Mathematical modeling of metabolism and hemodynamics.

We provide a mathematical study of a model of energy metabolism and hemodynamics of glioma allowing a better understanding of metabolic modifications leading to anaplastic transformation from low grade glioma. This mathematical analysis allows ultimately to unveil the solution to a viability problem which seems quite pertinent for applications to medecine.

Predicting the outcome of grade II glioma treated with temozolomide using proton magnetic resonance spectroscopy.

BACKGROUND: This study was designed to evaluate proton magnetic resonance spectroscopy ((1)H-MRS) for monitoring the WHO grade II glioma (low-grade glioma (LGG)) treated with temozolomide (TMZ). METHODS: This prospective study included adult patients with progressive LGG that was confirmed by magnetic resonance imaging (MRI). Temozolomide was administered at every 28 days. Response to TMZ was evaluated by monthly MRI examinations that included MRI with volumetric calculations and (1)H-MRS for assessing Cho/Cr and Cho/NAA ratios. Univariate, multivariate and receiver-operating characteristic statistical analyses were performed on the results. RESULTS: A total of 21 LGGs from 31 patients were included in the study, and followed for at least n=14 months during treatment. A total of 18 (86%) patients experienced a decrease in tumour volume with a greater decrease of metabolic ratios. Subsequently, five (28%) of these tumours resumed growth despite the continuation of TMZ administration with an earlier increase of metabolic ratios of 2 months. Three (14%) patients did not show any volume or metabolic change. The evolutions of the metabolic ratios, mean(Cho/Cr)(n) and mean(Cho/NAA)(n), were significantly correlated over time (Spearman ρ=+0.95) and followed a logarithmic regression (P>0.001). The evolutions over time of metabolic ratios, mean(Cho/Cr)(n) and mean(Cho/NAA)(n), were significantly correlated with the evolution of the mean relative decrease of tumour volume, mean(ΔV(n)/V(o)), according to a linear regression (P<0.001) in the 'response/no relapse' patient group, and with the evolution of the mean tumour volume (meanV(n)), according to an exponential regression (P<0.001) in the 'response/relapse' patient group. The mean relative decrease of metabolic ratio, mean(Δ(Cho/Cr)(n)/(Cho/Cr)(o)), at n=3 months was predictive of tumour response over the 14 months of follow-up. The mean relative change between metabolic ratios, mean((Cho/NAA)(n)-(Cho/Cr)(n))/(Cho/NAA)(n), at n=4 months was predictive of tumour relapse with a significant cutoff of 0.046, a sensitivity of 60% and a specificity of 100% (P=0.004). CONCLUSIONS: The (1)H-MRS profile changes more widely and rapidly than tumour volume during the response and relapse phases, and represents an early predictive factor of outcome over 14 months of follow-up. Thus, (1)H-MRS may be a promising, non-invasive tool for predicting and monitoring the clinical response to TMZ.

[Multimodal magnetic resonance imaging of brain tumors]. / Imagerie multimodale par résonance magnétique des tumeurs cérébrales.

Magnetic resonance imaging arose as a reference for diagnosis, pre-therapeutic and follow-up of brain tumors. Among parameters obtained from standard MRI (of low specificity), only volumetric growth allows prognostic information. The multiple "advanced" sequences have leaded to increase both sensitivity and specificity of brain MRI. Yet, perfusion-weighted imaging and spectroscopy provide metabolic information, and diffusion tensor imaging and cortical activation provide functional information. Characterization, grading, therapeutic management and follow-up have improved, with prognostic information.

A comparative study of perfusion measurement in brain tumours at 3 Tesla MR: Arterial spin labeling versus dynamic susceptibility contrast-enhanced MRI.

PURPOSE: To prove the feasibility of arterial spin labeling (ASL) to explore brain tumors by comparing dynamic susceptibility contrast-enhanced MRI to ASL at 3T MR. MATERIALS AND METHODS: Twenty-seven patients were included presenting 9 gliomas, 10 metastases and 8 meningiomas. All were explored by a pseudo-continuous ASL and dynamic susceptibility contrast-enhanced T2* perfusion sequence. Two neuroradiologists analyzed the cerebral blood flow (CBF) maps to assess feasibility, examination quality and quantitative comparison. The Spearman nonparametric correlation test and the Bland-Altman graphic test were used to analyze our quantitative results. RESULTS: 92% of ASL CBF maps were informative. ASL detected all lesions as well as dynamic susceptibility contrast-enhanced MRI. Both sequences provide relative quantitative CBF values closely correlated. CONCLUSION: On a 3T MR unit, ASL is a good alternative to dynamic susceptibility contrast-enhanced MRI when contrast medium is contraindicated or intravenous injection is not possible. Its results on relative CBF parameters are similar to contrast-injected perfusion.

[Bithalamic infarct: is there an evocative aspect? Radioclinical study]. / Accident vasculaire ischémique bithalamique: existe-t-il un tableau évocateur ? Etude radioclinique.

INTRODUCTION: Bithalamic paramedian infarcts are uncommon. This stroke results in a complex clinical syndrome. CASE REPORT: We report four cases of bithalamic paramedian infarcts with a presumed mechanism of occlusion of a single thalamic paramedian artery. DISCUSSION: This normal anatomic variant corresponds to an asymmetrical common trunk for the two thalamosubthalamic paramedian arteries arising from a P1 segment (type IIb in the G. Percheron classification dating from 1977). A literature analysis (from 1985 to 2006) allowed us to identify the most widely reported clinical signs. Four main clinical findings are described: vertical gaze palsy (65%), memory impairment (58%), confusion (53%) and coma (42%). We also found these symptoms in our patients but rarely associated; however, all four patients had exhibited episodes of drowsiness. In this article, we discuss the anatomy-function correlation responsible for such clinical variability. CONCLUSION: Clinicians should be aware of this diagnosis to better understand the imaging results which provide confirmation. Although the literature describes frequently severe consciousness disorders such as coma, this diagnosis must also be considered in patients presenting a simple fluctuation of consciousness, e.g. hypersomnia.

Dynamic contrast-enhanced T2*-weighted MR imaging: a peritumoral brain oedema study.

BACKGROUND AND PURPOSE: Glioma and meningioma are the two most common types of primary brain tumor. The aim of the present study was to analyze, using dynamic susceptibility contrast MR perfusion imaging, the effect of angiogenesis on peritumoral tissue. METHODS: In this prospective study, conducted from December 2003 to March 2005, out of 18 patients recruited, 12 were included (six with meningioma, six with glioblastoma). Using rates of maximum signal drop (MSD), we drew regions of interest (ROI) starting near the lesion, and gradually moving outwards to areas of distant edema in axial and sagittal planes at 10, 20 and 30 mm from the tumor. We also drew ROI on the contralateral brain white matter to obtain a normal baseline for comparison (relative MSD; rMSD). RESULTS: In regions of peritumoral T2 hypersignals, we observed a decrease in rMSD with distance from glioblastoma due to reduced angiogenesis, and an increase in rMSD with distance from meningioma, probably due to a reduced mass effect. CONCLUSION: In our study, dynamic susceptibility contrast MR perfusion imaging, using MSD as a parameter, revealed differences between meningioma and glioblastoma peritumoral tissue due to changes in angiogenesis.

[Acute CSF changes in the mesencephalon aqueduct after subarachnoid hemorrhage as measured by PC-MRI]. / Caractérisation des perturbations du flux de LCS dans l'aqueduc du mésencéphale par IRM-CP à la phase aiguë de l'hémorragie méningée.

PURPOSE: Determining acute intracranial hydrodynamic changes after subarachnoid hemorrhage through an analysis of the CSF stroke volume (SV) as measured by phase-contrast MRI (PC-MRI) in the mesencephalon aqueduct. METHOD: A prospective study was performed in 33 patients with subarachnoid hemorrhage. A PC-MRI imaging study was performed n the acute phase (< 48 hours). CSF flow was measured in the aqueduct. The appearance of acute hydrocephalus (HCA) was then compared with data on CSF flow, and the location of the intraventricular and perimesencephalic bleeding. RESULTS: CSF analysis was performed on 27 patients, 11 of whom presented with an acute HCA. All 11 patients had an abnormal SV in the aqueduct: patients with a communicating HCA had an increased SV (n=8); and patients with a noncommunicating HCA had a nil SV (n=3). Patients with a normal SV in the aqueduct did not develop an acute HCA. Intraventricular bleeding significantly led to HCA (P=0.02), which was of the communicating type in 70% of cases. CONCLUSION: Subarachnoid hemorrhage leads to intracranial CSF hydrodynamic modifications in the aqueduct in the majority of patients. CSF flow can help us to understand the mechanism of the appearance of acute HCA. Indeed, hydrocephalus occurred - of the communicating type in most cases - even in the presence of intraventricular bleeding.

[Clinical interest of fMRI and functional exploration methods of brain activity and interactivity: physical and neurophysiological considerations]. / Intérêt clinique de l'IRMf et des méthodes d'exploration fonctionnelle de l'activité et de l'interactivité cérébrales : considérations physiques et neurophysiologiques.

After having provided a brief reminder of the principle of the blood oxygen level-dependent (BOLD) contrast effect, the physiological bases of brain activity and the concepts of functional integration and effective connectivity, we describe the most recent approaches, which permit to explore brain activity and putative networks of interconnected active areas in order to examine the normal brain physiology and its dysfunctions. We present various methods and studies of brain activity analysis clinically applicable, and we detail the concepts of functional and effective connectivity, which allow to study the cerebral plasticity which occurs at the child's during the maturation (e.g., dyslexia), at the adult during the ageing (e.g., Alzheimer disease), or still in schizophrenia or Parkinson disease. The study of specific circuits in networks has to allow defining in a more realistic way the dynamic of the central nervous system, which underlies various cerebral functions, both in physiological and pathological conditions. This connectivity approach should improve the diagnostic and facilitate the development of new therapeutic strategies.

Added Value of Spectroscopy to Perfusion MRI in the Differential Diagnostic Performance of Common Malignant Brain Tumors.

BACKGROUND AND PURPOSE: Perfusion and spectroscopic MR imaging provide noninvasive physiologic and metabolic characterization of tissues, which can help in differentiating brain tumors. We investigated the diagnostic role of perfusion and spectroscopic MR imaging using individual and combined classifiers of these modalities and assessed the added performance value that spectroscopy can provide to perfusion using optimal combined classifiers that have the highest differential diagnostic performance to discriminate lymphomas, glioblastomas, and metastases. MATERIALS AND METHODS: From January 2013 to January 2016, fifty-five consecutive patients with histopathologically proved lymphomas, glioblastomas, and metastases were included after undergoing MR imaging. The perfusion parameters (maximum relative CBV, maximum percentage of signal intensity recovery) and spectroscopic concentration ratios (lactate/Cr, Cho/NAA, Cho/Cr, and lipids/Cr) were analyzed individually and in optimal combinations. Differences among tumor groups, differential diagnostic performance, and differences in discriminatory performance of models with quantification of the added performance value of spectroscopy to perfusion were tested using 1-way ANOVA models, receiver operating characteristic analysis, and comparisons between receiver operating characteristic analysis curves using a bivariate χ2, respectively. RESULTS: The highest differential diagnostic performance was obtained with the following combined classifiers: maximum percentage of signal intensity recovery-Cho/NAA to discriminate lymphomas from glioblastomas and metastases, significantly increasing the sensitivity from 82.1% to 95.7%; relative CBV-Cho/NAA to discriminate glioblastomas from lymphomas and metastases, significantly increasing the specificity from 92.7% to 100%; and maximum percentage of signal intensity recovery-lactate/Cr and maximum percentage of signal intensity recovery-Cho/Cr to discriminate metastases from lymphomas and glioblastomas, significantly increasing the specificity from 83.3% to 97.0% and 100%, respectively. CONCLUSIONS: Spectroscopy yielded an added performance value to perfusion using optimal combined classifiers of these modalities, significantly increasing the differential diagnostic performances for these common brain tumors.

Osteoblastic and mixed spinal metastases: evaluation of the analgesic efficacy of percutaneous vertebroplasty.

PURPOSE: To determine the analgesic efficacy of percutaneous vertebroplasty in treating osteoblastic and mixed spinal metastases. MATERIALS AND METHODS: Fifty-two patients underwent 59 vertebroplasty procedures for 103 painful vertebral metastases, among which 53 were pure osteoblastic and 50 were mixed (blastic and lytic). Analgesic efficacy was classified as "excellent," "good," "fair," and "poor." The patients were followed up at 1 month, 6 months, 12 months, 2 years, and 5 years. The mean follow-up period was 17 months. RESULTS: The analgesic efficacy rate was 86% at 1 month and 92% at 6 months (among which 71% of patients had "excellent" results and 21% had with "good" results). In most cases, it was stable. It was correlated with vertebral filling quality (Fisher test, P = .0932 at 1 month follow-up) but neither with filling volume (Mann-Whitney test, P = .143 at 1 month) nor with the vertebral structure, pure blastic or mixed (Fisher test, P = .784 at 1 month). There were 5 filling failures (4.7%) whose occurrence was correlated with the pure blastic structure of the vertebra (Mann-Whitney test, P = .033). Local clinical complications were observed in 5 cases (8.5%): 1 transitory radiculalgia (1.7%), 2 durable radiculalgias (3.4%), 1 cauda equina syndrome (1.7%), and 1 hemothorax (1.7%). General clinical complications were 2 pulmonary embolisms (3.4%). No patients died. The occurrence of clinical complications was not correlated with the vertebral structure (Fisher test, P = .279). CONCLUSION: Vertebroplasty for osteoblastic and mixed metastases allows, with a well-trained operator, a satisfactory anesthesia with acceptable clinical complication rates.

[Contribution of the spectral analysis to the brain connectivity study by fMRI]. / Apport de l'analyse spectrale à l'étude de la connectivité cérébrale en IRMf Dissociation fonctionnelle de l'aire motrice supplémentaire.

AIM: To validate, through functional magnetic resonance imaging (fMRI) from spectral analysis of time series during a visuomotor task, a model of functional connectivity mainly constituted by the pre-supplementary motor area (pre-SMA), the supplementary motor area proper (SMA-proper) and the primary motor cortex (M1). MATERIALS AND METHODS: The paradigm that was tried out in young subjects (n=5) consisted of a preparation task of motor movement. We firstly proceeded with an estimate in the frequency domain of coherency coefficients and values of phase shift between these three areas. Secondly, the estimated coherency coefficients were integrated to a model of functional connectivity. Two interaction coefficients were calculated, one for the related M1 and pre-SMA regions, the other one for the related M1 and SMA-proper regions. RESULTS AND CONCLUSION: Our results demonstrate hemodynamic activity that definitely occurred earlier in the pre-SMA area during the preparatory period of the task. In the same way, a more important interaction was found between M1 and pre-SMA areas, which corroborates the assumption of the prevalent role played by these two areas in the case of a preparation task of a motor movement. Thus, this study has allowed highlighting a functional dissociation between the two portions of the SMA.

Spine metastasis imaging: review of the literature.

Any malignant neoplasm possesses the capacity to metastasize to the musculoskeletal system. Because the spine is the most frequent site of bone metastasis, imaging must be discussed in cases of cancer. Bone marrow is the main interest in imaging the metastatic process by magnetic resonance, while X-rays allow the study of cortical involvement. This article presents our experience, and a review of the literature, in an overview of the different imaging techniques-X-rays and magnetic resonance-with emphasis on the many difficulties that can be encountered in the diagnosis and monitoring of spinal metastases, allowing a management strategy for diagnosis and follow-up.

[Ankle and foot sprains: conventional radiography aspects]. / Aspects radiographiques des lésions ostéo-articulaires et ligamentaires des entorses de pied et de cheville.

Emergency departments frequently encounter pathology resulting from injury to the foot and ankle, with approximately 6000 case per day in France. In an ankle sprain, 85% of the lesions involve the lateral collateral ligament. Many other, much rarer, types of lesion with different therapeutic consequences can present, however. Interpretation of the initial conventional radiographs is vital to establishing the type lesion and to proposing adapted and rapid treatment. The objective of this article is to review the various osteoarticular and ligament injuries encountered in the foot and the ankle.

[The law of March 4, 2002: how to implement it with regards to informed consent in radiology]. / La loi du 4 mars 2002: comment l'appliquer en matière d'information des patients en radiologie.

The duty of providing information to patients makes it possible to obtain an informed consent. Information must be complete and relate to the health of the patient and not only to the risks of a medical procedure. From jurisprudence initially, and then from the law of March 4, 2002, it is a right for patients. It is the physician's burden to prove that he or she informed his patient well. This provision raises difficulties in radiology because of the particular nature of this practice. The radiologist intervenes after a fellow-physician has prescribed the examination. This relation involves three individuals: the requesting physician, the radiologist and the patient. Both physicians have a duty to provide information. As such, should consultations with radiologists prior to specific invasive procedures be obtained? This article aims at clarifying the concept of informed consent in radiology, based on the law of March 4, 2002, examples of jurisprudence, and the recent regulation specific to radiology in the decrees of March 2003.

N-butyl 2-cyanoacrylate embolization of spinal dural arteriovenous fistulae: CT evaluation, technical features, and outcome prognosis in 26 cases.

BACKGROUND AND PURPOSE: This study investigated the role of CT as an early predictor of outcome prognosis after glue embolization of spinal dural arteriovenous fistulas (SDAVF). METHODS: Over a 13-year period, 26 patients underwent glue embolization of SDAVF and were retrospectively reviewed. Immediately after embolization, each patient had CT evaluation of cast position. Mean follow-up angiography was 23.4 months (range, 1-87 months; median, 21 months). Both MR images and clinical data (e.g., gait and micturition disabilities according to the Aminoff and Logue disability scale, deep and superficial sensitivity) were analyzed, with a mean follow-up of 37.7 months (range, 12-98 months; median, 28 months). Data were tested by univariate analysis by using Fisher's exact test and the Kruskall Wallis test, depending on the order of the qualitative variables. RESULTS: Glue was found in the dura mater on CT in 19 (73%) patients. None of these patients had a recanalized fistula on angiography, and the clinical status of all of them improved. Glue was observed in or proximal to the foramen on CT in seven (27%) patients. In five of them, the fistula was recanalized within a mean period of 9 months (range, 3-24 months; median, 6 months) and their clinical status worsened. All five required surgical treatment. On angiography, the absence of fistula recanalization was observed in 21 (81%) patients and correlated with improvements in gait (P = .016), sensitivity (P = .030), and micturition (P = .080). It also correlated with a decrease in the extent of the abnormally high intramedullary T2 signal intensity (P = .002), a decrease in spinal cord diameter (P = .017), and the resolution of prominent perimedullary vessels (P < .001). The presence of glue within the dura mater on CT correlated with the absence of fistula recanalization (P = .045) and with overall improvement in clinical status, including gait and/or sensitivity and/or micturition (P = .042). CONCLUSION: CT evaluation of embolization cast position immediately after embolization may constitute an early and reliable tool for predicting permanent fistula occlusion and the prognosis for outcome.

Superselective ophthalmic artery fibrinolytic therapy for the treatment of central retinal vein occlusion.

AIM: To study the effect of superselective ophthalmic artery fibrinolysis as a treatment for central retinal vein occlusion (CRVO). METHODS: Retrospective, university based single centre study. The charts of 26 eyes of 26 patients treated were reviewed. Among the 26 patients, there were nine cases of combined artery and vein occlusion, three cases of combined cilioretinal artery and CRVO, and 14 cases of classic CRVO. Complete preoperative and postoperative ophthalmological examination and fluorescein angiography were performed in all cases. The therapeutic procedure comprised the infusion of urokinase through a microcatheter into the ostium of the ophthalmic artery, via a femoral artery approach. The main outcome measure was the improvement in visual acuity 48 hours after the procedure. RESULTS: Six eyes of six patients exhibited significant improvement in visual acuity immediately after the fibrinolysis procedure. Among them, four had a initial funduscopic appearance suggestive of combined occlusion of the central retinal artery (CRAO) and vein. For these patients, the visual benefit was maintained in the long term. Intravitreal haemorrhage occurred in two patients. There were no extraocular complications linked to the procedure. CONCLUSIONS: Selective ophthalmic artery infusion of urokinase was followed by improvement in VA in six out of 26 cases of CRVO. Eyes with combined CRAO and CRVO with recent visual loss appeared to be the most responsive. This treatment did not prevent the occurrence of ischaemia in the failure cases. The efficacy of in situ fibrinolysis for treatment of CRVO needs to be further evaluated in a controlled study.

[Endoluminal dilatations and stenosis of symptomatic vertebral arteries]. / Dilatations endo-luminales des sténoses des artères vertébrales symptomatiques.

Surgical treatment of symptomatic atherosclerotic stenosis of vertebral arteries has been proposed for many years but this technique remains quite confidential due to technical difficulties and relatively high risks. Transluminal angioplasty has been proposed and we developed a simplified technique using coronary stent placement. The aim of this study was to evaluate the feasibility and efficacy of transluminal angiography with primary stenting for proximal stenosis for vertebral arteries. Eleven patients with symptomatic atherosclerotic stenosis of vertebral arteries were treated by trans luminal angioplasty with primary stent placement. Two patients, one with stenosis of the proximal vertebral artery and one with distal stenosis of the vertebral artery where only treated by transluminal angioplasty. In all cases transluminal angioplasty and stenting were feasible with restitution ad integrum of the diameter of the artery in 98 cases and with residual moderate stenose (<20%) in 5 cases. All patients were followed for more than one year, only one patient had recurrence of symptoms, but he stopped spontaneously the anti platteless drugs. Vertebro basilar symptoms disappeared completely in 12/13 cases and were improved in 1/13 cases. No restenose of the artery was observed on control (echodoppler) excepted in one case, where a tight stenose of pre vertebral sub clavian artery developed. Transluminal angioplasty for symptomatic stenosis of vertebral artery appears as a very successful technique with a low complication rate. It should be proposed in many cases of vertebrobasilar insufficiency related with tight vertebral artery stenosis.

Selective endovascular treatment of intracranial aneurysms using micrus microcoils: preliminary results in a series of 78 patients.

PURPOSE: To determine the safety and reliability of a new platinum microcoil (Micrus), in the treatment of intracranial aneurysms. PATIENTS AND METHODS: Seventy-eight patients (28 male and 50 female patients; age range, 28-83 years; mean age, 44 years) with 80 intracranial aneurysms were treated in 10 centers in Belgium and France. All aneurysms were smaller than 15 mm. Nine aneurysms (11%) were located in the posterior circulation and 71 (89%) in the anterior. Fifty aneurysms (63%) were ruptured and 30 (37%) unruptured. Micrus microcoil is a new platinum coil. It is electrically detached with a time of detachment close to 5 seconds. RESULTS: The degree of occlusion of the aneurysm was classified as total in 49 aneurysms (61%), subtotal in 28 cases (35%) and incomplete in 3 cases (4%). Technical complications were encountered in 10 patients (13%) including parent artery occlusion and thromboembolism (4 cases), coil migration (2 cases) and non-detachment of the coil (2 cases). The immediate morbidity rate was 1.3% and mortality rate 1.3%. CONCLUSION: Micrus microcoils are effective and safe in the selective treatment of ruptured and unruptured intracranial aneurysms. Spherical microcoils are helpful to create a good basket in the aneurysmal sac at the beginning of treatment.

[Value of local ophthalmic artery fibrinolysis in severe forms of central retinal vein occlusion]. / Intérêt de la fibrinolyse locale intra-artérielle ophtalmique dans les formes sévères de l'occlusion de la veine centrale de la rétine.

PURPOSE: To assess the value of selective ophthalmic artery thrombolysis as a treatment for central retinal vein occlusion (CRVO) for which no alternative therapy is available. MATERIALS AND METHODS: Patients included in this study presented with recent severe non-ischemic CRVO. Urokinase (300,000 IU) was perfused for 40 minutes into the ophthalmic artery. Visual acuity, fundoscopy and retinal arteriovenous transit time were assessed during one year of follow-up. RESULTS: Five of the 13 patients treated experienced a marked improvement of vision (p = 0.05) and retinal perfusion within 24-48 hours, and exhibited progressive lesion regression at fundoscopy within 2-4 weeks. The clinical course of the 5 patients prior to treatment resembled that of combined central retinal artery and vein obstruction (CRAO/CRVO), which typically has a poor visual outcome. One patient relapsed 1 month after thrombolysis. No technical complications were observed. CONCLUSION: Although there was no control group, the short period between fibrinolysis and significant visual improvement combined with marked retinal perfusion improvement, suggests that local thrombolysis is beneficial for CRVO, especially recent CRAO/CRVO.