MR Imaging of Müllerian Anomalies.

Constituting a broad spectrum of developmental abnormalities of the female genital tract, Müllerian duct anomalies (MDAs) are present in up to 7% of the general population and in up to 25% of women who present with infertility and a history of miscarriage. Imaging plays an important role in narrowing the diagnostic considerations in these patients. In this article, we review the normal embryologic development of the female genital tract followed by the MR imaging techniques and protocol recommendations to evaluate such patients. The differential diagnoses and the MR imaging features of MDAs are also reviewed.

MR Imaging of Germ Cell and Sex Cord Stromal Tumors.

MR imaging is useful in the detection and characterization of adnexal lesions. This review discusses the clinical findings and MR imaging appearances of two types of ovarian neoplasms: germ cell and sex cord stromal tumors. The most common of these lesions, mature cystic teratomas, is characterized by the presence of bulk fat on MR imaging. Some of the other germ cell neoplasms and sex cord stromal tumors may have suggestive clinical, laboratory, or MR imaging features (eg, lipid and fibrosis) to establish a diagnosis. The ability to differentiate benign tumors from possible malignancy can aid in patient management.

Evaluation of the Viability of Untreated Leiomyomas Using Computed Tomography-Detected Calcification Patterns.

OBJECTIVE: To evaluate the relationship between computed tomography (CT)-detected calcification patterns and Magnetic Resonance Imaging (MRI) enhancement as a surrogate for viability in untreated uterine leiomyomas. METHODS: We queried 2 university hospital databases to identify patients with: (1) at least 1 calcified leiomyoma on CT greater than 1 cm (2) contrast-enhanced MRI of the pelvis performed within 5 years of the CT, and (3) no prior history of uterine fibroid embolization (UFE). Computed tomography was used to analyze calcification pattern and contrast-enhanced MRI to analyze size and viability. RESULTS: There were 12,862 reports that fit the criteria. After exclusion, 50 patients with 74 calcified untreated leiomyomas were analyzed. Three calcification patterns were identified: rim (n = 22), diffuse (n = 9), and coarse either less than or greater than 50% (n = 43). Four of 22 (18%) of leiomyomas with rim calcification were viable. Three of 9 (33%) of leiomyomas with diffuse calcification were viable. All leiomyomas with coarse calcifications were viable, 43 of 43 (100%). CONCLUSIONS: Leiomyomas with coarse calcifications are viable, whereas the majority with rim or diffuse calcification are not. This information may be helpful when triaging symptomatic women to treatment.

O-RADS MRI Risk Stratification System: Guide for Assessing Adnexal Lesions from the ACR O-RADS Committee.

MRI plays an important role as a secondary test or problem-solving modality in the evaluation of adnexal lesions depicted at US. MRI has increased specificity compared with US, decreasing the number of false-positive diagnoses for malignancy and thereby avoiding unnecessary or over-extensive surgery in patients with benign lesions or borderline tumors, while women with possible malignancies can be expeditiously referred for oncologic surgical evaluation. The Ovarian-Adnexal Reporting and Data System (O-RADS) MRI Committee is an international collaborative effort formed under the direction of the American College of Radiology and includes a diverse group of experts on adnexal imaging and management who developed the O-RADS MRI risk stratification system. This scoring system assigns a probability of malignancy based on the MRI features of an adnexal lesion and provides information to facilitate optimal patient management. The widespread implementation of a codified reporting system will lead to improved interpretation agreement and standardized communication between radiologists and referring physicians. In addition, it will allow for high-quality multi-institutional collaborations-an important unmet need that has hampered the performance of high-quality research in this area in the past. This article provides guidelines on using the O-RADS MRI risk stratification system in clinical practice, as well as in the educational and research settings.

Variability in biopsy quality informs translational research applications in hepatocellular carcinoma.

In the era of precision medicine, biopsies are playing an increasingly central role in cancer research and treatment paradigms; however, patient outcomes and analyses of biopsy quality, as well as impact on downstream clinical and research applications, remain underreported. Herein, we report biopsy safety and quality outcomes for percutaneous core biopsies of hepatocellular carcinoma (HCC) performed as part of a prospective clinical trial. Patients with a clinical diagnosis of HCC were enrolled in a prospective cohort study for the genetic, proteomic, and metabolomic profiling of HCC at two academic medical centers from April 2016 to July 2020. Under image guidance, 18G core biopsies were obtained using coaxial technique at the time of locoregional therapy. The primary outcome was biopsy quality, defined as tumor fraction in the core biopsy. 56 HCC lesions from 50 patients underwent 60 biopsy events with a median of 8 core biopsies per procedure (interquartile range, IQR, 7-10). Malignancy was identified in 45/56 (80.4%, 4 without pathology) biopsy events, including HCC (40/56, 71.4%) and cholangiocarcinoma (CCA) or combined HCC-CCA (5/56, 8.9%). Biopsy quality was highly variable with a median of 40% tumor in each biopsy core (IQR 10-75). Only 43/56 (76.8%) and 23/56 (41.1%) samples met quality thresholds for genomic or metabolomic/proteomic profiling, respectively, requiring expansion of the clinical trial. Overall and major complication rates were 5/60 (8.3%) and 3/60 (5.0%), respectively. Despite uniform biopsy protocol, biopsy quality varied widely with up to 59% of samples to be inadequate for intended purpose. This finding has important consequences for clinical trial design and highlights the need for quality control prior to applications in which the presence of benign cell types may substantially alter findings.

Occult Hepatocellular Carcinoma Associated With Transjugular Intrahepatic Portosystemic Shunts in Liver Transplant Recipients.

Transplant eligibility for hepatocellular carcinoma (HCC) is determined by the imaging identification of tumor burden within the Milan criteria. Transjugular intrahepatic portosystemic shunt(s) (TIPS) reduce portal hypertension but may impact HCC visualization. It was hypothesized that the presence of pretransplant TIPS would correlate with occult HCC and reduced survival. A single-center, retrospective, case control study was performed among liver transplant recipients with HCC (2000-2017). The primary endpoint was occult disease on explant pathology. Backward stepwise logistic regression was performed. The secondary endpoints disease-free survival (DFS) and overall survival (OS) were evaluated with Kaplan-Meier curves and Cox regression analysis. Of 640 patients, 40 had TIPS and more frequently exhibited occult disease (80.0% versus 43.1%; P < 0.001; odds ratio [OR], 4.16; P < 0.001). Portal vein thrombosis (PVT) similarly correlated with occult disease (OR, 1.97; P = 0.02). Explant tumor burden was equivalent between TIPS subgroups; accordingly, TIPS status was not independently associated with reduced DFS or OS. However, exceeding the Milan criteria was associated with reduced DFS (hazard ratio, 3.21; P = 0.001), and TIPS status in patients with a single suspected lesion (n = 316) independently correlated with explant tumor burdens beyond these criteria (OR, 13.47; P = 0.001). TIPS on pretransplant imaging are associated with occult HCC on explant pathology. Comparable occult disease findings in patients with PVT suggest that the mechanism may involve altered hepatic perfusion, obscuring imaging diagnosis. TIPS are not independently associated with reduced DFS or OS but are associated with exceeding the Milan criteria for patients with a single suspected lesion. The presence of TIPS may necessitate a higher index of suspicion for occult HCC.

Ovarian-Adnexal Reporting Lexicon for MRI: A White Paper of the ACR Ovarian-Adnexal Reporting and Data Systems MRI Committee.

MRI is used in the evaluation of ovarian and adnexal lesions. MRI can further characterize lesions seen on ultrasound to help decrease the number of false-positive lesions and avoid unnecessary surgery in benign lesions. Currently, the reporting of ovarian and adnexal findings on MRI is inconsistent because of the lack of standardized descriptor terminology. The development of uniform reporting descriptors can lead to improved interpretation agreement and communication between radiologists and referring physicians. The Ovarian-Adnexal Reporting and Data Systems MRI Committee was formed under the direction of the ACR to create a standardized lexicon for adnexal lesions with the goal of improving the quality and consistency of imaging reports. This white paper describes the consensus process in the creation of a standardized lexicon for ovarian and adnexal lesions for MRI and the resultant lexicon.

Update on MR Imaging of cystic retroperitoneal masses.

OBJECTIVE: This article reviews the MRI appearance of cystic retroperitoneal (RP) masses. CONCLUSION: Lymphangiomas are the most common RP cystic masses and typically appear simple; microscopic fat is a specific but insensitive finding. Location, internal complexity, and enhancement pattern suggest alternative diagnoses which range from normal anatomic variants to congenital abnormalities and importantly include benign, neurogenic, and malignant neoplasms. An approach to the MR imaging of cystic RP masses is presented.

Platinum response characteristics of patients with pancreatic ductal adenocarcinoma and a germline BRCA1, BRCA2 or PALB2 mutation.

BACKGROUND: Retrospective studies suggest a survival benefit when platinum-based chemotherapy is administered to patients with pancreatic cancer harbouring a germline mutation in BRCA1, BRCA2 or PALB2 (mut-positive PDAC). However, the objective response rate (ORR) and real-world progression free survival (rwPFS) achieved with such treatment remain ill-defined. METHODS: Twenty-six patients with advanced-stage mut-positive PDAC who had been treated with platinum-based therapy were matched by age, race and sex to 52 platinum-treated control PDAC patients. Responses to therapy were determined by RECIST v1.1, performed by blinded radiology review. Measured outcomes included ORR and rwPFS. RESULTS: The ORR in mut-positive patients was 58% compared to 21% in the control group (p = 0.0022). There was no significant difference in ORR between platinum regimens in mut-positive patients (p = 0.814), whereas in control patients, the only observed responses were to FOLFIRINOX. rwPFS was 10.1 mo. for mut-positive patients and 6.9 mo. for controls (HR 0.43; 95% CI 0.25-0.74; 0.0068). CONCLUSION: Mut-positive PDAC has a high ORR and prolonged rwPFS to platinum-based chemotherapy. These findings may have implications particularly in the neoadjuvant setting, and for future clinical trial design, and highlight the importance of early germline testing in patients with PDAC.

Pancreatic schwannoma, an extremely rare and challenging entity: Report of two cases and review of literature.

Pancreatic schwannoma is a rare benign tumor, for which the preoperative and intraoperative definitive diagnosis is quite challenging. We present the clinical, radiological and pathologic features of two primary pancreatic schwannomas identified in our pathology database over a period of 30 years at our tertiary care hospital. To better understand the clinico-pathological and radiological features of this entity, we provide a comprehensive review of 73 cases described in the English literature, along with our two cases. This review will especially focus on preoperative and intraoperative diagnosis to assess their accuracy for pancreatic schwannoma. The three most common preoperative diagnoses based on imaging for pancreatic schwannomas were cystic neoplasm (56%), pancreatic neuroendocrine tumor (29%) and mucinous cystic neoplasm (26%). Imaging could not definitely diagnose pancreatic schwannoma in any of the reported cases. To obtain a definite diagnosis before surgery, 25 cases underwent imaging-guided fine-needle aspiration (FNA)/biopsy, of which 60% were correctly reported as benign with definite diagnosis of pancreatic schwannoma in 48%. A higher diagnostic accuracy was observed in biopsies (71%) than FNA (37%). In addition, an intraoperative frozen section was carried out in 15 cases, and 47% were correctly diagnosed. Despite relatively low accuracy, preoperative histological assessment can be helpful in surgical managment. A core tissue specimen is recommended to improve the diagnostic accuracy in this setting.

Hydrosalpinx in patients with hysterectomy without salpingo-oophorectomy referred for pelvic magnetic resonance imaging.

OBJECTIVE: Women with ovarian-sparing hysterectomy before 2007 are more likely to have retained Fallopian tube remnants which can become fluid-filled, distended masses, potentially mistaken for a cystic adnexal neoplasm on imaging. Here we assess the prevalence and appearance of hydrosalpinx in women with ovarian-sparing hysterectomy prior to 2007 referred for pelvic MRI. METHODS: A total of 3044 consecutive pelvic MRI exams performed over a two-year period (2003-2004) were selected from our radiology database and retrospectively reviewed. Examinations performed on male patients (N = 858), duplicate examinations on the same patient (N = 675) and examinations performed for MR guided biopsy (N = 1) were excluded from the study. From the remaining female pelvic MRI examinations (N = 1510), patients with hysterectomy without oophorectomy were identified. The frequency of hydrosalpinx in this population was then determined visually by two experienced radiologists and kappa analysis was then performed to assess for interobserver agreement. RESULTS: Of the 3044 pelvic MRI examinations, 1510 were performed on females and 76 (5%) of these women had ovarian-sparing hysterectomy. Of these 76 women, 14 patients (18%) had hydrosalpinx (kappa = 0.8) of which 11 were unilateral and 3 bilateral. A total of 9 of the 14 cases positive for hydrosalpinx in patients with ovarian-sparing hysterectomy were referred to MRI for evaluation of cystic adnexal masses detected on other modalities. CONCLUSION: Hydrosalpinx should be considered in the differential diagnosis of cystic adnexal lesions in women with prior hysterectomy and retained ovaries.

Comparison of Vaginal Axis in Women Who Have Undergone Hysterectomy Versus Women With an Intact Uterus.

OBJECTIVES: To compare vaginal axis and posterior cul-de-sac measurements in women who have undergone hysterectomy and women with an intact uterus. METHODS: This was a retrospective cohort study comparing magnetic resonance imaging findings in women who had undergone hysterectomy with women with an intact uterus. The primary outcome was change in the upper, middle, and lower vaginal axes relative to the pelvic inclination correction system line. Secondary outcomes included angles between the upper-middle and middle-lower vagina, depth of the posterior cul-de-sac, and total vaginal length. RESULTS: In the hysterectomy group, the middle vaginal axis was significantly more anterior as compared with the intact uterus group (61.3 degrees ± 12.7 vs 49.4 degrees ± 23.6, P = 0.01). The upper-middle and the middle-lower vaginal angles were significantly more obtuse in the hysterectomy group than the intact uterus group (112.3 degrees ± 28.7 vs 69.3 degrees ± 56.6, P = 0.01 and 145.4 degrees ± 13.2 vs 130.9 degrees ± 29.7, P = 0.02, respectively). The mean depth of the posterior cul-de-sac and the total vaginal length were significantly shorter in the hysterectomy group than the intact uterus group (5.5 mm ± 7.6 vs 21.8 mm ± 11.9, P < 0.0001 and 78.7 mm ± 3.9 vs 100 mm ± 15.9, P < 0.001, respectively). CONCLUSIONS: The vaginal anatomy of women who have undergone hysterectomy differs significantly from that of women with an intact uterus.

CT and MR Imaging Features of Artificial Urinary Sphincters, Penile Prostheses, and Other Devices in the Male Lower Genitourinary Tract.

Urinary incontinence and erectile dysfunction are relatively common conditions in the aging male population. Surgical interventions for urinary incontinence include placement of an artificial urinary sphincter (AUS), perineal sling, or sacral nerve stimulator and injections of periurethral bulking agents. Erectile dysfunction can be treated surgically with placement of a penile prosthesis. The complications of these devices can be broadly categorized as device component malposition, malfunction, and infection. This article focuses on AUSs, penile prostheses, and their complications. Familiarity with these devices and their complications allows the radiologist to effectively describe these implants in radiologic reports and to recognize complications when they occur. This article reviews the normal cross-sectional radiologic appearance of the most common implants used to surgically treat male urinary incontinence and erectile dysfunction, as well as the potential complications associated with these devices. ©RSNA, 2018.

Patterns of Discordance Between Pretransplant Imaging Stage of Hepatocellular Carcinoma and Posttransplant Pathologic Stage: A Contemporary Appraisal of the Milan Criteria.

BACKGROUND: Patients with hepatocellular carcinoma (HCC) exceeding Milan criteria on explant pathology are at increased risk of recurrence and death. Discordance between contemporary magnetic resonance imaging (MRI) and explant pathology, and preoperative characteristics predictive of discordance are not well understood. METHODS: Patients who underwent orthotopic liver transplantation for HCC after preoperative MRI were identified in a prospectively collected institutional database (January 2003 to December 2013). Patients were dichotomized to "within" or "outside" Milan criteria by both imaging and explant pathologic evaluation. Binary logistic regression and Kaplan-Meier methodology were used to identify independent predictors of imaging/pathologic discordance and its impact on posttransplant survival. RESULTS: Of 318 patients with HCC meeting Milan criteria by MRI at the time of orthotopic liver transplantation, 248 (78.0%) remained within a pathological correlate of Milan criteria on explant examination. Understaging was associated with worse median recurrence-free survival (64.0 months vs 140.0 months, P = 0.002) and overall survival (96.0 months vs 143.0 months, P = 0.005), and did not vary between patients exceeding criteria due to tumor explant greater than 5 cm, more than 3 tumor foci, or a tumor greater than 3 cm in the setting of multifocality. Discordance was independently associated with an increasing serum alpha fetal protein level (odds ratio, 2.82; 95% confidence interval, 1.37-5.79; P = 0.005). CONCLUSIONS: Underestimating HCC burden before liver transplant remains frequent despite contemporary imaging technologies. Patients with an increasing alpha fetal protein before transplantation may benefit from more frequent testing or novel neoadjuvant therapies.

Characterizing and eliminating errors in enhancement and subtraction artifacts in dynamic contrast-enhanced breast MRI: Chemical shift artifact of the third kind.

PURPOSE: To characterize errors in enhancement in breast dynamic contrast-enhanced (DCE) MRI studies as a function of echo time and determine the source of dark band artifacts in clinical subtraction images. METHODS: Computer simulations, oil and water substitute (methylene chloride), as well as an American College of Radiology quality control phantom were tested. Routine clinical DCE breast MRI study was bracketed with (accelerated) in-phase DCE acquisitions in five patients. RESULTS: Simulation results demonstrated up to -160% suppression of the expected enhancement caused by differential enhancement of fat and water. Two-dimensional gradient-recalled echo and fat-suppressed 3D GRE phantom imaging confirmed the simulation results and showed that fat suppression does not eliminate the artifact. In vivo in-phase DCE images showed increased enhancement consistent with predictions and also confirmed increased spatial blurring on in-phase 3D gradient-recalled echo images. Combined multi-dimensional partial Fourier and parallel imaging provided a time-equivalent in-phase DCE MRI acquisition. CONCLUSION: Errors in expected enhancement occur in DCE breast MRI subtraction images because of differential enhancement of fat and water and incomplete fat signal suppression. These errors can lead to artificial suppression of enhancement as well as dark band artifacts on subtraction images. These artifacts can be eliminated with a time-equivalent in-phase fat-suppressed 3D gradient-recalled echo sequence. Understanding chemical shift artifact of the third kind, a unique artifact of artificial enhancement suppression in the presence of intravoxel fat and water signal, will aid DCE breast MRI image interpretation. In-phase acquisitions (combined with simultaneous minimum echo time or opposed-phase echoes) may facilitate qualitative, quantitative and longitudinal analysis of contrast enhancement. Magn Reson Med 79:2277-2289, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Utility of MRI to Differentiate Clear Cell Renal Cell Carcinoma Adrenal Metastases From Adrenal Adenomas.

OBJECTIVE: The purpose of this study is to compare MRI features of clear cell renal cell carcinoma (RCC) adrenal metastases and adenomas. MATERIALS AND METHODS: Fifteen clear cell RCC adrenal metastases imaged with MRI were compared to 29 consecutive adenomas between 2006 and 2015. Two blinded radiologists assessed homogeneity (homogeneous vs heterogeneous), signal intensity (SI) decrease on chemical-shift MRI, and T2-weighted SI (isointense, mildly hyperintense, or markedly hyperintense) relative to muscle. A third blinded radiologist measured the chemical-shift SI index, adrenal-to-spleen SI ratio, T2-weighted SI ratio, AUC for contrast-enhanced MRI, and histogram analysis. Analyses were performed using chi-square, linear regression, ROC, and logistic regression modeling. RESULTS: Clear cell RCC metastases were larger than adenomas (mean [± SD], 5.0 ± 4.2 cm [range, 1.1-15 cm] vs 2.0 ± 0.7 cm [range, 1.2-3.7 cm]; p < 0.0001). Subjectively, 33.3% (5/15) of metastases and 68.9% (20/29) of adenomas showed an SI decrease on chemical-shift MRI (p = 0.0421; κ = 0.76). Chemical-shift SI index (mean, 9.2% ± 20.6%; range, -30.0% to 57.9%) and adrenal-to-spleen SI ratio (0.94 ± 0.23 [range, 0.44-1.33]) for metastases differed significantly from those for adenomas (47.3% ± 27.8% [range, -9.4% to 86%] and 0.52 ± 0.28 [range, 0.13-1.11], respectively) (p < 0.0001). Twenty percent (3/15) of metastases had chemical-shift SI index in the adenoma range (> 16.5%). Metastases had higher T2-weighted SI than did adenomas, both quantitatively (5.1 ± 3.0 [range, 1.5-10.6] vs 1.8 ± 0.8 [range, 0.5-3.8]; p < 0.0001) and subjectively (p < 0.0001; κ = 0.89). Metastases had higher entropy than did adenomas (6.76 ± 0.61 vs 6.1 ± 0.74; p = 0.0051) and were subjectively more heterogeneous (p < 0.0001; κ = 0.86). The contrast-enhanced MRI AUC, skewness, and kurtosis did not differ between groups (p > 0.05). The ROC AUCs were 0.91 (95% CI, 0.79-1.0) for T2-weighted SI ratio and 0.85 (95% CI, 0.68-1.0) for entropy. The logistic regression model of T2-weighted SI ratio plus entropy improved accuracy (ROC AUC, 0.97; 95% CI, 0.93-1.0]) compared with either feature alone (p = 0.0215). CONCLUSION: Increased T2-weighted SI and heterogeneity are features that can differentiate clear cell RCC adrenal metastases from adenomas using quantitative and subjective analysis.

Update on CT and MRI of Adrenal Nodules.

OBJECTIVE: The objective of this article is to review the current role of CT and MRI for the characterization of adrenal nodules. CONCLUSION: Unenhanced CT and chemical-shift MRI have high specificity for lipid-rich adenomas. Dual-energy CT provides comparable to slightly lower sensitivity for the diagnosis of lipid-rich adenomas but may improve characterization of lipid-poor adenomas. Nonadenomas containing intracellular lipid pose an imaging challenge; however, nonadenomas that contain lipid may be potentially diagnosed using other imaging features. Multiphase adrenal washout CT can be used to differentiate lipid-poor adenomas from metastases but is limited for the diagnosis of hypervascular malignancies and pheochromocytoma.

MRI Evaluation of the Urothelial Tract: Pitfalls and Solutions.

OBJECTIVE: MR urography (MRU) can be an alternative to CT urography (CTU) for imaging of the kidneys, urinary bladder, and collecting systems. MRU can be a challenging examination to perform and interpret, which may result in technical and interpretive errors being made. This article highlights the pitfalls associated with MRU and discusses how to recognize and avoid them. CONCLUSION: When performed properly, MRU may provide imaging quality generally comparable to that of CTU, and it enables comprehensive evaluation of the entire urinary tract.