- Email: [email protected]
Case report: CT and angiographic appearances of intrasplenic mycotic aneurysm
ClinicalRadiology (1991) 44, 271-272
Case Report: CT and Angiographic Appearances of Intrasplenic Mycotic Aneurysm G. R . A V E R Y ,
J. B. W I L S D O N
a n d L. M I T C H E L L *
Department of Radiology, Newcastle General Hospital, and * Department of Cardiothoracic Radiology, Freeman Hospital, Newcastle Upon Tyne A 67-year-old man developed intrasplenic mycotic aneurysms secondary to bacterial endocarditis. The computed tomography (CT) appearances showing enhancing lesions within the spleen are correlated with the angiographic appearances. A v e r y , G . R . , W i l s d o n , J.B. & M i t c h e l l , L. (1991). Clinical Radiology 44, 271 272. C a s e R e p o r t : C T a n d A n g i o g r a p h i c A p p e a r a n c e s o f Intrasplenic Mycotic Aneurysm
S p l e n i c a b s c e s s is a n u n u s u a l c o n d i t i o n , t h e d i a g n o s i s o f which can be made on computed tomography (CT) and successfully managed with percutaneous drainage (van der L a a n et al., 1989). H o w e v e r , m y c o t i c a n e u r y s m f o r m a t i o n is a r a r e c o m p l i c a t i o n a n d a l t h o u g h t h e a n g i o g r a p h i c a p p e a r a n c e s h a v e b e e n r e p o r t e d ( J a c o b s et al., 1974) t h e C T a p p e a r a n c e s a r e u n r e p o r t e d .
CASE R E P O R T A 67-year-old man presented with a history of rectal bleeding of recent onset. The only clinical abnormality noted was an aortic ejection systolic murmur. Investigations revealed anaemia and a barium enema showed diverticulosis. He was discharged following a blood transfusion. One month later he was readmitted with anaemia following further episodes of rectal bleeding. On admission he had a rigor. Examination revealed hepatosplenomegaly, aortic ejection systolic and diastolic murmurs. Investigations confirmed the anaemia and an erythrocyte sedimentation rate of 130 mm/h. Streptococcusboris was isolated from blood cultures. Ultrasound revealed an enlarged spleen of uniform texture. Echocardiography showed a calcified bicuspid aortic valve with a gradient of 45 mmHg and regurgitation; no vegetations were seen. Despite intravenous antibiotics the patient remained pyrexial and complained of left upper quadrant pain. An abdominal CT was performed. CT showed that within the spleen there were central areas of low attenuation with surrounding areas of slightly higher attenuation (Fig. 1). Following a bolus intravenous injection of 100 ml ofiopamidol 370 the low attenuation areas enhanced rapidly and to the same extent as the aorta. These were thought to represent aneurysms which in view of the history were considered to be mycotic in origin. The areas of initial high attenuation did not enhance. In view of the high attenuation it was thought these appearances may be due to recent thrombus within abscess cavities (Fig. 2). A splenic ultrasound performed at this time with settings of low persistence (frame averaging) showed swirling blood flow within two hypoechoic areas. These appearances were not as obvious on the usual scan settings of moderate persistence. A selective splenic arteriogram was performed. This demonstrated one large and a further small blood-filled cavity arising from the side wallof an upper pole segmental artery early in the arterial phase (Fig. 3). These findings support the diagnosis made from the CT scan. A repeat echocardiogram 2 weeks after the initial study revealed vegetations on the aortic valve. Unfortunately the patient had a cerebrovascutar accident, in view of which splenectomy was not performed. The patient is thought to have developed mycotic aneurysms secondary to emboli from bacterial endocarditis. However, due to the clinical progress pathological confirmation was not obtained. Correspondence to: Dr J. B. Wilsdon, Department of Radiology, Newcastle General Hospital, Westgate Road, Newcastle Upon Tyne NE4 6BE.
Fig. 1 Pre-contrast CT of the spleen showing central areas of low attenuation with surrounding areas of slightly higher attenuation.
Fig. 2 Post-contrast CT of the spleen showing marked enhancement similar to the aorta of,the previously low attenuation areas.
272
CLINICAL RADIOLOGY
lesions (Balcar et al., 1984). Therefore the differentiation between abscess and infarct is not always possible on CT. The angiographic appearances of a small intrasplenie mycotic aneurysm have been reported (Jacobs et al., 1974). Acute pseudoaneurysms of the splenic artery secondary to acute pancreatitis have been demonstrated on CT. These have shown enhancing lesions adjacent to the splenic artery or at the splenic hilum (Nino-Murcia et al., 1983; Burke et al., 1986). However, no intrasplenic aneurysms have been previously demonstrated on CT. This case represents an unusual complication of splenic abscess. It shows the importance of intravenous contrast media without which it would not have been possible to differentiate between the mycotic aneurysms and simple abscesses on CT. However, ultrasound clearly showed swirling blood flow and therefore would differentiate between the two. With the management of splenic abscess by percutaneous drainage (Lerner and Spataro, 1984; van der Laan et al., 1989) it is a situation of which radiologists should be aware in order to avoid potentially serious complications during interventional procedures. Fig. 3 - Selective splenic artery digital subtraction angiogram demonstrating contrast filling two cavities arising from the side wall of an upper pole segmental artery.
Acknowledgements.We would like to thank Dr W. Simpson for his help in preparing the manuscript.
DISCUSSION REFERENCES
The commonest cause of splenic abscess is haematogenous spread from a distant focus, and bacterial endocarditis is a major predisposing factor (Simson, 1980). Between 40% and 60% of patients with bacterial endocarditis have autopsy evidence of emboli, commonly involving the spleen and causing infarcts and predisposing to abscess formation (Simson, 1980; Julian et al., 1989). The absence of valve vegetations on the initial echocardiogram should not exclude endocarditis because the frequency with which valve vegetations are detected on ultrasound varies from 55% to 80% and they are rarely detected in the first 2 weeks of infection (Julian et al., 1989). The CT appearances of splenic infarcts and abscesses have been reported. Both present as areas of low attenuation which are better defined after the injection of intravenous contrast medium but show no rim enhancement. Most infarcts are well defined, wedge-shaped and extend to the periphery, while abscesses tend to be centrally located with irregular margins and occasionally multiple (Piekarski et al., 1980; Balthazar et al., 1985). Gas has also been demonstrated in splenic abscesses (Lerner and Spataro, 1984). However, one clinical and experimental study has shown that splenic infarcts can appear as multiple, heterogeneous and poorly marginated
Balcar, I, Seltzer, SE, Davis, S & Geller, S (1984) CT patterns of splenic infarction: a clinical and experimental study. Radiology, 151, 723729. Balthazar, EJ, Hilton, S, Naidich, D, Megibow, A & Levine, R (1985). CT of splenic and perisplenic abnormalities in septic patients. American Journal of Radiology, 144, 53-56. Burke, JW, Erickson, SJ, Kellum, CD, Tegtmeyer, CJ, Williamson BRJ & Hansen, MF (1986). Pseudoaneurysms complicating pancreatitis: Detection by CT. Radiology, 161, 447-450. Jacobs, RP, Shanser, JD, Lawson, DL & Palubinskas, AJ (1974). Angiography of splenic abscesses. American Journal of Radiology, 122, 419 424. Julian, DG, Camm, AJ, Fox, KM, Hall, RJC & Poole-Wilson, PA (1989). Diseases of the Heart. 1st edn., pp. 859 860. Bailliere Tindall, London. Lerrler, RM & Spataro, RF (1984). Splenic abscess: Percutaneous drainage. Radiology, 153, 643-645. Nino-Murcia, M, Kurtz, A, Brenrlan, RE, Shaw, E, Peiken, SR & Weiss, SM (1983). CT diagnosis of a splenic artery pseudoanerlrysm: A complication of chronic pancreatitis and pseudocyst formation. Journal of Computer Assisted Tomography, 7, 527-529. Piekarski, J, Federle, MP, Moss, AA & London, SS (1980). Computed tomography of the spleen. Radiology, 135, 683 689. Simson, JNL (1980). Solitary abscess of the spleen. British Journal of Surgery, 67, 106-110. van der Laan, RT, Verbeeten, B, Smits, NJ & Lubbers, MJ (1989). Computed tomography in the diagnosis and treatment of solitary splenic abscesses. Journal of Computer Assisted Tomography, 13, 71-74.
Case Report: CT and Angiographic Appearances of Intrasplenic Mycotic Aneurysm G. R . A V E R Y ,
J. B. W I L S D O N
a n d L. M I T C H E L L *
Department of Radiology, Newcastle General Hospital, and * Department of Cardiothoracic Radiology, Freeman Hospital, Newcastle Upon Tyne A 67-year-old man developed intrasplenic mycotic aneurysms secondary to bacterial endocarditis. The computed tomography (CT) appearances showing enhancing lesions within the spleen are correlated with the angiographic appearances. A v e r y , G . R . , W i l s d o n , J.B. & M i t c h e l l , L. (1991). Clinical Radiology 44, 271 272. C a s e R e p o r t : C T a n d A n g i o g r a p h i c A p p e a r a n c e s o f Intrasplenic Mycotic Aneurysm
S p l e n i c a b s c e s s is a n u n u s u a l c o n d i t i o n , t h e d i a g n o s i s o f which can be made on computed tomography (CT) and successfully managed with percutaneous drainage (van der L a a n et al., 1989). H o w e v e r , m y c o t i c a n e u r y s m f o r m a t i o n is a r a r e c o m p l i c a t i o n a n d a l t h o u g h t h e a n g i o g r a p h i c a p p e a r a n c e s h a v e b e e n r e p o r t e d ( J a c o b s et al., 1974) t h e C T a p p e a r a n c e s a r e u n r e p o r t e d .
CASE R E P O R T A 67-year-old man presented with a history of rectal bleeding of recent onset. The only clinical abnormality noted was an aortic ejection systolic murmur. Investigations revealed anaemia and a barium enema showed diverticulosis. He was discharged following a blood transfusion. One month later he was readmitted with anaemia following further episodes of rectal bleeding. On admission he had a rigor. Examination revealed hepatosplenomegaly, aortic ejection systolic and diastolic murmurs. Investigations confirmed the anaemia and an erythrocyte sedimentation rate of 130 mm/h. Streptococcusboris was isolated from blood cultures. Ultrasound revealed an enlarged spleen of uniform texture. Echocardiography showed a calcified bicuspid aortic valve with a gradient of 45 mmHg and regurgitation; no vegetations were seen. Despite intravenous antibiotics the patient remained pyrexial and complained of left upper quadrant pain. An abdominal CT was performed. CT showed that within the spleen there were central areas of low attenuation with surrounding areas of slightly higher attenuation (Fig. 1). Following a bolus intravenous injection of 100 ml ofiopamidol 370 the low attenuation areas enhanced rapidly and to the same extent as the aorta. These were thought to represent aneurysms which in view of the history were considered to be mycotic in origin. The areas of initial high attenuation did not enhance. In view of the high attenuation it was thought these appearances may be due to recent thrombus within abscess cavities (Fig. 2). A splenic ultrasound performed at this time with settings of low persistence (frame averaging) showed swirling blood flow within two hypoechoic areas. These appearances were not as obvious on the usual scan settings of moderate persistence. A selective splenic arteriogram was performed. This demonstrated one large and a further small blood-filled cavity arising from the side wallof an upper pole segmental artery early in the arterial phase (Fig. 3). These findings support the diagnosis made from the CT scan. A repeat echocardiogram 2 weeks after the initial study revealed vegetations on the aortic valve. Unfortunately the patient had a cerebrovascutar accident, in view of which splenectomy was not performed. The patient is thought to have developed mycotic aneurysms secondary to emboli from bacterial endocarditis. However, due to the clinical progress pathological confirmation was not obtained. Correspondence to: Dr J. B. Wilsdon, Department of Radiology, Newcastle General Hospital, Westgate Road, Newcastle Upon Tyne NE4 6BE.
Fig. 1 Pre-contrast CT of the spleen showing central areas of low attenuation with surrounding areas of slightly higher attenuation.
Fig. 2 Post-contrast CT of the spleen showing marked enhancement similar to the aorta of,the previously low attenuation areas.
272
CLINICAL RADIOLOGY
lesions (Balcar et al., 1984). Therefore the differentiation between abscess and infarct is not always possible on CT. The angiographic appearances of a small intrasplenie mycotic aneurysm have been reported (Jacobs et al., 1974). Acute pseudoaneurysms of the splenic artery secondary to acute pancreatitis have been demonstrated on CT. These have shown enhancing lesions adjacent to the splenic artery or at the splenic hilum (Nino-Murcia et al., 1983; Burke et al., 1986). However, no intrasplenic aneurysms have been previously demonstrated on CT. This case represents an unusual complication of splenic abscess. It shows the importance of intravenous contrast media without which it would not have been possible to differentiate between the mycotic aneurysms and simple abscesses on CT. However, ultrasound clearly showed swirling blood flow and therefore would differentiate between the two. With the management of splenic abscess by percutaneous drainage (Lerner and Spataro, 1984; van der Laan et al., 1989) it is a situation of which radiologists should be aware in order to avoid potentially serious complications during interventional procedures. Fig. 3 - Selective splenic artery digital subtraction angiogram demonstrating contrast filling two cavities arising from the side wall of an upper pole segmental artery.
Acknowledgements.We would like to thank Dr W. Simpson for his help in preparing the manuscript.
DISCUSSION REFERENCES
The commonest cause of splenic abscess is haematogenous spread from a distant focus, and bacterial endocarditis is a major predisposing factor (Simson, 1980). Between 40% and 60% of patients with bacterial endocarditis have autopsy evidence of emboli, commonly involving the spleen and causing infarcts and predisposing to abscess formation (Simson, 1980; Julian et al., 1989). The absence of valve vegetations on the initial echocardiogram should not exclude endocarditis because the frequency with which valve vegetations are detected on ultrasound varies from 55% to 80% and they are rarely detected in the first 2 weeks of infection (Julian et al., 1989). The CT appearances of splenic infarcts and abscesses have been reported. Both present as areas of low attenuation which are better defined after the injection of intravenous contrast medium but show no rim enhancement. Most infarcts are well defined, wedge-shaped and extend to the periphery, while abscesses tend to be centrally located with irregular margins and occasionally multiple (Piekarski et al., 1980; Balthazar et al., 1985). Gas has also been demonstrated in splenic abscesses (Lerner and Spataro, 1984). However, one clinical and experimental study has shown that splenic infarcts can appear as multiple, heterogeneous and poorly marginated
Balcar, I, Seltzer, SE, Davis, S & Geller, S (1984) CT patterns of splenic infarction: a clinical and experimental study. Radiology, 151, 723729. Balthazar, EJ, Hilton, S, Naidich, D, Megibow, A & Levine, R (1985). CT of splenic and perisplenic abnormalities in septic patients. American Journal of Radiology, 144, 53-56. Burke, JW, Erickson, SJ, Kellum, CD, Tegtmeyer, CJ, Williamson BRJ & Hansen, MF (1986). Pseudoaneurysms complicating pancreatitis: Detection by CT. Radiology, 161, 447-450. Jacobs, RP, Shanser, JD, Lawson, DL & Palubinskas, AJ (1974). Angiography of splenic abscesses. American Journal of Radiology, 122, 419 424. Julian, DG, Camm, AJ, Fox, KM, Hall, RJC & Poole-Wilson, PA (1989). Diseases of the Heart. 1st edn., pp. 859 860. Bailliere Tindall, London. Lerrler, RM & Spataro, RF (1984). Splenic abscess: Percutaneous drainage. Radiology, 153, 643-645. Nino-Murcia, M, Kurtz, A, Brenrlan, RE, Shaw, E, Peiken, SR & Weiss, SM (1983). CT diagnosis of a splenic artery pseudoanerlrysm: A complication of chronic pancreatitis and pseudocyst formation. Journal of Computer Assisted Tomography, 7, 527-529. Piekarski, J, Federle, MP, Moss, AA & London, SS (1980). Computed tomography of the spleen. Radiology, 135, 683 689. Simson, JNL (1980). Solitary abscess of the spleen. British Journal of Surgery, 67, 106-110. van der Laan, RT, Verbeeten, B, Smits, NJ & Lubbers, MJ (1989). Computed tomography in the diagnosis and treatment of solitary splenic abscesses. Journal of Computer Assisted Tomography, 13, 71-74.