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The value of radionuclide studies to the practicing urologist and nephrologist
The Value of Radionuclide Studies to the Practicing Urologist and Nephrologist Jorgen U. Schlegel
T
H E UTILlZA nON of scintillation-camera image studies incorporating quantitation, which is the topic dealt with in this issue of the Seminars, is a tool that to us equals in importance the emergence of radiology as it is applied to the diagnosis of renal and urinary-tract disease. The modern gamma camera, with its potential to quantitate dynamic events as well as to picture morphological occurrences, can no more be compared with the renogram as it came into being in 1955 1 than can modern television transmitter and receiver be compared with Marconi's wireless communication. It is important that the urologist and the nephrologist recognize that such modern technology can yield exeedingly useful information concerning static and dynamic events that is not obtainable by other means. It should further be recognized that renal physiology and pathophysiology can today be studied with radionuclide techniques that cause no morbidity and may be used with ease and accuracy without invasion of the urinary tract. This modern approach to renal physiology compares favorably with difficult clinical and laboratory procedures such as differential renal function studies previously used to obtain information that often was not physiological and that certainly was connected with considerable morbidity. In order for the nephrologist and urologist to properly assess the tremendous potential of nuclear medicine, it appears overdue that their training include some background in this field. At the Section of Urology at the Tulane Medical Center we have over the last 4 to 5 years performed more than 5,000 scintillation-camera studies on patients, following a standardized approach to allow not only comparison from patient to patient but also follow-up comparison of repeat studies on the same patient. The standard procedure'? requires adequate hydration, since one of the determinations made is the amount of radionuclide excreted within a 30-min period. Hippuran labeled with 1311 is routinely used as the radiopharmaceutical in the initial screening examination. The minute sequence study will reveal functional discrepancies between the two kidneys. A visual image of the two kidneys is obtained where abnormalities such as tumor or hydronephrosis may be detected. An accurate evaluation of the amount of residual urine is subsequently performed by obtaining counts over the bladder before and after urination 30 min after injection of the radioiodinated Hippuran. Utilizing this screening examination combined with urinalysis and a brief history, it is possible to determine the presence or absence of renal or urinary-tract disease above the bladder neck in 30 min. It is true that a stone or small tumor causing neither hematuria nor any degree of obstruction or renal damage can be missed. However, if there is no syrnptornatol-
From the Section of Urology, Tulane University School ofMedicine, Nell' Orleans, La. Jorgen U. Schlegel, M.D., Ph.D.: Professor and Chairman. Section 0/ Urology, Tulane University School ofMedicine, New Orleans, La. © 1974 by Grune & Stratton, Inc. Seminars in Nuclear Medicine, Vol. 4, No.2 (April), 1974
213
214
JORGEN U. SCHLEGEL
ogy associated with this condition, it is even more likely to be missed by any other diagnostic procedure as well. The amount of information that can be obtained in this fashion with a noninvasive procedure over a very short period of time is of tremendous importance to the physician and the patient alike. The number of intravenous urograms done without specific indication appears to be disproportionate to the yield of pathological findings and the morbidity involved. Such intravenous urograms are frequently not diagnostic, due to the presence of overlying gas, inadequate visualization, etc., which further makes their routine use for screening purposes a highly questionable procedure. However, this writer would in no way attempt to compare a welldone intravenous urogram with a scintillation-camera study, nor suggest that the scintillation-camera study can in any way provide the morphological details obtainable with a high-quality urogram. In fact, if the screening scintillation-camera study is abnormal and/or if hematuria is present, an intravenous urogram is considered the next logical step. Certainly there are institutions in which this order oftests might be reversed. It should be mentioned that we have never seen any allergic reaction to the administration of radioiodinated Hippuran, and scintillation-camera studies are routinely used in patients who have had even severe anaphylactic reactions to contrast media. It is thus indisputable that the radionuclide study is essential in patients who need functional evaluation of the upper urinary tract and who have had a previous reaction to contrast media. It is well recognized that an assessment of individual renal function cannot adequately be obtained by judging from the appearance of the contrast media on the urogram.v? To the urological surgeon who is faced with a situation of unilateral pathology requiring exploration of the kidney or ureter, accurate knowledge of individual kidney function may be a determining factor in the final decision in the operating room; here the quantitation that is obtainable by scintillation-camera studies in a simple way provides him with accurate and important information. In children, and particularly in newborns, an intravenous urogram is often unreliable, and we have found, along with others, that a scintillation-camera study of such patients not only involves less radiation than a pyelogram but also is much more reliable." Our pediatric experience is quite extensive, and we have routinely used radioiodinated-Hippuran camera studies not only in the initial evaluation of patients with reflux but also in follow-up examinations over a period of several years. In hypertensive patients" we use the radioiodinated-Hippuran studies as a primary procedure, and then proceed with other studies only when there is positive indication of possible renovascular hypertension. Not only do we find this a simple, noninvasive evaluation that can' accurately pinpoint a "guilty" kidney, but also a guilty portion of a kidney (segmental renal ischemia). The utilization of radioiodinated Hippuran in evaluation of transplanted kidneys, especially to evaluate rejection, goes back in our experience almost 10 years," and the scintillation camera has routinely been used for the last 4 to 5 years here, as it is in most other transplant centers. Although our experience with acute trauma is rather limited, this would appear to be an obvious area for application of the scintillation camera. It is, how-
VALUE OF RADIONUCLIDE STUDIES
215
ever, possible that 99mTc DTPA or other radiopharmaceuticals would be more useful in such cases. The morphological details obtained with radioiodinated Hippuran are not as good as those obtained using the much higher photon flux of a 99IDTc-Iabeled compound. For evaluation of parenchymal tumors, a good assessment of perfusion of a cold spot shown on a radioiodinated-Hippuran scintiphoto using 99mTc DTPA or pertechnetate can be made. It is not the purpose of this overview to go into details, which will be discussed subsequently in much greater depth, but rather to point out the tremendous impact that nuclear medicine has made on the practice of urology and nephrology. There are few patients we see who do not have radioiodinatedHippuran scintiphotography as a preliminary procedure, and it appears obvious that the cost factor can be reduced as the need for and volume of such studies increase. We have estimated that it is possible to conduct approximately 3,000 such studies per year using one camera. If five cameras were used, possibly in different locations, and tied into a computer analyzer, the cost per patient for such a study could be in the neighborhood of $25.00. For this cost, I feel that one would obtain an accurate estimate of total as well as individual renal function and an accurate estimate of residual urine, if present, as well as an estimate of the excretory function and gross morphology of the kidneys. In a large number of patients, such a study might eliminate the need for an intravenous urogram, as well as determination of residual urine by catheterization. Apart from the financial savings, the innocuousness of the procedure and the accuracy and reproducibility of the results should make it obvious that this is indeed an indispensable tool that is already here and available for use. It is probably not recognized by the majority of urologists and nephrologists that gamma scintillation cameras are now available in most major hospitals around the country, although equipment for quantitation is not necessarily present. It is equally obvious that utilization of this equipment by both urologists and nephrologists lags far behind its utilization by other medical specialists. This reflects primarily the lack of appreciation by the treating physician of what information can be obtained. There is no question that most nuclear medicine departments can provide the information described in this issue of the Seminars, but if the referring physician does not know what to ask for, such studies will not be done. An article by O'Neill and Maxfield was reviewed recently, and the abstractor's comments were as follows: "As a practicing urologist, I doubt that the renogram would ever replace the IVP as our primary urologic diagnostic tool. However, I do feel that the authors' conclusions deserve our thoughtful attention." It is my considered opinion that this comment is a reflection of the average urologist's attitude, i.e., "I don't know what this is all about, and I would rather use what I know." Understandable as this attitude is, the only solution is that the urologist as well as the nephrologist find out what it is all about. REFERENCES 1. Taplin GV, Meredith OM, Kade H, Winter CC: The radioisotope renogram. J Lab Clin Med48:886-901, 1956
2. Schlegel JU, Bakule PT: A diagnostic approach in detecting renal and urinary tract disease. J Urol 104:2,1970
216
3. Schlegel JU, Warlick JT: Experience in urologic diagnosis using a gamma scintillation camera system. J Urol IO~: 15.1972 4. Keane JM. Schlegel JU: The use of a scintillation camera system for screening of hypertensive patients. J UroIIO~:12, 1972 5. Schlegel JU: Gamma camera screening for renal and urinary tract disease: A teaching slide series, Medcom Famous Teachings in Modern Medicine. New York, Medcom, 1972 6. Wilkiemeyer RM. Boyce WHo Malek RS: Validity of the intravenous pyelogram in
JORGEN U. SCHLEGEL
assessment of renal function. Surg Gynecol Obstet 135:~97. 1972 7. Mogensen P, Rossing N, Giese J: Glomerular nitration rate measurement and I3I(-Hippuran renography before unilateral nephrectomy. Scand J Nephrol 6:22~ ·231. 1972 s. O'Neill JA, Maxfield WS: 131( Hippuran camera renogram for detection of urologic pathology in the newborn. J Ped Surg 7:236. 1972 9. Mobley JE, Schlegel JU: Radiohippurun accumulation in the transplanted kidney as a signal of rejection. Surgery 58:815, 1965
T
H E UTILlZA nON of scintillation-camera image studies incorporating quantitation, which is the topic dealt with in this issue of the Seminars, is a tool that to us equals in importance the emergence of radiology as it is applied to the diagnosis of renal and urinary-tract disease. The modern gamma camera, with its potential to quantitate dynamic events as well as to picture morphological occurrences, can no more be compared with the renogram as it came into being in 1955 1 than can modern television transmitter and receiver be compared with Marconi's wireless communication. It is important that the urologist and the nephrologist recognize that such modern technology can yield exeedingly useful information concerning static and dynamic events that is not obtainable by other means. It should further be recognized that renal physiology and pathophysiology can today be studied with radionuclide techniques that cause no morbidity and may be used with ease and accuracy without invasion of the urinary tract. This modern approach to renal physiology compares favorably with difficult clinical and laboratory procedures such as differential renal function studies previously used to obtain information that often was not physiological and that certainly was connected with considerable morbidity. In order for the nephrologist and urologist to properly assess the tremendous potential of nuclear medicine, it appears overdue that their training include some background in this field. At the Section of Urology at the Tulane Medical Center we have over the last 4 to 5 years performed more than 5,000 scintillation-camera studies on patients, following a standardized approach to allow not only comparison from patient to patient but also follow-up comparison of repeat studies on the same patient. The standard procedure'? requires adequate hydration, since one of the determinations made is the amount of radionuclide excreted within a 30-min period. Hippuran labeled with 1311 is routinely used as the radiopharmaceutical in the initial screening examination. The minute sequence study will reveal functional discrepancies between the two kidneys. A visual image of the two kidneys is obtained where abnormalities such as tumor or hydronephrosis may be detected. An accurate evaluation of the amount of residual urine is subsequently performed by obtaining counts over the bladder before and after urination 30 min after injection of the radioiodinated Hippuran. Utilizing this screening examination combined with urinalysis and a brief history, it is possible to determine the presence or absence of renal or urinary-tract disease above the bladder neck in 30 min. It is true that a stone or small tumor causing neither hematuria nor any degree of obstruction or renal damage can be missed. However, if there is no syrnptornatol-
From the Section of Urology, Tulane University School ofMedicine, Nell' Orleans, La. Jorgen U. Schlegel, M.D., Ph.D.: Professor and Chairman. Section 0/ Urology, Tulane University School ofMedicine, New Orleans, La. © 1974 by Grune & Stratton, Inc. Seminars in Nuclear Medicine, Vol. 4, No.2 (April), 1974
213
214
JORGEN U. SCHLEGEL
ogy associated with this condition, it is even more likely to be missed by any other diagnostic procedure as well. The amount of information that can be obtained in this fashion with a noninvasive procedure over a very short period of time is of tremendous importance to the physician and the patient alike. The number of intravenous urograms done without specific indication appears to be disproportionate to the yield of pathological findings and the morbidity involved. Such intravenous urograms are frequently not diagnostic, due to the presence of overlying gas, inadequate visualization, etc., which further makes their routine use for screening purposes a highly questionable procedure. However, this writer would in no way attempt to compare a welldone intravenous urogram with a scintillation-camera study, nor suggest that the scintillation-camera study can in any way provide the morphological details obtainable with a high-quality urogram. In fact, if the screening scintillation-camera study is abnormal and/or if hematuria is present, an intravenous urogram is considered the next logical step. Certainly there are institutions in which this order oftests might be reversed. It should be mentioned that we have never seen any allergic reaction to the administration of radioiodinated Hippuran, and scintillation-camera studies are routinely used in patients who have had even severe anaphylactic reactions to contrast media. It is thus indisputable that the radionuclide study is essential in patients who need functional evaluation of the upper urinary tract and who have had a previous reaction to contrast media. It is well recognized that an assessment of individual renal function cannot adequately be obtained by judging from the appearance of the contrast media on the urogram.v? To the urological surgeon who is faced with a situation of unilateral pathology requiring exploration of the kidney or ureter, accurate knowledge of individual kidney function may be a determining factor in the final decision in the operating room; here the quantitation that is obtainable by scintillation-camera studies in a simple way provides him with accurate and important information. In children, and particularly in newborns, an intravenous urogram is often unreliable, and we have found, along with others, that a scintillation-camera study of such patients not only involves less radiation than a pyelogram but also is much more reliable." Our pediatric experience is quite extensive, and we have routinely used radioiodinated-Hippuran camera studies not only in the initial evaluation of patients with reflux but also in follow-up examinations over a period of several years. In hypertensive patients" we use the radioiodinated-Hippuran studies as a primary procedure, and then proceed with other studies only when there is positive indication of possible renovascular hypertension. Not only do we find this a simple, noninvasive evaluation that can' accurately pinpoint a "guilty" kidney, but also a guilty portion of a kidney (segmental renal ischemia). The utilization of radioiodinated Hippuran in evaluation of transplanted kidneys, especially to evaluate rejection, goes back in our experience almost 10 years," and the scintillation camera has routinely been used for the last 4 to 5 years here, as it is in most other transplant centers. Although our experience with acute trauma is rather limited, this would appear to be an obvious area for application of the scintillation camera. It is, how-
VALUE OF RADIONUCLIDE STUDIES
215
ever, possible that 99mTc DTPA or other radiopharmaceuticals would be more useful in such cases. The morphological details obtained with radioiodinated Hippuran are not as good as those obtained using the much higher photon flux of a 99IDTc-Iabeled compound. For evaluation of parenchymal tumors, a good assessment of perfusion of a cold spot shown on a radioiodinated-Hippuran scintiphoto using 99mTc DTPA or pertechnetate can be made. It is not the purpose of this overview to go into details, which will be discussed subsequently in much greater depth, but rather to point out the tremendous impact that nuclear medicine has made on the practice of urology and nephrology. There are few patients we see who do not have radioiodinatedHippuran scintiphotography as a preliminary procedure, and it appears obvious that the cost factor can be reduced as the need for and volume of such studies increase. We have estimated that it is possible to conduct approximately 3,000 such studies per year using one camera. If five cameras were used, possibly in different locations, and tied into a computer analyzer, the cost per patient for such a study could be in the neighborhood of $25.00. For this cost, I feel that one would obtain an accurate estimate of total as well as individual renal function and an accurate estimate of residual urine, if present, as well as an estimate of the excretory function and gross morphology of the kidneys. In a large number of patients, such a study might eliminate the need for an intravenous urogram, as well as determination of residual urine by catheterization. Apart from the financial savings, the innocuousness of the procedure and the accuracy and reproducibility of the results should make it obvious that this is indeed an indispensable tool that is already here and available for use. It is probably not recognized by the majority of urologists and nephrologists that gamma scintillation cameras are now available in most major hospitals around the country, although equipment for quantitation is not necessarily present. It is equally obvious that utilization of this equipment by both urologists and nephrologists lags far behind its utilization by other medical specialists. This reflects primarily the lack of appreciation by the treating physician of what information can be obtained. There is no question that most nuclear medicine departments can provide the information described in this issue of the Seminars, but if the referring physician does not know what to ask for, such studies will not be done. An article by O'Neill and Maxfield was reviewed recently, and the abstractor's comments were as follows: "As a practicing urologist, I doubt that the renogram would ever replace the IVP as our primary urologic diagnostic tool. However, I do feel that the authors' conclusions deserve our thoughtful attention." It is my considered opinion that this comment is a reflection of the average urologist's attitude, i.e., "I don't know what this is all about, and I would rather use what I know." Understandable as this attitude is, the only solution is that the urologist as well as the nephrologist find out what it is all about. REFERENCES 1. Taplin GV, Meredith OM, Kade H, Winter CC: The radioisotope renogram. J Lab Clin Med48:886-901, 1956
2. Schlegel JU, Bakule PT: A diagnostic approach in detecting renal and urinary tract disease. J Urol 104:2,1970
216
3. Schlegel JU, Warlick JT: Experience in urologic diagnosis using a gamma scintillation camera system. J Urol IO~: 15.1972 4. Keane JM. Schlegel JU: The use of a scintillation camera system for screening of hypertensive patients. J UroIIO~:12, 1972 5. Schlegel JU: Gamma camera screening for renal and urinary tract disease: A teaching slide series, Medcom Famous Teachings in Modern Medicine. New York, Medcom, 1972 6. Wilkiemeyer RM. Boyce WHo Malek RS: Validity of the intravenous pyelogram in
JORGEN U. SCHLEGEL
assessment of renal function. Surg Gynecol Obstet 135:~97. 1972 7. Mogensen P, Rossing N, Giese J: Glomerular nitration rate measurement and I3I(-Hippuran renography before unilateral nephrectomy. Scand J Nephrol 6:22~ ·231. 1972 s. O'Neill JA, Maxfield WS: 131( Hippuran camera renogram for detection of urologic pathology in the newborn. J Ped Surg 7:236. 1972 9. Mobley JE, Schlegel JU: Radiohippurun accumulation in the transplanted kidney as a signal of rejection. Surgery 58:815, 1965