Agreement between computed tomography and ultrasound on abdominal aortic aneurysms and implications on clinical decisions

OBJECTIVES

The United Kingdom abdominal aortic aneurysm (AAA) screening programme refers aneurysms with ultrasound (US) diameters of ≥5.5 cm to vascular services for consideration of computed tomography (CT) and intervention. We investigated the discrepancy between US and CT, implications on clinical decisions and question at which stage CT be used.

DESIGN/METHODS

AAA USs over 5 years were retrospectively analysed. Patients included had aneurysms measuring ≥5 cm on US with subsequent CT within 2 months (n = 123). Based on maximum US diameters, 44 patients had aneurysms between 5 and 5.4 cm (group I) and 79 patients ≥5.5 cm (group II). Results were cross-referenced. Correlation and limits of agreement were calculated. Two radiologists re-measured 44 pairs of CT/US scans and the inter-observer bias in determining discrepancies between imaging modalities calculated.

RESULTS

Mean difference between imaging modalities was 0.21 cm (±0.39 cm, p < 0.001). Limits of agreement were -0.55 to 0.96 cm, exceeding clinical acceptability. Mean difference was higher and significant in group I (0.39 cm, p < 0.001) compared to group II (0.10 cm, p > 0.05). Seventy-percent of group I patients had CT scans revealing diameters of ≥5.5 cm. Inter-observer bias was not significant.

CONCLUSION

Significant differences between imaging modalities, more in US diameters of below 5.5 cm, exist. We recommend AAAs measuring ≥5 cm on US should undergo earlier referral to a vascular service and CT.

Long term follow-up of transcatheter coil embolotherapy for major colonic haemorrhage

AIM

Therapeutic angiography with embolization is fast becoming the preferred treatment modality for major bleeding in the lower gastrointestinal (LGI) tract. The aim of this study was to determine the long term outcome and complications of percutaneous coil embolization (PCE) and its efficacy as definitive therapy in patients with major LGI bleeding.

METHODS

All patients presenting to our institution with a haemodynamically significant LGI tract bleed between 1995 and 2001 that were unresponsive to conservative measures were considered for emergency angiography and coil embolization where appropriate. The outcome of these individuals was determined by case note review and telephone interview.

RESULTS

There were 20 patients (11 females) with a mean follow-up period 72 months, mean age was 67 years. All underwent PCE following positive angiogram. The most common site of bleeding was the right colon (40%); haemostasis was successfully achieved in 16 (80%) patients. Five of the 20 patients died within 30 days of the intervention, three following PCE and two following surgery. None of the mortality following PCE was considered procedure related. On long term follow-up four patients required readmission to hospital for further LGI bleeds at 1, 2, 12 and 16 months respectively. Ischaemic complications occurred in 23%.

CONCLUSION

Superselective embolization as the primary technique for the treatment of haemodynamically significant LGI bleeding is an effective, feasible and safe technique. Long term follow-up in our series up to 72 months has shown that it should be considered as both a primary and potentially definitive treatment for life threatening LGI bleeds.

Strategies for the Management of SVC Stent Migration into the Right Atrium

PURPOSE

Stent migration into the right atrium is a potentially fatal complication of stenting in the venous system and is most likely to occur during the treatment of superior vena cava obstruction. Endovascular approaches that can salvage this hazardous situation are described and the keys to successful treatment are highlighted.

MATERIALS AND METHODS

Four different strategies are reviewed: (1) snaring the stent directly, (2) angioplasty balloon-assisted snaring of the stent, (3) guide wire-assisted snaring of the stent, and (4) superior vena cava-to-inferior vena cava bridging stent.

RESULTS

These techniques have been employed in the successful management of four cases. No short- or long-term complications as a result of these maneuvers have been identified. Additional treatment of the underlying disease was possible at the same time in each case.

CONCLUSION

We conclude that prompt management of right atrial stent migration is essential and can be successfully achieved by a variety of "bale-out" techniques which are within the technical range of most interventional radiologists.

Endovascular embolization of visceral artery aneurysms with ethylene-vinyl alcohol (Onyx): a case series

We report the application of the liquid embolic agent ethylene-vinyl alcohol (Onyx; MicroTherapeutics, Irvine, CA, USA) in the management of visceral artery aneurysms. The technique and indications for using Onyx are discussed with emphasis on the management of wide-necked aneurysms and maintenance of patency of the parent vessel. None of the cases was considered suitable for stent-grafting or embolization with conventional agents. Two aneurysms of the renal artery bifurcation and one aneurysm of the inferior pancreaticoduodenal artery were treated. Following treatment there was complete exclusion of all aneurysms. There was no evidence of end-organ infarction. Follow-up with intervals up to 6 months has shown sustained aneurysm exclusion. Onyx is known to be effective in the management of intracranial aneurysms. Our experience demonstrates the efficacy and applicability of the use of Onyx in the treatment of complex visceral artery aneurysms.

Cryoplasty for Arterial Restenosis

OBJECTIVE

A prospective follow-up study of patients with arterial restenosis undergoing cryoplasty.

MATERIALS & METHODS

Between May 2004 and June 2005, 10 patients with restenosis following ilio-femoral endovascular treatment underwent twelve cryoplasty procedures. All patients had had at least one previous episode of stenosis treated by conventional endovascular methods and had suffered further restenosis. The indications for treatment were grafts at risk (n=5) and symptomatic in-stent restenosis (n=5). Two patients underwent re-cryoplasty. Cryoplasty was performed in accordance with manufacturer's instructions using 6-8mm balloons. All patients had Doppler ultrasound evaluation at 1, 3, 6 and 12 months.

RESULTS

All procedures had angiographically successful immediate outcome with <30% residual stenosis. Non flow limiting dissection was evident in two cases. In six procedures (50%), restenosis was evident within 6 months post-procedure, whilst in the other six, there was progressive restenosis appearing between 6-12 months. Five cryoplasty procedures have needed endovascular re-intervention due to symptomatic high-grade restenosis and a sixth is awaiting surgery.

CONCLUSION

Cryoplasty is of no value in patients with restenosis in the iliofemoral segment with half the procedures failing within six months and all of them within the first year. Evidence to support the use of cryoplasty in the peripheral arterial restenotic lesions is lacking.

"Whatever happened to the class of 2000?" An outcome survey of potential interventional radiologists

OBJECTIVES

To find out what final career choices were made by trainee doctors who had indicated a strong interest in pursuing a career in interventional radiology and to establish the reasons behind their final career choice.

METHODS

Eighty-eight doctors who attended a meeting in 2000 designed to promote interventional radiology as a career were questioned as to whether the meeting influenced their potential career choices and then further surveyed via postal questionnaire 5 years later to find out their eventual career choices. Of the 88 doctors who attended, 56 were radiology trainees and 32 were training in either medical or surgical specialties. There were 25 women and 63 men.

RESULTS

Five years after the meeting, six are now interventional radiologists (6.8%) though four of these are still in a 6th year interventional radiology fellowship. A further 12 (13.6%) are systems based, predominantly diagnostic radiologists with an interest in intervention. Thirty-two (43.2%) are diagnostic radiologists who undertake little or no therapeutic intervention. Of the 32 non-radiologists who attended the meeting only three entered radiology and are still in training.

CONCLUSIONS

Interventional radiology is a popular initial career choice amongst trainee doctors. However, only a small number eventually pursue the specialty. If the manpower shortage of interventional radiologists is to be addressed, there needs to be improvements in training, accreditation, career opportunities and working conditions.

Percutaneous thrombin injection for the treatment of a post-pancreatitis pseudoaneurysm

Visceral artery pseudoaneurysms are often treated surgically or by transcatheter embolisation. We report a case of a pseudoaneurysm in a patient with chronic pancreatitis, which was successfully occluded by percutaneous injection of thrombin into the pseudoaneurysmal sac as a first-line management.

Symptomatic malignant gastroesophageal anastomotic leak: management with covered metallic esophageal stents

OBJECTIVE

Gastroesophageal anastomotic leak after cancer resection has a mortality rate of up to 60% and significant morbidity, whatever the mode of treatment. We assessed the efficacy of esophageal stenting as a therapeutic option to reduce the mortality and morbidity associated with symptomatic intrathoracic anastomotic leakage.

SUBJECTS AND METHODS

During a 52-month period, 14 patients had placement of stents for clinically significant postoperative leaks: 10 patients had an esophagogastrectomy and four patients had a total gastrectomy with esophagojejunal anastomosis. Thirteen of 14 patients had tumors that were histologically staged as T3 N1 M0 or worse. Significant anastomotic leaks were revealed by a contrast-enhanced study at 3-28 days after surgery. Stents were inserted in patients in whom the leakage was debilitating or initial conservative treatment had failed. Stenting outcome in terms of clinical and radiologic healing, hospital stay, survival, and complications was assessed.

RESULTS

No procedural morbidity or 30-day mortality occurred. Immediate postprocedural leak occlusion was obtained in all patients. Clinical healing of the leak occurred in 13 (92.8%) of 14 patients, with a median healing time of 6 days. Of the 13 patients, healing occurred within 10 days in 10 patients (76.9%). Eight of these 10 early closures received a knitted nitinol stent (p = 0.02). One patient (7%) died as a consequence of leakage at 135 days. Median survival for all 14 patients was 11 months (Kaplan-Meier method). Complications included five episodes of food blockages in three patients, which required endoscopic clearance, and one case of stent-related upper gastrointestinal hemorrhage. No patients developed anastomotic stricture or occlusive epithelial hyperplasia.

CONCLUSION

Covered esophageal stenting appears to reduce the mortality and morbidity of symptomatic anastomotic leakage after surgery for gastroesophageal cancer. Knitted nitinol stents may be best suited to this purpose.

The clinical utility of spiral CT cholangiography

Spiral CT cholangiography has received little attention, yet in a single breath-hold spiral and with limited manipulation at the workstation it can yield high resolution images of the biliary tract. In addition it can clearly demonstrate periampullary detail and contribute some dynamic information regarding biliary excretion. The clinical utility of this technique is illustrated and discussed. Breen, D. J., Nicholson, A. A. (2000). Clinical Radiology55, 733-739.

Recurrent superior vena caval obstruction due to invasion by malignant thymoma: treatment using a stent-graft

A stent-graft was used to palliate superior vena caval obstruction in a 50-year-old patient with histologically proven ingrowth of malignant thymoma through three previously inserted non-covered stents. The stent-graft is still patent 12 months later. This is the first report of such a procedure where histological evidence of tumour ingrowth is available and long-term patency is verified.

Vascular imaging and intervention in peripheral arteries in the diabetic patient

Diabetic patients are four times more likely to develop peripheral vascular disease than the general population. This disease is likely to be more aggressive, with five times more patients developing critical limb ischaemia. Early diagnosis and treatment allows up to 80% of these patients to have some form of surgical or endovascular re-vascularisation. The primary imaging modalities to be used should be duplex ultrasound followed by angiography. Magnetic resonance angiography, however, holds out promise for the future as being a good method of non-invasive imaging. Endovascular (interventional radiological) procedures have a major role to play in treatment of vascular stenoses and occlusions. Thrombolytic agents can be used to dissolve thrombus within occluded vessels and so restore patency. Percutaneous transluminal angioplasty is of value in dilating the stenotic lesions within the vessels and so restoring normal blood flow. Endovascular stents may be inserted to ensure longer term patency. There is indirect evidence to suggest that the outcomes of endovascular procedures in the diabetic patient are less good than those in the general population, but nevertheless such procedures may save the diabetic patient from primary amputation and allow healing of ischaemic ulcers.

Long-term follow-Up of percutaneous balloon angioplasty in adult aortic coarctation

PURPOSE

To assess long-term outcomes following percutaneous transluminal angioplasty (PTA) of congenital aortic coarctation in adults.

METHODS

Seventeen patients underwent PTA for symptomatic adult coarctation of the aorta. Sixteen patients, with a mean age of 28 years (range 15-60 years), were reviewed at a mean interval after angioplasty of 7.3 years (range 1.5-11 years). Assessment included magnetic resonance imaging (MRI), Doppler echocardiography, and clinical examination. Current clinical measurements were compared with pre- and immediate post-angioplasty measurements.

RESULTS

At follow-up 16 patients were alive and well. The patient not included in follow-up had undergone surgical repair and excision of the coarctation segment following PTA. Mean brachial systolic blood pressure for the group decreased from 174 mmHg before angioplasty to 130 mmHg at follow-up (p = 0.0001). The mean gradient had fallen significantly from 50.9 to 17.8 at follow-up (p = 0.001). The average number of antihypertensive drugs required per patient decreased from 0.56 to 0.31 (p = 0.234). No significant residual stenoses or restenoses were seen at MRI. Small but clinically insignificant residual pressure gradients were recorded in all patients using Doppler echocardiography. Complications included one transient ischemic attack at 5 days, one external iliac dissection requiring stent insertion, and a further patient who developed a false aneurysm close to the coarctation site at 12 months which subsequently required surgical excision.

CONCLUSION

PTA of adult coarctation is safe and effective in the long term. Although primary stenting has recently been advocated in the treatment of this condition, our results suggest that PTA remains the treatment of choice.

Mechanical properties of metallic stents: how do these properties influence the choice of stent for specific lesions?

PURPOSE

To assess selected balloon-expandable and self-expanding stents for radial force, flexibility, radio-opacity, and trackability, and to relate these physical characteristics to potential indications for placement.

METHODS

Force-strain curves were plotted for each stent and the force required to produce 50% luminal narrowing was recorded. The ability of the stent to show elastic recoil following deformation was also noted. Flexibility was measured by bending the stents against a force transducer and recording the force required per degree of flexion. Radio-opacity was measured by comparing each stent against a standard aluminum step wedge. Trackability was measured by testing the ability of the stent on its delivery system to track over angles of 90 degrees and 60 degrees.

RESULTS

The balloon-expandable stents showed greater radial strength and radio-opacity but, apart from the AVE Iliac Bridge stent, showed poorer flexibility and trackability. The self-expanding stents showed less radial force but were able to re-expand following deformity. They were generally more flexible and had better trackability but lower radio-opacity.

CONCLUSION

There is no stent which exhibits all the ideal properties required and therefore the interventionist will need to keep a range of stents available if all lesions are to be addressed.

Long-term follow-up of the Bird's Nest IVC Filter

AIM

This study is a long-term clinical follow-up of the Bird's Nest Filter which addresses issues such as caval patency, filter integrity, morbidity and mortality.

MATERIALS AND METHODS

78 consecutive patients with Bird's Nest Filters inserted between 1989 and 1994 were recalled for clinical assessment and imaging follow-up. Pre- and post-filter medical histories were obtained from the patients and their medical records. They were examined for clinical signs of inferior vena cava occlusion. Imaging follow-up was by plain abdominal radiography, colour duplex ultrasound and computed tomography.

RESULTS

52 patients were alive and well at 4-6 years. Thirty-day mortality was 5.1%. Three-year mortality was 19.2%. Recurrent pulmonary embolus occurred in 1.3%. IVC occlusion was demonstrated in 4.7%. No evidence of filter migration was seen. Wire prolapse occurred in 70% on abdominal X-ray and asymptomatic performation of the caval wall in 85.3% on CT. Morbidity and mortality were the same whether the patient was anticoagulated or not.

CONCLUSION

The Bird's Nest Filter is safe and effective in both the short and long term.

Treatment of rectal hemorrhage by coil embolization

Four patients, aged 54-84 years, presenting with life-threatening rectal bleeding from the superior hemorrhoidal artery, underwent percutaneous fibered platinum coil embolization via coaxial catheters. Pre-procedure sigmoidoscopy had failed to identify the source of hemorrhage, because the rectum was filled with fresh blood. Embolization was technically and clinically successful in all four patients. Subsequent sigmoidoscopy confirmed the diagnoses in three patients as a solitary rectal ulcer, iatrogenic traumatic ulceration following manual evacuation, and a rectal Dieulafoy's lesion. The other case was angiographically seen to be due to a rectal angiodysplasia. Embolization is an effective procedure in life-threatening superior hemorrhoidal arterial bleeding when endoscopic treatment fails, and should be preferred to rectosigmoid resection.

Directional atherectomy in iliac stent failure: clinical technique and histopathologic correlation

PURPOSE

To assess the feasibility and efficacy of directional atherectomy in the treatment of iliac stent stenosis or occlusion and to evaluate the histologic composition of excised atherectomy specimens.

METHODS

Directional atherectomy of six occluded and 10 severely stenosed iliac stents was undertaken in 12 patients at a mean interval of 28 months (range 3-69 months) after stent insertion for occlusive aortoiliac disease. In cases of stent occlusion, atherectomy was preceded by low-dose thrombolysis. In all patients stent clearance with return of femoral pulses was achieved within 24 hr and there were no significant complications. All excised specimens were sent for histologic examination.

RESULTS

Eleven patients (92%) remain symptom free with unlimited walking distance at a mean follow-up interval of 11.5 months (range 3-31 months) after treatment. Histologic examination revealed typical myointimal hyperplasia at three excision sites, intimal fibrosis at three sites, atheroma at four sites and organized thrombus at six sites.

CONCLUSION

Atherectomy offers an effective treatment in iliac stent occlusion and restenosis with no significant adverse effects. Debulking of these lesions seems to offer a more logical approach than simple balloon angioplasty. Clinical and duplex follow-up confirms satisfactory outcome within the first year but longer-term results are not yet known. The histologic data obtained demonstrate that stent restenosis and occlusion are likely to be multifactorial, and challenge the assumption that myointimal hyperplasia is the sole cause of iliac stent occlusion.

Transcatheter coil embolotherapy: a safe and effective option for major colonic haemorrhage

BACKGROUND

The management of major colonic bleeding is problematic. A proportion of patients require emergency surgery which is associated with high morbidity and mortality. Percutaneous embolotherapy, previously considered a high risk procedure in the colon, may provide an alternative treatment in this group of patients.

AIMS

To assess the safety and efficacy of embolotherapy in the treatment of life threatening colonic haemorrhage.

PATIENTS AND METHODS

Thirty eight patients with fresh haemorrhage per rectum were referred for surgery because of failed conservative treatment. All underwent angiography; in 14 a bleeding site or vascular abnormality was detected. A coaxial catheter was directed to the most distal bleeding artery and this was embolised with platinum coils.

RESULTS

Detection of a bleeding site correlated with haemodynamic stability at the time of angiography (r = 1 for a systolic blood pressure less than 100 mm Hg). Bleeding sites or vascular abnormalities were detected and embolised in 14 patients (37%). In 12/14 there was immediate and sustained haemodynamic improvement; two continued to bleed and required emergency hemicolectomy (14%). Three developed ischaemic complications (21.4%); these were managed conservatively and required no intervention. The 30 day mortality was 7.1% in the embolotherapy group and 10.5% in the overall group of 38 patients.

CONCLUSION

Colonic embolotherapy for life threatening haemorrhage is an effective, relatively safe procedure with a low incidence of major complications. Its use depends on the identification of a focal bleeding point or vascular abnormality, which in turn depends on the haemodynamic stability of the patient at the time of angiography.

Treatment of malignant superior vena cava obstruction: metal stents or radiation therapy

PURPOSE

The results of treating malignant superior vena cava obstruction by means of percutaneous self-expanding stent insertion or by means of radiation therapy were compared.

PATIENTS AND METHODS

Seventy-six patients with malignant superior vena cava obstruction who were treated by stent insertion were studied prospectively and 25 patients who were treated by radiation therapy were studied retrospectively. A superior vena cava obstruction score was devised to measure treatment effectiveness. Speed of symptom relief and complications were recorded. End points in the study were recurrent obstruction or death. Asymptomatic survival times were compared by log rank and Mann Whitney tests of significance, as well as Kaplan-Meier analysis. A subgroup of 26 patients who were treated by stent placement only were compared with the radiation therapy group and analyzed separately.

RESULTS

There were seven complications in the overall stent group, one in the stent-only group, and 25 in the radiation therapy group. Stent insertion provided faster relief of symptoms and significantly greater improvement in the superior vena cava obstruction score than radiation therapy (P < .001, Mann-Whitney U test). A Kaplan-Meier analysis of asymptomatic survival demonstrated that significantly fewer patients in the overall and stent-only groups developed recurrent symptoms (P = .0005 and .001, respectively, log rank test).

CONCLUSION

This study suggests that percutaneous stent insertion in malignant superior vena cava obstruction fulfills the requirements of a palliative procedure significantly better than radiation therapy and that it should be the procedure of first choice.

Preoperative staging of rectal carcinoma by magnetic resonance imaging with a pelvic phased-array coil

BACKGROUND

The use of surface coils for magnetic resonance imaging (MRI) allows enhanced image definition and so potentially more accurate staging of colorectal cancer. Endorectal coil imaging is invasive, operator dependent and impossible in a high proportion of patients due to rectal stricture. The phased-array pelvic coil, however, is non-invasive and applicable to all rectal tumours.

METHODS

A pelvic phased-array coil was used for preoperative MRI staging of 38 primary rectal carcinomas. Results were expressed according to the Dukes and tumour nodes metastasis (TNM) classifications. After resection of the tumour, the stage predicted on MRI was compared with the pathological classification.

RESULTS

The overall accuracy of preoperative staging with the pelvic phased-array coil was 55 per cent for both Dukes class and T stage. Assessment of nodal involvement gave an overall accuracy for MRI of 76 per cent with a sensitivity of 57 per cent and specificity of 88 per cent.

CONCLUSION

Use of a pelvic phased-array coil did not improve the staging accuracy of MRI to a clinically useful level.

Treatment of chronic iliac artery occlusions by means of percutaneous endovascular stent placement

PURPOSE

A retrospective evaluation of outcomes in patients with chronic iliac occlusions treated with insertion of metallic endovascular stents, without previous thrombolysis, on an intention-to-treat basis.

MATERIALS AND METHODS

Seventy-two patients with chronic iliac occlusion underwent attempted stent placement from either the ipsilateral or contralateral femoral artery. There were 49 men and 23 women. Mean age was 63.1 years (range, 39-88 years). A total of 89 stents were deployed in 67 patients. Follow-up was from 24 to 69 months (mean, 37.5 months).

RESULTS

Stents were successfully deployed in 67 patients (93%), with two early failures, giving a primary success rate of 90%. There were five significant and four insignificant procedural complications. There were four late failures (all within the first year) and four non-stent-related deaths.

CONCLUSION

Endovascular stent placement offers an alternative to surgery in the treatment of chronic iliac occlusions.

Misplacement of endoscopic biliary endoprostheses

Four patients with cholangiocarcinoma involving the common hepatic duct or the confluence of the hepatic ducts are described here, in whom endoscopically placed endoprostheses were unknowingly misplaced, with their proximal portions lying outside the bile duct system. Because of persisting jaundice, the stents were changed endoscopically in three cases on several occasions, but the misplacement was not recognized. The problem was recognized during percutaneous transhepatic cholangiography in all four patients, with percutaneous stent placement allowing resolution of the jaundice. The avoidance and management of this complication is discussed.

Feasibility, accuracy and safety of magnetic resonance imaging in acute aortic dissection

Magnetic resonance imaging (MRI) is the most accurate method of defining the morphology and haemodynamic features of thoracic aortic dissection. However, because of doubts about its safety in acute situations, its use has so far been confined to imaging chronic dissections. We present a prospective study of 50 patients thought clinically to have acute thoracic aortic dissection in which a rapid diagnosis was made by MRI.

Palliation of malignant oesophageal perforation and proximal oesophageal malignant dysphagia with covered metal stents

Twelve patients underwent placement of nine polyethylene-covered self-expanding metal stents (Cook), and three polyurethane-covered Wallstents (Schneider). All obstructing lesions were crossed fluoroscopically and stents placed under fluoroscopic control. Eleven of the 12 patients had recently undergone failed endoscopic stent insertion, which had resulted in oesophageal perforation. Technical success was achieved in 100% of patients, with no immediate complications. The stents were well tolerated and allowed the patients to eat within 12 h of their insertion. Covered stents are technically safe to insert, are best inserted fluoroscopically, and are particularly cost-effective in proximal oesophageal lesions and perforations, where Atkinson tubes are often not tolerated.

Measurement of tissue-bound amiodarone and its metabolites by computed tomography

Amiodarone is strongly tissue-bound and serum levels are a poor guide to therapeutic efficacy. The electrocardiographic measure of the QT interval corrected for heart rate (QTc) is a better guide but is unhelpful in patients with bundle branch block or U-waves on the electrocardiogram. Myocardial amiodarone levels are the most accurate guide but are not easy to obtain. There is, however, a relationship between myocardial concentration and hepatic concentration of amiodarone and its metabolites. Since amiodarone contains iodine, and there is hepatic uptake, the increased hepatic attenuation from single slice computed tomography was compared with serum levels and the electrocardiographic QTc in 12 patients before and during amiodarone therapy. Hepatic attenuation increased by a mean value of 18.25 HU over a 12 month study period. This increase correlated well with increased QTc (r = 0.83) and with serum amiodarone levels (r = 0.89), but less well with serum desethyl amiodarone levels (r = 0.43). An iodine-containing phantom was used to construct a curve of attenuation against iodine concentration in mol/l. Thus an indirect measurement of amiodarone concentration in g/l wet weight of liver could be determined.

The use of the Wallstent endovascular prosthesis in the treatment of malignant obstruction of the superior vena cava

Seventeen patients (10 men and seven women) aged 48-76 years (mean 63.4) who were suffering from malignant superior vena caval obstruction had Wallstents implanted percutaneously to relieve the obstruction. Fifteen of the patients had previously been treated by radiotherapy or chemotherapy, with either failure to remit or later recurrence. Six patients required thrombolysis prior to stenting. All patients had rapid relief of the obstructive symptoms. This was sustained in 15 patients to date or at death. Two patients, both of whom had pre-stent lysis, developed stent thrombosis following withdrawal of anticoagulation at 4 months and 7 days respectively. Stenting has been shown to be extremely effective at relieving superior vena caval obstruction in these patients and is usually the only method available in this condition when other treatments fail. Whether all patients presenting with malignant superior vena caval obstruction should be stented de novo remains to be proven.

The use of the Wallstent in aorto-iliac vascular disease

Forty-three patients had self-expanding endovascular Wallstents inserted for aorto-iliac arterial disease. A total of 59 Wallstents were inserted into 50 iliac arteries. There were 27 males and 16 females with a mean age of 62.51 years. Included in the series were 19 iliac occlusions, 21 severe atheromatous disease of the aortoiliac segment, two severe dissections following conventional angioplasty and one re-stenosis of a previously dilated iliac segment. All of the stents were successfully deployed but there were five significant complications. One case of distal embolism was treated by surgical embolectomy but the other four were treated by an additional percutaneous technique. At follow-up after 6 months all patients remain symptomatically improved. Aorto-iliac stenting is a cost-effective treatment in selected cases of severe aorto-iliac disease.

Palliation of inoperable biliary obstruction with self-expanding metal endoprostheses: a review of 77 patients

Our experience of inserting 90 self-expanding metal endoprostheses in 77 patients with obstructive jaundice is described. All were inserted percutaneously. The longest metal endoprosthesis available was inserted where possible. For local economic reasons most patients had a normal serum albumin, and no evidence of metastases at presentation. Dilatation of biliary occlusions and strictures was not performed. Six re-interventions have been necessary because of tumour ingrowth or overgrowth. Serum bilirubin levels fell to normal in 98.7% of patients within 7 days of insertion. Self-expandable metal endoprostheses offer technical, psychological, physiological and anatomical advantages compared to other forms of palliation in biliary obstructions thought to be unsuitable for surgery. Furthermore, where stents have to be placed percutaneously because endoscopy is not possible, self-expanding metal endoprostheses should be used.

Percutaneous transluminal angioplasty of the subclavian artery

A series of 12 consecutive cases of symptomatic subclavian artery stenosis or occlusion treated by percutaneous transluminal angioplasty are described. In seven cases stenoses were successfully dilated, and in four out of five cases occlusions were recanalised using standard angioplasty technique. Complications were trivial and did not prolong hospital stay, all patients being discharged within 48 h of the procedure. Percutaneous transluminal angioplasty of the subclavian artery is a safe, effective procedure and recommended as the treatment of first choice in symptomatic subclavian stenosis or occlusion.

Arteriovenous malformations involving the vein of Galen

Images

The value of computed tomography in the diagnosis of amiodarone-induced pulmonary toxicity

Amiodarone hydrochloride (Cordarone) is an effective antiarrhythmic drug which can cause a potentially fatal pneumonitis. The clinical diagnosis is difficult and investigation non-specific. Narrow section computed tomography (CT) was performed in nine patients who developed new respiratory symptoms during treatment with amiodarone. All had chest radiographs prior to CT, six had respiratory function tests and four had serum amiodarone estimations. High density basal peripheral pleuro-parenchymal lesions were seen in four of the nine patients. These appearances were compatible with those previously detected in other pulmonary interstitial lung diseases. We suggest that CT is a useful investigation in patients with suspected amiodarone pulmonary toxicity.

The measured height of the lumbosacral disc in patients with and without transitional vertebrae

In the presence of transitional lumbosacral segmentation, the lumbosacral intervertebral disc is significantly narrower than its counterpart in non-transitional spines. Even in spines with no transitional features, the lumbosacral disc is significantly narrower than discs at higher levels. This narrowing does not imply disc degeneration.

Photochemical synthesis 29. Photoannelation and cyclohexenone

Values of 1.7 × 108 s−1 and 2.5 × 107 M−1 s−1 for kd, the unimolecular rate constant for decay, and kr, the rate constant for addition to cyclohexene, have been obtained for cyclohexenone. These indicate that this cyclenone decays somewhat faster and reacts significantly slower with the same substrate (in the same solvent) than does cyclopentenone. Evidence is adduced, from sensitization experiments and the phosphorescence quenching of a range of carbonyl compounds, that the reactive triplet and lowest triplet of cyclohexenone lie close together, if they are indeed not identical, and the energy of this triplet is in the region of 66–68 kcal/mole. This is higher than that indicated by photostationary state measurements. This latter method, applied to cyclenones, may be suspect, and triplet energies so derived subject to doubt (that of cyclopentenone included) or have a different significance from those obtained by other methods. Further attempts to demonstrate the existence of a lower, cycloadditively unreactive, triplet in cyclopentenone have been negative. It now seems far more likely that the original interpretation was in error, that the lowest energy triplet is near 73 kcal/mole, and that a special mechanism for quenching benzophenone triplets by ground state cyclopentenone exists. The evidence for other multiple reactive triplets is re-examined as is the evidence for the nature of the states involved.

Evidence for reversible intermediate formation in cyclopentenone cycloaddition

The usual kinetics for product formation lead to variable values of kd, the rate constant for decay of the responsible triplet. On the assumption that at least one intermediate is formed which gives either products, or reverts to starting materials, a value near 108 s−1 is obtained for kd both from cyclopentene and hex-3-ene cycloadditions.