Citations

PurposeThe purpose of this work is to derive and demonstrate constrained‐phase dual‐echo Dixon imaging within a maximum likelihood framework solved with a regularized graph‐cuts‐guided optimization.Theory and MethodsDual‐echo Dixon reconstruction is fundamentally underdetermined; however, adopting a constrained‐phase signal model reduces the number of unknowns and the nonlinear problem can be solved under a maximum likelihood framework. Period shifts in the field map (manifesting as fat/water signal swaps) must also be corrected. Here, a regularized cost function promotes a smooth field map and is solved with a graph‐cuts‐guided greedy binary optimization. The reconstruction shown here is compared to two other prevalent Dixon reconstructions in experimental phantom and human studies.ResultsReconstructed images of the water and fat signal are shown for a phantom study, and in vivo studies of foot/ankle, pelvis, and CE‐MRA of the thighs. The method shown here compared favorably with the other two methods. Large field inhomogeneities on the order of 20 ppm were resolved, thereby avoiding the fat and water signal swaps present in images reconstructed with the other methods.ConclusionConstrained‐phase dual‐echo Dixon imaging solved with a regularized graph‐cuts‐guided optimization has been derived and demonstrated to successfully separate water and fat images in the presence of large magnetic field inhomogeneities. Magn Reson Med 78:2203–2215, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

Pial arteriovenous fistulae (AVFs) are rare vascular abnormalities that are distinct from arteriovenous malformations and dural AVFs. These vascular lesions have been linked with trauma, ischemic syndromes, venous thrombotic diseases, and intracranial surgical procedures. In this report we describe a case of an intracranial ruptured pial AVF immediately following uneventful spinal surgery in an elderly patient with subsequent spontaneous resolution. He was a previous heavy smoker with a 60-pack-year history and alcohol abuse. His examination was positive for morbid obesity and mild weakness of the anterior tibialis and gastrocnemius muscles bilaterally. He underwent uneventful spinal surgery, suffering a generalized seizure shortly after extubation. Imaging studies demonstrated acute subarachnoid hemorrhage and cerebral angiography identified a pial AVF. He was stabilized medically and follow-up angiography demonstrated spontaneous resolution of the pial AVF. This case highlights a rare vascular malformation with rupture following uneventful spinal surgery.

Snapping biceps femoris tendon (BFT) over the fibular head is an uncommon cause of lateral knee pain. This study reports a case of nontraumatic painful snapping of the BFT due to a prominent fibular head that was persistent intraoperatively after fibular head resection. We describe a novel surgical technique of release of the anterior arm of the biceps tendon followed by soft tissue tenodesis to the popliteofibular ligament, as opposed to the remaining fibular head, to prevent iatrogenic fracture.