Bilateral Tubo-Ovarian Abscess Mimics Ovarian Cancer on MRI and (18)F-FDG PET/CT

O-RADS MRI risk stratification system: pearls and pitfalls

In 2021, the American College of Radiology (ACR) Ovarian-Adnexal Reporting and Data System (O-RADS) MRI Committee developed a risk stratification system and lexicon for assessing adnexal lesions using MRI. Like the BI-RADS classification, O-RADS MRI provides a standardized language for communication between radiologists and clinicians. It is essential for radiologists to be familiar with the O-RADS algorithmic approach to avoid misclassifications. Training, like that offered by International Ovarian Tumor Analysis (IOTA), is essential to ensure accurate and consistent application of the O-RADS MRI system. Tools such as the O-RADS MRI calculator aim to ensure an algorithmic approach. This review highlights the key teaching points, pearls, and pitfalls when using the O-RADS MRI risk stratification system.Critical relevance statement This article highlights the pearls and pitfalls of using the O-RADS MRI scoring system in clinical practice.Key points• Solid tissue is described as displaying post- contrast enhancement.• Endosalpingeal folds, fimbriated end of the tube, smooth wall, or septa are not solid tissue.• Low-risk TIC has no shoulder or plateau. An intermediate-risk TIC has a shoulder and plateau, though the shoulder is less steep compared to outer myometrium.

Bilateral Tubo-Ovarian Abscess Colonized by Enterococcus in a Woman With Systemic Lupus Erythematosus and End-Stage Renal Disease: A Case Report

Tubo-ovarian abscess (TOA) is an inflammatory process involving the fallopian tubes and the ovary. It is one of the complications occurring in acute pelvic inflammatory disease (PID). Intrauterine device (IUD) insertion, history of a prior PID, reproductive age, and multiple sexual partners are the most common risk factors for TOA. The diagnosis of bilateral TOA is rare. Commonly isolated organisms from the abscess include Neisseria (N.) gonorrhoeae, Escherichia​​​​​​​ (E.) coli, and/or normal flora of the vagina and cervix. Treatment of the abscess should be started as soon as possible with broad-spectrum antibiotics as recommended by the Centers for Disease Control and Prevention (CDC) and drainage of the pelvic collection.

Here, we present a complicated case in a middle-aged, sexually inactive woman with bilateral TOA colonized by Enterococcus faecalis. She is a known case of systemic lupus erythematosus (SLE) complicated by end-stage renal disease (ESRD), along with other co-morbidities. We summarize, in our case report, the experience of a successful treatment for this condition.

The role of "penumbra sign" and diffusion-weighted imaging in adnexal masses: do they provide a clue in differentiating tubo-ovarian abscess from ovarian malignancy?

Purpose

To evaluate the role of “penumbra sign”, diffusion-weighted imaging (DWI), and the apparent diffusion coefficient (ADC) value in differentiating tubo-ovarian abscess (TOA) from ovarian malignancy.

Material and methods

Thirty-six patients with 50 adnexal masses (tubo-ovarian abscess, n = 24; ovarian malignancy, n = 26), who underwent magnetic resonance imaging (MRI) with DWI, were retrospectively evaluated. “Penumbra sign” (hyperintense rim on T1W images), diffusion restriction, and mean apparent diffusion coefficient (ADC) values from cystic (c-ADC) and solid (s-ADC) components were evaluated for all the masses.

Results

“Penumbra sign” on T1W images was significantly more common in the TOA group (n = 21, 87.5%) than in the ovarian malignancy group (n = 2, 7.7%) (p < 0.001). Similarly, diffusion restriction in the cystic component was more frequent in the TOA group (n = 24, 100% vs. n = 2, 10.5%; p < 0.001). In contrast, diffusion restriction in the solid component was more common in the ovarian malignancy group (n = 5, 20.8% vs. n = 26, 100%; p < 0.001). The mean c-ADC value was significantly lower in TOAs (p < 0.001). A c-ADC value of 1.31 × 10^-3 mm²/s may be an optimal cut-off in distinguishing TOAs from ovarian malignancies. Conversely, the mean s-ADC value was significantly lower in the ovarian malignancy group (p < 0.001). An s-ADC value of 0.869 × 10^-3 mm²/s may be an optimal cut-off in differentiating ovarian malignancies from TOAs (p < 0.001). ROC curve analysis showed that c-ADC values had a higher diagnostic accuracy than s-ADC values.

Conclusions

“Penumbra sign” on T1W images, diffusion characteristics, and ADC values provide important clues in addition to conventional MR imaging features in differentiating TOA from ovarian malignancy.

Extrapulmonary Tuberculosis Mimics Diffuse Metastatic Disease: A Case Report

Background  Extrapulmonary tuberculosis (TB) is associated with major diagnostic difficulties as it has many atypical symptoms and its imaging findings are similar to those of many other diseases.

Case Report  We present the case of a 50-year-old woman with a complex cystic mass in her pelvis and a 2-month history of pain. Thoracoabdominal computed tomography (CT) revealed the following: (1) multiple supraclavicular, axillary, mediastinal, and abdominal pathologic lymph nodes with central hypoattenuation; (2) sternal and dorsal vertebral bone destruction with a soft tissue mass; and (3) multiple hypoattenuating masses in the liver. ¹⁸ F-fludeoxyglucose positron emission tomography/computed tomography ( ¹⁸ F-FDG PET/CT) revealed pathologic uptake in the defined areas, which were similar to metastases. Chest X-ray was normal. Diffuse metastatic disease was suspected clinically, but careful analysis of the imaging findings and the final pathologic results revealed multisystemic extrapulmonary TB. Clinical and radiological recovery was significant after anti-TB treatment at the 6-month follow-up.

Conclusion  Extrapulmonary TB without pulmonary involvement is associated with major diagnostic difficulties, especially with PET-CT. However, recognition and understanding of the CT or MR imaging spectrum can aid in the correct diagnosis and management of the disease.

Acute Findings on FDG PET/CT: Key Imaging Features and How to Differentiate Them from Malignancy

PURPOSE OF REVIEW

To review acute findings commonly encountered during routine clinical FDG PET/CT studies and present key imaging features to differentiate them from malignant counterparts.

RECENT FINDINGS

FDG PET/CT is extensively used in routine clinical practice for oncology patients. Incidental acute findings in patients undergoing FDG PET/CT are increasingly common, and awareness of these findings and their mimics are important in delivering a clinically relevant and accurate radiological report for directing further management.

SUMMARY

This article will review examples of common acute findings encountered during routine FDG PET/CT scans, compare them against examples of FDG-avid malignancy that can mimic these findings and emphasize key imaging findings to differentiate acute findings from their malignant mimics.

The impact of infection and inflammation in oncologic 18F-FDG PET/CT imaging

Sites of infection and inflammation can be misleading in oncology PET/CT imaging because these areas commonly show ¹⁸F-FDG activity. Caution in the interpretation must be taken to avoid the misdiagnosis of malignancy. Utilization of both CT findings as well as patient history can help differentiate benign infectious and inflammatory processes from malignancy, although occasionally additional work-up may be required. This article discusses the mechanism of ¹⁸F-FDG uptake in infection and inflammation with illustrative examples.

Characterization of tubo-ovarian abscess mimicking adnexal masses: Comparison between contrast-enhanced CT, 18F-FDG PET/CT and MRI

0BJECTIVE: We compared the diagnostic accuracy of contrast-enhanced computed tomography (CT), fluorine 18-labeled-fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT and conventional magnetic resonance imaging (MRI) without and with diffusion-weighted imaging (DWI) for characterization of tubo-ovarian abscesses (TOAs) that mimic adnexal tumors.

MATERIALS AND METHODS

We evaluated (retrospectively) 43 patients who underwent contrast-enhanced CT, PET/CT, conventional MRI without and with DWI, and who were found to have TOAs and complex adnexal tumors. All images were evaluated independently by four radiologists using a two-point grading system. Results of contrast-enhanced CT, PET/CT, MRI without DWI, and MRI with DWI were compared for each patient using receiver operating characteristic curves. Sensitivity, specificity, and positive predictive value (PPV) were calculated and compared using the chi-square test.

RESULTS

Sensitivity of MRI with DWI (95%) was significantly higher than that of contrast-enhanced CT (78.6%), PET/CT (86.7%) and MRI without DWI (87.5%). Specificities of these modalities were not significantly different. The PPV of MRI with DWI (100%) was significantly higher than that of the other three modalities (CT, 72.4%; PET/CT 78.5%; MRI without DWI, 81.5%). Overall accuracy of MRI with DWI was significantly higher than that of the other three modalities (CT, 74.4%; PET/CT, 81.4%; MRI without DWI, 83.7%).

CONCLUSION

MRI with DWI shows high accuracy for characterization of complex ovarian lesions, and is the most useful method for differentiation of TOAs from ovarian tumors.

Middlemore Hospital experience with tubo-ovarian abscesses: an observational retrospective study

AIM

The aim of this paper was to study the characteristics of patients presenting to Middlemore Hospital with tubo-ovarian abscess (TOA) and to compare the outcomes of conservative medical management versus medical management with surgical drainage and medical management with radiological drainage.

METHODS

All patients admitted with a radiologically or surgically proven TOA between January 01, 2008 and December 31, 2010, were included and followed up until June 30, 2011. The total number of patient/index admission was 174.

RESULTS

The mean age of patients was 37.8 years. One hundred thirty patients had medical treatment only with hospitalization and antibiotics, and 44 patients were managed with antibiotics and surgical drainage. Complete resolution of TOA was 77.3% (99/128) for patients managed medically and 93.2% (41/44) for patients managed surgically. When the two groups were compared, patients who were managed surgically were more likely to have complete resolution of TOA within 6 months of index admission with an odds ratio (OR) of 4 and a P-value of 0.029. There was no statistically significant difference in the secondary outcomes namely of readmission with TOA (OR: 0.47) and the need for repeat surgical or radiological drainage (OR: 1.48). Nonetheless, the relative duration of hospitalization was longer for the surgical group with a P-value of <0.0001. The C-reactive protein and the size of TOA were the significant factors involved in the resolution of TOA.

CONCLUSION

The results of this study confirmed our initial hypothesis that we should consider surgical drainage more often, probably earlier, especially for the younger patients still desiring fertility preservation and for larger abscesses. Laparoscopic surgical drainage is safe and could be used as the procedure of choice. Conservative medical management is still acceptable with good cure rates of 77%. C-reactive protein and the size of the abscess were the important factors to consider when managing patients with TOA.

Transvaginal Sonography-Guided Core Biopsy of Adnexal Masses as a Useful Diagnostic Alternative Replacing Cytologic Examination or Laparoscopy in Advanced Ovarian Cancer Patients

Objective

The aim of this study was to evaluate transvaginal sonography (TVS)-guided core biopsy of the adnexal masses for neoadjuvant chemotherapy (NACT) in patients with advanced ovarian malignancies.

Materials and Methods

We retrospectively reviewed the medical records of 52 patients who had undergone TVS-guided core biopsies in our gynecologic cancer center between May 2009 and October 2015. TVS-guided core biopsies were performed on patients with advanced ovarian malignancies who were considered as candidates for NACT and patients with adnexal masses who required a differential diagnosis of non-gynecologic tumors.

Results

Thirty-seven patients (71.2%) were scheduled to undergo NACT owing to the presence of coexisting illness, age, tumor burden, and location of metastatic sites. Fifteen patients (28.8%) underwent TVS-guided core biopsies to determine if they had primary or secondary ovarian tumors. Histopathologic examinations revealed primary ovarian tumors in 44 patients (84.6%). Nongynecologic tumors including gastrointestinal stromal tumor and metastatic tumor from gallbladder, gastric, and colorectal cancer were found to be the second most common disease (n = 5 [9.6%]). Findings in the samples were nondiagnostic in 4 patients (5.8%). With respect to the histological concordance rate between TVS-guided core biopsy and surgical specimen, diagnostic accuracy was 93.6%. There were no biopsy-related complications.

Conclusions

TVS-guided core biopsy may be a feasible procedure to diagnose adnexal masses, particularly in patients with advanced ovarian malignancies who are more likely to benefit from NACT.

Tubo-Ovarian Abscess (with/without Pseudotumor Area) Mimicking Ovarian Malignancy: Role of Diffusion-Weighted MR Imaging with Apparent Diffusion Coefficient Values

Objective

To assess the added value of diffusion-weighted magnetic resonance imaging (DWI) with apparent diffusion coefficient (ADC) values compared to MRI, for characterizing the tubo-ovarian abscesses (TOA) mimicking ovarian malignancy.

Materials and Methods

Patients with TOA (or ovarian abscess alone; n = 34) or ovarian malignancy (n = 35) who underwent DWI and MRI were retrospectively reviewed. The signal intensity of cystic and solid component of TOAs and ovarian malignant tumors on DWI and the corresponding ADC values were evaluated, as well as clinical characteristics, morphological features, MRI findings were comparatively analyzed. Receiver operating characteristic (ROC) curve analysis based on logistic regression was applied to identify different imaging characteristics between the two patient groups and assess the predictive value of combination diagnosis with area under the curve (AUC) analysis.

Results

The mean ADC value of the cystic component in TOA was significantly lower than in malignant tumors (1.04 ± 0 .41 × 10⁻³ mm²/s vs. 2.42 ± 0.38 × 10⁻³ mm²/s; p < 0.001). The mean ADC value of the enhanced solid component in 26 TOAs was 1.43 ± 0.16×10⁻³mm²/s, and 46.2% (12 TOAs; pseudotumor areas) showed significantly higher signal intensity on DW-MRI than in ovarian malignancy (mean ADC value 1.44 ± 0.20×10⁻³ mm²/s vs.1.18 ± 0.36 × 10⁻³ mm²/s; p = 0.043). The combination diagnosis of ADC value and dilated tubal structure achieved the best AUC of 0.996. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of MRI vs. DWI with ADC values for predicting TOA were 47.1%, 91.4%, 84.2%, 64%, and 69.6% vs. 100%, 97.1%, 97.1%, 100%, and 98.6%, respectively.

Conclusions

DW-MRI is superior to MRI in the assessment of TOA mimicking ovarian malignancy, and the ADC values aid in discriminating the pseudotumor area of TOA from the solid portion of ovarian malignancy.

The performance of contrast-enhanced FDG PET/CT for the differential diagnosis of unexpected ovarian mass lesions in patients with nongynecologic cancer

PURPOSE

This study aimed to evaluate the diagnostic accuracy of contrast-enhanced FDG PET/CT for unexpected ovarian lesions in patients with nongynecologic cancers.

PATIENTS AND METHODS

The present retrospective study was approved by the hospital institutional review board. We enrolled 72 nongynecologic cancer patients (33 colorectal cancer, 20 breast cancer, and 19 gastric cancer) who showed unexpected ovarian lesions on contrast-enhanced FDG PET/CT and subsequently underwent surgical resection of the ovarian lesions. The SUVmax values of the ovarian lesions were compared according to the histopathological results, and the accuracy of PET/CT was evaluated.

RESULTS

A total of 103 ovarian lesions were surgically resected from 72 patients (64 ovarian lesions were metastases, 21 were benign, and 18 were malignant primary ovarian cancer). SUVmax among the 3 groups were different (P < 0.0001). Using a cutoff SUVmax of 2.5, the sensitivity, specificity, and accuracy of PET/CT for detecting malignant ovarian lesions were 80.5%, 81.0%, and 80.6%, respectively. Detection rates of PET/CT for colorectal, breast, and gastric cancer metastases, as well as primary ovarian cancers were 91.4%, 83.3%, 47.8%, and 100.0%, respectively. Using contrast-enhanced CT findings with SUVmax, the sensitivity, specificity, and accuracy of contrast-enhanced FDG PET/CT were improved to 95.1%, 76.2%, and 91.3%, respectively (P = 0.003).

CONCLUSIONS

Conventional FDG PET/CT showed moderate diagnostic accuracy for the detection of malignant ovarian lesions mainly due to low detection rate in gastric cancer metastases. The PET/CT detection rate of malignant ovarian lesions can be improved using contrast-enhanced CT findings with FDG uptake measurement.