(2008) 38–41

Clinical Imaging 32

F-18 FDG PET in detecting uterine leiomyoma

Chun-Yi Lina, Hueisch-Jy Dingb, Yen-Kung Chenc, Chiu-Shoung Liud,⁎,Cheng-Chieh Line, Chia-Hung Kaof,⁎

aDepartment of Nuclear Medicine, Show Chwan Memorial Hospital, Changhua, TaiwanbDepartment of Radiological Technology, I-Shou University, Kaohsiung, Taiwan

cDepartment of Nuclear Medicine and PET Center, Shin Kong Wu Ho-Su Memorial Hospital, Taipei, TaiwandDepartment of Community Medicine and Health Examination Center, China Medical University Hospital, Taichung, Taiwan

eDepartment of Family Medicine, China Medical University Hospital, Taichung, TaiwanfDepartment of Nuclear Medicine and PET Center, China Medical University Hospital, Taichung 404, Taiwan

Received 10 June 2007; accepted 11 July 2007

Abstract

Purpose: Uterine leiomyoma, benign tumors of the human uterus, are clinically apparent in about 25% of women and the most commonsolid pelvic tumors. The purpose of this study was to investigate the F-18 2-fluoro-2-deoxy-D-glucose (FDG) uptake in the uterineleiomyoma and assess the correlation between the intensity of FDG uptake in the uterine leiomyomas and menstrual cycle. Methods: A totalof 589 charts of healthy females examined by whole body FDG positron emission tomography (PET) for health screening examination werereviewed retrospectively. Twenty-two of them were suspected gynacecological tumors and referred to the department of gynacecology toascertain the nature of the causes. Final diagnosis as uterine leiomyomas were made based on uterine sonography, pelvic computedtomography, or pelvic magnetic resonance imaging scans. We defined FDG uptake as Grade I when FDG uptake was less than liver uptake,Grade II when FDG uptake was equal to liver uptake, and Grade III when FDG uptake was greater than liver uptake. The menstrual cycle wasrecorded on the day of performing FDG PET in premenopausal women. Results: The FDG uptake in the uterine region is Grade I in three ofthese 22 females (13.65%), Grade II in 16 (72.7%), and Grade III in 3 (13.65%). Conclusion: There is no significant correlation between theintensity of FDG uptake in the uterine leiomyomas and menstrual cycle (P=.914).© 2008 Elsevier Inc. All rights reserved.

Keywords: F-18 FDG PET; Uterine leiomyoma; Menstrual cycle

1. Introduction

Uterine leiomyomas are clinically apparent in about25% of women and the most common solid pelvic tumors.They are benign tumors that arise from the overgrowth ofsmooth muscle and connective tissue in the uterus. A

⁎ Corresponding authors. C.-S. Liu is to be contacted at Department ofCommunity Medicine and Health Examination Center, China MedicalUniversity Hospital, No. 2, Yuh-Der Road, Taichung 404, Taiwan. C.-H.Kao, Department of Nuclear Medicine and PET Center, China MedicalUniversity Hospital, No. 2, Yuh-Der Road, Taichung 404, Taiwan. Tel.:+886 4 22052121x3475; fax: +886 4 22070675.

E-mail address: d10040@www.cmuh.org.tw (C.-H. Kao).

0899-7071/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved.doi:10.1016/j.clinimag.2007.07.006

genetic predisposition exists. Histologically, a monoclonalproliferation of smooth muscle cells occurs [1–3]. Rarely,uterine leiomyoma may undergo malignant degeneration tobecome a sarcoma. The incidence of malignant degenera-tion is less than 1.0% and has been estimated to be as lowas 0.2%. The treatment of symptomatic uterine fibroidsranges from conservative medical management of symp-toms to hysterectomy.

F-18 2-fluoro-2-deoxy-D-glucose (FDG) is the mostcommonly used radiopharmaceutical for PET studies inoncology. The tracer is a substrate of energy metabolism;therefore, an increased FDG uptake is not limited tomalignant tissues alone [4–6]. In addition to the abnormalFDG uptake associated with malignant tumors, benign

Fig. 1. A 46-year-old female with Grade I FDG uptake in the uterine region.

39C.-Y. Lin et al. / Clinical Imaging 32 (2008) 38–41

tumors are the common causes of pitfalls of FDG PET. Goodknowledge of physical FDG uptake in the healthy populationis of great importance for the correct interpretation of FDGPET images of pathological processes.

The aim of the study is to investigate the FDG uptake inthe uterine leiomyoma and assess the correlation between theintensity of FDG uptake in the uterine leiomyomas andmenstrual cycle.

2. Material and methods

A total of 589 charts of healthy females, referred from thedepartment of family medicine, examined by whole bodyFDG PET for health screening examination from June 2002to December 2005, were reviewed retrospectively. Twenty-

Fig. 2. A 62-year-old female with Grade I

two of them were suspected gynacecological tumors due toincreased FDG uptake in the uterine region. Then they werereferred to the department of gynacecology to ascertain thenature of the causes. Final diagnosis as uterine leiomyomaswere made based on uterine sonography pelvic computedtomography, or pelvic magnetic resonance imaging scans[7]. Five of them were menopausal and seventeen of themwere premenopausal. The menstrual cycle was recorded onthe day of performing FDG PET in premenopausal women.

All patients fasted for at least 4 h before the examination.Whole body PET images were acquired on a GE AdvanceNXi scanner (35 image planes, 4.30 mm/slice, 15 cm axialfield of view) 40 min to 1 h after the intravenous injection of370 MBq (10 mCi) of F-18 FDG. Emission PET images ofthe neck, chest, abdomen and pelvis were acquired in the 2Dmode 4 min per bed position, followed by transmission scans

I FDG uptake in the uterine region.

Fig. 3. A 45-year-old female with Grade III FDG uptake in the uterine region.

40 C.-Y. Lin et al. / Clinical Imaging 32 (2008) 38–41

at selected sites. Images were reconstructed using vendor-provided software and formatted into transaxial, coronal andsagittal image sets. We defined FDG uptake was Grade Iwhen FDG uptake was less than liver uptake, Grade II whenFDG uptake equal to liver uptake, and Grade III when FDGuptake greater than liver uptake.

The significance of correlation between the intensity ofFDG uptake in the uterine leiomyomas and menstrual cyclewas assessed using chi-square test. A P value lower than .05was regarded as statically significant.

3. Results

The FDG uptake in the uterine region is Grade I (Fig. 1) inthree of these 22 females (13.65%), Grade II (Fig. 2) in 16(72.7%), and Grade III (Fig. 3) in 3 (13.65%) (Table 1).

In the Grade I uptake group, one is menopausal, one is inovulatory phase, and one is in menstrual phase. In the GradeII uptake group, three are menopausal, four are in pro-liferative phase, three are in ovulatory phase, two are insecretary phase, and the others are in menstrual phase. In theGrade III uptake group, one is menopausal, one is inproliferate phase, and 1 is in ovulatory phase. There is no

Table 1Intensity of FDG uptake, number of menopausal females, and number ofcyclic phase in premenopausal females

FDGuptake intheuterus

No. ofmenopausalfemales

No. of premenopausal females

Menstrualphase

Proliferativephase

Ovulatoryphase

Secretoryphase

Grade I 1 1 0 1 0Grade II 3 4 4 3 2Grade III 1 0 1 1 0

significant association between intensity of FDG uptake inthe uterine leiomyoma and menstrual cycle (P=.914).

4. Discussion

During the past few years, many studies have demon-strated the effectiveness of FDG PET in the detection ofmalignancies. However, it has to be realized that F-18 FDGis not a specific tumor-seeking compound since somephysiological and even some benign tumoural conditionsmay determine FDG uptake. This situation can causemisinterpretation of a PET scan and, as a consequence,may lead to false positive reports, thus reducing the accuracyof the technique.

The normal menstrual cycle reflects the fine balancebetween the proliferate actions of estrogen and theantiestrogenic and secretory transforming actions of proges-terone [8–11]. The reason for the accumulation of FDG inuterine leiomyoma is not known. It may explained by theexistence of higher levels of growth factors, including basicfibroblast growth factor, transforming growth factor beta,granulocyte macrophage colony-stimulating factor andreceptors, and proliferation of smooth muscle cells inleiomatous uterus [12–16].

Only a few cases of FDG uptake in uterine leiomyomawere reported [17–20]. It has also been reported that normaluptake of FDG in the endometrium of premenopausalpatients varies cyclically, being increased at the ovulatoryand menstrual phase [21]. However, there is no significantcorrelation between intensity of FDG uptake in the uterineleiomyoma and menstrual cycle that can be identified in thisretrospective study. It seems that proliferate actions ofestrogen on uterine leiomyomas do not have significantinfluence on expression of metabolic grade. The FDG uptakein uterine leiomyomas in this study is mostly Grade II uptake

41C.-Y. Lin et al. / Clinical Imaging 32 (2008) 38–41

(72.7%), so we hypothesize that a large part of FDG-aviduterine leiomyomas are equal to hepatic radioactivity.

In conclusion, in patients who are suspected of havingmalignant gynecological tumors, increased FDG uptake inthe pelvis may be caused by uterine leiomyomas. Thus,clinical correlation is needed for the accurate interpretationof FDG PET findings in these patients. Most of FDG-aviduterine leiomyomas are Grade II uptake, and no significantcorrelation between the intensity of FDG uptake in theuterine leiomyomas and menstrual cycle is noted in thisretrospective study. However, uterine leiomyomas that arenon-FDG-avid are not included in this study. Thus, a largergroup of studies need to be undergone to assess that whatpercentage of uterine leiomyomas are non-FDG-avid.

References

[1] Buttram VJ, Reiter R. Uterine leiomyomata: etiology, symptomatol-ogy, and management. Fertil Steril 1981;36:433–45.

[2] Cramer S, Patel A. The frequency of uterine leiomyomas. Am J ClinPathol 1990;94:435–8.

[3] Leyendecker G, Kunz G. Endometriosis and adenomyosis. ZentralblGynakol 2005;127:288–94.

[4] Cook GJ, Wegner EA, Fogelman I. Pitfalls and artifacts in 18FDG PETand PET/CT oncologic imaging. Semin Nucl Med 2004;34:122–33.

[5] Cook GJ, Maisey MN, Fogelman I. Normal variants, artefacts andinterpretative pitfalls in PET imaging with 18-fluoro-2-deoxyglucoseand carbon-11 methionine. Eur J Nucl Med 1999;26:1363–78.

[6] Shreve PD, Anzai Y, Wahl RL. Pitfalls in oncologic diagnosis withFDG PET imaging: physiologic and benign variants. Radiographics1999;19:61–77.

[7] Sopers JT. Radiographic imaging in gynecologic oncology. Clin ObstetGynecol 2001;44:485–94.

[8] Hughes EC. The effect of enzymes upon metabolism, storage, andrelease of carbohydrates in normal and abnormal endometria. Cancer1976;38:487–502.

[9] Noci I, Borri P, Scarselli G, Chieffi O, Bucciantini S, Biagiotti R,Paglierani M, Moncini D, Taddei G. Morphological and functionalaspect of the endometrium of asymptomatic post-menopausal women:does the endometrium really age? Hum Reprod 1996;1:246–50.

[10] Levine D, Gosin B, Johnson LA. Change in endometrial thickness inpostmenopausal women undergoing hormone replacement therapy.Radiology 1995;97:603–8.

[11] Kubota R, Kubota K, Yamada S, Tada M, Ido T, Tamahashi N.Microautoradiographic study for the differentiation of intratumoralmacrophages, granulation tissues and cancer cells by the dynamicsof fluorine-18-fluorodeoxyglucose uptake. J Nucl Med 1994;5:104–12.

[12] Imai A, Matsunami K, Ohno T, Tamayaet T. Enhancement of growth-promoting activity in extract from uterine cancer by protein kinase C inhuman endometrial fibroblasts. Gynecol Obstet Invest 1992;33:109–13.

[13] Fenchel S, Grab D, Nuessle K, Kotzerke J, Rieber A, KreienbergR, Brambs HJ, Reske SN. Asymptomatic adnexal masses: cor-relation of FDG PET and histopathologic findings. Radiology2002;223:780–8.

[14] Gull I, Geva E, Lerner-Geva L, Lessing JB, Wolman I, Amit A.Anaerobic glycolysis. The metabolism of the preovulatory humanoocyte. Eur J Obstet Gynecol Reprod Biol 1999;85:225–8.

[15] Kol S, Ben-Shlomo I, Ruutiainen K, Ando M, Davies-Hill TM, RohanRM, Simpson IA, Adashi EY. The midcycle increase in ovarianglucose uptake is associated with enhanced expression of glucosetransporter 3. Possible role for interleukin-1, a putative intermediary inthe ovulatory process. J Clin Invest 1997;99:2274–83.

[16] Kubota R, Yamada S, Kubota K, Ishiwata K, Tamahashi N, Ido T.Intratumoral distribution of fluorine-18-fluorodeoxyglucose in vivo:high accumulation in macrophages and granulation tissues studied bymicroautoradiography. J Nucl Med 1992;33:1972–80.

[17] Kao CH. FDG uptake in a huge uterine myoma. Clin Nucl Med2003;28:249.

[18] Dose J, Bohuslavizki K, Huneke B, Lindner C, Janicke F. Detection ofintramural choriocarcinoma of the uterus with 18F-FDG-PET. A casereport. Clin Positron Imaging 2000;3:37–40.

[19] Ak I, Ozalp S, Yalcin OT, Zor E, Vardareli E. Uptake of 2-[18F]fluoro-2-deoxy-D-glucose in uterine leiomyoma: imaging of four patients bycoincidence positron emission tomography. Nucl Med Commun 2004;25:941–5.

[20] Maeda T, Tateishi U, Sasajima Y, Hasegawa T, Daisaki H, Arai Y,Sugimura K. Atypical polypoid adenomyoma of the uterus: appearanceon (18)F-FDG PET/MRI fused images. AJR Am J Roentgenol 2006;186:320–3.

[21] Kunz G, Noe M, Herbertz M, Leyendecker G. Uterine peristalsisduring the follicular phase of the menstrual cycle: effects of oestrogen,antioestrogen and oxytocin. Hum Reprod Update 1998;4:647–54.