A Multicenter Assessment of Interreader Reliability of LI-RADS Version 2018 for MRI and CT.

Background Various limitations have impacted research evaluating reader agreement for Liver Imaging Reporting and Data System (LI-RADS). Purpose To assess reader agreement of LI-RADS in an international multicenter multireader setting using scrollable images. Materials and Methods This retrospective study used deidentified clinical multiphase CT and MRI and reports with at least one untreated observation from six institutions and three countries; only qualifying examinations were submitted. Examination dates were October 2017 to August 2018 at the coordinating center. One untreated observation per examination was randomly selected using observation identifiers, and its clinically assigned features were extracted from the report. The corresponding LI-RADS version 2018 category was computed as a rescored clinical read. Each examination was randomly assigned to two of 43 research readers who independently scored the observation. Agreement for an ordinal modified four-category LI-RADS scale (LR-1, definitely benign; LR-2, probably benign; LR-3, intermediate probability of malignancy; LR-4, probably hepatocellular carcinoma [HCC]; LR-5, definitely HCC; LR-M, probably malignant but not HCC specific; and LR-TIV, tumor in vein) was computed using intraclass correlation coefficients (ICCs). Agreement was also computed for dichotomized malignancy (LR-4, LR-5, LR-M, and LR-TIV), LR-5, and LR-M. Agreement was compared between research-versus-research reads and research-versus-clinical reads. Results The study population consisted of 484 patients (mean age, 62 years ± 10 [SD]; 156 women; 93 CT examinations, 391 MRI examinations). ICCs for ordinal LI-RADS, dichotomized malignancy, LR-5, and LR-M were 0.68 (95% CI: 0.61, 0.73), 0.63 (95% CI: 0.55, 0.70), 0.58 (95% CI: 0.50, 0.66), and 0.46 (95% CI: 0.31, 0.61) respectively. Research-versus-research reader agreement was higher than research-versus-clinical agreement for modified four-category LI-RADS (ICC, 0.68 vs 0.62, respectively; P = .03) and for dichotomized malignancy (ICC, 0.63 vs 0.53, respectively; P = .005), but not for LR-5 (P = .14) or LR-M (P = .94). Conclusion There was moderate agreement for LI-RADS version 2018 overall. For some comparisons, research-versus-research reader agreement was higher than research-versus-clinical reader agreement, indicating differences between the clinical and research environments that warrant further study. © RSNA, 2023 Supplemental material is available for this article. See also the editorials by Johnson and Galgano and Smith in this issue.

Magnetic Resonance Imaging Virtual Biopsy of Common Solid Renal Masses-A Pictorial Review.

ABSTRACT: The expanded application of radiologic imaging resulted in an increased incidence of renal masses in the recent decade. Clinically, it is difficult to determine the malignant potential of the renal masses, thus resulting in complex management. Image-guided biopsies are the ongoing standard of care to identify molecular variance but are limited by tumor accessibility and heterogeneity. With the evolving importance of individualized cancer therapies, radiomics has displayed promising results in the identification of tumoral mutation status on routine imaging. This article discusses how magnetic resonance imaging features can guide a radiologist toward identifying renal mass characteristics.

Imaging Update for Hereditary Abdominopelvic Neuroendocrine Neoplasms.

ABSTRACT: Neuroendocrine neoplasms have shown a linear increase in incidence and prevalence in recent decades, primarily due to improved cross-sectional imaging, expanded use of endoscopic procedures, and advanced genetic analysis. However, diagnosis of hereditary neuroendocrine tumors is still challenging because of heterogeneity in their presentation, the variety of tumor locations, and multiple associated syndromes. Radiologists should be familiar with the spectrum of these tumors and associated hereditary syndromes. Furthermore, as the assessment of multiple tumor elements such as morphology, biochemical markers, and presence of metastatic disease are essential for the treatment plan, conventional anatomic and functional imaging methods are fundamental in managing and surveilling these cases. Our article illustrates the role of different cross-sectional imaging modalities in diagnosing and managing various hereditary abdominopelvic neuroendocrine tumors.

Comparison of Conventional and Triple Bolus Computerized Tomographic Urography Protocols for Radiation Dose Reduction in Hematuria Evaluation: A Randomized Controlled Trial.

PURPOSE: Computerized tomographic urography is the diagnostic tool of choice for evaluating hematuria. In keeping with the ALARA (As Low As Reasonably Achievable) principle, we evaluated a triple bolus computerized tomography protocol designed to reduce radiation exposure. MATERIALS AND METHODS: Patients with macroscopic or microscopic hematuria were prospectively randomized to conventional computerized tomography (100) or triple bolus computerized tomography (100). The triple bolus computerized tomography protocol entails 2 scans: pre-contrast scan followed by 3 contrast injections at 40 seconds, 60 seconds and 20 minutes prior to the second scan to capture all 3 phases. The conventional computerized tomography protocol requires 4 scans: pre-contrast scan, and 3 post-contrast scans at the corticomedullary, nephrographic and excretory phases. Radiation exposure and the detection of urological pathology were recorded based on radiology reports. RESULTS: There were no differences in patient demographics or body mass index between the 2 groups. Triple bolus computerized tomography exposed patients to 33% less radiation (1,715 vs 1,145 mGy*cm for conventional vs triple bolus computerized tomography; p <0.001). For macroscopic hematuria, the pathology detection rates were 70% for triple bolus and 73% for conventional computerized tomography (p=0.72). For microscopic hematuria, the detection rates were 59% for triple bolus and 50% for conventional computerized tomography (p=0.68). In both groups, the rates of detection of urolithiasis, renal cysts, urological masses, bladder pathology and prostate pathology were no different between triple bolus and conventional computerized tomography. CONCLUSIONS: In both the settings of macroscopic and microscopic hematuria evaluation, triple bolus computerized tomography significantly reduces radiation exposure while providing equivalent detection of genitourinary pathology compared to conventional computerized tomography. The ability to detect upper tract filling defects was not specifically tested.

Magnetic Resonance Imaging Evaluation of Ectopic Pregnancy: A Value-Added Review.

ABSTRACT: Ectopic pregnancy (EP) is a known cause of maternal mortality and may be misdiagnosed in up to 50% of pregnant female individuals (Ann Emerg Med. 1996;28(1):10-17). Magnetic resonance imaging, with its superior soft tissue resolution, is a valuable alternative diagnostic modality to diagnose EP when transvaginal ultrasound results are inconclusive. Although an extrauterine gestational sac is the most specific finding, there are other key MRI findings that can aid in diagnosing EP. As availability of MRI access in the emergency department setting increases across the nation, its utility in women with a positive pregnancy test has also increased. Specific MRI findings that are diagnostic of EP include absence of intrauterine pregnancy, adnexal mass separate from the ovary, and hemoperitoneum. In addition, intrauterine ectopic locations, especially intramural, cornual, and cervical pregnancies, can be diagnosed with increased accuracy with the help of MRI. Magnetic resonance imaging is also useful in excluding potential mimics of EP, including adnexal cysts, ovarian neoplasms, and fibroids. In summary, providing an accurate diagnosis and determining the precise location of an EP, which is supported by the use of MRI, is imperative for guiding a patient's treatment to prevent a potentially fatal outcome.

"Renal emergencies: a comprehensive pictorial review with MR imaging".

Superior soft-tissue contrast and high sensitivity of magnetic resonance imaging (MRI) for detecting and characterizing disease may provide an expanded role in acute abdominal and pelvic imaging. Although MRI has traditionally not been exploited in acute care settings, commonly used in biliary obstruction and during pregnancy, there are several conditions in which MRI can go above and beyond other modalities in diagnosis, characterization, and providing functional and prognostic information. In this manuscript, we highlight how MRI can help in further assessment and characterization of acute renal emergencies. Currently, renal emergencies are predominantly evaluated with ultrasound (US) or computed tomography (CT) scanning. US may be limited by various patient factors and technologist experience while CT imaging with intravenous contrast administration can further compromise renal function. With the advent of rapid, robust non-contrast MRI, and magnetic resonance angiography (MRA) imaging studies with short scan times, free-breathing techniques, and lack of ionization radiation, the utility of MRI for renal evaluation might be superior to CT not only in diagnosing an emergent renal process but also by providing functional and prognostic information. This review outlines the clinical manifestations and the key imaging findings for acute renal processes including acute renal infarction, hemorrhage, and renal obstruction, among other entities, to highlight the added value of MRI in evaluating the finer nuances in acute renal emergencies.

Variability of the Positive Predictive Value of PI-RADS for Prostate MRI across 26 Centers: Experience of the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel.

Background Prostate MRI is used widely in clinical care for guiding tissue sampling, active surveillance, and staging. The Prostate Imaging Reporting and Data System (PI-RADS) helps provide a standardized probabilistic approach for identifying clinically significant prostate cancer. Despite widespread use, the variability in performance of prostate MRI across practices remains unknown. Purpose To estimate the positive predictive value (PPV) of PI-RADS for the detection of high-grade prostate cancer across imaging centers. Materials and Methods This retrospective cross-sectional study was compliant with the HIPAA. Twenty-six centers with members in the Society of Abdominal Radiology Prostate Cancer Disease-focused Panel submitted data from men with suspected or biopsy-proven untreated prostate cancer. MRI scans were obtained between January 2015 and April 2018. This was followed with targeted biopsy. Only men with at least one MRI lesion assigned a PI-RADS score of 2-5 were included. Outcome was prostate cancer with Gleason score (GS) greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2). A mixed-model logistic regression with institution and individuals as random effects was used to estimate overall PPVs. The variability of observed PPV of PI-RADS across imaging centers was described by using the median and interquartile range. Results The authors evaluated 3449 men (mean age, 65 years ± 8 [standard deviation]) with 5082 lesions. Biopsy results showed 1698 cancers with GS greater than or equal to 3+4 (International Society of Urological Pathology grade group ≥2) in 2082 men. Across all centers, the estimated PPV was 35% (95% confidence interval [CI]: 27%, 43%) for a PI-RADS score greater than or equal to 3 and 49% (95% CI: 40%, 58%) for a PI-RADS score greater than or equal to 4. The interquartile ranges of PPV at these same PI-RADS score thresholds were 27%-44% and 27%-48%, respectively. Conclusion The positive predictive value of the Prostate Imaging and Reporting Data System was low and varied widely across centers. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Milot in this issue.

Multiple Endocrine Neoplasia: Spectrum of Abdominal Manifestations.

OBJECTIVE. Multiple endocrine neoplasia (MEN) syndromes are autosomal-dominant genetic disorders that predispose two or more organs of the endocrine system to tumor development. Although the diagnosis relies on clinical and serologic findings, imaging provides critical information for surgical management with the ultimate goal of complete tumor resection. CONCLUSION. This article reviews abdominal neoplasms associated with the various subtypes of MEN syndromes, with a focus on clinical presentation and characteristic imaging features.

Calcified Splenic Lesions: Pattern Recognition Approach on CT With Pathologic Correlation.

OBJECTIVE. Incidental splenic lesions, often found on CT images of the abdomen, may often be ignored or mischaracterized. Calcified splenic lesions are often presumed to be granulomas; however, understanding the broader differential diagnostic considerations can be useful. CONCLUSION. Determining the cause of splenic lesions is essential to guide appropriate management; the pattern of calcification together with other imaging and clinical findings can aid with differentiation.

CT texture analysis in the differentiation of major renal cell carcinoma subtypes and correlation with Fuhrman grade.

OBJECTIVE: CT texture analysis (CTTA) using filtration-histogram-based parameters has been associated with tumor biologic correlates such as glucose metabolism, hypoxia, and tumor angiogenesis. We investigated the utility of these parameters for differentiation of clear cell from papillary renal cancers and prediction of Fuhrman grade. METHODS: A retrospective study was performed by applying CTTA to pretreatment contrast-enhanced CT scans in 290 patients with 298 histopathologically confirmed renal cell cancers of clear cell and papillary types. The largest cross section of the tumor on portal venous phase axial CT was chosen to draw a region of interest. CTTA comprised of an initial filtration step to extract features of different sizes (fine, medium, coarse spatial scales) followed by texture quantification using histogram analysis. RESULTS: A significant increase in entropy with fine and medium spatial filters was demonstrated in clear cell RCC (p = 0.047 and 0.033, respectively). Area under the ROC curve of entropy at fine and medium spatial filters was 0.804 and 0.841, respectively. An increased entropy value at coarse filter correlated with high Fuhrman grade tumors (p = 0.01). The other texture parameters were not found to be useful. CONCLUSION: Entropy, which is a quantitative measure of heterogeneity, is increased in clear cell renal cancers. High entropy is also associated with high-grade renal cancers. This parameter may be considered as a supplementary marker when determining aggressiveness of therapy. KEY POINTS: • CT texture analysis is easy to perform on contrast-enhanced CT. • CT texture analysis may help to separate different types of renal cancers. • CT texture analysis may enhance individualized treatment of renal cancers.

Ovarian Cancer Genetics and Implications for Imaging and Therapy.

Ovarian cancer is the second most common gynecologic malignancy in the United States. Ovarian cancer has a dismal prognosis when diagnosed at an advanced stage. Therapy for these cancers is determined not only by stage but also by their heterogeneous pathologic features, genetic mutations, and biology. In this review, we will discuss types of epithelial ovarian cancer, and their associated genetic mutations and the implications for imaging and treatment.

Significance and Prevalence of Haziness Surrounding the Hepatic Artery and Celiac Axis on Computed Tomographic Imaging After Pancreaticoduodenectomy.

PURPOSE: This study was conducted to assess the prevalence and significance of "haziness" around the hepatic artery and celiac axis in patients after pancreaticoduodenectomy. METHODS: This retrospective study was conducted on 116 patients who underwent pancreaticoduodenectomy or a similar procedure and had no clinical evidence of tumor recurrence or malignancy within 2 years from the date of surgery. RESULTS: Most images exhibited at least mild to moderate haziness around the hepatic artery and celiac axis. Patients with benign vs malignant results on formal pathology had no significant difference in severity of findings. Haziness remained in the mild to moderate range 2 years after surgery. CONCLUSIONS: Mild to moderate soft tissue stranding with increased attenuation around the hepatic artery and celiac axis is a common finding after pancreaticoduodenectomy that may persist for years after surgery. Such haziness alone has low specificity for tumor recurrence and should not be regarded as an indicator of malignancy.

Computed Diffusion Weighted Imaging of the Liver Using Extrapolation Technique in Patients Who Underwent Liver Transplantation With Hepatocellular Carcinomas: Initial Experience and Feasibility Study.

OBJECTIVE: This study aimed to evaluate the feasibility and image quality of computed diffusion weighted imaging (DWI) of the liver in patients with hepatocellular carcinoma (HCC). METHODS: Twenty-four patients who underwent liver transplantation with HCC were enrolled. Computed DWI was synthesized for b-values of 800 (cDWI800) and 1200 s/mm (cDWI1200) using directly acquired DWI with b-values of 0, 50, and 500 s/mm. Signal intensity of HCC, background liver, and contrast-to-noise ratio were evaluated for directly acquired DWI of 800 s/mm (dDWI800), cDWI800, and cDWI1200. Two radiologists evaluated the image quality for contrast between HCC and liver, suppression of background signal and T2 shine-through, and overall image quality. RESULTS: cDWI1200 showed the lowest contrast-to-noise ratio. Qualitative scores for background suppression and decreased T2 shine-through were highest for cDWI1200. However, contrast between HCC and background liver was worst in cDWI1200. CONCLUSIONS: In computed DWI of high b-values, contrast between HCC and background liver was very low.

MRI of Small Hepatocellular Carcinoma: Typical Features Are Less Frequent Below a Size Cutoff of 1.5 cm.

OBJECTIVE: The purposes of this study were to analyze MRI features of small hepatocellular carcinomas (HCCs) on the basis of size and to evaluate the difference in frequency of typical radiologic hallmarks of HCC (arterial enhancement and washout) according to the tumor size. MATERIALS AND METHODS: Enrolled were 86 patients with 110 HCCs 3 cm or smaller who underwent surgical resection or transplantation. Two radiologists reviewed gadoxetic acid-enhanced MRI features for signal intensity of T2-weighted and T1-weighted imaging, diffusion restriction, presence of arterial enhancement, washout on portal and transitional phases, and signal intensity on the hepatobiliary phase. ROC curve analysis was performed to determine the optimal HCC cutoff size for radiologic hallmarks of HCC. Tumors were divided into two groups by cutoff size, and the frequencies of MRI features were assessed. RESULTS: On ROC analysis, the optimal cutoff for radiologic hallmarks of HCC was 1.5 cm in independent and consensus reviews by two radiologists. HCCs smaller than 1.5 cm showed typical finding of HCC less frequently than HCCs 1.5 cm or larger in diameter. In subgroup analyses, HCCs with diameters between 1 and 1.5 cm showed similar MRI findings to HCCs with diameters 1 cm or less but significantly different findings compared with HCCs with diameters from 1.5 to 2 cm and 2-3 cm. CONCLUSION: HCCs smaller than 1.5 cm in size less frequently showed MRI findings seen typically in larger HCCs. Therefore, small HCCs are harder to detect with certainty not only because of small size but also because of the lower frequency of typical MRI findings.

Preoperative Computed Tomography Assessment for Perinephric Fat Invasion: Comparison With Pathological Staging.

OBJECTIVE: The aim of this study was to assess the accuracy of computed tomography (CT) imaging in diagnosing perinephric fat (PNF) invasion in patients with renal cell carcinoma. METHODS: We retrospectively reviewed the medical records and preoperative CT images of 161 patients (105 men and 56 women) for pT1-pT3a renal cell carcinoma. We analyzed the predictive accuracy of CT criteria for PNF invasion stratified by tumor size. We determined the predictive value of CT findings in diagnosing PNF invasion using logistic regression analysis. RESULTS: The overall accuracy of perinephric (PN) soft-tissue stranding, peritumoral vascularity, increased density of the PNF, tumoral margin, and contrast-enhancing soft-tissue nodule to predict PNF invasion were 56%, 59%, 35%, 80%, and 87%, respectively. Perinephric soft-tissue stranding and peritumoral vascularity showed high sensitivity but low specificity regardless of tumor size. A contrast-enhancing soft-tissue nodule showed low sensitivity but high specificity in predicting PNF invasion. Among tumors 4 cm or less, PN soft-tissue stranding showed 100% sensitivity and 70% specificity, and tumor margin showed 100% sensitivity and 98% specificity. Among CT criteria for PNF invasion, PN soft-tissue stranding was chosen as the only significant factor for assessing PNF invasion by logistic regression analysis. CONCLUSIONS: Computed tomography does not seem to reliably predict PNF invasion. However, PN soft-tissue stranding was shown to be the only significant factor for predicting PNF invasion, which showed good accuracy with high sensitivity and high specificity in tumors 4 cm or less.

The Volume of the Spleen and Its Correlates after Acute Stroke.

BACKGROUND: Animal studies describe changes in the spleen following a stroke, with an immediate reduction in volume associated with changes in the counts of specific blood white blood cell (WBCs). This brain-spleen cell cycling after stroke affects systemic inflammation and the brain inflammatory milieu and may be a target for emerging therapeutic studies. This study aimed to evaluate features of this brain-spleen model in human patients admitted for acute stroke. METHODS: Medical and imaging records were retrospectively reviewed for 82 consecutive patients admitted for acute stroke in whom an abdominal computed tomography scan was performed. RESULTS: Mean ± SD splenic volume was 224.5 ± 135.5 cc. Splenic volume varied according to gender (P = .014) but not stroke subtype (ischemic versus hemorrhagic, P = .76). The change in splenic volume over time was biphasic (P = .04), with splenic volumes initially decreasing over time, reaching a nadir 48 hours after stroke onset, then increasing thereafter. Splenic volume was related inversely to percent blood lymphocytes (r = -.36, P = .001) and positively to percent blood neutrophils (r = .30, P = .006). CONCLUSIONS: Current results support that several features of brain-spleen cell cycling after stroke described in preclinical studies extend to human subjects, including the immediate contraction of splenic volume associated with proportionate changes in blood WBC counts. Splenic volume may be useful as a biomarker of systemic inflammatory events in clinical trials of interventions targeting the immune system after stroke.

CT of Atypical and Uncommon Presentations of Hepatocellular Carcinoma.

OBJECTIVE: The purpose of this article is to familiarize radiologists with uncommon presentations of hepatocellular carcinoma (HCC) with an emphasis on the CT spectrum of atypical appearances. CONCLUSION: HCC is the fifth most common neoplasm worldwide and the second most common cause of cancer-related death. In many cases, HCC can be confidently diagnosed with noninvasive imaging. However, there are numerous unusual appearances of HCC with which the radiologist must be familiar.

Comparison of Dynamic Phase Enhancement of Hepatocellular Carcinoma Using Gadoxetate Disodium vs Gadobenate Dimeglumine.

OBJECTIVE: To determine the differences in enhancement of hepatocellular carcinoma during the first 5 minutes of postcontrast phases with gadoxetic acid (Gd-EOB-DTPA) vs gadobenate dimeglumine. METHODS: Ninety-five cirrhotic patients with hepatocellular carcinoma were examined on a 1.5-T scanner: 74 patients with Gd-BOPTA and 21 patients with Gd-EOB-DTPA. Same magnetic resonance imaging parameters were used for both groups. Gadoxetate isodium was administered at a dose of 0.025 mmol/kg; and Gd-BOPTA, at a dose of 0.1 mmol/kg. RESULTS: Mean contrast-to-noise ratios (CNR) were similar in arterial (P = 0.3), portal venous (P = 0.1), and 5-minute delayed phases (P = 0.73). The CNRs of lesions in the Gd-EOB-DTPA group were lower in arterial phase, although this did not reach statistical significance. The CNRs of Gd-EOB-DTPA during the equilibrium phase was higher (P = 0.006). CONCLUSIONS: Gadoxetate isodium resulted in lower CNR during the arterial phase and higher CNR during the portal venous, equilibrium, and 5-minute delayed phases compared with gadobenate dimeglumine using the Food and Drug Administration-approved doses; however, overall, there was no statistical significance (P = 0.077).