MRI of the ankle joint in healthy non-athletes and in marathon runners: image quality issues at 7.0 T compared to 1.5 T.

OBJECTIVE: To present imaging characteristics of the ankle at 7.0 T and to investigate the appearance and image quality of presumed pathologies of ankles without physical strain as well as of ankles after a marathon run in comparison to 1.5 T. MATERIALS AND METHODS: Appearance of presumed pathologic findings and image quality of TSE (PD, T2, and STIR) and GRE sequences (MEDIC, DESS, and/or CISS) at 7.0 T and 1.5 T MRI were compared by two senior radiologists in consensus in two healthy controls without strain and in six marathon runners after a full-length marathon (eight males, mean age 49.1 years). RESULTS: Overall, 7.0 T MRI allowed for higher resolution images for most of the sequences while requiring comparable acquisition times and achieving high contrast images mainly in gradient echo sequences. Bursal or presumed peritendineal fluid and/or edematous tissue, which were found in seven of eight subjects, could be best appreciated with 7.0 T MEDIC. Other findings with sharper delineation at 7.0 T included cartilage defects (best: CISS), osseous avulsions, and osteophytes (best: DESS). Nevertheless, 1.5 T STIR imaging enabled assessment of a tibiotalar bone edema-like lesion in two runners, which was barely visible at 7.0 T using STIR, but not with any other sequence at 7.0 T including MEDIC (with frequency selective fat suppression). 7.0 T showed larger image quality variations with challenges especially in the TSE sequences. CONCLUSION: Our initial results of ultra-high-field ankle joint imaging demonstrate the improved depiction of ankle anatomy, fluid depositions, and cartilage defects. However imaging of edema-like bone lesions remains challenging at ultra-high magnetic field strength, and TSE coverage in particular is limited by the specific absorption rate.

Transarterial hepatic chemoperfusion of uveal melanoma metastases: survival and response to treatment.

PURPOSE: To assess the survival of patients with hepatic uveal melanoma metastases undergoing sequential transarterial hepatic chemoperfusion. MATERIALS AND METHODS: 61 patients (mean age, 60.3 ± 13.8 y) underwent a total of 249 hepatic chemoperfusion procedures (mean: 4 chemoperfusion procedures; range, 1-7 chemoperfusion procedures; standard deviation, 2.3 chemoperfusion procedures). All patients started with melphalan. In the case of progressive disease, melphalan was replaced by a different chemoperfusion agent. 38 patients were treated with melphalan only, 23 patients were treated with a combination of melphalan and other drugs. The median overall survival time was calculated for the overall population and several sub-groups. Differences in the survival rate between the sub-groups were assessed for statistical significance. The complication rate was assessed. RESULTS: The median overall survival of the entire population was 10 months. The patients in the subgroups with a maximum number of 9 hepatic metastases as well as the patients in the subgroup without extrahepatic metastases at the beginning of therapy survived significantly longer than patients with more than 9 metastases/extrahepatic metastases (p = 0.019, p = 0.008). One patient (0.4%) died from liver failure after initial infusion of melphalan. CONCLUSION: Intraarterial sequential hepatic chemoperfusion offers a minimally invasive treatment in patients with hepatic uveal melanoma metastases with good survival times and an acceptable major complication rate.

Recovery of ophthalmoplegia after endovascular treatment of intracranial aneurysms.

BACKGROUND AND PURPOSE: Recovery of aneurysm induced CNP after endosaccular coiling has been reported in the literature. The aim of this study was to assess in detail the parameters that affect the outcome after endovascular treatment of ophthalmoplegic aneurysms due CNP. MATERIALS AND METHODS: Between November 1999 and March 2008, 30 consecutive patients (8 men, 22 women; mean age, 54.9 years) presenting with CNP underwent endosaccular coiling with or without additional use of stents in the parent artery. Subarachnoid hemorrhage was present in 10 patients, whereas 20 patients had unruptured aneurysms. The mean size of the aneurysms was 10 mm. Initial CNP was complete in 11 patients and partial in 19. Mean follow-up after coiling was 19 months. RESULTS: The mean interval between the onset of CNP and aneurysm embolization was 48 days. Fifteen patients (50%) had complete recovery of oculomotor function, 12 had incomplete recovery (40%), and 3 (10%) remained unchanged after treatment. In 4 aneurysms (13.3%), 1 additional embolization was performed, whereas in 4 other aneurysms, 2 additional embolization procedures were necessary. Procedure-related permanent morbidity occurred in 2 patients (6.6%). CONCLUSIONS: Endosaccular coiling is an effective and safe method for the treatment of ophthalmoplegic aneurysms. Age, neck size, and time of treatment do not seem to constitute prognostic factors with respect to CNP recovery, though patients with small aneurysms, unruptured status, and/or location in the posterior circulation showed a tendency for better outcome. The degree of initial CNP was the only statistically significant prognostic factor concerning the final outcome, resulting in better recovery, in case of incomplete initial CNP.

Imaging of brain metastases of bronchial carcinomas with 7 T MRI - initial results.

PURPOSE: To compare the depiction of brain metastases of bronchial carcinomas on susceptibility-weighted and contrast-enhanced images with 7 T and at 1.5 T MRI. MATERIALS AND METHODS: Twelve patients with brain metastases of bronchial carcinomas underwent 7 T and 1.5 T MRI. Minimum intensity projections (MinIP) of a 1.5 T SWI sequence (voxel size = 0.9 x 0.9 x 2.0 mm(3)) were compared to 7 T SWI MinIPs (voxel size = 0.4 x 0.4 x 1.5 mm(3)). A T 1-w 3D MPRAGE at 1.5 T (voxel size = 1 x 1 x 1 mm(3) after double-dose (DD) gadoterate meglumine, Gd-DOTA) was compared to a 7 T MPRAGE sequence (voxel size = 0.7 x 0.7 x x 0.7 mm(3), single dose (SD) Gd-DOTA) in all patients, and to DD Gd-DOTA in 6 patients after a 10 minute delay. The number of intracranial microhemorrhages in SWI MinIPs and the number of contrast-enhancing metastases in MPRAGE images were compared in each patient grouped into three size ranges (< or = 2 mm, > 2 mm and < 6 mm, > or = 6 mm) by two radiologists in consensus. RESULTS: In all 12 patients the 7 T SWI with spatially higher resolution allowed the identification of 87 versus 67 cerebral microhemorrhages at 1.5 T. 7 T T 1-w images after SD Gd-DOTA depicted 198 brain metastases versus 238 at 1.5 T after DD Gd-DOTA. After doubling the contrast dose in six patients, 4 additional brain metastases were identified at 7 T. CONCLUSION: Our preliminary results indicate that despite the higher spatial resolution the detection of brain metastases on 7 T MPRAGE images is almost equal to 1.5 T MPRAGE images. The 7 T SWI sequence with spatially higher resolution allowed the detection of 20 % more microhemorrhages in brain metastases compared to the 1.5 T SWI sequence.

Suitability of semi-automated tumor response assessment of liver metastases using a dedicated software package.

PURPOSE: To evaluate the suitability of semi-automated compared to manual tumor response assessment (TRA) of liver metastases. MATERIALS AND METHODS: In total, 32 patients with colorectal cancer and liver metastases were followed by an average of 2.8 contrast-enhanced CT scans. Two observers (O 1, O 2) measured the longest diameter (LD) of 269 liver metastases manually and semi-automatically using software installed as thin-client on a PACS workstation (LMS-Liver, MEDIAN Technologies). LD and TRA ("progressive", "stable", "partial remission") were performed according to RECIST (Response Evaluation Criteria in Solid Tumors) and analyzed for between-method, interobserver and intraobserver variability. The time needed for evaluation was compared for both methods. RESULTS: All measurements correlated excellently (r>or=0.96). Intraobserver (semi-automated), interobserver (manual) and between-method differences (by O 1) in LD of 1.4+/-2.6 mm, 1.9+/-1.9 mm and 2.1+/-2.0 mm, respectively, were not significant. Interobserver (semi-automated) and between-method (by O 2) differences in LD of 3.0+/-3.0 mm and 2.6+/-2.0 mm, respectively, reflected a significant variability (p<0.01). The interobserver agreement in manual and semi-automated TRA was 91.4 %. The intraobserver agreement in semi-automated TRA was 84.5%. Between both methods a TRA agreement of 86.2% was obtained. Semi-automated evaluation (2.7 min) took slightly more time than manual evaluation (2.3 min). CONCLUSION: Semi-automated and manual evaluation of liver metastases yield comparable results in response assessments and require comparable effort.

Concomitant atherosclerotic disease detected by whole-body MR angiography in relation to coronary artery calcification in patients with coronary artery disease.

PURPOSE: Patients with coronary artery disease (CAD) show a high prevalence for concomitant atherosclerotic peripheral arterial disease (PAD). On the other hand, PAD seems to be an additional risk factor for cardiac events. We evaluated the correlation between arterial pathologies as found in whole-body MR angiography and coronary artery calcification (CAC) detected by electron beam computed tomography (EBCT) and multislice CT (MSCT). MATERIALS AND METHODS: Two hundred and twenty-eight patients (161 men; 67 women) with suspicion for CAD/known CAD underwent whole-body contrast-enhanced MR angiography (wb-ce-MRA) and EBCT/MSCT. An atherosclerosis index was calculated for each patient Index = (40)Sigma(n=1) w(i) with w(i) being the grading of the stenosis of the i (ten) of 40 arteria segments (grade: 0 - no plaque; 1 - plaque - < or = 50 % stenosis; 2 - > 50 % stenosis - < or = 90 % stenosis; 3 - > 90 % stenosis - < 100 % stenosis; 4 - occlusion). Correlations between CAC and atherosclerosis index were performed. RESULTS: Wb-ce MRA and CAC correlate only moderately in this population. An atherosclerosis index 8 renders a positive predictive value for a CAC 100 of 63.3 %. CONCLUSION: An atherosclerosis index as defined in this study does not fully correlate with the extent of CAD as revealed by catheter angiography or EBCT/MSCT, but it might theoretically mirror the increased risk by PAD. It thus might be a promising complementary parameter for the prediction of cardiac events. Future studies need to show its possible additional predictive impact.

[Effects of MRI on the electrophysiology of the motor cortex: a TMS study]. / Auswirkungen der Magnetresonanztomografie auf die Elektrophysiologie des motorischen Kortex: eine Studie mit transkranieller Magnetstimulation.

PURPOSE: The increasing spread of high-field and ultra-high-field MRI scanners encouraged a new discussion on safety aspects of MRI examinations. Earlier studies report altered acoustically evoked potentials. This finding was not able to be confirmed in later studies. In the present study transcranial magnetic stimulation (TMS) was used to evaluate whether motor cortical excitability may be altered following MRI examination even at field strength of 1.5 T. MATERIALS AND METHODS: In 12 right-handed male volunteers individual thresholds for motor responses and then the length of the post-excitatory inhibition (silent period) were determined. Subsequently the volunteers were examined in the MRI scanner (Siemens Avanto, 1.5 T) for 63 minutes using gradient and spin echo sequences. MRI examination was immediately followed by another TMS session and a third 10 minutes later. As a control condition, the 12 subjects spent one hour in the scanner without examination and one hour on a couch without the presence of a scanner. RESULTS: After MRI examination, the silent period was significantly lengthened in all 12 subjects and then tended to the initial value after 10 min. Motor thresholds were significantly elevated and then normalized after 10 minutes. No significant effects were found in the control conditions. CONCLUSION: MRI examination leads to a transient effect on motor cortical excitability indicated by elongation of the post-excitatory inhibition and to an increase in motor thresholds in some subjects. These effects do not seem to be associated with a static magnetic field.

Evaluation of intracranial aneurysms with 7 T versus 1.5 T time-of-flight MR angiography - initial experience.

PURPOSE: The purpose of this study was to compare the depiction of intracranial aneurysms by 3D time-of-flight (TOF) magnetic resonance angiography (MRA) at 7 Tesla (T) with the clinical standard TOF MRA at 1.5 T and with digital subtraction angiography (DSA). MATERIALS AND METHODS: 7 T and 1.5 T TOF MRA images optimized for both field strengths were compared in ten patients with an unruptured intracranial aneurysm. Two blinded neuroradiologists independently rated the image quality of the dome, the neck, and the vessel of origin of all aneurysms in MRA source and maximum intensity projection (MIP) images. DSA was obtained in all subjects and served as reference standard. The mean values of image quality were compared by Wilcoxon signed rank test. In all patients the number and location of the aneurysms was confirmed by DSA. RESULTS: Both readers identified twelve aneurysms in ten patients in 7 T, 1.5 T TOF MRA and DSA. The image quality of the aneurysm dome was rated higher in 8 of 12 aneurysms and the image quality of the aneurysm neck was superior in 9 of 12 aneurysms at 7 T TOF MRA compared to 1.5 T TOF MRA. The depiction of the parent vessel was graded almost equally by both readers. CONCLUSION: Our initial results indicate that image quality of intracranial aneurysms may benefit from the increased spatial resolution of 7 T TOF MRA compared with 1.5 T TOF MRA. Tailored scan protocols and optimized radiofrequency head coils are needed to further improve the image quality of 7 T TOF MRA.

The human hippocampus at 7 T--in vivo MRI.

The human hippocampus plays a central role in various neuropsychiatric disorders, such as temporal lobe epilepsy (TLE), Alzheimer's dementia, mild cognitive impairment, and schizophrenia. Its volume, morphology, inner structure, and function are of scientific and clinical interest. Magnetic resonance (MR) imaging is a widely employed tool in neuroradiological workup regarding changes in brain anatomy, (sub-) volumes, and cerebral function including the hippocampus. Gain in intrinsic MR signal provided by higher field strength scanners and concomitant improvements in spatial resolution seem highly valuable. An examination protocol permitting complete, high-resolution imaging of the human hippocampus at 7 T was implemented. Coronal proton density, T2, T2*, and fluid-attenuated inversion recovery contrasts were acquired as well as an isotropic 3D magnetization-prepared rapid acquisition gradient-echo (500 microm isotropic voxel dimension, noninterpolated). Observance of energy deposition restrictions within acceptable scan times remained challenging in the acquisition of thin, spin-echo-based sections. At the higher resolution enabled by 7 T, demarcation of the hippocampus and some internal features including gray/white matter differentiation and depiction of the hippocampal mantle becomes much more viable when compared with 1.5 T; thus, in the future, this imaging technology might help in the diagnosis of subtle hippocampal changes.

Detection of myocardial fibrosis in systemic sclerosis by contrast-enhanced magnetic resonance imaging.

PURPOSE: Our study aimed to assess the prevalence and pattern of late gadolinium enhancement (LGE) as an in vivo correlate of myocardial fibrosis in cardiac asymptomatic patients with systemic sclerosis (SSc). MATERIALS AND METHODS: Cardiac magnetic resonance imaging was successfully performed in 34 patients (30 female, 4 male, mean age of 54 +/- 14 years) with proven SSc and in controls with matching age, sex and cardiovascular risk factors. All examinations were performed on a 1.5 T MR system (Avanto, Siemens, Germany). 2D inversion recovery spoiled gradient echo images (TR 8.0 msec, TE 4.0 msec, TI 180 - 240 msec, FA 20 degrees, slice thickness 8 mm, in-plane resolution 1.2 x 1.2 mm (2)) were acquired 10 to 15 min after injection of 0.2 mmol Gd-DTPA per kg body weight to detect myocardial LGE. RESULTS: Poorly defined, patchy as well as well-defined focal areas of LGE were detected predominantly in the mid-myocardial layer of the basal left ventricular segments in 5 of 34 (15 %) SSc patients. A focal area of LGE was observed within the apical septum in one control (3 %, p > 0.05). LGE was observed in a total of 15 segments of the SSc patients and in 1 segment of the controls (p < 0.005). CONCLUSION: Our results revealed a significantly higher number of LGE positive segments in patients with SSc compared to matched controls, and demonstrate the ability of contrast-enhanced MRI to detect myocardial fibrosis, the hallmark of scleroderma heart disease, in-vivo.

[MR colography: technique, indications, and findings]. / MR-Kolonographie: Technik, Indikationen und Befunde.

Magnetic resonance imaging (MRI) has evolved as a powerful tool that has been applied more and more in recent years for the assessment of gastrointestinal structures, owing to its unsurpassed soft tissue contrast, lack of radiation exposure, and implementation of fast scanning techniques. As a virtual endoscopic technique, MR colography (MRC) makes it possible to image inflammatory processes and tumor disease of the large intestine with a high degree of accuracy. In this article we describe current techniques and applications of MRC and give an overview of clinical studies comparing MRC with other diagnostic procedures.

MRI of the knee at 7.0 Tesla.

PURPOSE: Measurement protocols which have been optimized for MRI at field strengths of 1.5 T or 3 T cannot be directly transferred to 7 T. Specific absorption rate limitations, different tissue relaxation times, as well as new image artifacts require adjustments of the sequence parameters. The goal of our study was to investigate and optimize various sequences for 7 T imaging of the knee. MATERIALS AND METHODS: Starting with sequences used on a standard 1.5 T scanner, the parameters were modified to obtain optimal image contrast, maximum coverage, and the highest spatial resolution within a reasonable acquisition time. All sequences were optimized in two healthy volunteers and then tested in 10 patients with various pathologies. High-resolution 7 T images with several SE and GRE sequences were acquired and compared to 1.5 T images. RESULTS: A comparison of 1.5 T and 7 T images clearly shows the advantage of MRI at higher field strengths, especially the higher SNR which could be translated into higher spatial resolution. The MEDIC sequence appears to be very well suited for the assessment of cartilage pathologies at 7 T. Using the DESS sequence, full coverage of the knee can be obtained with a very high resolution of 0.4 x 0.4 x 1.0 mm(3) within 7 minutes. Despite optimization of the STIR sequence parameters, bone marrow edema is better visualized at 1.5 T compared to 7 T. The PD TSE renders excellent image quality at 7 T. The total acquisition time of the 7 T protocol is approximately 40 minutes. CONCLUSION: Gradient echo sequences provide excellent image contrast at very high spatial resolution in a reasonable scan time. However, not all sequences used at 1.5 T are currently well suited for high-field imaging, in particular SAR-intensive sequences. Imaging of meniscal tears and lesions of the cruciate ligaments may benefit from the higher spatial resolution. The most favorable clinical indication for knee examinations at 7 T currently appears to be cartilage imaging.

[Rapid total body fat measurement by magnetic resonance imaging: quantification and topography]. / Schnelle Ganzkörperfettmessung mittels MRT: Quantifizierung und Topografie.

PURPOSE: To evaluate a rapid and comprehensive MR protocol based on a T1-weighted sequence in conjunction with a rolling table platform for the quantification of total body fat. MATERIALS AND METHODS: 11 healthy volunteers and 50 patients were included in the study. MR data was acquired on a 1.5-T system (Siemens Magnetom Sonata). An axial T1-weighted flash 2D sequence (TR 101, TE 4.7, FA 70, FOV 50 cm, 205 x 256 matrix, slice thickness: 10 mm, 10 mm interslice gap) was used for data acquisition. Patients were placed in a supine position on a rolling table platform capable of acquiring multiple consecutive data sets by pulling the patient through the isocenter of the magnet. Data sets extending from the upper to lower extremities were collected. The images were analyzed with respect to the amount of intraabdominal, subcutaneous and total abdominal fat by semi-automated image segmentation software that employs a contour-following algorithm. RESULTS: The obtained MR images were able to be evaluated for all volunteers and patients. Excellent correlation was found between whole body MRI results in volunteers with DEXA (r (2) = 0.95) and bioimpedance (r (2) = 0.89) measurements, while the correlation coefficient was 0.66 between MRI and BMI, indicating only moderate reliability of the BMI method. Variations in patients with respect to the amount of total, subcutaneous, and intraabdominal adipose tissue was not related to standard anthropometric measurements and metabolic lipid profiles (r (2) = 0,001 to 0.48). The results showed that there was a significant variation in intraabdominal adipose tissue which could not be predicted from the total body fat (r (2) = 0.14) or subcutaneous adipose tissue (r (2) = 0.04). Although no significant differences in BMI could be found between females and males (p = 0.26), females showed significantly higher total and subcutaneous abdominal adipose tissue (p < 0.05). CONCLUSION: This MR protocol can be used for the rapid and non-invasive quantification of body fat. The missing relationship between serum lipids and body fat masses suggests that the latter is an additional and independent hazard factor. Variations in body fat distribution, e. g. relationship between subcutaneous and intraabdominal fat, can be comprehensively assessed.

[Whole-body MR diagnostic concepts]. / MR-Ganzkörperdiagnostik.

The term whole-body magnetic resonance imaging (MRI) covers a whole series of different MRI techniques that can be used for detecting various diseases. Whole-body magnetic resonance angiography facilitates the visualization of the entire arterial system from head to toe with the exception of the coronary arteries. Whole-body MRA is clinically used for therapy planning in patients with multiple stenoses and may be able to be used in the future as a screening method for high risk populations, for example in patients with coronary heart disease. Whole-body MRI can replace skeletal scintigraphy in the detection of bone marrow metastases by using fluid-sensitive sequences. Fast contrast-enhanced sequences can be used as an alternative approach in the search for tumors. Whole-body MRI can even be superior to a combination of positron-emission tomography and computed tomography in the detection of distant metastases. This article presents the recent developments in whole-body MRI and its established indications, which in the future might lead to a change in the paradigm for the diagnostic work-up of many diseases.

[Are chest radiographs justified in pre-employment examinations? Presentation of legal position and medical evidence based on 1760 cases]. / Ist die Röntgenthoraxaufnahme bei Neueinstellungen gerechtfertigt? Darstellung von Rechtslage und medizinischer Evidenz in 1760 Fällen.

BACKGROUND: The legal and medical basis for chest radiographs as part of pre-employment examinations (PEE) at a University Hospital is evaluated. The radiographs are primarily performed to exclude infectious lung disease. METHODS: A total of 1760 consecutive chest radiographs performed as a routine part of PEEs were reviewed retrospectively. Pathologic findings were categorized as "nonrelevant" or "relevant." RESULTS: No positive finding with respect to tuberculosis or any other infectious disease was found; 94.8% of the chest radiographs were completely normal. Only five findings were regarded as "relevant" for the individual. No employment-relevant diagnosis occurred. CONCLUSIONS: The performance of chest radiography as part of a PEE is most often not justified. The practice is expensive, can violate national and European law, and lacks medical justification.