Repeatability and reproducibility of various 4D Flow MRI postprocessing software programs in a multi-software and multi-vendor cross-over comparison study.

BACKGROUND: Different software programs are available for the evaluation of 4D Flow cardiovascular magnetic resonance (CMR). A good agreement of the results between programs is a prerequisite for the acceptance of the method. Therefore, the goal was to compare quantitative results from a cross-over comparison in individuals examined on two scanners of different vendors analyzed with four postprocessing software packages. METHODS: Eight healthy subjects (27 ± 3 years, 3 women) were each examined on two 3T CMR systems (Ingenia, Philips Healthcare; MAGNETOM Skyra, Siemens Healthineers) with a standardized 4D Flow CMR sequence. Six manually placed aortic contours were evaluated with Caas (Pie Medical Imaging, SW-A), cvi42 (Circle Cardiovascular Imaging, SW-B), GTFlow (GyroTools, SW-C), and MevisFlow (Fraunhofer Institute MEVIS, SW-D) to analyze seven clinically used parameters including stroke volume, peak flow, peak velocity, and area as well as typically scientifically used wall shear stress values. Statistical analysis of inter- and intrareader variability, inter-software and inter-scanner comparison included calculation of absolute and relative error (ER), intraclass correlation coefficient (ICC), Bland-Altman analysis, and equivalence testing based on the assumption that inter-software differences needed to be within 80% of the range of intrareader differences. RESULTS: SW-A and SW-C were the only software programs showing agreement for stroke volume (ICC = 0.96; ER = 3 ± 8%), peak flow (ICC: 0.97; ER = -1 ± 7%), and area (ICC = 0.81; ER = 2 ± 22%). Results from SW-A/D and SW-C/D were equivalent only for area and peak flow. Other software pairs did not yield equivalent results for routinely used clinical parameters. Especially peak maximum velocity yielded poor agreement (ICC ≤ 0.4) between all software packages except SW-A/D that showed good agreement (ICC = 0.80). Inter- and intrareader consistency for clinically used parameters was best for SW-A and SW-D (ICC = 0.56-97) and worst for SW-B (ICC = -0.01-0.71). Of note, inter-scanner differences per individual tended to be smaller than inter-software differences. CONCLUSIONS: Of all tested software programs, only SW-A and SW-C can be used equivalently for determination of stroke volume, peak flow, and vessel area. Irrespective of the applied software and scanner, high intra- and interreader variability for all parameters have to be taken into account before introducing 4D Flow CMR in clinical routine. Especially in multicenter clinical trials a single image evaluation software should be applied.

Evaluation of Lower Leg Arteries and Fibular Perforators before Microsurgical Fibular Transfer Using Noncontrast-Enhanced Quiescent-Interval Slice-Selective (QISS) Magnetic Resonance Angiography.

(1) Background: Preoperative imaging of the lower leg arteries is essential for planning fibular grafting. The aim of this study was to evaluate the feasibility and clinical value of non-contrast-enhanced (CE) Quiescent-Interval Slice-Selective (QISS)-magnetic resonance angiography (MRA) for reliably visualizing the anatomy and patency of the lower leg arteries and for preoperatively determining the presence, number, and location of fibular perforators. (2) Methods: The anatomy and stenoses of the lower leg arteries and the presence, number, and location of fibular perforators were determined in fifty patients with oral and maxillofacial tumors. Postoperative outcomes of patients after fibula grafting were correlated with preoperative imaging, demographic, and clinical parameters. (3) Results: A regular three-vessel supply was present in 87% of the 100 legs. QISS-MRA was able to accurately assign the branching pattern in patients with aberrant anatomy. Fibular perforators were found in 87% of legs. More than 94% of the lower leg arteries had no relevant stenoses. Fibular grafting was performed in 50% of patients with a 92% success rate. (4) Conclusions: QISS-MRA has the potential to be used as a preoperative non-CE MRA technique for the diagnosis and detection of anatomic variants of lower leg arteries and their pathologies, as well as for the assessment of fibular perforators.

Clinical Evaluation of Non-Contrast-Enhanced Radial Quiescent-Interval Slice-Selective (QISS) Magnetic Resonance Angiography in Comparison to Contrast-Enhanced Computed Tomography Angiography for the Evaluation of Endoleaks after Abdominal Endovascular Aneurysm Repair.

PURPOSE: Contrast-enhanced (CE) angiographic techniques, such as computed tomographic angiography (CE-CTA), are most commonly used for follow-up imaging after endovascular aneurysm repair. In this study, CE-CTA and non-CE QISS-MRA were compared for the first time for assessing endoleaks and aneurysms at follow-up after abdominal EVAR. METHODS: Our study included 20 patients (17 male, median age 79.8 years) who underwent radial QISS-MRA and CE-CTA after EVAR at their first follow-up examination. Two interventional radiologists evaluated datasets from both techniques in each patient concerning presence of endoleaks, types of endoleaks, aneurysm diameter, and image quality. Interobserver and intermodal agreement were assessed with Cohen's Kappa. RESULTS: Image quality was rated as excellent or good for both modalities by both observers. Ferromagnetic embolization materials cause hyperdense artifacts in CE-CTA causing aneurysm sac diameter measurements to be inaccurate by up to 1 cm. Type 2 endoleaks with low-flow characteristics in CE-CTA were overlooked compared to radial QISS-MRA. Compared to CE-CTA, all endoleaks after abdominal EVAR were detected and classified correctly on QISS-MRA. The interobserver agreement between CE-CTA and QISS-MRA was almost perfect, except for type 2 endoleaks, where agreement was substantial. Intermodal aneurysm diameter correlate "very strongly" for both observers. CONCLUSIONS: Radial QISS-MRA is a contrast agent free technique for diagnosing and monitoring all types of endoleaks and aneurysms in patients after abdominal EVAR. It provides information about specific clinical questions concerning aneurysm diameter and presence and types of endoleaks without radiation exposure and the side effects associated with iodine-based contrast agents.

Non-contrast enhanced magnetic resonance imaging for characterization of Fontan associated liver disease.

OBJECTIVES: To evaluate the ability of non-contrast enhanced magnetic resonance imaging (MRI) techniques to characterize Fontan associated liver disease (FALD) in adolescent and adult Fontan patients. METHODS: Fontan patients (n = 29) and healthy controls (n = 13) underwent an MRI protocol with T1, T2 and Apparent Diffusion Coefficient (ADC) mapping. Routine FALD screening included abdominal ultrasound and laboratory testing. RESULTS: Median follow-up after Fontan operation was 15.1 (IQR 12.0-16.8) years. Distinct differences in tissue characteristics were visualized. T1 and T2 relaxation times were prolonged in Fontan patients, particularly of the right lobe (T1: 745 (IQR 715-784) ms vs. 586 (IQR 555-602) ms, p < 0.001; T2: 63 (IQR 59-64) ms vs. 58 (IQR 56-60) ms, p = 0.002). Left lobe ADC was lower in Fontan patients (1.10 (IQR 1.06-1.18) x 10-3 mm2/s vs. 1.23 (IQR 1.19-1.29) x 10-3 mm2/s, p < 0.001). T2 mapping was able to differentiate between controls and Fontan patients with different FALD severity. Right lobe T2 was higher in patients with moderate or severe in comparison to those with no or mild changes and healthy controls (64 (IQR 61-67) ms vs. 60 (IQR 59-63) ms vs. 58 (IQR 56-60) ms, p = 0.001). CONCLUSIONS: Non-contrast enhanced MRI methods are able to visualize regional differences in liver tissue characteristics. T1 and T2 relaxation times were prolonged in Fontan patients suggestive of fibrosis or congestive hepatopathy, while reduced ADC might reflect impaired microperfusion. These methods have promising clinical potential for detection of liver abnormalities in Fontan patients. The usefulness of T2 mapping to grade FALD severity merits further investigation.

High-resolution, non-contrast-enhanced magnetic resonance angiography of the wrist, hand and digital arteries using optimized implementation of Cartesian quiescent interval slice selective (QISS) at 1.5 T.

PURPOSE: Non-contrast-enhanced (CE) magnetic resonance angiography (MRA) techniques are of considerable interest for diagnosing vascular diseases in the upper extremities owing to the possibility of repeated examinations, sufficient coverage of the measurement volume, and because possible side effects of administering iodine- or gadolinium-based contrast agents and radiation exposure can be avoided. The aim of this study was to investigate the feasibility of an optimized electrocardiogram (ECG) triggered Cartesian quiescent interval slice selective (QISS) technique for MRA of hand arteries. MATERIAL AND METHODS: Both hands of 20 healthy volunteers (HVs) were examined using an optimized QISS-MRA pulse sequence at 1.5 Tesla. The wrist and hand arterial trees were divided into 36 segments. Cross-sectional areas (CSA) of all arterial segments were measured. For the technical evaluation of the pulse sequence, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed and six imaging artifacts were graded. Two experienced observers used an ordinal scoring system to assess the image quality of each arterial segment. Interobserver agreement was determined. RESULTS: The median CSA was 7.3 mm2 in the ulnar and radial artery, 3.2 mm2 in the four common digital arteries, and 1.5 mm2 in five proper digital arteries. The median SNR and CNR of the third common proper arteries were 45.9 and 20.3, respectively. None of the arterial segments were contaminated by venous enhancement. The image quality of arterial segments for both hands was considered as diagnostic in 87.2% of all 1440 segments. An interobserver agreement of 0.67 for both hands was determined for image quality of arterial segments using a five-grade scoring system. Optimized QISS-MRA allows as the first MRA technique the classification of superficial palmar arch (SPA) and deep palmar arch (DPA) variants. 5 new SPA and 6 new DPA variants could be classified using QISS-MRA in comparison with previous studies using CE computed tomography angiography and using fixed cadaver hands. CONCLUSIONS: By using this optimized 2D Cartesian QISS-MRA protocol, contrast agent-free angiography of the wrist and hand arteries provided a high in-plane spatial resolution and an excellent visualization of small digital arteries.

Clinical Value of Noncontrast-Enhanced Radial Quiescent-Interval Slice-Selective (QISS) Magnetic Resonance Angiography for the Diagnosis of Acute Pulmonary Embolism Compared to Contrast-Enhanced Computed Tomography and Cartesian Balanced Steady-State Free Precession.

BACKGROUND: Free-breathing noncontrast-enhanced (non-CE) magnetic resonance angiography (MRA) techniques are of considerable interest for the diagnosis of acute pulmonary embolism (APE), due to the possibility for repeated examinations, avoidance of side effects from iodine-based contrast agents, and the absence of ionizing radiation exposure as compared to CE-computed tomographic angiography (CTA). PURPOSE: To analyze the clinical performance of free-breathing and electrocardiogram (ECG)-gated radial quiescent-interval slice-selective (QISS)-MRA compared to CE-CTA and to Cartesian balanced steady-state free precession (bSSFP)-MRA. STUDY TYPE: Prospective. SUBJECTS: Thirty patients with confirmed APE and 30 healthy volunteers (HVs). FIELD STRENGTH/SEQUENCE: Radial QISS- and bSSFP-MRA at 1.5T. ASSESSMENT: Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were computed to compare the pulmonary imaging quality between MRA methods. The pulmonary arterial tree was divided into 25 branches and an ordinal scoring system was used to assess the image quality of each pulmonary branch. The clinical performance of the two MRA techniques in accurately assessing APE was evaluated with respect to CE-CTA as the clinical reference standard. STATISTICAL TESTS: Wilcoxon signed-rank and Spearman's correlation tests were performed. Sensitivity and specificity of the MRA techniques were determined using CE-CTA as the clinical reference standard. RESULTS: Thrombus-mimicking artifacts appeared more frequently in lobar and peripheral arteries of patients with Cartesian bSSFP than with radial QISS-MRA (pulmonary trunk: 12.2% vs. 14.0%, P = 0.64; lobar arteries: 35.6% vs. 22.0%, P = 0.005, peripheral arteries: 74.4% vs. 49.0%, P < 0.001). The relative increases in SNR and of CNR provided by radial QISS-MRA with respect to Cartesian bSSFP-MRA were 30-35% (P-values of SNR/CNR, HVs: 0.09/0.09, patients: 0.03/0.02). The image quality of pulmonary arterial branches was considered good to excellent in 77.2% of patients with radial QISS-MRA and in 43.2% with Cartesian bSSFP-MRA (P < 0.0001). The clinical performance of radial QISS-MRA was higher than Cartesian bSSFP-MRA for grading embolism, with a total sensitivity of 86.0% vs. 80.6% and a specificity of 93.3% vs. 84.0%, respectively. DATA CONCLUSION: Radial QISS-MRA is a reliable and safe non-CE angiographic technique with promising clinical potential compared to Cartesian bSSFP-MRA and as an alternative technique to CE-CTA for the diagnosis of APE. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 3.

Non-contrast enhanced diagnosis of acute myocarditis based on the 17-segment heart model using 2D-feature tracking magnetic resonance imaging.

PURPOSE: The aim of this study was to investigate the diagnostic value of myocardial deformation analysis based on the 17-segment heart model using non-contrast enhanced (CE) 2D tissue feature tracking (2D-FT) technique. MATERIAL AND METHODS: Seventy patients with suspected myocarditis underwent a cardiovascular magnetic resonance (CMR) examination at 1.5 Tesla. A contrast-agent-free part of this CMR protocol was additionally performed in forty healthy volunteers (HV). Besides standard CMR data sets, 2D-FT derived segmental and global longitudinal, radial, and circumferential deformation parameters were analyzed. The 2D-FT results were compared to the combined findings from CMR imaging and endomyocardial biopsy (EMB). RESULTS: Patients were assigned to three groups depending on their ejection fraction (EF) (<40%, 40-55%, ≥55%). Compared to HV, impaired EF (<55%) was significantly correlated to reduced segmental and global strain and strain rate values. The circumferential deformation analysis was more sensitive to myocardial changes than longitudinal and radial analysis. The segmental strain/strain rate had an accuracy of 84.3%/70.0% for the diagnosis of an acute myocarditis, stated by EMB and CMR in 42 of 70 patients. In patients with preserved EF, acute myocarditis could be ruled out using only segmental strain analysis with a negative predictive value of 87.5%. CONCLUSION: In patients with suspected myocarditis, the deformation analysis based on the 17-segment heart model provides valuable information about functional myocardial inhomogeneity. This quantitative approach could be used in addition to the clinical standard CMR protocol and represents a promising tool in the framework of a prospective automatized multiparametric CMR imaging analysis.

Non-contrast-enhanced magnetic resonance imaging for visualization and quantification of endovascular aortic prosthesis, their endoleaks and aneurysm sacs at 1.5 T.

PURPOSE: After an endovascular aortic aneurysm repair (EVAR), a follow-up at 1, 6 and every 12 months is recommended for remainder of the patient's life. The diagnostic standard methods for diagnosing endoleaks and visualization of aneurysms in EVAR-patients are: invasive digital subtraction angiography (DSA), contrast enhanced (CE) computed tomographic angiography (CE-CTA), and magnetic resonance angiography (CE-MRA). These techniques, however, require the use of iodine- or gadolinium-based contrast agents with rare, but possibly life threatening side effects such as renal impairment, thyrotoxicosis and allergic reactions, nephrogenic systemic fibrosis, and cerebral gadolinium deposition. The aim of this prospective study was to compare a non-contrast-enhanced MRI protocol (consist of four MRI methods) with DSA and CE-CTA for visualization and quantification of endovascular aortic prosthesis, their endoleaks and aneurysms. MATERIAL AND METHODS: Eight patients (mean age 76.8 ±â€¯4.9 years, 63% male), whose thoracic, abdominal, or iliac aneurysms were treated with different endovascular prosthesis and suffered from type I-V endoleaks, were examined on a 1.5 Tesla MR system. Quiescent-interval slice selective MR angiography (QISS-MRA), 4-dimensional (4D)-flow MRI, T1- and T2-mapping, as well as DSA and CE-CTA were used for the visualization and quantification of endoprosthesis, endoleaks, and aneurysms in these patients. RESULTS: QISS-MRA provided good visualization of endoleaks and comparable quantification of aneurysm size with respect to CE-CTA and DSA. The 4D-flow MRI provided additional information about the wall shear stress, which could not be determined using DSA. In contrast to CE-CTA, T1- and T2-mapping provided detailed information about heterogeneous areas within an aneurysm sac. CONCLUSIONS: Compared to DSA and CE-CTA, the proposed MRI methods provide improved anatomical and functional information for various types of endoprostheses and endoleaks. In addition, hemodynamic parameters of the aorta and information on the content of aneurysm sac are provided as well. Within the frame of personalized medicine, the personalized diagnosis enabled by this non-CE MRI protocol is the foundation for a personalized and successful treatment.

Optimization of 3D phase contrast venography for the assessment of the cranio-cervical venous system at 1.5 T.

PURPOSE: The aim of this work was to optimize a three-dimensional (3D) phase-contrast venography (PCV) product MR pulse sequence in order to obtain clinically reliable images with less artifacts for an improved depiction of the cranio-cervical venous vessels. METHODS: Starting from the product sequence, the 3D PCV protocol was optimized in eight steps with respect to the velocity encoding (Venc) direction and value, slice thickness, reduction of susceptibility artifacts and arterial contamination, gradient mode and radio-frequency (RF)-spoiling, B0-Shimming, asymmetric echo technique and RF-pulse type, and flip angle. The product and optimized protocol was used to perform 3D PCV in 12 healthy male volunteers with a median age of 50 years using a state-of-the-art 1.5-T MR system. For evaluation, the cranio-cervical venous system was divided into 15 segments. These segments were evaluated by three radiologists with experience in neuroradiology. An ordinal scoring system was used to access the overall diagnostic quality, arterial contamination, and the quality of visualization. RESULTS: Image quality in the optimized 3D PCV was graded as "excellent" by all readers in 65.3% of the cases (p < 0.0001). The visualization of venous segments was strongly improved: it was considered diagnostic in 81.8% of all cases using the optimized sequence and in 47.6% for the product 3D PCV (p < 0.0001), respectively. The optimized protocol improved the imaging of all venous segments (p < 0.0001). CONCLUSION: The optimized 3D PCV pulse sequence showed superior results compared to the product 3D PCV for the visualization and evaluation of the venous system in all healthy volunteers.

Left atrial active contractile function parameters assessed by cardiac MR are sensitive to myocardial iron.

PURPOSE: To determine the impact of myocardial iron overload on left atrial (LA) volume and function using MR in patients with systemic iron overload. MATERIALS AND METHODS: Thirty-eight patients with systemic iron overload disease and 10 controls underwent 1.5 Tesla MR performing steady state free precession short-axis cine-series of the LA. Three-dimensional-volumetry was assessed to calculate LA volumes and function. Parameters were indexed (i) to body surface area. The myocardial transverse relaxation rate R2* was determined in the ventricular septum using a multi-echo GRE sequence (breathhold; electrocardiography triggered; 12 echoes; echo time = 1.3-25.7 ms). RESULTS: Significantly decreased active atrial emptying fraction (AAEF) (23% [95%-range, 7-34] versus 36% [95%-range, 14-49], P = 0.009), active atrial emptying volume (AAEVi) (5.5 mL/m2 [95%-range, 2-11] versus 11.9 mL/m2 [95%-range, 3-23], P = 0.008), and active peak emptying rate (APERi) (46 mL/s/m2 [95%-range, 29-69] versus 75 mL/s/m2 [95%-range, 45-178], P < 0.001) were found for patients with myocardial iron overload (R2* > 40 s-1 ) compared with patients with normal myocardial iron levels (R2* < 40 s-1 ). Receiver operating characteristics (ROC) analysis revealed higher potential to indicate myocardial iron overload for the AAEF (area under the ROC curve [AUC] = 0.84; P < 0.0001), APERi (AUC = 0.87; P < 0.0001), and AAEVi (AUC = 0.80; P < 0.0001) compared with LA ejection fraction (LAEF) (AUC = 0.68; P = 0.02) with equal sensitivities and specificities of 82% (AAEF), 79% (APERi), 73% (AAEVi), and 57% (LAEF). CONCLUSION: MR parameters of active LA contractile function were associated with myocardial iron overload. This cross-sectional study suggests impaired active LA contractile function to be sensitive to myocardial iron toxicity. LEVEL OF EVIDENCE: 3 J. Magn. Reson. Imaging 2017;45:535-541.

Pancreatic iron and fat assessment by MRI-R2* in patients with iron overload diseases.

BACKGROUND: To determine the pancreatic iron (R2*) and fat content (FC) in comparison to hepatic and cardiac R2* in patients with iron overload disorders like ß-thalassemia major (TM), Diamond-Blackfan anemia (DBA) or hereditary hemochromatosis. METHODS: R2* rates were assessed in the liver, heart and pancreas of 42 patients with TM, 29 subjects with other iron overload diseases, and 10 controls using an ECG-gated breathhold sequence (12 echo time [TE] = 1.3-25.7 ms, readout repetition time [TR] = 244 ms). Pancreatic R2* and FC were assessed from TE dependent region of interest based signal intensities performing water-fat chemical shift relaxometry and were compared with laboratory parameters (glucose, HbA1c, amylase and lipase). RESULTS: A pancreatic iron gradient from tail (R2* = 122 s(-1) ) to head (R2* = 114 s(-1) , P < 10(-4) ) was found. The close association between cardiac and pancreatic R2* was also confirmed in patients with TM and other iron overload diseases (rs = 0.64, P < 10(-4) ). Receiver operator characteristic analysis (area: 0.89, P < 10(-4) ) identified patients with elevated cardiac iron at a pancreatic R2* cut-off level of 131s(-1) (sensitivity = specificity at 81%). Highest pancreatic R2* (211s(-1) ) and FC (36%) were found in the tail region of diabetic patients with TM. CONCLUSION: Pancreatic tail showed highest R2* rates and fat contents, especially in patients with thalassemia. Besides iron accumulation fatty degeneration might be an additional risk factor for the development of diabetes in ß-thalassemia major, but this hypothesis needs further studies in prediabetic patients.

Postmortem 31P magnetic resonance spectroscopy of the skeletal muscle: α-ATP/Pi ratio as a forensic tool?

PURPOSE: Phosphor magnetic resonance spectroscopy ((31)P MRS) is an established method for metabolic examinations of resting and exercising skeletal muscle. So far, there are few MRS investigations of human corpses. The aim of this study was to investigate the temporal postmortem pattern of phosphor metabolites in the adductor magnus muscle and to check the value of MRS as a forensic tool, especially for the determination of the time of death. MATERIAL AND METHODS: Eight corpses, died of natural cause, were examined (5 males, 3 females; age: 73±7 y, weight 65.8±15.9 kg). A control group of 3 subjects (2 males, 1 female, mean age: 51±24 y, range: 24-69 y, mean body weight: 84.0±16.5 kg) was examined at a single time point as well. (31)P MRS was performed on a 1.5 T MRI (TR 700 ms, TE 0.35 ms, averages 256, flip angle 90°). A standard (31)P/(1)H heart/liver coil was employed (receiver coil diameter 12 cm). The (31)P MRS scans were repeated in intervals of 1 h over a period from 4.5 to 24 h postmortem (p.m.). The core temperature was rectally measured throughout the MRI examination. RESULTS: The mean core temperature decreased from 36.0°C to 25.7°C. In vivo and ex vivo spectra showed characteristic differences, especially the PCr metabolite was no longer detectable after 10 h p.m. The α-ATP/Pi ratio decreased with time from 0.445 to 0.032 over 24 h p.m. CONCLUSION: There is a characteristic postmortem time pattern of the phosphor metabolites. Especially the acquired α-ATP/Pi ratio could be described by a significant exponential time course (r(2)=0.92, p<0.001). (31)P MRS might be added to the postmortem imaging methods.

Diffusion-weighted imaging of the healthy pancreas: ADC values are age and gender dependent.

PURPOSE: To investigate the healthy pancreas with diffusion-weighted imaging (DWI) for characterization of age and gender-related differences in apparent diffusion coefficient (ADC) values. MATERIALS AND METHODS: Sixty six volunteers were prospectively enrolled (33 male, 33 female; range 1.4 to 83.7 years of age) and echo-planar DWI of the pancreas was performed. ADC values were measured in the pancreas head, body, and tail using a pixel-by-pixel approach. Effects of age and gender on ADC values were analyzed using a two-factorial multivariate analysis of variance (MANOVA). RESULTS: ADC values correlated inversely with the age of the volunteers. The mean global pancreatic ADC values (× 10(-3) mm(2)/s) in the age groups 0-20 years, 21-40 years, and > 40 years were 1.18 ± 0.19, 1.07 ± 0.13, and 0.99 ± 0.18, respectively. Female individuals had higher mean global ADC values than male (1.13 ± 0.14 versus 1.02 ± 0.18 × 10(-3) mm(2)/s). MANOVA showed significant effects of age (P value 0.022, eta(2) = 0.13) and gender (P value 0.001, eta(2) = 0.28) on ADC values. CONCLUSION: Pancreatic ADC values decline with ageing and show significant gender differences with higher mean values in females. The awareness of baseline values adjusted to age and gender will be important for correct interpretation of individual cases and design of future studies.

Assessment of aortic root dimensions in patients with suspected Marfan syndrome: intraindividual comparison of contrast-enhanced and non-contrast magnetic resonance angiography with echocardiography.

PURPOSE: Our purpose was to evaluate intraindividually the performance of contrast-enhanced magnetic resonance angiography (MRA) and non-contrast MRA for aortic root diameter measurements and to compare the results with routinely performed echocardiography in patients with suspected Marfan syndrome. METHODS AND MATERIALS: Aortic roots were examined prospectively in 51 consecutive patients with suspected Marfan syndrome by using contrast-enhanced MRA and non-contrast MRA at 1.5 T. Two readers independently measured aortic root diameters at the annulus, sinuses of Valsalva and sinutubular junction in both data sets and compared results with echocardiographic data. Intraclass correlation coefficient, Pearson correlation coefficient, Bland-Altman, and two-sided t-test were used to assess agreement between observers and methods. RESULTS: 38 (74.5%) of the 51 patients (25 female, 26 male; mean age 37.1 ± 13.7 years) had Marfan syndrome. Both, contrast-enhanced MRA and non-contrast MRA measurements of the sinuses of Valsalva revealed a strong correlation with echocardiography (r=0.850 and r=0.893, respectively). Intraclass correlation was markedly better for non-enhanced MRA (r=0.904) when compared to contrast-enhanced MRA (r=0.690). Image quality (p<0.001) as well as interobserver agreement (p<0.0042) of measurements of the sinuses of Valsalva was significantly better for non-enhanced MRA than for contrast-enhanced MRA. CONCLUSION: Non-contrast MRA was more reliable and more valid than contrast-enhanced MRA for assessment of aortic root dimensions in patients with suspected Marfan syndrome. Therefore contrast agents can be omitted for establishing the diagnosis of aortic involvement in Marfan syndrome.

Age-related distribution of vertebral bone-marrow diffusivity.

PURPOSE: To determine age-related diffusivity changes of the lumbar bone marrow by measurement of apparent diffusion coefficient (ADC) values. MATERIALS AND METHODS: The local ethics committee approved this study and written informed consent was obtained. The study group comprised 88 individuals including 75 healthy volunteers and 13 patients (48 female, 40 male; mean age 36 years, range 0-84 years). The pediatric cases were recruited from patients. Echo-planar diffusion weighted imaging (DWI) was performed with b-values of 50, 400 and 800 s/mm(2). ADC-values were calculated and measured in the 1st and 2nd vertebral body of the lumbar spine. Correlation between age and ADC-values was analyzed with Spearman's rho test. RESULTS: The ADC values of the vertebral bone marrow of the lumbar spine showed a significant negative correlation with age (rho=-0.398, p=0.001). The mean ADC values (×10(-3)mm(2)/s) in the age groups 0-29 years (mean age 18.0 years, n=42) and 30-88 years (mean age 51.6 years, n=46) were 0.54 ± 0.07 and 0.47 ± 0.08, respectively (p<0.001, T-test). No significant differences were found between children and young adults. CONCLUSION: Bone marrow ADC values of the lumbar spine show a linear decrease with growing age and thereby reflect the gradual changes of cell composition occurring during marrow conversion.

Diffusion-weighted imaging of the healthy pancreas: apparent diffusion coefficient values of the normal head, body, and tail calculated from different sets of b-values.

PURPOSE: To evaluate differences in apparent diffusion coefficient (ADC) values between head, body, and tail regions and the impact of sets of b-values used in diffusion weighted imaging (DWI) of the normal pancreas. MATERIALS AND METHODS: In 51 healthy volunteers echo-planar DWI of the pancreas was prospectively performed with b-values of 50, 400, and 800 s/mm(2) . All four possible combinations of b-values were used to calculate ADC values in a total of 587 regions in the pancreas head, body, and tail regions. Dependency of ADC values on the anatomical regions and on the applied sets of b-values was calculated using multivariate analysis of variance (ANOVA). RESULTS: Mean ADC values differed significantly between the anatomical regions with the lowest values measured in the pancreatic tail (head 1.13 ± 0.20, body 1.05 ± 0.20, and tail 0.94 ± 0.18 × 10(-3) mm(2) /s; P < 0.05). ANOVA showed no dependency of ADC values on the sets of b-values used. CONCLUSION: ADC values differed significantly between the pancreatic head, body, and tail region, with decreasing ADC values toward the tail. Cautious interpretation of DWI results with adjusted, normalized values adapted to the anatomical region seems advisable. The knowledge of such differences may enhance the method's capability to differentiate between different pancreatic pathologies.

Magnetic resonance imaging of prostate cancer: diffusion-weighted imaging in comparison with sextant biopsy.

PURPOSE: To retrospectively evaluate the impact of diffusion-weighted imaging (DWI) on the detection of prostate cancer in comparison with sextant biopsy. MATERIALS AND METHODS: Fifty patients with clinical suspicion of prostate cancer underwent a combined endorectal-body-phased array magnetic resonance imaging examination at a 1.5 T magnetic resonance imaging (Siemens, Erlangen, Germany). The DWI was performed using b values of 50, 400, 800 s/mm. The prostate was divided into sextants, including the apex, the middle aspect, and the base for the left and right sides, separately. Regions of interest were placed in the peripheral zone of each sextant to evaluate the apparent diffusion coefficient (ADC) values. The results of the DWI were compared side by side with the findings of the histological examination of endorectal sonographically guided sextant biopsy. The sensitivity and specificity of ADC for the identification of the tumor tissue were computed for variable discrimination thresholds to evaluate its receiver operating characteristic. An association between ADC and Gleason score was tested for both the whole study group and on an individual basis using the nonparametric Spearman ρ test and the Pearson correlation, respectively. RESULTS: Histopathology identified tumor tissue in 21 (42%) of the 50 patients. The ADC value was 1.65 ± 0.32 mm/s 10 in normal tissue and 0.96 ± 0.24 mm/s 10 in tumor tissue (mean ± 1 SD). The area under the receiver operating characteristic curve was 0.966. Using the discrimination threshold 1.21 mm/s 10, for example, the ADC value provided a sensitivity of 0.92 and a specificity of 0.93. There was a highly significant negative correlation between the ADC value and the Gleason score in the tumor-positive tissue probes (n = 62, ρ = -0.405, P = 0.001) in the whole study group. On the individual patient basis, the Pearson correlation revealed a mean coefficient of r = -0.89 (SD ± 0.12) with a P < 0.001. CONCLUSIONS: Diffusion-weighted imaging of the prostate can be used to differentiate benign from malignant tissue in the peripheral zone. In the present study, ADC values were significantly lower in prostate cancer than in benign tissue.

Self-gating MR imaging of the fetal heart: comparison with real cardiac triggering.

PURPOSE: To investigate the self-gating technique for MR imaging of the fetal heart in a sheep model. MATERIAL AND METHODS: MR images of 6 fetal sheep heart were obtained at 1.5 T. For self-gating MRI of the fetal heart a cine SSFP in short axis, two and four chamber view was used. Self-gated images were compared with real cardiac triggered MR images (pulse-wave triggering). MRI of the fetal heart was performed using both techniques simultaneously. Image quality was assessed and the left ventricular volume and function were measured and compared. RESULTS: Compared with pulse-wave triggering, the self-gating technique produced slightly inferior images with artifacts. Especially the atrial septum could not be so clearly depicted. The contraction of the fetal heart was shown in cine sequences in both techniques. The average blood volumes could be measured with both techniques with no significant difference: at end-systole 3.1 ml (SD±0.2), at end-diastole 4.9 ml (±0.2), with ejection fractions at 38.6%, respectively 39%. CONCLUSION: Both self-gating and pulse-wave triggered cardiac MRI of the fetal heart allowed the evaluation of anatomical structures and functional information. Images obtained by self-gating technique were slightly inferior than the pulse-wave triggered MRI.