Published online before print June 21, 2002, 10.1148/radiol.2242911110
(Radiology 2002;224:429-435.)
© RSNA, 2002
Echogenic Ovarian Foci without Shadowing: Are They Caused by Psammomatous Calcifications?1
Derek Muradali, MD, FRCPC,
Terence Colgan, MD, FRCPC,
Eran Hayeems, MD, FRCPC,
Peter N. Burns, PhD and
Stephanie R. Wilson, MD, FRCPC
1 From the Departments of Medical Imaging (D.M., E.H., S.R.W.) and Pathology (T.C.), University Health Network, Toronto General Hospital, 200 Elizabeth St, Toronto, Ontario, Canada M5G 2C4; and Department of Medical Biophysics, University of Toronto, Imaging Research, Sunnybrook and Women’s College Health Sciences Centre, Toronto, Ontario, Canada (P.N.B.). Received June 25, 2001; revision requested July 27; revision received November 7; accepted January 7, 2002. Address correspondence to D.M. (e-mail: derek.muradali@uhn.on.ca).
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ABSTRACT
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PURPOSE: To determine and report the spectrum of ultrasonographic appearances of echogenic ovarian foci (EOF) without shadowing in otherwise normal ovaries and the histopathologic and physical characteristics of these foci.
MATERIALS AND METHODS: The appearances of foci on transvaginal pelvic sonograms obtained in 189 patients with EOF were prospectively analyzed. The foci were classified according to bilaterality, size, number (<5, 5–10, or >10), and location (peripheral, central, or diffuse). At histopathologic analysis, resected normal ovaries, seven with and 10 without echogenic foci, in a water bath were scanned. The foci were then localized for histopathologic correlation. To assess the physical properties of the foci, tissue-mimicking water- and glycerol-based phantoms, with voids of different diameters, in a water bath were scanned with 8- and 70-MHz transducers.
RESULTS: At appearance analysis, EOF (mean diameter, 1.8 mm ± 0.6 [SD]) were detected unilaterally in 103 (54.5%) of 189 patients. EOF were distributed peripherally in 183 (66.5%), centrally in 15 (5.5%), and diffusely in 77 (28.0%) of 275 ovaries. There were fewer than five foci in 123 (44.7%), five to 10 foci in 91 (33.1%), and more than 10 foci in 61 (22.2%) of 275 ovaries. At histopathologic analysis of the seven ovaries with EOF, the foci had tiny cysts with no evidence of calcifications. A single cyst cluster was identified in two of 10 ovaries that did not have echogenic foci. At physical property analysis, single echogenic foci were associated with specular reflection from the walls of unresolved cysts that were comparable in size to the ultrasound wavelength (about 0.50 mm).
CONCLUSION: EOF without shadowing are caused by a specular reflection from the walls of tiny unresolved benign cysts rather than by psammomatous calcifications.
© RSNA, 2002
Index terms: Ovary, abnormalities, 852.817 • Ovary, neoplasms, 852.311 • Ovary, US, 852.12985, 852.12989, 855.12985, 855.12989 • Ultrasound (US), transvaginal, 852.12985, 852.12989, 855.12985, 855.12989
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INTRODUCTION
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While performing transvaginal and transvesical pelvic ultrasonography (US), we frequently encounter women with bright echogenic foci that are not associated with shadowing in ovaries that otherwise appear to be normal (Fig 1). These foci vary in US appearance and in their number and location in the ovary. They have a striking resemblance to the echogenic foci observed in certain malignant ovarian masses, particularly primary and secondary serous adenocarcinomas (Fig 2). In these instances, the bright foci observed on sonograms are thought to represent intratumoral psammomatous calcifications (1,2). In addition to ovarian tumors, tiny flecks of calcium that also show bright echogenicities on sonograms have been described with primary serous carcinoma of the peritoneum, papillary carcinoma of the thyroid (Fig 3), and liver metastasis from mucin-producing tumors of the gastrointestinal tract (3–5). Therefore, the US identification of bright echogenic foci in a visceral mass may be an important feature that suggests the possibility of a malignancy. Nonetheless, the clinical importance, pathologic origin, and physical properties of echogenic foci in an otherwise normal ovary remain uncertain (6,7).
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Figure 2a. (a) Transvaginal pelvic US scan obtained in 70-year-old woman with histologically proven serous papillary adenocarcinoma of the right ovary shows numerous bright echogenic foci (arrows) in a large ovarian mass (M). At histologic analysis, intratumoral psammomatous calcifications were detected. (b) Transvaginal pelvic US scan obtained in 55-year-old woman with peritoneal carcinomatosis secondary to metastatic papillary adenocarcinoma of the ovary shows bright EOF (arrowheads) in a visceral peritoneal plaque (arrows) adhering to the surface of a small-bowel loop (B). A = ascites.
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Figure 2b. (a) Transvaginal pelvic US scan obtained in 70-year-old woman with histologically proven serous papillary adenocarcinoma of the right ovary shows numerous bright echogenic foci (arrows) in a large ovarian mass (M). At histologic analysis, intratumoral psammomatous calcifications were detected. (b) Transvaginal pelvic US scan obtained in 55-year-old woman with peritoneal carcinomatosis secondary to metastatic papillary adenocarcinoma of the ovary shows bright EOF (arrowheads) in a visceral peritoneal plaque (arrows) adhering to the surface of a small-bowel loop (B). A = ascites.
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Figure 3. Sagittal US scan of the thyroid gland of 33-year-old man shows multiple bright echogenic foci (arrows) in a solid nodule (N). Papillary thyroid carcinoma associated with psammomatous calcifications was proved at biopsy. T = normal thyroid gland.
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An initial study was performed by Brandt et al (7) to assess the clinical importance of echogenic foci in ovaries that appeared to be otherwise normal on gray-scale sonograms. These authors presumed that any visceral hyperechoic focus was indicative of a calcium deposit, even if the focus was not associated with posterior shadowing. The pelvic US scans obtained in 15 patients with echogenic ovarian foci (EOF) were retrospectively reviewed, and the histologic features of 10 ovaries resected from these patients were analyzed. At histologic analysis, four ovaries were associated with masses (dermoid calcified mucinous cystadenoma, two ovaries with adenofibromas), whereas the remaining ovaries were unremarkable. Although there was no evidence of frank malignancy in either the histologic or clinical part of that study, the authors concluded that the presence of an echogenic focus in an ovary could represent the earliest manifestation of malignancy, and, thus, clinical or imaging follow-up was indicated owing to the possible risk of ovarian carcinoma (7). Even in that study, however, there was no factual basis for the assumption that an echogenic focus at US definitely represents a region of calcification.
In a later study, Kupfer et al (6) reviewed the histologic features of nine resected ovaries that had multiple peripheral bright echogenic foci and of one resected ovary that did not have an echogenic focus at preoperative transvaginal US. At histologic assessment, multiple superficial inclusion cysts with associated psammomatous calcifications were identified in a peripheral location in all 10 ovaries. The similarity in location between the psammomatous calcifications at histologic analysis and the EOF at US led the authors to conclude that psammomatous calcifications were the cause of the peripheral echogenic foci. However, this conclusion was based on inference rather than direct US-histologic correlation. Furthermore, there was no explanation for the fact that one ovary with multiple peripheral psammomatous calcifications at histologic analysis did not show evidence of even a single echogenic focus at transvaginal US (6). We therefore question the relationship between the psammomatous calcifications and the bright EOF described in that study. Because the resected ovaries were not scanned to directly localize the echogenicities, we believe that it is difficult to conclude that peripheral psammomatous calcifications were the source of the echogenic foci.
We were stimulated to investigate these tiny bright foci on the basis of the study findings just described and because the pathologic origin of these foci is uncertain, and, thus, there is no clear consensus with regard to the appropriate care of patients who have this finding at routine pelvic US. The purposes of this three-part study were to determine and report (a) the spectrum of appearances of EOF in otherwise normal ovaries, (b) the histopathologic characteristics of EOF, and (c) the physical properties of these foci.
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MATERIALS AND METHODS
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Part 1: Spectrum of US Appearances of EOF
In this part of the study, we prospectively investigated the spectrum of appearances of EOF at US in patients who presented to the Division of Ultrasound, Toronto General Hospital, University Health Network, Ontario, Canada, during a 1-year period (1998–1999). Of a series of 4,000 patients who underwent 4,000 transvaginal pelvic US examinations at our institution during this time, 189 nonconsecutive patients (mean age, 46.5 years; age range, 20–77 years) with tiny bright echogenic foci without posterior shadowing or artifact in otherwise normal-appearing ovaries at US were entered into the study. The patients were enrolled in a nonconsecutive manner outside of peak hours because of the high-volume, busy nature of our US department. Therefore, the study did not include all of the patients with EOF who were examined in our department between 1998 and 1999, but rather it included a sample population of these patients.
There were a variety of indications for pelvic US in this patient group; these included familial ovarian cancer screening (n = 54), fibroids (n = 32), follow-up of physiologic cysts (n = 19), abdominal pain (n = 20), obstetric imaging (n = 5), endometriosis (n = 14), cervical dysplasia or cancer (n = 11), hydrosalpinx (n = 1), infertility (n = 3), and endometrial assessment (n = 30). All patients were scanned with a transvaginal probe (C8-4; Advanced Technology Laboratories Ultrasound, Bothell, Wash) and a commercially available US scanner (HDI 3000 or HDI 5000; Advanced Technology Laboratories Ultrasound).
Each case was directly supervised by a physician (D.M., S.R.W.) with expertise in US. EOF were classified according to bilaterality and number of foci per ovary (<5, 5–10, or >10). The location of the foci in the ovary also was documented and was classified as peripheral (on or within 2 mm of ovary surface), central, or diffuse (peripheral and central involvement) (Fig 4). For each ovary, the largest echogenic focus was measured according to the single longest dimension.
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Figure 4a. (a) Transvaginal pelvic US scan obtained in 54-year-old woman shows multiple peripheral (arrowheads) and central (arrows) EOF that are not associated with posterior US artifact. (b) Transvaginal pelvic US scan obtained in 43-year-old woman shows central echogenic foci (arrows) without associated posterior artifact in an otherwise normal ovary.
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Figure 4b. (a) Transvaginal pelvic US scan obtained in 54-year-old woman shows multiple peripheral (arrowheads) and central (arrows) EOF that are not associated with posterior US artifact. (b) Transvaginal pelvic US scan obtained in 43-year-old woman shows central echogenic foci (arrows) without associated posterior artifact in an otherwise normal ovary.
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All pelvic US scans obtained in the 189 study patients in the preceding 3 years were subjectively evaluated for changes in foci. Some of the study patients were also followed up sonographically for up to 21 months for assessment of interval foci changes. Our institutional review board approved this part of the study; informed patient consent was not required.
Part 2: Histopathologic Characteristics of EOF
To determine the histopathologic features of EOF by using direct US-histopathologic correlation, 17 consecutively resected ovaries that appeared to be morphologically normal at visual inspection at surgery were placed in a bath of degassed water and scanned with US. Seven of these 17 ovaries showed nonshadowing echogenic foci. None of the patients in this part of the study had EOF at US in the first part of the study.
For each ovary, the largest echogenic focus was measured according to the single longest dimension. The location of the echogenic foci in the ovary was documented and classified as peripheral (on or within 2 mm of ovary surface), central, or diffuse (peripheral and central involvement) (Fig 5a). The number of echogenic foci per ovary (<5, 5–10, >10) also was recorded.
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Figure 5a. (a) Transverse US scan of an ovary resected from 63-year-old woman and imaged while immersed in a water bath shows a dominant simple cyst (C) with multiple bright EOF (arrows) surrounding the cyst and throughout the parenchyma. (b) For direct US-histopathologic correlation, a suture (arrowheads) soaked in black India ink was placed, with US guidance, around one of the EOF (open arrow) depicted in a. Solid arrows point to EOF surrounding the now collapsed dominant cyst (C). (c) Histologic specimen from the ovary depicted in a and b shows multiple small cysts (C) and no evidence of associated psammomatous calcifications in the area where the bright echogenic focus was localized with US guidance in b. Arrowheads point to the surface of the ovary.
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Figure 5b. (a) Transverse US scan of an ovary resected from 63-year-old woman and imaged while immersed in a water bath shows a dominant simple cyst (C) with multiple bright EOF (arrows) surrounding the cyst and throughout the parenchyma. (b) For direct US-histopathologic correlation, a suture (arrowheads) soaked in black India ink was placed, with US guidance, around one of the EOF (open arrow) depicted in a. Solid arrows point to EOF surrounding the now collapsed dominant cyst (C). (c) Histologic specimen from the ovary depicted in a and b shows multiple small cysts (C) and no evidence of associated psammomatous calcifications in the area where the bright echogenic focus was localized with US guidance in b. Arrowheads point to the surface of the ovary.
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Figure 5c. (a) Transverse US scan of an ovary resected from 63-year-old woman and imaged while immersed in a water bath shows a dominant simple cyst (C) with multiple bright EOF (arrows) surrounding the cyst and throughout the parenchyma. (b) For direct US-histopathologic correlation, a suture (arrowheads) soaked in black India ink was placed, with US guidance, around one of the EOF (open arrow) depicted in a. Solid arrows point to EOF surrounding the now collapsed dominant cyst (C). (c) Histologic specimen from the ovary depicted in a and b shows multiple small cysts (C) and no evidence of associated psammomatous calcifications in the area where the bright echogenic focus was localized with US guidance in b. Arrowheads point to the surface of the ovary.
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One representative echogenic focus from each of the seven ovaries was then localized with US guidance. The focus was selected because of the technical ease of localization with a 3-0 silk suture soaked in black India ink (Fig 5b). The ovary was then sectioned for histopathologic evaluation, and the entire suture-ink track was followed microscopically to determine the pathologic origin of the EOF that were detected sonographically.
Ten of the 17 resected ovaries, which also appeared to be morphologically normal at surgery but did not contain echogenic foci at waterbath US, were examined histopathologically by means of analysis of multiple sections from throughout the entire ovary. For the purposes of this study, the histopathologic evaluation of these ovaries was more extensive than that which would be routinely performed at assessment of morphologically normal ovaries removed at surgery. These 10 ovaries functioned as control specimens for this part of the study.
All ovaries were scanned within 15 minutes after resection with either a curvilinear 7.5-MHz or a linear 12–5-MHz transducer and the commercially available US scanner (HDI 3000 or HDI 5000). The ovaries were fixed in formalin immediately after they were scanned. The maximum scanning time per ovary was 20 minutes. At the time of this study, our institutional review board did not require its approval for the evaluation of pathologic specimens.
Part 3: Physical Properties of EOF
The results of parts 1 and 2 of our study motivated us to create an in vitro model of an ovary containing tiny simple parenchymal cysts. A soft-tissue phantom that was made of agar and graphite and that had two rows of voids with different diameters (0.30, 0.40, 0.50, 0.70, 0.80, 0.92, 1.26, and 1.66 mm) was used. When scanned in the transverse plane, the voids mimicked cysts that were imaged by using an ultrasound beam with a negligible elevation width (Fig 6). To investigate the effect on the resulting US scan of matching the impedance of the fluid to that of the tissue gel, a phantom with identical voids was filled with a glycerol-ethanol solution (Fig 7). Glycerol decreases the speed of sound.
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Figure 6. Transverse US scan of tissue phantom, scanned in a water bath, with two rows of cysts that range in size from 0.30 mm (arrowheads) to 1.66 mm (curved arrow) in diameter shows that cysts that range in size from 0.50 to 1.66 mm in diameter are associated with bright echogenic foci arising from the anterior and posterior walls (straight arrows) of the cysts. However, the smallest cysts, which are 0.30 mm in diameter, appear as a single bright echogenic focus (arrowheads).
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Figure 7. Transverse US scan of glycerol-ethanol phantom. To investigate the effect on the resulting US scan of matching the impedance of the fluid to that of the tissue gel, a phantom with identical voids (size range, 0.30-1.66 mm) was filled with a glycerol-ethanol solution. At US with an 8-MHz transducer, the three largest voids appear as an anechoic space (arrowheads) without evidence of specular echoes. Smaller voids are not seen.
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To mimic the imaging of an ovary with a transvaginal probe as closely as possible, we placed each phantom in a bath of degassed water and then scanned them by using an 8-MHz linear transducer that was fixed to a stationary stand and connected to a US scanner (L12–5, HDI 5000; Advanced Technologies Ultrasound). Images of the phantoms were obtained in the sagittal and transverse planes, at different distances from the surface of the transducer, and with different angles of incidence. After scanning the phantoms with the 8-MHz linear transducer, we scanned them with a custom-made high-frequency, high-spatial-resolution 70-MHz transducer to confirm the morphologic features of the voids and ensure that the phantoms were free of air bubbles that might produce an echogenic focus.
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RESULTS
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Part 1: Spectrum of US Appearances of EOF
EOF were detected unilaterally in 103 (54.5%) of the 189 patients and bilaterally in 86 (45.5%); thus, a total of 275 ovaries with bright echogenic foci were identified. Most commonly, the foci were very small, and they had a mean diameter of 1.8 mm ± 0.6 (SD) (range, 1–3 mm).
The echogenic foci were distributed peripherally in 183 (66.5%), centrally in 15 (5.5%), and diffusely in 77 (28.0%) of the 275 ovaries. Fewer than five foci were detected in 123 (44.7%) of the 275 ovaries; five to 10 foci, in 91 (33.1%) ovaries, and greater than 10 foci, in 61 (22.2%) ovaries.
The US studies previously obtained in 116 of the 189 study patients were reviewed (range, 1–38 months), and there was no interval change in foci. The follow-up US studies obtained in 86 patients (range, 1–21 months) also showed no interval change in foci. At all examinations, the ovaries appeared to be morphologically normal. Thirty-two patients did not undergo any previous pelvic imaging studies or follow-up US.
Part 2: Histopathologic Characteristics of EOF
At US scanning of the seven morphologically normal resected ovaries in a water bath, the EOF had a mean diameter of 1.60 mm ± 0.50 (range, 1–2 mm) and were distributed in either peripheral (six [86%] ovaries) or peripheral and central (one [14%] ovary) locations. Fewer than five foci were detected in four (57%) of the seven normal ovaries; five to 10 foci, in two (29%) ovaries; and more than 10 foci, in one (14%) ovary.
All 17 ovaries that were evaluated in this part of the study (seven ovaries with EOF and 10 control ovaries without EOF) were normal at final pathologic analysis. At histopathologic analysis, the echogenic foci in the seven ovaries corresponded to either central (one [14%] ovary) or peripheral (four [57%] ovaries) clusters of inclusion cysts (Fig 5) or to solitary corpus luteum cysts (two [29%] ovaries), and there was no evidence of associated calcifications. Tissue contraction during fixation made it difficult to determine the exact sizes of these cysts. However, all of the cysts that produced EOF were smaller than 0.50 mm in diameter. A single cluster of inclusion cysts was identified in two of the 10 control ovaries.
Part 3: Physical Properties of EOF
At US scanning of the water-based tissue phantom with the 8-MHz linear transducer, the cysts that ranged in size from 0.50 to 1.66 mm in diameter were anechoic centrally and had bright echogenic foci arising from specular reflections from the anterior and posterior walls of the cyst (Fig 6). With decreasing cyst size, the echogenic foci emanating from the anterior and posterior walls persisted, but the central anechoic portion gradually could not be resolved—that is, rendered indistinguishable on the image. The smallest cyst (0.3 mm) appeared as a single bright focus, without posterior artifact or resolution of the central lumen (Fig 6). These findings were unchanged when the phantom was scanned at varying distances from the surface of the transducer and at different angles of incidence (Fig 8), indicating that the echogenic foci were specific to insonation of the cysts and not dependent on the geometry of the phantom.
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Figure 8a. Transverse US scans of tissue phantom in a water bath and scanned (a) at different distances from the transducer and (b) at different angles of incidence show persisting echogenic foci, as observed when the tissue phantom was scanned perpendicular to the ultrasound beam (Fig 6). These findings indicate that the observed echogenic foci are specific to the cysts and independent of the geometry of the phantom.
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Figure 8b. Transverse US scans of tissue phantom in a water bath and scanned (a) at different distances from the transducer and (b) at different angles of incidence show persisting echogenic foci, as observed when the tissue phantom was scanned perpendicular to the ultrasound beam (Fig 6). These findings indicate that the observed echogenic foci are specific to the cysts and independent of the geometry of the phantom.
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At US scanning of the glycerol-based phantom with an 8-MHz linear transducer, the voids appeared as anechoic spaces, and there was no evidence of associated echogenic foci (Fig 7). These findings indicated that the echogenic foci observed in the water-based tissue phantom at US were associated with the specular reflection arising from the acoustic impedance mismatch between the fluid in the cyst lumen and the surrounding soft tissue. In the absence of an acoustic impedance mismatch, the echogenic foci disappeared.
When the phantoms were scanned with a 70-MHz transducer, all cysts were resolved with sharp well-defined wall margins (Fig 9). The cysts were not associated with echogenic foci, regardless of their diameter. This indicated that the specular reflection that produced the echogenic foci occurred only at those frequencies that are used in the range of diagnostic US.
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Figure 9. Transverse US scan of tissue phantom in water bath and scanned with a 70-MHz transducer shows all cysts are resolved, have well-defined margins, and have no evidence of specular reflection. These findings indicate that the specular reflection needed to produce an echogenic focus at scanning with an 8-MHz transducer occurs only in the range of diagnostic US.
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The findings in this final part of the study showed that individual cysts or clusters of cysts that are insonated at frequencies in the diagnostic range can result in bright echogenic foci secondary to a specular reflection at the lumen-tissue interface. In addition, tiny cysts have the potential to appear as a single bright echogenic focus without resolution of the fluid center.
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DISCUSSION
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US scans that show bright echogenic foci, especially those associated with distal acoustic shadowing, are frequently associated with flecks of calcium at histopathologic analysis. Our study results show that a nonshadowing echogenic focus on a sonogram is not diagnostic of underlying calcium and can be related to minute cysts below the spatial resolution of diagnostic US.
The study results suggest that the echogenic foci produced by these tiny cysts may be the result of a specular reflection from the front and back walls of the cysts. However, the appearance of the focus depends on the size of the individual cyst and the resolution of the US scan. In our phantom model, cysts that ranged in size from 0.50 to 1.66 mm in diameter produced an echogenic focus from each wall, whereas the very small cysts (0.3–0.4 mm) appeared as either a double or single echogenic focus. We postulate that the observed difference in the appearances of the cysts was due to the distance between the anterior and posterior surfaces of the cyst in relation to the ultrasound wavelength. When this distance is large, the two walls are resolved as two distinct echoes. As the cyst diameter becomes comparable to the axial resolution of the US scan, the cyst acts as a point scatterer and a single echogenic point is seen. With our phantoms, the axial resolution was about 0.2 mm; at clinical US with a lower frequency transducer in the aberrant medium of the pelvis, the effective resolution may be closer to 1 mm. Both removing the acoustic impedance difference by using glycerol and reducing the wavelength by using high-frequency US (in this case, to 0.02 mm) cause the echo to disappear; these findings support our observations. We therefore conclude that echogenic foci that are not associated with distal shadowing artifact can be accounted for by single or multiple small cysts that have an average diameter of 1 mm or less.
In our study, we scanned the ovaries while they were immersed in a water bath to localize any associated echogenic foci and thus permit direct US-histopathologic correlation. In addition, a control group of ovaries without evidence of echogenic foci at water bath US was evaluated histopathologically for comparison. The results showed that tiny cysts may appear as bright EOF when they are scanned at frequencies in the range of diagnostic US. Although it is possible that flecks of calcium in the ovary account for a portion of the echogenic foci observed in clinical practice, they were not identified as causes of the foci in our study.
Our study did not include large echogenic foci or foci associated with distal acoustic shadowing. We believe that the physical properties of these foci may be different, because their appearances are different from those of the commonly encountered bright echogenic foci that we investigated in the present study.
The limitations of our study included the relatively small number of ovaries with echogenic foci in the second part (histopathologic correlation) of the study, as well as the technical difficulty encountered in scanning the normal ovaries in water baths. In some instances, the relatively small size of the ovary, coupled with intervening bubbles of air floating within the scanning field and sticking to the surface of the ovary, made US scan interpretation difficult. Two of our control ovaries were associated with a single tiny cluster of inclusion cysts, although no EOF were appreciated by the sonographer during water bath scanning. We believe that the foci produced by these tiny clusters either were not visualized by the sonographer owing to the technical difficulty of the procedure or were misinterpreted as tiny bubbles of gas adhering to the ovarian surface.
In addition, we recognize that our method for localizing EOF, in which a suture was extended around rather than through or at the echogenic focus, may have been less than ideal for precise histopathologic correlation. Although this method was excellent for localizing and evaluating peripheral foci on the surface of the ovary, evaluating central echogenic foci was more challenging because the suture track included a larger volume of normal surrounding tissue. Despite these minor limitations, there was overwhelming evidence in both the histopathologic correlation portion and the phantom model portion (for physical property analysis) of our study that tiny cysts or clusters of cysts may appear as a bright echogenic focus at US.
In conclusion, there is a wide spectrum of appearances of bright echogenic foci, which vary in number, distribution, and location, in an otherwise normal ovary. In our study, these foci had a large association with nonsubstantial small cysts; thus, in our opinion, they should be regarded as benign. Therefore, we believe further imaging investigations or clinical follow-up may not be warranted in patients with these US findings.
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ACKNOWLEDGMENTS
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We acknowledge the contribution of Kasia Harasiewicz, MSc, P. Eng, in the development of the phantoms used in the study.
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FOOTNOTES
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Abbreviation: EOF = echogenic ovarian foci
Author contributions: Guarantors of integrity of entire study, all authors; study concepts and design, D.M., S.R.W., T.C., P.N.B.; literature research, D.M., E.H.; clinical studies, D.M., S.R.W.; experimental studies, D.M., E.H.; data acquisition, D.M., E.H.; data analysis/interpretation, all authors; statistical analysis, D.M., E.H.; manuscript preparation, D.M.; manuscript definition of intellectual content, editing, revision/review, and final version approval, all authors.
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REFERENCES
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D. L. Brown, M. C. Frates, M. G. Muto, and W. R. Welch
Small Echogenic Foci in the Ovaries: Correlation With Histologic Findings
J. Ultrasound Med.,
February 1, 2004;
23(2):
307 - 313.
[Abstract]
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ABSTRACT
INTRODUCTION
