The use of scintiangiography with technetium 99m in the diagnosis of traumatic pseudoaneurysm

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1 The use of scintiangiography with technetium 99m in the diagnosis of traumatic pseudoaneurysm Michael E. Hayek, M.D., Mark A. Ludwig, M,D., Keith Fischer, M.D., and Cheryl Sisler, M.D., St. Louis, Mo. Pseudoaneurysm formation is a known complication of peripheral arterial access procedures. Although standard contrast angiography has been considered the diagnostic study of choice to identify pseudoaneurysms, isotope angiography has been described as an alternative method. In this study, we examined the role of 99~Tc-tagged red blood cell scans in the diagnosis of traumatic pseudoanem'ysm. Forty patients underwent scans; 25 scans were reported as abnormal and 15 as normal. There were no false-negative results; one scan had false-positive results (2.5%). The presence of pseudoaneurysm among the patients with abnormal scans was verified at operation in 23 of 25 patients. The one falsepositive test was verified by ultrasound. All patients with normal scans were followed up for verification. Follow-up time ranged from 2 to 28 months. Radionuclide vascular flow study appears to give information similar to that of conventional angiography. With a series false-positive rate of 2.5%, the examination has a high specificity. The 99"Tc-tagged red blood cell scan is a viable alternative to conventional angiography for the diagnosis of traumatic pseudoaneurysms and is associated with less radiation and morbidity. (J VAsc SuRG 1988;7:409-i3.) Pseudoaneurysm formation after arterial puncture is a recognized complication of procedures that use peripheral arterial access with large-bore catheters1; these procedures include cardiac catheterization, other angiographic techniques, and placement of intra-aortic balloon pumps (IABPs). Known sequelae of such aneurysms include arterial rupture, ischemia, pain, paralysis of the involved extremity, and embolization. Early diagnosis and treatment are essential. 1,2 Standard contrast angiography has been the diagnostic study of choice. The major risks include bleeding from the puncture site, perforation of major vessels, and renal insufficiency. Isotope angiography has been previously described as a possible alternative for the diagnosis of pseudoaneurysm. 3 W;e present our experience with technetium 99m (99mTc)~-labeled red blood cells (RBCs) for the detection of pseudoaneurysm resulting from arterial puncture. METHODS Forty patients with a tentative diagnosis of pseudoaneurysm at a site of arterial puncture were re- From the Departments of Surgery (Drs. Hayek and Ludwig) and Radiology (Drs. Fischer and Sisler), The Jewish Hospital of St. Louis at Washington University Medical Center. Reprint requests: Michael E. Hayek, M.D., Department of Surgery, The Jewish Hospital of St. Louis, St. Louis, MO ferred to the Vascular Surgery Service at The Jewish Hospital of St. Louis between March 1984 and October There were 23 women and 17 men. The age of the patients ranged from 59 to 88 years of age (mean 74 years). The procedures performed included cardiac catheterization, balloon angioplasty, or placcment of an intra-aortic balloon pump (IABP). Information about the patient included the admitting diagnosis, reason for the procedure, date of the procedure, and the vessel used for the procedure. Also obtained was information concerning the initial presentation of the suspected pseudoaneurysm. Thc questions included presencc or absence of pain, hematoma, pulsatilc mass, and function and sensation of the distal portion of the extremity. Physical examination was performed on all the patients and findings concerning the injury site and the neurovascular status of the distal portion of the extremity were documented. After initial evaluation, all patients underwent a 99roTe-labeled R_BC vascular flow study. The patient's RBCs were labeled by the modified in vivo method. Twenty minutes after injection of stannous pyrophosphate, 7 ml of blood was drawn into a syringe containing heparin and 25 mci of 99rnTc. The syringe was gently shaken periodically to promote mixing during the next i0 minutes. Reinjection of the la- 409

2 410 Hayek et al. Journal of VASCULAR SURGERY R ANT L I0 12 :(i:!/711)! i!i;i: ~:,, 14 i6 18 Fig. 1A. Scan (99~Fc-labeled red blood cell scan) of the lower extremities shows abnormal collection of activity over the right common femoral artery: dynamic image. This is consistent with the diagnosis ofa pseudoaneurysm. beled blood was performed with rapid sequential 1.5-second images obtained by a gamma camera positioned over the femoral arteries. This was followed by immediate static images and static images taken 20 minutes later. A complete imaging set consisted of a direct anterior projection as well as both anterior oblique projections to better visualize the collection of activity in the pseudoaneurysm. The diagnosis of pseudoaneurysm was made when a focus of activity was detected over the groin on the flow images and this focus could be seen to connect with the femoral vessel on the oblique views (Figs. 1A and 1B). With one exception, no other radiographic or noninvasive procedure was used to verify these results. The 25 patients with abnormal scans underwent operative repair with two exceptions. One patient was observed for eventual resolution. The other patient had ultrasound examination of the area; no abnormality was found. The possibility ofpseudoaneurysm was eliminated at this point, and the patient was referred back to her private physician for follow-up. Twenty-three of 25 patients (92%) with abnormal scans underwent operative repair, which con- sisted of closure of the defect with simple stitches after proximal and distal control of the vessel was obtained. Anesthesia used was either general or local with anesthesia standby of 1% xylocaine. Patients were examined by the attending vascular surgeon involved. The follow-up period ranged from 2 to 28 months. Any complications were noted. RESULTS Pseudoaneurysm was identified in 39 of 40 patients (97.5%) after cardiac catheterization and in one patient (2.5%) after placement of an IABP. Six of the 40 patients (15%) who had cardiac catheterization had subsequent transluminal balloon angioplasty. The site of arterial puncture reflected the standard operating procedures of the investigation. The right groin was involved in 37 of 40 procedures (92.5%/ with the left groin used in the other three (75%). All abnormal scan results involved the right groin puncture, Twenty-five of 40 vascular flow scans were interpreted as abnormal with the remaining 15 interpreted as normal. A scan was declared abnormal if there was evidence of contrast uptake outside the normal vasculature on both the dynamic and static portions of the examination. Patients who had normal studies were followed up for a period ranging from 2 to 28 months. There were no false-negative results noted in this study. However, a pseudoaneurysm was found in one patient more than 2 months after a normal vascular flow study. A 68-year-old woman underwent cardiac catheterization via the right groin. Right groin pain then developed with a large area ofecchymosis and a ques. tionable pulsatile mass. A 99mTc-tagged RBC study was performed for suspected pseudoaneurysm; results were normal. The patient did well without evidence of sequelae and was discharged from the hospital. At a 2-month follow-up examination, there was no evidence ofpseudoaneurysm formation. Two days after this examination, the patient returned with acute onset of right groin pain and a new right groin mass that was tender and ecchymotic. A radionuclide vascular flow study was obtained that was interpreted as showing pseudoaneurysm; this was verified at operation. A defect less than 0.5 cm was discovered in the right superficial femoral artery. This was repaired in the usual fashion. No other incidences have been reported in follow-up of the other 12 normal studies. It should be noted that this particular patient was

3 Volume 7 Number 3 March mTc-tagged scintiangiography to diagnose pseudoaneurysm 4 11 R RAO L R R RAO L Fig. lb. Scan (99mTc-labeled red blood cell scan) of the lower extremities shows collection of activity as in Fig. 1A: static images. given warfarin (Coumadin) for anticoagulation because of chronic atrial fibrillation. Of the 25 patients with abnormal scans, 23 pseudoaneurysms (92%) were verified at exploration and were repaired in the standard fashion. One of the two patients with abnormal scans who did not undergo operation is considered to be a false positive. This patient is a 72-year-old woman who, after cardiac catheterization, continued to have right groin pain, tenderness, and a large ecchymotic area. A vascular flow study was interpreted as abnormal. A subsequent ultrasound examination of the area did not verify the presence of a pseudoaneurysm. The patient was followed up for 16 months with periodic examinations and no new evidence of pseudoaneurysm. The second patient with an abnormal scan that was not verified at operation was a 68-year-old woman who had groin pain after cardiac catheterization. Physical examination revealed tenderness, ecchymosis, and a possible pulsatile mass in the area of the catheter puncture site. A vascular flow study was interpreted as indicative of pseudoaneurysm. It was elected to manage the patient conservatively with periodic examination. The mass had disappeared at 6-month follow-up. It was assumed that the pseudoaneurysm had resolved. The patient has had no difficulty since that time. The overall false-positive rate is 2.5% (1 of 40 patients). DISCUSSION Angiographic procedures such as contrast angiography and cardiac catheterization carry a risk of injury to the arterial wall. Among the more serious complications are bleeding, embolization, arteriovenous fistulas, and pseudoaneurysms) '2 This particular study dealt with the diagnosis of pseudoaneurysm formation as a complication of invasive angiographic procedures. These procedures are performed with large-bore catheters via a percutaneous modified Seldinger technique. This technique carries a significant risk of creating an arteriotomy that will not spontaneously close, this despite adequate direct pressure over the puncture site when the procedure was completed? Early recognition and diagnosis of a pseudoaneurysm are necessary to prevent the late complications of this problem. These include thrombosis, rupture, embolization, and infection.1 Diagnosis is initially made on clinical grounds.

4 412 Hayek et al. Journal of VASCULAR SURGERY Most patients have had traumatic invasion of the artery followed by a painful mass with a tender ecchymotic area. Evidence of distal ischemia may or may not be present. The current accepted method of examination is contrast angiography, which carries well-known risks, including exacerbation of any present renal insufficiency. Other methods include CT scan, ultrasound, digital subtraction angiography, and radionuclide angiography? CT scans have been used previously in the diagnosis of selected abdominal pseudoaneurysms. The limitations of digital selected angiography include the inability to delineate the borders of a pseudoaneurysm with thrombus present. 4's The use of radionuclide angiography to diagnose pseudoaneurysm has been described previously. Salles and MacDonald 6 described the use of the 99roTe-tagged RBC flow studies in the diagnosis of pseudoaneurysms. They reported two cases of false aneurysms identified by this technique. Both of these pseudoaneurysms were verified by standard contrast angiography. 7 Powers et al.8 used radionuclide angiography in a 62-year-old dialysis patient to determine whether a mass seen after bone marrow aspiration was cellulitis or osteomyelitis. Dynamic and static image s revealed a mass lateral to the left femoral artery. Sonography and contrast angiography revealed this to be a false aneurysm, which was verified at operation. 8 A recent letter by Rudavsky and Moss 9 described a series of 47 patients with suspected arterial trauma who underwent emission angiography. They found that the scans were 100% successful in the detection of an arterial injury when compared with other diagnostic modalities. Overall specificity was found to be 81%. 9 Moss, Rudavsky, and Veith 1 reported their experience with radionuclide arterial imaging on 200 patients, using 253 scans. These patients were divided into three groups: uncorroborated, validated, and clinical studies. In the validated studies, 20 scintiangiograms that were interpreted as normal were verified as such by contrast angiography. Seventythree studies were interpreted as abnormal with only one false-positive scan. A single case of postoperative pseudoaneurysm diagnosed by scintiangiography was verified by contrast angiography. 1 Moss, Rudavsky, and Moss u examined 100 patients with 100 penetrating wounds by isotope angiography. Ninety-six scans were divided into validation and clinical series groups. In the validation group, 20 studies interpreted as normal were verified whereas the 27 abnormal scans revealed five falsepositive results (19%). In the clinical series, no falsepositive results were noted. The authors recommend isotope angiography as the initial study in suspected arterial trauma. A normal study assures that there is no arterial injury; they recommend that contrast angiography be'employed after abnormal results, u Moss, Rudavsky, and Veith 12 reviewed 167 scintiangiograms and have recommended this method be used to evaluate vascular reconstructions postoperatively. Ertzner and Powers 3 reported four cases ofpseudoaneurysm diagnosed with 99mTc-tagged RBCs and ultrasound. They describe this as a principal means to exclude patients with a noncommunicating hematoma from unnecessary contrast angiography. When this method is compared with other modalities, it is found that ultrasound can locate the ane, choic structure representing the pseudoaneurysm but difficulty lies with determining the presence of a communicating vessel. Its value also lies in measurement of the dimensions of the pseudoaneurysm and in the presence of thrombus. In our review, we examined 40 patients with 40 scans. There were 25 abnormal scans and 15 normal. There were no false-negative studies and only one false-positive. The overall accuracy of the study in this situation is greater than 90%. A puzzling situation concerns the 68-year-old woman who had a normal initial examination but subsequently had an abnormal one. The new symptom complex developed more than 2 months after the first examination. We believe that the fact that the patient was taking warfarin during this period contributed to the development of the false aneurysm. Only one scintiangiogram was verified by ultrasound and none by conventional angiography. That one case found to be negative for a false ancurysm led to the single false-positive result in the series. It is our belief that a follow-up study such as an angiogram is not necessary for verification at this time. Ultrasound has been shown previously not to be the optimal examination for false aneurysms. The benefits of a radionuclide vascular flow study centers on its ability to give information comparable to conventional angiography with less risk. The procedure is less invasive and results in far less radiation exposure than conventional angiography. In our seties, the one false-positive result led to a rate of 2.5%, which we believe is acceptable. There are several problems with this series. First, it is a retrospective report and the abnormal results

5 Volume 7 Number 3 March ~Tc-tagged scintiangiography to diagnose pseudoaneurysm 413 were verified at operation only. The two exceptions to this led to the one false-positive and the only nonoperated true-positive. None of the patients with normal results had further follow-up studies to verify the first scintiangiogram. A possible future study may include randomizing the results into operated and nonoperated groups. The operated group would have the results verified in that manner and the nonoperated groups would be followed up with periodic 99~Tc-labeled RBC scans and physical examinations. In this case the vascular flow study can be used to correlate physical findings of possible resolution of the false aneurysm. In conclusion, it is our belief that the 99mTctagged RBC scan is a viable alternative to conventional angiography. It appears to be an examination with high specificity and high overall accuracy. It is easy to perform and imposes less risk than conventional angiography. We recommend it as the procedure of choice in cases of suspected pseudoaneurysm, especially in the extremity. REFERENCES 1. Bole PV, Mtmda R, Purdy RT, et al. Traumatic pseudoaneurysms: a review of 32 cases. J Trauma 1976;16: Chavez CM. False aneurysms of the femoral artery. Ann Surg 1976;183: Ertzner TW, Powers TA. Pseudoaneurysm detection with Tc -99 m-labeled red blood cells. Radiology 1985; 154: Borlaza GS, Kuhns LR, Seigel R, Pozderac R, Eckhauser F. Computed tomographic and angiographic demonstration of gastroduodenal artery pseudoaneurysms in a pancreatic pseudocyst. J Comput Assist Tomogr 1979;3: Nino-Marcia M, Kurtz A, Biennan RE, Shaw E, Peiken SR, Weiss SM. CT diagnosis of a splenic artery aneurysm and a complication of chronic pancreatitis and pseudocyst formation. J Comput Assist Tomogr 1983;7: Sailes JF, MacDonald GB. The value of radionuchde angiography in the evaluation of suspected false aneurysms. J Nucl Med 1979;20: Lane IF, et al. The diagnosis of true and false aneurysms with indium lll labeled platelets. Vasc Surg 1985;2: Powers TA, Harolds JA, Kadir S, Grove RB. Pseudoaneurysm of the profunda femoris artery diagnosed on angiographic phase of bone scan. Clin Nucl Med 1979;4: Rudavsky AZ, Moss CM. Emission angiography for detection of false aneurysms. (Letter) J Nucl Med 1980;21: Moss CM, Rudavsky AZ, Veith FJ. The value of scintiangiography in arterial disease. Arch Surg 1976; 111: Moss CM, Veith FJ, Jason R, Rudavsky A. Screening isotope angiography in arterial trauma. Surgery 1979;86: Moss CM, Rudavsky AZ, Veith FJ. Isotope angiography: technique, validation and value in the assessment of arterial reconstruction. Ann Surg 1976;1'84: