PubMed Health⌕ Search

Biomedical subjects

M Crofton

Publications and source records attributed to M Crofton.

13 recordsLinked to original sources
PubMed1997

Duplex scanning in the postoperative surveillance of patients undergoing total hip arthroplasty.

Color flow duplex imaging is a well-established method for the diagnosis of deep vein thrombosis in symptomatic patients; however, the sensitivity and specificity of duplex scanning compared with venography in high-risk asymptomatic patients are not known. Consecutive patients undergoing total hip arthroplasty who consented to have bilateral venography on days 8 to 12 were included in this prospective study. One hundred and fifty-one venograms were finally obtained in 78 patients. All duplex scanning was performed with the Ultramark 9 ATL (Advanced Technology Laboratories) by one investigator. In the beginning of the study, the first 44 legs, only the femoropopliteal segment was tested and the result was based on B-mode compression; the sensitivity for the duplex was 56% (5/9), and the specificity, 94% (33/35). In the next 107 legs, the addition of color to our criteria improved the sensitivity of the duplex scan from 55% to 93% (13/14) for the femoropopliteal segment and the specificity from 94% to 99% (92/93). For the calf segment, in the same 107 legs, using the color facility of the duplex, the sensitivity and specificity were 79% (15/19) and 97% (85/88), respectively. The color facility of new-generation machines makes duplex scanning reliable for the detection of proximal deep vein thrombosis, even in asymptomatic high-risk patients. For the detection of calf deep vein thrombosis, however, more experience is needed. A larger study is necessary to confirm these preliminary data.

Aged↗
PubMed1997

Training phantom for ultrasound guided biopsy.

Commercial phantoms designed for radiologists to practise the skills needed to biopsy lesions under ultrasound guidance can be prohibitively costly, and do not have an indefinite shelf-life. A gelatin-based in-house model has been developed to recreate the conditions found in human tissues, using materials which are cheap and in everyday use. This phantom remains useful for several weeks, although tears produced by the biopsy needle take progressively longer to bond when the reconstructed gelatin is older than a month. However, new phantoms can be built quickly and easily using fresh gelatin while recycling other components.

Biopsy, Needle↗
PubMed1994

Ultrasound scanning of the acute abdomen by surgeons in training.

Ultrasound is widely used in the investigation of abdominal symptoms. Its increasing popularity may lead to pressure on radiological services, diagnostic delay and prolonged hospital stay. Immediate imaging performed by radiologists can contribute useful information in acute emergencies. This study assessed the accuracy and value of abdominal ultrasonography when carried out by admitting surgeons. Three surgical registrars were first instructed for two half days by a consultant radiologist. Patients with acute symptoms were scanned at the time of initial presentation using an Aloka SSD-620 scanner with 3.5 and 5 MHz probes. A total of 205 scans was performed--124 of the upper and 81 of the lower abdomen. Immediate ultrasound provided information that contributed to the establishment or refutal of a diagnosis in 138 patients (67.3%), predominantly by confirming or excluding hepatobiliary disease, tubo-ovarian pathology or aortic aneurysms and in blunt abdominal trauma. The diagnosis was altered in a small proportion (7.8%). Scanning proved unhelpful in 62 patients and misleading in five. Findings concurred with those of a radiologist in 86% of the 139 patients subsequently scanned. Abdominal ultrasound is a useful tool in the hands of surgeons dealing with emergencies and may occasionally provide vital information. If access to radiological facilities is delayed, ultrasound by the admitting surgeon could lead to improved patient management and cost savings.

Abdomen, Acute↗
PubMed1993

Combined percutaneous transhepatic and endoscopic placement of biliary stents.

Combined percutaneous transhepatic cholangiography and endoscopic retrograde cholangiography can be used to stent biliary obstruction when attempts at endoscopic stenting have failed. Between January 1987 and August 1991 we performed 35 combined procedures in 31 patients with malignant obstruction. Post stenting serum bilirubin and serum alkaline phosphatase concentration fell after 33 and 29 procedures, respectively. In six studies there was evidence of infection prior to stenting. In spite of the use of prophylactic antibiotics, septic complications developed after eight procedures (23%). Pseudomonas was the most commonly isolated pathogen (46%). Twenty-three patients were discharged, 30-day mortality was 8 (23%) and median survival was 14 weeks (range 0-75 weeks). Seven patients required eight stent changes because of blockage (median patency time 18 weeks; range 7-75 weeks). Use of this technique allows relief of biliary obstruction. Potential infective and bleeding complications must be anticipated.

Aged↗
PubMed1992

Colour flow imaging in the detection of femoro-distal graft and native artery stenosis: improved criteria.

Vein graft or native artery stenosis after femoro-distal revascularisation is a common cause of graft occlusion. The early detection and treatment of such stenoses offers the potential for better graft patency than salvage procedures undertaken for graft thrombosis. In the past, two criteria using duplex scanning have been used to detect grafts at risk: (a) a localised increase in the peak velocity (V2) by 100% or more in comparison to the peak velocity (V1) 2 cm upstream (i.e. V2/V1 ratio greater than 2.0), and (b) a decrease in average peak velocity to less than 45 cm s-1. Seventy-four consecutive patients with femoro-distal vein grafts have been studied with intravenous digital subtraction angiography to detect stenosis (greater than 50% diameter) and colour flow imaging using both duplex scanning criteria (a) and (b) at 1.5, 3, 6, 9 and 12 months after operation. The results show that the V2:V1 ratio greater than criterion had a sensitivity of 100% and a specificity of 83%. Stenoses in the native distal arteries were not detected. Low average peak velocity less than 45 cm s-1 had a sensitivity of 61% and a specificity of 98%. By combining both criteria the sensitivity for detecting stenoses in both the vein graft and native distal artery, became 100% and the specificity 98%.

Angiography, Digital Subtraction↗
PubMed1991

Impact of duplex scanning on vascular surgical practice.

This review outlines the development of duplex scanning over the past 15 years and its value not only in vascular medicine and surgery but also in the field of transplantation and obstetrics. It is now the first line of investigation of patients with symptomatic carotid bifurcation disease and those with clinically suspected acute deep venous thrombosis. It is also an established method of femoropopliteal and femorodistal arterial graft surveillance, determination of the extent and cause of chronic venous insufficiency, detection of placental insufficiency and portasystemic shunt patency, early transplant monitoring, as well as of detecting an arterial stenosis suitable for angioplasty. In addition, it is developing into the method of choice for the initial investigation of patients with suspected mesenteric or renal artery stenosis. The accuracy of duplex scanning, avoiding further unnecessary invasive and expensive diagnostic procedures, makes it one of the most cost-effective investigations ever introduced into clinical practice. Also, when used as a screening technique in arterial and venous disease, it selects those patients who need more invasive procedures such as angiography. This helps to reduce waiting lists of patients requiring investigation, and better directs limited resources to treatment rather than investigation.

Aorta↗