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Computed Tomography of the Genitourinary Tract
0022-5347/78/1196-0780$02. 00/0 Vol. 119, June
THE JOURNAL OF UROLOGY
Printed in U.SA.
Copyright © 1978 by The Williams & Wilkins Co.
COMPUTED TOMOGRAPHY OF THE GENITOURINARY TRACT ROBERT J. STANLEY,* STUARTS. SAGEL
AND
WILLIAM R. FAIR
From the Mallinckrodt Institute of Radiology and Division of Urology, Washington University School of Medicine, St. Louis, Missouri
ABSTRACT
Eighteen months of experience with computed body tomography have revealed that this radiologic modality is useful in the diagnostic evaluation and management of urologic patients. Renal masses, perirenal lesions, poorly functioning kidneys, pelvic tumors and associated retroperitoneal nodal spread and other diagnostic problems related to the urinary tract have been imaged successfully with computed body tomography. Accuracy is high in the differentiation of benign renal cysts from renal neoplasms. Tumor staging with computed body tomography is being explored currently. The radiographic evaluation of the genitourinary system has increased steadily in usefulness and accuracy since the introduction of safe, intravenous renal contrast agents. Arteriography added a new dimension to the preoperative evaluation of renal mass lesions. Recently, ultrasound has assumed a major diagnostic role. In September 1975, when computed body tomography was introduced in our medical center, a considerable role in diagnostic uroradiology was not anticipated. However, during the next 18 months of clinical experience a wide application of computed body tomography to the evaluation of the genitourinary tract has emerged. This experience, which includes more than 150 patients with a variety of genitourinary lesions, will serve as the basis for this report. TECHNIQUE
All computed body tomography studies were performed on an EMI CT 5000 prototype body scanner. i-a A single scan takes 18 seconds and more than 90 per cent of the patients studied were able to suspend respiration during the scans. The method of performing the study has been described previously. 4 • 5 An entire examination usually is completed in less than 1 hour. Intravenous contrast agents are used frequently. A bolus injection, usually 50 cc Conray 400t, is used most frequently and is valuable in the computed body tomography distinction of solid from cystic masses, as well as in the delineation of the collecting system. Diagnostic problems commonly referred for evaluation with computed body tomography include 1) renal masses (benign cyst versus neoplasm), 2) juxtarenal masses (including neoplasms, abscesses, hematomas and aneurysms), 3) poorly or non-functioning kidneys and 4) staging of prostate, bladder and testicular tumors. RESULTS
Normal anatomy. The cross-sectional anatomy of the normal and abnormal kidney is well demonstrated by computed body tomography. 6 The presence of perinephric and renal sinus fat provides the tissue contrast needed to define the renal parenchyma. The hilar structures usually can be identified- the renal veins are anterior to the arteries and are of larger caliber. Normal intrarenal pelves usually are seen only Accepted for publication July 8, 1977. Read at annual meeting of American Urological Association, Chicago, Illinois, April 24-28, 1977. * Requests for reprints: Mallinckrodt Institute of Radiology, 510 South Kingshighway, St. Louis, Missouri 63110. t Mallinckrodt, Inc., St. Louis, Missouri. 780
after injection of intravenous contrast medium. Some larger extrarenal pelves can be identified by their shape and water density without the need of a contrast agent. Normal-sized calices can be seen occasionally outlined by renal sinus fat. More often they are demonstrated only with the aid of a contrast agent. Benign renal cysts. Displayed by computed body tomography, benign renal cysts are round or oval, sharply marginated, thin walled, water density masses that do not enhance with intravenous contrast agents (fig. 1). Water density means that the measured attenuation value of the mass is that of water (0 on the EMI measuring scale).:j: Non-enhancement means that no change in the measured attenuation value of the mass occurs after use of intravenous contrast medium. During the first 6 months of use of computed body tomography most of the diagnosed renal cysts were confirmed with percutaneous needle aspiration or at the time of operation performed for other reasons. No errors were made in the 26 confirmed cases. Subsequently, diagnosis with computed body tomography was regarded as definitive by the referring clinicians in the majority of cases and the number of cyst punctures decreased sharply. A prospective study is underway to evaluate every cystic-appearing mass, which will subsequently be aspirated, with computed body tomography in order to obtain more conclusive data. These cases, initially detected by excretory urography, also will be studied with ultrasound for the purpose of comparison. Renal neoplasms. Found to be approximately equal in density to the normal renal parenchyma, neoplasms generally were recognized as a mass causing a discrete alteration in the contour of the organ (fig. 2). The attenuation values of the solid tumors differed significantly from renal cysts and could be distinguished without the use of intravenous contrast medium. After injection of an intravenous contrast medium the attenuation value of the neoplasms increased slightly, reflecting the vascularity of the tumor and concomitant interstitial diffusion of the contrast agent. Because the surrounding normally functioning renal parenchyma enhanced to a greater degree after injection of an intravenous contrast medium the tumors usually were more apparent on the post-contrast scans. In comparison to the renal cysts the interface of tumor with renal tissue was usually not sharp. Areas of decreased density related to cystic change or necrosis were encountered in several tumors (fig. 2). Even when the entire tumor was cystic a distinction could be made between these angiographically hypovascular or avascular tumors and simple benign cysts by the presence of a thick wall, density greater than water and slight post-contrast enhancement (fig. 3). Twentyeight cases were diagnosed as renal neoplasms on the basis of :j:
EMI Medical Ltd., Northbrook, Illinois.
COMPUTED TOMOGRAPHY OF GENITOURINARY TRACT
the computed body tomography study and 27 were confirmed by an operation. In the 1 incorrect case the tumor was primary in the adrenal gland and could not be separated from the upper pole of the kidney with computed body tomography. There are no known falsely negative cases to date. Additional information provided by computed body tomography in the renal neoplasm cases included the detection of renal hilus and para-aortic nodal metastases, extracapsular extension of the tumor and liver metastases.4 Computed body tomography was unable to provide reliable information concerning presence or absence of tumor extending into the main renal vein or inferior vena cava. However, it could show clearly if the mass directly encroached upon the inferior vena cava. Computed body tomography also was found useful in the
Fm. 1. Round, water density mass (by precise measurement of attenuation value) arises from anterior surface of upper pole of right kidney (arrow). Margin between cyst and renal parenchyma, enhanced with contrast agent, is defined sharply. Findings are characteristic of benign cyst. Scan clarified an indeterminate ultrasound examination and obviated renal arteriography.
781
followup of post-nephrectomy rel).al cancer patients. Recurrence of tumor could be detected at a stage when it was neither palpable nor easily studied with other radiologic techniques. 4 In cases in which ajuxtarenal mass was suspected computed body tomography was most useful in clarifying or excluding such a possibility. Perinephric hematoma, 7 retroperitoneal neoplasm, 5 abscess and unsuspected aortic aneurysm all have been defined clearly with computed body tomogtaphy. Of equal value was the exclusion of disease in cases ih which a marked axis deviation of a kidney was related to an unusual amount ofperirenal fat. 4 Computed body tomography provides one with the ability to separate clearly intrarenal from extrarenal lesions in nearly all instances. The size, shape and location of poorly or non-functioning kidneys can be determined with computed body tomography, with or without the use of an intravenous contrast agent. The presence or absence of obstruction and hydronephrosis can be
Fm. 2. Bulky tumor containing low density areas of necrosis deforms and displaces left kidney anteriorly. Findings are diagnostic of large renal neoplasm,
Fm. 3. Round, cyst-like mass is present in right kidney in patient with chronic renal failure and otherwise small kidneys. Surrounding wall is thick (arrows). Measurement of attenuation of central, low density area indicated value substantially higher than water, inconsistent with benign cyst. Findings were indicative of cystic renal tumor and this was confirmed by operation.
782
STANLEY, SAGEL AND FAIR
determined accuratel~ and, quite often, the level and the cause of obstruction can be defined. Whether computed body tomography will replace high dose urography and tomography, currently used in renal failure patients, is not known presently. It is clear that computed body tomography can provide muclJ. diagnostic information in such patients without the need for contrast agents. Atrophy of chronic disease, enlargement owing to an infiltrative process or polycystic renal disease, distended collecting systems owing to bilateral obstruction or the normal-sized kidneys of an acute nephropathy can all be defined. 4 Certain functional aspects, such as vascular perfusion of all or part of the kidney, also can be assessed in a qualitative way. The cause for decreasing function in a transplant kidney can be clarified sometimes with computed body tomography. The differentiation between obstruction of the transplanted ureter and intrinsic rejection, a frequent diagnostic problem, can be made. Staging of prostate, bladder and testicular tumors with computed body tomography is being explored currently. In individual cases the technique has been most accurate in identifying direct extension of tumor, lateral pelvic wall nodal metastases (fig. 4) or the spread of testicular tumors to lymph nodes about the renal hilus, which are not usually opacified with bipedal lymphangiography (fig. 5). The clinical efficacy of such staging has not been determined to date. It is clear that computed body tomography can not
Fm. 5. Patient with proved left testicular seminoma had normalappearing lymph nodes on lymphangiography. Scan shows some of these normal-appearing nodes. Large mass lateral to left para-aortic nodes (arrow) is produced by metastatic seminoma to lymph node chain along left renal vein, not normally opacified by bipedal lymphangiography. differentiate between normal lymph nodes and those unenlarged nodes that have been replaced by tumor. No reliable tissue density difference has been found. However, screening such pelvic and testicular tumor cases with computed body tomography prior to a staging lymphangiogram may obviate the need for the latter procedure when gross nodal enlargment is detected. REFERENCES
Fm. 4. Pelvic scan at level of cystoscopically proved transitional cell carcinoma of bladder shows thickening of left bladder wall and mass projecting into bladder lumen. Contralateral internal iliac nodal metastasis is defined clearly (arrow).
L Kreel, L.: Computerized tomography using the EMI general purpose scanner. Brit. J. Radiol., 50: 2, 1977. 2. Sagel, S. S., Stanley, R. J. and Evens, R. G.: Early clinical experience with motionless whole-body computed tomography. Radiology, 119: 321, 1976. 3. Stephens, D. H., Sheedy, P. F., II, Hattery, R.R. and Hartman, G. W.: Initial clinical experience with computerized tomography of the body. Radiol. Clin. N. Amer., 14: 149, 1976. 4. Sagel, S. S., Stanley, R. J., Levitt, R. G. and Geisse, G.: Computed tomography of the kidney. Radiology, 124: 359, 1977. 5. Stanley, R. J., Sagel, S. S. and Levitt, R. G.: Computed tomography of the body: early trends in application and accuracy of the method. Amer. J. Roentgen., 127: 53, 1976. 6. Hattery, R. R., Williamson, B., Jr. and Hartman, G. W.: Urinary tract tomography. Radio!. Clin. N. Amer., 14: 23, 1976. 7. Sagel, S. S., Siegel, M. J., Stanley, R. J. and Jost, R. G.: Detection of retroperitoneal hemorrhage by computed tomography. Amer. J. Roentgen., 129: 403, 1977.
THE JOURNAL OF UROLOGY
Printed in U.SA.
Copyright © 1978 by The Williams & Wilkins Co.
COMPUTED TOMOGRAPHY OF THE GENITOURINARY TRACT ROBERT J. STANLEY,* STUARTS. SAGEL
AND
WILLIAM R. FAIR
From the Mallinckrodt Institute of Radiology and Division of Urology, Washington University School of Medicine, St. Louis, Missouri
ABSTRACT
Eighteen months of experience with computed body tomography have revealed that this radiologic modality is useful in the diagnostic evaluation and management of urologic patients. Renal masses, perirenal lesions, poorly functioning kidneys, pelvic tumors and associated retroperitoneal nodal spread and other diagnostic problems related to the urinary tract have been imaged successfully with computed body tomography. Accuracy is high in the differentiation of benign renal cysts from renal neoplasms. Tumor staging with computed body tomography is being explored currently. The radiographic evaluation of the genitourinary system has increased steadily in usefulness and accuracy since the introduction of safe, intravenous renal contrast agents. Arteriography added a new dimension to the preoperative evaluation of renal mass lesions. Recently, ultrasound has assumed a major diagnostic role. In September 1975, when computed body tomography was introduced in our medical center, a considerable role in diagnostic uroradiology was not anticipated. However, during the next 18 months of clinical experience a wide application of computed body tomography to the evaluation of the genitourinary tract has emerged. This experience, which includes more than 150 patients with a variety of genitourinary lesions, will serve as the basis for this report. TECHNIQUE
All computed body tomography studies were performed on an EMI CT 5000 prototype body scanner. i-a A single scan takes 18 seconds and more than 90 per cent of the patients studied were able to suspend respiration during the scans. The method of performing the study has been described previously. 4 • 5 An entire examination usually is completed in less than 1 hour. Intravenous contrast agents are used frequently. A bolus injection, usually 50 cc Conray 400t, is used most frequently and is valuable in the computed body tomography distinction of solid from cystic masses, as well as in the delineation of the collecting system. Diagnostic problems commonly referred for evaluation with computed body tomography include 1) renal masses (benign cyst versus neoplasm), 2) juxtarenal masses (including neoplasms, abscesses, hematomas and aneurysms), 3) poorly or non-functioning kidneys and 4) staging of prostate, bladder and testicular tumors. RESULTS
Normal anatomy. The cross-sectional anatomy of the normal and abnormal kidney is well demonstrated by computed body tomography. 6 The presence of perinephric and renal sinus fat provides the tissue contrast needed to define the renal parenchyma. The hilar structures usually can be identified- the renal veins are anterior to the arteries and are of larger caliber. Normal intrarenal pelves usually are seen only Accepted for publication July 8, 1977. Read at annual meeting of American Urological Association, Chicago, Illinois, April 24-28, 1977. * Requests for reprints: Mallinckrodt Institute of Radiology, 510 South Kingshighway, St. Louis, Missouri 63110. t Mallinckrodt, Inc., St. Louis, Missouri. 780
after injection of intravenous contrast medium. Some larger extrarenal pelves can be identified by their shape and water density without the need of a contrast agent. Normal-sized calices can be seen occasionally outlined by renal sinus fat. More often they are demonstrated only with the aid of a contrast agent. Benign renal cysts. Displayed by computed body tomography, benign renal cysts are round or oval, sharply marginated, thin walled, water density masses that do not enhance with intravenous contrast agents (fig. 1). Water density means that the measured attenuation value of the mass is that of water (0 on the EMI measuring scale).:j: Non-enhancement means that no change in the measured attenuation value of the mass occurs after use of intravenous contrast medium. During the first 6 months of use of computed body tomography most of the diagnosed renal cysts were confirmed with percutaneous needle aspiration or at the time of operation performed for other reasons. No errors were made in the 26 confirmed cases. Subsequently, diagnosis with computed body tomography was regarded as definitive by the referring clinicians in the majority of cases and the number of cyst punctures decreased sharply. A prospective study is underway to evaluate every cystic-appearing mass, which will subsequently be aspirated, with computed body tomography in order to obtain more conclusive data. These cases, initially detected by excretory urography, also will be studied with ultrasound for the purpose of comparison. Renal neoplasms. Found to be approximately equal in density to the normal renal parenchyma, neoplasms generally were recognized as a mass causing a discrete alteration in the contour of the organ (fig. 2). The attenuation values of the solid tumors differed significantly from renal cysts and could be distinguished without the use of intravenous contrast medium. After injection of an intravenous contrast medium the attenuation value of the neoplasms increased slightly, reflecting the vascularity of the tumor and concomitant interstitial diffusion of the contrast agent. Because the surrounding normally functioning renal parenchyma enhanced to a greater degree after injection of an intravenous contrast medium the tumors usually were more apparent on the post-contrast scans. In comparison to the renal cysts the interface of tumor with renal tissue was usually not sharp. Areas of decreased density related to cystic change or necrosis were encountered in several tumors (fig. 2). Even when the entire tumor was cystic a distinction could be made between these angiographically hypovascular or avascular tumors and simple benign cysts by the presence of a thick wall, density greater than water and slight post-contrast enhancement (fig. 3). Twentyeight cases were diagnosed as renal neoplasms on the basis of :j:
EMI Medical Ltd., Northbrook, Illinois.
COMPUTED TOMOGRAPHY OF GENITOURINARY TRACT
the computed body tomography study and 27 were confirmed by an operation. In the 1 incorrect case the tumor was primary in the adrenal gland and could not be separated from the upper pole of the kidney with computed body tomography. There are no known falsely negative cases to date. Additional information provided by computed body tomography in the renal neoplasm cases included the detection of renal hilus and para-aortic nodal metastases, extracapsular extension of the tumor and liver metastases.4 Computed body tomography was unable to provide reliable information concerning presence or absence of tumor extending into the main renal vein or inferior vena cava. However, it could show clearly if the mass directly encroached upon the inferior vena cava. Computed body tomography also was found useful in the
Fm. 1. Round, water density mass (by precise measurement of attenuation value) arises from anterior surface of upper pole of right kidney (arrow). Margin between cyst and renal parenchyma, enhanced with contrast agent, is defined sharply. Findings are characteristic of benign cyst. Scan clarified an indeterminate ultrasound examination and obviated renal arteriography.
781
followup of post-nephrectomy rel).al cancer patients. Recurrence of tumor could be detected at a stage when it was neither palpable nor easily studied with other radiologic techniques. 4 In cases in which ajuxtarenal mass was suspected computed body tomography was most useful in clarifying or excluding such a possibility. Perinephric hematoma, 7 retroperitoneal neoplasm, 5 abscess and unsuspected aortic aneurysm all have been defined clearly with computed body tomogtaphy. Of equal value was the exclusion of disease in cases ih which a marked axis deviation of a kidney was related to an unusual amount ofperirenal fat. 4 Computed body tomography provides one with the ability to separate clearly intrarenal from extrarenal lesions in nearly all instances. The size, shape and location of poorly or non-functioning kidneys can be determined with computed body tomography, with or without the use of an intravenous contrast agent. The presence or absence of obstruction and hydronephrosis can be
Fm. 2. Bulky tumor containing low density areas of necrosis deforms and displaces left kidney anteriorly. Findings are diagnostic of large renal neoplasm,
Fm. 3. Round, cyst-like mass is present in right kidney in patient with chronic renal failure and otherwise small kidneys. Surrounding wall is thick (arrows). Measurement of attenuation of central, low density area indicated value substantially higher than water, inconsistent with benign cyst. Findings were indicative of cystic renal tumor and this was confirmed by operation.
782
STANLEY, SAGEL AND FAIR
determined accuratel~ and, quite often, the level and the cause of obstruction can be defined. Whether computed body tomography will replace high dose urography and tomography, currently used in renal failure patients, is not known presently. It is clear that computed body tomography can provide muclJ. diagnostic information in such patients without the need for contrast agents. Atrophy of chronic disease, enlargement owing to an infiltrative process or polycystic renal disease, distended collecting systems owing to bilateral obstruction or the normal-sized kidneys of an acute nephropathy can all be defined. 4 Certain functional aspects, such as vascular perfusion of all or part of the kidney, also can be assessed in a qualitative way. The cause for decreasing function in a transplant kidney can be clarified sometimes with computed body tomography. The differentiation between obstruction of the transplanted ureter and intrinsic rejection, a frequent diagnostic problem, can be made. Staging of prostate, bladder and testicular tumors with computed body tomography is being explored currently. In individual cases the technique has been most accurate in identifying direct extension of tumor, lateral pelvic wall nodal metastases (fig. 4) or the spread of testicular tumors to lymph nodes about the renal hilus, which are not usually opacified with bipedal lymphangiography (fig. 5). The clinical efficacy of such staging has not been determined to date. It is clear that computed body tomography can not
Fm. 5. Patient with proved left testicular seminoma had normalappearing lymph nodes on lymphangiography. Scan shows some of these normal-appearing nodes. Large mass lateral to left para-aortic nodes (arrow) is produced by metastatic seminoma to lymph node chain along left renal vein, not normally opacified by bipedal lymphangiography. differentiate between normal lymph nodes and those unenlarged nodes that have been replaced by tumor. No reliable tissue density difference has been found. However, screening such pelvic and testicular tumor cases with computed body tomography prior to a staging lymphangiogram may obviate the need for the latter procedure when gross nodal enlargment is detected. REFERENCES
Fm. 4. Pelvic scan at level of cystoscopically proved transitional cell carcinoma of bladder shows thickening of left bladder wall and mass projecting into bladder lumen. Contralateral internal iliac nodal metastasis is defined clearly (arrow).
L Kreel, L.: Computerized tomography using the EMI general purpose scanner. Brit. J. Radiol., 50: 2, 1977. 2. Sagel, S. S., Stanley, R. J. and Evens, R. G.: Early clinical experience with motionless whole-body computed tomography. Radiology, 119: 321, 1976. 3. Stephens, D. H., Sheedy, P. F., II, Hattery, R.R. and Hartman, G. W.: Initial clinical experience with computerized tomography of the body. Radiol. Clin. N. Amer., 14: 149, 1976. 4. Sagel, S. S., Stanley, R. J., Levitt, R. G. and Geisse, G.: Computed tomography of the kidney. Radiology, 124: 359, 1977. 5. Stanley, R. J., Sagel, S. S. and Levitt, R. G.: Computed tomography of the body: early trends in application and accuracy of the method. Amer. J. Roentgen., 127: 53, 1976. 6. Hattery, R. R., Williamson, B., Jr. and Hartman, G. W.: Urinary tract tomography. Radio!. Clin. N. Amer., 14: 23, 1976. 7. Sagel, S. S., Siegel, M. J., Stanley, R. J. and Jost, R. G.: Detection of retroperitoneal hemorrhage by computed tomography. Amer. J. Roentgen., 129: 403, 1977.