Ersan Altun

Risk of Nephrogenic Systemic Fibrosis: Evaluation of Gadolinium Chelate Contrast Agents at Four American Universities

PURPOSE To retrospectively determine the benchmark incidence of nephrogenic systemic fibrosis (NSF) related to the confirmed use of different gadolinium chelate contrast agents at four U.S. university tertiary care centers. MATERIALS AND METHODS Institutional review board approval was obtained for this HIPAA-compliant multi-institutional study; the requirement for informed patient consent was waived. Patients who had a diagnosis of NSF between January 2000 and December 2006 were identified at four tertiary care centers with renal transplant and dialysis services. A standard checklist was used to acquire reliable data from the four centers. The diagnosis of NSF was confirmed histopathologically in all patients. The association of NSF development with gadolinium chelate contrast agent administration in each patient was assessed. The type and cumulative dose of contrast agent administered to each patient with NSF were determined at each center by using the standard checklist. The benchmark incidence of NSF was determined and expressed as the ratio of the number of patients with NSF who had undergone gadolinium chelate-enhanced magnetic resonance (MR) imaging, relative to the total number of patients who underwent gadolinium chelate-enhanced MR imaging at each tertiary care center. Benchmark incidences of NSF were compared among the four centers by using Fisher exact tests. RESULTS Gadodiamide was used at University of North Carolina at Chapel Hill (center A) and Emory University (center B), and gadopentetate dimeglumine was used at Wake Forest University (center C) and Thomas Jefferson University (center D) during the study period. Twenty-three patients at center A, nine patients at center B, three patients at center C, and one patient at center D had NSF and had undergone gadolinium chelate-enhanced MR imaging. The incidence of NSF was one in 2913 patients who underwent gadodiamide-enhanced MR examinations and one in 44,224 patients who underwent gadopentetate dimeglumine-enhanced MR examinations. CONCLUSION The benchmark incidence of NSF was much greater at the two centers where gadodiamide was used than at the two centers where gadopentetate dimeglumine was used.

Nephrogenic Systemic Fibrosis: Change in Incidence Following a Switch in Gadolinium Agents and Adoption of a Gadolinium Policy—Report from Two U.S. Universities

PURPOSE To determine the incidence of nephrogenic systemic fibrosis (NSF) in tertiary care centers of two U.S. universities following the switch from the use of gadodiamide to gadobenate dimeglumine and gadopentetate dimeglumine, and the adoption of restrictive gadolinium-based contrast agent (GBCA) policies. MATERIALS AND METHODS Institutional review board approval with waiver of informed consent was obtained for this Health Insurance Portability and Accountability Act-compliant retrospective study. NSF patients were identified between January 2000 and December 2006 at center A and between October 2003 and February 2007 at center B (preadoption periods); and from June 2007 to June 2008 at both centers (postadoption period). The numbers of patients who underwent gadolinium-enhanced magnetic resonance at each center, patients at risk for NSF at center A, and dialysis patients at center B were identified in the pre- and postadoption periods. Gadodiamide was the only agent used in the preadoption period. Gadobenate dimeglumine and gadopentetate dimeglumine were the agents used in the postadoption period. A restrictive GBCA policy that limits the use and dose of GBCAs in patients with risk factors was adopted in the postadoption period. Follow-up lasted 9 months from July 2008 to March 2009. Corresponding incidences were determined and compared with the Fisher exact test. RESULTS Respective total benchmark incidence of NSF at both centers, at-risk incidence of NSF at center A, and dialysis incidence of NSF at center B were 37 of 65 240, 28 of 925, and nine of 312 in the preadoption period and zero of 25 167, zero of 147, and zero of 402 in the postadoption period. All three incidences demonstrated significant differences (P < .0001, .024, and .001, respectively) between the pre- and postadoption periods. CONCLUSION Following the switch from gadodiamide to gadobenate dimeglumine and gadopentetate dimeglumine, and the adoption of restrictive GBCA policies, no NSF cases were observed at either center.

Focal pancreatic mass: Distinction of pancreatic cancer from chronic pancreatitis using gadolinium-enhanced 3D-gradient-echo MRI†

To determine the accuracy of MRI including T1‐weighted gadolinium (Gd)‐enhanced three‐dimensional‐gradient‐echo (3D‐GE) sequences to distinguish pancreatic cancer from chronic pancreatitis in patients with pancreatic mass or focal enlargement.

Quantitative and qualitative comparison of 3.0 T and 1.5 T MR imaging of the liver in patients with diffuse parenchymal liver disease

PURPOSE The purpose of our study was to compare signal characteristics and image qualities of MR imaging at 3.0T and 1.5T in patients with diffuse parenchymal liver disease. MATERIALS AND METHODS 25 consecutive patients with diffuse parenchymal liver disease underwent abdominal MR imaging at both 3.0T and 1.5T within a 6-month interval. A retrospective study was conducted to obtain quantitative and qualitative data from both 3.0T and 1.5T MRI. Quantitative image analysis was performed by measuring the signal-to-noise ratios (SNRs) and the contrast-to-noise ratios (CNRs) by the Students t-test. Qualitative image analysis was assessed by grading each sequence on a 3- and 4-point scale, regarding the presence of artifacts and image quality, respectively. Statistical analysis consisted of the Wilcoxon signed-rank test. RESULTS the mean SNRs and CNRs of the liver parenchyma and the portal vein were significantly higher at 3.0T than at 1.5T on portal and equilibrium phases of volumetric interpolated breath-hold examination (VIBE) images (P<0.05). The mean SNRs were significantly higher at 3.0T than at 1.5T on T1-weighted spoiled gradient echo (SGE) images (P<0.05). However, there were no significantly differences on T2-weighted short-inversion-time inversion recovery (STIR) images. Overall image qualities of the 1.5T non-contrast T1- and T2-weighted sequences were significantly better than 3.0T (P<0.01). In contrast, overall image quality of the 3.0T post-gadolinium VIBE sequence was significantly better than 1.5T (P<0.01). CONCLUSIONS MR imaging of post-gadolinium VIBE sequence at 3.0T has quantitative and qualitative advantages of evaluating for diffuse parenchymal liver disease.

Nephrogenic Systemic Fibrosis and Management of High-risk Patients

The purpose of this work is to provide current information on the rapidly evolving subject of nephrogenic systemic fibrosis (NSF), to establish the radiologic approach to the management of high-risk patients for NSF, and to assess the probabilistic risk of NSF compared to contrast induced nephropathy (CIN), as encountered with iodinated contrast media used in computed tomographic (CT) imaging. NSF is a disease process of considerable concern following gadolinium-containing contrast agents (GCCA) exposure in patients with diminished renal function. To minimize the possibility of NSF development in high-risk patients, GGCAs should not be used when they are not necessary, or the GCCAs, that have not at present been associated with NSF development, should be used at the lowest possible diagnostic dose, when they are necessary. Contrast-induced nephropathy is also a great risk in this patient population following the adminstration of iodinated contrast media (CM). In patients with diminished renal function who are not on regular dialysis, the risk of CIN following the administration of iodinated CM is higher than the risk of NSF following the administration of the most stable GCCAs. Risk benefit analysis should be performed prior to the administration of all CM, and the best combination of safety and diagnostic accuracy should be sought. Concern of NSF or CIN should not prevent the use of contrast agents in magnetic resonance imaging or computed tomography when they are deemed essential.

Quantitative and qualitative comparison of 1.5 and 3.0 Tesla MRI in patients with chronic liver diseases.

To compare the quantitative and qualitative image quality intra‐individually, at 1.5 and 3.0 Tesla (T) in patients with chronic liver diseases.

Gadolinium- and superparamagnetic-iron-oxide-enhanced MR findings of intrapancreatic accessory spleen in five patients

PURPOSE The purposes of this study were to describe dynamic gadolinium-enhanced magnetic resonance imaging (MRI) findings of intrapancreatic accessory spleen(s) (IPAS) in five patients and to show how superparamagnetic iron oxide (SPIO) enhancement can be used for definite characterization in two cases. MATERIALS AND METHODS An MRI database was searched for patients who had pancreatic tail lesions with imaging features compatible with IPAS between June 2005 and July 2007. Five (four male, one female) patients (age: mean+/-S.D., 58+/-9.8 years; range, 50-75 years) were identified. All patients were examined with standard gadolinium-enhanced MRI protocol. Additionally, two patients were examined with SPIO-enhanced MRI protocol. All MRI examinations were retrospectively and blindly evaluated by two radiologists for the predetermined findings, and their final diagnoses were noted. RESULTS One pancreatic tail lesion was detected in each patient. All of these lesions were single, focal, well-marginated and located within 3 cm of the distal tail of the pancreas. The mean size (mean+/-S.D.) of the lesions was (2.02+/-0.64)x(1.72+/-0.42) cm2, and all lesions had a rounded morphology. The signal intensity of all lesions was similar to that of the spleen on all sequences, including precontrast, postgadolinium and post-SPIO sequences. The reviewers confidently diagnosed IPAS in two patients who had SPIO-enhanced MRI. In the remaining three patients, the reviewers favored the diagnosis of IPAS based on the findings of standard gadolinium-enhanced MRI; however, they could not definitively exclude the other differential diagnoses. CONCLUSION The discovery of a well-marginated, rounded mass in the distal aspect of the tail of the pancreas with signal intensity features of the spleen on all precontrast and postgadolinium sequences suggests the diagnosis of IPAS. However, SPIO-enhanced MRI can be used to characterize the lesion and to establish the definite diagnosis of IPAS in case of clinical doubt.

Water excitation MPRAGE: an alternative sequence for postcontrast imaging of the abdomen in noncooperative patients at 1.5 Tesla and 3.0 Tesla MRI.

To evaluate the diagnostic image quality of postgadolinium water excitation–magnetization‐prepared rapid gradient‐echo (WE‐MPRAGE) sequence in abdominal examinations of noncooperative patients at 1.5 Tesla (T) and 3.0T MRI.

Enhancement of abdominal organs on hepatic arterial phase: quantitative comparison between 1.5- and 3.0-T magnetic resonance imaging

PURPOSE To compare the extent of enhancement of abdominal organs as shown on subphases of hepatic arterial phase quantitatively between 1.5- and 3.0-T MRI among patients with various abdominal conditions. MATERIALS AND METHODS A total of 126 patients, of whom 68 were women (age range, 3-82 years; mean age, 48 years) and 58 were men (age range, 6-73 years; mean age, 50 years), were included in the study. Of 126 patients, 98 were scanned at 1.5 T and 28 were scanned at 3.0 T. The presence of one of three predefined subphases of hepatic arterial phase was determined on early post-gadolinium sequence in each patient by two reviewers in consensus. Extent of enhancement of the kidney, pancreas, spleen and liver on these subphases was determined quantitatively by measuring the signal intensities. Mann Whitney-Wilcoxon test was used to compare the contrast enhancement of organs on each subphase between 1.5- and 3.0-T MRI. RESULTS The kidney, spleen, pancreas and liver demonstrated 1.79- to 2.45-, 1.65- to 1.97-, 1.66- to 1.8- and 1.1- to 2.02-fold higher enhancement on the subphases of hepatic arterial phase at 3.0 T compared to 1.5 T, respectively. The differences in contrast enhancement were significant for the kidney, pancreas and spleen on all subphases between 1.5 and 3.0 T. CONCLUSION The relative enhancement of the kidney, spleen and pancreas is consistently and significantly higher at 3.0 T than at 1.5 T in matched subphases of hepatic arterial enhancement.

MRI findings in nonalcoholic steatohepatitis: correlation with histopathology and clinical staging

PURPOSE To evaluate magnetic resonance imaging (MRI) findings of nonalcoholic steatohepatitis (NASH) and to determine the correlation of MRI findings with histopathology and Mayo End-Stage Liver Disease (MELD) score. MATERIALS AND METHODS Thirty patients (18 males, 12 females; mean age: 57+/-8.9 years; age range: 35-71 years) with histopathologically proven NASH who underwent MRI examinations between January 2001 and October 2005 were included in the study. Two radiologists retrospectively reviewed all magnetic resonance (MR) examinations in consensus to evaluate the presence and extent of predetermined findings of NASH including liver steatosis, early patchy liver enhancement indicating inflammation and liver fibrosis. The findings detected on MRI were correlated and compared to histopathological findings and MELD score by using nonparametric Spearman correlation coefficient and Kruskal-Wallis analysis of variance. RESULTS Liver steatosis was observed in 10 of 30 patients; early patchy liver enhancement, in 8 of 30 patients and liver fibrosis in 19 of 30 patients on MR images. Liver fibrosis was reticular in all these patients. There were statistically significant moderate correlations between MRI findings of liver steatosis and histopathologic grades of steatosis (r=0.43; P<.05), and between MRI findings of fibrosis and histopathologic stages of fibrosis (r=0.61; P<.001). Early patchy enhancement did not demonstrate statistically significant correlation with inflammation (P=.28). There was no statistically significant overall correlation between MRI findings of NASH and MELD score. CONCLUSION MRI findings of liver steatosis and fibrosis in NASH showed moderate correlations with histopathologic grades of steatosis and stages of fibrosis, but MRI findings of NASH did not demonstrate any significant correlations with MELD score.