Extent of Late Gadolinium Enhancement Predicts Thromboembolic Events in Patients With Hypertrophic Cardiomyopathy.

BACKGROUND: Thromboembolic complications such as ischemic stroke or peripheral arterial thromboembolism are known complications in hypertrophic cardiomyopathy (HCM). We sought to assess the clinical and cardiovascular magnetic resonance (CMR) characteristics of patients with HCM suffering from thromboembolic events and analyzed the predictors of these unfavorable outcomes.Methods and Results:The 115 HCM patients underwent late gadolinium enhanced (LGE) CMR and were included in the study. Follow-up was 5.6±3.6 years. The primary endpoint was the occurrence of thromboembolic events (ischemic stroke or peripheral arterial thromboembolism). It occurred in 17 (14.8%) patients (event group, EG), of whom 64.7% (11) were men. During follow-up, 10 (8.7%) patients died. Patients in the EG showed more comorbidities, such as heart failure (EG 41.2% vs. NEG (non-event group) 14.3%, P<0.01) and atrial fibrillation (AF: EG 70.6% vs. NEG 36.7%, P<0.01). Left atrial end-diastolic volume was significantly higher in the EG (EG 73±24 vs. NEG 50±33 mL/m2, P<0.01). Both the presence and extent of LGE were enhanced in the EG (extent% EG 23±15% vs. NEG 8±9%, P<0.0001). No patient without LGE experienced a thromboembolic event. Multivariate analysis revealed AF and LGE extent as independent predictors. CONCLUSIONS: LGE extent (>14.4%) is an independent predictor for thromboembolic complications in patients with HCM and might therefore be considered as an important risk marker. The risk for thromboembolic events is significantly elevated if accompanied by AF.

Association of training level and outcome of software-based image fusion-guided targeted prostate biopsies.

PURPOSE: The aim of this study was to assess the impact of experience on the outcome of image fusion-guided prostate biopsies performed by urologists working at a high-volume medical center. METHODS: The first 210 consecutive fusion biopsies were analyzed following installation of the software-based biopsy platform Artemis™ (Eigen, USA). The impact of training was measured in terms of changes in prostate cancer detection rates and biopsy duration over time. We sought to identify a threshold of experience for urologists, which predicts higher detection rates of targeted biopsies. The influence of various factors on prostate cancer detection rates was evaluated using bi- and multivariate analysis. RESULTS: Twenty-two urologists (n = 9 senior urologists, n = 13 urological residents) performed targeted biopsies followed by systematic 12-core biopsies. Overall, targeted biopsies yielded a positive result in 39.6% of 260 suspicious MRI lesions. A subgroup analysis of the six urologists who performed more than ten biopsies was then conducted, and their level of experience (i.e., performance of more than eight biopsies) was found to be associated with higher detection rates than those with less experience (49.0% and 23.0%, respectively; p < 0.001) in the targeted biopsies. Experience was likewise a significant and independent predictor of a cancer-positive targeted biopsy (p = 0.002). Experienced senior physicians did not outperform residents in their targeted biopsy results. Further, biopsy duration correlated negatively (r = - 0.5931, p < 0.001) with the total number of biopsies performed for all subgroups during the period of assessment. CONCLUSIONS: Experience is an important predictor of the rate of detection in targeted biopsies using software-based biopsy platforms with semi-robotic assistance. Moreover, the performance of just a few procedures appears sufficient to increase biopsy effectiveness significantly. Lastly, supervision by experts is recommended during the training phase.

Defining the target prior to prostate fusion biopsy: the effect of MRI reporting on cancer detection.

PURPOSE: Definition of targets in multiparametric MRI (mpMRI) prior to MRI/TRUS fusion prostate biopsy either by urologist or radiologist, as a prose report or by illustration is crucial for accurate targeted biopsies (TB). The objective was to analyze the effect of MRI reporting on target definition and cancer detection. METHODS: 202 patients underwent MRI/TRUS fusion biopsy with Artemis™ (Eigen, USA). mpMRI results were submitted in written form to urologists, who marked the targets in the proprietary software. An expert uroradiologist reviewed and marked mpMRI targets blinded to biopsy data. We compared number, localization and volume of targets between the observers and analyzed whether variations impaired TB results by bivariate and logistic regression models. RESULTS: Interobserver variability was moderate regarding number and low regarding localization of targets. Urologists overestimated target volumes significantly compared to radiologists (p = 0.045) and matching target volume between both observers was only 43.9%. Overall cancer detection rate was 69.8 and 52.0% by TB. A higher matching target volume was a significant predictor of cancer in TB (p < 0.001). Logistic regression revealed prostate volume and PI-RADS as independent predictors. Defining targets in incorrect T2w slices in the cranio-caudal axis are one presumable reason for missing cancer in TB. CONCLUSIONS: A high concordance of the target definition between radiologist and urologist is mandatory for accurate TB. Optimized ROI definition is recommended to improve TB results, preferably as contouring in MRI sequences by the radiologist or, if not feasible, by precise MRI reports including specific localization in sequence and slice as well as an illustration. High prostate volume and low PI-RADS score have to be considered as limiting factors for target definition.

Cerebral sodium (23Na) magnetic resonance imaging in patients with migraine - a case-control study.

OBJECTIVE: Evaluation of MRI-derived cerebral 23Na concentrations in patients with migraine in comparison with healthy controls. MATERIALS AND METHODS: In this case-control study, 24 female migraine patients (mean age, 34 ± 11 years) were enrolled after evaluation of standardized questionnaires. Half (n = 12) of the cohort suffered from migraine, the other half was impaired by both migraine and tension-type headaches (TTH). The combined patient cohort was matched to 12 healthy female controls (mean age, 34 ± 11 years). All participants underwent a cerebral 23Na-magnetic resonance imaging examination at 3.0 T, which included a T1w MP-RAGE sequence and a 3D density-adapted, radial gradient echo sequence for 23Na imaging. Circular regions of interests were placed in predetermined anatomic regions: cerebrospinal fluid (CSF), gray and white matter, brain stem, and cerebellum. External 23Na reference phantoms were used to calculate the total 23Na tissue concentrations. Pearson's correlation, Kendall Tau, and Wilcoxon rank sum test were used for statistical analysis. RESULTS: 23Na concentrations of all patients in the CSF were significantly higher than in healthy controls (p < 0.001). The CSF of both the migraine and mixed migraine/TTH group showed significantly increased sodium concentrations compared to the control group (p = 0.007 and p < 0.001). Within the patient cohort, a positive correlation between pain level and TSC in the CSF (r = 0.62) could be observed. CONCLUSION: MRI-derived cerebral 23Na concentrations in the CSF of migraine patients were found to be statistically significantly higher than in healthy controls. KEY POINTS: • Cerebral sodium MRI supports the theory of ionic imbalances and may aid in the challenging pathophysiologic understanding of migraine. • Case-control study shows significantly higher sodium concentrations in cerebrospinal fluid of migraineurs. • Cerebral sodium MRI may become a non-invasive imaging tool for drugs to modulate sodium, and hence migraine, on a molecular level, and influence patient management.

Repeatability and reproducibility of cerebral 23Na imaging in healthy subjects.

BACKGROUND: Initial reports of 23Na magnetic resonance imaging (MRI) date back to the 1970s. However, methodological challenges of the technique hampered its widespread adoption for many years. Recent technical developments have overcome some of these limitations and have led to more optimal conditions for 23Na-MR imaging. In order to serve as a reliable tool for the assessment of clinical stroke or brain tumor patients, we investigated the repeatability and reproducibility of cerebral sodium (23Na) imaging in healthy subjects. METHODS: In this prospective, IRB approved study 12 consecutive healthy volunteers (8 female, age 31 ± 8.3) underwent three cerebral 23Na-MRI examinations at 3.0 T (TimTrio, Siemens Healthineers) distributed between two separate visits with an 8 day interval. For each scan a T1w MP-RAGE sequence for anatomical referencing and a 3D-density-adapted, radial GRE-sequence for 23Na-imaging were acquired using a dual-tuned (23Na/1H) head-coil. On 1 day, these scans were repeated consecutively; on the other day, the scans were performed once. 23Na-sequences were reconstructed according to the MP-RAGE sequence, allowing direct cross-referencing of ROIs. Circular ROIs were placed in predetermined anatomic regions: gray and white matter (GM, WM), head of the caudate nucleus (HCN), pons, and cerebellum. External 23Na-reference phantoms were used to calculate the tissue sodium content. RESULTS: Excellent correlation was found between repeated measurements on the same day (r2 = 0.94), as well as on a different day (r2 = 0.86). No significant differences were found based on laterality other than in the HCN (63.1 vs. 58.7 mmol/kg WW on the right (p = 0.01)). Pronounced inter-individual differences were identified in all anatomic regions. Moderate to good correlation (0.310 to 0.701) was found between the readers. CONCLUSION: Our study has shown that intra-individual 23Na-concentrations in healthy subjects do not significantly differ after repeated scans on the same day and a pre-set time interval. This confirms the repeatability and reproducibility of cerebral 23Na-imaging. However, with manual ROI placement in predetermined anatomic landmarks, fluctuations in 23Na-concentrations can be observed.

The impact of injector-based contrast agent administration in time-resolved MRA.

OBJECTIVES: Time-resolved contrast-enhanced MR angiography (4D-MRA), which allows the simultaneous visualization of the vasculature and blood-flow dynamics, is widely used in clinical routine. In this study, the impact of two different contrast agent injection methods on 4D-MRA was examined in a controlled, standardized setting in an animal model. METHODS: Six anesthetized Goettingen minipigs underwent two identical 4D-MRA examinations at 1.5 T in a single session. The contrast agent (0.1 mmol/kg body weight gadobutrol, followed by 20 ml saline) was injected using either manual injection or an automated injection system. A quantitative comparison of vascular signal enhancement and quantitative renal perfusion analyses were performed. RESULTS: Analysis of signal enhancement revealed higher peak enhancements and shorter time to peak intervals for the automated injection. Significantly different bolus shapes were found: automated injection resulted in a compact first-pass bolus shape clearly separated from the recirculation while manual injection resulted in a disrupted first-pass bolus with two peaks. In the quantitative perfusion analyses, statistically significant differences in plasma flow values were found between the injection methods. CONCLUSIONS: The results of both qualitative and quantitative 4D-MRA depend on the contrast agent injection method, with automated injection providing more defined bolus shapes and more standardized examination protocols. KEY POINTS: • Automated and manual contrast agent injection result in different bolus shapes in 4D-MRA. • Manual injection results in an undefined and interrupted bolus with two peaks. • Automated injection provides more defined bolus shapes. • Automated injection can lead to more standardized examination protocols.

Diffusion kurtosis imaging of the liver at 3 Tesla: in vivo comparison to standard diffusion-weighted imaging.

Background Functional techniques like diffusion-weighted imaging (DWI) are gaining more and more importance in liver magnetic resonance imaging (MRI). Diffusion kurtosis imaging (DKI) is an advanced technique that might help to overcome current limitations of DWI. Purpose To evaluate DKI for the differentiation of hepatic lesions in comparison to conventional DWI at 3 Tesla. Material and Methods Fifty-six consecutive patients were examined using a routine abdominal MR protocol at 3 Tesla which included DWI with b-values of 50, 400, 800, and 1000 s/mm2. Apparent diffusion coefficient maps were calculated applying a standard mono-exponential fit, while a non-Gaussian kurtosis fit was used to obtain DKI maps. ADC as well as Kurtosis-corrected diffusion ( D) values were quantified by region of interest analysis and compared between lesions. Results Sixty-eight hepatic lesions (hepatocellular carcinoma [HCC] [n = 25]; hepatic adenoma [n = 4], cysts [n = 18]; hepatic hemangioma [HH] [n = 18]; and focal nodular hyperplasia [n = 3]) were identified. Differentiation of malignant and benign lesions was possible based on both DWI ADC as well as DKI D-values ( P values were in the range of 0.04 to < 0.0001). Conclusion In vivo abdominal DKI calculated using standard b-values is feasible and enables quantitative differentiation between malignant and benign liver lesions. Assessment of conventional ADC values leads to similar results when using b-values below 1000 s/mm2 for DKI calculation.

Complete and Durable Remission of Human Epidermal Growth Factor Receptor 2-Positive Metastatic Urothelial Carcinoma Following Third-Line Treatment with Trastuzumab and Gemcitabine.

Urothelial carcinoma (UC) is one of the most common cancers and survival rates are low in metastatic disease with currently established first-line platinum-based chemotherapies. Unlike in many other cancers, no clinically established molecular targeted therapies exist for the treatment of this malignancy. Here we present a case of complete tumor remission following third-line treatment with trastuzumab and gemcitabine in a patient with human epidermal growth factor receptor 2 (HER2)-positive UC after progression under cisplatin and vinflunine chemotherapies. This case shows the potential significance of anti-HER2 therapy in selected patients with molecularly characterized UC. Clinical trials so far show inconclusive outcomes of anti-HER2 therapies in UC, indicating further need for both basic research and clinical studies for the identification of resistance factors and improved patient selection.

Tumor size and invasiveness matters for partial nephrectomy: External validation and modification of the arterial based complexity score.

BACKGROUND: Outcome of partial nephrectomy (PN) depends on anatomic features of the renal tumor, which can be assessed by nephrometry scores. The aim was to externally validate and refine the Arterial Based Complexity (ABC) score and to compare it to established systems. METHODS: Tumors of 300 patients undergoing PN were categorized according to the ABC, RENAL, and PADUA score. Size and tumor invasiveness were combined to form the ABCD score. Correlation analysis and multivariate logistic regression was performed to validate and compare the respective scores as predictors of surgical outcome. RESULTS: The ABC score shows significant correlation with ischemia time (IT) (P < 0.01), opening of the collecting system (CS) (P < 0.01), and conversion to nephrectomy (P = 0.01). In the multivariate analysis, the ABC score was predictive for on-clamp excision (P < 0.01) and opening of the CS (P < 0.01) only. The RENAL and ABCD scores were independent predictors for complications (P = 0.02, P = 0.05), IT (P < 0.01, P = 0.03), on clamp excision (P < 0.01, P < 0.01), and opening of the CS (P < 0.01, P < 0.01). CONCLUSIONS: The ABC score correlates well with surgical parameters. Expanding the score by tumor diameter gives the ABCD system. It has similar predictive effectiveness to the well-established RENAL score, but features simplicity by only assessing invasiveness and tumor size.

Galectin-3 Reflects Left Atrial Function being Assessed by Cardiac Magnetic Resonance Imaging.

BACKGROUND: This study aims to evaluate the association between galectin-3 and left atrial function (LAF) in patients undergoing cMRI. METHODS: Patients undergoing cMRI were prospectively enrolled. Right ventricular dysfunction (< 50%) was excluded. Blood samples for biomarker measurements of galectin-3 and NT-proBNP were collected at the time of cMRI examination. RESULTS: A total of 84 patients were included. Median LVEF was 59% (IQR 51 - 64%). Galectin-3 was inversely correlated with overall LAF within a multivariable linear regression model (Beta -0.27; T -2.54; p = 0.01). Galectin-3 increased significantly according to the different stages of impaired LAF (p = 0.003) and was able to discriminate both patients with impaired LAF < 55% (AUC = 0.70, p = 0.002) and LAF < 45% (AUC = 0.69, p = 0.004). In multivariable logistic regression models, galectin-3 was still associated with impaired LAF (LAF < 55%: OR = 2.64, p = 0.07; LAF < 45%: OR = 6.65, p = 0.007). CONCLUSIONS: This study demonstrates that galectin-3 is able to reflect LAF being assessed by cMRI.

Rapid Cartesian versus radial acquisition: comparison of two sequences for hepatobiliary phase MRI at 3 tesla in patients with impaired breath-hold capabilities.

BACKGROUND: Hepatocyte-specific gadolinium based contrast agents (HSCA) provide substantial information for the classification of liver lesions in magnetic resonance imaging (MRI). However, breathing artifacts which reduce image quality and diagnostic confidence of hepatobiliary phase acquisitions are regularly observed in clinical routine. The aim of this study was to evaluate two approaches to reduce breathing artifacts for hepatobiliary phase imaging. METHODS: Twenty minutes after administration of a HSCA (gadoxetic acid), a T1-weighted VIBE sequence with radial k-space sampling (radialVIBE, 180 s acquisition time in free breathing) and a highly accelerated Cartesian VIBE with Dixon fat separation (CD-VIBE, CAIPIRINHA acceleration with r = 2 × 2, breath-hold 8-10 s) were acquired in 35 patients (12 female, 57 ± 13 years), who showed breath-holding difficulties in early phases of the examinations. Image quality (image sharpness, noise, artifacts, homogeneity of fat saturation, bile duct delineation and overall image quality) as well as conspicuity and liver-to-lesion signal intensity (SI) ratios of focal liver lesions were assessed for both radial- and CD-VIBE. RESULTS: Overall image quality was rated good to excellent for both sequences, while CD-VIBE was preferred in most cases. Though radialVIBE received better results regarding image noise and artifacts, both sequences were rated equally regarding bile duct delineation and sharpness. Focal liver lesion (n = 42) conspicuity was rated significantly better and SI-ratios were significantly higher on CD-VIBE (2.45 ± 1.44 vs. 1.61 ± 0.70 in radialVIBE, p = 0.0001). In three patients, CD-VIBE was rated non-diagnostic due to severe breathing artifacts, while radialVIBE was diagnostic in those patients. CONCLUSION: Both highly accelerated Cartesian as well as radial acquisition techniques provide good to excellent image quality in hepatobiliary phase MRI. In comparison, CD-VIBE offered better overall image quality and liver lesion conspicuity. However, radialVIBE was a valuable alternative in patients unable to sustain even short breath-hold intervals. Further studies including lager patient cohorts are desirable to allow a transfer of these results to a general patient population.

Quantitative sodium MRI of kidney.

One of the main tasks of the human kidneys is to maintain the homeostasis of the body's fluid and electrolyte balance by filtration of the plasma and excretion of the end products. Herein, the regulation of extracellular sodium in the kidney is of particular importance. Sodium MRI ((23)Na MRI) allows for the absolute quantification of the tissue sodium concentration (TSC) and thereby provides a direct link between TSC and tissue viability. Renal (23)Na MRI can provide new insights into physiological tissue function and viability thought to differ from the information obtained by standard (1)H MRI. Sodium imaging has the potential to become an independent surrogate biomarker not only for renal imaging, but also for oncology indications. However, this technique is now on the threshold of clinical implementation. Numerous, initial pre-clinical and clinical studies have already outlined the potential of this technique; however, future studies need to be extended to larger patient groups to show the diagnostic outcome. In conclusion, (23)Na MRI is seen as a powerful technique with the option to establish a non-invasive renal biomarker for tissue viability, but is still a long way from real clinical implementation.

MRI morphologic alterations after liver SBRT : Direct dose correlation with intermodal matching.

AIM: CT morphologic and histopathologic alterations have been reported after SBRT. We analyzed the correlation of MRI morphologic alterations with radiation doses to assess the potential for MRI-based dose-effect correlation in healthy liver tissue. PATIENTS AND METHODS: MRI data of 24 patients with liver metastases 7±3 weeks after image-guided SBRT in deep-inspiration breath-hold were retrospectively analyzed. MRI images were intermodally matched to the planning CT and corresponding dose distribution. Absolute doses were converted to EQD2,α/ß =x with α/ß values of 2, 3 for healthy liver tissue, 8 Gy for modelled predamaged liver tissue and 10 Gy for tumor tissue. RESULTS: A central nonenhancing area was observed within the isodose lines of nominally 48.2 ± 15.2 Gy, EQD2Gy/α/ß =10 92.5 ± 27.7 Gy. Contrast-enhancement around the central nonenhancing area was observed within the isodose lines of nominally 46.9 ± 15.3 Gy, EQD2Gy/α/ß =10 90.5 ± 28.3 Gy. Outside the high-dose volume, in the beam path, characteristic sharply defined, nonblurred MRI morphologic alterations were observed that corresponded with the following isodose lines: T1-intensity changes occurred at isodose lines of nominally 21.9 ± 6.7 Gy (EQD2,α/ß =2 42.5 ± 8.7 Gy, EQD2,α/ß =3 38.5 ± 7.6 Gy, EQD2,α/ß =8 30.2 ±6.3 Gy). T2-hyper/hypointensity was observed within isodose lines of nominally 22.4 ± 6.6 Gy (EQD2,α/ß=2 42.7 ± 8.1 Gy, EQD2,α/ß=3 38.7 ± 7 Gy; EQD2,α/ß=8 30.5 ± 5.9 Gy). CONCLUSIONS: Using deformable matching, direct spatial/dosimetric correlation of SBRT-induced changes in liver tissue was possible. In the PTV high-dose region, a central nonenhancing area and peripheral contrast medium accumulation was observed. Beam path doses of 38-42 Gy (EQD2,α/ß =2-3) induce characteristic MRI morphologic alterations.

Myocardial T1-mapping at 3T using saturation-recovery: reference values, precision and comparison with MOLLI.

BACKGROUND: Myocardial T1-mapping recently emerged as a promising quantitative method for non-invasive tissue characterization in numerous cardiomyopathies. Commonly performed with an inversion-recovery (IR) magnetization preparation at 1.5T, the application at 3T has gained due to increased quantification precision. Alternatively, saturation-recovery (SR) T1-mapping has recently been introduced at 1.5T for improved accuracy. Thus, the purpose of this study is to investigate the robustness and precision of SR T1-mapping at 3T and to establish accurate reference values for native T1-times and extracellular volume fraction (ECV) of healthy myocardium. METHODS: Balanced Steady-State Free-Precession (bSSFP) Saturation-Pulse Prepared Heart-rate independent Inversion-REcovery (SAPPHIRE) and Saturation-recovery Single-SHot Acquisition (SASHA) T1-mapping were compared with the Modified Look-Locker inversion recovery (MOLLI) sequence at 3T. Accuracy and precision were studied in phantom. Native and post-contrast T1-times and regional ECV were determined in 20 healthy subjects (10 men, 27 ± 5 years). Subjective image quality, susceptibility artifact rating, in-vivo precision and reproducibility were analyzed. RESULTS: SR T1-mapping showed <4 % deviation from the spin-echo reference in phantom in the range of T1 = 100-2300 ms. The average quality and artifact scores of the T1-mapping methods were: MOLLI:3.4/3.6, SAPPHIRE:3.1/3.4, SASHA:2.9/3.2; (1: poor - 4: excellent/1: strong - 4: none). SAPPHIRE and SASHA yielded significantly higher T1-times (SAPPHIRE: 1578 ± 42 ms, SASHA: 1523 ± 46 ms), in-vivo T1-time variation (SAPPHIRE: 60.1 ± 8.7 ms, SASHA: 70.0 ± 9.3 ms) and lower ECV-values (SAPPHIRE: 0.20 ± 0.02, SASHA: 0.21 ± 0.03) compared with MOLLI (T1: 1181 ± 47 ms, ECV: 0.26 ± 0.03, Precision: 53.7 ± 8.1 ms). No significant difference was found in the inter-subject variability of T1-times or ECV-values (T1: p = 0.90, ECV: p = 0.78), the observer agreement (inter: p > 0.19; intra: p > 0.09) or consistency (inter: p > 0.07; intra: p > 0.17) between the three methods. CONCLUSIONS: Saturation-recovery T1-mapping at 3T yields higher accuracy, comparable inter-subject, inter- and intra-observer variability and less than 30 % precision-loss compared to MOLLI.

Right Ventricular and Right Atrial Involvement Can Predict Atrial Fibrillation in Patients with Hypertrophic Cardiomyopathy?

OBJECTIVES AND BACKGROUND: Atrial fibrillation (AF) is associated with clinical deterioration, stroke and disability in patients with hypertrophic cardiomyopathy (HCM). Therefore, the objective of this study was to evaluated cardiac magnetic resonance (CMR)-derived determinants for the occurrence of AF in patients with HCM. METHODS: 98 Patients with HCM and 30 healthy controls underwent CMR and were followed-up for 6 ± 3 years. RESULTS: 19 (19.4%) patients presented with AF at initial diagnosis, 19 (19.4%) developed AF during follow-up and 60 (61.2%) remained in sinus rhythm (SR). Compared to healthy controls, patients with HCM who remained in SR presented with significantly increased left ventricular mass, an elevated left ventricular remodeling index, enlarged left atrial volumes and reduced septal mitral annular plane systolic excursion (MAPSE) compared to healthy controls. Whereas HCM patients who presented with AF at initial diagnosis and those who developed AF during follow-up additionally presented with reduced tricuspid annular plane systolic excursion (TAPSE) and right atrial (RA) dilatation. Receiver-operator curve analysis indicated good predictive performance of TAPSE, RA diameter and septal MAPSE (AUC 0.73, 0.69 and 0.71, respectively) to detect patients at risk of developing AF. CONCLUSION: Reduced MAPSE measurements and enlarged LA volumes seems to be a common feature in patients with HCM, whereas reduced TAPSE and RA dilatation only seem to be altered in patients with history of AF and those developing AF. Therefore, they could serve as easy determinable markers of AF in patients with HCM.

Dose-dependent changes in renal (1)H-/(23)Na MRI after adjuvant radiochemotherapy for gastric cancer.

PURPOSE: Combined radiochemotherapy (RCT) for gastric cancer with three-dimensional conformal radiotherapy (3D-CRT) results in ablative doses to the upper left kidney, while image-guided intensity-modulated radiotherapy (IG-IMRT) allows kidney sparing despite improved target coverage. Renal function in long-term gastric cancer survivors was evaluated with 3T functional magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) and (23)Na imaging. PATIENTS AND METHODS: Five healthy volunteers and 13 patients after radiotherapy were included: 11×IG-IMRT; 1×3D-CRT; 1× "positive control" with stereotactic body radiotherapy (SBRT) of a metastasis between the spleen/left kidney. Radiation doses were documented for the upper/middle/lower kidney subvolumes. Late toxicity was evaluated based on CTC criteria, questionnaire, and creatinine values. Morphological sequences, DWI images, and (23)Na images were acquired using a (1)H/(23)Na-tuned body-coil before/after intravenous water load (WL). Statistics for [(23)Na] (concentration) and apparent diffusion coefficient (ADC) values were calculated for upper/middle/lower renal subvolumes. Corticomedullary [(23)Na] gradients and [(23)Na] differences after WL were determined. RESULTS: No major morphological alteration was detected in any patient. Minor scars were observed in the cranial subvolume of the left kidney of the 3D-CRT and the whole kidney of the control SBRT patient. All participants presented a corticomedullary [(23)Na] gradient. After WL, a significant physiological [(23)Na] gradient decrease (p < 0.001) was observed in all HV and IG-IMRT patients. In the cranial left kidney of the 3D-CRT patient and the positive control SBRT patient, the decrease was nonsignificant (p = 0.01, p = 0.02). ADC values were altered nonsignificantly in all renal subvolumes (all participants). Renal subvolumes with doses ≥ 35 Gy showed a reduced change of the [(23)Na] gradient after WL (p = 0.043). No participants showed clinical renal impairment. CONCLUSIONS: Functional parameters of renal (23)Na MRI after gastric IG-IMRT are identical to those of healthy volunteers, in contrast to renal subvolumes after ablative doses in the control and 3D-CRT patient. While kidney doses to the cortex below 20-25 Gy in fractional doses of ~ 1 Gy in IG-IMRT (combined with intensified chemotherapy) do not seem to cause significant MRI morphological or functional alterations, doses of > 35 Gy in 1.5-2 Gy fractions clearly result in impairment.

Nonenhanced ECG-gated quiescent-interval single shot MRA: image quality and stenosis assessment at 3 tesla compared with contrast-enhanced MRA and digital subtraction angiography.

PURPOSE: To evaluate the diagnostic accuracy of a nonenhanced electrocardiograph-gated quiescent-interval single shot MR-angiography (QISS-MRA) at 3 Tesla with contrast-enhanced MRA (CE-MRA) and digital subtraction angiography (DSA) serving as reference standard. MATERIALS AND METHODS: Following institutional review board approval, 16 consecutive patients with peripheral arterial disease underwent a combined peripheral MRA protocol consisting of a large field-of-view QISS-MRA, continuous table movement MRA, and an additional time-resolved MRA of the calves. DSA correlation was available in eight patients. Image quality and degree of stenosis was assessed. Sensitivity and specificity of QISS-MRA was evaluated with CE-MRA and DSA serving as the standards of reference and compared using the Fisher exact test. RESULTS: With the exception of the calf station, image quality with QISS-MRA was rated statistically significantly less than that of CE-MRA (P < 0.05, P = 0.17, and P = 0.6, respectively). A greater percentage of segments were not accessible with QISS-MRA (19.5-20.1%) in comparison to CE-MRA (10.9%). Relative to DSA, sensitivity for QISS-MRA was high (100% versus 91.2% for CE-MRA, P = 0.24) in the evaluated segments; however, specificity (76.5%) was substantially less than that of CE-MRA (94.6%, P = 0.003). CONCLUSION: Overall image quality and specificity of QISS-MRA at 3T are diminished relative to CE-MRA. However, when image quality is adequate, QISS-MRA has high sensitivity and, thus, has potential use in patients with contraindications to gadolinium.

Assessment of acute intestinal graft versus host disease by abdominal magnetic resonance imaging at 3 Tesla.

OBJECTIVES: After allogeneic stem cell transplantation (SCT), a reliable diagnosis of acute graft versus host disease (aGvHD) is essential for an early and successful treatment. It is the aim of this analysis to assess intestinal aGvHD by magnetic resonance imaging (MRI). METHODS: Prior to allogeneic SCT, 64 consecutive patients underwent abdominal MRI examination on a 3 T MR system, including axial and coronal T2w sequences and a three-dimensional dynamic T1w, contrast enhanced sequence. After SCT, 20 patients with suspected aGvHD received a second MRI as well as an endoscopic examination. RESULTS: Nine patients suffered from histologically proven intestinal aGvHD. In eleven patients intestinal aGvHD was excluded. In all aGvHD patients typical MRI findings with long-segment bowel wall thickening--always involving the terminal ileum--with profound submucosal oedema, were detected. The bowel wall was significantly thickened in patients with intestinal aGvHD. Bowel contrast enhancement spared the submucosa while demonstrating strong mucosal hyperemia. CONCLUSIONS: In intestinal aGvHD, a characteristic MR-appearance can be detected. This MRI pattern might facilitate an early and non-invasive diagnosis of intestinal aGvHD. MRI might thus be used as a sensitive tool to rule out or support the clinical diagnosis of aGvHD. KEY POINTS: • Acute intestinal graft versus host disease (aGvHD) can be assessed by MRI. • The aGvHD of the bowel demonstrates a characteristic MR imaging pattern. • Bowel wall shows extensive long-segment wall thickening with profound submucosal oedema. • Terminal ileum seems invariably affected; other bowel segments show variable involvement. • Colonoscopy in suspected aGvHD should include inspection of terminal ileum.

Intraindividual Comparison of Compressed Sensing-Accelerated Cartesian and Radial Arterial Phase Imaging of the Liver in an Experimental Tumor Model.

OBJECTIVES: The aim of this study was to intraindividually compare the performance of 2 compressed sensing (CS)-accelerated magnetic resonance imaging (MRI) sequences, 1 featuring Cartesian (compressed sensing volumetric interpolated breath-hold examination [CS-VIBE]) and the other radial (golden-angle radial sparse parallel [GRASP]) k-space sampling in continuous dynamic imaging during hepatic vascular phases, using extracellular and hepatocyte-specific contrast agents. MATERIALS AND METHODS: Seven New Zealand white rabbits, with induced VX2 liver tumors (median number of lesions, 2 ± 0.83; range, 1-3), received 2 continuously acquired T1-weighted prototype CS-accelerated MRI sequences (CS-VIBE and GRASP) with high spatial (0.8 × 0.8 × 1.5 mm) and temporal resolution (3.5 seconds) in randomized order on 2 separate days using a 1.5-T scanner. In all animals, imaging was performed using first gadobutrol at a dose of 0.1 mmol/kg and, then 45 minutes later, gadoxetic acid at a dose of 0.025 mmol/kg.The following qualitative parameters were assessed using 3- and 5-point Likert scales (3 and 5 being the highest scores respectively): image quality (IQ), arterial and venous vessel delineation, tumor enhancement, motion artifacts, and sequence-specific artifacts. Furthermore, the following quantitative parameters were obtained: relative peak signal enhancement, time to peak, mean transit time, and plasma flow ratios. Paired sampled t tests and Wilcoxon signed rank tests were used for intraindividual comparison. Image analysis was performed by 2 radiologists. RESULTS: Six of 7 animals underwent the full imaging protocol and obtained data were analyzed statistically. Overall IQ was rated moderate to excellent, not differing significantly between the 2 sequences.Gadobutrol-enhanced CS-VIBE examinations revealed the highest mean Likert scale values in terms of vessel delineation and tumor enhancement (arterial 4.4 [4-5], venous 4.3 [3-5], and tumor 2.9 [2-3]). Significantly, more sequence-specific artifacts were seen in GRASP examinations (P = 0.008-0.031). However, these artifacts did not impair IQ. Excellent Likert scale ratings were found for motion artifacts in both sequences. In both sequences, a maximum of 4 hepatic arterial dominant phases were obtained. Regarding the relative peak signal enhancement, CS-VIBE and GRASP showed similar results. The relative peak signal enhancement values did not differ significantly between the 2 sequences in the aorta, the hepatic artery, or the inferior vena cava (P = 0.063-0.536). However, significantly higher values were noted for CS-VIBE in gadoxetic acid-enhanced examinations in the portal vein (P = 0.031) and regarding the tumor enhancement (P = 0.005). Time to peak and mean transit time or plasma flow ratios did not differ significantly between the sequences. CONCLUSIONS: Both CS-VIBE and GRASP provide excellent results in dynamic liver MRI using extracellular and hepatocyte-specific contrast agents, in terms of IQ, peak signal intensity, and presence of artifacts.