Ultrasound as a Diagnostic Aid for Renal Neoplasms and Cysts

Vol. 111:J, Mar. Printed 'in C.8.A.

THE JOURNAL OF LROLOGY

Copyright© 1970 by The Williams & Wilkins Co.

ULTRASOUND AS A DIAGNOSTIC AID FOR RENAL ='JEOPLASJIS AND CYSTS WALTER R. SCHRECK

AND

JOSEPH H. HOLMES

From the Department of Surgery, Division of Urology ancl Departmenl of ivleclicine, Division of Renal Medicine, University of Colorado Medical Center, Denver, Colorado

Preoperative differentiation between renal cysts and neoplasms continues to be a problem for clinicians. The recent application of pulse echo D-scan ultrasonic techniques in obstetrics and gynecology suggested it might have potential usefulness in the diagnosis of certain renal lesions.1. 2 Potential advantages of the procedure include a cross-sectional presentation, a greater sensitivity to tissue density differences thus not requiring contrast material, ease of examination and equal effectiveness in patients with impaired renal function. Thus this technique could provide diagnostic information which would supplement other techniques. We decided to test the potential usefulness of diagnostic ultrasound in differentiating renal cysts from neoplasms. 'vVe herein present the results of examination of 19 patients with confirmed renal cysts and 17 patients with confirmed renal neoplasms. The results ·will be presented in relation to the usefulness of diagnostic ultrasound for the abovementioned renal lesions and the necessary improvements in the technique which must be achieved before it will have universal application. METHODS AND MATERIALS

We used 2 types of compound contact ultrasonic scanners. One was a contact scanner constructed in this laboratory3 and the other was a porta-arm scanner constructed by Physionics Engineering, Incorporated. The basic equipment Accepted for publication February 3, 1969. Read at annual meeting of South Central Section, American Urological Association. San An-· tonio, Texas, October 20-24, 1968. · Supported in part by United States Public Health Grants No. HE02115 and HDOI669. 1 Thompson, H. E., Holmes, J. H., Gottesfeld, K. R. and Taylor, E. S.: Fetal development as determined by ultrasonic pulse echo techniques. Amer. J. Obstet. Gynec., 92: 44, 1965. 2 Thompson, H. E., Holmes, J. H., Gottesfeld, K. R. and Taylor, E. S.: Ultrasound as a diagnostic aid in diseases of the pelvis. Amer. J. Obstet. Gynec., 98: 472, 1967. 3 Holmes, J. H., Wright, W. L., Meyer, E. P., Posakony, G. J. and Howry, D. H.: Ultrasonic contact scanner for diagnostic application. Amer. J . l\Ied. Electronics, 4: 147, 1965.

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units consisted of a pulser, a receiver-amplifier a scanning system with position indicators and a display system. A 2 megahertz lead zirconate transducer was pulsed with a 500 volt. current at 400 times a second. This causes vibraproducing ultrasonic tions within the waves which were then directed into the ti~sue. vVhen the wa,"es contacted tissue interfaces of different densities they were reflected back to the crystal which then acted as a receiver to c01Fert ultrasonic energy to electrical energy. This energy was then amplified and displayed on an oscilloscope as a bright dot for each reflecting interface. The transducer was moved around the organ being examined and the dots coalesced to trace the outline of the tissue interface. The compound scanning motion is necessary to precisely delineate the character of the tissue interface. In the first scanner this was accomplished by a mechanical sector scan 30 each side of the perpendicular while the transducer was being moved across the body surface. ·with the porta-arm scanner the sectoring motion was provided by the operator's hand as he moved the transducer across the body surface. Ultrasonic coupling between the skin surface and the transducer was achieved by the application of mineral oil or ultrasonic jelly. The resultant picture appeared on the oscilloscope screen in a crosssectional presentation and a polaroid camera was used to photograph the screen for a permanent record. Pictures were taken at 2 cm. intervals above the anterior-superior iliac spine usually in the posterior and lateral positions. Figure 1 shows the hand porta-arm scanner in operation for examination o± the kidney region. The patient lies on his abdomen while the trans-· ducer is moved from one side to the other over the patient's back. H takes approximately 1 minute to produce a complete picture of the renal area at any one level. The scanning arm with the position indicator is just to the right of the operator. The rack contains the pnlser, receiver, amplifier and display system. The rnethocl of examination is simple and provides no discomfort to the patient.

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Xineteen patients with renal cysts and 17 patients with renal neoplasms were chosen for examination. The diagnoses were established by operation, arteriography and nephrotomography. RESULTS

The ultrasonic pictures in patients with cysts consisted of a clear black area with a regular white echo outline and the absence of appearance of echo patterns within the clear area after an increase in receiver sensitivity. In patients with neoplasms the renal echo outline was usually irregular and the area within the abnormal echo outline contained scattered echo patterns. A clear area was found to occur in some but it usually showed echo patterns as receiver sensitivity was increased. This agrees with the findings of Goldberg and associates who studied cysts and solid tumors of the kidney using A-mode ultrason-

FIG. 1. Porta-arm scanner in operation

ography. 4 If the clear area remained after increasing the sensitivities it was difficult t• interpret but was consistent with a neoplas with a necrotic area. Thirteen of 19 patients with known cysts had ultrasound pictures consistent with a cyst. Figure 2, A is an example of a cyst showing the clear area with a regular outline. Figure 2, B, taken 3 days later, demonstrates the persistence of the clear dark area after an increase in receiver sensitivity. Figure 3, A shows the typical echo pattern of a cyst in another patient. The arteriogram is presented for comparison (fig. 3, B). In 1 patient the clear area was so large that it was considered consistent with either a huge cyst or massive hydronephrosis (fig. 4). The dense echo patterns medially suggest compression of adjacent tissue. The patient was a 10-year-old girl found at operation to have a large hydronephrosis due to a congenital ureteropelvic junction obstruction. The pictures of 6 patients were of poor quality and therefore uninterpretable. Sixteen of 17 patients with neoplasms had renal cell carcinoma proved at operation. The other patient in this series had a papillary carcinoma of the renal pelvis. Of the 16 patients with renal cell carcinoma the ultrasound pictures were consistent with a neoplasm in 12 cases. In ·. patients the pictures were consistent with either 4 Goldberg, B. B., Ostrum, B. J. and Isard. H. J.: N ephrosonography: ultrasound differentiation of renal masses. Radiology, 90: 1113, 1968 .

. FIG. 2. Patient was 75-year-old man with prostatism. IVP showed mass in left kidney. A, typical picture representative of cyst shows regular outline with central clear area. B with increase in receiver sensitivity from dial setting of 0.6 in A to 2.2 in B, central area remains clear. '

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FIG. 3. A, sonogram of cyst. B, arteriogram for comparison. Patient was 38-year-old woman referred to our hospital for evaluation of hypertension. IVP done elsewhere showed filling defect in left kidney. Arteriogram was subsequently done at our institution.

FIG. 4. Patient was 10-year-old girl with huge left flank mass. Ultrasound picture is example of massive hydronephrosis.

a cyst or neoplasm. In one of these the neoplasm had a central necrotic area when bivalved and in the other the arteriogram showed a central lucent area surrounded by vascularity consistent with neoplastic vessels (fig. 5). This picture is also a good example of the ultrasonic appearance of the normal right kidney. One factor against the lesion

being a cyst in the last patient is the irregular outline of the dark area. Of the remaining 2 patients the sonograms of one suggested a cyst and the sonograms of the other patient were of poor quality because of obesity and therefore uninterpretable. The patient with the papillary cell carcinoma had a normal ultrasound profile and when the kidney was bivalved the neoplasm was found to be confined to the renal pelvis. Figure 6, A represents the echo pattern of a renal cell carcinoma. This diagnosis was based on the irregularity of the renal outline and the scattered echo patterns within this outline. Picture 6, B shows the arteriogram for comparison. Figure 7 shows a large clear area at low sensitivities that, except for the irregularity of outline, suggests a cyst. With an increase in the receiver sensitivity there is an increase in the number of echo patterns in the previously clear area which is consistent with a neoplasm. DISCUSSION

Our study shows that ultrasound scanning can be of value in differentiating between renal neoplasms and cysts. As with many other techniques ultrasound scanning alone does not provide a specific diagnosis, but when used in conjunction with other studies it is definitely helpful. We

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FIG. 5. A, irregular outline of renal neoplasm surrounding clear dark area. B, this is seen also as clear area in arteriogram. The area was believed to represent necrotic area in neoplasm. Patient was 64-yearold woman with gross, painless hematuria. Pre-admission IVP revealed large left renal mass.

FIG. 6. A, sonogram of renal tumor with large, irregular area and echo patterns scattered throughout. Patient was 35-year-old woman who had episode of gross, painless hematuria. IVP revealed large renal mass. B, arteriogram.

have had particular difficulty in obtaining good pictures in markedly obese patients, but with further development in the technique and the instruments, we expect better pictures to result and therefore, better delineation of renal masses. Since the technique is sensitive to density differences we may expect specific echo patterns in some patients with chronic pyelonephritis,

nephrosclerosis, glomerulonephritis, renal vem thrombosis and renal calculi.• One particular advantage of this technique is that it does not create discomfort for the patient. 5 Holmes, J. H.: Ultrasonic studies of the bladder and kidney. In: Diagnostic Ultrasound. Edited by C. C. Grossman. New York: Plenum Publishing Corp., pp. 465-480, 1966.

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Frn. 7. Patient was 46-year-old man with gross, painless hematuria. Right renal cell carcinoma was found at operation. Increasing density of echo patterns was seen within large, dark, irregular, clear area. with increase in receiver sensitivity. Receiver sensitivity dial settings were L5 (A), 1.9 (B), 2.0 (C') and

2.6 (D)

In addition, it has no known hazards and can be repeated indefinitely without fear of toxicity or allergic reactions. The power level required is .04 watts per square centimeter which is approximately 1/100 of that used in physical medicine. It is the only diagnostic technique available at this time that provides a cross-sectional view of the anatomical structures which may have considerable value in relation to contemplated operation or needle insertion. We believe this technique has a definite future in the diagnostic armamentarium of the urologist and nephrologist as it has already shown itself to have for the neurologist, 6 ophthalmologist/ obstetrician1.2 and cardiologist. 8 , 9 6 Grossman, C. C.: The Use of Diagnostic Ultrasound in Brain Disorders. Springfield Illinois: Charles C Thomas, 1966. · 'K. A. Gitter, A.H. Keeney, L. K. Sarin and D. . Proceedings of the Fourth International Congress of Ultrnsonography in Ophthalmology,

SUM1/L\.RY

We herein describe the use of ultrasound in the diagnostic study of 19 patients with renal cysts and 17 patients with renal neoplasms. A characteristic echo pattern vrns found in 13 patients with renal cysts and 12 patients with renal neoplasms. The results demonstrate that ultrasound has definite diagnostic value in urology and nephrology and improvement in diagnostic results can be expected with improvement in the technique and equipment. Philadelphia, Pennsylvania, 1968. St. Louis: C. V. Mosby Co., 1969. 8 Edler, I.: Mitra.! valve function studied by the ultrasound echo method, In: Diagnostic Ultrasound. Edited by C. C. Grossman. New York: Plenum Publishing Corp., pp. 198-228, 1966. 9 Joyner, C, R.: Experience with ultrnsound in study of heart disease and the production of intra.cardiac sound. In: Diagno,stic Ultrasound. Edited bv C. C. Grossman. New York: Plenum Publishi11g Corp., pp 237-248, 1966,