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Magnetic resonance imaging using “fat-saturation” technique is useful for diagnosing small endometrioma: a case report
FERTILITY AND STERILITY
Vol. 58, No.5, November 1992
Copyright () 1992 The American Fertility Society
Printed on acid-free paper in U.S.A.
Magnetic resonance imaging using "fat-saturation" technique is useful for diagnosing small endometrioma: a case report
Kentaro Takahashi, M.D., Ph.D.*t Saori Okada, M.D.* Manabu Kitao, M.D., Ph.D.* Kazuro Sugimura, M.D., Ph.D.:j: Shimane Medical University, /zumo, Japan
Endometriosis is still a complex disease. The understanding of its pathophysiology, role in infertility, diagnosis, and treatment are still evolving and changing. Endometriosis is a common cause of infertility (1). Diagnostic indications for endometriosis include history, bimanual and/or rectal examination, ultrasound (US), computed tomography (CT) scanning, laparoscopy, serologic assays, and so forth. Although US and CT scanning have most commonly been used for the noninvasive diagnosis of endometriosis, the clinical manifestations are often nonspecific. Magnetic resonance imaging (MRI) is more specific than other imaging techniques (2). Togashi et al. (3) have reported that MRI seems to be an acceptable diagnostic method for endometriosis. However, it is difficult to distinguish small endometrioma from adipose tissue by MRI. We have now employed a "fat-saturation" technique that can consistently differentiate hemorrhagic cyst from fat as follows: MRI was performed on a 1.5-T superconducting unit (Signa; GE Medical Systems, Milwaukee, WI). Both Tl-weighted (SE 500/15 [TR msec/TE msec» and T2-weighted (SE 2,400/80) images were obtained. Section thickness was 6 mm, with a 2-mm intersection gap. Inferior and superior saturation pulses were applied. These parameters were maintained as similar as possible between regular spinecho and fat-saturation technique. Fat saturation was achieved by application of a low-amplitude, longduration sinusoidal radio-frequency pulse at the freReceived May 26, 1992; revised and accepted July 16, 1992. * Department of Obstetrics and Gynecology. t Reprint requests: Kentaro Takahashi, M.D., Ph.D., Department of Obstetrics and Gynecology, Shimane Medical University, 89-1, Enya-cho, lzumo 693, Japan. :j: Department of Radiology. Vol. 58, No.5, November 1992
quency of lipid followed by a section-select gradient pulse to disperse the fat signal. The subsequent spinecho sequence was obtained with reception centered on the frequency of water. In this case report, we emphasize that MRI using fat-saturation technique is useful for diagnosing small endometrioma. CASE REPORT
A 46-year-old married Japanese woman presented with dysmenorrhea and abdominal distension. Bimanual examination was suggestive of bilateral ovarian cysts and myoma uteri. Laboratory data showed only abnormally high values of CA-125 (100 U/mL). Magnetic resonance images revealed a typical image of bilateral endometrial cysts with hyperintense signal on Tl-weighted image (Fig. lA) and hyperintense and hypointense signal with shading on T2-weighted image (Fig. IB). On transverse section, fat-saturation Tl-weighted image revealed only hyperintense signal of endometrioma and inhibited fat signal (Fig. lC). And fat-saturation Tl-weighted image clearly revealed endometrial implants as small as 3 mm on the myomatous mass (Fig. 2A). All foci revealed by fat-saturation Tlweighted image completely corresponded with postoperative histologic specimen (Fig. 2B). DISCUSSION
Although laparoscopy is the best all inclusive method for diagnosing, staging, and managing endometriosis, US and CT scanning have been proposed as imaging modalities in the diagnosis of endometriosis (4,5). However, these imaging modalities often lacked specificity. Recently, MRI has been advocated as the Takahashi et al.
Communications-in-brief
1063
imaging modality of choice in evaluating endometrioma (3, 6), but limitations of current MRI resolution in detecting small implants have been pointed out (2, 6). Furthermore, a contrast between the endometrial implants and adipose tissue that surrounds normal organs and serosa of the pelvis may be insufficient for clear depiction ofthe implant (2). In the method, fatsaturation Tl-weighted image, the adipose tissue shows low signal intensity, and only endometrial implants show high signal intensity. As the contrast becomes more clear between the endometrial implants and normal organs, small endometrial implants of 2 to 3 mm can be discriminated. In this case, although small implants were not visible on Tl-weighted image and T2-weighted image, these foci could be detected on fat-saturation Tl-weighted image. We suggest that the fat-saturation image will improve the sensitivity and specificity of MRI for diagnosing endometriosis. Although the fat-saturation technique may not replace laparoscopy for the diagnosis and management of endometriosis' it seems to be an acceptable diagnostic technique because it can detect small implants like blueberry spots. In addition, MRI is far safer and more cost-effective than laparoscopy.
Figure 2 (A), Endometrial implants on myomatous mass (fatsaturation T1-weighted image). Three endometrial implants as small as 3 mm (arrows) are demonstrated on myomatous mass. (B), Postoperative specimen reveals bilateral endometriomas (large arrows) and small endometrial implants (small arrows). M = myomatous mass.
SUMMARY
Preoperative MRI using fat-saturation technique was performed in a patient with endometriosis. Endometrial implants as small as 3 mm were accurately diagnosed by MRI. The fat-saturation technique is useful for diagnosing small endometrioma. Key Words: Magnetic resonance imaging, fatsaturation, endometriosis. REFERENCES
Figure 1 Endometrial cysts of bilateral ovaries. (A), T1weighted image (SE 500/15) shows the content of endometrioma (E) to be of high signal intensity. (B), T2-weighted image (SE 2,400/80) shows the content of left endometrioma (E) to be of heterogenous signal intensity (shading). (C), Fat-saturation T1weighted image shows the content of endometrioma (E) to be of high signal intensity. Endometriomas are clearly separated from other organs. U = uterus. 1064
Takahashi et al.
Communications-in-brief
1. Abu-Musa A, Takahashi K, Nagata H, Kitao M. A clinical and statistical study on endometriosis. Jpn J Fertil Steril 1992;37:41-3. 2. Arrive L, Hricak H, Martin MC. Pelvic endometriosis: MR imaging. Radiology 1989;171:687-92. 3. Togashi K, Nishimura K, Kimura I, Tsuda Y, Yamashita K, Shibata T, et al. Endometrial cysts: diagnosis with MR imaging. Radiology 1991;180:73-8. 4. Friedman H, Vogelzang RL, Mendelson EB, Neiman HL, Cohen M. Endometriosis detection by US with laparoscopic correlation. Radiology 1985;157:217-20. 5. Fishman EK, Scatarige JC, Saksouk FA, Rosenshein NB, Siegelman SS. Computed tomography of endometriosis. J Comput Assist Tomogr 1983;7:257-64. 6. Nishimura K, Togashi K, Itoh K, Fujisawa I, Noma S, Kawamura Y, et al. Endometrial cysts of the ovary: MR imaging. Radiology 1987;162:315-8.
Fertility and Sterility
Vol. 58, No.5, November 1992
Copyright () 1992 The American Fertility Society
Printed on acid-free paper in U.S.A.
Magnetic resonance imaging using "fat-saturation" technique is useful for diagnosing small endometrioma: a case report
Kentaro Takahashi, M.D., Ph.D.*t Saori Okada, M.D.* Manabu Kitao, M.D., Ph.D.* Kazuro Sugimura, M.D., Ph.D.:j: Shimane Medical University, /zumo, Japan
Endometriosis is still a complex disease. The understanding of its pathophysiology, role in infertility, diagnosis, and treatment are still evolving and changing. Endometriosis is a common cause of infertility (1). Diagnostic indications for endometriosis include history, bimanual and/or rectal examination, ultrasound (US), computed tomography (CT) scanning, laparoscopy, serologic assays, and so forth. Although US and CT scanning have most commonly been used for the noninvasive diagnosis of endometriosis, the clinical manifestations are often nonspecific. Magnetic resonance imaging (MRI) is more specific than other imaging techniques (2). Togashi et al. (3) have reported that MRI seems to be an acceptable diagnostic method for endometriosis. However, it is difficult to distinguish small endometrioma from adipose tissue by MRI. We have now employed a "fat-saturation" technique that can consistently differentiate hemorrhagic cyst from fat as follows: MRI was performed on a 1.5-T superconducting unit (Signa; GE Medical Systems, Milwaukee, WI). Both Tl-weighted (SE 500/15 [TR msec/TE msec» and T2-weighted (SE 2,400/80) images were obtained. Section thickness was 6 mm, with a 2-mm intersection gap. Inferior and superior saturation pulses were applied. These parameters were maintained as similar as possible between regular spinecho and fat-saturation technique. Fat saturation was achieved by application of a low-amplitude, longduration sinusoidal radio-frequency pulse at the freReceived May 26, 1992; revised and accepted July 16, 1992. * Department of Obstetrics and Gynecology. t Reprint requests: Kentaro Takahashi, M.D., Ph.D., Department of Obstetrics and Gynecology, Shimane Medical University, 89-1, Enya-cho, lzumo 693, Japan. :j: Department of Radiology. Vol. 58, No.5, November 1992
quency of lipid followed by a section-select gradient pulse to disperse the fat signal. The subsequent spinecho sequence was obtained with reception centered on the frequency of water. In this case report, we emphasize that MRI using fat-saturation technique is useful for diagnosing small endometrioma. CASE REPORT
A 46-year-old married Japanese woman presented with dysmenorrhea and abdominal distension. Bimanual examination was suggestive of bilateral ovarian cysts and myoma uteri. Laboratory data showed only abnormally high values of CA-125 (100 U/mL). Magnetic resonance images revealed a typical image of bilateral endometrial cysts with hyperintense signal on Tl-weighted image (Fig. lA) and hyperintense and hypointense signal with shading on T2-weighted image (Fig. IB). On transverse section, fat-saturation Tl-weighted image revealed only hyperintense signal of endometrioma and inhibited fat signal (Fig. lC). And fat-saturation Tl-weighted image clearly revealed endometrial implants as small as 3 mm on the myomatous mass (Fig. 2A). All foci revealed by fat-saturation Tlweighted image completely corresponded with postoperative histologic specimen (Fig. 2B). DISCUSSION
Although laparoscopy is the best all inclusive method for diagnosing, staging, and managing endometriosis, US and CT scanning have been proposed as imaging modalities in the diagnosis of endometriosis (4,5). However, these imaging modalities often lacked specificity. Recently, MRI has been advocated as the Takahashi et al.
Communications-in-brief
1063
imaging modality of choice in evaluating endometrioma (3, 6), but limitations of current MRI resolution in detecting small implants have been pointed out (2, 6). Furthermore, a contrast between the endometrial implants and adipose tissue that surrounds normal organs and serosa of the pelvis may be insufficient for clear depiction ofthe implant (2). In the method, fatsaturation Tl-weighted image, the adipose tissue shows low signal intensity, and only endometrial implants show high signal intensity. As the contrast becomes more clear between the endometrial implants and normal organs, small endometrial implants of 2 to 3 mm can be discriminated. In this case, although small implants were not visible on Tl-weighted image and T2-weighted image, these foci could be detected on fat-saturation Tl-weighted image. We suggest that the fat-saturation image will improve the sensitivity and specificity of MRI for diagnosing endometriosis. Although the fat-saturation technique may not replace laparoscopy for the diagnosis and management of endometriosis' it seems to be an acceptable diagnostic technique because it can detect small implants like blueberry spots. In addition, MRI is far safer and more cost-effective than laparoscopy.
Figure 2 (A), Endometrial implants on myomatous mass (fatsaturation T1-weighted image). Three endometrial implants as small as 3 mm (arrows) are demonstrated on myomatous mass. (B), Postoperative specimen reveals bilateral endometriomas (large arrows) and small endometrial implants (small arrows). M = myomatous mass.
SUMMARY
Preoperative MRI using fat-saturation technique was performed in a patient with endometriosis. Endometrial implants as small as 3 mm were accurately diagnosed by MRI. The fat-saturation technique is useful for diagnosing small endometrioma. Key Words: Magnetic resonance imaging, fatsaturation, endometriosis. REFERENCES
Figure 1 Endometrial cysts of bilateral ovaries. (A), T1weighted image (SE 500/15) shows the content of endometrioma (E) to be of high signal intensity. (B), T2-weighted image (SE 2,400/80) shows the content of left endometrioma (E) to be of heterogenous signal intensity (shading). (C), Fat-saturation T1weighted image shows the content of endometrioma (E) to be of high signal intensity. Endometriomas are clearly separated from other organs. U = uterus. 1064
Takahashi et al.
Communications-in-brief
1. Abu-Musa A, Takahashi K, Nagata H, Kitao M. A clinical and statistical study on endometriosis. Jpn J Fertil Steril 1992;37:41-3. 2. Arrive L, Hricak H, Martin MC. Pelvic endometriosis: MR imaging. Radiology 1989;171:687-92. 3. Togashi K, Nishimura K, Kimura I, Tsuda Y, Yamashita K, Shibata T, et al. Endometrial cysts: diagnosis with MR imaging. Radiology 1991;180:73-8. 4. Friedman H, Vogelzang RL, Mendelson EB, Neiman HL, Cohen M. Endometriosis detection by US with laparoscopic correlation. Radiology 1985;157:217-20. 5. Fishman EK, Scatarige JC, Saksouk FA, Rosenshein NB, Siegelman SS. Computed tomography of endometriosis. J Comput Assist Tomogr 1983;7:257-64. 6. Nishimura K, Togashi K, Itoh K, Fujisawa I, Noma S, Kawamura Y, et al. Endometrial cysts of the ovary: MR imaging. Radiology 1987;162:315-8.
Fertility and Sterility