to within less than 1 mm. In two patients, this facilitated the redirection of an errant approach. No complications were associated with the use of this image-guided device.

CONCLUSIONS

The ACUSTAR I system is useful in displaying accurate, three-dimensional anatomic relationships during transsphenoidal approaches to pituitary lesions. This system provides critical information intraoperatively to redirect errant approaches and prevent significant morbidity.

The role of surgery and laser ablation in oesophageal carcinoma

Between January 1990 and December 1994 oesophagectomy was carried out in 42 patients and comparison made with 38 who had palliative laser therapy. Apart from six patients referred after being unresectable at surgical exploration there were no agreed selection criteria, although the laser patients were in general older (mean 64 V 73 year) with a higher proportion of cardiorespiratory co-morbidity (14 per cent V 18 per cent). Lateral margins were involved in 14 per cent of known palliative resections with 50 per cent having positive nodes. The mean operating time was three hours and two chest drains inserted electively were removed after 3.6 days with mean drainage of 817 ml. The mean ICU stay was 5.4 days and 3 had radiological leaks; all but one settled conservatively. The 90 day mortality was 11.9 per cent for surgery and 34 per cent for laser patients. Twenty-three patients (61 per cent) required further courses of laser-therapy for benign anastomotic stenosis. Including the initial treatment of both groups 6.0 procedures per patient year were required in the laser groups compared with 1.1 for surgery. The 1, 2 and 3 year survival was 60 per cent, 31 per cent, 39 per cent for surgery compared with 24 per cent, 8 per cent, 3 per cent for laser--12 surgical patients are still alive and well at mean of 29 months (range 16-68). Surgery where possible with acceptable morbidity and mortality offers good palliation and long-term survival is possible; selection criteria for palliation only need to be defined.

Registration of head volume images using implantable fiducial markers

In this paper, we describe an extrinsic-point-based, interactive image-guided neurosurgical system designed at Vanderbilt University, Nashville, TN, as part of a collaborative effort among the Departments of Neurological Surgery, Computer Science, and Biomedical Engineering. Multimodal image-to-image (II) and image-to-physical (IP) registration is accomplished using implantable markers. Physical space tracking is accomplished with optical triangulation. We investigate the theoretical accuracy of point-based registration using numerical simulations, the experimental accuracy of our system using data obtained with a phantom, and the clinical accuracy of our system using data acquired in a prospective clinical trial by six neurosurgeons at four medical centers from 158 patients undergoing craniotomies to resect cerebral lesions. We can determine the position of our markers with an error of approximately 0.4 mm in X-ray computed tomography (CT) and magnetic resonance (MR) images and 0.3 mm in physical space. The theoretical registration error using four such markers distributed around the head in a configuration that is clinically practical is approximately 0.5-0.6 mm. The mean CT-physical registration error for the phantom experiments is 0.5 mm and for the clinical data obtained with rigid head fixation during scanning is 0.7 mm. The mean CT-MR registration error for the clinical data obtained without rigid head fixation during scanning is 1.4 mm, which is the highest mean error that we observed. These theoretical and experimental findings indicate that this system is an accurate navigational aid that can provide real-time feedback to the surgeon about anatomical structures encountered in the surgical field.

Transurethral needle ablation of the prostate for the treatment of benign prostatic hyperplasia: a collaborative multicentre study

OBJECTIVE

To assess the efficacy and safety of transurethral needle ablation of the prostate (TUNA) for patients with symptomatic benign prostatic hyperplasia (BPH) in a multicentre trial.

PATIENTS AND METHODS

Seventy-six patients were recruited from five centres; all were treated with the TUNA system consisting of a powered radiofrequency generator and a TUNA catheter. The patients were evaluated prospectively using the international prostate symptom score (IPSS), uroflowmetry, quality-of-life score, and other variables, and followed for a mean of 12 months after treatment.

RESULTS

Sixty-eight patients were available for follow-up: TUNA produced significant improvements in the IPSS (median 22 before, to 7.5 after treatment). urinary flow rate (mean 8.7 before, to 11.6 mL/s after treatment) and quality-of-life score (median 5 before, to 2 after treatment) at 12 months.

CONCLUSIONS

If these early promising results are maintained. In the medium to long term, TUNA therapy will be a useful low-morbidity alternative for patients with symptomatic BPH.

Comparison and evaluation of retrospective intermodality brain image registration techniques

PURPOSE

The primary objective of this study is to perform a blinded evaluation of a group of retrospective image registration techniques using as a gold standard a prospective, marker-based registration method. To ensure blindedness, all retrospective registrations were performed by participants who had no knowledge of the gold standard results until after their results had been submitted. A secondary goal of the project is to evaluate the importance of correcting geometrical distortion in MR images by comparing the retrospective registration error in the rectified images, i.e., those that have had the distortion correction applied, with that of the same images before rectification.

METHOD

Image volumes of three modalities (CT, MR, and PET) were obtained from patients undergoing neurosurgery at Vanderbilt University Medical Center on whom bone-implanted fiducial markers were mounted. These volumes had all traces of the markers removed and were provided via the Internet to project collaborators outside Vanderbilt, who then performed retrospective registrations on the volumes, calculating transformations from CT to MR and/ or from PET to MR. These investigators communicated their transformations again via the Internet to Vanderbilt, where the accuracy of each registration was evaluated. In this evaluation, the accuracy is measured at multiple volumes of interest (VOIs), i.e., areas in the brain that would commonly be areas of neurological interest. A VOI is defined in the MR image and its centroid c is determined. Then, the prospective registration is used to obtain the corresponding point c' in CT or PET. To this point, the retrospective registration is then applied, producing c" in MR. Statistics are gathered on the target registration error (TRE), which is the distance between the original point c and its corresponding point c".

RESULTS

This article presents statistics on the TRE calculated for each registration technique in this study and provides a brief description of each technique and an estimate of both preparation and execution time needed to perform the registration.

CONCLUSION

Our results indicate that retrospective techniques have the potential to produce satisfactory results much of the time, but that visual inspection is necessary to guard against large errors.

Measuring clinical nurse performance: development of the King's Nurse Performance Scale

The development of the King's Nurse Performance Scale to measure clinical nurse performance is described. Instrument construction was informed by the Slater Nursing Competencies Rating Scale [Wandelt, M. A. and Stewart, D. S. (1975) Slater Nursing Competencies Rating Scale. Appleton-Century Crofts, New York] together with key literature and the use of expert opinion. The instrument was utilised to observe the clinical performance of senior student nurses (n = 99) and data which were at the ordinal level were statistically analysed using a variety of non-parametric tests. Key findings of students' observed nursing practice are presented in a separate paper (While et al., unpublished document). Internal consistency testing of the King's Nurse Performance Scale using Cronbach's alpha coefficient revealed a promising alpha for the total instrument (r = 0.93). The subsection alphas indicated that further refinement may enhance the strength of the instrument as a tool for the measurement of performance in different domains of practice. The possible use of the Scale in the professional development of newly qualified nurses is suggested.

Determination of testicular function after torsion by DNA flow cytometry of serial fine-needle aspirates

OBJECTIVE

To determine the efficacy of DNA flow cytometric analysis of testicular percutaneous fine-needle aspirates in the assessment and follow-up of testicular function after torsion, and to determine the relationship between the duration of torsion and testicular injury.

MATERIALS AND METHODS

Three groups of 15 adult rats underwent a 720 degrees torsion, with fixation of the mesorchial ligament, for 1, 3 or 5 h. Bilateral aspirations, performed 7, 21 and 35 days after torsion were examined by flow cytometry. Testes were harvested and evaluated histologically using Johnsen's scoring.

RESULTS

Irreversible testicular injury occurred in all three groups of rats, with loss of function after 1 h and loss of viability after 3 and 5 h. The results from flow cytometry suggested significant contralateral testicular injury (P < 0.025) but this was not supported by the histological evaluation. There was a strong correlation between the testicular function assessed by flow cytometry and by Johnsen's scoring of histological specimens (r2 = 0.95).

CONCLUSION

The assessment of testicular aspirates by flow cytometry allows testicular function to be followed after torsion in rats, and potentially in humans. Using DNA flow cytometry, the temporal course of the twisted testis in the adult rat was determined; contralateral testicular injury following the reversal of torsion could not be excluded.

High-intensity focused ultrasound in the treatment of benign prostatic hyperplasia

OBJECTIVE

To assess the role of high-intensity focused ultrasound (HIFU) in the treatment of symptomatic benign prostatic hyperplasia (BPH).

PATIENTS AND METHODS

Thirteen patients (mean age 65 years, range 58-74) were treated with HIFU as part of a phase-2 clinical trial and evaluated prospectively using the International Prostate Symptom Score, uroflowmetry, and transrectal and transabdominal ultrasonography to determine prostate size and post-void residual urine volume, respectively. The results and the patients' satisfaction were assessed at regular intervals for 2 years.

RESULTS

The new procedure was learned quickly and was easy to perform. Symptom scores decreased from a mean of 23 before treatment to 5 after 12 months and 7 after 2 years. There was an initial improvement in flow rates but they then declined. The size of the prostate and the post-void residual volume were both decreased after treatment.

CONCLUSIONS

The treatment is safe, easy to implement and was effective in substantially reducing symptom scores in these few patients. However, we would not encourage its use as an alternative to other well established treatment modalities until it has been assessed fully in a randomized trial.

Case report: combined hand access with laparoscopic pneumoperitoneum in intraperitoneal adhesiolysis

Previous abdominal surgery is one of the relative contraindications to safe induction of pneumoperitoneum with a Veress needle. Similarly visual inspection with a telescope may be limited and instrumental manipulation difficult. The manual ability to distract bowel loops and finger dissect greatly facilitates adhesiolysis and this is lost with conventional laparoscopy. A novel hand-access port is described which combines manual tactile ability with minimally invasive laparoscopic adhesiolysis.

Laparoscopic-assisted rectopexy using a novel hand-access port

Many surgeons who were ready converts to laparoscopic cholecystectomy did not translate the technique to more advanced procedures. There are several reasons: increased operating times, a steeper learning curve, concern for oncological efficacy, and the loss of manual tactile ability. As shown with this report on laparoscopic assisted rectopexy, many of these difficulties can be overcome using the IntromitTM while still maintaining the benefits of minimally invasive surgery.

Key influences on the professional socialisation and practice of students undertaking different pre-registration nurse education programmes in the United Kingdom

A principal aim of pre-registration nurse education programmes is the process of effective socialisation of students into the professional role. Key influences on the professional socialisation and practice of students undertaking such programmes were explored using a semi-structured interview approach (N = 99). This work formed part of a major comparative study of outcomes of pre-registration nurse education programmes in the United Kingdom. Analysis revealed differences between the programmes regarding positive influences of the respective courses; therapeutic influences of the practice environment; modelling performance on exemplars of high quality practice; and the identification of teachers within the educational setting and nurses in practice as key persons. This study has confirmed that the positive influence of the education programmes and the practice environment as well as high quality role models from both education and practice establishments are critical to the professional socialisation of student nurses.

Operationalisation of an observation instrument to explore nurse performance

This paper explores the operationalization of an observation instrument to explore actual situated behaviour in the clinical setting. Challenges encountered during this process and strategies employed to address these difficulties are discussed. This work formed part of a comparative study of outcomes of pre-registration nurse education programmes commissioned by the English National Board for Nursing, Health Visiting and Midwifery.

Effect of geometrical distortion correction in MR on image registration accuracy

In this article we investigate the effect of geometrical distortion correction in MR images on the accuracy of the registration of X-ray CT and MR head images for both a fiducial marker (extrinsic point) method and a surface-matching technique. We use CT and T2-weighted MR image volumes acquired from seven patients who underwent craniotomies in a stereotactic neurosurgical clinical trial. Each patient had four external markers attached to transcutaneous posts screwed into the outer table of the skull. The MR images are corrected for static field inhomogeneity by using an image rectification technique and corrected for scale distortion (gradient magnitude uncertainty) by using an attached stereotactic frame as an object of known shape and size. We define target registration error (TRE) as the distance between corresponding marker positions after registration and transformation. The accuracy of the fiducial marker method is determined by using each combination of three markers to estimate the transformation and the remaining marker to calculate registration error. Surface-based registration is accomplished by fitting MR contours corresponding to the CSF-dura interface to CT contours derived from the inner surface of the skull. The mean point-based TRE using three noncollinear fiducials improved 34%-from 1.15 to 0.76 mm-after correcting for both static field inhomogeneity and scale distortion. The mean surface-based TRE improved 46%-from 2.20 to 1.19 mm. Correction of geometrical distortion in MR images can significantly improve the accuracy of point-based and surface-based registration of CT and MR head images. Distortion correction can be important in clinical situations such as stereotactic and functional neurosurgery where 1 to 2 mm accuracy is required.

An automatic technique for finding and localizing externally attached markers in CT and MR volume images of the head

An image processing technique is presented for finding and localizing the centroids of cylindrical markers externally attached to the human head in computed tomography (CT) and magnetic resonance (MR) image volumes. The centroids can be used as control points for image registration. The technique, which is fast, automatic, and knowledge-based, has two major steps. First, it searches the entire image volume to find one voxel inside each marker-like object. We call this voxel a "candidate" voxel, and we call the object a candidate marker. Second, it classifies the voxels in a region surrounding the candidate voxel as marker or nonmarker voxels using knowledge-based rules and calculates an intensity-weighted centroid for each true marker. We call this final centroid the "fiducial" point of the marker. The technique was developed on 42 scans of six patients-one CT and six MR scans per patient. There are four markers attached to each patient for a total of 168 marker images. For the CT images the false marker rate was zero. For MR the false marker rate was 1.4% (Two out of 144 markers). To evaluate the accuracy of the fiducial points, CT-MR registration was performed after correcting the MR images for geometrical distortion. The fiducial registration accuracy averaged 0.4 mm and was better than 0.6 mm for each of the eighteen image pairs.

Methods of renal blood flow measurement

Variations in regional renal blood flow have been implicated in a variety of disease states. Many techniques have been developed in an attempt to accurately assess these changes. The microsphere technique is the most widely used method at the present time. This technique allows focal measurements to be performed, but there is a conflict between the resolution of the method and the number of microspheres necessary in each sample. New imaging techniques such as tomography and autoradiography enable visual assessment of renal blood flow. Though there is no ideal method, these techniques have opened up new possibilities in the quantification of regional renal blood flow.

A universal method for geometric correction of magnetic resonance images for stereotactic neurosurgery

Accurate stereotactic navigation depends strongly upon the spatial fidelity of the image used for registration. Clinically significant levels of geometric distortion are present in standard MR images, limiting their utility. A technique for correction of all geometric distortions in spine echo MR images was assessed in a prospective clinical trial of 19 stereotactic craniotomies. The Euclidean error in target registration between CT and MR was significantly reduced, from 3.833 +/- 0.992 to 1.986 +/- 0.605 mm. The results of this clinical trial support the incorporation of this MR image rectification protocol into standard clinical practice.

Combined androgen blockade is the treatment of choice for patients with advanced prostate cancer: the argument against

The concept that patients with advanced prostate cancer will survive longer if treated by a combination of castration and the blockade of androgens of non-testicular origin cannot be substantiated. When all of the available studies are reviewed, meta-analysis does not show any significant improvement in mortality when the combined approach is used. Some studies have suggested that combined treatment is particularly useful in patients with minimal disease, or with a good prognosis; it must be remembered that these are smaller groups which have been taken from large numbers of patients in which the endpoint was observations on the larger group and not the small subgroup.

Accurate localization of cortical convolutions in MR brain images

Analysis of brain images often requires accurate localization of cortical convolutions. Although magnetic resonance (MR) brain images offer sufficient resolution for identifying convolutions in theory, the nature of tomographic imaging prevents clear definition of convolutions in individual slices. Existing methods for solving this problem rely on heuristic adaptation of brain atlases created from a small number of individuals. These methods do not usually provide high accuracy because of large biological variations among individuals. The authors propose to localize convolutions by linking realistic visualizations of the cortical surface with the original image volume. They have developed a system so that a user can quickly localize key convolutions in several visualizations of an entire brain surface. Because of the links between the visualizations and the original volume, these convolutions are simultaneously localized in the original image slices. In the process of the authors' development, they have implemented a fast and easy method for visualizing cortical surfaces in MR images, thereby making their scheme usable in practical applications.

Dysregulated cytokine expression in vivo in prediseased and diseased autoimmune-prone MRL mice

Macrophages (mø) from prediseased autoimmune-prone MRL/ + and MRL/lpr mice produce markedly decreased levels of IL-1 in vitro in response to LPS. In contrast, tissues from diseased MRL/lpr mice overexpress IL-1 in vivo. To determine whether IL-1 underproduction in the MRL strains is solely an in vitro phenomenon, we compared in vivo cytokine mRNA expression from prediseased age-matched MRL/ + and MRL/lpr mice to that from normal BALB/c and C3HeB/FeJ mice. Like mø in vitro, whole organ RNA from the spleen, liver, and kidney of MRL/ + and MRL/lpr mice showed down-regulation of IL-1 RNA following intraperitoneal injection of LPS. This abnormality in inducible IL-1 expression was present in all MRL mice, irrespective of disease stage or the presence of the lpr gene. On the other hand, only diseased MRL/lpr mice displayed elevated and constitutive expression of IL-1 in their livers and kidneys. We suggest that inducible expression is most indicative of the intrinsic, or genetic, capacity of cells to produce cytokine, whereas constitutive expression reflects extracellular disease-related inflammatory stimuli present only in the diseased MRL/lpr strains. By restricting our studies to prediseased MRL mice, we have tried to eliminate the effects of disease and to focus on the predisposing genetic background. The existence both in vitro and in vivo of a defect in inducible IL-1 expression by prediseased MRL mice suggests that the molecular abnormality underlying this defect may be a part of this predisposing background to autoimmunity.