| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Technical Developments |
1 From the Department of Radiology, University Hospitals Catholic University, Leuven, Herestraat 49, 3000 Leuven, Belgium. Received June 26, 1998; revision requested July 30; final revision received January 13, 1999; accepted April 30. Address reprint requests to L.V.H. (e-mail: lieven.vanhoe@hnbe.com).
 |
Abstract |
|---|
 TOP Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Index terms: Uterine neoplasms, diagnosis, 854.121411, 854.121412, 854.32 • Uterine neoplasms, MR, 854.121411, 854.121412, 854.32 • Uterine neoplasms, staging, 854.121411, 854.121412, 854.12143, 854.32
|
Introduction |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The purpose of this study was to assess whether the use of intravaginal contrast medium could contribute to improved visualization of the upper vagina and fornices and to more accurate staging of cervical tumors.
|
Materials and Methods |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
All of the patients had undergone biopsy prior to referral to the MR department. The final histopathologic diagnosis was not available at the time the MR study was performed. Clinical staging at surgery with anesthesia was performed after MR imaging and thus did not contribute to the selection of patients for MR imaging. Because the gynecologists who performed the clinical staging were aware of the results obtained at MR imaging, a blinded comparison was not possible. Therefore, we did not include the results obtained at clinical staging in our study.
MR images were obtained with a 1.5-T system (Vision Magnetom; Siemens, Erlangen, Germany) with gradient switching capability of 25 mt/m in a rise time of 300 seconds. All patients underwent imaging with a phased-array coil. No oral contrast media or drugs were given.
MR images were obtained both before and after opacification of the vagina with the contrast medium. First, nonenhanced T1-weighted images were obtained in the axial plane. Images were obtained with a magnetization-prepared spoiled gradient-echo (turbo fast low-angle shot [FLASH]) sequence: repetition time/echo time msec, 7.7/4.2; inversion time, 300 msec; flip angle, 15°; matrix, 192 x 256; bandwidth, 195 Hz per pixel; section thickness, 6 mm; intersection gap, 0.6 mm; acquisition time per section, 700 msec. Two interleaved series of 20 sections were acquired in 35 seconds each. Fat suppression was not applied. An average field of view of 263 x 320 mm was used.
T2-weighted fast spin-echo images were obtained in the axial, sagittal, and coronal planes: 6,000/120; four signals acquired; matrix, 260 x 512 (75% partial-Fourier reconstruction); echo train length, 49; echo spacing, 5.8 msec; section thickness, 5 mm; intersection gap, 1 mm; acquisition window, 280 msec with a 90° pulse; acquisition time, 1 minute 18 seconds. The field of view was adapted to the size of the patient and averaged 260 x 320 mm.
Next, the vagina was filled with contrast medium, and imaging was repeated with the same sequences.
In addition, multiplane multisection (four to six sections) dynamic contrast material–enhanced MR imaging was performed with the turbo FLASH technique. One to three sections were obtained in the axial plane, and two to four sections in the sagittal plane. Data acquisition began 10 seconds after initiation of rapid manual injection of a bolus of gadopentetate dimeglumine (Magnevist; Berlex Laboratories, Wayne, NJ) (0.1 mol/L per kilogram of body weight). Depending on the number of sections, images were obtained every 4–6 seconds for approximately 3 minutes.
Finally, images were obtained in a more delayed phase of perfusion (approximately 5 minutes after bolus injection) with use of a fat-suppressed FLASH sequence: 744/4.8; flip angle, 75°; matrix, 93 x 256; section thickness, 6 mm; intersection gap, 0.6 mm; acquisition time, 1 minute 10 seconds.
Vaginal Opacification
For opacification of the vagina, we used the contrast medium that is used in our department for colpocystodefecographic studies. The contrast medium consisted of a mixture of 20 mL of maltodextrin/calcium lactate (Nutriton; Nutricia, Zoetermeer, the Netherlands), 100 mL of water, and 100 mL of barium. After the procedure was explained to the patient, a bladder catheter was positioned into the vagina by a radiologist (D.V., L.V.H.), and the contrast medium was injected slowly until spillage was observed. The actual filling was performed on the MR table and required only a few minutes. The purpose of adding water was to ensure optimal contrast (high signal intensity on T2-weighted images and low signal intensity on T1-weighted images); maltodextrin/calcium lactate was added to avoid early spillage.
Image Evaluation
For the purpose of this study, we compared T2-weighted fast spin-echo images obtained before and after administration of intravaginal contrast material. These images were independently analyzed by two radiologists (L.V.H., D.V.) in two different sessions. In the first session, all images obtained without vaginal opacification were studied, and an attempt was made to determine the T stage of the tumor. In the second session, 3 weeks later, images obtained after vaginal opacification were analyzed. To avoid bias, patient images were presented in an order different from that in the first session. Again, the T stage of the tumor was determined.
Finally, in a third session, the two sets of images were analyzed in a side-by-side comparison. Both observers determined in consensus whether they found the use of intravaginal contrast medium useful for visualization of anatomic structures and evaluation of tumor extent.
|
Results |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Results Obtained with Vaginal Opacification
The injection of contrast medium into the vagina did not cause discomfort in any of the patients. As expected, the contrast medium was moderately hyperintense on T2-weighted images (Figs 1, 2) and hypointense on T1-weighted images. Distention of the vagina was adequate in all patients; the exact thickness of the vaginal wall could always be adequately assessed.
|
|
|
|
In a second patient, with endometrial carcinoma, two submucosal metastases in the distal portion of the vagina were detected only at evaluation of MR images obtained with vaginal opacification (stage IIIb instead of I).
In these two patients (20%), the addition of intravaginal contrast material changed both tumor stage and patient treatment.
Subjectively, both observers agreed that intravaginal contrast medium improved delineation of the cervical orifice, vaginal wall, and fornices in all patients. In the patients with cervical carcinoma, improved differentiation of the patterns of tumor spread—including forniceal obliteration without extracervical spread; invasion of the wall of the fornices, vagina, or both; vaginal intraluminal protrusion; and parametrial invasion—was reported twice (Fig 1). In another patient, with a cervical carcinoma that involved the posterior wall of the vagina, the clinical benefit of intravaginal contrast medium was considered doubtful because images obtained before vaginal opacification also revealed thickening of the posterior vaginal wall (Fig 2).
|
Discussion |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
The mixture of maltodextrin/calcium lactate, water, and barium used in this study has several characteristics that make it well suited for use as a vaginal contrast medium at MR imaging. First, unlike pure fluid, it distends the vagina and remains in situ during the time of an MR study. Second, its signal intensity characteristics are quite different from those of normal cervical, forniceal, and vaginal tissue and tumor, which enables adequate delineation of these structures on both T1- and T2-weighted images. Furthermore, the contrast medium is easy to concoct. Water and barium are abundant in every radiology department, and maltodextrin/calcium lactate is commercially available as a product used to thicken baby milk.
Although the use of vaginal contrast media has not been described, to our knowledge, use of a vaginal tampon has been proposed to improve vaginal localization (6). In patients referred for cervical tumor staging, we prefer use of vaginal contrast media because, in our preliminary experience, they distend the vagina more than a tampon does.
In this study, the injection of contrast medium into the vagina did not cause discomfort in any of the patients. It should be mentioned that none of our patients had severe vaginal bleeding. Clinically important bleeding should probably be considered a contraindication for use of vaginal contrast media.
This study has some limitations. First, images obtained after intravenous injection of contrast medium were not included in the evaluation. For practical reasons, intravenous contrast material–enhanced images were obtained only once (ie, at the end of each study). Theoretically, it is possible that by analyzing intravenous contrast-enhanced images obtained without vaginal opacification, results in session 1 would have improved. This appears unlikely, however. Although dynamic contrast-enhanced MR imaging may be superior to T2-weighted MR imaging for assessment of the depth of stromal invasion (7), this technique does not necessarily contribute to improved visualization of parametrial, forniceal, or vaginal wall involvement (2,5).
A second limitation of this preliminary study is the small number of patients included. It is clear that further work is required to determine the precise indications for vaginal opacification. As a result of our initial experience, an interactive staging approach is now used at our institution for MR imaging evaluation of cervical carcinoma. After evaluation at the computer console of the first series of T2-weighted images (obtained in three planes), we determine the indication for use of intravenous and vaginal contrast media. If the tumor is relatively small and clearly located within the confines of the cervix, no further images are obtained. If parametrial, forniceal, and/or vaginal extension is suspected, the next and final stage consists of dynamic intravenous contrast-enhanced imaging and T2-weighted imaging after vaginal opacification.
We conclude that the use of intravaginal contrast material may improve the clinical value of MR imaging in the pretreatment work-up of patients suspected of having cervical carcinoma.
|
Footnotes |
|---|
Author contributions: Guarantor of integrity of entire study, L.V.H.; study concepts and design, L.V.H., D.V.; definition of intellectual content, L.V.H., D.V.; literature research, L.V.H., D.V.; clinical studies, all authors; data acquisition, L.V.H., D.V.; data analysis, L.V.H., D.V., R.O., U.I.; manuscript preparation, L.V.H.; manuscript editing, L.V.H., D.V., I.V.; manuscript review, R.O., U.I., I.V.
|
References |
|---|
|
TOPAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| RADIOLOGY | RADIOGRAPHICS | RSNA JOURNALS ONLINE |
