Two-point Dixon and six-point Dixon magnetic resonance techniques in the detection, quantification and grading of hepatic steatosis.

BACKGROUND: Hepatic steatosis is a very common problem worldwide. AIM: To assess the performance of two- and six-point Dixon magnetic resonance (MR) techniques in the detection, quantification and grading of hepatic steatosis. METHODS: A single-center retrospective study was performed in 62 patients with suspected parenchymal liver disease. MR sequences included two-point Dixon, six-point Dixon, MR spectroscopy (MRS) and MR elastography. Fat fraction (FF) estimates on the Dixon techniques were compared to the MRS-proton density FF (PDFF). Statistical tests used included Pearson's correlation and receiver operating characteristic. RESULTS: FF estimates on the Dixon techniques showed excellent correlation (≥ 0.95) with MRS-PDFF, and excellent accuracy [area under the receiver operating characteristic (AUROC) ≥ 0.95] in: (1) Detecting steatosis; and (2) Grading severe steatosis, (P < 0.001). In iron overload, two-point Dixon was not evaluable due to confounding T2* effects. FF estimates on six-point Dixon vs MRS-PDFF showed a moderate correlation (0.82) in iron overload vs an excellent correlation (0.97) without iron overload, (P < 0.03). The accuracy of six-point Dixon in grading mild steatosis improved (AUROC: 0.59 to 0.99) when iron overload cases were excluded. The excellent correlation (> 0.9) between the Dixon techniques vs MRS-PDFF did not change in the presence of liver fibrosis (P < 0.01). CONCLUSION: Dixon techniques performed satisfactorily for the evaluation of hepatic steatosis but with exceptions.

Multiparametric MR assessment of liver fat, iron, and fibrosis: a concise overview of the liver "Triple Screen".

Chronic liver disease (CLD) is a common source of morbidity and mortality worldwide. Non-alcoholic fatty liver disease (NAFLD) serves as a major cause of CLD with a rising annual prevalence. Additionally, iron overload can be both a cause and effect of CLD with a negative synergistic effect when combined with NAFLD. The development of state-of-the-art multiparametric MR solutions has led to a change in the diagnostic paradigm in CLD, shifting from traditional liver biopsy to innovative non-invasive methods for providing accurate and reliable detection and quantification of the disease burden. Novel imaging biomarkers such as MRI-PDFF for fat, R2 and R2* for iron, and liver stiffness for fibrosis provide important information for diagnosis, surveillance, risk stratification, and treatment. In this article, we provide a concise overview of the MR concepts and techniques involved in the detection and quantification of liver fat, iron, and fibrosis including their relative strengths and limitations and discuss a practical abbreviated MR protocol for clinical use that integrates these three MR biomarkers into a single simplified MR assessment. Multiparametric MR techniques provide accurate and reliable non-invasive detection and quantification of liver fat, iron, and fibrosis. These techniques can be combined in a single abbreviated MR "Triple Screen" assessment to offer a more complete metabolic imaging profile of CLD.

Tips for improving consistency of thyroid nodule interpretation with ACR TI-RADS.

Thyroid nodules are very common in the general population. Most are benign and even those that are malignant are typically slow-growing and do not require treatment. Overdiagnosis and overtreatment of thyroid nodules has resulted in significant healthcare costs. ACR TI-RADS was developed to address these concerns, and reduce the number of unnecessary biopsies and follow-up intervals. ACR TI-RADS offers a point-based risk stratification system centered on five sonographic features: consistency, echogenicity, shape, margins and echogenic foci. While the system has noticeable benefits and comparable accuracy with other available risk stratification systems (ATA, EU-TIRADS and K-TIRADS), there are inherent challenges relating to suboptimal inter-reader agreement. In this article, we include 10 educational tips that may be helpful to the ultrasound practitioner for improving the consistency of nodule interpretation with ACR TI-RADS.

Implantation subcutaneous phaeohyphomycosis caused by Rhytidhysteron rufulum: A case report.

Subcutaneous phaeohyphomycosis is caused by traumatic implantation of melanized environmental fungi. The majority of cases occur in tropical areas of the world or are associated with travel from these regions. Herein, we describe a rare case of subcutaneous phaeohyphomycosis caused by Rhytidhysteron rufulum in an immunocompetent Somalia-born patient. The use of molecular diagnostics as an essential tool for identification of rare fungal pathogens is highlighted.

Effect of training on resident inter-reader agreement with American College of Radiology Thyroid Imaging Reporting and Data System.

BACKGROUND: The American College of Radiology Thyroid Imaging Reporting and Data System (ACR TI-RADS) was introduced to standardize the ultrasound characterization of thyroid nodules. Studies have shown that ACR-TIRADS reduces unnecessary biopsies and improves consistency of imaging recommendations. Despite its widespread adoption, there are few studies to date assessing the inter-reader agreement amongst radiology trainees with limited ultrasound experience. We hypothesize that in PGY-4 radiology residents with no prior exposure to ACR TI-RADS, a statistically significant improvement in inter-reader reliability can be achieved with a one hour training session. AIM: To evaluate the inter-reader agreement of radiology residents in using ACR TI-RADS before and after training. METHODS: A single center retrospective cohort study evaluating 50 thyroid nodules in 40 patients of varying TI-RADS levels was performed. Reference standard TI-RADS scores were established through a consensus panel of three fellowship-trained staff radiologists with between 1 and 14 years of clinical experience each. Three PGY-4 radiology residents (trainees) were selected as blinded readers for this study. Each trainee had between 4 to 5 mo of designated ultrasound training. No trainee had received specialized TI-RADS training prior to this study. Each of the readers independently reviewed the 50 testing cases and assigned a TI-RADS score to each case before and after TI-RADS training performed 6 wk apart. Fleiss kappa was used to measure the pooled inter-reader agreement. The relative diagnostic performance of readers, pre- and post-training, when compared against the reference standard. RESULTS: There were 33 females and 7 males with a mean age of 56.6 ± 13.6 years. The mean nodule size was 19 ± 14 mm (range from 5 to 63 mm). A statistically significant superior inter-reader agreement was found on the post-training assessment compared to the pre-training assessment for the following variables: 1. "Shape" (k of 0.09 [slight] pre-training vs 0.67 [substantial] post-training, P < 0.001), 2. "Echogenic foci" (k of 0.28 [fair] pre-training vs 0.45 [moderate] post-training, P = 0.004), 3. 'TI-RADS level' (k of 0.14 [slight] pre-training vs 0.36 [fair] post-training, P < 0.001) and 4. 'Recommendations' (k of 0.36 [fair] pre-training vs 0.50 [moderate] post-training, P = 0.02). No significant differences between the pre- and post-training assessments were found for the variables 'composition', 'echogenicity' and 'margins'. There was a general trend towards improved pooled sensitivity with TI-RADS levels 1 to 4 for the post-training assessment while the pooled specificity was relatively high (76.6%-96.8%) for all TI-RADS level. CONCLUSION: Statistically significant improvement in inter-reader agreement in the assigning TI-RADS level and recommendations after training is observed. Our study supports the use of dedicated ACR TI-RADS training in radiology residents.

Diagnostic accuracy and inter-observer reliability of the O-RADS scoring system among staff radiologists in a North American academic clinical setting.

PURPOSE: The objective of this study is to evaluate the diagnostic accuracy, interobserver variability, and common lexicon pitfalls of the ACR O-RADS scoring system among staff radiologists without prior experience to O-RADS. MATERIALS AND METHODS: After independent review of the ACR O-RADS publications and 30 training cases, three fellowship-trained, board-certified staff radiologists scored 50 pelvic ultrasound exams using the O-RADS system. The diagnostic accuracy and area under receiver operating characteristic were analyzed for each reader. Overall agreement and pair-wise agreement between readers were also analyzed. RESULTS: Excellent specificities (92 to 100%), NPVs (92 to 100%), and variable sensitivities (72 to 100%), PPVs (66 to 100%) were observed. Considering O-RADS 4 and O-RADS 5 as predictors of malignancy, individual reader AUC values range from 0.94 to 0.98 (p < 0.001). Overall inter-reader agreement for all 3 readers was "very good," k = 0.82 (0.73 to 0.90, 95% CI, p < 0.001). Pair-wise agreement between readers were also "very good," k = 0.86-0.92. 14 out of 150 lesions were misclassified, with the most common error being down-scoring of a solid lesion with irregular outer contours. CONCLUSION: Even without specific training, experienced ultrasound readers can achieve excellent diagnostic performance and high inter-reader reliability with self-directed review of guidelines and cases. The study highlights the effectiveness of ACR O-RADS as a stratification tool for radiologists and supports its continued use in practice.

Hepatic hemangiomas: the various imaging avatars and its mimickers.

Hemangiomas are the most common benign tumors of the liver. These lesions are typically asymptomatic, solitary and almost always discovered incidentally, and in recent years with advances in imaging technology these lesions are being detected more frequently. Although, in majority of the cases, the imaging diagnosis of a liver hemangioma is clearly and confidently established, not all hemangiomas present with their characteristic or typical appearance on imaging. Occasionally, these lesions do present with an atypical pattern, and can be confused with other malignant lesions such as hepatocellular carcinoma, intrahepatic cholangiocarcinoma, mixed hepatocellular-cholangiocarcinoma and angiosarcoma. In this article, we review with illustrations the diverse imaging appearances of hemangiomas on the commonly used imaging modalities, as well as provide a gamut of common and uncommonly encountered hemangioma mimickers. Knowledge of the various atypical avatars of this benign lesion is important and can help one circumvent diagnostic errors, thereby potentially avoiding unnecessary surgeries.

Abdominal and pelvic radiographs of medical devices and materials- part 2: neurologic and genitourinary devices and materials.

Radiographs of the abdomen and pelvis are routinely obtained as a standard part of clinical care for the abdomen and pelvis. Brisk advances in technology over the last few decades have resulted in a multitude of medical devices and materials. Recognizing and evaluating these devices on abdominal and pelvic radiographs are critical, yet increasingly a difficult endeavor. In addition, multiple devices serving different purposes may have a similar radiographic appearance and position causing confusion for the interpreting radiologist. The role of the radiologist is to not only identify accurately these medical objects, but also to confirm for their accurate placement and to recognize any complications that could affect patient care, management or even be potentially life threatening. An extensive online search of literature showed our review article to be the most comprehensive work on medical devices and materials of the abdomen and pelvis, and in this second part of our two-part series, we discuss in depth about the neurologic and genitourinary devices seen on abdominal and pelvic radiographs.

Abdominal and pelvic radiographs of medical devices and materials-Part 1: gastrointestinal and vascular devices and materials.

When compared with chest radiographs, medical devices of the abdomen and pelvis are less frequently seen. However, with recent advances in technology the interpreting radiologists are seeing more medical objects on these radiographs. The identification of these devices and materials are crucial for not only enabling the radiologist to understand the underlying background pathology but also for evaluating any related complications. An online survey of literature showed our review article to be the most detailed. In this first part of our two-part series, we discuss about the various gastrointestinal and vascular devices and materials seen on abdominal and pelvic radiographs.

Accuracy of findings in the diagnosis of uterine adenomyosis on ultrasound.

PURPOSE: MRI is the current imaging gold standard to diagnose adenomyosis, but access is often limited by high costs and availability. Transvaginal ultrasound provides a cost-effective, accurate and readily available alternative. The objective of our study was to determine the diagnostic accuracy of commonly described sonographic findings in predicting uterine adenomyosis. METHODS: This retrospective study evaluated 649 MRI studies performed to investigate adenomyosis with a preceding transvaginal ultrasound within 12 months between 2013 and 2018. Two blinded reviewers assessed the presence or absence of six sonographic features: bulky uterus, heterogeneous myometrium, streaky myometrium, myometrial cysts, endometrial-myometrial interface ill-definition, and echogenic linear striations. The sensitivity, specificity, positive and negative predictive values of these features were calculated individually and in combination when compared to MRI as the standard of reference. RESULTS: Adenomyosis was found in 315 (48.5%) cases on MRI. Ultrasound had a high specificity of 91.8% (95% CI 88.4 to 94.6%) but was less sensitive (36.8% (95% CI 31.5 to 42.4%)) for detecting adenomyosis. Comorbid fibroids or focal adenomyosis did not affect diagnostic accuracy. All six variables were significantly more common in patients with adenomyosis compared to those without. Individually, 'bulky uterus' and 'heterogenous myometrium' each demonstrated a mean sensitivity and specificity > 50%. The best dual combined variables were 'bulky uterus' + 'ill definition of the endometrial-myometrial interface' (sensitivity 39%, specificity 91%). The best triple combined variables were 'bulky uterus', 'heterogeneous myometrium' + 'ill definition of the endometrial-myometrial interface' (sensitivity 38%, specificity 93%). CONCLUSION: Transvaginal ultrasound is highly specific for diagnosing uterine adenomyosis, providing a cost-effective and readily available alternative to MRI.

A practical imaging classification for the non-invasive differentiation of renal cell carcinoma into its main subtypes.

AIM: Renal cell carcinoma (RCC) is a heterogeneous disease which encompasses various subtypes that exhibit differing biologic behavior and imaging findings. Non-invasive subtype differentiation by imaging facilitates prognostication and treatment selection. The aim of the study was to evaluate the performance of a diagnostic imaging key based on tumor morphology, T2 signal intensity on MRI, and tumor vascularity for differentiating RCC into its subtypes. MATERIALS AND METHODS: Using a custom-designed diagnostic imaging key, three blinded fellowship-trained abdominal radiologists independently evaluated the cross-sectional imaging of 50 histologically proven RCCs and categorized these into subtypes in two sessions. The diagnostic performance of the imaging key was evaluated and compared to the baseline performance without the key. RESULTS: The 50 RCCs comprised 20 (40%) clear cell, 17 (34%) papillary, and 13 (26%) chromophobe tumors. All expert readers demonstrated an improvement in diagnostic accuracy by an average of 5.3% with the use of the key. The readers showed good to excellent diagnostic performance for clear cell RCC (area under the receiver operating curve, AUROC of 0.86-0.91) and papillary RCC (AUROC of 0.82-0.87), and fair performance with chromophobe RCC (AUROC of 0.67-0.77). The Reader-to-SOR (standard of reference) agreement increased from 0.53 (moderate) to 0.67 (good) with the use of the key. CONCLUSION: The diagnostic imaging key facilitates RCC subtype characterization and can be used as a decision support tool.

Glutathione transferase P1 interacts strongly with the inner leaflet of the plasma membrane.

GSH transferases (GSTs) are a superfamily of proteins best known for detoxifying harmful electrophilic compounds by catalyzing their conjugation with GSH. GSTP1 is the most prevalent and widely distributed GST in human tissues, helping to detoxify a diverse array of carcinogens and drugs. In contrast with its protective role, overexpression of GSTP1 in a variety of malignancies is associated with a poor prognosis due to failure of chemotherapy. Although GSTP1 is classified as a cytosolic GST, we discovered previously that it is associated with the plasma membrane of the small cell lung cancer cell lines, H69 and H69AR. In the current study, endogenous and overexpressed GSTP1 in human embryonic kidney (HEK) 293 and MCF-7 cell lines, respectively, were found also to associate with the plasma membrane, indicating that this interaction is not unique to H69 and H69AR cells. GSTP1 immunostaining in HEK293 and MCF7-GSTP1 cells only occurred under permeabilized conditions, suggesting that GSTP1 is associated with the intracellular surface of the plasma membrane. Cell surface biotinylation studies confirmed this finding. Immunogold electron microscopy revealed the presence of GSTP1 in close proximity to the plasma membrane. GSTP1 was not dissociated from plasma membrane sheets by high salt [potassium iodide (KI; 1 M) or KI/EDTA (1 M/2 mM)] or alkaline Na(2)CO(3) (100 mM, pH 11.4), conditions known to strip peripherally associated membrane proteins. Thus, we report for the first time that GSTP1 is associated with the inner leaflet of the plasma membrane through a remarkably strong interaction.