Roentgenology-pathology correlative study of neovascularity

The Sonographic Evaluation of Lymph Nodes

Ultrasound can be used to detect and evaluate both normal and abnormal lymph nodes, as well as aid in biopsy sampling procedures, an important part of staging procedures in cancer patients. Several parameters can be evaluated using ultrasound; lymph node size, margins, echogenicity, echopattern (echotexture), acoustic transmission, presence and distribution of vascular flow, and vascular flow indices. The most diagnostically helpful include the short/long axis ratio of the lymph node, the pattern of distribution of the blood vessels within the lymph node, and to some extent the resistive and pulsatility indices. This review discusses the use of ultrasound for detecting, evaluating, and sampling peripheral, abdominal and thoracic lymph nodes in small animals.

Small renal masses: the value of contrast-enhanced colour Doppler imaging

OBJECTIVE

To assess the value of a microbubble-based ultrasonographic contrast agent for enhancing blood vessels in colour Doppler imaging (CDI) of small renal masses.

PATIENTS AND METHODS

Fifty-one patients with small renal masses (< 3 cm in diameter) had prospective CDI before and after intravenous administration of the contrast agent Levovist (Schering, Berlin, Germany). The degree of tumour vascularity was subjectively graded from 0 to IV (indicating an increasing vessel count). Furthermore, peak systolic velocity (PSV), resistive index, and pulsatility index were measured. The CDI findings were then compared with those obtained at histopathological examination.

RESULTS

Intra- and/or peritumoral vessels were detected in 26 lesions (51%) by unenhanced CDI and in 48 by enhanced CDI (94%; P = 0.006, McNemar test). Higher grades of tumour vascularity (grade III and IV) were more common in malignant renal masses (P < 0.01). There were PSVs of >80 cm/s only in malignant lesions. Based on receiver operating characteristic analysis, enhanced CDI (area under the curve 0.789) was more accurate than unenhanced CDI (0.576) for differentiating benign from malignant renal masses (P < 0.004).

CONCLUSION

Enhanced CDI is better than unenhanced CDI for detecting tumour vascularity, and for discriminating between benign and malignant small renal masses.

A review of the sonographic assessment of tumor metastases in liver and superficial lymph nodes

Diagnostic imaging techniques are an important part of the diagnostic workup and staging of cancer patients. Ultrasound is of particular interest in this respect. In so far as tumor metastases are concerned, ultrasonography of regional lymph nodes and of the liver can provide valuable information. In humans many criteria, some of them objective, have been evaluated as indicators of malignancy. The most diagnostically helpful of these include the short/long axis ratio of the lymph node, the pattern of distribution of the blood vessels within the lymph node, and to some extent the calculated values for resistive and pulsatility indices. Putative objective criteria to improve the specificity of ultrasound for metastases detection in the liver have also been evaluated. These include perfusion indices, primarily using analysis of Doppler frequencies (Doppler perfusion index) and hepatic venography using an ultrasound contrast agent. Contrast-enhanced ultrasonography is a new and promising area to help the initial diagnosis and characterization of malignancy, particularly for focal lesions in the liver. This review discusses the use of ultrasound for detection of metastases and presents material from four veterinary cases.

Differentiation of malignant and benign musculoskeletal tumors: combined color and power Doppler US and spectral wave analysis

PURPOSE

To assess the use of combined color Doppler ultrasonography (US), power Doppler US, and spectral wave analysis (SWA) in differentiating malignant and benign musculoskeletal tumors.

MATERIALS AND METHODS

Seventy-nine musculoskeletal tumors (34 malignant, 45 benign) were examined with color and power Doppler US and SWA. Two radiologists independently assessed US images and SWA findings. Echotexture and vessel characteristics such as stenoses, occlusions, loops, shunts, trifurcations, vascular pattern, and resistive index were evaluated. All tumors were subject to US-guided or open biopsy for histologic correlation.

RESULTS

Combined color and power Doppler US and SWA revealed four major (stenosis, occlusion, trifurcation, vascular pattern) and three minor (shunt, self loop, resistive index) vessel characteristics, which proved helpful in differentiating benign from malignant lesions. Echotexture showed moderate sensitivity (82% [28 of 34 tumors]) and low specificity (38% [17 of 45 tumors]). When comparing several combinations of vessel characteristics, a combination of any two major characteristics demonstrated the best results (sensitivity, 94% [33 of 39 tumors]; specificity, 93% [three of 45 tumors]). Combining more than two characteristics resulted in lower sensitivity.

CONCLUSION

Combined color and power Doppler US and SWA may enable assessment of vascular architecture and altered flow of musculoskeletal tumors. Vascular architecture analysis enables differentiation of benign and malignant lesions and evaluation of musculoskeletal tumors.

Distribution of intranodal vessels in differentiating benign from metastatic neck nodes

AIM

Recent studies report high accuracy of power Doppler sonography in the differentiation of benign from malignant cervical lymphadenopathy. This study was undertaken to identify which of the parameters used in Doppler sonography of cervical lymph nodes is accurate and readily applicable in routine clinical practice.

MATERIALS AND METHODS

We reviewed the power Doppler ultrasound examinations of 50 patients with cytologically proven metastatic nodes from nasopharyngeal carcinoma and 50 patients with proven reactive lymphadenopathy. All the examinations had been performed by an experienced sonologist, and intranodal vascular distribution and resistance were evaluated during real-time ultrasound. Twenty metastatic nodes and 40 reactive nodes were less than 10 mm in maximum transverse diameter. The vascular patterns of lymph nodes were classified into three categories: (1) hilar; (2) capsular; (3) hilar and capsular. The resistive index (RI) and pulsatility index (PI) were measured by spectral Doppler.

RESULTS

Although metastatic nodes (RI, 0.81 +/- 0.11; PI, 1.89 +/- 0.89) tended to have higher intranodal vascular resistance than reactive nodes (RI, 0.65 +/- 0.08; PI, 1.07 +/- 0.26), there was considerable overlap of the resistance parameters between benign and malignant nodes. Most of the metastatic nodes showed the presence of capsular vascularity (capsular, 16%; capsular and hilar, 78%), whereas the majority of the reactive nodes showed hilar vascularity (98%), and the difference was significant.

CONCLUSION

The distribution of intranodal vascularity appears to be more useful than RI or PI in differentiating benign from malignant cervical lymphadenopathy. It is also easier to evaluate the distribution and the results are therefore readily applicable in routine clinical practice.

Differentiation of benign and malignant cervical lymph nodes: value of B-mode and color Doppler sonography

OBJECTIVE

To evaluate the efficacy of color Doppler sonography in detecting possible differences in blood flow patterns and B-mode sonographic characteristics between malignant and benign cervical lymph nodes.

PATIENTS AND METHODS

During a period of 10 months, the palpable cervical lymph nodes of 39 patients were prospectively evaluated with B-mode and color Doppler sonography. The echogenity, contour, ratio of longitudinal diameter to the transverse diameter and the presence of a hilus were evaluated by B-mode sonography. Capsullary and intranodal arterial flow rates were measured and maximal systolic, end-diastolic, mid-systolic flow velocities with pulsatility, resistivity and acceleration indices were obtained. Final diagnosis was established by excisional biopsy (n:34) and clinical follow-up (n:5).

RESULTS

The lymph nodes in 20 cases were malignant and in 19 cases were benign. The B-mode contour characteristics and presence of a hilus in malignant and benign lymph nodes were statistically significant (P < 0.05), but there were no significant differences between the ratio of longitudinal diameter to the transverse diameter (P > 0.05), echogenity (P > 0.05) and the diameters of lymph nodes (P > 0.05). Flow patterns were obtained in 14 malignant (70%) and 10 benign (52.6%) cases. The maximal systolic, end diastolic, mid-systolic flow velocities and pulsatility, resistivity, acceleration indices did not differ statistically (P > 0.05).

CONCLUSION

In the differentiations of benign and malignant cervical lymph nodes, the B-mode and color Doppler sonography are limited methods and can not replace biopsy.

Color Doppler ultrasound pulsatile flow signals of thoracic lesions: comparison of lung cancers and benign lesions

Color Doppler ultrasound (US) was performed in 153 patients (including 102 with lung cancer and 51 with benign lesions) to assess pulsatile flow signals in thoracic lesions. The values of resistive index (RI) and pulsatility index (PI) of color Doppler US pulsatile flow signals in lung cancers and benign lesions were measured, analyzed, and compared. In the enrolled 153 patients with thoracic lesions, 61 lung cancers and 34 benign lesions had detectable color Doppler US pulsatile flow signals, and lung cancers had lower RI and PI values than benign lesions (RI: 0.70+/-0.03 vs. 0.79+/-0.04, p < 0.05; PI: 1.61+/-0.15 vs. 2.44+/-0.25, p < 0.005). However, overlapping RI and PI values in lung cancers and benign lesions somewhat limited color Doppler US pulsatile flow signals to differentiate lung cancers from benign lesions. Further analysis of RI and PI values in subgroups of lung cancers [squamous cell carcinoma (SCC, n = 34), adenocarcinoma (AC, n = 18), and small-cell lung cancer (SCLC, n = 6)] and benign lesions [cavitary benign lesions (CBL, n = 8), and noncavitary benign lesions (NCBL, n = 26)] revealed that all different cell types of lung cancers (SCC, AC, and SCLC), indeed, had lower RI and PI values than NCBL (for RI, all p < 0.01; for PI, all p< or =0.001). Moreover, the mean RI and PI values showed a significant incremental decrease from NCBL (mean RI, PI = 0.88, 2.94) toward SCC and AC (for SCC, mean RI, PI = 0.71, 1.68; for AC, mean RI, PI = 0.68, 1.67) and, finally, to SCLC (mean RI, PI = 0.62, 1.05). In contrast, CBL had relatively lower RI and PI values than AC and SCLC (for CBL, mean RI, PI = 0.53, 0.80; both p > 0.05 for RI and PI), and even a significant difference from SCC (p < 0.05 for RI and PI). We conclude that color Doppler US pulsatile flow signal is somewhat limited to differentiate lung cancers from benign lesions, but provides a noninvasive in vivo model to assess the neovascularity intensity of lung cancers.

Intratumoral vascularity of experimentally induced VX2 carcinoma: comparison of color Doppler sonography, power Doppler sonography, and microangiography

RATIONALE AND OBJECTIVES

Tumor vascularity is useful for characterizing tumors and determining tumor management. The recent development of power Doppler sonography has enhanced the sensitivity of color Doppler imaging in the detection of blood flow because of low power noise and less angle dependence. The purpose of this study was to compare the capability of color and power Doppler sonography with that of microangiography for showing tumor vascularity of VX2 carcinoma.

METHODS

Color and power Doppler sonography was performed on VX2 carcinomas in the rabbit thighs, and their findings were correlated with those of microangiography. For qualitative analysis, tumor vascularity was categorized into four items including distribution of tumor vessels, crowdedness of vessels, small vessels, (> or = 0.1 mm), and micro-vessels (< 0.1 mm). Tumor blood flow signals of color Doppler sonography and power Doppler sonography were graded as 3, 2, 1, and 0 and were compared with tumor vascularity on microangiography. For quantitative analysis, percentages of tumor vascular area per tumor area on each study were compared.

RESULTS

The mean scores of tumor vascularity on power Doppler sonography were 2.87, 2.73, 2.93, and 2.73 in tumor vascular distribution, crowdedness of vessels, small vessels, and micro-vessels, respectively. Those on color Doppler sonography were 2.4, 2.2, 2.8, and 1.67, respectively. Power Doppler sonography was statistically superior to color Doppler sonography in displaying tumor vascular distribution (P < 0.05) and micro-vessels (P < 0.01). The means and medians of percentages of tumor vascular area per tumor area were 22.7% and 23.5% on microangiography, 17.9% and 21.4% on color Doppler sonography, and 36.4% and 34.7 % on power Doppler sonography, respectively. Percentages of tumor vascular area per tumor area on both color Doppler sonography (r = 0.70) and power Doppler sonography (r = 0.84) were well correlated with those on microangiography.

CONCLUSIONS

Power Doppler sonography can demonstrate the tumor vascularity on microangiography relatively well, however, it tends to overestimate the blood flow signals. Color Doppler sonography may have some limitations in imaging tumor vascular distribution and micro-vessels and tends to underestimate tumor vascularity, but can display the blood flow direction. Therefore, power Doppler and color Doppler sonography could complement each other in demonstrating the tumor vascularity.

A combined Doppler and morphopathological study of ovarian tumors

OBJECTIVE

To evaluate intratumoral blood flow in 46 patients with ovarian masses.

METHODS

Transvaginal color Doppler was carried out in each patient prior to the laparoscopy or laparotomy. Tumors were analyzed according to the size, morphology, presence of the neovascularization, configuration and distribution of the tumoral blood vessels and pattern of the intratumoral blood flow. Vascular patterns of surgically removed tumors were studied microscopically. Three types of vasculature were analyzed: neovascular capillaries without media, sinusoidal thin walled spaces and normal vessels' morphology. The RI (resistance index) values were analyzed in relation to gross appearance, histological type of the tumor, existence of inflammation/necrosis area and vascularization pattern of the tumor.

RESULTS

Neovascularization was found in all the malignant tumors with low RI (less than 0.42) and solid or solid cystic gross morphology. Neovascular signals were obtained in only one patient with ovarian endometrioma. Sinusoidal spaces were identified in all the malignant ovarian tumors, but also in most of the benign lesions. Normal vessel morphology was identified in 60% of malignant ovarian tumors and in all the patients with benign ovarian lesions.

CONCLUSION

There is a significant correlation between Doppler and histopathological studies in terms of vascularization pattern analysis (detection of neovascular capillaries, sinusoidal spaces and normal vessels morphology). In most of the malignant ovarian tumors there were few areas of vascularization which can be analyzed non-invasively by transvaginal color and pulsed Doppler ultrasound.

Color flow mapping

Color flow mapping systems have become widely used in the short time since their development. These systems overlay a pseudo-color velocity map upon the gray-scale two-dimensional image. Between 4 and 16 pulses are directed to each line-of-sight, and this requirement reduces the frame rate in comparison with the gray-scale image. Other limitations of color flow mapping include its ability to estimate only the velocity toward or away from the transducer and an increase in the variance in comparison with spectral Doppler. Potential artifacts include aliased velocities and the detection of flow in hypoechoic or hyperechoic nonvascular structures. Clinical applications include cardiology, studies of the abdominal and peripheral vasculature, evaluation of organ perfusion and the differentiation of tumors. Most current systems use narrowband estimators that examine a fixed sample volume and detect a change in phase between two pulses. Wideband estimators that can track red blood cells in two or three dimensions are under evaluation. Narrowband estimators, including the autocorrelator, the short Fourier transform and second order autoregressive filters, are compared with wideband estimators including cross-correlation, sum-absolute-difference and the wideband maximum likelihood estimator. Because the intensity of blood echoes is far smaller than echoes from surrounding tissue, high pass filters have been developed that can reject the larger signal from tissue using the return from a small number of pulses. Other areas of research include strategies for flow estimation with contrast agents, three-dimensional color flow mapping and power Doppler flow mapping.

Is sonographic flow imaging useful in the differential diagnosis of adrenal masses?

This prospective study was carried out to assess the ability of colour Doppler ultrasound (CDUS) and power flow imaging to differentiate between benign and malignant adrenal masses. We examined 56 adrenal masses, discovered at CT, in 47 patients who had undergone CT for known extraadrenal malignancy or unrelated benign conditions. The nature of the masses was confirmed by histopathology or assessed for likelihood of malignancy by CT appearance, MRI appearance, recent development or increase in size. In none of the adrenal masses was blood flow detected by colour Doppler or power imaging, despite optimizing scanning parameters for the detection of slow flow. We conclude that colour Doppler ultrasound and power imaging do not help in differentiating benign from malignant adrenal masses.

Is early detection of ovarian cancer possible?

Advances in medical technology have led to potentially useful techniques for the early detection of epithelial ovarian cancer. Early detection of ovarian cancer is crucial for survival as women found to have Stage I or II disease have a 5-year survival of 90% and 70%, respectively, whereas those with advanced disease (Stage III and IV) have a survival of approximately 20%. The circulating tumour marker CA-125 has been extremely useful in following women known to have epithelial ovarian cancers. It has been employed in differentiating benign tumours from malignancies, and is now being tested in a variety of programmes for its role in the early detection of ovarian cancer. The application of endovaginal ultrasound and colour Doppler flow techniques to early detection of ovarian cancer have resulted in several large series identifying ovarian cancer in 1:1000 to 1:2000 postmenopausal women screened. However, a high false positivity rate persists using CA-125 and ultrasound techniques alone or in sequence. Developments in molecular genetics may be extremely useful in evaluating women with inherited susceptibilities for this disease, but this probably represents only about 3% of the population of the women who develop epithelial ovarian cancer. The cost-benefit analysis of isolated screening for epithelial ovarian cancer using CA-125 and ultrasound techniques, even in women at high risk for the disease, would suggest that such screening is not cost-effective at this time.

Hypertensive intra-arterial chemotherapy for endometrial carcinoma assessed by transvaginal Doppler ultrasound and magnetic resonance imaging

We examined the effectiveness of hypertensive intra-arterial chemotherapy for endometrial carcinoma using transvaginal Doppler ultrasound and magnetic resonance imaging. Angiotensin II, 100 mg cisplatin, and 40 mg doxorubicin were prescribed for 8 patients with endometrial carcinoma (3 stage Ia; 3 stage Ib; 2 stage II). The resistance index (RI) was obtained for intratumoral blood flow velocity waveforms by transvaginal Doppler ultrasound and changes in RI (delta RI: differences before and after chemotherapy) were calculated. The tumor volume (TV) was also evaluated, based on the T2-weighted image of magnetic resonance imaging (MRI). The decrease in tumor size [DR-T: (TV before chemotherapy--TV after chemotherapy)/TV before chemotherapy x 100] was determined. RI measurements did not correlate with TV, either before or after chemotherapy. The delta RI varied from 0.007 to 0.615 (mean: 0.207) and DR-T varied from 20.1% to 65.0% (mean: 45.5%). The correlation between delta RI and DR-T [DR-T = 23.5 + 167.2 (delta RI)-165.6 (delta RI)2; R2 = 0.772, p < 0.05] was significant. Therefore, we confirmed the effectiveness of hypertensive intra-arterial chemotherapy for endometrial carcinoma using both transvaginal Doppler ultrasound and MRI.

Effects of external radiotherapy on uterine blood flow in patients with advanced cervical carcinoma assessed by color Doppler ultrasonography

BACKGROUND

This study was designed to evaluate radiation-induced changes in tumor blood flow by color Doppler ultrasonography.

METHODS

Color Doppler examination was performed on 14 patients with advanced cervical carcinoma treated with external radiotherapy. The total dose of radiation varied from 30 to 65 Gy and was given as 1.9 Gy daily fractions, 5 days/week. Tumor vascularity and blood flow impedance were measured by one pretreatment and five follow-up examinations.

RESULTS

At the baseline examination, 11 of 14 patients had very low tumor blood flow impedance (< 0.70). Radiotherapy caused a significant decrease in tumor vascularity (P = 0.0001) and in presence of very low blood flow impedance. The decrease of tumor vascularity during the treatment was associated with better outcome, whereas persistence of excessive vascularity or of vessels with low blood flow impedance at the end of radiation was associated with modest therapeutic response. Eight of 10 patients with increased tumor vascularity at the end of radiation needed further treatment or died of disease. Only one of four patients with normal vasculature at the end of radiotherapy needed further treatment and all four were clinically disease free during the follow-up (mean, 13 months; range, 6-26 months).

CONCLUSIONS

These results suggest that color Doppler ultrasonography may be useful in early assessment of therapeutic response during radiotherapy and in for planning individualized treatment schedules.

Image-directed color Doppler ultrasonography in the evaluation of superficial solid tumors

Image-directed color Doppler ultrasonography (ICDUS) studies of 86 patients with superficial solid masses yielded significantly lower resistive index (RI) values in acute inflammatory lesions, but no significant difference between the maximum systolic flow velocities (S) of the patient groups with malignant, benign, and acute inflammatory lesions. When analyzed separately, the malignant soft-tissue tumor subgroup was shown to have significantly higher mean RI compared to that of the malignant node subgroup. We conclude that RI may be useful in the differentiation of acute inflammatory masses from other pathological entities. Malignant soft-tissue tumors, especially sarcomas, may have different Doppler features from those of carcinomatous tumors.

Ovarian tumors of low malignant potential: transvaginal Doppler ultrasound features

Twenty-nine patients with ovarian tumors were studied with transvaginal Doppler ultrasound before surgery. After surgery, pathological examination revealed that 26 tumors were benign and 3 were of low malignant potential (LMP). B-mode sonography, computed tomography, and magnetic resonance imaging showed no positive findings for malignancy in these 3 cases of LMP. Serum levels of the CA-125, tissue polypeptide antigen, and carcinoembryonic antigen were also within the normal range. Blood flow velocity waveforms were evaluated by the calculation of the resistance index (RI). There was a significant difference between the RI value (0.818 +/- 0.223) in benign tumors and that (0.418 +/- 0.072) in LMP (P less than 0.01). When the 0.56 (mean of LMP tumor RI value + 2SD) was considered as the cutoff value of RI, the sensitivity was 100% and the specificity was 88.5%. Transvaginal Doppler ultrasound provides a useful diagnostic information for the differentiation of benign and LMP ovarian tumors before surgery.

Transvaginal color Doppler imaging for hemodynamic assessment of reproductive tract tumors

Transvaginal color Doppler flow imaging was carried out on 68 Japanese women (normal, 10; uterine myoma, 21; cervical carcinoma, 7; endometrial carcinoma, 10; benign ovarian tumor, 12; ovarian carcinoma, 8). Blood flow velocity waveforms were evaluated by calculation of the resistance index (RI). In 6 patients with cervical carcinoma neovascularization was evident within the cervix. In all patients with endometrial carcinoma such signs were present adjacent to and/or within the endometrium. These findings were absent in normal women and in those with myomata. There was a significant difference between the RI (0.510 +/- 0.097) in patients with cervical carcinoma and in normal women (0.881 +/- 0.048) in the ascending branch. In endometrial carcinoma the RI (0.535 +/- 0.158) was significantly lower in the arcuate artery compared to the normal uterus (0.768 +/- 0.075) and patients with uterine myoma (0.679 +/- 0.131), respectively. There was no area of neovascularization in the normal ovaries. Neovascularization was confirmed in four patients with a benign ovarian tumor and in all patients with an ovarian carcinoma. A significantly lower RI was obtained in cases of ovarian carcinoma (0.503 +/- 0.122) than in patients with benign ovarian tumors (0.888 +/- 0.216). Transvaginal color Doppler imaging and pulsed Doppler analysis may be useful diagnostic tools to differentiate benign and malignant tumors.

[Microangiographic examinations of different human tumors after transplantation to thymus aplastic nude mice]

Ten different human tumors (two soft tissue sarcomas, seven adenocarcinomas of the colon and stomach and, one squamous cell carcinoma of the lung) were implanted s.c. in thymus-aplastic mice and retransplanted over several generations. In 40 animals, the tumors were studied by microangiography and microscopy and classified according to angiographic tumor criteria. Tumor transplants always revealed similar angiographic patterns. The microscopic results presented a good correlation with the roentgenologic findings. The microstructure of the tumor vessels and lacunes are analyzed and discussed. The nude mice model is well suitable for the research of human tumors.

Dynamic CT of the urogenital tract

The theoretical basis for and the technique of intravenous contrast enhancement by bolus injection for dynamic CT examination of the kidney are described. The clinical applications of this method include the study of normal vascular anatomy of the kidney, congenital kidney abnormalities and form variants, space-occupying lesions, and kidney trauma. In tumoral lesions of the kidney, dynamic CT aids in detecting the lesion as well as in the tumor staging and evaluating operability. CT time density curves can be used to study disturbances in renal perfusion, but the clinical value of this method needs further confirmation.

Contribution of angiography to the diagnosis, staging and assessment of radiation and chemotherapy of solid abdominal malignancies in children

Sequential angiographic studies were done in six children to stage and assess the results of radiation and/or chemotherapy of solid abdominal malignancies: one bilateral Wilms' tumor, two neuroblastomas, two hepatoblastomas and one hepatocarcinoma. Angiography was of value in demonstrating the tumor, its location, extent and vascular characteristics, as well as its regression and recurrence. Wilms' tumor and neuroblastoma responded and well to radiation and chemotherapy with substantial decrease in tumor size and regression or disappearance of tumor neovasculature. Resceted tumors revealed this to be due to tumor necrosis, hemorrhage and/or cystic degeneration. Hepatoblastoma and hepatocarcinoma did not respond as well to chemotherapy, with only mild decrease in size and neovasculature of the tumor.

Combined radiographic and ultrasonographic approach in diagnosis of renal inflammatory lesions

Seven cases of inflammatory lesions of the kidneys are reported. In 6 of the 7 patients, there were clinical and/or laboratory signs of urinary tract infection. The lesions occurred without any preference to age, sex, or location as to the right or left kidney. The diagnostic approach was individualized, and a correct preoperative diagnosis was made in 6 of the 7 cases. This high diagnostic accuracy was reached by using the following diagnostic principles. The lesions are detected and localized by urography and nephrotomography. Ultrasonography is used to decide whether the mass is solid or cystic. A percutaneous needle puncture is done in cases in which ultrasonography indicates a cystic lesion. The diagnosis of renal cyst is confirmed or excluded by cytology and analysis of the cyst fluid. Renal angiography is performed when the mass displays a solid or mixed ultrasonographic pattern and also in cases of hematuria and in cases in which the clinical symptomatology suggests malignancy.