Endovascular stents and stent-grafts: is heparin coating desirable?

Heparins are glycosaminoglycans that, in addition to their anticoagulant activity, have interactions with growth factors and other glycoproteins. These interactions may stimulate neointimal hyperplasia when heparin is delivered locally on stents and stent-grafts. Modifying the structure of heparin to retain anticoagulant activity while minimizing these stimulatory effects on the vascular endothelium is desirable and may be achieved by understanding the relationships between the structure and function of the various parts of the heparin molecule.

Design and use of internal receiver coils for magnetic resonance imaging.

This review describes coils for MRI that are inserted into the body through natural orifices. It covers the design and implementation of small internal receiver coils for use in the pelvis and gastrointestinal tract. Normal anatomy delineated by the high resolution obtained by using these coils and the appearances in a number of disease states for each clinical application are described.

Use of vector volume manometry and endoanal magnetic resonance imaging in the adult female for assessment of anal sphincter dysfunction.

Purpose: This study compared conventional water-perfused and vector volume anal manometry in female patients with neurogenic fecal incontinence and chronic anal fissure and in healthy female volunteers. We used endoanal magnetic resonance (MR) imaging to measure internal and external sphincter lengths and thicknesses and contrasted these with the manometric findings in the different anorectal conditions.

Methods: One hundred thirty-three female subjects were studied over an eight-month period, including 33 control volunteers, 83 patients with neurogenic fecal incontinence, and 17 patients with chronic anal fissure.

Pre-polarized saline: an in vivo feasibility study of a potential contrast agent.

The potential for using pre-polarized liquids as contrast agents in vivo is investigated and the feasibility of the method demonstrated. In this study we show the enhancement obtained following intravenous delivery of pre-polarized saline into the antecubital vein of a volunteer. This form of contrast agent provides signal gain on time scales commensurate with its T(1) and allows repeated doses to be administered, thus making alternate acquisitions of data with and without enhancement practicable.

Transanal MR imaging after repair of anorectal anomalies in children: appearances in pull-through versus posterior sagittal reconstructions.

Objective: Our objective was to use transanal MR imaging to compare the anatomic appearance of the components of the anal sphincter and the pattern of scarring after a pull-through perineoplasty versus a posterior sagittal anorectoplasty.

Subjects And Methods: Sixteen children ranging in age from 10 months to 15 years (mean, 10 years) were imaged using transanal receiver coils appropriate to the size of the child. Five had low, four intermediate, and seven high anomalies.

High-resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal receiver coil.

The use of a surface coil in MR imaging improves signal-to-noise ratio of adjacent tissues of interest. We therefore devised an endoanal receiver coil for imaging the anal sphincter. The probe is solid and re-usable: it comprises a saddle geometry receiver with integral tuning, matching and decoupling.

Hepatic steatosis as a potential risk factor for major hepatic resection.

Hepatic steatosis is a recognized risk factor for primary nonfunction of hepatic allografts, but the effect of steatosis on postoperative recovery after major liver resection is unknown. Our aim was to determine if hepatic steatosis is associated with increased perioperative morbidity and mortality in patients undergoing major resection. A retrospective review of medical records of 135 patients who had undergone major hepatic resection from 1990 to 1993 was performed.

Integrated and interactive position tracking and imaging of interventional tools and internal devices using small fiducial receiver coils.

A method is described of tracking the position of a rigid device within an MR scanner and imaging with the image slice position determined by the current position of the device, such that the manipulation of the device can be achieved in a robust, interactive manner. The device can be either external or internal to the patient. The position tracking is performed by means of two or three small MR receiver coils attached to individual receiver channels.

Fecal incontinence in scleroderma: assessment of the anal sphincter with thin-section endoanal MR imaging.

Purpose: To compare the magnetic resonance (MR) imaging appearance of the anal sphincter in patients with fecal incontinence and scleroderma with that in patients with fecal incontinence alone, scleroderma alone, or neither.

Materials And Methods: The study population comprised 14 patients with fecal incontinence and scleroderma, four with scleroderma alone, 13 with incontinence alone, and six with neither. T1- and T2-weighted spin-echo, magnetization transfer contrast-weighted, and dynamic gadolinium-enhanced images were obtained and analyzed for the integrity, thickness, and length of sphincter components.

Value of magnetic resonance imaging with an endovaginal receiver coil in the pre-operative assessment of Stage I and IIa cervical neoplasia.

Objective: To assess the value of high resolution endovaginal magnetic resonance images (MRI) of the uterine cervix in planning management of early cervical cancer.

Design: Prospective cross-sectional study.

Setting: Specialist gynaecological oncology unit of a postgraduate teaching hospital.

MRI of fistula-in-ano: a comparison of endoanal coil with external phased array coil techniques.

Purpose: The objective of our study was to compare MRI of fistulas-in-ano using an endoanal coil with that using a pelvic phased array coil and to assess the value of a combined approach by correlating the findings with those at surgery.

Method: Twenty consecutive patients with clinical suspicion of perianal sepsis were studied using an endoanal coil immediately followed by a phased array coil. T1 weighted and STIR images in transverse and coronal planes were made with each coil and analysed by noting the presence and site of a collection and primary track, the position of any internal opening, and subcutaneous or supralevator extension.

High-resolution MR imaging of the anal sphincter in children: a pilot study using endoanal receiver coils.

Objective: The purpose of this study was to obtain high-resolution MR images of the various components of the anal sphincter complex in children who have anorectal disorders. We therefore used dedicated endoanal receiver coils for MR imaging.

Conclusion: Our pilot study suggested that MR imaging that uses a dedicated endoanal coil may have considerable diagnostic potential in children who have anorectal disorders.

MR imaging of the anal sphincter in multiparous women using an endoanal coil: correlation with in vitro anatomy and appearances in fecal incontinence.

Objective: The aim of this study was to correlate the components of the normal female anal sphincter seen on high-resolution MR images with the in vitro anatomy and to describe the change in appearances of these components in multiparous women with fecal incontinence.

Subjects And Methods: Ten asymptomatic female volunteers (32-72 years old; mean, 54 years old) and 22 women with fecal incontinence were studied. In six patients (26-68 years old; mean, 49 years old) fecal incontinence began immediately after childbirth; in the remaining 16 patients (45-77 years old; mean, 58 years old) fecal incontinence developed 15- 30 years after childbirth.

The effects of detubularization and outflow competence in substitution cystoplasty.

Objective: To assess the effects of detubularization and outflow competence on the clinical and urodynamic results of patients undergoing substitution cystoplasty.

Patients And Methods: The study included 142 patients undergoing orthotopic substitution cystoplasty, of whom 85 underwent a 'straight' and 57 a detubularized substitution cystoplasty using the ileo-colonic segment. All were assessed clinically and by video-urodynamic studies before and after surgery.

Laser ablation of the endometrium: MR appearance during and after treatment and the relation of MR appearance to clinical outcome.

Objective: Our objective was to study the appearance of the uterus on MR images obtained during and 3 months after laser ablation of the endometrium and to determine if a correlation exists between the MR imaging findings and the subsequent clinical outcome. The appearance could then be used to guide the application of laser energy during the procedure to optimize the clinical result.

Subjects And Methods: Eight women 34-55 years old (mean, 42 years old) with symptoms of heavy, painful menses underwent laser ablation under epidural anesthesia.

A solid reusable endorectal receiver coil for magnetic resonance imaging of the prostate: design, use, and comparison with an inflatable endorectal coil.

We have designed a solid endorectal receiver coil for MRI of the prostate. The coil provided an improved signal-to-noise ratio up to 5 cm from its surface when compared with a standard pelvic phased array. This preliminary report describes 16 patients who were imaged using this coil, seven of whom had been examined previously with a balloon-design endorectal coil.

MR imaging and spectroscopy of the basal ganglia in chronic liver disease: correlation of T1-weighted contrast measurements with abnormalities in proton and phosphorus-31 MR spectra.

The purpose of this study was to correlate the hyperintensity in the globus pallidus seen on T1-weighted magnetic resonance imaging (MRI) of the brain in chronic liver disease with changes in metabolite ratios measured from both proton and phosphorus-31 magnetic resonance spectroscopy (MRS) localised to the basal ganglia. T1-weighted spin echo (T1WSE) images were obtained in 21 patients with biopsy-proven cirrhosis (nine Child's grade A, eight Child's grade B and four Child's grade C). Four subjects showed no evidence of neuropsychiatric impairment on clinical, psychometric and electrophysiological testing, four showed evidence of subclinical hepatic encephalopathy and 13 had overt hepatic encephalopathy.

High resolution magnetic resonance imaging of the anal sphincter using a dedicated endoanal coil. Comparison of magnetic resonance imaging with surgical findings.

Purpose: To obtain high resolution images of the anal sphincter and adjacent anorectum using an endoanal coil in patients with sepsis, trauma, and low rectal tumors and to compare imaging appearances with findings at time of surgery.

Patients And Methods: A cylindrical saddle geometry coil (diameter, 9 mm; length, 75 mm) was used to examine 30 patients (mean age, 53.6 years).

Magnetic resonance imaging guided breast biopsy using a frameless stereotactic technique.

The high sensitivity but poor specificity of contrast enhanced magnetic resonance (MR) imaging for delineating malignant breast lesions is increasing the demand for MR guide breast biopsy. However, the poor patient access offered by conventional MR systems makes such procedures extremely difficult. We describe a method of performing breast biopsy outside the bore of the magnet using the 3-D MR imaging data.

High-resolution MR imaging of stage I cervical neoplasia with a dedicated transvaginal coil: MR features and correlation of imaging and pathologic findings.

Objective: The purposes of this study were to assess the appearance of stage 1 neoplasia of the cervix by high-resolution MR imaging with an enveloping transvaginal receiver coil and to correlate the imaging findings with the pathologic findings.

Subjects And Methods: Fifteen patients (25-73 years old; mean, 40 years old) with clinical stage I disease were examined with a 37-mm-diameter ring-design solenoid receiver coil placed around the cervix. Axial 2.

The role of urodynamic studies in the evaluation of patients with augmentation cystoplasties.

Objective: To assess the role and value of videourodynamic studies (VUD) in the post-operative evaluation of 100 patients who were continent following augmentation (clam) enterocystoplasty.

Patients And Methods: Fifty patients had non-neuropathic detrusor instability and 50 had neuropathic bladder dysfunction. All underwent standard dual channel medium fill cystometry and synchronous video screening before and at 6 months and 2 years after a clam ileocystoplasty.