Intracranial circulation: preliminary clinical results with three- dimensional (volume) MR angiography

The authors assessed the clinical utility of a magnetic resonance angiography technique in the evaluation of intracranial circulation. Eighteen patients with a low likelihood of cerebrovascular disease (control group) and 40 patients with suspected cerebrovascular disease were imaged with a FISP (fast imaging with steady precession) sequence (repetition time of 50 msec, echo time of 15 msec, velocity compensation in the read and section-select directions with acceleration compensation in the read direction, 15 degrees anisotropic volume, and a 1.25-mm partition thickness). Ninety-four percent of images in the control group and 72% of images in the group with cerebrovascular disease were considered useful for diagnosis. This technique can provide accurate images of intracranial circulation and can be performed in conjunction with two-dimensional spin-echo or gradient-echo imaging. It was most useful in the evaluation of patent intracranial aneurysms, vessel displacement, and large-vessel occlusive disease. Disadvantages included limited field of view, persistent signal voids, limited spatial resolution, and inadequate depiction of lesions with slow flow.     

Carotid bifurcation: MR imaging. Work in progress

To devise and implement an in-plane magnetic resonance angiography examination of the carotid bifurcation capable of producing high-resolution images, the authors examined 19 normal carotid arteries and 14 patients with angiographically documented disease with two flow-correction techniques: a three-gradient, velocity-refocused technique with spin-echo (SE) and gradient-echo sequences, and a four-gradient velocity- and acceleration-corrected SE technique. With use of three equal gradients in the read direction, velocity-related phase changes were minimized by placing the dephasing gradient after the 180 degree pulse and near the read gradient. Acceleration effects were minimized through the use of short echo times and cardiac gating. Both velocity- and acceleration-produced phase changes were corrected with the four-gradient scheme but at the expense of some limitations in spatial resolution. Both techniques consistently produced satisfactory images of the carotid bifurcation in healthy individuals. However, the results indicate that the present gradient-phase modulation techniques have several drawbacks, including susceptibility to patient motion, overlapping with the jugular vein, and inability to image carotid stenosis accurately due to turbulence.     

A MULTICENTRE STUDY OF THE SAFETY AND EFFICACY OF AMLODIPINE IN MILD TO MODERATE HYPERTENSION

SUMMARY An open, non-comparative study of 10 weeks' duration was conducted in general practice to assess the safety of amlodipine in patients with mild to moderate hypertension. Of the 5352 patients entering the study, 5135 received amlodipine; 4621 patients (90%) with a mean age of 58.2 years completed the study. Normalisation of blood pressure was achieved in over 80% of patients with a mean reduction of 21/15 mmHg. The mean final dose of amlodipine was 6.8 mg/day. Adverse experiences possibly related to amlodipine were reported by 19.3% of patients, and overall adverse events led to withdrawal in 6.7% of patients. The most common reported side-effect was oedema. The frequency of headache was almost identical in older and younger patients and oedema, flushing and dizziness were seen only slightly more often in elderly patients. Ninety per cent of patients were considered by their GP to have shown excellent or good toleration of therapy. Over 85% of patients elected to continue on amlodipine therapy after completion of the study.     

Treatment of dextran sulfate sodium-induced murine colitis by intracolonic cyclosporin

The use of oral and intravenous cyclosporin represents a significant advance in the therapy of refractory inflammatory bowel diseases (IBD). However, oral administration of cyclosporin is fraught with improper delivery of cyclosporin to the colon for its topical action. Because of unpredictable metabolism by cytochrome P-450 IIIA, the targeted blood level for systemic effect is not reached at low doses. Furthermore, the doses that have been used for therapy of IBD have been shown to induce several adverse side effects. Thus, an alternate method of delivering cyclosporin to the colon is desirable. In this study, the effect of intracolonically administered cyclosporin was tested for its efficacy to heal mucosal erosions in dextran sulfate sodium (DSS)-induced colitis in mice. Both acute and chronic colitis was induced by feeding female Swiss-Webster mice with 5% DSS (30,000–40,000 mol wt) for five or seven days, respectively. Therapy was advocated prophylactically, prophylaxis plus therapy and therapeutically during the acute and chronic phase of the disease and therapeutically during the chronic phase of the disease. Intracolonic cyclosporin given prophylactically showed adverse effects by increasing the damage to the colonic mucosa. However, intracolonic cyclosporin given therapeutically in 2.5, 5, and 10 mg/kg after the induction of colitis resulted in dramatic responses in terms of reducing the disease activity and histologic scores, corroborated by complete histological resolution compared to oral cyclosporin given at identical doses. Intracolonic cyclosporin (5 mg/kg) was also very effective in reducing the chronic inflammation. The results of this study highlight the application of this animal model for therapeutic research. Furthermore, cyclosporin administered as an enema provides a new stratagem for the therapy of IBD because of its rapid onset of action at very low doses without the risk inherent in oral or systemic administration.     

Positron emission tomographic measurement of bone marrow blood flow to the pelvis and lumbar vertebrae in young normal adults [published erratum appears in Blood 1994 Nov 15;84(10):3602]

Ten young normal adults had pelvic and lumbar vertebral body bone marrow blood flow examined using [15O]water and positron emission tomography (PET) in a study designed to assess the feasibility and reproducibility of the PET technique for measuring marrow blood flow to various marrow regions. The procedure was well tolerated. Repeated blood flow measurements obtained from two consecutive [15O]water exams on each individual subject were highly reproducible. In addition, there was minimal variation in marrow blood flow from individual to individual and no gender differences were noted. In contrast, mean +/- SD bone marrow blood flows (expressed as milliliters per minute per 100 g) at selected anatomical sites were significantly different and were as follows: lower lumbar vertebral bodies, 17.6 +/- 3.1; most posterior and superior pelvis (conventional site of percutaneous bone marrow biopsy), 14.3 +/- 3.1; and total superior pelvis, 11.1 +/- 2.0. We conclude that PET is a relatively noninvasive, simple, and reproducible technique for measuring bone marrow blood flow. Marrow blood flow is consistent between normal young subjects, but varies significantly between different anatomic regions of the marrow.     

Idiopathic megarectum in adults

Outlet obstruction is thought to be one of the major factors responsible for idiopathic constipation. However, outlet obstruction itself may be due to several mechanisms. Among these, the presence of a megarectum is a leading one. Pathophysiological studies in adult patients with idiopathic megarectum are scarce. We studied by manometric and defecographic means 15 adult subjects with idiopathic megarectum and severe chronic constipation. Twenty-five healthy volunteers of both sexes acted as controls. Manometric variables showed significant differences between patients and controls with respect to internal anal sphincter pressure (P=0.02), minimum relaxation volume (P<0.001), defecatory sensory threshold (P<0.001), mean rectal tolerable volume (P<0.001), and rectal compliance (P<0.001). An altered response to straining was observed in 46.6% of patients and in 12% of controls (P=0.04); the ability to expel a 50-ml balloon per anum was 13.3% in patients and 100% in controls (P<0.001). Although all patients opened the anorectal angle and had descent of the pelvic floor, thereby confirming an adequate expulsion effort, evacuation of contrast material appeared extremely difficult. In fact, no subject was able to expel more than 30% of the rectal contents during fluoroscopic screening. These results confirm previous hypotheses that idiopathic megarectum displays features of a neuropathic process as an underlying mechanism. Further studies are needed that also take into consideration the muscle tone component of the rectum in these patients.     

Intravenous digital subtraction angiography of the intracranial veins and dural sinuses

When combined with computed tomography, IV DSA is usually of sufficient quality to replace conventional angiography in most patients with abnormalities of the larger intracranial veins and sinuses. Preoperatively, IV DSA can be used to evaluate normal anatomic variations of venous outflow to determine what sinuses can be safely occluded if necessary in the region of the temporal bone, jugular fossa, and base of the skull. Patients with glomus jugular tumors and carotid-cavernous fistulas also need conventional angiograms to define the feeding vessels of these lesions for obliteration by embolization or surgery.