Faculty Bibliography

Angiomyolipoma (AML) is a benign tumor comprised of a mixture of vessels ("angio"), smooth muscle ("myo"), and adipose tissue ("lipo"). It belongs to a group of unusual mesenchymal tumors with myogenic and melanocytic differentiation known as perivascular epithelioid cell tumors. AMLs are commonly sporadic tumors but may be associated with tuberous sclerosis complex (TSC) and/or lymphangioleiomyomatosis (LAM). The imaging appearance of AMLs strongly correlates with the pathologic findings. Fat is detectable in the vast majority of AMLs, and these tumors are referred to as classic AMLs. Fat-poor AMLs are smooth muscle-predominant tumors. The smooth muscle content drives the imaging findings, which include increased attenuation on non-contrast-enhanced CT images, low T2 signal intensity, and avid enhancement. Rare histologic variants of AMLs include epithelioid AML (EAML) and AML with epithelial cysts. Most AMLs exhibit benign clinical behavior. The most important clinical complication of AML is tumor hemorrhage, which may lead to retroperitoneal hemorrhage and shock. Hemorrhage most commonly occurs in large tumors or tumors with aneurysms equal to or larger than 5 mm. Benign AMLs may also invade the renal vein and inferior vena cava. EAMLs may behave aggressively with local recurrence and metastatic spread. Treatment options for AML vary and may include observation for small classic AMLs; embolization, ablation, and/or surgical resection of large or potentially aggressive lesions; or systemic therapy in cases associated with TSC or LAM. ^©RSNA, 2025 Supplemental material is available for this article.

Endometriosis is a common condition primarily impacting women of childbearing age. Despite increasing awareness that endometriosis can be diagnosed non-invasively with the correct imaging techniques, there exists a significant delay in diagnosis, to the tune of 5-10 years. This gap can be narrowed by understanding that this is a disease that lends itself to pattern recognition, and learning to recognize the characteristic patterns on any imaging study will allow earlier diagnosis and prevent long-term complications that can occur with progressive, untreated endometriosis. The disease is often multifocal and thus can present with a wide array of nonspecific symptoms. When clinical findings do not suggest endometriosis, patients often undergo non-targeted imaging, such as chest, abdominal, or pelvic computed tomography (CT); Magnetic Resonance imaging (MRI) studies optimized for neurologic or musculoskeletal indications; or ultrasound (US) exams performed for palpable masses or nonspecific abdominal pain. Familiarity with endometriosis's characteristic patterns across organ systems and how it can masquerade as other diseases helps radiologists broaden their differential to include endometriosis, even on studies not originally aimed at its detection. This review article will describe those imaging findings of endometriosis affecting various organ systems that mimic other pathologies and will enable the reader to pause and question whether endometriosis should be included in the differential.

Renal transplantation remains the treatment of choice in patients with end-stage renal disease as the 5-year survival rates for the graft in renal transplant patients range from 72% to 99%. Despite improvements in graft survival related to increased efficacy of immunosuppression drugs and improvements in surgical technique, various complications do occur. Ultrasound is the first-line imaging modality for the evaluation of renal transplants in the immediate postoperative period and for longitudinal follow-up. Various other imaging techniques serve as complementary examinations in specific clinical settings. Angiography remains the reference standard for arterial complications and is used for nonsurgical intervention, but noninvasive CT or MR angiography could be considered prior to an invasive procedure. 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.

Noncontrast CT (NCCT) is the imaging study of choice for initial evaluation of patients with acute onset of flank pain and suspicion of stone disease without known prior stone disease. NCCT can reliably characterize the location and size of an offending ureteral calculus, identify complications, and diagnose alternative etiologies of abdominal pain. Although less sensitive in the detection of stones, ultrasound may have a role in evaluating for signs of obstruction. Radiography potentially has a role, although has been shown to be less sensitive than NCCT. For patients with known disease and recurrent symptoms of urolithiasis, NCCT remains the test of choice for evaluation. In pregnancy, given radiation concerns, ultrasound is recommended as the initial modality of choice with potential role for noncontrast MRI. In scenarios where stone disease suspected and initial NCCT is inconclusive, contrast-enhanced imaging, either with MRI or CT/CT urogram may be appropriate. 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.

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.

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.

PURPOSE/OBJECTIVE: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/CONCLUSIONS: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.

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.