Enhancement of abdominal structures on MRI at 1.5 and 3 T: a retrospective intraindividual crossover comparison.

OBJECTIVE: To quantitatively compare the extent of enhancement of abdominal structures on MRI in an intraindividual fashion at 1.5 and 3 T. METHODS: HIPAA-compliant, retrospective, longitudinal, intraindividual, crossover study, with waived informed consent, of consecutive individuals scanned at both 1.5 and 3 T closed-bore magnets using gadobenate dimeglumine during different phases of enhancement at tightly controlled arterial phase timing. Quantitative ROI measurements and qualitative sub-phase arterial phase assignments were independently performed by two radiologists. Qualitative discrepancies were resolved by a senior radiologist. RESULTS: Final population included 60 patients [41 female and 19 male; age, 49.35 ± 18.31 years (range 16-81); weight, 78.88 ± 20.3 kg (range 44.5-136)]. Similar enhancement peak patterns were noted at both field strengths. Interobserver agreement of quantitative evaluations was substantial. Significantly higher amplitudes of enhancement peaks were noted for all abdominal solid organs during all phases at 3 T, except for the pancreas (p = 0.17-0.30). Significantly higher amplitudes of enhancement peaks of the abdominal aorta at 1.5 T were noted. CONCLUSION: Similar peak patterns of enhancement for abdominal structures were observed at 1.5 and 3 T, with solid abdominal organs showing a higher percentage enhancement at 3 T, while unexpectedly higher aortic higher percentage enhancement was observed at 1.5 T. KEY POINTS: • Similar enhancement peak patterns at both field strengths for studied abdominal structures. • Significantly higher percentage enhancement of most abdominal organs at 3 T. • Non-statistically significant trend of higher pancreatic percentage enhancement at 3 T. • Significantly lower abdominal aortic percentage enhancement at 3 T.

Signal intensity change on unenhanced T1-weighted images in dentate nucleus following gadobenate dimeglumine in patients with and without previous multiple administrations of gadodiamide.

OBJECTIVES: To evaluate the impact of previous administration of gadodiamide and neural tissue gadolinium deposition in patients who received gadobenate dimeglumine. METHODS: Our population included 62 patients who underwent at least three administrations of gadobenate dimeglumine, plus an additional contrast-enhanced last MRI for reference, divided into two groups: group 1, patients who in addition to gadobenate dimeglumine administrations had prior exposure to multiple doses of gadodiamide; group 2, patients without previous exposure to other gadolinium-based contrast agent (GBCAs). Quantitative analysis was performed on the first and last gadobenate dimeglumine MRIs in both groups. Dentate nucleus-to-middle cerebellar peduncle signal intensity ratios (DN/MCP) and relative change (RC) in signal over time were calculated and compared between groups using generalized additive model. RESULTS: Group 1 showed significant increase in baseline and follow-up DN/MCP compared to group 2 (p < 0.0001). The RC DN/MCP showed a non-statistically significant trend towards an increase in patients who underwent previous gadodiamide (p = 0.0735). CONCLUSION: There is increased T1 signal change over time in patients who underwent gadobenate dimeglumine and had received prior gadodiamide compared to those without known exposure to previous gadodiamide. A potentiating effect from prior gadodiamide on subsequent administered gadobenate dimeglumine may occur. KEY POINTS: • Neural gadolinium deposition is associated with multiple administrations of less stable GBCAs. • Less stable GBCA effect on subsequent more stable GBCA administrations is undetermined. • Significant increase of DN/MCP was seen in patients with previous gadodiamide exposure. • RC DN/MCP showed a non-significant increase in patients who received previous gadodiamide. • Potentiating effects from prior gadodiamide on subsequent administered gadobenate dimeglumine may occur.

Gadolinium in Humans: A Family of Disorders.

OBJECTIVE: The literature informs us that gadolinium can cause health issues. At least four major gadolinium disorders, including the two well-recognized nephrogenic systemic fibrosis and severe acute adverse event, have been identified. CONCLUSION: We propose naming the histopathologically proven presence of gadolinium in brain tissue "gadolinium storage condition," and we describe a new entity that represents symptomatic deposition of gadolinium in individuals with normal renal function, for which we propose the designation "gadolinium deposition disease."

Bone Metastases of Hepatocellular Carcinoma: Appearance on MRI Using a Standard Abdominal Protocol.

OBJECTIVE: The purpose of this study is to describe the MRI features of hepatocellular carcinoma (HCC) bone metastases. MATERIALS AND METHODS: Thirty-three consecutive patients were included. Two radiologists performed qualitative and quantitative analysis. The coordinator searched for clinical and epidemiologic features related to patients and their primary liver tumors. Earlier MRI studies were also reviewed to determine whether bone metastases were already present and prospectively identified. Descriptive statistics and the Lin concordance correlation coefficient were used. RESULTS: Chronic hepatitis C virus infection was the most common cause of liver disease (20/32; 62.5%), and diffuse and multifocal HCC were the most frequent types of liver HCCs (28/33; 84.8%). Most lesions were located at the spine (109/155; 70.3%), with high signal intensity on fat-suppressed T1-weighted (54/62; 87.1%) and T2-weighted (53/62; 85.5%) images. Bone metastases were predominantly nodular (48/62; 77.4%), confined to the vertebral body (40/60; 66.7%), and best visualized at the arterial phase (40/62; 64.5%). The ring pattern of enhancement was present in 23 of 62 lesions, and the remaining lesions showed diffuse enhancement. Thirty-five of 62 (56.4%) bone metastases showed arterial peak of enhancement. In 13 of 33 (39.9%) patients, bone metastases were not prospectively reported. CONCLUSION: Most patients with bone metastases had chronic hepatitis C virus infection and diffuse or multifocal HCC. Metastases are most commonly appreciated as hypervascular focal moderately intensely enhancing nodular masses on the hepatic arterial dominant phase images, with concomitant moderately high signal intensity on fat-suppressed T1- and T2-weighted images.

Surrogate arterial phase imaging using a long duration (≈1.5 min) radial acquisition T1-weighted sequence: an alternative in patients unable to breath-hold.

BACKGROUND: Pediatric and adult patients unable to suspend respiration generally undergo magnetic resonance (MR) examinations that lack arterial phase imaging, which is a phase that provides substantial information on disease processes. An MR strategy that provides this type of information may be of considerable value. PURPOSE: To describe and assess the feasibility and enhancement quality of early-phase imaging utilizing long-duration radial 3D-GRE imaging by initiating the sequence prior to starting contrast injection. MATERIAL AND METHODS: Thirty-three consecutive patients (10 men, 23 women; 50.7 ± 25.5 years) underwent free-breathing gadolinium-enhanced radial 3D-GRE, with sequence initiation 30 s prior to contrast injection. Late hepatic arterial (LHA) phase was chosen for comparison. Images were evaluated for enhancement and overall image quality. Organ enhancement was calculated. Sub-group analysis was performed. RESULTS: Twenty-two examinations of radial 3D-GRE sequences were acquired during the LHA phase. Organ enhancement scores were of satisfactory to good quality (range, 3.32-3.82). There was a significant trend of superior overall enhancement quality scores in pediatrics and examinations performed at 3 T (P = 0.0225 and 0.0001, respectively). CONCLUSION: Arterial phase abdominal MR imaging is feasible using conventional radial 3D-GRE by adopting this simplistic proposed approach, which may allow arterial-phase imaging in patients unable to breath-hold.

Radiologist income, receipts, and academic performance: an analysis of many nations.

Background Considerable interest exists in comparison between healthcare systems across multiple countries, especially where cost enters the discussion. Purpose To evaluate the relationship between radiologists' income, receipts for studies, and academic performance across multiple countries. Material and Methods The annual income of radiologists and receipts for computed tomography (CT) and magnetic resonance imaging (MRI) were obtained based on a survey sent to expert radiologists practicing in 23 countries of varying developmental status. Articles published in generalist radiology journals determined the academic performance of each country. Results Among the developed countries, Canada has the highest estimated annual income for both private ($700,000/year) and university radiologists ($600,000/year) while Spain has the lowest income for private practice ($68,000/year) and Portugal has the lowest income for university practice ($57,300/year). Among the developing countries, Saudi Arabia has the highest incomes for both private ($210,000/year) and university ($140,000/year) radiologists and Vietnam has the lowest incomes for both private ($30,000/year) and university ($6,000/year) radiologists. Total receipts for CT and MRI studies ranged from $80/study (Portugal) to $1000/study (USA) in developed countries, and ranged from $30/study (Egypt) to $700/study (Saudi Arabia) in developing countries. A moderate correlation ( r = 0.482) was seen between radiologist's income and the receipts for combined practice in all countries. The radiology journal academic quotient was highest in The Netherlands among developed countries, and Turkey among developing countries. Conclusion A relatively broad range of radiologists' income is observed among developed and developing countries, which shows correlation with the receipts for advanced imaging studies. Countries with an acceptable compromise between income, receipts, and academic performance, may be the best models for other countries to emulate.

High Signal Intensity in Globus Pallidus and Dentate Nucleus on Unenhanced T1-weighted MR Images: Evaluation of Two Linear Gadolinium-based Contrast Agents.

PURPOSE: To determine if a correlation exists between the number of previous enhanced magnetic resonance (MR) imaging examinations and high signal intensity in the globus pallidus (GP) and dentate nucleus (DN) in patients who received gadodiamide (Omniscan), a linear nonionic gadolinium-based contrast agent, and in those who received gadobenate dimeglumine (MultiHance), a linear ionic contrast agent. MATERIALS AND METHODS: Institutional review board approval was obtained for this single-center retrospective study, with waiver of informed consent. The study population included 69 patients divided into two groups: Group 1 included patients who underwent gadodiamide-enhanced MR imaging, and group 2 included patients who underwent gadobenate dimeglumine-enhanced MR imaging. Two radiologists conducted a quantitative analysis of unenhanced T1-weighted images by using region of interest measurements. The GP-to-thalamus (TH) signal intensity ratio, DN-to-middle cerebellar peduncle (MCP) signal intensity ratio and relative percentage change (Rchange) between the first and last examinations for each patient were calculated. Relation between the signal intensity ratios and Rchange and the number of enhanced MR imaging examinations was analyzed by using a generalized additive model. Inter- and intraobserver agreement was evaluated with the Lin concordance correlation coefficient test. RESULTS: Group 1 included 23 patients (19 female), with a mean of 5.0 doses ± 2.4 (standard deviation) (range, 3-11 doses) administered. Group 2 included 46 patients (24 female) with a mean of 4.6 doses ± 2.2 (range, 3-11 doses) administered. The interval between the first and last examination was 1500.1 days ± 780.2 (range, 98-3097 days) for group 1 and 1086.2 days ± 582.9 (range, 94-2633) for group 2. All patients had normal liver and renal function. Gadodiamide showed a significant increase in DN:MCP and GP:TH (P < .001 for both) and in Rchange (P = .001 for GP:TH, P < .001 for DN:MCP). In group 2, there was no significant increase in DN:MCP or GP:TH over time or in Rchange for GP:TH, but there was a significant trend toward an increase in Rchange for DN:MCP (P = .013). Interobserver agreement was almost perfect (0.99; 95% confidence interval: 0.99, 0.99) for all evaluated structures. Intraobserver agreement was substantial to almost perfect for both readers. CONCLUSION: A significant increase in GP:TH and DN:MCP is associated with multiple gadodiamide-enhanced studies but not with gadobenate dimeglumine-enhanced studies, likely reflecting differences in stability and elimination of both contrast agents. Rate-of-change data indirectly suggest gadolinium deposition in the DN with gadobenate dimeglumine use, although it is considerably less than that with gadodiamide use.

Magnetic resonance imaging of acute appendicitis in pregnancy: a 5-year multiinstitutional study.

OBJECTIVE: The purpose of this study was to determine the diagnostic performance of magnetic resonance imaging (MRI) in the diagnosis of acute appendicitis during pregnancy in a multiinstitutional study. STUDY DESIGN: In this multicenter retrospective study, the cases of pregnant women who underwent MRI evaluation of abdominal or pelvic pain and who had clinical suspicion of acute appendicitis between June 1, 2009, and July 31, 2014, were reviewed. All MRI examinations with positive findings for acute appendicitis were confirmed with surgical pathologic information. Sensitivity, specificity, negative predictive values, and positive predictive values were calculated. Receiver operating characteristic curves were generated, and area under the curve analysis was performed for each participating institution. RESULTS: Of the cases that were evaluated, 9.3% (66/709) had MRI findings of acute appendicitis. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive values were 96.8%, 99.2%, 99.0%, 92.4%, and 99.7%, respectively. There was no statistically significant difference between centers that were included in the study (pair-wise probability values ranged from 0.12-0.99). CONCLUSION: MRI is useful and reproducible in the diagnosis of suspected acute appendicitis during pregnancy.

High-resolution 3D-GRE imaging of the abdomen using controlled aliasing acceleration technique - a feasibility study.

OBJECTIVES: To assess the feasibility of high-resolution 3D-gradient-recalled echo (GRE) fat-suppressed T1-weighted images using controlled aliasing acceleration technique (CAIPIRINHA-VIBE), and compare image quality and lesion detection to standard-resolution 3D-GRE images using conventional acceleration technique (GRAPPA-VIBE). MATERIALS AND METHODS: Eighty-four patients (41 males, 43 females; age range: 14-90 years, 58.8 ± 15.6 years) underwent abdominal MRI at 1.5 T with CAIPIRINHA-VIBE [spatial resolution, 0.76 ± 0.04 mm] and GRAPPA-VIBE [spatial resolution, 1.17 ± 0.14 mm]. Two readers independently reviewed image quality, presence of artefacts, lesion conspicuity, and lesion detection. Kappa statistic was used to assess interobserver agreement. Wilcoxon signed-rank test was used for image qualitative pairwise comparisons. Logistic regression with post-hoc testing was used to evaluate statistical significance of lesions evaluation. RESULTS: Interobserver agreement ranged between 0.45-0.93. Pre-contrast CAIPIRINHA-VIBE showed significantly (p < 0.001) sharper images and lesion conspicuity with decreased residual aliasing, but more noise enhancement and inferior image quality. Post-contrast CAIPIRINHA-VIBE showed significantly (p < 0.001) sharper images and higher lesion conspicuity, with less respiratory motion and residual aliasing artefacts. Inferior fat-suppression was noticeable on CAIPIRINHA-VIBE sequences (p < 0.001). CONCLUSION: High in-plane resolution abdominal 3D-GRE fat-suppressed T1-weighted imaging using controlled-aliasing acceleration technique is feasible and yields sharper images compared to standard-resolution images using standard acceleration, with higher post-contrast image quality and trend for improved hepatic lesions detection. KEY POINTS: • High-resolution imaging of the upper abdomen is clinically feasible using 2D-controlled aliasing acceleration technique. • High-resolution imaging yields significantly sharper images and increased hepatic lesions conspicuity. • High-resolution imaging yields significantly less respiratory motion and residual aliasing artefacts. • Controlled-aliasing offers substantial acquisition-time reduction in patients with breath-holding difficulties.

MR-PET co-registration in upper abdominal imaging: quantitative comparison of two different T1-weighted gradient echo sequences: initial observations.

PURPOSE: The purpose of this study is to quantitatively compare the accuracy of spatial registration of Cartesian breath-hold 3D-GRE and non-respiratory-triggered free-breathing radial 3D-GRE images with PET data acquisition on whole-body hybrid MR-PET system. MATERIALS AND METHODS: Eight patients (six men and two women; mean age, 56.6 ± 5.5 years) with nine ablated hepatocellular carcinomas constituted our study population. Spatial coordinates (x, y, z) of the estimated isocenters of the ablated areas were independently determined by two radiologists. Both T1-weighted sequences were performed in the axial plane. Distance between the isocenter of the lesion on PET images and on both T1-weighted images was measured, and misregistration was calculated. Statistical analysis was performed using Student t test. RESULTS: Misalignment values of the hepatic ablation zones between PET and MR images were calculated at 4.94 ± 1.35 mm (reader 1) and 4.89 ± 2.21 mm (reader 2) for Cartesian 3D-GRE sequence, and 2.48 ± 0.65 mm (reader 1) and 2.72 ± 0.44 mm (reader 2) for the radial 3D-GRE sequence, with p values of 0.0011 and 0.0133, respectively. CONCLUSION: Radial 3D-GRE offers improved registration accuracy with PET, supporting the use of this T1-weighted sequence in upper abdominal MR-PET studies.

Inter- and intra-individual comparative study of two gadolinium-based agents: A pilot study.

PURPOSE: The aim of the study was to evaluate the acute adverse events rate and enhancement properties of gadoterate meglumine (Dotarem(®)) and gadobenate dimeglumine (MultiHance(®)) in a small-scale controlled double-blinded study, using inter- and intra-individual comparisons. MATERIALS AND METHODS: Forty-one randomly selected patients were scanned with Dotarem(®). The rate of adverse reactions, qualitative and quantitative image evaluation was performed vs. a control group of 46 patients who underwent MultiHance(®) over the same 1-month time period (population 1), and 27 patients who underwent both Dotarem(®) and MultiHance(®)-enhanced body MRI studies within an 18-month period (population 2). Data were subjected to statistical analysis. RESULTS: Only 1 mild acute adverse event (vomiting) was observed in population 1 (with Dotarem(®)). Blinded assessment of image quality was good for both agents in all patients. Population 1 showed significantly higher liver percentage enhancement with MultiHance(®) (p < 0.0001). There was a trend to higher pancreas-to-liver enhancement with Dotarem(®), significant in population 2 (p = 0.0333). CONCLUSION: This small-scale multi-blinded study characterizes a strategy to objectively assess intravenous contrast agents, which may be an ideal method to evaluate whether a new contrast agent should be introduced for clinical use at any institution, and to re-evaluate the agent in standard use. Whenever available, intra-individual assessment may be ideal.

MR-PET evaluation of 1-month post-ablation therapy for hepatocellular carcinoma: preliminary observations.

PURPOSE: The purpose of the study was to evaluate the feasibility and protocol optimization of whole-body hybrid MR-PET system performed 1-month after post-locoregional thermoablative procedures for hepatocellular carcinomas (HCCs). MATERIALS AND METHODS: Eight patients (6 men and 2 women; mean age, 56.6 ± 5.5 years) with 9 ablated HCCs constituted our study population. Three readers interpreted the studies to determine the presence or absence of residual malignancy. Two readers independently assessed the fused MR-PET images to compare registration accuracy of two types of T2-weighted (triggered T2 half-Fourier acquisition single-shot turbo spin-echo and turbo spin-echo) and T1-weighted [Cartesian and radial 3D gradient echo (GRE)]. Image quality evaluation of both 3D-GRE T1-weighted sequences was evaluated. Kappa statistics were used to measure inter-observer agreement. Non-parametric Kruskal-Wallis and Wilcoxon signed-rank tests were used for qualitative data analysis. RESULTS: Definite residual tumor was observed in 3/9 ablations; two were PET positive. All residual tumors were isovascular on MRI. Radial 3D-GRE demonstrated significantly superior MR-PET subjective co-registration in comparison with the remaining sequences and showed a non-significant trend toward higher image quality scores than Cartesian GRE. CONCLUSION: Whole-body hybrid MR-PET is feasible as a part of 1-month follow-up post-locoregional thermoablative treatment for HCC. Radial 3D-GRE offers improved co-registration with PET data, with overall good image quality.

Post-contrast T1-weighted sequences in pediatric abdominal imaging: comparative analysis of three different sequences and imaging approach.

BACKGROUND: Post-contrast T1-weighted imaging is an essential component of a comprehensive pediatric abdominopelvic MR examination. However, consistent good image quality is challenging, as respiratory motion in sedated children can substantially degrade the image quality. OBJECTIVE: To compare the image quality of three different post-contrast T1-weighted imaging techniques-standard three-dimensional gradient-echo (3-D-GRE), magnetization-prepared gradient-recall echo (MP-GRE) and 3-D-GRE with radial data sampling (radial 3-D-GRE)-acquired in pediatric patients younger than 5 years of age. MATERIALS AND METHODS: Sixty consecutive exams performed in 51 patients (23 females, 28 males; mean age 2.5 ± 1.4 years) constituted the final study population. Thirty-nine scans were performed at 3 T and 21 scans were performed at 1.5 T. Two different reviewers independently and blindly qualitatively evaluated all sequences to determine image quality and extent of artifacts. RESULTS: MP-GRE and radial 3-D-GRE sequences had the least respiratory motion (P < 0.0001). Standard 3-D-GRE sequences displayed the lowest average score ratings in hepatic and pancreatic edge definition, hepatic vessel clarity and overall image quality. Radial 3-D-GRE sequences showed the highest scores ratings in overall image quality. CONCLUSIONS: Our preliminary results support the preference of fat-suppressed radial 3-D-GRE as the best post-contrast T1-weighted imaging approach for patients under the age of 5 years, when dynamic imaging is not essential.

Multiple focal nodular hyperplasia: MRI features.

PURPOSE: To describe MRI features of multiple Focal Nodular Hyperplasia (FNHs). METHODS: 40 consecutive subjects (37 females, mean age, 38.8years) were included. All studies were independently reviewed. This was an observational study to define the radiological features of multifocal FNH. RESULTS: 130 lesions were evaluated. The majority (88.5%), were peripheral in location. 92.3% lesions were lobulated. Marked enhancement was present in 94.6% lesions. In the portal venous and delayed phase, 46.2% and 47.7% lesions were mildly hyperintense. Central scar was present in 77% lesions. CONCLUSIONS: Distinctive features included predominant subcapsular location and mild hyperintensity in the delayed phase, seen in nearly 50% of FNHs.

Magnetic resonance imaging of the cirrhotic liver: diagnosis of hepatocellular carcinoma and evaluation of response to treatment - Part 1.

Magnetic resonance imaging (MRI) is the modern gold standard for the noninvasive evaluation of the cirrhotic liver. The combination of arterial phase hyperenhancement and delayed wash-out allows a definitive diagnosis of hepatocellular carcinoma (HCC) in patients with liver cirrhosis or chronic liver disease, without the requirement for confirmatory biopsy. That pattern is highly specific and has been endorsed in Western and Asian diagnostic guidelines. However, the sensitivity of the combination is relatively low for small HCCs. In this two-part review paper, we will address MRI of the cirrhotic liver. In this first part, we provide a brief background on liver cirrhosis and HCC, followed by descriptions of imaging surveillance of liver cirrhosis and the diagnostic performance of the different imaging modalities used in clinical settings. We then describe some of the requirements for the basic MRI technique, as well as the standard MRI protocol, and provide a detailed description of the appearance of various types of hepatocellular nodules encountered in the setting of the carcinogenic pathway in the cirrhotic liver, ranging from regenerative nodules to HCC.

A ressonância magnética (RM) é o método padrão para a avaliação não invasiva do fígado cirrótico. A combinação de hiper-realce arterial e wash-out tardio permite um diagnóstico definitivo de carcinoma hepatocelular (CHC) em pacientes com cirrose hepática ou doença hepática crônica, sem a necessidade de biópsia confirmatória. Este padrão é altamente específico e tem sido utilizado por guidelines de diagnóstico ocidentais e asiáticas. No entanto, a sensibilidade desta combinação é relativamente baixa para CHCs pequenos. Neste artigo de revisão de duas partes, irá ser efetuada uma revisão do papel da RM na avaliação do fígado cirrótico. Na primeira parte, faremos uma breve revisão sobre cirrose hepática e CHC, seguido da vigilância da cirrose hepática por imagem e desempenho diagnóstico das diferentes modalidades de imagem utilizadas na prática clínica. Depois, descreveremos alguns dos requisitos técnicos básicos para RM, protocolos de RM e uma descrição detalhada do aparecimento dos diferentes nódulos hepatocelulares encontrados no contexto da via carcinogênica do fígado cirrótico, desde nódulos regenerativos a CHC.

Magnetic resonance imaging of the cirrhotic liver: diagnosis of hepatocellular carcinoma and evaluation of response to treatment - Part 2.

In the second part of this review, we will describe the ancillary imaging features of hepatocellular carcinoma (HCC) that can be seen on standard magnetic resonance imaging (MRI) protocol, and on novel and emerging protocols such as diffusion weighted imaging and utilization of hepatocyte-specific/hepatobiliary contrast agent. We will also describe the morphologic sub-types of HCC, and give a simplified non-invasive diagnostic algorithm for HCC, followed by a brief description of the liver imaging reporting and data system (LI-RADS), and MRI assessment of tumor response following locoregional therapy.

Na segunda parte desta revisão descreveremos os achados de imagem auxiliares para o diagnóstico de carcinoma hepatocelular (CHC) e que podem ser observados num protocolo de ressonância magnética (RM) padrão e em protocolos emergentes que incluem imagens de difusão e aplicação de contrastes hepatoespecíficos/hepatobiliares. Descreveremos também os subtipos morfológicos de CHC e um algoritmo diagnóstico não invasivo simplificado para o CHC, seguido de uma breve descrição do liver imaging reporting and data system (LI-RADS) e avaliação por RM após terapêutica locorregional.

Comparison of Cartesian and radial acquisition on short-tau inversion recovery (STIR) sequences in breast MRI.

OBJECTIVE: The purpose of this study was to compare two short-tau inversion recovery (STIR) sequences, Cartesian and radial (BLADE) acquisitions, for breast magnetic resonance imaging (MRI) examinations. MATERIALS AND METHODS: Ninety-six women underwent 1.5 T breast MRI exam (48 Cartesian and 48 BLADE). Qualitative analysis including image artifacts, image quality, fat-suppression, chest-wall depiction, lesion detection, lymph node depiction and overall impression were evaluated by three blinded readers. Signal to noise ratios (SNRs) were calculated. Cronbach's alpha test was used to assess inter-observer agreement. Subanalyses of image quality, chest-wall depiction and overall impression in 15 patients with implants and image quality in 31 patients with clips were correlated using Pearson test. Wilcoxon rank sum test and t-test were performed. RESULTS: Motion artifacts were present in 100% and in 0% of the Cartesian and the BLADE exams, respectively. Chemical-shift artifacts were present in 8% of the Cartesian exams. Flow artifacts were more frequent on BLADE. BLADE sequence was statistically superior to Cartesian for all qualitative features (p < 0.05) except for fat-suppression (p = 0.054). In the subanalysis, BLADE was superior for implants and clips (p < 0.05). SNR was statistically greater for BLADE (48.35 vs. 16.17). Cronbach ranged from 0.502 to 0.813. CONCLUSION: BLADE appears to be superior to Cartesian acquisition of STIR imaging as measured by improved image quality, fewer artifacts, and improved chest wall and lymph node depiction.

OBJETIVO: Comparar duas sequências de aquisição, cartesiana e radial (BLADE) ponderadas em short-tau inversion recovery (STIR), em exames de ressonância magnética de mama. MATERIAIS E MÉTODOS: Noventa e seis pacientes foram submetidas a exame de ressonância magnética de mama em 1,5 T (48 aquisições STIR cartesianas e 48 aquisições STIR BLADE). A análise qualitativa incluindo artefatos, qualidade de imagem, supressão de gordura, avaliação da parede torácica, detecção de lesões, linfonodos e impressão geral foi avaliada independentemente por três leitores. Os signal to noise ratios (SNRs) foram calculados. Foi utilizado o teste alfa de Cronbach para avaliar a concordância interobservador. Subanálises da qualidade de imagem, avaliação da parede torácica e impressão geral em 15 pacientes com implantes e qualidade de imagem em 31 pacientes com clipes cirúrgicos foram correlacionadas aplicando o teste de Pearson. Os testes de Wilcoxon rank sum test e Student t foram utilizados para comparação qualitativa e quantitativa entre as duas sequências. RESULTADOS: Os artefatos de movimento estavam presentes em 100% e 0% dos exames de aquisição cartesiana e de BLADE, respectivamente. Os artefatos de desvio químico estavam presentes em 8% dos exames cartesianos. Artefatos de fluxo foram mais frequentes nas sequências BLADE. A sequência BLADE foi estatisticamente superior para todos os atributos qualitativos (p < 0,05), exceto na supressão de gordura (p = 0,054). O BLADE foi superior na avaliação dos implantes e clipes cirúrgicos (p < 0,05). O SNR foi estatisticamente superior na sequência BLADE (48,35 versus 16,17). Cronbach variou entre 0,502 e 0,813. CONCLUSÃO: A sequência BLADE foi superior à sequência de aquisição cartesiana de imagens na ponderação STIR, comprovada por uma melhor qualidade de imagem, menos artefatos e melhor avaliação da parede torácica e de linfonodos.

Technical aspects of MRI signal change quantification after gadolinium-based contrast agents' administration.

Over the last 2years several studies have been published regarding gadolinium deposition in brain structures in patients with normal renal function after repeated administrations of gadolinium-based contrast agents (GBCAs). Most of the publications are magnetic resonance imaging (MRI) based retrospective studies, where gadolinium deposition may be indirectly measured by evaluating changes in T1 signal intensity (SI) in brain tissue, particularly in the dentate nucleus (DN) and/or globus pallidi (GP). The direct correlation between T1 signal changes and gadolinium deposition was validated by human pathology studies. However, the variability of the MR equipment and parameters used across different publications, along with the inherent limitations of MRI to assess gadolinium in human tissues should be acknowledged when interpreting those studies. Nevertheless, MRI studies remain essential regarding gadolinium bio-distribution knowledge. The aim of this paper is to overview current knowledge of technical aspects of T1 signal intensity evaluation by MRI and describe confounding factors, with the intention to achieve higher accuracy and maximize reproducibility.

Gadolinium deposition disease: Initial description of a disease that has been around for a while.

PURPOSE: To describe the clinical manifestations of presumed gadolinium toxicity in patients with normal renal function. MATERIALS AND METHODS: Participants were recruited from two online gadolinium toxicity support groups. The survey was anonymous and individuals were instructed to respond to the survey only if they had evidence of normal renal function, evidence of gadolinium in their system beyond 30days of this MRI, and no pre-existent clinical symptoms and/or signs of this type. RESULTS: 42 subjects responded to the survey (age: 28-69, mean 49.1±22.4years). The most common findings were: central pain (n=15), peripheral pain (n=26), headache (n=28), and bone pain (n=26). Only subjects with distal leg and arm distribution described skin thickening (n=22). Clouded mentation and headache were the symptoms described as persistent beyond 3months in 29 subjects. Residual disease was present in all patients. Twenty-eight patients described symptoms following administration of one brand of Gadolinium-Based Contrast Agent (GBCA), 21 after a single GBCA administration and 7 after multiple GBCA administrations, including: gadopentetate dimeglumine, n=9; gadodiamide, n=4; gadoversetamide, n=4; gadobenate dimeglumine, n=4; gadobutrol, n=1; gadoteridol, n=2; and unknown, n=4. CONCLUSIONS: Gadolinium toxicity appears to arise following GBCA administration, which appears to contain clinical features seen in Nephrogenic Systemic Fibrosis, but also features not observed in that condition.