Adrenal Neoplasms: Lessons from Adrenal Multidisciplinary Tumor Boards.

The radiologic diagnosis of adrenal disease can be challenging in settings of atypical presentations, mimics of benign and malignant adrenal masses, and rare adrenal anomalies. Misdiagnosis may lead to suboptimal management and adverse outcomes. Adrenal adenoma is the most common benign adrenal tumor that arises from the cortex, whereas adrenocortical carcinoma (ACC) is a rare malignant tumor of the cortex. Adrenal cyst and myelolipoma are other benign adrenal lesions and are characterized by their fluid and fat content, respectively. Pheochromocytoma is a rare neuroendocrine tumor of the adrenal medulla. Metastases to the adrenal glands are the most common malignant adrenal tumors. While many of these masses have classic imaging appearances, considerable overlap exists between benign and malignant lesions and can pose a diagnostic challenge. Atypical adrenal adenomas include those that are lipid poor; contain macroscopic fat, hemorrhage, and/or iron; are heterogeneous and/or large; and demonstrate growth. Heterogeneous adrenal adenomas may mimic ACC, metastasis, or pheochromocytoma, particularly when they are 4 cm or larger, whereas smaller versions of ACC, metastasis, and pheochromocytoma and those with washout greater than 60% may mimic adenoma. Because of its nonenhanced CT attenuation of less than or equal to 10 HU, a lipid-rich adrenal adenoma may be mimicked by a benign adrenal cyst, or it may be mimicked by a tumor with central cystic and/or necrotic change such as ACC, pheochromocytoma, or metastasis. Rare adrenal tumors such as hemangioma, ganglioneuroma, and oncocytoma also may mimic adrenal adenoma, ACC, metastasis, and pheochromocytoma. The authors describe cases of adrenal neoplasms that they have encountered in clinical practice and presented to adrenal multidisciplinary tumor boards. Key lessons to aid in diagnosis and further guide appropriate management are provided. © RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

ACR Appropriateness Criteria® Staging of Renal Cell Carcinoma: 2022 Update.

Renal cell carcinoma is a complex group of highly heterogenous renal tumors demonstrating variable biological behavior. Pretreatment imaging of renal cell carcinoma involves accurate assessment of the primary tumor, presence of nodal, and distant metastases. CT and MRI are the key imaging modalities used in the staging of renal cell carcinoma. Important imaging features that impact treatment include tumor extension into renal sinus and perinephric fat, involvement of pelvicalyceal system, infiltration into adrenal gland, involvement of renal vein and inferior vena cava, as well as the presence of metastatic adenopathy and distant metastases. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

MR Imaging of Endometriosis of the Adnexa.

Endometriosis is the presence of ectopic endometrial glands outside of the uterus. MR imaging is particularly useful for characterizing deep infiltrating endometriosis but can also be useful in characterizing endometriomas and hematosalpinges, characterizing broad ligament deposits, assessing for endometriosis-associated malignancy, and differentiating malignancy from decidualized endometriomas. Masses and cysts with hemorrhagic or proteinaceous contents can sometimes be difficult to distinguish from endometriomas. Imaging protocols should include pre-contrast T1-weighted imaging with fat saturation, T2-weighted imaging without fat saturation, opposed- and in-phase or Dixon imaging, administration of contrast media, and subtraction imaging.

Lexicon for adrenal terms at CT and MRI: a consensus of the Society of Abdominal Radiology adrenal neoplasm disease-focused panel.

PURPOSE: Substantial variation in imaging terms used to describe the adrenal gland and adrenal findings leads to ambiguity and uncertainty in radiology reports and subsequently their understanding by referring clinicians. The purpose of this study was to develop a standardized lexicon to describe adrenal imaging findings at CT and MRI. METHODS: Fourteen members of the Society of Abdominal Radiology adrenal neoplasm disease-focused panel (SAR-DFP) including one endocrine surgeon participated to develop an adrenal lexicon using a modified Delphi process to reach consensus. Five radiologists prepared a preliminary list of 35 imaging terms that was sent to the full group as an online survey (19 general imaging terms, 9 specific to CT, and 7 specific to MRI). In the first round, members voted on terms to be included and proposed definitions; subsequent two rounds were used to achieve consensus on definitions (defined as ≥ 80% agreement). RESULTS: Consensus for inclusion was reached on 33/35 terms with two terms excluded (anterior limb and normal adrenal size measurements). Greater than 80% consensus was reached on the definitions for 15 terms following the first round, with subsequent consensus achieved for the definitions of the remaining 18 terms following two additional rounds. No included term had remaining disagreement. CONCLUSION: Expert consensus produced a standardized lexicon for reporting adrenal findings at CT and MRI. The use of this consensus lexicon should improve radiology report clarity, standardize clinical and research terminology, and reduce uncertainty for referring providers when adrenal findings are present.

Prevalence of Malignancy in Adrenal Nodules With Heterogeneous Microscopic Fat on Chemical-Shift MRI: A Multiinstitutional Study.

BACKGROUND. Homogeneous microscopic fat within adrenal nodules on chemical-shift MRI (CS-MRI) is diagnostic of benign adrenal adenoma, but the clinical relevance of heterogeneous microscopic fat is not well established. OBJECTIVE. This study sought to determine the prevalence of malignancy in adrenal nodules with heterogeneous microscopic fat on dual-echo T1-weighted CS-MRI. METHODS. We performed a retrospective study of adult patients with adrenal nodules detected on MRI performed between August 2007 and November 2020 at seven institutions. Eligible nodules had a short-axis diameter of 10 mm or larger with heterogeneous microscopic fat (defined by an area of signal loss of < 80% on opposed-phase CS-MRI). Two radiologists from each center, blinded to reference standard results, determined the signal loss pattern (diffuse, two distinct parts, speckling pattern, central loss, or peripheral loss) within the nodules. The reference standard used was available for 283 nodules (pathology for 21 nodules, ≥ 1 year of imaging follow-up for 245, and ≥ 5 years of clinical follow-up for 17) in 282 patients (171 women and 111 men; mean age, 60 ± 12 [SD] years); 30% (86/282) patients had prior malignancy. RESULTS. The mean long-axis diameter was 18.7 ± 7.9 mm (range, 10-80 mm). No malignant nodules were found in patients without prior cancer (0/197; 95% CI, 0-1.5%). Four of the 86 patients with prior malignancy (hepatocellular carcinoma [HCC], renal cell carcinoma [RCC], lung cancer, or both colon cancer and RCC) (4.7%; 95% CI, 1.3-11.5%) had metastatic nodules. Detected patterns were diffuse heterogeneous signal loss (40% [114/283]), speckling (28% [80/283]), two distinct parts (18% [51/283]), central loss (9% [26/283]), and peripheral loss (4% [12/283]). Two metastases from HCC and RCC showed diffuse heterogeneous signal loss. Lung cancer metastasis manifested as two distinct parts, and the metastasis in the patient with both colon cancer and RCC showed peripheral signal loss. CONCLUSION. Presence of heterogeneous microscopic fat in adrenal nodules on CS-MRI indicates a high likelihood of benignancy, particularly in patients without prior cancer. This finding is also commonly benign in patients with cancer; however, caution is warranted when primary malignancies may contain fat or if the morphologic pattern of signal loss may indicate a collision tumor. CLINICAL IMPACT. In the absence of prior cancer, adrenal nodules with heterogeneous microscopic fat do not require additional imaging evaluation.

ACR Appropriateness Criteria® Acute Pyelonephritis: 2022 Update.

Acute pyelonephritis (APN) is a severe urinary tract infection (UTI) that has the potential to cause sepsis, shock, and death. In the majority of patients, uncomplicated APN is diagnosed clinically and is responsive to treatment with appropriate antibiotics. In patients who are high risk or when treatment is delayed, microabscesses may coalesce to form an acute renal abscess. High-risk patients include those with a prior history of pyelonephritis, lack of response to therapy for lower UTI or for APN, diabetes, anatomic or congenital abnormalities of the urinary system, infections by treatment-resistant organisms, nosocomial infection, urolithiasis, renal obstruction, prior renal surgery, advanced age, pregnancy, renal transplant recipients, and immunosuppressed or immunocompromised patients. Pregnant patients and patients with renal transplants on immunosuppression are at an elevated risk of severe complications. Imaging studies are often requested to aid with the diagnosis, identify precipitating factors, and differentiate lower UTI from renal parenchymal involvement, particularly in high-risk individuals. Imaging is usually not appropriate for the first-time presentation of suspected APN in an uncomplicated patient. The primary imaging modalities used in high-risk patients with suspected APN are CT, MRI, and ultrasound, although CT was usually not appropriate for initial imaging in a pregnant patient with no other complications. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

ACR Appropriateness Criteria® Post-Treatment Follow-up and Active Surveillance of Clinically Localized Renal Cell Carcinoma: 2021 Update.

Renal cell carcinoma (RCC) accounts for most malignant renal tumors and is considered the most lethal of all urologic cancers. For follow-up of patients with treated or untreated RCC and those with neoplasms suspected to represent RCC, radiologic imaging is the most valuable component of surveillance, as most relapses and cases of disease progression are identified when patients are asymptomatic. Understanding the strengths and limitations of the various imaging modalities for the detection of disease, recurrence, or progression is essential when planning follow-up regimens. This document addresses the appropriate imaging examinations for asymptomatic patients who have been treated for RCC with radical or partial nephrectomy or ablative therapies. It also discusses the appropriate imaging examinations for asymptomatic patients with localized biopsy-proven or suspected RCC undergoing active surveillance. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Adrenal hemorrhage and hemorrhagic masses; diagnostic workup and imaging findings.

Adrenal hemorrhage (AH) is a rare condition. It can be traumatic or non-traumatic. Most common causes are septicemia, coagulopathy or bleeding diathesis, and underlying neoplasms. Other reported less common causes of AH are COVID-19 and neonatal stress. Clinical diagnosis of AH is challenging due to its non-specific presentation and occurrence in the setting of acute medical illness. Therefore, most cases are diagnosed incidentally on imaging. Having high clinical suspicion in the proper clinical setting for AH is crucial to avoid life-threatening adrenal insufficiency that occurs in 16-50% of patients with bilateral AH. We discuss the clinical situations that predispose to AH, review the imaging features on different imaging modalities, highlight a variety of clinical cases, imaging features that should be concerning for an underlying neoplasm, and outline the potential role of interventional radiology in management of AH.

Hepatocarcinogenesis: Radiology-Pathology Correlation.

In the background of chronic liver disease, hepatocellular carcinoma develops via a complex, multistep process called hepatocarcinogenesis. This article reviews the causes contributing to the process. Emphasis is made on the imaging manifestations of the pathologic changes seen at many stages of hepatocarcinogenesis, from regenerative nodules to dysplastic nodules and then to hepatocellular carcinoma.

The humbling hemangioma: uncommon CT and MRI imaging features and mimickers of hepatic hemangiomas.

Cavernous hemangiomas are among the most common liver lesions encountered in abdominal imaging. While classical imaging characteristics usually aid the radiologist in confidently arriving at its diagnosis, atypical hemangiomas can prove to be difficult to distinguish from other more worrisome hepatic lesions such as metastases and hepatocellular carcinoma. Furthermore, some malignant lesions can display features that simulate hemangiomas. The radiologist must be aware of these pitfalls to make an accurate diagnosis, when possible.

Cross-sectional anatomy of the male pelvis.

The visceral organs of the male pelvis have complex anatomic relationships with the surrounding extraperitoneal spaces, supplying arteries and adjacent pelvic musculature. Since various neoplastic, vascular, and traumatic pathologies can often involve multiple organs and spread into adjacent pelvic spaces, a keen understanding of this intricate anatomy can help radiologists to accurately characterize findings and improve recognition of the routes in which these conditions can spread. The purpose of this review is to examine the relationships between the anatomic compartments of the pelvic extraperitoneal space, summarize the pelvic arterial anatomy, and identify the pelvic muscles that support normal genitourinary function.

Exploratory Study of Apparent Diffusion Coefficient Histogram Metrics in Assessing Pancreatic Malignancy.

PURPOSE: To evaluate whole-lesion 3D-histogram apparent diffusion coefficient (ADC) metrics for assessment of pancreatic malignancy. METHODS: Forty-two pancreatic malignancies (36 pancreatic adenocarcinoma [PDAC], 6 pancreatic neuroendocrine [PanNET]) underwent abdominal magnetic resonance imaging (MRI) with diffusion-weighted imaging before endoscopic ultrasound biopsy or surgical resection. Two radiologists independently placed 3D volumes of interest to derive whole-lesion histogram ADC metrics. Mann-Whitney tests and receiver operating characteristic analyses were used to assess metrics' diagnostic performance for lesion histology, T-stage, N-stage, and grade. RESULTS: Whole-lesion ADC histogram metrics lower in PDACs than PanNETs for both readers (P ≤ .026) were mean ADC (area under the curve [AUC] = 0.787-0.792), mean of the bottom 10th percentile (mean0-10) (AUC = 0.787-0.880), mean of the 10th-25th percentile (mean10-25) (AUC = 0.884-0.917) and mean of the 25th-50th percentile (mean25-50) (AUC = 0.829-0.829). For mean10-25 (metric with highest AUC for identifying PDAC), for reader 1 a threshold > 0.94 × 10-3 mm2/s achieved sensitivity 94% and specificity 83%, and for reader 2 a threshold > 0.82 achieved sensitivity 97% and specificity 67%. Metrics lower in nodal status ≥ N1 than N0 for both readers (P ≤ .043) were mean0-10 (AUC = 0.789-0.822) and mean10-25 (AUC = 0.800-0.822). For mean10-25 (metric with highest AUC for identifying N0), for reader 1 a threshold <1.17 achieved sensitivity 87% and specificity 67%, and for reader 2 a threshold <1.04 achieved sensitivity 87% and specificity 83%. No metric was associated with T-stage (P > .195) or grade (P > .215). CONCLUSION: Volumetric ADC histogram metrics may serve as non-invasive biomarkers of pancreatic malignancy. Mean10-25 outperformed standard mean for lesion histology and nodal status, supporting the role of histogram analysis.

Diffusion Quantification in Body Imaging.

Diffusion-weighted imaging (DWI) is increasingly incorporated into routine body magnetic resonance imaging protocols. DWI can assist with lesion detection and even in characterization. Quantitative DWI has exhibited promise in the discrimination between benign and malignant pathology, in the evaluation of the biologic aggressiveness, and in the assessment of the response to treatment. Unfortunately, inconsistencies in DWI acquisition parameters and analysis have hampered widespread clinical utilization. Focusing primarily on liver applications, this article will review the basic principles of quantitative DWI. In addition to standard mono-exponential fitting, the authors will discuss intravoxel incoherent motion and diffusion kurtosis imaging that involve more sophisticated approaches to diffusion quantification.

ACR Appropriateness Criteria Renal Cell Carcinoma Staging.

Renal cell carcinoma accounts for 2%-3% of all visceral malignancies. Preoperative imaging can provide important staging and anatomic information to guide treatment decisions. Size of the primary tumor and degree of local invasion, such as involvement of perinephric fat or renal sinus fat, and tumor thrombus in renal veins and inferior vena cava are important detriments to local staging of primary tumor. Both kidneys are assessed for presence of other synchronous lesions. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and application by the panel of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Imaging features of benign and malignant ampullary and periampullary lesions.

The ampulla of Vater is an important anatomic landmark where the common bile duct and main pancreatic duct converge in the major duodenal papilla. Imaging evaluation of the ampulla and periampullary region poses a unique diagnostic challenge to radiologists because of the region's complex and variable anatomy and the variety of lesions that can occur. Lesions intrinsic to the ampulla and involved segment of the biliary tree can be neoplastic, inflammatory, or congenital. Neoplastic lesions include ampullary adenocarcinomas and adenomas, which often are difficult to differentiate, as well as pancreatic or duodenal adenocarcinomas, pancreatic neuroendocrine tumors, and cholangiocarcinomas. Ultrasonography (US), computed tomography, magnetic resonance (MR) imaging, and MR cholangiopancreatography are commonly used to evaluate this region. Endoscopic retrograde cholangiopancreatography or endoscopic US examination may be necessary for more definitive evaluation. Periampullary conditions in the duodenum that may secondarily involve the ampulla include neoplasms, duodenitis, duodenal diverticula, and Brunner's gland hyperplasia or hamartomas. Because these lesions can exhibit a wide overlap of imaging features and subtle or nonspecific imaging findings, diagnosis is made on the basis of patient age, clinical history, and imaging and laboratory findings. Given the complexity of imaging evaluation of the ampulla and periampullary region, it is essential for radiologists to understand the variety of lesions that can occur and recognize their imaging characteristics.

De-misty-fying the mesentery: an algorithmic approach to neoplastic and non-neoplastic mesenteric abnormalities.

Mesenteric abnormalities are often incidentally discovered on cross-sectional imaging performed during daily clinical practice. Findings can range from the vague "misty mesentery" to solid masses, and the possible etiologic causes encompass a wide spectrum of underlying pathologies including infectious, inflammatory, and neoplastic processes. Unfortunately, the clinical and imaging findings are often non-specific and may overlap. This article discusses the various diseases that result in mesenteric abnormalities. It provides a framework to non-invasively differentiate these entities, when possible.