Accuracy of ‘Quickscan’ in arterial graft surveillance

ABSTRACTS Imaging of epidural blood patches was conducted 30 min to 24 h after injection. All patients were imaged on a 0.5 T system using Tl-weighted parasagittal and transverse images (GE 500/25/90") and parasagittal STIR (IR 1500/110) sequences. Following epidural anaesthesia the epidural space and thecal sac appeared normal. In 2/3 patients following uncomplicated epidural catheterization and in all three patients in w h o m catheterization was difficult, there was extensive h a e m a t o m a arising in the region of the spinous process at the level of puncture and passing down in the interfascial space of the deep subcutaneous tissue. Following epidural blood patching (volume 15 22 ml), blood was seen to extend over 8-10 spinal segments within the epidural space and was associated with compression of the thecal sac over 3-5 levels around the injection site. All mass effect resolved by 9 h at which time patches of h a e m a t o m a were seen adherent to the thecal sac. Extensive interfascial h a e m a t o m a was also present in all these patients. Blood patch was successful in all cases with complete resolution of headache. Epidural catheterization appears to be commonly associated with extensive h a e m a t o m a into the soft tissues of the back which m a y reflect trauma to the spinous processes during needle insertion. The findings in patients following blood patches suggests that the immediate effect reflects raised CSF pressure to thecal compression, whilst the sustained effect is due to sealing of the thecal-epidural fistula.

VIDEO L O O P M R I OF O C U L A R M O T I L I T Y D I S O R D E R S R. D. LAITT, F. JEWELL, C. J. W A K E L E Y , J. K A B A L A , C. BAILEY, M. POTTS*, R. H A R R A D * , M. W E S T O N and P. G O D D A R D

Department of Radiology and *Ophthalmology, United Bristol Healthcare Trust, Bristol In certain conditions such as blow out fractures o f the orbital floor, Duane's syndrome and thyroid eye disease assessment of dysconjugate eye movements is made clinically with imaging having only a limited role. Video-loop M R I of the orbits is a technique that adds functional information of eye movements to the anatomical information obtained from static images and hence allows more accurate assessment of these patients when surgical intervention is being considered. Images were acquired on a 1.0 T scanner (Siemens M a g n e t o m Impact) using the FISP 2D sequence, flip angle 30", T R 17 ms and TE 7 ms with a fast acquisition time of 15 s per scan. Scans were obtained with the patient fixating sequentially through the visual field in either a transverse or vertical direction depending on the eye movements of interest. These images can then be played in sequence to produce a moving video image. We describe our findings in 12 patients with traumatic or surgicallyinduced lesions of extraocular muscles or the orbital floor, 20 patients with thyroid eye disease and three patients with D u a n e ' s syndrome. The video-loop images provide valuable information to the surgeons and this technique is now performed routinely in the assessment of these patients.

H E M I F A C I A L SPASM: P R E - O P E R A T I V E D E M O N S T R A T I O N O F V A S C U L A R C O M P R E S S I O N O F T H E FACIAL N E R V E BY MAGNETIC RESONANCE ANGIOGRAPHY J. F. M. M E A N E Y , J. B. MILES, T. E. N I X O N , G. H. W H I T E H O U S E and E. S. B A L L A N T Y N E

Department of Neuroradiology and Neurosurgery, Walton Hospital, Liverpool Hemifacial spasm (HS) may be due to vascular compression of the facial nerve at its root entry zone (REZ) by a looping vessel. At present an exploratory craniotomy is performed on the assumption that vascular compression is p r e s e n t - t h i s is not always the case however. We performed magnetic resonance angiography ( M R A ) to establish whether the base data provided adequate demonstration of the relationships of the facial nerve to the adjacent vessels to enable identification of those cases which might benefit from surgical decompression. The neurovascular relationships of the facial nerve were examined in seven patients with hemifacial spasm and 25 controls using an FISP 3D M R A sequence. Angiograms were reconstructed from the base data using a m a x i m u m intensity projection (MIP) algorithm. The axial slices and mean planar reconstructions were inspected. Vascular compression of the symptomatic facial nerve at the R E Z was seen in all seven patients with HS but in only one asymptomatic facial nerve. Posterior fossa exploration was performed in five patients and confirmed the findings in all of these patients. Our study supports vascular compression of the facial nerve as the

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cause of HS and establishes that N V C can be identified pre-operatively by M RA.

A S P I N A L SKIN MARKER FOR M R I P. D. G R I F F I T H S , P. E N G L I S H and A. G H O L K A R

Department of Neuroradiology, Newcastle General Hospital, Newcastle upon Tyne Magnetic resonance imaging (MRI) is the method of choice for visualizing spinal pathology in patients with spinal cord compression. It is important to translate abnormalities shown by imaging to an external reference point in order to direct surgery or radiotherapy to the precise location of pathology. We describe a method which allows external topographic marking of spinal abnormalities in patients undergoing MRI. Design: A series of six, 8 cm plastic tubes of either 4 or 6 cm diameter were filled with Dimeglumine Gadopentetate (Magnevist, Schering) diluted to 1% of its commercial concentration (469 mg/ml). The ends of plastic tubes were heat sealed. These were secured at 5 cm intervals along an adhesive flexible backing. This system is securely fastened to patients skin overlying the region of interest. Indelible skin marks are placed adjacent to the tubes with the patient prone. The patient is then turned over and scanned using routine protocols. After scanning, the patient's back is checked for any movement of the tubes. Short T R / T E sagittal images were used to localize the pathology to skin marker. These images demonstrate high signal from the tubes placed on the skin and can be matched precisely with the level of pathology. Results: Patients with spinal cord compression (50) and disc disease (10) were scanned using this method. All six tubes were identified on sagittal/parasagittal images in each o f the subjects. The skin marker did not move during the examination in any patient. In those patients undergoing surgery, correct localization of pathology was confirmed.

CAN R A D I O L O G I S T S S T O P KISSING? P. I. I G N O T U S , M. I. S H A I K H , A.-M. BELLI and T. M. B U C K E N H A M

Department of Diagnostic Radiology, St George's Hospital. London Purpose: To assess the safety of balloon dilatation of atheromatous disease involving the c o m m o n iliac artery (CIA) origin without contralateral balloon protection. Materials and Methods: We retrospectively reviewed all patients undergoing CIA dilatations within 1 cm of the ostium over a 30 m o n t h period. Complications and the pre- and post-dilatation appearance of the contralateral CIA were recorded. Results: 30 dilatations were performed on 24 patients with a mean age of 64.8 years (range 48-79 years). Twenty-three were undertaken for claudication (Fontaine stages IIa or lib) and seven for rest pain or tissue loss (Fontaine III or IV). There were 22 stenoses and eight occlusions. All were treated by ipsilateral dilatation only. Two cases were stented for recurrent disease or inadequate PTA. Technical success was 100% and angiographic success 28/30 (93%). Twelve cases had significant contralateral ostial disease. In none were the symptoms or angiographic appearance worse following PTA and no contralateral embolizations occurred. In two cases femoral artery aneurysms occurred at the puncture site. Conclusion: Conventional teaching suggests that the contralateral iliac artery should be protected by a balloon when dilating atheromatous disease near the CIA origin. Our results show that this is not warranted. A C C U R A C Y OF ' Q U I C K S C A N ' IN A R T E R I A L G R A F T SURVEILLANCE B. J. M c K E O W N , A. D. H O U G H T O N , D. K I N G , P. T A Y L O R and J. F. R E I D Y

Departments of Radiology, Surgery and Ultrasonic Angiology, Guy's Hospital, London Introduction: Occlusion of femoro-popliteal and femoro-distal by-pass grafts is a major problem with 5 year failure rates of 20 75~ Detection and treatment of stenoses developing within the first year m a y improve graft survival from 53% to 93%. This study is to evaluate the accuracy of "Quickscan' (QS) as a rapid, reliable, inexpensive, noninvasive technique for graft surveillance. Design: Prospective study. Patients and Methods: 37 infrainguinal grafts were examined by QS and digital subtraction angiography (DSA). Correlations were per-

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CLINICAL RADIOLOGY

formed in the proximal, mid and distal portions of the grafts, and in adjacent native vessels. Significant stenosis on QS was defined as a velocity drop of 3 : I, corresponding to a 42'/0 decrease in cross-sectional area. Results: 19 stenoses and two occlusions were detected on DSA. Three stenoses were missed on QS, one attributed to an overlying profunda femoris artery. There were two false positive occlusions and four false positive stenoses. These lesions were, however, found in adjacent native vessels and do indicate a graft at risk. Conclusion: Quickscan is a sensitive technique suitable for graft surveillance. When +at risk' grafts are detected, angiography should precede angioplasty or thrombolysis.

recent report claims a difference between arterial and venous anticoagulation post H bolus. The aim of this study was: (1) to establish the range of protocols for H use in the U K in the light of published guidelines; and (2) to determine the effect of intravascular H and its variation between venous and arterial blood.

E S T A B L I S H M E N T O F A R A D I O L O G I C A L SERVICE F O R T H E I N S E R T I O N OF AN I M P L A N T A B L E V A S C U L A R ACCESS SYSTEM 9 C. COUSINS, A. LOPEZ, P. S I D H U and D. D U T K A

(1) Of the 116 questionnaires sent, 85 were returned (73%). A wide range of protocols are in use ranging from no H to 10000 IU H per h, although most (69"/0) use between 3000 and 6000 IU H. N o measurement of clotting times is performed or used to justify variable doses. (2) A bolus dose of 3000 IU H gave adequate anticoagulation (twice baseline ACT) for 30 min in 83% of cases and for 15 min in 97% of cases; sufficient to cover most angioplasties done. No difference between venous and arterial A C T was found. (1) Heparin usage in this context in the U K is very variable and, in m a n y cases, at variance with published recommendations. We believe there is a need for protocol standardization. (2) We have shown that a 3000 IU H bolus at the time of angioplasty gave adequate anticoagulant coverage in most cases.

Departments of Radiology and Cardiology, Hammer~mith Hospital and Royal Postgraduate Medical School, London An implanted subcutaneous vascular port has many advantages for long-term venous access. The system benefits patients suffering from a wide range of chronic diseases requiring chemotherapeutic regimes or transfusions. These patients include those with HIV infection whose infective exacerbations m a y be m a n a g e d at home with intravenous antibiotics via the port, transfusion-dependent patients with sickle cell disease and patients with malignancy receiving chemotherapy. A radiological service for the percutaneous insertion of the Vascuport (Viggo-Spectramed), a fully implantable venous access system, has been successfully estal~lished following an initial pilot study to assess feasibility. Twenty-four Vascuports have now been inserted radiologically in the angiography suite under local anaesthetic. Such systems have traditionally required surgical placement with the additional costs of theatre time and anaesthetist, if needed. Radiological insertion of the implantable port potentially offers a substantial annual saving of 40~ compared with surgical placement. Patient acceptance of the Vascuport is greater than for tunnelled external catheters as their lifestyle is not so restricted. The insertion of a port venous access device by the radiologist is a feasible, safe and cost effective procedure which is acceptable to both patients and clinicians. Due to demand a regular service has now been established.

EARLY C L I N I C A L E V A L U A T I O N O F T H E C O R D I S HYDRODYNAMIC THROMBECTOMY CATHETER P. I. I G N O T U S , D. J. BREEN, T. M. B U C K E N H A M and A.-M. BELLI

Department of Diagnostic Radiology, St George's Hospital, London Purpose: TO assess the efficacy of the hydrodynamic thrombectomy catheter-(HTC) in treating lower limb arterial and graft occlusions. Method and Materials: The H T C is a blunt-ended catheter which aspirates thrombus by injecting pressurized saline across an opening causing suction through the venturi effect. We have so far used the H T C in five patients (six procedures) with ischaemic limbs of 2 days to 6 weeks history: one native superficial femoral artery, one femoro-popliteal vein graft and three synthetic femoro-popliteal grafts. Results: The catheter successfully aspirated most of the thrombus in 5/ 6 cases. Three subsequently required aspiration of distally embolized material, and two needed adjuvant Tissue Plasminogen Activator. One patient had a stenotic distal anastomosis of a PTFE graft which was angioplastied. This re-occluded and 2 days later the graft was again lysed with the H T C and an atherectomy performed to maintain patency. In one patient a dissection occurred in a vein patch at the distal anastomosis necessitating surgical revision. Conclusion: The H T C effectively removed thrombus rapidly and reduced the requirement for thrombolysis. It is most effective in occluded synthetic grafts. Distal embolization has been a problem although this is amenable to aspiration and thrombolysis. Design modifications are under way to minimize this complication. T H E P H A R M A C O K I N E T I C S A N D UK U S A G E OF H E P A R I N IN VASCULAR INTERVENTION P. DE V. M E I R I N G , M. G A N D H I and P. A. G A I N E S

Department of Radiology, Royal Hallamshire Hospital, Sheffield intravascular heparin (H) is a recognized treatment during peripheral and visceral angioplasty, although usage and dose varies widely. A

(1) A questionnaire was sent to 116 members of the U K Radiological Interventional Society to establish usage, dose, timing and variations in H use in both flushing solution and as an adjunct to angioplasty. (2) The activated clotting time (ACT) was measured immediately before and at intervals for 1 h after a bolus H dose during 30 angioplasty procedures. The effect of our most commonly used doses were determined and arterial and venous A C T compared.

M A G N E T I C R E S O N A N C E A N G I O G R A P H Y OF R E N A L ARTERY S T E N O S I S W. G E D R O Y C , P. N E E R H U T , R. N E G U S and T. T A U B E

Departments of Radiology and Renal Medicine, St Mary's Hospital, London Renal artery stenosis (RAS) is a c o m m o n cause of renal impairment which is, in m a n y cases, potentially reversible. Unfortunately, the diagnosis of this condition is currently largely dependent on invasive intra-arterial angiography. In an effort to see whether a suitable noninvasive screening test could be developed for the diagnosis of RAS, we evaluated 3D phase contrast (3DPC) magnetic resonance angiography in this situation. 3DPC was carried out on 60 consecutive patients undergoing conventional angiography and the results were assessed independently. Conventional angiography was assumed to be the gold standard for the purposes of this study, and calculated sensitivity and specificity results were 86% and 97% respectively. 3DPC studies allowed good visualization of the renal vasculature often beyond the renal hilum and more often useful in patients who had very tortuous arteries which may be a limiting factor in conventional angiography. O u r conclusions were that 3D phase contrast M R angiography is a very promising technique for non-invasive investigation of renal artery stenosis with acceptable sensitivity and specificity levels. Its noninvasiveness suggests that it m a y be a useful screening test in the future, and further improvements in technology will also prove its performance.

A N G I O G R A P H I C E M B O L I Z A T I O N O F T H E DISTAL I N T E R N A L M A M M A R Y ARTERY (IMA) AS AN A D J U N C T T O R E G I O N A L C H E M O T H E R A P Y IN I N O P E R A B L E BREAST CARCINOMA D. H. A. M c C A R T E R , J. C. D O U G H T Y * , C. S- McARDLE*~ T. G. C O O K E * and A. W. REID

Departments of Radiology and *Surgery, Glasgow Royal Infirmary, Glasgow Local control of stage III/IV breast cancer is difficult to achieve. Regional chemotherapy delivers high doses of the drug to the breast with minimal systemic toxicity. The conventional methods of delivering regional breast chemotherapy are operative insertion of subclavian artery catheters and, more recently, radiological insertion o f IMA catheters 9 Both methods are complicated by unwanted perfusion of the anterior abdominal wall via the superior epigastric artery. Skin sloughing and necrosis have been reported in the superior epigastric territory when chemotherapy has been delivered. We have devised a method of eliminating this unwanted perfusion by coil embolization of the distal IMA. A selective catheter is sited fluoroscopically into either the left or right I M A using a trahsfemoral Seldinger approach. A coaxial system is used to deliver a platinum occlusion coil into the distal 1MA, beyond the last branch to the breast.