[Correlation between cranial vault size and brain size over time: preliminary MRI evaluation]. / Evolution comparative de la voûte crânienne et du parenchyme cérébral avec l'âge: étude préliminaire en IRM.

OBJECTIVES: To correlate changes of cranial vault measurements of an adult population during the aging process with brain size using the maximum width of the third ventricle in the axial AC-PC plane. MATERIALS AND METHODS: Prospective study of 126 adult subjects (range: 20 to 80 years) with normal brain MRI and without history of neuropsychiatric disorder. MEASUREMENTS INCLUDED: Cranial vault (Maximum length: Glabella-Opisthocranion, Maximum width: euryon-euryon, and maximum height: Basion-Vertex) measurements and maximum width of the third ventricle in the A C-PC plane. RESULTS: Vault measurements (length, width, high) were similar for every age group, irrespective of gender. The variability of cranial vault measurements between individuals was low (<1 cm). Cranial vault measurements were larger for men, but this was not significant when adjusted for body height Comparatively, a gradual widening of the third ventricle, with an exponential behavior, was observed with advancing age. CONCLUSION: Our results indicate that cranial vault measurements are stable over time (between 20-80 years) comparatively to brain atrophy with advancing age. The low variability of cranial vault measurements and their stability over time should be taken into account during segmentation and normalization of brain parenchymal structures.

Effect of stimulus frequency and stimulation site on the N1m response of the human auditory cortex.

The aim of the present study was to investigate the functional organization of the auditory cortex for pure tones of 1, 2, 4, 6, 8 and 12 kHz. Ten subjects were tested with a whole-head magnetometer (151 channels). The location, latency and amplitude of the generators of the N1m (the main component of the response, peaking approximately at 100 ms) were explored simultaneously in the right and left hemispheres under monaural stimulation. Our results revealed that tonotopy is a rather complex functional organization of the auditory cortex. From 1 to 12 kHz, tonotopic maps were found for contralateral as well as for ipsilateral stimulation: N1m generators were found to be tonotopically organized mainly in an anterior-posterior direction in both hemispheres, whatever the stimulated ear, but also in an inferior-superior direction in the right hemisphere. Furthermore, latencies were longer in the left than in the right hemisphere. Two different representations of spectral distribution were found in the right auditory cortex: one for ipsilateral and one for contralateral stimulation.

Better results with rhenium-186 radiosynoviorthesis than with cortivazol in rheumatoid arthritis (RA): a two-year follow-up randomized controlled multicentre study.

OBJECTIVE: The aim of this international multicentric randomized phase 3 clinical trial was to compare prospectively radiosynoviorthesis (RSO) with rhenium-186-sulfide (186Re) to intra-articular corticotherapy in patients with clinically controlled rheumatoid arthritis (RA), but in whom one or a few medium-sized joints remained painful or swollen. METHODS: One hundred and twenty-nine joints in 81 RA patients [stratified into 2 groups: wrists (group 1, n = 78) and all the other joints (group 2, n = 51, including 18 elbows, 21 shoulders and 12 ankles)] were randomized to receive intra-articular injections of either 186Re-sulfide (64 +/- 4 MBq), or cortivazol (Altim) 3.75 mg. Clinical assessment was performed before and then at 3, 6, 12, 18 and 24 months after local therapy, using a 4-step verbal rating scale (VRS) and a 100 mm visual analog scale for pain, a 4-step VRS for joint swelling and mobility and a 2-step VRS for the radiological stage. The Mantel-Haenszel test was used for qualitative variables, analysis of variance (ANOVA) for quantitative pain analysis and Kaplan-Meyer survival test for relapse analysis. RESULTS: 186Re was observed to be statistically superior to cortivazol at 18 and 24 months while no statistical difference was seen for any criterion at 3, 6 and 12 months post injection. At 24 months, the difference in favor of 186Re was significant for pain (p = 0.024), joint swelling (p = 0.01), mobility (p = 0.05, non-wrists only), pain and swelling (p = 0.03) and pain or swelling (p = 0.02). "Survival" studies (Kaplan-Meyer) demonstrated a greater relative risk of relapse in corticoid treated joints, but only from the second year of follow-up. No serious side effect was observed in any patient, with only light and transient local pain and/or swelling occurring in 24% of cases, regardless of the treatment used. CONCLUSION: 186Re-sulfide and cortivazol had similar efficacy up to 12 months post-injection, but 186Re became clearly more effective at 18 and 24 months, for all criteria monitored and for RA outcome. Therefore, 186Re RSO can be recommended for routine clinical use.

169Erbium-citrate synoviorthesis after failure of local corticosteroid injections to treat rheumatoid arthritis-affected finger joints.

OBJECTIVES: Intra-articular injection of 169Erbium-citrate (169Er-citrate; radiosynoviorthesis or radiosynovectomy) is an effective local treatment of rheumatic joint diseases. However, its efficacy in corticosteroid-resistant rheumatoid arthritis-affected joints has not been clearly demonstrated. METHODS: A double-blind, randomised, placebo-controlled, international multicentre study was conducted in patients with rheumatoid arthritis with recent (< or = 24 months) ineffective corticosteroid injection(s) into their finger joint(s). Eighty-five finger joints of 44 patients were randomised to receive a single injection of placebo (NaCl 0.9%) or 169Er-citrate. Results of evaluation 6 months later were available for 82 joints (46 metacarpophalangeal and 36 proximal interphalangeal joints) of 42 patients: 39 169Er-citrate-injected joints and 43 placebo-injected joints. Efficacy was assessed using a rating scale for joint pain, swelling and mobility. RESULTS: Intent-to-treat analysis of the results of the 82 joints showed a significant effect of 169Er-citrate compared to placebo for the principal criteria decreased pain or swelling (95 vs 79%; p = 0.038) and decreased pain and swelling (79 vs 47%; p = 0.0024) and for the secondary criteria decreased pain (92 vs 72%; p = 0.017), decreased swelling (82 vs 53%; p = 0.0065) and increased mobility (64 vs 42%; p = 0.036). Per-protocol analysis, excluding 18 joints of patients who markedly changed their usual systemic treatment for arthritis, gave similar percentages of improvement but statistical significance was lower owing the reduced power of the statistical tests. CONCLUSION: These results confirm the clinical efficacy of 169Er-citrate synoviorthesis of rheumatoid arthritis-diseased finger joints after recent failure of intra-articular corticotherapy.

Regional differences and metabolic changes in normal aging of the human brain: proton MR spectroscopic imaging study.

BACKGROUND AND PURPOSE: Aging is recognized to originate from a diversity of mechanisms that blur the limits between normal and pathologic processes. The purpose of this study was to determine the early effect of normal aging on the regional distribution of brain metabolite concentrations, including N-acetylaspartate (NAA), a major neuronal marker, choline (Cho), and creatine (Cr). METHODS: Thirty-two healthy participants, ages 21 to 61 years, were examined by proton MR spectroscopic (1H MRS) imaging. 1H MRS imaging acquisitions were performed in two brain locations: the centrum semiovale and the temporal lobe. Thirty voxels were selected in four cerebral regions, cortical, semioval, temporal, and hippocampal, and 1H MR spectra were processed to determine the metabolite ratios. RESULTS: With advancing age of the participants, the ratios of %NAA, NAA:Cho, and NAA:Cr were significantly decreased, whereas the ratios of %Cho and %Cr were significantly increased in the cortical, semioval, and temporal regions. On the basis of the significant metabolic difference determined by cluster analysis, two groups of 16 participants with ages ranging from 21 to 39 years (younger group) and 40 to 61 years (older group) were compared. Repeated measures analysis of variance tests, with multiple comparison procedures between the two age groups and among the four brain region groups, showed significant decreases of the %NAA, NAA:Cho, and NAA:Cr ratios in the semioval and temporal regions of the older group compared with the younger group. When compared with other cerebral regions, %NAA and %Cho ratios were significantly decreased in the hippocampal and cortical regions, respectively. CONCLUSION: These metabolic changes suggest that brain aging is characterized by a reduction in neuronal viability or function associated with an accelerated membrane degradation and/or an increase in glial cell numbers.

A constrained Gauss-Seidel method for correction of point spread function effect in MR spectroscopic imaging.

Magnetic resonance spectroscopic imaging is limited by a low signal-to-noise ratio, so a compromise between spatial resolution and examination time is needed in clinical application. The reconstruction of truncated signal introduces a Point Spread Function that considerably affects the spatial resolution. In order to reduce spatial contamination, three methods, applied after Fourier transform image reconstruction, based on deconvolution or iterative techniques are tested to decrease Point Spread Function contamination. A Gauss-Seidel (GS) algorithm is used for iterative techniques with and without a non-negative constraint (GS+). Convergence and noise dependence studies of the GS algorithm have been done. The linear property of contamination was validated on a point sample phantom. A significant decrease of contamination without broadening the spatial resolution was obtained with GS+ method compared to a conventional apodization. This post-processing method can provide a contrast enhancement of clinical spectroscopic images without changes in acquisition time.

A model of the dual effect of gadopentetate dimeglumine on dynamic brain MR images.

An optimized dynamic gradient echo sequence with two echoes is used to obtain data that can be analyzed with indicator dilution theory as well as with pharmacokinetic theory. Taking advantage of the simultaneity of T(*)(2) and T(1) information, both theories can be employed and merged to interpret consistently the observed effects of the redistribution of a contrast agent (gadopentetate dimeglumine) into the tissue from first pass onward. The regional cerebral blood volume (rCBV) and the exchange rate of the contrast agent between the vascular and the interstitial space through the blood-brain barrier are analyzed for each pixel in a two-step algorithm. Two values for rCBV are obtained with different weighting for the microvascular fraction of the blood volume. Because the analysis, called PELEAKAN, is capable of separating effects related to perfusion (through intravascular blood volume) and to leakage in places where the blood-brain barrier is damaged, it is an appropriate tool for evaluating these parameters in brain tumors, and we show clinical examples of this analysis in brain tumor patients.

Phosphorus and proton magnetic resonance spectroscopy in episodic ataxia type 2.

Localized phosphorus (31P) and proton (1H) magnetic resonance spectroscopy was performed in the cerebellum and the occipital lobe of 6 patients with episodic ataxia type 2. From use of 31P magnetic resonance spectroscopy, untreated patients showed decreased high-energy phosphate ratios in the cerebrum, and increased pH in the cerebellum and cerebrum, which normalized under acetazolamide. 1H magnetic resonance spectra demonstrated high lactate peaks in 3 of the 6 patients. These metabolic alterations, probably induced by the calcium channelopathy, may characterize episodic ataxia type 2.

Assessment of osteosarcoma response to neoadjuvant chemotherapy: comparative usefulness of dynamic gadolinium-enhanced spin-echo magnetic resonance imaging and technetium-99m skeletal angioscintigraphy.

The aim of this work was to study and compare the usefulness of dynamic contrast-enhanced spin-echo MR imaging with high temporal resolution hydroxymethylene diphosphonate technetium-99 m skeletal angioscintigraphy in predicting the osteosarcoma histological response to neoadjuvant chemotherapy. Twelve patients with resectable osteosarcoma were prospectively monitored with dynamic MR imaging and skeletal scintigraphy before start of neoadjuvant chemotherapy, after two cycles of therapy and before surgery. Neoplasm signal intensity and activity intensity were plotted against time, and slopes were calculated for percentage increase over baseline values in the first minute. Stability and increase in slope values during or after chemotherapy were defined as a "radiological non-response". Changes in slopes were compared with the "histological response" (Huvos grading). At midpoint of the chemotherapy, these two imaging modalities failed in predicting final histological response. After the completion of the chemotherapy, these imaging modalities allowed the prediction of histological response with the same accuracy (91 %). In this series, dynamic MR imaging and technetium skeletal scintigraphy provide similar results regarding the prediction of final histological response during neoadjuvant chemotherapy; these results cannot be used to modify the therapeutic protocol at midpoint of chemotherapy; these imaging tools predict accurately the histological response at the end of chemotherapy. These latter results may permit anticipation of the adjuvant chemotherapy strategy during decalcification procedures in resected osteosarcoma and thus to monitor chemotherapy in non-surgical osteosarcoma.

Regional cerebral blood flow determination using 133Xe and a standard rotating gamma-camera.

While most of the methods for quantitative regional cerebral blood flow (rCBF) determination in man requires expensive fast devices, a method is proposed using single photon emission computed tomography with a conventional rotating gamma camera and 133Xe inhalation. It is tested using a computer simulation of a cerebral exam and a simplified CBF map as a model. The results obtained show that this method is relevant and can be tested in clinical studies.

A metabolism study of human masseter muscle by 31P magnetic resonance spectroscopy during long periods of exercise and recovery.

The metabolism of the human masseter muscle was investigated using phosphorus (31p) magnetic resonance spectroscopy (MRS) during long periods of exercise and recovery. Eleven subjects aged 19 to 28 yr were examined by 31p MRS during four consecutive periods of 13 min each: rest, exercise, recovery 1 and 2. For each subject, a biting force equal to 20% of maximum voluntary biting force was applied and controlled during the exercise period to produce maximum fatigue. 31p MR spectra were localized from a 24 cm3 volume of interest using an image selected in vivo spectroscopy (ISIS) sequence and a 6 cm diameter surface coil placed on the left masseter. Compared to the resting level, the phosphocreatine (PCr) content decreased by 26% during exercise, while the inorganic phosphate (Pi) concentration increased by 65%. During the two recovery periods, the Pi content remained decreased compared with the resting level by 36% and 30%, respectively. The Pi/PCr ratio was increased from 0.30+/-0.04 at rest to 0.63+/-0.13 during exercise while the adenosine triphosphate (ATP)/Pi ratio was decreased. The pH decreased from 7.02+/-0.03 to 6.93+/-0.04 during exercise and returned to control level (7.09+/-0.08) only during the second recovery period. These results suggest that the masseter muscle is characterized by high ATP turnover and, therefore, high oxidative phosphorylative activity in agreement with its constitution of predominantly fatigue resistant type I fibers.

[Anatomical study with MRI of a small muscle: the masseter]. / Etude anatomique par IRM d'un muscle de petite dimension: le masséter.

Magnetic resonance imaging (MRI) provides functional information in an anatomic presentation allowing to distinguish soft tissues with high sensitivity. The goal of this study was to investigate the normal anatomy of the major masticatory muscle, the masseter, both at rest or during contraction by using three dimensional (3D) MRI. Eighteen subjects aged from 19 to 28 years, all in good health, were studied. Several experiments were first realized on phantoms to test the 3D-MRI technique. After reconstruction and segmentation processing, 3D acquisition, enabled obtaining data on the masseter anatomy. The normal anatomical position of the masseter was reported to the skin plan as the mean internal distance (7.9 +/- 0.42 mm) and external distance (15.2 +/- 0.41 mm). While there was no difference between internal distance, for sex or side, the external distance was significantly (p = 0.02) shorter in male (7.7 +/- 0.5 mm) than in female (8.8 +/- 0.4 mm) for both sides. The mean volume for all subjects and both sides (20.3 +/- 1.1 cm3) did not change significantly between rest and exercise. The masseter volume was significantly (p < 0.00001) greater in male (24.2 +/- 2.0 cm3) than in female (16.4 +/- 3.6 cm3) groups. These physiological references may be useful for further MRI investigations of masticatory system pathologies.

Bone marrow metastases in small cell lung cancer: detection with magnetic resonance imaging and monoclonal antibodies.

The detection of bone marrow involvement might be of prognostic value and may influence therapeutic decisions in small cell lung cancer. By unilateral bone marrow aspiration and biopsy, evidence of bone marrow metastases is seen in 15-30% of patients with this disease. Since magnetic resonance imaging of the lower body and immunostaining with monoclonal antibodies have recently been shown to be very sensitive detection methods, we investigated the value of these two techniques in detecting bone marrow involvement in 35 consecutive patients with small cell lung cancer. The results were compared to those obtained with conventional cytohistological analysis. In all cases when cytology and/or bone marrow biopsy were positive, monoclonal antibodies immunostaining and magnetic resonance imaging also detected malignant cells. Furthermore, evidence of bone marrow involvement was shown with magnetic resonance imaging and/or immunostaining in 10 of 26 cases (38%) where routine procedures were unable to detect malignant cells. In one of these 26 patients, magnetic resonance imaging and immunostaining provided the only evidence of metastatic disease. These data suggest that the rate of bone marrow metastases is underestimated by routine procedures. Further investigation is needed to determine whether or not these new non-invasive methods have prognostic value or affect therapeutic choices in small cell lung carcinoma.

[Flow analysis by phase modulation of NMR signals]. / Analyse des écoulements fluides par modulation de phase des signaux RMN.

Time modulated field-gradient-sequences able to selectively phase encode spatial location or flow velocity in NMR signals are described. The specific phase modulation discriminates between stationary and mobile protons. The method is presented in the one dimensional case and has the following advantages: it is sensitive to flow direction and unaffected by the relaxation times.

Spatial or flow velocity phase encoding gradients in NMR imaging.

We describe time modulated field gradient sequences able to selectively phase encode spatial location or flow velocity in NMR Signals. Two flow conditions are presented: constant flow velocity and simple harmonic flow superposed on steady flow. In each case we show that specific modulated gradients are available in order to discriminate between stationary and mobile protons. The methods are presented in the one dimensional case. The advantages of the phase modulation for flow analysis are the following: the method is sensitive to flow direction, unaffected by the T2, and the stationary and flow parameters are quantifiable factors.

[Cardiac involvement in sarcoidosis. Results of a prospective study of 37 cases]. / L'atteinte cardiaque au cours de la sarcoïdose. Résultats d'une étude prospective sur 37 cas.

An evaluation of the incidence of cardiac lesions in sarcoidosis was conducted in a group of patients with progressive pulmonary signs of the disease. Five non-invasive methods: echocardiogram, ECG, Holter, effort ECG, and thallium scintigraphy were employed on a routine basis; 31 patients were investigated by all procedures, scintigraphy being performed in all 37 cases. First degree auriculoventricular block was detected in only one case, this being compatible with cardiac sarcoidosis, though the possibility of a congenital lesion could not be excluded. The ECG remains an essential investigation among those employed, other examinations not supplying superior data. Scintigraphy appears to be of positive value, as faults in localized uptake were demonstrated in 17 p. cent of cases, these possibly corresponding to intramyocardial granulomas.