Detection of different kidney stone types: an ex vivo comparison of ultrashort echo time MRI to reference standard CT

BACKGROUND AND PURPOSE: With the development of ultrashort echo time (UTE) sequences, it may now be possible to detect kidney stones by using magnetic resonance imaging (MRI). In this study, kidney stones of varying composition and sizes were imaged using both UTE MRI as well as the reference standard of computed tomography (CT), with different surrounding materials and scan setups. METHODS: One hundred and fourteen kidney stones were inserted into agarose and urine phantoms and imaged both on a dual-energy CT (DECT) scanner using a standard renal stone imaging protocol and on an MRI scanner using the UTE sequence with both head and body surface coils. A subset of the stones representing all composition types and sizes was then inserted into the collecting system of porcine kidneys and imaged in vitro with both CT and MRI. RESULTS: All of the stones were visible on both CT and MRI imaging. DECT was capable of differentiating between uric acid and nonuric acid stones. In MRI imaging, the choice of coil and large field of view (FOV) did not affect stone detection or image quality. The MRI images showed good visualization of the stones' shapes, and the stones' dimensions measured from MRI were in good agreement with the actual values (R(2)=0.886, 0.895, and 0.81 in the agarose phantom, urine phantom, and pig kidneys, respectively). The measured T2 relaxation times ranged from 4.2 to 7.5ms, but did not show significant differences among different stone composition types. CONCLUSIONS: UTE MRI compared favorably with the reference standard CT for imaging stones of different composition types and sizes using body surface coil and large FOV, which suggests potential usefulness of UTE MRI in imaging kidney stones in vivo

MRI normal variants and pitfalls /

Includes bibliographical references and index.Liver and biliary system / Mellena D. Bridges and Nolan Karstaedt -- Gallbladder / Mellena D. Bridges -- Pancreas / Mellena D. Bridges -- Kidneys and adrenals / Mellena D. Bridges and Joseph G. Cernigliaro -- Spleen / Mellena D. Bridges -- Vasculature / Mellena D. Bridges, J. Mark McKinney, and Eric M. Walser -- Lumbar spine / Laura W. Bancroft and Debbie J. Merinbaum -- Female / Mellena D. Bridges -- Male / Mellena D. Bridges -- Unisex / Mellena D. Bridges and Robert A. Pooley -- Musculoskeletal / Laura W. Bancroft and John E. Kirsch -- Knee / Laura W. Bancroft and Patrick T. Liu -- Calf / Laura W. Bancroft and Robert A. Pooley -- Ankle/foot / Laura W. Bancroft and William B. Morrison.The head / David A. Miller, Debbie J. Merinbaum, and John E. Kirsch -- The neck / David A. Miller, Robert A. Pooley, and Laura W. Bancroft -- Cervical spine / David A. Miller and Laura W. Bancroft -- Shoulder/arm / Laura W. Bancroft, Jeffrey J. Peterson, and John E. Kirsch -- Elbow / Laura W. Bancroft, Thomas H. Berquist, and Debbie J. Merinbaum -- Forearm / Laura W. Bancroft, Thomas H. Berquist, and Debbie J. Merinbaum -- Wrist/hand / Laura W. Bancroft, Mark J. Kransdorf, and Thomas H. Berquist -- Breast / Elizabeth R. DePeri -- Thoracic spine / Laura W. Bancroft and Debbie J. Merinbaum -- Intrathoracic / Laura W. Bancroft, Ronald S. Kuzo, and J. Mark McKinney -

Safety and technique of ferumoxytol administration for MRI.

Ferumoxytol is an ultrasmall superparamagnetic iron oxide agent marketed for the treatment of anemia. There has been increasing interest in its properties as an MRI contrast agent as well as greater awareness of its adverse event profile. This mini-review summarizes the current state of knowledge of the risks of ferumoxytol and methods of administration

Impact of neoadjuvant chemoradiation on the tumor burden before liver transplantation for unresectable cholangiocarcinoma

The very early experience with liver transplantation (LT) for cholangiocarcinoma (CC) was dismal because of the poor survival outcomes and the high recurrence rates. However, LT for CC in conjunction with neoadjuvant chemoradiation recently has shown encouraging results, although the data are extremely limited. At our institution between 2001 and 2008, 22 CC patients underwent protocol orthotopic LT at a median age of 45 years (range = 24-63 years). At a median follow-up of 601.5 days (range = 111-1388 days), the median survival time of the cohort was 3.3 years. The 1-, 2-, and 3-year Kaplan-Meier survival probabilities were 90%, 70%, and 63%, respectively, whereas the historical 5-year survival rates were 0% to 18% for intrahepatic CC and 23% to 26% for extrahepatic CC when patients underwent transplantation without neoadjuvant therapy. These encouraging survival rates for patients with this type of tumor, which is difficult to diagnose and treat, are no less significant when they are compared to the national 1- and 3-year survival rates (86% and 68%, respectively) of patients undergoing deceased donor LT for malignant neoplasms of the liver (as reported by the United Network for Organ Sharing). In our series, disease recurrence was significantly associated with a larger residual tumor [6.3 versus 2.0 cm (mean values), P = 0.008] and with a shorter waiting time for LT after the chemoradiation protocol [18 versus 56 days (mean values), P = 0.04]. Our LT protocol for CC was found to be promising for patients with truly extrahepatic CC and for patients within stages I to IIB of the American Joint Committee on Cancer Staging system (100% survival at a median follow-up of 2.2 years), but the results were notably poor for patients with stage III extrahepatic CC (median survival = 1.2 years). These observations highlight the need for accurate preoperative staging of CC for ideal LT recipient selection and the importance of a low tumor burden and a longer wait after neoadjuvant therapy. More effective chemoradiation regimens for reducing the tumor burden and the appropriate timing of LT after neoadjuvant chemoradiation require further research. Copyright © 2012 American Association for the Study of Liver Diseases

Aberrant right hepatic arterial anatomy and pancreaticoduodenectomy: recognition, prevalence and management

AbstractBackgroundAberrant arterial anatomy is a common finding during foregut surgery. Anomalies to the right hepatic lobe are especially relevant during pancreaticoduodenectomy (PD) and their recognition serves to protect the blood supply to the liver and bile ducts. We report our experience with aberrant right hepatic arterial anatomy (ARHAA) found during PD.MethodsAll patients who underwent PD between February 2003 and June 2007 were retrospectively reviewed and those with ARHAA were identified. Preoperative imaging studies were assessed by one radiologist, graded according to the presence of ARHAA and compared with the original interpretations.ResultsWe found ARHAA in 31 of 191 patients (16.2%). Operative management included dissection and preservation in 24, transection and reconstruction in four, and transection and primary anastomosis in three patients. Reconstruction of ARHAA was carried out through interposition grafts in two patients and implantation into the gastroduodenal stump in two patients. No cases of arterial thrombosis, liver infarction, abscess formation or biliary fistula were demonstrated in the immediate postoperative period. Review of preoperative imaging interpretations found that only nine of 23 reports indicated the presence of ARHAA; however, the retrospective review of the images found that ARHAA was readily apparent in 24 patients.DiscussionRecognition of aberrant vasculature to the liver before PD is important. Preoperative imaging studies will often be adequate to identify these anomalies, but interpreting radiologists may not be aware of its clinical significance. Surgeons performing PD must be adept at managing ARHAA safely