Novel oral phosphate binder with nanocrystalline maghemite-phosphate binding capacity and pH effect.

Hyperphosphatemia is one of the main risk factors contributing to morbidity and mortality in patients with end stage renal disease. The demand for a new phosphate binder is continuously increasing since the number of patients suffering under hyperphosphatemia is growing. However, side effects and high pill burden of currently available phosphate binders are the main reasons for low compliance and uncontrolled serum phosphate levels. Therefore, the aim of this study was to develop a novel phosphate binder with a high phosphate binding capacity over the entire gastrointestinal (GI) pH range. This novel phosphate binder C-PAM-10 is based on d-mannose coated nanocrystalline maghemite and belongs to the new class of phosphate binders, called the "iron based agents". It was possible to obtain a phosphate binding product that showed very high phosphate binding capacities with the characteristic of being pH independent at relevant pH ranges. The simulation of a GI passage ranging from pH 1.2 to pH 7.5 showed a 2.5 times higher phosphate binding capacity compared to the commonly used phosphate binder sevelamer carbonate. The simulation of a pH sensitive coating that releases the iron based phosphate binder at pH values ≥4.5 still showed a very high phosphate binding capacity combined with very low iron release which might decrease iron related side effects in vivo. Therefore, C-PAM-10 and its variations may be very promising candidates as a superior phosphate binder.

ECG-gated imaging of the left atrium and pulmonary veins: Intra-individual comparison of CTA and MRA.

AIM: To compare electrocardiography (ECG)-gated computed tomography angiography (CTA) with ECG-gated magnetic resonance angiography (MRA) for assessment of the left atrium (LA) and pulmonary veins (PVs). MATERIAL AND METHODS: Twenty-nine consecutive patients who underwent both cardiac CTA and MRA were evaluated. Contrast-enhanced CTA was performed with prospective ECG-gating using a 320 detector row CT system. Contrast-enhanced MRA was performed with prospective ECG-gating using a 1.5 T MRI system equipped with a 32 channel cardiac coil. MRA was acquired during free-breathing with a navigator-gated inversion-recovery prepared steady-state free precession sequence. Two readers independently assessed the CTA and MRA images for vascular definition of the PVs (from 0, not visualized, to 4, excellent definition) and ostial PV diameters. Variants of LA anatomy were assessed in consensus. RESULTS: CTA was successfully performed in all patients with a mean radiation exposure of 5.1 ± 2.2 mSv. MRA was successfully performed in 27 of 29 patients (93 %). Visual definition of PVs was rated significantly higher on CTA compared to MRA (p < 0.0001; reader 1: excellent/good ratings of CTA versus MRA: 100% versus 86%; reader 2: excellent/good ratings of CTA versus MRA: 99% versus 89%). Assessment of ostial PV diameters showed good correlation between CTA and MRA (reader 1: Pearson r = 0.91; reader 2: Pearson r = 0.82). Moreover, agreement between both imaging methods for evaluation of variants of LA anatomy was high (agreement rate of 95% (95% CI: 92-99%). CONCLUSION: ECG-gated CTA provides higher image quality compared to ECG-gated MRA. Nevertheless, both CTA and MRA provided similar information of LA anatomy and ostial PV diameters.

Impact of magnetic field strength and receiver coil in ocular MRI: a phantom and patient study.

PURPOSE: Generally, high-resolution MRI of the eye is performed with small loop surface coils. The purpose of this phantom and patient study was to investigate the influence of magnetic field strength and receiver coils on image quality in ocular MRI. MATERIALS AND METHODS: The eyeball and the complex geometry of the facial bone were simulated by a skull phantom with swine eyes. MR images were acquired with two small loop surface coils with diameters of 4 cm and 7 cm and with a multi-channel head coil at 1.5 and 3 Tesla, respectively. Furthermore, MRI of the eye was performed prospectively in 20 patients at 1.5 Tesla (7 cm loop surface coil) and 3 Tesla (head coil). These images were analysed qualitatively and quantitatively and statistical significance was tested using the Wilcoxon-signed-rank test (a p-value of less than 0.05 was considered to indicate statistical significance). RESULTS: The analysis of the phantom images yielded the highest mean signal-to-noise ratio (SNR) at 3 Tesla with the use of the 4 cm loop surface coil. In the phantom experiment as well as in the patient studies the SNR was higher at 1.5 Tesla by applying the 7 cm surface coil than at 3 Tesla by applying the head coil. Concerning the delineation of anatomic structures no statistically significant differences were found. CONCLUSION: Our results show that the influence of small loop surface coils on image quality (expressed in SNR) in ocular MRI is higher than the influence of the magnetic field strength. The similar visibility of detailed anatomy leads to the conclusion that the image quality of ocular MRI at 3 Tesla remains acceptable by applying the head coil as a receiver coil.

Dynamic contrast enhanced MRI of the prostate: comparison of gadobutrol and Gd-DTPA.

PURPOSE: To evaluate the enhancement profile of the macrocyclic contrast medium (CM) gadobutrol in comparison to linear CM Gd-DTPA in DCE-MRI of the prostate. MATERIALS AND METHODS: In total 53 patients with prostata cancer (PCa) were included, who received a radical prostatectomy after multiparametric MRI of the prostate including DCE-MRI. Using circular regions of interests normal peripheral zone (PZ) and PCa foci > 5 mm in diameter (42 and 34 foci in Gd-DTPA and gadobutrol group, respectively) were analysed in DCE-MRI. Enhancement curves (Type I, II and III) and pharmacokinetic parameters were analyzed qualitatively and quantitatively and compared using mixed linear models (two sided p-values < 0.05 were regarded significant). RESULTS: There was no significant difference in frequencies of curve types I, II or III in the normal PZ (p = 0.63) or in PCa foci (p = 0.75). PCa with a Gleason score ≥ 7 had in comparison to Gleason ≤ 6 significantly more often a Wash-Out-curve (Type III) with both CM (p = 0.02). The relative peak enhancement was in the PZ (Gd-DTPA 1.4 a. u. [1.20; 1.59], gadobutrol 1.58 a. u. [1.37; 1.78]) and in PCa foci (Gd-DTPA 1.56 a. u. [1.41; 1.71], gadobutrol 1.76 a. u. [1.59; 1.94]) significantly higher with gadobutrol (p = 0.04). The pharmacokinetic parameters Ktrans und kep were higher in PCa foci than in PZ (p < 0.0001 and p = 0.002, respectively) without significant difference of the parameter values between both CM (p = 0.65). CONCLUSION: [corrected] This study is the first systematic comparison of gadobutrol and Gd-DTPA in DCE-MRI of the prostate. The relative peak enhancement is higher using gadobutrol compared to Gd-DTPA in DCE-MRI. There was no statistically significant difference in curve types or the pharmacokinetic parameters in PCa or normal PZ between both CM.

Results from a 1-year, open-label, single arm, multi-center trial evaluating the efficacy and safety of oral Deferasirox in patients diagnosed with low and int-1 risk myelodysplastic syndrome (MDS) and transfusion-dependent iron overload.

The majority of patients with myelodysplastic syndrome (MDS) present with anemia and will become dependent on regular transfusions of packed red blood cells (PRBC) with the risk of iron overload (IOL). Liver iron content best reflects the total body iron content, and measurement of liver iron concentration (LIC) by MRI is a validated tool for detection, but data in MDS is rather limited. Here we present the results of a multi-center trial evaluating the efficacy and safety of deferasirox (DFX) in low and intermediate-1 risk MDS patients with transfusion-dependent IOL. Three patients with transfusion frequency of > 4 units PRBC per month were initially treated with 30 mg/kg/day while in 46 patients with a lower transfusion burden deferasirox was initiated at 20 mg/kg/day, due to patient related reasons one patient received DFX in a dose of 6 mg/kg/day only. LIC was measured by MRI at baseline and end of study using the method by St. Pierre et al. The intention to treat population consisted of 50 MDS patients (28 male; 22 female) with a median age of 69 years who were treated with DFX for a median duration of 354 days. Mean daily dose of DFX was 19 mg/kg/day. Median serum ferritin level (SF) at baseline was 2,447 ng/mL and decreased to 1,685 ng/mL (reduction by 31 %) at end of study (p = 0.01). In 7 (13 %) patients the initially chosen dose had to be increased due to unsatisfactory efficacy of chelation therapy. For 21 patients, LIC measurement by liver MRI was performed at baseline and for 19 of these patients at the end of study: mean LIC decreased significantly from 16,8 mg/g dry tissue weight (± 8.3 mg/g dry tissue weight) at study entry to 10,8 mg/g dry tissue weight (± 10.4 mg/g dry tissue weight) at end of study (p = 0.01). Of all patients exposed to the study drug (n = 54), 28 (52 %) did not complete the 12 month study period most commonly due to AEs in 28 % (n = 15) and abnormal laboratory values in 7 % (n = 4), respectively. The most common adverse events (≥ 10 % of all patients) with suspected drug relationship were diarrhea (n = 25, 46 %), nausea (n = 13, 24 %), upper abdominal pain (n = 8, 15 %), serum creatinine increase (n = 16, 30 %) and rash (n = 5, 9 %). Adverse events making dose adjustments or interruption of study drug necessary occurred in 33 patients (61 %). Hematologic improvement according to IWG criteria (2006) was observed in 6 patients (11 %). Initiation of treatment of IOL with DFX depending on the transfusion burden yields sufficient reduction of excess iron indicated by serum ferritin levels and most importantly by liver MRI. The safety profile of DFX was comparable to previous observations.

Assessing prostate cancer growth with citrate measured by intact tissue proton magnetic resonance spectroscopy.

BACKGROUND: Annual PSA tests have led to a significant increase in the number of prostate cancer (PCa) cases diagnosed. This increased incidence has led to overtreatment of many patients, as current pathology often cannot distinguish latent from aggressive PCa. Studies have shown that the depletion of zinc in prostate cells correlated with cell-line growth rates, and may therefore relate to the progression of PCa. Furthermore, as zinc is normally an inhibitor of citrate oxidation, the reduction of zinc in PCa may cause a decrease in citrate secretion levels in the glandular epithelia of PCa patients. METHODS: Using high-resolution magic angle spinning proton magnetic resonance spectroscopy followed by quantitative histopathology, we investigate unit histo-benign prostate epithelial citrate concentrations in intact tissue samples obtained from 18 patients with pre-surgical PSA values less than 20 ng/ml. Using these data, we evaluate correlations between citrate concentrations and PSA velocities, densities and blood percent-free PSA. RESULTS: We observe different linear patterns between citrate concentrations and histo-benign glandular epithelia from patients of different PSA velocities. More importantly, we obtain a significant correlation between PSA velocity, density and percent-free PSA, and citrate concentrations in unit volume of histo-benign epithelial glands of the peripheral zone. CONCLUSIONS: Low levels of citrate in unit volume represent rapidly increasing PSA values, and, therefore, may be used as an indicator of fast-growing PCa. Thus, tissue samples obtained at the time of biopsy may be evaluated for their citrate concentrations for the prediction of PCa growth rates, allowing for the implementation of alternative treatment options and reducing overtreatment.

Cardiac magnetic resonance angiography using blood-pool contrast agents: comparison of citrate-coated very small superparamagnetic iron oxide particles with gadofosveset trisodium in pigs.

PURPOSE: To compare citrate-coated very small superparamagnetic iron oxide particles (VSOP) with gadofosveset trisodium as blood pool contrast agents for cardiac magnetic resonance angiography (CMRA) in pigs. MATERIALS AND METHODS: Animal experiments were approved by the responsible authority. 10 CMRA-like examinations were performed at 1.5 T after administration of VSOP (0.06  mmol Fe/kg; 5 examinations) and gadofosveset trisodium (0.03  mmol Gd/kg; 5 examinations). The CMRA protocol included ECG-gated inversion-recovery-prepared T1-weighted gradient echo imaging (IR-GRE; one slice) and ECG-gated inversion recovery prepared steady state free precession imaging (IR SSFP; one slice) before and 1, 3, 5, 10, 15, 20, 25, 30, 40, 50, and 60  min after injection. At each time point, three different inversion times (TI; 200  msec, 300  msec, and 400  msec) were applied. Contrast-to-noise ratios (CNR) between blood and myocardium were calculated and compared using mixed linear models. RESULTS: No significant differences of CNR were found between IR-GRE and IR SSFP. At 3 and 5  min after contrast agent administration, VSOP showed a significantly higher CNR than gadofosveset trisodium when TI of 200  msec and 300 msec were applied (TI of 200  msec at 3 min: 8.2 ±â€Š0.7 vs. 5.4 ±â€Š0.7; TI of 200  msec at 5 min: 7.9 ±â€Š0.7 vs. 3.5 ±â€Š0.8; TI of 300  msec at 3  min: 11.7 ±â€Š0.7 vs. 8.8 ±â€Š0.8; TI of 300  msec at 5  min: 11.4 ±â€Š0.7 vs. 8.0 ±â€Š0.8; p < 0.05). Moreover, significant differences in favor of VSOP were found for all time points from 10 to 40  min irrespective of TI (p < 0.05). CONCLUSION: VSOP has superior blood-pool properties compared to gadofosveset trisodium resulting in prolonged improvement of CNR on CMRA.

[Magnetic particle imaging (MPI)]. / Magnetic Particle Imaging (MPI).

Magnetic particle imaging (MPI) displays the spatial distribution and concentration of superparamagnetic iron oxides (SPIOs). It is a quantitative, tomographic imaging method with high temporal and spatial resolution and allows work with high sensitivity yet without ionizing radiation. Thus, it may be a very promising tool for medical imaging. In this review, we describe the physical and technical basics and various concepts for clinical scanners. Furthermore, clinical applications such as cardiovascular imaging, interventional procedures, imaging and therapy of malignancies as well as molecular imaging are presented.

Effect of butylscopolamine on image quality in MRI of the prostate.

AIM: To evaluate the impact of butylscopolamine on the quality of magnetic resonance imaging (MRI) images of the prostate. MATERIAL AND METHODS: Eighty-two MRI examinations of the prostate were retrospectively analysed. MRI was performed with a combined endorectal/body phased-array coil including proton density-weighted (PD) sequence, T1-weighted turbo spin-echo (TSE)-sequence, and T2-weighted TSE-sequences. Forty milligrams of butylscopolamine was administered intramuscularly in 31 patients (im-group) and intravenously in 30 patients (iv-group). Twenty-one patients did not receive premedication with butylscopolamine (ø-group). Overall image quality, delineation of the bowel wall, and visualization of the prostate, neurovascular bundle, and pelvic lymph nodes were evaluated qualitatively using a five-point scale (from 1=excellent to 5=non-diagnostic/structure not discernible). Motion artefacts within the endorectal coil were quantified by baseline adjusted signal intensities inside the endorectal coil area. RESULTS: Delineation of the bowel wall using the PD-sequence was significantly improved after both intramuscular and intravenous butylscopolamine administration (ø-group: 3.6+/-0.7; im-group: 2.9+/-0.7; iv-group: 2.9+/-0.7; p=0.001). However, there were no significant differences in motion artefacts measured within the endorectal coil (ø-group: 1.18+/-0.14; im-group: 1.15+/-0.11; iv-group: 1.12+/-0.06; p=0.39). There were also no significant differences in qualitative assessment of visualization of the prostate, neurovascular bundle, pelvic lymph nodes, and of overall image quality between the study groups. CONCLUSION: : In conclusion, butylscopolamine had only a small effect on image quality and is not mandatory for MRI of the prostate.

[Pharmacokinetic MRI of the prostate: parameters for differentiating low-grade and high-grade prostate cancer]. / Pharmakokinetische MRT der Prostata: Parameter zur Unterscheidung von Low-grade- und High-grade-Prostatakarzinomen.

PURPOSE: To investigate whether pharmacokinetic MRI parameters "perfusion, blood volume, mean transit time (MTT), interstitial volume, permeability, extraction coefficient, delay, and dispersion" allow the differentiation of low-grade (Gleason score < or = 6) and high-grade (Gleason score > or = 7) prostate cancer. MATERIALS AND METHOD: Forty-two patients with prostate cancer verified by biopsy (PSA 2.7 to 31.4 ng/ml) and scheduled for prostatectomy underwent MRI at 1.5 Tesla using the dynamic contrast-enhanced inversion-prepared dual-contrast gradient echo sequence (temporal resolution, 1.65 s) and a combined endorectal body phased array coil. Parametric maps were computed using a sequential 3-compartment model and the corresponding post-processing algorithms. A total of 41 areas of prostate cancer (15 low-grade, 26 high-grade cancers) in 32 patients were able to be correlated with the prostatectomy specimens and were included in the analysis. RESULTS: Low-grade prostate cancers had a higher mean blood volume (1.76 % vs. 1.64 %, p = 0.039), longer MTT (6.39 s vs. 3.25 s, p < 0.001), and lower mean permeability (2.57 min (-1) vs. 3.86 min (-1), p = 0.011) than high-grade cancers. No statistically significant difference was found for perfusion (p = 0.069), interstitial volume (p = 0.849), extraction coefficient (p = 0.615), delay (p = 0.489), and dispersion (p = 0.306). CONCLUSIONS: Blood volume, MTT, and permeability allow the differentiation of low-grade and high-grade prostate cancer. They may be used to detect cancer progression by MRI in patients managed by active surveillance.

High-resolution T2-weighted abdominal magnetic resonance imaging using respiratory triggering: impact of butylscopolamine on image quality.

BACKGROUND: Respiratory triggering allows the acquisition of high-resolution magnetic resonance (MR) images of the upper abdomen. However, the depiction of organs close to the gastrointestinal tract can be considerably impaired by ghosting artifacts and blurring caused by bowel peristalsis. PURPOSE: To evaluate the effect of gastrointestinal motion suppression by intramuscular butylscopolamine administration on the image quality of a respiratory-triggered T2-weighted turbo spin-echo (T2w TSE) sequence of the upper abdomen. MATERIAL AND METHODS: Images of 46 patients were retrospectively analyzed. Twenty-four patients had received intramuscular injection of 40 mg butylscopolamine immediately before MR imaging. Fourteen of the 24 patients in the butylscopolamine group underwent repeat imaging after a mean of 29 min. Quantitative analysis of the ghosting artifacts was done by measuring signal intensities in regions of interest placed in air anterior to the patient. In addition, image quality was assessed qualitatively by two radiologists by consensus. RESULTS: Spasmolytic medication with butylscopolamine reduced ghosting artifacts and significantly improved image quality of the respiratory-triggered T2w TSE sequence. The most pronounced effect of butylscopolamine administration on image quality was found for the pancreas and the left hepatic lobe. The rate of examinations with excellent or good depiction of the pancreas and the left hepatic lobe in the group without premedication and in the butylscopolamine group was 55% vs. 96% (pancreatic head), 35% vs. 88% (pancreatic body), 43% vs. 96% (pancreatic tail), and 45% vs. 83% (left hepatic lobe), respectively. Regarding the duration of the effect of intramuscular butylscopolamine, repeat imaging after a mean of 29 min did not result in a significant deterioration of image quality. CONCLUSION: Intramuscular butylscopolamine administration significantly improves image quality of respiratory-triggered T2-weighted abdominal MR imaging by persistent reduction of peristaltic artifacts. MR imaging of the liver and pancreas in particular benefits from the suppression of gastrointestinal peristalsis by butylscopolamine.

[Preoperative imaging in 78 living kidney donors using CE-MRA and DSA]. / Donor-Evaluation vor Lebendnierenspende: Vergleich von CE-MRA und DSA an 78 Patienten.

PURPOSE: To evaluate contrast-enhanced 3D magnetic resonance angiography (CE-MRA) and digital subtraction angiography (DSA) in comparison with the intraoperative findings in living kidney donors. MATERIALS AND METHODS: A total of 156 kidneys in 78 potential kidney donors were prospectively examined using CE-MRA (0.2 mmol Gd/kg, voxel size 1.3 x 0.8 x 2.0) and DSA. Two experienced radiologists assessed the images in consensus regarding the renal vascular anatomy and variants. The results for the 67 candidates accepted for donation were compared to the intraoperative findings. In the other kidneys not accepted for donor nephrectomy, MRA and DSA were compared with each other. RESULTS: Nineteen arterial variants were identified intraoperatively, of which 11 (58%) were also detected by preoperative CE-MRA and 10 (53%) by preoperative DSA. Of the 10 venous variants found intraoperatively, CE-MRA detected 8 (80%) and DSA 3 (30%). The agreement (kappa test) between MRI and DSA for all 156 evaluated kidneys was 0.7 for arterial variants (McNemar p=0.12) and 0.3 for venous variants (McNemar p=0.01). The preoperative choice of kidney (right or left) made on the basis of the renal vascular anatomy seen on CE-MRA and DSA differed in 22% of the 78 potential donors (McNemar p=0.3). CONCLUSION: Our results in a large group of potential living kidney donors suggest that CE-MRA and DSA are comparable for detecting arterial renal variants while CE-MRA is superior for identifying venous variants. The preoperative choice of transplant kidney was not significantly influenced by the different results of CE-MRA and DSA.

Peripheral washout phenomenon in an animal tumour model: comparison of dynamic magnetic resonance imaging using a small molecular contrast medium with histology.

The peripheral washout sign was first described in delayed dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using a small molecular contrast medium in solid lesions of the human breast and liver. It was found to be 100% specific for malignant lesions and could therefore potentially be used as an additional noninvasive diagnostic tool differentiating malignant from benign lesions. The origin of this phenomenon has not yet been explained. The objective of this study was to translate the peripheral washout sign as seen in solid tumours in delayed DCE-MRI in human onto an animal model for further assessment of DCE-MRI characteristics and histological analysis. Small molecular contrast medium DCE-MRI was performed over 42 min in experimental colon carcinoma grown subcutaneously in rats. Qualitative and quantitative analyses for evaluation of presence and characteristics of the peripheral washout sign were accomplished, defining four centripetally distributed tumour zones (central, intermediate, peripheral and marginal). One hundred per cent of the carcinomas demonstrated a peripheral washout sign in DCE-MRI starting at 20 min after bolus injection. Histomorphological analysis was performed for tissue classification and evaluation of microvasculature. Quantitative analysis revealed different enhancement profiles of the four tumour zones. Histology indicated centripetally asymmetric vascularization and vascular endothelial growth factor VEGF/VEGF receptor 2 expression within the tumour tissue. Thus, peripheral washout sign can be translated to an animal model. However, comparison of small molecular contrast medium DCE-MRI with histology revealed that histology alone does not explain the occurrence of the peripheral washout.

Cine magnetic resonance imaging of the small bowel: comparison of different oral contrast media.

PURPOSE: To evaluate several substances regarding small bowel distension and contrast on balanced steady-state free precession (bSSFP) cine magnetic resonance (MR) images. MATERIAL AND METHODS: Luminal contrast was evaluated in 24 volunteers after oral application of two different contrast agent groups leading to either bright lumen (pineapple, blueberry juice) or dark lumen (tap water, orange juice) on T1-weighted images. Bowel distension was evaluated in 30 patients ingesting either methylcellulose or mannitol solution for limiting intestinal absorption. Fifteen patients with duodeno-jejunal intubation served as the control. Quantitative evaluation included measurement of luminal signal intensities and diameters of four bowel segments, qualitative evaluation assessed luminal contrast and distension on a five-point scale. RESULTS: Quantitative and qualitative evaluation of the four contrast agents revealed no significant differences regarding luminal contrast on bSSFP images. Quantitative evaluation revealed significantly lower (P<0.05) small bowel distension for three out of four segments (qualitative evaluation: two out of four segments) for methylcellulose in comparison to the control. Mannitol was found to be equal to the control. CONCLUSION: Oral ingestion of tap water or orange juice in combination with mannitol is recommended for cine MR imaging of the small bowel regarding luminal contrast and small bowel distension on bSSFP sequences.

[Whole-body MR angiography: comparison of two protocols for contrast media injection]. / Ganzkörper-MR-Angiographie: Vergleich von zwei Protokollen zur Kontrastmittelinjektion.

PURPOSE: To compare two injection strategies for contrast media injection in whole-body MR angiography quantitatively and qualitatively with regard to contrast and image quality. MATERIAL AND METHODS: 40 patients were examined at 1.5 Tesla using either a single injection protocol or a double injection protocol with two separate bolus injections. Vessel regions I (supraaortic/thoracic), II (abdominal/pelvic), III (upper legs) and IV (lower legs) were examined in the following order: single injection: I, II, III, IV, double injection: I and IV after the first injection, II and III after the second bolus injection. Quantitative evaluation: SI measurements were carried out in 2 arteries per region. Contrast values were calculated. Qualitative evaluation: Evaluation of regions I-IV regarding vessel contrast, venous overlay and image quality on a five-point scale by two reviewers in consensus. The Mann-Whitney-U test was used to test the differences for significance. RESULTS: Quantitative evaluation: Using the double injection protocol, significantly higher contrast values in regions I and II and significantly lower contrast values in the subregions IIIa (upper part of III) and IVb (lower part of IV) were obtained (p < 0.05). The mean contrast values in subregions IIIb (lower part of III) and IVa (upper part of IV) were lower using the double injection protocol, but not significantly. Qualitative evaluation: Using the double injection protocol, region II was rated significantly higher (mean ratings: 3.55, 3.45 and 3.5 versus 2.7, 2.5 and 2.55; p < 0.05) and region III significantly lower (mean ratings: 3.1, 2, 2.5 versus 3.9, 3.1 and 3.55; p < 0.05) for all three examined criteria. When using the double injection protocol, ratings were significantly lower in region IV regarding vessel contrast and image quality (mean ratings: 2.4 and 2.15 versus 3.45 and 3.15; p < 0.05). The ratings regarding venous overlay in region IV showed no significant differences (mean ratings: 2.15 versus 2.75; p > 0.05). CONCLUSION: Due to the better results in the supraaortic/thoracic and abdominal/pelvic regions, the double injection protocol is preferred. However, both protocols require further improvement.

[How safe is magnetic resonance imaging in patients with contraceptive implants?]. / Wie sicher ist die MRT bei Patientinnen mit kontrazeptiven Implantaten?

When patients with an implanted contraceptive device undergo MRI, it must be ensured that the examination involves no risk to the patient (MR safety) and that the diagnosis is not affected by artifacts or the function of the device compromised (MR compatibility). Two basic types of intrauterine devices can be distinguished: the metal-containing/metal-free intrauterine device (IUD) and the hormone-containing implant, the fully metal-free intrauterine system (IUS), as well as the ESSURE insert made of stainless steel, which has been approved for use in Europe since February 2001. The metal-containing and metal-free IUDs and ESSURE are MRI compatible up to a magnetic field strength of 1.5 T. They do not interact in any relevant way with the external magnetic or high-frequency field and the temperature increase is within the physiologic range. The implants merely produce a local signal void with a shape that depends on their orientation relative to the magnetic field lines. At 3 T, only the metal-free IUD and the IUS are MRI safe in terms of the material used. In contrast, metal-containing IUDs and the ESSURE have not yet been fully evaluated in the 3 T field, which is why they represent a contraindication to MRI. No data are available on the MRI compatibility at 3 T for any of these devices.

Differentiation of prostate cancer from normal prostate tissue in an animal model: conventional MRI and dynamic contrast-enhanced MRI.

PURPOSE: To differentiate orthotopically implanted prostate cancer from normal prostate tissue using magnetic resonance imaging (MRI) and Gd-DTPA-BMA-enhanced dynamic MRI in the rat model. MATERIAL AND METHODS: Tumors were induced in 15 rats by orthotopic implantation of G subline Dunning rat prostatic tumor cells. MRI was performed 56 to 60 days after tumor cell implantation using T1-weighted spin-echo, T2-weighted turbo SE sequences, and a 2D FLASH sequence for the contrast medium based dynamic study. The interstitial leakage volume, normalized permeability and the permeability surface area product of tumor and healthy prostate were determined quantitatively using a pharmacokinetic model. The results were confirmed by histologic examination. RESULTS: Axial T2-weighted TSE images depicted low-intensity areas suspicious for tumor in all 15 animals. The mean tumor volume was 46.5 mm(3). In the dynamic study, the suspicious areas in all animals displayed faster and more pronounced signal enhancement than surrounding prostate tissue. The interstitial volume and the permeability surface area product of the tumors increased significantly by 420 % (p < 0.001) and 424 % (p < 0.001), respectively, compared to normal prostate tissue, while no significant difference was seen for normalized permeability alone. CONCLUSION: The results of the present study demonstrate that quantitative analysis of contrast-enhanced dynamic MRI data enables differentiation of small, slowly growing orthotopic prostate cancer from normal prostate tissue in the rat model.

Complex genital malformation in a female with congenital adrenal hyperplasia: evaluation with magnetic resonance imaging.

This is a case of complex genital malformation in a young patient with congenital adrenal hyperplasia. The magnetic resonance imaging (MRI) findings included ostium of the vagina into the urethra (common urogenital opening), prostate-like tissue surrounding the urethra, and hyperplasia of the left adrenal gland. The report provides information on the clinical findings, the MRI examination, including the applied sequences and the MR findings, and gives an overview of the disease pattern and its frequency of occurrence.