Magnetic resonance imaging in obstetrics and gynaecology

Magnetic resonance imaging in obstetrics and gynaecology

Eur. J. O&et. Elsevier HO Gynecol. Reprod. Biol., 24 (1987) 133-137 133 00437 European Association of Gynaecologists and Obstetricians 1st Meeti...

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Eur. J. O&et. Elsevier

HO

Gynecol. Reprod. Biol., 24 (1987) 133-137

133

00437

European

Association of Gynaecologists and Obstetricians 1st Meeting, London, 12-13 June 1986

Magnetic resonance imaging Magnetic resonance imaging in obstetrics and gynaecology E.M. Symonds,

M.C. Powell and B .S. Worthington, Nottingham, U.K.

Queen’s Medical Centre,

Magnetic resonance imaging (MRI) employs radio-frequency radiation in the presence of a powerful magnetic field to produce cross-sectional images of the body. The images are essentially distribution-density maps of protons and their related parameters. In Nottingham, magnetic resonance imaging is performed on a Picker 0.15 Tesla system based on a resistive magnet. Single-slice and multi-slice protocols are available in transverse axial, coronal or sagittal planes. By altering the pattern of radio-frequency waves applied to the pulse sequences, images can be produced weighted by Tt or T2 sequences. Ti sequences give useful pathological information, whereas T2 pulse sequences give good tissue differentiation and resolution. MRI pelvimetry In obstetric cases, the maternal bony pelvis has been demonstrated with good resolution. MRI has been examined as an alternative to X-ray pelvimetry. Cortical bone is represented by a low intensity line where a T2 weighted sequence is used. Using a four-slice, transverse axial protocol, the bispinous diameter can be measured and a good concordance with x-ray pelvimetry is obtained [l]. Imaging the cervix Magnetic resonance imaging offers a unique method for imaging the cervix and the complex changes it undergoes in pregnancy. There is a tri-laminar configuration of the cervix with a high-intensity signal in the cervical canal and a low-intensity band which parallels the cervical canal. These images allow precise definitions of placental placement. Placentography T2 weighted sequences demonstrated the placenta with a harsh white appearance and therefore allow clear identification of the portion of the placenta in relation to the cervix. In a study of 30 patients with ultrasound diagnosis of placenta praevia, over-estimation of the degree of placenta praevia was demonstrated in 7 cases [2] (Fig. 1).

0028-2243/87/$03.50

0 1987 Elsevier Science Publishers

B.V. (Biomedical

Division)

Fig. 1. Sagittal TE 80 ms).

section T2 weighted

sequence.

Marginal

placenta

praevia.

Trilaminar

cervix. (TR 2000 ms,

Disorders of placental tissue

The high-intensity signal seen with the placenta is also found in gestational trophoblastic disease. As the myometrium is also visible, it is possible to identify invasion of trophoblastic disease into the uterine wall [3]. Imaging the fetus

The present technique is not real-time and therefore imaging the fetus is difficult in the first and second trimesters because of fetal movement, which degrades the image. In the third trimester excellent views can be obtained of the fetal cerebral cortex, the fetal lung and the fetal heart. With inversion recovery sequences, the fetal cerebral cortex has a uniform low-intensity signal indicative of a long Tr time, which is characteristic of a high water content and minimal myelination [4]. Imaging of gynaecological tumours

Benign ovarian cysts exhibit a high signal intensity with T2 weighted sequences and a low signal intensity with Tr weighted sequences. Endometriosis exhibits a

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dense white appearance with Ti sequences. Imaging of ovarian adenocarcinomas can demonstrate early invasion of the capsule and mixed signal-intensity areas can be demonstrated on T2 weighted sequences. The characteristics of the primary tumour can be demonstrated in patients with recurrent disease [5]. Endometrial disease Endometrium has a high signal intensity in contrast to the low signal of the underlying myometrium. This high signal intensity is also seen in endometrial carcinoma and therefore makes it possible to measure the depth of invasion into the myometrium. Lymphatic involvement can also be demonstrated [6]. Cervical turnout3 Cervical carcinoma has a low signal intensity but there is some increase in signal intensity when the T2 weighting is lengthened. Invasion into the cervix and surrounding tissues can be demonstrated but it is difficult to demonstrate node involvement [7]. Unlike fibrosis, the signal intensity of a tumour increases with an increased T2 weighting, thereby enabling MRI to differentiate between recurrent tumours and fibrosis. In conclusion, MRI has unique qualities which have great potential value in obstetrics and gynaecology. It will not replace ultrasound in obstetrics but will be of help in those specific situations where ultrasound has known limitations. In gynaecology, it is of value in staging gynaecological tumours and in assessing endometrial changes in the normal cycle. References 1 Powell MC, Buckley JH, Worthington 2 3 4 5 6 7

BS, Symonds EM. Comparative study of conventional and MRI pelvimetry. Radiology 1985; 157(P): 83. Powell MC, Buckley JH, Symonds EM, Worthington BS. Magnetic resonance imaging (MRI) and hydatidiform mole. Br J Radio1 1986; 56: 561-564. Powell MC, Buckley JH, Symonds EM, Worthington BS. Magnetic resonance imaging (MRI) and placenta praevia. Am J Obstet Gynecol 1986; 154: 565-9. Powell MC, Worthington BS, Symonds EM. MRI, a new milestone in modem obstetric care. Diagnostic Imaging 1986; 8 No. 4: 86-91. Powell MC, Symonds EM, Worthington BS. The application of magnetic resonance imaging in gynaecology. Br J Hosp Med 1986; 356, 6: 393-403. Powell MC, Worthington BS, Symonds EM, Womack C. Magnetic resonance imaging (MRI) and Stage 1 endometrial adenocarcinoma. Br J Obstet Gynaecol 1986; 93: 353-360. Powell MC, Worthington BS, Wastie M, Buckley JH, Symonds EM. Magnetic resonance imaging (MRI): Its application to cervical cancer. Br J Obstet Gynaecol 1986; in the press.

NMR imaging in terms of human atomic pathology Rudolf

“Not

Klimek,

Copernicus University School of Medicine, OB/ GYN Institute, Cracow, Poland

to know the Second Law (of thermodynamics) is the same as not having read a work of Shakespeare” - C.P. Snow