Ultrasound
Gray-Scale Ultrasound Diagnosis of Peripheral Arterial Aneurysms 1 Harvey L. Neiman, M.D., James S.T. Yao, M.D., Ph.D., and Terry M. Silver, M.D. Diagnostic ultrasound is a feasible technique for demonstrating the presence of an aneurysm in the popliteal, femoral, iliac, and brachial arteries. All aneurysms were correctly identified and confirmed by arteriography, surgery, or examination of the amputated specimen. The popliteal artery in healthy volunteers had a mean size of 0.8 ± 0.2 em. Neither the age nor the sex of the patient influenced artery size. In patients with known abdominal aortic aneurysms or significant atherosclerosis, the popliteal size was within two standard deviations from the mean of normal popliteal arteries. Aneurysm, popliteal • Arteries, popliteal • Ultrasound, indications • (Vascular ultrasonography, 9.1298). (Arteries of lower extremity, ultrasonography, 9 [2] .1298) • (Arteries of lower limb, aneurysm, 9[2].730) • (Popliteal artery, aneurysm,
INDEX TERMS:
system,
9[24].730) Radiology 130:413-416, February 1979
I
arterial aneurysms usually present little problem in physical diagnosis; yet their presence is often unrecognized until complications, such as acute thrombosis or distal embolization, arise (1). This is particularly true of popliteal aneurysms, which account for 70 % of peripheral arterial aneurysms (2). Physical diagnosis of an atherosclerotic popliteal aneurysm may be difficult, especially in patients with generalized arterial ectasia or a thrombosed aneurysm. In patients with a false aneurysm that developed after trauma or reconstructive surgery, the surroundingedema or scar tissue may mask the aneurysm, making physical diagnosis difficult. Few reports have analyzed the potential diagnostic value of ultrasound in visualization of peripheral arteries (3-6). Defining the ultrasonographic appearance of normal peripheral arteries has received even less attention (3, 4). This study was undertaken to define the size of the normal popliteal artery by gray-scale ultrasound, and to evaluate the appearance of popliteal aneurysms. ARGE PERIPHERAL
L.
Fig. 1. Thirty-one-year-old asymptomatic woman with a normal popliteal artery (arrowheads).
arteries were first palpated and the area covered with a coupling agent. Transverse and longitudinal sequential scans were made a few millimeters apart until the entire vessel was demonstrated. Measurements of the normal popliteal arteries were made at the level of the popliteal fossa and 4 cm above and below this point on both transverse and longitudinal sections (Fig. 1). Aneurysms were measured at their maximum dimension. In all cases, the normal artery both proximal and distal to an aneurysm was demonstrated; an M-mode or real-time scan was also obtained. One hundred and twenty-five patients were examined and categorized according to the site of examination.
MATERIALS AND METHODS
Commercially available gray-scale equipment was used with either a 5-MHz, short internally focused transducer (7mm in diameter), or a 3.5-MHz medium internally focused transducer (13 mm in diameter). The time-gain compensation (TGC) curve was set with the knee at 3-6 cm in depth, depending on the individual's muscularity. For popliteal artery studies, patients were scanned in the prone position with a small pillow placed under their feet, allowing the knee to be slightly flexed. This facilitated scanning and also produced a more accurate anatomical representation, as the artery was not taut. Femoral vessels were studied with the patient supine, and brachial arteries were studied with the patient's arm neutrally extended. In all cases, the
Popliteal Artery The popliteal arteries were bilaterally examined in 102 individuals (204 arteries). Three groups of individuals (classified by their clinical presentation) were analyzed. Group I: This group consisted of healthy volunteers without signs or symptoms of vascular disease (Fig. 1). The
1 From the Department of Radiology (H.L.N.)and the Division of Vascular Surgery of the Department of Surgery (J.S.T.Y.), Northwestern University Medical School, Chicago, 111., and the Department of Radiology (T.M.S.), University of Michigan Medical School, Ann Arbor, Mich. Received Dec. 16, 1977; accepted and revision requested Feb. 27, 1978; revision received Sept. 14. jr
413
414
.
,
HARVEY
L.
NEIMAN AND OTHERS
February 1979
-I
•
"
Fig. 2. This 68-year-old man with a 5.2-cm abdominal aortic aneurysm had no symptoms of the lower extremities. The popliteal artery is normal and sharply marginated (arrowheads).
Fig. 4. A. Transverse section (left) through a 3.3-cm popliteal artery aneurysm shows low-level internal echoes which represent thrombus. B. Corresponding lower extremity arteriogram (right) demonstrates the residual lumen.
firmed peripheral arterial aneurysms. There were 19 patients with a total of 30 popliteal aneurysms.
Femoral and Iliac Arteries The iliac or femoral arteries were examined in 20 patients classified into two groups by anatomic site. Ten patients with femoral aneurysms were examined. There were 7 men and 3 women in this group, ranging in age from 57 to 74 years. Ten patients with iliac aneurysms were also studied.
Brachial Artery Three patients with traumatic false aneurysms of the brachial artery were examined. There were 2 women and 1 man in this group. Fig. 3. A 4.4-cm popliteal artery aneurysm is demonstrated, with the artery both proximal and distal to it (small arrowheads). The large arrowhead points to intraluminal thrombus.
46 individuals ranged in age from 17 to 47 years. Twenty-seven were male, and 19 were female. A total of 92 arteries were examined. Group 1/: This group consisted of individualswith known abdominal aortic aneurysms or significant atherosclerosis. All patients had arteriographic examination and ranged in age from 58 to 79 years (Fig. 2). There were 29 men and 8 women. Seventy-four arteries were examined. Group 11/: This group consisted of patients with con-
RESULTS
Popliteal Artery The mean arterial size in Group I was 0.8 ± 0.2 em. There were 23 individuals from 17 to 32 years and similarly 23 adults from 32 to 47 years. Neither the age nor the sex of the patient influenced arterial size. All patients in Group II had arteriographic examinations. The size of their popliteal arteries fell within two standard deviations of the mean set by Group I. All aneurysms in Group III were correctly identified by ultrasound and confirmed by arteriography, surgery, or examination of the amputated specimen. By ultrasound, the popliteal aneurysms ranged in ventral dorsal dimen-
Vol. 130
DIAGNOSIS OF PERIPHERAL ARTERIAL ANEURYSMS
415
Ultrasound
sions from 1.2 to 8 cm. The transverse dimension ranged in size from 1.5 to 8 cm (Fig. 3). The 8-cm aneurysmal lesion was approximately 60 % filled with thrombus. Varying amounts of thrombus were identified in 16 of the 30 aneurysms (Fig. 4). Residual lumen in those patients with an aneurysm and thrombus, but without complete occlusion, was also determined and ranged from 0.75 to 1.4 ern, for a mean residual luminal size of 1.075 cm. Popliteal aneurysms were not visualized by angiography in 5 patients because of proximal occlusion or thrombosed aneurysms. Eleven of the 19 patients (63 % ) had bilateral aneurysms. An additional 8 patients were clinically suspected of having unilateral or bilateral popliteal aneurysms. Ultrasonography, however, excluded the clinical diagnosis in these patients; thus they were placed in Group II.
Femoral and Iliac Arteries
Fig. 5. Longitudinal (left) and transverse (right) sections through a 5.S-cm iliac artery aneurysm (large arrowheads) are shown. A minimal amount of thrombus was noted (small arrowheads).
The femoral aneurysms examined ranged in size from 2.0 to 5.7 cm by ultrasoundevaluation. The iliac aneurysms were often distal extensions of an aorto-iliac aneurysm and ranged from 3.5 to 7.2 cm (Fig. 5).
Brachial Arteries In the 3 patients with traumatic false aneurysms, aneurysm size ranged from 1.2 to 4 cm. Gray-scale ultrasound demonstrated the presence of thrombosis within an aneurysm as an area of low-level internal echoes (Figs. 3 and 4). Calcification in the arterial wall appeared as a dense, high-level echoqenk band.
DISCUSSION
Several reports have demonstrated the usefulness of gray-scale ultrasound in the diagnosis of popliteal aneurysms (3-7). In a pilot study, we evaluated the normal femoral and popliteal artery size by ultrasound scanning (4). In contrast to the pilot study, we have found the normal popliteal artery size to be 0.8 ± 0.2 cm, rather than 0.9 ± 0.2 cm (Figs. 1 and 2). The difference in sizes is probably related to the larger patient sample in the present study and the use of higher-frequency transducers which allow for improved resolution. The size of the popliteal artery agrees with that measured at operation, estimated to be 0.6-0.8 cm. The size of the normal popliteal artery is also in close agreement with that of Collins et al. who reported a figure of 0.78 ± 0.14 cm (3). In our pilot study,the normal femoral artery size was found to be 1.0 ± 0.3 cm in younger individuals, and 1.2 ± 0.3 cm in older individuals (4). All 30 patients with confirmed popliteal aneurysms were correctly identified by ultrasonography. The scan was also able to detect thrombus within the aneurysm by the presence of internal echoes. Embolization to the distal arterial tree is a well-known complication of popliteal aneurysms. When such a clinical presentation is seen, a search for the presence of popliteal or femoral aneurysm must be made;
Fig. 6. A 2.8-cm false aneurysm of the femoral artery secondary to an arteriographic procedure is shown. Note the excellent demonstration of the displaced superficial femoral artery (arrowhead) and deep femoral artery (arrowhead).
the ultrasound scan appears to be a convenient way to locate a possible source of emboli. The finding of thrombus within a popliteal aneurysm constitutes an indication for surgical intervention, regardless of lesion size. In this series, 16 out of 30 popliteal aneurysms contained thrombus, and femoropopliteal artery bypass with aneurysm exclusion (proximal and distal ligation) was done to prevent further embolization. An advantage of diagnostic ultrasound over arteriography is its ability to establish the diagnosis of a thrombosed popliteal aneurysm or an aneurysm with proximal occlusion. Arteriography in these situations will not be helpful because of the absence of contrast material filling the aneurysm. Ultrasound provides the only imaging technique to establish the diagnosis. In this series, popliteal aneurysms were not visualized by angiography in 5 patients because of proximal occlusion or thrombosed aneurysm. Since popliteal aneurysms are bilateral in approximately half of the cases (2,8) and multiple aneurysms in the same
416
DIAGNOSIS OF PERIPHERAL ARTERIAL ANEURYSMS
LATERAL
Fig. 7. Anatomy of the posterior aspect of the popliteal fossa is shown. For most of its course in the fossa, the popliteal artery lies medial to the vein.
February 1979
suspected aneurysm. This maneuver simplifies the differentiation of a popliteal cyst from an aneurysm (9, 10). In addition, A-mode, M-mode, or real-time ultrasonography confirms the vascular nature of the lesion and its continuity with the popliteal artery. Computed tomography of the body can also visualize peripheral arteries, but appears to be of no advantage in this setting. High-resolution real-time ultrasound scanning of the carotid artery is now feasible, and similar instrumentation may prove valuable in other peripheral arterial locations (11). Since popliteal aneurysms present a serious threat to limb survival, every effort must be made to identify them. As demonstrated in the present study, ultrasound is an accurate, noninvasive means of establishing diagnosis. When reconstructive surgery is contemplated, the use of arteriography remains a necessity because ultrasound does not provide information on the distal vascular anatomy. In patients with acute femoropopliteal artery occlusion, but without a history of claudication or cardiac source of emboli, diagnosis by ultrasound may assist in establishing the presence ofa thrombosed popliteal aneurysm as the cause of ischemia. Department of Radiology Northwestern Memorial Hospital Superior S1. and Fairbanks C1. Chicago, III. 60611
REFERENCES patient is not uncommon, the presence of a popliteal aneurysm would suggest evaluation of other sites. The fact that 63 % of the patients in this series had bilateral aneurysms emphasizes the importance of studying both popliteal fossae. In false aneurysms, clinical diagnosis may be difficult, particularly when there is a penetrating wound or surrounding edema. In this series, all false aneurysms were correctly detected by ultrasound (Fig. 6). In the patients with femoral or brachial artery false aneurysms, the ultrasonograms correlated with arteriographic and operative findings. Upon evaluating a peripheral artery, one must carefully consider the normal anatomy. The popliteal vein is in close apposition to the artery and may simulate the popliteal artery in its course and caliber. As the popliteal fossa is traversed from cephalad to caudad, the popliteal vein first lies lateral to the artery; it then crosses dorsally and comes to lie medial to the artery (Fig. 7). Just proximal to the arterial trifurcation, the vein is medial to the artery. When a popliteal aneurysm is suspected, great care must be taken to demonstrate the vessel both proximal and distal to the
1. Towne JB, Thompson JE, Patman DO, et al: Progression of popliteal aneurysmal disease following popliteal aneurysm resection with graft: a twenty year experience. Surgery 80:426-432, Oct
1976 2. Wychulis AR, Spittel! JA Jr, Wallace RB: Popliteal aneurysms. Surgery 68:942-952, Dec 1970 3. Collins GJ Jr, Rich NM, Phillips J, et al: Ultrasound diagnosis of popliteal arterial aneurysms. Am Surg 42:853-858, Nov 1976 4. Davis RP, Neiman HL, Yao JST, et al: Ultrasound scan in diagnosis of peripheral aneurysms. Arch Surg 112:55-58, Jan 1977 5. Sarti DA, Louie JS, Lindstrom RR, et al: Ultrasonic diagnosis of a popliteal artery aneurysm. Radiology 121:707-708, Dec 1976 6. Scott WW Jr, Scott PP, Sanders RC: B-scan ultrasound in the diagnosis of popliteal aneurysms. Surgery 81: 436-441, Apr 1977 7. Silver TM, Washburn RL, Stanley JC, et al: Gray scale ultrasound evaluation of popliteal artery aneurysms. Am J Roentgenol 129: 1003-1006, Dec 1977 8. Dent TL, Lindenauer SM, Ernst CB, et al: Multiple arteriosclerotic arterial aneurysms. Arch Surg 105:338-344, Aug 1972 9. Carpenter JR, Hattery RR, Hunder GG, et al: Ultrasound evaluation of popliteal space. Comparison with arthrography and physical examination. Mayo Clin Proc 51:498-503, Aug 1976 10. Moore CP, Sarti DA, Louie JS: Ultrasonographicdemonstration of popliteal cysts in rheumatoid arthritis. A noninvasive technique. Arthritis Rheum 18:577-580, Nov-Dec 1975 11. Barber FE, Baker OW, Nation AWC, et al: Ultrasonic duplex echo-Doppler scanner. IEEE Trans Biomed Eng 21:109-113, Mar
1974
Gray-Scale Ultrasound Diagnosis of Peripheral Arterial Aneurysms 1 Harvey L. Neiman, M.D., James S.T. Yao, M.D., Ph.D., and Terry M. Silver, M.D. Diagnostic ultrasound is a feasible technique for demonstrating the presence of an aneurysm in the popliteal, femoral, iliac, and brachial arteries. All aneurysms were correctly identified and confirmed by arteriography, surgery, or examination of the amputated specimen. The popliteal artery in healthy volunteers had a mean size of 0.8 ± 0.2 em. Neither the age nor the sex of the patient influenced artery size. In patients with known abdominal aortic aneurysms or significant atherosclerosis, the popliteal size was within two standard deviations from the mean of normal popliteal arteries. Aneurysm, popliteal • Arteries, popliteal • Ultrasound, indications • (Vascular ultrasonography, 9.1298). (Arteries of lower extremity, ultrasonography, 9 [2] .1298) • (Arteries of lower limb, aneurysm, 9[2].730) • (Popliteal artery, aneurysm,
INDEX TERMS:
system,
9[24].730) Radiology 130:413-416, February 1979
I
arterial aneurysms usually present little problem in physical diagnosis; yet their presence is often unrecognized until complications, such as acute thrombosis or distal embolization, arise (1). This is particularly true of popliteal aneurysms, which account for 70 % of peripheral arterial aneurysms (2). Physical diagnosis of an atherosclerotic popliteal aneurysm may be difficult, especially in patients with generalized arterial ectasia or a thrombosed aneurysm. In patients with a false aneurysm that developed after trauma or reconstructive surgery, the surroundingedema or scar tissue may mask the aneurysm, making physical diagnosis difficult. Few reports have analyzed the potential diagnostic value of ultrasound in visualization of peripheral arteries (3-6). Defining the ultrasonographic appearance of normal peripheral arteries has received even less attention (3, 4). This study was undertaken to define the size of the normal popliteal artery by gray-scale ultrasound, and to evaluate the appearance of popliteal aneurysms. ARGE PERIPHERAL
L.
Fig. 1. Thirty-one-year-old asymptomatic woman with a normal popliteal artery (arrowheads).
arteries were first palpated and the area covered with a coupling agent. Transverse and longitudinal sequential scans were made a few millimeters apart until the entire vessel was demonstrated. Measurements of the normal popliteal arteries were made at the level of the popliteal fossa and 4 cm above and below this point on both transverse and longitudinal sections (Fig. 1). Aneurysms were measured at their maximum dimension. In all cases, the normal artery both proximal and distal to an aneurysm was demonstrated; an M-mode or real-time scan was also obtained. One hundred and twenty-five patients were examined and categorized according to the site of examination.
MATERIALS AND METHODS
Commercially available gray-scale equipment was used with either a 5-MHz, short internally focused transducer (7mm in diameter), or a 3.5-MHz medium internally focused transducer (13 mm in diameter). The time-gain compensation (TGC) curve was set with the knee at 3-6 cm in depth, depending on the individual's muscularity. For popliteal artery studies, patients were scanned in the prone position with a small pillow placed under their feet, allowing the knee to be slightly flexed. This facilitated scanning and also produced a more accurate anatomical representation, as the artery was not taut. Femoral vessels were studied with the patient supine, and brachial arteries were studied with the patient's arm neutrally extended. In all cases, the
Popliteal Artery The popliteal arteries were bilaterally examined in 102 individuals (204 arteries). Three groups of individuals (classified by their clinical presentation) were analyzed. Group I: This group consisted of healthy volunteers without signs or symptoms of vascular disease (Fig. 1). The
1 From the Department of Radiology (H.L.N.)and the Division of Vascular Surgery of the Department of Surgery (J.S.T.Y.), Northwestern University Medical School, Chicago, 111., and the Department of Radiology (T.M.S.), University of Michigan Medical School, Ann Arbor, Mich. Received Dec. 16, 1977; accepted and revision requested Feb. 27, 1978; revision received Sept. 14. jr
413
414
.
,
HARVEY
L.
NEIMAN AND OTHERS
February 1979
-I
•
"
Fig. 2. This 68-year-old man with a 5.2-cm abdominal aortic aneurysm had no symptoms of the lower extremities. The popliteal artery is normal and sharply marginated (arrowheads).
Fig. 4. A. Transverse section (left) through a 3.3-cm popliteal artery aneurysm shows low-level internal echoes which represent thrombus. B. Corresponding lower extremity arteriogram (right) demonstrates the residual lumen.
firmed peripheral arterial aneurysms. There were 19 patients with a total of 30 popliteal aneurysms.
Femoral and Iliac Arteries The iliac or femoral arteries were examined in 20 patients classified into two groups by anatomic site. Ten patients with femoral aneurysms were examined. There were 7 men and 3 women in this group, ranging in age from 57 to 74 years. Ten patients with iliac aneurysms were also studied.
Brachial Artery Three patients with traumatic false aneurysms of the brachial artery were examined. There were 2 women and 1 man in this group. Fig. 3. A 4.4-cm popliteal artery aneurysm is demonstrated, with the artery both proximal and distal to it (small arrowheads). The large arrowhead points to intraluminal thrombus.
46 individuals ranged in age from 17 to 47 years. Twenty-seven were male, and 19 were female. A total of 92 arteries were examined. Group 1/: This group consisted of individualswith known abdominal aortic aneurysms or significant atherosclerosis. All patients had arteriographic examination and ranged in age from 58 to 79 years (Fig. 2). There were 29 men and 8 women. Seventy-four arteries were examined. Group 11/: This group consisted of patients with con-
RESULTS
Popliteal Artery The mean arterial size in Group I was 0.8 ± 0.2 em. There were 23 individuals from 17 to 32 years and similarly 23 adults from 32 to 47 years. Neither the age nor the sex of the patient influenced arterial size. All patients in Group II had arteriographic examinations. The size of their popliteal arteries fell within two standard deviations of the mean set by Group I. All aneurysms in Group III were correctly identified by ultrasound and confirmed by arteriography, surgery, or examination of the amputated specimen. By ultrasound, the popliteal aneurysms ranged in ventral dorsal dimen-
Vol. 130
DIAGNOSIS OF PERIPHERAL ARTERIAL ANEURYSMS
415
Ultrasound
sions from 1.2 to 8 cm. The transverse dimension ranged in size from 1.5 to 8 cm (Fig. 3). The 8-cm aneurysmal lesion was approximately 60 % filled with thrombus. Varying amounts of thrombus were identified in 16 of the 30 aneurysms (Fig. 4). Residual lumen in those patients with an aneurysm and thrombus, but without complete occlusion, was also determined and ranged from 0.75 to 1.4 ern, for a mean residual luminal size of 1.075 cm. Popliteal aneurysms were not visualized by angiography in 5 patients because of proximal occlusion or thrombosed aneurysms. Eleven of the 19 patients (63 % ) had bilateral aneurysms. An additional 8 patients were clinically suspected of having unilateral or bilateral popliteal aneurysms. Ultrasonography, however, excluded the clinical diagnosis in these patients; thus they were placed in Group II.
Femoral and Iliac Arteries
Fig. 5. Longitudinal (left) and transverse (right) sections through a 5.S-cm iliac artery aneurysm (large arrowheads) are shown. A minimal amount of thrombus was noted (small arrowheads).
The femoral aneurysms examined ranged in size from 2.0 to 5.7 cm by ultrasoundevaluation. The iliac aneurysms were often distal extensions of an aorto-iliac aneurysm and ranged from 3.5 to 7.2 cm (Fig. 5).
Brachial Arteries In the 3 patients with traumatic false aneurysms, aneurysm size ranged from 1.2 to 4 cm. Gray-scale ultrasound demonstrated the presence of thrombosis within an aneurysm as an area of low-level internal echoes (Figs. 3 and 4). Calcification in the arterial wall appeared as a dense, high-level echoqenk band.
DISCUSSION
Several reports have demonstrated the usefulness of gray-scale ultrasound in the diagnosis of popliteal aneurysms (3-7). In a pilot study, we evaluated the normal femoral and popliteal artery size by ultrasound scanning (4). In contrast to the pilot study, we have found the normal popliteal artery size to be 0.8 ± 0.2 cm, rather than 0.9 ± 0.2 cm (Figs. 1 and 2). The difference in sizes is probably related to the larger patient sample in the present study and the use of higher-frequency transducers which allow for improved resolution. The size of the popliteal artery agrees with that measured at operation, estimated to be 0.6-0.8 cm. The size of the normal popliteal artery is also in close agreement with that of Collins et al. who reported a figure of 0.78 ± 0.14 cm (3). In our pilot study,the normal femoral artery size was found to be 1.0 ± 0.3 cm in younger individuals, and 1.2 ± 0.3 cm in older individuals (4). All 30 patients with confirmed popliteal aneurysms were correctly identified by ultrasonography. The scan was also able to detect thrombus within the aneurysm by the presence of internal echoes. Embolization to the distal arterial tree is a well-known complication of popliteal aneurysms. When such a clinical presentation is seen, a search for the presence of popliteal or femoral aneurysm must be made;
Fig. 6. A 2.8-cm false aneurysm of the femoral artery secondary to an arteriographic procedure is shown. Note the excellent demonstration of the displaced superficial femoral artery (arrowhead) and deep femoral artery (arrowhead).
the ultrasound scan appears to be a convenient way to locate a possible source of emboli. The finding of thrombus within a popliteal aneurysm constitutes an indication for surgical intervention, regardless of lesion size. In this series, 16 out of 30 popliteal aneurysms contained thrombus, and femoropopliteal artery bypass with aneurysm exclusion (proximal and distal ligation) was done to prevent further embolization. An advantage of diagnostic ultrasound over arteriography is its ability to establish the diagnosis of a thrombosed popliteal aneurysm or an aneurysm with proximal occlusion. Arteriography in these situations will not be helpful because of the absence of contrast material filling the aneurysm. Ultrasound provides the only imaging technique to establish the diagnosis. In this series, popliteal aneurysms were not visualized by angiography in 5 patients because of proximal occlusion or thrombosed aneurysm. Since popliteal aneurysms are bilateral in approximately half of the cases (2,8) and multiple aneurysms in the same
416
DIAGNOSIS OF PERIPHERAL ARTERIAL ANEURYSMS
LATERAL
Fig. 7. Anatomy of the posterior aspect of the popliteal fossa is shown. For most of its course in the fossa, the popliteal artery lies medial to the vein.
February 1979
suspected aneurysm. This maneuver simplifies the differentiation of a popliteal cyst from an aneurysm (9, 10). In addition, A-mode, M-mode, or real-time ultrasonography confirms the vascular nature of the lesion and its continuity with the popliteal artery. Computed tomography of the body can also visualize peripheral arteries, but appears to be of no advantage in this setting. High-resolution real-time ultrasound scanning of the carotid artery is now feasible, and similar instrumentation may prove valuable in other peripheral arterial locations (11). Since popliteal aneurysms present a serious threat to limb survival, every effort must be made to identify them. As demonstrated in the present study, ultrasound is an accurate, noninvasive means of establishing diagnosis. When reconstructive surgery is contemplated, the use of arteriography remains a necessity because ultrasound does not provide information on the distal vascular anatomy. In patients with acute femoropopliteal artery occlusion, but without a history of claudication or cardiac source of emboli, diagnosis by ultrasound may assist in establishing the presence ofa thrombosed popliteal aneurysm as the cause of ischemia. Department of Radiology Northwestern Memorial Hospital Superior S1. and Fairbanks C1. Chicago, III. 60611
REFERENCES patient is not uncommon, the presence of a popliteal aneurysm would suggest evaluation of other sites. The fact that 63 % of the patients in this series had bilateral aneurysms emphasizes the importance of studying both popliteal fossae. In false aneurysms, clinical diagnosis may be difficult, particularly when there is a penetrating wound or surrounding edema. In this series, all false aneurysms were correctly detected by ultrasound (Fig. 6). In the patients with femoral or brachial artery false aneurysms, the ultrasonograms correlated with arteriographic and operative findings. Upon evaluating a peripheral artery, one must carefully consider the normal anatomy. The popliteal vein is in close apposition to the artery and may simulate the popliteal artery in its course and caliber. As the popliteal fossa is traversed from cephalad to caudad, the popliteal vein first lies lateral to the artery; it then crosses dorsally and comes to lie medial to the artery (Fig. 7). Just proximal to the arterial trifurcation, the vein is medial to the artery. When a popliteal aneurysm is suspected, great care must be taken to demonstrate the vessel both proximal and distal to the
1. Towne JB, Thompson JE, Patman DO, et al: Progression of popliteal aneurysmal disease following popliteal aneurysm resection with graft: a twenty year experience. Surgery 80:426-432, Oct
1976 2. Wychulis AR, Spittel! JA Jr, Wallace RB: Popliteal aneurysms. Surgery 68:942-952, Dec 1970 3. Collins GJ Jr, Rich NM, Phillips J, et al: Ultrasound diagnosis of popliteal arterial aneurysms. Am Surg 42:853-858, Nov 1976 4. Davis RP, Neiman HL, Yao JST, et al: Ultrasound scan in diagnosis of peripheral aneurysms. Arch Surg 112:55-58, Jan 1977 5. Sarti DA, Louie JS, Lindstrom RR, et al: Ultrasonic diagnosis of a popliteal artery aneurysm. Radiology 121:707-708, Dec 1976 6. Scott WW Jr, Scott PP, Sanders RC: B-scan ultrasound in the diagnosis of popliteal aneurysms. Surgery 81: 436-441, Apr 1977 7. Silver TM, Washburn RL, Stanley JC, et al: Gray scale ultrasound evaluation of popliteal artery aneurysms. Am J Roentgenol 129: 1003-1006, Dec 1977 8. Dent TL, Lindenauer SM, Ernst CB, et al: Multiple arteriosclerotic arterial aneurysms. Arch Surg 105:338-344, Aug 1972 9. Carpenter JR, Hattery RR, Hunder GG, et al: Ultrasound evaluation of popliteal space. Comparison with arthrography and physical examination. Mayo Clin Proc 51:498-503, Aug 1976 10. Moore CP, Sarti DA, Louie JS: Ultrasonographicdemonstration of popliteal cysts in rheumatoid arthritis. A noninvasive technique. Arthritis Rheum 18:577-580, Nov-Dec 1975 11. Barber FE, Baker OW, Nation AWC, et al: Ultrasonic duplex echo-Doppler scanner. IEEE Trans Biomed Eng 21:109-113, Mar
1974
