Body Phased-array Coil Research Articles

Diffusion weighted MR imaging of pancreatic islet cell tumors

Purpose The aim of our study is to demonstrate the feasibility of body diffusion weighted (DW) MR imaging in the evaluation of pancreatic islet cell tumors (ICTs) and to define apparent diffusion coefficient (ADC) values for these tumors. Materials and methods 12 normal volunteers and 12 patients with histopathologically proven pancreatic ICT by surgery were included in the study. DW MR images were obtained by a body-phased array coil using a multisection single-shot echo planar sequence on the axial plane without breath holding. In addition, the routine abdominal imaging protocol for pancreas was applied in the patient group. We measured the ADC value within the normal pancreas in control group, pancreatic ICT, and surrounding pancreas parenchyma. Mann–Whitney U-test has been used to compare ADC values between tumoral tissues and normal pancreatic tissues of the volunteers. Wilcoxon Signed Ranks Test was preferred to compare ADC values between tumoral tissues and surrounding pancreatic parenchyma of the patients. Results In 11 patients out of 12, conventional MR sequences were able to demonstrate ICTs succesfully. In 1 patient an indistinct suspicious lesion was noted at the pancreatic tail. DW sequence was able to demonstrate the lesions in all of the 12 patients. On the DW images, all ICTs demonstrated high signal intensity relative to the surrounding pancreatic parenchyma. The mean and standard deviations of the ADC values (×10 −3 mm 2/s) were as follows: ICT ( n = 12), 1.51 ± 0.35 (0.91–2.11), surrounding parenchyma ( n = 11) 0.76 ± 0.15 (0.51–1.01) and normal pancreas in normal volunteers ( n = 12), 0.80 ± 0.06 (0.72–0.90). ADC values of the ICT were significantly higher compared with those of surrounding parenchyma ( p < 0.01) and normal pancreas ( p < 0.001). Conclusion DW MR imaging does not appear to provide significant contribution to routine MR imaging protocol in the evaluation of pancreatic islet cell tumors. But it can be added to MR imaging protocol to detect the lesion in a limited number of patients with clinical suspicion for pancreatic ICT with negative or suspicious imaging findings.

The Contribution of Cardiac Magnetic Resonance Imaging to the Diagnosis of Cardiac Diseases

Background : Cardiac magnetic resonance imaging (MRI) has been established in clinical practice as a valid imaging modality for the diagnosis of various cardiovascular disorders. Objectives : To underline the importance of cardiac MRI as an alternative non - invasive imaging method for the diagnosis and follow-up of cardiac patients based on findings from our own recent experience. Patients and Methods : The study included all cardiac patients referred for cardiac MRI over a period of one year. Cardiac MRI studies were performed with the use of a 1.5-Tesla scanner using a body phased-array coil, breath and ECG-triggering. A lmost all cardiac sequences were gated to the patient’s cardiac cycle. Cine imaging for the evaluation of cardiac volumes and heart motion was performed using a cine breath-hold true short-axis and true four-chamber sequence with whole left ventricular coverage. Black blood imaging for the assessment of morphology was acquired on a true short-axis and true four-chamber view. Depending on the pathology under investigation, special sequences were added to the imaging protocol, such as late-enhancement imaging after gadolinium administration. Results: The study cohort comprised 114 patients who were referred for cardiac MRI with the following indications and clinical diagnoses: myocarditis (n=29), arrhythmogenic right ventricular cardiomyopathy (ARVC; n=27), valvular heart disease (n=23), history of myocardial infarction (n=13; seeking myocardial viability), hypertrophic (n=12), or dilated (n=2), or tako-tsubo (n=1), or non-compaction (n=2) cardiomyopathy, pericardial effusion (n=2) and various intracardiac masses (n=3). Cardiac MRI confirmed the clinical diagnosis and gave further specific information in 52% of myocarditis cases, in 37% of suspected ARVC cases, in 38% of coronary artery disease patients regarding myocardial viability, while it confirmed all other clinical diagnoses (100% match). Conclusions : Cardiac MRI represents a clinically useful imaging method for the diagnosis of various cardiac disorders since it has the capability of providing highly accurate and reproducible measurements of cardiac hemodynamics in addition to the detailed demonstration of cardiac anatomical structures.

Quantitative Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Assessing Treatment Response in Hepatocellular Carcinoma

Quantitative Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Assessing Treatment Response in Hepatocellular Carcinoma

Dose comparison of single versus double dose in contrast-enhanced magnetic resonance angiography of the renal arteries: intra-individual cross-over blinded trial using Gd-DTPA

This study was planned as an open-label, single-centre trial with blinded evaluations by two independent radiologists, aimed at the intra-individual comparison of single-dose and double-dose Gd-DTPA-enhanced MRA in the renal arterial territory. Ten healthy volunteers were included in the study. Renal MRAs were carried out on a clinical 1.5-T MR system using a body phased-array coil. Images were acquired with three-dimensional fast spoiled gradient echo sequence. Contrast agent was injected with a power injector keeping the injection time constant for single dose and double dose. Both readers found at least 96% of vascular segments evaluable. Median overall image quality was rated excellent, and diagnostic confidence was rated confident. No statistically significant difference between the dosage groups could be demonstrated. Signal intensity, SNR and CNR were significantly higher for the double-dose group. Our results demonstrate that while a double dose of contrast agent increases SNR, it does not lead to further improvement in visual and perceptual image quality. A single dosage of approximately 0.1 mmol/kg bw Gd-DTPA may be the preferable dosage to demonstrate the renal arteries.

Whole-heart coronary magnetic resonance angiography with parallel imaging: Comparison of acceleration in one-dimension vs. two-dimensions

Purpose To evaluate visualization of the whole-heart coronary arteries accelerated with parallel imaging (PI) applied in two-dimension (2D) in comparison with one-dimension (1D). Materials and methods Seventeen healthy subjects were studied with a 1.5-T scanner equipped with a whole body phased array coil system and 16-channel receivers. Using 16 coil elements, whole-heart coronary magnetic resonance angiography (CMRA) was acquired in two conditions of 1D-PI and 2D-PI. The former scan was accelerated in phase direction by factor of 2 and the latter in phase and slice directions by factors of 2.5 and 2, respectively. Visualized length of right coronary artery (RCA), left anterior descending artery (LAD), and left circumflex artery (LCX) was measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was also measured. The CMRA quality was assessed in segment-wise with a five-point scale. Results The average scan time decreased to 5.3 ± 2.2 min in 2D-PI from 11.6 ± 3.5 min in 1D-PI, reducing the scan time to 45%. The visualized length, SNR, and CNR in average were smaller for images of 2D-PI compared with those of 1D-PI, however, statistically significant results were observed only in RCA ( P < 0.05). Score reduction of 2D-PI image quality was limited to 0.34 in average, and only two out of fifteen segments (#2, 6) showed significant score deterioration ( P < 0.05). Conclusions Compared with the relatively limited degree of image degradation, 2D-PI offered a large reduction of the acquisition time, which is of large benefit in clinical situations.

Congenital anomalies and variations of the bile and pancreatic ducts: magnetic resonance cholangiopancreatography findings, epidemiology and clinical significance

The objective of this paper is to document the magnetic resonance cholangiopancreatography (MRCP) findings and the epidemiology of congenital anomalies and variations of the bile and pancreatic ducts and to discuss their clinical significance. Three-hundred and fifty patients of both sexes (150 females, 200 males, age range 0-76 years, average age 38 years) underwent MRCP for clinically suspected lithiasic, neoplastic or inflammatory disease of the bile and pancreatic ducts. Patients were imaged with a 1.5-T superconductive magnet (Magnetom Vision, Siemens, Erlangen, Germany), a four-channel phased-array body coil, breath-hold technique, with multislice T2-weighted half-Fourier acquisition single-shot turbo spin echo (HASTE), MIP reconstructions, and a single-shot T2-weighted turbo-spin-echo sequence rapid acquisition with relaxation enhancement (RARE) with different slice thicknesses. Studies in oncological patients were completed with fat saturation 3D T1 gradient-echo sequences during the intravenous injection of gadolinium diethylene triamine pentaacetate acid (DTPA) (0.2 ml/kg). MRCP demonstrated recurrent and therefore normal bile and pancreatic ducts in 57% of patients. In the remaining 42.3%, it documented anatomical variants (41%) and congenital anomalies (1.3%). Variants of the intrahepatic bile duct were seen in 21% of cases: crossover anomaly (6.7%), anterior branch of the right hepatic duct draining the IV and VII segments that flow together with the left bile duct (3.1%) and anterior and posterior branches of the right hepatic duct that flow together with the common hepatic duct (3.3%). Variants of the extrahepatic bile ducts were present in 8.8% of patients: low insertion of the cystic duct into the common hepatic duct (4.5%), emptying of the cystic duct into the right hepatic duct (2.7%) and a second-order large branch draining into the cystic duct (1.6%). MRCP identified a double gall bladder in 3% of patients and anatomical variants of the biliopancreatic system in 8.2%: pancreas divisum (5.2%) and a long sphincter of Oddi (3%). Finally, congenital anomalies were diagnosed in 1.3% of cases: bile duct cysts (0.3%), atresia of the bile ducts (0.3%) and multiple biliary hamartomatosis (0.7%). The congenital anomalies and anatomical variants of the bile and pancreatic ducts present a complex spectrum of frequent alterations, which are worthy of attention in both the clinical and surgical settings and are readily identified by MRCP.

Detection of lymph node metastasis in cervical and uterine cancers by diffusion‐weighted magnetic resonance imaging at 3T

To evaluate diffusion-weighted imaging (DWI) for detection of pelvic lymph node metastasis in patients with cervical and uterine cancers. Fifty patients scheduled for pelvic lymph node dissection were enrolled for 3T magnetic resonance imaging (MRI) using a single-shot echo-planar DWI technique, body-phased array coil, b = 0, 1000 s/mm(2). We measured short/long-axis diameters, mean apparent diffusion coefficient (ADC) values of all identifiable nodes, relative ADC values between tumors and nodes, and utilized their cutoff values to validate the diagnostic accuracy internally. Histopathologic results served as the reference standard. The relative ADC values between tumor and nodes were significantly lower in metastatic than in benign nodes (0.06 vs. 0.21 x 10(-3) mm(2)/s, P < 0.001; cutoff value 0.10 x 10(-3) mm(2)/s). Compared to conventional MRI, the method combining size and relative ADC values resulted in better sensitivity (25% vs. 83%) and similar specificity (98% vs. 99%). The smallest metastatic lymph node detected by this method measured 5 mm on its short axis. The combination of size and relative ADC values was useful in detecting pelvic lymph node metastasis in patients with cervical and uterine cancers.

Prostate MR imaging at 3T with a longitudinal array endorectal surface coil and phased array body coil

To demonstrate the feasibility of using a double loop phased array endorectal coil combined with a phased array body coil to image the prostate at 3T. We designed and constructed a novel prostate coil employing two arrayed 4.0 x 5.0 cm loops, tuned the device for optimal performance at 3T, and characterized the signal-to-noise ratio (SNR) associated with it. The coil Q factor was calculated to be approximately 50 unloaded, and 30 when loaded on human tissue. SNR maps at multiple orientations were constructed and images were acquired on both a phantom and a human. As expected, SNR was highest along the midpoint of the array and demonstrated strong signal even at 4 cm from the coil. The double loop phased array endorectal coil combined with a phased array body coil at 3T is feasible in vivo and compelling enough to warrant future clinical trials to evaluate its efficacy. These trials are currently under way.

Pilot Study Evaluating Use of Lymphotrophic Nanoparticle-Enhanced Magnetic Resonance Imaging for Assessing Lymph Nodes in Renal Cell Cancer

To assess lymphotrophic nanoparticle-enhanced magnetic resonance imaging (LNMRI) in identifying malignant nodal involvement in patients with renal neoplasms. MRI was performed in 9 patients with renal masses. All patients were imaged on a GE 1.5T system with phased array body coil. Protocols included T2 and T2* weighted imaging before and after administration of ferumoxtran-10 (Combidex) for the evaluation of lymph node (LN) involvement. All 9 patients underwent nephrectomy. Lymph node dissection (LND) was performed in patients with stage 2 renal cell cancer (RCC), or transitional cell cancer (TCC), per routine clinical practice. Data analysis was performed by 2 radiologists, who were blinded to pathologic results. Nodes that lacked contrast uptake were deemed malignant, and those with homogeneous uptake were deemed benign. Quantitative, retrospective analysis was performed on primary tumors by quantifying T2* with a monoexponential fitting algorithm (Osirix). T2* was quantified before, immediately after, and 24 hours after the administration of ferumoxtran-10. MRI demonstrated 26 lymph nodes within the 9 patients imaged (24 benign and 2 malignant). Pathologic results allowed comparison in 22 of the 26 lymph nodes and demonstrated high sensitivity (100%) and specificity (95.7%). LNMRI demonstrated high sensitivity (100%) and specificity (95.7%) in patients with renal neoplasms. Although in a relatively small sample size, the results are encouraging and warrant a larger, prospective trial.

Prostate Cancer: Added Value of Subtraction Dynamic Imaging in 3T Magnetic Resonance Imaging with a Phased-array Body Coil

PurposeTo determine the added value of dynamic subtraction magnetic resonance (MR) imaging for the localization of prostate cancer.Materials and MethodsWe examined 21 consecutive patients who underwent MR imaging in 3T unit with a phased-array body coil and then had radical prostatectomy. After T2-weighted fast spin-echo imaging, we performed a contrast-enhanced dynamic 3D gradient-echo imaging consisting of pre-contrast, 2 successive early-phased (first imaging was started just after the appearance of contrast material in the aortic bifurcation followed by second imaging 35 seconds after the initiation of first imaging) and one 5-minute delayed post-contrast series. Subtraction of pre-contrast images from corresponding post-contrast images of each phase was performed on the console.ResultsOn ROC analysis, the overall accuracy (Az value) of dynamic imaging combined with subtraction imaging was higher than T2-weighted imaging (p = 0.001) or conventional dynamic imaging alone (p = 0.074) for localization of cancer foci regardless of their zonal locations. Among pathologically verified 81 lesions, the mean volume of detected lesions with the subtraction images (n = 49, 0.69 cm3) was smaller than with T2-weighted images (n = 14, 1.05 cm3) or conventional dynamic images (n = 43, 0.71 cm3).ConclusionFor localization of small prostate cancer, additional subtraction for the dynamic imaging could be superior to both T2-weighted imaging and un-subtracted dynamic imaging.

Prostatakarzinom - Diagnostik und Staging

Prostate cancer is the most common malignancy of men in Germany. Transrectal ultrasound (TRUS) is the primary used imaging modality. Patients with elevated PSA levels undergo systematic TRUS-guided transrectal biopsy of the prostate for histologic confirmation of prostate cancer. Magnetic resonance imaging (MRI) using the combined endorectal body phased-array coil may be indicated in men with one or more negative prostate biopsies. The detection of prostate cancer by conventional MRI can be improved by an additional dynamic contrast-enhanced MR study and proton MR spectroscopy. Local staging of prostate cancer by MRI is more accurate compared with digital rectal examination and transrectal ultrasound. However, accuracies reported in the literature for these procedures vary widely. Bone scintigraphy with 99m Tc-bisphosphonate is currently the method of choice for the detection of bone metastases. However, more recent techniques such as whole-body MRI and PET using 18 F-FDG, 11 C-choline or 11 C-acetate as tracers were found to have higher sensitivities.

Dynamic MR imaging of the gastroesophageal junction in healthy volunteers during bolus passage

To evaluate the feasibility of noninvasive dynamic fast magnetic resonance imaging (MRI) during swallowing in healthy volunteers, and to determine esophageal function at the gastroesophageal junction during swallowing. A total of 20 healthy volunteers underwent MRI while swallowing in the supine position. Dynamic gradient-echo (GRE) sequences (balanced fast field echo [B-FFE]) were employed in three planes on a 1.5T unit using a phased-array body coil. Buttermilk spiked with gadolinium (Gd) chelate (40:1) for bolus passage was used as an oral contrast agent. We evaluated visualization of esophageal bolus transit, bolus transit time (BTT), peristalsis, identification of the gastroesophageal junction, and reflux during the Valsalva maneuver. The mean visible length of the esophagus was 16.2+/-5.3 cm in the sagittal view, and 13.8+/-4.9 cm in the coronal view. In the sagittal view the BTT was defined in 15 of 20 volunteers and was 7.6+/-1.4 seconds. The BTT in the coronal view was measured in seven of 20 volunteers and was 8+/-1.3 seconds on average. The axial view yielded higher scores (2.25) than the coronal (1.98) and sagittal (1.78) views for identification of the cardia and during the Valsalva maneuver. Bolus contrast was better displayed in the sagittal (2.2) view than in the coronal (2.08) or axial (1.73) planes. In six volunteers, gastroesophageal abnormalities, such as axial hernia, reflux, and nonperistaltic contractions, were identified. For statistical analysis we used the Friedman test and a one-way analysis of variance (ANOVA). The results indicate that dynamic MR swallowing is a feasible and reproducible technique that warrants further studies in patients.

Assessment of normal fetal brain maturation in utero by proton magnetic resonance spectroscopy

Cerebral maturation in the normal human fetal brain was investigated by in utero localized proton MR spectroscopy ((1)H MRS). Fifty-eight subjects at 22-39 weeks of gestational age (GA) were explored. A combination of anterior body phased-array coils (four elements) and posterior spinal coils (two to three elements) was used. Four sequences were performed (point-resolved spectroscopy (PRESS) sequence with short and long TEs (30 and 135 ms), with and without water saturation). A significant reduction in myo-inositol (myo-Ins) and choline (Cho) levels, and an increase in N-acetylaspartate (NAA) and creatine (Cr) content were observed with progressing age. A new finding is the detection of NAA as early as 22 weeks of GA. This result is probably related to the fact that oligodendrocytes (whether mature or not) express NAA, as demonstrated by in vitro studies. Cho and myo-inositol were the predominant resonances from 22 to 30 weeks and decreased gradually, probably reflecting the variations in substrate needed for membrane synthesis and myelination. The normal MRS data for the second trimester of gestation (when fetal MRI is usually performed) reported here can help determine whether brain metabolism is altered or not, especially when subtle anatomic changes are observed on conventional images.

Magnetic resonance imaging measurement of the anorectal striated muscle complex in normal children

Purpose The aim of the study was to describe and establish a normal measurement of the striated muscle complex (SMC) in healthy children using body phased-array or head coil magnetic resonance imaging. Methods Imaging was performed in 20 boys and 20 girls (age range, from 3 months to 14 years; average age, 3.2 years) without anorectal disorders. The dimensions of the puborectalis muscle (PR) and external anal sphincter (EAS) were measured in different planes. Results There was a close positive correlation between absolute width and length of SMC and age ( P < .05), whereas there was no correlation between the relative width and length of SMC and age ( P > .05). Normal relative length of the PR and EAS were measured as 0.47 ± 0.04 and 0.41 ± 0.04, respectively, and the normal relative width of PR and posterior EAS were 0.50 ± 0.04 and 0.44 ± 0.04 in children younger than 14 years. Conclusions The width and length of PR and EAS increase progressively with age. The relative width and length of PR and EAS were not variable with age. A relative width and length of PR and EAS were chosen as objective criteria for normal SMC in children younger than 14 years.

Prostate Cancer Evaluated with Ferumoxtran-10–enhanced T2*-weighted MR Imaging at 1.5 and 3.0 T: Early Experience

To prospectively evaluate the feasibility of ferumoxtran-10-enhanced magnetic resonance (MR) imaging at high magnetic field strength (3.0 T) and to compare image quality between 1.5- and 3.0-T MR imaging in terms of lymph node detection in patients with prostate cancer. This study was institutional review board approved, and all patients gave written informed consent. Forty-eight consecutive patients aged 51-79 years (mean, 65.5 years) with prostate cancer were enrolled. T2*-weighted 1.5- and 3.0-T MR images of the pelvis were acquired in a sagittal plane parallel to the psoas muscle 24 hours after ferumoxtran-10 administration. A pelvic and body phased-array coil was used and yielded an in-plane resolution of 0.56 x 0.56 x 3.00 mm at 1.5 T and 0.50 x 0.50 x 2.50 mm at 3.0 T. All images were evaluated by three readers for total image quality, lymph node border delineation, muscle-fat contrast, and vessel-fat contrast. Statistical significance was calculated by using the Mann-Whitney U test. Subsequently, the general linear mixed model was used to estimate the contributions of three factors-patient, reader, and technique-to the variability of the imaging results. Significantly (P < .05) better muscle-fat contrast, vessel-fat contrast, lymph node border delineation, and total image quality were observed at 3.0-T MR imaging. The general linear mixed model revealed that the variability of all results could be attributed to the use of 3.0-T imaging. Ferumoxtran-10-enhanced MR imaging can be performed at high magnetic field strengths and result in improved image quality, which may lead to improved detection of small positive lymph nodes.

Total-body MR-imaging in oncology

Although MRI is an effective modality in oncology, state-of-the-art total-body MRI (TB-MRI) in the past was infeasible in the diagnostic work-up, due to the need for repeated examinations with repositioning and separate surface coils to cover all body parts. To overcome this limitation, either a moving table platform in combination with the body-coil or a special designed rolling table platform with one body phased-array coil have been implemented with promising results for both tumor staging and metastases screening. Since 2004, state-of-the-art TB-MR imaging with high spatial resolution has become feasible using a newly developed 1.5 Tesla TB-MRI system with multiple receiver channels. This review gives an overview based on the recent literature as well as our own experience concerning the possibilities, challenges, and limitations of TB-MRI in oncology, emphasizing both oncological staging and early tumor detection in asymptomatic subjects.

CINE-MRT des Thorax bei Patienten mit Pectus excavatum

Morphologic and dynamic assessment of respiratory chest kinetics was performed in patients with pectus excavatum deformity (PE) using dynamic MRI: cine MRI. Seven consecutive patients with PE (aged 20.3 years+/-4.0) and ten healthy volunteers of comparable age underwent real-time cine MRI of the chest during breathing on a 1.5 T MR scanner (Magnetom Sonata, Siemens Medical Systems, Erlangen, Germany) using a standard phased array body coil and a half-Fourier single-shot turbo spin echo sequence (HASTE) for dynamic imaging. During deep inspiration and expiration, single-shot sequences were performed in one slice level over 20 s at a frequency of 1 image/s covering the entire thoracic cage in three orientations. Morphology and chest kinetics in patients with PE were analyzed and compared with normal values, and typical patterns of chest kinetics were noted. Three different types of chest morphology in PE were identified: (1) the generally flattened thoracic cage, (2) the "tilted" sternum, and (3) the focally deepened sternum. Three patterns of motion correspond to these morphological types: (1) elevation of the sternum and the anterior thoracic wall, (2) angulated elevation of the parasternal rib cage with persistent deepening of the sternum resembling a "wing beat" movement, and (3) increased diaphragmatic movements with limited chest wall dynamics. Cine MRI is an adequate radiation-free diagnostic modality for the dynamic imaging of both chest morphology and chest wall kinetics in patients with PE. The pectus severity index can easily be determined and three typical movement patterns of chest wall kinetics identified.

Dynamic MR urography in urinary tract obstruction: implementation and preliminary results

Recent studies have demonstrated magnetic resonance (MR) capabilities in evaluating renal morphology and function in patients with urinary obstruction. The objective of this report is to support the introduction of dynamic MR renography on any MR equipment. A custom-made device of vials filled with different concentrations of gadolinium was studied by combinations of T1-weighted gradient-echo sequences and coils. We compared the capabilities of two coils (phased array vs. standard body), the properties of dynamic sequences, and the effects of increasing concentrations of gadolinium on signal intensity. In a second section, we designed MR urography plug-ins of Image J (DICOM image software) for the analysis of dynamic studies. Optimized gradient-echo sequences acquired with a phased array body coil produced acceptable quality images with a linear relation between signal intensity and the lowest concentrations of gadolinium. In vitro measurements showed loss of linearity above 8 mmol/L. Theoretical calculation and data from the literature suggest that the gadolinium dose to the patient should not exceed one-fourth of the usual one (0.025 mmol/kg). Postprocessing using Image J software and the specifically designed plug-ins was validated. The collection of plug-ins is now available on the Internet.

Prostate biopsy in the supine position in a standard 1.5-T scanner under real time MR-imaging control using a MR-compatible endorectal biopsy device

Thirty-seven consecutive patients with elevated PSA levels and negative tumor prostate biopsies underwent a MR-guided prostate biopsy in a 1.5-T scanner in the supine position. After localization of suspected tumor areas using an endorectal coil and two body-phased array coils, the biopsy device was positioned without any repositioning of the patient. The biopsy device consisted of a mount, a ball joint, a positioning stage and an insertion stage with a needle guide, which was filled with a MR-visible fluid to control positioning of the needle using a balanced steady-state free precession sequence (TrueFISP) and a high-resolution turbo spin echo (T2-TSE) sequence. Core biopsies were taken manually in the magnet. The biopsy needle could be correctly positioned in all cases. Suspected lesions with a diameter > or =10 mm could be successfully punctured. Four to nine (mean = 6) biopsies were taken per patient. In 14 patients, prostate cancer was confirmed at histology. Twenty-four biopsies positive for cancer were performed in 14 patients. A correct correlation was found between the site of biopsy and histology. MR-guided prostate biopsy can be effective in increasing primary positive tumor biopsy results in patients with a history of negative tumor TRUS-guided prostate biopsies.

MRS of normal and impaired fetal brain development

Cerebral maturation in the human fetal brain was investigated by in utero localized proton magnetic resonance spectroscopy (MRS). Spectra were acquired on a clinical MR system operating at 1.5 T. Body phased array coils (four coils) were used in combination with spinal coils (two coils). The size of the nominal volume of interest (VOI) was 4.5 cm 3 (20 mm × 15 mm × 15 mm). The MRS acquisitions were performed using a spin echo sequence at short and long echo times (TE = 30 ms and 135 ms) with a VOI located within the cerebral hemisphere at the level of the centrum semiovale. A significant reduction in myo-inositol and choline and an increase in N-acetylaspartate were observed with progressive age. The normal MR spectroscopy data reported here will help to determine whether brain metabolism is altered, especially when subtle anatomic changes are observed on conventional images. Some examples of impaired fetal brain development studied by MRS are illustrated.