Vol. 115, June

THE JOURNAL OF UROLOGY

Copyright© 1976 by The Williams & Wilkins Co.

Printed in U.S.A.

THE ROLE OF ULTRASONICS IN THE EVALUATION OF RENAL MASSES R. J. BABAIAN, F. A. FRIED,* A. T. COLE

AND

E. V. STAAB

From the Departments of Surgery (Urology) and Radiology, University of North Carolina School of Medicine, Chapel Hill, North Carolina

ABSTRACT

Analysis of our experience with echography in the evaluation of renal masses reveals an error rate of 31 per cent. Presently, this technique may be useful in directing the evaluation of a renal mass to either arteriography, if a tumor is suspected, or needle aspiration and renal cystogram, if a cyst is suspected. However, echography should not replace more definitive studies. The use of echography in the evaluation of renal masses has been established. 1-4 Its primary attribute has been its ability to differentiate non-invasively between solid and cystic masses. The diagnostic accuracy reported varies from 80 to 95 per cent. 3 • 5 - 7 Our experience with renal echography has been somewhat less encouraging and forms the basis for this report. MATERIALS AND METHODS

At our institution adult patients with renal masses are evaluated by a diagnostic protocol, which has included the use of renal echograms. Between July 1971 and October 1974, 55 patients with renal masses suspected or diagnosed on an excretory urogram (IVP) were studied with echography. Of these patients 35 had confirmation of the diagnosis by one or more of the following procedures: cyst puncture in conjunction with renal cystography, selective renal arteriography and/or an operation (see table). The 35 masses included 17 cystic lesions, 12 solid lesions, 4 hydronephrotic kidneys and 2 normal kidneys. Included among the 12 solid lesions were 6 renal cell carcinomas, 3 Wilms tumors, an inflammatory mass, a transitional cell carcinoma of the renal pelvis and an infiltrating lymphoma. All studies were obtained with a Unirad sonograph I unit, which produces leading edge scans. It is noteworthy that this instrument was one of the first commercial units of its kind designed for clinical use. Criterion for the diagnosis of a renal cyst includes the finding of sharp walls with absence of echos within the mass at low amplitudes. During these years the studies were performed by 4 radiologists without special training in ultrasonic techniques. RESULTS

For this report we established the criteria of a successful study as follows: 1) the confirmation of the presence or absence of the mass and 2) if a mass was detected to distinguish between fluid filled and solid lesions. On the basis of previous reports that document the difficulty in distinguishing between cysts and large hydronephrotic kidneys, we did not require that the ultrasonic study distinguish between these 2 entities. 8 Thirty-five masses were evaluated: 24 were correctly diagnosed, 10 studies were in error and 1 was indeterminate. The 10 errors included 6 masses that were not detected (a 4 cm. multicystic kidney and 5 solitary cysts measuring ·2, 4, 4.5, 6 and 7.5 cm. in diameter) and 4 incorrect diagnoses (a renal pelvic tumor diagnosed as a hydronephrotic kidney, a Wilms tumor diagnosed as hydronephrosis, a renal cyst diagnosed as Accepted for publication October 10, 1975. . . . Read at annual meeting of Southeastern Sectrnn, American Urological Association, Atlanta, Georgia, April 13-16, 1975. * Requests for reprints: Division of Health Affairs, Department. of Surgery (Urology), North Carolina Memorial Hospital, Chapel Hill, North Carolina 27514. 646

a solid mass and a cyst adenocarcinoma diagnosed as a cyst). One indeterminate study proved to be a normal kidney. DISCUSSION

Our results revealed a surprisingly high rate of error. In an effort to determine if our error rate was in part owing to the lack of experience with this new tool the 35 studies were recently resubmitted to 2 of our most experienced radiologists for another interpretation, without knowledge of the prior interpretation. A summary of the results of the reinterpretations is as follows: 21 correct diagnoses, 12 incorrect diagnoses and 2 indeterminate studies. Two previously correctly identified solid masses were incorrectly reinterpreted as cysts, while 2 correctly diagnosed cystic lesions were now believed to be uninterpretable. The accuracy rate with reinterpretation decreased from 71 to 64 per cent. As before, 6 lesions failed to be detected but 2 of these were previously correctly diagnosed. The lesions that were not identified consisted of 4 upper pole cysts, a mid renal cyst and a lower pole hypernephroma. The accuracy rate in distinguishing between fluid filled and solid masses was 71 per cent. Several limitations of renal echography previously reported also have been encountered in our study. As previously mentioned, it is difficult to differentiate between renal cystic lesions and hydronephrosis. Lesions involving the upper pole of a kidney are far more difficult to identify because of the presence of the overlying ribs. In our study 5 of the 10 incorrectly diagnosed cases involved cysts of the upper pole of the kidney. The size of the lesion is another obviously important consideration. The power of resolution of this technique is stated to be at approximately 3 cm.• In our series a small lesion (less than 3 cm.) accounted for 1 undetected mass. Finally, others also have noted the difficulty in detecting tumors of the renal pelvis. 10 This problem was encountered in 1 case and we, too, were unable to make the correct diagnosis although the lesion was obvious on IVP. Our experience, like others, re-emphasizes the need for careful ultrasonic techniques, adequate interpretation, experienced ultrasonographers and up-to-date equipment. Ultrasonic techniques should not be used to detect the presence of mass lesions. They should nearly always be limited to the investigation of masses identified by other diagnostic studies. With this in mind, if one re-examines the aforementioned data, omitting cases in which masses were not appreciated or outlined, the accuracy becomes 86 per cent. Nevertheless, it should not be used as a definitive study but a guide for directing the evaluation in either the direction of cyst puncture and renal cystogram or a selective renal arteriogram. Analysis of our results has underscored certain correctable deficiencies, that is equipment, training and interpretation. It is planned that with correction of these deficiencies our

547

ULTRASONZ:SS AJ">JD RENAL

Procec.b,,1fes used to rnake final diagnosis No. Pts. Arteriogram Surgery Cyst puncture Surgery plus arteriogram Cyst puncture plus arteriogram

Total

7 12 2 11 3 35

6. Barnett) Eo and tviorley~ P .. :Diagnostic ultrasound in renal disease. Brit. Med. Bull., 2§: l96, 1S72. 7. Stuber, J. L., Templeton, A. W. and Bishop, K.: Ultrasonic evaluation of the kidneys. Radiology, 104: 139, 1972. 8. Sanders, R. C. and Bearman, S.: B-scan ultrasound in the diagnosis of hydronephrosis. Radiology, 108: 375, 1973. 9. Goldberg, B. B., Ostrum, B. J. and Isard, H. J.: Nephrosonography: ultrasound differentiation of renal masses. Radiology, 90: 1113, 1968. 10. Barnett, E. and Morley, P.: Ultrasound in the diagnosis of abdominal and pelvic conditions. Brit. J. Hosp. Med., 8: 531, 1972.

accuracy will improve. This study suggests the need for each institution to critically review their own experience with this

technique. REFERENCES

1. Damascel!i, R, Lattuada, A., Musumeci, R. and Severini, A.: Two-dimensional ultrasonic investigations of the urinary tract. Brit. J. Radio!., 41: 837, 1968. 2. Barnett, E. and Morley, P.: Ultrasound in the investigation of space-occupying lesions of the urinary tract. Brit. J. Radio!., 44: 733, 1971. 3. Mountford, R. A., Ross, F. G. M., Burwood, R. J. and Knapp, M. S.: The use of ultrasound in the diagnosis of renal disease. Brit. J. Radio!., 44: 860, 1971. 4. Schreck, W.R. and Holmes, J. H.: Ultrasound as a diagnostic aid for renal neoplasms and cysts. J. Urol., Hl3: 281, 1970. 5. Holm, H. H., Rasmussen, S. N. and Kristensen, J. K.: Errors and pitfalls in ultrasonic scanning of the abdomen. Brit. J. Radio!., 45: 835, 1972.

COMMENT These authors make several points that need to be emphasized. Ultrasound is an inefficient method to detect renal mass lesions that are more easily seen on IVP or retrograde pyelography. The value of ultrasound is its ability to characterize mass lesions as cystic or solid and, thus, influence management. Patients with cystic masses diagnosed by ultrasound arteriography should undergo cyst puncture or an operation unless the patient is elderly or debilitated, for neither arteriography nor echography will provide a diagnosis of small carcinomas in a cyst wall or is 100 per cent accurate in the differentiation between cystic and solid masses. Hydronephrosis usually has a characteristic ultrasonic appearance but requires further investigation either by antegrade or retrograde pyelography to demonstrate the level and nature of the obstruction. Cysts of the left upper pole are especially difficult to diagnose by ultrasound owing to overlying ribs and lung. Urologists should not be surprised by an equivocatory ultrasonic report of a mass in this area. R.c.g

The role of ultrasonics in the evaluation of renal masses.

Vol. 115, June THE JOURNAL OF UROLOGY Copyright© 1976 by The Williams & Wilkins Co. Printed in U.S.A. THE ROLE OF ULTRASONICS IN THE EVALUATION OF...
69KB Sizes 0 Downloads 0 Views