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Objectives: To assess the extents of pelvic floor descent both during the maximal straining phase and the defecation phase in healthy volunteers and in patients with pelvic floor disorders, studied with MR defecography (MRD), and to define specific threshold values for pelvic floor descent during the defecation phase.Material and methods: Twenty-two patients (mean age 51 ± 19.4) with obstructed defecation and 20 healthy volunteers (mean age 33.4 ± 11.5) underwent 3.0T MRD in supine position using midsagittal T2-weighted images. Two radiologists performed measurements in reference to PCL-lines in straining and during defecation. In order to identify cutoff values of pelvic floor measurements for diagnosis of pathologic pelvic floor descent [anterior, middle, and posterior compartments (AC, MC, PC)], receiver-operating characteristic (ROC) curves were plotted.Results: Pelvic floor descent of all three compartments was significantly larger during defecation than at straining in patients and healthy volunteers (p < 0.002). When grading pelvic floor descent in the straining phase, only two healthy volunteers showed moderate PC descent (10%), which is considered pathologic. However, when applying the grading system during defecation, PC descent was overestimated with 50% of the healthy volunteers (10 of 20) showing moderate PC descent. The AUC for PC measurements during defecation was 0.77 (p = 0.003) and suggests a cutoff value of 45 mm below the PCL to identify patients with pathologic PC descent. With the adapted cutoff, only 15% of healthy volunteers show pathologic PC descent during defecation.Conclusion: MRD measurements during straining and defecation can be used to differentiate patients with pelvic floor dysfunction from healthy volunteers. However, different cutoff values should be used during straining and during defecation to define normal or pathologic PC descent. [ABSTRACT FROM AUTHOR]

Objectives: A nationwide survey was performed assessing current practice of dose data analysis in computed tomography (CT).Material and Methods: All radiological departments in Switzerland were asked to participate in the on-line survey composed of 19 questions (16 multiple choice, 3 free text). It consisted of four sections: (1) general information on the department, (2) dose data analysis, (3) use of a dose management software (DMS) and (4) radiation protection activities.Results: In total, 152 out of 241 Swiss radiological departments filled in the whole questionnaire (return rate, 63%). Seventy-nine per cent of the departments (n = 120/152) analyse dose data on a regular basis with considerable heterogeneity in the frequency (1-2 times per year, 45%, n = 54/120; every month, 35%, n = 42/120) and method of analysis. Manual analysis is carried out by 58% (n = 70/120) compared with 42% (n = 50/120) of departments using a DMS. Purchase of a DMS is planned by 43% (n = 30/70) of the departments with manual analysis. Real-time analysis of dose data is performed by 42% (n = 21/50) of the departments with a DMS; however, residents can access the DMS in clinical routine only in 20% (n = 10/50) of the departments. An interdisciplinary dose team, which among other things communicates dose data internally (63%, n = 76/120) and externally, is already implemented in 57% (n = 68/120) departments.Conclusion: Swiss radiological departments are committed to radiation safety. However, there is high heterogeneity among them regarding the frequency and method of dose data analysis as well as the use of DMS and radiation protection activities.Key Points: • Swiss radiological departments are committed to and interest in radiation safety as proven by a 63% return rate of the survey. • Seventy-nine per cent of departments analyse dose data on a regular basis with differences in the frequency and method of analysis: 42% use a dose management software, while 58% currently perform manual dose data analysis. Of the latter, 43% plan to buy a dose management software. • Currently, only 25% of the departments add radiation exposure data to the final CT report. [ABSTRACT FROM AUTHOR]

Objective: To develop recommendations that can be used as guidance for standardized approach regarding indications, patient preparation, sequences acquisition, interpretation and reporting of magnetic resonance imaging (MRI) for diagnosis and grading of pelvic floor dysfunction (PFD).Methods: The technique included critical literature between 1993 and 2013 and expert consensus about MRI protocols by the pelvic floor-imaging working group of the European Society of Urogenital Radiology (ESUR) and the European Society of Gastrointestinal and Abdominal Radiology (ESGAR) from one Egyptian and seven European institutions. Data collection and analysis were achieved in 5 consecutive steps. Eighty-two items were scored to be eligible for further analysis and scaling. Agreement of at least 80 % was defined as consensus finding.Results: Consensus was reached for 88 % of 82 items. Recommended reporting template should include two main sections for measurements and grading. The pubococcygeal line (PCL) is recommended as the reference line to measure pelvic organ prolapse. The recommended grading scheme is the "Rule of three" for Pelvic Organ Prolapse (POP), while a rectocele and ARJ descent each has its specific grading system.Conclusion: This literature review and expert consensus recommendations can be used as guidance for MR imaging and reporting of PFD.Key Points: • These recommendations highlight the most important prerequisites to obtain a diagnostic PFD-MRI. • Static, dynamic and evacuation sequences should be generally performed for PFD evaluation. • The recommendations were constructed through consensus among 13 radiologists from 8 institutions. [ABSTRACT FROM AUTHOR]

Objectives: The purpose was to report on the initial experience after implementation of a patient dose-monitoring system in conventional X-ray imaging.Methods: A dose-monitoring system collected dose data relating to different radiographs (one projection) and studies (two or more projections). Images were acquired on digital X-ray systems equipped with flat-panel detectors. During period 1, examinations were performed in a routine fashion in 12,614 patients. After period 1, technical modifications were performed and radiographers underwent training in radiation protection. During period 2, examinations were performed in 14,514 patients, and the radiographers were advised to read dose data after each radiograph/study. Dose data were compared by means of kerma area product (KAP, gray × centimetre squared) and entrance surface air kerma (ESAK, milligray).Results: During period 1, 13,955 radiographs and 8,466 studies were performed, and in period 2 16,090 radiographs and 10,389 studies. In period 2, KAP values for radiographs were an average of 25 % lower and for studies 7 % lower, and ESAK values for radiographs were 24 % lower and for studies 5 % lower. The reduction in KAP was significant in 8/13 radiographs and in 6/14 studies, and the reduction in ESAK was significant in 6/13 radiographs and 5/14 studies.Conclusions: Implementation of a patient dose-monitoring system in conventional X-ray imaging allows easy data collection, supports dose reduction efforts, and may increase radiographers' dose awareness.Key Points: • A dose-monitoring system enables easy dose data collection in X-ray imaging. • The system facilitates dose reduction efforts and may increase radiographers' radiation awareness. • Mean kerma-area-product significantly declined in period 2 in 8/13 radiographs and 6/14 studies. • In ESAK a significant decline was evident in 6/13 radiographs and 5/14 studies. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) is an excellent tool to understand the complex anatomy of the pelvic floor and to assess pelvic floor disorders. MRI enables static and dynamic imaging of the pelvic floor. Using static T2-weighted sequences the morphology of the pelvic floor can be visualized in great detail. A rapid half-Fourier T2-weighted, balanced steady state free precession, or gradient-recalled echo sequence are used to obtain sagittal images while the patient is at rest, during pelvic squeeze, during pelvic strain and to document the evacuation process. On these images the radiologist identifies the pubococcygeal line (PCL) (which represents the level of the pelvic floor). In normal findings, the base of the anterior and the middle compartment are above the PCL at rest, and the pelvic floor elevates during contraction. During straining the pelvic floor muscles should relax and the pelvic floor descends normally less than 3 cm below the PCL. Pelvic floor MRI based on the static and dynamic MRI sequences allows for the detection and characterization of a vast array of morphologic and functional pelvic floor disorders. In this review, we focus on technical aspects of static and dynamic pelvic floor MRI. [ABSTRACT FROM AUTHOR]

Objectives: To assess the diagnostic accuracy of 64-multidetector CT (MDCT) for restaging of patients with oesophageal cancer undergoing neoadjuvant therapy. Methods: Results of pathological staging were correlated with those from 64-MDCT before and after neoadjuvant treatment in 35 patients using the American Joint Committee on Cancer/TNM classification (7th edition). CT response was determined using the Response Evaluation Criteria in Solid Tumours (RECIST) method, modified for one-dimensional tumour diameter measurement. Results: 64-MDCT predicted T stage correctly in 34 % (12/35), overstaged in 49 % (17/35) and understaged in 17 % (6/35). Sensitivity/specificity values were as follows: T0, 20 %/92 %; T1-T2, 31 %/59 %; T3, 60 %/64 %; T4, 100 %/4 %. Negative predictive values for T3/T4 were 80 %/100 %. MDCT accurately predicted complete histopathological response in 20 % (accuracy 74 %) and overstaged in 80 %. Tumour regression grade was predicted correctly in only 8 % (2/25) and underestimated in 68 % (17/25). Accurate N stage was noted in 69 % (24/35). Conclusion: Although MDCT tends to be able to exclude advanced tumour stages (T3, T4) with a higher likelihood, the diagnostic accuracy of high resolution MDCT for restaging oesophageal cancer and assessing the response to neoadjuvant therapy has not improved in comparison to older-generation CT. Therefore, the future assessment of oesophageal tumour response should focus on combined morphologic and metabolic imaging. Key Points: • Multidetector CT (MDCT) has been beneficial for the evaluation of many tumours. • However diagnostic accuracy for restaging oesophageal cancer has not improved with MDCT. • MDCT tends to be able to exclude advanced tumour stages (T3/T4). • MDCT has a low accuracy for determining lymph node metastasis. • Oesophageal tumour response should be assessed by combined morphological and metabolic imaging. [ABSTRACT FROM AUTHOR]

Objective: To prospectively evaluate the diagnostic accuracy of whole-body T2-weighted (wbT2), whole-body diffusion-weighted imaging (wbDWI) and wbT2/wbDWI image fusion for malignant tumour detection compared with PET/CT.Methods: Sixty-eight patients (44 men; 60 ± 14 years) underwent PET/CT for staging of malignancy and were consecutively examined by 1.5-Tesla MRI including wbT2 and wbDWI. Two radiologists independently assessed wbDWI, wbT2, wbT2 + wbDWI (side-by-side) and wbT2 + wbDWI + wbT2/wbDWI image fusion for the presence of malignancy. PET/CT served as a reference standard.Results: PET/CT revealed 374 malignant lesions in 48/64 (75%) patients. Detection rates and positive predictive value (PPV) of wbT2 and wbDWI alone were 64% and 84%, and 57% and 93%, respectively. Detection rates and PPV of wbT2 and wbDWI for side-by-side analysis without and with fused images were 72% and 89%, and 74% and 91%, respectively. The detection rate was significantly higher with side-by-side analysis and fused image analysis compared with wbT2 and wbDWI alone (p = .0159; p < .0001). There was no significant difference between fused image interpretation and side-by-side analysis.Conclusions: WbDWI allows detection of malignant lesions with a similar detection rate to wbT2. Side-by-side analysis of wbT2 and wbDWI significantly improves the overall detection rate and fused image data provides no added value. [ABSTRACT FROM AUTHOR]

The purpose of the study was to retrospectively compare three-dimensional gadolinium-enhanced magnetic resonance angiography (conventional MRA) with MRA accelerated by a parallel acquisition technique (fast MRA) for the assessment of visceral arteries, using 64-detector-row computed tomography angiography (MDCTA) as the reference standard. Eighteen patients underwent fast MRA (imaging time 17 s), conventional MRA (29 s) and MDCTA of the abdomen and pelvis. Two independent readers assessed subjective image quality and the presence of arterial stenosis. Data were analysed on per-patient and per-segment bases. Fast MRA yielded better subjective image quality in all segments compared with conventional MRA (P = 0.012 for reader 1, P = 0.055 for reader 2) because of fewer motion-induced artefacts. Sensitivity and specificity of fast MRA for the detection of arterial stenosis were 100% for both readers. Sensitivity of conventional MRA was 89% for both readers, and specificity was 100% (reader 1) and 99% (reader 2). Differences in sensitivity between the two types of MRA were not significant for either reader. Interobserver agreement for the detection of arterial stenosis was excellent for fast (kappa = 1.00) and good for conventional MRA (kappa = 0.76). Thus, subjective image quality of visceral arteries remains good on fast MRA compared with conventional MRA, and the two techniques do not differ substantially in the grading of arterial stenosis, despite the markedly reduced acquisition time of fast MRA. [ABSTRACT FROM AUTHOR]

Background. We initiated a randomized controlled clinical trial to assess the effect of sirolimus on disease progression in patients affected by autosomal dominant polycystic kidney disease (ADPKD). Here we report the preliminary safety results of the first 6 months of treatment. [ABSTRACT FROM PUBLISHER]

The clinical and morphologic outcome of patients with obstructed defecation syndrome after stapled transanal rectal resection was prospectively evaluated. Twenty-four consecutive patients (22 women; median age, 61 (range, 36–74) years) who suffered from obstructed defecation syndrome and with rectal redundancy on magnetic resonance defecography were enrolled in the study. Constipation was assessed by using the Cleveland Constipation Score. Morphologic changes were determined by using closed-configuration magnetic resonance defecography before and after stapled transanal rectal resection. After a median follow-up of 18 (range, 6–36) months, Cleveland Constipation Score significantly decreased from 11 (range, 1–23) preoperatively to 5 (range, 1–15) postoperatively ( P = 0.02). In 15 of 20 patients, preexisting intussusception was no longer visible in the magnetic resonance defecography. Anterior rectoceles were significantly reduced in depth, from 30 mm to 23 mm ( P = 0.01), whereas the number of detectable rectoceles did not significantly change. Complications occurred in 6 of the 24 patients; however, only two were severe (1 bleeding and 1 persisting pain requiring reintervention). Clinical improvement of obstructed defecation syndrome after stapled transanal rectal resection correlates well with morphologic correction of the rectal redundancy, whereas correction of intussusception seems to be of particular importance in patients with obstructed defecation syndrome. [ABSTRACT FROM AUTHOR]

Purpose To prospectively assess and compare two formulations and methods of administration of low-dose nasal midazolam for the treatment of claustrophobic patients undergoing magnetic resonance imaging (MRI) as part of a multicenter Phase III trial. Materials and Methods In all, 108 consecutive adult claustrophobic patients were randomly assigned to one of two treatment groups (multidose group: MDG, unit-dose group: UDG). MDG encompassed 55 patients who received intranasally a 0.5% midazolam formulation into each nostril (total dose, 1.0 mg), whereas the 53 patients in UDG received a 1% midazolam formulation into only one nostril (total dose, 1.0 mg). This initial dose could be repeated once. Patient tolerance and anxiety were assessed using a questionnaire and a visual analog scale immediately before and after MRI. Image quality was evaluated using a five-point scale. Results In all, 53/55 MR examinations (96%) with MDG and 52/53 (98%) with UDG were completed successfully. The dose of 1 mg had to be repeated significantly less often in UDG compared to MDG (4/53, 8% vs. 13/55, 24%; P = 0.003). The image quality of all MR examinations was rated good to excellent, and slightly better in UDG ( P = 0.045). Conclusion Nasally applied low-dose midazolam is a patient-friendly solution to facilitate MRI of claustrophobicpatients. The nasal spray of UDG is superior to that of MDG with a necessity of additional dosing. J. Magn. Reson. Imaging 2008;28:866-872. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

To investigate the role of MR imaging (MRI) in the evaluation of peripheral nerve lesions of the upper extremities and to assess its impact on the patient management. Fifty-one patients with clinical evidence of radial, median, and/or ulnar nerve lesions and unclear or ambiguous clinical findings had MRI of the upper extremity at 1.5 T. MR images and clinical data were reviewed by two blinded radiologists and a group of three clinical experts, respectively, with regard to radial, median, and/or ulnar nerve, as well as muscle abnormalities. MRI and clinical findings were correlated using Spearman's (p) rank correlation test. The impact of MRI on patient management was assessed by the group of experts and ranked as "major," "moderate," or "no" impact. The correlation of MRI and clinical findings was moderate for the assessment of the median/radial nerve and muscles (p = 0.51/0.51/0.63, respectively) and weak for the ulnar nerve (p = 0.40). The impact of MRI on patient management was assessed as "major" in 24/51 (47%), "moderate" in 19/51 (37%), and "no" in 8/51 (16%) patients. MRI in patients with upper extremity peripheral neuropathies and unclear or ambiguous clinical findings substantially influences the patient management. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the quality of biliary duct visualization using Gd-EOB-DTPA-enhanced magnetic resonance cholangiography (EOB-MRC) in patients with liver cirrhosis. Forty adult patients with liver cirrhosis (cirrhosis group) and 20 adult individuals with normal liver parenchyma (control group) underwent EOB-MRC using T1-weighted GRE imaging up to 180 min after Gd-EOB-DTPA administration. Two observers assessed the visualization of each biliary structure and the overall anatomical visualization of the biliary tree. Child-Pugh, MELD score and laboratory findings were compared. The grade of visualization for each evaluated biliary structure was statistically different in the two groups (P = 0.004 to <0.001). The overall EOB-MRC quality was rated as sufficient for anatomical visualization of the biliary tree in all individuals of the control group 20 min after Gd-EOB-DTPA application, but in only 16/40 patients (40%) of the cirrhosis group within 30 min after application. Analysis of the ROC curves revealed that the cut-off values, for non-sufficient visualization of the biliary tree 20 min after Gd-EOB-DTPA application, were MELD scores > or =11 and total serum bilirubin levels > or =30 micromol/l. Consecutively, EOB-MRC in patients with liver cirrhosis resulted in a decreased or even non-visualization of the biliary tree in a substantial percentage of patients. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to assess the accuracy of double-contrast magnetic resonance (MR) imaging for the treatment response evaluation of hepatocellular carcinoma (HCC) in cirrhotic liver after transarterial chemoembolization (TACE).Methods: Twenty-two patients with 30 HCC nodules treated by TACE underwent double-contrast MR imaging 1 month after treatment. MR images were obtained before and after the sequential administration of superparamagnetic iron oxide (SPIO) and gadopentetate dimeglumine contrast agent within the same imaging session. Two observers retrospectively assessed all treated nodules for evidence of residual viable tumor after TACE. The diagnostic performance of gadolinium-enhanced, SPIO-enhanced, and double-contrast enhanced images was calculated. Histopathological and angiographical findings served as standard of reference. Receiver operating characteristic curves and areas under the curves (A (z)) were calculated.Results: Double-contrast technique (A (z) = 0.95) was significantly (p = 0.036) more accurate than SPIO-enhanced technique (A (z) = 0.92) and gadolinium-enhanced technique (p = 0.005) (A (z) = 0.81) in viable tumor detection after TACE. Double-contrast technique was significantly more sensitive (92%) than SPIO-enhanced technique (80%) and gadolinium-enhanced technique (68%). Kappa values for interobserver agreement ranged from 0.67 to 0.87 and were significantly different from zero (all p < 0.001).Conclusions: Compared to gadolinium-enhanced and SPIO-enhanced techniques, double-contrast technique significantly improves the detection of viable tumor in HCC after TACE. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess prospectively the potential of low-dose intranasal midazolam compared to oral midazolam in claustrophobic patients undergoing routine body magnetic resonance imaging (MRI). Seventy-two adult claustrophobic patients referred for body MRI were randomly assigned to one of two treatment groups (TG1 and TG2). The 36 patients of TG1 received 7.5 mg midazolam orally 15 min before MRI, whereas the 36 patients of TG2 received one (or, if necessary, two) pumps of a midazolam nasal spray into each nostril immediately prior to MRI (in total, 1 or 2 mg). Patients' tolerance, anxiety and sedation were assessed using a questionnaire and a visual analogue scale immediately before and after MRI. Image quality was evaluated using a five-point-scale. In TG1, 18/36 MRI examinations (50%) had to be cancelled, the reduction of anxiety was insufficient in 12/18 remaining patients (67%). In TG2, 35/36 MRI examinations (97%) were completed successfully, without relevant adverse effects. MRI image quality was rated higher among patients of TG2 compared to TG1 (p<0.001). Low-dose intranasal midazolam is an effective and patient-friendly solution to overcome anxiety in claustrophobic patients in a broad spectrum of body MRI. Its anxiolytic effect is superior to that of the orally administrated form. [ABSTRACT FROM AUTHOR]

Summary: Assessing the vascular status and anatomy of the lower extremity is of crucial importance when planning the coverage of a tissue defect with a free flap. The standard techniques comprise the clinical examination, Doppler ultrasound and Doppler sonography for healthy patients without suspected direct trauma to the vascular system, and conventional digital subtraction angiography (DSA), respectively, in case of traumatized vessels or patients with peripheral arterial obstructive disease. Materials: We have conducted a prospective study for the comparison of the magnetic resonance angiography (MRA) to the conventional DSA. Fourteen patients were examined presurgically by means of both a conventional DSA and an MRA before undergoing planned microvascular coverage of tissue defects of the lower extremity. The surgeon, based on a questionnaire, assessed and compared both examination results according to their information content. Furthermore, the presurgically planned level and localization of the vascular anastomoses and the intraoperative findings were compared postoperatively. Results: The MRA examination yielded sufficient information on the vascular anatomy to enable the surgeon to carry out a detailed presurgical planning. Additionally, the use of MRA showed clear advantages with regard to both patient and user comfort. Conclusion: Taking into account the advantages for the assessment of vessels using MRA, in particular when considering the impact of the frequently varying vascular anatomy of the lower leg on reconstructive surgery, as well as the significantly lower morbidity rate of the examination itself, then the MRA must be regarded as a safe alternative to the DSA. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate a new three-dimensional gradient-echo (GRE) MR sequence performed with a parallel acquisition technique to shorten breath-hold times (parallel GRE MRI) in the detection of arterial variants and stenosis of the abdominal aorta and its visceral branches. A total of 102 patients underwent dynamic parallel GRE MRI, timed to the arterial phase by a test bolus (mean breath-hold time, 17 s). For both quantitative and qualitative analysis, the abdominal aorta and its visceral branches were divided into 13 arterial segments. In a subanalysis of 55/102 patients, the accuracy of parallel GRE MRI compared to MDCT in the detection arterial variants and stenosis was calculated for two independent readers. Mean SNRs and CNRs were 47.2 and 35.6, respectively. Image quality was rated good or excellent in 1,234/1,326 segments (93%). Hepatic and renal arterial variants were identified with an accuracy of 93 and 95%, respectively (reader 1) and 98 and 100%, respectively (reader 2). Both readers detected arterial stenosis with an accuracy of 98%. Interobserver agreement was good to excellent for the detection of hepatic (kappa=0.69) and renal (kappa=0.92) variants and for the diagnosis of stenosis (kappa=0.96). Dynamic three-dimensional parallel GRE MRI is feasible and allows a reliable and accurate diagnosis of arterial variants and stenosis of the abdominal aorta and its visceral branches in a short breath-hold-time. [ABSTRACT FROM AUTHOR]

Background: Currently there is no effective treatment available to retard cyst growth and to prevent the progression to end-stage renal failure in patients with autosomal dominant polycystic kidney disease (ADPKD). Evidence has recently been obtained from animal experiments that activation of the mammalian target of rapamycin (mTOR) signaling pathway plays a crucial role in cyst growth and renal volume expansion, and that the inhibition of mTOR with rapamycin (sirolimus) markedly slows cyst development and renal functional deterioration. Based on these promising results in animals we have designed and initiated the first randomized controlled trial (RCT) to examine the effectiveness, safety and tolerability of sirolimus to retard disease progression in ADPKD. Method/design: This single center, randomised controlled, open label trial assesses the therapeutic effect, safety and tolerability of the mTOR inhibitor sirolimus (Rapamune®) in patients with autosomal dominant polycystic kidney disease and preserved renal function. The primary outcome will be the inhibition of kidney volume growth measured by magnetic resonance imaging (MRI) volumetry. Secondary outcome parameters will be preservation of renal function, safety and tolerability of sirolimus. Discussion: The results from this proof-of-concept RCT will for the first time show whether treatment with sirolimus effectively retards cyst growth in patients with ADPKD. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare respiratory-triggered balanced steady-state free precession (bSSFP) with breath-hold contrast-enhanced dynamic two-dimensional (2D) gradient-echo (GRE) and time-of-flight (TOF) magnetic resonance imaging (MRI) for portal and hepatic vein visualization and assessment of portal and hepatic venous variants. Sixty patients with liver disease underwent nonenhanced bSSFP and contrast-enhanced GRE, bSSFP, and TOF imaging. Contrast-to-noise ratios (CNRs) for portal and hepatic veins were measured. Two readers rated the quality of portal and hepatic vein visualization on a 5-point Likert scale. The diagnostic performance of each MRI series in the detection of portal and hepatic venous variants was assessed in 40/60 patients who also underwent contrast-enhanced multidetector-row computed tomography (MDCT). CNRs for portal and hepatic veins were highest on contrast-enhanced bSSFP images. Image quality of portal and hepatic veins was rated higher for nonenhanced bSSFP than for contrast-enhanced GRE (p<0.03) and TOF (p<0.003) and higher for contrast-enhanced than for nonenhanced bSSFP (p<0.003). Compared with MDCT, portal and hepatic venous variants were identified with an accuracy of 99% on bSSFP images, with an excellent interobserver agreement (kappa=0.97). Compared with MDCT, presence of surgically important portal and hepatic venous anatomical variants can be predicted with high accuracy on bSSFP images. [ABSTRACT FROM AUTHOR]

The effects of macronutrients on gastric volume changes, emptying, and gastrointestinal symptoms are incompletely understood. Three liquid meals of 500 ml (fat emulsion, 375 kcal; protein solution, 375 kcal; glucose solution, 400 kcal) were infused into the stomach of 12 healthy volunteers on three occasions. Studies were performed in seated body position using an open-configuration magnetic resonance imaging (MRI) system. MRI imaging sequences, assessing stomach and meal volumes, were performed prior to and at times t = 0, 3, 6, 9, 12, 15, 25, 35, 45, 60, 75, and 90 mm after meal administration. Areas under the curve for the early emptying phase (0-15 and 0-45 mm) were calculated, and characteristics of the volume curves were analyzed by a gastric emptying model. Gastrointestinal symptoms were assessed by a self-report scale. Initial (r = 0 mm) and early postprandial gastric volumes were highest for glucose because of lower initial emptying. However, in the early emptying phase the characteristics of the volume curves for stomach and meal were uniform for all macronutrients. Perceptions of fullness and satiety were linearly associated with postprandial gastric volumes, but not with macronutrient composition. Isovolumic macronutrient meals modulate gastric volume response by initial meal emptying patterns. Macronutrient specific accommodation responses, as shown in barostat studies, are not reflected as gastric volume responses under noninvasive conditions. [ABSTRACT FROM AUTHOR]

Objective. Gastric contents empty from the stomach despite frequent changes in body position. The mechanism that maintains gastric emptying independent of position is poorly understood. The aim of this study was to determine the effects of body position on gastric emptying and motor function. Material and methods. Twelve volunteers were investigated in seated position (SP) and upside-down position (UDP) after ingestion of 300 ml water. Magnetic resonance imaging provided a non-invasive assessment of gastric emptying and volumes, intragastric distribution and peristaltic function. Results. A marked difference in distal/proximal intragastric distribution between UDP and SP was present (7% versus 40%; p < 0.01). Gastric-emptying time was similar but emptying pattern was linear in UDP and exponential in SP. Peristalsis was slower in UDP than SP (2.75 versus 2.96 min-1; p < 0.01), but no correlation was found between peristaltic frequency and the rate of gastric emptying in either position. Postprandial volume response (gastric relaxation) was greater in UDP than SP (280 versus 250 ml; p < 0.05). A correlation was found between gastric relaxation and gastric-emptying time in SP (r 2=0.46) but not in UDP. Conclusions. The stomach maintains the rate of gastric emptying despite radical changes in body position and intragastric distribution of gastric contents. In SP, hydrostatic pressure (modulated by gastric tone) dictates the gastric emptying. In UDP, gastric emptying also appears to be mediated by continuous adaptation of gastric tone. These findings provide support for the hypothesis that the mechanism of gastric emptying resembles a "pressure pump" rather than a "peristaltic pump". [ABSTRACT FROM AUTHOR]

Purpose To evaluate whether ultrasmall superparamagnetic iron particles (USPIO)-enhanced MRI is capable of assessing both synovial perfusion characteristics and the presence of synovial macrophages in a model of antigen-induced arthritis. Materials and Methods Unilateral arthritis was induced in six knees of six rabbits. The contralateral knees of the rabbits served as control knees. After onset of arthritis, all 12 knees were scanned prior to and immediately following intravenous administration of USPIO using a multiphase T1-weighted (T1w) fast gradient-echo (FGRE) sequence, and T1w spin-echo (SE), T2-weighted (T2w) FSE, T2*w GRE, and short-tau inversion recovery (STIR) sequences prior to and 24 hours following USPIO administration. SI-vs.-time curves (STCs) and the early enhancement rate during the first 56 seconds (REE56) were calculated from SI measurements within the synovial tissue of all knees on dynamic T1w images. MR findings were correlated to histopathology. Results REE56 was significantly higher in the synovial tissue of arthritic knees than in the control knees ( P < 0.01). Significant T1-, T2-, and T2* effects ( P = 0.03-0.04) and multiple synovial vessels were visually detectable within the arthritic synovial tissue 24 hours after administration of USPIO, whereas no signal changes or synovial vessels were seen in the control knees. Histopathology revealed widened synovial blood vessels in the arthritic knees, and confirmed iron uptake by macrophages in the arthritic knees. Conclusion USPIO-enhanced MRI is capable of both assessing synovial hyperperfusion and detecting macrophages in antigen-induced arthritis in rabbits. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Magnetic resonance (MR) imaging has become an important diagnostic tool in evaluation of the musculoskeletal system. While most examinations are currently performed at magnetic field strengths of 1.5 T or lower, whole-body MR systems operating at 3.0 T have recently become available for clinical use. The higher field strengths promise various benefits, including increased signal-to-noise ratios, enhanced T2* contrast, increased chemical shift resolution, and most likely a better diagnostic performance in various applications. However, the changed T1, T2, and T2* relaxation times, the increased resonance-frequency differences caused by susceptibility and chemical-shift differences, and the increased absorption of radiofrequency (RF) energy by the tissues pose new challenges and/or offer new opportunities for imaging at 3.0 T compared to 1.5 T. Some of these issues have been successfully addressed only in the very recent past. This review discusses technical aspects of 3.0 T imaging as far as they have an impact on clinical routine. An overview of the current data is presented, with a focus on areas where 3.0 T promises equivalent or improved performance compared 1.5 T or lower field strengths. [ABSTRACT FROM AUTHOR]

Purpose To determine the effect of the right decubitus lying body position (RP) on relevant parameters of human gastric motor function in healthy volunteers. Materials and Methods Postprandial gastric function after ingestion of a solid/liquid meal (150 g/150 mL) was assessed over 90 minutes in volunteers in the RP and seated position (SP). Ten healthy volunteers were imaged using two MRI systems that differed in architecture and field strength. Stomach and intragastric air volume, intragastric meal distribution, gastric emptying, and gastric peristalsis were compared between the RP and SP. Results Body position did not affect gastric relaxation (RP, 372 mL vs. SP, 384 mL) and initial gastric volumes (stomach: RP, 458 mL vs. SP, 462 mL; meal: RP, 377 mL vs. SP, 399 mL; intragastric air: RP, 110 mL vs. SP, 98 mL). Postprandial stomach volume and gastric activity (RP and SP, 3.1 minute-1) were also similar. Meal emptying showed different characteristics, resulting in a significant but small difference in meal volume of -43 mL at t = 90 minutes ( P < 0.05). Conclusion Gastric MRI in RP is feasible for clinical research assessing gastric motor function. The subtle difference in meal emptying may be induced by posture-dependent vagal activity. This study confirms that MRI is a highly sensitive imaging technique for assessing gastrointestinal function in humans. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Static superior shoulder instability is associated with long-standing rotator cuff tears. Factors or mechanisms which can prevent superior migration of the humeral head, and therefore allow preservation or restoration of shoulder function despite nonanatomical cuff repair, are poorly understood. The question has therefore arisen, whether centering of the humeral head was the result of active shoulder muscle function. It was the goal of this experimental investigation to (1) determine the pattern of glenohumeral translations during active shoulder abduction measured by open-magnetic resonance imaging (MRI) techniques, and to (2) determine the influence of experimental paralysis of the infra- and supraspinatus muscles on these translations. In contrast to prior experimental investigations, the humeral head remained always centered in the glenoid fossa during active abduction. No superior migration of the humeral head could be provoked with experimental paralysis of the supra- and/or infraspinatus muscles. The hypothesis that static or dynamic superior humeral head displacement is prevented by active-supra- and/or infraspinatus muscle function must therefore be rejected, for the shoulder with a structurally intact muscle-tendon-bone unit. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:491-500, 2006 [ABSTRACT FROM AUTHOR]

Fibrocartilaginous embolization (FCE) of the spinal cord is a common disease in large breed dogs. There are only a few reports about this entity in small breed dogs and it has never been reported in chondrodystrophic breed. For definitive diagnosis histopathologic examination is necessary. Magnetic resonance imaging (MRI) as a potential diagnostic tool for intravitam diagnosis of FCE has been mentioned before, but results have not been reported so far. This report describes the neurological findings and MRI results in three small breed dogs, including a Pekingese dog, with FCE of the spinal cord. The disease was suspected in two animals based upon clinical and MRI-appearance and confirmed in the third by histopathological examination. In all three cases, similar focal intramedullary lesions, consisting of hyperintensive signals on T2-weighted images, were detected. Based on these findings, high-field MRI may be used as an antemortem tool for the diagnosis of FCE. It is also shown that FCE can occur in chondrodystrophic dogs. [ABSTRACT FROM AUTHOR]

Sensitivity encoding (SENSE) with a receiver coil array is typically used as a means of reducing the scan time in MRI. The speed benefit usually comes at some expense in terms of the signal-to-noise ratio (SNR) efficiency, which has been notorious as the main downside of SENSE and parallel MRI in general. In this work it is shown that in steady-state gradient-echo imaging the parallel approach may as well be used to increase the SNR efficiency. The basic idea is to balance reduced phase encoding by increasing the repetition time. In this fashion both the acquisition duty cycle and the steady-state magnetization can be enhanced, resulting in considerable net gains in SNR yield. It is argued that the reduction factor in parallel imaging is essentially an additional degree of freedom in optimizing the SNR. The optimal SENSE factor depends on scan, tissue, and hardware parameters, assuming values up to 3.0 and higher. The achievable SNR benefit also depends on the spoiling regime and is most pronounced for RF-spoiled techniques. The proposed mechanism is demonstrated by simulations and phantom experiments, as well as by contrast-enhanced angiography in vivo, achieving an approximate doubling of the SNR efficiency. Magn Reson Med 53:177-185, 2005. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Purpose To probe the potential and pitfalls of contrast medium first-pass skeletal muscle perfusion imaging under reproducible stress conditions. Materials and Methods Magnetic resonance (MR) signal dynamics in calf muscle and lower-leg arteries of 20 healthy volunteers were analyzed under postarterial occlusion reactive hyperemia and concurrent contrast medium first pass, using a saturation recovery spoiled gradient-echo type sequence without heartbeat synchronization. The signal vs. time curves were analyzed descriptively and by two-compartment deconvolution analysis. Results Highly significant changes in calf muscle signal dynamics in the hyperemic leg vs. those in the contralateral leg at rest were found in phenomenological and deconvolution analysis. Although a distortion of the arterial signal derived input function by inflow effects was found to cause large variations of the deconvolution results, the magnitude of the observed effects suggested a potential for immediate visual detection of areas with reduced tissue perfusion. Conclusion The first-pass approach appeared promising for visual evaluation. However, a disentanglement of inflow and contrast medium-induced effects on arterial signal intensity was deemed a prerequisite for input function-based numerical assessment. J. Magn. Reson. Imaging 2004;20:111-121. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Purpose. To develop a magnetic resonance imaging (MRI) technique for assessing in vivo properties of orally ingested gastric-retentive tablets under physiologic conditions. Methods. Tablets with different floating characteristics (tablet A-C) were marked with superparamagnetic Fe3O4 particles to analyze intragastric tablet position and residence time in human volunteers. Optimal Fe3O4 concentration was determined in vitro. Intragastric release characteristic of one slow-release tablet (tablet D) was analyzed by embedding gadolinium chelates (Gd-DOTA) as a drug model into the tablet. All volunteers underwent MRI in the sitting position. Tablet performance was analyzed in terms of relative position of tablet to intragastric meal level (with 100% at meal surface), intragastric residence time (min) and Gd-DOTA distribution volume (% of meal volume). Results. Intragastric tablet floating performance and residence time of tablets (tablet A-D) as well as the intragastric Gd-DOTA distribution of tablet D could be monitored using MRI. Tablet floating performance was different between the tablets (A, 93%(95 - 9%); B, 80%(80 - 68%); C, 38%(63 - 32%); p < 0.05). The intragastric distribution volume of Gd-DOTA was 19.9% proximally and 35.5% distally. Conclusions. The use of MRI allows the assessment of galenic properties of orally ingested tablets in humans in seated position. KEY WORDS: human stomach; drug delivery systems; floating tablet; superparamagnetic contrast marker; Gd-DOTA; intragastric tablet performance; seated magnetic resonance imaging. [ABSTRACT FROM AUTHOR]