A Corpus Luteal Cyst Masquerading as a Lymph Node Mass on PET/CT Scan in a Pregnant Woman With an Anterior Mediastinal Lymphomatous Mass

Risk of Upstaging Due to Oncofertility Treatment Mimicking Pelvic Lymphoma on 18F-FDG PET/CT

ABSTRACT

A 23-year-old woman with primary mediastinal large B-cell lymphoma was referred to 18F-FDG PET/CT for staging. Besides the large mediastinal FDG-avid tumor, another FDG-avid lesion with an SUV higher than expected in corpus luteum cysts was found in the pelvis, raising suspicion for tumor. However, gynecologic ultrasound and review of patient chart revealed history of oncofertility treatment with GNRH analog. This prior treatment was responsible for the intense 18F-FDG uptake within the left ovary, way above the SUV levels commonly associated with menstrual cycle. In this case, the disease was downgraded to stage II, resulting in a less aggressive treatment.

A false positive fluorodeoxyglucose positron emission tomography/computed tomography diagnosis of pelvic lymph node recurrence following surgical treatment of Stage 1 endometrial cancer-a case report

A 47 year old patient with a G3, FIGO stage 1A endometrial cancer was treated by hysterectomy. Her two ovaries were conserved because of the pre-operative diagnosis of endocervical cancer. On follow up PET-CT follow up investigation, she had a benign ovarian corpus luteal cyst mistaken as a metastatic pelvic lymph node which was later removed and proven benign histologically. This paper is to raise the clinical awareness of possible false positive PET finding from a benign ovarian cyst, such that a misinterpretation of “recurrence” as in this case can be avoided.

Value of second-opinion review of outside institution PET-CT examinations

OBJECTIVE

This study aimed to determine whether second-opinion reviews of PET/CT examinations by subspecialists alter reporting of malignant findings.

MATERIALS AND METHODS

This IRB-approved study compared 240 fluorine-18 fluorodeoxyglucose PET/CT consecutively dictated reports by two nuclear medicine subspecialists against the original outside institution reports. Subspecialist reviews documented whether malignant findings on the outside report were malignant and noted additional malignant findings not described on the outside report. The final diagnosis of malignancy or benignity was determined by pathology when available, otherwise by imaging follow-up.

RESULTS

A total of 22 findings (in 20 reports) called suspicious/malignant on the outside reports were deemed benign by subspecialist review. A final diagnosis was available for 20 of 22 findings by pathology (n=3) or follow-up imaging (n=17). The subspecialist review was accurate in 20 (100%) of 20 cases where a final diagnosis was available. The subspecialist review called 11 findings (in 11 reports) suspicious/malignant that were not described or deemed benign on the outside reports. Definitive diagnosis was available for 10 of 11 findings by pathology (n=7) or follow-up imaging (n=3). The second-opinion report was accurate in seven (70%) of 10 cases where a final diagnosis was available.

CONCLUSION

In 31 (13%) of 240 fluorine-18 fluorodeoxyglucose PET/CT examinations performed at an outside institution, subspecialist review resulted in at least one discordant opinion of malignancy. For 28 discrepant cases where a final diagnosis was available, the subspecialist review defined malignancy or benignity correctly in 25 (89%) of 28 cases. This provides evidence for the cost and effort invested in performing second-opinion reviews of PET/CT studies.

Radiological appearances of corpus luteum cysts and their imaging mimics

PURPOSE

To review the radiological appearances of corpus luteum cysts and their imaging mimics.

CONCLUSION

Corpus luteum cysts are normal post-ovulatory structures seen in the ovaries through the second half of the menstrual cycle and the first trimester of pregnancy. The typical appearance, across all modalities, is of a 1- to 3-cm cyst with a thick crenulated vascularized wall. Occasionally, similar imaging findings may be seen with endometrioma, ectopic pregnancy, tuboovarian abscess, red degeneration of a fibroid, and ovarian neoplasia. In most cases, imaging findings are distinctive and allow for a confident and accurate diagnosis that provides reassurance for patients and referring physicians and avoids costly unnecessary follow-up.

FDG PET-CT of gynecologic cancers: pearls and pitfalls

FDG PET-CT plays an important role in treatment planning and in prognosis assessment of gynecologic cancer patients. Detection of hypermetabolic tissue with FDG PET, when combined with the high spatial resolution of CT, results in improved cancer detection and localization not afforded by either modality independently. This article is a primer for a radiologist performing PET-CT on gynecologic cancer patients and includes the imaging protocol, normal pattern of FDG distribution in the female pelvis and the lymph node drainage pathways from the gynecologic organs. Clinically relevant imaging findings that should be included in the report are discussed. Case examples illustrate how potential errors in exam interpretation can be avoided by concurrently performing a high-quality diagnostic CT with the FDG PET scan and by analyzing both the stand-alone and the fusion images.

Pelvis: normal variants and benign findings in FDG-PET/CT imaging

With the widespread use of whole-body fluorodeoxyglucose (FDG)-PET/computed tomography as a diagnostic tool in patients with cancer, incidental findings are of increasing importance. This is particularly true within the pelvis, where several benign findings might present with increased FDG uptake. In addition, physiologic excretion of radiotracer by way of the urinary tract can complicate image analysis. This article reviews potential incidental benign findings in the pelvis that one should be aware of when interpreting FDG-PET/computed tomography scans.

Pelvic MRI as the "gold standard" in the subsequent evaluation of ultrasound-indeterminate adnexal lesions: a systematic review

OBJECTIVE

Incidentally discovered adnexal masses are common, posing a challenging diagnostic problem because imaging features of benign and malignant overlap. Thus, once an adnexal lesion has been detected, the primary goal of further imaging is accurate tissue characterization resulting in surgery only for lesions that are indeterminate or frankly malignant. This study aims to conduct a systematic review, following the PRISMA guidelines, and critically appraise pelvic MR Imaging as the preferred advanced second imaging test, as regards detection of ovarian cancer and assessment of indeterminate adnexal masses, with respect to pre-operatively improving the assignment of these patients to the appropriate level of care.

METHODS

A comprehensive computerized systematic literature search of English language studies was performed (from 2002 to 2012) of PubMed, EMBASE, Scopus, Evidence Based Medicine Reviews (Cochrane Database and Cochrane Central Register of Controlled Trials), and Google Scholar. Relevant article reference lists were hand searched.

RESULTS

Computerized database search revealed 37 citations of relevance, 10 of which fulfilled the inclusion/exclusion criteria. From the aforementioned, 8 articles were acquired (2 authors were contacted but did not respond) as well as assessed with AHRQ, QUADAS, and STARD evaluation tools. Finally, 6 papers (5 prospective and 1 retrospective) were included in the systematic review.

CONCLUSIONS

MRI with intravenous (IV) contrast administration provides the highest post-test probability of ovarian cancer detection. However, the preponderant contribution of MRI in adnexal mass evaluation is its specificity because it provides confident diagnosis of many benign adnexal lesions.

Nuclear imaging of a pregnant patient: should we perform nuclear medicine procedures during pregnancy?

Although it is extremely rare, nuclear imaging of a pregnant woman presents a unique challenge to the nuclear medicine physician because of the high concern for radiation risk to the embryo or the fetus. This challenge has been exacerbated due to recent heightened public concern of medical procedures involving radiation. This awareness also has been emphasized to the referring physicians to the extent that the risks of most nuclear medicine scans are overstressed relative to the benefit. Radionuclide procedures are reluctantly ordered by clinicians in pregnant patients, because of the malpractice fear or because of uncertainty regarding fetal radiation dose. However, when used appropriately, the benefits of nuclear imaging procedures usually outweigh the minimal risks associated with small amount of radiation even in pregnant patients.

CONFLICT OF INTEREST

None declared.

Tc-99m red blood cell bleeding scan in a pregnant woman presenting with hematemesis: a brief review of indications and guidelines for radionuclide scans during pregnancy

A 6-month pregnant 35-year-old woman with hematemesis and dark blood in her stool was evaluated for location of an active gastrointestinal bleeding site. The findings from 2 esophagogastroduodenoscopies and a colonoscopy were negative. The patient was referred for a Tc-99m red blood cell scintigraphy, for location of an active bleeding site. As the patient was 6 months pregnant, the necessity of the case was discussed with the patient's referring physician and after determining that this study was necessary, the risk of radiation exposure to the fetus was discussed with the radiation safety officer and the patient. The procedure was performed after the patient signed informed consent regarding the considerations of radiation safety to the fetus. The Tc-99m red blood cell bleeding scan clearly shows activity in the fetus in addition to a large arteriovenous malformation in the patient. The visualized fetus prompted this report to discuss radiation risks concerns and a brief review of indications and guidelines for performing nuclear medicine procedures in pregnant patients.

MRI, CT, and PET/CT for ovarian cancer detection and adnexal lesion characterization

OBJECTIVE

The purpose of this article is to describe the role of MR, CT, and PET/CT in the detection of ovarian cancer and the evaluation of adnexal lesions.

CONCLUSION

The goal of imaging in ovarian cancer detection is to expeditiously distinguish benign adnexal lesions from those requiring further pathologic evaluation for malignancy. For lesions indeterminate on ultrasound, MRI increases the specificity of imaging evaluation, thus decreasing benign resections. CT is useful in diagnosis and treatment planning of advanced cancer. Although (18)F-FDG-avid ovarian lesions in postmenopausal women are considered suspicious for malignancy, PET/CT is not recommended for primary cancer detection because of high false-positive rates.