Rafael O.P. de Campos

Free-Breathing 3D T1-Weighted Gradient-Echo Sequence With Radial Data Sampling in Abdominal MRI: Preliminary Observations

OBJECTIVE The purposes of this study were to evaluate the feasibility of a free-breathing 3D gradient-recalled echo sequence with radial data sampling (radial 3D GRE) in abdominal MRI compared with a standard 3D GRE volumetric interpolated breath-hold examination (VIBE) sequence for imaging of cooperative patients and to perform a preliminary assessment in imaging of noncooperative patients. MATERIALS AND METHODS Fifty-five consecutively registered patients who underwent unenhanced and contrast-enhanced abdominal MRI with the free-breathing radial 3D GRE technique constituted the study population. Two readers independently and blindly evaluated the images. RESULTS Overall image quality with the contrast-enhanced radial 3D GRE sequence was lower than but rated at least nearly as good as that with the 3D GRE VIBE sequence (p < 0.0001). Higher scores were recorded for 3D GRE VIBE images with respect to pixel graininess, streaking artifact, and sharpness (p = 0.0009 to p < 0.0001). Except for sharpness of vessels on unenhanced images, results for the radial 3D GRE sequence did not differ significantly in the comparison of cooperative and noncooperative patients (p = 0.004). For imaging of noncooperative patients, radial 3D GRE images of children had higher ratings for shading (unenhanced, p = 0.0004; contrast-enhanced, p < 0.0001) and streaking artifacts on contrast-enhanced images (p = 0.0017) than did those of adults. Overall image quality was higher for pediatric patients. In lesion analysis, use of the 3D GRE VIBE sequence was associated with significantly greater detectability, confidence, and conspicuity than was use of the radial 3D GRE sequence (p = 0.00026-0.011). CONCLUSION A free-breathing radial 3D GRE sequence is feasible for abdominal MRI and may find application in imaging of patients who are unable to suspend respiration, especially children.

Combined hepatocellular carcinoma-cholangiocarcinoma: Report of MR appearance in eleven patients

To describe the magnetic resonance imaging (MRI) appearance of hepatic combined hepatocellular‐cholangiocarcinoma (cHCC‐CC) in 11 patients.

Quarter-Dose (0.025 mmol/kg) Gadobenate Dimeglumine for Abdominal MRI in Patients at Risk for Nephrogenic Systemic Fibrosis: Preliminary Observations

OBJECTIVE The purpose of this study is to evaluate the feasibility of 0.025 mmol/kg gadobenate dimeglumine, which is one quarter of the standard dose, for abdominal 3-T MRI studies in patients considered to be at risk for nephrogenic systemic fibrosis, using qualitative and quantitative measures and comparison with higher doses. MATERIALS AND METHODS The MRI database was retrospectively searched to select consecutive patients who underwent quarter-dose gadobenate dimeglumine-enhanced abdominal MRI at 3 T, between January 1, 2009, and January 15, 2010, and who underwent half-dose (0.05 mmol/kg) gadobenate dimeglumine-enhanced abdominal MRI at 3 T during one randomly chosen month. There were 25 patients in the final quarter-dose group (16 men and nine women; mean age, 57 years) and 44 patients in the half-dose group (21 men and 23 women; mean age, 58 years). The enhancement of abdominal organs and aorta was evaluated qualitatively and quantitatively on contrast-enhanced images. The overall quality of abdominal enhancement was also evaluated. RESULTS Reviewers rated the diagnostic enhancement of the evaluated organs in all phases of enhancement for both studied doses, but the half dose had significantly higher ratings than did the quarter dose in all comparisons (p, 0.034 to < 0.0001), except in the pancreas in the early hepatic venous phase (p = 0.095 for reviewer 1; p = 0.0611 for reviewer 2). The overall enhancement quality of the quarter dose was rated as good in all phases of enhancement, although it was significantly lower than that for the half dose (p ≤ 0.0001). The liver, pancreas, renal cortex, and aorta had 1.52-1.93-fold, 1.53-1.90-fold, 1.46-1.77-fold, and 1.58-1.84-fold, respectively, higher percentages of enhancement with the half dose than with the quarter dose (p, 0.0049 to < 0.0001). CONCLUSION A one-quarter dose of gadobenate dimeglumine at 3 T is a feasible alternative for abdominal MRI in patients at risk for nephrogenic systemic fibrosis. Our results might have important clinical implications, because greater safety may be conferred on patients with poor renal function with this low dose of contrast agent.

Hepatic tumor response evaluation by MRI.

Noninvasive evaluation of hepatic tumor response is necessary to improve the survival rate and quality of life of cancer patients. Among radiologic imaging modalities, MRI plays a significant role in the management of patients with hepatic tumor and is crucial for diagnosis, treatment planning and assessment of response or recurrence, because of its high contrast resolution, lack of ionizing radiation and the possibility of performing functional imaging sequences. This review provides an overview of the MRI findings after various treatments in patients with primary and secondary focal liver malignancies. The imaging methods described focus on the recent trends of using MRI techniques as biomarkers for disease. We also describe the appearance of successful and incomplete response for the various forms of treatment, including transcatheter arterial chemoembolization, ablative therapy, systemic chemotherapy and radiation therapy. Dynamic contrast‐enhanced MRI is regarded as an established noninvasive method and potential biomarker for tumor detection, as well as for the characterization of the tumor response. Diffusion‐weighted MRI, perfusion‐weighted MRI and MRS are also promising functional biomarkers to help select patients for various therapies and to assess the response to treatments. However, further validation and standardization should be performed before their widespread use as imaging biomarkers. Copyright

Enhancement of the liver and pancreas in the hepatic arterial dominant phase: Comparison of hepatocyte‐specific MRI contrast agents, gadoxetic acid and gadobenate dimeglumine, on 3 and 1.5 tesla MRI in the same patient

To evaluate the relative enhancement of liver, pancreas, focal nodular hyperplasia (FNH), pancreas‐to‐liver index, and FNH‐to‐liver index in the hepatic arterial dominant phase (HADP) after injection of hepatocyte‐specific MRI contrast agents, gadoxetic acid and gadobenate dimeglumine, on 3 and 1.5 Tesla (T) MRI in the same patient.

In-phase and out-of-phase gradient-echo imaging in abdominal studies: intra-individual comparison of three different techniques.

Background T1-weighted gradient-echo in-phase and out-of-phase imaging is an essential component of comprehensive abdominal MR exams. It is useful for the study of fat-containing lesions and to identify various disease states related to the presence of fat in the liver. Purpose To compare three T1-weighted in-phase and out-of-phase (IP/OP) gradient-echo imaging sequences in an intra-individual fashion, and to determine whether advantages exist for each of these sequences for various patient types. Material and Methods One hundred and eighteen consecutive subjects (74 men, 44 women; mean age 53.9 ± 13.8 years) who had MRI examinations containing all three different IP/OP sequences (two-dimensional spoiled gradient-echo [2D-GRE], three-dimensional gradient-echo [3D-GRE], and magnetization-prepared gradient-recall echo [MP-GRE]) were included. Two different reviewers independently and blindly qualitatively evaluated IP/OP sequences to determine image quality, extent of artifacts, lesion detectability and conspicuity, and subjective grading of liver steatosis for the various sequences. Quantitative analysis was also performed. Qualitative and quantitative data were subjected to statistical analysis. Results Respiratory ghosting, parallel imaging, and truncation artifacts as well as shading and blurring were more pronounced with 3D-GRE IP/OP imaging. Overall image quality was higher with 2D-GRE (P < 0.05). Detectability of low-fluid content lesions was lower with IP/OP MP-GRE sequences. MP-GRE sequences had the lowest SNRs (P < 0.001). Liver-to-spleen and liver-to-lesion CNRs were significantly lower with 3D-GRE and MP-GR, respectively (P < 0.001). Fat liver indexes showed strongly positive correlation between all sequences. Conclusion Currently, 2D-GRE remains the best approach for clinical IP/OP imaging. The good image quality of MP-GRE sequences acquired in a free-breathing manner should recommend its use in patients unable to suspend breathing.

Combined Chemical Shift Imaging With Early Dynamic Serial Gadolinium-Enhanced MRI in the Characterization of Adrenal Lesions

OBJECTIVE The purpose of this study was to retrospectively evaluate early dynamic serial gadolinium-enhanced and chemical-shift imaging (CSI) MRI to distinguish benign from malignant adrenal tumors. MATERIALS AND METHODS Between July 2007 and December 2011, 205 patients with 239 adrenal lesions (177 adenomas, 54 metastases, 5 pheochromocytomas, and 3 adrenal cortical carcinomas) underwent early dynamic serial gadolinium-enhanced MRI and CSI. CSI was assessed qualitatively and by calculating the adrenal index, and enhancement patterns were evaluated qualitatively and quantitatively. Statistical analyses were performed. RESULTS Most adenomas exhibited either an arterial blush or homogeneous enhancement, whereas most metastases showed early peripheral or heterogeneous enhancement. Visualization of higher enhancement on arterial and venous phases enabled differentiation of adenomas from metastases in most cases. Moderate to high signal intensity drop on CSI was seen in 95.4% of adenomas and 14.8% of metastases. In lesions with this level of signal intensity drop, 87 of 88 lesions with a capillary blush were adenomas. Early dynamic serial imaging alone was a significant (p < 0.0001) indicator of nonadenoma (area under the curve [AUC], 0.912) with optimal sensitivity of 81% and specificity of 93% for differentiating adenomas from nonadenomas. Combined analysis (CSI and early dynamic serial imaging) was also significant (p < 0.0001 and p=0.0014, respectively) for diagnosing nonadenomas (AUC, 0.983) with optimal sensitivity of 94% and specificity of 98%. CONCLUSION Early dynamic serial gadolinium-enhanced MRI aids in characterization of adrenal tumors, especially lesions that are categorized as indeterminate on the basis of CSI.

Comparison of a single shot T1-weighted in- and out-of-phase magnetization prepared gradient recalled echo with a standard two-dimensional gradient recalled echo: preliminary findings.

To compare in‐phase (IP) /out‐of‐phase (OP) single shot magnetization‐prepared gradient‐recalled‐echo (MP‐GRE) with a standard two‐dimensional gradient‐recalled‐echo (2D‐GRE), and to compare image quality of MP‐GRE in cooperative and noncooperative subjects.

Characterization of Adrenal Lesions With 1.5-T MRI: Preliminary Observations on Comparison of Three In-Phase and Out-of-Phase Gradient-Echo Techniques

OBJECTIVE The purpose of this study was to use previously described quantitative evaluation methods to compare the performance of 3D gradient-recalled echo (GRE) and magnetization-prepared (MP) GRE in-phase and out-of phase sequences with standard 2D GRE technique in the characterization of adrenal lesions. MATERIALS AND METHODS The study sample consisted of 44 consecutively registered patients (22 men, 22 women; mean age, 59.1 ± 11.6 years) with 50 adrenal lesions who underwent standard abdominal MRI that included in-phase and out-of-phase 2D GRE (n = 41), 3D GRE (n = 35), MP GRE (n = 36), or a combination of these techniques. The adrenal signal intensity (SI) index and adrenal-to-spleen, adrenal-to-liver, and adrenal-to-muscle SI ratios of each lesion were calculated and compared for the three techniques by independent samples Student t test. The area under the receiver operating characteristic (ROC) curve (AUC) for each evaluation method was determined, and comparisons of independent ROC curves were performed for all sequences. RESULTS For all sequences, the mean adrenal SI index and SI ratios of adenomas and nonadenomas differed significantly (p < 0.001). For the 3D GRE and MP GRE techniques, adrenal SI index and modified adrenal-to-spleen ratio, respectively, had the larger AUCs, but the difference was not statistically significant. Different thresholds for the three techniques were recommended for discriminating adenoma from nonadenoma. CONCLUSION The results of characterization of adrenal lesions with MP GRE and 3D GRE in-phase and out-of-phase MRI techniques are comparable to those obtained with the reference standard 2D GRE technique. Different thresholds should be selected according to the in-phase and out-of-phase techniques used and for the various evaluation methods.

Hepatic sarcoidosis: MR appearances in patients with chronic liver disease

PURPOSE To describe the MR appearances of hepatic sarcoidosis in patients with chronic liver disease and correlate the results with clinical stage of disease as measured with the Mayo end-stage liver disease (MELD) score. MATERIALS AND METHODS Twenty patients with chronic liver disease and histopathological diagnosis of hepatic sarcoidosis who underwent MR imaging were included in this study. Two abdominal radiologists retrospectively reviewed all images for the presence of cirrhosis, imaging pattern of the liver, intrahepatic biliary dilatation, presence of areas of parenchymal atrophy, presence of splenic nodules and lymphadenopathy. Imaging findings were correlated with the MELD score. RESULTS Of the patients, 14/20 had imaging findings of cirrhosis, 9/20 had a large macronodular pattern of liver cirrhosis and 5/20 had a diffuse pattern of liver cirrhosis. Peripheral wedge-shaped areas of parenchymal atrophy were observed in 10 patients. The combination of a central macronodular pattern and peripheral atrophy was observed in 9/20 patients. The pattern of cirrhosis had statistically significant correlation with the presence of wedge-shaped areas of parenchymal atrophy (p<0.005). No statistically significant difference was revealed between the clinical score of patients who had imaging findings consistent with cirrhosis and those who did not. CONCLUSION MR imaging appearances of chronic sarcoid liver disease are diverse and do not appear to correlate with severity of clinical disease. Large central regenerative nodules and wedge-shaped areas of peripheral parenchymal atrophy are frequent findings and may help to suggest the diagnosis.