Thierry Metens

Present and potential future issues in glioblastoma treatment

The treatment of glioblastomas requires a multidisciplinary approach that takes the presently incurable nature of the disease into consideration. Treatments are multimodal and include surgery, radiotherapy and chemotherapy. Current recommendations are that patients with glioblastomas should undergo maximum surgical resection, followed by concurrent radiation and chemotherapy with the novel alkylating drug temozolomide. This is then to be followed by additional adjuvant temozolomide for a period of up to 6 months. Major advances in surgical and imaging technologies used to treat glioblastoma patients are described. These technologies include magnetic resonance imaging and metabolic data that are helpful in the diagnosis and guiding of surgical resection. However, glioblastomas almost invariably recur near their initial sites. Disease progression usually occurs within 6 months and leads rapidly to death. A number of signaling pathways can be activated constitutively in migrating glioma cells, thus rendering these cells resistant to proapoptotic insults, such as conventional chemotherapies. Therefore, the molecular and cellular therapies and local drug delivery that could be used to complement conventional treatments are described, and some of the currently ongoing clinical trials are reviewed, with respect to these new approaches.

The role of MR imaging for the assessment of complicated duplex kidneys in children: preliminary report

Objective. To determine whether MR imaging, including MR urography, is able to assess complicated duplex kidneys and to determine the possible role of MRI compared to other imaging techniques in such uropathies. Material and methods. Twenty consecutive patients (age 1 month– 11 years) presenting with a suspicion of a complicated duplex kidney were prospectively studied with MRI and MR urography. The examinations were performed on a 0.5-T machine using routinely available sequences that were optimised to the patients age and size. MR images were reviewed separately by two observers blinded to the patient history. They were asked to assess the presence of a duplex kidney, the presence of an abnormality that may require surgery and to indicate the type of the inferior ureteric insertion. A qualitative gradation of these results was performed on the basis of the final diagnosis provided at endoscopy (n = 6) or surgery (n = 14). MR results were compared to those provided by US examinations and excretory urography, when available, and a non-parametric statistical analysis was performed. Results. MRI differentiated well between the upper and the lower poles of the kidneys and correctly answered the three questions in all 20 patients. The two observers agreed completely in all the 20 patients. MR was statistically superior to both US and excretory urography in the evaluation of the distal ureter (P < 0.05). Conclusions. MRI provides a precise assessment of the complications associated with duplex kidneys. Its optimal role seems to be the assessment of ectopic extra-vesical ureteric insertions and whenever an occult upper pole is suspected.

Apparent Diffusion Coefficient and Cerebral Blood Volume in Brain Gliomas: Relation to Tumor Cell Density and Tumor Microvessel Density Based on Stereotactic Biopsies

BACKGROUND AND PURPOSE: MR imaging–based apparent diffusion coefficient (ADC) and regional cerebral blood volume (rCBV) measurements have been related respectively to both cell and microvessel density in brain tumors. However, because of the high degree of heterogeneity in gliomas, a direct correlation between these MR imaging–based measurements and histopathologic features is required. The purpose of this study was to correlate regionally ADC and rCBV values with both cell and microvessel density in gliomas, by using coregistered MR imaging and stereotactic biopsies. MATERIALS AND METHODS: Eighteen patients (9 men, 9 women; age range, 19–78 years) with gliomas underwent diffusion-weighted and dynamic susceptibility contrast-enhanced MR imaging before biopsy. Eighty-one biopsy samples were obtained and categorized as peritumoral, infiltrated tissue, or bulk tumor, with quantification of cell and microvessel density. ADC and rCBV values were measured at biopsy sites and were normalized to contralateral white matter on corresponding maps coregistered with a 3D MR imaging dataset. ADC and rCBV ratios were compared with quantitative histologic features by using the Spearman correlation test. RESULTS: The highest correlations were found within bulk tumor samples between rCBV and cell density (r=0.57, P < .001) and rCBV and microvessel density (r=0.46, P < .01). An inverse correlation was found between ADC and microvessel density within bulk tumor (r=−0.36, P < .05), whereas no significant correlation was found between ADC and cell density. CONCLUSION: rCBV regionally correlates with both cell and microvessel density within gliomas, whereas no regional correlation was found between ADC and cell density.

Endometriosis: Contribution of 3.0-T Pelvic MR Imaging in Preoperative Assessment—Initial Results

PURPOSE To determine the accuracy of 3.0-T pelvic magnetic resonance (MR) imaging in the preoperative assessment of endometriosis and to evaluate colon wall involvement after intrarectal gel administration. MATERIALS AND METHODS Institutional review board approval for this study was obtained, and each patient gave written informed consent. Forty-one consecutive patients with clinical suspicion of endometriosis underwent pelvic MR imaging at 3.0 T before surgery. Single-shot and high-spatial-resolution axial T2-weighted, sagittal fat-suppressed T2-weighted, and axial fat-suppressed T1-weighted sequences were performed. T2-weighted sequences were repeated after the rectum was filled with ultrasonographic (US) gel. Two blinded readers interpreted images independently. Image quality was scored by using a four-point scale. Detailed mapping of deep endometriosis was performed. Colon wall infiltration was graded (none, serosa, muscularis, submucosa, mucosa). MR imaging results were compared with surgical and pathologic findings. Interobserver agreement was assessed by using kappa statistics. Nonparametric tests were performed to compare colon wall infiltration scores without and those with US gel and between observers. RESULTS Twenty-seven of 41 patients had deep endometriosis at surgery and histopathologic examination. Sensitivity, specificity, positive and negative predictive values, and accuracy for the diagnosis of deep endometriosis at MR imaging were 96.3% (26 of 27), 100% (14 of 14), 100% (26 of 26), 93.3% (14 of 15), and 97.6% (40 of 41), respectively. kappa Values ranged from 0.65 to 1.0, depending on the location of deep endometriosis. Colon wall infiltration assessment by both readers correlated well with pathologic findings (Spearman coefficient, >0.93), although median wall involvement scores were lower at pathologic examination than for both readers both before (P = .042 and P = .011) and after (P = .079 and P = .011) intrarectal gel filling. CONCLUSION MR imaging of the pelvis at 3.0 T is accurate in the diagnosis and staging of deep endometriosis for the preoperative assessment of patients clinically suspected of having endometriosis.

Combination of functional magnetic resonance imaging-guided neuronavigation and intraoperative cortical brain mapping improves targeting of motor cortex stimulation in neuropathic pain.

OBJECTIVE: To evaluate, regardless of the clinical results, the contribution of combining functional magnetic resonance imaging (fMRI) with intraoperative cortical brain mapping (iCM) as functional targeting methods for epidural chronic motor cortex stimulation (MCS) in refractory neuropathic pain. METHODS: Eighteen neuropathic pain patients (central stroke in six; trigeminal neuropathy in six; syrinx or amputation in six) who underwent operations for epidural MCS were studied with preoperative fMRI and iCM. fMRI investigated motor tasks of hands (as well as foot and tongue, when painful). fMRI data were analyzed with Statistical Parametric Mapping99 software (University College London, London, England; initial analysis threshold corresponding to P < 0.001), registered in a neuronavigation system, and correlated during surgery with iCM. The primary aim of this study was to improve the topographical precision of MCS. Matching of fMRI and iCM specifically was examined. RESULTS: Correspondence between the contour of the fMRI activation area and iCM in precentral gyrus (mean distance, 3.8 mm) was found in 17 (94%) of 18 patients. Eleven of them showed correspondence for more restrictive values of the analysis threshold (P < 0.0001); in six patients, the quality of the iCM was reduced by somatosensory wave attenuation and general anesthesia. In this group of six patients, a combination of both techniques was used for the final targeting. Correspondence was not found in one patient as the result of image distortion and residual motion artifact. At follow-up (4–60 mo), MCS induced significant pain relief in a total of 11 patients (61%). CONCLUSION: This study confirms the functional accuracy of fMRI guidance in neuropathic pain and illustrates the usefulness of combining fMRI guidance with iCM to improve the functional targeting in MCS. Because appropriate targeting is crucial to obtaining pain relief, this combination may increase the analgesic efficacy of MCS.

MR urography in children.

Thanks to the development of rapid sequences with better resolution, applications of uro MR have rapidly increased in children. Difficulties that remain are related to the variable ages of the patients. It is therefore mandatory to standardize as much as possible the techniques that are used in order to obtain reproducible results. In this review, the examination protocols will be explained. In a second part the current applications in children will be illustrated and discussed, especially in comparison with the other imaging techniques.

Magnetic resonance cholangiopancreatography: interest of IV secretin administration in the evaluation of pancreatic ducts

Abstract. The aim of this study was to investigate whether IV secretin administration is useful to enhance the delineation of the main pancreatic duct (MPD) and its side branches, and if it provides additional information concerning signal voids and strictures. Twenty-seven patients referred for abdominal pain or laboratory abnormalities (group 1, n = 13) or for the follow-up of chronic pancreatitis (CP; group 2, n = 14) were studied. Magnetic resonance cholangiopancreatography was acquired at 1.5 T before and after IV secretin by a coronal 3D TSE T2-weighted sequence with maximum intensity projection postprocessing. In group 1 secretin provided a better visualization of MPD in 9 patients. In a patient with pancreas divisum, it allowed suggestion of stenosis of the accessory papilla, confirmed at endoscopic retrograde cholangiopancreatography (ERCP). In group 2 secretin provided a better visualization of MPD only in the 3 patients with mild disease. A mild dilation upstream a stricture occurred in 2 cases and a marked dilation appeared upstream a wallstent which was non-patent at ERCP. Few changes were noticed concerning side branches. These preliminary results indicate that in patients without CP, secretin improves MPD delineation avoiding invasive diagnostic ERCP. In patients with mild CP secretin does not improve the characterization of signal voids, but it may be useful to appreciate their significance and to follow-up stenosis.

Structural asymmetries in motor and language networks in a population of healthy preterm neonates at term equivalent age: A diffusion tensor imaging and probabilistic tractography study

In this MRI study, we aimed to provide new in vivo structural markers of asymmetry in motor and language networks in a population of healthy preterm neonates scanned at term equivalent age. Using diffusion tensor imaging and probabilistic tractography, we showed that, besides volume and microstructural asymmetries in the parieto-temporal part of the superior longitudinal fasciculus (SLF) and a trend towards microstructural asymmetry in the corticospinal tract (CST), volume asymmetry in the motor part of the superior thalamic radiations (STR) and a trend towards volume asymmetry in the CST are already present in the neonatal period. No asymmetry was found in the sensory part of the STR, the anterior thalamic radiations (ATR), and posterior thalamic radiations (PTR) neither in the fronto-parietal part of the SLF. These results suggest that structural asymmetries in the motor and language networks are present in healthy preterm neonates at term equivalent age, well before the development of speech and hand preference.

Tumoral and Nontumoral Pancreas: Correlation between Quantitative Dynamic Contrast-enhanced MR Imaging and Histopathologic Parameters

PURPOSE To prospectively determine whether dynamic contrast material-enhanced (DCE) magnetic resonance (MR) quantitative parameters correlate with fibrosis and microvascular density (MVD) in malignant and benign solid pancreatic focal lesions and nontumoral pancreatic tissue. MATERIALS AND METHODS The institutional review board approved the study; written informed consent was obtained. DCE MR was performed in 28 patients with surgically resectable focal pancreatic lesions. DCE MR quantitative parameters derived from one-compartment (OC) (transfer rate constant [K(trans)] and distribution fraction [ƒ]) and two-compartment (TC) (K(trans), tissue volume fraction occupied by extravascular extracellular space [v(i)], and tissue volume fraction occupied by vascular space [v(p)]) pharmacokinetic models were correlated with fibrosis content and MVD counts in focal lesions and nontumoral tissue (Spearman correlation coefficient [SCC]). Pharmacokinetic parameters were compared (Mann-Whitney test) between tumoral and nontumoral tissue. Diagnostic performance of DCE MR fibrosis detection was assessed (receiver operator characteristic curve analysis). RESULTS K(trans) OC and K(trans) TC were significantly lower in primary malignant tumors compared with benign lesions (P = .023) and nontumoral pancreatic tissue downstream (P < .001) and upstream (P = .006); ƒ and v(i) were significantly higher in primary malignant tumors compared with nontumoral pancreatic tissue downstream (P = .012 and .018, respectively). Fibrosis was correlated negatively with K(trans) OC (SCC, -0.600) and K(trans) TC (SCC, -0.564) and positively with ƒ (SCC, 0.514) and v(i) (SCC, 0.464), with P < .001 (all comparisons). MVD was positively correlated with ƒ (SCC, 0.355; P = .019) and v(i) (SCC, 0.297; P = .038) but not with K(trans) OC (SCC, -0.140; P = .33) and K(trans) TC (SCC, -0.194; P = .181). Sensitivity and specificity for fibrosis detection were 65% (24 of 37) and 83% (10 of 12) for K(trans) OC (cutoff value, 0.35 min(-1)) and 76% (28 of 37) and 83% (10 of 12) for K(trans) TC (cutoff value, 0.29 min(-1)), respectively. CONCLUSION Quantitative DCE MR parameters, derived from pharmacokinetic models in malignant and benign pancreatic solid lesions and nontumoral pancreatic tissue, were significantly correlated with fibrosis and MVD. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11103515/-/DC1.

Pancreatic perfusion: noninvasive quantitative assessment with dynamic contrast-enhanced MR imaging without and with secretin stimulation in healthy volunteers--initial results.

PURPOSE To prospectively quantify pancreatic regional perfusion with dynamic contrast material-enhanced magnetic resonance (MR) imaging by using a one-compartment model and to assess perfusion changes during secretin stimulation in healthy volunteers. MATERIALS AND METHODS The study had institutional review board approval, and written informed consent was obtained. Ten healthy volunteers (five men, five women; mean age, 24.7 years +/- 1.9 [standard deviation]; range, 22-29 years) underwent MR imaging pancreatic perfusion studies performed twice without secretin and twice during secretin stimulation. Dynamic contrast-enhanced MR imaging consisted of saturation-recovery T1-weighted turbo-field-echo imaging with peripheral pulse triggering and respiratory tracking. A dose of 0.05 mmol gadodiamide per kilogram of body weight was injected at a rate of 3.5 mL/sec. Regional perfusion parameters were fitted with a one-compartment model. The analysis of variance test for repeated measurements was used to assess differences in pancreatic perfusion without and that with secretin administration. RESULTS Significant differences in perfusion parameters between the three pancreatic regions were observed (P < .05). During secretin stimulation, a significant difference was observed only between the body and the tail of the pancreas (P = .02). A significant increase (P = .003) in pancreatic perfusion was observed after secretin administration. Mean pancreatic perfusion was 184 mL/min/100 g of tissue +/- 71, 207 mL/min/100 g +/- 77, and 230 mL/min/100 g +/- 87 without secretin and 342 mL/min/100 g +/- 154, 338 mL/min/100 g +/- 156, and 373 mL/min/100 g +/- 176 after secretin stimulation in the head, body, and tail of the pancreas, respectively. Intraindividual variability was 21% without secretin stimulation and 46% with secretin stimulation. CONCLUSION Dynamic contrast-enhanced MR imaging enables noninvasive quantification of regional pancreatic perfusion in resting conditions and demonstrates the increase in pancreatic perfusion during secretin stimulation in healthy subjects.