Virtual Monochromatic Dual-Energy Aortoiliac CT Angiography With Reduced Iodine Dose: A Prospective Randomized Study.

OBJECTIVE: The purpose of this study was to assess the feasibility of performing abdominopelvic aortoiliac CT angiography (CTA) with 16.0 g of iodine contrast medium acquired with low-energy (40 and 50 keV) virtual monochromatic (VMC) images with rapid-kilovoltage-switching dual-energy CT. SUBJECTS AND METHODS: A total of 52 adults with abdominal aortoiliac aneurysm and prior 120-kVp single-energy CTA (SECTA) with 33 g iodine (standard dose) underwent follow-up dual-energy CTA (DECTA) with a 52% reduced iodine dose. Subjects were randomly assigned to a contrast medium protocol for DECTA examinations: one group (n = 26) received 16.2 g (270 mg I/mL) and the other (n = 26) received 16.0 g (320 mg I/mL). Two readers independently assessed SECTA and VMC DECTA datasets for image quality using a 5-point scale. Aortoiliac intravascular attenuation was measured, and ANOVA was used to compare measurements between VMC DECTA and SECTA images. In a subset of patients with DECTA after endovascular aortic repair, endoleak detection was evaluated on VMC images. Volume CT dose index, dose-length product, and size-specific dose estimate were compared between DECTA and SECTA. RESULTS: All DECTA examinations (n = 52) were rated diagnostic with image quality scores comparable to those of 120-kVp single-energy CTA (40 keV, 4.2-4.4; 50 keV, 4.6-4.8; SECTA, 4.4-4.5). Intravascular attenuation was uniform in all reduced-iodine DECTA examinations and was significantly higher on 40- and 50-keV images than on standard-iodine-dose SECTA images (720 ± 125 HU and 482 ± 82 HU vs 303 ± 65 HU) (p < 0.01). There was no difference in intravascular attenuation between the 16.2-g and the 16.0-g doses (p = 0.82). Sensitivity and specificity for endoleak detection were 78.9-94.7% and 100%. Total dose-length product was lower for DECTA (788 ± 166 mGy · cm) than for SECTA (1114 ± 468 mGy · cm). CONCLUSION: Low-energy VMC DECTA images (40 and 50 keV) acquired with two contrast protocols at approximately 50% reduced iodine dose (16.0 and 16.2 g) provide adequate intravascular attenuation and diagnostic quality for aortoiliac evaluation.

Incidental pulmonary nodules in emergent coronary CT angiography for suspected acute coronary syndrome: Impact of revised 2017 Fleischner Society Guidelines.

BACKGROUND: Pulmonary nodules (PN) are frequently detected incidentally during coronary computed tomography angiography (CTA). We evaluated whether the 2017 Fleischner Society guidelines may result in a decrease of follow-up testing of incidental PN as compared to prior guidelines in patients undergoing coronary CTA. METHODS: We conducted a retrospective study of a registry of emergency department patients who underwent coronary CTA for acute coronary syndrome assessment between 2012 and 2017. Based on guidelines, patients <35 years, history of cancer, or prior exams showing stability of PN were excluded. Patients >60 years, history of smoking, irregular/spiculated PN morphology, or PN size >20 mm were classified as high-risk for lung cancer. Radiological findings pertaining to PN were identified (PN size, morphology, quantity) through review of radiology reports. PN follow-up recommendations were established using 2017 Fleischner Society Guidelines and compared with prior guidelines for solid (2005) and subsolid (2013) PN. Data were analyzed with Student's t-test. RESULTS: The registry included 2066 patients (female 45.1%, 52.9 ± 11.0 years), of which 578 (28.0%) reported PN. 438 of those (21.2%) were eligible for guideline-based follow-up evaluation. 205 (4 6.8%) were classified as high-risk for lung cancer. 2017 guidelines reduced the number of individuals requiring follow-up by 64.5%, from 264 (12.8%) to 94 patients (4.5%) when compared to prior guidelines (p < 0.001). The minimum number of follow-up chest CTs decreased by 55.8% from 430 to 190 (p < 0.001). CONCLUSION: Application of the 2017 Fleischner Society Guidelines resulted in a significant decrease of follow-up testing for incidental PN in patients undergoing coronary CTA for suspected acute coronary syndrome.

Results of a phase I-II study of fenretinide and rituximab for patients with indolent B-cell lymphoma and mantle cell lymphoma.

Fenretinide, a synthetic retinoid, induces apoptotic cell death in B-cell non-Hodgkin lymphoma (B-NHL) and acts synergistically with rituximab in preclinical models. We report results from a phase I-II study of fenretinide with rituximab for B-NHLs. Eligible diagnoses included indolent B-NHL or mantle cell lymphoma. The phase I design de-escalated from fenretinide at 900 mg/m2 PO BID for days 1-5 of a 7-day cycle. The phase II portion added 375 mg/m2 IV rituximab weekly on weeks 5-9 then every 3 months. Fenretinide was continued until progression or intolerance. Thirty-two patients were treated: 7 in phase I, and 25 in phase II of the trial. No dose-limiting toxicities were observed. The phase II component utilized fenretinide 900 mg/m2 twice daily with rituximab. The most common treatment-related adverse events of grade 3 or higher were rash (n = 3) and neutropenia (n = 3). Responses were seen in 6 (24%) patients on the phase II study, with a median duration of response of 47 months (95% confidence interval, 2-56). The combination of fenretinide and rituximab was well tolerated, yielded a modest overall response rate, but with prolonged remission durations. Further study should focus on identifying the responsive subset of B-NHL.

Prospective Comparison of Reduced-Iodine-Dose Virtual Monochromatic Imaging Dataset From Dual-Energy CT Angiography With Standard-Iodine-Dose Single-Energy CT Angiography for Abdominal Aortic Aneurysm.

OBJECTIVE: The purpose of this study was to compare the image quality of reduced-iodine-dose single-source dual-energy CT angiography (CTA) with that of standard-iodine-dose single-energy CTA in examinations of patients with abdominal aortic aneurysm and to assess the effect of the concentration of iodinated contrast medium on intravascular enhancement and image quality of reduced-iodine-dose CTA. SUBJECTS AND METHODS: In a prospective randomized clinical trial, 66 consecutively registered patients with abdominal aortic aneurysm who had previously undergone single-energy CTA (30-37 g I) underwent follow-up CTA at a reduced dose (21-27 g I) of iodinated contrast medium of either 270 mg I/mL (n = 33) or 320 mg I/mL (n = 33). Two readers independently evaluated virtual monochromatic imaging datasets (40-140 keV) and single-energy CTA images for image quality and noise and their preference for optimal energy virtual monochromatic imaging dataset. A value of p < 0.05 was considered statistically significant. RESULTS: All 66 dual-energy CTA examinations were rated diagnostic with mean image quality and image noise scores of 4.8 and 4.5 for reader 1 and 3.8 and 3.4 for reader 2 compared with single-energy CTA results of 4.5 and 4.2 for reader 1 and 4.5 and 4.1 for reader 2. Low-energy virtual monochromatic images (40-60 keV) from reduced-iodine-dose (28%) dual-energy CTA had significantly higher intravascular aortic attenuation (26-185%) and contrast-to-noise ratio (CNR) (20-25%) than standard-iodine-dose single-energy CTA images (p < 0.0001). No significant difference was found between patients who received 270 and those who received 320 mg I/mL with respect to intravascular aortic attenuation (p = 0.6331) or CNR (p = 0.9775). CONCLUSION: Low-energy virtual monochromatic imaging datasets from reduced-iodine (24 g I) single-source dual-energy CTA of the abdomen provide up to 185% higher attenuation and 25% higher CNR than standard-iodine-dose (33.3 g I) single-energy CTA while offering a wide range of energy settings irrespective of the concentration of IV contrast medium used.

Advances in axial imaging of peripheral vascular disease.

Peripheral artery disease (PAD) has become increasingly common in the US patient population and can be a highly symptomatic and significant source of morbidity. When PAD is suspected, the first-line screening study that is obtained is typically a noninvasive evaluation that includes the ankle brachial index (ABI). Following a positive screening study, invasive catheter digital subtraction angiography (DSA) has been historically used to image the peripheral artery system and still remains the gold standard. However, newer developments in axial imaging including computed tomography angiography (CTA) and magnetic resonance angiography (MRA) have in large part supplanted DSA for imaging the peripheral artery system in clinical practice. Benefits of CTA include rapid noninvasive acquisition, wide availability, high spatial resolution, and the ability to generate isotropic datasets on 64-detector row and higher CT scanners, thereby allowing for multiplanar 3D reformatting. Drawbacks of CTA include the exposure to both iodinated contrast and ionizing radiation, although the radiation dose exposure is lower than for DSA, and newer techniques such as using low tube voltage and rapid acquisition times allow for lower contrast doses. The presence of vascular calcification also limits the evaluation of small distal arteries using CTA, although the development of dual-energy CT techniques has significantly addressed this issue. Benefits of MRA include the avoidance of exposure to ionizing radiation and high diagnostic accuracy, while drawbacks include limited availability and increased cost along with the risk of nephrogenic systemic fibrosis that is associated with gadolinium-based contrast agents, although the latter can be mitigated by using newer non-contrast MR angiography techniques. Future technical advances in CT and MR hardware and software and MR pulse sequences will likely lead to the broader applicability and increased accuracy of noninvasive axial imaging in the evaluation of patients with peripheral artery disease.

An easily missed diagnosis: flank pain and nutcracker syndrome.

A 27-year-old woman presented to her primary care doctor's office with left flank pain. CT of the abdomen showed an isolated left renal vein thrombus. The clot was initially attributed to her oral contraceptive use; however, closer inspection of CT images revealed nutcracker phenomenon (compression of the renal vein between the superior mesenteric artery and abdominal aorta). Intravascular ultrasound imaging confirmed the diagnosis. Nutcracker syndrome is a rare condition, which if left untreated may cause damage to the left kidney. Although under diagnosed, there are several treatment options available ranging from simple surveillance to surgical resolution.

A phase I study of pulse high-dose vorinostat (V) plus rituximab (R), ifosphamide, carboplatin, and etoposide (ICE) in patients with relapsed lymphoma.

Given the poor outcomes of relapsed aggressive lymphomas and preclinical data suggesting that ≥2·5 µmol/l concentrations of vorinostat synergize with both etoposide and platinums, we hypothesized that pulse high-dose vorinostat could safely augment the anti-tumour activity of (R)ICE [(rituximab), ifosphamide, carboplatin, etoposide] chemotherapy. We conducted a phase I dose escalation study using a schedule with oral vorinostat ranging from 400 mg/d to 700 mg bid for 5 d in combination with the standard (R)ICE regimen (days 3, 4 and 5). Twenty-nine patients [median age 56 years, median 2 prior therapies, 14 chemoresistant (of 27 evaluable), 2 prior transplants] were enrolled and treated. The maximally tolerated vorinostat dose was defined as 500 mg twice daily × 5 d. Common dose limiting toxicities included infection (n = 2), hypokalaemia (n = 2), and transaminitis (n = 2). Grade 3 related gastrointestinal toxicity was seen in 9 patients. The median vorinostat concentration on day 3 was 4·5 µmol/l (range 4·2-6·0 µmol/l) and in vitro data confirmed the augmented antitumour and histone acetylation activity at these levels. Responses were observed in 19 of 27 evaluable patients (70%) including 8 complete response/unconfirmed complete response. High-dose vorinostat can be delivered safely with (R)ICE, achieves potentially synergistic drug levels, and warrants further study, although adequate gastrointestinal prophylaxis is warranted.

Critical limb ischemia: an update for interventional radiologists.

Critical limb ischemia (CLI) is a growing epidemic with bleak patient outcomes. A variety of treatment modalities have been adopted to address CLI based on comorbidities, life expectancy, and the nature of the arterial disease. With advances in technology and treatment strategies, the clinical outcomes of CLI patients have significantly improved over recent years. However, despite progress, patency rates of both surgical and endovascular interventions, limb-salvage and amputation rates are still dismal. We review the epidemiology, treatment strategies, imaging modalities, and the microcirculation aspect of CLI.

Identifying, characterizing, and classifying congenital anomalies of the coronary arteries.

The clinical manifestations of coronary artery anomalies vary in severity, with some anomalies causing severe symptoms and cardiovascular sequelae and others being benign. Cardiovascular computed tomography (CT) has emerged as the standard of reference for identification and characterization of coronary artery anomalies. Therefore, it is important for the reader of cardiovascular CT images to be thoroughly familiar with the spectrum of coronary artery anomalies. Hemodynamically significant anomalies include atresia, origin from the pulmonary artery, interarterial course, and congenital fistula. Non-hemodynamically significant anomalies include duplication; high origin; a prepulmonic, transseptal, or retroaortic course; shepherd's crook right coronary artery; and systemic termination. In general, coronary arteries with an interarterial course are associated with an increased risk of sudden cardiac death. Coronary artery anomalies that result in shunting, including congenital fistula and origin from the pulmonary artery, are also commonly symptomatic and may cause steal of blood from the myocardium. Radiologists should be familiar with each specific variant and its specific constellation of potential implications.

Pseudolesion in segment IV A of the liver from vein of Sappey secondary to SVC obstruction.

Pseudolesions in the liver are caused by unusual/altered hemodynamics of the liver and can be confused with a true hepatic mass. In superior vena cava (SVC) obstruction. there is recruitment of the cavo-mammary-phrenic-hepatic-capsule-portal pathway. and the venous blood follows the internal mammary vein, the inferior phrenic vein, the hepatic capsule veins, and the intrahepatic portal system. causing a hypervascular pseudolesion in segment IV A of the liver. Recognizing the classic appearances of this hypervascular pseudolesion from the vein of Sappey in a CT study of the abdomen has prognostic implications in directing further evaluation of the chest for SVC obstruction. We present a case of a 54-year-old HIV-positive male smoker in whom identification of the hypervascular pseudolesion from the vein of Sappey on the abdominal CT led to the diagnosis of SVC syndrome.