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Techniques of cerebral angiography
Techniques By RICW
of Cerebral
L. GOLDMAN,
M.D.,
Angiograpby AND E. RALPH HEINZ, M.D.
EREBRAL ANGIOGRAPHY broadly refers to the evaluation of the vessels of the brain, and includes a variety of approaches. Naturally, the particular clinical situation, the age, and the information desired will all weigh heavily in the decision for performing cerebral angiography by a given route. However, for this discussion, we will assume that the particular procedure to be performed has already been selected and we will not be concerned with the indications for its choice.
C
CAHOTIDARTERIOGRAPHY:
Dmecr NEEDLE Prnvcrurur
Whenever arteriography is to be performed, the physician performing the procedure, whether neurologist, neurosurgeon, or radiologist, should familiarize himself with the case, and should take the time to explain the nature of the procedure to the patient, and if necessary, to the patient’s family. Although the situation may indicate that arteriography is warranted, we must still make every effort to obtain “informed consent.” The “informed” portion naturally may present problems, and how much should be explained as to the procedure and possible complications will vary with the particular case and the policy at the given institution. Premeditation Sedation for adults usually consists of 100 mg. of Seconal, 0 to 50 mg. of Dcmerol, and 0.4 to 0.6 mg. atropine on call to the X-ray Department. With this sedation, most patients tolerate the procedure without difficulty, and only rarely has general anesthesia been needed. In children, we have been using relatively low doses of a mixture of Seconal, Thorazine, and Demerol, and have an intravenous solution running at the time of the procedure to allow for supplementation with Valium in low doses at a very slow rate. It should be noted, however, that in young children, cerebral arteriography via the femoral route has been our usual choice and has allowed this sedation, rather than anesthesia, to be acceptable. Direct carotid arteriography may be performed with this sedation in children, although general anesthesia may be required more often than in the adult group. Equipment The radiographic equipment needed for carotid arteriography has already been discussed. Sterile trays containing most of the materials needed for the performance of the procedure should be prepared as well as equipment for emergency use. Basic items include sterile drapes, metal bowls for flushing RICHARD L. GOLDXZAN, M. D.: Assistant Professor of Radiology, University of Pittsburgh School of Medicine, Presbyterian-University Hospital, Pittsburgh, Pa. E. RALPH HEINZ, M. D.: Professor and Chairma% Department of Radiology, Uniuersity of Pittsburgh Schuol of Medicine, Presbyterian-Uniuersity Hospital, Pittsburgh, Pa.
SEMINARSINROENTGENOLOGY,
Vo~.6,No.l
(JANUARY),
1971
8
GOLDMAN
for
AND HEINZ
Fig. L-Needle systems cerebral angiography.
A. 18T cannula stylet and flexible carotid guide. B. Disposable 18Tplastic cannula with stylet and guide. solutions, materials to prepare the neck, needles, connecting tubing, stopcocks, syringes, and gauze squares. The trays should be kept as simple as possible without cluttering with rarely used materials. Many needles designed for carotid arteriography have been produced and each needle has its advocates. It has been shown that most complications resulting from the procedure are related to the technique of puncture rather than to the contrast medium or cerebral effects. For this reason, the selection of an appropriate needle system is important. A needle system consisting of a blunt tip cannula and a removable sharp central stylet is recommended. Another valuable addition is a guidewire that can be inserted into the needle and that will project a few centimeters beyond the tip with a flexible portion of wire. This allows threading of the needle into the carotid artery by holding the hub of the needle and will allow the guide to back out of the needle automatically if an obstruction is met. This will immediately tell the examiner to cease advancing and to take a test film to determine the position of the needle. An example of this system which we use is shown in Figure 1A. This is the Cook 18T needle and stylet and the guidewire specifically made for it. Disposable Teflon cannulas with an inner metal stylet have been prepared (Fig. 1B ) and these can also be handled and threaded using the same guidewire as with the metal cannula. Contrast Media
Discussion of the relative values of the various contrast media is beyond the scope of this article. The 29 per cent iodine compounds of Hypaque, Renografin, and Conray have all been used with satisfactory opacification and a minimum of complications.
TECHNIQUES
OF CEREBRAL
ANG~Of.SAPl%
9
Procedure The patient is supine on the table with his head extended. An inflatable balloon placed beneath the shoulders will help achieve extra extension. The carotid artery should be punctured below the bifurcation, which is roughly at the level of the upper border of the thyroid cartilage. If the vessel can be trapped between the index and middle fingers of one hand, it facilitates puncturing the vessel with the needle in the other hand. Detecting a thrill with the tips of the finger on a forceful push upon the needle helps to establish proper needle placement. The needle is then passed at an angle through both walls of the vessel and the stylet is removed. Slow withdrawal of the cannula will result in a good flow of blood if the needle is properly placed. Frequently, the first blood obtained is a slow trickle indicating that the cannula tip is against the posterior wall; a further pull of 1 or 2 mm. while elevating the tip of the cannula should give good ilow. At this point, the guidewire is gently inserted and, if it passes all the way to the hub without meeting an obstruction, the cannula is threaded into the artery by holding the hub without having the finger over the end of the guidewire. In younger patients, the cannula may be safely threaded several centimeters, whereas in older individuals, one may wish to thread only 1 or 2 cm. to avoid atherosclerotic plaques. A very important part of the procedure is the test injection for needle placement, which should always be done. Three or 4 cc. of contrast medium should be injected and a single lateral film taken. If rapid film processing is available, a standard film is used; without rapid processing, a Polaroid technique will give satisfactory information, One should be certain to have the needle visible on the test film and good filling of the common, internal, and external carot.id arteries should be seen. If evidence of an intimal tear is noted, careful attempts to reposition the needle should be made *before proceeding with the injections, However, with the technique described, it is rare to encounter subintimal injection of contrast medium. The test film also may have some diagnostic import, as one may detect evidence of atherosclerotic disease at the bifurcation. Selective injection of the internal or external carotid artery may occasionally be indicated. With proper puncture using the system described, the needle may be advanced either into the internal or external carotid artery after a test injection. Alternatively, catheter placement under fluoroscopy followed by selective internal or external catheterization may be performed.
Radiographic
Factors
A high ma three-phase generator allows for relatively low kv, high mas films, which will still be within the time limitations of the rapid film changer. This permits the average kv of the photons to be closer to the photoelectric absorption peak for iodine and will give better contrast with less unwanted scatter. However, it is not necessary to have this sophisticated equipment to produce good angiograms. Satisfactory angiograms may be made with 300 ma, single phase equipment as long as close attention is paid to the radiographic
10
GOLDMANANDHEINZ
factors. The use of extension cones will also greatly improve the quality of the radiographs. The standard angle for AP carotid arteriography is approximately 12” caudal to the canthomeatal line. This angulation will place the superior orbital rim and the upper border of the petrous bone at the same level. As much flexion of the chin as possible is worthwhile to allow as little tube angulation in relation to the film as possible. The less angulation, the less distortion. The sequencing should be such that films are obtained in the early and late arterial phases, the capillary phase, and the early and late venous phases. Our routine film sequence is two films per second for 2% to 3 seconds, and then one film per second for an additional 4 seconds. The first film usually contains no contrast and can be used for subtraction if this is indicated. This sequence will completely cover the circulation in most cases, but if the first injection shows delayed flow, subsequent film series should be timed accordingly. RETROGRADE BRACHIAL
ARTERIOGRAPHY
Retrograde brachial arteriography has a definite place in the armamentarium of neuroradiology and, when applied properly, can give high quality examinations. In certain situations, it may be the safest and most informative procedure. Right retrograde brachial arteriography may demonstrate the origin of the right common carotid artery, the origin of the right vertebral artery, the right carotid bifurcation, and the intracranial right carotid system as well as the posterior circulation. Statistics show that the left vertebral artery is significantly larger than the right in approximately 50 per cent of the patients, the two vertebral arteries are equal in size in about 25 per cent, and the remaining 25 per cent have a larger right vertebral artery. Based on these statistics, if one is interested in examining only the posterior fossa circulation, a retrograde left brachial arteriogram (which would naturally visualize only the left vertebral artery) would be preferable. However, this technique probably will not visualize the right posterior inferior cerebellar artery. If study of this vessel is also needed, simultaneous bibrachial injection can be used. Equipment
The tray for brachial arteriography is similar to that for carotid arteriography with a few exceptions. For brachial arteriography, a 16T cannula, solid stylet, and 16 gauge guidewire are used. Pressure resistant, radiolucent, flexible, polyethylene tubing which will withstand a bursting pressure of 400 to 500 mm. Hg is recommended as connecting tubing. The needle is threaded gently up to the hub, again making sure the guidewire does not back out. The needle is fixed to the skin with two adhesive strips crossing one another over the hub. This will adequately secure the needle and will obviate the need to sew it to the skin, as has been common practice, Contrast Injection
The contrast agent used is the same as that for carotid arteriography. On the right side, in adults, an injection of 60 cc. at the rate of 30 cc. per second for
TECHNIQUESOFCEREl3RALANGIOG~PHY
11
2 seconds, with a blood pressure cuff blown up on the forearm below the puncture site, will give excellent visualization of the intracranial carotid circulation in’ a high percentage of cases. This amount of contrast can be safely injected several times. On the left side, 40 to 50 cc. of contrast, again with the blood pressure cuff blown up below the needle, will usually give satisfactory posterior fossa studies. A power injector is needed for this examination, and most of the available injectors are satisfactory. We prefer the type that allows setting the amount of contrast instilled per second and the injection time rather than the ones that necessitate setting a definite pressure. The importance of obtaining a preliminary film of the arm with a hand injection of 5 to 6 cc. of contrast material is again stressed. One should be certain that the needle is within the lumen and that the hub is fixed to the skin in such a way that the axis of the needle is parallel to the axis of the artery. If there is marked angulation of the needle to the artery, the chances for a subintimal injection or a ruptured artery due to the high pressure injection are considerably increased. However, with satisfactory needle position as shown on the preliminary film, the chances of complications at the puncture site are minimal. The film sequence for brachial arteriography is the same as that for carotid arteriography, except that there should be a l-second delay in filming after the injection is started to allow for the contrast to travel from the arm to the head. Upon completion of the examination, the needle should be removed and broad pressure applied with the hand over the puncture site. One should be able to palpate the radial pulse while the pressure is being applied. CATHETERCEREBRALANGIOGRAPHY
Selective catheterization of the carotid and vertebral arteries via the femoral approach is now established as a major method of examining the cerebral circulation. Catheter angiography is particularly helpful when no localizing signs are present and several vessels must be visualized. This is also true in the case of subarachnoid hemorrhage from aneurysm or arteriovenous malformation where it is mandatory to study multiple vessels. Catheter angiography is the technique of choice in children whether for a single or multiple vessels, as it seems quite safe and is much less traumatic than direct carotid angiography. A patient with a tracheostomy or intubation may also be examined more easily by the femoral approach. Selective angiography becomes more difficult in the elderly, in whom extensive atherosclerosis and marked uncoiling of the aortic arch may make it difficult to adequately catheterize the individual vessels. Insertion of the catheter is by the standard Seldinger method. We prefer to buy rolls of barium-impregnated polyethylene tubing and to shape the tip of the catheter individually for each patient, depending on age and on the appearance of the aortic arch. In children under 4 years of age, a #4 French catheter is usually used; in older children a #5 French catheter is employed. In adults, a #5F or #6F catheter is preferred. In the younger individual, a
GOLDMAN
AND
HEINZ
Fig. 2.- Catheters for selective cerebral angiography. A. Straight barium~ impregnated polyethylene catheter with small bend
at tip. B. Double
curve
~ catheter of barium-impreg-
nated polyethylene. C and D. Cordis 1 and 3 “headhunter” catheters. straight catheter (except for a small bend at the tip) will usually suffice to enter all of the vessels (Fig. 2A). If a particular vessel is difficult, a double curve catheter (Fig. 2B) can be easily fashioned and will invariably allow catheterization of the desired vessel. In the occasional individual in whom catheterizing a vessel with the small polyethylene catheters is diihcult, the Cordis headhunter catheters (Fig. 2C, D), which have excellent torque, will usually succeed. The large size of these catheters makes them dangerous for selectively catheterizing a vertebral artery unless it is known to be large. In these cases, it may be advisable to inject the contrast medium into the subclavian artery adjacent to the vertebral orifice. In younger individuals, it is acceptable to perform angiography by selectively catheterizing the vertebral with a small catheter so long as one observes rapid washout
with
a test injection
under fluoroscopy.
The Teflon coated 125 cm. guidewires have proved very satisfactory in our experience. In older individuals, the removable core and J guidewires have been of help in negotiating markedly atherosclerotic vessels. After removal of the catheter, broad compression of the femoral artery puncture
site should
be applied,
but complete
occlusion
should
be avoided.
The procedure should only be performed on in-patients so that there may be proper observation of the patient and the puncture site for 24 hours following the examination.
13
TECHNIQUESOFCEREEJRALANGIOGRAFTIY FACTORS COMMON TO ALL METHODS OF CEREBRAL ANGI~CRAPHY
Regardless of the method of opacifying the cerebral vessels, the posStion of the head, the film sequence, and other radiographic factors are the same. One should make every effort to obtain high quality films. The patient’s level of consciousness, blood pressure, and respirations should be constantly monitored. If a patient becomes severely hypotensive, one should, of course, attend to this problem rather than continuing with attempts to visualize the intracranial vessels. Constant irrigation of the needles or catheters is important in all methods of examination. We use 4 to 5 cc. of a 1 to 1000 Heparin solution per 500 cc. saline. Frequent flushing may prevent thrombus formation within the needle and decrease the incidence of fibrin emboli. Many individuals find the use of a closed system for flushing with a bottle of intravenous saline connected to a stopcock to be preferable to the technique of drawing the solution from metal bowls on the table. Another method is the use of a high pressure infusion to provide a continuous drip into the arterial system between injections. SPECIAL TECHNIQUES
Magnification
Small focal spot tubes with a high heat capacity will allow magnification serial cerebral angiography. This may play an increasingly important role in evaluation of many of the small intracranial vessels. Subtraction
Subtraction films have been shown to increase the certainty and may actually provide the only diagnostic film.
of a diagnosis
Stereoscopic Films
Stereoscopic films, particularly in the lateral projection, for lesions in the posterior fossa as well as in the supratentorial compartment, have been used by many neuroradiologists.
of Cerebral
L. GOLDMAN,
M.D.,
Angiograpby AND E. RALPH HEINZ, M.D.
EREBRAL ANGIOGRAPHY broadly refers to the evaluation of the vessels of the brain, and includes a variety of approaches. Naturally, the particular clinical situation, the age, and the information desired will all weigh heavily in the decision for performing cerebral angiography by a given route. However, for this discussion, we will assume that the particular procedure to be performed has already been selected and we will not be concerned with the indications for its choice.
C
CAHOTIDARTERIOGRAPHY:
Dmecr NEEDLE Prnvcrurur
Whenever arteriography is to be performed, the physician performing the procedure, whether neurologist, neurosurgeon, or radiologist, should familiarize himself with the case, and should take the time to explain the nature of the procedure to the patient, and if necessary, to the patient’s family. Although the situation may indicate that arteriography is warranted, we must still make every effort to obtain “informed consent.” The “informed” portion naturally may present problems, and how much should be explained as to the procedure and possible complications will vary with the particular case and the policy at the given institution. Premeditation Sedation for adults usually consists of 100 mg. of Seconal, 0 to 50 mg. of Dcmerol, and 0.4 to 0.6 mg. atropine on call to the X-ray Department. With this sedation, most patients tolerate the procedure without difficulty, and only rarely has general anesthesia been needed. In children, we have been using relatively low doses of a mixture of Seconal, Thorazine, and Demerol, and have an intravenous solution running at the time of the procedure to allow for supplementation with Valium in low doses at a very slow rate. It should be noted, however, that in young children, cerebral arteriography via the femoral route has been our usual choice and has allowed this sedation, rather than anesthesia, to be acceptable. Direct carotid arteriography may be performed with this sedation in children, although general anesthesia may be required more often than in the adult group. Equipment The radiographic equipment needed for carotid arteriography has already been discussed. Sterile trays containing most of the materials needed for the performance of the procedure should be prepared as well as equipment for emergency use. Basic items include sterile drapes, metal bowls for flushing RICHARD L. GOLDXZAN, M. D.: Assistant Professor of Radiology, University of Pittsburgh School of Medicine, Presbyterian-University Hospital, Pittsburgh, Pa. E. RALPH HEINZ, M. D.: Professor and Chairma% Department of Radiology, Uniuersity of Pittsburgh Schuol of Medicine, Presbyterian-Uniuersity Hospital, Pittsburgh, Pa.
SEMINARSINROENTGENOLOGY,
Vo~.6,No.l
(JANUARY),
1971
8
GOLDMAN
for
AND HEINZ
Fig. L-Needle systems cerebral angiography.
A. 18T cannula stylet and flexible carotid guide. B. Disposable 18Tplastic cannula with stylet and guide. solutions, materials to prepare the neck, needles, connecting tubing, stopcocks, syringes, and gauze squares. The trays should be kept as simple as possible without cluttering with rarely used materials. Many needles designed for carotid arteriography have been produced and each needle has its advocates. It has been shown that most complications resulting from the procedure are related to the technique of puncture rather than to the contrast medium or cerebral effects. For this reason, the selection of an appropriate needle system is important. A needle system consisting of a blunt tip cannula and a removable sharp central stylet is recommended. Another valuable addition is a guidewire that can be inserted into the needle and that will project a few centimeters beyond the tip with a flexible portion of wire. This allows threading of the needle into the carotid artery by holding the hub of the needle and will allow the guide to back out of the needle automatically if an obstruction is met. This will immediately tell the examiner to cease advancing and to take a test film to determine the position of the needle. An example of this system which we use is shown in Figure 1A. This is the Cook 18T needle and stylet and the guidewire specifically made for it. Disposable Teflon cannulas with an inner metal stylet have been prepared (Fig. 1B ) and these can also be handled and threaded using the same guidewire as with the metal cannula. Contrast Media
Discussion of the relative values of the various contrast media is beyond the scope of this article. The 29 per cent iodine compounds of Hypaque, Renografin, and Conray have all been used with satisfactory opacification and a minimum of complications.
TECHNIQUES
OF CEREBRAL
ANG~Of.SAPl%
9
Procedure The patient is supine on the table with his head extended. An inflatable balloon placed beneath the shoulders will help achieve extra extension. The carotid artery should be punctured below the bifurcation, which is roughly at the level of the upper border of the thyroid cartilage. If the vessel can be trapped between the index and middle fingers of one hand, it facilitates puncturing the vessel with the needle in the other hand. Detecting a thrill with the tips of the finger on a forceful push upon the needle helps to establish proper needle placement. The needle is then passed at an angle through both walls of the vessel and the stylet is removed. Slow withdrawal of the cannula will result in a good flow of blood if the needle is properly placed. Frequently, the first blood obtained is a slow trickle indicating that the cannula tip is against the posterior wall; a further pull of 1 or 2 mm. while elevating the tip of the cannula should give good ilow. At this point, the guidewire is gently inserted and, if it passes all the way to the hub without meeting an obstruction, the cannula is threaded into the artery by holding the hub without having the finger over the end of the guidewire. In younger patients, the cannula may be safely threaded several centimeters, whereas in older individuals, one may wish to thread only 1 or 2 cm. to avoid atherosclerotic plaques. A very important part of the procedure is the test injection for needle placement, which should always be done. Three or 4 cc. of contrast medium should be injected and a single lateral film taken. If rapid film processing is available, a standard film is used; without rapid processing, a Polaroid technique will give satisfactory information, One should be certain to have the needle visible on the test film and good filling of the common, internal, and external carot.id arteries should be seen. If evidence of an intimal tear is noted, careful attempts to reposition the needle should be made *before proceeding with the injections, However, with the technique described, it is rare to encounter subintimal injection of contrast medium. The test film also may have some diagnostic import, as one may detect evidence of atherosclerotic disease at the bifurcation. Selective injection of the internal or external carotid artery may occasionally be indicated. With proper puncture using the system described, the needle may be advanced either into the internal or external carotid artery after a test injection. Alternatively, catheter placement under fluoroscopy followed by selective internal or external catheterization may be performed.
Radiographic
Factors
A high ma three-phase generator allows for relatively low kv, high mas films, which will still be within the time limitations of the rapid film changer. This permits the average kv of the photons to be closer to the photoelectric absorption peak for iodine and will give better contrast with less unwanted scatter. However, it is not necessary to have this sophisticated equipment to produce good angiograms. Satisfactory angiograms may be made with 300 ma, single phase equipment as long as close attention is paid to the radiographic
10
GOLDMANANDHEINZ
factors. The use of extension cones will also greatly improve the quality of the radiographs. The standard angle for AP carotid arteriography is approximately 12” caudal to the canthomeatal line. This angulation will place the superior orbital rim and the upper border of the petrous bone at the same level. As much flexion of the chin as possible is worthwhile to allow as little tube angulation in relation to the film as possible. The less angulation, the less distortion. The sequencing should be such that films are obtained in the early and late arterial phases, the capillary phase, and the early and late venous phases. Our routine film sequence is two films per second for 2% to 3 seconds, and then one film per second for an additional 4 seconds. The first film usually contains no contrast and can be used for subtraction if this is indicated. This sequence will completely cover the circulation in most cases, but if the first injection shows delayed flow, subsequent film series should be timed accordingly. RETROGRADE BRACHIAL
ARTERIOGRAPHY
Retrograde brachial arteriography has a definite place in the armamentarium of neuroradiology and, when applied properly, can give high quality examinations. In certain situations, it may be the safest and most informative procedure. Right retrograde brachial arteriography may demonstrate the origin of the right common carotid artery, the origin of the right vertebral artery, the right carotid bifurcation, and the intracranial right carotid system as well as the posterior circulation. Statistics show that the left vertebral artery is significantly larger than the right in approximately 50 per cent of the patients, the two vertebral arteries are equal in size in about 25 per cent, and the remaining 25 per cent have a larger right vertebral artery. Based on these statistics, if one is interested in examining only the posterior fossa circulation, a retrograde left brachial arteriogram (which would naturally visualize only the left vertebral artery) would be preferable. However, this technique probably will not visualize the right posterior inferior cerebellar artery. If study of this vessel is also needed, simultaneous bibrachial injection can be used. Equipment
The tray for brachial arteriography is similar to that for carotid arteriography with a few exceptions. For brachial arteriography, a 16T cannula, solid stylet, and 16 gauge guidewire are used. Pressure resistant, radiolucent, flexible, polyethylene tubing which will withstand a bursting pressure of 400 to 500 mm. Hg is recommended as connecting tubing. The needle is threaded gently up to the hub, again making sure the guidewire does not back out. The needle is fixed to the skin with two adhesive strips crossing one another over the hub. This will adequately secure the needle and will obviate the need to sew it to the skin, as has been common practice, Contrast Injection
The contrast agent used is the same as that for carotid arteriography. On the right side, in adults, an injection of 60 cc. at the rate of 30 cc. per second for
TECHNIQUESOFCEREl3RALANGIOG~PHY
11
2 seconds, with a blood pressure cuff blown up on the forearm below the puncture site, will give excellent visualization of the intracranial carotid circulation in’ a high percentage of cases. This amount of contrast can be safely injected several times. On the left side, 40 to 50 cc. of contrast, again with the blood pressure cuff blown up below the needle, will usually give satisfactory posterior fossa studies. A power injector is needed for this examination, and most of the available injectors are satisfactory. We prefer the type that allows setting the amount of contrast instilled per second and the injection time rather than the ones that necessitate setting a definite pressure. The importance of obtaining a preliminary film of the arm with a hand injection of 5 to 6 cc. of contrast material is again stressed. One should be certain that the needle is within the lumen and that the hub is fixed to the skin in such a way that the axis of the needle is parallel to the axis of the artery. If there is marked angulation of the needle to the artery, the chances for a subintimal injection or a ruptured artery due to the high pressure injection are considerably increased. However, with satisfactory needle position as shown on the preliminary film, the chances of complications at the puncture site are minimal. The film sequence for brachial arteriography is the same as that for carotid arteriography, except that there should be a l-second delay in filming after the injection is started to allow for the contrast to travel from the arm to the head. Upon completion of the examination, the needle should be removed and broad pressure applied with the hand over the puncture site. One should be able to palpate the radial pulse while the pressure is being applied. CATHETERCEREBRALANGIOGRAPHY
Selective catheterization of the carotid and vertebral arteries via the femoral approach is now established as a major method of examining the cerebral circulation. Catheter angiography is particularly helpful when no localizing signs are present and several vessels must be visualized. This is also true in the case of subarachnoid hemorrhage from aneurysm or arteriovenous malformation where it is mandatory to study multiple vessels. Catheter angiography is the technique of choice in children whether for a single or multiple vessels, as it seems quite safe and is much less traumatic than direct carotid angiography. A patient with a tracheostomy or intubation may also be examined more easily by the femoral approach. Selective angiography becomes more difficult in the elderly, in whom extensive atherosclerosis and marked uncoiling of the aortic arch may make it difficult to adequately catheterize the individual vessels. Insertion of the catheter is by the standard Seldinger method. We prefer to buy rolls of barium-impregnated polyethylene tubing and to shape the tip of the catheter individually for each patient, depending on age and on the appearance of the aortic arch. In children under 4 years of age, a #4 French catheter is usually used; in older children a #5 French catheter is employed. In adults, a #5F or #6F catheter is preferred. In the younger individual, a
GOLDMAN
AND
HEINZ
Fig. 2.- Catheters for selective cerebral angiography. A. Straight barium~ impregnated polyethylene catheter with small bend
at tip. B. Double
curve
~ catheter of barium-impreg-
nated polyethylene. C and D. Cordis 1 and 3 “headhunter” catheters. straight catheter (except for a small bend at the tip) will usually suffice to enter all of the vessels (Fig. 2A). If a particular vessel is difficult, a double curve catheter (Fig. 2B) can be easily fashioned and will invariably allow catheterization of the desired vessel. In the occasional individual in whom catheterizing a vessel with the small polyethylene catheters is diihcult, the Cordis headhunter catheters (Fig. 2C, D), which have excellent torque, will usually succeed. The large size of these catheters makes them dangerous for selectively catheterizing a vertebral artery unless it is known to be large. In these cases, it may be advisable to inject the contrast medium into the subclavian artery adjacent to the vertebral orifice. In younger individuals, it is acceptable to perform angiography by selectively catheterizing the vertebral with a small catheter so long as one observes rapid washout
with
a test injection
under fluoroscopy.
The Teflon coated 125 cm. guidewires have proved very satisfactory in our experience. In older individuals, the removable core and J guidewires have been of help in negotiating markedly atherosclerotic vessels. After removal of the catheter, broad compression of the femoral artery puncture
site should
be applied,
but complete
occlusion
should
be avoided.
The procedure should only be performed on in-patients so that there may be proper observation of the patient and the puncture site for 24 hours following the examination.
13
TECHNIQUESOFCEREEJRALANGIOGRAFTIY FACTORS COMMON TO ALL METHODS OF CEREBRAL ANGI~CRAPHY
Regardless of the method of opacifying the cerebral vessels, the posStion of the head, the film sequence, and other radiographic factors are the same. One should make every effort to obtain high quality films. The patient’s level of consciousness, blood pressure, and respirations should be constantly monitored. If a patient becomes severely hypotensive, one should, of course, attend to this problem rather than continuing with attempts to visualize the intracranial vessels. Constant irrigation of the needles or catheters is important in all methods of examination. We use 4 to 5 cc. of a 1 to 1000 Heparin solution per 500 cc. saline. Frequent flushing may prevent thrombus formation within the needle and decrease the incidence of fibrin emboli. Many individuals find the use of a closed system for flushing with a bottle of intravenous saline connected to a stopcock to be preferable to the technique of drawing the solution from metal bowls on the table. Another method is the use of a high pressure infusion to provide a continuous drip into the arterial system between injections. SPECIAL TECHNIQUES
Magnification
Small focal spot tubes with a high heat capacity will allow magnification serial cerebral angiography. This may play an increasingly important role in evaluation of many of the small intracranial vessels. Subtraction
Subtraction films have been shown to increase the certainty and may actually provide the only diagnostic film.
of a diagnosis
Stereoscopic Films
Stereoscopic films, particularly in the lateral projection, for lesions in the posterior fossa as well as in the supratentorial compartment, have been used by many neuroradiologists.