Adnexal masses may be difficult to characterize on a morphologic basis alone. Since most benign lesions, as well as most neoplasms, are predominantly cystic, a method to differentiate these lesions would be clinically valuable. Un-fortunately, morphologic evaluation by gray-scale sonography alone may at times be inadequate. Sonographic characterization of the internal contents, such as low-level echoes, septation, and projections, may suggest the most likely type of tumor as well as the malignant potential of these lesions. Color Doppler sonography affords additional information concerning the growth and malignant potential of these masses.12
Recently, a study of the various gray-scale and CDS parameters indicated that the presence of a solid component is the most statistically significant predictor of a malignant ovarian mass.18 For masses that did not contain a solid component, the location of flow (central), amount of intraperitoneal fluid, and presence and thickness of septations seemed to have statistically significant discrimination power. Others have confirmed that the utility of CDS is related to the proportion of multiloculated masses with solid components that are stud-ied.19
The pelvis is the source of benign and malignant ovarian lesions and of adnexal masses, including paraovarian cysts, tubo-ovarian complexes, and uterine leiomyomata. Doppler characteristics of these lesions reflect their vascu-larity. In general, benign pelvic masses exhibit high-resistance waveform patterns (ie, high PI). Functional ovarian masses often present with patterns that demonstrate low resistance to diastolic flow (ie, low PI). With hormonal ma-nipulation, cyclical variation, or both, these lesions typically regress or revert to a high-resistance waveform pat-tern.20 Of the benign ovarian lesions, 2 in particular are great mimickers. These are endometriomas and teratomas. Morphologically, they may appear suspicious for malignancy due to their solid components. Doppler interrogation of these lesions may differ with areas of high or low diastolic flow.5,7 The pattern of low impedance (low PI) may be problematic when assessing for the possibility of malignancy because they may contain vessels with low-impedance and high-diastolic flow. The flow within these masses had been related to their biologic activity, the presence of acute hemorrhage, or both.20 The clinical presentation of patients with these masses may be useful in further distinguishing them from women at risk for ovarian malignancies.
Malignant ovarian masses often show characteristic findings on gray-scale sonography. In those cases in which the morphology is nonspecific, Doppler interrogation may add additional information. The CDS analysis obtained from malignant vessels will usually show an increase in the number of vessels, as well as central or scattered locations of these vessels. The diastolic notch is characteristically absent.6 This high-diastolic flow (low PI) reflects the neovascularity of the malignant process. It seems to be most evident in rapidly growing tumors as compared with those late-stage tumors that have become necrotic. In our experience, 3 stage I ovarian cancers were found out of the 9 diagnosed based on their CDS findings. All of the late-stage tumors, however, were diagnosable based on their morphologic features alone.7,21,22 Some have reported differences in velocity in malignancies, although our series showed a trend but not a statistically significant differ-ence.21,22
Other lesions that may contain high-diastolic flow (low PI) include inflammatory tubal or bowel masses and uterine leiomyomata. Morphologic changes that indicate that these masses arise outside of the ovary, as well as the patient's clinical history, are useful in assessing these patients. Color Doppler sonographic evaluation of tubo-ovarian complexes will differ depending on the presence of concurrent inflammation. Characteristically, in those patients actively infected, there will be low resistance to diastolic flow (low PI). This reflects the active inflammatory process with vasodilation occurring in these lesions. However, in patients with adequate medical treatment, the tubo-ovarian complex is a residuum of the previous disease. These noninfected masses often demonstrate increased diastolic resistance and high PI values.23 With uterine leiomyomata, a rim of stroma may be seen along the uterine wall, separating it from the ovary. This rim of stroma represents the peritoneal surface of the leiomyomata and is quite useful in determining the epicenter of the mass. The resistive indices in leio-myomata will differ depending on the vascularity of the mass and whether or not normal vessels are parasitized.
Figures 32-1, 32-2, 32-3, 32-4, 32-5, 32-6, 32-7, 32-8, 32-9 and 32-10 illustrate the morphologic and spectral analysis of selected pelvic masses. Table 32-1 lists the multiple parameters used and typical findings in benign and malignant masses. Table 32-2 illus-trates the expected sonographic characteristics compared to impedance patterns of selected adnexal masses.
Table 32-2TYPICAL TRANSVAGINAL COLOR DOPPLER SONOGRAPHIC FINDINGS IN BENIGN AND MALIGNANT OVARIAN MASSES ||Download (.pdf) Table 32-2 TYPICAL TRANSVAGINAL COLOR DOPPLER SONOGRAPHIC FINDINGS IN BENIGN AND MALIGNANT OVARIAN MASSES
|Type of Mass ||Vessel Distribution ||Impedance, Relative Velocity |
|Corpus Iuteum ||Peripheral ||Low, high |
|Endometrioma ||Peripheral ||Variable |
|Dermoid cyst ||Peripheral and central ||Variable |
|Ovarian torsion ||Absent ||Very high if present |
|Benign epithelial ovarian tumor ||Peripheral ||High, low |
|Malignant ovarian tumor ||Peripheral and central ||Low, high |
Multiparameter analysis of 25 benign and 25 malignant ovarian lesions. Most benign tumors had central flow, low velocity, and high impedance, whereas malignant tumors tended to have central flow, higher velocities, and lower impedance. The notch was absent in all malignancies but also absent in 10 of 25 benign lesions. (Redrawn with permission from Fleischer A, et al: Color Doppler sonography of benign and malignant ovarian masses, Radiographics Sep 12(5):879-885, 1992.)
Physiologic masses. A: Corpus luteum with low-impedance (pulsatility index = 0.7), high-velocity diastolic flow. B: Hemorrhagic corpus luteum cyst with low-impedance flow. C: Corpus luteum flow without detectable mass.
Cystic masses showing various flow. A: Simple cyst with smooth walls and high-impedance flow (pulsatility index [PI] = 2.1). B: Endometrioma with low-level internal echoes and low-impedance flow (PI = 0.5) in an intraovarian arteriole. C: Initial transvaginal color Doppler sonogram (TV-CDS) showing a cystic mass with high impedance (PI = 2.7), low-velocity (maximum systemic velocity = 9 cm/s) flow. D: Follow-up TV-CDS 6 weeks later shows regression of the cystic mass and no change in waveform. This most likely represented a physiologic cyst.
Complex, predominantly cystic masses. A: Complex mass with solid areas and high-impedance flow (pulsatility index [PI] = 2.1). This was a dermoid cyst. B: Septated cystic mass with an area of low-impedance flow (PI = 0.5) in a thick septum. A mucinous cystadenocarcinoma was found at surgery. At histology, an abnormally dilated tumoral vessel was found within the septation. C: Complex mass with irregular cystic areas with high-impedance, high-velocity flow. This was a hemorrhagic corpus luteum cyst. D, E: A complex mass with cystic areas with high-velocity (maximum systolic velocity = 18 cm/s), low-impedance (PI = 0.49) flow. This represented a tubo-ovarian abscess. Low-impedance flow was related to vasodilation observed in the initial inflammatory phase. F: Septated mass with low-impedance (PI = 0.8), low-velocity (maximum systolic velocity = 10 cm/s) flow within a papillary excrescence. This was ovarian cancer. G: Septated mass with high-impedance (PI = 1.4), low-velocity (maximum systolic velocity = 9 cm/s) flow was found to be a benign mucinous cystadenoma. H: Complex mass with irregular solid areas suspicious for cancer. No flow was seen within the solid areas, however. This was a large endometrioma that contained focal areas of clot.
Solid adnexal masses. A: A 3-cm solid adnexal mass with high-impedance flow (pulsatility index [PI] = 2.3) within a peripherally located vessel. This was found to be a dermoid cyst at surgery. B: A 4-cm heterogeneous solid mass with intermediate impedance flow (PI = 1.1). This also represented a dermoid cyst.
Ovarian carcinoma. A: Transabdominal color Doppler sonography shows low-impedance flow (pulsatility index [PI] = 0.9) within the periphery of an ovarian endometrioid carcinoma. B: Within this serous papillary cystadenocarcinoma were vessels with low-impedance flow (PI = 0.9). C: In the center of this dysgerminoma were vessels with low-impedance (PI = 0.4), high-diastolic flow. D: Low-impedance (PI = 0.8) flow within solid area of a pelvic mass. This was an ovarian car-cinoma. E, F: Complex, mostly cystic mass with irregularly thickened wall containing intermediate-impedance (PI = 1.2), low-velocity (maximum systolic velocity = 8 cm/s) flow (E) and increased venous flow (F). This was ovarian cancer.
Inflammatory masses. A: A tubo-ovarian abscess with low-impedance (pulsatility index [PI] = 0.8), high-diastolic flow. B: A tubo-ovarian complex in an asymptomatic patient with a prior history of pelvic inflammatory disease with intermediate-resistance flow (PI = 1.2). C: This walled-off appendiceal abscess demonstrated low-impedance (PI = 0.5), high-diastolic flow.
Spontaneous resolution of a hemorrhagic ovarian cyst. A: Initial transvaginal color Doppler sonogram shows 4-cm hypoechoic mass due to nonclotted blood. B: Same patient as in (A); 6 weeks later, the waveform demonstrates high impedance.
Using a combination of morphology and spectral analysis, investigators have attempted to determine the histopathology of pelvic masses. Fleischer et al21 examined 62 patients in whom 25 malignancies were pathologically proven. Twenty of the malignancies showed low PIs and an absent diastolic notch; however, 3 benign lesions also shared similar findings. This resulted in a 98% negative predictive value and a positive pre-dictive value of 83%.21 A high negative predictive value would be expected of any test in a disease that has low prevalence such as ovarian carcinoma. Kurjak et al identified 624 benign masses and 56 malignant masses, including 16 stage I lesions, in more than 14,000 women.14 Neovascularity was seen in 15 of 16 of the stage I carcinomas and in 39 of the 40 stage III or IV ovarian carcinomas. At our institution, retrospective analysis of 96 patients with pathologic correlation after TV-CDS indicated that in approximately 40% of cases, CDS provided enhanced specificity concerning the organ of origin and the cell type.1 This specificity was most evident in the detection of ovarian malignancy, ovarian torsion, and ectopic pregnan-cies. In 40% of cases, the specificities of TVS and CDS were equal; in 6% of the patients, TVS was more specific than CDS. In 2 lesions, neither exam was histologically definitive. These included a 2-mm metastatic ovarian can-cer, which was not diagnosed, and an intraligamentous leiomyomata, which was misdiagnosed as an ovarian neoplasm.1
When interpreting the sonographic findings, it is important to be aware of the patient's clinical history, including age, prior surgery, risk factors for infection, and hormonal status. Laboratory values, such as white cell count and CA-125 values, are also important in evaluating this information. Because low-impedance flow occurs in a number of clinical situations, it is only by integrating these factors that the significance of the lesion be appreci-ated. It would appear that CDS can accurately exclude the possibility of malignancy in most situations. This enables the clinician to identify those patients in whom aggressive management is indicated.
The true sensitivity of CDS awaits further evaluation and study. At present, many investigators have reported on small groups of patients in whom it was felt that the added specificity afforded by CDS substantiated its use, especially in those cases in which gray-scale sonography was equivocal or nondiagnostic (Table 32-3). In these studies, true-positive rates for the diagnosis of ovarian cancer (percentage of lesions with low impedance that were ovarian cancer) ranges from 80% to 100%, whereas false-positive (percentage of benign masses with low imped-ance) ranges from 0 to 20%. These results need to be analyzed relative to the population studied and techniques used. Although only approximately 50 stage I ovarian cancers have been reported worldwide, it would appear that CDS, coupled with the morphologic appearance of the mass, adds important clinical information.
Table 32-3VASCULAR RESISTANCE TO BLOOD FLOW, IN TERMS OF RESISTANCE (RI) OR PULSATILITY (PI) INDICES, BETWEEN MALIGNANT AND BENIGN AND EXAL LESIONS ||Download (.pdf) Table 32-3 VASCULAR RESISTANCE TO BLOOD FLOW, IN TERMS OF RESISTANCE (RI) OR PULSATILITY (PI) INDICES, BETWEEN MALIGNANT AND BENIGN AND EXAL LESIONS
|Reference ||Index ||Malignant ||Benign |
|Hata et al.40 ||RI ||0.469 ± 0.11 ||0.96 ± 0.17 |
|Fleischer et al.12 ||PI ||0.3–1.5 ||0.6–4.0 |
|Kawai et al.16 ||PI ||0.53 ± 0.65 ||1.44 ± 0.05 |
|Takay and Jouppila4 ||PI ||0.5 (0.5–0.9) ||0.6 (0.5–3.5) |
|Kitao41 ||RI ||0.50 ± 0.11 ||0.69 ± 0.18 |
|Kurjak et al.42 ||RI ||0.38 (0.27–0.61) ||0.52 (0.46–1.0) |
|Schneider et al.39 ||RI ||0.52 (0.2–1.0) ||0.84 (0.24–1.0) |
|Hamper et al.5 ||RI ||0.5 ± 0.17 (0.27–0.67) ||0.77 ± 0.33 (0.2–1.0) |
|Timor-Tritsch et al.2 ||RI ||0.39 (0.2–0.53) ||0.63 (0.23–0.98) |
|Levine et al.43 ||RI ||0.47 ± 0.11 ||0.57 ± 0.17 |
|Brown et al.44 ||RI ||0.39 ± 0.09 (0.25–0.50) ||0.62 ± 0.16 (0.34–0.90) |
|Valentin et al.32 ||PI ||0.9–0.94 ||0.18–0.96 |
|Carter et al.13 ||RI ||0.6 ± 0.1 ||0.7 ± 0.2 |
|Prompeler et al.45 ||RI ||0.40 (0.22–0.66) ||0.68 (0.26–1.0) |
|Chou et al.46 ||RI ||0.41 (0.18–0.68) ||0.68 (0.36–0.89) |
|Zaneta et al.47 ||RI ||0.46 ± 0.10 (0.27–0.99) ||0.72 ± 0.14 (0.43–0.90) |
|Salem et al.48 ||PI ||0.82 ± 0.38 (0.3–1.89) ||1.44 ± 0.65 (0.3–3.5) |
|Sengoku et al.49 ||PI ||0.57 ± 0.14 ||2.42 ± 0.67 |
|Franchi et al.50 ||RI ||0.49 (0.28–0.78) ||0.72 (0.48–0.98) |
|Maly et al.51 ||RI ||0.5 (0.3–0.6) ||0.7 (0.5–1.0) |
|Stein et al.52 ||RI ||0.53 ± 0.16 (0.27–0.83) ||0.65 ± 0.18 (0.27–0.98) |
|Buy et al.53 ||RI ||0.54 ± 0.11 (0.28–0.77) ||0.59 ± 0.14 (0.34–1.0) |
|Predanicetal.54 ||RI ||0.33 ± 0.03 (0.23–0.45) ||0.57 ± 0.02 (0.35–1.0) |
Color Doppler sonography provides important data concerning the evaluation of ovarian (adnexal) torsion. Adnexal torsion is usually associated with abnormalities in the blood supply and venous return from the ovary. This, in turn, may be associated with anatomic derangement and associated intraovarian hemorrhage as well.
In order to better understand the sonographic findings in torsion, it is important to consider the arterial and venous flow to and from and within the ovary. The ovary receives arterial blood from 2 sources. Variation in the completeness of the obstruction of this vascular supply may explain the variety of the spectrum of CDS findings that have been identified in ovarian torsion.24,25 Another parameter that may factor into what is seen with CDS is the pressures inside the ovary. This can be altered if there is increased venous pressure from interstitial (intraovarian) hemorrhage. Clearly, the CDS findings in torsion depend on the severity and chronicity of the torsion. In incomplete or intermittent torsion, the CDS findings may be minimal, whereas in patients with several twists or complete torsion, no flow will be detected. Typically, the first finding is that of lack of venous flow, in which case arterial flow may still be demonstrated, although there may be high-resistance flow in these cases.1,3,4 Subsequently, absent arterial flow is demonstrated. It is important to examine the inner portions of the ovary, because the capsular vessels may not be compro-mised. Demonstration of an enlarged ovary with small central cystic spaces resulting from macroscopic hemorrhage and compromised vascularity on CDS suggests a diagnosis of ovarian torsion. We have also reported on the CDS findings in isolated tubal torsion, which usually occurs in women who have undergone minor tubal ligation.25 The fusiform mass representing the distended torsed tube usually lacks any demonstrable flow on CDS. The interested reader is referred to Chapter 36 on pelvic pain for more extensive discussion on illustration of this topic.
Eighty percent of ovarian carcinomas arise in women older than 50, and the majority of these are of the cystic epithelial type. It is evident that demonstration of a cystic mass in a postmenopausal woman is of clinical signifi-cance. A cyst that fulfills all criteria for a simple cyst in the premenopausal woman has been shown to be benign in nearly 100% of cases in premenopausal women and in 95% of cases in postmenopausal women.14 Wolf et al examined 149 postmenopausal patients, 15.8% of whom demonstrated a benign cystic adnexal mass.26 The prevalence of ovarian carcinoma at age 60 is 70 per 100,000 women, whereas the prevalence of uniloculated, nonseptated ovarian cysts in this study was 14,800 per 100,000 women. This study would indicate that postmenopausal ovarian cysts are 200 times more frequent than ovarian carcinoma. In a follow-up study, Levine et al followed the natural history of simple adnexal cysts in postmenopausal women. In the 72 masses that were followed, 53% disappeared and 39% increased in size or remained constant.27 In a similar study performed in Scandinavia with a follow-up of 3 years, 78% of masses disappeared or did not change. Most of the cysts that regressed were in women less than 60 years of age. In 13%, new cysts were observed during the study interval.28 The postmenopausal ovary has long been viewed as a static organ. These studies, however, would tend to lend support to the fact that the ovary is a dynamic structure even into menopause.
Little is known concerning the natural history of ovarian carcinoma. It is not clear what role, if any, the formation of benign cysts play in tumorigenesis. In view of the prevalence of cysts in the ovaries of peri- and postmenopausal patients, the area lends itself to future research.29 These studies underscore the need to determine the malignant potential of these lesions to decrease unnecessary surgeries. Current management would be to consider sonographic follow-up for those women with small simple cysts demonstrating reassuring Doppler interrogation and normal CA-125 values. All other cases should be referred for further evaluation and possible surgery.