[Diffusion-weighted MR imaging of the female pelvis]. / IRM de diffusion et pelvis féminin.

Due to technical advances (parallel imaging and new phased-array coils), diffusion-weighted MR imaging can be used to image the female pelvis. Diffusion-weighted (b=1000) images are now acquired as a complement to conventional sequences (T2W, dynamic T1W images after intravenous injection of gadolinium). Diffusion weighted imaging improves the detection of small uterine tumors and the visualization of small implants of peritoneal carcinomatosis, which could play a significant role for tumor staging. It is helpful for characterization of complex ovarian tumors: the absence of hyperintensity on b=1000 diffusion-weighted images has an excellent positive predictive value for a benign etiology. It could also be helpful to characterize endometrial lesions, to differentiate between endometrial polyp and carcinoma when hysteroscopy is not possible, and to differentiate uterine fibroid from sarcoma. Finally, diffusion-weighted imaging could be helpful to assess the response of uterine tumors to therapy and could confirm a good outcome following uterine artery embolization of uterine fibroids.

[Value of diffusion-weighted imaging in the evaluation of adnexal tumors]. / Evaluation de la séquence de diffusion pour l'étude des tumeurs annexielles.

PURPOSE: To determine the value of diffusion-weighted imaging (DWI) in the evaluation of adnexal tumors, especially to distinguish between malignant and benign tumors. Materials and methods. Fifty-four patients with pelvic tumors (32 malignant and 22 benign) were referred for MRI of the pelvis. DWI was obtained in all patients. Histological correlation was available in all cases. The signal of solid and cystic tumor components was evaluated on T2W and b=1000 DWI, and ADC values were obtained. RESULTS: T2W hypointensity or absence of hyperintense signal on b=1000 DWI sequences was suggestive of a benign tumor. Hyperintensity on b=1000 DWI sequences was strongly correlated with malignant lesions. ADC values did not appear to discriminate between malignant and benign tumors. Also, the signal intensity of cystic tumor components on DWI sequences was not helpful to distinguish between malignant and benign tumor. CONCLUSION: The evaluation of solid tumor components on DWI appears to be helpful for adnexal tumor characterization.

[Non-masslike enhancement on breast MRI: interpretation pearls]. / Le rehaussement sans masse en IRM mammaire: comment j'interprète?

The MR Breast Imaging Reporting and Data System (BI-RADS) lexicon of the American College of Radiology (ACR) includes a new lesion category defined as non-masslike enhancement. The purpose of this paper is to review the definition of this new entity, illustrate the main imaging features described in the BI-RADS lexicon and to propose a diagnostic approach based on data from the literature in order to achieve diagnosis and optimal patient management.

[Perfusion and diffusion-weighted MR imaging in the early staging and the follow-up of patients with lung cancer]. / IRM de perfusion et de diffusion dans le bilan initial et le suivi des patients atteints de cancer bronchique.

Tissue characterization is a major and ultimate goal of imaging, whether morphological (Computed Tomography, Magnetic Resonance Imaging) or metabolic (PET-FDG-[18F]). Functional imaging, using the MRI, began several years ago with the perfusion of lung nodules and very recently with diffusion-weighted imaging applied to the lung cancer. The authors review the interest and the place of diffusion-weighted and perfusion MR imaging in the diagnosis, early staging and follow-up of patients with lung cancer.

[Imaging of chronic pelvis pain]. / Imagerie de la douleur pelvienne chronique.

This is a review of different diseases implicated in chronic pelvic pain (endometriosis, adenomyosis, pelvic varices, and pelvic chronic inflammatory disease) assessed by different imaging modalities (US, CT, MRI).

[How to measure breast density?]. / Comment mesurer la densité mammaire?

The relation between breast tissue density and cancer risk is well known. Early quantification techniques were based on subjective visual assessment. Quantitative techniques were then developed using planimetric measurements, surface area calculations or volumetric measurements. More recently, digital mammography should allow objective computer-based density measurements using mathematical models.

[Virtual pleuroscopy of diaphragmatic pleura: myth or reality?]. / Pleuroscopie virtuelle de la plèvre diaphragmatique: mythe ou réalité ?

PURPOSE: Evaluate the feasibility of the virtual pleuroscopy (VP) in the detection of the pleural plaques. METHOD AND MATERIALS: Twenty consecutive patients, having asbestos exposure, explored by unenhanced multidetector CT-scan (Siemens, Sensation 16). The imaging parameters were as follows: beam width, 12 mm; beam pitch, 1; and reconstruction thickness, 1mm every 0.8mm at 120 kV and 180 mA. The image display used a surface-rendering algorithm and produced perspective red-scale images with a matrix of 512 x 512. Each VP image simulated a coned-down view, with a variable cone angle to explore the diaphragmatic pleura. The camera was placed 1 to 2 cm above the diaphragmatic dome. Four views are studied by diaphragm: crâniocaudal, lateral tangential, anterior and posterior. The observed virtual pleura aspect was classified in 5 groups (gr): gr 1: Rib band, gr 2: lobulated pleural thickening, gr 3: spicular, gr 4: plaques and gr 5: nodules. The results were compared to the other MDCT images using multiplanar reformatting. RESULTS: The visualization of each diaphragm was optimal (35/40; 87.5%), limited (3/40; round atelectasis and asbestosis) or impossible (2/40; asbestosis). The classifications of the studied 38 diaphragmatic pleura were: gr 1 (n=15), gr 2 (n=5), gr 3 (n=11), gr 4 (n=7), gr 5 (n=0). The MDCT analysis showed normal pleura for both gr 1 and gr 2, a confirmed or beginning of fibrosis for gr 3 and confirmed the presence of pleural plaques on the diaphragmatic pleura in all cases of gr 4. CONCLUSION: The virtual pleuroscopy is a reality. It is a feasible technique. Other studies are necessary to confirm these preliminary results.

[Persistent sciatic artery: possible false negative imaging]. / Artère sciatique persistante: possibles faux-négatifs de l'imagerie.

Persistent sciatic artery is a rare congenital malformation due to the lack of regression of the dorsal arterial axis of the embryo that can be revealed by serious complications. We report a case of bilateral persistent sciatic artery revealed by subacute distal ischemia. This case illustrates the possibility of false negative imaging and the importance of ruling out this diagnosis in case of recurrent and apparently idiopathic distal embolism.

Fatal hemorrhagic complication following endovascular treatment of a cerebral arteriovenous malformation. Case report and review of the literature.

Evaluation of the natural history of brain Arteriovenous Malformations (AVMs) including its morbidity and mortality is a crucial point in the management of patients having a cerebral AVM. The risks associated with the AVM natural history, especially regarding the occurrence of an hemorrhage, have to be compared to the risks due to the therapeutic approach. In the literature, the risk of annual bleeding of an AVM is estimated from 2 to 4%. Morbidity from AVM rupture is estimated from 13% to 50% with a risk of mortality reported from 3 to 30%. Endovascular treatment is an efficient tool in the therapy of these lesions. However, AVM embolization remains a difficult procedure. Complications of the endovascular treatment must be evaluated in relation to the potential risk associated to the AVM natural history. After AVM endovascular treatment, morbidity with permanent neurological deficit is reported in 0.4% to 12.5% of patients and mortality in 0.4% to 7.5%. In more recent reports, after brain AVM embolization, a permanent neurological deficit is estimated to occur in 9% of patients and death in 2%. Hemorrhage appears the most frequent and serious complication in the endovascular treatment of a brain AVM. We report a case of fatal hemorrhagic complication following endovascular treatment of a cerebral AVM in a 20 year old patient. This case contributes to remind that embolization, even in specialized centers with experience in the management of this pathology, can be followed by a poor and even fatal outcome. In most cases, the treatment is performed in order to protect the patient of a potential risk. Consequently, the complication of the embolization must always be carefully considered and discussed between the medical team, the patient and its family for planning the AVM endovascular treatment.

[Imaging of salivary lithiasis]. / Imagerie des lithiases salivaires.

Lithiasis is the most common disease of salivary glands after mumps. The purpose of this review is to analyze the respective role of the different available imaging techniques for the diagnosis of lithiasis and related complications since the treatment of salivary lithiasis has evolved with the emergence of minimally invasive and non surgical techniques. In spite of its limitations, US represents an excellent first line imaging technique because it is non-invasive and widely available. Non contrast helical CT with multiplanar reconstructions seems to be the gold standard for the diagnosis of lithiasis, especially when small and poorly calcified since these may not be visible on standard radiographs. CT allows accurate characterization of the number and position of lithiasis. MR Sialography is increasingly replacing the more invasive conventional sialography for the non invasive visualization of the ductal system of major salivary glands even though conventional sialography has a higher spatial resolution.

[Value of sonography and MR imaging for the evaluation of deep pelvic endometriosis]. / Valeurs diagnostiques de l'echographie et de l'IRM pour l'evaluation de l'endométriose pelvienne profonde.

Deep pelvic endometriosis may involve the uterosacral ligaments, cul-de-sac of Douglas, vagina, rectum, and occasionally the bladder. Evaluation by physical examination is difficult, and imaging techniques are needed to evaluate the location and extent of endometriosis. In this review, we review the transvaginal and transrectal sonographic and MR imaging features suggestive of deep pelvic endometriosis and their diagnostic value.

Is there an apparent diffusion coefficient threshold in predicting tissue viability in hyperacute stroke?

BACKGROUND AND PURPOSE: Rapid and precise identification of the penumbra is important for decision-making in acute stroke. We sought to determine whether an early and moderate decrease in the apparent diffusion coefficient (ADC) may help to identify, within the diffusion/perfusion (DWI/PWI) mismatch, those areas that will eventually evolve toward infarction. METHODS: We reviewed 48 patients not treated by thrombolytics who had a DWI/PWI within 6 hours after onset, with infarct evolution documented by follow-up magnetic resonance on days 2 to 4. We calculated absolute values for ADC and the ADC ratio (ADCr) in (1) the initial DWI hypersignal; (2) the final volume of the infarct, ie, the follow-up fluid-attenuated inversion recovery abnormalities; (3) the infarct growth (IGR) area; and (4) the oligemic area (OLI) that remained viable despite initial hemodynamic disturbance. We tested the value of the ADC to predict tissue outcome by using discriminant analysis. RESULTS: ADC values were marginally but significantly decreased in the IGR area (ADC 782+/-82x10(-6) mm(2)/s, ADCr 0.94+/-0.08) compared with mirror values (P=0.01) and with OLI (ADC 823+/-41x10(-6) mm(2)/s, ADCr 0.99+/-0.07; P=0.001). Of all quantitative DWI and PWI parameters, the ADCr best discriminated between IGR and OLI (F(1,50)=13.6, cutoff=0.97, 64% sensitivity, 92% specificity) and between the final volume of infarct and OLI (F(1,83)=219, cutoff=0.91, 91% sensitivity, 100% specificity). CONCLUSIONS: A simple approach based on ADC alone may allow the identification of tissue at risk of infarction in acute-stroke patients.

Prediction of malignant middle cerebral artery infarction by diffusion-weighted imaging.

BACKGROUND AND PURPOSE: This study was designed to analyze whether early diffusion-weighted imaging (DWI) provides reliable quantitative information for the prediction of stroke patients at risk of malignant brain infarct. METHODS: We selected 28 patients with a middle cerebral artery (MCA) infarct and proven MCA or carotid T occlusion on DWI and MRI angiography performed within 14 hours after onset (mean 6.5+/-3.5 hours, median 5.2 hours). Of these, 10 patients developed malignant MCA infarct, whereas 18 did not. For the 2 groups, we compared the National Institutes of Health Stroke Scale (NIHSS) score at admission, site of arterial occlusion, standardized visual analysis of DWI abnormalities, quantitative volume measurement of DWI abnormalities (volume(DWI)), and apparent diffusion coefficient values. Univariate and multivariate discriminant analysis was used to determine the most accurate predictors of malignant MCA infarct. RESULTS: Univariate analysis showed that an admission NIHSS score >20, total versus partial MCA infarct, and volume(DWI) >145 cm(3) were highly significant predictors of malignant infarct. The best predictor was volume(DWI) >145 cm(3), which achieved 100% sensitivity and 94% specificity. Prediction was further improved by bivariate models combining volume(DWI) and apparent diffusion coefficient measurements, which reached 100% sensitivity and specificity in this series of patients. CONCLUSIONS: Quantitative measurement of infarct volume on DWI is an accurate method for the prediction of malignant MCA infarct in patients with persistent arterial occlusion imaged within 14 hours of onset. This may be of importance for early management of severe stroke patients.

Striatopallidal and thalamic dystonia. A magnetic resonance imaging anatomoclinical study.

OBJECTIVE: To determine which brain structures are involved in symptomatic unilateral dystonia caused by localized cerebral infarction. DESIGN: Three-dimensional T1-weighted magnetic resonance imaging sequence and stereotactic analysis were used to analyze the topography of the lesions. Stereotactic localization of thalamic lesions was conducted according to the atlas of Hassler with a Voxtool software (Advantage Windows Workstation, General Electric, Milwaukee, Wis) workstation system. PATIENTS: Eight patients with hemidystonia, segmental dystonia, or focal dystonia were selected from among 51 consecutive patients (between January 1988 and May 1993) with symptomatic unilateral dystonia. RESULTS: Patients had dystonic spasms (n=4) or myoclonic dystonia (n=4). Lesions associated with dystonic spasms were located in the striatopallidal complex, and those with myoclonic dystonia were in the thalamus contralateral to the dystonia. Lesions of the striatopallidal complex involved the putamen posterior to the anterior commissure in all patients and extended variably into the dorsolateral part of the caudate nucleus, the posterior limb of the internal capsule, or the lateral segment of the globus pallidus. These lesions were centered in the "sensorimotor" part of the striatopallidal complex, with a trend toward a somatotopical distribution. Lesions of the thalamus were located in the ventral intermediate and ventral caudal nuclei, while the ventral oral anterior and posterior nuclei (which receive pallidal efferents) were largely spared. CONCLUSIONS: These results suggest that striatopallidal and thalamic dystonia may have different pathophysiologic bases.

Dopaminergic dysfunction in midbrain dystonia: anatomoclinical study using 3-dimensional magnetic resonance imaging and fluorodopa F 18 positron emission tomography.

OBJECTIVE: To determine the role of damage to neuronal systems, especially the dopaminergic system, in patients with symptomatic dystonia and mesencephalic lesions. DESIGN: Stereotaxic magnetic resonance imaging analysis and positron emission tomography after the administration of fluorodopa F 18. PATIENTS: Of a group of 48 patients with unilateral dystonia following a stroke, 7 patients with a well-defined midbrain lesion were selected. RESULTS: All patients had unilateral dystonic posture of an upper extremity and cerebellar dysmetria or hypotonia. Cerebellar tremor was present in 1 patient. Two patients had resting and postural tremor, which showed a marked improvement with treatment with levodopa. In patients with dystonia only, dopaminergic lesions were mostly confined to the ventromesial mesencephalon and red nucleus area, including the substantia nigra and nigrostriatal and cerebellothalamic fibers. Dystonia was severe and did not resolve with time in patients with lesions involving the nigrostriatal pathway, and the degree of dopaminergic denervation revealed by positron emission tomography was correlated with the severity of dystonia. In patients with resting and postural tremor, lesions of the dopaminergic structures were larger and located more laterally and dorsally in the pars compacta, the perirubral and retrorubral areas, and extending to the central tegmental tract. CONCLUSIONS: Dopaminergic dysfunction plays a role in the occurrence and severity of midbrain dystonia, and additional lesions to dopaminergic neurons in the perirubral and retrorubral areas result in tremor that responds to levodopa treatment.

Functional MR evaluation of temporal and frontal language dominance compared with the Wada test.

OBJECTIVE: To evaluate the reliability of temporal and frontal functional MRI (fMRI) activation for the assessment of language dominance, as compared with the Wada test. PATIENTS AND METHODS: Ten patients with temporal lobe epilepsy were studied using blood oxygen level dependent fMRI and echoplanar imaging (1.5-T). Three tasks were used: semantic verbal fluency, covert sentence repetition, and story listening. Data were analyzed using pixel by pixel autocorrelation and cross-correlation. fMRI laterality indices were defined for several regions of interest as the ratio (L - R)/(L + R), L being the number of activated voxels in the left hemisphere and R in the right hemisphere. Wada laterality indices were defined as the difference in the percentages of errors in language tests between left and right carotid injections. RESULTS: Semantic verbal fluency: The asymmetry of frontal activation was correlated with Wada laterality indices. The strongest correlation was observed in the precentral/middle frontal gyrus/inferior frontal sulcus area. Story listening: The asymmetry of frontal, but not temporal, activation was correlated with Wada laterality indices. Covert sentence repetition: No correlation was observed. CONCLUSIONS: There was a good congruence between hemispheric dominance for language as assessed with the Wada test and fMRI laterality indices in the frontal but not in the temporal lobes. The story listening and the covert sentence repetition tasks increased the sensitivity of detection of posterior language sites that may be useful for brain lesion surgery.

Long-term survival after gene therapy for a recurrent glioblastoma.

A patient presenting with a recurrent glioblastoma (GBM) survived 3 years after suicide gene therapy and finally died of a disseminated breast cancer with no indication of tumor recurrence on MRI. Postmortem analysis showed no evidence of recurrence of the GBM, neither near the initial tumor localization nor in any other area of the brain. Such an evolution is unusual in the course of this disease and may suggest in this particular case a cure of the GBM.

Pallidal stimulation for Parkinson's disease. Two targets?

There has been renewed interest in functional surgery as treatment for Parkinson's disease (PD). Although pallidotomy and chronic pallidal stimulation are highly effective in suppressing levodopa-induced dyskinesia (LID), both methods also seem to be effective in reducing parkinsonian disability. However, the simultaneous improvement of LID and motor signs is hard to explain with the classic model of basal ganglia circuitry. Taking advantage of the fact that deep brain stimulation is reversible and that implanted electrodes contain four discrete stimulation sites, we investigated the effect of stimulation on different sites of the globus pallidus (GP) in five PD patients. Stimulation in the dorsal GP (upper contact) significantly improved gait, akinesia, and rigidity and could induce dyskinesia when patients were in the "off" state. In contrast, stimulation in the posteroventral GP (lower contact) significantly worsened gait and akinesia, although the reduction in rigidity remained. For patients in the "on" state, stimulation in the posteroventral GP dramatically reduced LID but, as in the "off" state, worsened gait and akinesia, thus canceling out the antiparkinsonian effect of levodopa. Our results indicate that stimulation had a striking different effect on parkinsonism and dyskinesia when applied at two different loci of the GP and that stimulation applied in the posteroventral GP produced opposite effects on rigidity and on akinesia. We conclude that parkinsonian signs and LID are a reflection of at least two different anatomofunctional systems within the GP and that this functional organization of the GP needs to be considered when determining the optimal target for surgical treatment of PD.

Clinical characteristics and topography of lesions in movement disorders due to thalamic lesions.

OBJECTIVE: To determine which thalamic subnuclei are involved in symptomatic unilateral movement disorders due to localized thalamic infarction, and the clinical characteristics of these abnormal movements. METHODS: The authors studied 22 patients with thalamic infarcts for their clinical presentation and the topography of the lesions, using three-dimensional T1-weighted MRI sequencing and stereotaxic analysis of the lesions. RESULTS: Patients were divided into four groups: 1) absence of abnormal involuntary movements (AIM) (nine patients); 2) isolated dystonic posture (two patients); 3) myoclonic dystonia (five patients); and 4) tremor or myoclonus (six patients). In patients with AIM, thalamic lesions were contralateral to the abnormal movements, involving the thalamogeniculate territory, centered on the ventral intermediate (Vim) and ventral caudal (Vc) nuclei. No significant difference in the volumes or center of mass of the lesions was found between patients with tremor and myoclonus and patients with dystonia, although the central nucleus and the internal part of the Vim nucleus were more consistently damaged in dystonic patients. CONCLUSION: Movement disorders related to thalamic lesions included: 1) myoclonic dystonia with predominating myoclonus and "thalamic" hand associating dystonic posture and slow, pseudo-athetoid movements, both related to lesions in the Vim and Vc nuclei of the thalamus; and 2) postural and action tremor, also related to lesions in the Vim, similar to tremor associated with midbrain lesions, as a result of abnormal functioning of the cerebello-thalamic pathways.

Role of the supplementary motor area in motor deficit following medial frontal lobe surgery.

OBJECTIVE: Patients undergoing surgical resection of medial frontal lesions may present a transient postoperative deficit that remains largely unpredictable. The authors studied the role of the supplementary motor area (SMA) in the occurrence of this deficit using fMRI. METHODS: Twenty-three patients underwent a preoperative fMRI before resection of medial frontal lesions. Tasks included self-paced flexion/extension of the left and right hand, successively. Preoperative fMRI data were compared with postoperative MRI data and with neurologic outcome. RESULTS: Following surgery, 11 patients had a motor deficit from which all patients recovered within a few weeks or months. The deficit was similar across patients, consisting of a global reduction in spontaneous movements contralateral to the operated side with variable severity. SMA activation was observed in all patients. The deficit was observed when the area activated in the posterior part of the SMA (SMA proper) was resected. CONCLUSIONS: fMRI is able to identify the area at risk in the SMA proper whose resection is highly related to the occurrence of the motor deficit. The clinical characteristics of this deficit support the role of the SMA proper in the initiation and execution of the movement.