Hepatic Hemangioma: Pitfalls & Mimics, Part II
In this video lecture, we focus on variants and malignant mimics of hemangioma and discuss how to characterize these masses on ultrasound, CT and MRI. Key points include: The ultrasound “target” sign is typical for hepatic metastases and appears as a lesion with a hypoechoic periphery and echogenic center. Hemangiomas in a fatty liver may appear hypoechoic and mimic a more serious tumor but can be definitively characterized with MRI. Sclerosed or hyalinized hemangiomas contain fibrous tissue and therefore have variable enhancement and diminished T2 hyperintensity. Hemangiomas can be associated with arterioportal shunts and may be surrounded by areas of transient hepatic enhancement difference (THED) and peritumoral sparing of fatty infiltration. Differential diagnostic considerations for hepatic hemangioma include hypervascular liver metastases (including melanoma and pancreatic neuroendocrine tumor), intrahepatic mass-forming cholangiocarcinoma, and hepatic angiosarcoma. Irregular rim enhancement is not the same as interrupted peripheral nodular enhancement and should raise suspicion for malignancy in a solid mass. Metastatic tumors may progressively fill in and mimic hemangioma, but often show less pronounced “evil grey” T2 hyperintensity isointense to spleen, restrict diffusion, and have atypical enhancement. Mass-forming, peripheral intrahepatic cholangiocarcinoma can mimic hemangioma as both tumors demonstrate gradual progressive enhancement, but cholangiocarcinoma enhancement will be heterogeneous and not usually isointense to blood pool. Intrahepatic cholangiocarcinoma is heterogeneously T2 hyperintense often with central hypointensity and overlying capsular retraction but may not have associated biliary ductal dilatation. The post Hepatic Hemangioma: Pitfalls & Mimics, Part II appeared first on Radiologist Headquarters.
21 Mar 2019
Malignant Adrenal Masses
In this video lecture, we discuss the diagnosis and imaging appearance of malignant adrenal masses: adrenal metastases including collision tumor, adrenocortical carcinoma and adrenal lymphoma. Key points include: Adrenal metastases are the most common malignant lesion involving the adrenal gland. Lung carcinoma is the most common primary malignancy to metastasize to the adrenal glands. Adrenal metastases are often bilateral and greater than 3 cm in size. When malignant adrenal lesions are compared to adenomas, SUV cutoff of 3.1 has a 99% negative predictive value. Adrenal-to-liver SUV ratio cutoff value of 1.4 has a specificity of 100% in differentiating adrenal adenomas and metastases. Collision tumors are two histologically distinct tumors that abut or are near each other in the adrenal gland, and PET/CT is the best way to characterize these lesions without biopsy. An enlarging defect within adrenal signal dropout on T1-weighted opposed-phase GRE images is suspicious for a metastatic collision tumor abutting a lipid-rich adrenal adenoma. Renal cell carcinoma metastases can be slow growing and occur many years after the initial tumor presentation. Adrenocortical carcinoma has a bimodal age distribution, may be hormonally functioning and has a poor prognosis. Adrenocortical carcinoma usually presents as a large (greater than 6 cm) mass with internal hemorrhage, necrosis and sometimes calcification. Venous invasion is common with adrenocortical carcinoma. Adrenal lymphoma will be round or adreniform in shape and frequently shows restricted diffusion, a feature that can be helpful in differentiating from adrenal hyperplasia. Diffuse large B-cell lymphoma is the most common type of adrenal lymphoma, and patients usually present with B-cell symptoms and/or adrenal insufficiency. Adrenal lymphoma is usually bilateral and may invade the adjacent kidney(s). The post Malignant Adrenal Masses appeared first on Radiologist Headquarters.
31 Jan 2019
Introduction to Genitourinary Radiology, Part III
In the conclusion of this introductory series, we discuss the basics of computed tomography (CT) urography, bladder and urethral diverticula, and scrotal pathology including varicocele, epididymo-orchitis, and testicular neoplasm. Topics include: CT urography post-processing techniques: maximum intensity projection (MIP) and 3D volume-rendered (VR) imaging. Appearance of transitional cell carcinoma in the ureters and bladder on excretory phase CT mages. Papillary necrosis. Weigert-Meyer rule for duplicated collecting systems and tips to remember it. Urethral diverticula appearance on magnetic resonance imaging (MRI) and voiding cystourography (VCUG). Scrotal varicocele and the importance of recognizing the implications of right-sided versus left-sided. Acute scrotal pathology: testicular torsion and epididymo-orchitis. Differentiating seminomatous and non-seminomatous testicular neoplasms via ultrasound. The post Introduction to Genitourinary Radiology, Part III appeared first on Radiologist Headquarters.
22 Oct 2016
Imaging of Adrenal Adenomas & Incidentalomas
In this video lecture, we discuss the imaging appearance of lipid-rich and lipid-poor adrenal adenomas, explain the CT washout calculation, and review the choice of CT vs. MRI for the evaluation of adrenal nodules. Also, we compare the 2017 ACR (American College of Radiologists) Incidental Findings Committee recommendations to the AACE/AAES (American Association of Clinical Endocrinologists and American Association of Endocrine Surgeons) medical guidelines in the evaluation of adrenal incidentalomas. Key points include: 70% of adrenal adenomas will be lipid-rich with a low-density of 10 or less Hounsfield units (HU) on CT. Adrenal nodules with greater than 60% enhancement washout and greater than 40% relative washout are consistent with adenomas. Using chemical shift, MRI may be helpful in characterizing a mass which is indeterminate on non-contrast CT, particularly if the non-contrast density is less than 20-30 HU. If the non-contrast density of an adrenal nodule is greater than 20-30 HU, MRI should be avoided, as washout CT is typically the test of choice. While the AACE/AAES and ACR follow-up algorithms for adrenal nodules differ in many respects, they agree that surgical resection should be considered for adrenal masses measuring 4 cm or more in size, and that biochemical evaluation should at least be considered for most adrenal masses. The post Imaging of Adrenal Adenomas & Incidentalomas appeared first on Radiologist Headquarters.
6 Dec 2018
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5 Cases in 5 Minutes: Musculoskeletal #1
Quiz yourself with this week’s interactive video lecture as we present a total of 5 interesting musculoskeletal imaging cases followed by a diagnosis reveal and key teaching points after each case, all in just a few minutes! The post 5 Cases in 5 Minutes: Musculoskeletal #1 appeared first on Radiologist Headquarters.
6 Jun 2019
Adrenal Cysts and Myelolipomas
In this video lecture, we discuss the imaging appearance of adrenal cysts and myelolipomas, as well as differential diagnostic considerations. Key points include: Adrenal cysts typically have density of simple fluid ranging from 20 to -10 Hounsfield units (HU).Adrenal pseudocysts may be symptomatic, may have a complicated appearance and may have peripheral calcification.The “claw” sign can be helpful in differentiating adrenal from renal masses.Gastric diverticula can mimic adrenal cysts but can be differentiated by identifying communication of gastric diverticulum with adjacent stomach, as well as the presence of oral contrast and/or gas with the diverticulum. Adrenal myelolipomas are benign neoplasms that have varying degrees of macroscopic fat and hematopoietic soft tissue elements.Fat density within myelolipomas on CT ranges from -30 to -90 HU.Up to 30% of myelolipomas contain small calcifications.Unlike myelolipomas, malignant retroperitoneal sarcomas are usually ill-defined and displace or invade adjacent structures.Because myelolipomas contain macroscopic fat, they show greater signal loss (darkening) on fat-saturated images compared to T1 opposed-phase chemical shift images. Conversely, lipid-rich adrenal adenomas contain microscopic fat (also known as intracellular, intracytoplasmic, or intravoxel fat) and therefore show greater signal loss on T1 opposed-phase images than on fat-saturated images. The post Adrenal Cysts and Myelolipomas appeared first on Radiologist Headquarters.
3 Jan 2019
5 Cases in 5 Minutes: Vascular #1
Join us in this interactive video lecture as we present a total of 5 unknown vascular imaging cases followed by a diagnosis reveal and key teaching points after each case, all in about 5(ish) minutes! The post 5 Cases in 5 Minutes: Vascular #1 appeared first on Radiologist Headquarters.
4 Apr 2019
5 Cases in 5 Minutes: Vascular #2
Quiz yourself with this week’s interactive video lecture as we present a total of 5 unknown vascular imaging cases followed by a diagnosis reveal and key teaching points after each case, all in about 5(ish) minutes! The post 5 Cases in 5 Minutes: Vascular #2 appeared first on Radiologist Headquarters.
25 Apr 2019
5 Cases in 5 Minutes: Vascular #4
Quiz yourself with this week’s interactive video lecture as we present a total of 5 interesting vascular imaging cases followed by a diagnosis reveal and key teaching points after each case, all in just a few minutes! The post 5 Cases in 5 Minutes: Vascular #4 appeared first on Radiologist Headquarters.
16 May 2019
In this video lecture, we discuss the imaging appearance of adrenal hemorrhage on CT, MRI and ultrasound. Causes of adrenal hemorrhage will also be reviewed. Key points include: On CT scan, adrenal hemorrhage typically appears as a nonenhancing round or oval hyperdense mass with density of 50-90 HU. MRI is the most sensitive and specific modality for diagnosing adrenal hemorrhage. The “high signal intensity rim” rim sign seen on T1-weighted images is characteristic of subacute adrenal hemorrhage. Adrenal hemorrhage may appear solid or cystic on ultrasound depending on the age of hemorrhage.Adrenal hemorrhage is more common in neonates than in children and adults and is the most common adrenal mass in infancy.Trauma is the most common cause and is usually unilateral and right-sided. Atraumatic adrenal hemorrhage is usually unilateral. The post Adrenal Hemorrhage appeared first on Radiologist Headquarters.
19 Dec 2018
Imaging of Pelvic Inflammatory Disease, Part II
In the second part of this video lecture, we discuss the MRI appearance of pelvic inflammatory disease (PID), including tips on how to differentiate pyosalpinx from both hydrosalpinx and hematosalpinx. The computed tomography (CT) and ultrasound appearance of associated complications of PID are also reviewed. Topics include: Using diffusion-weighted imaging to differentiate pyosalpinx/tubo-ovarian abscess (TOA) from hydrosalpinx. Association between hematosalpinx and endometriosis. Fitz-Hugh-Curtis perihepatitis syndrome and its CT appearance on both late hepatic arterial phase and portal venous phase imaging. Imaging appearance of endometritis, including fluid-filled dilated endometrial cavity, subendometrial enhancement, gas, “dirty” shadowing and (most importantly) presence of clinical suspicion. Ovarian vein thrombosis, with emphasis on identifying enhancing, thickened venous walls and perivenous inflammation as findings of thrombophlebitis. TOA secondary to diverticulitis. How oxidized regenerated cellulose can mimic pelvic abscess and can normally contain gas for at least a month after surgery, highlighting the importance of reviewing the details of the operative history. References: Revzin MV, Mathur M, Dave HB, et al. Pelvic inflammatory disease: Multimodality imaging approach with clinical-pathologic correlation. Radiographics. 2016;36(5):1579-1596. Kim D, Kim TU, Lee JW, et al. The perihepatic space: Comprehensive anatomy and CT features of pathologic conditions. Radiographics. 2007;27(1):129 –143. Bennett GL, Slywotzky CM, Giovanniello G. Gynecologic causes of acute pelvic pain: Spectrum of CT findings. Radiographics. 2002;22(4):785–801. Sam JW, Jacobs JE, Birnbaum BA. Spectrum of CT findings in acute pyogenic pelvic inflammatory disease. Radiographics 2002;22(6):1327–1334. Kaakaji Y, Nghiem HV, Nodell C, Winter. TC. Sonography of obstetric and gynecologic emergencies. Part II, Gynecologic emergencies. AJR Am J Roentgenol. 2000 Mar;174(3):651-656. Kim MY, Rha SE, Oh SN, et al. MR imaging findings of hydrosalpinx: a comprehensive review. Radiographics. 2009;29(2):495-507. Ha HK, Lim GY, Cha ES, et al. MR imaging of tubo-ovarian abscess. Acta Radiol. 1995;36(5):510-4. Wilbur AC, Aizenstein RI, Napp TE. CT findings in tuboovarian abscess. AJR Am J Roentgenol. 1992;158(3):575-9. Young ST, Paulson EK, McCann RL, Baker ME. Appearance of oxidized cellulose (Surgicel) on postoperative CT scans: similarity to postoperative abscess. AJR Am J Roentgenol. 1993;160(2):275-277. Sandrasegaran K, Lall C, Rajesh A, Maglinte DT. Distinguishing gelatin bioabsorbable sponge and postoperative abdominal abscess on CT. AJR Am J Roentgenol. 2005;184(2):475-480. The post Imaging of Pelvic Inflammatory Disease, Part II appeared first on Radiologist Headquarters.
28 Jan 2017
5 Cases in 5 Minutes: Thoracic #1
Join us in this interactive video lecture as we present a total of 5 unknown thoracic imaging cases followed by a diagnosis reveal and key teaching points after each case, all in about 5(ish) minutes! The post 5 Cases in 5 Minutes: Thoracic #1 appeared first on Radiologist Headquarters.
28 Mar 2019
Hepatic Hemangioma: Pitfalls & Mimics, Part I
In this video lecture, we discuss tips and tricks to diagnose everybody’s favorite hepatic tumor on CT, MRI and ultrasound. Key points include: Hemangioma is the most common benign hepatic tumor, and it is more common in females. These tumors are usually asymptomatic and typically require no treatment, but can rarely cause pain, rupture if large, or cause Kasabach-Merritt syndrome. On nonenhanced CT, hemangiomas will be hypodense to liver parenchyma and homogeneously isodense to the blood pool. There are three major enhancement patterns for typical hemangiomas, and all patterns will show persistent delayed enhancement without contrast washout. Peripheral, nodular, interrupted enhancement with gradual centripetal progression to uniform enhancement is the most common pattern. Smaller lesions (less than 1-2 cm) can have immediate uniform enhancement and appear flash-filling. Larger hemangiomas may have a central scar that does not enhance. MRI is highly specific in the diagnosis of hemangioma. On MRI, hemangiomas will appear T1 hypointense and T2 hyperintense to liver parenchyma, or (perhaps more importantly) T1 isointense to the blood pool and T2 hyperintense to the spleen. Hemangiomas usually do not show restricted diffusion. The central scar of hemangioma will appear T1 hypointense and T2 hypointense on MRI. Additional liver masses that may have a central scar include focal nodular hyperplasia, fibrolamellar hepatocellular carcinoma, cholangiocarcinoma, and hepatocellular carcinoma. On ultrasound, hemangiomas are usually uniformly echogenic. 40% of hemangiomas can have a “reverse target” appearance with an echogenic periphery and hypoechoic center. Hemangiomas usually have no color Doppler flow on ultrasound, but they may occasionally exhibit mild flow. The post Hepatic Hemangioma: Pitfalls & Mimics, Part I appeared first on Radiologist Headquarters.
14 Mar 2019
5 Cases in 5 Minutes: Thoracic #2
Quiz yourself with this week’s interactive video lecture as we present a total of 5 unknown thoracic imaging cases followed by a diagnosis reveal and key teaching points after each case, all in about 5(ish) minutes! The post 5 Cases in 5 Minutes: Thoracic #2 appeared first on Radiologist Headquarters.
11 Apr 2019
5 Cases in 5 Minutes: Ultrasound #4
Join us in this interactive lecture as we present a total of 5 unknown cases followed by a diagnosis reveal and key teaching points after each case, all in about 5(ish) minutes! The post 5 Cases in 5 Minutes: Ultrasound #4 appeared first on Radiologist Headquarters.
28 Feb 2019