mr findings of struma ovarii

6
MR findings of struma ovarii Jong Chul Kim*, Sung Soo Kim, Jin Yong Park Department of Diagnostic Radiology, Chungnam National University Hospital, 640 Dacesa-dong, Jung-ku, Taejeon 301-721, South Korea Received 20 September 1999; accepted 1 March 2000 Abstract This study was performed to characterize MR findings of struma ovarii. In 10 patients, T1- and fast spin echo T2-weighted MR images were obtained in the axial, coronal, and sagittal planes using 1.5 T MR units, and they were retrospectively evaluated for the site, size, components, signal intensity, and contrast enhancement. MR images showed a unilateral complex mass with a multilobulated surface and thickened septa, corresponding pathologically to thyroid follicles and the stroma. Cystic portions had variable signal intensities on T1- and T2-weighted images. The contents of cystic components showing low signal intensities both on T1- and T2-weighted images were viscid gelatinous materials (n = 4). Solid portions were relatively well-enhanced. In conclusion, struma ovarii has some characteristic MR appearance of a multilobulated complex mass with thickened septa, multiple cysts of variable signal intensities, and enhancing solid components. D 2000 Elsevier Science Inc. All rights reserved. Keywords: Struma ovarii; MR images; Multilobulated; Ovary neoplasms; Ovary; Cysts; Ovary; MR The mature cystic teratomas constitute the majority of ovarian germ cell tumors [1,2], and thyroid tissues are found in 5–15% of these tumors on pathologic examina- tions [2–4]. Struma ovarii is a rare ovarian tumor com- posed solely or predominantly of thyroid tissue or the tumor in which hyperthyroidism results from the ovarian thyroid tissue [1,2,5 – 8]. Pure struma ovarii with micro- scopic or macroscopic thyroid tissue constitutes 2% of all germ cell tumors of the ovary [4] and 2.7% of all ovarian teratomas [3]. Preoperative clinical or radiologic diagnosis of struma ovarii, however, is very difficult. There are limited numbers of radiologic reports of struma ovarii [2,4,7,9 –16], and the majority of these are case reports [2,7,11,13 –15]. Even though magnetic reso- nance (MR) imaging is known to be useful in the detection and characterization of adnexal masses, to our knowledge, there are only several reports concerning the MR findings of this rare tumor [4,7,11,16] The purpose of this study was to evaluate whether there were any characteristic imaging findings in struma ovarii through the retrospective analysis of MR findings. 1. Materials and methods During the recent 11 years, 10 cases of pathologically proven struma ovarii after salpingo-oophorectomy were retrospectively identified in our hospital and its affiliated hospitals by reviewing medical records. The age of the 10 patients ranged from 37 to 73 years (average, 51). Of the 10 patients, nine women complained of palpable lower abdominal masses, and one woman was admitted due to symptoms and signs of hyperthyroidism such as facial flushing, palpitation, etc. Thyroid function test after admission was positive in the latter patient. GE Signa 1.5 T MR unit (General Electric Medical Systems, Milwaukee, WI, USA) was used to obtain T1-weighted images (TR/TEeff 410–660/11–17 ms), fast spin echo T2-weighted images (TR/TE 3200–6000/85– 132 ms; echo train length = 8, 12) and gadolinium- enhanced T1-weighted images in the axial, coronal, and sagittal planes. Contrast-enhanced images were obtained after intravenous injection of gadopentetate dimeglumine (Magnevist, Schering, Berlin, Germany, 0.1 mmol/kg). In 3 of 10 patients, fat saturation techniques were performed to differentiate whether hyperintense areas in the tumors on T1-weighted images were due to hemorrhage, fat, and/ or fluid of high protein content. The sequence parameters were as follows: section thickness = 8–10 mm; field of * Corresponding author. Tel.: +82-42-220-7835; fax: +82-42-253-0061. E-mail address: [email protected] (J.C. Kim). 0899-7071/00/$ – see front matter D 2000 Elsevier Science Inc. All rights reserved. PII:S0899-7071(00)00158-3 Journal of Clinical Imaging 24 (2000) 28 – 33

Upload: jong-chul-kim

Post on 17-Sep-2016

219 views

Category:

Documents


0 download

TRANSCRIPT

MR findings of struma ovarii

Jong Chul Kim*, Sung Soo Kim, Jin Yong Park

Department of Diagnostic Radiology, Chungnam National University Hospital, 640 Dacesa-dong, Jung-ku, Taejeon 301-721, South Korea

Received 20 September 1999; accepted 1 March 2000

Abstract

This study was performed to characterize MR findings of struma ovarii. In 10 patients, T1- and fast spin echo T2-weighted MR images

were obtained in the axial, coronal, and sagittal planes using 1.5 T MR units, and they were retrospectively evaluated for the site, size,

components, signal intensity, and contrast enhancement. MR images showed a unilateral complex mass with a multilobulated surface and

thickened septa, corresponding pathologically to thyroid follicles and the stroma. Cystic portions had variable signal intensities on T1- and

T2-weighted images. The contents of cystic components showing low signal intensities both on T1- and T2-weighted images were viscid

gelatinous materials (n = 4). Solid portions were relatively well-enhanced. In conclusion, struma ovarii has some characteristic MR

appearance of a multilobulated complex mass with thickened septa, multiple cysts of variable signal intensities, and enhancing solid

components. D 2000 Elsevier Science Inc. All rights reserved.

Keywords: Struma ovarii; MR images; Multilobulated; Ovary neoplasms; Ovary; Cysts; Ovary; MR

The mature cystic teratomas constitute the majority of

ovarian germ cell tumors [1,2], and thyroid tissues are

found in 5±15% of these tumors on pathologic examina-

tions [2±4]. Struma ovarii is a rare ovarian tumor com-

posed solely or predominantly of thyroid tissue or the

tumor in which hyperthyroidism results from the ovarian

thyroid tissue [1,2,5±8]. Pure struma ovarii with micro-

scopic or macroscopic thyroid tissue constitutes 2% of all

germ cell tumors of the ovary [4] and 2.7% of all ovarian

teratomas [3]. Preoperative clinical or radiologic diagnosis

of struma ovarii, however, is very difficult.

There are limited numbers of radiologic reports of

struma ovarii [2,4,7,9±16], and the majority of these are

case reports [2,7,11,13±15]. Even though magnetic reso-

nance (MR) imaging is known to be useful in the detection

and characterization of adnexal masses, to our knowledge,

there are only several reports concerning the MR findings

of this rare tumor [4,7,11,16]

The purpose of this study was to evaluate whether there

were any characteristic imaging findings in struma ovarii

through the retrospective analysis of MR findings.

1. Materials and methods

During the recent 11 years, 10 cases of pathologically

proven struma ovarii after salpingo-oophorectomy were

retrospectively identified in our hospital and its affiliated

hospitals by reviewing medical records.

The age of the 10 patients ranged from 37 to 73 years

(average, 51). Of the 10 patients, nine women complained

of palpable lower abdominal masses, and one woman was

admitted due to symptoms and signs of hyperthyroidism

such as facial flushing, palpitation, etc. Thyroid function

test after admission was positive in the latter patient.

GE Signa 1.5 T MR unit (General Electric Medical

Systems, Milwaukee, WI, USA) was used to obtain

T1-weighted images (TR/TEeff 410±660/11±17 ms), fast

spin echo T2-weighted images (TR/TE 3200±6000/85±

132 ms; echo train length = 8, 12) and gadolinium-

enhanced T1-weighted images in the axial, coronal, and

sagittal planes. Contrast-enhanced images were obtained

after intravenous injection of gadopentetate dimeglumine

(Magnevist, Schering, Berlin, Germany, 0.1 mmol/kg). In

3 of 10 patients, fat saturation techniques were performed

to differentiate whether hyperintense areas in the tumors

on T1-weighted images were due to hemorrhage, fat, and/

or fluid of high protein content. The sequence parameters

were as follows: section thickness = 8±10 mm; field of* Corresponding author. Tel.: +82-42-220-7835; fax: +82-42-253-0061.

E-mail address: [email protected] (J.C. Kim).

0899-7071/00/$ ± see front matter D 2000 Elsevier Science Inc. All rights reserved.

PII: S0 8 9 9 - 7 0 7 1 ( 0 0 ) 0 0 1 58 - 3

Journal of Clinical Imaging 24 (2000) 28± 33

view = 26 � 26 cm; matrix = 512 � 224; numbers of

excitation = 1.5±4.

MR findings of struma ovarii were retrospectively

evaluated for the site, size, components (cystic, solid,

mixed, or complex), signal intensity, and absence or degree

of contrast enhancement, by three experienced radiologists

who reached a consensus on the analysis. These radiologic

findings were compared with pathologic ones.

2. Results

MR findings of our 10 patients were summarized in

Table 1.

All tumors in 10 patients were unilateral (right, five; left,

five), and the maximal tumor size ranged from 5 to 16 cm

(mean, 9.9 cm). In one patient, the symptoms and signs of

hyperthyroidism such as facial flushing, palpitation, etc.,

subsided after the ipsilateral salpingo-oophorectomy.

MR images showed a unilateral complex mass of

multiple cysts and some solid components with a multi-

lobulated surface and thickened septa in all patients. In 2

of 10 patients, most of struma ovarii appeared to be

consisted of only multiseptated cysts. The maximal thick-

ness of the septa was 3±10 mm in each patient on

contrast-enhanced T1-weighted image, and that of the

peripheral cyst wall was 7±15 mm. The cystic portions

of the tumors were variable in size (range of maximal

diameter, 0.5±6.5 cm), shape (round, oval, semilunar,

irregular, triangular, lobulated, etc.), numbers (range 3±

40), and location (peripheral, central, eccentric, even dis-

tribution). Their cystic portions showed variable signal

intensities without contrast enhancement on T1-weighted

images, and were mainly high with different signal in-

tensities of fast spin echo T2-weighted images (Figs. 1±3).

In 4 of 10 tumors, some cystic portions of the tumors,

either scattered (n = 3) (Fig. 2) or peripherally located (n =

1) (Fig. 3), were hyperintense both on T1- and T2-

weighted images. Fat saturated MR images in three of

these four patients revealed the non-fatty nature of the

cystic contents of the masses, because the hyperintense

areas on T1-weighted images were not suppressed. These

hyperintense cystic areas on T1-weighted images were

pathologically proved to be due to hemorrhagic products

(n = 1) and viscous colloid components (n = 3) (Figs. 2

and 3). There are four cases with some cystic components

showing low signal intensities both on T1- and fast spin

echo T2-weighted images (Figs. 1±3). The contents of

these cysts were also viscid gelatinous materials. Both the

viscid fluid and viscid gelatinous materials were histolo-

gically eosinophilic, similar to the colloid in the normal

thyroid follicles.

Table 1

MR findings of 10 cases of pathologically proven struma ovarii

T1WI T2WI Gd-T1WI

No. Age Site Size (cm) Cystic Solid Cystic Solid Cystic Solid

(1) 73 R 10 � 9 � 7 iso iso hyper sl. hyper UE ME

hypo hypo

(2) 42 R 7 � 6 � 5 iso iso hyper sl. hyper UE IE

hypo hyper

(3) 65 L 10 � 8 � 5 iso iso hyper sl. hyper UE IE

hyper hyper iso

hypo hypo

(4) 39 L 8 � 10 � 7 hyper iso UE ME

iso hypo

hyper hyper

(5) 57 R 12 � 11 � 9 hypo iso hyper iso UE IE

iso hypo

hyper hyper

(6) 37 L 7 � 10 � 10 hypo iso hypo iso UE ME

iso hyper

(7) 53 L 16 � 13 � 9 hypo iso hyper iso UE IE

iso sl. hyper hyper

(8) 40 R 5 � 4 � 2 hypo iso hyper iso UE IE

iso hyper

hyper hyper

(9) 63 L 8 � 5 � 3 hyper iso hyper sl. hyper UE IE

hypo hyper

(10) 45 R 6 � 11 � 9 hyper iso hyper iso UE IE

hypo hypo

Note: MR, magnetic resonance; T1WI, T1-weighted image; T2WI, T2-weighted image; Gd-T1WI, gadolinium-DTPA-enhanced T1-weighted image with

or without fat saturation; hyper, hyperintense; hypo, hypointense; iso, isointense with surrounding pelvic muscles; sl., slightly; UE, unenhanced; IE, intense

contrast enhancement; ME, moderate enhancement.

J.C. Kim et al. / Journal of Clinical Imaging 24 (2000) 28±33 29

Solid portions or septa of the tumors were isointense

relative to the adjacent pelvic muscles on T1-weighted

images, iso- or hyperintense on T2-weighted images, and

intensely (n = 7) or moderately (n = 3) enhanced on

postcontrast T1-weighted images (Figs. 1±3). Most of

these solid portions were scattered throughout the tumors

or abutted on the cystic areas with variable size (0.7±5

cm) and irregular shapes.

The surgical specimens revealed that the 10 tumors

were complex multilobulated masses with multiple cysts,

thickened septa, and solid portions. Adult thyroid tissues

were found in all patients on microscopy. Thyroid follicles

were filled with high proteinaceous gelatinous fluid of

eosinophilic colloid, and the solid portions of the tumors

consisted of the thyroid tissues composed of multiple

follicles and stroma containing abundant blood vessels

and fibrous tissue (Fig. 1d). There were no ascites and

no evidence of malignancy in the pelvic lymphadenopathy.

3. Discussion

Ovarian teratomas are classified as the mature, imma-

ture, and monodermal or highly specialized ones. Struma

ovarii is one of the monodermal or highly specialized type,

together with a carcinoid [17]. This tumor is uncommon,

constituting only 2.7% of all ovarian teratomas [3,18,19]

and only 0.3% of all ovarian tumors [7,18]. It has been

reported that about 85% of patients with struma ovarii has

been present before menopause [2,20,21]. In our study, the

age range of 10 patients including four postmenopausal

women were 37±73 years (average, 51). This age range in

struma ovarii patients was slightly higher than the reported

prevalent age range of 20±44 years in cystic teratomas

[22,23]. In our study, all tumors occurred unilaterally,

similar to the other reports [24].

Clinically, most cases of struma ovarii are silent or

present with nonspecific symptoms similar to the other

Fig. 1. Sagittal pelvic MR images of right struma ovarii in a 73-year-old woman (No. 1). (a) T1-weighted image reveals a large complex pelvic mass (black

arrows). The signal intensity of the mass is similar to that of the uterus (u), and the mass also contains some hypointense areas (white arrowheads). (b) Fast spin

echo T2-weighted image demonstrates a multiloculated tumor of hyperintense cystic areas with some isointense solid portions and septa (black solid arrows),

and hypointense uterine myomas (black open arrows). (c) Gadolinium-enhanced sagittal T1-weighted image reveals non-enhancing cystic contents of variable

signal intensities with moderately enhancing solid portions and septa (white arrowheads) of the tumor. (d) Pathologic microscopy revealed that the mass was

composed of thyroid tissue containing multiple follicles filled with eosinophilic viscous colloid.

J.C. Kim et al. / Journal of Clinical Imaging 24 (2000) 28±3330

benign ovarian tumors. However, if the mature thyroid

tissue in this tumor is hyperfunctioning, symptoms and

signs of hyperthyroidism may be present [2,7,25]. In one

of our 10 patients, the symptoms and signs of hyperthyr-

oidism due to struma ovarii subsided dramatically after

surgical removal of struma ovarii. In a small number of

cases, ascites and pleural effusion may be found (so-

called pseudo-Meigs' syndrome) [3,4], but our patients

had no evidence of ascites either on MR imaging or

on pathology.

Most of struma ovarii are benign and can be treated

by surgical resection of the diseased ovary with or with-

out excision of the ipsilateral fallopian tube. Malignant

foci, however, were reported to be found in 5±10% of

struma ovarii [2,24]. In our study, all patients were

treated with salpingo-oophorectomy and total abdominal

hysterectomy. Fortunately, there have been no clinical or

pathological evidences of malignancy or recurrence dur-

ing the postoperative follow-up period (from 7 months to

12 years).

There are not many radiologic reports of struma ovarii

[2,4,7,9 ± 16], and most of these are case reports

[2,7,11,13±15]. In addition, to our knowledge, there are

very few reports describing the MR findings of struma

ovarii [4,7,11,16]. Matsumoto et al. [7] reported one case

of struma ovarii with CT and MR imaging, Dohke et al.

[11] reported two cases, Yamashita et al. [4] described

MR appearances of six tumors, and Joja et al. [16]

reported the appearance on MR images in 12 cases of

struma ovarii.

In our study, similar to other reports [4,7,11,16,25±28],

all tumors were complex multilobulated masses with thick-

ened septa both on MR imaging and on pathology. On

pathology, most of their cystic portions were filled with high

proteinaceous gelatinous fluid of eosinophilic colloid, and

their solid portions consisted of the thyroid tissues and

stroma containing abundant blood vessels and fibrous

tissue. So, multilocularity of struma ovarii may be consid-

ered to be due to multiple large thyroid follicles. The

multiple cysts of struma ovarii may have variable signal

Fig. 2. Axial pelvic MR images of left struma ovarii in a 65-year-old woman (No. 3). (a) T1-weighted image reveals a large complex pelvic mass of variable

signal intensities behind the urinary bladder. (b) Fat saturated T1-weighted image reveals that the hyperintense areas on T1-weighted image are not fatty tissues,

because those areas are not suppressed as subcutaneous or pelvic fat. (c) Fast spin echo T2-weighted image demonstrates a complex multiloculated mass

with hyper- or hypointense cystic areas and isointense solid portions (arrows) relative to the uterine muscle layer (u). (d) Fat saturated gadolinium-enhanced

T1-weighted image shows non-enhancing cystic contents and intensely enhancing solid portions and septa of the tumor.

J.C. Kim et al. / Journal of Clinical Imaging 24 (2000) 28±33 31

intensities depending on the amount, density, or concentra-

tion of viscous proteinaceous fluid in thyroid follicles. In 4

of our 10 cases, hyperintense areas on T1-weighted images

without chemical shift artefact on T2-weighted images were

pathologically confirmed to be due to hemorrhage (n = 1)

and colloid (n = 3) on pathology. The contents of cystic

components showing low signal intensities both on T1- and

fast spin echo T2-weighted images in four cases were also

viscid gelatinous materials. Dillon et al. [29] and Som et al.

[30] reported that viscid fluid showed low signal intensity

on T2-weighted images and high signal intensity on

T1-weighted images. But they also said that as the vicosity

of the fluid increases, the signal intensity on T2-weighted

images decreased and became a signal void and that on T1-

weighted images also decreased. Amr and Hassan [28]

reported that struma ovarii contained thick gelatinous ma-

terial in the tumors. Therefore, the characteristic very low

signal intensities on both T1- and T2-weighted images may

reflect very viscid material such as triiodo thyronine, thyr-

oxine, thyroglobulin, thyroid hormones, etc., within the

tumor [16].

Solid portions or septa of struma ovarii were isointense

relative to the adjacent muscles on T1-weighted images,

iso- or hyperintense on T2-weighted images, and intensely

enhanced on postcontract T1-weighted images. The strong

enhancement of these solid portions can be explained due

to the thyroid tissues and stroma of abundant blood vessels

and fibrous tissue.

MR findings of such complex adnexal masses are found

not only in struma ovarii but also in many other adnexal

masses. These include cystadenoma, cystadenocarcinoma,

endometrioma, mature cystic teratoma, ovarian metastasis,

or tuboovarian abscess [4,10]. Intense or moderate enhance-

ment of solid portions of the tumor may increase the

possibility of struma ovarii rather than the mucinous or

serous cystadenoma, cystic teratoma without fatty tissue, or

ovarian metastasis. Clinical findings of fever, tenderness,

leukocytosis, etc., due to inflammation will favor the

diagnosis of the tuboovarian abscess. Some hyperintense

areas of cystic portions of the tumor which cannot be

suppressed by fat saturation technique on T1-weighted

images and which do not have chemical shift artefact on

Fig. 3. Pelvic MR images of right struma ovarii in a 57-year-old woman (No. 5). (a) Sagittal T1-weighted image demonstrates a large multiloculated mainly

cystic pelvic mass of variable signal intensities. (b) Fast spin echo axial T2-weighted image demonstrates that the mass is composed of hyperintense fluid and

isointense solid portions and septa (arrows) relative to the pelvic muscles. (c) Gadolinium-enhanced axial T1-weighted image shows non-enhancing cystic

contents and intensely enhancing solid portions and septa (white arrowheads) of the tumor.

J.C. Kim et al. / Journal of Clinical Imaging 24 (2000) 28±3332

T2-weighted images may exclude the diagnosis of the pure

teratoma with fatty tissue. Unilaterality may increase the

probability of struma ovarii compared with metastatic tu-

mors to the ovary. Shading artefact due to variable hemor-

rhagic products of different stage may favor the diagnosis of

endometrioma. The complex mass associated with hy-

perthyroidism, ascites, and/or pleural effusion may increase

the possibility of struma ovarii.

Our study has a critical limitation that the sample size is

too small to be statistically significant.

In conclusion, when MR imaging shows a unilateral

complex adnexal mass with a multilobulated surface and

thickened septa and when this mass is composed of multiple

cysts of variable signal intensities and intensely or mode-

rately enhancing solid components, struma ovarii should be

included in the differential diagnosis with high probability.

References

[1] Fox H, Langley FA. Tumors of the Ovary. London: Heinemann, 1976.

[2] March DE, Desai AG, Park CH, Hendricks PJ, Davis PS. Struma

ovarii: hyperthyroidism in a postmenopausal woman. J Nucl Med

1988;29:263± 5.

[3] Talerman A. Germ cell tumors of the ovary. In: Kurman RJ, editor.

Blaustein's Pathology of the Female Genital Tract, 3rd edn. New

York, NY: Springer-Verlag, 1987. pp. 687± 721.

[4] Yamashita Y, Hatanaka Y, Takahashi M, Miyazaki K, Okamura H.

Struma ovarii: MR appearances. Abdom Imaging 1997;22:100±2.

[5] Thomas RD, Batty VB. Metastatic malignant struma ovarii. Clin Nucl

Med 1992;17:577± 8.

[6] Radecki PD, McKrisky PJ. Female pelvis: neoplastic and nonneoplas-

tic masses. In: Friedman AC, Radecki PD, Lev-Toaff AS, Hilpert PL,

editors. Clinical Pelvic Imaging. St. Louis: C.V. Mosby, 1990. pp.

197± 204.

[7] Matsumoto F, Yoshioka H, Hamada T, Ishida O, Noda K. Struma ovarii:

CT and MR findings. J Comput Assist Tomogr 1990;14(2):310 ±12.

[8] Ayhan A, Yanik F, Tuncer R, Tuncer ZS, Ruacan S. Struma ovarii. Int

J Gynaecol Obstet 1993;42:143± 6.

[9] Kozuka Y, Tamaishi Y, Yamawaki T, Sugiyama Y. A case of struma

carcinoid. Obstet Gynecol 1983;50:1991± 4.

[10] Hahn ST, Park SH, Bahk YW, Chung SK. Struma ovarii simulating a

teratodermoid cyst: computed tomographic findings in one case. Radi-

ology 1991;31:89± 91.

[11] Dohke M, Watanabe Y, Takahashi A, et al. Struma ovarii: MR find-

ings. J Comput Assist Tomogr 1997;21(2):265± 7.

[12] Zale Y, Caspi B, Tepper R. Doppler flow characteristics of dermoid

cysts: unique appearance of struma ovarii. J Ultrasound Med

1997;16(5):355±8.

[13] Thomas RD, Batty VB. Metastatic malignant struma ovarii: two case

reports. Clin Nucl Med 1992;17:577± 8.

[14] Lieberman G, Buscombe JR, Hilson AJ, Thakrar D, MacLean A. The

detection of struma ovarii in two patients by radioimmunoscintigra-

phy. Am J Obstet Gynecol 1998;179:262± 3.

[15] Bayot MR, Chopra IJ. Coexistence of struma ovarii and Graves' dis-

ease. Thyroid 1995;5:469±71.

[16] Joja I, Asakawa T, Mitsumori A, et al. Struma ovarii: appearance on

MR images. Abdom Imaging 1998;23:652± 6.

[17] Cotran RS, Kumar V, Robbins SL. Female genital tract. In: Cotran RS,

Kumar V, Robbins SL, editors. Robbins Pathologic Basis of Disease,

4th edn. Philadelphia: Saunders, 1989. pp. 1127±80.

[18] Stevens SK. The adnexa. In: Higgins CB, Hricak H, Helms CA,

editors. Magnetic Resonance Imaging of the Body, 2nd edn. New

York: Raven Press, 1992. pp. 875±7.

[19] Gusberg SB, Danforth DN. Clinical significance of struma ovarii. Am

J Obstet Gynecol 1944;48:532± 42.

[20] Sciarra JJ. Benign neoplasm of the ovary. In: Bird CC, McElin TW,

Victor TA, editors. Gynecology and Obstetrics (Vol. 12). Philadelphia:

JB Lippincott, 1988.

[21] Fox JF, Clement KW. Functioning struma ovarii. Ann Surg 1951;133:

253± 4.

[22] Griffiths CT, Berkowitz RS. The ovary. In: Kistner RW, editor. Gy-

necology: Principles and Practice. St. Louis: Mosby year book, 1986.

pp. 173± 5.

[23] Scoutt LM, McCarthy SM. Female pelvis. In: Stark DD, Bradley WG,

editors. Magnetic Resonance Imaging, 2nd edn. St. Louis: Mosby year

book, 1992. pp. 1973±6.

[24] Marcus CC, Marcus SL. Struma ovarii: a report of 7 cases and a

review of the subject. Am J Obstet Gynecol 1961;81:752± 61.

[25] Szyfelbein WM, Young RH, Scully RE. Cystic struma ovarii. A fre-

quently unrecognized tumor. A report of 20 cases. Am J Surg Pathol

1994;18:785±8.

[26] Smith FG. Pathology and physiology of struma ovarii. Arch Surg

1946;53:603±26.

[27] Szyfelbein WM, Young RH, Scully RE. Struma ovarii simulating

ovarian tumors of other types. A report of 30 cases. Am J Surg

Pathol 1995;19:21±9.

[28] Amr SS, Hassan AA. Struma ovarii with pseudo-Meigs' syndrome:

report of a case and review of the literature. Eur J Obstet Gynecol

Reprod Biol 1994;55:205± 8.

[29] Dillon WP, Som PM, Fullerton GD. Hypointense MR signal in chroni-

cally inspissated sinonasal secretions. Radiology 1990;51:396± 8.

[30] Som PM, Dillon WP, Fullerton GD, Zimmerman RA, Rajagopalan

Z, Maron Z. Chronically obstructed sinonasal secretions on T1 and

T2 shortening. Radiology 1989;172:515± 20.

J.C. Kim et al. / Journal of Clinical Imaging 24 (2000) 28±33 33