1976, British Journal of Radiology, 49, 1-2
VOLUME 49 NUMBER 577
J A N U A R Y 1976
The British Journal of Radiology Radiology now Recent Interest In the spleen Radiology has played a part in the study of splenic function since Barcroft and his co-workers (Barcroft 1925; 1926; Barcroft et al, 1925) observed the alteration of the size of the spleen in rabbits, cats and dogs by placing metallic sutures on the splenic capsule, and taking radiographs following various physiological stimuli. In clinical practice, plain-film radiography still has a place to surprise the unwary clinician. Development of isotope-labelling techniques followed later in the study of the relationship between cellular elements of the blood and splenic function. These methods are sometimes of great value, though scanning of the spleen has proved unreliable in the staging of Hodgkin's disease (Ell et al, 1975). Recently, Kreel (1974) has studied at length the incidence of aneurysms in the splenic arterial tree, using plain and contrast radiography in vitro and in vivo. He found an increasing incidence of aneurysms with age, as might be expected, but the female predominance is surprising. In his group with portal hypertension and splenomegaly, aneurysms were observed in a much younger age group. I am not sure that his hypothesis of "wear and tear from many years of high rates of blood flow" is well founded. Normally the splenic blood-flow rate, measured by clearance of radioactive xenon, is 120 ml./minute (Williams et al, 1968), but this can rise markedly both in cirrhosis of the liver and haematological disorders. In splenomegaly due to myelofibrosis and leukaemia, splenic blood flow has been measured at 1-6 1./minute, representing over 20 per cent of the cardiac output (Garnet et al., 1969). It would be interesting to observe the prevalence of aneurysms in patients with high splenic blood flow from causes other than portal hypertension. Across the Atlantic, splenic arteriography is performed more readily than in this country in cases of suspected trauma to exclude rupture, haematoma and infarction. Here the detailed intra-splenic anatomy is important. However, the most exciting 1
developments in the recent radiology of the spleen have come with the advances of modern immunology. The spleen is a secondary lymphoid organ, where lymphopoiesis begins late in fetal life, after the development of the thymus. Together with lymphnodes, the spleen may respond to antigen stimulus by germinal centre and plasma cell production. Sandberg (1972) has used radioactive xenon to record an increase in intra-splenic blood flow following pertussis vaccination. This rather basic observation may in fact reveal a close link between vascular changes and immune responses or disorders in the spleen. Splenic atrophy has recently been shown to be associated with widespread immunological disturbances, notably auto-immunity (Wardrope^a/., 1975), Also, some splenic enlargement is reputed to occur after cardiac transplantation. Herman, Yamamoto and Mellins (1972) investigated the micro-circulation changes of lymph-nodes during the primary immune response, and recently the same centre has turned its attention to the white pulp of the spleen. The marginal sinus of the splenic Malpighian follicle was recognized as a site of intimate contact between the reticulo-endothelial cells and the cellular elements in the blood many years ago (Macneal, Otani and Patterson, 1927). The localization of injected antigens near the marginal sinuses (Nossal et al., 1966; Mitchell and Abbott, 1971), and the migration of antigen-binding cells from there to the germinal centre of the Malpighian follicle (Mitchell, 1972) are more recent findings. Concurrent work in radiological departments in Boston and London has demonstrated the finer vascular pathways of the white pulp using injection methods (Dubreuil et al, 1975; Ayers et al, 1975). The marginal sinus of the Malpighian follicle has been shown to be an important link in this pathway. Furthermore, the marginal sinuses have been seen in vivo in dogs by arteriography as round "haloes" of contrast, and the haemodynamics studied (Ayers et al., 1975). The circulation through the marginal
VOL. 49, No. 577
Radiology now—recent interest in the spleen sinus has been shown to be slow. This, it is suggested, provides an environment which encourages the trans-vascular migration of cells to occur. Further studies may enable us to determine what changes occur in the microvascular structure and flow patterns during immune responses following antigen stimulus. Whether improving radiological techniques will allow such detail to be obtained in man in vivo has yet to be discovered. One could speculate that the unlikely combination of immunology and radiology may produce data in patients with immunological disturbances which will be useful in diagnosis and prognosis. In clinical practice, advancement may come more quickly with the use of ultrasonography. This is already of value in the diagnosis of splenic cysts, and may prove its worth in the separation of splenic enlargement due to vascular engorgement from that due to increase in cellular content. Such tissue differentiation with ultrasonography is still in its early days: there are strong hopes for its success, but will the EMI scanner surpass all? A. B. AYERS
REFERENCES AYERS, A. B., HENRY. K., RUSSELL, S. B., and STEINER,
R. E., 1976. The microvasculature of the spleen. Clinical Radiology (in press). BARCROFT, J., 1925. Recent knowledge of the spleen. Lancet, 205,319-322. 1926. Some recent work on the functions of the spleen. Lancet, 210, 544-547. BARCROFT, J., HARRIS, H. A., ORAHOVATS, D., and WEISS,
R., 1925. A contribution to the physiology of the spleen. Journal of Physiology (London), 60, 443-456.
DUBREUIL, A. E., HERMAN, P. G., TILNEY, N. L., and
MELLINS, H. Z., 1975. Microangiography of the white pulp of the spleen. American Journal of Roentgenology, 123, 427-433. ELL, P. J., BRITTON, K. E., FARRER-BROWN, G., KEELING, D. H., JELLIFFE, A. M., and WOOD, T. P., 1975. An
assessment of the value of spleen scanning in the staging of Hodgkin's disease. British Journal of Radiology, 48, 590-593. GARNET, E. S., GODDARD, B. A., MARKBY, D., and WEBBER,
C. E., 1969. Spleen as an arterio-venous shunt. Lancet, 1, 386-388. HERMAN, P. G., YAMAMOTO, I., and MELLINS, H. Z., 1972.
Blood circulation in the lymph node during primary immune response. Journal of Experimental Medicine, 136, 697-714. KREEL, L., 1974. The recognition and incidence of splenic artery aneurysms, Part II-IV. Australasian Radiology, 18, 415^38. MACNEAL, W. J., OTANI, S., and PATTERSON, M. B., 1927.
The finer vascular channels of the spleen. American Journal of Pathology, 3, 111-122. MITCHELL, J., 1972. Antigens in immunity XVIII—The migration of antigen-binding, bone-marrow-derived and thymus-derived spleen cells in mice. Immunology, 22, 231-245. MITCHELL, J. and ABBOTT, A., 1971. Antigens in immunity
XVI—A light and electron microscope study of antigen localization in the rat spleen. Immunology, 21, 207-224. NOSSAL, G. J. V., AUSTIN, C. M., PYE, J., and MITCHELL, J.,
1966. Antigens in immunity XII—Antigen trapping in the spleen. International Archives of Allergy and Applied Immunology, 29, 368-383. SANDBERG, G., 1972. Splenic blood flow in the guinea pig measured with xenon133 and calculation of venous output of lymphocytes. Ada Physiologica Scandinavica, 84, 208216. WARDROP, C. A. J., LEE, F. D., DYET, J. F., DAGG., J. H., SINGH, H., and MOFFAT, A., 1975. Immunological ab-
normalities in splenic atrophy. Lancet, 2, 4-7. WILLIAMS, R., CONDON, R. E., WILLIAMS, H. S., BLENDIS,
L. M., and KREEL, L., 1968. Splenic blood flow in cirrhosis and portal hypertension. Clinical Science, 34, 441452.
VOLUME 49 NUMBER 577
J A N U A R Y 1976
The British Journal of Radiology Radiology now Recent Interest In the spleen Radiology has played a part in the study of splenic function since Barcroft and his co-workers (Barcroft 1925; 1926; Barcroft et al, 1925) observed the alteration of the size of the spleen in rabbits, cats and dogs by placing metallic sutures on the splenic capsule, and taking radiographs following various physiological stimuli. In clinical practice, plain-film radiography still has a place to surprise the unwary clinician. Development of isotope-labelling techniques followed later in the study of the relationship between cellular elements of the blood and splenic function. These methods are sometimes of great value, though scanning of the spleen has proved unreliable in the staging of Hodgkin's disease (Ell et al, 1975). Recently, Kreel (1974) has studied at length the incidence of aneurysms in the splenic arterial tree, using plain and contrast radiography in vitro and in vivo. He found an increasing incidence of aneurysms with age, as might be expected, but the female predominance is surprising. In his group with portal hypertension and splenomegaly, aneurysms were observed in a much younger age group. I am not sure that his hypothesis of "wear and tear from many years of high rates of blood flow" is well founded. Normally the splenic blood-flow rate, measured by clearance of radioactive xenon, is 120 ml./minute (Williams et al, 1968), but this can rise markedly both in cirrhosis of the liver and haematological disorders. In splenomegaly due to myelofibrosis and leukaemia, splenic blood flow has been measured at 1-6 1./minute, representing over 20 per cent of the cardiac output (Garnet et al., 1969). It would be interesting to observe the prevalence of aneurysms in patients with high splenic blood flow from causes other than portal hypertension. Across the Atlantic, splenic arteriography is performed more readily than in this country in cases of suspected trauma to exclude rupture, haematoma and infarction. Here the detailed intra-splenic anatomy is important. However, the most exciting 1
developments in the recent radiology of the spleen have come with the advances of modern immunology. The spleen is a secondary lymphoid organ, where lymphopoiesis begins late in fetal life, after the development of the thymus. Together with lymphnodes, the spleen may respond to antigen stimulus by germinal centre and plasma cell production. Sandberg (1972) has used radioactive xenon to record an increase in intra-splenic blood flow following pertussis vaccination. This rather basic observation may in fact reveal a close link between vascular changes and immune responses or disorders in the spleen. Splenic atrophy has recently been shown to be associated with widespread immunological disturbances, notably auto-immunity (Wardrope^a/., 1975), Also, some splenic enlargement is reputed to occur after cardiac transplantation. Herman, Yamamoto and Mellins (1972) investigated the micro-circulation changes of lymph-nodes during the primary immune response, and recently the same centre has turned its attention to the white pulp of the spleen. The marginal sinus of the splenic Malpighian follicle was recognized as a site of intimate contact between the reticulo-endothelial cells and the cellular elements in the blood many years ago (Macneal, Otani and Patterson, 1927). The localization of injected antigens near the marginal sinuses (Nossal et al., 1966; Mitchell and Abbott, 1971), and the migration of antigen-binding cells from there to the germinal centre of the Malpighian follicle (Mitchell, 1972) are more recent findings. Concurrent work in radiological departments in Boston and London has demonstrated the finer vascular pathways of the white pulp using injection methods (Dubreuil et al, 1975; Ayers et al, 1975). The marginal sinus of the Malpighian follicle has been shown to be an important link in this pathway. Furthermore, the marginal sinuses have been seen in vivo in dogs by arteriography as round "haloes" of contrast, and the haemodynamics studied (Ayers et al., 1975). The circulation through the marginal
VOL. 49, No. 577
Radiology now—recent interest in the spleen sinus has been shown to be slow. This, it is suggested, provides an environment which encourages the trans-vascular migration of cells to occur. Further studies may enable us to determine what changes occur in the microvascular structure and flow patterns during immune responses following antigen stimulus. Whether improving radiological techniques will allow such detail to be obtained in man in vivo has yet to be discovered. One could speculate that the unlikely combination of immunology and radiology may produce data in patients with immunological disturbances which will be useful in diagnosis and prognosis. In clinical practice, advancement may come more quickly with the use of ultrasonography. This is already of value in the diagnosis of splenic cysts, and may prove its worth in the separation of splenic enlargement due to vascular engorgement from that due to increase in cellular content. Such tissue differentiation with ultrasonography is still in its early days: there are strong hopes for its success, but will the EMI scanner surpass all? A. B. AYERS
REFERENCES AYERS, A. B., HENRY. K., RUSSELL, S. B., and STEINER,
R. E., 1976. The microvasculature of the spleen. Clinical Radiology (in press). BARCROFT, J., 1925. Recent knowledge of the spleen. Lancet, 205,319-322. 1926. Some recent work on the functions of the spleen. Lancet, 210, 544-547. BARCROFT, J., HARRIS, H. A., ORAHOVATS, D., and WEISS,
R., 1925. A contribution to the physiology of the spleen. Journal of Physiology (London), 60, 443-456.
DUBREUIL, A. E., HERMAN, P. G., TILNEY, N. L., and
MELLINS, H. Z., 1975. Microangiography of the white pulp of the spleen. American Journal of Roentgenology, 123, 427-433. ELL, P. J., BRITTON, K. E., FARRER-BROWN, G., KEELING, D. H., JELLIFFE, A. M., and WOOD, T. P., 1975. An
assessment of the value of spleen scanning in the staging of Hodgkin's disease. British Journal of Radiology, 48, 590-593. GARNET, E. S., GODDARD, B. A., MARKBY, D., and WEBBER,
C. E., 1969. Spleen as an arterio-venous shunt. Lancet, 1, 386-388. HERMAN, P. G., YAMAMOTO, I., and MELLINS, H. Z., 1972.
Blood circulation in the lymph node during primary immune response. Journal of Experimental Medicine, 136, 697-714. KREEL, L., 1974. The recognition and incidence of splenic artery aneurysms, Part II-IV. Australasian Radiology, 18, 415^38. MACNEAL, W. J., OTANI, S., and PATTERSON, M. B., 1927.
The finer vascular channels of the spleen. American Journal of Pathology, 3, 111-122. MITCHELL, J., 1972. Antigens in immunity XVIII—The migration of antigen-binding, bone-marrow-derived and thymus-derived spleen cells in mice. Immunology, 22, 231-245. MITCHELL, J. and ABBOTT, A., 1971. Antigens in immunity
XVI—A light and electron microscope study of antigen localization in the rat spleen. Immunology, 21, 207-224. NOSSAL, G. J. V., AUSTIN, C. M., PYE, J., and MITCHELL, J.,
1966. Antigens in immunity XII—Antigen trapping in the spleen. International Archives of Allergy and Applied Immunology, 29, 368-383. SANDBERG, G., 1972. Splenic blood flow in the guinea pig measured with xenon133 and calculation of venous output of lymphocytes. Ada Physiologica Scandinavica, 84, 208216. WARDROP, C. A. J., LEE, F. D., DYET, J. F., DAGG., J. H., SINGH, H., and MOFFAT, A., 1975. Immunological ab-
normalities in splenic atrophy. Lancet, 2, 4-7. WILLIAMS, R., CONDON, R. E., WILLIAMS, H. S., BLENDIS,
L. M., and KREEL, L., 1968. Splenic blood flow in cirrhosis and portal hypertension. Clinical Science, 34, 441452.
