Focal Nodular Hyperplasia and Focal Nodular Hyperplasia-like Lesions.

Focal nodular hyperplasia (FNH) is a benign lesion occurring in a background of normal liver. FNH is seen most commonly in young women and can often be accurately diagnosed at imaging, including CT, MRI, or contrast-enhanced US. In the normal liver, FNH frequently must be differentiated from hepatocellular adenoma, which although benign, is managed differently because of the risks of hemorrhage and malignant transformation. When lesions that are histologically identical to FNH occur in a background of abnormal liver, they are termed FNH-like lesions. These lesions can be a source of diagnostic confusion and must be differentiated from malignancies. Radiologists' familiarity with the imaging appearance of FNH-like lesions and knowledge of the conditions that predispose a patient to their formation are critical to minimizing the risks of unnecessary intervention for these lesions, which are rarely symptomatic and carry no risk for malignant transformation. FNH is thought to form secondary to an underlying vascular disturbance, a theory supported by the predilection for formation of FNH-like lesions in patients with a variety of hepatic vascular abnormalities. These include abnormalities of hepatic outflow such as Budd-Chiari syndrome, abnormalities of hepatic inflow such as congenital absence of the portal vein, and hepatic microvascular disturbances, such as those that occur after exposure to certain chemotherapeutic agents. Familiarity with the imaging appearances of these varied conditions and knowledge of their association with formation of FNH-like lesions allow radiologists to identify with confidence these benign lesions that require no intervention. Online supplemental material is available for this article. ©RSNA, 2022.

Current Imaging Techniques for Noninvasive Staging of Hepatic Fibrosis.

OBJECTIVE. The purpose of this article is to discuss quantitative methods of CT, MRI, and ultrasound (US) for noninvasive staging of hepatic fibrosis. Hepatic fibrosis is the hallmark of chronic liver disease (CLD), and staging by random liver biopsy is invasive and prone to sampling errors and subjectivity. Several noninvasive quantitative imaging methods are under development or in clinical use. The accuracy, precision, technical aspects, advantages, and disadvantages of each method are discussed. CONCLUSION. The most promising methods are the liver surface nodularity score using CT and measurement of liver stiffness using MR elastography or US elastography.

Active Surveillance Versus Nephron-Sparing Surgery for a Bosniak IIF or III Renal Cyst: A Cost-Effectiveness Analysis.

OBJECTIVE: The objective of our study was to evaluate the cost-effectiveness of active surveillance (AS) versus nephron-sparing surgery (NSS) in patients with a Bosniak IIF or III renal cyst. MATERIALS AND METHODS: Markov models were developed to estimate life expectancy and lifetime costs for 60-year-old patients with a Bosniak IIF or III renal cyst (the reference cases) managed by AS versus NSS. The models incorporated the malignancy rates, reclassification rates during follow-up, treatment effectiveness, complications and costs, and short- and long-term outcomes. An incremental cost-effectiveness analysis was performed to identify management preference under an assumed $75,000 per quality-adjusted life-year (QALY) societal willingness-to-pay threshold, using data from studies in the literature and the 2015 Medicare Physician Fee Schedule. The effects of key parameters were addressed in a multiway sensitivity analysis. RESULTS: The prevalence of malignancy for Bosniak IIF and III renal cysts was 26% (25/96) and 52% (542/1046). Under base case assumptions for Bosniak IIF cysts, the incremental cost-effectiveness ratio of NSS relative to AS was $731,309 per QALY for women, exceeding the assumed societal willingness-to-pay threshold, and AS outperformed NSS for both life expectancy and cost for men. For Bosniak III cysts, AS yielded greater life expectancy (24.8 and 19.4 more days) and lower lifetime costs (cost difference of $12,128 and $11,901) than NSS for men and women, indicating dominance of AS over NSS. Superiority of AS held true in sensitivity analyses for men 46 years old or older and women 57 years old or older even when all parameters were set to favor NSS. CONCLUSION: AS is more cost-effective than NSS for patients with a Bosniak IIF or III renal cyst.

Scanner-Based Protocol-Driven Ultrasound: An Effective Method to Improve Efficiency in an Ultrasound Department.

OBJECTIVE: For ultrasound, a wide variation is often observed among the number and sequence of images acquired for a particular examination type. Scanner-based protocols are preset pathways in the ultrasound machine that guide a sonographer through the required study images. These protocols can streamline image acquisition by improving consistency and efficiency of ultrasound examinations. This study evaluated whether implementation of scanner-based protocol-driven ultrasound improves efficiency by decreasing the scanning duration and number of images acquired. MATERIALS AND METHODS: Retrospective evaluation of 437 carotid Doppler examinations, 395 complete abdominal ultrasound examinations with Doppler imaging, and 413 bilateral lower extremity venous Doppler examinations for deep venous thrombosis (DVT) performed by five sonographers before and after implementation of scanner-based protocol-driven ultrasound was performed. The scanning duration and number of images acquired for each study were recorded. Statistical analysis compared the scanning duration and number of images acquired before and after implementation of protocol-driven ultrasound. A p value of < 0.05 was considered significant. RESULTS: A significant decrease in scanning duration occurred for both carotid Doppler ultrasound examinations (decrease by 12.4% [2.7 minutes], p < 0.0001) and complete abdominal ultrasound examinations with Doppler imaging (decrease by 7.5% [2.0 minutes], p = 0.0054) after implementation of protocol-driven ultrasound. The decrease in scanning duration was not significant for lower extremity DVT Doppler examinations (p = 0.4192). In addition, there was a significant decrease in the overall number of images obtained for all three types of studies. CONCLUSION: Scanner-based protocol-driven ultrasound is an effective method that streamlines image acquisition and significantly improves efficiency in an ultrasound department while ensuring consistency and adherence to accreditation guidelines.

Outcomes and complications related to the management of Bosniak cystic renal lesions.

OBJECTIVE: The objective of our study was to evaluate outcomes and complications related to the management of Bosniak category IIF, III, and IV renal cysts. MATERIALS AND METHODS: For this multiinstitutional retrospective study, a Web-based Research Electronic Data Capture (REDCap) data registry was used to record data of 286 adult patients with 312 prospectively classified Bosniak IIF, III, and IV renal cysts diagnosed between January 2000 and October 2011. Included patients were managed by surgery (n = 86), percutaneous ablation (n = 19), or imaging surveillance of 1 year or more (n = 181). The median number of years of clinical surveillance was 2.4 years (range, 0-11.7 years), 2.6 years (range, 0.4-11.4 years), and 3.2 years (range, 1.1-11.6 years) for patients managed by surgery, ablation, and imaging surveillance, respectively. Pathologic and survival outcomes and complications related to management were evaluated. RESULTS: The malignancy rate at surgical pathology was 38% (3/8) for Bosniak IIF, 40% (29/72) for Bosniak III, and 90% (18/20) for Bosniak IV renal cysts. There were no metastases or deaths (0/144) directly related to Bosniak IIF renal cysts. There were no deaths (0/113) directly related to Bosniak III renal cysts, although one patient (1/113) developed local progression and lung metastases after thermal ablation. One patient with a Bosniak IV renal cyst (1/29) presented with and died of metastatic disease. Moderate to severe complications occurred in 19% (16/86), 5% (1/19), and 0% (0/181) of patients managed by surgery, ablation, and imaging surveillance, respectively (p < 0.0001). Severe complications occurred in 7% (6/86) of surgical patients and included multiorgan failure (n = 2), acute myocardial infarction (n = 1), acute ischemic stroke (n = 1), conversion to hemodialysis-dependent chronic kidney disease (n = 1), and postoperative severe hemorrhage (n = 1). CONCLUSION: There were no deaths from Bosniak IIF or III renal cysts regardless of management approach. Moderate to severe complications are frequent in patients managed by surgery.

Secretin-enhanced MR cholangiopancreatography: spectrum of findings.

Magnetic resonance cholangiopancreatography (MRCP) is the most effective, safe, noninvasive magnetic resonance (MR) imaging technique for the evaluation of the pancreaticobiliary ductal system. The MRCP imaging technique has substantially improved during the past 2 decades and is based mainly on the acquisition of heavily T2-weighted MR images, with variants of fast spin-echo sequences. MRCP can also be performed by utilizing the hormone secretin, which stimulates a normal pancreas to secrete a significant amount of fluid while transiently increasing the tone of the sphincter of Oddi. The transient increase in the diameter of the pancreatic duct improves the depiction of the ductal anatomy, which can be useful in patients in whom detailed evaluation of the pancreatic duct is most desired because of a suspicion of pancreatic disease. Improved depiction of the ductal anatomy can be important in (a) the differentiation of side-branch intraductal papillary mucinous neoplasms from other cystic neoplasms and (b) the diagnosis and classification of chronic pancreatitis, the disconnected pancreatic duct syndrome, and ductal anomalies such as anomalous pancreaticobiliary junction and pancreas divisum. In patients examined after pancreatectomy, stimulation with secretin can give information about the patency of the pancreaticoenteric anastomosis. Duodenal filling during the secretin-enhanced phase of the MRCP examination can be used to estimate the excretory reserve of the pancreas. Secretin is well tolerated, and complications are rarely seen. Secretin-enhanced MRCP is most useful in (a) the evaluation of acute and chronic pancreatitis, congenital variants of the pancreaticoduodenal junction, and intraductal papillary mucinous neoplasms and (b) follow-up of patients after pancreatectomy.

Recent advances in cross-sectional renal imaging-an oncologic perspective: the current concepts and the future challenges.

Renal imaging remains a critical tool to differentiate and manage benign from malignant renal disorders. Conventional multidetector computed tomography (CT) and magnetic resonance (MR) provide great anatomical details, although lack functional information and specificity. The lack of resolution undermines the functional capabilities of nuclear medicine imaging. Functional MR imaging has shown strong utility in imaging of renal masses, with evolving techniques such as diffusion, perfusion, and blood oxygen level-dependent sequences. At the same time, newer techniques like dual-energy CT and CT perfusion are also showing promise in renal oncologic imaging.This article will discuss the recent advances in MR imaging and CT techniques pertaining to renal oncological applications.

Secretin-enhanced MRCP: review of technique and application with proposal for quantification of exocrine function.

OBJECTIVE: The purpose of this article is to present a proposal for quantification of exocrine function using secretin-enhanced MRCP for the diagnosis of chronic pancreatitis. The article also reviews the technique and application of secretin-enhanced MRCP in evaluating various pancreatic abnormalities. SUBJECTS AND METHODS: One hundred thirty-four consecutive patients with chronic abdominal pain undergoing secretin-enhanced MRCP for suspected chronic pancreatitis were included. Patients were divided into four clinical groups (normal, equivocal, early chronic pancreatitis, established pancreatitis) on the basis of clinical symptoms and additional investigations, including CT (n=98), endoscopic pancreatic function test (n=65), endoscopic ultrasound (n=84), and ERCP (n=36). The volume of secretion was obtained by drawing a region of interest around T2 bright fluid secreted on postsecretin HASTE images. The maximal rate of secretion in response to secretin was obtained by plotting change in signal intensity on sequential postsecretin images. The analysis of variance test was used to compare the clinical groups with the volume and rate of secretion. RESULTS: Significant volume differences were found between the normal and established pancreatitis groups (p<0.0001) as well as the equivocal and established pancreatitis groups (p<0.0005). Marginally significant differences were found between the normal and early pancreatitis groups (p=0.0150) as well as early and established pancreatitis groups (p=0.0351). Differences in the maximal rate of secretion were not statistically significant. CONCLUSION: Secretory volume measurement of secretin-enhanced MRCP data is a simple method that brings out significant differences between normal, early, and established pancreatitis patients.

Orthotopic liver transplantation: reversible Doppler US findings in the immediate postoperative period.

Orthotopic liver transplantation (OLT) is the only definitive treatment for irreversible acute liver failure and chronic liver disease. In the immediate postoperative period after OLT, patients are closely monitored with Doppler ultrasonography (US) to detect treatable vascular complications and ensure graft survival. The first postoperative Doppler US examination is performed fairly early on the first postoperative day, before surgical wound closure has been performed. The immediate postoperative images, obtained when the effects of surgery are very recent, often reveal an array of findings that may appear alarming but that tend to normalize within a few days and are compatible with changes related to the surgery itself. These findings include a starry-sky appearance of reperfusion hepatic edema, transient foci of increased echogenicity, pneumobilia, small fluid collections, perihepatic hematomas, pleural effusion, temporary elevation of hepatic arterial velocity, transient elevation of resistive index (RI), decreased RI with tardus parvus waveform, increased portal venous flow and mono- or biphasic waveforms of the hepatic veins. Most of these changes revert to normal in the first postoperative week; deterioration atypical of transient changes requires further evaluation.

Nephrogenic systemic fibrosis: A frivolous entity.

Gadolinium-based contrast agents (GBCAs) used in magnetic resonance imaging are vital in providing enhanced quality images, essential for diagnosis and treatment. Nephrogenic systemic fibrosis (NSF) with GBCAs has been a deterrent for the physician and has led to avoidance of these agents in patients with impaired kidney function. NSF is a progressive debilitating multisystem condition described classically in patients with renal insufficiency exposed to gadolinium contrast media. It is characterized by an induration and hardening of the skin. NSF is described to first involve the extremities and can imperceptibly involve internal organs. Lack of therapeutic interventions to treat NSF makes it more challenging and warrants deep insight into the pathogenesis, risk factors and treatment strategies.

The Male Urethra: Imaging and Surgical Approach for Common Pathologies.

Urethral pathology is common in clinical practice and important to recognize. It is essential to recognize urethral pathology on imaging and to understand how to best image the urethra. In this way, the radiologist can provide the urologist with the necessary information prior to intervention. Basic knowledge of commonly performed urethral surgeries can help the radiologist understand the expected appearance of the post-treatment urethra and common postoperative complications.

Diagnostic performance of fusion of myocardial perfusion imaging (MPI) and computed tomography coronary angiography.

BACKGROUND: We evaluated the incremental diagnostic value of fusion images of coronary computed tomography angiography (CTA) and myocardial perfusion imaging (MPI) over MPI alone or MPI and CTA side-by-side to identify obstructive coronary artery disease (CAD > 50% stenosis) using invasive coronary angiography (ICA) as the gold standard. METHODS: 50 subjects (36 men; 56 +/- 11 years old) underwent rest-stress MPI and CTA within 12-26 days of each other. CTAs were performed with multi-detector CT-scanners (31 on 64-slice; and 19 on 16-slice). 37 patients underwent ICA while 13 subjects did not because of low (<5%) pre-test likelihood (LLK) of disease. Three blinded readers scored the images in sequential sessions using (1) MPI alone (2) MPI and CTA side-by-side, (3) fused CTA/MPI images. RESULTS: One or more critical stenoses during ICA were found in 28 patients and non-critical stenoses were found in 9 patients. MPI, side-by-side MPI-CTA, and fused CTA/MPI showed the same normalcy rate (NR:13/13) in LLK subjects. The fusion technique performed better than MPI and MPI and CTA side-by-side for the presence of CAD in any vessel (overall area under the curve (AUC) for fused images: 0.89; P = .005 vs MPI, P = .04 vs side-by-side MPI-CTA) and for localization of CAD to the left anterior descending coronary artery (AUC: 0.82, P < .001 vs MPI; P = .007 vs side-by-side MPI-CTA). There was a non-significant trend for better detection of multi-vessel disease with fusion. CONCLUSIONS: Using ICA as the gold standard, fusion imaging provided incremental diagnostic information compared to MPI alone or side-by-side MPI-CTA for the diagnosis of obstructive CAD and for localization of CAD to the left anterior descending coronary artery.

Radiology of the retroperitoneum: case-based review.

OBJECTIVE: We discuss five scenarios in which retroperitoneal abnormalities are imaged. CONCLUSION: Retroperitoneal disorders may manifest as a focal or diffuse abnormality and may be benign or malignant. Imaging plays a key role in providing a differential diagnosis in patients with retroperitoneal abnormalities.

Role of imaging in the management of splenic artery steal syndrome.

OBJECTIVE: The purpose of this study is to discuss the etiology and role of imaging in the management of splenic artery steal syndrome (SASS) following orthotropic liver transplantation (OLT). METHODS: Hepatic arterial thrombosis and stenosis have been the most commonly recognized arterial complications following OLT. Splenic artery steal syndrome is a recently described entity in the transplant literature and thought to be an under-recognized cause of graft ischemia. It is characterized by hepatic arterial hypoperfusion accompanied by splenic arterial and portal venous hyperperfusion and leads to various vascular and biliary graft complications. Because the clinical manifestations of SASS are so non-specific, imaging plays a key role in the diagnosis of this condition. RESULTS: This article discusses the role of imaging in the management of this potentially reversible cause of graft ischemia. CONCLUSIONS: Awareness of the imaging features and having a high index of suspicion are essential for the early diagnosis and prompt management of this condition.

Ultrasound of Renal Masses.

Renal masses are common incidental findings. Although most are benign, it is important to evaluate for features concerning for malignancy. Because of its relative low cost; excellent differentiation among simple cysts, complex cysts, and solid lesions; and lack of ionizing radiation, ultrasound is the preferred modality for initial workup of renal lesions. Given the increasing availability of contrast-enhanced ultrasound, more and more lesions are now able to be completely characterized by sonography alone, including use of the Bosniak criteria.

Potential impact of noncontrast computed tomography as gatekeeper for myocardial perfusion positron emission tomography in patients admitted to the chest pain unit.

We investigated the ability of coronary artery calcium (CAC) to predict a normal adenosine stress rubidium-82 (Rb-82) myocardial perfusion positron emission tomography (PET) in patients admitted to the chest pain unit. Eighty-four consecutive patients (33 men; mean age 62 +/- 14.8 years) with low to intermediate likelihood of coronary artery disease were included. A single noncontrast computed tomogram under shallow breathing was obtained for attenuation correction and to assess the presence of CAC. This was followed by a rest and adenosine stress dynamic Rb-82 emission PET. Computed tomography and PET images were interpreted independently. There was a high prevalence of risk factors (80% hypertension, 30% diabetes, 38% hypercholesterolemia, 13% smoking); prior coronary revascularization and myocardial infarction were present in 21% and 15% of the patients, respectively. The absence of CAC was associated with a normal adenosine stress Rb-82 myocardial perfusion PET in 34 of 34 patients, yielding a negative predictive value of 100%. The presence of CAC (50 of 84) was associated with a higher incidence of myocardial perfusion defects (13 of 50), yielding a positive predictive value of 26%. Sensitivity was 100% (13 of 13) and specificity was 48% (34 of 71). In conclusion, the absence of CAC is predictive of a normal adenosine stress Rb-82 myocardial perfusion PET in patients admitted to the chest pain unit. If these results are confirmed, myocardial perfusion imaging probably can be safely avoided in chest pain patients with negative CAC with low to intermediate pretest likelihood of disease. This approach may decrease overall radiation exposure and hospital time and prove to be cost effective.

Vitamin D and bone health in adults with cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) patients have chronic pancreatic insufficiency leading to malabsorption of fat-soluble vitamins, including vitamin D which can contribute to poor skeletal health and respiratory function. OBJECTIVE: This study evaluated the prevalence of vitamin D insufficiency and its impact on bone and respiratory health in adults with CF. DESIGN AND MEASUREMENTS: This was a retrospective study in which data were collected from medical records over a 2-year period. Data included patient demographics, lung function, biochemical data, bone mineral densities, X-rays and ascertainment of use of vitamin supplements. Data were collected from medical records at a single accredited CF Center. Serum 25-hydroxyvitamin D [25(OH)D] levels and bone mineral density studies were also collected. PATIENTS: A total of 185 adults with CF were identified with a mean age of 29 +/- 9 years. RESULTS: The prevalence of vitamin D insufficiency [25(OH)D < 75 nmol/l] was 76%. Mean serum 25(OH)D concentrations were 58.8 +/- 30 nmol/l. Use of specific vitamin D supplementation was protective against vitamin D insufficiency whereas use of multivitamins was not. There was a small, but significant, positive association between serum 25(OH)D and FEV(1) per cent predicted after controlling for age, gender, BMI and race (R(2) = 0.30, P < 0.001). A high prevalence (27%) of vertebral fractures was detected on lateral chest X-ray. CONCLUSIONS: The prevalence of vitamin D insufficiency and poor skeletal health is high in the US CF population. Vitamin D status appears to be positively associated with lung function. Prospective studies to examine the impact of correction of vitamin D insufficiency on skeletal and lung health in adult CF are warranted.

Adenosine stress rubidium-82 PET/computed tomography in patients with known and suspected coronary artery disease.

BACKGROUND: Integrated positron emission tomography/computed tomography (PET/CT) is increasingly being utilized for myocardial perfusion imaging (MPI). However, there is a potential for increased imaging artifact compared with standard PET due to the different temporal resolution of PET and CT. We reviewed the diagnostic accuracy of adenosine stress Rb myocardial perfusion PET/CT to detect obstructive coronary artery disease (CAD) on invasive angiography at our institution. METHODS AND RESULTS: Seventy-five patients were included, 23 (13 men, mean age 55.8+/-11.8 years) with low likelihood of CAD and 52 (28 men, mean age 67.1+/-11.4 years) with intermediate to high pretest probability of disease. Coronary angiography was performed only in the latter 52 patients on average within 17 days of the MPI study. The test characteristics of PET/CT MPI were assessed using a threshold of >or=50 and >or=70% stenosis in one or more major coronary artery on invasive angiography. Dedicated software was used for registration, processing, and interpretation. Consensus interpretation of the tomographic PET slices using a 4-point scale (1=definitely normal, 2=probably normal, 3=probably abnormal, 4=definitely abnormal) was done by two readers blinded to clinical information. RESULTS: All MPI studies in the 23 low likelihood patients were normal. In the remaining 52 patients using a stenosis severity>or=50%, global sensitivity and specificity, negative and positive predictive value for detection of CAD were 86, 100, 57, and 100%. Using a stenosis severity>or=70%, these values changed to 90, 83, 71, and 87%. CONCLUSION: Adenosine stress Rb MPI using PET/CT with manual registration demonstrates diagnostic accuracy comparable with that of traditional PET MPI.