0022-5347 /79/1221-0014$02.00/0 Vol. 122, July Printed in U.S.A.
THE JOURNAL OF UROLOGY
Copyright © 1979 by The Williams & Wilkins Co.
ULTRASONIC DIFFERENTIATION OF RENAL PELVIC FILLING DEFECTS S. GRANT MULHOLLAND,* PETER H. ARGER, BARRY B. GOLDBERG
AND
HOWARD M. POLLACK
From the Division of Urology, Departments of Surgery and Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
ABSTRACT
We herein describe 9 patients with non-opaque calculi and 3 patients with soft tissue filling defects in the renal pelvis studied by ultrasound. The calculi varied in size from 1.5 cm. to staghorn calculi. All stones were imaged satisfactorily by ultrasound, allowing the diagnosis of stone to be made with confidence. Ultrasonic differentiation ofrenal pelvic filling defects proved to be a simple, reliable, non-invasive method to differentiate these clinically perplexing lesions. Renal pelvic filling defects often present a perplexing diagnostic problem for the urologist. To plan treatment a simple, reliable, non-invasive diagnostic aid is needed. The clear demonstration of a filling defect on excretory urography (IVP) or retrograde pyelography often does not present a conclusive diagnosis. The lesion may be one of many different diagnoses. When the impaired renal function in the patient or reluctance to perform retrograde pyelography by the surgeon (as in some cases of renal infection) precludes the use of opaque contrast medium ancillary methods of diagnosis must be sought. There are few, if any, critical assessments in the literature of ultrasound in the diagnosis of nephrolithiasis and other renal pelvic lesions. We herein describe our experience with ultrasound in the diagnosis of non-opaque renal filling defects. There were 9 non-opaque renal calculi, 2 renal pelvic tumors and 1 parenchymal neoplasm invading the pelvis shown on IVP. Satisfactory differentiation of stone versus soft tissue was attained by ultrasound.
rare xanthme and mucoid matrix stones also are non-opaque. Because of the gross similarity in roentgenographic appearances between non-opaque calculi and some transitional cell tumors (fig. 2, A) of the renal pelvis and calices, it often is not possible to distinguish between them radiologically so interventional procedures such as endoscopic brush biopsy or surgical exploration must be used for this purpose. For this reason, an alternate method of diagnosis is sorely needed. Ultrasound is of proved value in the diagnosis of opaque and non-opaque biliary tract calculi. 2 There have been reports on the use of ultrasound in renal stone disease but none specifically has used ultrasound to differentiate between non-opaque calculi and renal pelvic neoplasms.3--8 We postulated that nonopaque renal calculi should lend themselves to in vivo detection by ultrasound as readily as do biliary stones. Reports of in vitro experiments on renal calculi4 as well as experiences with ultrasonography of the surgically exposed kidney further strengthened this belief. 3 In our investigation 9 patients with non-opaque calculi had the stones imaged satisfactorily by ultrasound (see table). These findings were conclusive enough to suggest that this diagnostic aid may have an important place for patients with renal pelvic filling defects or for those patients at risk for the development of uric acid stones. In 1 patient diminution of uric acid stone size was documented clearly ultrasonically during medical treatment. In each of the 9 patients the stone was represented by an echo-dense pattern associated with pronounced sound attenuation producing a strong acoustical shadowing effect (echo-free zone) beyond the calculus (fig. 1, B). Our experience with filling defects other than stone (cases 10, 11 and 12) indicates that no significant acoustical shadow effect is produced by soft tissue masses in the renal pelvis (fig. 2, B). Therefore, the differences between these 2 ultrasonic patterns seems to be strongly suggestive, if not diagnostic, of stone disease. The differential diagnosis of acoustical shadowing within the kidney is limited. Other than renal calculi only internal gas can produce acoustical shadowing. The presence of gas should be detectable easily on the plain film abdominal roentgenograms. Abscesses containing micro air bubbles9 and angiomyolipomas10 can produce intense echoes. If ultrasound proves to be a consistently reliable method of differentiating non-opaque stones from renal pelvic soft tissue lesions it might well represent an important contribution, since uric acid calculi can be treated medically and may, at times, be completely dissolved without surgical intervention. 1 We have imaged renal calculi measuring 1.5 x 1.5 cm. with clarity. The limits of ultrasonic resolution of renal calculi have yet to be determined. Ultrasound can demonstrate accurately the degree of associated hydronephrosis when present
METHOD
The ultrasonic examinations were done with a standard commercially available scanner. Medium focused 2.25 and 3.5 m.Hz. transducers were used and over scanning was avoided with a single pass scanning technique. Patients were examined in the prone and, when appropriate, supine and decubitus positions. Transverse and longitudinal images were obtained in all cases. DISCUSSION
Renal pelvic filling defects may have many different etiologies and, therefore, present a perplexing problem for the urologist. Unfortunately, the diagnosis often cannot be assured by merely outlining the defects with contrast material. Arteriography seldom is conclusive. A simple, reliable, noninvasive diagnostic aid is needed to plan treatment. The most important clinical question to answer quickly is whether this defect is soft tissue or sto~e. If there is good evidence of stone causing the filling defect the approach might be entirely medical, thus saving the patient an operation. Clinical trials of regimens to dissolve stones have been advocated by some1 but this seems clinically unwise unless there is conclusive evidence that the defect is a stone. Among the most common filling defects in the renal pelvis are those produced by non-opaque calculi. Such stones usually are composed of uric acid or urates (fig. 1, A), although the Accepted for publication August 4, 1978. Read at annual meeting of American Urological Association, Washington, D. C., May 21-25, 1978. * Current address: Department of Urology, Thomas Jefferson University, 1025 Walnut St., Philadelphia, Pennsylvania 19107.
14
ULTRASONIC DIFFERENTIATION OF RENAL PELVIC FILLING DEFECTS
15
FIG. 1. A, IVP demonstrates large filling defect within renal pelvis. B, ultrasound demonstrates echo-dense area with acoustical shadowing (arrow). Diagnosis is uric acid calculus.
FIG. 2. A, IVP demonstrates filling defect. B, separation of pelviocaliceal system echo complex. Note lack of acoustic shadowing and some low intensity echoes in separation. Diagnosis is transitional cell carcinoma of renal pelvis.
! L
16
MULHOLLAND AND ASSOCIATES
Case reports of 12 patients with renal filling defects Case No.
IVP
Ultrasound Findings
1
Non-visualization bilat.
Bilat. echo-dense areas, acoustical shadowing, hydronephrosis
2
Non-visualization It. kidney
Echo-dense area, 1.5 x 1.5 cm., It. renal pelvis, acoustical shadowing
3
Non-opaque filling defect, rt. renal pelvis, 2.5 x 1.5 cm. Non-opaque filling defect, rt. lower pole calix, 1.5 x 2 cm. Non-opaque filling defect, It. lower pole, 2 x 2cm. Non-opaque filling defect, It. renal pelvis, 2 x 3 cm. Non-opaque filling defect, rt. lower pole calix, 1.5 x 2 cm. Non-opaque filling defect, rt. renal pelvis, 3 x 5cm. 2 non-opaque filling defects, It. renal pelvis and lower calix, 2 x 2 cm., 1.5 x 1.5 cm. Non-opaque filling defect, It. renal pelvis, 4 x 4cm.
Echo-dense area, rt. renal pelvis, acoustical shadowing Echo-dense area, lower pole, acoustical shadowing Echo-dense area, It. lower pole, acoustical shadowing Echo-dense area, It. renal pelvis, acoustical shadowing Echo-dense area, rt. lower pole, acoustical shadowing Echo-dense area, rt. renal pelvis, acoustical shadowing Echo-dense areas, It. kidney, acoustical shadowing Lt. hydronephrosis, moderate number of echos in renal pelvis, no acoustical shadowing Echo-dense mass, upper rt. collecting system, no acoustical shadowing Parenchymal mass involving collecting system, no acoustical shadowing
4
5 6 7 8
9 10 11
12
Non-opaque filling defect, rt. renal pelvis, middle and upper calix, 4 x 4 cm. Non-opaque filling defect, rt. upper pole calix, 2 x 3 cm.
and, if a ureteral calculus also is present, the dilated proximal ureter may be visualized. REFERENCES
1. Thomas, W. C., Jr.: Symposium on renal lithiasis. Medical aspects of renal calculous disease. Treatment and prophylaxis. Urol. Clin. N. Amer., 1: 261, 1974. 2. Leopold, G. R., Amberg, J., Gosink, B. B. and Mittelstaedt, C.: Gray scale ultrasonic cholecystography: a comparison with conventional radiographic techniques. Radiology, 121: 445, 1976. 3. Cook, J. H., III and Lytton, B.: Intraoperative localization of renal calculi during nephrolithotomy by ultrasound scanning. J. Urol., 117: 543, 1977. 4. Cunningham, J. J. and Cunningham, M.A.: Characterization of renal stone models with gray scale echography. Urology, 7: 315, 1976. 5. Holmes, J. H.: Urologic ultrasonography. In: Diagnostic Ultrasound. Edited by D. King. St. Louis: The C. V. Mosby Co., p. 253, 1974. 6. Pollack, H. M. and Goldberg, B. B.: Kidney. In: Abdominal Gray Scale Ultrasonography. Edited by B. B. Goldberg. New York: John Wiley & Sons, Inc., p. 303, 1977.
Diagnosis Surgically proved uric acid staghorn calculus on It. side. Presumptive uric acid calculus responded to medical treatment on rt. side Clinically diagnosed uric acid stone. Previous operation, rt. kidney, uric acid stone. Responded to dissolution with medical treatment Surgically proved uric acid stone Clinically diagnosed, pt. declined operation Clinically diagnosed uric acid stone. Surgically proved uric acid stone in recent past Surgically proved uric acid stone Surgically proved uric acid stone Surgically proved uric acid stone Clinical diagnosis, uric acid stone. Passed uric acid stones in past Surgically proved transitional cell Ca Surgically proved transitional cell Ca Surgically proved mesenchymal tumor
7. Sanders, R. C.: Renal ultrasound. Rad. Clin. N. Amer., 13: 417, 1975. 8. Edell, S. and Zegel, H.: Ultrasonic evaluation of renal calculi. Amer. J. Roentgen., 130: 261, 1978. 9. Kressel, H. Y. and Filly, R. A.: Ultrasonographic appearance of gas-containing abscesses in the abdomen. Amer. J. Roentgen., 130: 71, 1978. 10. Duffy, P., Ryan, J. and Aldous, W.: Ultrasound demonstration of a 1.5 cm. intrarenal angiomyolipoma. J. Clin. Ultrasound, 5: 111, 1977. EDITORIAL COMMENT The practical management of a filling defect in the pelvis, found on an IVP, is difficult because it may represent blood clot, renal cyst, uric acid calculus or transitional cell carcinoma. These authors describe the use of ultrasound to differentiate between transitional cell cancer and stone. Since a finding of acoustic shadowing owing to stone is a positive finding one can depend upon it to indicate that one is dealing with a uric acid stone, thus allowing conservative management. Whether all uric acid calculi cause acoustic shadowing remains to be proved with a larger series. Whether peripelvic cysts of the size that causes a problem in the renal pelvis can be reliably differentiated from the other possible lesions also is a must point. R.C.S.
THE JOURNAL OF UROLOGY
Copyright © 1979 by The Williams & Wilkins Co.
ULTRASONIC DIFFERENTIATION OF RENAL PELVIC FILLING DEFECTS S. GRANT MULHOLLAND,* PETER H. ARGER, BARRY B. GOLDBERG
AND
HOWARD M. POLLACK
From the Division of Urology, Departments of Surgery and Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania
ABSTRACT
We herein describe 9 patients with non-opaque calculi and 3 patients with soft tissue filling defects in the renal pelvis studied by ultrasound. The calculi varied in size from 1.5 cm. to staghorn calculi. All stones were imaged satisfactorily by ultrasound, allowing the diagnosis of stone to be made with confidence. Ultrasonic differentiation ofrenal pelvic filling defects proved to be a simple, reliable, non-invasive method to differentiate these clinically perplexing lesions. Renal pelvic filling defects often present a perplexing diagnostic problem for the urologist. To plan treatment a simple, reliable, non-invasive diagnostic aid is needed. The clear demonstration of a filling defect on excretory urography (IVP) or retrograde pyelography often does not present a conclusive diagnosis. The lesion may be one of many different diagnoses. When the impaired renal function in the patient or reluctance to perform retrograde pyelography by the surgeon (as in some cases of renal infection) precludes the use of opaque contrast medium ancillary methods of diagnosis must be sought. There are few, if any, critical assessments in the literature of ultrasound in the diagnosis of nephrolithiasis and other renal pelvic lesions. We herein describe our experience with ultrasound in the diagnosis of non-opaque renal filling defects. There were 9 non-opaque renal calculi, 2 renal pelvic tumors and 1 parenchymal neoplasm invading the pelvis shown on IVP. Satisfactory differentiation of stone versus soft tissue was attained by ultrasound.
rare xanthme and mucoid matrix stones also are non-opaque. Because of the gross similarity in roentgenographic appearances between non-opaque calculi and some transitional cell tumors (fig. 2, A) of the renal pelvis and calices, it often is not possible to distinguish between them radiologically so interventional procedures such as endoscopic brush biopsy or surgical exploration must be used for this purpose. For this reason, an alternate method of diagnosis is sorely needed. Ultrasound is of proved value in the diagnosis of opaque and non-opaque biliary tract calculi. 2 There have been reports on the use of ultrasound in renal stone disease but none specifically has used ultrasound to differentiate between non-opaque calculi and renal pelvic neoplasms.3--8 We postulated that nonopaque renal calculi should lend themselves to in vivo detection by ultrasound as readily as do biliary stones. Reports of in vitro experiments on renal calculi4 as well as experiences with ultrasonography of the surgically exposed kidney further strengthened this belief. 3 In our investigation 9 patients with non-opaque calculi had the stones imaged satisfactorily by ultrasound (see table). These findings were conclusive enough to suggest that this diagnostic aid may have an important place for patients with renal pelvic filling defects or for those patients at risk for the development of uric acid stones. In 1 patient diminution of uric acid stone size was documented clearly ultrasonically during medical treatment. In each of the 9 patients the stone was represented by an echo-dense pattern associated with pronounced sound attenuation producing a strong acoustical shadowing effect (echo-free zone) beyond the calculus (fig. 1, B). Our experience with filling defects other than stone (cases 10, 11 and 12) indicates that no significant acoustical shadow effect is produced by soft tissue masses in the renal pelvis (fig. 2, B). Therefore, the differences between these 2 ultrasonic patterns seems to be strongly suggestive, if not diagnostic, of stone disease. The differential diagnosis of acoustical shadowing within the kidney is limited. Other than renal calculi only internal gas can produce acoustical shadowing. The presence of gas should be detectable easily on the plain film abdominal roentgenograms. Abscesses containing micro air bubbles9 and angiomyolipomas10 can produce intense echoes. If ultrasound proves to be a consistently reliable method of differentiating non-opaque stones from renal pelvic soft tissue lesions it might well represent an important contribution, since uric acid calculi can be treated medically and may, at times, be completely dissolved without surgical intervention. 1 We have imaged renal calculi measuring 1.5 x 1.5 cm. with clarity. The limits of ultrasonic resolution of renal calculi have yet to be determined. Ultrasound can demonstrate accurately the degree of associated hydronephrosis when present
METHOD
The ultrasonic examinations were done with a standard commercially available scanner. Medium focused 2.25 and 3.5 m.Hz. transducers were used and over scanning was avoided with a single pass scanning technique. Patients were examined in the prone and, when appropriate, supine and decubitus positions. Transverse and longitudinal images were obtained in all cases. DISCUSSION
Renal pelvic filling defects may have many different etiologies and, therefore, present a perplexing problem for the urologist. Unfortunately, the diagnosis often cannot be assured by merely outlining the defects with contrast material. Arteriography seldom is conclusive. A simple, reliable, noninvasive diagnostic aid is needed to plan treatment. The most important clinical question to answer quickly is whether this defect is soft tissue or sto~e. If there is good evidence of stone causing the filling defect the approach might be entirely medical, thus saving the patient an operation. Clinical trials of regimens to dissolve stones have been advocated by some1 but this seems clinically unwise unless there is conclusive evidence that the defect is a stone. Among the most common filling defects in the renal pelvis are those produced by non-opaque calculi. Such stones usually are composed of uric acid or urates (fig. 1, A), although the Accepted for publication August 4, 1978. Read at annual meeting of American Urological Association, Washington, D. C., May 21-25, 1978. * Current address: Department of Urology, Thomas Jefferson University, 1025 Walnut St., Philadelphia, Pennsylvania 19107.
14
ULTRASONIC DIFFERENTIATION OF RENAL PELVIC FILLING DEFECTS
15
FIG. 1. A, IVP demonstrates large filling defect within renal pelvis. B, ultrasound demonstrates echo-dense area with acoustical shadowing (arrow). Diagnosis is uric acid calculus.
FIG. 2. A, IVP demonstrates filling defect. B, separation of pelviocaliceal system echo complex. Note lack of acoustic shadowing and some low intensity echoes in separation. Diagnosis is transitional cell carcinoma of renal pelvis.
! L
16
MULHOLLAND AND ASSOCIATES
Case reports of 12 patients with renal filling defects Case No.
IVP
Ultrasound Findings
1
Non-visualization bilat.
Bilat. echo-dense areas, acoustical shadowing, hydronephrosis
2
Non-visualization It. kidney
Echo-dense area, 1.5 x 1.5 cm., It. renal pelvis, acoustical shadowing
3
Non-opaque filling defect, rt. renal pelvis, 2.5 x 1.5 cm. Non-opaque filling defect, rt. lower pole calix, 1.5 x 2 cm. Non-opaque filling defect, It. lower pole, 2 x 2cm. Non-opaque filling defect, It. renal pelvis, 2 x 3 cm. Non-opaque filling defect, rt. lower pole calix, 1.5 x 2 cm. Non-opaque filling defect, rt. renal pelvis, 3 x 5cm. 2 non-opaque filling defects, It. renal pelvis and lower calix, 2 x 2 cm., 1.5 x 1.5 cm. Non-opaque filling defect, It. renal pelvis, 4 x 4cm.
Echo-dense area, rt. renal pelvis, acoustical shadowing Echo-dense area, lower pole, acoustical shadowing Echo-dense area, It. lower pole, acoustical shadowing Echo-dense area, It. renal pelvis, acoustical shadowing Echo-dense area, rt. lower pole, acoustical shadowing Echo-dense area, rt. renal pelvis, acoustical shadowing Echo-dense areas, It. kidney, acoustical shadowing Lt. hydronephrosis, moderate number of echos in renal pelvis, no acoustical shadowing Echo-dense mass, upper rt. collecting system, no acoustical shadowing Parenchymal mass involving collecting system, no acoustical shadowing
4
5 6 7 8
9 10 11
12
Non-opaque filling defect, rt. renal pelvis, middle and upper calix, 4 x 4 cm. Non-opaque filling defect, rt. upper pole calix, 2 x 3 cm.
and, if a ureteral calculus also is present, the dilated proximal ureter may be visualized. REFERENCES
1. Thomas, W. C., Jr.: Symposium on renal lithiasis. Medical aspects of renal calculous disease. Treatment and prophylaxis. Urol. Clin. N. Amer., 1: 261, 1974. 2. Leopold, G. R., Amberg, J., Gosink, B. B. and Mittelstaedt, C.: Gray scale ultrasonic cholecystography: a comparison with conventional radiographic techniques. Radiology, 121: 445, 1976. 3. Cook, J. H., III and Lytton, B.: Intraoperative localization of renal calculi during nephrolithotomy by ultrasound scanning. J. Urol., 117: 543, 1977. 4. Cunningham, J. J. and Cunningham, M.A.: Characterization of renal stone models with gray scale echography. Urology, 7: 315, 1976. 5. Holmes, J. H.: Urologic ultrasonography. In: Diagnostic Ultrasound. Edited by D. King. St. Louis: The C. V. Mosby Co., p. 253, 1974. 6. Pollack, H. M. and Goldberg, B. B.: Kidney. In: Abdominal Gray Scale Ultrasonography. Edited by B. B. Goldberg. New York: John Wiley & Sons, Inc., p. 303, 1977.
Diagnosis Surgically proved uric acid staghorn calculus on It. side. Presumptive uric acid calculus responded to medical treatment on rt. side Clinically diagnosed uric acid stone. Previous operation, rt. kidney, uric acid stone. Responded to dissolution with medical treatment Surgically proved uric acid stone Clinically diagnosed, pt. declined operation Clinically diagnosed uric acid stone. Surgically proved uric acid stone in recent past Surgically proved uric acid stone Surgically proved uric acid stone Surgically proved uric acid stone Clinical diagnosis, uric acid stone. Passed uric acid stones in past Surgically proved transitional cell Ca Surgically proved transitional cell Ca Surgically proved mesenchymal tumor
7. Sanders, R. C.: Renal ultrasound. Rad. Clin. N. Amer., 13: 417, 1975. 8. Edell, S. and Zegel, H.: Ultrasonic evaluation of renal calculi. Amer. J. Roentgen., 130: 261, 1978. 9. Kressel, H. Y. and Filly, R. A.: Ultrasonographic appearance of gas-containing abscesses in the abdomen. Amer. J. Roentgen., 130: 71, 1978. 10. Duffy, P., Ryan, J. and Aldous, W.: Ultrasound demonstration of a 1.5 cm. intrarenal angiomyolipoma. J. Clin. Ultrasound, 5: 111, 1977. EDITORIAL COMMENT The practical management of a filling defect in the pelvis, found on an IVP, is difficult because it may represent blood clot, renal cyst, uric acid calculus or transitional cell carcinoma. These authors describe the use of ultrasound to differentiate between transitional cell cancer and stone. Since a finding of acoustic shadowing owing to stone is a positive finding one can depend upon it to indicate that one is dealing with a uric acid stone, thus allowing conservative management. Whether all uric acid calculi cause acoustic shadowing remains to be proved with a larger series. Whether peripelvic cysts of the size that causes a problem in the renal pelvis can be reliably differentiated from the other possible lesions also is a must point. R.C.S.
