Information gained by sonography is useful in guiding the gynecologic surgeon through decision regarding surgical intervention. Sonography is the diagnostic modality of choice for evaluation of patient with a plevic mass.
Sonography usually provides clinically important paramaters for pelvic mass, include :
Confirmation of the presence or absence for a plevic mass
Delineation of the size, internal consistency and contour of the mass.
Establishment of the origin and anatomic relationship of the mass and pelvic
structure
A survey of abnormalities assosiated with malignant disease, such as ascites or
metastatic lesion
In the evaluation of the uterus and adnexa, transvaginal sonography (TVS) has an important role and it is the best used as an adjunct to and standart transabdominal scan (TAS). TAS affords detailed assessment of the morphology of adnexal mass.
Color doppler sonography (CDS) with spectral analysis has added to understanding and characterization of the lession based on of its depiction of vascularity of the mass.
Principles of Color Doppler Sonoghrapy
Diagnosis of ovarian tumor with CDS is based on detection of the low-impedance, high-velocity flow assoiated with tumor neovascularity.Normal arterioles have an inner muscular linning, but in tumor angiogenesis, a paucity of this linning is present and there may be arteriovemous shuting in tumor vessel. Absent of muscular linning, with CDS become show a “high velocity flow” and “low reisitance signal“. Increased diastolic flow relative to systolic flow occurs due to a decrease in resistance to forward flow.
Scanning procedures
Color doppler sonography can be performed using either abdominal or vaginal probes. Any sonographic evaluation of adnexal mass begins with its morphologic analysis. The mass should be caracterized as :
predominantly cystic, complex or solid
assesed internal structure for the presence of : papillary projections, septations (presence and thickness of septa) and echogenicity.
parietal wall thickness
secondary sign of malignancy, such as ascites, pelvic peritoneal implant etc.
Similar to caracterizing masses by their morphology, CDS requires multiple parameters need to be evaluated iclude :
vessel location
relative impedance
velocities
notch in the waveform during diastole : the nocth indicates momentary resistance to forward flow and is usually a sign that a vessel has a muscular coating. This nocth is often absent in malignancies.
The vessel must be localized as peripheral, central or miscellaneous ( ie, within projection, septations )
Analysis of the wave flow is performed using two standart indices.The first is Resistance Index (RI) and the second index is the Pulsatility Index (PI). RI defined as the maximum systolic velocity minus the end-diastolic velocity divided by maximum systolic velocity. PI defined as the maximum systolic minus the end-diastolic velocity divided by the mean velocity. There is debate as to which index is preferred, and several investigators have reported that both are equally accurate.At present, some investigators have assigned the value that is indicated for malignancy a cutoff of PI < 1,0 and RI < 0,4. Kurjaks and co workers used a scoring sistem that incorporate the variable of morphology, type of vaskularity and RI to predict malignancy.
Transvaginal colour and pulsed Doppler was used to visualize the uterine and ovarian arteries and the blood vessels within the ovarian stroma in all patients. The uterine artery was localized laterally to the uterus at the level of the corporocervical junction, and the ovarian artery was found lateral to the upper pole of the ovary, near the infundibulopelvic ligament. The stromal vessels of the ovary were identified as colour signals within the ovarian stroma of both ovaries.
A pulsed Doppler range gate was placed across each vessel, aiming for an angle of insonation close to 0° between the Doppler beam and the vessel. After detection of blood flow and visualization of the waveform of the uterine and ovarian arteries, four blood flow indices were automatically calculated: the pulsatility index (PI); the resistance index (RI); the peak systolic velocity (Vp, units of cm/s); and the end-diastolic velocity (Vd, units of cm/s). At least three consecutive correctly imaged blood flow velocity waveforms were analysed, and mean values of PI, RI, Vp and Vd calculated.
Color Doppler Sonography of Adnexal Masses
The pelvis is the source of benign and malignant ovarian lesions, tubo ovarian complexes and uterine leiomyomata.In general benign pelvic masses exhibit high-resistance waveform pattern. Using a combination of morphology and spectral analysis, investigators have attempted to determine the histopthology of pelvic masses. Table I show parameters of transvaginal color doppler sonography.
Table I : Transvaginal color doppler sonography : Parameters
Probable Histology
Parameters
Benign Malignant
Vessel location
Peripheral Central Other Peripheral Central
Maximum systolic velocity
High Intermediate Low High Low
( > 15cm/s) (b/w 10-15cm/s) (<10cm/s)
Impedance
High Intermediate Low High Low
PI (>1,5) (b/w 1,0-1,5 ) ( <1,0)
RI (>0,6) (b/w 0,4-0,6 ) ( <0,4 )
Waveform shape
+Notch Intermediate -Notch Positive Negative
Vessel “density”
High Intermediate Low Low High
( < 10%) (b/w 5-10%) (>5%)
While interpreting the sonographic finding, it is important to be aware of the patiens clinical history, her age, prior surgery, laboratory status such as CA-125 and other imaging ( CT / MRI ). Table II show the diferential diagnosis of adnexal masses by CDS based on vessel distribution and impedance.
Table II : Typical Transvaginal Color Doppler Sonography finding
in benign and malignant ovarian masses
Type of Masses Vessel Impedance
Distribution Relative Velocity
Corpus luteum Peripheral Low, high
Endometrioma Peripheral Variable
Dermoid cyst Peripheral and central Variable
Ovarian torsion Absent Very high if present
Benign epithelial Peripheral High, low
ovarian tumor
Malignant ovarian tumor Peripheral an central Low, high
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Ovarian Tumor
The management of ovarian tumors remains a common clinical gynecologic problem. Recently the role of color and spectral Doppler in the diagnosis of ovarian malignancy has been a subject of enormous debate. Many investigators have used color Doppler imaging in addition to B-mode ultrasound morphological characterization to discriminate between benign and malignant ovarian tumors
Multivariate logistic regression has been used in a few recent studies to predict the probability of malignancy in patients with ovarian tumors. They included sonographic variables of transvaginal B-mode and color Doppler imaging,clinical variables such as menopausal status or age and serum CA 125 levels. Doppler parameters always featured as independent predictors of malignancy.
Doppler energy is very useful for the detection of small vessels in the septa, papillary projections,or solid areas. Any color signals were counted and subsequently classified into three groups (no flow, low vascularity and high vascularity). The location of tumor vessels was stated as central (solid areas, septa and papillae) or peripheral. Pulsed Doppler was used to interrogate each color signal detected and a flow velocity waveform was obtained in each case. If it was an artery, then the RI and PI were calculated. Both RIand PI were calculated for each vessel if there was more than one artery within a given tumor. The lowest value was considered for analysis.
Doppler studies of ovarian blood flow are based on: semiquantitative analysis of Doppler flow waves recorded over the ovarian artery at its entry into the ovary and color Doppler mapping of intraovarian vessels.
Evaluate tumor with with Color Doppler showed presence of tumor neovascularisation in 92.59% of malignant tumors in contrast to 42.24% benign tumors.
The site of tumor vascularity did not affect the diagnosis in cystic neoplasm, as the tumor vascularity was encountered almost equally in the wall and septae. But, in solid malignant neoplasms; the central vascularity was encountered in 81.25% cases while peripheral vascularity was present in 18.75% cases. For ovarian malignancy Doppler energy, RI, and a central blood flow location were found to be the best predictive factors.In conclusion, the use of color Doppler energy imaging seems to be a useful secondary test when a mass is suspected to be malignant by B-mode ultrasonography.
Daftar Pustaka
- Schmidt W, Kurjak A .Color Doppler Sonography in Gynecology and Obstetrics Translated by Terry Telger. Stuttgart, Germany: Georg Thieme Verlag, 2005.
- Fleischer AC,Entman SS. Sonographic Evaluation of Pelvic Masses with Transabdominal and/or Transvaginal Sonography in Sonography in Obstetrics and Gynecology, Principles and Practice.5th edition.Appleton and Lange, Connecticut, USA,1996,p: 791-813
- Palmer PES, editor : Panduan Pemeriksaan Diagnostik USG – World Health Organization,EGC,Jakarta,2001.
- Guerriero S, Ajossa S, Risalvato A et al. Diagnosis of adnexal malignancies by using color Doppler energy imaging as a secondary test in persistent masses. Ultrasound in Obstetrics and Gynecology 11 (4). 1998, 277–282
- Tailor A. Jurkovic D.; Bourne T.H.; Natucci M.; Collins W.P.; Campbell S. Comparison of Transvaginal Color Doppler Imaging and Color Doppler Energy for Assessment of Intraovarian Blood Flow. Obstetrics and Gynecology, Vol 91, Number 4, April 1998 , pp. 561-567
- Taori KB, Mitra KR, Ghonge NP, Ghonge SN. Doppler determinants of Ovarian malignancy : Experience with 60 patients. Genitourainary tract imaging. Vol 12,2,2002. p: 245 -249
- Marret H, Ecocard R, Giraudea B et al . Color Doppler energy prediction of malignancy in adnexal masses using logistic regression models. Ultrasound Obstet Gynecol 2002; 20: p.597-604
- Block B.Color atlas of ultrasound anatomy. Thieme, Braunschweig Germany.2004