Registration of 3-D images using weighted geometrical features

The authors present a weighted geometrical feature (WGF) registration algorithm. Its efficacy is demonstrated by combining points and a surface. The technique is an extension of Besl and McKay's (1992) iterative closest point (ICP) algorithm. The authors use the WGF algorithm to register X-ray computed tomography (CT) and T2-weighted magnetic resonance (MR) volume head images acquired from eleven patients that underwent craniotomies in a neurosurgical clinical trial. Each patient had five external markers attached to transcutaneous posts screwed into the outer table of the skull. The authors define registration error as the distance between positions of corresponding markers that are not used for registration. The CT and MR images are registered using fiducial paints (marker positions) only, a surface only, and various weighted combinations of points and a surface. The CT surface is derived from contours corresponding to the inner surface of the skull. The MR surface is derived from contours corresponding to the cerebrospinal fluid (CSF)-dura interface. Registration using points and a surface is found to be significantly more accurate then registration using only points or a surface.

Obstetric health services in Far North Queensland: is choice an option?

In remote Far North Queensland, evacuation for mandatory hospital births saves lives. However, morbidity and mortality for mothers and infants remain high. Results from a retrospective study of deliveries over a one-year period showed significant differences in obstetric risk and outcomes among rural and urban Aboriginal, Torres Strait Islander and Caucasian women. Choices of birth place for remote residents were severely limited but those women with education and knowledge about how the system worked utilised options alternative to the regional public hospital. The findings from both the retrospective hospital sample and interviews among remote-area residents of Far North Queensland confirm the need to develop community-based perinatal services to reduce cultural and social barriers to clinical care.

Cardiorespiratory effects of laparoscopy with and without gas insufflation

BACKGROUND

Patients who are undergoing laparoscopic procedures can present with a number of ventilatory and circulatory problems. The use of a gasless technique for performing a laparoscopy by using a mechanical lifting device may potentially avoid such problems.

OBJECTIVE

To compare the cardiorespiratory effects of laparoscopy with and without gas insufflation.

METHODS

Twelve adult pigs were randomized to undergo a laparoscopy by using either carbon dioxide insufflation or mechanical elevation. Full invasive monitoring was performed preoperatively and at 10-minute intervals throughout the operative period. Parameters that were measured included blood gas determinations, mean arterial pressure, pulmonary arterial pressure, pulmonary capillary wedge pressure, central venous pressure, cardiac output, stroke volume, and total peripheral resistance.

RESULTS

Carbon dioxide insufflation unlike mechanical elevation led to a fall in PO2 and absorption of a significant quantity of CO2, resulting in hypercapnia, acidosis, and a consequent hyperdynamic circulation.

CONCLUSION

These findings have significant implications for the use of CO2 insufflation for laparoscopy in patients with a compromised respiratory or cardiac status.

Clinical problem-solving using video simulation: an investigation

This paper examines the use of videotape simulation as a research method for the exploration of clinical problem-solving. The challenges posed and the strategies employed to overcome the difficulties encountered are discussed. The simulation forms part of a larger comparative study of outcomes of pre-registration nurse education programmes, commissioned by the English National Board for Nursing, Midwifery and Health Visiting.

Prospective evaluation of a composite scoring system for mammographically detected cytologically assessed impalpable breast abnormalities

The aim of all breast screening programmes is a reduction in deaths from the disease. It is hoped that this can be achieved with minimal intervention in the patient cohort who do not have cancer. In this study we have assessed the efficacy of a combination of mammographic and cytological scoring systems in the evaluation of 208 women with screen-detected non-palpable breast lesions. All mammograms were scored 1-5 and those with a score of 3 or more required needle localization. A cytology score of 1 to 5 was generated for each patient according to a similar system and an aggregate score for each patient was achieved by the addition of the mammographic and cytology score. Ninety-three of the 208 patients had malignancy--the positive predictive value for mammography alone in this series was 45%. All 58 patients who had an aggregate score of 8 or greater had cancer. The 60 patients who had an aggregate score of 4 had benign disease on excision biopsy. We suggest that a 'wait and repeat mammogram' approach is appropriate in patients with grade 3 mammography and benign (grade 1) cytology. Patients with an intermediate aggregate score of 5-7 should have an excision biopsy and those with an aggregate score of 8 could have definitive surgery rather than excision biopsy. Application of this aggregate scoring technique would enhance the delivery of more appropriate surgery to a majority of patients with screen-detected breast abnormalities.

Phytotherapeutic agents in the management of symptomatic benign prostatic hyperplasia

Phytotherapeutic agents constitute a large part of the market for the pharmacological treatment of symptomatic BPH. At present, these agents are being used on an empirical basis with some success in relieving symptoms. They have not been shown to have any effect on objective indices. Several agents are presently undergoing randomized trials.

Regional renal blood flow in normal and disease states

Renal function is intimately dependent on renal blood flow. Alterations in either total or regional renal blood flow have major consequences for renal function. Through homeostatic mechanisms the kidneys are able to maintain relatively stable rates of flow over a wide range of perfusion pressures. A combination of neural, endocrine, exocrine and autocrine signals serve to regulate renal blood flow at both local and systemic levels. Alterations in the balance of these systems occur in the presence of certain pathophysiological conditions and an understanding of the subsequent changes in regional renal blood flow distribution aids in the understanding of the associated changes in renal function. The regulation and distribution of regional blood flow and the effects of surgical and pathophysiological conditions on these factors are reviewed.

Prostate disease: management options for the primary healthcare team. Report of a working party of the British Prostate Group

The prostate gland has attracted a remarkable increase in interest in the past few years. The two most common diseases of this gland, benign prostatic hyperplasia and carcinoma of the prostate, have been brought into greater prominence by new diagnostic methods, public interest, and a wider choice of surgical and non-surgical treatments. Uncertainty about the significance of these changes has occurred because of the rapidity of change, the profusion of statements, opinions and promotions, and the relatively little guidance available from the profession. Ten urologists and two general practitioners have reviewed the relevant evidence about these two prostate diseases and the newer diagnostic methods; their conclusions are summarised here. Management options and guidance on clinical practice are also discussed. Because of a number of unresolved diagnostic and management issues, detailed requirements for practice guidelines have not been specified.

Anatomy of the prostate and distribution of early prostate cancer

Many of the difficulties in understanding diseases of the prostate have arisen through poor understanding of the anatomy of the prostate. The recent description of histologically separate zones in the prostate has been an important advance, allowing evaluation of separate cancers arising in the transition and peripheral zones of the prostate. While the majority of cancers sampled at transurethral resection of the prostate (TURP) are of transition zone origin, most of these prostates contain separate cancers in the peripheral zone. The peripheral zone cancers have a higher grade-to-volume ratio and are more frequently associated with histological features of progression (extracapsular extension, seminal vesicle invasion) than transition zone cancers. Furthermore, peripheral zone cancers are frequently associated with prostatic intraepithelial neoplasia, in contrast to transition zone cancers. These findings suggest a greater biological activity for cancers arising in the peripheral zone. The majority of cancers detected by digital rectal examination are of peripheral zone origin. While associated transition zone cancers are less frequently present than in TURP sampled prostates, a similarly high association of peripheral zone cancers with histological indicators of biological activity is seen. DNA ploidy analysis of separate foci in radical prostatectomy specimens confirms a significantly higher rate of non-diploidy in cancers of peripheral zone origin, some of very small volume, which further suggests a greater biological activity compared to transition zone cancers.

Renal haemodynamics and prostaglandin synthesis in partial unilateral ureteric obstruction

Haemodynamic changes in partial unilateral ureteric obstruction (PUUO) may be related to altered prostaglandin synthesis. In 12 dogs the left ureter was partially obstructed for 5 weeks. In six dogs the ureter was reimplanted into the bladder and to investigate the effect of this procedure on the contralateral side the other six animals underwent ipsilateral nephroureterectomy. Renal blood flow (RBF) was measured by the distribution of radiolabelled microspheres. Changes in urinary prostaglandin (PG) concentrations were validated by renin activity using angiotensin I. Reduced left RBF during obstruction was associated with increased thromboxane A2 synthesis (P < 0.01). Increased RBF to the non-obstructed side was associated with elevated PGE2 formation (P < 0.05). Elevated angiotensin I levels (P < 0.01) corresponded to maximal increases in PG synthesis. Reimplantation of the obstructed kidney did not exert a direct effect on contralateral RBF or PG concentration. Haemodynamic changes in PUUO in vivo are associated with alterations in renal PGs.

The measurement of nurse performance and its differentiation by course of preparation

This paper addresses the concept of nurse performance, its measurement and its differentiation by programme of preparation. It is evident from the research conducted to date that a variety of methodologies have been used to explore and compare nurse performance. The process of direct observation, however, has been selected to a lesser degree, and it is argued that its potential has yet to be realized. Further, in recognition of the methodological challenges inherent within research of this nature it is suggested that nurse performance should be explored from a variety of perspectives, using a multi-method research design. Significantly, educational preparation as a potential discriminator of performance has been explored only to a limited extent and studies carried out in the United States predominate. In view of recent nurse education changes in the United Kingdom and the introduction of Project 2000, empirical work comparing outcomes of the different courses of pre-registration preparation is urgently required. The authors are currently engaged in a comparative study of outcomes of pre-registration nurse education programmes funded by the English National Board for Nursing, Midwifery and Health Visiting. This paper draws upon the literature reviewed to date.

The effects of acute and chronic JJ stent placement on upper urinary tract motility and calculus transit

OBJECTIVE

To determine the pathophysiological changes in upper urinary tract motility and calculus transit which may occur following JJ stent insertion.

MATERIALS AND METHODS

The acute and chronic effects of JJ stent placement were studied in 24 canine renal units. Intrarenal and intraureteric pressures and motility were measured, in addition to transit times for complete passage of synthetic calculi from the upper ureter into the bladder.

RESULTS

Acute effects included raised renal intrapelvic pressure, reduced pelvic and ureteric motility and delayed calculus transit time. Prolonged JJ stent placement was associated with return of intrapelvic pressure to normal but persistent changes in both renal and ureteric motility and also calculus transit time.

CONCLUSION

In situ JJ stents impair upper urinary tract motility and experimental calculus transit time and may delay passage of ureteric calculi or calculus fragments following extracorporeal shock wave lithotripsy.

Retrospective registration of PET and MR brain images: an algorithm and its stereotactic validation

OBJECTIVE

We present a validation study of an algorithm for retrospective registration of PET and MR brain images.

MATERIALS AND METHODS

This algorithm involves two steps. In the first step, the two volumes are reformatted by aligning their interhemispheric fissure planes (midsagittal plane). In the second step, the corresponding planes parallel to the midsagittal plane are further aligned in the reformatted volumes to produce a 3D rigid body registration of the two original volumes. It is an efficient algorithm because both steps are performed in 2D spaces, and in each step only a small number of landmarks are required. A user-friendly system has been implemented to facilitate easy and fast processing of registration and reformatting of image volumes. The accuracy of this algorithm is validated using clinical scans of neurosurgical patients with a stereotaxic frame attached to their skull. The frame-based stereotaxic system provides an effective method for transforming image coordinates from different image volumes into a common coordinate system. This common coordinate system is used for assessing the spatial correspondence of each pixel in the registered image volumes. Validation using the stereotaxic image volumes enables objective estimation of retrospective registration accuracy.

RESULTS

Analysis of 11 MR/PET image pairs indicates that our registration method not only is efficient but also provides adequate accuracy for most clinical evaluation of PET studies.

CONCLUSION

We have implemented and validated an efficient algorithm for retrospective registration of PET and MR brain images.

Radiotracer measurement of ureteric blood flow

This paper describes a novel technique using the blood flow tracer C14-iodoantipyrine to measure ureteric blood flow in anesthetized Sprague-Dawley rats. The ureters were divided into five equal segments, and the blood flow was measured using a modification of the Fick principle. There was a gradient down the ureter with a significant difference between upper (159 ml./100 gm./min.) and lower (83 ml./100 gm./min.) ureteric segmental blood flows. This technique may allow the role of ureteric ischemia to be investigated in a variety of disease states.

Proliferating cell nuclear antigen: a new prognostic indicator in renal cell carcinoma

Renal cell carcinoma is a tumor, the prognosis and behavior of which remain poorly understood. Proliferating cell nuclear antigen levels have been shown to act as an independent prognostic variable in a variety of malignancies. Proliferating cell nuclear antigen was evaluated in 59 cases of renal cell carcinoma, and the results were correlated with existing clinicopathological variables and survival. Proliferating cell nuclear antigen index (percentage of tumor cells positive for proliferating cell nuclear antigen) did not correlate with stage, grade or ploidy. To assess survival, tumors with proliferating cell nuclear antigen indexes of greater than and less than 60% were compared. The 24 patients with a high index (greater than 60%) had a significantly worse survival than did 35 with a low index (less than 60%, p < 0.001). Therefore, the prognostic potential of proliferating cell nuclear antigen in renal cell carcinoma is promising and may be of clinical value in the management of patients with renal cell carcinoma.

Pulse Oximetry in the Diagnosis of Non-Critical Peripheral Vascular Insufficiency

Pulse oximetry was used to detect return of pulsatile flow in 27 subjects during reactive hyperaemia following 3 min of total limb ischaemia induced by above knee tourniquet occlusion. Fourteen patients with exercise induced leg pain had 18 symptomatic limbs tested. Thirteen controls had 25 limbs tested. Return of pulsatile flow during reactive hyperaemia occurred within 20 s of tourniquet release in the 25 control limbs which was then regarded as normal. The mean time for return of pulsatile flow in 18 symptomatic limbs was 53±37 s ( P > 0.05 versus controls). Three limbs had a normal value, two of which did not have peripheral vascular disease. Pulse oximetry correctly identified all 25 asymptomatic limbs and 15 of 16 patients with claudication secondary to peripheral vascular disease (PVD). This modification of the reactive hyperaemia test using the pulse oximeter is simple and quick to perform. It has potential as a non-invasive screening test for PVD, suitable for outpatient assessment.

Serum myoglobin does not predict cardiac allograft rejection

Noninvasive studies are useful, but limited, in detecting rejection among cardiac allograft recipients. Because an elevated serum myoglobin level is a sensitive indicator of necrosis in acute myocardial infarction, we postulated that myoglobin levels might correlate with the presence, absence, or degree of rejection. Therefore we prospectively measured serum myoglobin levels at the time of endomyocardial biopsy in 45 heart transplant recipients and correlated these levels with biopsy scores (grade 0 through grade 4). There was no significant difference in mean myoglobin levels among patients with grade 0 biopsy scores and those with grade 1 through grade 4 scores. Serial myoglobin levels and endomyocardial biopsy specimens were obtained in five patients during a 4- to 9-week period; no significant directional change in myoglobin levels appeared to correlate with changes in endomyocardial biopsy score. In addition, a normal myoglobin level did not exclude, nor did an elevated level confirm, any grade of rejection. We conclude that neither the absolute level nor a directional change in serum myoglobin is useful in identifying rejection among heart transplant recipients.

Stereotactic cytology in a regional breast-screening programme

Stereotactic localization and fine-needle aspiration are new procedures for the management of non-palpable mammographic abnormalities. In this prospective study, stereotactically guided cytology with immediate reporting was performed before biopsy in a consecutive series of 166 patients with screen-detected non-palpable abnormalities. All specimens were obtained by multiple stereotactically guided passes with a 22-G Franzén needle and graded as: 1, acellular or inadequate; 2, benign; 3, atypical, probably benign; 4, probably malignant; or 5, malignant. After definitive surgery all tumours were staged according to the Union Internacional Contra la Cancrum classification. Of 71 patients with malignancy, 56 were correctly diagnosed by cytology before operation. Twelve patients with malignancy had grade 1 cytology and 50 of the 52 with grade 2 cytology had benign disease. This study confirms that stereotactic cytology is a valuable diagnostic test in a breast-screening programme.

Effects of balloon dilatation on canine ureteric physiology

The concept of adynamic ureteric obstruction following balloon dilatation was explored in 12 female mongrel dogs. Upper ureteric segments were dilated to 15 french at 10 atm for 3 min. Pressure and motility in the dilated segments were compared to that proximal and distal to the dilated segment prior to, immediately after, and at 2 and 6 weeks after dilatation. Immediately after dilatation the dilated segment and proximal pelvi-ureter showed a rise in baseline pressure from 2.5 +/- 0.3 and 1.9 +/- 0.3 to 32 +/- 4.6 and 37.2 +/- 5.7 mm Hg, with an associated decrease in the amplitude of contractions. Distal ureteric pressure/motility was unaffected at this point. At 2 weeks, the motility of the pelvis, dilated segment and distal ureter was diminished. Nephrostograms showed hydronephrosis and dilated upper ureteric segments with extravasation in 2 animals. At 6 weeks there was residual dilatation but motility of the dilated segment, and that of the proximal pelvi-ureter and distal ureter had returned to normal.

Pancreatic atrophy: a new model using serial intra-peritoneal injections of L-arginine

No simple rat model for chronic pancreatitis exists at present. A single dose of arginine has recently been shown to induce acute pancreatitis in rats. This study was designed to assess whether serial injections of arginine would induce reproducible chronic pancreatic damage. Forty rats received an intra-peritoneal injection of 500 mg per 100 g body weight of L-arginine followed by three injections of 250 mg per 100 g over 10 days. The rats were killed 24 h after each injection and at intervals of up to 6 months. Serum amylase levels were increased in the acute phase only. Examination of the pancreas at 24 h showed a severe oedematous pancreatitis. By day 5 there was up to 90% acinar destruction with adipose tissue replacement, although ductal, vascular, and islet cells appeared undamaged. These changes were present 6 months after injection. This is proposed as a new, simple, and reproducible method of inducing chronic pancreatic damage in the rat.

Interleukin-1 dysregulation is an intrinsic defect in macrophages from MRL autoimmune-prone mice

Macrophages (M phi) from pre-diseased autoimmune-prone MRL mice (both MRL/+ and MRL/lpr) dramatically underproduce the cytokine interleukin-1 (IL-1) in comparison to M phi from a number of normal strains. In this study we show that IL-1 dysregulation by MRL M phi is fully expressed at birth, and that this defect does not change with time or the development of disease. We also constructed adult irradiation chimeras (consisting of A/J-->MRL and MRL-->A/J mice), and show that M phi isolated from these chimeras display a pattern of IL-1 production indistinguishable from that of the donor strain controls. Moreover, when we constructed a mixed chimera (A/J + MRL-->A/J, the A/J and MRL M phi coexisting within the same animal retained their individual patterns of IL-1 production when isolated by negative selection. Taken together, these results provide the first substantive evidence for an intrinsic defect (IL-1 dysregulation) in M phi from MRL autoimmune-prone mice.

Recovery of ureteric motility following complete and partial ureteric obstruction

Complete and partial ureteric obstruction was created in 2 groups of 10 mongrel dogs by placing a ligature around, or inserting a fine bore plastic stent into, the lower end of the left ureter (Groups 1 and 2). After 4 weeks the ligature or stent was removed, a 2.5-cm segment of ureter was harvested for in vitro analysis and the ureter reimplanted into the bladder. Pelvic and ureteric pressures and motility were recorded before, during and after the period of obstruction via a subcutaneously placed nephrostomy tube. Pre-obstruction resting intra-ureteric pressure was 2.1 +/- 0.3 mm Hg (mean +/- SEM), with regular contractions 8.9 +/- 0.7/min of 36.2 +/- 1.2 mm Hg amplitude. After 4 weeks of obstruction, contractility was abolished in Group 1 but increased in Group 2, 71.5 +/- 3.3 mm Hg, with irregular multiphasic contractions seen following diuresis. Intra-ureteric pressure was 16.3 + 1.2 mm Hg in Group 1 and 9.3 + 1.2 mm Hg in Group 2. In vitro experiments confirmed the patterns of contractility seen in vivo. Eight weeks after reimplantation the ureter returned to normal rhythm and rate in Group 1, but increased contractility persisted both in vivo and in vitro in Group 2.