Melissa Ong

CAIPIRINHA-Dixon-TWIST (CDT)-volume-interpolated breath-hold examination (VIBE) for dynamic liver imaging: Comparison of gadoterate meglumine, gadobutrol and gadoxetic acid

PURPOSE CAIPIRINHA-Dixon-TWIST (CDT)-VIBE is a robust method for abdominal magnetic resonance imaging providing both high spatial and high temporal resolution. The purpose of this study was to examine the influence of different gadolinium based contrast agents (GBCA) on image quality (IQ) with CDT-VIBE. MATERIALS AND METHODS In this IRB-approved, retrospective, inter-individual comparison study, 86 patients scanned at 3T were included. Within 28s, 14 high-resolution 3D datasets were acquired using CDT-VIBE. 37 patients received 0.1mmol/kg gadoterate meglumine, 28 patients 0.1mmol/kg gadobutrol, and 19 patients 0.1mL/kg gadoxetic acid. Two blinded, board-certified radiologists assessed the image quality on a 5 point scale, as well as the number of hepatic arterial dominant (HAD) phases. RESULTS Regardless of the GBCA utilized, CDT-VIBE resulted in good IQ in terms of best IQ achieved among all 14 datasets (gadobutrol 4.3, gadoterate meglumine 3.9, gadoxetic acid 3.7). With respect to worst IQ, the three groups showed statistically significant differences with gadobutrol receiving the highest rating (3.6) and gadoxetic acid the lowest (2.4) (gadoterate meglumine 3.0; 0.0014<p<0.0485). No statistically significant differences were found in the mean number of acquired HAD phases (gadobutrol 3.4, gadoterate meglumine 3.9, gadoxetic acid 3.1; 0.18<p<0.57). CONCLUSION Different gadolinium-based contrast agents can be utilized for dynamic liver imaging with CDT-VIBE resulting in good image quality.

Lack of increased signal intensity in the dentate nucleus after repeated administration of a macrocyclic contrast agent in multiple sclerosis: An observational study.

AbstractRecently, several studies reported increased signal intensity (SI) in the dentate nucleus (DN) after repeated application of gadolinium-based contrast agents (GBCAs), suggesting a deposition of gadolinium in this location. Patients with relapsing–remitting multiple sclerosis (RRMS) frequently show increased permeability of the blood–brain barrier as part of the inflammatory process in the brain parenchyma, which theoretically might increase the risk of gadolinium deposition. In this retrospective study, we investigated a possible increasing SI in the DN after repeated administrations of the macrocyclic contrast agent gadoterate meglumine.Forty-one RRMS patients (33 women, mean age 38 years) with at least 6 prior gadolinium-enhanced examinations (single dose gadoterate meglumine) were identified. A total of 279 unenhanced T1-weighted examinations were analyzed.SI ratio differences did not differ between the first and last MRI examination, neither for the DN-to-pons ratio (P = 0.594) nor for the DN-to-cerebellum ratio (P = 0.847). There was no correlation between the mean DN-to-pons, or between the mean DN-to-cerebellum SI ratio and the number of MRI examinations (P = 0.848 and 0.891), disease duration (P = 0.676 and 0.985), and expanded disability status scale (EDSS) (P = 0.639 and 0.945).We found no signal increases in the DN after a minimum of 6 injections of the macrocyclic GBCA gadoterate meglumine in RRMS patients. This warrants further investigations in regard to the true pathophysiologic basis of intracerebral gadolinium deposition.

Fifty Years of Technological Innovation: Potential and Limitations of Current Technologies in Abdominal Magnetic Resonance Imaging and Computed Tomography.

AbstractMagnetic resonance imaging (MRI) has become an important modality for the diagnosis of intra-abdominal pathology. Hardware and pulse sequence developments have made it possible to derive not only morphologic but also functional information related to organ perfusion (dynamic contrast-enhanced MRI), oxygen saturation (blood oxygen level dependent), tissue cellularity (diffusion-weighted imaging), and tissue composition (spectroscopy). These techniques enable a more specific assessment of pathologic lesions and organ functionality. Magnetic resonance imaging has thus transitioned from a purely morphologic examination to a modality from which image-based disease biomarkers can be derived. This fits well with several emerging trends in radiology, such as the need to accurately assess response to costly treatment strategies and the need to improve lesion characterization to potentially avoid biopsy. Meanwhile, the cost-effectiveness, availability, and robustness of computed tomography (CT) ensure its place as the current workhorse for clinical imaging. Although the lower soft tissue contrast of CT relative to MRI is a long-standing limitation, other disadvantages such as ionizing radiation exposure have become a matter of public concern. Nevertheless, recent technical developments such as dual-energy CT or dynamic volume perfusion CT also provide more functional imaging beyond morphology.The aim of this article was to review and discuss the most important recent technical developments in abdominal MRI and state-of-the-art CT, with an eye toward the future, providing examples of their clinical utility for the evaluation of hepatic and renal pathologies.

Where do we stand? Functional imaging in acute and chronic pulmonary embolism with state-of-the-art CT

Nowadays, CT pulmonary angiography (CTPA) is the diagnostic imaging modality of choice for acute and chronic pulmonary embolism (PE) in order to assess vascular anatomy and parenchymal morphology. Over the past decade, several prognostic CTPA markers associated with an increased risk of adverse clinical events and in-hospital mortality have been evaluated, namely cardiac chamber dimensions, obstruction scores, and visualization of iodinated contrast material in the lung parenchyma by dual-energy (DE) CTPA. This article reviews the current status and potential prognostic advantages of CTPA or DE CTPA with its recent developments for accessing right ventricular dysfunction and the assessment of first pass lung perfusion with DE CTPA in the diagnosis of acute and chronic PE.

23Na-magnetic resonance imaging of the human lumbar vertebral discs: in vivo measurements at 3.0 T in healthy volunteers and patients with low back pain.

BACKGROUND CONTEXT 1H magnetic resonance imaging (MRI) of the spine can rule out common causes of low back pain (LBP), such as disc protrusions or nerve root compression; however, no significant causal relation exists between morphology and the extent of symptoms. Functional MRI techniques, such as 23Na, may provide additional information, allowing indirect assessment of vertebral glycosaminoglycan concentrations, decreases in which are associated with early degenerative changes. PURPOSE To evaluate 23Na-MRI of asymptomatic healthy volunteers and symptomatic patients with LPB and correlate the results to the Pfirrmann classification of MRI disc morphology. STUDY DESIGN Retrospective cohort study at an academic medical center. PATIENT SAMPLE Two groups were studied: (1) 55 healthy volunteers (31 men, 24 women; mean age 28.8 years) and (2) 12 patients (6 men, 6 women; mean age: 35.3 years) with a recent history of LBP. METHODS Lumbar spines of the aforementioned groups were examined on a 3.0 T MRI scanner with morphological 1H and 23Na imaging. Intervertebral disc (IVD) 23Na at each level was normalized (23Nanorm). Distribution and differences between mean 23Nanorm corresponding to each Pfirrmann classification were evaluated in the two study groups (analysis of variance). Linear correlations between 23Nanorm, body mass index (BMI), and age were assessed (Pearson correlation coefficient). Gender-dependent differences were evaluated (paired t test). OUTCOME MEASURES Physiological measure: IVD 23Nanorm as determined by 23Na-MRI. RESULTS A normal distribution of 23Nanorm was confirmed for both groups (p=.072 and p=.073, respectively). The mean Pfirrmann score statistically significantly differed between them (p<.0001). 23Nanorm was statistically significantly reduced in degenerated IVDs (Pfirrmann scores 4+5) (p<.0001). No statistically significant differences were seen for the mean 23Nanorm of IVDs with the same Pfirrmann score in healthy volunteers and patients (.469<p<.967). Age (0.007<R2<0.202) and BMI (0.074<R2<0.288) showed either weak or no correlation to 23Nanorm. Mean 23Nanorm was significantly (p=.0002) greater in women relative to men. CONCLUSIONS The results underline the feasibility and robustness of 23Na-MRI of human IVDs and affirm, in a large cohort, decreases in 23Na IVD content seen with disc degeneration.

Quantitative Perfusionsbildgebung in der Magnetresonanztomographie

CLINICAL/METHODICAL ISSUE Magnetic resonance imaging (MRI) is recognized for its superior tissue contrast while being non-invasive and free of ionizing radiation. Due to the development of new scanner hardware and fast imaging techniques during the last decades, access to tissue and organ functions became possible. One of these functional imaging techniques is perfusion imaging with which tissue perfusion and capillary permeability can be determined from dynamic imaging data. STANDARD RADIOLOGICAL METHODS Perfusion imaging by MRI can be performed by two approaches, arterial spin labeling (ASL) and dynamic contrast-enhanced (DCE) MRI. While the first method uses magnetically labelled water protons in arterial blood as an endogenous tracer, the latter involves the injection of a contrast agent, usually gadolinium (Gd), as a tracer for calculating hemodynamic parameters. PERFORMANCE Studies have demonstrated the potential of perfusion MRI for diagnostics and also for therapy monitoring. ACHIEVEMENTS The utilization and application of perfusion MRI are still restricted to specialized centers, such as university hospitals. A broad application of the technique has not yet been implemented. PRACTICAL RECOMMENDATIONS The MRI perfusion technique is a valuable tool that might come broadly available after implementation of standards on European and international levels. Such efforts are being promoted by the respective professional bodies.ZusammenfassungKlinisches/methodisches ProblemDie Magnetresonanztomographie (MRT) zeichnet sich durch einen überlegenen Gewebekontrast aus, während sie nichtinvasiv und frei von ionisierender Strahlung ist. Sie bietet Zugang zu Gewebe- und Organfunktion. Eine dieser funktionellen bildgebenden Verfahren ist die Perfusionsbildgebung. Mit dieser Technik können u. a. Gewebeperfusion und Kapillarpermeabilität aus dynamischen Bilddaten bestimmt werden.Radiologische StandardverfahrenPerfusionsbildgebung mithilfe der MRT kann durch 2 Ansätze, nämlich „arterial spin labeling“ (ASL) und dynamische kontrastverstärkte (DCE-)MRT durchgeführt werden. Während die erste Methode magnetisch markierte Wasserprotonen im arteriellen Blut als endogenen Tracer verwendet, erfolgt bei der DCE-MRT eine Injektion eines Kontrastmittels, üblicherweise Gadolinium (Gd) als Tracer für die Berechnung hämodynamischer Parameter.LeistungsfähigkeitAus Studien werden das Potenzial und die Möglichkeiten der MRT-Perfusionsbildgebung deutlich, sei es in Bezug auf die Diagnostik oder aber auch zunehmend im Bereich des Therapiemonitorings.BewertungNutzung und Anwendung der MRT-Perfusionsbildgebung beschränken sich jedoch auf spezialisierte Zentren wie Universitätskliniken. Eine breite Anwendung der Technik ist bisher leider nicht erfolgt.Empfehlung für die PraxisDie MRT-Perfusionsbildgebung ist ein wertvolles Tool, das im Rahmen europäischer und internationaler Standardisierungsbemühungen für die Praxis zukünftig einsetzbar werden sollte.AbstractClinical/methodical issueMagnetic resonance imaging (MRI) is recognized for its superior tissue contrast while being non-invasive and free of ionizing radiation. Due to the development of new scanner hardware and fast imaging techniques during the last decades, access to tissue and organ functions became possible. One of these functional imaging techniques is perfusion imaging with which tissue perfusion and capillary permeability can be determined from dynamic imaging data.Standard radiological methodsPerfusion imaging by MRI can be performed by two approaches, arterial spin labeling (ASL) and dynamic contrast-enhanced (DCE) MRI. While the first method uses magnetically labelled water protons in arterial blood as an endogenous tracer, the latter involves the injection of a contrast agent, usually gadolinium (Gd), as a tracer for calculating hemodynamic parameters.PerformanceStudies have demonstrated the potential of perfusion MRI for diagnostics and also for therapy monitoring.AchievementsThe utilization and application of perfusion MRI are still restricted to specialized centers, such as university hospitals. A broad application of the technique has not yet been implemented.Practical recommendationsThe MRI perfusion technique is a valuable tool that might come broadly available after implementation of standards on European and international levels. Such efforts are being promoted by the respective professional bodies.

Sodium MRI of T1 High Signal Intensity in the Dentate Nucleus due to Gadolinium Deposition in Multiple Sclerosis

Recently, several studies reported increased signal intensity (SI) of the dentate nucleus (DN) on unenhanced T1‐weighted magnetic resonance imaging (MRI) as a possible consequence of multiple applications of gadolinium‐based contrast agents. The aim of this study was to investigate with sodium (23Na) MRI possible tissue abnormalities of the DN in multiple sclerosis (MS) patients.

Radiation Dose Levels of Retrospectively ECG-Gated Coronary CT Angiography Using 70-kVp Tube Voltage in Patients with High or Irregular Heart Rates.

RATIONALE AND OBJECTIVES Despite ongoing technical refinements, coronary computed tomography angiography (cCTA) remains challenging in its diagnostic value by electrocardiographic (ECG) misregistration and motion artifacts, which commonly occur in patients with atrial fibrillation and high or irregular heart rates. The aim of this study was to evaluate the radiation dose and the number of inconclusive coronary segments at cCTA using retrospective ECG gating at 100 and 70 kV. MATERIALS AND METHODS With institutional review board approval, 154 patients (median age 54 years, 98 men) with high or irregular heart rate prospectively underwent retrospectively ECG-gated cCTA without tube current modulation on a third-generation dual-source computed tomography (DSCT) system at 70 kV (n = 103) or on a second-generation DSCT system at 100 kV (n = 51). Images were reconstructed in best diastolic phase (BDP), best systolic phase (BSP), and in all phases (APs) at 10% intervals across the R-R cycle. Objective and subjective image qualities were evaluated as well as the presence of motion artifacts with the three different reconstruction approaches. RESULTS The mean heart rate was 93 ± 16 bpm. The mean effective radiation dose was 4.5 mSv for 70 kV compared to 8.4 mSv for 100 kV (P < 0.05). At BDP reconstruction, 71% (n = 110) of the patients showed motion artifacts in one or more coronary segments. At BSP reconstruction, the number of patients with motion artifacts decreased to 37% (n = 57). In contrast, if images were reconstructed with the AP approach, all vessels and coronary segments were evaluable with both cCTA protocols. CONCLUSIONS Retrospectively ECG-gated cCTA at 70 kV results in 52% decreased radiation dose. Further using the AP algorithm allowed for diagnostic evaluation of all coronary segments for stenosis, in contrast to BDP or BSP phase alone.

Onkologische Erkrankungen und postoperative Veränderungen der Harnblase und der ableitenden Harnwege

ZusammenfassungMalignome im Nierenbeckenkelchsystem oder in den Ureteren stellen eine diagnostische Herausforderung dar, der mittels mehrphasiger [CT (Computertomographie)-]Untersuchungsprotokolle begegnet werden kann. Neben dem direkten Tumornachweis erlaubt die Schnittbildgebung hier eine Umgebungsdiagnostik und kann im Sinne eines One-Stop-Shop sowohl zur Einordnung der Lokalsituation als auch zum Staging dienen. Urothelkarzinome sind überwiegend in der Harnblase lokalisiert. Die CT und in jüngster Zeit auch in verstärktem Maße die Magnetresonanztomographie (MRT) können auch hier zur Einteilung des TNM-Stadiums entscheidende Informationen beisteuern. Eine Kombination aus klinischen, histologischen, bildmorphologischen und funktionellen Parametern ermöglicht eine Risikostratifizierung und eine stadienadaptierte Therapie.AbstractIn the challenging evaluation of upper urinary tract malignanciesmultidetector computed tomography (CT) has become the standard imaging method. Cross sectional imaging not only allows the detection and visualization of the tumor itself but also provides nodal and metastasis staging in one examination (one-stop-shop). The majority of urothelial carcinomas are located in the urinary bladder. In this case, CT and more recently magnetic resonance imaging (MRI) can also deliver decisive information regarding TNM classification. A combination of clinical, histological, morphological and functional parameters allows both risk stratification and a targeted therapy based on the individual tumor stage.In the challenging evaluation of upper urinary tract malignancies multidetector computed tomography (CT) has become the standard imaging method. Cross sectional imaging not only allows the detection and visualization of the tumor itself but also provides nodal and metastasis staging in one examination (one-stop-shop). The majority of urothelial carcinomas are located in the urinary bladder. In this case, CT and more recently magnetic resonance imaging (MRI) can also deliver decisive information regarding TNM classification. A combination of clinical, histological, morphological and functional parameters allows both risk stratification and a targeted therapy based on the individual tumor stage.

Steady state vascular imaging with extracellular gadobutrol: evaluation of the additional diagnostic benefit in patients who have undergone a peripheral magnetic resonance angiography protocol

BackgroundTo evaluate the feasibility and additional diagnostic benefit of a high-resolution steady state 3D-volume interpolated breath-hold exam (VIBE) sequence between a continuous table movement (CTM) MR angiography of the entire runoff vasculature and a time-resolved (TWIST) MRA of the calves.MethodsIn this retrospective IRB approved study 224 patients (72 women, 152 men, mean age 67.29 ± 13.9) were included who had undergone a low-dose MR angiographic protocol at 3T (Siemens TimTrio) after injection of 0.1 mmol/kg gadobutrol including a CTM MRA, a time-resolved MRA of the calf station and a steady state 3D VIBE sequence prior to the time-resolved MRA. One board-certified radiologist rated the image quality of the steady state VIBE sequences on an ordinal three point scale (excellent, good, poor) and analyzed the images for additional diagnostic findings of and beyond the vascular system in comparison to the CTM MRA and the time-resolved MRA. Descriptive statistics and demographic patient data were used for further evaluation.ResultsThe image quality of the steady state imaging of the pelvis, upper and lower leg was excellent in up to 88%, 84% and 47%, respectively, while poor image quality was only detected in the upper (2%) and lower leg (6%). An additional diagnostic benefit was found in 44% of the patients overall. The most common relevant pathologies included inflammatory processes of the soft tissues (26%), thrombi (14%), abscesses (13%) and tumors (11%). In subgroups of patients above the age of 60, 65, 70, 75 and 80 years an additional pathology was found in 50% 33%, 44%, 65% and 58%, respectively. There was no significant difference in terms of additional findings between men and women (46% and 39%, p > 0.05) and inpatients and outpatients (42% and 45%, p > 0.05).ConclusionSteady state imaging is also feasible with extracellular contrast agents with good image quality yielding additional diagnostic findings in up to 44% and above in patients older than 60 years of age irrespective of gender or patient status. Given the short acquisition time of 4 minutes this sequence could be added to all peripheral MRA exams.