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Role of Scintillation Scanning in Diagnosis of Renal Tumors
THE JOliR:N"AL OF UROLOGY
Vol. 87, No. 6 June 1962 Copyright © 1962 by The Williams & Wilkins Co. Printed in U.S.A.
ROLE OF SCINTILLATION SCANNI~G IN DIAGNOSIS OF RENAL TUMORS BRUCE H, STEWART, THOMAS P. HAYNIE, MOHAMED M. NOFAL EDWARD A. CARR, JR.
AND
From the Departments of Surgery, Internal JVIedieine, Pharmacology, and the Clinical Radioisotope Unit of the University of Michigan Medical Center, Ann Arbor, Mich.
Recent adYances in radioisotope techniques haYe made it possible to perform scintillation scanning of the human kidney. Following intravenous infusion, certain radioactive substances become highly concentrated in the kidneys, and
paratus. The radioisotope concentration over normally functioning renal parenchyma is good, whereas the concentration owr diseased parenchyma may be relatiYely poor. vVagner and associates1 described the advan-
FIG. 1. H. W., 52-year-old white man. A, excretory urogram shows large, poorly functioning left kidney. B, radioactive mercury renoscan shows extensive replacement of renal parenchyrna on left.
the outline of functioning renal parenchyma can then be recorded by scintillation scanning apAccepted for publication October 13, 1961. Supported by a grant from the Michigan Memorial Phoenix Project No. 200 of the University of Michigan, and the Atomic Energy Commission, Project 15. 782
tages of radioactive mercury and of photorecording in the technique of renal scintillation scanning, and felt that the procedure would be 1 Wagner, H. N., Jr., McAfee, J. G. and Mozley, J. M.: Medical radioisotope scanning. J.A.M.A., 174: 162, 1960.
DIAG?\OSIS OF Rl~NAL TlTMORS BY SCINTILLATION SCAXKI~G
FIG. 2. Sarne case as fig. . Retrograde pyelogram demonstrates tumor deformity of left kidney and operation large hypernephroma replacing most of left kidney was removed.
FrG. 3. A. D., 60-year-old. white rnan -with polycythcmia. A, excretory urogram shows lnrgo mass overlying lower pole of left kidney. Little evidence of calyccal distortion. Opinion divided as to ,Yheilim· or not mass wa,.c, extraremd in origin. HyperneJihronw (i by Ci cm. was found at operation arising frorn lower pole of left kidney. B, rndioactive mercury renoscan showed significant loss of functioning tissue in left lower pole. Smooth border of deformity sLrggestcd cyst, demonstrating inability of renoscan to differentiate bet1i-cen benign ancl malignant lesions. ~ote irregular projections over right kidm,~,, c,rnsed by lateral motion of patient during period of scanning;.
784
BRUCE H. STEWART AND ASSOCIATES
FIG. 4. J. W., 64-year-old man with unexplained anemia. A, excretory urogram shows suggestive widening of upper pole of left kidney. Calyces not seen well enough to establish diagnosis of tumor deformity. B, radioactive mercury renoscan shows extensive replacement of left kidney, particularly upper half. Palliative left nephrectomy done later for large invasive hypernephroma. Note "cold" area in remaining lower pole tissue which was benign cyst unrelated to carcinoma.
of diagnostic value in patients with renal vascular disease. The presence of experimental renal infarcts has been demonstrated in laboratory animals by renoscan, and the technique has subsequently been shown to be helpful in evaluating patients with renal hypertension 2 • 3 McAfee 2 Haynie, T. P., Nofal, M., Carr, E. A., Jr. and Beierwaltes, W. H.: Scintillation scanning of the kidney with radio-iodinated contrast media. Clin. Res., 8: 288, 1960. 3 Haynie, T. P., Stewart, B. H., Nofal, M. JYI., Carr, E. A., Jr. and Beierwaltes, W. H.: Renal scintiscans in the diagnosis of renal vascular disease. J. Nucl. Med., 2: 272-281, 1961.
and associates 4 showed that space-occupying lesions of the kidney presented as filling defects on renoscan, and that these "cold areas" represented the portion of renal parenchyma replaced by tumor. An attempt will be made here to more completely evaluate the role of the renoscan in patients with suspected renal tumors, outlining both the advantages as well as the apparent drawbacks of this new diagnostic technique. 4 McAfee, J. G. and Wagner, H. :I'\., Jr.: Visualization of renal parenchyma by scintiscanning with Hg 203 -neohydrin. Radio!., 75: 820, 1960.
DIAGNOSIS OF RENAL TUMORS BY SCINTILLATION SCANNING
785
Fm. 5. B. B., 53-year-old woman with asymptomatic right flank mass. A, excretory urogram showed tumor deformity on right. B, renoscan did not show evidence of tumor. Operation disclosed large hypernephroma arising from anterior surface of right kidney. Fact that entire posterior three-fourths of kidney was uninvolved by neoplasm probably accounts for normal scan. MATERIALS AND METHODS
Renal scintillation scanning was performed on 18 patients with suspected renal tumor. The final diagnosis was confirmed by operative exploration in 13 of these patients. All patients have received Hg-203-labeled neohydrin * which so far has proven to be the most satisfactory substance for use in renal scintillation scanning. 5 The usual dose has been 100 µc. given as a single intravenous injection. Forty-five minutes later the patient is placed in the prone position and scanning begun over the renal area. The instrument used for scintillation scanningt employed a 3 inch by 2 inch thallium-activated sodium iodide crystal with a 19-hole focusing collimator, a pulse height selector, and a photorecorder. X-ray film was used for photoscanning and a direct-recording stylus produced a simultaneous dot-scan for the convenience of the
* Abbott and Squibb Laboratories. t Picker magnascanner. 5 Carr, E. A., Jr., Haynie, T. P., Stewart, B. H., Nofal, M. M. and Beierwaltes, W. H.: Scintillation scanning of the human kidney. Univ. of Mich. Med. Bull., 27: 244-2621961.
operator. 6 The total scanning time averaged one hour. RESULTS
A). Renal carcinoma. Renal scintillation scanning was performed on 8 patients who subsequently underwent nephrectomy for malignant disease. Hypernephroma was found in seven and an invasive transitional cell carcinoma of the upper calyces in one. The renoscan was abnormal in seven of the 8 cases showing significant decrease in uptake over the tumor area. The excretory urogram was diagnostic of tumor deformity in only four of the 8 cases. In two of the remaining 4 patients, the excretory urogram showed only a large, poorly functioning kidney on the side of suspected disease, and retrograde pyelograms were necessary to establish the presence of neoplasm. An example of this sequence of events is shown in figures 1 and 2. The remaining 2 patients are of interest in that the excretory urogram did not show con6 Haynie, T. P., Nofal, M. M., Carr, E. A., Jr. and Beierwaltes, W. H.: The use of P 31 -labeled contrast media in scintillation scanning of the kidney. J. Lab. & Clin. Med., 58: 598, 1961.
786
BRUCE H. STEWART AND ASSOCIATES
FIG. 6. L.B., 49-year-old man with intermittent right flank pain. A, excretory urogram sho,ved bulge over lateral aspect of right kidney. B, radioactive mercury renoscan showed normal isotope uptake over area of suspected tumor. Renal exploration later revealed only fetal lobulation. Biopsy showed no evidence of neoplasm.
elusive evidence of a tumor deformity, while the renoscan showed definite and extensive renal parenchymal replacement. One patient (fig. 3) had a large mass projecting over the lmver pole of the left kidney on the excretory urogram. However, the calyces were not distorted, and many observers felt that the mass was extrarenal in nature. The renoscan showed significant abnormality of the lower pole of the left kidney, and at operation this proved to be a large hypernephroma. The other patient (fig. 4) had excretory urography performed on two occasions during evaluation of unexplained anemia. Al-
though there was suggestion of widening of the upper pole of the left kidney, there vrns no definite evidence of calyceal distortion and the pyelograms were felt by some obscrwrs to be probably normal. However, the renoscan showed extensive destruction on the left, and nephrectomy was subsequently performed ,vith subtotal removal of a large invasive hypernephroma. One further patient in this series is of extreme interest, and constitutes the only false negative renoscan found to date in patients with malignant renal neoplasms. This patient ,vas found to have a large right abdominal mass on routine physical
DIAGNOSIS OF RENAL TUMORS BY SCINTILLATION SCANNING
787
:·.~. T
• LEFT
Fm. 7. R. G., 45-year-old man with suspected renal hypertension. A, excretory urogram interpreted as probably normal. Suggestive widening of lateral aspect of right kidney could not be differentiated with certainty from bowel shadows. B, radioactive mercury renoscan showed large defect in renal parenchyma on right. examination, and an excretory urogram showed definite calyceal distortion on the right. The renoscan did not show evidence of parenchymal replacement by tumor (fig. 5). However, at operation a 5 by 6 cm. hypernephroma was found arising superficially from the anterior surface of the right kidney. The fact that the entire posterior surface of the kidney, involving perhaps three-fourths of the thickness of the parenchyma, was uninvolved by tumor probably accounted for failure of the scan to detect an abnormality. Also studied were 2 patients who had pyelographic evidence of renal neoplasm, but were not explored because of extensive metastases. The renoscan showed extensive parenchymal abnormality over the suspected tumor area in both cases. B) Fetal lobulation. One patient subsequently found to have fetal lobulation was studied because of the possibility of renal neoplasm. His excretory urogram showed an abnormal bulge
Fm. 8. Nephrogram phase of aortogram showed large lucent areas over upper aspect of left kidney and lateral aspect of right kidney. Operation disclosed 3 by 4 cm. cyst in left upper pole and 4 by 5 cm. cyst in lower lateral aspect of right kidney. Both cysts unroofed; hypertension unchanged 12 months after operation. Renoscan failed to show abnormality on left due to fact that cyst on that side did not significantly compress renal parenchyma.
788
BRUCE H. STEWART A::\'D ASSOCIATES
Right
Hg-N
Left
Fm. 9. C. T ., 56-year-old man. A, excretory urogram showed tumor deformity of lower and middle calyces on right. Distortion of upper calyces not apparent. B, radioactive mercury renoscan showed destruction of renal parenchyma over lower lateral aspect on right. Irregular contour here was caused by presence of 2 cysts, but could easily be confused with irregular replacement by neoplasm. Area of slightly reduced isotope concentration in upper pole on right corresponded to smaller cyst found there at operation. over the lateral aspect of the right kidney. The renoscan did not reveal any evidence of parenchymal destruction (fig. 6) and at operation a large fetal lobulation was found, biopsy of which showed no evidence of neoplasm. C) Renal cyst. Renal scintillation scanning was performed on 5 patients subsequently found to have solitary or multiple cysts. The renoscan was abnormal in but three of the 5 patients. Definite renoscan defects appeared only in those cases where the cyst compressed a relatively large area of parenchyma. Cysts located in the periphery of the kidney and bulging primarily outward, although sometimes as large as 4 cm. in diameter, did not produce an abnormality on the renoscan (figs. 7 and 8). Difficulty also arose in trying to differentiate
cyst from neoplasm on the basis of the renoscan. One patient (fig. 9) had a renoscan which was quite suggestive of infiltrating carcinoma, but at operation was found only to have multiple cysts in the central portion of the kidney. DISCUSSION
The clinician is occasionally faced with the problem of managing a patient suspected of having a renal neoplasm where the excretory urogram fails to definitely demonstrate the presence of a tumor. A retrograde pyelogram may not clarify the situation if there is little or no calyceal distortion by the tumor. Special studies such as aortography7 • 8 or nephrotomog7 Evans, A. T.: Renal cancer: Translumbar aortography for its recognition. Radiol., 69: 657663, 1957.
DIAGNOSIS OF RENAL TUMORS BY SCINTILLATION SCANNING
raphy 9 have been used with some success in doubtful cases, although these procedures are not without risk and are also occasionally misleading. Renal scintillation scanning can be of great value in establishing the diagnosis in these cases. Renal cell carcinomas destroy functioning parenchyma and produce a decrease in radioisotope concentration over the tumor area. This "cold" area on the renoscan often far exceeds the estimated size of the tumor as judged by the pyelogram, and may give a fairly accurate picture of the extent of renal parenchymal destruction by the neoplasm prior to operation. This may hold true in cases of transitional cell carcinoma of the renal pelvis as well as those of hypernephroma. In the one case of transitional cell carcinoma in this series, the renoscan predicted extensive invasion of the upper pole of the left kidney, and this was confirmed at operation. Fetal lobulation may so distort the renal outline on the pyelogram that the presence of tumor may be suspected. In this situation the renoscan shows no decrease in isotope concentration over the area of suspected abnormality, thus ruling out the presence of renal cyst or neoplasm. There are several distinct advantages of the renoscan over other special techniques used to establish the diagnosis of tumor in doubtful cases. Renal scintillation scanning has so far proven to be entirely safe and can be done without discomfort to the patient. The state of hydration, presence of excessive intestinal gas, degree of obesity, and other factors which may prevent a good x-ray examination do not adversely affect the quality of the renoscan. Since radioactive mercury is used in renal scintillation scanning, the test can be of great value in patients sensitive to organic iodides. While the renoscan can be extremely helpful in selected situations, certain limitations must 8 Creevy, C. D. and Price, W. E.: Differentiation of renal cysts from neoplasms by abdominal aortography: Pitfalls. Radio!., 64: 831, 1955. 9 Evans, J. A., Dubilier, W., Jr. and Monteith, J.C.: Nephrotomography. Radio!., 64: 655, 1955.
789
be considered. In the first place, the renoscan cannot give a visual image of the calyceal pattern and is not intended to replace the pyelogram as the initial diagnostic study in patients with suspected renal tumor. In the second place, it has so far been extremely difficult to differentiate cyst from neoplasm on the basis of the scan. Finally, the scan will fail to reveal a cyst or neoplasm which arises from the extreme periphery of the kidney and which consequently does not compress or replace functioning renal tissue. Small lesions less than 2 cm. in diameter may be missed regardless of location, although complete information on this point is lacking. In spite of its limitations, however, the renoscan may be a valuable aid in the diagnosis of renal tumors when used in conjunction with routine excretory urography. The need for special studies which may carry unnecessary risk to the patient can often be avoided by judicious use of the renal scintillation scan. SUMMARY AND CONCLUSIONS
Renal scintillation scanning was performed on 13 patients later explored for renal tumor. The scan demonstrated an abnormality in seven of eight cases with renal neoplasm, and in three of five cases with renal cyst. The renoscan was of particular help in establishing the diagnosis of tumor where pyelographic evidence was equivocal or lacking. This occurred in one of 5 patients with renal cyst and in two of 8 patients with renal neoplasm. Preoperative renal scintillation scanning may reveal the extent of parenchymal invasion by tumor much more accurately than can be done by pyelographic techniques alone. The difference between renal cysts and neoplasms cannot be reliably determined on the basis of the renoscan, and the scan may fail to detect tumors of either type which do not significantly replace functioning renal tissue. When used as an adjunct to excretory urography in selected cases, the renoscan can be of considerable help in evaluating the patient with suspected renal tumor.
Vol. 87, No. 6 June 1962 Copyright © 1962 by The Williams & Wilkins Co. Printed in U.S.A.
ROLE OF SCINTILLATION SCANNI~G IN DIAGNOSIS OF RENAL TUMORS BRUCE H, STEWART, THOMAS P. HAYNIE, MOHAMED M. NOFAL EDWARD A. CARR, JR.
AND
From the Departments of Surgery, Internal JVIedieine, Pharmacology, and the Clinical Radioisotope Unit of the University of Michigan Medical Center, Ann Arbor, Mich.
Recent adYances in radioisotope techniques haYe made it possible to perform scintillation scanning of the human kidney. Following intravenous infusion, certain radioactive substances become highly concentrated in the kidneys, and
paratus. The radioisotope concentration over normally functioning renal parenchyma is good, whereas the concentration owr diseased parenchyma may be relatiYely poor. vVagner and associates1 described the advan-
FIG. 1. H. W., 52-year-old white man. A, excretory urogram shows large, poorly functioning left kidney. B, radioactive mercury renoscan shows extensive replacement of renal parenchyrna on left.
the outline of functioning renal parenchyma can then be recorded by scintillation scanning apAccepted for publication October 13, 1961. Supported by a grant from the Michigan Memorial Phoenix Project No. 200 of the University of Michigan, and the Atomic Energy Commission, Project 15. 782
tages of radioactive mercury and of photorecording in the technique of renal scintillation scanning, and felt that the procedure would be 1 Wagner, H. N., Jr., McAfee, J. G. and Mozley, J. M.: Medical radioisotope scanning. J.A.M.A., 174: 162, 1960.
DIAG?\OSIS OF Rl~NAL TlTMORS BY SCINTILLATION SCAXKI~G
FIG. 2. Sarne case as fig. . Retrograde pyelogram demonstrates tumor deformity of left kidney and operation large hypernephroma replacing most of left kidney was removed.
FrG. 3. A. D., 60-year-old. white rnan -with polycythcmia. A, excretory urogram shows lnrgo mass overlying lower pole of left kidney. Little evidence of calyccal distortion. Opinion divided as to ,Yheilim· or not mass wa,.c, extraremd in origin. HyperneJihronw (i by Ci cm. was found at operation arising frorn lower pole of left kidney. B, rndioactive mercury renoscan showed significant loss of functioning tissue in left lower pole. Smooth border of deformity sLrggestcd cyst, demonstrating inability of renoscan to differentiate bet1i-cen benign ancl malignant lesions. ~ote irregular projections over right kidm,~,, c,rnsed by lateral motion of patient during period of scanning;.
784
BRUCE H. STEWART AND ASSOCIATES
FIG. 4. J. W., 64-year-old man with unexplained anemia. A, excretory urogram shows suggestive widening of upper pole of left kidney. Calyces not seen well enough to establish diagnosis of tumor deformity. B, radioactive mercury renoscan shows extensive replacement of left kidney, particularly upper half. Palliative left nephrectomy done later for large invasive hypernephroma. Note "cold" area in remaining lower pole tissue which was benign cyst unrelated to carcinoma.
of diagnostic value in patients with renal vascular disease. The presence of experimental renal infarcts has been demonstrated in laboratory animals by renoscan, and the technique has subsequently been shown to be helpful in evaluating patients with renal hypertension 2 • 3 McAfee 2 Haynie, T. P., Nofal, M., Carr, E. A., Jr. and Beierwaltes, W. H.: Scintillation scanning of the kidney with radio-iodinated contrast media. Clin. Res., 8: 288, 1960. 3 Haynie, T. P., Stewart, B. H., Nofal, M. JYI., Carr, E. A., Jr. and Beierwaltes, W. H.: Renal scintiscans in the diagnosis of renal vascular disease. J. Nucl. Med., 2: 272-281, 1961.
and associates 4 showed that space-occupying lesions of the kidney presented as filling defects on renoscan, and that these "cold areas" represented the portion of renal parenchyma replaced by tumor. An attempt will be made here to more completely evaluate the role of the renoscan in patients with suspected renal tumors, outlining both the advantages as well as the apparent drawbacks of this new diagnostic technique. 4 McAfee, J. G. and Wagner, H. :I'\., Jr.: Visualization of renal parenchyma by scintiscanning with Hg 203 -neohydrin. Radio!., 75: 820, 1960.
DIAGNOSIS OF RENAL TUMORS BY SCINTILLATION SCANNING
785
Fm. 5. B. B., 53-year-old woman with asymptomatic right flank mass. A, excretory urogram showed tumor deformity on right. B, renoscan did not show evidence of tumor. Operation disclosed large hypernephroma arising from anterior surface of right kidney. Fact that entire posterior three-fourths of kidney was uninvolved by neoplasm probably accounts for normal scan. MATERIALS AND METHODS
Renal scintillation scanning was performed on 18 patients with suspected renal tumor. The final diagnosis was confirmed by operative exploration in 13 of these patients. All patients have received Hg-203-labeled neohydrin * which so far has proven to be the most satisfactory substance for use in renal scintillation scanning. 5 The usual dose has been 100 µc. given as a single intravenous injection. Forty-five minutes later the patient is placed in the prone position and scanning begun over the renal area. The instrument used for scintillation scanningt employed a 3 inch by 2 inch thallium-activated sodium iodide crystal with a 19-hole focusing collimator, a pulse height selector, and a photorecorder. X-ray film was used for photoscanning and a direct-recording stylus produced a simultaneous dot-scan for the convenience of the
* Abbott and Squibb Laboratories. t Picker magnascanner. 5 Carr, E. A., Jr., Haynie, T. P., Stewart, B. H., Nofal, M. M. and Beierwaltes, W. H.: Scintillation scanning of the human kidney. Univ. of Mich. Med. Bull., 27: 244-2621961.
operator. 6 The total scanning time averaged one hour. RESULTS
A). Renal carcinoma. Renal scintillation scanning was performed on 8 patients who subsequently underwent nephrectomy for malignant disease. Hypernephroma was found in seven and an invasive transitional cell carcinoma of the upper calyces in one. The renoscan was abnormal in seven of the 8 cases showing significant decrease in uptake over the tumor area. The excretory urogram was diagnostic of tumor deformity in only four of the 8 cases. In two of the remaining 4 patients, the excretory urogram showed only a large, poorly functioning kidney on the side of suspected disease, and retrograde pyelograms were necessary to establish the presence of neoplasm. An example of this sequence of events is shown in figures 1 and 2. The remaining 2 patients are of interest in that the excretory urogram did not show con6 Haynie, T. P., Nofal, M. M., Carr, E. A., Jr. and Beierwaltes, W. H.: The use of P 31 -labeled contrast media in scintillation scanning of the kidney. J. Lab. & Clin. Med., 58: 598, 1961.
786
BRUCE H. STEWART AND ASSOCIATES
FIG. 6. L.B., 49-year-old man with intermittent right flank pain. A, excretory urogram sho,ved bulge over lateral aspect of right kidney. B, radioactive mercury renoscan showed normal isotope uptake over area of suspected tumor. Renal exploration later revealed only fetal lobulation. Biopsy showed no evidence of neoplasm.
elusive evidence of a tumor deformity, while the renoscan showed definite and extensive renal parenchymal replacement. One patient (fig. 3) had a large mass projecting over the lmver pole of the left kidney on the excretory urogram. However, the calyces were not distorted, and many observers felt that the mass was extrarenal in nature. The renoscan showed significant abnormality of the lower pole of the left kidney, and at operation this proved to be a large hypernephroma. The other patient (fig. 4) had excretory urography performed on two occasions during evaluation of unexplained anemia. Al-
though there was suggestion of widening of the upper pole of the left kidney, there vrns no definite evidence of calyceal distortion and the pyelograms were felt by some obscrwrs to be probably normal. However, the renoscan showed extensive destruction on the left, and nephrectomy was subsequently performed ,vith subtotal removal of a large invasive hypernephroma. One further patient in this series is of extreme interest, and constitutes the only false negative renoscan found to date in patients with malignant renal neoplasms. This patient ,vas found to have a large right abdominal mass on routine physical
DIAGNOSIS OF RENAL TUMORS BY SCINTILLATION SCANNING
787
:·.~. T
• LEFT
Fm. 7. R. G., 45-year-old man with suspected renal hypertension. A, excretory urogram interpreted as probably normal. Suggestive widening of lateral aspect of right kidney could not be differentiated with certainty from bowel shadows. B, radioactive mercury renoscan showed large defect in renal parenchyma on right. examination, and an excretory urogram showed definite calyceal distortion on the right. The renoscan did not show evidence of parenchymal replacement by tumor (fig. 5). However, at operation a 5 by 6 cm. hypernephroma was found arising superficially from the anterior surface of the right kidney. The fact that the entire posterior surface of the kidney, involving perhaps three-fourths of the thickness of the parenchyma, was uninvolved by tumor probably accounted for failure of the scan to detect an abnormality. Also studied were 2 patients who had pyelographic evidence of renal neoplasm, but were not explored because of extensive metastases. The renoscan showed extensive parenchymal abnormality over the suspected tumor area in both cases. B) Fetal lobulation. One patient subsequently found to have fetal lobulation was studied because of the possibility of renal neoplasm. His excretory urogram showed an abnormal bulge
Fm. 8. Nephrogram phase of aortogram showed large lucent areas over upper aspect of left kidney and lateral aspect of right kidney. Operation disclosed 3 by 4 cm. cyst in left upper pole and 4 by 5 cm. cyst in lower lateral aspect of right kidney. Both cysts unroofed; hypertension unchanged 12 months after operation. Renoscan failed to show abnormality on left due to fact that cyst on that side did not significantly compress renal parenchyma.
788
BRUCE H. STEWART A::\'D ASSOCIATES
Right
Hg-N
Left
Fm. 9. C. T ., 56-year-old man. A, excretory urogram showed tumor deformity of lower and middle calyces on right. Distortion of upper calyces not apparent. B, radioactive mercury renoscan showed destruction of renal parenchyma over lower lateral aspect on right. Irregular contour here was caused by presence of 2 cysts, but could easily be confused with irregular replacement by neoplasm. Area of slightly reduced isotope concentration in upper pole on right corresponded to smaller cyst found there at operation. over the lateral aspect of the right kidney. The renoscan did not reveal any evidence of parenchymal destruction (fig. 6) and at operation a large fetal lobulation was found, biopsy of which showed no evidence of neoplasm. C) Renal cyst. Renal scintillation scanning was performed on 5 patients subsequently found to have solitary or multiple cysts. The renoscan was abnormal in but three of the 5 patients. Definite renoscan defects appeared only in those cases where the cyst compressed a relatively large area of parenchyma. Cysts located in the periphery of the kidney and bulging primarily outward, although sometimes as large as 4 cm. in diameter, did not produce an abnormality on the renoscan (figs. 7 and 8). Difficulty also arose in trying to differentiate
cyst from neoplasm on the basis of the renoscan. One patient (fig. 9) had a renoscan which was quite suggestive of infiltrating carcinoma, but at operation was found only to have multiple cysts in the central portion of the kidney. DISCUSSION
The clinician is occasionally faced with the problem of managing a patient suspected of having a renal neoplasm where the excretory urogram fails to definitely demonstrate the presence of a tumor. A retrograde pyelogram may not clarify the situation if there is little or no calyceal distortion by the tumor. Special studies such as aortography7 • 8 or nephrotomog7 Evans, A. T.: Renal cancer: Translumbar aortography for its recognition. Radiol., 69: 657663, 1957.
DIAGNOSIS OF RENAL TUMORS BY SCINTILLATION SCANNING
raphy 9 have been used with some success in doubtful cases, although these procedures are not without risk and are also occasionally misleading. Renal scintillation scanning can be of great value in establishing the diagnosis in these cases. Renal cell carcinomas destroy functioning parenchyma and produce a decrease in radioisotope concentration over the tumor area. This "cold" area on the renoscan often far exceeds the estimated size of the tumor as judged by the pyelogram, and may give a fairly accurate picture of the extent of renal parenchymal destruction by the neoplasm prior to operation. This may hold true in cases of transitional cell carcinoma of the renal pelvis as well as those of hypernephroma. In the one case of transitional cell carcinoma in this series, the renoscan predicted extensive invasion of the upper pole of the left kidney, and this was confirmed at operation. Fetal lobulation may so distort the renal outline on the pyelogram that the presence of tumor may be suspected. In this situation the renoscan shows no decrease in isotope concentration over the area of suspected abnormality, thus ruling out the presence of renal cyst or neoplasm. There are several distinct advantages of the renoscan over other special techniques used to establish the diagnosis of tumor in doubtful cases. Renal scintillation scanning has so far proven to be entirely safe and can be done without discomfort to the patient. The state of hydration, presence of excessive intestinal gas, degree of obesity, and other factors which may prevent a good x-ray examination do not adversely affect the quality of the renoscan. Since radioactive mercury is used in renal scintillation scanning, the test can be of great value in patients sensitive to organic iodides. While the renoscan can be extremely helpful in selected situations, certain limitations must 8 Creevy, C. D. and Price, W. E.: Differentiation of renal cysts from neoplasms by abdominal aortography: Pitfalls. Radio!., 64: 831, 1955. 9 Evans, J. A., Dubilier, W., Jr. and Monteith, J.C.: Nephrotomography. Radio!., 64: 655, 1955.
789
be considered. In the first place, the renoscan cannot give a visual image of the calyceal pattern and is not intended to replace the pyelogram as the initial diagnostic study in patients with suspected renal tumor. In the second place, it has so far been extremely difficult to differentiate cyst from neoplasm on the basis of the scan. Finally, the scan will fail to reveal a cyst or neoplasm which arises from the extreme periphery of the kidney and which consequently does not compress or replace functioning renal tissue. Small lesions less than 2 cm. in diameter may be missed regardless of location, although complete information on this point is lacking. In spite of its limitations, however, the renoscan may be a valuable aid in the diagnosis of renal tumors when used in conjunction with routine excretory urography. The need for special studies which may carry unnecessary risk to the patient can often be avoided by judicious use of the renal scintillation scan. SUMMARY AND CONCLUSIONS
Renal scintillation scanning was performed on 13 patients later explored for renal tumor. The scan demonstrated an abnormality in seven of eight cases with renal neoplasm, and in three of five cases with renal cyst. The renoscan was of particular help in establishing the diagnosis of tumor where pyelographic evidence was equivocal or lacking. This occurred in one of 5 patients with renal cyst and in two of 8 patients with renal neoplasm. Preoperative renal scintillation scanning may reveal the extent of parenchymal invasion by tumor much more accurately than can be done by pyelographic techniques alone. The difference between renal cysts and neoplasms cannot be reliably determined on the basis of the renoscan, and the scan may fail to detect tumors of either type which do not significantly replace functioning renal tissue. When used as an adjunct to excretory urography in selected cases, the renoscan can be of considerable help in evaluating the patient with suspected renal tumor.