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Purpose To develop a fast volumetric T1 mapping technique. Materials and methods A stack-of-stars (SOS) Look Locker technique based on the acquisition of undersampled radial data (>30× relative to Nyquist) and an efficient multi-slab excitation scheme is presented. A principal-component based reconstruction is used to reconstruct T1 maps. Computer simulations were performed to determine the best choice of partitions per slab and degree of undersampling. The technique was validated in phantoms against reference T1 values measured with a 2D Cartesian inversion-recovery spin-echo technique. The SOS Look Locker technique was tested in brain (n = 4) and prostate (n = 5). Brain T1 mapping was carried out with and without kz acceleration and results between the two approaches were compared. Prostate T1 mapping was compared to standard techniques. A reproducibility study was conducted in brain and prostate. Statistical analyses were performed using linear regression and Bland Altman analysis. Results Phantom T1 values showed excellent correlations between SOS Look Locker and the inversion-recovery spin-echo reference (r2 = 0.9965; p Conclusion A rapid volumetric T1 mapping technique was developed. The technique enables high-resolution T1 mapping with adequate anatomical coverage in a clinically acceptable time.

A deep learning MR parameter mapping framework which combines accelerated radial data acquisition with a multi-scale residual network (MS-ResNet) for image reconstruction is proposed. The proposed supervised learning strategy uses input image patches from multi-contrast images with radial undersampling artifacts and target image patches from artifact-free multi-contrast images. Subspace filtering is used during pre-processing to denoise input patches. For each anatomy and relaxation parameter, an individual network is trained. in vivo T(1) mapping results are obtained on brain and abdomen datasets and in vivo T(2) mapping results are obtained on brain and knee datasets. Quantitative results for the T(2) mapping of the knee show that MS-ResNet trained using either fully sampled or undersampled data outperforms conventional model-based compressed sensing methods. This is significant because obtaining fully sampled training data is not possible in many applications. in vivo brain and abdomen results for T(1) mapping and in vivo brain results for T(2) mapping demonstrate that MS-ResNet yields contrast-weighted images and parameter maps that are comparable to those achieved by model-based iterative methods while offering two orders of magnitude reduction in reconstruction times. The proposed approach enables recovery of high-quality contrast-weighted images and parameter maps from highly accelerated radial data acquisitions. The rapid image reconstructions enabled by the proposed approach makes it a good candidate for routine clinical use.

Superior soft tissue and contrast resolution of MR imaging benefits sensitivity to kidney cyst features and classification, which may have an impact on patient management and outcomes. Contrast-enhanced ultrasound (CEUS) may have nearly similar sensitivity for detection of cyst features yet is dependent on patient body habitus and adequacy of visualization windows for the kidneys, which does not have the same impact on MR imaging results. Both MR imaging and CEUS may provide superior kidney cyst assessment compared with contrast-enhanced CT; however, further research is needed, particularly for the identification of role of CEUS.

MR imaging has been optimized for the evaluation of a multitude of disease processes affecting the kidneys. A wide variety of noncontrast methods are available for the evaluation of both kidney structure and function, which are especially useful in clinical scenarios that obviate the use of intravenous contrast. Contrast-enhanced methods remain important, especially for tumor evaluation, and are used increasingly for functional analysis of quantitative biometrics, such as glomerular filtration rate and kidney blood flow.

Contrast media are essential to the practice of MR imaging. An increasing variety of agents have been approved for clinical use, specific contrast agents can often be tailored to a specific clinical question. Compared with CT contrast media, MR imaging contrast is well tolerated with an excellent safety record and a low incidence of adverse events. In this article, we review the pharmacology, indications, and the common adverse events of the intravenous and oral MR contrast agents most commonly used in contemporary imaging practice, including gadolinium-based contrast, manganese and iron-based agents and the most common oral contrast agents.

Purpose To evaluate the utility of dynamic, contrast-enhanced magnetic resonance imaging (MRI) in combination with single-shot T2-weighted (ssT2) sequences in the differentiation of lipid-poor adrenal adenomas from non-adenomas. Materials and methods This retrospective study was approved by the institutional review board and is HIPAA compliant. Between January 2007 and December 2010, 46 patients with MRI demonstrating a lipid-poor adrenal lesion who underwent either surgical resection or a minimum of 24 months of imaging follow-up were identified retrospectively. All images were retrospectively reviewed in blinded fashion by two radiologists. Each adrenal lesion was categorized by dynamic enhancement features and qualitative signal on ssT2 images and was categorized as an adenoma if it demonstrated homogenous enhancement in the arterial phase, washout with capsule enhancement in the delayed phase, and T2 signal isointense to normal adrenal tissue. Any lesion that did not fulfill all the criteria was classified as a non-adenoma. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for characterization of adenoma were calculated for each reader with 95% confidence intervals. A κ test assessed level of agreement between readers. Results Application of our criteria lead to an MRI diagnosis of lipid-poor adrenal adenoma with a sensitivity of 84.2–89.5% (16/19–17/19), specificity of 96.3% (26/27), positive predictive value of 94.1–94.4% (16/17–17/18), negative predictive value of 89.7–92.9% (26/29–26/28), and accuracy of 91.3–93.5% (42/46–43/46). Agreement between the two readers showed substantial κ agreement for the differentiation of adenoma from non-adenoma. Conclusions Dynamic, contrast-enhanced T1-weighted three-dimensional gradient echo sequences in combination with ssT2 images can accurately differentiate lipid-poor adrenal adenomas from non-adenomas.

Quantitating hepatic steatosis is important in many liver diseases and liver transplantation. Since steatosis estimation by pathologists has inherent intra- and inter-observer variability, we compared and contrasted computerized techniques with magnetic resonance imaging measurements, pathologist visual scoring, and clinical parameters. Computerized methods applied to whole slide images included a commercial positive pixel count algorithm and a custom algorithm programmed at our institution. For all liver samples (n=59), including pediatric, adult, frozen section, and permanent specimens, statistically significant correlations were observed between pathology, radiology, and each image analysis modality (r=0.75-0.97, p

BackgroundPreoperative imaging is often inadequate in excluding unresectable pancreatic cancer. Accordingly, many groups employ staging laparoscopy (SL), although none have evaluated SL after preoperative magnetic resonance imaging (MRI). We performed a retrospective, indirect cost-effectiveness analysis of SL after MRI for pancreatic head lesions.MethodsAll MRI scans administered for proximal pancreatic cancer between 2004 and 2008 were reviewed and the clinical course of each patient determined. We queried our billing database to render average total costs for all inpatients with proximal pancreatic cancer who underwent pancreaticoduodenectomy, palliative bypass or an endoscopic stenting procedure. We then performed an indirect evaluation of the cost of routine SL.ResultsThe average costs of hospitalization for patients undergoing pancreaticoduodenectomy, open palliative bypass and endoscopic palliation were: US$26122.43, US$21957.18 and US$11304.00, respectively. The calculated cost of SL without laparotomy was US$2966.25 or US$1538.61 prior to laparotomy. The calculated cost of treating unresectable disease by outpatient laparoscopy followed by endoscopy was US$5943.17. Routine SL would increase our costs by US$76967.46 (3.6%).ConclusionsStaging laparoscopy becomes cost-effective by diverting unresectable patients from operative to endoscopic palliation. Given the paucity of missed metastases on MRI, the yield of SL is marginal and its cost-effectiveness is poor. Future studies should address the utility of SL by both examining this issue prospectively and investigating the cost-effectiveness of endoscopic vs. surgical palliation in a manner that takes account of survival and quality of life data.

This manuscript will provide the background current understanding of Nephrogenic Systemic Fibrosis (NSF) necessary to be appreciated by radiologists who are practicing cross-sectional imaging including gadolinium based contrast agent (Gd-CA) enhanced MRI. Examination of the known risk factors for NSF provides a practical list of considerations including an appreciation of the degree of patient renal function, or dysfunction, and the type and dose of Gd-CA used. Data is presented to argue that we must consider not only the one-time dose, but particularly the cumulative Gd-CA life-time dose administered to a patient. Using the foundation of known risk factors for NSF, we can then assemble a working list of strategies that can be utilized in an imaging practice to minimize the risk of NSF for all patients, including those at highest risk for this disorder. This list includes a discussion of high stability Gd-CAs, cumulative dose monitoring and limits, dialysis, and more specific documentation in the medical records. Finally, the issues required to understand the information that should be provided to the patient prior to obtaining informed consent are discussed. The objectives of an informed consent is to ensure that the patient is properly informed and involved in the decision to proceed with a contrast enhanced MRI, and to provide documentation to establish that the medical facilities and the radiologist are themselves well-versed in the risks and benefits when making the decision to use contrast enhanced MRI for particular patients. The process of informed consent requires that there be a consideration of the risks of not performing the contrast enhanced MRI, or the relative risk of performing another test, particularly a contrast enhanced CT. This requires an appreciation of the risks of CT-related ionizing radiation and cancer, and the risk of iodine based contrast agents (I-CA) and contrast induced nephropathy (CIN). Data is presented to show that many, and perhaps the vast majority, of renal dysfunction patients are at greater risk of harm from I-CA related to CT as compared to high stability Gd-CAs used for MRI.

Small bowel involvement in Crohn’s disease (CD) occurs in 70% of patients with CD, and exclusive small bowel involvement is seen in approximately 30% of CD patients. Although endoscopy and histologic examination have served as the gold standard for the diagnosis of CD, diagnosing lesions in the small bowel from the distal duodenum to the terminal ileum has been a challenge. Critically important pathologic observations in CD are that (1) submucosal and serosal-mesenteric involvement is common and commonly involves the processes of fibrosis and/or inflammation and (2) mucosa has a high capacity for repair and evaluation of the mucosa alone may under represent the extent and activity of disease. Because disease management depends on appreciating the degree of active inflammatory disease, and the presence or absence of fistulae, the role of diagnostic tests should primarily be to provide an accurate assessment of these pathologic features. Herein we present the use of magnetic resonance imaging (MRI) as a powerful diagnostic modality for assessing the severity of the submucosa and serosa of small bowel in CD. We present the technical basis of a standard MRI study, and describe the range of MRI features of mild to severe and active in

Pelvic MR imaging using the combination of motion-insensitive T2-weighted single-shot fast spin echo and high soft tissue resolution standard T2-weighted fast spin echo techniques has helped to identify soft tissue abnormalities that directly correlate with the clinical and intraoperative findings related to pelvic floor prolapse. In particular, the authors have shown that pelvic MR imaging has the ability to identify changes related to uterosacral ligament disruption and to document the corrective changes after surgical repair of this ligament. In the future, pelvic MR imaging is expected to play a progressively larger role in preoperative planning for complex or uncertain cases and for more detailed evaluation of repair in cases that do not show good symptomatic response. Pelvic MR imaging should also help to document and advance knowledge of surgical repair methodology.

critical. The T1W precontrast images must include in-phase and out-of-phase acquisitions to assess hepatic lipid or iron content, and dynamically enhanced postgadolinium images. Timing of the arterial phase images also is critical for demonstration of acute hepatitis. The timing of the venous and equilibrium phase images are less critical, and are important for grading more severe acute hepatitis, demonstration of fibrosis, and for delineating vascular abnormalities. In cirrhosis, dynamic postgadolinium images are critical for detection and characterization of regenerative or dysplastic nodules and hepatocellular carcinoma (HCC). The same sequences that are useful for liver evaluation provide a comprehensive evaluation of all of the soft tissues of the abdomen, and allow depiction of most of the important diseases, and thus, facilitate use of a universal protocol for abdominal imaging. The following sections discuss MR imaging sequences that are used for the evaluation of diffuse liver diseases, including processes that lead to abnormal lipid metabolization, iron deposition disease, and perfusion abnormalities that are related to inflammation, fibrosis, vascular occlusion or infarction, and hemorrhage.

Over the past 15 years, MR imaging of the abdomen and pelvis has progressed significantly. Although initially found to be useful as an adjunct to CT imaging for selective applications, MR imaging now is establishing a role as a primary diagnostic technique. Increasing evidence shows that MR imaging has advantages over CT regarding diagnostic sensitivity and specificity for many abnormalities of solid organs, bile and pancreatic ducts, bowel, peritoneum, and retroperitoneum. This article discusses and contrasts current MR and CT techniques for imaging the liver and discusses the relative ability to identify and diagnose focal liver disease.

MR imaging of the pancreas has evolved with better understanding of pathologic and radiologic correlation and with continued improvement in rapid-acquisition breath-hold or breathing-independent MR imaging techniques. MR imaging should be considered essential in the evaluation of pancreatic disease and particularly for optimal presurgical detection, characterization, and staging of pancreatic masses.

The purpose of this study was to assess the feasibility of sequential administration of 2 different MR imaging contrast agents using a single visit protocol to image focal liver abnormalities. Twenty-one patients with known or suspected liver lesions were included in the study. All patients received a bolus intravenous injection of gadolinium chelate (Gd) and dynamically enhanced imaging performed. The patients then received an injection of mangafodipir trisodium (Mn) contrast and a second scan performed with an average delay of 62 min after the Gd bolus injection. The images were evaluated to determine the appearance of liver lesions after administration of each contrast agent, and for evidence of prior Gd administration adversely affecting evaluation of images acquired after Mn administration. Focal liver lesions were present in 19 patients, including 8 with liver metastases, 1 with liver lymphoma, 6 with hemangiomas, 3 with focal nodular hyperplasia (FNH), and 1 with hepatic abscess. In 2 other patients no liver lesions were identified in either the post-Gd or post-Gd-post-Mn scans. All malignant lesions identified on the post-Gd scan were also identified on post-Gd-post-Mn scans. Although the potential benefit for increasing detection sensitivity for hepatic metastases was not demonstrated, this is a preliminary series. This study does demonstrate the practicality for use a single visit sequential Gd-Mn protocol described here, with possible application of this technique for further assessment of the utility of combining Gd and Mn for detection of liver metastases.

Background Regardless of surgical effectiveness, ongoing activity in parathyroid localization in hyperparathyroidism (HPT) is an established enterprise. Sestamibi (MIBI), the most recent new modality, is being assessed in this regard. Methods Twenty mCl of 99 TC Sestamibi was administered intravenously in patients with prospective HPT. Images were assessed by pinhole and full-field gamma camera at 20 minutes and 2 hours. Dual-phase one isotope only was utilized. Patients were then studied for pathology and MIBI correlation. Results Sixty-three cases underwent MIBI scanning, 50, or 79%, of which were due to a single adenoma. Sensitivity showed in 41 of 50 adenomas and was 82% correct. Quadrant localization was 97%. Eleven patients showed hyperplasia with MIBI sensitivity of 82% on a case basis but only 31% for multiglandular disease. Overall MIBI sensitivity is 80%. One false-positive and one true-negative case were observed. All patients achieved eucalcemia. No operative morbidity of significance occurred. Conclusion Scanning with 99M Sestamibi dual-phase technique is the preferred mode of parathyroid localization in current practice. It is of assistance in primary HPT, essential in recurrent HPT, and of use in ectopic gland detection. It can support surgical intervention in the marginal HPT patient. Scanning still requires bilateral exploration for complete assessment.

Diagnostic cross-sectional imagers should agree on certain principles with regard to future directions. The ultimate goals for our techniques should include the ability to safely and noninvasively make specific and accurate diagnoses of tissue pathology in living functional tissue and to replace the need for extracting tissue specimens for the purpose of histopathology that have been considered historically to represent a diagnostic gold standard. Clinical diagnostic MR imaging of the abdomen and pelvis has been shown to provide an imaging technology that may be optimal for diagnostic sensitivity and specificity for a wide range of applications compared with ultrasound or CT. Although MR imaging historically has been perceived as being more complex and less accessible than CT, there has been strong incentive to continue to pursue MR development to minimize the need for CT with associated ionizing radiation, to avoid the use of iodinated contrast agents with potentially greater health risks compared with MR contrast agents, and to exploit MR capabilities for tissues characterization, both morphologically and functionally. One of the major themes to which I would like to draw the attention of the reader of this issue of the Magnetic Resonance Imaging Clinics of North America is that MR imaging provides more information about the tissues beyond

tion) OR time, estimated blood loss and transfusions, tumor size and histology, lymph node status, postoperative hematocrit and leukocyte count and postoperative NSAID use. We defined DGE as failure to tolerate a regular diet by postoperative day seven. Data was analyzed with alpha=0.05 using Fisher exact test for categorical variables and Mann-Whitney U test for continuous variables. RESULTS: A total of 114 patients with DGE were compared with 134 patients without DGE. Patients who suffered DGE were significantly more likely to have smaller tumors (p=0.015) and fewer positive lymph nodes (p=0.025), while patients without DGE were more likely to have received preoperative chemotherapy (p= 0.005) or preoperative radiation (p= 0.010). A possible explanation for these results is that patients with malignant disease have less normal functioning pancreatic parenchyma and are consequently less at risk for digestive symptoms resulting from pancreatic injury and inflammation. In addition, DGE was associated with an infection during hospitalization (p=0.008.) Hematocrit on the third postoperative day was significantly lower (p=0.019) for patients who experienced DGE , excluding patients who experienced post-operative bleeding. We hypothesize that DGE patients experienced more postoperative third space sequestration and bowel edema, resulting in greater hemodilution when sequestered fluid redistributed back into the vasculature. CONCLUSIONS: Contrary to our expectations, patients with smaller tumors and benign disease were more likely to experience DGE than patients with more advanced, malignant disease. As our ability to diagnose premalignant lesions improves, there will likely be more PD performed for benign disease, with a subsequent increase in the frequency of patients with DGE.

Background and Objective: The role of CT in follow up of hepatocellular carcinoma (HCC) after local ablative therapy have been demonstrated in many clinical experience, whereas the role of contrast enhanced ultrasonography (CEUS) is still under evaluation. The aim of this study is to evaluate the role of immediate CEUS in prediction 30-days CT follow up after single local ablative therapy with radiofrequency ablation (RFA) or percutaneous ethanol injection (PEI). Methods:100 consecutive patients with HCC treated 2006 to 2007 were prospectively included into the study. All the patients were treated with single session of PEI or RFA. After each single percutaneous procedure CEUS was performed in order to identify residual disease (persistence of contrast enhanced pattern). Three different CEUS patters were identified: 1-isovascular-hypervascular pattern, 2-ipovascular pattern, 3-avascular pattern. After 30 days complete necrosis of HCC was evaluated with contrast-enhanced CT scan in all cases. Results: Patients included into the study were submitted to RFA (43 patients) or PEI (57 patients) for HCCs with a mean diameter of 2.7 cm (range 1.5-5 cm). After RFA, isovascular pattern was found in 2% (1/43) of patients resulting in incomplete necrosis at CT; ipovascular pattern was found in 12% (5/43) patients that resulted in incomplete necrosis in 3/5 (60%); in 86% (37/43) avascular pattern was found with complete necrosis at CT in 28/37(76%) cases. Among the PEI group, isovascular pattern was found in 5% (3/57) of patients case resulting incomplete necrosis in 1/3 (33%) case; ipovascular pattern was found in 44% (25/57) of patients that resulted CT incomplete necrosis in 17/ 25(68%) ; in 19% (11/57) of patients avascular pattern was found with complete necrosis at CT in 2/11(18%) cases. Sensitivity, specificity, positive and negative predictive values for complete necrosis at CT of the CEUS avascular pattern after RFA were 93%, 31%, 76% and 67%,respectively, while the positive predictive value after PEI treatments was 18%. Conclusions Immediate CEUS control after percutaneous treatment of HCC have high predictive value after RFA where the avascular pattern is highly related with complete necrosis at 30 day CT. On the contrary predictive value of immediate CEUS after PEI is limited