Four-dimensional Flow MRI: Principles and Cardiovascular Applications.

In-plane phase-contrast (PC) imaging is now a routine component of MRI of regional blood flow in the heart and great vessels. In-plane PC MRI provides a volumetric, isotropic, time-resolved cine sequence that enables three-directional velocity encoding, a technique known as four-dimensional (4D) flow MRI. Recent advances in 4D flow MRI have shortened imaging times, while progress in big-data processing has improved dataset pre- and postprocessing, thereby increasing the feasibility of 4D flow MRI in clinical practice. Important technical issues include selection of the optimal velocity-encoding sensitivity before acquisition and preprocessing of the raw data for phase-offset corrections. Four-dimensional flow MRI provides unprecedented capabilities for comprehensive analysis of complex blood flow patterns using new visualization tools such as streamlines and velocity vectors. Retrospective multiplanar navigation enables flexible retrospective flow quantification through any plane across the volume with good accuracy. Current flow parameters include forward flow, reverse flow, regurgitation fraction, and peak velocity. Four-dimensional flow MRI also supplies advanced flow parameters of use for research, such as wall shear stress. The vigorous burgeoning of new applications indicates that 4D flow MRI is becoming an important imaging modality for cardiovascular disorders. This article reviews the main technical issues of 4D flow MRI and the different parameters provided by it and describes the main applications in cardiovascular diseases, including congenital heart disease, cardiac valvular disease, aortic disease, and pulmonary hypertension. Online supplemental material is available for this article. ©RSNA, 2019 See discussion on this article by Ordovas .

Surgical Treatment of Venous Malformations of the Knee: Treatment Outcomes for 35 Patients.

BACKGROUND: The place of open surgery in venous malformations (VMs) of knee joint is still discussed. The aim of this study was to evaluate the benefits of surgery in terms of pain, function, and quality of life. DESIGN: This was a retrospective observational study. METHODS: Thirty-five consecutive young patients undergoing surgery for VMs of the knee between 2011 and 2014 were included. Data collection was performed using a prospective database by reviewing patient records. Pain, mobility of the joint, residual VMs as seen by magnetic resonance imaging, and quality of life were the main outcome endpoints for this study. RESULTS: Thirty-five patients (22 females and 13 males, with a median age of 15 y, range of 5 to 20 y) were included. Twenty-seven VMs were localized in and around the knee joint, of which 8 were extensive. Indication for surgery was intermittent or permanent pain.Details of the surgical excisions of the VM are as follows: suprapatellar area in 57%, suprapatellar and infrapatellar area in 29%, infrapatellar area in 2%, limited in the femoropatellar area in 12%. Partial resection of a vastus muscle or patellar retinaculum was necessary for 19 patients.The median duration of the surgery was 4 hours (range: 2 to 7 h). The median hospital stay was 5 days; full-time physiotherapy was systematic for 2 to 3 weeks.After 6 months, 74% had no longer pain, the mobility of the joint was normal for 60%. Of the 33 patients who had a magnetic resonance imaging at 6 months, 86% (28 patients) had no residual intra-articular VMs, and 14% had focal residual VMs.At the last follow-up, 77% (27 patients) had no longer pain, 23% experienced intermittent pain with unusual activities, and 91% (32 patients) had normal mobility of the joint. Quality of life was increased significantly due to the pronounced impact on pain. CONCLUSION: Extensive surgical excision of knee VMs is a safe procedure with good outcomes in terms of pain, function, and quality of life. LEVEL OF EVIDENCE: Level II-retrospective observational monocentric study.

Standardized three dimensional computerised tomography scanner reconstructions increase the accuracy of acetabular fracture classification.

PURPOSE: Evaluate the role of four standardized 3D reconstruction views in the accurate diagnosis of acetabular fractures. MATERIALS AND METHODS: Thirty-five acetabular fracture cases were selected from a tertiary centre database. Fourteen reviewers with different experience level evaluated this set of images which were provided in axial 2D views and multiplanar reconstruction (MPR) without 3D views in the first two readings then the standardized 3D views were added for the subsequent two readings. The primary outcome was the accuracy of diagnosis while inter-observer reliability and reading time as well as time needed for accurate diagnosis were evaluated. RESULTS: Accuracy of classification was 56.7% using the 2D and 73% using the described 3D (p < 0.001). Improvement was noted in all groups even though the expert group showed the least improvement (6.7% (p = 0.04)) and the least experience group showed the most improvement (35.7% (p < 0.001)). Average time of interpretation was 96 minutes for the 2D sets and 47 minutes for the 3D sets. Finally, the adding of the four standardized views increased the inter-observer reliability in all groups compared to the standard 2D sets with MPR. CONCLUSION: Acetabular fracture diagnosis according to Letournel classification is difficult and depends greatly on the experience of the reader. The described set of 3D images yields better accuracy and renders the diagnosis more repeatable and faster. We recommend the use of these images in classifying acetabular fractures.

Identification and treatment of atypical acetabular fractures having an independent acetabular roof fragment: Three-column fractures.

INTRODUCTION: A unique type of both-column fracture of the acetabulum that also has an independent roof fragment seems to occur relatively often. It is challenging to diagnose, thus our ability to detect it and its frequency are not known. This led us to analyze a database of acetabular fractures to 1) determine the incidence of this type of fracture, 2) describe its radiological characteristics, 3) attempt to set out a specific treatment strategy. HYPOTHESIS: The need for a dual surgical approach depends on the type and displacement of the independent roof fragment. METHODS: Four surgeons and radiologists independently analyzed a set of acetabular fractures that occurred between 2007 and 2017. The diagnosis was made using two-dimensional (2D) and three-dimensional (3D) CT reconstructions. Once the fractures had been identified, a detailed description was made of all 2D and 3D slices. A retrospective analysis was done of the reduction and fixation of the independent roof fragment relative to the chosen surgical approach. RESULTS: The study comprised 534 acetabular fractures, of which 96 where both-column fractures. In that subset, 41% (39 fractures) had an independent roof fragment. A detailed analysis resulted in the identification of two subtypes of three-column fracture with independent fragment: type 1 has a posterosuperior fragment (22 cases); type 2 has an independent fragment separated by a juxtatectal fracture line (17 cases). The best radiological outcomes were achieved when the independent fragment was minimally displaced and did not require additional reduction. CONCLUSION: The isolated roof fragment is common, as it occurs is more than one-third of both-column fractures. We were able to identify two subtypes that require different surgical strategies. Surgical treatment of these fractures is difficult; thus a combined surgical approach (anterior followed by posterior) may provide the best reduction, especially for subtype 1. LEVEL OF EVIDENCE: IV.

Intramuscular venous malformations of the calf: Surgical treatment outcomes of 57 patients.

OBJECTIVES: To report the outcomes of surgical treatment of calf intramuscular venous malformations (IMVMs) on pain, functional limitation, and quality of life. METHODS: We retrospectively reviewed 57 consecutive patients who had surgery for IMVM of the posterior compartment of the leg between 2010 and 2015. Treatments were all done at a single institution. RESULTS: Patients presented with pain (52), muscle contracture (14), or pulmonary embolism (4). Muscle involvement included the soleus muscle (n = 28, 49%), the gastrocnemius muscle (n = 25, 43%), and deep muscles (n = 4, 7%). Complete excision was possible in 52 patients (91%) and partial excision in 5 (9%). Thirty-five of 46 patients who had an MRI follow-up at six months had no residual venous malformation. At the final follow-up (mean 39 months), 32 of 40 patients seen had no residual pain and 37 had no residual functional impairment. CONCLUSION: In cases where IMVM is located in one muscle in the leg, we demonstrated that surgery yielded improvement in pain, function, and quality of life.

Craniocervical arterial dissection: spectrum of imaging findings and differential diagnosis.

Craniocervical artery dissection is a potentially disabling yet probably underrecognized condition that often occurs in young and middle-aged adults. Accurate and prompt diagnosis of this condition is crucial because timely and appropriate therapy can significantly reduce the risk of stroke and long-term sequelae. Because of the great diversity in the clinical features of craniocervical artery dissection, imaging plays a primary role in its diagnosis. The increased diagnosis of this disorder in the past two decades can be attributed to an increased awareness of the clinical manifestations of internal carotid artery and vertebral artery dissection and to use of noninvasive diagnostic imaging techniques. To achieve an accurate diagnosis of craniocervical artery dissection, it is important to be familiar with its pathologic features (intimal tear, intramural hematoma, and dissecting aneurysm); the spectrum of imaging findings at color duplex ultrasonography, computed tomographic angiography, magnetic resonance (MR) imaging with MR angiography, and conventional angiography; and potential pitfalls in image interpretation.

Cerebral venous thrombosis and multidetector CT angiography: tips and tricks.

Because of the great diversity of clinical features, its unforeseeable evolution, and a small proportion of cases that will worsen in the acute phase, cerebral venous thrombosis must be diagnosed as early as possible so that specific treatment can be started, typically transcatheter thrombolysis or systemic anticoagulation. Unenhanced computed tomography (CT) is usually the first imaging study performed on an emergency basis. Unenhanced CT allows detection of ischemic changes related to venous insufficiency and sometimes demonstrates a hyperattenuating thrombosed dural sinus or vein. Helical multidetector CT venography with bolus power injection of contrast material and combined use of two-dimensional and three-dimensional reformations (maximum intensity projection, integral display, and volume rendering) provides exquisite anatomic detail of the deep and superficial intracranial venous system and can demonstrate filling defects. However, common variants of the sinovenous system should not be mistaken for sinus thrombosis. A comprehensive diagnostic approach facilitates imaging of cerebral venous thrombosis with multidetector CT.

A Novel Technique of Ilio-Portal Venous Bypass to Relieve Symptoms of Pelvic Vein Congestion in a Patient with Inferior Vena Cava Agenesis.

A 37 year old man known to have inferior vena cava agenesis, presented to our center with severe symptoms of pelvic venous congestion. Surgical approach was attempted by creating a bypass between the right external iliac vein and the portal vein using an autogenous venous bypass (superficial femoral vein). Over a three year follow up, the bypass remained patent with complete resolution of symptoms. The ilio-portal venous bypass suggests a surgical alternative that has not been previously described.

Spontaneous dissection of branch renal artery- is conservative management safe and effective?

PURPOSE: We analyzed the long-term results of conservative management for spontaneous branch renal artery dissection. MATERIALS AND METHODS: In the last 6 years 8 patients were treated for acute spontaneous branch renal artery dissection at our department. The diagnosis was established by angiography, which showed primary branch artery dissection in all cases. All patients were treated with antihypertensive and platelet anti-aggregate therapy. None of them underwent surgery. After treatment patients were evaluated for blood pressure and renal function and by abdominal computerized tomography angiography with 3-dimensional reconstruction. RESULTS: Median followup was 72.3 months. In 6 patients blood pressure was controlled with a single antihypertensive agent. In another patient 3 antihypertensive agents were required. The remaining patient continued to have labile hypertension because of poor compliance with treatment. Renal function was normal in 7 patients. Control computerized tomography angiography showed proximal arterial remodeling in 6 patients and persistent occlusion of primary branches in 2. CONCLUSIONS: In our experience conservative management of spontaneous branch renal artery dissection is safe and effective. Surgical treatment should be proposed at the acute stage only in patients with malignant hypertension or renal failure and at the chronic stage in those with refractory renovascular hypertension.

Totally laparoscopic assisted thoracic aorta endograft delivery by direct sheath placement into the aorta.

This report describes the treatment of a descending thoracic aortic aneurysm with an endograft introduced through the infrarenal aorta by using the laparoscopic technique. The indication for infrarenal aorta access was the existence of heavy calcifications and stenosis of the both iliac arteries. We report what we think to be the first totally laparoscopic assisted thoracic aorta endograft delivery by direct sheath placement into the aorta.