Standardized uptake values of uterine leiomyoma with 18F-FDG PET/CT: variation with age, size, degeneration, and contrast enhancement on MRI

Molecular Imaging in Gynecology: Beyond Cancer

Gynecological pathologies account for approximately 4.5% of the overall global disease burden. Although cancers of the female reproductive system have understandably been the focus of a great deal of research, benign gynecological conditions-such as endometriosis, polycystic ovary syndrome, and uterine fibroids-have remained stubbornly understudied despite their astonishing ubiquity and grave morbidity. This historical inattention has frequently become manifested in flawed diagnostic and treatment paradigms. Molecular imaging could be instrumental in improving patient care on both fronts. In this Focus on Molecular Imaging review, we will examine recent advances in the use of PET, SPECT, MRI, and fluorescence imaging for the diagnosis and management of benign gynecological conditions, with particular emphasis on recent clinical reports, areas of need, and opportunities for growth.

Current Concepts in the Imaging of Uterine Sarcomas

Uterine sarcomas are a group of rare uterine tumors comprised of multiple subtypes with different histologic characteristics, prognoses, and imaging appearances. Identification of uterine sarcomas and their differentiation from benign uterine disease on imaging is of critical importance for treatment planning to guide appropriate management and optimize patient outcomes. Herein, we review the spectrum of uterine sarcomas with a focus on the classification of primary sarcoma subtypes and presenting the typical MR imaging appearances.

MRI Evaluation of Uterine Masses for Risk of Leiomyosarcoma: A Consensus Statement

Laparoscopic myomectomy, a common gynecologic operation in premenopausal women, has become heavily regulated since 2014 following the dissemination of unsuspected uterine leiomyosarcoma (LMS) throughout the pelvis of a physician treated for symptomatic leiomyoma. Research since that time suggests a higher prevalence than previously suspected of uterine LMS in resected masses presumed to represent leiomyoma, as high as one in 770 women (0.13%). Though rare, the dissemination of an aggressive malignant neoplasm due to noncontained electromechanical morcellation in laparoscopic myomectomy is a devastating outcome. Gynecologic surgeons' desire for an evidence-based, noninvasive evaluation for LMS is driven by a clear need to avoid such harms while maintaining the availability of minimally invasive surgery for symptomatic leiomyoma. Laparoscopic gynecologists could rely upon the distinction of higher-risk uterine masses preoperatively to plan oncologic surgery (ie, potential hysterectomy) for patients with elevated risk for LMS and, conversely, to safely offer women with no or minimal indicators of elevated risk the fertility-preserving laparoscopic myomectomy. MRI evaluation for LMS may potentially serve this purpose in symptomatic women with leiomyomas. This evidence review and consensus statement defines imaging and disease-related terms to allow more uniform and reliable interpretation and identifies the highest priorities for future research on LMS evaluation.

Review of uterine fibroids: imaging of typical and atypical features, variants, and mimics with emphasis on workup and FIGO classification

Uterine fibroids are the most common gynecologic neoplasm. Although non-degenerated fibroids are easily identifiable on imaging, degenerated fibroids, fibroid variants, and fibroids with unusual growth patterns can constitute a diagnostic dilemma. Identification of these abnormal morphologic features can alter the diagnosis of presumed uterine fibroids and hence change management plans. This article reviews the typical and atypical radiologic imaging features of uterine fibroids, with an emphasis on the pitfalls, mimics, and radiologically identifiable features that can alter clinical management plans.

18F-fluorodeoxyglucose positron emission tomography-computed tomography imaging of leiomyomatosis peritonealis disseminata

Leiomyomatosis peritonealis disseminata (LPD) is a rare benign condition characterized by multiple smooth muscle implants in the peritoneal cavity. The clinical presentation is usually nonspecific abdominal discomfort and nontender abdominal mass. Preoperative imaging usually points to suggests malignancy due to its unusual location, but the diagnosis can only be confirmed by histopathological examination. We share ¹⁸F-Fluorodeoxyglucose positron emission tomography-computed tomography images of a 43-year-old woman diagnosed with LPD and briefly discuss the clinical aspects of this disease.

PET/CT Variants and Pitfalls in Gynecological Cancers

The role of hybrid imaging with 2-[18F] flourodeoxyglucose (FDG) positron emission tomography and computed tomography (PET/CT) is continuously evolving and now considered standard practice in evaluation of disease stage, treatment response, recurrent disease and follow-up for numerous primary malignancies. In gynecological malignancies FDG PET/CT plays an important role, not only in the assessment of disease in the pre-and post-therapy setting, but also in radiation therapy (RT) planning by defining the metabolically active gross tumor volume (GTV. The glucose analogue radiotracer, FDG, is by far the most utilized radiotracer in PET/CT and is typically seen with high uptake in malignant cells. The radiotracer FDG has a high sensitivity but low specificity for malignancy, as benign processes with an inflammatory response for example infection, are also FDG-avid. In the evaluation of the female pelvic region an awareness of potential confounding factors in the interpretation of FDG is essential as variations of FDG uptake occur in accordance with the menstrual cycle and the menopausal state. Incidental imaging findings in the female genital can pose differential diagnostic challenges as false-positive and false-negative findings in benign and malignant processes are not uncommon. Gynecological malignancies continue to pose major public health problems with cervical cancer as the fourth most common cancer in women ranking after breast cancer, colorectal cancer and lung cancer. Familiarity with frequently encountered benign and malignant variants and pitfalls in FDG PET/CT in the female pelvic region can aid the reader in differential diagnostic considerations.

Multiple Cutaneous Leiomyomas Showing Increased FDG Uptake

Cutaneous leiomyomas are rare, sporadic, or inherited benign tumors arising from smooth muscle cells of the skin associated with various disorders. We present a case of multiple cutaneous leiomyomas showing increased FDG uptake with SUVmax of 19.9. This case indicates cutaneous leiomyoma should be considered as a rare differential diagnosis in patients with hypermetabolic cutaneous lesions. Careful correlation with clinical history is needed to avoid misdiagnosis.

Isolated uterine metastasis from a lung adenocarcinoma

A 65-year-old woman was referred with an incidental finding of a flurodeoxyglucose-avid uterine lesion, following excision of a local lung adenocarcinoma. MRI had features concerning for an atypical fibroid or smooth muscle tumour of uncertain malignant potential. She underwent a total abdominal hysterectomy and bilateral salpingo-oophorectomy. Histopathology demonstrated a leiomyoma infiltrated with adenocarcinoma consistent with a secondary lesion from the lung cancer. Among the small number of cases of uterine metastases of extra-pelvic primary cancers reported in the literature, those from lung cancers are very rare. Concerning features for an atypical fibroid included the patient's age and postmenopausal status, as well as positron emission tomography and MRI findings. A metastatic secondary cancer was not suspected. Diagnosis was only made after histopathological examination. This case represents a very unusual cause of a uterine mass. It demonstrates the importance of thorough preoperative work-up and accurate histopathological assessment.

How to differentiate uterine leiomyosarcoma from leiomyoma with imaging

Uterine leiomyomas, the most frequent benign myomatous tumors of the uterus, often cannot be distinguished from malignant uterine leiomyosarcomas using clinical criteria. Furthermore, imaging differentiation between both entities is frequently challenging due to their potential overlapping features. Because a suspected leiomyoma is often managed conservatively or with minimally invasive treatments, the misdiagnosis of leiomyosarcoma for a benign leiomyoma could potentially result in significant treatment delays, therefore increasing morbidity and mortality. In this review, we provide an overview of the differences between leiomyoma and leiomyosarcoma, mainly focusing on imaging characteristics, but also briefly touching upon their demographic, histopathological and clinical differences. The main indications and limitations of available cross-sectional imaging techniques are discussed, including ultrasound, computed tomography, magnetic resonance imaging (MRI) and positron emission tomography/computed tomography. A particular emphasis is placed on the review of specific MRI features that may allow distinction between leiomyomas and leiomyosarcomas according to the most recent evidence in the literature. The potential contribution of texture analysis is also discussed. In order to help guide-imaging diagnosis, we provide an MRI-based diagnostic algorithm which takes into account morphological and functional features, both individually and in combination, in an attempt to optimize radiologic differentiation of leiomyomas from leiomyosarcomas.

A Giant Duodenal Leiomyoma Showing Increased Uptake on 18F-Fluorodeoxyglucose Positron Emission Tomography

Background

Although 18F-fluorodeoxyglucose positron emission tomography (FDG-PET/CT) is now widely used in their differential diagnosis, it is sometimes difficult to distinguish between benign and malignant diseases.

Case Presentation

A 44-year-old woman was found to have abnormalities on health screening. Magnetic resonance imaging for detailed examination showed an intra-abdominal tumor measuring 12 cm in the major axis near the cranial end of the uterus. Upper gastrointestinal tract endoscopy showed a tumor with an ulcer in the third part of the duodenum, involving half the circumference. Heterogeneous uptake was observed within the tumor on FDG-PET/CT. Based on these findings, the patient underwent surgery for suspected primary malignant lymphoma of the duodenum or gastrointestinal stromal tumor. Laparotomy revealed a 12 cm tumor in the third part of the duodenum. Partial duodenectomy and end-to-end duodenojejunostomy were performed. Pathological findings showed a solid tumor growing from the muscle layer of the duodenum to outside the serous membrane; based on immunostaining, it was diagnosed as a leiomyoma.

Conclusions

Duodenal leiomyomas are originally benign; to date, there have been no reports of uptake in duodenal leiomyomas on FDG-PET/CT; therefore, our case is rare. Leiomyomas should be considered in the differential diagnosis of duodenal neoplastic diseases.

18F-FDG PET/CT in the evaluation of cancer cervix: Where do we stand today?

The incidence of gynecological malignancies is on the rise partly because of the availability of screening programmes, awareness, higher technological advancements, and availability of better medical care. Early diagnosis of any malignancy leads to prompt treatment. Use of 18Fluorine-Fluorodeoxyglucose (F-FDG) PET/CT in the treatment and follow-up of patients with Ca cervix considerably improves patient management. The primary diagnosis of Ca cervix is made either by biopsy of a visible tumor on the cervix or by a cone biopsy of a nonvisible malignant cervical focus. The staging procedure is purely clinical (i.e. gynecologic examination under general anesthesia) according to the International Federation of Gynaecology and Obstetrics classification. Earlier, with the nonavailability of sophisticated medical equipment and imaging specialists, oncologists relied heavily on clinical examination. However, anatomical and functional imaging has been proven to be considerably superior in understanding parametrial involvement and nodal/distant metastases in the cancer cervix than clinical examination alone. Data are evolving on the usage of F-FDG PET/CT in initial staging, treatment planning, and monitoring therapy response for gynecological malignancies. Prognostic information derived from the primary lesion such as the maximum standardized uptake value, metabolic tumor volume, and extent of para-aortic nodal metastatic disease plays a critical role in tailoring therapy on the basis of patient tumor-specific factors rather than on International Federation of Gynaecology and Obstetrics stage alone. Thus, F-FDG PET/CT needs to be listed not only under the panel of pretherapy investigations for Ca cervix but also for recurrence and therapy response assessments. It allows a more confident approach to patient management at initial staging, especially in terms of the decision to choose surgical versus palliation measures.

Evidence-based management of incidental focal uptake of fluorodeoxyglucose on PET-CT

Focal incidental uptake, with or without CT abnormalities, is a common finding on fluorodeoxyglucose PET/CT and evidence-based management for this type of uptake is lacking. This article reviews the evidence on focal incidental uptake including the incidence of malignancy, differential diagnosis and imaging criteria which can be used to further characterize it. The article focusses on PET rather than CT criteria. The strength of the evidence base is highly variable ranging from systematic reviews and meta-analyses to a virtual absence of evidence. Caution needs to be used when using standardized uptake values (SUVs) reported in other studies due to interpatient and institution observed variation in SUVs. There is sufficient evidence to permit specific suggestions on how to interpret the foci and recommend further management in the: pituitary (investigate when SUVmax >4.1), thyroid (investigate all), breast (investigate all), lung parenchyma (if focus of fluorodeoxyglucose without a CT nodule, no further investigations), colon (investigate all foci with SUVmax >5.9, urgently if SUVmax >11.4), adrenals (criteria depend on if patient has cancer) and prostate gland (investigate in males aged >50 years or >40 years if peripheral uptake or patient has other risk factors). There is some evidence to guide further management for the parotid gland, naso-orophaynx, oesophagus, pancreas, uterus and ovaries. There is insufficient evidence to guide management for the liver, spleen, kidneys, gallbladder, testis and bone, for these organs patient characteristics and other guidelines will likely be of more use in determining further management.

Uterine fibroids with positive 18F-FDG PET/CT image and significantly increased CA19-9: A case report

RATIONALE

Uterine fibroids are the most common pelvic solid tumors and common to 25% of women. F-fluorodexyglucose (F-FDG) is an energy metabolism tracer. Although FDG is generally concentrated in malignant lesions with high glucose metabolism, it can also accumulate in normal tissues, benign lesions, and inflammatory sites. The exact mechanism of FDG uptake by uterine fibroids is not clear. Here, we report a case of uterine fibroids with positive F-FDG positron emission tomography/computed tomography (PET/CT) imaging and significantly increased CA19-9.

PATIENTS CONCERNS

The patient was a 43-year-old woman and admitted to our hospital because of "1-year-extended menstrual periods." At admission, she had normal CA125, AFP, and CEA level and CA19-9>1000.00 U/mL. Gynecological transvaginal ultrasound found enlarged uterus with an anterior hypoechoic area of 3.9 × 4.2 cm. CT and contrast-enhanced CT showed significantly enhanced mass shadow on the left anterior wall of uterus. F-FDG PET/CT showed increased FDG metabolism of tumor in the anterior wall of the uterus.

INTERVENTIONS

Laparoscopic hysterectomy was performed.

DIAGNOSIS

Pathological examination demonstrated subserosal leiomyoma.

OUTCOMES

Her CA19-9 level dropped to 91.50 U/mL 1 day after surgery.

LESSONS

Significantly elevated CA19-9 was positioned in the uterus by PET/CT imaging, which not only avoided unnecessary gastrointestinal endoscopy and reduced the suffering of patients, but also strengthened the operation confidence in gynecologists.

Impacts of biological and procedural factors on semiquantification uptake value of liver in fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging

BACKGROUND

Increased metabolic activity of fluorodeoxyglucose (FDG) in tissue is not only resulting of pathological uptake, but due to physiological uptake as well. This study aimed to determine the impacts of biological and procedural factors on FDG uptake of liver in whole body positron emission tomography/computed tomography (PET/CT) imaging.

METHODS

Whole body fluorine-18 ((18)F) FDG PET/CT scans of 51 oncology patients have been reviewed. Maximum standardized uptake value (SUVmax) of lesion-free liver was quantified in each patient. Pearson correlation was performed to determine the association between the factors of age, body mass index (BMI), blood glucose level, FDG dose and incubation period and liver SUVmax. Multivariate regression analysis was established to determine the significant factors that best predicted the liver SUVmax. Then the subjects were dichotomised into four BMI groups. Analysis of variance (ANOVA) was established for mean difference of SUVmax of liver between those BMI groups.

RESULTS

BMI and incubation period were significantly associated with liver SUVmax. These factors were accounted for 29.6% of the liver SUVmax variance. Statistically significant differences were observed in the mean SUVmax of liver among those BMI groups (P<0.05).

CONCLUSIONS

BMI and incubation period are significant factors affecting physiological FDG uptake of liver. It would be recommended to employ different cut-off value for physiological liver SUVmax as a reference standard for different BMI of patients in PET/CT interpretation and use a standard protocol for incubation period of patient to reduce variation in physiological FDG uptake of liver in PET/CT study.

FDG-PET/CT findings of atypical (bizarre/symplastic) uterine leiomyoma in a patient with abdominal leiomyosarcoma

Atypical (bizarre) leiomyoma is a benign uterine smooth-muscle tumor characterized by a) a significant number of cells with dense eosinophilic cytoplasm and enlarged, bizarre single/multiple hyperchromatic or multiple nuclei without tumor necrosis and b) poor mitotic activity. We report the case of an atypical (bizarre) leiomyoma revealed by focal fluoro-deoxyglucose (FDG) uptake during a PET-CT in a patient with relapsing abdominal and retroperitoneal leiomyosarcoma.

Medical Device Safety and Surgical Dissemination of Unrecognized Uterine Malignancy: Morcellation in Minimally Invasive Gynecologic Surgery

There is a risk of dissemination of uterine malignancies during minimally invasive hysterectomies when morcellation is used. Although the technique of uterine power morcellation allows timely removal of large benign tumors through small laparoscopic incisions, there are concerns about iatrogenic spread of cancers and reduced survival for women with preoperatively unrecognized malignancies. This review examines the literature on intraperitoneal spread and implantation of mechanically disrupted malignant tissue, discusses the current diagnostic tools for preoperative assessment of uterine tumors, and summarizes the current recommendations of the Society of Gynecologic Oncologists, the American College of Obstetricians and Gynecologists, and the American Association of Gynecologic Laparoscopists. Recommendations include informed consent of the risk of disseminating an otherwise contained malignancy, appropriate preoperative evaluation for malignancy, and development of alternatives to intracorporeal morcellation.

IMPLICATIONS FOR PRACTICE

Preoperative assessment of uterine masses or abnormal uterine bleeding must include understanding of the limitations of an endometrial biopsy and imaging studies to evaluate the possibility of a uterine malignancy. Minimally invasive surgery using morcellation of benign uterine growths is well established and safe; however, alternative surgical techniques to morcellation must be considered when the malignant potential of a uterine mass is uncertain. Morcellation carries the risk of widespread peritoneal seeding of an unrecognized uterine malignancy. Gynecologic surgeons must weigh the unlikely occurrence of disseminating an undiagnosed uterine sarcoma with the much more common surgical risks of abdominal surgery.

Gynecologic oncologic imaging with PET/CT

FDG-PET/CT has been evaluated in a variety of gynecologic malignancies in a variety of settings and is approved by the Centers for Medicare & Medicaid Services for the initial and subsequent treatment strategies of these malignancies. Cervical cancer is typically very FDG avid, and FDG-PET/CT appears to be most valuable for initial staging, radiation therapy planning, and detection of recurrent disease. For ovarian cancer, the most value of FDG-PET/CT appears to be for detecting recurrent disease in the setting of rising CA-125 level and negative or equivocal anatomical imaging studies. Initial studies evaluating response to therapy are promising and further work in this area is needed. FDG uptake in both nonmalignant and physiological processes in the pelvis can make interpretation of FDG-PET/CT in this region challenging and knowledge of these entities and patterns can avoid misinterpretation. Some of the most common findings relate to the cyclic changes that occur as part of the menstrual cycle in premenopausal women. Mucinous tumors and low-volume or peritoneal carcinomatosis are causes of false-negative results on FDG-PET/CT studies. As new tracers are developed, comparisons with patient outcomes and standards of care (eg, FDG-PET/CT) will be needed.

Non-FDG-avid primary papillary thyroid carcinoma may not differ from FDG-avid papillary thyroid carcinoma

BACKGROUND

FDG (2-[(18)F]Fluoro-2-D-deoxyglucose-positron emission tomography (PET)/computed tomography (CT), which can detect a change in glucose metabolism in cancer cells, has been introduced as a diagnostic and prognostic tool in papillary thyroid carcinoma (PTC). However, differences in the clinicopathological and biological characteristics between primary PTCs with FDG uptake and those without FDG uptake are not well established.

METHODS

A total of 188 patients with PTC who had preoperative PET/CT scans were enrolled to compare the differences of clinicopathological parameters between FDG-avid (F-PTC; n = 150) and non-FDG-avid tumors (FN-PTC; n = 38). Immunohistochemical staining for glucose transporter (GLUT)-1 and hypoxia-inducible factor-1 alpha (HIF-1α) was performed.

RESULTS

FN-PTCs were smaller; had a lower incidence of lymphatic invasion, vascular invasion, multifocality, and central lymph node metastasis; and had a lower maximum standardized uptake value than F-PTCs. After exclusion of high-risk patients for recurrence, FN-PTCs remained smaller (p < 0.001) and had less lymphatic invasion (p = 0.061). Among tumors larger than the spatial resolution of the PET/CT scan, macrocalcification was more frequent in FN-PTC than in F-PTC (p = 0.043). While FN-PTC and F-PTC showed no difference in GLUT-1 expression (50% vs. 75%, p = 0.363), FN-PTC showed lower HIF-1α immunoreactivity than F-PTC (25.0% vs. 75.0%, p = 0.032).

CONCLUSION

Tumor size and macrocalcification are clinicopathological differences between FN-PTC and F-PTC. Biologically, HIF-1α may be responsible for increased FDG uptake in PTC.

ATL

Objective

Positron emission tomography/computed tomography (PET/CT) is an important tool in oncology for assessment of disease extent and recurrence. Recognition of benign fluorodeoxyglucose (FDG) uptake promotes correct interpretation of imaging data. This study assesses the appearance of benign uterine leiomyomas (ULs) on PET/CT and evaluates possible hormonal influences.

Patients and Methods

This was a retrospective study performed in a tertiary referral cancer center in Israel. One hundred fifty-two women with nongynecologic malignancies were referred for PET/CT scans, with incidental UL on imaging. Information on menopausal status and menstrual phase and on the use of oral contraceptives, hormone replacement therapy, and selective estrogen receptor modulators (SERM) was collected. Fluorodeoxyglucose uptake measured as standard uptake value (SUV) was obtained for UL, normal myometrium, and gluteus muscle. Changes associated with menopausal status, menstrual cycle phase, and the use of oral contraceptives, hormone replacement therapy, and SERM were assessed.

Results

The mean ± SD SUV in UL for the entire cohort was 1.39 ± 0.65 and was higher than in myometrium (1.24 ± 0.33) and gluteus muscle (0.48 ± 0.36). Fluorodeoxyglucose uptake was similar in UL and in myometrium during the preovulatory (1.42 ± 0.31 vs 1.23 ± 0.34) and postovulatory (1.23 ± 0.34 vs1.38 ± 0. 4) periods. During ovulation, SUV was significantly higher in UL (1.62 ± 0.39) than in normal myometrium (1.12 ± 0.15; P = 0.01). Uterine leiomyoma FDG uptake in premenopausal women (1.47 ± 0.32) was higher than in postmenopausal women (1.29 ± 0.41; P < 0.02). The UL/gluteus SUV ratio in patients on hormone replacement therapy (2.53 ± 0.23) was significantly higher than in untreated patients (1.27 ± 0.92; P = 0.05). Lower uptake was recorded in patients on SERM (SUV, 1.1 ± 0.24) than in untreated patients (SUV, 1.41 ± 0.36; P < 0.01).

Conclusion

Fluorine 18 FDG uptake in UL may be estrogen dependent. Endogenous estrogen and hormone replacement therapy increase FDG uptake, whereas withdrawal of estrogen by menopause or SERM decreases uptake.

Successful enucleation of a fluorine-18-fluorodeoxyglucose positron emission tomography positive esophageal leiomyoma in the prone position using sponge spacer and intra-esophageal balloon compression

Recently, prone position esophagectomy for esophageal cancer is thought to be an easier and safer procedure. Here, we introduced prone position for enucleation of the fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) positive esophageal leiomyoma. The patient was a 47-year-old man with a 4 cm mid-thoracic esophageal submucosal tumor. The tumor was enucleated safely without injury of the esophageal mucosa under the gravity effect of the prone position with use of a sponge spacer and Sengstaken-Blakemore balloon. Postoperative examination revealed that the tumor was a leiomyoma that was positive for smooth muscle actin and negative for CD117. Postoperative course was uneventful and the patient was discharged on day 7 after the operation. The prone position with use of a sponge spacer and Sengstaken-Blakemore balloon was a safer and easier procedure for the enucleation of the esophageal submucosal tumor.

18F-FLT PET performs better than 18F-FDG PET in differentiating malignant uterine corpus tumors from benign leiomyoma

PURPOSE

The aim of this study is to test the hypothesis that positron emission tomography (PET) with 3'-deoxy-3'-[(18)F]-fluorothymidine ((18)F-FLT) can differentiate malignancy from benign leiomyoma better than PET with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG), and to evaluate whether (18)F-FLT and (18)F-FDG uptake correlate with immunohistochemical index of cell proliferation.

METHODS

The protocol of this prospective study was approved by the institutional ethics committee, and all patients gave written informed consent. Fifteen patients (aged 26-65 years, median 44 years) with uterine corpus tumor which has the possibility of being leiomyosarcoma underwent (18)F-FLT and (18)F-FDG PET scans. Maximum standard uptake value (SUV(max)) of PET scans and Ki-67 labeling index of surgical specimens were evaluated. Mann-Whitney's U test was used for comparing uptakes between benign and malignant, and linear regression analysis was used for evaluating the correlation between Ki-67 labeling index and SUV(max).

RESULTS

Five cases were diagnosed as malignant (leiomyosarcoma for 3 cases, and carcinoma for 2 cases), and the others were benign leiomyoma. Sensitivity and negative predictive value of both tracers for detecting malignancy was 100%. Specificity, positive predictive value and accuracy of (18)F-FLT PET were higher than those of (18)F-FDG PET. Difference in SUV(max) between malignant and benign was significant for (18)F-FLT PET (P < 0.01), but not for (18)F-FDG PET. While all the malignant cases showed positive uptake in both tracers, a case of leiomyosarcoma with huge necrosis showed relatively low uptake. Uptake of (18)F-FLT showed better correlation with Ki-67 labeling index compared with (18)F-FDG (R(2) = 0.91 vs. R(2) = 0.26).

CONCLUSION

Negative findings on additional (18)F-FDG or (18)F-FLT PET may rule out the possibility of malignancy for the patients with suspected leiomyosarcoma diagnosed by conventional methods. (18)F-FLT PET is superior to (18)F-FDG PET in differentiating malignant from benign leiomyoma. Moreover, (18)F-FLT uptake correlated well with the immunohistochemical index of cell proliferation.

Adenomyosis with extensive glandular proliferation simulating infiltrating malignancy on magnetic resonance imaging

We report a case of multicystic adenomyosis, which is an exceedingly rare benign tumor. The patient complained of an irregular menstrual cycle and abnormal genital bleeding that gradually increased in amount and frequency. The patient finally became severely anemic, and a hysterectomy was therefore performed. T2-weighted magnetic resonance imaging (MRI) indicated hyperplasia of the endometrium, with a myometrial lesion, where a high signal intensity multicystic mass was observed. The preoperative diagnosis was complicated by confusing MRI results. Postoperative macroscopic examination revealed a villous endometrium and a myometrium thickened with multiple small cysts containing serous transparent fluid. The final diagnosis, based on the hysterectomy specimen, was adenomyosis coexisting with simple endometrial hyperplasia. The MRI and positron emission tomography images are presented.

Glucose transporter expression of intraductal papilloma of the breast detected by fluorodeoxyglucose positron emission tomography

A 40-year-old woman discovered through palpation a tumor in the upper lateral quadrant of the left mammary gland. Mammography, ultrasonography (US), and magnetic resonance imaging (MRI) showed a 10 mm diameter tumor. Fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG-PET) showed abnormal accumulation in the detected tumor, and the maximum standardized uptake value was 2.2. The patient underwent tumor resection. The postoperative histopathological finding was intraductal papilloma. The intraductal papilloma showed strong expression of glucose transporter (GLUT)-4 on membrane and/or cytoplasm, and weak expression of GLUT-1 and GLUT-3 by immunohistochemistry. This case suggests that other glucose transporters (e.g., GLUT-4), other pathological factors, and cytokines may have a close relation with (18)F-FDG accumulation in intraductal papilloma more than GLUT-1 or GLUT-3 expression.

Analysis of various malignant neoplasms detected by FDG-PET cancer screening program: based on a Japanese Nationwide Survey

OBJECTIVE

The most distinctive feature of FDG-PET cancer screening program is the ability to find various kinds of malignant neoplasms in a single test. The aim of this survey is to clarify the range and frequency of various malignant neoplasms detected by FDG-PET cancer screening performed in Japan.

METHODS

"FDG-PET cancer screening" was defined as FDG-PET or positron emission tomography and computed tomography (PET/CT) scan with or without other tests performed for cancer screening of healthy subjects. This survey was based on a questionnaire regarding FDG-PET cancer screening. We analyzed the situation of 9 less frequently found malignant neoplasms including malignant lymphoma, malignancy of head and neck, esophagus, hepatobiliary and gallbladder, pancreas, kidney, cervical and uterine, ovary, and bladder.

RESULTS

The detailed information of subjects with the suspected 9 kinds of malignant neoplasms mentioned above in the FDG-PET cancer screening program was studied in a total of 1,219 cases from 212 facilities. A statistical significance between PET/CT and PET was found in relative sensitivity and PPV for renal cell cancer. Malignant lymphoma was frequently of indolent type, suspected head and neck cancers had many false-positive results, and pancreatic cancer detected in this program was often in the advanced stage even in asymptomatic subjects. The recommendation of combined screening modality to PET or PET/CT was as follows: gastric endoscopy for assessing early esophageal cancer; abdominal ultrasound for screening hepatobiliary and gallbladder cancer; pelvic magnetic resonance imaging for assessing gynecological and pelvic cancers; and the CA125 blood test for screening ovarian cancer. Delayed image was helpful depending on the type of suspected malignant neoplasm.

CONCLUSION

We analyzed various types of malignant neoplasms detected by the FDG-PET cancer screening program and presented recommended combination of examinations to cover FDG-PET and PET/CT.

Spectrum of FDG PET/CT findings of uterine tumors

OBJECTIVE

The purpose of this article is to review FDG PET/CT and MRI findings in a variety of benign and malignant tumors of the uterus and to become familiar with the wide variety of FDG PET/CT findings of this entity.

CONCLUSION

Benign uterine tumors generally have mild FDG uptake, and leiomyoma rarely shows high uptake. Uterine malignant tumors generally have intense FDG uptake, whereas malignant uterine tumors that are small or that have low cellular density often show minimal uptake.